CODATA Recommended Values of the Fundamental Physical Constants:
2006
∗
Peter J. Mohr
â€
, Barry N. Taylor
‡
, and David B. Newell
§
,
National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8420, USA
(Dated: December 28, 2007)
This paper gives the 2006 self-consistent set of values of the basic constants and conversion factors
of physics and chemistry recommended by the Committee on Data for Science and Technology
(CODATA) for international use. Further, it describes in detail the adjustment of the values of the
constants, including the selection of the final set of input data based on the results of least-squares
analyses. The 2006 adjustment takes into account the data considered in the 2002 adjustment
as well as the data that became available between 31 December 2002, the closing date of that
adjustment, and 31 December 2006, the closing date of the new adjustment. The new data have
led to a significant reduction in the uncertainties of many recommended values. The 2006 set
replaces the previously recommended 2002 CODATA set and may also be found on the World
Wide Web at physics.nist.gov/constants.
Contents
Glossary
2
I. Introduction
4
A. Background
4
B. Time variation of the constants
5
C. Outline of paper
5
II. Special quantities and units
6
III. Relative atomic masses
6
A. Relative atomic masses of atoms
6
B. Relative atomic masses of ions and nuclei
7
∗
This report was prepared by the authors under the auspices of the
CODATA Task Group on Fundamental Constants. The members
of the task group are:
F. Cabiati, Istituto Nazionale di Ricerca Metrologica, Italy
K. Fujii, National Metrology Institute of Japan, Japan
S. G. Karshenboim, D. I. Mendeleyev All-Russian Research Insti-
tute for Metrology, Russian Federation
I. Lindgren, Chalmers University of Technology and G¨
oteborg Uni-
versity, Sweden
B. A. Mamyrin (deceased), A. F. Ioffe Physical-Technical Institute,
Russian Federation
W. Martienssen, Johann Wolfgang Goethe-Universit¨
at, Germany
P. J. Mohr, National Institute of Standards and Technology, United
States of America
D. B. Newell, National Institute of Standards and Technology,
United States of America
F. Nez, Laboratoire Kastler-Brossel, France
B. W. Petley, National Physical Laboratory, United Kingdom
T. J. Quinn, Bureau international des poids et mesures
B. N. Taylor, National Institute of Standards and Technology,
United States of America
W. W¨
oger, Physikalisch-Technische Bundesanstalt, Germany
B. M. Wood, National Research Council, Canada
Z. Zhang, National Institute of Metrology, China (People’s Repub-
lic of)
â€
Electronic address: mohr@nist.gov
‡
Electronic address: barry.taylor@nist.gov
§
Electronic address: dnewell@nist.gov
C. Cyclotron resonance measurement of the electron
relative atomic mass
A
r
(e)
8
IV. Atomic transition frequencies
8
A. Hydrogen and deuterium transition frequencies, the
Rydberg constant
R
∞
, and the proton and deuteron
charge radii
R
p
, R
d
8
1. Theory relevant to the Rydberg constant
9
2. Experiments on hydrogen and deuterium
16
3. Nuclear radii
16
B. Antiprotonic helium transition frequencies and
A
r
(e)
17
1. Theory relevant to antiprotonic helium
17
2. Experiments on antiprotonic helium
18
3. Values of
A
r
(e) inferred from antiprotonic helium 20
C. Hyperfine structure and fine structure
20
1. Hyperfine structure
20
2. Fine structure
20
V. Magnetic moment anomalies and
g
-factors
21
A. Electron magnetic moment anomaly
a
e
and the
fine-structure constant
α
22
1. Theory of
a
e
22
2. Measurements of
a
e
23
3. Values of
α
inferred from
a
e
24
B. Muon magnetic moment anomaly
a
µ
24
1. Theory of
a
µ
24
2. Measurement of
a
µ
: Brookhaven.
26
C. Bound electron
g
-factor in
12
C
5+
and in
16
O
7+
and
A
r
(e)
27
1. Theory of the bound electron
g
-factor
28
2. Measurements of
g
e
(
12
C
5+
) and
g
e
(
16
O
7+
).
31
VI. Magnetic moment ratios and the muon-electron
mass ratio
32
A. Magnetic moment ratios
32
1. Theoretical ratios of atomic bound-particle to
free-particle
g
-factors
33
2. Ratio measurements
33
B. Muonium transition frequencies, the muon-proton
magnetic moment ratio
µ
µ
/µ
p
, and muon-electron
mass ratio
m
µ
/m
e
36
1. Theory of the muonium ground-state hyperfine
splitting
36
2. Measurements of muonium transition frequencies
and values of
µ
µ
/µ
p
and
m
µ
/m
e
38
2
VII. Electrical measurements
39
A. Shielded gyromagnetic ratios
γ
′
, the fine-structure
constant
α
, and the Planck constant
h
39
1. Low-field measurements
40
2. High-field measurements
40
B. von Klitzing constant
R
K
and
α
41
1. NIST: Calculable capacitor
41
2. NMI: Calculable capacitor
41
3. NPL: Calculable capacitor
42
4. NIM: Calculable capacitor
42
5. LNE: Calculable capacitor
42
C. Josephson constant
K
J
and
h
42
1. NMI: Hg electrometer
43
2. PTB: Capacitor voltage balance
43
D. Product
K
2
J
R
K
and
h
43
1. NPL: Watt balance
43
2. NIST: Watt balance
43
3. Other values
45
4. Inferred value of
K
J
45
E. Faraday constant
F
and
h
46
1. NIST: Ag coulometer
46
VIII. Measurements involving silicon crystals
46
A.
{
220
}
lattice spacing of silicon
d
220
46
1. X-ray/optical interferometer measurements of
d
220
(
X
)
47
2.
d
220
difference measurements
49
B. Molar volume of silicon
V
m
(Si)
and the Avogadro
constant
N
A
50
C. Gamma-ray determination of the neutron relative
atomic mass
A
r
(n)
51
D. Quotient of Planck constant and particle mass
h/m
(
X
)
and
α
52
1. Quotient
h/m
n
52
2. Quotient
h/m
(
133
Cs)
53
3. Quotient
h/m
(
87
Rb)
54
IX. Thermal physical quantities
55
A. Molar gas constant
R
55
1. NIST: speed of sound in argon
55
2. NPL: speed of sound in argon
55
3. Other values
55
B. Boltzmann constant
k
55
C. Stefan-Boltzmann constant
σ
56
X. Newtonian constant of gravitation
G
56
A. Updated values
57
1. Huazhong University of Science and Technology
57
2. University of Zurich
58
B. Determination of 2006 recommended value of
G
58
C. Prospective values
59
XI. X-ray and electroweak quantities
59
A. X-ray units
59
B. Particle Data Group input
60
XII. Analysis of Data
60
A. Comparison of data
64
B. Multivariate analysis of data
69
1. Summary of adjustments
70
2. Test of the Josephson and quantum Hall effect
relations
71
XIII. The 2006 CODATA recommended values
83
A. Calculational details
83
B. Tables of values
83
XIV. Summary and Conclusion
84
A. Comparison of 2006 and 2002 CODATA
recommended values
84
B. Some implications of the 2006 CODATA
recommended values and adjustment for physics and
metrology
85
C. Outlook and suggestions for future work
86
XV. Acknowledgments
87
References
87
Glossary
AMDC
Atomic Mass Data Center, Centre de Spec-
trom´etrie Nucl´eaire et de Spectrom´etrie de Masse
(CSNSM), Orsay, France
AME2003
2003 atomic mass evaluation of the AMDC
A
r
(
X
)
Relative atomic mass of
X
:
A
r
(
X
) =
m
(
X
)
/m
u
A
90
Conventional unit of electric current:
A
90
=
V
90
/
Ω
90
Ëš
A
∗
Ëš
Angstr¨
om-star:
λ
(WK
α
1
) = 0
.
209 010 0 Ëš
A
∗
a
e
Electron magnetic moment anomaly:
a
e
= (
|
g
e
| −
2)/2
a
µ
Muon magnetic moment anomaly:
a
µ
= (
|
g
µ
| −
2)/2
BIPM
International Bureau of Weights and Measures,
S`evres, France
BNL
Brookhaven National Laboratory, Upton, New
York, USA
CERN
European Organization for Nuclear Research,
Geneva, Switzerland
CIPM
International
Committee
for
Weights
and
Measures
CODATA
Committee on Data for Science and Technology
of the International Council for Science
CP T
Combined charge conjugation, parity inversion,
and time reversal
c
Speed of light in vacuum
cw
Continuous wave
d
Deuteron (nucleus of deuterium D, or
2
H)
d
220
{
220
}
lattice spacing of an ideal crystal of natu-
rally occurring silicon
d
220
(
X
)
{
220
}
lattice spacing of crystal
X
of naturally oc-
curring silicon
E
b
Binding energy
e
Symbol for either member of the electron-positron
pair; when necessary, e
−
or e
+
is used to indicate
the electron or positron
e
Elementary charge: absolute value of the charge
of the electron
F
Faraday constant:
F
=
N
A
e
FCDC
Fundamental Constants Data Center, NIST, USA
FSU
Friedrich-Schiller University, Jena, Germany
F
90
F
90
= (
F/A
90
) A
G
Newtonian constant of gravitation
g
Local acceleration of free fall
g
d
Deuteron
g
-factor:
g
d
=
µ
d
/µ
N
g
e
Electron
g
-factor:
g
e
= 2
µ
e
/µ
B
g
p
Proton
g
-factor:
g
p
= 2
µ
p
/µ
N
g
′
p
Shielded proton
g
-factor:
g
′
p
= 2
µ
′
p
/µ
N
g
t
Triton
g
-factor:
g
t
= 2
µ
t
/µ
N
g
X
(
Y
)
g
-factor of particle
X
in the ground (1S) state of
hydrogenic atom
Y
g
µ
Muon
g
-factor:
g
µ
= 2
µ
µ
/
(
e
¯
h/
2
m
µ
)
3
GSI
Gesellschaft f¨
ur Schwerionenforschung, Darm-
stadt, Germany
HD
HD molecule (bound state of hydrogen and deu-
terium atoms)
HT
HT molecule (bound state of hydrogen and tri-
tium atoms)
h
Helion (nucleus of
3
He)
h
Planck constant; ¯
h
=
h/
2
Ï€
Harvard;
Harvard University, Cambridge, Massachusetts,
HarvU
USA
ILL
Institut Max von Laue-Paul Langevin, Grenoble,
France
IMGC
Istituto di Metrologia “T. Colonetti,†Torino,
Italy
INRIM
Istituto Nazionale di Ricerca Metrologica, Torino,
Italy
IRMM
Institute for Reference Materials and Measure-
ments, Geel, Belgium
JINR
Joint Institute for Nuclear Research, Dubna, Rus-
sian Federation
KRISS
Korea Research Institute of Standards and Sci-
ence, Taedok Science Town, Republic of Korea
KR/VN
KRISS-VNIIM collaboration
K
J
Josephson constant:
K
J
= 2
e/h
K
J
−
90
Conventional value of the Josephson constant
K
J
:
K
J
−
90
= 483 597
.
9 GHz V
−
1
k
Boltzmann constant:
k
=
R/N
A
LAMPF
Clinton P. Anderson Meson Physics Facility at Los
Alamos National Laboratory, Los Alamos, New
Mexico, USA
LKB
Laboratoire Kastler-Brossel, Paris, France
LK/SY
LKB and SYRTE collaboration
LNE
Laboratoire national de m´etrologie et d’essais,
Trappes, France
MIT
Massachusetts Institute of Technology, Cam-
bridge, Massachusetts, USA
MPQ
Max-Planck-Institut f¨
ur Quantenoptik, Garching,
Germany
MSL
Measurement Standards Laboratory, Lower Hutt,
New Zealand
M
(
X
)
Molar mass of
X
:
M
(
X
) =
A
r
(
X
)
M
u
Mu
Muonium (
µ
+
e
−
atom)
M
u
Molar mass constant:
M
u
= 10
−
3
kg mol
−
1
m
u
Uniï¬ed atomic mass constant:
m
u
=
m
(
12
C)/12
m
X
,
m
(
X
) Mass of
X
(for the electron e, proton p, and other
elementary particles, the ï¬rst symbol is used,
i.e.,
m
e
,
m
p
,
etc.
)
N
A
Avogadro constant
N/P/I
NMIJ-PTB-IRMM combined result
NIM
National Institute of Metrology, Beijing, China
(People’s Republic of)
NIST
National Institute of Standards and Technology,
Gaithersburg, Maryland and Boulder, Colorado,
USA
NMI
National Metrology Institute, Lindï¬eld, Australia
NMIJ
National Metrology Institute of Japan, Tsukuba,
Japan
NMR
Nuclear magnetic resonance
NPL
National Physical Laboratory, Teddington, UK
NRLM
National Research Laboratory of Metrology,
Tsukuba, Japan
n
Neutron
PRC
People’s Republic of China
PTB
Physikalisch-Technische Bundesanstalt, Braun-
schweig and Berlin, Germany
p
Proton
p
A
He
+
Antiprotonic helium (
A
He
+
+ p atom,
A
=
3 or 4)
QED
Quantum electrodynamics
Q
(
χ
2
|
ν
)
Probability that an observed value of chi-square
for
ν
degrees of freedom would exceed
χ
2
R
Molar gas constant
R
Ratio of muon anomaly difference frequency to
free proton NMR frequency
R
B
Birge ratio:
R
B
= (
χ
2
/ν
)
1
2
R
d
; Rd
Bound-state rms charge radius of the deuteron
R
K
von Klitzing constant:
R
K
=
h/e
2
R
K
−
90
Conventional value of the von Klitzing constant
R
K
:
R
K
−
90
= 25 812
.
807 Ω
R
p
; Rp
Bound-state rms charge radius of the proton
R
∞
Rydberg constant:
R
∞
=
m
e
cα
2
/
2
h
r
(
x
i
, x
j
)
Correlation coefficient of estimated values
x
i
and
x
j
:
r
(
x
i
, x
j
) =
u
(
x
i
, x
j
)
/
[
u
(
x
i
)
u
(
x
j
)]
r
i
Normalized residual of
x
i
:
r
i
= (
x
i
−
ˆ
x
i
)
/u
(
x
i
),
ˆ
x
i
is the adjusted value of
x
i
rms
Root mean square
S
c
Self-sensitivity coefficient
SI
Syst`eme international d’unit´es (International Sys-
tem of Units)
Stanford;
Stanford University, Stanford, California, USA
StanfU
StPtrsb
St. Petersburg, Russian Federation
SYRTE
Syst`emes de r´ef´erence Temps Espace, Paris,
France
T
Thermodynamic temperature
t
Triton (nucleus of tritium T, or
3
H)
th
Theory
Type A
Uncertainty evaluation by the statistical analysis
of series of observations
Type B
Uncertainty evaluation by means other than the
statistical analysis of series of observations
t
90
Celsius temperature on the International Temper-
ature Scale of 1990 (ITS-90)
U. Sussex;
University of Sussex, Sussex, UK
USus
UK
United Kingdom
USA
United States of America
UWash
University of Washington, Seattle, Washington,
USA
u
Uniï¬ed atomic mass unit (also called the dalton,
Da): 1 u =
m
u
=
m
(
12
C)/12
u
(
x
i
)
Standard uncertainty (
i.e.,
estimated standard
deviation) of an estimated value
x
i
of a quantity
X
i
(also simply
u
)
u
(
x
i
, x
j
)
Covariance of estimated values
x
i
and
x
j
u
diff
Standard uncertainty of the difference
x
i
−
x
j
:
u
2
diff
=
u
2
(
x
i
) +
u
2
(
x
j
)
−
2
u
(
x
i
, x
j
)
u
r
(
x
i
)
Relative standard uncertainty of an estimated
value
x
i
of a quantity
X
i
:
u
r
(
x
i
) =
u
(
x
i
)
/
|
x
i
|
, x
i
6
= 0 (also simply
u
r
)
u
r
(
x
i
, x
j
)
Relative covariance of estimated values
x
i
and
x
j
:
u
r
(
x
i
, x
j
) =
u
(
x
i
, x
j
)
/
(
x
i
x
j
)
V
m
(Si)
Molar volume of naturally occurring silicon
VNIIM
D. I. Mendeleyev All-Russian Research Institute
for Metrology, St. Petersburg, Russian Federation
4
V
90
Conventional unit of voltage based on the Joseph-
son effect and
K
J
−
90
:
V
90
= (
K
J
−
90
/K
J
) V
WGAC
Working Group on the Avogadro Constant of the
CIPM Consultative Committee for Mass and Re-
lated Quantities (CCM)
W
90
Conventional unit of power:
W
90
=
V
2
90
/
Ω
90
XROI
Combined x-ray and optical interferometer
xu(CuK
α
1
) Cu x unit:
λ
(CuK
α
1
) = 1 537.400 xu(CuK
α
1
)
xu(MoK
α
1
) Mo x unit:
λ
(MoK
α
1
) = 707.831 xu(MoK
α
1
)
x
(
X
)
Amount-of-substance fraction of
X
YAG
Yttrium aluminium garnet; Y
3
Al
5
O
12
Yale; YaleU Yale University, New Haven, Connecticut, USA
α
Fine-structure constant:
α
=
e
2
/
4
Ï€
Ç«
0
¯
hc
≈
1
/
137
α
Alpha particle (nucleus of
4
He)
Γ
′
X
−
90
(lo)
Γ
′
X
−
90
(lo) = (
γ
′
X
A
90
) A
−
1
,
X
= p or h
Γ
′
p
−
90
(hi)
Γ
′
p
−
90
(hi) = (
γ
′
p
/
A
90
) A
γ
p
Proton gyromagnetic ratio:
γ
p
= 2
µ
p
/
¯
h
γ
′
p
Shielded proton gyromagnetic ratio:
γ
′
p
= 2
µ
′
p
/
¯
h
γ
′
h
Shielded helion gyromagnetic ratio:
γ
′
h
= 2
|
µ
′
h
|
/
¯
h
∆
ν
Mu
Muonium ground-state hyperï¬ne splitting
δ
e
Additive correction to the theoretical expression
for the electron magnetic moment anomaly
a
e
δ
Mu
Additive correction to the theoretical expression
for the ground-state hyperï¬ne splitting of muon-
ium ∆
ν
Mu
δ
p He
Additive correction to the theoretical expression
for a particular transition frequency of antipro-
tonic helium
δ
X
(
n
L
j
)
Additive correction to the theoretical expression
for an energy level of either hydrogen H or deu-
terium D with quantum numbers
n
, L, and
j
δ
µ
Additive correction to the theoretical expression
for the muon magnetic moment anomaly
a
µ
Ç«
0
Electric constant:
Ç«
0
= 1
/µ
0
c
2
λ
(
X
K
α
1
)
Wavelength of K
α
1
x-ray line of element
X
λ
meas
Measured wavelength of the 2.2 MeV capture
γ
-
ray emitted in the reaction n + p
→
d +
γ
µ
Symbol for either member of the muon-antimuon
pair; when necessary,
µ
−
or
µ
+
is used to indicate
the negative muon or positive muon
µ
B
Bohr magneton:
µ
B
=
e
¯
h/
2
m
e
µ
N
Nuclear magneton:
µ
N
=
e
¯
h/
2
m
p
µ
X
(
Y
)
Magnetic moment of particle
X
in atom or
molecule
Y
.
µ
0
Magnetic constant:
µ
0
= 4
Ï€
×
10
−
7
N/A
2
µ
X
,
µ
′
X
Magnetic moment, or shielded magnetic moment,
of particle
X
ν
Degrees of freedom of a particular adjustment
ν
(
f
p
)
Difference between muonium hyperï¬ne splitting
Zeeman transition frequencies
ν
34
and
ν
12
at a
magnetic flux density
B
corresponding to the free
proton NMR frequency
f
p
σ
Stefan-Boltzmann constant:
σ
= 2
Ï€
5
k
4
/
(15
h
3
c
2
)
Ï„
Symbol for either member of the tau-antitau pair;
when necessary,
Ï„
−
or
Ï„
+
is used to indicate the
negative tau or positive tau
χ
2
The statistic “chi squareâ€
Ω
90
Conventional unit of resistance based on the quan-
tum Hall effect and
R
K
−
90
:
Ω
90
= (
R
K
/R
K
−
90
) Ω
.
=
Symbol used to relate an input datum to its ob-
servational equation
I. INTRODUCTION
A. Background
This paper gives the complete 2006 CODATA self-
consistent set of recommended values of the fundamental
physical constants and describes in detail the 2006 least-
squares adjustment, including the selection of the ï¬nal
set of input data based on the results of least-squares
analyses. Prepared under the auspices of the CODATA
Task Group on Fundamental Constants, this is the ï¬fth
such report of the Task Group since its establishment
in 1969
1
and the third in the four-year cycle of reports
begun in 1998. The 2006 set of recommended values re-
places its immediate predecessor, the 2002 set. The clos-
ing date for the availability of the data considered for
inclusion in this adjustment was 31 December 2006. As
a consequence of the new data that became available in
the intervening four years there has been a signiï¬cant re-
duction of the uncertainty of many constants. The 2006
set of recommended values ï¬rst became available on 29
March 2007 at http://physics.nist.gov/constants, a Web
site of the NIST Fundamental Constants Data Center
(FCDC).
The 1998 and 2002 reports describing the 1998 and
2002 adjustments (Mohr and Taylor, 2000, 2005), re-
ferred to as CODATA-98 and CODATA-02 throughout
this article, describe in detail much of the currently avail-
able data, its analysis, and the techniques used to obtain
a set of best values of the constants using the standard
method of least squares for correlated input data. This
paper focuses mainly on the new information that has be-
come available since 31 December 2002 and references the
discussions in CODATA-98 and CODATA-02 for earlier
work in the interest of brevity. More speciï¬cally, if a po-
tential input datum is not discussed in detail, the reader
can assume that it (or a closely related datum) has been
reviewed in either CODATA-98 or CODATA-02.
The reader is also referred to these papers for a discus-
sion of the motivation for and the philosophy behind the
periodic adjustment of the values of the constants and
for descriptions of how units, quantity symbols, numeri-
cal values, numerical calculations, and uncertainties are
treated, in addition to how the data are characterized, se-
lected, and evaluated. Since the calculations are carried
out with more signiï¬cant ï¬gures than are displayed in the
text to avoid rounding errors, data with more digits are
available on the FCDC Web site for possible independent
analysis.
However, because of their importance, we recall in de-
tail the following two points also discussed in these ref-
erences. First, although it is generally agreed that the
1
The Committee on Data for Science and Technology was estab-
lished in 1966 as an interdisciplinary committee of the Interna-
tional Council for Science.
5
correctness and over-all consistency of the basic theo-
ries and experimental methods of physics can be tested
by comparing values of particular fundamental constants
obtained from widely differing experiments, throughout
this adjustment, as a working principle, we assume the
validity of the physical theory that necessarily underlies
it. This includes special relativity, quantum mechanics,
quantum electrodynamics (QED), the Standard Model
of particle physics, including combined charge conjuga-
tion, parity inversion, and time reversal (
CP T
) invari-
ance, and the theory of the Josephson and quantum Hall
effects, especially the exactness of the relationships be-
tween the Josephson and von Klitzing constants
K
J
and
R
K
and the elementary charge
e
and Planck constant
h
.
In fact, tests of these relations,
K
J
= 2
e/h
and
R
K
=
h/e
2
, using the input data of the 2006 adjustment
are discussed in Sec. XII.B.2.
The second point has to do with the 31 December 2006
closing date for data to be considered for inclusion in the
2006 adjustment. A datum was considered to have met
this date, even though not yet reported in an archival
journal, as long as a description of the work was available
that allowed the Task Group to assign a valid standard
uncertainty
u
(
x
i
) to the datum. Thus, any input datum
labeled with an “07†identiï¬er because it was published
in 2007 was, in fact, available by the cutoff date. Also,
some references to results that became available after the
deadline are included, even though they were not used in
the adjustment.
B. Time variation of the constants
This subject, which was briefly touched upon in
CODATA-02, continues to be an active ï¬eld of exper-
imental and theoretical research, because of its impor-
tance to our understanding of physics at the most fun-
damental level. Indeed, a large number of papers rele-
vant to the topic have appeared in the last four years;
see the FCDC bibliographic database on the funda-
mental constants using the keyword “time variation†at
http://physics.nist.gov/constantsbib. For example, see
Fortier
et al.
(2007); Lea (2007). However, there has
been no laboratory observation of time dependence of
any constant that might be relevant to the recommended
values.
C. Outline of paper
Section II touches on special quantities and units, that
is, those that have exact values by deï¬nition.
Sections III-XI review all of the available experimental
and theoretical data that might be relevant to the 2006
adjustment of the values of the constants. As discussed
in Appendix E of CODATA-98, in a least squares anal-
ysis of the fundamental constants the numerical data,
both experimental and theoretical, also called
observa-
tional data
or
input data
, are expressed as functions of
a set of independent variables called
adjusted constants
.
The functions that relate the input data to the adjusted
constants are called
observational equations
, and the least
squares procedure provides best estimated values, in the
least squares sense, of the adjusted constants. The fo-
cus of the review-of-data sections is thus the identiï¬ca-
tion and discussion of the input data and observational
equations of interest for the 2006 adjustment. Although
not all observational equations that we use are explicitly
given in the text, all are summarized in Tables XXXVIII,
XL, and XLII of Sec. XII.B.
As part of our discussion of a particular datum, we
often deduce from it an inferred value of a constant, such
as the ï¬ne-structure constant
α
or Planck constant
h
. It
should be understood, however, that these inferred values
are for comparison purposes only; the datum from which
it is obtained, not the inferred value, is the input datum
in the adjustment.
Although just 4 years separate the 31 December clos-
ing dates of the 2002 and 2006 adjustments, there are
a number of important new results to consider. Experi-
mental advances include the 2003 Atomic Mass Evalua-
tion from the Atomic Mass Data Center (AMDC) that
provides new values for the relative atomic masses
A
r
(
X
)
of a number of relevant atoms; a new value of the elec-
tron magnetic moment anomaly
a
e
from measurements
on a single electron in a cylindrical penning trap that
provides a value of the ï¬ne-structure constant
α
; better
measurements of the relative atomic masses of
2
H,
3
H,
and
4
He; new measurements of transition frequencies in
antiprotonic helium (¯
p
A
He
+
atom) that provide a com-
petitive value of the relative atomic mass of the electron
A
r
(e); improved measurements of the nuclear magnetic
resonance (NMR) frequencies of the proton and deuteron
in the HD molecule and of the proton and triton in the
HT molecule; a highly accurate value of the Planck con-
stant obtained from an improved measurement of the
product
K
2
J
R
K
using a moving-coil watt balance; new
results using combined x-ray and optical interferometers
for the
{
220
}
lattice spacing of single crystals of natu-
rally occurring silicon; and an accurate value of the quo-
tient
h/m
(
87
Rb) obtained by measuring the recoil veloc-
ity of rubidium-87 atoms upon absorption or emission
of photons—a result that provides an accurate value of
α
that is virtually independent of the electron magnetic
moment anomaly.
Theoretical advances include improvements in certain
aspects of the theory of the energy levels of hydrogen
and deuterium; improvements in the theory of antipro-
tonic helium transition frequencies that, together with
the new transition frequency measurements, have led to
the aforementioned competitive value of
A
r
(e); a new
theoretical expression for
a
e
that, together with the new
experimental value of
a
e
, has led to the aforementioned
value of
α
; improvements in the theory of the
g
-factor of
the bound electron in hydrogenic ions with nuclear spin
quantum number
i
= 0 relevant to the determination of
6
A
r
(e); and improved theory of the ground state hyperï¬ne
splitting of muonium ∆
ν
Mu
(the
µ
+
e
−
atom).
Section XII describes the analysis of the data, with
the exception of the Newtonian constant of gravitation
which is analyzed in Sec. X. The consistency of the data
and potential impact on the determination of the 2006
recommended values were appraised by comparing mea-
sured values of the same quantity, comparing measured
values of different quantities through inferred values of a
third quantity such as
α
or
h
, and ï¬nally by using the
method of least squares. Based on these investigations,
the ï¬nal set of input data used in the 2006 adjustment
was selected.
Section XIII provides, in several tables, the 2006
CODATA recommended values of the basic constants and
conversion factors of physics and chemistry, including the
covariance matrix of a selected group of constants.
Section XIV concludes the paper with a comparison of
the 2006 and 2002 recommended values of the constants,
a survey of implications for physics and metrology of the
2006 values and adjustment, and suggestions for future
work that can advance our knowledge of the values of the
constants.
II. SPECIAL QUANTITIES AND UNITS
Table I lists those special quantities whose numerical
values are exactly deï¬ned. In the International System
of Units (SI) (BIPM, 2006), which we use throughout
this paper, the deï¬nition of the meter ï¬xes the speed
of light in vacuum
c
, the deï¬nition of the ampere ï¬xes
the magnetic constant (also called the permeability of
vacuum)
µ
0
, and the deï¬nition of the mole ï¬xes the molar
mass of the carbon 12 atom
M
(
12
C) to have the exact
values given in the table. Since the electric constant (also
called the permittivity of vacuum) is related to
µ
0
by
Ç«
0
= 1
/µ
0
c
2
, it too is known exactly.
The relative atomic mass
A
r
(
X
) of an entity
X
is de-
ï¬ned by
A
r
(
X
) =
m
(
X
)
/m
u
, where
m
(
X
) is the mass of
X
and
m
u
is the atomic mass constant deï¬ned by
m
u
=
1
12
m
(
12
C) = 1 u
≈
1
.
66
×
10
−
27
kg
,
(1)
where
m
(
12
C) is the mass of the carbon 12 atom and u is
the uniï¬ed atomic mass unit (also called the dalton, Da).
Clearly,
A
r
(
X
) is a dimensionless quantity and
A
r
(
12
C) =
12 exactly. The molar mass
M
(
X
) of entity
X
, which is
the mass of one mole of
X
with SI unit kg/mol, is given
by
M
(
X
) =
N
A
m
(
X
) =
A
r
(
X
)
M
u
,
(2)
where
N
A
≈
6
.
02
×
10
23
/mol is the Avogadro constant
and
M
u
= 10
−
3
kg/mol is the molar mass constant. The
numerical value of
N
A
is the number of entities in one
mole, and since the deï¬nition of the mole states that one
mole contains the same number of entities as there are in
0.012 kg of carbon 12,
M
(
12
C) = 0
.
012 kg/mol exactly.
The Josephson and quantum Hall effects have played
and continue to play important roles in adjustments of
the values of the constants, because the Josephson and
von Klitzing constants
K
J
and
R
K
, which underlie these
two effects, are related to
e
and
h
by
K
J
=
2
e
h
;
R
K
=
h
e
2
=
µ
0
c
2
α
.
(3)
Although we assume these relations are exact, and no
evidence—either theoretical or experimental—has been
put forward that challenges this assumption, the conse-
quences of relaxing it are explored in Sec. XII.B.2. Some
references to recent work related to the Josephson and
quantum Hall effects may be found in the FCDC biblio-
graphic database (see Sec. I.B).
The next-to-last two entries in Table I are the conven-
tional values of the Josephson and von Klitzing constants
adopted by the International Committee for Weights and
Measures (CIPM) and introduced on 1 January 1990 to
establish worldwide uniformity in the measurement of
electrical quantities. In this paper, all electrical quanti-
ties are expressed in SI units. However, those measured
in terms of the Josephson and quantum Hall effects with
the assumption that
K
J
and
R
K
have these conventional
values are labeled with a subscript 90.
For high-accuracy experiments involving the force of
gravity, such as the watt-balance, an accurate measure-
ment of the local acceleration of free fall at the site of the
experiment is required. Fortunately, portable and easy-
to-use commercial absolute gravimeters are available that
can provide a local value of
g
with a relative standard un-
certainty of a few parts in 10
9
. That these instruments
can achieve such a small uncertainty if properly used is
demonstrated by a periodic international comparison of
absolute gravimeters (ICAG) carried out at the Interna-
tional Bureau of Weights and Measures (BIPM), S`evres,
France; the seventh and most recent, denoted ICAG-
2005, was completed in September 2005 (Vitushkin
et
al.
, 2005); the next is scheduled for 2009. In the future,
atom interferometry or Bloch oscillations using ultracold
atoms could provide a competitive or possibly more ac-
curate method for determining a local value of
g
(Clad´e
et al.
, 2005; McGuirk
et al.
, 2002; Peters
et al.
, 2001).
III. RELATIVE ATOMIC MASSES
Included in the set of adjusted constants are the rel-
ative atomic masses
A
r
(
X
) of a number of particles,
atoms, and ions. Tables II-VI and the following sections
summarize the relevant data.
A. Relative atomic masses of atoms
Most values of the relative atomic masses of neu-
tral atoms used in this adjustment are taken from the
2003 atomic mass evaluation (AME2003) of the Atomic
7
TABLE I Some exact quantities relevant to the 2006 adjustment.
Quantity
Symbol
Value
speed of light in vacuum
c
,
c
0
299 792 458 m s
−
1
magnetic constant
µ
0
4
Ï€
×
10
−
7
N A
−
2
= 12
.
566 370 614
...
×
10
−
7
N A
−
2
electric constant
Ç«
0
(
µ
0
c
2
)
−
1
= 8
.
854 187 817
...
×
10
−
12
F m
−
1
relative atomic mass of
12
C
A
r
(
12
C)
12
molar mass constant
M
u
10
−
3
kg mol
−
1
molar mass of
12
C
A
r
(
12
C)
M
u
M
(
12
C)
12
×
10
−
3
kg mol
−
1
conventional value of Josephson constant
K
J
−
90
483 597
.
9 GHz V
−
1
conventional value of von Klitzing constant
R
K
−
90
25 812
.
807 Ω
Mass Data Center, Centre de Spectrom´etrie Nucl´eaire
et de Spectrom´etrie de Masse (CSNSM), Orsay, France
(AMDC, 2006; Audi
et al.
, 2003; Wapstra
et al.
, 2003).
The results of AME2003 supersede those of both the 1993
atomic mass evaluation and the 1995 update. Table II
lists the values from AME2003 of interest here, while Ta-
ble III gives the covariance for hydrogen and deuterium
(AMDC, 2003). Other non-negligible covariances of these
values are discussed in the appropriate sections.
Table IV gives six values of
A
r
(
X
) relevant to the 2006
adjustment reported since the completion and publica-
tion of AME2003 in late 2003 that we use in place of the
corresponding values in Table II.
The
3
H and
3
He values are those reported by the
SMILETRAP group at the Manne Siegbahn Laboratory
(MSL), Stockholm, Sweden (Nagy
et al.
, 2006), using a
Penning trap and a time of flight technique to detect
cyclotron resonances. This new
3
He result is in good
agreement with a more accurate, but still preliminary,
result from the University of Washington group in Seat-
tle, USA (Van Dyck, 2006). The AME2003 values for
3
H
and
3
He were influenced by an earlier result for
3
He from
the University of Washington group which is in disagree-
ment with their new result.
The values for
4
He and
16
O are those reported by the
University of Washington group (Van Dyck
et al.
, 2006)
using their improved mass spectrometer; they are based
on a thorough reanalysis of data that yielded preliminary
results for these atoms which were used in AME2003.
They include an experimentally determined image-charge
correction with a relative standard uncertainty
u
r
= 7
.
9
×
10
−
12
in the case of
4
He and
u
r
= 4
.
0
×
10
−
12
in the
case of
16
O. The value of
A
r
(
2
H) is also from this group
and is a near-ï¬nal result based on the analysis of ten
runs carried out over a 4 year period (Van Dyck, 2006).
Because the result is not yet ï¬nal, the total uncertainty is
conservatively assigned;
u
r
= 9
.
9
×
10
−
12
for the image-
charge correction. This value of
A
r
(
2
H) is consistent with
the preliminary value reported by Van Dyck
et al.
(2006)
based on the analysis of only three runs.
The covariance and correlation coefficient of
A
r
(
3
H)
and
A
r
(
3
He) given in Table V are due to the common
component of uncertainty
u
r
= 1
.
4
×
10
−
10
of the rel-
ative atomic mass of the H
+
2
reference ion used in the
SMILETRAP measurements; the covariances and corre-
lation coefficients of the University of Washington values
of
A
r
(
2
H),
A
r
(
4
He), and
A
r
(
16
O) given in Table VI are
due to the uncertainties of the image-charge corrections,
which are based on the same experimentally determined
relation.
The
29
Si value is that implied by the ratio
A
r
(
29
Si
+
)/
A
r
(
28
Si H
+
)= 0
.
999 715 124 1812(65) obtained
at the Massachusetts Institute of Technology (MIT),
Cambridge, USA, using a recently developed technique
of determining mass ratios by directly comparing the cy-
clotron frequencies of two different ions simultaneously
conï¬ned in a Penning trap (Rainville
et al.
, 2005). (The
relative atomic mass work of the MIT group has now
been transferred to Florida State University, Tallahas-
see, USA.) This approach eliminates many components
of uncertainty arising from systematic effects. The value
for
A
r
(
29
Si) is given in the Supplementary Information
to Rainville
et al.
(2005) and has a signiï¬cantly smaller
uncertainty than the corresponding AME2003 value.
B. Relative atomic masses of ions and nuclei
The relative atomic mass
A
r
(
X
) of a neutral atom
X
is given in terms of the relative atomic mass of an ion of
the atom formed by the removal of
n
electrons by
A
r
(
X
) =
A
r
(
X
n
+
) +
nA
r
(e)
−
E
b
(
X
)
−
E
b
(
X
n
+
)
m
u
c
2
.
(4)
Here
E
b
(
X
)
/m
u
c
2
is the relative-atomic-mass equivalent
of the total binding energy of the
Z
electrons of the atom,
where
Z
is the atomic number (proton number), and
E
b
(
X
n
+
)
/m
u
c
2
is the relative-atomic-mass-equivalent of
the binding energy of the
Z
−
n
electrons of the
X
n
+
ion. For a fully stripped atom, that is, for
n
=
Z
,
X
Z
+
is
N
, where
N
represents the nucleus of the atom, and
E
b
(
X
Z
+
)
/m
u
c
2
= 0, which yields the ï¬rst few equations
of Table XL in Sec. XII.B.
The binding energies
E
b
used in this work are the same
as those used in the 2002 adjustment; see Table IV of
CODATA-02. For tritium, which is not included there,
we use the value 1
.
097 185 439
×
10
7
m
−
1
(Kotochigova,
2006). The uncertainties of the binding energies are neg-
ligible for our application.
8
TABLE II Values of the relative atomic masses of the neutron
and various atoms as given in the 2003 atomic mass evaluation
together with the deï¬ned value for
12
C.
Atom
Relative atomic
Relative standard
mass
A
r
(X)
uncertainty
u
r
n
1
.
008 664 915 74(56)
5
.
6
×
10
−
10
1
H
1
.
007 825 032 07(10)
1
.
0
×
10
−
10
2
H
2
.
014 101 777 85(36)
1
.
8
×
10
−
10
3
H
3
.
016 049 2777(25)
8
.
2
×
10
−
10
3
He
3
.
016 029 3191(26)
8
.
6
×
10
−
10
4
He
4
.
002 603 254 153(63)
1
.
6
×
10
−
11
12
C
12
(exact)
16
O
15
.
994 914 619 56(16)
1
.
0
×
10
−
11
28
Si
27
.
976 926 5325(19)
6
.
9
×
10
−
11
29
Si
28
.
976 494 700(22)
7
.
6
×
10
−
10
30
Si
29
.
973 770 171(32)
1
.
1
×
10
−
9
36
Ar
35
.
967 545 105(28)
7
.
8
×
10
−
10
38
Ar
37
.
962 732 39(36)
9
.
5
×
10
−
9
40
Ar
39
.
962 383 1225(29)
7
.
2
×
10
−
11
87
Rb
86
.
909 180 526(12)
1
.
4
×
10
−
10
107
Ag
106
.
905 0968(46)
4
.
3
×
10
−
8
109
Ag
108
.
904 7523(31)
2
.
9
×
10
−
8
133
Cs
132
.
905 451 932(24)
1
.
8
×
10
−
10
TABLE III The variances, covariance, and correlation coeffi-
cient of the AME2003 values of the relative atomic masses of
hydrogen and deuterium. The number in bold above the main
diagonal is 10
18
times the numerical value of the covariance;
the numbers in bold on the main diagonal are 10
18
times the
numerical values of the variances; and the number in italics
below the main diagonal is the correlation coefficient.
A
r
(
1
H)
A
r
(
2
H)
A
r
(
1
H)
0
.
0107 0
.
0027
A
r
(
2
H)
0
.
0735
0
.
1272
C. Cyclotron resonance measurement of the electron
relative atomic mass
A
r
(e)
A value of
A
r
(e) is available from a Penning-trap mea-
surement carried out by the University of Washington
group (Farnham
et al.
, 1995); it is used as an input datum
in the 2006 adjustment, as it was in the 2002 adjustment:
A
r
(e) = 0
.
000 548 579 9111(12)
[2
.
1
×
10
−
9
]
.
(5)
IV. ATOMIC TRANSITION FREQUENCIES
Atomic transition frequencies in hydrogen, deuterium,
and anti-protonic helium yield information on the Ryd-
berg constant, the proton and deuteron charge radii, and
the relative atomic mass of the electron. The hyperï¬ne
splitting in hydrogen and ï¬ne-structure splitting in he-
lium do not yield a competitive value of any constant at
the current level of accuracy of the relevant experiment
TABLE IV Values of the relative atomic masses of various
atoms that have become available since the 2003 atomic mass
evaluation.
Atom
Relative atomic
Relative standard
mass
A
r
(
X
)
uncertainty
u
r
2
H
2
.
014 101 778 040(80)
4
.
0
×
10
−
11
3
H
3
.
016 049 2787(25)
8
.
3
×
10
−
10
3
He
3
.
016 029 3217(26)
8
.
6
×
10
−
10
4
He
4
.
002 603 254 131(62)
1
.
5
×
10
−
11
16
O
15
.
994 914 619 57(18)
1
.
1
×
10
−
11
29
Si
28
.
976 494 6625(20)
6
.
9
×
10
−
11
TABLE V The variances, covariance, and correlation coeffi-
cient of the values of the SMILETRAP relative atomic masses
of tritium and helium three. The number in bold above the
main diagonal is 10
18
times the numerical value of the co-
variance; the numbers in bold on the main diagonal are 10
18
times the numerical values of the variances; and the number
in italics below the main diagonal is the correlation coefficient.
A
r
(
3
H)
A
r
(
3
He)
A
r
(
3
H)
6
.
2500
0
.
1783
A
r
(
3
He)
0
.
0274
6
.
7600
and/or theory. All of these topics are discussed in this
section.
A. Hydrogen and deuterium transition frequencies, the
Rydberg constant
R
∞
, and the proton and deuteron
charge radii
R
p
, R
d
The Rydberg constant is related to other constants by
the deï¬nition
R
∞
=
α
2
m
e
c
2
h
.
(6)
It can be accurately determined by comparing measured
resonant frequencies of transitions in hydrogen (H) and
deuterium (D) to the theoretical expressions for the en-
ergy level differences in which it is a multiplicative factor.
TABLE VI The variances, covariances, and correlation coef-
ï¬cients of the University of Washington values of the relative
atomic masses of deuterium, helium 4, and oxygen 16. The
numbers in bold above the main diagonal are 10
20
times the
numerical values of the covariances; the numbers in bold on
the main diagonal are 10
20
times the numerical values of the
variances; and the numbers in italics below the main diagonal
are the correlation coefficients.
A
r
(
2
H)
A
r
(
4
He)
A
r
(
16
O)
A
r
(
2
H)
0
.
6400
0
.
0631
0
.
1276
A
r
(
4
He)
0
.
1271
0
.
3844
0
.
2023
A
r
(
16
O)
0
.
0886
0
.
1813
3
.
2400
9
1. Theory relevant to the Rydberg constant
The theory of the energy levels of hydrogen and deu-
terium atoms relevant to the determination of the Ryd-
berg constant
R
∞
, based on measurements of transition
frequencies, is summarized in this section. Complete in-
formation necessary to determine the theoretical values
of the relevant energy levels is provided, with an emphasis
on results that have become available since the previous
adjustment described in CODATA-02. For brevity, refer-
ences to earlier work, which can be found in Eides
et al.
(2001b), for example, are not included here.
An important consideration is that the theoretical val-
ues of the energy levels of different states are highly cor-
related. For example, for S states, the uncalculated terms
are primarily of the form of an unknown common con-
stant divided by
n
3
. This fact is taken into account by
calculating covariances between energy levels in addition
to the uncertainties of the individual levels as discussed
in detail in Sec. IV.A.1.l. In order to take these corre-
lations into account, we distinguish between components
of uncertainty that are proportional to 1
/n
3
, denoted by
u
0
, and components of uncertainty that are essentially
random functions of
n
, denoted by
u
n
.
The energy levels of hydrogen-like atoms are deter-
mined mainly by the Dirac eigenvalue, QED effects such
as self energy and vacuum polarization, and nuclear size
and motion effects, all of which are summarized in the
following sections.
a. Dirac eigenvalue
The binding energy of an electron in
a static Coulomb ï¬eld (the external electric ï¬eld of a
point nucleus of charge
Ze
with inï¬nite mass) is deter-
mined predominantly by the Dirac eigenvalue
E
D
=
f
(
n, j
)
m
e
c
2
,
(7)
where
f
(
n, j
) =
1 +
(
Zα
)
2
(
n
−
δ
)
2
−
1
/
2
,
(8)
n
and
j
are the principal quantum number and total
angular momentum of the state, respectively, and
δ
=
j
+
1
2
−
(
j
+
1
2
)
2
−
(
Zα
)
2
1
/
2
.
(9)
Although we are interested only in the case where the
nuclear charge is
e
, we retain the atomic number
Z
in
order to indicate the nature of various terms.
Corrections to the Dirac eigenvalue that approximately
take into account the ï¬nite mass of the nucleus
m
N
are
included in the more general expression for atomic energy
levels, which replaces Eq. (7) (Barker and Glover, 1955;
Sapirstein and Yennie, 1990):
E
M
=
M c
2
+ [
f
(
n, j
)
−
1]
m
r
c
2
−
[
f
(
n, j
)
−
1]
2
m
2
r
c
2
2
M
+
1
−
δ
l
0
κ
(2
l
+ 1)
(
Zα
)
4
m
3
r
c
2
2
n
3
m
2
N
+
· · ·
,
(10)
where
l
is the nonrelativistic orbital angular momentum
quantum number,
κ
is the angular-momentum-parity
quantum number
κ
= (
−
1)
j
−
l
+1
/
2
(
j
+
1
2
),
M
=
m
e
+
m
N
,
and
m
r
=
m
e
m
N
/
(
m
e
+
m
N
) is the reduced mass.
b. Relativistic recoil
Relativistic corrections to Eq. (10)
associated with motion of the nucleus are considered
relativistic-recoil corrections. The leading term, to low-
est order in
Zα
and all orders in
m
e
/m
N
, is (Erickson,
1977; Sapirstein and Yennie, 1990)
E
S
=
m
3
r
m
2
e
m
N
(
Zα
)
5
Ï€
n
3
m
e
c
2
×
1
3
δ
l
0
ln(
Zα
)
−
2
−
8
3
ln
k
0
(
n, l
)
−
1
9
δ
l
0
−
7
3
a
n
−
2
m
2
N
−
m
2
e
δ
l
0
m
2
N
ln
m
e
m
r
−
m
2
e
ln
m
N
m
r
,
(11)
where
a
n
=
−
2
"
ln
2
n
+
n
X
i
=1
1
i
+ 1
−
1
2
n
#
δ
l
0
+
1
−
δ
l
0
l
(
l
+ 1)(2
l
+ 1)
.
(12)
To lowest order in the mass ratio, higher-order cor-
rections in
Zα
have been extensively investigated; the
contribution of the next two orders in
Zα
is
E
R
=
m
e
m
N
(
Zα
)
6
n
3
m
e
c
2
×
D
60
+
D
72
Zα
ln
2
(
Zα
)
−
2
+
· · ·
,
(13)
where for
n
S
1
/
2
states (Eides and Grotch, 1997c;
Pachucki and Grotch, 1995)
D
60
= 4 ln 2
−
7
2
(14)
and (Melnikov and Yelkhovsky, 1999; Pachucki and
Karshenboim, 1999)
D
72
=
−
11
60
Ï€
,
(15)
and for states with
l
≥
1 (Elkhovski˘ı, 1996; Golosov
et al.
,
1995; Jentschura and Pachucki, 1996)
D
60
=
3
−
l
(
l
+ 1)
n
2
2
(4
l
2
−
1)(2
l
+ 3)
.
(16)
In Eq. (16) and subsequent discussion, the ï¬rst subscript
on the coefficient of a term refers to the power of
Zα
and the second subscript to the power of ln(
Zα
)
−
2
. The
relativistic recoil correction used in the 2006 adjustment
is based on Eqs. (11) to (16). The estimated uncertainty
10
for S states is taken to be 10 % of Eq. (13), and for states
with
l
≥
1, it is taken to be 1 % of that equation.
Numerical values for the complete contribution of
Eq. (13) to all orders in
Zα
have been obtained by
(Shabaev
et al.
, 1998). Although the difference between
the all-orders calculation and the truncated power series
for S states is about three times their quoted uncertainty,
the two results are consistent within the uncertainty as-
signed here. The covariances of the theoretical values
are calculated by assuming that the uncertainties are
predominately due to uncalculated terms proportional to
(
m
e
/m
N
)
/n
3
.
c. Nuclear polarization
Interactions between the atomic
electron and the nucleus which involve excited states
of the nucleus give rise to nuclear polarization correc-
tions. For hydrogen, we use the result (Khriplovich and
Sen’kov, 2000)
E
P
(H) =
−
0
.
070(13)
h
δ
l
0
n
3
kHz
.
(17)
For deuterium, the sum of the proton polarizability, the
neutron polarizability (Khriplovich and Sen’kov, 1998),
and the dominant nuclear structure polarizability (Friar
and Payne, 1997a), gives
E
P
(D) =
−
21
.
37(8)
h
δ
l
0
n
3
kHz
.
(18)
We assume that this effect is negligible in states of higher
l
.
d. Self energy
The one-photon electron self energy is
given by
E
(2)
SE
=
α
Ï€
(
Zα
)
4
n
3
F
(
Zα
)
m
e
c
2
,
(19)
where
F
(
Zα
) =
A
41
ln(
Zα
)
−
2
+
A
40
+
A
50
(
Zα
)
+
A
62
(
Zα
)
2
ln
2
(
Zα
)
−
2
+
A
61
(
Zα
)
2
ln(
Zα
)
−
2
+
G
SE
(
Zα
) (
Zα
)
2
.
(20)
From Erickson and Yennie (1965) and earlier papers cited
therein,
A
41
=
4
3
δ
l
0
A
40
=
−
4
3
ln
k
0
(
n, l
) +
10
9
δ
l
0
−
1
2
κ
(2
l
+ 1)
(1
−
δ
l
0
)
A
50
=
139
32
−
2 ln 2
Ï€
δ
l
0
(21)
A
62
=
−
δ
l
0
A
61
=
4
1 +
1
2
+
· · ·
+
1
n
+
28
3
ln 2
−
4 ln
n
−
601
180
−
77
45
n
2
δ
l
0
+
1
−
1
n
2
2
15
+
1
3
δ
j
1
2
δ
l
1
+
96
n
2
−
32
l
(
l
+ 1)
3
n
2
(2
l
−
1)(2
l
)(2
l
+ 1)(2
l
+ 2)(2
l
+ 3)
(1
−
δ
l
0
)
.
TABLE VII Bethe logarithms ln
k
0
(
n, l
) relevant to the de-
termination of
R
∞
.
n
S
P
D
1
2
.
984 128 556
2
2
.
811 769 893
−
0
.
030 016 709
3
2
.
767 663 612
4
2
.
749 811 840
−
0
.
041 954 895
−
0
.
006 740 939
6
2
.
735 664 207
−
0
.
008 147 204
8
2
.
730 267 261
−
0
.
008 785 043
12
−
0
.
009 342 954
The Bethe logarithms ln
k
0
(
n, l
) in Eq. (21) are given in
Table VII (Drake and Swainson, 1990).
The function
G
SE
(
Zα
) in Eq. (20) is the higher-order
contribution (in
Zα
) to the self energy, and the values for
G
SE
(
α
) that we use here are listed in Table VIII. For S
and P states with
n
≤
4 the values in the table are based
on direct numerical evaluations by Jentschura and Mohr
(2004, 2005); Jentschura
et al.
(1999, 2001). The values
of
G
SE
(
α
) for the 6S and 8S states are based on the low-
Z
limit of this function
G
SE
(0) =
A
60
(Jentschura
et al.
,
2005a) together with extrapolations of the results of com-
plete numerical calculations of
F
(
Zα
) [see Eq. (20)] at
higher
Z
(Kotochigova and Mohr, 2006). The values of
G
SE
(
α
) for D states are from Jentschura
et al.
(2005b)
The dominant effect of the ï¬nite mass of the nucleus on
the self energy correction is taken into account by mul-
tiplying each term of
F
(
Zα
) by the reduced-mass fac-
tor (
m
r
/m
e
)
3
, except that the magnetic moment term
−
1
/
[2
κ
(2
l
+ 1)] in
A
40
is instead multiplied by the factor
(
m
r
/m
e
)
2
. In addition, the argument (
Zα
)
−
2
of the log-
arithms is replaced by (
m
e
/m
r
)(
Zα
)
−
2
(Sapirstein and
Yennie, 1990).
The uncertainty of the self energy contribution to a
given level arises entirely from the uncertainty of
G
SE
(
α
)
listed in Table VIII and is taken to be entirely of type
u
n
.
e. Vacuum
polarization
The
second-order
vacuum-
polarization level shift is
E
(2)
VP
=
α
Ï€
(
Zα
)
4
n
3
H
(
Zα
)
m
e
c
2
,
(22)
where the function
H
(
Zα
) is divided into the part cor-
responding to the Uehling potential, denoted here by
H
(1)
(
Zα
), and the higher-order remainder
H
(R)
(
Zα
),
where
H
(1)
(
Zα
) =
V
40
+
V
50
(
Zα
) +
V
61
(
Zα
)
2
ln(
Zα
)
−
2
+
G
(1)
VP
(
Zα
) (
Zα
)
2
(23)
H
(R)
(
Zα
) =
G
(R)
VP
(
Zα
) (
Zα
)
2
,
(24)
11
TABLE VIII Values of the function
G
SE
(
α
).
n
S
1
/
2
P
1
/
2
P
3
/
2
D
3
/
2
D
5
/
2
1
−
30
.
290 240(20)
2
−
31
.
185 150(90)
−
0
.
973 50(20)
−
0
.
486 50(20)
3
−
31
.
047 70(90)
4
−
30
.
9120(40)
−
1
.
1640(20)
−
0
.
6090(20)
0
.
031 63(22)
6
−
30
.
711(47)
0
.
034 17(26)
8
−
30
.
606(47)
0
.
007 940(90)
0
.
034 84(22)
12
0
.
0080(20)
0
.
0350(30)
with
V
40
=
−
4
15
δ
l
0
V
50
=
5
48
Ï€
δ
l
0
(25)
V
61
=
−
2
15
δ
l
0
.
The part
G
(1)
VP
(
Zα
) arises from the Uehling potential
with values given in Table IX (Kotochigova
et al.
, 2002;
Mohr, 1982). The higher-order remainder
G
(R)
VP
(
Zα
) has
been considered by Wichmann and Kroll, and the leading
terms in powers of
Zα
are (Mohr, 1975, 1983; Wichmann
and Kroll, 1956)
G
(R)
VP
(
Zα
) =
19
45
−
Ï€
2
27
δ
l
0
+
1
16
−
31
Ï€
2
2880
Ï€
(
Zα
)
δ
l
0
+
· · ·
.
(26)
Higher-order terms omitted from Eq. (26) are negligible.
In a manner similar to that for the self energy, the
leading effect of the ï¬nite mass of the nucleus is taken into
account by multiplying Eq. (22) by the factor (
m
r
/m
e
)
3
and including a multiplicative factor of (
m
e
/m
r
) in the
argument of the logarithm in Eq. (23).
There is also a second-order vacuum polarization level
shift due to the creation of virtual particle pairs other
than the e
−
e
+
pair. The predominant contribution for
n
S states arises from
µ
+
µ
−
, with the leading term being
(Eides and Shelyuto, 1995; Karshenboim, 1995)
E
(2)
µ
VP
=
α
Ï€
(
Zα
)
4
n
3
−
4
15
m
e
m
µ
2
m
r
m
e
3
m
e
c
2
.
(27)
The next order term in the contribution of muon vacuum
polarization to
n
S states is of relative order
Zαm
e
/m
µ
and is therefore negligible. The analogous contribution
E
(2)
Ï„
VP
from
Ï„
+
Ï„
−
(
−
18 Hz for the 1S state) is also negli-
gible at the level of uncertainty of current interest.
For the hadronic vacuum polarization contribution, we
take the result given by Friar
et al.
(1999) that utilizes
all available e
+
e
−
scattering data:
E
(2)
had VP
= 0
.
671(15)
E
(2)
µ
VP
,
(28)
where the uncertainty is of type
u
0
.
The muonic and hadronic vacuum polarization contri-
butions are negligible for P and D states.
f. Two-photon corrections
Corrections from two virtual
photons have been partially calculated as a power series
in
Zα
:
E
(4)
=
α
Ï€
2
(
Zα
)
4
n
3
m
e
c
2
F
(4)
(
Zα
)
,
(29)
where
F
(4)
(
Zα
) =
B
40
+
B
50
(
Zα
) +
B
63
(
Zα
)
2
ln
3
(
Zα
)
−
2
+
B
62
(
Zα
)
2
ln
2
(
Zα
)
−
2
+
B
61
(
Zα
)
2
ln(
Zα
)
−
2
+
B
60
(
Zα
)
2
+
· · ·
.
(30)
The leading term
B
40
is well known:
B
40
=
3
Ï€
2
2
ln 2
−
10
Ï€
2
27
−
2179
648
−
9
4
ζ
(3)
δ
l
0
+
Ï€
2
ln 2
2
−
Ï€
2
12
−
197
144
−
3
ζ
(3)
4
1
−
δ
l
0
κ
(2
l
+ 1)
.
(31)
The second term is (Eides
et al.
, 1997; Eides and She-
lyuto, 1995; Pachucki, 1993a, 1994)
B
50
=
−
21
.
5561(31)
δ
l
0
,
(32)
and the next coefficient is (Karshenboim, 1993; Manohar
and Stewart, 2000; Pachucki, 2001; Yerokhin, 2000)
B
63
=
−
8
27
δ
l
0
.
(33)
For S states the coefficient
B
62
is given by
B
62
=
16
9
71
60
−
ln 2 +
γ
+
ψ
(
n
)
−
ln
n
−
1
n
+
1
4
n
2
,
(34)
where
γ
= 0
.
577
...
is Euler’s constant and
ψ
is the psi
function (Abramowitz and Stegun, 1965). The difference
B
62
(1)
−
B
62
(
n
) was calculated by Karshenboim (1996)
12
TABLE IX Values of the function
G
(1)
VP
(
α
).
n
S
1
/
2
P
1
/
2
P
3
/
2
D
3
/
2
D
5
/
2
1
−
0
.
618 724
2
−
0
.
808 872
−
0
.
064 006
−
0
.
014 132
3
−
0
.
814 530
4
−
0
.
806 579
−
0
.
080 007
−
0
.
017 666
−
0
.
000 000
6
−
0
.
791 450
−
0
.
000 000
8
−
0
.
781 197
−
0
.
000 000
−
0
.
000 000
12
−
0
.
000 000
−
0
.
000 000
and conï¬rmed by Pachucki (2001) who also calculated
the
n
-independent additive constant. For P states the
calculated value is (Karshenboim, 1996)
B
62
=
4
27
n
2
−
1
n
2
.
(35)
This result has been conï¬rmed by Jentschura and
N´
andori (2002) who also show that for D and higher an-
gular momentum states
B
62
= 0.
Recent work has led to new results for
B
61
and higher-
order coefficients. In Jentschura
et al.
(2005a) an ad-
ditional state-independent contribution to the coefficient
B
61
for S states is given, which slightly differs (2 %) from
the earlier result of Pachucki (2001) quoted in CODATA
2002. The revised coefficient for S states is
B
61
=
413 581
64 800
+
4
N
(
n
S)
3
+
2027
Ï€
2
864
−
616 ln 2
135
−
2
Ï€
2
ln 2
3
+
40 ln
2
2
9
+
ζ
(3) +
304
135
−
32 ln 2
9
×
3
4
+
γ
+
ψ
(
n
)
−
ln
n
−
1
n
+
1
4
n
2
,
(36)
where
ζ
is the Riemann zeta function (Abramowitz and
Stegun, 1965). The coefficients
N
(
n
S) are listed in Ta-
ble X. The state-dependent part
B
61
(
n
S)
−
B
61
(1S) was
conï¬rmed by Jentschura
et al.
(2005a) in their Eqs. (4.26)
and (6.3). For higher-
l
states,
B
61
has been calculated
by Jentschura
et al.
(2005a); for P states
B
61
(
n
P
1
/
2
) =
4
3
N
(
n
P) +
n
2
−
1
n
2
166
405
−
8
27
ln 2
,
(37)
B
61
(
n
P
3
/
2
) =
4
3
N
(
n
P) +
n
2
−
1
n
2
31
405
−
8
27
ln 2
,
(38)
and for D states
B
61
(
n
D) = 0
.
(39)
The coefficient
B
61
also vanishes for states with
l >
2.
The necessary values of
N
(
n
P) are given in Eq. (17) of
Jentschura (2003) and are listed in Table X.
The next term is
B
60
, and recent work has also been
done for this contribution. For S states, the state depen-
dence is considered ï¬rst, and is given by Czarnecki
et al.
(2005); Jentschura
et al.
(2005a)
B
60
(
n
S)
−
B
60
(1S) =
b
L
(
n
S)
−
b
L
(1S) +
A
(
n
)
,
(40)
TABLE X Values of
N
used in the 2006 adjustment
n
N
(
n
S)
N
(
n
P)
1
17
.
855 672 03(1)
2
12
.
032 141 58(1)
0
.
003 300 635(1)
3
10
.
449 809(1)
4
9
.
722 413(1)
−
0
.
000 394 332(1)
6
9
.
031 832(1)
8
8
.
697 639(1)
where
A
(
n
) =
38
45
−
4
3
ln 2
[
N
(
n
S)
−
N
(1S)]
−
337 043
129 600
−
94 261
21 600
n
+
902 609
129 600
n
2
+
4
3
−
16
9
n
+
4
9
n
2
ln
2
2
+
−
76
45
+
304
135
n
−
76
135
n
2
ln 2
+
−
53
15
+
35
2
n
−
419
30
n
2
ζ
(2) ln 2
+
28 003
10 800
−
11
2
n
+
31 397
10 800
n
2
ζ
(2)
+
53
60
−
35
8
n
+
419
120
n
2
ζ
(3)
+
37 793
10 800
+
16
9
ln
2
2
−
304
135
ln 2 + 8
ζ
(2) ln 2
−
13
3
ζ
(2)
−
2
ζ
(3)
[
γ
+
ψ
(
n
)
−
ln
n
]
.
(41)
The term
A
(
n
) makes a small contribution in the range
0.3 to 0.4 for the states under consideration.
The two-loop Bethe logarithms
b
L
in Eq. (40) are
listed in Table XI. The values for
n
= 1 to 6 are from
Jentschura (2004); Pachucki and Jentschura (2003), and
the value at
n
= 8 is obtained by extrapolation of the
calculated values from
n
= 4 to 6 [
b
L
(5S) =
−
60
.
6(8)]
with a function of the form
b
L
(
n
S) =
a
+
b
n
+
c
n
(
n
+ 1)
,
(42)
13
which yields
b
L
(
n
S) =
−
55
.
8
−
24
n
.
(43)
It happens that the ï¬t gives
c
= 0. An estimate for
B
60
given by
B
60
(
n
S) =
b
L
(
n
S) +
10
9
N
(
n
S) +
· · ·
(44)
was derived by Pachucki (2001). The dots represent
uncalculated contributions at the relative level of 15 %
(Pachucki and Jentschura, 2003). Equation (44) gives
B
60
(1S) =
−
61
.
6(9
.
2). However, more recently Yerokhin
et al.
(2003, 2005a,b, 2007) have calculated the 1S-state
two-loop self energy correction for
Z
≥
10. This is ex-
pected to give the main contribution to the higher-order
two-loop correction. Their results extrapolated to
Z
= 1
yield a value for the contribution of all terms of order
B
60
or higher of
−
127
×
(1
±
0
.
3), which corresponds to a
value of roughly
B
60
=
−
129(39), assuming a linear ex-
trapolation from
Z
= 1 to
Z
= 0. This differs by about a
factor of two from the result given by Eq. (44). In view of
this difference between the two calculations, for the 2006
adjustment, we use the average of the two values with an
uncertainty that is half the difference, which gives
B
60
(1S) =
−
95
.
3(0
.
3)(33
.
7)
.
(45)
In Eq. (45), the ï¬rst number in parentheses is the state-
dependent uncertainty
u
n
(
B
60
) associated with the two-
loop Bethe logarithm, and the second number in paren-
theses is the state-independent uncertainty
u
0
(
B
60
) that
is common to all S-state values of
B
60
. Values of
B
60
for
all relevant S-states are given in Table XI. For higher-
l
states,
B
60
has not been calculated, so we take it
to be zero, with uncertainties
u
n
[
B
60
(
n
P)] = 5
.
0 and
u
n
[
B
60
(
n
D)] = 1
.
0. We assume that these uncertain-
ties account for higher-order P and D state uncertainties
as well. For S states, higher-order terms have been es-
timated by Jentschura
et al.
(2005a) with an effective
potential model. They ï¬nd that the next term has a
coefficient of
B
72
and is state independent. We thus as-
sume that the uncertainty
u
0
[
B
60
(
n
S)] is sufficient to ac-
count for the uncertainty due to omitting such a term
and higher-order state-independent terms. In addition,
they ï¬nd an estimate for the state dependence of the next
term, given by
∆
B
71
(
n
S) =
B
71
(
n
S)
−
B
71
(1S) =
Ï€
427
36
−
16
3
ln 2
×
3
4
−
1
n
+
1
4
n
2
+
γ
+
ψ
(
n
)
−
ln
n
(46)
with a relative uncertainty of 50 %. We include this ad-
ditional term, which is listed in Table XI, along with the
estimated uncertainty
u
n
(
B
71
) =
B
71
/
2.
The disagreement of the analytic and numerical calcu-
lations results in an uncertainty of the two-photon contri-
bution that is larger than the estimated uncertainty used
TABLE XI Values of
b
L
,
B
60
, and ∆
B
71
used in the 2006
adjustment
n
b
L
(
n
S)
B
60
(
n
S)
∆
B
71
(
n
S)
1
−
81
.
4(0
.
3)
−
95
.
3(0
.
3)(33
.
7)
2
−
66
.
6(0
.
3)
−
80
.
2(0
.
3)(33
.
7)
16(8)
3
−
63
.
5(0
.
6)
−
77
.
0(0
.
6)(33
.
7)
22(11)
4
−
61
.
8(0
.
8)
−
75
.
3(0
.
8)(33
.
7)
25(12)
6
−
59
.
8(0
.
8)
−
73
.
3(0
.
8)(33
.
7)
28(14)
8
−
58
.
8(2
.
0)
−
72
.
3(2
.
0)(33
.
7)
29(15)
in the 2002 adjustment. As a result, the uncertainties of
the recommended values of the Rydberg constant and
proton and deuteron radii are slightly larger in the 2006
adjustment, although the 2002 and 2006 recommended
values are consistent with each other. On the other hand,
the uncertainty of the 2P state ï¬ne structure is reduced
as a result of the new analytic calculations.
As in the case of the order
α
self-energy and vacuum-
polarization contributions, the dominant effect of the ï¬-
nite mass of the nucleus is taken into account by mul-
tiplying each term of the two-photon contribution by
the reduced-mass factor (
m
r
/m
e
)
3
, except that the mag-
netic moment term, the second line of Eq. (31), is in-
stead multiplied by the factor (
m
r
/m
e
)
2
. In addition,
the argument (
Zα
)
−
2
of the logarithms is replaced by
(
m
e
/m
r
)(
Zα
)
−
2
.
g. Three-photon corrections
The leading contribution
from three virtual photons is expected to have the form
E
(6)
=
α
Ï€
3
(
Zα
)
4
n
3
m
e
c
2
[
C
40
+
C
50
(
Zα
) +
· · ·
]
,
(47)
in analogy with Eq. (29) for two photons. The leading
term
C
40
is (Baikov and Broadhurst, 1995; Eides and
Grotch, 1995a; Laporta and Remiddi, 1996; Melnikov and
14
van Ritbergen, 2000)
C
40
=
−
568 a
4
9
+
85
ζ
(5)
24
−
121
Ï€
2
ζ
(3)
72
−
84 071
ζ
(3)
2304
−
71 ln
4
2
27
−
239
Ï€
2
ln
2
2
135
+
4787
Ï€
2
ln 2
108
+
1591
Ï€
4
3240
−
252 251
Ï€
2
9720
+
679 441
93 312
δ
l
0
+
−
100 a
4
3
+
215
ζ
(5)
24
−
83
Ï€
2
ζ
(3)
72
−
139
ζ
(3)
18
−
25 ln
4
2
18
+
25
Ï€
2
ln
2
2
18
+
298
Ï€
2
ln 2
9
+
239
Ï€
4
2160
−
17 101
Ï€
2
810
−
28 259
5184
1
−
δ
l
0
κ
(2
l
+ 1)
,
(48)
where
a
4
=
P
∞
n
=1
1
/
(2
n
n
4
) = 0
.
517 479 061
. . .
. Higher-
order terms have not been calculated, although partial
results have been obtained (Eides and Shelyuto, 2007).
An uncertainty is assigned by taking
u
0
(
C
50
) = 30
δ
l
0
and
u
n
(
C
63
) = 1, where
C
63
is deï¬ned by the usual con-
vention. The dominant effect of the ï¬nite mass of the
nucleus is taken into account by multiplying the term
proportional to
δ
l
0
by the reduced-mass factor (
m
r
/m
e
)
3
and the term proportional to 1
/
[
κ
(2
l
+ 1)], the magnetic
moment term, by the factor (
m
r
/m
e
)
2
.
The contribution from four photons is expected to be
of order
α
Ï€
4
(
Zα
)
4
n
3
m
e
c
2
,
(49)
which is about 10 Hz for the 1S state and is negligible at
the level of uncertainty of current interest.
h. Finite nuclear size
At low
Z
, the leading contribution
due to the ï¬nite size of the nucleus is
E
(0)
NS
=
E
NS
δ
l
0
,
(50)
with
E
NS
=
2
3
m
r
m
e
3
(
Zα
)
2
n
3
m
e
c
2
ZαR
N
λ
C
2
,
(51)
where
R
N
is the bound-state root-mean-square (rms)
charge radius of the nucleus and
λ
C
is the Compton wave-
length of the electron divided by 2
Ï€
. The leading higher-
order contributions have been examined by Friar (1979b);
Friar and Payne (1997b); Karshenboim (1997) [see also
Borisoglebsky and Troï¬menko (1979); Mohr (1983)]. The
expressions that we employ to evaluate the nuclear size
correction are the same as those discussed in more detail
in CODATA-98.
For S states the leading and next-order corrections are
given by
E
NS
=
E
NS
(
1
−
C
η
m
r
m
e
R
N
λ
C
Zα
−
ln
m
r
m
e
R
N
λ
C
Zα
n
+
ψ
(
n
) +
γ
−
(5
n
+ 9)(
n
−
1)
4
n
2
−
C
θ
(
Zα
)
2
)
,
(52)
where
C
η
and
C
θ
are constants that depend on the details
of the assumed charge distribution in the nucleus. The
values used here are
C
η
= 1
.
7(1) and
C
θ
= 0
.
47(4) for
hydrogen or
C
η
= 2
.
0(1) and
C
θ
= 0
.
38(4) for deuterium.
For the P
1
/
2
states in hydrogen the leading term is
E
NS
=
E
NS
(
Zα
)
2
(
n
2
−
1)
4
n
2
.
(53)
For P
3
/
2
states and D states the nuclear-size contribution
is negligible.
i. Nuclear-size correction to self energy and vacuum polar-
ization
For the self energy, the additional contribution
due to the ï¬nite size of the nucleus is (Eides and Grotch,
1997b; Milstein
et al.
, 2002, 2003a; Pachucki, 1993b)
E
NSE
=
4 ln 2
−
23
4
α
(
Zα
)
E
NS
δ
l
0
,
(54)
and for the vacuum polarization it is (Eides and Grotch,
1997b; Friar, 1979a, 1981; Hylton, 1985)
E
NVP
=
3
4
α
(
Zα
)
E
NS
δ
l
0
.
(55)
For the self-energy term, higher-order size corrections
for S states (Milstein
et al.
, 2002) and size corrections
for P states have been calculated (Jentschura, 2003; Mil-
stein
et al.
, 2003b), but these corrections are negligible
for the current work, and are not included. The D-state
corrections are assumed to be negligible.
j. Radiative-recoil corrections
The dominant effect of nu-
clear motion on the self energy and vacuum polarization
has been taken into account by including appropriate
reduced-mass factors. The additional contributions be-
yond this prescription are termed radiative-recoil effects
with leading terms given by
E
RR
=
m
3
r
m
2
e
m
N
α
(
Zα
)
5
Ï€
2
n
3
m
e
c
2
δ
l
0
×
6
ζ
(3)
−
2
Ï€
2
ln 2 +
35
Ï€
2
36
−
448
27
+
2
3
Ï€
(
Zα
) ln
2
(
Zα
)
−
2
+
· · ·
.
(56)
15
The constant term in Eq. (56) is the sum of the an-
alytic result for the electron-line contribution (Czar-
necki and Melnikov, 2001; Eides
et al.
, 2001a) and
the vacuum-polarization contribution (Eides and Grotch,
1995b; Pachucki, 1995). This term agrees with the nu-
merical value (Pachucki, 1995) used in CODATA-98. The
log-squared term has been calculated by Pachucki and
Karshenboim (1999) and by Melnikov and Yelkhovsky
(1999).
For the uncertainty, we take a term of order
(
Zα
) ln(
Zα
)
−
2
relative to the square brackets in Eq. (56)
with numerical coefficients 10 for
u
0
and 1 for
u
n
. These
coefficients are roughly what one would expect for the
higher-order uncalculated terms. For higher-
l
states in
the present evaluation, we assume that the uncertainties
of the two- and three-photon corrections are much larger
than the uncertainty of the radiative-recoil correction.
Thus, we assign no uncertainty for the radiative-recoil
correction for P and D states.
k. Nucleus self energy
An additional contribution due to
the self energy of the nucleus has been given by Pachucki
(1995):
E
SEN
=
4
Z
2
α
(
Zα
)
4
3
Ï€
n
3
m
3
r
m
2
N
c
2
×
ln
m
N
m
r
(
Zα
)
2
δ
l
0
−
ln
k
0
(
n, l
)
.
(57)
This correction has also been examined by Eides
et al.
(2001b), who consider how it is modiï¬ed by the effect of
structure of the proton. The structure effect would lead
to an additional model-dependent constant in the square
brackets in Eq. (57).
To evaluate the nucleus self-energy correction, we use
Eq. (57) and assign an uncertainty
u
0
that corresponds
to an additive constant of 0.5 in the square brackets for
S states. For P and D states, the correction is small
and its uncertainty, compared to other uncertainties, is
negligible.
l. Total energy and uncertainty
The total energy
E
X
n
L
j
of
a particular level (where L = S, P, ... and
X
= H, D)
is the sum of the various contributions listed above plus
an additive correction
δ
X
n
L
j
that accounts for the uncer-
tainty in the theoretical expression for
E
X
n
L
j
. Our theo-
retical estimate of the value of
δ
X
n
L
j
for a particular level
is zero with a standard uncertainty of
u
(
δ
X
n
L
j
) equal to
the square root of the sum of the squares of the indi-
vidual uncertainties of the contributions; as they are de-
ï¬ned above, the contributions to the energy of a given
level are independent. (Components of uncertainty asso-
ciated with the fundamental constants are not included
here, because they are determined by the least squares
adjustment itself.) Thus, we have for the square of the
uncertainty, or variance, of a particular level
u
2
(
δ
X
n
L
j
) =
X
i
u
2
0
i
(
XLj
) +
u
2
ni
(
XLj
)
n
6
,
(58)
where
the
individual
values
u
0
i
(
XLj
)
/n
3
and
u
ni
(
XLj
)
/n
3
are
the
components
of
uncertainty
from each of the contributions, labeled by
i
, discussed
above. (The factors of 1
/n
3
are isolated so that
u
0
i
(
XLj
)
is explicitly independent of
n
.)
The covariance of any two
δ
’s follows from Eq. (F7) of
Appendix F of CODATA-98. For a given isotope
X
, we
have
u
(
δ
X
n
1
L
j
, δ
X
n
2
L
j
) =
X
i
u
2
0
i
(
XLj
)
(
n
1
n
2
)
3
,
(59)
which follows from the fact that
u
(
u
0
i
, u
ni
) = 0 and
u
(
u
n
1
i
, u
n
2
i
) = 0 for
n
1
6
=
n
2
. We also set
u
(
δ
X
n
1
L
1
j
1
, δ
X
n
2
L
2
j
2
) = 0
,
(60)
if L
1
6
= L
2
or
j
1
6
=
j
2
.
For covariances between
δ
’s for hydrogen and deu-
terium, we have for states of the same
n
u
(
δ
H
n
L
j
, δ
D
n
L
j
)
=
X
i
=
i
c
u
0
i
(HL
j
)
u
0
i
(DL
j
) +
u
ni
(HL
j
)
u
ni
(DL
j
)
n
6
,
(61)
and for
n
1
6
=
n
2
u
(
δ
H
n
1
L
j
, δ
D
n
2
L
j
) =
X
i
=
i
c
u
0
i
(HL
j
)
u
0
i
(DL
j
)
(
n
1
n
2
)
3
,
(62)
where the summation is over the uncertainties common
to hydrogen and deuterium. In most cases, the uncer-
tainties can in fact be viewed as common except for a
known multiplicative factor that contains all of the mass
dependence. We assume
u
(
δ
H
n
1
L
1
j
1
, δ
D
n
2
L
2
j
2
) = 0
,
(63)
if L
1
6
= L
2
or
j
1
6
=
j
2
.
The values of
u
(
δ
X
n
L
j
) of interest for the 2006 adjust-
ment are given in Table XXVIII of Sec. XII, and the non
negligible covariances of the
δ
’s are given in the form
of correlation coefficients in Table XXIX of that section.
These coefficients are as large as 0.9999.
Since the transitions between levels are measured in
frequency units (Hz), in order to apply the above equa-
tions for the energy level contributions we divide the the-
oretical expression for the energy difference ∆
E
of the
transition by the Planck constant
h
to convert it to a
frequency. Further, since we take the Rydberg constant
R
∞
=
α
2
m
e
c/
2
h
(expressed in m
−
1
) rather than the elec-
tron mass
m
e
to be an adjusted constant, we replace the
group of constants
α
2
m
e
c
2
/
2
h
in ∆
E/h
by
cR
∞
.
16
m. Transition frequencies between levels with
n
= 2
As an
indication of the consistency of the theory summarized
above and the experimental data, we list below values of
the transition frequencies between levels with
n
= 2 in
hydrogen. These results are based on values of the con-
stants obtained in a variation of the 2006 least squares
adjustment in which the measurements of the directly
related transitions (items
A
38,
A
39
.
1, and
A
39
.
2 in Ta-
ble XXVIII) are not included, and the weakly coupled
constants
A
r
(e),
A
r
(p),
A
r
(d), and
α
, are assigned their
2006 adjusted values. The results are
ν
H
(2P
1
/
2
−
2S
1
/
2
) = 1 057 843
.
9(2
.
5) kHz
[2
.
3
×
10
−
6
]
ν
H
(2S
1
/
2
−
2P
3
/
2
) = 9 911 197
.
6(2
.
5) kHz
[2
.
5
×
10
−
7
]
ν
H
(2P
1
/
2
−
2P
3
/
2
)
= 10 969 041
.
475(99) kHz
[9
.
0
×
10
−
9
]
,
(64)
which agree well with the relevant experimental results of
Table XXVIII. Although the ï¬rst two values in Eq. (64)
have changed only slightly from the results of the 2002
adjustment, the third value, the ï¬ne-structure splitting,
has an uncertainty that is almost an order-of-magnitude
smaller than the 2002 value, due mainly to improvements
in the theory of the two-photon correction.
A value of the ï¬ne structure constant
α
can be obtained
from the data on the hydrogen and deuterium transi-
tions. This is done by running a variation of the 2006
least-squares adjustment that includes all the transition
frequency data in Table XXVIII and the 2006 adjusted
values of
A
r
(e),
A
r
(p), and
A
r
(d). The resulting value is
α
−
1
= 137
.
036 002(48)
[3
.
5
×
10
−
7
]
,
(65)
which is consistent with the 2006 recommended value,
although substantially less accurate. This result is in-
cluded in Table XXXIV.
2. Experiments on hydrogen and deuterium
Table XII summarizes the transition frequency data
relevant to the determination of
R
∞
. With the excep-
tion of the ï¬rst entry, which is the most recent result for
the 1S
1
/
2
– 2S
1
/
2
transition frequency in hydrogen from
the group at the Max-Planck-Institute f¨
ur Quantenop-
tik (MPQ), Garching, Germany, all of these data are the
same as those used in the 2002 adjustment. Since these
data are reviewed in CODATA-98 or CODATA-02, they
are not discussed here. For a brief discussion of data not
included in Table XII, see Sec. II.B.3 of CODATA-02.
The new MPQ result,
ν
H
(1S
1
/
2
−
2S
1
/
2
) = 2 466 061 413 187
.
074(34) kHz
[1
.
4
×
10
−
14
]
,
(66)
was obtained in the course of an experiment to search
for a temporal variation of the ï¬ne-structure constant
α
(Fischer
et al.
, 2004; H¨
ansch
et al.
, 2005; Poirier
et al.
, 2004; Udem, 2006). It is consistent with, but
has a somewhat smaller uncertainty than, the previ-
ous result from the MPQ group,
ν
H
(1S
1
/
2
−
2S
1
/
2
) =
2
.
466 061 413 187
.
103(46) kHz [1
.
9
×
10
−
14
] (Niering
et al.
,
2000), which was the value used in the 2002 adjustment.
The improvements that led to the reduction in uncer-
tainty include a more stable external reference cavity
for locking the 486 nm cw dye laser, thereby reducing
its linewidth; an upgraded vacuum system that lowered
the background gas pressure in the interaction region,
thereby reducing the background gas pressure shift and
its associated uncertainty; and a signiï¬cantly reduced
within-day Type A (
i.e.,
statistical) uncertainty due to
the narrower laser linewidth and better signal-to-noise
ratio.
The MPQ result in Eq. (66) and Table XII for
ν
H
(1S
1
/
2
−
2S
1
/
2
) was provided by Udem (2006) of
the MPQ group. It follows from the measured value
ν
H
(1S
1
/
2
−
2S
1
/
2
) = 2
.
466 061 102 474
.
851(34) kHz [1
.
4
×
10
−
14
] obtained for the (1S
, F
= 1
, m
F
=
±
1)
−→
(2S
, F
′
= 1
, m
′
F
=
±
1) transition frequency (Fischer
et al.
, 2004; H¨
ansch
et al.
, 2005; Poirier
et al.
, 2004) by
using the well known 1S and 2S hyperï¬ne splittings (Ko-
lachevsky
et al.
, 2004; Ramsey, 1990) to convert it to the
frequency corresponding to the hyperï¬ne centroid.
3. Nuclear radii
The theoretical expressions for the ï¬nite nuclear size
correction to the energy levels of hydrogen H and deu-
terium D (see Sec. IV.A.1.h) are functions of the bound-
state nuclear rms charge radius for the proton,
R
p
, and
for the deuteron,
R
d
. These values are treated as vari-
ables in the adjustment, so the transition frequency data,
together with theory, determine values for the radii. The
radii are also determined by elastic electron-proton scat-
tering data in the case of
R
p
and from elastic electron-
deuteron scattering data in the case of
R
d
. These inde-
pendently determined values are used as additional in-
formation on the radii. There have been no new results
during the last 4 years and thus we take as input data for
these two radii the values used in the 2002 adjustment:
R
p
= 0
.
895(18) fm
(67)
R
d
= 2
.
130(10) fm
.
(68)
The result for
R
p
is due to Sick (2003) [see also Sick
(2007b)]. The result for
R
d
is that given in Sec. III.B.7
of CODATA-98 based on the analysis of Sick and Traut-
mann (1998).
An experiment currently underway to measure the
Lamb shift in muonic hydrogen may eventually provide a
signiï¬cantly improved value of
R
p
and hence an improved
value of
R
∞
(Nebel
et al.
, 2007).
17
TABLE XII Summary of measured transition frequencies
ν
considered in the present work for the determination of the Rydberg
constant
R
∞
(H is hydrogen and D is deuterium).
Authors
Laboratory
Frequency interval(s)
Reported value
Rel. stand.
ν
/kHz
uncert.
u
r
(Fischer
et al.
, 2004)
MPQ
ν
H
(1S
1
/
2
−
2S
1
/
2
)
2 466 061 413 187
.
074(34) 1
.
4
×
10
−
14
(Weitz
et al.
, 1995)
MPQ
ν
H
(2S
1
/
2
−
4S
1
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
2S
1
/
2
)
4 797 338(10)
2
.
1
×
10
−
6
ν
H
(2S
1
/
2
−
4D
5
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
2S
1
/
2
) 6 490 144(24)
3
.
7
×
10
−
6
ν
D
(2S
1
/
2
−
4S
1
/
2
)
−
1
4
ν
D
(1S
1
/
2
−
2S
1
/
2
)
4 801 693(20)
4
.
2
×
10
−
6
ν
D
(2S
1
/
2
−
4D
5
/
2
)
−
1
4
ν
D
(1S
1
/
2
−
2S
1
/
2
) 6 494 841(41)
6
.
3
×
10
−
6
(Huber
et al.
, 1998)
MPQ
ν
D
(1S
1
/
2
−
2S
1
/
2
)
−
ν
H
(1S
1
/
2
−
2S
1
/
2
)
670 994 334
.
64(15)
2
.
2
×
10
−
10
(de Beauvoir
et al.
, 1997)
LKB/SYRTE
ν
H
(2S
1
/
2
−
8S
1
/
2
)
770 649 350 012
.
0(8
.
6)
1
.
1
×
10
−
11
ν
H
(2S
1
/
2
−
8D
3
/
2
)
770 649 504 450
.
0(8
.
3)
1
.
1
×
10
−
11
ν
H
(2S
1
/
2
−
8D
5
/
2
)
770 649 561 584
.
2(6
.
4)
8
.
3
×
10
−
12
ν
D
(2S
1
/
2
−
8S
1
/
2
)
770 859 041 245
.
7(6
.
9)
8
.
9
×
10
−
12
ν
D
(2S
1
/
2
−
8D
3
/
2
)
770 859 195 701
.
8(6
.
3)
8
.
2
×
10
−
12
ν
D
(2S
1
/
2
−
8D
5
/
2
)
770 859 252 849
.
5(5
.
9)
7
.
7
×
10
−
12
(Schwob
et al.
, 1999, 2001)
LKB/SYRTE
ν
H
(2S
1
/
2
−
12D
3
/
2
)
799 191 710 472
.
7(9
.
4)
1
.
2
×
10
−
11
ν
H
(2S
1
/
2
−
12D
5
/
2
)
799 191 727 403
.
7(7
.
0)
8
.
7
×
10
−
12
ν
D
(2S
1
/
2
−
12D
3
/
2
)
799 409 168 038
.
0(8
.
6)
1
.
1
×
10
−
11
ν
D
(2S
1
/
2
−
12D
5
/
2
)
799 409 184 966
.
8(6
.
8)
8
.
5
×
10
−
12
(Bourzeix
et al.
, 1996)
LKB
ν
H
(2S
1
/
2
−
6S
1
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
3S
1
/
2
)
4 197 604(21)
4
.
9
×
10
−
6
ν
H
(2S
1
/
2
−
6D
5
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
3S
1
/
2
) 4 699 099(10)
2
.
2
×
10
−
6
(Berkeland
et al.
, 1995)
Yale
ν
H
(2S
1
/
2
−
4P
1
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
2S
1
/
2
) 4 664 269(15)
3
.
2
×
10
−
6
ν
H
(2S
1
/
2
−
4P
3
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
2S
1
/
2
) 6 035 373(10)
1
.
7
×
10
−
6
(Hagley and Pipkin, 1994)
Harvard
ν
H
(2S
1
/
2
−
2P
3
/
2
)
9 911 200(12)
1
.
2
×
10
−
6
(Lundeen and Pipkin, 1986) Harvard
ν
H
(2P
1
/
2
−
2S
1
/
2
)
1 057 845
.
0(9
.
0)
8
.
5
×
10
−
6
(Newton
et al.
, 1979)
U. Sussex
ν
H
(2P
1
/
2
−
2S
1
/
2
)
1 057 862(20)
1
.
9
×
10
−
5
B. Antiprotonic helium transition frequencies and
A
r
(e)
The antiprotonic helium atom is a three-body system
consisting of a
4
He or
3
He nucleus, an antiproton, and
an electron, denoted by ¯
p He
+
. Even though the Bohr
radius for the antiproton in the ï¬eld of the nucleus is
about 1836 times smaller than the electron Bohr radius,
in the highly-excited states studied experimentally, the
average orbital radius of the antiproton is comparable
to the electron Bohr radius, giving rise to relatively long-
lived states. Also, for the high-
l
states studied, because of
the vanishingly small overlap of the antiproton wavefunc-
tion with the helium nucleus, strong interactions between
the antiproton and the nucleus are negligible.
One of the goals of the experiments is to measure the
antiproton-electron mass ratio. However, since we as-
sume that
CP T
is a valid symmetry, for the purpose of
the least squares adjustment we take the masses of the
antiproton and proton to be equal and use the data to de-
termine the proton-electron mass ratio. Since the proton
mass is known more accurately than the electron mass
from other experiments, the mass ratio yields informa-
tion primarily on the electron mass. Other experiments
have demonstrated the equality of the charge-to-mass ra-
tio of p and ¯
p to within 9 parts in 10
11
; see Gabrielse
(2006).
1. Theory relevant to antiprotonic helium
Calculations of transition frequencies of antiprotonic
helium have been done by Kino
et al.
(2003) and by Ko-
robov (2003, 2005). The uncertainties of calculations by
Korobov (2005) are of the order of 1 MHz to 2 MHz,
while the uncertainties and scatter relative to the ex-
perimental values of the results of Kino
et al.
(2003) are
substantially larger, so we use the results Korobov (2005)
in the 2006 adjustment. [See also the remarks in Hayano
(2007) concerning the theory.]
The dominant contribution to the energy levels is just
the non-relativistic solution of the Schr¨odinger equation
for the three-body system together with relativistic and
radiative corrections treated as perturbations. The non-
relativistic levels are resonances, because the states can
decay by the Auger effect in which the electron is ejected.
Korobov (2005) calculates the nonrelativistic energy by
using one of two formalisms, depending on whether the
Auger rate is small or large. In the case where the rate
is small, the Feshbach formalism is used with an optical
potential. The optical potential is omitted in the calcula-
tion of higher-order relativistic and radiative corrections.
For broad resonances with a higher Auger rate, the non-
relativistic energies are calculated with the Complex Co-
ordinate rotation method. In checking the convergence of
18
the nonrelativistic levels, attention was paid to the con-
vergence of the expectation value of the the delta func-
tion operators used in the evaluation of the relativistic
and radiative corrections.
Korobov (2005) evaluated the relativistic and radia-
tive corrections as perturbations to the nonrelativistic
levels, including relativistic corrections of order
α
2
R
∞
,
anomalous magnetic moment corrections of order
α
3
R
∞
and higher, one-loop self-energy and vacuum-polarization
corrections of order
α
3
R
∞
, higher-order one-loop and
leading two-loop corrections of order
α
4
R
∞
.
Higher-
order relativistic corrections of order
α
4
R
∞
and radiative
corrections of order
α
5
R
∞
were estimated with effective
operators. The uncertainty estimates account for uncal-
culated terms of order
α
5
ln
α R
∞
.
Transition frequencies obtained by Korobov (2005,
2006) using the CODATA-02 values of the relevant con-
stants are listed in Table XIII under the column header
“Calculated Value.†We denote these values of the fre-
quencies by
ν
(0)
¯
p He
(
n, l
:
n
′
, l
′
), where He is either
3
He
+
or
4
He
+
. Also calculated are the leading-order changes
in the theoretical values of the transition frequencies as
a function of the relative changes in the mass ratios
A
r
(¯
p)
/A
r
(e) and
A
r
(
N
)
/A
r
(¯
p); here
N
is either
3
He
2+
or
4
He
2+
. If we denote the transition frequencies as func-
tions of these mass ratios by
ν
¯
p He
(
n, l
:
n
′
, l
′
), then the
changes can be written as
a
¯
p He
(
n, l
:
n
′
, l
′
) =
A
r
(¯
p)
A
r
(e)
(0)
∂ν
¯
p He
(
n, l
:
n
′
, l
′
)
∂
A
r
(¯
p)
A
r
(e)
(69)
b
¯
p He
(
n, l
:
n
′
, l
′
) =
A
r
(
He
)
A
r
(¯
p)
(0)
∂ν
¯
p He
(
n, l
:
n
′
, l
′
)
∂
A
r
(
N
)
A
r
(¯
p)
.
(70)
Values of these derivatives, in units of 2
cR
∞
, are listed in
Table XIII in the columns with the headers “
a
†and “
b
,â€
respectively. The zero-order frequencies and the deriva-
tives are used in the expression
ν
¯
p He
(
n, l
:
n
′
, l
′
) =
ν
(0)
¯
p He
(
n, l
:
n
′
, l
′
)
+
a
¯
p He
(
n, l
:
n
′
, l
′
)
"
A
r
(e)
A
r
(¯
p)
(0)
A
r
(¯
p )
A
r
(e)
−
1
#
(71)
+
b
¯
p He
(
n, l
:
n
′
, l
′
)
"
A
r
(¯
p)
A
r
(
N
)
(0)
A
r
(
N
)
A
r
(¯
p)
−
1
#
+
. . . ,
which provides a ï¬rst-order approximation to the tran-
sition frequencies as a function of changes to the mass
ratios. This expression is used to incorporate the ex-
perimental data and the calculations for the antiprotonic
system as a function of the mass ratios into the least-
squares adjustment. It should be noted that even though
the mass ratios are the independent variables in Eq. (71)
and the atomic relative masses
A
r
(e),
A
r
(p ), and
A
r
(
N
)
are the adjusted constants in the 2006 least-squares ad-
justment, the primary effect of including this data in
the adjustment is on the electron relative atomic mass,
because independent data in the adjustment constrains
the proton and helium nuclei relative atomic masses with
smaller uncertainties.
The uncertainties in the theoretical expressions for the
transition frequencies are included in the adjustment as
additive constants
δ
¯
p He
(
n, l
:
n
′
, l
′
). Values for the theo-
retical uncertainties and covariances used in the adjust-
ment are given in Sec. XII, Tables XXXII and XXXIII,
respectively (Korobov, 2006).
2. Experiments on antiprotonic helium
Experimental work on antiprotonic helium began in
the early 1990s and it continues to be an active ï¬eld of re-
search; a comprehensive review through 2000 is given by
Yamazaki
et al.
(2002) and a very concise review through
2006 by Hayano (2007). The ï¬rst measurements of ¯
p He
+
transition frequencies at CERN with
u
r
<
10
−
6
were re-
ported in 2001 (Hori
et al.
, 2001), improved results were
reported in 2003 (Hori
et al.
, 2003), and transition fre-
quencies with uncertainties sufficiently small that they
can, together with the theory of the transitions, provide
a competitive value of
A
r
(e), were reported in 2006 (Hori
et al.
, 2006).
The 12 transition frequencies—seven for
4
He and ï¬ve
for
3
He given by Hori
et al.
(2006)—which we take as
input data in the 2006 adjustment are listed in column
2 of Table XIII with the corresponding transitions indi-
cated in column 1. To reduce rounding errors, an addi-
tional digit for both the frequencies and their uncertain-
ties as provided by Hori (2006) have been included. All
twelve frequencies are correlated; their correlation coef-
ï¬cients, based on detailed uncertainty budgets for each,
also provided by Hori (2006), are given in Table XXXIII
in Sec XII.
In the current version of the experiment, 5.3 MeV an-
tiprotons from the CERN Antiproton Decelerator (AD)
are decelerated using a radio-frequency quadrupole decel-
erator (RFQD) to energies in the range 10 keV to 120 keV
controlled by a dc potential bias on the RFQD’s elec-
trodes. The decelerated antiprotons, about 30 % of the
antiprotons entering the RFQD, are then diverted to a
low pressure cryogenic helium gas target at 10 K by an
achromatic momentum analyzer, the purpose of which
is to eliminate the large background that the remaining
70 % of undecelerated antiprotons would have produced.
About 3 % of the ¯
p stopped in the target form ¯
p He
+
, in
which a ¯
p with large principle quantum number (
n
≈
38)
and angular momentum quantum number (
l
≈
n
) cir-
culates in a localized, nearly circular orbit around the
He
2+
nucleus while the electron occupies the distributed
1S state. These ¯
p energy levels are metastable with life-
times of several microseconds and de-excite radiatively.
There are also short lived ¯
p states with similar values of
n
19
TABLE XIII Summary of data related to the determination of
A
r
(e) from measurements on antiprotonic helium
Transition
Experimental
Calculated
a
b
(
n, l
)
→
(
n
′
, l
′
)
Value (MHz)
Value (MHz)
(2
cR
∞
)
(2
cR
∞
)
¯
p
4
He
+
: (32
,
31)
→
(31
,
30)
1 132 609 209(15)
1 132 609 223
.
50(82)
0
.
2179
0
.
0437
¯
p
4
He
+
: (35
,
33)
→
(34
,
32)
804 633 059
.
0(8
.
2)
804 633 058
.
0(1
.
0)
0
.
1792
0
.
0360
¯
p
4
He
+
: (36
,
34)
→
(35
,
33)
717 474 004(10)
717 474 001
.
1(1
.
2)
0
.
1691
0
.
0340
¯
p
4
He
+
: (37
,
34)
→
(36
,
33)
636 878 139
.
4(7
.
7)
636 878 151
.
7(1
.
1)
0
.
1581
0
.
0317
¯
p
4
He
+
: (39
,
35)
→
(38
,
34)
501 948 751
.
6(4
.
4)
501 948 755
.
4(1
.
2)
0
.
1376
0
.
0276
¯
p
4
He
+
: (40
,
35)
→
(39
,
34)
445 608 557
.
6(6
.
3)
445 608 569
.
3(1
.
3)
0
.
1261
0
.
0253
¯
p
4
He
+
: (37
,
35)
→
(38
,
34)
412 885 132
.
2(3
.
9)
412 885 132
.
8(1
.
8)
−
0
.
1640
−
0
.
0329
¯
p
3
He
+
: (32
,
31)
→
(31
,
30)
1 043 128 608(13)
1 043 128 579
.
70(91)
0
.
2098
0
.
0524
¯
p
3
He
+
: (34
,
32)
→
(33
,
31)
822 809 190(12)
822 809 170
.
9(1
.
1)
0
.
1841
0
.
0460
¯
p
3
He
+
: (36
,
33)
→
(35
,
32)
646 180 434(12)
646 180 408
.
2(1
.
2)
0
.
1618
0
.
0405
¯
p
3
He
+
: (38
,
34)
→
(37
,
33)
505 222 295
.
7(8
.
2)
505 222 280
.
9(1
.
1)
0
.
1398
0
.
0350
¯
p
3
He
+
: (36
,
34)
→
(37
,
33)
414 147 507
.
8(4
.
0)
414 147 509
.
3(1
.
8)
−
0
.
1664
−
0
.
0416
and
l
but with lifetimes on the order of 10 ns and which
de-excite by Auger transitions to form ¯
p He
2+
hydrogen-
like ions. These undergo Stark collisions, which cause the
rapid annihilation of the ¯
p in the helium nucleus. The
annihilation rate vs. time elapsed since ¯
p He
+
formation,
or delayed annihilation time spectrum (DATS), is mea-
sured using Cherenkov counters.
With the exception of the (36
,
34)
→
(35
,
33) transi-
tion frequency, all of the frequencies given in Table XIII
were obtained by stimulating transitions from the ¯
p He
+
metastable states with values of
n
and
l
indicated in col-
umn one on the left-hand side of the arrow to the short
lived, Auger-decaying states with values of
n
and
l
indi-
cated on the right-hand side of the arrow.
The megawatt-scale light intensities needed to induce
the ¯
p He
+
transitions, which cover the wavelength range
265 nm to 726 nm, can only be provided by a pulsed laser.
Frequency and linewidth fluctuations and frequency cal-
ibration problems associated with such lasers were over-
come by starting with a cw “seed†laser beam of fre-
quency
ν
cw
, known with
u
r
<
4
×
10
−
10
through its sta-
bilization by an optical frequency comb, and then ampli-
fying the intensity of the laser beam by a factor of 10
6
in
a cw pulse ampliï¬er consisting of three dye cells pumped
by a pulsed Nd:YAG laser. The 1 W seed laser beam with
wavelength in the range 574 nm to 673 nm was obtained
from a pumped cw dye laser, and the 1 W seed laser beam
with wavelength in the range 723 nm to 941 nm was ob-
tained from a pumped cw Ti:sapphire laser. The shorter
wavelengths (265 nm to 471 nm) for inducing transitions
were obtained by frequency doubling the ampliï¬er out-
put at 575 nm and 729 nm to 941 nm or by frequency
tripling its 794 nm output. The frequency of the seed
laser beam
ν
cw
, and thus the frequency
ν
pl
of the pulse
ampliï¬ed beam, was scanned over a range of
±
4 GHz
around the ¯
p He
+
transition frequency by changing the
repetition frequency
f
rep
of the frequency comb.
The resonance curve for a transition was obtained by
plotting the area under the resulting DATS peak vs.
ν
pl
.
Because of the approximate 400 MHz Doppler broaden-
ing of the resonance due to the 10 K thermal motion of
the ¯
p He
+
atoms, a rather sophisticated theoretical line
shape that takes into account many factors must be used
to obtained the desired transition frequency.
Two other effects of major importance are the so-called
chirp effect and linear shifts in the transition frequencies
due to collisions between the ¯
p He
+
and background he-
lium atoms. The frequency
ν
pl
can deviate from
ν
cw
due
to sudden changes in the index of refraction of the dye
in the cells of the ampliï¬er. This chirp, which can be
expressed as ∆
ν
c
(
t
) =
ν
pl
(
t
)
−
ν
cw
, can shift the mea-
sured ¯
p He
+
frequencies from their actual values. Hori
et al.
(2006) eliminated this effect by measuring ∆
ν
c
(
t
)
in real time and applying a frequency shift to the seed
laser, thereby canceling the dye-cell chirp. This effect is
the predominant contributor to the correlations among
the 12 transitions (Hori, 2006). The collisional shift was
eliminated by measuring the frequencies of ten transi-
tions in helium gas targets with helium atom densities
Ï
in the range 2
×
10
18
/
cm
3
to 3
×
10
21
/
cm
3
to determine
dν/dÏ
. The
in vacuo
(
Ï
= 0) values were obtained by
applying a suitable correction in the range
−
14 MHz to
1 MHz to the initially measured frequencies obtained at
Ï
≈
2
×
10
18
/
cm
3
.
In contrast to the other 11 transition frequencies in
Table XIII, which were obtained by inducing a transi-
tion from a long-lived, metastable state to a short-lived,
Auger-decaying state, the (36
,
34)
→
(35
,
33) transition
frequency was obtained by inducing a transition from
the (36, 34) metastable state to the (35, 33) metastable
state using three different lasers.
This was done by
ï¬rst depopulating at time
t
1
the (35, 33) metastable
state by inducing the (35
,
33)
→
(34
,
32) metastable-state
to short-lived-state transition, then at time
t
2
inducing
the (36
,
34)
→
(35
,
33) transition using the cw pulse-
ampliï¬ed laser, and then at time
t
3
again inducing the
(35
,
33)
→
(34
,
32) transition. The resonance curve for
the (36
,
34)
→
(35
,
33) transition was obtained from the
DATS peak resulting from this last induced transition.
The 4 MHz to 15 MHz standard uncertainties of the
20
transition frequencies in Table XIII arise from the reso-
nance line shape ï¬t (3 MHz to 13 MHz, statistical or Type
A), not completely eliminating the chirp effect (2 MHz
to 4 MHz, nonstatistical or Type B), collisional shifts
(0.1 MHz to 2 MHz, Type B), and frequency doubling or
tripling (1 MHz to 2 MHz, Type B).
3. Values of
A
r
(e)
inferred from antiprotonic helium
From the theory of the 12 antiprotonic transition fre-
quencies discussed in Sec IV.B.1, the 2006 recommended
values of the relative atomic masses of the proton, al-
pha particle (nucleus of the
4
He atom), and the helion
(nucleus of the
3
He atom),
A
r
(p),
A
r
(alpha), and
A
r
(h),
respectively, together with the 12 experimental values for
these frequencies given in Table XIII, we ï¬nd the follow-
ing three values for
A
r
(e) from the seven ¯
p
4
He
+
frequen-
cies alone, from the ï¬ve ¯
p
3
He
+
frequencies alone, and
from the 12 frequencies together:
A
r
(e) = 0
.
000 548 579 9103(12) [2
.
1
×
10
−
9
]
(72)
A
r
(e) = 0
.
000 548 579 9053(15) [2
.
7
×
10
−
9
]
(73)
A
r
(e) = 0
.
000 548 579 908 81(91) [1
.
7
×
10
−
9
]
.
(74)
The separate inferred values from the ¯
p
4
He
+
and ¯
p
3
He
+
frequencies differ somewhat, but the value from all 12
frequencies not only agrees with the three other available
results for
A
r
(e) (see Table XXXVI, Sec XII.A), but has
a competitive level of uncertainty as well.
C. Hyperfine structure and fine structure
1. Hyperfine structure
Because the ground-state hyperï¬ne transition frequen-
cies ∆
ν
H
, ∆
ν
Mu
, and ∆
ν
Ps
of the comparatively sim-
ple atoms hydrogen, muonium, and positronium, respec-
tively, are proportional to
α
2
R
∞
c
, in principle a value of
α
can be obtained by equating an experimental value of
one of these transition frequencies to its presumed read-
ily calculable theoretical expression. However, currently
only measurements of ∆
ν
Mu
and the theory of the muon-
ium hyperï¬ne structure have sufficiently small uncertain-
ties to provide a useful result for the 2006 adjustment,
and even in this case the result is not a competitive value
of
α
, but rather the most accurate value of the electron-
muon mass ratio
m
e
/m
µ
. Indeed, we discuss the relevant
experiments and theory in Sec.VI.B.
Although the ground-state hyperï¬ne transition fre-
quency of hydrogen has long been of interest as a po-
tential source of an accurate value of
α
because it is ex-
perimentally known with
u
r
≈
10
−
12
(Ramsey, 1990),
the relative uncertainty of the theory is still of the or-
der of 10
−
6
. Thus, ∆
ν
H
cannot yet provide a competi-
tive value of the ï¬ne-structure constant. At present, the
main sources of uncertainty in the theory arise from the
internal structure of the proton, namely (i) the electric
charge and magnetization densities of the proton, which
are taken into account by calculating the proton’s so-
called Zemach radius; and (ii) the polarizability of the
proton (that is, protonic excited states). For details of
the progress made over the last four years in reducing
the uncertainties from both sources, see (Carlson, 2007;
Pachucki, 2007; Sick, 2007a) and the references cited
therein. Because the muon is a structureless point-like
particle, the theory of ∆
ν
Mu
is free of such uncertainties.
It is also not yet possible to obtain a useful value of
α
from ∆
ν
Ps
since the most accurate experimental result
has
u
r
= 3
.
6
×
10
−
6
(Ritter
et al.
, 1984). The uncertainty
of the theory of ∆
ν
Ps
is not signiï¬cantly smaller and may
in fact be larger (Adkins
et al.
, 2002; Penin, 2004).
2. Fine structure
As in the case of hyperï¬ne splittings, ï¬ne-structure
transition frequencies are proportional to
α
2
R
∞
c
and
could be used to deduce a value of
α
. Some data re-
lated to the ï¬ne structure of hydrogen and deuterium are
discussed in Sec. IV.A.2 in connection with the Rydberg
constant. They are included in the adjustment because of
their influence on the adjusted value of
R
∞
. However, the
value of
α
that can be derived from these data is not com-
petitive; see Eq. (65). See also Sec. III.B.3 of CODATA-
02 for a discussion of why earlier ï¬ne structure-related
results in H and D are not considered.
Because the transition frequencies corresponding to
the differences in energy of the three 2
3
P levels of
4
He
can be both measured and calculated with reasonable ac-
curacy, the ï¬ne structure of
4
He has long been viewed as
a potential source of a reliable value of
α
. The three fre-
quencies of interest are
ν
01
≈
29
.
6 GHz,
ν
12
≈
2
.
29 GHz,
and
ν
02
≈
31
.
9 GHz, which correspond to the intervals
2
3
P
1
−
2
3
P
0
,
2
3
P
2
−
2
3
P
1
, and 2
3
P
2
−
2
3
P
0
, respectively.
The value with the smallest uncertainty for any of these
frequencies was obtained at Harvard (Zelevinsky
et al.
,
2005):
ν
01
= 29 616 951
.
66(70) kHz
[2
.
4
×
10
−
8
]
.
(75)
It is consistent with the value of
ν
01
reported by George
et al.
(2001) with
u
r
= 3
.
0
×
10
−
8
, and that reported
by Giusfredi
et al.
(2005) with
u
r
= 3
.
4
×
10
−
8
. If the
theoretical expression for
ν
01
were exactly known, the
weighted mean of the three results would yield a value of
α
with
u
r
≈
8
×
10
−
9
.
However, as discussed in CODATA-02, the theory of
the 2
3
P
J
transition frequencies is far from satisfactory.
First, different calculations disagree, and because of the
considerable complexity of the calculations and the his-
tory of their evolution, there is general agreement that re-
sults that have not been conï¬rmed by independent evalu-
ation should be taken as tentative. Second, there are sig-
niï¬cant disagreements between theory and experiment.
Recently, Pachucki (2006) has advanced the theory by
21
calculating the complete contribution to the 2
3
P
J
ï¬ne-
structure levels of order
mα
7
(or
α
5
Ryd), with the ï¬nal
theoretical result for
ν
01
being
ν
01
= 29 616 943
.
01(17) kHz
[5
.
7
×
10
−
9
]
.
(76)
This value disagrees with the experimental value given
in Eq (75) as well as with the theoretical value
ν
01
=
29 616 946
.
42(18) kHz [6
.
1
×
10
−
9
] given by Drake (2002),
which also disagrees with the experimental value. These
disagreements suggest that there is a problem with the-
ory and/or experiment which must be resolved before a
meaningful value of
α
can be obtained from the helium
ï¬ne structure (Pachucki, 2006). Therefore, as in the 2002
adjustment, we do not include
4
He ï¬ne-structure data in
the 2006 adjustment.
V. MAGNETIC MOMENT ANOMALIES AND
g
-FACTORS
In this section, the theory and experiment for the mag-
netic moment anomalies of the free electron and muon
and the bound-state
g
-factor of the electron in hydro-
genic carbon (
12
C
5+
) and in hydrogenic oxygen (
16
O
7+
)
are reviewed.
The magnetic moment of any of the three charged lep-
tons
â„“
= e
,
µ
,
Ï„
is written as
µ
â„“
=
g
â„“
e
2
m
â„“
s
,
(77)
where
g
â„“
is the
g
-factor of the particle,
m
â„“
is its mass,
and
s
is its spin. In Eq. (77),
e
is the elementary charge
and is positive. For the negatively charged leptons
â„“
−
,
g
â„“
is negative, and for the corresponding antiparticles
â„“
+
,
g
â„“
is positive.
CP T
invariance implies that the masses
and absolute values of the
g
-factors are the same for each
particle-antiparticle pair. These leptons have eigenvalues
of spin projection
s
z
=
±
¯
h/
2, and it is conventional to
write, based on Eq. (77),
µ
â„“
=
g
â„“
2
e
¯
h
2
m
â„“
,
(78)
where in the case of the electron,
µ
B
=
e
¯
h/
2
m
e
is the
Bohr magneton.
The free lepton magnetic moment anomaly
a
â„“
is de-
ï¬ned as
|
g
â„“
|
= 2(1 +
a
â„“
)
,
(79)
where
g
D
=
−
2 is the value predicted by the free-electron
Dirac equation. The theoretical expression for
a
â„“
may be
written as
a
â„“
(th) =
a
â„“
(QED) +
a
â„“
(weak) +
a
â„“
(had)
,
(80)
where the terms denoted by QED, weak, and had account
for the purely quantum electrodynamic, predominantly
electroweak, and predominantly hadronic (that is, strong
interaction) contributions to
a
â„“
, respectively.
The QED contribution may be written as (Kinoshita
et al.
, 1990)
a
â„“
(QED) =
A
1
+
A
2
(
m
â„“
/m
â„“
′
) +
A
2
(
m
â„“
/m
â„“
′′
)
+
A
3
(
m
â„“
/m
â„“
′
, m
â„“
/m
â„“
′′
)
,
(81)
where for the electron, (
â„“, â„“
′
, â„“
′′
) = (e
,
µ
,
Ï„
), and for the
muon, (
â„“, â„“
′
, â„“
′′
) = (
µ
,
e
,
Ï„
). The anomaly for the
Ï„
,
which is poorly known experimentally (Yao
et al.
, 2006),
is not considered here. For recent work on the theory of
a
Ï„
, see Eidelman and Passera (2007). In Eq. (81), the
term
A
1
is mass independent, and the mass dependence
of
A
2
and
A
3
arises from vacuum polarization loops with
lepton
â„“
′
,
â„“
′′
, or both. Each of the four terms on the
right-hand side of Eq. (81) can be expressed as a power
series in the ï¬ne-structure constant
α
:
A
i
=
A
(2)
i
α
Ï€
+
A
(4)
i
α
Ï€
2
+
A
(6)
i
α
Ï€
3
+
A
(8)
i
α
Ï€
4
+
A
(10)
i
α
Ï€
5
+
· · ·
,
(82)
where
A
(2)
2
=
A
(2)
3
=
A
(4)
3
= 0. Coefficients proportional
to (
α/
Ï€
)
n
are of order
e
2
n
and are referred to as 2
n
th-
order coefficients.
The second-order coefficient is known exactly, and the
fourth- and sixth-order coefficients are known analyti-
cally in terms of readily evaluated functions:
A
(2)
1
=
1
2
(83)
A
(4)
1
=
−
0
.
328 478 965 579
. . .
(84)
A
(6)
1
= 1
.
181 241 456
. . . .
(85)
A total of 891 Feynman diagrams give rise to the mass-
independent eighth-order coefficient
A
(8)
1
, and only a few
of these are known analytically. However, in an effort
that has its origins in the 1960s, Kinoshita and collab-
orators have calculated all of
A
(8)
1
numerically, with the
result of this ongoing project that was used in the 2006
adjustment being (Gabrielse
et al.
, 2006, 2007; Kinoshita
and Nio, 2006a)
A
(8)
1
=
−
1
.
7283(35)
.
(86)
Work was done in the evaluation and checking of this
coefficient in an effort to obtain a reliable quantitative re-
sult. A subset of 373 diagrams containing closed electron
loops was veriï¬ed by more than one independent formu-
lation. The remaining 518 diagrams with no closed elec-
tron loops were formulated in only one way. As a check
on this set, extensive cross checking was performed on the
renormalization terms both among themselves and with
lower-order diagrams that are known exactly (Kinoshita
and Nio, 2006a) [see also Gabrielse
et al.
(2006, 2007)].
For the ï¬nal numerical integrations, an adaptive-iterative
Monte Carlo routine was used. A time-consuming part
22
TABLE XIV Summary of data related to magnetic moments of the electron and muon and inferred values of the ï¬ne structure
constant. (The source data and not the inferred values given here are used in the adjustment.)
Quantity
Value
Relative standard
Identiï¬cation
Sect. and Eq.
uncertainty
u
r
a
e
1
.
159 652 1883(42)
×
10
−
3
3
.
7
×
10
−
9
UWash-87
V.A.2.a (102)
α
−
1
(
a
e
)
137
.
035 998 83(50)
3
.
7
×
10
−
9
V.A.3 (104)
a
e
1
.
159 652 180 85(76)
×
10
−
3
6
.
6
×
10
−
10
HarvU-06
V.A.2.b (103)
α
−
1
(
a
e
)
137
.
035 999 711(96)
7
.
0
×
10
−
10
V.A.3 (105)
R
0
.
003 707 2064(20)
5
.
4
×
10
−
7
BNL-06
V.B.2 (128)
a
µ
1
.
165 920 93(63)
×
10
−
3
5
.
4
×
10
−
7
V.B.2 (129)
α
−
1
(
R
)
137
.
035 67(26)
1
.
9
×
10
−
6
V.B.2.a (132)
of the work was checking for round-off error in the inte-
gration.
The 0
.
0035 standard uncertainty of
A
(8)
1
contributes a
standard uncertainty to
a
e
(th) of 0
.
88
×
10
−
10
a
e
, which is
smaller than the uncertainty due to uncalculated higher-
order contributions. Independent work is in progress on
analytic calculations of eighth-order integrals. See, for
example, Laporta (2001); Laporta
et al.
(2004); Mastrolia
and Remiddi (2001).
Little is known about the tenth-order coefficient
A
(10)
1
and higher-order coefficients, although Kinoshita
et al.
(2006) are starting the numerical evaluation of the 12 672
Feynman diagrams for this coefficient. To evaluate the
contribution to the uncertainty of
a
e
(th) due to lack of
knowledge of
A
(10)
1
, we follow CODATA-98 to obtain
A
(10)
1
= 0
.
0(3
.
7). The 3
.
7 standard uncertainty of
A
(10)
1
contributes a standard uncertainty component to
a
e
(th)
of 2
.
2
×
10
−
10
a
e
; the uncertainty contributions to
a
e
(th)
from all other higher-order coefficients, which should be
signiï¬cantly smaller, are assumed to be negligible.
The 2006 least-squares adjustment was carried out us-
ing the theoretical results given above, including the
value of
A
(8)
1
given in Eq. (86). Well after the dead-
line for new data and the recommended values from the
adjustment were made public (Mohr
et al.
, 2007), it was
discovered by Aoyama
et al.
(2007) that 2 of the 47 inte-
grals representing 518 QED diagrams that had not previ-
ously been conï¬rmed independently required a corrected
treatment of infrared divergences. The revised value they
give is
A
(8)
1
=
−
1
.
9144(35)
,
(87)
although the new calculation is still tentative (Aoyama
et al.
, 2007). This result would lead to the value
α
−
1
= 137
.
035 999 070(98)
[7
.
1
×
10
−
10
] (88)
for the inverse ï¬ne-structure constant derived from the
electron anomaly using the Harvard measurement result
for
a
e
(Gabrielse
et al.
, 2006, 2007). This number is
shifted down from the previous result by 641
×
10
−
9
and its uncertainty is increased from (96) to (98) (see
Sec. V.A.3), but it is still consistent with the values ob-
tained from recoil experiments (see Table XXVI). If this
result for
A
(8)
1
had been used in the 2006 adjustment,
the recommended value of the inverse ï¬ne-structure con-
stant would differ by a similar, although slightly smaller,
change. The effect on the muon anomaly theory is com-
pletely negligible.
The mass independent term
A
1
contributes equally to
the free electron and muon anomalies and the bound-
electron
g
-factors. The mass-dependent terms are differ-
ent for the electron and muon and are considered sepa-
rately in the following. For the bound-electron
g
-factor,
there are bound-state corrections in addition to the free-
electron value of the
g
-factor, as discussed below.
A. Electron magnetic moment anomaly
a
e
and the
fine-structure constant
α
The combination of theory and experiment for the elec-
tron magnetic moment anomaly yields the value for the
ï¬ne-structure constant
α
with the smallest estimated un-
certainty (see Table XIV for the values corresponding to
the 2006 adjustment).
1. Theory of
a
e
The mass-dependent coefficients of interest and cor-
responding contributions to the theoretical value of the
anomaly
a
e
(th), based on the 2006 recommended values
of the mass ratios, are
23
A
(4)
2
(
m
e
/m
µ
) = 5
.
197 386 78(26)
×
10
−
7
→
24
.
182
×
10
−
10
a
e
(89)
A
(4)
2
(
m
e
/m
Ï„
) = 1
.
837 63(60)
×
10
−
9
→
0
.
085
×
10
−
10
a
e
(90)
A
(6)
2
(
m
e
/m
µ
) =
−
7
.
373 941 72(27)
×
10
−
6
→ −
0
.
797
×
10
−
10
a
e
(91)
A
(6)
2
(
m
e
/m
Ï„
) =
−
6
.
5819(19)
×
10
−
8
→ −
0
.
007
×
10
−
10
a
e
,
(92)
where the standard uncertainties of the coefficients are
due to the uncertainties of the mass ratios, which are
negligible. The contributions from
A
(6)
3
(
m
e
/m
µ
, m
e
/m
Ï„
)
and all higher-order mass-dependent terms are negligible
as well.
The value for
A
(6)
2
(
m
e
/m
µ
) in Eq. (91) has been up-
dated from the value in CODATA-02 and is in agreement
with the result of Passera (2007) based on a calculation
to all orders in the mass ratio. The change is given by
the term
17
x
6
ζ
(3)
36
−
4381
x
6
ln
2
x
30240
+
24761
x
6
ln
x
158760
−
13
Ï€
2
x
6
1344
−
1840256147
x
6
3556224000
,
(93)
where
x
=
m
e
/m
µ
, which was not included in CODATA-
02. The earlier result was based on Eq. (4) of Laporta
and Remiddi (1993), which only included terms to order
x
4
. The additional term was kindly provided by Laporta
and Remiddi (2006).
For the electroweak contribution we have
a
e
(weak) = 0
.
029 73(52)
×
10
−
12
= 0
.
2564(45)
×
10
−
10
a
e
,
(94)
as calculated in CODATA-98 but with the current values
of
G
F
and sin
2
θ
W
(see Sec. XI.B).
The hadronic contribution is
a
e
(had) = 1
.
682(20)
×
10
−
12
= 1
.
450(17)
×
10
−
9
a
e
.
(95)
It is the sum of the following three contributions:
a
(4)
e
(had) = 1
.
875(18)
×
10
−
12
obtained by Davier and
H¨
ocker (1998);
a
(6
a
)
e
(had) =
−
0
.
225(5)
×
10
−
12
given by
Krause (1997); and
a
(
γγ
)
e
(had) = 0
.
0318(58)
×
10
−
12
cal-
culated by multiplying the corresponding result for the
muon given in Sec. V.B.1 by the factor (
m
e
/m
µ
)
2
, since
a
(
γγ
)
e
(had) is assumed to vary approximately as the square
of the mass.
Since the dependence on
α
of any contribution other
than
a
e
(QED) is negligible, the anomaly as a function of
α
is given by combining terms that have like powers of
α/
Ï€
to yield
a
e
(th) =
a
e
(QED) +
a
e
(weak) +
a
e
(had)
,
(96)
where
a
e
(QED) =
C
(2)
e
α
Ï€
+
C
(4)
e
α
Ï€
2
+
C
(6)
e
α
Ï€
3
+
C
(8)
e
α
Ï€
4
+
C
(10)
e
α
Ï€
5
+
· · ·
,
(97)
with
C
(2)
e
= 0
.
5
C
(4)
e
=
−
0
.
328 478 444 00
C
(6)
e
= 1
.
181 234 017
C
(8)
e
=
−
1
.
7283(35)
C
(10)
e
= 0
.
0(3
.
7)
,
(98)
and where
a
e
(weak) and
a
e
(had) are given in Eqs. (94)
and (95).
The standard uncertainty of
a
e
(th) from the uncertain-
ties of the terms listed above, other than that due to
α
,
is
u
[
a
e
(th)] = 0
.
27
×
10
−
12
= 2
.
4
×
10
−
10
a
e
,
(99)
and is dominated by the uncertainty of the coefficient
C
(10)
e
.
For the purpose of the least-squares calculations car-
ried out in Sec. XII.B, we deï¬ne an additive correction
δ
e
to
a
e
(th) to account for the lack of exact knowledge
of
a
e
(th), and hence the complete theoretical expression
for the electron anomaly is
a
e
(
α, δ
e
) =
a
e
(th) +
δ
e
.
(100)
Our theoretical estimate of
δ
e
is zero and its standard
uncertainty is
u
[
a
e
(th)]:
δ
e
= 0
.
00(27)
×
10
−
12
.
(101)
2. Measurements of
a
e
a. Measurement of
a
e
: University of Washington.
The clas-
sic series of measurements of the electron and positron
anomalies carried out at the University of Washington by
Van Dyck
et al.
(1987) yield the value
a
e
= 1
.
159 652 1883(42)
×
10
−
3
[3
.
7
×
10
−
9
]
,
(102)
as discussed in CODATA-98. This result assumes that
CP T
invariance holds for the electron-positron system.
24
b. Measurement of
a
e
: Harvard University.
A new deter-
mination of the electron anomaly using a cylindrical Pen-
ning trap has been carried out by Odom
et al.
(2006) at
Harvard University, yielding the value
a
e
= 1
.
159 652 180 85(76)
×
10
−
3
[6
.
6
×
10
−
10
]
,
(103)
which has an uncertainty that is nearly six times smaller
than that of the University of Washington result.
As in the University of Washington experiment, the
anomaly is obtained in essence from the relation
a
e
=
f
a
/f
c
by determining, in the same magnetic flux den-
sity
B
(about 5 T), the anomaly difference frequency
f
a
=
f
s
−
f
c
and cyclotron frequency
f
c
=
eB/
2
Ï€m
e
,
where
f
s
=
g
e
µ
B
B/h
is the electron spin-flip (often
called precession) frequency. The marked improvement
achieved by the Harvard group, the culmination of a 20
year effort, is due in large part to the use of a cylin-
drical Penning trap with a resonant cavity that interacts
with the trapped electron in a readily calculable way, and
through its high
Q
resonances, signiï¬cantly increases the
lifetime of the electron in its lowest few energy states by
inhibiting the decay of these states through spontaneous
emission. Further, cooling the trap and its vacuum enclo-
sure to 100 mK by means of a dilution refrigerator elim-
inates blackbody radiation that could excite the electron
from these states.
The frequencies
f
a
and
f
c
are determined by apply-
ing quantum-jump spectroscopy (QJS) to transitions be-
tween the lowest spin (
m
s
=
±
1
/
2) and cyclotron (
n
=
0
,
1
,
2) quantum states of the electron in the trap. (In
QJS, the quantum jumps per attempt to drive them are
measured as a function of drive frequency.) The transi-
tions are induced by applying a signal of frequency
≈
f
a
to trap electrodes or by transmitting microwaves of fre-
quency
≈
f
c
into the trap cavity. A change in the cy-
clotron or spin state of the electron is reflected in a shift
in
ν
z
, the self excited axial oscillation of the electron.
(The trap axis and
B
are in the
z
direction.) This oscil-
lation induces a signal in a resonant circuit that is am-
pliï¬ed and fed back to the trap to drive the oscillation.
Saturated nickel rings surrounding the trap produce a
small magnetic bottle that provides quantum nondemo-
lition couplings of the spin and cyclotron energies to
ν
z
.
Failure to resolve the cyclotron energy levels would result
in an increase of uncertainty due to the leading relativis-
tic correction
δ/f
c
≡
hf
c
/mc
2
≈
10
−
9
.
Another unique feature of the Harvard experiment is
that the effect of the trap cavity modes on
f
c
, and hence
on the measured value of
a
e
, are directly observed for
the ï¬rst time. The modes are quantitatively identiï¬ed
as the familiar transverse electric (TE) and transverse
magnetic (TM) modes by observing the response of a
cloud of electrons to an axial parametric drive, and, based
on the work of Brown and Gabrielse (1986), the range of
possible shifts of
f
c
for a cylindrical cavity with a
Q >
500 as used in the Harvard experiment can be readily
calculated. Two measurements of
a
e
were made: one,
which resulted in the value of
a
e
given in Eq. (103), was
at a value of
B
for which
f
c
= 149 GHz, far from modes
that couple to the cyclotron motion; the other was at
146.8 GHz, close to mode TE
127
. Within the calibration
and identiï¬cation uncertainties for the mode frequencies,
very good agreement was found between the measured
and predicted difference in the two values. Indeed, their
weighted mean gives a value of
a
e
that is larger than the
value in Eq. (103) by only the fractional amount 0
.
5
×
10
−
10
, with
u
r
slightly reduced to 6
.
5
×
10
−
10
.
The largest component of uncertainty, 5
.
2
×
10
−
10
, in
the 6
.
6
×
10
−
10
u
r
of the Harvard result for
a
e
arises
from ï¬tting the resonance line shapes for
f
a
and
f
c
ob-
tained from the quantum jump spectroscopy data. It is
based on the consistency of three different methods of
extracting these frequencies from the line shapes. The
method that yielded the best ï¬ts and which was used to
obtain the reported value of
a
e
weights each drive fre-
quency, spin flip or cyclotron, by the number of quantum
jumps it produces, and then uses the weighted average
of the resulting spin flip and cyclotron frequencies in the
ï¬nal calculation of
a
e
. Although the cavity shifts are
well characterized, they account for the second largest
fractional uncertainty component, 3
.
4
×
10
−
10
. The sta-
tistical (Type A) component, which is the next largest,
is only 1
.
5
×
10
−
10
.
3. Values of
α
inferred from
a
e
Equating the theoretical expression with the two ex-
perimental values of
a
e
given in Eqs. (102) and (103)
yields
α
−
1
(
a
e
) = 137
.
035 998 83(50) [3
.
7
×
10
−
9
]
(104)
from the University of Washington result and
α
−
1
(
a
e
) = 137
.
035 999 711(96) [7
.
0
×
10
−
10
] (105)
from the Harvard University result. The contribution
of the uncertainty in
a
e
(th) to the relative uncertainty
of either of these results is 2
.
4
×
10
−
10
. The value in
Eq. (105) has the smallest uncertainty of any value of
alpha currently available. Both values are included in
Table XIV.
B. Muon magnetic moment anomaly
a
µ
Comparison of theory and experiment for the muon
magnetic moment anomaly gives a test of the theory of
the hadronic contributions, with the possibility of reveal-
ing physics beyond the Standard Model.
1. Theory of
a
µ
The current theory of
a
µ
has been throughly reviewed
in a number of recent publications by different authors,
25
including a book devoted solely to the subject; see, for
example, Davier
et al.
(2006); Jegerlehner (2007); Mel-
nikov and Vainshtein (2006); Miller
et al.
(2007); Passera
(2005).
The relevant mass-dependent terms and the corre-
sponding contributions to
a
µ
(th), based on the 2006 rec-
ommended values of the mass ratios, are
A
(4)
2
(
m
µ
/m
e
) = 1
.
094 258 3088(82)
(106)
→
506 386
.
4561(38)
×
10
−
8
a
µ
,
A
(4)
2
(
m
µ
/m
Ï„
) = 0
.
000 078 064(25)
(107)
→
36
.
126(12)
×
10
−
8
a
µ
,
A
(6)
2
(
m
µ
/m
e
) = 22
.
868 379 97(19)
(108)
→
24 581
.
766 16(20)
×
10
−
8
a
µ
,
A
(6)
2
(
m
µ
/m
Ï„
) = 0
.
000 360 51(21)
(109)
→
0
.
387 52(22)
×
10
−
8
a
µ
,
A
(8)
2
(
m
µ
/m
e
) = 132
.
6823(72)
(110)
→
331
.
288(18)
×
10
−
8
a
µ
,
A
(10)
2
(
m
µ
/m
e
) = 663(20)
(111)
→
3
.
85(12)
×
10
−
8
a
µ
,
(112)
A
(6)
3
(
m
µ
/m
e
, m
µ
/m
Ï„
) = 0
.
000 527 66(17)
(113)
→
0
.
567 20(18)
×
10
−
8
a
µ
,
A
(8)
3
(
m
µ
/m
e
, m
µ
/m
Ï„
) = 0
.
037 594(83)
(114)
→
0
.
093 87(21)
×
10
−
8
a
µ
.
These contributions and their uncertainties, as well as
the values (including their uncertainties) of
a
µ
(weak) and
a
µ
(had) given below, should be compared with the 54
×
10
−
8
a
µ
standard uncertainty of the experimental value
of
a
µ
from Brookhaven National Laboratory (BNL) (see
next section).
Some of the above terms reflect the results of recent
calculations.
The value of
A
(6)
2
(
m
µ
/m
Ï„
) in Eq. (109)
includes an additional contribution as discussed in
connection with Eq. (91).
The terms
A
(8)
2
(
m
µ
/m
e
)
and
A
(8)
3
(
m
µ
/m
e
, m
µ
/m
Ï„
) have been updated by Ki-
noshita and Nio (2004), with the resulting value for
A
(8)
2
(
m
µ
/m
e
) in Eq. (110) differing from the previous
value of 127
.
50(41) due to the elimination of various
problems with the earlier calculations, and the result-
ing value for
A
(8)
3
(
m
µ
/m
e
, m
µ
/m
Ï„
) in Eq. (114) differ-
ing from the previous value of 0
.
079(3), because dia-
grams that were thought to be negligible do in fact con-
tribute to the result. Further, the value for
A
(10)
2
(
m
µ
/m
e
)
in Eq. (111) from Kinoshita and Nio (2006b) replaces
the previous value, 930(170).
These authors believe
that their result, obtained from the numerical evalua-
tion of all of the integrals from 17 key subsets of Feyn-
man diagrams, accounts for the leading contributions to
A
(10)
2
(
m
µ
/m
e
), and the work of Kataev (2006), based
on the so-called renormalization group-inspired scheme-
invariant approach, strongly supports this view.
The electroweak contribution to
a
µ
(th) is taken to be
a
µ
(weak) = 154(2)
×
10
−
11
,
(115)
as given by Czarnecki
et al.
(2003, 2006). This value
was used in the 2002 adjustment and is discussed in
CODATA-02.
The hadronic contribution to
a
µ
(th) may be written as
a
µ
(had) =
a
(4)
µ
(had) +
a
(6
a
)
µ
(had) +
a
(
γγ
)
µ
(had) +
· · ·
,
(116)
where
a
(4)
µ
(had) and
a
(6
a
)
µ
(had) arise from hadronic vac-
uum polarization and are of order (
α/
Ï€
)
2
and (
α/
Ï€
)
3
,
respectively; and
a
(
γγ
)
µ
(had), which arises from hadronic
light-by-light vacuum polarization, is also of order
(
α/
Ï€
)
3
.
Values of
a
(4)
µ
(had) are obtained from calculations that
evaluate dispersion integrals over measured cross sections
for the scattering of e
+
e
−
into hadrons. In addition,
in some such calculations, data on decays of the
Ï„
into
hadrons is used to replace the e
+
e
−
data in certain parts
of the calculation. In the 2002 adjustment, results from
both types of calculation were averaged to obtain a value
that would be representative of both approaches.
There have been improvements in the calculations that
use only e
+
e
−
data with the addition of new data from
the detectors CMD-2 at Novosibirsk, KLOE at Frascati,
BaBar at the Stanford Linear Accelerator Center, and
corrected data from the detector SND at Novosibirsk
(Davier, 2007; Hagiwara
et al.
, 2007; Jegerlehner, 2007).
However, there is a persistent disagreement between the
results that include the
Ï„
decay data and those that use
only e
+
e
−
data. In view of the improvements in the re-
sults based solely on e
+
e
−
data and the unresolved ques-
tions concerning the assumptions required to incorporate
the
Ï„
data into the analysis (Davier, 2007; Davier
et al.
,
2006; Melnikov and Vainshtein, 2006), we use in the 2006
adjustment results based solely on e
+
e
−
data. The value
employed is
a
(4)
µ
(had) = 690(21)
×
10
−
10
,
(117)
which is the unweighted mean of the values
a
(4)
µ
(had) =
689
.
4(4
.
6)
×
10
−
10
(Hagiwara
et
al.
,
2007) and
a
(4)
µ
(had) = 690
.
9(4
.
4)
×
10
−
10
(Davier, 2007). The un-
certainty assigned the value of
a
(4)
µ
(had), as expressed in
Eq (117), is essentially the difference between the values
that include
Ï„
data and those that do not. In particular,
26
the result that includes
Ï„
data that we use to estimate
the uncertainty is 711
.
0(5
.
8)
×
10
−
11
from Davier
et al.
(2003); the value of
a
(4)
µ
(had) used in the 2002 adjust-
ment was based in part on this result. Although there
is the smaller value 701
.
8(5
.
8)
×
10
−
11
from Troc´
oniz
and Yndur´
ain (2005), we use only the larger value in
order to obtain an uncertainty that covers the possibil-
ity of physics beyond the Standard Model not included
in the calculation of
a
µ
(th). Other, mostly older results
for
a
(4)
µ
(had), but which in general agree with the two
values we have averaged, are summarized in Table III of
Jegerlehner (2007).
For the second term in Eq. (116), we employ the value
a
(6
a
)
µ
(had) =
−
97
.
90(95)
×
10
−
11
(118)
calculated by Hagiwara
et al.
(2004), which was also used
in the 2002 adjustment.
The light-by-light contribution in Eq. (116) has been
calculated by Melnikov and Vainshtein (2004, 2006), who
obtain the value
a
(
γγ
)
µ
(had) = 136(25)
×
10
−
11
.
(119)
It is somewhat larger than earlier results, because it
includes short distance constraints imposed by quan-
tum chromodynamics (QCD) that were not included
in the previous calculations. It is consistent with the
95 % conï¬dence limit upper bound of 159
×
10
−
11
for
a
(
γγ
)
µ
(had) obtained by Erler and S´
anchez (2006), the
value 110(40)
×
10
−
11
proposed by Bijnens and Prades
(2007), and the value 125(35)
×
10
−
11
suggested by Davier
and Marciano (2004).
The total hadronic contribution is
a
µ
(had) = 694(21)
×
10
−
10
= 595(18)
×
10
−
7
a
µ
.
(120)
Combining terms in
a
µ
(QED) that have like powers of
α/
Ï€
, we summarize the theory of
a
µ
as follows:
a
µ
(th) =
a
µ
(QED) +
a
µ
(weak) +
a
µ
(had)
,
(121)
where
a
µ
(QED) =
C
(2)
µ
α
Ï€
+
C
(4)
µ
α
Ï€
2
+
C
(6)
µ
α
Ï€
3
+
C
(8)
µ
α
Ï€
4
+
C
(10)
µ
α
Ï€
5
+
· · ·
,
(122)
with
C
(2)
µ
= 0
.
5
C
(4)
µ
= 0
.
765 857 408(27)
C
(6)
µ
= 24
.
050 509 59(42)
C
(8)
µ
= 130
.
9916(80)
C
(10)
µ
= 663(20)
,
(123)
and where
a
µ
(weak) and
a
µ
(had) are as given in
Eqs. (115) and (120). The standard uncertainty of
a
µ
(th)
from the uncertainties of the terms listed above, other
than that due to
α
, is
u
[
a
µ
(th)] = 2
.
1
×
10
−
9
= 1
.
8
×
10
−
6
a
µ
,
(124)
and is primarily due to the uncertainty of
a
µ
(had).
For the purpose of the least-squares calculations car-
ried out in Sec. XII.B, we deï¬ne an additive correction
δ
µ
to
a
µ
(th) to account for the lack of exact knowledge
of
a
µ
(th), and hence the complete theoretical expression
for the muon anomaly is
a
µ
(
α, δ
µ
) =
a
µ
(th) +
δ
µ
.
(125)
Our theoretical estimate of
δ
µ
is zero and its standard
uncertainty is
u
[
a
µ
(th)]:
δ
µ
= 0
.
0(2
.
1)
×
10
−
9
.
(126)
Although
a
µ
(th) and
a
e
(th) have some common compo-
nents of uncertainty, the covariance of
δ
µ
and
δ
e
is negli-
gible.
2. Measurement of
a
µ
: Brookhaven.
Experiment E821 at Brookhaven National Laboratory
(BNL), Upton, New York, was initiated by the Muon
g
−
2
Collaboration in the early-1980s with the goal of mea-
suring
a
µ
with a signiï¬cantly smaller uncertainty than
u
r
= 7
.
2
×
10
−
6
. This is the uncertainty achieved in the
third
g
−
2 experiment carried out at the European Orga-
nization for Nuclear Research (CERN), Geneva, Switzer-
land, in the mid-1970s using both positive and negative
muons and which was the culmination of nearly 20 years
of effort (Bailey
et al.
, 1979).
The basic principle of the experimental determination
of
a
µ
is similar to that used to determine
a
e
and involves
measuring the anomaly difference frequency
f
a
=
f
s
−
f
c
,
where
f
s
=
|
g
µ
|
(
e
¯
h/
2
m
µ
)
B/h
is the muon spin-flip (of-
ten called precession) frequency in the applied magnetic
flux density
B
and where
f
c
=
eB/
2
Ï€
m
µ
is the corre-
sponding muon cyclotron frequency. However, instead of
eliminating
B
by measuring
f
c
as is done for the electron,
B
is determined from proton nuclear magnetic resonance
(NMR) measurements. As a consequence, the value of
µ
µ
/µ
p
is required to deduce the value of
a
µ
from the
data. The relevant equation is
a
µ
=
R
|
µ
µ
/µ
p
| −
R
,
(127)
where
R
=
f
a
/f
p
, and
f
p
is the free proton NMR fre-
quency corresponding to the average flux density seen by
the muons in their orbits in the muon storage ring used in
the experiment. (Of course, in the corresponding experi-
ment for the electron, a Penning trap is employed rather
than a storage ring.)
27
The BNL
a
µ
experiment was discussed in both
CODATA-98 and CODATA-02. In the 1998 adjustment,
the CERN ï¬nal result for
R
with
u
r
= 7
.
2
×
10
−
6
, and the
ï¬rst BNL result for
R
, obtained from the 1997 engineer-
ing run using positive muons and with
u
r
= 13
×
10
−
6
,
were taken as input data. By the time of the 2002 adjust-
ment, the BNL experiment had progressed to the point
where the CERN result was no longer competitive, and
the input datum used was the BNL mean value of
R
with
u
r
= 6
.
7
×
10
−
7
obtained from the 1998, 1999, and 2000
runs using
µ
+
. The ï¬nal run of the BNL E821 experi-
ment was carried out in 2001 with
µ
−
and achieved an
uncertainty for
R
of
u
r
= 7
.
0
×
10
−
7
, but the result only
became available in early 2004, well after the closing date
of the 2002 adjustment.
Based on the data obtained in all ï¬ve runs and as-
suming
CP T
invariance, an assumption justiï¬ed by the
consistency of the values of
R
obtained from either
µ
+
or
µ
−
, the ï¬nal report on the E821 experiment gives as the
ï¬nal value of
R
(Bennett
et al.
, 2006) [see also (Miller
et al.
, 2007)]
R
= 0
.
003 707 2064(20) [5
.
4
×
10
−
7
]
,
(128)
which we take as an input datum in the 2006 adjustment.
A new BNL experiment to obtain a value of
R
with a
smaller uncertainty is under discussion (Hertzog, 2007).
The experimental value of
a
µ
implied by this value of
R
is, from Eq. (127) and the 2006 recommended value
of
µ
µ
/µ
p
, the uncertainty of which is inconsequential in
this application,
a
µ
(exp) = 1
.
165 920 93(63)
×
10
−
3
[5
.
4
×
10
−
7
]
.
(129)
Further, with the aid of Eq. (217) in Sec. VI.B, Eq. (127)
can be written as
R
=
−
a
µ
(
α, δ
µ
)
1 +
a
e
(
α, δ
e
)
m
e
m
µ
µ
e
−
µ
p
,
(130)
where we have used the relations
g
e
=
−
2(1 +
a
e
) and
g
µ
=
−
2(1 +
a
µ
) and replaced
a
e
and
a
µ
with their
complete theoretical expressions
a
e
(
α, δ
e
) and
a
µ
(
α, δ
µ
),
which are discussed in Sec. V.A.1 and Sec. V.B.1, re-
spectively. Equation (130) is, in fact, the observational
equation for the input datum
R
.
a. Theoretical value of
a
µ
and inferred value of
α
Evalu-
ation of the theoretical expression for
a
µ
in Eq. (121)
with the 2006 recommended value of
α
, the uncertainty
of which is negligible in this context, yields
a
µ
(th) = 1
.
165 9181(21)
×
10
−
3
[1
.
8
×
10
−
6
]
,
(131)
which may be compared to the value in Eq. (129) de-
duced from the BNL result for
R
given in Eq. (128).
The experimental value exceeds the theoretical value by
1
.
3
u
diff
, where
u
diff
is the standard uncertainty of the
difference. It should be recognized, however, that this
reasonable agreement is a consequence of the compar-
atively large uncertainty we have assigned to
a
(4)
µ
(had)
[see Eq. (124)]. If the result for
a
(4)
µ
(had) that includes
tau data were ignored and the uncertainty of
a
(4)
µ
(had)
were based on the estimated uncertainties of the calcu-
lated values using only e
+
e
−
data, then the experimental
value would exceed the theoretical value by 3
.
5
u
diff
. This
inconsistency is well known to the high-energy physics
community and is of considerable interest because it may
be an indication of “New Physics†beyond the Standard
Model, such as supersymmetry (St¨ockinger, 2007).
One might ask, why include the theoretical value for
a
µ
in the 2006 adjustment given its current problems?
By retaining the theoretical expression with an increased
uncertainty, we ensure that the 2006 recommended value
of
a
µ
reflects, even though with a comparatively small
weight, the existence of the theoretical value.
The consistency between theory and experiment may
also be examined by considering the value of
α
obtained
by equating the theoretical expression for
a
µ
with the
BNL experimental value, as was done for
a
e
in Sec. V.A.3.
The result is
α
−
1
= 137
.
035 67(26) [1
.
9
×
10
−
6
]
,
(132)
which is the value included in Table XIV.
C. Bound electron
g
-factor in
12
C
5+
and in
16
O
7+
and
A
r
(e)
Precise measurements and theoretical calculations of
the
g
-factor of the electron in hydrogenic
12
C and in hy-
drogenic
16
O lead to values of
A
r
(e) that contribute to
the determination of the 2006 recommended value of this
important constant.
For a ground-state hydrogenic ion
A
X
(
Z
−
1)+
with
mass number
A
, atomic number (proton number)
Z
,
nuclear spin quantum number
i
= 0, and
g
-factor
g
e
−
(
A
X
(
Z
−
1)+
) in an applied magnetic flux density
B
,
the ratio of the electron’s spin-flip (often called pre-
cession) frequency
f
s
=
|
g
e
−
(
A
X
(
Z
−
1)+
)
|
(
e
¯
h/
2
m
e
)
B/h
to the cyclotron frequency of the ion
f
c
= (
Z
−
1)
eB/
2
Ï€
m
(
A
X
(
Z
−
1)+
) in the same magnetic flux density
is
f
s
(
A
X
(
Z
−
1)+
)
f
c
(
A
X
(
Z
−
1)+
)
=
−
g
e
−
(
A
X
(
Z
−
1)+
)
2(
Z
−
1)
A
r
(
A
X
(
Z
−
1)+
)
A
r
(e)
,
(133)
where as usual,
A
r
(
X
) is the relative atomic mass of par-
ticle
X
. If the frequency ratio
f
s
/f
c
is determined exper-
imentally with high accuracy, and
A
r
(
A
X
(
Z
−
1)+
) of the
ion is also accurately known, then this expression can be
used to determine an accurate value of
A
r
(e), assuming
the bound-state electron
g
-factor can be calculated from
QED theory with sufficient accuracy; or the
g
-factor can
be determined if
A
r
(e) is accurately known from another
28
experiment. In fact, a broad program involving workers
from a number of European laboratories has been under-
way since the mid-1990s to measure the frequency ratio
and calculate the
g
-factor for different ions, most notably
(to date)
12
C
5+
and
16
O
7+
. The measurements them-
selves are being performed at the Gesellschaft f¨
ur Schwe-
rionenforschung, Darmstadt, Germany (GSI) by GSI and
University of Mainz researchers, and we discuss the ex-
perimental determinations of
f
s
/f
c
for
12
C
5+
and
16
O
7+
at GSI in Secs. V.C.2.a and V.C.2.b. The theoretical
expressions for the bound-electron
g
-factors of these two
ions are reviewed in the next section.
1. Theory of the bound electron
g
-factor
In this section, we consider an electron in the 1S state
of hydrogen like carbon 12 or oxygen 16 within the frame-
work of bound-state QED. The measured quantity is the
transition frequency between the two Zeeman levels of
the atom in an externally applied magnetic ï¬eld.
The energy of a free electron with spin projection
s
z
in a magnetic flux density
B
in the
z
direction is
E
=
−
µ
·
B
=
−
g
e
−
e
2
m
e
s
z
B ,
(134)
and hence the spin-flip energy difference is
∆
E
=
−
g
e
−
µ
B
B .
(135)
(In keeping with the deï¬nition of the
g
-factor in Sec. V,
the quantity
g
e
−
is negative.) The analogous expression
for ions with no nuclear spin is
∆
E
b
(
X
) =
−
g
e
−
(
X
)
µ
B
B ,
(136)
which deï¬nes the bound-state electron
g
-factor, and
where
X
is either
12
C
5+
or
16
O
7+
.
The theoretical expression for
g
e
−
(
X
) is written as
g
e
−
(X) =
g
D
+ ∆
g
rad
+ ∆
g
rec
+ ∆
g
ns
+
· · ·
,
(137)
where the individual terms are the Dirac value, the ra-
diative corrections, the recoil corrections, and the nuclear
size corrections, respectively. These theoretical contribu-
tions are discussed in the following paragraphs; numerical
results based on the 2006 recommended values are sum-
marized in Tables XV and XVI. In the 2006 adjustment
α
in the expression for
g
D
is treated as a variable, but the
constants in the rest of the calculation of the
g
-factors are
taken as ï¬xed quantities.
(Breit, 1928) obtained the exact value
g
D
=
−
2
3
h
1 + 2
p
1
−
(
Zα
)
2
i
=
−
2
1
−
1
3
(
Zα
)
2
−
1
12
(
Zα
)
4
−
1
24
(
Zα
)
6
+
· · ·
(138)
from the Dirac equation for an electron in the ï¬eld of
a ï¬xed point charge of magnitude
Ze
, where the only
uncertainty is that due to the uncertainty in
α
.
The radiative corrections may be written as
∆
g
rad
=
−
2
C
(2)
e
(
Zα
)
α
Ï€
+
C
(4)
e
(
Zα
)
α
Ï€
2
+
· · ·
,
(139)
where the coefficients
C
(2
n
)
e
(
Zα
), corresponding to
n
vir-
tual photons, are slowly varying functions of
Zα
. These
coefficients are deï¬ned in direct analogy with the corre-
sponding coefficients for the free electron
C
(2
n
)
e
given in
Eq. (98) so that
lim
Zα
→
0
C
(2
n
)
e
(
Zα
) =
C
(2
n
)
e
.
(140)
The ï¬rst two terms of the coefficient
C
(2)
e
(
Zα
) have
been known for some time (Close and Osborn, 1971;
Faustov, 1970; Grotch, 1970). Recently, Pachucki
et al.
(2005a, 2004, 2005b) have calculated additional terms
with the result
C
(2)
e
,
SE
(
Zα
) =
1
2
1 +
(
Zα
)
2
6
+ (
Zα
)
4
32
9
ln (
Zα
)
−
2
+
247
216
−
8
9
ln
k
0
−
8
3
ln
k
3
+(
Zα
)
5
R
SE
(
Zα
)
,
(141)
where
ln
k
0
= 2
.
984 128 556
(142)
ln
k
3
= 3
.
272 806 545
(143)
R
SE
(6
α
) = 22
.
160(10)
(144)
R
SE
(8
α
) = 21
.
859(4)
.
(145)
The quantity ln
k
0
is the Bethe logarithm for the 1S state
(see Table VII) and ln
k
3
is a generalization of the Bethe
logarithm relevant to the
g
-factor calculation. The re-
mainder function
R
SE
(
Zα
) was obtained by Pachucki
et al.
(2004, 2005b) by extrapolation of the results of
numerical calculations of the self energy for
Z >
8 by
Yerokhin
et al.
(2002) using Eq. (141) to remove the
lower-order terms. For
Z
= 6 and
Z
= 8 this yields
C
(2)
e
,
SE
(6
α
) = 0
.
500 183 606 65(80)
C
(2)
e
,
SE
(8
α
) = 0
.
500 349 2887(14)
.
(146)
The lowest-order vacuum-polarization correction con-
sists of a wave-function correction and a potential correc-
tion. The wave-function correction has been calculated
numerically by Beier
et al.
(2000), with the result (in our
notation)
C
(2)
e
,
VPwf
(6
α
) =
−
0
.
000 001 840 3431(43)
.
C
(2)
e
,
VPwf
(8
α
) =
−
0
.
000 005 712 028(26)
.
(147)
29
Each of these values is the sum of the Uehling potential
contribution and the higher-order Wichmann-Kroll con-
tribution, which were calculated separately with the un-
certainties added linearly, as done by Beier
et al.
(2000).
The values in Eq. (147) are consistent with the result of
an evaluation of the correction in powers of
Zα
(Karshen-
boim, 2000; Karshenboim
et al.
, 2001a,b). For the po-
tential correction, Beier
et al.
(2000) found that the
Uehling potential contribution is zero and calculated the
Wichmann-Kroll contribution numerically over a wide
range of
Z
(Beier, 2000). An extrapolation of the nu-
merical values from higher-
Z
, taken together with the
analytic result of Karshenboim and Milstein (2002),
C
(2)
e
,
VPp
(
Zα
) =
7
Ï€
432
(
Zα
)
5
+
· · ·
,
(148)
for the lowest-order Wichmann-Kroll contribution, yields
C
(2)
e
,
VPp
(6
α
) = 0
.
000 000 007 9595(69)
C
(2)
e
,
VPp
(8
α
) = 0
.
000 000 033 235(29)
.
(149)
More recently, Lee
et al.
(2005) have obtained the result
C
(2)
e
,
VPp
(6
α
) = 0
.
000 000 008 201(11)
C
(2)
e
,
VPp
(8
α
) = 0
.
000 000 034 23(11)
.
(150)
The values in Eq. (149) and Eq. (150) disagree somewhat,
so in the present analysis, we use a value that is an un-
weighted average of the two, with half the difference for
the uncertainty. These average values are
C
(2)
e
,
VPp
(6
α
) = 0
.
000 000 008 08(12)
C
(2)
e
,
VPp
(8
α
) = 0
.
000 000 033 73(50)
.
(151)
The total one-photon vacuum polarization coefficients
are given by the sum of Eqs. (147) and (151):
C
(2)
e
,
VP
(6
α
) =
C
(2)
e
,
VPwf
(6
α
) +
C
(2)
e
,
VPp
(6
α
)
=
−
0
.
000 001 832 26(12)
C
(2)
e
,
VP
(8
α
) =
C
(2)
e
,
VPwf
(8
α
) +
C
(2)
e
,
VPp
(8
α
)
=
−
0
.
000 005 678 30(50)
.
(152)
The total for the one-photon coefficient
C
(2)
e
(
Zα
),
given by the sum of Eqs. (146) and (152), is
C
(2)
e
(6
α
) =
C
(2)
e
,
SE
(6
α
) +
C
(2)
e
,
VP
(6
α
)
= 0
.
500 181 774 38(81)
C
(2)
e
(8
α
) =
C
(2)
e
,
SE
(8
α
) +
C
(2)
e
,
VP
(8
α
)
= 0
.
500 343 6104(14)
,
(153)
and the total one-photon contribution ∆
g
(2)
to the
g
-
factor is thus
∆
g
(2)
=
−
2
C
(2)
e
(
Zα
)
α
Ï€
=
−
0
.
002 323 663 914(4) for
Z
= 6
=
−
0
.
002 324 415 746(7) for
Z
= 8
.
(154)
The separate one-photon self energy and vacuum po-
larization contributions to the
g
-factor are given in Ta-
bles XV and XVI.
Calculations by Eides and Grotch (1997a) using the
Bargmann-Michel-Telegdi equation and by Czarnecki
et al.
(2001) using an effective potential approach yield
C
(2
n
)
e
(
Zα
) =
C
(2
n
)
e
1 +
(
Zα
)
2
6
+
· · ·
(155)
as the leading binding correction to the free electron coef-
ï¬cients
C
(2
n
)
e
for any order
n
. For
C
(2)
e
(
Zα
), this correc-
tion was known for some time. For higher-order terms,
it provides the leading binding effect.
The two-loop contribution of relative order (
Zα
)
4
has
recently been calculated by Jentschura
et al.
(2006);
Pachucki
et al.
(2005a) for any S state. Their result for
the ground-state correction is
C
(4)
e
(
Zα
) =
C
(4)
e
1 +
(
Zα
)
2
6
+ (
Zα
)
4
14
9
ln (
Zα
)
−
2
+
991343
155520
−
2
9
ln
k
0
−
4
3
ln
k
3
+
679
Ï€
2
12960
−
1441
Ï€
2
720
ln 2 +
1441
480
ζ
(3)
+
O
(
Zα
)
5
=
−
0
.
328 5778(23) for
Z
= 6
=
−
0
.
328 6578(97) for
Z
= 8
,
(156)
where ln
k
0
and ln
k
3
are given in Eqs. (142) and (143).
The uncertainty due to uncalculated terms is estimated
by assuming that the unknown higher-order terms, of or-
der (
Zα
)
5
or higher for two loops, are comparable to the
higher-order one-loop terms scaled by the free-electron
coefficients in each case, with an extra factor of 2 in-
cluded (Pachucki
et al.
, 2005a):
u
h
C
(4)
e
(
Zα
)
i
= 2
(
Zα
)
5
C
(4)
e
R
SE
(
Zα
)
.
(157)
The three- and four-photon terms are calculated with
the leading binding correction included:
C
(6)
e
(
Zα
) =
C
(6)
e
1 +
(
Zα
)
2
6
+
· · ·
= 1
.
181 611
. . .
for
Z
= 6
= 1
.
181 905
. . .
for
Z
= 8
,
(158)
where
C
(6)
e
= 1
.
181 234
. . .
, and
C
(8)
e
(
Zα
) =
C
(8)
e
1 +
(
Zα
)
2
6
+
· · ·
=
−
1
.
7289(35)
. . .
for
Z
= 6
=
−
1
.
7293(35)
. . .
for
Z
= 8
,
(159)
where
C
(8)
e
=
−
1
.
7283(35) (Kinoshita and Nio, 2006a).
This value would shift somewhat if the more recent ten-
tative value
C
(8)
e
=
−
1
.
9144(35) (Aoyama
et al.
, 2007)
30
were used (see Sec. V). An uncertainty estimate
C
(10)
e
(
Zα
)
≈
C
(10)
e
= 0
.
0(3
.
7)
(160)
is included for the ï¬ve-loop correction.
The recoil correction to the bound-state
g
-factor as-
sociated with the ï¬nite mass of the nucleus is denoted
by ∆
g
rec
, which we write here as the sum ∆
g
(0)
rec
+ ∆
g
(2)
rec
corresponding to terms that are zero- and ï¬rst-order in
α/
Ï€
, respectively. For ∆
g
(0)
rec
, we have
∆
g
(0)
rec
=
−
(
Zα
)
2
+
(
Zα
)
4
3[1 +
p
1
−
(
Zα
)
2
]
2
−
(
Zα
)
5
P
(
Zα
)
m
e
m
N
+
O
m
e
m
N
2
=
−
0
.
000 000 087 71(1)
. . .
for
Z
= 6
=
−
0
.
000 000 117 11(1)
. . .
for
Z
= 8
,
(161)
where
m
N
is the mass of the nucleus.
The
mass ratios, obtained from the 2006 adjustment, are
m
e
/m
(
12
C
6+
) = 0
.
000 045 727 5
. . .
and
m
e
/m
(
16
O
8+
) =
0
.
000 034 306 5
. . .
. The recoil terms are the same as in
CODATA-02 and references to the original calculations
are given there. An additional term of the order of the
mass ratio squared is included as
S
Z
(
Zα
)
2
m
e
m
N
2
,
(162)
where
S
Z
is taken to be the average of the disagreeing
values 1 +
Z
, obtained by Eides (2002); Eides and Grotch
(1997a), and
Z/
3 obtained by Martynenko and Faustov
(2001, 2002) for this term. The uncertainty in
S
Z
is taken
to be half the difference of the two values.
For ∆
g
(2)
rec
, we have
∆
g
(2)
rec
=
α
Ï€
(
Zα
)
2
3
m
e
m
N
+
· · ·
= 0
.
000 000 000 06
. . .
for
Z
= 6
= 0
.
000 000 000 09
. . .
for
Z
= 8
.
(163)
There is a small correction to the bound-state
g
-factor
due to the ï¬nite size of the nucleus, of order
∆
g
ns
=
−
8
3
(
Zα
)
4
R
N
λ
C
2
+
· · ·
,
(164)
where
R
N
is the bound-state nuclear rms charge radius
and
λ
C
is the Compton wavelength of the electron di-
vided by 2
Ï€
. This term is calculated as in CODATA-02
(Glazov and Shabaev, 2002) with updated values for the
nuclear radii
R
N
= 2
.
4703(22) fm and
R
N
= 2
.
7013(55)
from the compilation of Angeli (2004) for
12
C and
16
O,
respectively. This yields the correction
∆
g
ns
=
−
0
.
000 000 000 408(1) for
12
C
∆
g
ns
=
−
0
.
000 000 001 56(1) for
16
O
.
(165)
The theoretical value for the
g
-factor of the electron
in hydrogenic carbon 12 or oxygen 16 is the sum of the
individual contributions discussed above and summarized
in Tables XV and XVI:
g
e
−
(
12
C
5+
) =
−
2
.
001 041 590 203(28)
g
e
−
(
16
O
7+
) =
−
2
.
000 047 020 38(11)
.
(166)
For the purpose of the least-squares calculations car-
ried out in Sec. XII.B, we deï¬ne
g
C
(th) to be the sum
of
g
D
as given in Eq. (138), the term
−
2(
α/
Ï€
)
C
(2)
e
, and
the numerical values of the remaining terms in Eq. (137)
as given in Table XV, where the standard uncertainty of
these latter terms is
u
[
g
C
(th)] = 0
.
3
×
10
−
10
= 1
.
4
×
10
−
11
|
g
C
(th)
|
.
(167)
The uncertainty in
g
C
(th) due to the uncertainty in
α
enters the adjustment primarily through the func-
tional dependence of
g
D
and the term
−
2(
α/
Ï€
)
C
(2)
e
on
α
. Therefore this particular component of uncertainty is
not explicitly included in
u
[
g
C
(th)]. To take the uncer-
tainty
u
[
g
C
(th)] into account we employ as the theoretical
expression for the
g
-factor
g
C
(
α, δ
C
) =
g
C
(th) +
δ
C
,
(168)
where the input value of the additive correction
δ
C
is
taken to be zero and its standard uncertainty is
u
[
g
C
(th)]:
δ
C
= 0
.
00(27)
×
10
−
10
.
(169)
Analogous considerations apply for the
g
-factor in oxy-
gen:
u
[
g
O
(th)] = 1
.
1
×
10
−
10
= 5
.
3
×
10
−
11
|
g
O
(th)
|
(170)
g
O
(
α, δ
O
) =
g
O
(th) +
δ
O
(171)
δ
O
= 0
.
0(1
.
1)
×
10
−
10
.
(172)
Since the uncertainties of the theoretical values of the
carbon and oxygen
g
-factors arise primarily from the
same sources, the quantities
δ
C
and
δ
O
are highly cor-
related. Their covariance is
u
(
δ
C
, δ
O
) = 27
×
10
−
22
,
(173)
which corresponds to a correlation coefficient of
r
(
δ
C
, δ
O
) = 0
.
92.
The theoretical value of the ratio of the two
g
-factors,
which is relevant to the comparison to experiment in
Sec. V.C.2.c, is
g
e
−
(
12
C
5+
)
g
e
−
(
16
O
7+
)
= 1
.
000 497 273 218(41)
,
(174)
where the covariance, including the contribution from the
uncertainty in
α
for this case, is taken into account.
31
TABLE XV Theoretical contributions and total for the
g
-
factor of the electron in hydrogenic carbon 12 based on the
2006 recommended values of the constants.
Contribution
Value
Source
Dirac
g
D
−
1
.
998 721 354 402(2)
Eq. (138)
∆
g
(2)
SE
−
0
.
002 323 672 426(4)
Eq. (146)
∆
g
(2)
VP
0
.
000 000 008 512(1)
Eq. (152)
∆
g
(4)
0
.
000 003 545 677(25)
Eq. (156)
∆
g
(6)
−
0
.
000 000 029 618
Eq. (158)
∆
g
(8)
0
.
000 000 000 101
Eq. (159)
∆
g
(10)
0
.
000 000 000 000(1)
Eq. (160)
∆
g
rec
−
0
.
000 000 087 639(10)
Eqs. (161)-(163)
∆
g
ns
−
0
.
000 000 000 408(1)
Eq. (165)
g
e
−
(
12
C
5+
)
−
2
.
001 041 590 203(28)
Eq. (166)
TABLE XVI Theoretical contributions and total for the
g
-
factor of the electron in hydrogenic oxygen 16 based on the
2006 recommended values of the constants.
Contribution
Value
Source
Dirac
g
D
−
1
.
997 726 003 08
Eq. (138)
∆
g
(2)
SE
−
0
.
002 324 442 12(1)
Eq. (146)
∆
g
(2)
VP
0
.
000 000 026 38
Eq. (152)
∆
g
(4)
0
.
000 003 546 54(11)
Eq. (156)
∆
g
(6)
−
0
.
000 000 029 63
Eq. (158)
∆
g
(8)
0
.
000 000 000 10
Eq. (159)
∆
g
(10)
0
.
000 000 000 00
Eq. (160)
∆
g
rec
−
0
.
000 000 117 02(1)
Eqs. (161)-(163)
∆
g
ns
−
0
.
000 000 001 56(1)
Eq. (165)
g
e
−
(
16
O
7+
)
−
2
.
000 047 020 38(11)
Eq. (166)
2. Measurements of
g
e
(
12
C
5+
)
and
g
e
(
16
O
7+
)
.
The experimental data on the electron bound-state
g
-
factor in hydrogenic carbon and oxygen and the inferred
values of
A
r
(e) are summarized in Table XVII.
a. Experiment on
g
e
(
12
C
5+
)
.
The accurate determination
of the frequency ratio
f
s
(
12
C
5+
)
/f
c
(
12
C
5+
) at GSI based
on the double Penning-trap technique was discussed in
CODATA-02.
[See also the recent concise review by
Werth
et al.
(2006).] Since the result used as an input
datum in the 2002 adjustment is unchanged, we take it
as an input datum in the 2006 adjustment as well (Beier
et al.
, 2002; H¨
affner
et al.
, 2003; Werth, 2003):
f
s
12
C
5+
f
c
(
12
C
5+
)
= 4376
.
210 4989(23)
.
(175)
From Eq. (133) and Eq. (4) we have
f
s
12
C
5+
f
c
(
12
C
5+
)
=
−
g
e
−
12
C
5+
10
A
r
(e)
×
"
12
−
5
A
r
(e) +
E
b
12
C
−
E
b
12
C
5+
m
u
c
2
#
,
(176)
which is the basis for the observational equation for the
12
C
5+
frequency-ratio input datum.
Evaluation of this expression using the result for
f
s
(
12
C
5+
)
/f
c
(
12
C
5+
) in Eq. (175), the theoretical result
for
g
e
−
(
12
C
5+
) in Table XV, and the relevant binding
energies in Table IV of CODATA-02, yields
A
r
(e) = 0
.
000 548 579 909 32(29) [5
.
2
×
10
−
10
]
.
(177)
This value is consistent with that from antiprotonic
helium given in Eq. (74) and that from the University of
Washington given in Eq. (5), but has about a factor of
three to four smaller uncertainty.
b. Experiment
on
g
e
(
16
O
7+
)
.
The
double
Penning-
trap
determination
of
the
frequency
ratio
f
s
(
16
O
7+
)
/f
c
(
16
O
7+
) at GSI was also discussed in
CODATA-02, but the value used as an input datum
was not quite ï¬nal (Verd´
u
et al.
, 2003, 2002; Werth,
2003). A slightly different value for the ratio was given
in the ï¬nal report of the measurement (Tomaselli
et al.
,
2002), which is the value we take as the input datum
in the 2006 adjustment but modiï¬ed slightly as follows
based on information provided by Verd´
u (2006): (i) an
unrounded instead of a rounded value for the correction
due to extrapolating the axial temperature
T
z
to 0 K was
added to the uncorrected ratio (
−
0
.
000 004 7 in place of
−
0
.
000 005); and (ii) a more detailed uncertainty budget
was employed to evaluate the uncertainty of the ratio.
The resulting value is
f
s
16
O
7+
f
c
(
16
O
7+
)
= 4164
.
376 1837(32)
.
(178)
In analogy with what was done above with the ratio
f
s
(
12
C
5+
)
/f
c
(
12
C
5+
), from Eq. (133) and Eq. (4) we have
f
s
16
O
7+
f
c
(
16
O
7+
)
=
−
g
e
−
16
O
7+
14
A
r
(e)
A
r
16
O
7+
(179)
with
A
r
16
O
=
A
r
16
O
7+
+ 7
A
r
(e)
−
E
b
16
O
−
E
b
16
O
7+
m
u
c
2
,
(180)
which are the basis for the observational equations
for the oxygen frequency ratio and
A
r
(
16
O), respec-
tively. The ï¬rst expression, evaluated using the result
32
TABLE XVII Summary of experimental data on the electron bound-state
g
-factor in hydrogenic carbon and oxygen and
inferred values of the relative atomic mass of the electron.
Input datum
Value
Relative standard
Identiï¬cation
Sec. and Eq.
uncertainty
u
r
f
s
(
12
C
5+
)
/f
c
(
12
C
5+
)
4376
.
210 4989(23)
5
.
2
×
10
−
10
GSI-02
V.C.2.a (175)
A
r
(e)
0
.
000 548 579 909 32(29)
5
.
2
×
10
−
10
V.C.2.a (177)
f
s
(
16
O
7+
)
/f
c
(
16
O
7+
)
4164
.
376 1837(32)
7
.
6
×
10
−
10
GSI-02
V.C.2.b (178)
A
r
(e)
0
.
000 548 579 909 58(42)
7
.
6
×
10
−
10
V.C.2.b (181)
for
f
s
(
16
O
7+
)
/f
c
(
16
O
7+
) in Eq. (178) and the theoreti-
cal result for
g
e
−
(
16
O
7+
) in Table XVI, in combination
with the second expression, evaluated using the value of
A
r
(
16
O) in Table IV and the relevant binding energies in
Table IV of CODATA-02, yields
A
r
(e) = 0
.
000 548 579 909 58(42) [7
.
6
×
10
−
10
]
.
(181)
It is consistent with both the University of Washington
value in Eq. (5) and the value in Eq. (177) obtained from
f
s
(
12
C
5+
)
/f
c
(
12
C
5+
).
c. Relations between
g
e
(
12
C
5+
)
and
g
e
(
16
O
7+
)
.
It should
be noted that the GSI frequency ratios for
12
C
5+
and
16
O
7+
are correlated. Based on the detailed uncertainty
budgets of the two results (Verd´
u, 2006; Werth, 2003),
we ï¬nd the correlation coefficient to be
r
"
f
s
12
C
5+
f
c
(
12
C
5+
)
,
f
s
16
O
7+
f
c
(
16
O
7+
)
#
= 0
.
082
.
(182)
Finally, as a consistency test, it is of interest to com-
pare the experimental and theoretical values of the ratio
of
g
e
−
(
12
C
5+
) to
g
e
−
(
16
O
7+
) (Karshenboim and Ivanov,
2002). The main reason is that the experimental value of
the ratio is only weakly dependent on the value of
A
r
(e).
The theoretical value of the ratio is given in Eq. (174) and
takes into account the covariance of the two theoretical
values. The experimental value of the ratio can be ob-
tained by combining Eqs. (175), (176), (178) to (180) and
(182), and using the 2006 recommended value for
A
r
(e).
Because of the weak dependence of the experimental ra-
tio on
A
r
(e), the value used is not at all critical. The
result is
g
e
−
(
12
C
5+
)
g
e
−
(
16
O
7+
)
= 1
.
000 497 273 68(89) [8
.
9
×
10
−
10
]
,
(183)
in agreement with the theoretical value.
VI. MAGNETIC MOMENT RATIOS AND THE
MUON-ELECTRON MASS RATIO
Magnetic moment ratios and the muon-electron mass
ratio are determined by experiments on bound states of
the relevant particles. The free electron and muon mag-
netic moments are discussed in Sec. V and the theory
of the
g
-factor of an electron bound in an atom with no
nuclear spin is considered in Sec. V.C.1.
For nucleons or nuclei with spin
I
, the magnetic mo-
ment can be written as
µ
=
g
e
2
m
p
I
,
(184)
or
µ
=
gµ
N
i .
(185)
In Eq. (185),
µ
N
=
e
¯
h/
2
m
p
is the nuclear magneton,
deï¬ned in analogy with the Bohr magneton, and
i
is the
spin quantum number of the nucleus deï¬ned by
I
2
=
i
(
i
+ 1)¯
h
2
and
I
z
=
−
i
¯
h, ...,
(
i
−
1)¯
h, i
¯
h
, where
I
z
is the
spin projection. However, in some publications, moments
of nucleons are expressed in terms of the Bohr magneton
with a corresponding change in the deï¬nition of the
g
-
factor.
For atoms with a nonzero nuclear spin, bound state
g
-factors are deï¬ned by considering the contribution to
the Hamiltonian from the interaction of the atom with
an applied magnetic flux density
B
. For example, for
hydrogen, in the framework of the Pauli approximation,
we have
H
=
β
(H)
µ
e
−
·
µ
p
−
µ
e
−
(H)
·
B
−
µ
p
(H)
·
B
=
2
Ï€
¯
h
∆
ν
H
s
·
I
−
g
e
−
(H)
µ
B
¯
h
s
·
B
−
g
p
(H)
µ
N
¯
h
I
·
B
,
(186)
where
β
(H) characterizes the strength of the hyperï¬ne
interaction, ∆
ν
H
is the ground-state hyperï¬ne frequency,
s
is the spin of the electron, and
I
is the spin of the
nucleus, that is, the proton. Equation (186), or its analog
for other combinations of particles, serves to deï¬ne the
corresponding bound-state
g
-factors, which are
g
e
−
(H)
and
g
p
(H) in this case.
A. Magnetic moment ratios
A number of magnetic moment ratios are of interest for
the 2006 adjustment. The results of measurements and
the inferred values of various quantities are summarized
in Sec. VI.A.2, and the measurement results themselves
are also summarized in Table XIX.
The inferred moment ratios depend on the relevant
theoretical binding corrections that relate the
g
-factor
33
measured in the bound state to the corresponding free-
particle
g
-factor. To use the results of these experiments
in the 2006 adjustment, we employ theoretical expres-
sions that give predictions for the moments and
g
-factors
of the bound particles in terms of free-particle moments
and
g
-factors as well as adjusted constants; this is dis-
cussed in the following section. However, in a number of
cases, the differences between the bound-state and free-
state values are sufficiently small that the adjusted con-
stants can be taken as exactly known.
1. Theoretical ratios of atomic bound-particle to free-particle
g
-factors
Theoretical
g
-factor-related quantities used in the 2006
adjustment are the ratio of the
g
-factor of the electron
in the ground state of hydrogen to that of the free elec-
tron
g
e
−
(H)
/g
e
−
; the ratio of the
g
-factor of the proton
in hydrogen to that of the free proton
g
p
(H)
/g
p
; the anal-
ogous ratios for the electron and deuteron in deuterium,
g
e
−
(D)
/g
e
−
and
g
d
(D)
/g
d
, respectively; and the analo-
gous ratios for the electron and positive muon in muon-
ium,
g
e
−
(Mu)
/g
e
−
and
g
µ
+
(Mu)
/g
µ
+
, respectively.
These ratios and the references for the relevant calcu-
lations are discussed in CODATA-98 and CODATA-02;
only a summary of the results is included here.
For the electron in hydrogen, we have
g
e
−
(H)
g
e
−
= 1
−
1
3
(
Zα
)
2
−
1
12
(
Zα
)
4
+
1
4
(
Zα
)
2
α
Ï€
+
1
2
(
Zα
)
2
m
e
m
p
+
1
2
A
(4)
1
−
1
4
(
Zα
)
2
α
Ï€
2
−
5
12
(
Zα
)
2
α
Ï€
m
e
m
p
+
· · ·
,
(187)
where
A
(4)
1
is given in Eq. (84). For the proton in hydro-
gen, we have
g
p
(H)
g
p
= 1
−
1
3
α
(
Zα
)
−
97
108
α
(
Zα
)
3
+
1
6
α
(
Zα
)
m
e
m
p
3 + 4
a
p
1 +
a
p
+
· · ·
,
(188)
where the proton magnetic moment anomaly
a
p
is deï¬ned
by
a
p
=
µ
p
(
e
¯
h/
2
m
p
)
−
1
≈
1
.
793
.
(189)
For deuterium, similar expressions apply for the elec-
tron
g
e
−
(D)
g
e
−
= 1
−
1
3
(
Zα
)
2
−
1
12
(
Zα
)
4
+
1
4
(
Zα
)
2
α
Ï€
+
1
2
(
Zα
)
2
m
e
m
d
+
1
2
A
(4)
1
−
1
4
(
Zα
)
2
α
Ï€
2
−
5
12
(
Zα
)
2
α
Ï€
m
e
m
d
+
· · ·
,
(190)
TABLE XVIII Theoretical values for various bound-particle
to free-particle
g
-factor ratios relevant to the 2006 adjustment
based on the 2006 recommended values of the constants.
Ratio
Value
g
e
−
(H)
/g
e
−
1
−
17
.
7054
×
10
−
6
g
p
(H)
/g
p
1
−
17
.
7354
×
10
−
6
g
e
−
(D)
/g
e
−
1
−
17
.
7126
×
10
−
6
g
d
(D)
/g
d
1
−
17
.
7461
×
10
−
6
g
e
−
(Mu)
/g
e
−
1
−
17
.
5926
×
10
−
6
g
µ
+
(Mu)
/g
µ
+
1
−
17
.
6254
×
10
−
6
and deuteron
g
d
(D)
g
d
= 1
−
1
3
α
(
Zα
)
−
97
108
α
(
Zα
)
3
+
1
6
α
(
Zα
)
m
e
m
d
3 + 4
a
d
1 +
a
d
+
· · ·
,
(191)
where the deuteron magnetic moment anomaly
a
d
is de-
ï¬ned by
a
d
=
µ
d
(
e
¯
h/m
d
)
−
1
≈ −
0
.
143
.
(192)
In the case of muonium Mu, some additional higher-
order terms are included because of the larger mass ratio.
For the electron in muonium, we have
g
e
−
(Mu)
g
e
−
= 1
−
1
3
(
Zα
)
2
−
1
12
(
Zα
)
4
+
1
4
(
Zα
)
2
α
Ï€
+
1
2
(
Zα
)
2
m
e
m
µ
+
1
2
A
(4)
1
−
1
4
(
Zα
)
2
α
Ï€
2
−
5
12
(
Zα
)
2
α
Ï€
m
e
m
µ
−
1
2
(1 +
Z
)(
Zα
)
2
m
e
m
µ
2
+
· · ·
,
(193)
and for the muon in muonium, the ratio is
g
µ
+
(Mu)
g
µ
+
= 1
−
1
3
α
(
Zα
)
−
97
108
α
(
Zα
)
3
+
1
2
α
(
Zα
)
m
e
m
µ
+
1
12
α
(
Zα
)
α
Ï€
m
e
m
µ
−
1
2
(1 +
Z
)
α
(
Zα
)
m
e
m
µ
2
+
· · ·
.
(194)
The numerical values of the corrections in Eqs. (187)
to (194), based on the 2006 adjusted values of the rele-
vant constants, are listed in Table XVIII. Uncertainties
are negligible at the level of uncertainty of the relevant
experiments.
2. Ratio measurements
34
a. Electron to proton magnetic moment ratio
µ
e
/µ
p
.
The
ratio
µ
e
/µ
p
is obtained from measurements of the ra-
tio of the magnetic moment of the electron to the mag-
netic moment of the proton in the 1S state of hydrogen
µ
e
−
(H)
/µ
p
(H). We use the value obtained by Winkler
et al.
(1972) at MIT:
µ
e
−
(H)
µ
p
(H)
=
−
658
.
210 7058(66) [1
.
0
×
10
−
8
]
,
(195)
where a minor typographical error in the original pub-
lication has been corrected (Kleppner, 1997). The free-
particle ratio
µ
e
/µ
p
follows from the bound-particle ratio
and the relation
µ
e
−
µ
p
=
g
p
(H)
g
p
g
e
−
(H)
g
e
−
−
1
µ
e
−
(H)
µ
p
(H)
=
−
658
.
210 6860(66) [1
.
0
×
10
−
8
]
,
(196)
where the bound-state
g
-factor ratios are given in Table
XVIII.
b. Deuteron to electron magnetic moment ratio
µ
d
/µ
e
.
From measurements of the ratio
µ
d
(D)
/µ
e
−
(D) in the 1S
state of deuterium, Phillips
et al.
(1984) at MIT obtained
µ
d
(D)
µ
e
−
(D)
=
−
4
.
664 345 392(50)
×
10
−
4
[1
.
1
×
10
−
8
]
.
(197)
Although this result has not been published, as in the
1998 and 2002 adjustments, we include it as an input da-
tum, because the method is described in detail by Win-
kler
et al.
(1972) in connection with their measurement
of
µ
e
−
(H)
/µ
p
(H). The free-particle ratio is given by
µ
d
µ
e
−
=
g
e
−
(D)
g
e
−
g
d
(D)
g
d
−
1
µ
d
(D)
µ
e
−
(D)
=
−
4
.
664 345 548(50)
×
10
−
4
[1
.
1
×
10
−
8
]
,
(198)
with the bound-state
g
-factor ratios given in Table XVIII.
c. Proton to deuteron and triton to proton magnetic moment
ratios
µ
p
/µ
d
and
µ
t
/µ
p
The ratios
µ
p
/µ
d
and
µ
t
/µ
p
can
be determined by nuclear magnetic resonance (NMR)
measurements on the HD molecule (bound state of hydro-
gen and deuterium) and the HT molecule (bound state
of hydrogen and tritium,
3
H), respectively. The relevant
expressions are (see CODATA-98)
µ
p
(HD)
µ
d
(HD)
= [1 +
σ
d
(HD)
−
σ
p
(HD)]
µ
p
µ
d
(199)
µ
t
(HT)
µ
p
(HT)
= [1
−
σ
t
(HT) +
σ
p
(HT)]
µ
t
µ
p
,
(200)
where
µ
p
(HD) and
µ
d
(HD) are the proton and deuteron
magnetic moments in HD, respectively, and
σ
p
(HD) and
σ
d
(HD) are the corresponding nuclear magnetic shielding
corrections. Similarly,
µ
t
(HT) and
µ
p
(HT) are the tri-
ton (nucleus of tritium) and proton magnetic moments
in HT, respectively, and
σ
t
(HT) and
σ
p
(HT) are the cor-
responding nuclear magnetic shielding corrections. [Note
that
µ
(bound) = (1
−
σ
)
µ
(free) and the nuclear magnetic
shielding corrections are small.]
The determination of
µ
d
/µ
p
from NMR measurements
on HD by Wimett (1953) and by a Russian group work-
ing in St. Petersburg (Gorshkov
et al.
, 1989; Neronov
et al.
, 1975) was discussed in CODATA-98. However, for
reasons given there, mainly the lack of sufficient infor-
mation to assign a reliable uncertainty to the reported
values of
µ
d
(HD)
/µ
p
(HD) and also to the nuclear mag-
netic shielding correction difference
σ
d
(HD)
−
σ
p
(HD),
the results were not used in the 1998 or 2002 adjust-
ments. Further, since neither of these adjustments ad-
dressed quantities related to the triton, the determina-
tion of
µ
t
/µ
p
from measurements on HT by the Russian
group (Neronov and Barzakh, 1977) was not considered
in either of these adjustments. It may be recalled that a
systematic error related to the use of separate inductance
coils for the proton and deuteron NMR resonances in the
measurements of Neronov
et al.
(1975) was eliminated in
the HT measurements of Neronov and Barzakh (1977)
as well as in the HD measurements of Gorshkov
et al.
(1989).
Recently, a member of the earlier St. Petersburg group
together with one or more other Russian colleagues in
St. Petersburg published the following results based in
part on new measurements and re-examination of rel-
evant theory (Karshenboim
et al.
, 2005; Neronov and
Karshenboim, 2003):
µ
p
(HD)
µ
d
(HD)
= 3
.
257 199 531(29)
[8
.
9
×
10
−
9
] (201)
µ
t
(HT)
µ
p
(HT)
= 1
.
066 639 887(10)
[9
.
4
×
10
−
9
] (202)
σ
dp
≡
σ
d
(HD)
−
σ
p
(HD) = 15(2)
×
10
−
9
(203)
σ
tp
≡
σ
t
(HT)
−
σ
p
(HT) = 20(3)
×
10
−
9
,
(204)
which together with Eqs. (199) and (200) yield
µ
p
µ
d
= 3
.
257 199 482(30)
[9
.
1
×
10
−
9
]
(205)
µ
t
µ
p
= 1
.
066 639 908(10)
[9
.
8
×
10
−
9
]
.
(206)
The purpose of the new work (Karshenboim
et al.
,
2005; Neronov and Karshenboim, 2003) was (i) to check
whether rotating the NMR sample and using a high-
pressure gas as the sample (60 to 130 atmospheres),
which was the case in most of the older Russian exper-
iments, influenced the results and to report a value of
µ
p
(HD)
/µ
d
(HD) with a reliable uncertainty; and (ii) to
35
TABLE XIX Summary of data for magnetic moment ratios of various bound particles.
Quantity
Value
Relative standard Identiï¬cation Sect. and Eq.
uncertainty
u
r
µ
e
−
(H)
/µ
p
(H)
−
658
.
210 7058(66)
1
.
0
×
10
−
8
MIT-72
VI.A.2.a (195)
µ
d
(D)
/µ
e
−
(D)
−
4
.
664 345 392(50)
×
10
−
4
1
.
1
×
10
−
8
MIT-84
VI.A.2.b (197)
µ
p
(HD)
/µ
d
(HD)
3
.
257 199 531(29)
8
.
9
×
10
−
9
StPtrsb-03
VI.A.2.c (201)
σ
dp
15(2)
×
10
−
9
StPtrsb-03
VI.A.2.c (203)
µ
t
(HT)
/µ
p
(HT)
1
.
066 639 887(10)
9
.
4
×
10
−
9
StPtrsb-03
VI.A.2.c (202)
σ
tp
20(3)
×
10
−
9
StPtrsb-03
VI.A.2.c (204)
µ
e
−
(H)
/µ
′
p
−
658
.
215 9430(72)
1
.
1
×
10
−
8
MIT-77
VI.A.2.d (209)
µ
′
h
/µ
′
p
−
0
.
761 786 1313(33)
4
.
3
×
10
−
9
NPL-93
VI.A.2.e (211)
µ
n
/µ
′
p
−
0
.
684 996 94(16)
2
.
4
×
10
−
7
ILL-79
VI.A.2.f (212)
re-examine the theoretical values of the nuclear magnetic
shielding correction differences
σ
dp
and
σ
tp
and their un-
certainties. It was also anticipated that based on this new
work, a value of
µ
t
(HT)
/µ
p
(HT) with a reliable uncer-
tainty could be obtained from the highly precise mea-
surements of Neronov and Barzakh (1977). However,
Gorshkov
et al.
(1989), as part of their experiment to
determine
µ
d
/µ
p
, compared the result from a 100 atmo-
sphere HD rotating sample with a 100 atmosphere HD
non-rotating sample and found no statistically signiï¬cant
difference.
To test the effect of sample rotation and sample pres-
sure, Neronov and Karshenboim (2003) performed mea-
surements using a commercial NMR spectrometer op-
erating at a magnetic flux density of about 7 T and a
non-rotating 10 atmosphere HD gas sample. Because of
the relatively low pressure, the NMR signals were com-
paratively weak and a measurement time of 1 h was re-
quired. To simplify the measurements, the frequency of
the proton NMR signal from HD was determined rela-
tive to the frequency of the more easily measured proton
NMR signal from acetone, (CH
3
)
2
CO. Similarly, the fre-
quency of the deuteron NMR signal from HD was de-
termined relative to the frequency of the more easily
measured deuteron NMR signal from deuterated acetone,
(CD
3
)
2
CO. A number of tests involving the measurement
of the hyperï¬ne interaction constant in the case of the
proton triplet NMR spectrum, and the isotopic shift in
the case of the deuteron, where the deuteron HD doublet
NMR spectrum was compared with the singlet spectrum
of D
2
, were carried out to investigate the reliability of the
new data. The results of the tests were in good agreement
with the older results obtained with sample rotation and
high gas pressure.
The more recent result for
µ
p
(HD)
/µ
d
(HD) reported
by Karshenboim
et al.
(2005), which was obtained with
the same NMR spectrometer employed by Neronov and
Karshenboim (2003) but with a 20 atmosphere non-
rotating gas sample, agrees with the 10 atmosphere non-
rotating sample result of the latter researchers and is
interpreted by Karshenboim
et al.
(2005) as conï¬rming
the 2003 result. Although the values of
µ
p
(HD)
/µ
d
(HD)
reported by the Russian researchers in 2005, 2003, and
1989 agree, the 2003 result as given in Eq. (201) and
Table XIX, the uncertainty of which is dominated by
the proton NMR line ï¬tting procedure, is taken as the
input datum in the 2006 adjustment because of the at-
tention paid to possible systematic effects, both experi-
mental and theoretical.
Based on their HD measurements and related anal-
ysis, especially the fact that sample pressure and ro-
tation do not appear to be a problem at the current
level of uncertainty, Neronov and Karshenboim (2003)
conclude that the result for
µ
t
(HT)
/µ
p
(HT) reported
by Neronov and Barzakh (1977) is reliable but that it
should be assigned about the same relative uncertainty
as their result for
µ
p
(HD)
/µ
d
(HD). We therefore include
as an input datum in the 2006 adjustment the result for
µ
t
(HT)
/µ
p
(HT) given in Eq. (202) and Table XIX.
Without reliable theoretically calculated values for the
shielding correction differences
σ
dp
and
σ
tp
, reliable ex-
perimental values for the ratios
µ
p
(HD)
/µ
d
(HD) and
µ
t
(HT)
/µ
p
(HT) are of little use. Although Neronov and
Barzakh (1977) give theoretical estimates of these quan-
tities based on their own calculations, they do not discuss
the uncertainties of their estimates. To address this issue,
Neronov and Karshenboim (2003) carefully examined the
calculations and concluded that a reasonable estimate of
the relative uncertainty is 15 %. This leads to the values
for
σ
dp
and
σ
tp
in Eqs. (203) and (204) and Table XIX,
which we also take as input data for the 2006 adjustment.
[For simplicity, we use StPtrsb-03 as the identiï¬er in Ta-
ble XIX for
µ
p
(HD)
/µ
d
(HD),
µ
t
(HT)
/µ
p
(HT),
σ
dp
, and
σ
tp
, because they are directly or indirectly a consequence
of the work of Neronov and Karshenboim (2003).]
The equations for the measured moment ratios
µ
p
(HD)
/µ
d
(HD) and
µ
t
(HT)
/µ
p
(HT) in terms of the ad-
justed constants
µ
e
−
/µ
p
,
µ
d
/µ
e
−
,
µ
t
/µ
p
,
σ
dp
, and
σ
tp
are, from Eqs. (199) and (200),
µ
p
(HD)
µ
d
(HD)
= [1 +
σ
dp
]
µ
e
−
µ
p
−
1
µ
d
µ
e
−
−
1
(207)
µ
t
(HT)
µ
p
(HT)
= [1
−
σ
tp
]
µ
t
µ
p
.
(208)
36
d. Electron to shielded proton magnetic moment ratio
µ
e
/µ
′
p
.
Based on the measurement of the ratio of the electron mo-
ment in the 1S state of hydrogen to the shielded proton
moment at 34.7
â—¦
C by Phillips
et al.
(1977) at MIT, and
temperature-dependence measurements of the shielded
proton moment by Petley and Donaldson (1984) at the
National Physical Laboratory (NPL), Teddington, UK,
we have
µ
e
−
(H)
µ
′
p
=
−
658
.
215 9430(72) [1
.
1
×
10
−
8
]
,
(209)
where the prime indicates that the protons are in a spher-
ical sample of pure H
2
O at 25
â—¦
C surrounded by vacuum.
Hence
µ
e
−
µ
′
p
=
g
e
−
(H)
g
e
−
−
1
µ
e
−
(H)
µ
′
p
=
−
658
.
227 5971(72) [1
.
1
×
10
−
8
]
,
(210)
where the bound-state
g
-factor ratio is given in Table
XVIII. Support for the MIT result in Eq. (210) from
measurements at NPL on the helion (see the following
section) is discussed in CODATA-02.
e. Shielded helion to shielded proton magnetic moment ratio
µ
′
h
/µ
′
p
.
The ratio of the magnetic moment of the helion
h, the nucleus of the
3
He atom, to the magnetic moment
of the proton in H
2
O was determined in a high-accuracy
experiment at NPL (Flowers
et al.
, 1993) with the result
µ
′
h
µ
′
p
=
−
0
.
761 786 1313(33) [4
.
3
×
10
−
9
]
.
(211)
The prime on the symbol for the helion moment indi-
cates that the helion is not free, but is bound in a helium
atom. Although the exact shape and temperature of the
gaseous
3
He sample is unimportant, we assume that it is
spherical, at 25
â—¦
C, and surrounded by vacuum.
f. Neutron to shielded proton magnetic moment ratio
µ
n
/µ
′
p
.
Based on a measurement carried out at the Institut
Max von Laue-Paul Langevin (ILL) in Grenoble, France
(Greene
et al.
, 1979, 1977), we have
µ
n
µ
′
p
=
−
0
.
684 996 94(16) [2
.
4
×
10
−
7
]
.
(212)
The observational equations for the measured values
of
µ
′
h
/µ
′
p
and
µ
n
/µ
′
p
are simply
µ
′
h
/µ
′
p
=
µ
′
h
/µ
′
p
(213)
and
µ
n
/µ
′
p
=
µ
n
/µ
′
p
,
(214)
while the observational equations for the measured values
of
µ
e
−
(H)
/µ
p
(H),
µ
d
(D)
/µ
e
−
(D), and
µ
e
−
(H)
/µ
′
p
follow
directly from Eqs. (196), (198), and (210), respectively.
B. Muonium transition frequencies, the muon-proton
magnetic moment ratio
µ
µ
/µ
p
, and muon-electron mass
ratio
m
µ
/m
e
Measurements of transition frequencies between Zee-
man energy levels in muonium (the
µ
+
e
−
atom) yield
values of
µ
µ
/µ
p
and the muonium ground-state hyper-
ï¬ne splitting ∆
ν
Mu
that depend weakly on theory. The
relevant expression for the magnetic moment ratio is
µ
µ
+
µ
p
=
∆
ν
2
Mu
−
ν
2
(
f
p
) + 2
s
e
f
p
ν
(
f
p
)
4
s
e
f
2
p
−
2
f
p
ν
(
f
p
)
g
µ
+
(Mu)
g
µ
+
−
1
,
(215)
where ∆
ν
Mu
and
ν
(
f
p
) are the sum and difference of
two measured transition frequencies,
f
p
is the free proton
NMR reference frequency corresponding to the magnetic
flux density used in the experiment,
g
µ
+
(Mu)
/g
µ
+
is the
bound-state correction for the muon in muonium given
in Table XVIII, and
s
e
=
µ
e
−
µ
p
g
e
−
(Mu)
g
e
−
,
(216)
where
g
e
−
(Mu)
/g
e
−
is the bound-state correction for the
electron in muonium given in the same table.
The muon to electron mass ratio
m
µ
/m
e
and the muon
to proton magnetic moment ratio
µ
µ
/µ
p
are related by
m
µ
m
e
=
µ
e
µ
p
µ
µ
µ
p
−
1
g
µ
g
e
.
(217)
The theoretical expression for the hyperï¬ne splitting
∆
ν
Mu
(th) is discussed in the following section and may
be written as
∆
ν
Mu
(th) =
16
3
cR
∞
α
2
m
e
m
µ
1 +
m
e
m
µ
−
3
F
α, m
e
/m
µ
= ∆
ν
F
F
α, m
e
/m
µ
,
(218)
where the function
F
depends weakly on
α
and
m
e
/m
µ
.
By equating this expression to an experimental value of
∆
ν
Mu
, one can calculate a value of
α
from a given value
of
m
µ
/m
e
or one can calculate a value of
m
µ
/m
e
from a
given value of
α
.
1. Theory of the muonium ground-state hyperfine splitting
This section gives a brief summary of the present
theory of ∆
ν
Mu
, the ground-state hyperï¬ne splitting of
muonium (
µ
+
e
−
atom). There has been essentially no
change in the theory since the 2002 adjustment. Al-
though complete results of the relevant calculations are
given here, references to the original literature included in
CODATA-98 or CODATA-02 are generally not repeated.
The hyperï¬ne splitting is given mainly by the Fermi
formula:
∆
ν
F
=
16
3
cR
∞
Z
3
α
2
m
e
m
µ
1 +
m
e
m
µ
−
3
.
(219)
37
Some of the theoretical expressions correspond to a muon
with charge
Ze
rather than
e
in order to identify the
source of the terms. The theoretical value of the hyper-
ï¬ne splitting is given by
∆
ν
Mu
(th) = ∆
ν
D
+ ∆
ν
rad
+ ∆
ν
rec
+∆
ν
r
-
r
+ ∆
ν
weak
+ ∆
ν
had
,
(220)
where the terms labeled D, rad, rec, r-r, weak, and
had account for the Dirac (relativistic), radiative, recoil,
radiative-recoil, electroweak, and hadronic (strong inter-
action) contributions to the hyperï¬ne splitting, respec-
tively.
The contribution ∆
ν
D
, given by the Dirac equation, is
∆
ν
D
= ∆
ν
F
(1 +
a
µ
)
1 +
3
2
(
Zα
)
2
+
17
8
(
Zα
)
4
+
· · ·
,
(221)
where
a
µ
is the muon magnetic moment anomaly.
The radiative corrections are written as
∆
ν
rad
= ∆
ν
F
(1 +
a
µ
)
h
D
(2)
(
Zα
)
α
Ï€
+
D
(4)
(
Zα
)
α
Ï€
2
+
D
(6)
(
Zα
)
α
Ï€
3
+
· · ·
i
,
(222)
where the functions
D
(2
n
)
(
Zα
) are contributions associ-
ated with
n
virtual photons. The leading term is
D
(2)
(
Zα
) =
A
(2)
1
+ ln 2
−
5
2
Ï€
Zα
+
h
−
2
3
ln
2
(
Zα
)
−
2
+
281
360
−
8
3
ln 2
ln(
Zα
)
−
2
+16
.
9037
. . .
i
(
Zα
)
2
+
h
5
2
ln 2
−
547
96
ln(
Zα
)
−
2
i
Ï€
(
Zα
)
3
+
G
(
Zα
)(
Zα
)
3
,
(223)
where
A
(2)
1
=
1
2
, as in Eq. (83). The function
G
(
Zα
)
accounts for all higher-order contributions in powers of
Zα
, and can be divided into parts that correspond to the
self-energy or vacuum polarization,
G
(
Zα
) =
G
SE
(
Zα
)+
G
VP
(
Zα
). We adopt the value
G
SE
(
α
) =
−
14(2)
,
(224)
which is the simple mean and standard deviation of the
three values:
G
SE
(
α
) =
−
12
.
0(2
.
0) from Blundell
et al.
(1997);
G
SE
(0) =
−
15
.
9(1
.
6) from Nio (2001, 2002); and
G
SE
(
α
) =
−
14
.
3(1
.
1) from Yerokhin and Shabaev (2001).
The vacuum polarization part
G
VP
(
Zα
) has been calcu-
lated to several orders of
Zα
by Karshenboim
et al.
(1999,
2000). Their expression yields
G
VP
(
α
) = 7
.
227(9)
.
(225)
For
D
(4)
(
Zα
), as in CODATA-02, we have
D
(4)
(
Zα
) =
A
(4)
1
+ 0
.
7717(4)
Ï€
Zα
+
h
−
1
3
ln
2
(
Zα
)
−
2
−
0
.
6390
. . .
×
ln(
Zα
)
−
2
+ 10(2
.
5)
i
(
Zα
)
2
+
· · ·
,
(226)
where
A
(4)
1
is given in Eq. (84).
Finally,
D
(6)
(
Zα
) =
A
(6)
1
+
· · ·
,
(227)
where only the leading contribution
A
(6)
1
as given in
Eq. (85) is known. Higher-order functions
D
(2
n
)
(
Zα
)
with
n >
3 are expected to be negligible.
The recoil contribution is given by
∆
ν
rec
= ∆
ν
F
m
e
m
µ
−
3
1
−
m
e
/m
µ
2
ln
m
µ
m
e
Zα
Ï€
+
1
1 +
m
e
/m
µ
2
ln (
Zα
)
−
2
−
8 ln 2 +
65
18
+
9
2
Ï€
2
ln
2
m
µ
m
e
+
27
2
Ï€
2
−
1
ln
m
µ
m
e
+
93
4
Ï€
2
+
33
ζ
(3)
Ï€
2
−
13
12
−
12 ln 2
m
e
m
µ
(
Zα
)
2
+
−
3
2
ln
m
µ
m
e
ln(
Zα
)
−
2
−
1
6
ln
2
(
Zα
)
−
2
+
101
18
−
10 ln 2
ln(
Zα
)
−
2
+40(10)
(
Zα
)
3
Ï€
!
+
· · ·
,
(228)
as discussed in CODATA-02
The radiative-recoil contribution is
∆
ν
r
-
r
=
ν
F
α
Ï€
2
m
e
m
µ
−
2 ln
2
m
µ
m
e
+
13
12
ln
m
µ
m
e
+
21
2
ζ
(3) +
Ï€
2
6
+
35
9
+
4
3
ln
2
α
−
2
+
16
3
ln 2
−
341
180
ln
α
−
2
−
40(10)
Ï€
α
+
−
4
3
ln
3
m
µ
m
e
+
4
3
ln
2
m
µ
m
e
α
Ï€
−
ν
F
α
2
m
e
m
µ
2
6 ln 2 +
13
6
+
· · ·
,
(229)
where, for simplicity, the explicit dependence on
Z
is not
shown.
The electroweak contribution due to the exchange of a
Z
0
boson is (Eides, 1996)
∆
ν
weak
=
−
65 Hz
.
(230)
For the hadronic vacuum polarization contribution we
use the result of Eidelman
et al.
(2002),
∆
ν
had
= 236(4) Hz
,
(231)
which takes into account experimental data on the cross
section for e
−
e
+
→
Ï€
+
Ï€
−
and on the
φ
meson leptonic
38
width. The leading hadronic contribution is 231.2(2.9)
and the next order term is 5(2) giving a total of 236(4).
The pion and kaon contributions to the hadronic cor-
rection have been considered within a chiral unitary ap-
proach and found to be in general agreement with (but
have a three times larger uncertainty) the correspond-
ing contributions given in earlier studies using data from
e
+
-e
−
scattering (Palomar, 2003).
The standard uncertainty of ∆
ν
Mu
(th) was fully dis-
cussed in Appendix E of CODATA-02.
The four
principle sources of uncertainty are the terms ∆
ν
rad
,
∆
ν
rec
, ∆
ν
r
−
r
, and ∆
ν
had
in Eq. (220).
Included in
the 67 Hz uncertainty of ∆
ν
r
−
r
is a 41 Hz compo-
nent, based on the partial calculations of Eides
et al.
(2002, 2003); Li
et al.
(1993), to account for a pos-
sible uncalculated radiative-recoil contribution of or-
der ∆
ν
F
(
m
e
/
(
m
µ
)(
α/
Ï€
)
3
ln(
m
µ
/m
e
) and non-logarithmic
terms. Since the completion of the 2002 adjustment, the
results of additional partial calculations have been pub-
lished that, if taken at face value, would lead to a small
reduction in the 41 Hz estimate (D’Agostino
et al.
, 2005;
Eides
et al.
, 2004; Eides and Shelyuto, 2003, 2004, 2007).
However, because the calculations are not yet complete
and the decrease of the 101 Hz total uncertainty assigned
to ∆
ν
Mu
(th) for the 2002 adjustment would only be a few
percent, the Task Group decided to retain the 101 Hz un-
certainty for the 2006 adjustment.
We thus have for the standard uncertainty of the the-
oretical expression for the muonium hyperï¬ne splitting
∆
ν
Mu
(th)
u
[∆
ν
Mu
(th)] = 101 Hz
[2
.
3
×
10
−
8
]
.
(232)
For the least-squares calculations, we use as the theoret-
ical expression for the hyperï¬ne splitting
∆
ν
Mu
R
∞
, α,
m
e
m
µ
, δ
µ
, δ
Mu
= ∆
ν
Mu
(th) +
δ
Mu
,
(233)
where
δ
Mu
is assigned, a priori, the value
δ
Mu
= 0(101) Hz
(234)
in order to account for the uncertainty of the theoretical
expression.
The theory summarized above predicts
∆
ν
Mu
= 4 463 302 881(272) Hz
[6
.
1
×
10
−
8
]
,
(235)
based on values of the constants obtained from a varia-
tion of the 2006 least-squares adjustment that omits as
input data the two LAMPF measured values of ∆
ν
Mu
discussed in the following section.
The main source of uncertainty in this value is the mass
ratio
m
e
/m
µ
that appears in the theoretical expression
as an overall factor. See the text following Eq. (D14) of
Appendix D of CODATA-98 for an explanation of why
the relative uncertainty of the predicted value of ∆
ν
Mu
in Eq. (235) is smaller than the relative uncertainty of
the electron-muon mass ratio as given in Eq. (243) of
Sec. VI.B.2.c.
2. Measurements of muonium transition frequencies and values
of
µ
µ
/µ
p
and
m
µ
/m
e
The two most precise determinations of muonium
Zeeman transition frequencies were carried out at the
Clinton P. Anderson Meson Physics Facility at Los
Alamos (LAMPF), USA, and were reviewed in detail in
CODATA-98. The following three sections and Table XX
give the key results.
a. LAMPF 1982
The results obtained by Mariam (1981);
Mariam
et al.
(1982), which we take as input data in the
current adjustment as in the two previous adjustments,
may be summarized as follows:
∆
ν
Mu
= 4 463 302
.
88(16) kHz
[3
.
6
×
10
−
8
]
(236)
ν
(
f
p
) = 627 994
.
77(14) kHz
[2
.
2
×
10
−
7
]
(237)
r
[∆
ν
Mu
, ν
(
f
p
)] = 0
.
23
,
(238)
where
f
p
is very nearly 57
.
972 993 MHz, corresponding to
the flux density of about 1
.
3616 T used in the experiment,
and
r
[∆
ν
Mu
, ν
(
f
p
)] is the correlation coefficient of ∆
ν
Mu
and
ν
(
f
p
).
b. LAMPF 1999
The results obtained by Liu
et al.
(1999), which we also take as input data in the current
adjustment as in the 1998 and 2002 adjustments, may be
summarized as follows:
∆
ν
Mu
= 4 463 302 765(53) Hz
[1
.
2
×
10
−
8
]
(239)
ν
(
f
p
) = 668 223 166(57) Hz
[8
.
6
×
10
−
8
]
(240)
r
[∆
ν
Mu
, ν
(
f
p
)] = 0
.
19
,
(241)
where
f
p
is exactly 72
.
320 000 MHz, corresponding to the
flux density of approximately 1
.
7 T used in the experi-
ment, and
r
[∆
ν
Mu
, ν
(
f
p
)] is the correlation coefficient of
∆
ν
Mu
and
ν
(
f
p
).
c. Combined LAMPF results
By carrying out a least-
squares adjustment using only the LAMPF 1982 and
LAMPF 1999 data, the 2006 recommended values of
the quantities
R
∞
,
µ
e
/µ
p
,
g
e
, and
g
µ
, together with
Eqs. (215) to (218), we obtain
µ
µ
+
µ
p
= 3
.
183 345 24(37) [1
.
2
×
10
−
7
]
(242)
m
µ
m
e
= 206
.
768 276(24) [1
.
2
×
10
−
7
]
(243)
α
−
1
= 137
.
036 0017(80) [5
.
8
×
10
−
8
]
,
(244)
39
TABLE XX Summary of data related to the hyperï¬ne splitting in muonium and inferred values of
µ
µ
/µ
p
,
m
µ
/m
e
, and
α
from
the combined 1982 and 1999 LAMPF data.
Quantity
Value
Relative standard
Identiï¬cation
Sect. and Eq.
uncertainty
u
r
∆
ν
Mu
4 463 302
.
88(16) kHz
3
.
6
×
10
−
8
LAMPF-82
VI.B.2.a (236)
ν
(
f
p
)
627 994
.
77(14) kHz
2
.
2
×
10
−
7
LAMPF-82
VI.B.2.a (237)
∆
ν
Mu
4 463 302 765(53) Hz
1
.
2
×
10
−
8
LAMPF-99
VI.B.2.b (239)
ν
(
f
p
)
668 223 166(57) Hz
8
.
6
×
10
−
8
LAMPF-99
VI.B.2.b (240)
µ
µ
/µ
p
3
.
183 345 24(37)
1
.
2
×
10
−
7
LAMPF
VI.B.2.c (242)
m
µ
/m
e
206
.
768 276(24)
1
.
2
×
10
−
7
LAMPF
VI.B.2.c (243)
α
−
1
137
.
036 0017(80)
5
.
8
×
10
−
8
LAMPF
VI.B.2.c (244)
where this value of
α
may be called the muonium value of
the ï¬ne-structure constant and denoted as
α
−
1
(∆
ν
Mu
).
It is noteworthy that the uncertainty of the value of the
mass ratio
m
µ
/m
e
given in Eq. (243) is about four times
the uncertainty of the 2006 recommended value. The rea-
son is that taken together, the experimental value of and
theoretical expression for the hyperï¬ne splitting essen-
tially determine only the value of the product
α
2
m
µ
/m
e
,
as is evident from Eq. (218). In the full adjustment
the value of
α
is determined by other data with an un-
certainty signiï¬cantly smaller than that of the value in
Eq. (244), which in turn determines the value of
m
µ
/m
e
with a smaller uncertainty than that of Eq. (243).
VII. ELECTRICAL MEASUREMENTS
This section is devoted to the discussion of quantities
that require electrical measurements of the most basic
kind for their determination: the gyromagnetic ratios of
the shielded proton and helion, the von Klitzing constant
R
K
, the Josephson constant
K
J
, the product
K
2
J
R
K
, and
the Faraday constant. However, some of the results we
discuss were taken as input data for the 2002 adjust-
ment but were not included in the ï¬nal least-squares ad-
justment from which the 2002 recommended values were
obtained, mainly because of their comparatively large
uncertainties and hence low weight. Nevertheless, we
take them as input data in the 2006 adjustment because
they provide information on the overall consistency of
the available data and tests of the exactness of the rela-
tions
K
J
= 2
e/h
and
R
K
=
h/e
2
. The lone exception is
the low-ï¬eld measurement of the gyromagnetic ratio of
the helion reported by Tarbeev
et al.
(1989). Because of
its large uncertainty and strong disagreement with many
other data, we no longer consider it—see CODATA-02.
A. Shielded gyromagnetic ratios
γ
′
, the fine-structure
constant
α
, and the Planck constant
h
The gyromagnetic ratio
γ
of a bound particle of spin
quantum number
i
and magnetic moment
µ
is given by
γ
=
2
Ï€
f
B
=
ω
B
=
|
µ
|
i
¯
h
,
(245)
where
f
is the precession (that is, spin-flip) frequency and
ω
is the angular precession frequency of the particle in
the magnetic flux density
B
. The SI unit of
γ
is s
−
1
T
−
1
= C kg
−
1
= A s kg
−
1
. In this section we summarize
measurements of the gyromagnetic ratio of the shielded
proton
γ
′
p
=
2
µ
′
p
¯
h
,
(246)
and of the shielded helion
γ
′
h
=
2
|
µ
′
h
|
¯
h
,
(247)
where, as in previous sections that dealt with magnetic-
moment ratios involving these particles, the protons are
those in a spherical sample of pure H
2
O at 25
â—¦
C sur-
rounded by vacuum; and the helions are those in a spher-
ical sample of low-pressure, pure
3
He gas at 25
â—¦
C sur-
rounded by vacuum.
As discussed in detail in CODATA-98, two methods are
used to determine the shielded gyromagnetic ratio
γ
′
of a
particle: the low-ï¬eld method and the high-ï¬eld method.
In either case the measured current
I
in the experiment
can be expressed in terms of the product
K
J
R
K
, but
B
depends on
I
differently in the two cases. In essence, the
low-ï¬eld experiments determine
γ
′
/K
J
R
K
and the high-
ï¬eld experiments determine
γ
′
K
J
R
K
. This leads to the
relations
γ
′
=
Γ
′
90
(lo)
K
J
R
K
K
J
−
90
R
K
−
90
(248)
γ
′
=
Γ
′
90
(hi)
K
J
−
90
R
K
−
90
K
J
R
K
,
(249)
40
where
Γ
′
90
(lo) and
Γ
′
90
(hi) are the experimental values of
γ
′
in SI units that would result from the low- and high-
ï¬eld experiments if
K
J
and
R
K
had the exactly known
conventional values of
K
J
−
90
and
R
K
−
90
, respectively.
The quantities
Γ
′
90
(lo) and
Γ
′
90
(hi) are the input data
used in the adjustment, but the observational equations
take into account the fact that
K
J
−
90
6
=
K
J
and
R
K
−
90
6
=
R
K
.
Accurate values of
Γ
′
90
(lo) and
Γ
′
90
(hi) for the proton
and helion are of potential importance because they pro-
vide information on the values of
α
and
h
. Assuming the
validity of the relations
K
J
= 2
e/h
and
R
K
=
h/e
2
, the
following expressions apply to the four available proton
results and one available helion result:
Γ
′
p
−
90
(lo) =
K
J
−
90
R
K
−
90
g
e
−
4
µ
0
R
∞
µ
′
p
µ
e
−
α
3
,
(250)
Γ
′
h
−
90
(lo) =
−
K
J
−
90
R
K
−
90
g
e
−
4
µ
0
R
∞
µ
′
h
µ
e
−
α
3
,
(251)
Γ
′
p
−
90
(hi) =
c α
2
g
e
−
2
K
J
−
90
R
K
−
90
R
∞
µ
′
p
µ
e
−
1
h
.
(252)
Since the ï¬ve experiments, including necessary correc-
tions, were discussed fully in CODATA-98, only a brief
summary is given in the following sections. The ï¬ve re-
sults, together with the value of
α
inferred from each
low-ï¬eld measurement and the value of
h
inferred from
each high-ï¬eld measurement, are collected in Table XXI.
1. Low-field measurements
A number of national metrology institutes have long
histories of measuring the gyromagnetic ratio of the
shielded proton, motivated, in part, by their need to mon-
itor the stability of their practical unit of current based
on groups of standard cells and standard resistors. This
was prior to the development of the Josephson and quan-
tum hall effects for the realization of practical electric
units.
a. NIST: Low field
The most recent National Institute of
Standards and Technology (NIST), Gaithersburg, USA,
low-ï¬eld measurement was reported by Williams
et al.
(1989). Their result is
Γ
′
p
−
90
(lo) = 2
.
675 154 05(30)
×
10
8
s
−
1
T
−
1
[1
.
1
×
10
−
7
]
,
(253)
where
Γ
′
p
−
90
(lo) is related to
γ
′
p
by Eq. (248).
The value of
α
that may be inferred from this result
follows from Eq. (250). Using the 2006 recommended
values for the other relevant quantities, the uncertainties
of which are signiï¬cantly smaller than the uncertainty
of the NIST result (statements that also apply to the
following four similar calculations), we obtain
α
−
1
= 137
.
035 9879(51) [3
.
7
×
10
−
8
]
,
(254)
where the relative uncertainty is about one-third the rel-
ative uncertainty of the NIST value of
Γ
′
p
−
90
(lo) because
of the cube-root dependence of
α
on
Γ
′
p
−
90
(lo).
b. NIM: Low field
The latest low-ï¬eld proton gyromag-
netic ratio experiment carried out by researchers at the
National Institute of Metrology (NIM), Beijing, PRC,
yielded (Liu
et al.
, 1995)
Γ
′
p
−
90
(lo) = 2
.
675 1530(18)
×
10
8
s
−
1
T
−
1
[6
.
6
×
10
−
7
]
.
(255)
Based on Eq. (250), the inferred value of
α
from the
NIM result is
α
−
1
= 137
.
036 006(30) [2
.
2
×
10
−
7
]
.
(256)
c. KRISS/VNIIM: Low field
The determination of
γ
′
h
at
the Korea Research Institute of Standards and Science
(KRISS), Taedok Science Town, Republic of Korea, was
carried out in a collaborative effort with researchers
from the Mendeleyev All-Russian Research Institute for
Metrology (VNIIM), St. Petersburg, Russian Federation
(Kim
et al.
, 1995; Park
et al.
, 1999; Shifrin
et al.
, 1998a,b,
1999). The result of this work can be expressed as
Γ
′
h
−
90
(lo) = 2
.
037 895 37(37)
×
10
8
s
−
1
T
−
1
[1
.
8
×
10
−
7
]
,
(257)
and the value of
α
that may be inferred from it through
Eq. (251) is
α
−
1
= 137
.
035 9852(82) [6
.
0
×
10
−
8
]
.
(258)
2. High-field measurements
a. NIM:high field
The latest high-ï¬eld proton gyromag-
netic ratio experiment at NIM yielded (Liu
et al.
, 1995)
Γ
′
p
−
90
(hi) = 2
.
675 1525(43)
×
10
8
s
−
1
T
−
1
[1
.
6
×
10
−
6
]
,
(259)
where
Γ
′
p
−
90
(hi) is related to
γ
′
p
by Eq. (249). Its correla-
tion coefficient with the NIM low-ï¬eld result in Eq. (255)
is
r
(lo
,
hi) =
−
0
.
014
.
(260)
Based on Eq. (252), the value of
h
that may be inferred
from the NIM high-ï¬eld result is
h
= 6
.
626 071(11)
×
10
−
34
J s
[1
.
6
×
10
−
6
]
.
(261)
41
TABLE XXI Summary of data related to shielded gyromagnetic ratios of the proton and helion, and inferred values of
α
and
h
.
Quantity
Value
Relative standard
Identiï¬cation
Sect. and Eq.
uncertainty
u
r
Γ
′
p
−
90
(lo)
2
.
675 154 05(30)
×
10
8
s
−
1
T
−
1
1
.
1
×
10
−
7
NIST-89
VII.A.1.a (253)
α
−
1
137
.
035 9879(51)
3
.
7
×
10
−
8
VII.A.1.a (254)
Γ
′
p
−
90
(lo)
2
.
675 1530(18)
×
10
8
s
−
1
T
−
1
6
.
6
×
10
−
7
NIM-95
VII.A.1.b (255)
α
−
1
137
.
036 006(30)
2
.
2
×
10
−
7
VII.A.1.b (256)
Γ
′
h
−
90
(lo)
2
.
037 895 37(37)
×
10
8
s
−
1
T
−
1
1
.
8
×
10
−
7
KR/VN-98
VII.A.1.c (257)
α
−
1
137
.
035 9852(82)
6
.
0
×
10
−
8
VII.A.1.c (258)
Γ
′
p
−
90
(hi)
2
.
675 1525(43)
×
10
8
s
−
1
T
−
1
1
.
6
×
10
−
6
NIM-95
VII.A.2.a (259)
h
6
.
626 071(11)
×
10
−
34
J s
1
.
6
×
10
−
6
VII.A.2.a (261)
Γ
′
p
−
90
(hi)
2
.
675 1518(27)
×
10
8
s
−
1
T
−
1
1
.
0
×
10
−
6
NPL-79
VII.A.2.b (262)
h
6
.
626 0729(67)
×
10
−
34
J s
1
.
0
×
10
−
6
VII.A.2.b (263)
b. NPL: High field
The most accurate high-ï¬eld
γ
′
p
ex-
periment was carried out at NPL by Kibble and Hunt
(1979), with the result
Γ
′
p
−
90
(hi) = 2
.
675 1518(27)
×
10
8
s
−
1
T
−
1
[1
.
0
×
10
−
6
]
.
(262)
This leads to the inferred value
h
= 6
.
626 0729(67)
×
10
−
34
J s
[1
.
0
×
10
−
6
]
,
(263)
based on Eq. (252).
B. von Klitzing constant
R
K
and
α
Since the the quantum Hall effect, the von Klitzing
constant
R
K
associated with it, and the available deter-
minations of
R
K
are fully discussed in CODATA-98 and
CODATA-02, we only outline the main points here.
The quantity
R
K
is measured by comparing a quan-
tized Hall resistance
R
H
(
i
) =
R
K
/i
, where
i
is an in-
teger, to a resistance
R
whose value is known in terms
of the SI unit of resistance Ω. In practice, the latter
quantity, the ratio
R/
Ω, is determined by means of a cal-
culable cross capacitor, a device based on a theorem in
electrostatics discovered in the 1950s (Lampard, 1957;
Thompson and Lampard, 1956). The theorem allows
one to construct a cylindrical capacitor, generally called
a Thompson-Lampard calculable capacitor (Thompson,
1959), whose capacitance, to high accuracy, depends only
on its length.
As indicated in Sec. II, if one assumes the validity of
the relation
R
K
=
h/e
2
, then
R
K
and the ï¬ne-structure
constant
α
are related by
α
=
µ
0
c/
2
R
K
.
(264)
Hence, the relative uncertainty of the value of
α
that may
be inferred from a particular experimental value of
R
K
is
the same as the relative uncertainty of that value.
The values of
R
K
we take as input data in the 2006 ad-
justment and the corresponding inferred values values of
α
are given in the following sections and are summarized
in Table XXII.
1. NIST: Calculable capacitor
The result obtained at NIST is (Jeffery
et al.
, 1997)
[see also Jeffery
et al.
(1998)]
R
K
= 25 812
.
8 [1 + 0
.
322(24)
×
10
−
6
] Ω
= 25 812
.
808 31(62) Ω
[2
.
4
×
10
−
8
]
,
(265)
and is viewed as superseding the NIST result reported in
1989 by Cage
et al.
(1989). Work by Jeffery
et al.
(1999)
provides additional support for the uncertainty budget of
the NIST calculable capacitor.
The value of
α
that may be inferred from the NIST
value of
R
K
is, from Eq. (264),
α
−
1
= 137
.
036 0037(33) [2
.
4
×
10
−
8
]
.
(266)
2. NMI: Calculable capacitor
Based on measurements carried out at the National
Metrology Institute (NMI), Lindï¬eld, Australia, from
December 1994 to April 1995 and a complete reassess-
ment of uncertainties associated with their calculable ca-
pacitor and associated apparatus, Small
et al.
(1997) re-
ported the result
R
K
=
R
K
−
90
[1 + 0
.
4(4
.
4)
×
10
−
8
]
= 25 812
.
8071(11) Ω
[4
.
4
×
10
−
8
]
.
(267)
The value of
α
it implies is
α
−
1
= 137
.
035 9973(61) [4
.
4
×
10
−
8
]
.
(268)
42
TABLE XXII Summary of data related to the von Klitzing constant
R
K
and inferred values of
α
.
Quantity
Value
Relative standard
Identiï¬cation
Sect. and Eq.
uncertainty
u
r
R
K
25 812
.
808 31(62) Ω
2
.
4
×
10
−
8
NIST-97
VII.B.1 (265)
α
−
1
137
.
036 0037(33)
2
.
4
×
10
−
8
VII.B.1 (266)
R
K
25 812
.
8071(11) Ω
4
.
4
×
10
−
8
NMI-97
VII.B.2 (267)
α
−
1
137
.
035 9973(61)
4
.
4
×
10
−
8
VII.B.2 (268)
R
K
25 812
.
8092(14) Ω
5
.
4
×
10
−
8
NPL-88
VII.B.3 (269)
α
−
1
137
.
036 0083(73)
5
.
4
×
10
−
8
VII.B.3 (270)
R
K
25 812
.
8084(34) Ω
1
.
3
×
10
−
7
NIM-95
VII.B.4 (271)
α
−
1
137
.
036 004(18)
1
.
3
×
10
−
7
VII.B.4 (272)
R
K
25 812
.
8081(14) Ω
5
.
3
×
10
−
8
LNE-01
VII.B.5 (273)
α
−
1
137
.
036 0023(73)
5
.
3
×
10
−
8
VII.B.5 (274)
Because of problems associated with the 1989 NMI
value of
R
K
, only the result reported in 1997 is used
in the 2006 adjustment, as was the case in the 1998 and
2002 adjustments.
3. NPL: Calculable capacitor
The NPL calculable capacitor is similar in design to
those of NIST and NMI. The result for
R
K
reported by
Hartland
et al.
(1988) is
R
K
= 25 812
.
8 [1 + 0
.
356(54)
×
10
−
6
] Ω
= 25 812
.
8092(14) Ω
[5
.
4
×
10
−
8
]
,
(269)
and the value of
α
that one may infer from it is
α
−
1
= 137
.
036 0083(73) [5
.
4
×
10
−
8
]
.
(270)
4. NIM: Calculable capacitor
The NIM calculable cross capacitor differs markedly
from the version used at NIST, NMI, and NPL. The four
bars (electrodes) that comprise the capacitor are horizon-
tal rather than vertical and the length that determines
its known capacitance is ï¬xed rather than variable. The
NIM result for
R
K
, as reported by Zhang
et al.
(1995), is
R
K
= 25 812
.
8084(34) Ω
[1
.
3
×
10
−
7
]
,
(271)
which implies
α
−
1
= 137
.
036 004(18) [1
.
3
×
10
−
7
]
.
(272)
5. LNE: Calculable capacitor
The value of
R
K
obtained at the Laboratoire National
d’Essais (LNE), Trappes, France, is (Trapon
et al.
, 2003,
2001)
R
K
= 25 812
.
8081(14) Ω
[5
.
3
×
10
−
8
]
,
(273)
which implies
α
−
1
= 137
.
036 0023(73) [5
.
3
×
10
−
8
]
.
(274)
The LNE Thompson-Lampard calculable capacitor is
unique among all calculable capacitors in that it con-
sists of ï¬ve horizontal bars arranged at the corners of a
regular pentagon.
C. Josephson constant
K
J
and
h
Again, since the Josephson effect, the Josephson con-
stant
K
J
associated with it, and the available determi-
nations of
K
J
are fully discussed in CODATA-98 and
CODATA-02, we only outline the main points here.
The quantity
K
J
is measured by comparing a Joseph-
son voltage
U
J
(
n
) =
nf /K
J
to a high voltage
U
whose
value is known in terms of the SI unit of voltage V. Here,
n
is an integer and
f
is the frequency of the microwave ra-
diation applied to the Josephson device. In practice, the
latter quantity, the ratio
U
/V, is determined by counter-
balancing an electrostatic force arising from the voltage
U
with a known gravitational force.
A measurement of
K
J
can also provide a value of
h
.
If, as discussed in Sec. II, we assume the validity of the
relation
K
J
= 2
e/h
and recall that
α
=
e
2
/
4
Ï€
Ç«
0
¯
h
=
µ
0
ce
2
/
2
h
, we have
h
=
8
α
µ
0
cK
2
J
.
(275)
Since
u
r
of the ï¬ne-structure constant is signiï¬cantly
smaller than
u
r
of the measured values of
K
J
, the
u
r
of
h
derived from Eq. (275) will be essentially twice the
u
r
of
K
J
.
43
The values of
K
J
we take as input data in the 2006 ad-
justment, and the corresponding inferred values of
h
, are
given in the following two sections and are summarized
in Table XXIII. Also summarized in that table are the
measured values of the product
K
2
J
R
K
and the quantity
F
90
related to the Faraday constant
F
, together with
their corresponding inferred values of
h
. These results
are discussed below in Secs. VII.D and VII.E.
1. NMI: Hg electrometer
The determination of
K
J
at NMI, carried out using an
apparatus called a liquid-mercury electrometer, yielded
the result (Clothier
et al.
, 1989)
K
J
= 483 594
1 + 8
.
087(269)
×
10
−
6
GHz
/
V
= 483 597
.
91(13) GHz
/
V
[2
.
7
×
10
−
7
]
.
(276)
Equation (275), the NMI value of
K
J
, and the 2006 rec-
ommended value of
α
, which has a much smaller
u
r
, yields
an inferred value for the Planck constant of
h
= 6
.
626 0684(36)
×
10
−
34
J s
[5
.
4
×
10
−
7
]
.
(277)
2. PTB: Capacitor voltage balance
The determination of
K
J
at PTB was carried out by
using a voltage balance consisting of two coaxial cylindri-
cal electrodes (Funck and Sienknecht, 1991; Sienknecht
and Funck, 1985, 1986). Taking into account the correc-
tion associated with the reference capacitor used in the
PTB experiment as described in CODATA-98, the result
of the PTB determination is
K
J
= 483 597
.
96(15) GHz
/
V
[3
.
1
×
10
−
7
]
,
(278)
from which we infer, using Eq. (275),
h
= 6
.
626 0670(42)
×
10
−
34
J s
[6
.
3
×
10
−
7
]
.
(279)
D. Product
K
2
J
R
K
and
h
A value of the product
K
2
J
R
K
is of importance to the
determination of the Planck constant
h
, because if one
assumes that the relations
K
J
= 2
e/h
and
R
K
=
h/e
2
are valid, then
h
=
4
K
2
J
R
K
.
(280)
The product
K
2
J
R
K
is determined by comparing electrical
power known in terms of a Josephson voltage and quan-
tized Hall resistance to the equivalent mechanical power
known in the SI unit W = m
2
kg s
−
3
. The comparison
is carried out using an apparatus known as a moving-coil
watt balance ï¬rst proposed by Kibble (1975) at NPL. To
date two laboratories, NPL and NIST, have determined
K
2
J
R
K
using this method.
1. NPL: Watt balance
Shortly after Kibble’s original proposal in 1975, Kibble
and Robinson (1977) carried out a feasibility study of
the idea based on experience with the NPL apparatus
that was used to determine
γ
′
p
by the high-ï¬eld method
(Kibble and Hunt, 1979). The work continued and led to
the publication in 1990 by Kibble
et al.
(1990) of a result
with an uncertainty of about 2 parts in 10
7
. This result,
discussed in detail in CODATA-98 and which was taken
as an input datum in the 1998 and 2002 adjustments,
and which we also take as an input datum in the 2006
adjustment, may be expressed as
K
2
J
R
K
=
K
2
J
−
NPL
R
K
−
NPL
[1 + 16
.
14(20)
×
10
−
6
]
= 6
.
036 7625(12)
×
10
33
J
−
1
s
−
1
[2
.
0
×
10
−
7
]
,
(281)
where
K
J
−
NPL
= 483 594 GHz/V and
R
K
−
NPL
=
25 812
.
809 2 Ω. The value of
h
that may be inferred from
the NPL result is, according to Eq. (280),
h
= 6
.
626 0682(13)
×
10
−
34
J s
[2
.
0
×
10
−
7
]
.
(282)
Based on the experience gained in this experiment,
NPL researchers designed and constructed what is es-
sentially a completely new apparatus, called the NPL
Mark II watt balance, that could possibly achieve a re-
sult for
K
2
J
R
K
with an uncertainty of a few parts in 10
8
(Kibble and Robinson, 2003; Robinson and Kibble, 1997).
Although the balance itself employs the same balance
beam as the previous NPL watt balance, little else from
that experiment is retained in the new experiment.
Over 1000 measurements in vacuum were carried out
with the MK II between January 2000 and November
2001. Many were made in an effort to identify the cause
of an observed fractional change in the value of
K
2
J
R
K
of
about 3
×
10
−
7
that occurred in mid-April 2000 (Robinson
and Kibble, 2002). A change in the alignment of the
apparatus was suspected of contributing to the shift.
Signiï¬cant improvements were subsequently made in
the experiment and very recently, based on measure-
ments carried out from October 2006 to March 2007, the
initial result from MK II,
h
= 6
.
626 070 95(44) J s [6
.
6
×
10
−
8
], was reported by Robinson and Kibble (2007) as-
suming the validity of Eq. (280). Although this result
became available much too late to be considered for the
2006 adjustment, we do note that it lies between the
value of
h
inferred from the 2007 NIST result for
K
2
J
R
K
discussed in Sec. VII.D.2.b, and that inferred from the
measurement of the molar volume of silicon
V
m
(Si) dis-
cussed in Sec. VIII.B. The NPL work is continuing and
a result with a smaller uncertainty is anticipated (Robin-
son and Kibble, 2007).
2. NIST: Watt balance
44
TABLE XXIII Summary of data related to the Josephson constant
K
J
, the product
K
2
J
R
K
, and the Faraday constant
F
, and
inferred values of
h
.
Quantity
Value
Relative standard
Identiï¬cation
Sect. and Eq.
uncertainty
u
r
K
J
483 597
.
91(13) GHz V
−
1
2
.
7
×
10
−
7
NMI-89
VII.C.1 (276)
h
6
.
626 0684(36)
×
10
−
34
J s
5
.
4
×
10
−
7
VII.C.1 (277)
K
J
483 597
.
96(15) GHz V
−
1
3
.
1
×
10
−
7
PTB-91
VII.C.2 (278)
h
6
.
626 0670(42)
×
10
−
34
J s
6
.
3
×
10
−
7
VII.C.2 (279)
K
2
J
R
K
6
.
036 7625(12)
×
10
33
J
−
1
s
−
1
2
.
0
×
10
−
7
NPL-90
VII.D.1 (281)
h
6
.
626 0682(13)
×
10
−
34
J s
2
.
0
×
10
−
7
VII.D.1 (282)
K
2
J
R
K
6
.
036 761 85(53)
×
10
33
J
−
1
s
−
1
8
.
7
×
10
−
8
NIST-98
VII.D.2.a (283)
h
6
.
626 068 91(58)
×
10
−
34
J s
8
.
7
×
10
−
8
VII.D.2.a (284)
K
2
J
R
K
6
.
036 761 85(22)
×
10
33
J
−
1
s
−
1
3
.
6
×
10
−
8
NIST-07
VII.D.2.b (287)
h
6
.
626 068 91(24)
×
10
−
34
J s
3
.
6
×
10
−
8
VII.D.2.b (288)
F
90
96 485
.
39(13) C mol
−
1
1
.
3
×
10
−
6
NIST-80
VII.E.1 (295)
h
6
.
626 0657(88)
×
10
−
34
J s
1
.
3
×
10
−
6
VII.E.1 (296)
a. 1998 measurement
Work on a moving-coil watt bal-
ance at NIST began shortly after Kibble made his 1975
proposal. A ï¬rst result with
u
r
= 1
.
3
×
10
−
6
was re-
ported by NIST researchers in 1989 (Cage
et al.
, 1989).
Signiï¬cant improvements were then made to the appara-
tus and the ï¬nal result from this phase of the NIST effort
was reported in 1998 by Williams
et al.
(1998):
K
2
J
R
K
=
K
2
J
−
90
R
K
−
90
[1
−
8(87)
×
10
−
9
]
= 6
.
036 761 85(53)
×
10
33
J
−
1
s
−
1
[8
.
7
×
10
−
8
]
.
(283)
A lengthy paper giving the details of the NIST 1998 watt
balance experiment was published in 2005 by Steiner
et al.
(2005a). This was the NIST result taken as an input
datum in the 1998 and 2002 adjustments; although the
1989 result was consistent with that of 1998, its uncer-
tainty was about 15 times larger. The value of
h
implied
by the 1998 NIST result for
K
2
J
R
K
is
h
= 6
.
626 068 91(58)
×
10
−
34
J s
[8
.
7
×
10
−
8
]
.
(284)
b. 2007 measurement
Based on the lessons learned in
the decade-long effort with a watt balance operating in
air that led to their 1998 result for
K
2
J
R
K
, the NIST
watt-balance researchers initiated a new program with
the goal of measuring
K
2
J
R
K
with
u
r
≈
10
−
8
. The ex-
periment was completely disassembled and renovations
to the research facility were made to improve vibration
isolation, reduce electromagnetic interference, and incor-
porate a multilayer temperature control system. A new
watt balance with major changes and improvements was
constructed with little remaining of the earlier apparatus
except the superconducting magnet used to generate the
required radial magnetic flux density and the wheel used
as the balance.
The most notable change in the experiment is that in
the new apparatus, the entire balance mechanism and
moving coil are in vacuum, which eliminates the uncer-
tainties of the corrections in the previous experiment for
the index of refraction of air in the laser position mea-
surements (
u
r
= 43
×
10
−
9
) and for the buoyancy force
exerted on the mass standard (
u
r
= 23
×
10
−
9
). Align-
ment uncertainties were reduced by over a factor of four
by (i) incorporating a more comprehensive understand-
ing of all degrees of freedom involving the moving coil;
and (ii) the application of precise alignment techniques
for all degrees of freedom involving the moving coil, the
superconducting magnet, and the velocity measuring in-
terferometers. Hysteresis effects were reduced by a fac-
tor of four by using a diamond-like carbon coated knife
edge and flat (Schwarz
et al.
, 2001), employing a hys-
teresis erasure procedure, and reducing the balance de-
flections during mass exchanges with improved control
systems. A programmable Josephson array voltage stan-
dard (Benz
et al.
, 1997) was connected directly to the
experiment, eliminating two voltage transfers required in
the old experiment and reducing the voltage traceability
uncertainty by a factor of 15.
A total of 6023 individual values of
W
90
/W were ob-
tained over the two year period from March 2003 to
February 2005 as part of the effort to develop and im-
prove the new experiment. The results are converted
to the notation used here by the relation
W
90
/
W =
K
2
J
−
90
R
K
−
90
/K
2
J
R
K
discussed in CODATA-98. The ini-
tial result from that work was reported in 2005 by Steiner
45
et al.
(2005b):
K
2
J
R
K
=
K
2
J
−
90
R
K
−
90
[1
−
24(52)
×
10
−
9
]
= 6
.
036 761 75(31)
×
10
33
J
−
1
s
−
1
[5
.
2
×
10
−
8
]
.
(285)
This yields a value for the Planck constant of
h
= 6
.
626 069 01(34)
×
10
−
34
J s
[5
.
2
×
10
−
8
]
.
(286)
This result for
K
2
J
R
K
was obtained from data spanning
the ï¬nal 7 months of the 2 year period. It is based on the
weighted mean of 48
W
90
/W measurement sets using a
Au mass standard and 174 sets using a PtIr mass stan-
dard, where a typical measurement set consists of 12 to
15 individual values of
W
90
/W. The 2005 NIST result is
consistent with the 1998 NIST result but its uncertainty
has been reduced by a factor of 1.7.
Following this initial effort with the new apparatus,
further improvements were made to it in order to re-
duce the uncertainties from various systematic effects,
the most notable reductions being in the determination
of the local acceleration due to gravity
g
(a factor of 2.5),
the effect of balance wheel surface roughness (a factor of
10), and the effect of the magnetic susceptibility of the
mass standard (a factor of 1.6). An improved result was
then obtained based on 2183 values of
W
90
/W recorded
in 134 measurement sets from January 2006 to June 2006.
Due to a wear problem with the gold mass standard, only
a PtIr mass standard was used in these measurements.
The result, ï¬rst reported at a conference in 2006 and sub-
sequently published in the proceedings of the conference
in 2007 by Steiner
et al.
(2007), is
K
2
J
R
K
=
K
2
J
−
90
R
K
−
90
[1
−
8(36)
×
10
−
9
]
= 6
.
036 761 85(22)
×
10
33
J
−
1
s
−
1
[3
.
6
×
10
−
8
]
.
(287)
The value of
h
that may be inferred from this value of
K
2
J
R
K
is
h
= 6
.
626 068 91(24)
×
10
−
34
J s
[3
.
6
×
10
−
8
]
.
(288)
The 2007 NIST result for
K
2
J
R
K
is consistent with and
has an uncertainty smaller by a factor of 1.4 than the
uncertainty of the 2005 NIST result. However, because
the two results are from essentially the same experiment
and hence are highly correlated, we take only the 2007
result as an input datum in the 2006 adjustment.
On the other hand, the experiment on which the NIST
2007 result is based is only slightly dependent on the ex-
periment on which the NIST 1998 result is based, as can
be seen from the above discussions. Thus, in keeping with
our practice in similar cases, most notably the 1982 and
1999 LAMPF measurements of muonium Zeeman transi-
tion frequencies (see Sec. VI.B.2), we also take the NIST
1998 result in Eq. (283) as an input datum in the 2006
adjustment. But to ensure that we do not give undue
weight to the NIST work, an analysis of the uncertainty
budgets of the 1998 and 2007 NIST results was performed
to determine the level of correlation. Of the relative un-
certainty components listed in Table II of Williams
et al.
(1998) and in Table 2 of Steiner
et al.
(2005b) but as
updated in Table 1 of Steiner
et al.
(2007), the largest
common relative uncertainty components were from the
magnetic flux proï¬le ï¬t due to the use of the same anal-
ysis routine (16
×
10
−
9
); leakage resistance and electri-
cal grounding since the same current supply was used
in both experiments (10
×
10
−
9
); and the determination
of the local gravitational acceleration
g
due to the use of
the same absolute gravimeter (7
×
10
−
9
). The correlation
coefficient was thus determined to be
r
(
K
2
J
R
k
-98
, K
2
J
R
k
-07) = 0
.
14
,
(289)
which we take into account in our calculations as appro-
priate.
3. Other values
Although there is no competitive published value of
K
2
J
R
K
other than those from NPL and NIST discussed
above, it is worth noting that at least three additional
laboratories have watt-balance experiments in progress:
the Swiss Federal Office of Metrology and Accreditation
(METAS), Bern-Wabern, Switzerland, the LNE, and the
BIPM. Descriptions of these efforts may be found in the
papers by Beer
et al.
(2003), Genev`es
et al.
(2005), and
Picard
et al.
(2007), respectively.
4. Inferred value of
K
J
It is of interest to note that a value of
K
J
with an un-
certainty signiï¬cantly smaller than those of the directly
measured values discussed in Sec. VII.C can be obtained
from the directly measured watt-balance values of
K
2
J
R
K
,
together with the directly measured calculable-capacitor
values of
R
K
, without assuming the validity of the re-
lations
K
J
= 2
e/h
and
R
K
=
h/e
2
. The relevant ex-
pression is simply
K
J
= [(
K
2
J
R
K
)
W
/
(
R
K
)
C
]
1
/
2
, where
(
K
2
J
R
K
)
W
is from the watt-balance, and (
R
K
)
C
is from
the calculable capacitor.
Using the weighted mean of the three watt-balance re-
sults for
K
2
J
R
K
discussed in this section and the weighted
mean of the ï¬ve calculable-capacitor results for
R
K
dis-
cussed in Sec VII.B, we have
K
J
=
K
J
−
90
[1
−
2
.
8(1
.
9)
×
10
−
8
]
= 483 597
.
8865(94) GHz
/
V
[1
.
9
×
10
−
8
]
,
(290)
which is consistent with the directly measured values but
has an uncertainty that is smaller by more than an order
of magnitude. This result is implicitly included in the
least-squares adjustment, even though the explicit value
for
K
J
obtained here is not used as an input datum.
46
E. Faraday constant
F
and
h
The Faraday constant
F
is equal to the Avogadro con-
stant
N
A
times the elementary charge
e
,
F
=
N
A
e
; its
SI unit is coulomb per mol, C mol
−
1
= A s mol
−
1
. It
determines the amount of substance
n
(
X
) of an entity
X
that is deposited or dissolved during electrolysis by the
passage of a quantity of electricity, or charge,
Q
=
It
,
due to the flow of a current
I
in a time
t
. In particu-
lar, the Faraday constant
F
is related to the molar mass
M
(
X
) and valence
z
of entity
X
by
F
=
ItM
(
X
)
zm
d
(
X
)
,
(291)
where
m
d
(
X
) is the mass of entity
X
dissolved as the
result of transfer of charge
Q
=
It
during the electrolysis.
It follows from the relations
F
=
N
A
e
,
e
2
= 2
αh/µ
0
c
,
m
e
= 2
R
∞
h/cα
2
, and
N
A
=
A
r
(e)
M
u
/m
e
, where
M
u
=
10
−
3
kg mol
−
1
, that
F
=
A
r
(e)
M
u
R
∞
c
2
µ
0
α
5
h
1
/
2
.
(292)
Since, according to Eq. (291),
F
is proportional to the
current
I
, and
I
is inversely proportional to the prod-
uct
K
J
R
K
if the current is determined in terms of the
Josephson and quantum Hall effects, we may write
F
90
=
K
J
R
K
K
J
−
90
R
K
−
90
A
r
(e)
M
u
R
∞
c
2
µ
0
α
5
h
1
/
2
,
(293)
where
F
90
is the experimental value of
F
in SI units that
would result from the Faraday experiment if
K
J
=
K
J
−
90
and
R
K
=
R
K
−
90
. The quantity
F
90
is the input datum
used in the adjustment, but the observational equation
accounts for the fact that
K
J
−
90
6
=
K
J
and
R
K
−
90
6
=
R
K
.
If one assumes the validity of the expressions
K
J
= 2
e/h
and
R
K
=
h/e
2
, then in terms of adjusted constants,
Eq. (293) can be written as
F
90
=
cM
u
K
J
−
90
R
K
−
90
A
r
(e)
α
2
R
∞
h
.
(294)
1. NIST: Ag coulometer
There is one high-accuracy experimental value of
F
90
available, that from NIST (Bower and Davis, 1980). The
NIST experiment used a silver dissolution coulometer
based on the anodic dissolution by electrolysis of silver,
which is monovalent, into a solution of perchloric acid
containing a small amount of silver perchlorate. The ba-
sic chemical reaction is Ag
→
Ag
+
+ e
−
and occurs at
the anode, which in the NIST work was a highly puriï¬ed
silver bar.
As discussed in detail in CODATA-98, the NIST ex-
periment leads to
F
90
= 96 485
.
39(13) C mol
−
1
[1
.
3
×
10
−
6
]
.
(295)
[Note that the new AME2003 values of
A
r
(
107
Ag) and
A
r
(
109
Ag) in Table II have no effect on this result.]
The value of
h
that may be inferred from the NIST
result, Eq. (294), and the 2006 recommended values for
the other quantities is
h
= 6
.
626 0657(88)
×
10
−
34
J s
[1
.
3
×
10
−
6
]
,
(296)
where the uncertainties of the other quantities are negli-
gible compared to the uncertainty of
F
90
.
VIII. MEASUREMENTS INVOLVING SILICON
CRYSTALS
Here we discuss experiments relevant to the 2006 ad-
justment that use highly pure, nearly crystallographically
perfect, single crystals of silicon. However, because one
such experiment determines the quotient
h/m
n
, where
m
n
is the mass of the neutron, for convenience and be-
cause any experiment that determines the ratio of the
Planck constant to the mass of a fundamental particle or
atom provides a value of the ï¬ne-structure constant
α
,
we also discuss in this section two silicon-independent ex-
periments: the 2002 Stanford University, Stanford, USA,
measurement of
h/m
(
133
Cs) and the 2006 Laboratoire
Kastler-Brossel or LKB measurement of
h/m
(
87
Rb).
In this section, W4.2a, NR3, W04 and NR4 are short-
ened forms of the full crystal designations WASO 4.2a,
NRLM3, WASO 04, and NRLM4, respectively, for use in
quantity symbols. No distinction is made between differ-
ent crystals taken from the same ingot. As we use the
current laboratory name to identify a result rather than
the laboratory name at the time the measurement was
carried out, we have replaced IMGC and NRLM with
INRIM and NMIJ—see the glossary in CODATA-98.
A.
{
220
}
lattice spacing of silicon
d
220
A value of the
{
220
}
lattice spacing of a silicon crys-
tal in meters is relevant to the 2006 adjustment not
only because of its role in determining
α
from
h/m
n
(see Sec. VIII.D.1), but also because of its role in de-
termining the relative atomic mass of the neutron
A
r
(n)
(see Sec.VIII.C). Further, together with the measured
value of the molar volume of silicon
V
m
(Si), it can pro-
vide a competitive value of
h
(see Sec. VIII.B).
Various aspects of silicon and its crystal plane spac-
ings of interest here are reviewed in CODATA-98 and
CODATA-02. [See also the reviews of Becker (2003),
Mana (2001), and Becker (2001)]. Some points worth
noting are that silicon is a cubic crystal with
n
= 8
atoms per face-centered cubic unit cell of edge length (or
lattice parameter)
a
= 543 pm with
d
220
=
a/
√
8. The
three naturally occurring isotopes of Si are
28
Si,
29
Si,
and
30
Si, and the amount-of-substance fractions
x
(
28
Si),
x
(
29
Si), and
x
(
30
Si) of natural silicon are approximately
0.92, 0.05, and 0.03, respectively.
47
Although the
{
220
}
lattice spacing of Si is not a funda-
mental constant in the usual sense, for practical purposes
one can consider
a
, and hence
d
220
, of an impurity-free,
crystallographically perfect or “ideal†silicon crystal un-
der speciï¬ed conditions, principally of temperature, pres-
sure, and isotopic composition, to be an invariant of na-
ture. The reference temperature and pressure currently
adopted are
t
90
= 22
.
5
â—¦
C and
p
= 0 (that is, vacuum),
where
t
90
is Celsius temperature on the International
Temperature Scale of 1990 (ITS-90) (Preston-Thomas,
1990a,b). However, no reference values for
x
(
A
Si) have
yet been adopted, because the variation of
a
due to the
variation of the isotopic composition of the crystals used
in high-accuracy experiments is taken to be negligible
at the current level of experimental uncertainty in
a
. A
much larger effect on
a
is the impurities that the silicon
crystal contains—mainly carbon (C), oxygen (O), and ni-
trogen (N)—and corrections must be applied to convert
the
{
220
}
lattice spacing
d
220
(
X
) of a real crystal
X
to
the
{
220
}
lattice spacing
d
220
of an “ideal†crystal.
Nevertheless, we account for the possible variation in
the lattice spacing of different samples taken from the
same ingot by including an additional component (or
components) of relative standard uncertainty in the un-
certainty of any measurement result involving a silicon
lattice spacing (or spacings). This additional component
is typically
√
2
×
10
−
8
for each crystal, but it can be
larger, for example, (3
/
2)
√
2
×
10
−
8
in the case of crystal
MO
∗
discussed below, because it is known to contain a
comparatively large amount of carbon; see Secs. III.A.c
and III.I of CODATA-98 for details. For simplicity, we do
not explicitly mention our inclusion of such components
in the following discussion.
Further, because of this component and the use of the
same samples in different experiments, and because of the
existence of other common components of uncertainty in
the uncertainty budgets of different experimental results
involving silicon crystals, many of the input data dis-
cussed in the following sections are correlated. In most
cases we do not explicity give the relevant correlation
coefficients in the text; instead Table XXXI in Sec. XII
provides all the non-negligible correlation coefficients of
the input data listed in Table XXX.
1. X-ray/optical interferometer measurements of
d
220
(
X
)
High accuracy measurements of
d
220
(
X
), where
X
de-
notes any one of various crystals, are carried out using a
combined x-ray and optical interferometer (XROI) fab-
ricated from a single crystal of silicon taken from one of
several well-characterized single crystal ingots or boules.
As discussed in CODATA-98, an XROI is a device that
enables x-ray fringes of unknown period
d
220
(
X
) to be
compared with optical fringes of known period by mov-
ing one of the crystal plates of the XROI, called the ana-
lyzer. Also discussed there are the XROI measurements
of
d
220
(
W4
.
2a
),
d
220
(
MO
∗
), and
d
220
(
NR3
), which were car-
(
d
220
/
fm
−
192 015)
×
10
3
540
550
560
570
580
590
600
610
540
550
560
570
580
590
600
610
10
−
7
d
220
d
220
(
W4
.
2a
) PTB-81
d
220
PTB-81
d
220
(
NR3
) NMIJ-04
d
220
NMIJ-04
d
220
h/m
n
d
220
(
W04
) PTB-99
d
220
(
MO
∗
) INRIM-07
d
220
INRIM-07
d
220
(
W4
.
2a
) INRIM-07
d
220
INRIM-07
d
220
CODATA-02
d
220
CODATA-06
FIG. 1 Inferred values (open circles) of
d
220
from various
measurements (solid circles) of
d
220
(
X
). For comparison, the
2002 and 2006 CODATA recommended values of
d
220
are also
shown.
ried out at the PTB in Germany (Becker
et al.
, 1981),
the Istituto Nazionale di Ricerca Metrologica, Torino,
Italy (INRIM) (Basile
et al.
, 1994), and the National
Metrology Institute of Japan (NMIJ), Tsukuba, Japan
(Nakayama and Fujimoto, 1997), respectively.
For the reasons discussed in CODATA-02 and subse-
quently documented by Cavagnero
et al.
(2004a,b), only
the NMIJ 1997 result was taken as an input datum in
the 2002 adjustment. However, further work, published
in the Erratum to that paper, showed that the results
obtained at INRIM given in the paper were in error. Af-
ter the error was discovered, additional work was carried
out at INRIM to fully understand and correct it. New
results were then reported at a conference in 2006 and
published in the conference proceedings (Becker
et al.
,
2007). Thus, as summarized in Table XXIV and com-
pared in Fig. 1, we take as input data the four absolute
{
220
}
lattice spacing values determined in three different
laboratories, as discussed in the following three sections.
The last value in the table, which is not an XROI result,
is discussed in Sec. VIII.D.1.
We point out that not only do we take the
{
220
}
lat-
tice spacings of the crystals WASO 4.2a, NRLM3, and
MO
∗
as adjusted constants, but also the
{
220
}
lattice
spacings of the crystals N, WASO 17, ILL, WASO 04,
and NRLM4, because they too were involved in various
experiments, including the
d
220
lattice spacing fractional
difference measurements discussed in Sec VIII.A.2.
a. PTB measurement of
d
220
(
W4
.
2a
)
The following value,
identiï¬ed as PTB-81 in Table XXIV and Fig. 1, is the
48
TABLE XXIV Summary of measurements of the absolute
{
220
}
lattice spacing of various silicon crystals and inferred values
of
d
220
.
Quantity
Value
Relative standard
Identiï¬cation
Sect. and Eq.
uncertainty
u
r
d
220
(
W4
.
2a
)
192 015
.
563(12) fm
6
.
2
×
10
−
8
PTB-81
VIII.A.1.a (297)
d
220
192 015
.
565(13) fm
6
.
5
×
10
−
8
d
220
(
NR3
)
192 015
.
5919(76) fm
4
.
0
×
10
−
8
NMIJ-04
VIII.A.1.b (298)
d
220
192 015
.
5973(84) fm
4
.
4
×
10
−
8
d
220
(
W4
.
2a
)
192 015
.
5715(33) fm
1
.
7
×
10
−
8
INRIM-07
VIII.A.1.c (299)
d
220
192 015
.
5732(53) fm
2
.
8
×
10
−
8
d
220
(
MO
∗
)
192 015
.
5498(51) fm
2
.
6
×
10
−
8
INRIM-07
VIII.A.1.c (300)
d
220
192 015
.
5685(67) fm
3
.
5
×
10
−
8
h/m
n
d
220
(
W04
)
2060
.
267 004(84) m s
−
1
4
.
1
×
10
−
8
PTB-99
VIII.D.1 (322)
d
220
192 015
.
5982(79) fm
4
.
1
×
10
−
8
VIII.D.1 (325)
original result obtained at PTB as reported by Becker
et al.
(1981) and discussed in CODATA-98:
d
220
(
W4
.
2a
) = 192 015
.
563(12) fm
[6
.
2
×
10
−
8
]
.
(297)
b. NMIJ measurement of
d
220
(
NR3
)
The following value,
identiï¬ed as NMIJ-04 in Table XXIV and Fig. 1, reflects
the NMIJ efforts in the early and mid-1990s as well as
the work carried out in the early 2000s:
d
220
(
NR3
) = 192 015
.
5919(76) fm
[4
.
0
×
10
−
8
]
.
(298)
This value, reported by Cavagnero
et al.
(2004a,b), is
the weighted mean of the 1997 NIMJ result of Nakayama
and Fujimoto (1997) discussed in CODATA-98 and
CODATA-02, and the result from a new series of mea-
surements performed at NMIJ from December 2002 to
February 2003 with nearly the same apparatus. One of
the principle differences from the earlier experiment was
the much improved temperature control system of the
room in which the NMIJ XROI was located; the new sys-
tem provided a temperature stability of about 1 mK/d
and allowed the temperature of the XROI to be set to
within 20 mK of 22
.
5
â—¦
C.
The result for
d
220
(
NR3
) from the 2002-2003 measure-
ments is based on 61 raw data. In each measurement,
the phases of the x-ray and optical fringes (optical or-
ders) were compared at the 0th, 100th, and 201st optical
orders, and then with the analyzer moving in the reverse
direction, at the 201st, 100th, and 0th orders. The
n/m
ratio was calculated from the phase of the x-ray fringe at
the 0th and 201st orders, where
n
is the number of x-ray
fringes in
m
optical fringes (optical orders) of period
λ/
2,
where
λ
is the wavelength of the laser beam used in the
optical interferometer and
d
220
(
NR3
) = (
λ/
2)
/
(
n/m
).
In the new work, the fractional corrections to
d
220
(
NR3
), in parts in 10
9
, total 181(35), the largest by far
being the correction 173(33) for laser beam diffraction.
The next largest is 5.0(7.1) for laser beam alignment.
The statistical uncertainty is 33 (Type A).
Before calculating the weighted mean of the new and
1997 results for
d
220
(
NR3
), Cavagnero
et al.
(2004a,b) re-
vised the 1997 value based on a reanalysis of the old
experiment, taking into account what was learned in the
new experiment. Not only did the reanalysis result in
a reduction of the statistical uncertainty from (again, in
parts in 10
9
) 50 to 1.8 due to a better understanding of
the undulation of
n/m
values as a function of time, but
also in more reliable estimates of the corrections for laser
beam diffraction and laser beam alignment. Indeed, the
fractional corrections for the revised 1997 NMIJ value
of
d
220
(
NR3
) total 190(38) compared to the original total
of 173(14), and the ï¬nal uncertainty of the revised 1997
value is
u
r
= 3
.
8
×
10
−
9
compared to
u
r
= 4
.
8
×
10
−
9
of
the new value.
For completeness, we note that two possible correc-
tions to the NMIJ result have been discussed in the lit-
erature. In the Erratum to Cavagnero
et al.
(2004a,b), it
is estimated that a fractional correction to the value of
d
220
(
NR3
) in Eq. (298) of
−
1
.
3
×
10
−
8
may be required
to account for the contamination of the NMIJ laser by
a parasitic component of laser radiation as in the case
of the INRIM laser discussed in the next section. How-
ever, it is not applied, because of its comparatively small
size and the fact that no measurements of
d
220
(
NR3
) have
yet been made at NMIJ (or INRIM) with a problem-free
laser that conï¬rm the correction, as has been done at
INRIM for the crystals WASO 4.2a and MO
∗
.
In Fujimoto
et al.
(2007), it is estimated, based on
a Monte Carlo simulation, that the fractional correc-
tion to
d
220
(
NR3
) labeled “Fresnel diffraction†in Ta-
ble I of Nakayama and Fujimoto (1997) and equal to
16
.
0(8)
×
10
−
8
should be 10(3)
×
10
−
8
. The change arises
from taking into account the misalignment of the inter-
fering beams in the laser interferometer. Because this
additional diffraction effect was present in both the 1997
and 2002-2003 measurements but was not considered in
the reanalysis of the 1997 result nor in the analysis of
the 2002-2003 data, it implies that the weighted mean
49
value for
d
220
(
NR3
) in Eq. (298) should be reduced by this
amount and its
u
r
increased from 4
.
0
×
10
−
8
to 5
.
0
×
10
−
8
.
However, because the data required for the calculation
were not precisely known (they were not logged in the
laboratory notebooks because the experimenters were un-
aware of their importance), the correction is viewed as
somewhat conjectural and thus that applying it would
not be justiï¬ed (Mana and Massa, 2006).
c. INRIM measurement of
d
220
(
W4
.
2a
)
and
d
220
(
MO
∗
)
The
following two new INRIM values, with identiï¬er INRIM-
07, were reported by Becker
et al.
(2007):
d
220
(
W4
.
2a
) = 192 015
.
5715(33) fm
[1
.
7
×
10
−
8
]
(299)
d
220
(
MO
∗
) = 192 015
.
5498(51) fm [2
.
6
×
10
−
8
]
.
(300)
The correlation coefficient of these values is 0.057, based
on the detailed uncertainty budget for
d
220
(
MO
∗
) in Cav-
agnero
et al.
(2004a,b) and the similar uncertainty bud-
get for
d
220
(
W4
.
2a
) provided by Fujimoto
et al.
(2006).
Although the 2007 result for
d
220
(
MO
∗
) of Becker
et al.
(2007) in Eq. (300) agrees with the 1994 INRIM result of
Basile
et al.
(1994), which was used as an input datum
in the 1998 adjustment, because of the many advances
incorporated in the new work, we no longer consider the
old result.
In addition to the determination, described in the
previous section, of the
{
220
}
lattice spacing of crys-
tal NRLM3 carried out at NMIJ in 2002-2003 using the
NMIJ NRLM3 x-ray interferometer and associated NMIJ
apparatus, Cavagnero
et al.
(2004a,b) reported the re-
sults of measurements carried out at INRIM of the
{
220
}
lattice spacings of crystals MO
∗
and NRLM3, where in
the latter case it was an INRIM-NMIJ joint effort that
used the NIMJ NRLM3 x-ray interferometer but the IN-
RIM associated apparatus. But as indicated above, both
results were subsequently found to be in error: the opti-
cal laser beam used to measure the displacement of the
x-ray interferometer’s analyzer crystal was contaminated
by a parasitic component with a frequency that differed
by about 1.1 GHz from the frequency assigned the laser
beam.
After eliminating the error by replacing the prob-
lem laser with a 633 nm He-Ne external-cavity diode
laser locked to a
127
I
2
stabilized laser, the INRIM re-
searchers repeated the measurements they had previously
carried out with the INRIM MO
∗
x-ray interferometer
and with the refurbished PTB WASO 4.2a x-ray inter-
ferometer originally used in the PTB experiment that led
to the 1981 value of
d
220
(
W4
.
2a
) in Eq. (297). The PTB
WASO 4.2a x-ray interferometer was refurbished at PTB
through remachining, but the result for
d
220
(
W4
.
2a
) ob-
tained at INRIM with the contaminated laser was not
included in Cavagnero
et al.
(2004a,b). The values of
d
220
(
W4
.
2a
) and
d
220
(
MO
∗
) in Eqs. 299 and 300 resulted
from the repeated measurements (Becker
et al.
, 2007).
In principle, based on the experimentally observed
shifts in the measured values of
d
220
(
W4
.
2a
) and
d
220
(
MO
∗
)
obtained with the malfunctioning laser and the properly
functioning laser, the value of
d
220
(
NR3
) obtained in the
INRIM-NMIJ joint effort using the malfunctioning laser
mentioned above, and the value of
d
220
(
WS5C
) also ob-
tained with this laser, could be corrected and taken as
input data. WS5C is an XROI manufactured by INRIM
from a WASO 04 sample, but the value of
d
220
(
WS5C
)
obtained using the contaminated laser was also not in-
cluded in Cavagnero
et al.
(2004a,b). However, because
of the somewhat erratic history of silicon lattice spacing
measurements, the Task Group decided to use only data
obtained with a laser known to be functioning properly.
The improvements in the INRIM XROI apparatus
since the 1994
d
220
(
MO
∗
) measurement of Basile
et al.
(1994) include (i) a new two-axis “tip-tilt†platform for
the XROI that is electronically controlled to compensate
for parasitic rotations and straightness error of the guid-
ing system that moves the platform; (ii) imaging the x-
ray interference pattern formed by the x-ray beam trans-
mitted through the moving analyzer in such a way that
detailed information concerning lattice distortion and an-
alyzer pitch can be extracted on line from the analysis
of the phases of the x-ray fringes; and (iii) an upgraded
computer-aided system for combined interferometer dis-
placement and control, x-ray and optical fringe scanning,
signal digitization and sampling, environmental monitor-
ing, and data analysis.
The values of
d
220
(
W4
.
2a
) and
d
220
(
MO
∗
) in Eqs. (299)
and (300) are the means of tens of individual values, with
each value being the average of about ten data points
collected in 1 h measurement cycles during which the
analyzer was translated back and forth by 300 optical
orders. For the two crystals, respectively, the statisti-
cal uncertainties in parts in 10
9
are 3.5 and 11.6, and
the various corrections and their uncertainties are laser
beam wavelength,
−
0
.
8(4),
−
0
.
8(4); laser beam diffrac-
tion, 12.0(2.2), 12.0(2.2); laser beam alignment, 2.5(3.5),
2.5(3.5); Abbe error, 0.0(2.8), 0.0(3.7); trajectory er-
ror, 0.0(1.4), 0.0(3.6); analyzer temperature, 1.0(5.2),
1.0(7.9); and abberations, 0.0(5.0), 0.0(2.0). The total
uncertainties are 9.6 and 15.7.
2.
d
220
difference measurements
To relate the lattice spacings of crystals used in various
experiments, highly accurate measurements are made of
the fractional difference [
d
220
(
X
)
−
d
220
(ref)]
/d
220
(ref) of
the
{
220
}
lattice spacing of a sample of a single crystal
ingot
X
and that of a reference crystal “refâ€. Both NIST
and PTB have carried out such measurements, and the
fractional differences from these two laboratories that we
take as input data in the 2006 adjustment are given in
the following two sections and are summarized in Ta-
ble XXV. For details concerning these measurements,
see CODATA-98 and CODATA-02.
50
a. NIST difference measurements
The following fractional
difference involving a crystal denoted simply as “N†was
obtained as part of the NIST effort to measure the wave-
lengths in meters of the K
α
1
x-ray lines of Cu, Mo, and
W; see Sec. XI.A.
d
220
(
W17
)
−
d
220
(
N
)
d
220
(
W17
)
= 7(22)
×
10
−
9
.
(301)
The following three fractional differences involving
crystals from the four crystals denoted ILL, WASO 17,
MO*, and NRLM3 were obtained as part of the NIST
effort, discussed in Sec. VIII.C, to determine the relative
atomic mass of the neutron
A
r
(n) (Kessler
et al.
, 1999):
d
220
(
ILL
)
−
d
220
(
W17
)
d
220
(
ILL
)
=
−
8(22)
×
10
−
9
(302)
d
220
(
ILL
)
−
d
220
(
MO
∗
)
d
220
(
ILL
)
= 86(27)
×
10
−
9
(303)
d
220
(
ILL
)
−
d
220
(
NR3
)
d
220
(
ILL
)
= 34(22)
×
10
−
9
.
(304)
The following more recent NIST difference measure-
ments, which we also take as input data in the 2006 ad-
justment, were provided by Kessler (2006) of NIST and
are updates of the results reported by Hanke and Kessler
(2005):
d
220
(
NR3
)
−
d
220
(
W04
)
d
220
(
W04
)
=
−
11(21)
×
10
−
9
(305)
d
220
(
NR4
)
−
d
220
(
W04
)
d
220
(
W04
)
= 25(21)
×
10
−
9
(306)
d
220
(
W17
)
−
d
220
(
W04
)
d
220
(
W04
)
= 11(21)
×
10
−
9
.
(307)
The full designations of the two new crystals involved
in these comparisons are WASO 04 and NRLM4. The
measurements beneï¬ted signiï¬cantly from the relocation
of the NIST lattice comparator to a new laboratory where
the temperature varied by only about 5 mK in several
weeks compared to the previous laboratory where the
temperature varied by about 40 mK in one day (Hanke
and Kessler, 2005).
b. PTB difference measurements
Results for the
{
220
}
lattice-spacing fractional differences of various crystals
that we also take as input data in the 2006 adjustment
have been obtained at the PTB (Martin
et al.
, 1998):
d
220
(
W4
.
2a
)
−
d
220
(
W04
)
d
220
(
W04
)
=
−
1(21)
×
10
−
9
(308)
d
220
(
W17
)
−
d
220
(
W04
)
d
220
(
W04
)
= 22(22)
×
10
−
9
(309)
d
220
(
MO
∗
)
−
d
220
(
W04
)
d
220
(
W04
)
=
−
103(28)
×
10
−
9
(310)
d
220
(
NR3
)
−
d
220
(
W04
)
d
220
(
W04
)
=
−
23(21)
×
10
−
9
.
(311)
To relate
d
220
(
W04
) to the
{
220
}
lattice spacing
d
220
of
an “ideal†silicon crystal, we take as an input datum
d
220
−
d
220
(
W04
)
d
220
(
W04
)
= 10(11)
×
10
−
9
(312)
given by Becker
et al.
(2003), who obtained it by tak-
ing into account the known carbon, oxygen, and nitro-
gen impurities in WASO 04. However, following what
was done in the 1998 and 2002 adjustments, we have in-
cluded an additional component of uncertainty of 1
×
10
−
8
to account for the possibility that, even after correction
for C, O, and N impurities, the crystal WASO 04, al-
though very well characterized as to its purity and crys-
tallographic perfection, does not meet all of the criteria
for an ideal crystal. Indeed, in general, we prefer to use
experimentally measured fractional lattice spacing differ-
ences rather than differences implied by the C, O, and N
impurity content of the crystals in order to avoid the need
to assume that all crystals of interest meet these criteria.
In order to include this fractional difference in the 2002
adjustment, the quantity
d
220
is also taken as an adjusted
constant.
B. Molar volume of silicon
V
m
(Si)
and the Avogadro
constant
N
A
The deï¬nition of the molar volume of silicon
V
m
(Si)
and its relationship to the Avogadro constant
N
A
and
Planck constant
h
as well as other constants is discussed
in CODATA-98 and summarized in CODATA-02.
In
brief we have
m
(Si) =
Ï
(Si)
a
3
n
,
(313)
V
m
(Si) =
M
(Si)
Ï
(Si)
=
A
r
(Si)
M
u
Ï
(Si)
,
(314)
N
A
=
V
m
(Si)
a
3
/n
=
A
r
(Si)
M
u
√
8
d
3
220
Ï
(Si)
,
(315)
V
m
(Si) =
√
2
cM
u
A
r
(e)
α
2
d
3
220
R
∞
h
,
(316)
which are to be understood in the context of an impurity
free, crystallographically perfect, “ideal†silicon crystal
at the reference conditions
t
90
= 22
.
5
â—¦
C and
p
= 0, and
of isotopic composition in the range normally observed
for crystals used in high-accuracy experiments. Thus
m
(Si),
V
m
(Si),
M
(Si), and
A
r
(Si) are the mean mass,
mean molar volume, mean molar mass, and mean rela-
tive atomic mass of the silicon atoms in such a crystal,
respectively, and
Ï
(Si) is the crystal’s macroscopic mass
density. Equation (316) is the observational equation for
a measured value of
V
m
(Si).
It follows from Eq. (314) that the experimen-
tal determination of
V
m
(Si) requires (i) measurement
of the amount-of-substance ratios
n
(
29
Si)/
n
(
28
Si) and
n
(
30
Si)/
n
(
28
Si) of a nearly perfect silicon crystal—and
51
TABLE XXV Summary of measurements of the relative
{
220
}
lattice spacings of silicon crystals.
Quantity
Value
Identiï¬cation
Sect. and Eq.
1
−
d
220
(
W17
)
/d
220
(
ILL
)
−
8(22)
×
10
−
9
NIST-99
VIII.A.2.a (302)
1
−
d
220
(
MO
∗
)
/d
220
(
ILL
)
86(27)
×
10
−
9
NIST-99
VIII.A.2.a (303)
1
−
d
220
(
NR3
)
/d
220
(
ILL
)
34(22)
×
10
−
9
NIST-99
VIII.A.2.a (304)
1
−
d
220
(
N
)
/d
220
(
W17
)
7(22)
×
10
−
9
NIST-97
VIII.A.2.a (301)
d
220
(
NR3
)
/d
220
(
W04
)
−
1
−
11(21)
×
10
−
9
NIST-06
VIII.A.2.a (305)
d
220
(
NR4
)
/d
220
(
W04
)
−
1
25(21)
×
10
−
9
NIST-06
VIII.A.2.a (306)
d
220
(
W17
)
/d
220
(
W04
)
−
1
11(21)
×
10
−
9
NIST-06
VIII.A.2.a (307)
d
220
(
W4
.
2a
)
/d
220
(
W04
)
−
1
−
1(21)
×
10
−
9
PTB-98
VIII.A.2.b (308)
d
220
(
W17
)
/d
220
(
W04
)
−
1
22(22)
×
10
−
9
PTB-98
VIII.A.2.b (309)
d
220
(
MO
∗
)
/d
220
(
W04
)
−
1
−
103(28)
×
10
−
9
PTB-98
VIII.A.2.b (310)
d
220
(
NR3
)
/d
220
(
W04
)
−
1
−
23(21)
×
10
−
9
PTB-98
VIII.A.2.b (311)
d
220
/d
220
(
W04
)
−
1
10(11)
×
10
−
9
PTB-03
VIII.A.2.b (312)
hence amount of substance fractions
x
(
A
Si)—and then
calculation of
A
r
(Si) from the well-known values of
A
r
(
A
Si); and (ii) measurement of the macroscopic mass
density
Ï
(Si) of the crystal.
Determining
N
A
from
Eq. (315) by measuring
V
m
(Si) in this way and
d
220
using x rays is called the x-ray-crystal-density (XRCD)
method.
An extensive international effort has been under way
since the early 1990s to determine
N
A
using this tech-
nique with the smallest possible uncertainty. The effort
is being coordinated by the Working Group on the Avo-
gadro Constant (WGAC) of the Consultative Committee
for Mass and Related Quantities (CCM) of the CIPM.
The WGAC, which has representatives from all major
research groups working in areas relevant to the determi-
nation of
N
A
, is currently chaired by P. Becker of PTB.
As discussed at length in CODATA-02, the value of
V
m
(Si) used as an input datum in the 2002 adjustment
was provided to the CODATA Task Group by the WGAC
and was a consensus value based on independent mea-
surements of
Ï
(Si) at NMIJ and PTB using a number
of different silicon crystals, and measurements of their
molar masses
M
(Si) using isotopic mass spectrometry
at the Institute for Reference Materials and Measure-
ments (IRMM), European Commission, Geel, Belgium.
This value, identiï¬ed as N/P/I-03 in recognition of the
work done by researchers at NMIJ, PTB, and IRMM, is
V
m
(Si) = 12
.
058 8257(36)
×
10
−
6
m
3
mol
−
1
[3
.
0
×
10
−
7
].
Since then, the data used to obtain it were reanalyzed by
the WGAC, resulting in the slightly revised value (Fujii
et al.
, 2005)
V
m
(Si) = 12
.
058 8254(34)
×
10
−
6
m
3
mol
−
1
[2
.
8
×
10
−
7
]
,
(317)
which we take as an input datum in the 2006 adjustment
and identify as N/P/I-05. The slight shift in value and
reduction in uncertainty is due to the fact that the ef-
fect of nitrogen impurities in the silicon crystals used in
the NMIJ measurements was taken into account in the
reanalysis (Fujii
et al.
, 2005). Note that the new value of
A
r
(
29
Si) in Table IV has no effect on this result.
Based on Eq. (316) and the 2006 recommended values
of
A
r
(e),
α
,
d
220
, and
R
∞
, the value of
h
implied by this
result is
h
= 6
.
626 0745(19)
×
10
−
34
J s
[2
.
9
×
10
−
7
]
.
(318)
A comparison of this value of
h
with those in Tables XXI
and XXIII shows that it is generally not in good agree-
ment with the most accurate of the other values.
In this regard, two relatively recent publications, the
ï¬rst describing work performed in China (Ding
et al.
,
2005) and the second describing work performed in
Switzerland (Reynolds
et al.
, 2006), reported results
which, if taken at face value, seem to call into question
the uncertainty with which the molar mass of naturally
occurring silicon is currently known. [See also Valkiers
et al.
(2005).] These results highlight the importance
of the current WGAC project to measure
V
m
(Si) using
highly enriched silicon crystals with
x
(
28
Si)
>
0
.
99985
(Becker
et al.
, 2006), which should simplify the determi-
nation of the molar mass of such crystals.
C. Gamma-ray determination of the neutron relative
atomic mass
A
r
(n)
Although the value of
A
r
(n) listed in Table II is a re-
sult of AME2003, it is not used in the 2006 adjustment.
Instead,
A
r
(n) is obtained as discussed in this section in
order to ensure that its recommended value is consistent
with the best current information on the
{
220
}
lattice
spacing of silicon.
52
The value of
A
r
(n) can be obtained by measuring the
wavelength of the 2.2 MeV
γ
ray in the reaction n + p
→
d +
γ
in terms of the
d
220
lattice spacing of a particular
silicon crystal corrected to the commonly used reference
conditions
t
90
= 22
.
5
â—¦
C and
p
= 0. The result for the
wavelength-to-lattice spacing ratio, obtained from Bragg-
angle measurements carried out in 1995 and 1998 using
a flat crystal spectrometer of the GAMS4 diffraction fa-
cility at the high-flux reactor of the Institut Max von
Laue-Paul Langevin (ILL), Grenoble, France, in a NIST
and ILL collaboration, is (Kessler
et al.
, 1999)
λ
meas
d
220
(
ILL
)
= 0
.
002 904 302 46(50)
[1
.
7
×
10
−
7
]
,
(319)
where
d
220
(
ILL
) is the
{
220
}
lattice spacing of the silicon
crystals of the ILL GAMS4 spectrometer at
t
90
= 22
.
5
â—¦
C
and
p
= 0. Relativistic kinematics of the reaction yields
the equation
λ
meas
d
220
(
ILL
)
=
α
2
A
r
(e)
R
∞
d
220
(
ILL
)
A
r
(n) +
A
r
(p)
[
A
r
(n) +
A
r
(p)]
2
−
A
2
r
(d)
,
(320)
where all seven quantities on the right-hand side are ad-
justed constants.
Recently, Dewey
et al.
(2006); Rainville
et al.
(2005) re-
ported determinations of the wavelengths of the gamma
rays emitted in the cascade from the neutron capture
state to the ground state in the reactions n +
28
Si
→
29
Si
+ 2
γ
, n +
32
S
→
33
Si + 3
γ
, and n +
35
Cl
→
36
Cl + 2
γ
.
The gamma-ray energies are 3.5 MeV and 4.9 MeV for
the Si reaction, 5.4 MeV, 2.4 MeV, and 0.8 MeV for the S
reaction, and 6.1 MeV, 0.5 MeV, and 2.0 MeV for the Cl
reaction. While these data together with the relevant rel-
ative atomic masses are potentially an additional source
of information on the neutron relative atomic mass, the
uncertainties are too large for this purpose; the inferred
value of
A
r
(n) has an uncertainty nearly an order of mag-
nitude larger than that obtained from Eq. (320). Instead,
this work is viewed as the most accurate test of
E
=
mc
2
to date (Rainville
et al.
, 2005).
D. Quotient of Planck constant and particle mass
h/m
(
X
)
and
α
The relation
R
∞
=
α
2
m
e
c/
2
h
leads to
α
=
2
R
∞
c
A
r
(
X
)
A
r
(e)
h
m
(
X
)
1
/
2
,
(321)
where
A
r
(
X
) is the relative atomic mass of particle
X
with mass
m
(
X
) and
A
r
(e) is the relative atomic mass of
the electron. Because
c
is exactly known,
u
r
of
R
∞
and
A
r
(e) are less than 7
×
10
−
12
and 5
×
10
−
10
, respectively,
and
u
r
of
A
r
(
X
) for many particles and atoms is less
than that of
A
r
(e), Eq. (321) can provide a value of
α
with a competitive uncertainty if
h/m
(
X
) is determined
with a sufficiently small uncertainty. Here, we discuss the
determination of
h/m
(
X
) for the neutron n, the
133
Cs
atom, and the
87
Rb atom. The results, including the
inferred values of
α
, are summarized in Table XXVI.
1. Quotient
h/m
n
The PTB determination of
h/m
n
was carried out at
the ILL high-flux reactor. The de Broglie relation
p
=
m
n
v
=
h/λ
was used to determine
h/m
n
=
λv
for the
neutron by measuring both its de Broglie wavelength
λ
and corresponding velocity
v
. More speciï¬cally, the de
Broglie wavelength,
λ
≈
0
.
25 nm, of slow neutrons was
determined using back reflection from a silicon crystal,
and the velocity,
v
≈
1600 m/s, of the neutrons was
determined by a special time-of-flight method. The ï¬nal
result of the experiment is (Kr¨
uger
et al.
, 1999)
h
m
n
d
220
(
W04
)
= 2060
.
267 004(84) m s
−
1
[4
.
1
×
10
−
8
]
,
(322)
where as before,
d
220
(
W04
) is the
{
220
}
lattice spacing
of the crystal WASO 04 at
t
90
= 22
.
5
â—¦
C in vacuum.
This result is correlated with the PTB fractional lattice-
spacing differences given in Eqs. (308) to (311)—the cor-
relation coefficients are about 0.2.
The equation for the PTB result, which follows from
Eq. (321), is
h
m
n
d
220
(
W04
)
=
A
r
(e)
A
r
(n)
cα
2
2
R
∞
d
220
(
W04
)
.
(323)
The value of
α
that can be inferred from this relation
and the PTB value of
h/m
n
d
220
(
W04
), the 2006 recom-
mended values of
R
∞
,
A
r
(e), and
A
r
(n), the NIST and
PTB fractional lattice-spacing-differences in Table XXV,
and the four XROI values of
d
220
(
X
) in Table XXIV for
crystals WASO 4.2a, NRLM3, and MO
∗
, is
α
−
1
= 137
.
036 0077(28) [2
.
1
×
10
−
8
]
.
(324)
This value is included in Table XXVI as the ï¬rst entry;
it disagrees with the
α
values from the two other
h/m
results.
It is also of interest to calculate the value of
d
220
implied by the PTB result for
h/m
n
d
220
(
W04
). Based
on Eq. (323), the 2006 recommended values of
R
∞
,
A
r
(e),
A
r
(p),
A
r
(d),
α
, the NIST and PTB fractional
lattice-spacing-differences in Table XXV, and the value
of
λ
meas
/d
220
(
ILL
) given in Eq. (319), we ï¬nd
d
220
= 192 015
.
5982(79) fm [4
.
1
×
10
−
8
]
.
(325)
This result is included in Table XXIV as the last entry; it
agrees with the NMIJ value, but disagrees with the PTB
and INRIM values.
53
TABLE XXVI Summary of data related to the quotients
h/m
n
d
220
(
W04
),
h/m
(Cs), and
h/m
(Rb), together with inferred values
of
α
.
Quantity
Value
Relative standard
Identiï¬cation
Sect. and Eq.
uncertainty
u
r
h/m
n
d
220
(
W04
)
2060
.
267 004(84) m s
−
1
4
.
1
×
10
−
8
PTB-99
VIII.D.1 (322)
α
−
1
137
.
036 0077(28)
2
.
1
×
10
−
8
VIII.D.1 (324)
h/m
(Cs)
3
.
002 369 432(46)
×
10
−
9
m
2
s
−
1
1
.
5
×
10
−
8
StanfU-02
VIII.D.2 (329)
α
−
1
137
.
036 0000(11)
7
.
7
×
10
−
9
VIII.D.2 (331)
h/m
(Rb)
4
.
591 359 287(61)
×
10
−
9
m
2
s
−
1
1
.
3
×
10
−
8
LKB-06
VIII.D.2 (332)
α
−
1
137
.
035 998 83(91)
6
.
7
×
10
−
9
VIII.D.2 (334)
2. Quotient
h/m
(
133
Cs)
The Stanford University atom interferometry exper-
iment to measure the atomic recoil frequency shift of
photons absorbed and emitted by
133
Cs atoms, ∆
ν
Cs
, in
order to determine the quotient
h/m
(
133
Cs) is described
in CODATA-02. As discussed there, the expression ap-
plicable to the Stanford experiment is
h
m
(
133
Cs)
=
c
2
∆
ν
Cs
2
ν
2
eff
,
(326)
where the frequency
ν
eff
corresponds to the sum of the en-
ergy difference between the ground-state hyperï¬ne level
with
F
= 3 and the 6P
1
/
2
state
F
= 3 hyperï¬ne level and
the energy difference between the ground-state hyperï¬ne
level with
F
= 4 and the same 6P
1
/
2
hyperï¬ne level.
The result for ∆
ν
Cs
/
2 reported in 2002 by the Stanford
researchers is (Wicht
et al.
, 2002)
∆
ν
Cs
2
= 15 006
.
276 88(23) Hz
[1
.
5
×
10
−
8
]
.
(327)
The Stanford effort included an extensive study of cor-
rections due to possible systematic effects. The largest
component of uncertainty by far contributing to the un-
certainty of the ï¬nal result for ∆
ν
Cs
,
u
r
= 14
×
10
−
9
(Type B), arises from the possible deviation from 1 of the
index of refraction of the dilute background gas of cold ce-
sium atoms that move with the signal atoms. This com-
ponent, estimated experimentally, places a lower limit on
the relative uncertainty of the inferred value of
α
from
Eq. (321) of
u
r
= 7
×
10
−
9
. Without it,
u
r
of
α
would be
about 3 to 4 parts in 10
9
.
In
the
2002
adjustment,
the
value
ν
eff
=
670 231 933 044(81) kHz [1
.
2
×
10
−
10
], based on the
measured frequencies of
133
Cs D
1
-line transitions re-
ported by Udem
et al.
(1999), was used to obtain the
ratio
h/m
(
133
Cs) from the Stanford value of ∆
ν
Cs
/
2.
Recently, using a femtosecond laser frequency comb
and a narrow-linewidth diode laser, and eliminating
Doppler shift by orienting the laser beam perpendicular
to the
133
Cs atomic beam to within 5
µ
rad, Gerginov
et al.
(2006) remeasured the frequencies of the required
transitions and obtained a value of
ν
eff
that agrees with
the value used in 2002 but which has a
u
r
15 times
smaller:
ν
eff
= 670 231 932 889
.
9(4
.
8) kHz
[7
.
2
×
10
−
12
]
.
(328)
Evaluation of Eq. (326) with this result for
ν
eff
and the
value of ∆
ν
Cs
/
2 in Eq. (327) yields
h
m
(
133
Cs)
= 3
.
002 369 432(46)
×
10
−
9
m
2
s
−
1
[1
.
5
×
10
−
8
]
,
(329)
which we take as an input datum in the 2006 adjust-
ment. The observational equation for this datum is, from
Eq. (321),
h
m
(
133
Cs)
=
A
r
(e)
A
r
(
133
Cs)
c α
2
2
R
∞
.
(330)
The value of
α
that may be inferred from this expres-
sion, the Stanford result for
h/m
(
133
Cs) in Eq. (329),
the 2006 recommended values of
R
∞
and
A
r
(e), and the
ASME2003 value of
A
r
(
133
Cs) in Table II, the uncertain-
ties of which are inconsequential in this application, is
α
−
1
= 137
.
036 0000(11)
[7
.
7
×
10
−
9
]
,
(331)
where the dominant component of uncertainty arises
from the measured value of the recoil frequency shift, in
particular, the component of uncertainty due to a possi-
ble index of refraction effect.
In this regard, we note that Campbell
et al.
(2005)
have experimentally demonstrated the reality of one as-
pect of such an effect with a two-pulse light grating inter-
ferometer and have shown that it can have a signiï¬cant
impact on precision measurements with atom interferom-
eters. However, theoretical calculations based on simu-
lations of the Stanford interferometer by Sarajlic
et al.
(2006), although incomplete, suggest that the experi-
mentally based uncertainty component
u
r
= 14
×
10
−
9
assigned by Wicht
et al.
(2002) to account for this ef-
fect is reasonable. We also note that Wicht
et al.
(2005)
have developed an improved theory of momentum trans-
fer when localized atoms and localized optical ï¬elds in-
teract. The details of such interactions are relevant to
54
precision atom interferometry. When Wicht
et al.
(2005)
applied the theory to the Stanford experiment to evaluate
possible systematic errors arising from wave-front curva-
ture and distortion, as well as the Gouy phase shift of
gaussian beams, they found that such errors do not limit
the uncertainty of the value of
α
that can be obtained
from the experiment at the level of a few parts in 10
9
,
but will play an important role in future precision atom-
interferometer photon-recoil experiments to measure
α
with
u
r
≈
5
×
10
−
10
, such as is currently underway at
Stanford (M¨
uller
et al.
, 2006).
3. Quotient
h/m
(
87
Rb)
In the LKB experiment (Clad´e
et al.
, 2006a,b), the
quotient
h/m
(
87
Rb), and hence
α
, is determined by ac-
curately measuring the rubidium recoil velocity
v
r
=
¯
hk/m
(
87
Rb) when a rubidium atom absorbs or emits a
photon of wave vector
k
= 2
Ï€
/λ
, where
λ
is the wave-
length of the photon and
ν
=
c/λ
is its frequency. The
measurements are based on Bloch oscillations in a verti-
cal accelerated optical lattice.
The basic principle of the experiment is to precisely
measure the variation of the atomic velocity induced by
an accelerated standing wave using velocity selective Ra-
man transitions between two ground-state hyperï¬ne lev-
els. A Raman
Ï€
pulse of two counter-propagating laser
beams selects an initial narrow atomic velocity class. Af-
ter the acceleration process, the ï¬nal atomic velocity dis-
tribution is probed using a second Raman
Ï€
pulse of two
counter-propagating laser beams.
The coherent acceleration of the rubidium atoms arises
from a succession of stimulated two photon transitions
also using two counter-propagating laser beams. Each
transition modiï¬es the atomic velocity by 2
v
r
leaving the
internal state unchanged. The Doppler shift is compen-
sated by linearly sweeping the frequency difference of the
two lasers. This acceleration can conveniently be inter-
preted in terms of Bloch oscillations in the fundamental
energy band of an optical lattice created by the stand-
ing wave, because the interference of the two laser beams
leads to a periodic light shift of the atomic energy levels
and hence to the atoms experiencing a periodic potential
(Ben Dahan
et al.
, 1996; Peik
et al.
, 1997).
An atom’s momentum evolves by steps of 2¯
hk
, each
one corresponding to a Bloch oscillation. After
N
oscilla-
tions, the optical lattice is adiabatically released and the
ï¬nal velocity distribution, which is the initial distribution
shifted by 2
N v
r
, is measured. Due to the high efficiency
of Bloch oscillations, for an acceleration of 2000 m s
−
2
,
900 recoil momenta can be transferred to a rubidium
atom in 3 ms with an efficiency of 99.97 % per recoil.
The atoms are alternately accelerated upwards and
downwards by reversing the direction of the Bloch ac-
celeration laser beams, keeping the same delay between
the selection and the measurement Raman
Ï€
pulses. The
resulting differential measurement is independent of grav-
ity. In addition, the contribution of some systematic
effects changes sign when the direction of the selection
and measuring Raman beams is exchanged. Hence, for
each up and down trajectory, the selection and measur-
ing Raman beams are reversed and two velocity spectra
are taken. The mean value of these two measurements is
free from systematic errors to ï¬rst order. Thus each de-
termination of
h/m
(
87
Rb) is obtained from four velocity
spectra, each requiring 5 minutes of integration time, two
from reversing the Raman beams when the acceleration
is in the up direction and two when in the down direction.
The Raman and Bloch lasers are stabilized by means of
an ultrastable Fabry-P´erot cavity and the frequency of
the cavity is checked several times during the 20 minute
measurement against a well-known two-photon transition
in
85
Rb.
Taking into account a (
−
9
.
2
±
4)
×
10
−
10
correction to
h/m
(
87
Rb) not included in the value reported by Clad´e
et al.
(2006a) due to a nonzero force gradient arising from
a difference in the radius of curvature of the up and down
accelerating beams, the result derived from 72 measure-
ments of
h/m
(
87
Rb) acquired over 4 days, which we take
as an input datum in the 2006 adjustment, is (Clad´e
et al.
, 2006b)
h
m
(
87
Rb)
= 4
.
591 359 287(61)
×
10
−
9
m
2
s
−
1
[1
.
3
×
10
−
8
]
,
(332)
where the quoted
u
r
contains a statistical component
from the 72 measurements of 8
.
8
×
10
−
9
.
Clad´e
et al.
(2006b) examined many possible sources of
systematic error, both theoretically and experimentally,
in this rather complex, sophisticated experiment in order
to ensure that their result was correct. These include
light shifts, index of refraction effects, and the effect of a
gravity gradient, for which the corrections and their un-
certainties are in fact comparatively small. More signiï¬-
cant are the fractional corrections of (16
.
8
±
8)
×
10
−
9
for
wave front curvature and Guoy phase, (
−
13
.
2
±
4)
×
10
−
9
for second order Zeeman effect, and 4(4)
×
10
−
9
for the
alignment of the Raman and Bloch beams. The total of
all corrections is given as 10
.
98(10
.
0)
×
10
−
9
.
From Eq. (321), the observational equation for the
LKB value of
h/m
(
87
Rb) in Eq (332) is
h
m
(
87
Rb)
=
A
r
(e)
A
r
(
87
Rb)
c α
2
2
R
∞
.
(333)
Evaluation of this expression with the LKB result and
the 2006 recommended values of
R
∞
and
A
r
(e), and the
value of
A
r
(
87
Rb) resulting from the ï¬nal least-squares
adjustment on which the 2006 recommended values are
based, all of whose uncertainties are negligible in this
context, yields
α
−
1
= 137
.
035 998 83(91)
[6
.
7
×
10
−
9
]
,
(334)
which is included in Table XXVI. The uncertainty of
this value of
α
−
1
is smaller than the uncertainty of any
55
other value except those in Table XIV deduced from the
measurement of
a
e
, exceeding the smallest uncertainty of
the two values of
α
−
1
[
a
e
] in that table by a factor of ten.
IX. THERMAL PHYSICAL QUANTITIES
The following sections discuss the molar gas constant,
Boltzmann constant, and Stefan-Boltzmann constant—
constants associated with phenomena in the ï¬elds of ther-
modynamics and/or statistical mechanics.
A. Molar gas constant
R
The square of the speed of sound
c
2
a
(
p, T
) of a real gas
at pressure
p
and thermodynamic temperature
T
can be
written as (Colclough, 1973)
c
2
a
(
p, T
) =
A
0
(
T
) +
A
1
(
T
)
p
+
A
2
(
T
)
p
2
+
A
3
(
T
)
p
3
+
· · ·
,
(335)
where
A
1
(
T
) is the ï¬rst acoustic virial coefficient,
A
2
(
T
)
is the second,
etc.
In the limit
p
→
0, Eq. (335) yields
c
2
a
(0
, T
) =
A
0
(
T
) =
γ
0
R T
A
r
(
X
)
M
u
,
(336)
where the expression on the right-hand side is the square
of the speed of sound for an unbounded ideal gas, and
where
γ
0
=
c
p
/c
V
is the ratio of the speciï¬c heat capac-
ity of the gas at constant pressure to that at constant
volume,
A
r
(
X
) is the relative atomic mass of the atoms
or molecules of the gas, and
M
u
= 10
−
3
kg mol
−
1
. For a
monatomic ideal gas,
γ
0
= 5
/
3.
The 2006 recommended value of
R
, like the 2002 and
1998 values, is based on measurements of the speed of
sound in argon carried out in two independent exper-
iments, one done in the 1970s at NPL and the other
done in the 1980s at NIST. Values of
c
2
a
(
p, T
TPW
), where
T
TPW
= 273
.
16 K is the triple point of water, were ob-
tained at various pressures and extrapolated to
p
= 0 in
order to determine
A
0
(
T
TPW
) =
c
2
a
(0
, T
TPW
), and hence
R
, from the relation
R
=
c
2
a
(0
, T
TPW
)
A
r
(Ar)
M
u
γ
0
T
TPW
,
(337)
which follows from Eq. (336).
Because the work of both NIST and NPL is reviewed in
CODATA-98 and CODATA-02 and nothing has occurred
in the last 4 years that would change the values of
R
implied by their reported values of
c
2
a
(0
, T
TPW
), we give
only a brief summary here. Changes in these values due
to the new values of
A
r
(
A
Ar) resulting from the 2003
atomic mass evaluation as given in Table II, or the new
IUPAC compilation of atomic weights of the elements
given by Wieser (2006), are negligible.
Since
R
cannot be expressed as a function of any other
of the 2006 adjusted constants,
R
itself is taken as an
adjusted constant for the NIST and NPL measurements.
1. NIST: speed of sound in argon
In the NIST experiment of Moldover
et al.
(1988), a
spherical acoustic resonator at a temperature
T
=
T
TPW
ï¬lled with argon was used to determine
c
2
a
(
p, T
TPW
). The
ï¬nal NIST result for the molar gas constant is
R
= 8
.
314 471(15) J mol
−
1
K
−
1
[1
.
8
×
10
−
6
]
.
(338)
The mercury employed to determine the volume of the
spherical resonator was traceable to the mercury whose
density was measured by Cook (1961) [see also Cook and
Stone (1957)]. The mercury employed in the NMI Hg
electrometer determination of
K
J
(see VII.C.1) was also
traceable to the same mercury. Consequently, the NIST
value of
R
and the NMI value of
K
J
are correlated with
the non-negligible correlation coefficient 0.068.
2. NPL: speed of sound in argon
In contrast to the dimensionally ï¬xed resonator used in
the NIST experiment, the NPL experiment employed a
variable path length ï¬xed-frequency cylindrical acoustic
interferometer to measure
c
2
a
(
p, T
TPW
). The ï¬nal NPL
result for the molar gas constant is (Colclough
et al.
,
1979)
R
= 8
.
314 504(70) J mol
−
1
K
−
1
[8
.
4
×
10
−
6
]
.
(339)
Although both the NIST and NPL values of
R
are
based on the same values of
A
r
(
40
Ar),
A
r
(
38
Ar), and
A
r
(
36
Ar), the uncertainties of these relative atomic
masses are sufficiently small that the covariance of the
two values of
R
is negligible.
3. Other values
The most important of the historical values of
R
have
been reviewed by Colclough (1984) [see also (Quinn
et al.
,
1976) and CODATA-98]. However, because of the large
uncertainties of these early values, they were not consid-
ered for use in either the 1986, 1998, or 2002 CODATA
adjustments, and we do not consider them for the 2006
adjustment as well.
Also because of its non-competitive uncertainty (
u
r
=
36
×
10
−
6
), we exclude from consideration in the 2006
adjustment, as in the 2002 adjustment, the value of
R
obtained from measurements of the speed of sound in
argon reported by He and Liu (2002) at the Xi´an Jiaotong
University, Xi´
an, China (People’s Republic of).
B. Boltzmann constant
k
The Boltzmann constant is related to the molar gas
constant
R
and other adjusted constants by
k
=
2
R
∞
h
cA
r
(e)
M
u
α
2
R
=
R
N
A
.
(340)
56
No competitive directly measured value of
k
was avail-
able for the 1998 or 2002 adjustments, and the situation
remains unchanged for the present adjustment. Thus,
the 2006 recommended value with
u
r
= 1
.
7
×
10
−
6
is
obtained from this relation, as were the 1998 and 2002
recommended values. However, a number of experiments
are currently underway that might lead to competitive
values of
k
(or
R
) in the future; see Fellmuth
et al.
(2006)
for a recent review.
Indeed, one such experiment underway at the PTB
based on dielectric constant gas thermometry (DCGT)
was discussed in both CODATA-98 and CODATA-02,
but no experimental result for
A
Ç«
/R
, where
A
Ç«
is the
molar polarizability of the
4
He atom, other than that
considered in these two reports, has been published by
the PTB group [see also Fellmuth
et al.
(2006) and Luther
et al.
(1996)]. However, the relative uncertainty of the
theoretical value of the static electric dipole polarizability
of the ground state of the
4
He atom, which is required to
calculate
k
from
A
Ç«
/R
, has been lowered by more than
a factor of ten to below 2
×
10
−
7
( Lach
et al.
, 2004).
Nevertheless, the change in its value is negligible at the
level of uncertainty of the PTB result for
A
Ç«
/R
; hence,
the value
k
= 1
.
380 65(4)
×
10
−
23
J K
−
1
[30
×
10
−
6
] from
the PTB experiment given in CODATA-02 is unchanged.
In addition, preliminary results from two other ongo-
ing experiments, the ï¬rst being carried out at NIST by
Schmidt
et al.
(2007) and the second at the University
of Paris by Daussy
et al.
(2007), have recently been pub-
lished.
Schmidt
et al.
(2007) report
R
= 8
.
314 487(76) J mol
K
−
1
[9
.
1
×
10
−
6
], obtained from measurements of the in-
dex of refraction
n
(
p, T
) of
4
He gas as a function of
p
and
T
by measuring the difference in the resonant fre-
quencies of a quasispherical microwave resonator when
ï¬lled with
4
He at a given pressure and when evacuated
(that is, at
p
= 0). This experiment has some similari-
ties to the PTB DCGT experiment in that it determines
the quantity
A
Ç«
/R
and hence
k
. However, in DCGT
one measures the difference in capacitance of a capacitor
when ï¬lled with
4
He at a given pressure and at
p
= 0,
and hence one determines the dielectric constant of the
4
He gas rather than its index of refraction. Because
4
He
is slightly diamagnetic, this means that to obtain
A
Ç«
/R
in the NIST experiment, a value for
A
µ
/R
is required,
where
A
µ
= 4
Ï€
χ
0
/
3 and
χ
0
is the diamagnetic suscepti-
bility of a
4
He atom.
Daussy
et al.
(2007) report
k
= 1
.
380 65(26)
×
10
−
23
J
K
−
1
[190
×
10
−
6
], obtained from measurements as a func-
tion of pressure of the Doppler proï¬le at
T
= 273
.
15 K
(the ice point) of a well-isolated rovibrational line in the
ν
2
band of the ammonium molecule,
14
NH
3
, and extrap-
olation to
p
= 0. The experiment actually measures
R
=
kN
A
, because the mass of the ammonium molecule
in kilograms is required but can only be obtained with
the requisite accuracy from the molar masses of
14
N and
1
H, thereby introducing
N
A
.
It is encouraging that the preliminary values of
k
and
G/
(10
−
11
m
3
kg
−
1
s
−
2
)
6.670
6.672
6.674
6.676
6.678
6.670
6.672
6.674
6.676
6.678
10
−
4
G
UWup-02
HUST-05
LANL-97
TR&D-96
BIPM-01
MSL-03
UZur-06
UWash-00
CODATA-02
CODATA-06
FIG. 2 Values of the Newtonian constant of gravitation
G
.
R
resulting from these three experiments are consistent
with the 2006 recommended values.
C. Stefan-Boltzmann constant
σ
The Stefan-Boltzmann constant is related to
c
,
h
, and
the Boltzmann constant
k
by
σ
=
2
Ï€
5
k
4
15
h
3
c
2
,
(341)
which, with the aid of Eq. (340), can be expressed in
terms of the molar gas constant and other adjusted con-
stants as
σ
=
32
Ï€
5
h
15
c
6
R
∞
R
A
r
(e)
M
u
α
2
4
.
(342)
No competitive directly measured value of
σ
was avail-
able for the 1998 or 2002 adjustments, and the situa-
tion remains unchanged for the 2006 adjustment. Thus,
the 2006 recommended value with
u
r
= 7
.
0
×
10
−
6
is
obtained from this relation, as were the 1998 and 2002
recommended values. For a concise summary of exper-
iments that might provide a competiive value of
σ
, see
the review by Fellmuth
et al.
(2006).
X. NEWTONIAN CONSTANT OF GRAVITATION
G
Because there is no known quantitative theoretical re-
lationship between the Newtonian constant of gravitation
G
and other fundamental constants, and because the cur-
rently available experimental values of
G
are independent
of all of the other data relevant to the 2006 adjustment,
57
TABLE XXVII Summary of the results of measurements of the Newtonian constant of gravitation relevant to the 2006
adjustment together with the 2002 and 2006 CODATA recommended values.
Item Source
Identiï¬cation
a
Method
10
11
G
Rel. stand.
m
3
kg
−
1
s
−
2
uncert
u
r
2002 CODATA Adjustment
CODATA-02
6
.
6742(10)
1
.
5
×
10
−
4
a.
(Karagioz and Izmailov, 1996)
TR&D-96
Fiber torsion balance,
6
.
672 9(5)
7
.
5
×
10
−
5
dynamic mode
b.
(Bagley and Luther, 1997)
LANL-97
Fiber torsion balance,
6
.
674 0(7)
1
.
0
×
10
−
4
dynamic mode
c.
(Gundlach and Merkowitz, 2000, 2002) UWash-00
Fiber torsion balance,
6
.
674 255(92) 1
.
4
×
10
−
5
dynamic compensation
d.
(Quinn
et al.
, 2001)
BIPM-01
Strip torsion balance,
6
.
675 59(27) 4
.
0
×
10
−
5
compensation mode, static deflection
e.
(Kleinevoß, 2002; Kleinvoß
et al.
, 2002) UWup-02
Suspended body,
6
.
674 22(98) 1
.
5
×
10
−
4
displacement
f.
(Armstrong and Fitzgerald, 2003)
MSL-03
Strip torsion balance,
6
.
673 87(27) 4
.
0
×
10
−
5
compensation mode
g.
(Hu
et al.
, 2005)
HUST-05
Fiber torsion balance,
6
.
672 3(9)
1
.
3
×
10
−
4
dynamic mode
h.
(Schlamminger
et al.
, 2006)
UZur-06
Stationary body,
6
.
674 25(12) 1
.
9
×
10
−
5
weight change
2006 CODATA Adjustment
CODATA-06
6
.
674 28(67) 1
.
0
×
10
−
4
a
TR&D: Tribotech Research and Development Company, Moscow, Russian Federation; LANL: Los Alamos National Laboratory, Los
Alamos, New Mexico, USA; UWash: University of Washington, Seattle, Washington, USA; BIPM: International Bureau of Weights and
Measures, S`
evres, France; UWup: University of Wuppertal, Wuppertal, Germany; MSL: Measurement Standards Laboratory, Lower Hutt,
New Zealand; HUST: Huazhong University of Science and Technology, Wuhan, PRC; UZur: University of Zurich, Zurich, Switzerland.
these experimental values contribute only to the deter-
mination of the 2006 recommended value of
G
and can
be considered independently from the other data.
The historic difficulty of determining
G
, as demon-
strated by the inconsistencies among different measure-
ments, is described in detail in CODATA-86, CODATA-
98, and CODATA-02. Although no new competitive in-
dependent result for
G
has become available in the last
4 years, adjustments to two existing results considered
in 2002 have been made by researchers involved in the
original work. One of the two results that has changed is
from the Huazhong University of Science and Technology
(HUST) and is now identiï¬ed as HUST-05; the other is
from the University of Zurich (UZur) and is now identi-
ï¬ed as UZur-06. These revised results are discussed in
some detail below.
Table XXVII summarizes the various values of
G
con-
sidered here, which are the same as in 2002 with the ex-
ception of these two revised results, and Fig. 2 compares
them graphically. For reference purposes, both the table
and ï¬gure include the 2002 and 2006 CODATA recom-
mended values. The result now identiï¬ed as TR&D-96
was previously identiï¬ed as TR&D-98. The change is
because a 1996 reference, (Karagioz and Izmailov, 1996),
was found that reports the same result as does the 1998
reference (Karagioz
et al.
, 1998).
For simplicity, in the following text, we write
G
as a
numerical factor multiplying
G
0
, where
G
0
= 10
−
11
m
3
kg
−
1
s
−
2
.
(343)
A. Updated values
1. Huazhong University of Science and Technology
The HUST group, which determines
G
by the time-
of-swing method using a high-
Q
torsion pendulum with
two horizontal, 6.25 kg stainless steel cylindrical source
masses labeled A and B positioned on either side of
the test mass, has reported a fractional correction of
+360
×
10
−
6
to their original result given by Luo
et al.
(1999). It arises in part from recently discovered density
inhomogeneities in the source masses, the result of which
is a displacement of the center of mass of each source
mass from its geometrical center (Hu
et al.
, 2005). Using
a “weighbridge†with a commercial electronic balance—a
method developed by Davis (1995) to locate the center
of mass of a test object with micrometers precision—Hu
et al.
(2005) found that the axial eccentricities
e
A
and
e
B
of the two source masses were (10
.
3
±
2
.
6)
µ
m and
(6
.
3
±
3
.
7)
µ
m, with the result that the equivalent dis-
placements between the test mass and the source masses
are larger than the values used by (Luo
et al.
, 1999). As-
suming a linear axial density distribution, the calculated
58
fractional correction to the previous result is +210
×
10
−
6
with an additional component of relative standard un-
certainty of 78
×
10
−
6
due to the uncertainties of the
eccentricities.
The remaining 150
×
10
−
6
portion of the 360
×
10
−
6
fractional correction is also discussed by Hu
et al.
(2005)
and arises as follows. In the HUST experiment,
G
is
determined by comparing the period of the torsion pen-
dulum with and without the source masses. When the
source masses are removed, they are replaced by air.
Since the masses of the source masses used by Luo
et al.
(1999) are the vacuum masses, a correction for the air,
ï¬rst suggested by R. S. Davis and T. J. Quinn of the
BIPM, is required. This correction was privately com-
municated to the Task Group by the HUST researchers
in 2003 and included in the HUST value of
G
used in the
2002 adjustment.
The HUST revised value of
G
, including the additional
component of uncertainty due to the measurement of the
eccentricities
e
A
and
e
B
, is item
g
in Table XXVII.
2. University of Zurich
The University of Zurich result for
G
discussed in
CODATA-02 and used in the 2002 adjustment,
G
=
6
.
674 07(22)
G
0
[3
.
3
×
10
−
5
], was reported by Schlam-
minger
et al.
(2002). It was based on the weighted mean
of three highly consistent values obtained from three se-
ries of measurements carried out at the Paul Scherrer In-
stitute (PSI), Villigen, Switzerland, in 2001 and 2002 and
denoted Cu, Ta I, and Ta II. The designation Cu means
that the test masses were gold plated copper, and the
designation Ta means that they were tantalum. Follow-
ing the publication of Schlamminger
et al.
(2002), an ex-
tensive reanalysis of the original data was carried out by
these authors together with other University of Zurich re-
searchers, the result being the value of
G
in Table XXVII,
item
h
, as given in the detailed ï¬nal report on the exper-
iment (Schlamminger
et al.
, 2006).
In the University of Zurich approach to determining
G
, a modiï¬ed commercial single-pan balance is used to
measure the change in the difference in weight of two
cylindrical test masses when the relative position of two
source masses is changed. The quantity measured is the
800
µ
g difference signal obtained at many different work-
ing points in the balance calibration range using two sets
of 16 individual wire weights, allowing an
in situ
mea-
surement of the balance non-linearity over the entire 0.2 g
balance calibration interval. A more rigorous analysis us-
ing a ï¬tting method with Legendre polynomials has now
allowed the relative standard uncertainty contribution to
G
from balance nonlinearity to be reduced from 18
×
10
−
6
to 6
.
1
×
10
−
6
based on the Cu test-mass data. Various
problems with the mass handler for the wire weights that
did not allow the application of the Legendre polynomial
ï¬tting procedure occurred during the Ta test-mass mea-
surements, resulting in large systematic errors. There-
fore, the researchers decided to include only the Cu data
in their ï¬nal analysis (Schlamminger
et al.
, 2006).
Each source mass consisted of a cylindrical tank ï¬lled
with 7
.
5
×
10
3
kg of mercury. Since the mercury repre-
sented approximately 94 % of the total mass, special care
was taken in determining its mass and density. These
measurements were further used to obtain more accurate
values for the key tank dimensions and Hg mass. This
was done by minimizing a
χ
2
function that depended
on the tank dimensions and the Hg mass and density,
and using the dependence of the density on these dimen-
sions and the Hg mass as a constraint. Calculation of the
mass integration constant with these improved values re-
duced the
u
r
of this critical quantity from 20
.
6
×
10
−
6
to
6
.
7
×
10
−
6
.
Although the analysis of Schlamminger
et al.
(2002) as-
sumed a linear temporal drift of the balance zero point, a
careful examination by Schlamminger
et al.
(2006) found
that the drift was signiï¬cantly nonlinear and was influ-
enced by the previous load history of the balance. A
series of Legendre polynomials and a sawtooth function,
respectively, were therefore used to describe the slow and
rapid variations of the observed balance zero-point with
time.
The 2002 value of
G
obtained from the Cu data was
6.674 03
G
0
, consistent with the Ta I, and Ta II values of
6.674 09
G
0
and 6.674 10
G
0
(Schlamminger
et al.
, 2002),
whereas the value from the present Cu data analysis is
6
.
674 25(12)
G
0
, with the 3
.
3
×
10
−
5
fractional increase
being due primarily to the application of the nonlinear
zero point drift correction. A minor contributor to the
difference is the inclusion of the very ï¬rst Cu data set that
was omitted in the 2002 analysis due to a large start-up
zero-point drift that is now correctable with the new Leg-
endre polynomial-sawtooth function analysis technique,
and the exclusion of a data set that had a temperature
stabilization system failure that went undetected by the
old data analysis method (Schlamminger, 2007).
B. Determination of 2006 recommended value of
G
The overall agreement of the eight values of
G
in
Table XXVII (items
a
to
h
) has improved somewhat
since the 2002 adjustment, but the situation is still
far from satisfactory.
Their weighted mean is
G
=
6
.
674 275(68)
G
0
with
χ
2
= 38
.
6 for degrees of freedom
ν
=
N
−
M
= 8
−
1 = 7 , Birge ratio
R
B
=
p
χ
2
/ν
= 2
.
35,
and normalized residuals
r
i
of
−
2
.
75,
−
0
.
39,
−
0
.
22, 4
.
87,
−
0
.
56,
−
1
.
50,
−
2
.
19, and
−
0
.
19, respectively (see Ap-
pendix E of CODATA-98). The BIPM-01 value with
r
i
= 4
.
87 is clearly the most problematic. For compari-
son, the 2002 weighted mean was
G
= 6
.
674 232(75)
G
0
with
χ
2
= 57
.
7 for
ν
= 7 and
R
B
= 2
.
87.
If the BIPM value is deleted, the weighted mean
is reduced by 1.3 standard uncertainties to
G
=
6
.
674 187(70)
G
0
, and
χ
2
= 13
.
3,
ν
= 6, and
R
B
= 1
.
49.
In this case, the two remaining data with signiï¬cant nor-
59
malized residuals are the the TR&D-96 and the HUST-05
results with
r
i
=
−
2
.
57 and
−
2
.
10, respectively. If these
two data, which agree with each other, are deleted, the
weighted mean is
G
= 6
.
674 225(71)
G
0
with
χ
2
= 2
.
0,
ν
= 4,
R
B
= 0
.
70, and with all normalized residuals
less than one except
r
i
=
−
1
.
31 for datum MSL-03. Fi-
nally, if the UWash-00 and UZur-06 data, which have the
smallest assigned uncertainties of the initial eight values
and which are in excellent agreement with each other, are
deleted from the initial group of eight data, the weighted
mean of the remaining six data is
G
= 6
.
674 384(167)
G
0
with
χ
2
= 38
.
1,
ν
= 6, and
R
B
= 2
.
76. The normalized
residuals for these six data, TR&D-96, LANL-97, BIPM-
01, UWup-02, MSL-03, and HUST-05, are
−
2
.
97,
−
0
.
55,
4.46,
−
0
.
17,
−
1
.
91 and
−
2
.
32, respectively.
Finally, if the uncertainties of each of the eight values of
G
are multiplied by the Birge ratio associated with their
weighted mean,
R
B
= 2
.
35, so that
χ
2
of their weighted
mean becomes equal to its expected value of
ν
= 7 and
R
B
= 1, the normalized residual of the datum BIPM-01
would still be larger than two.
Based on the results of the above calculations, the his-
torical difficulty of determining
G
, the fact that all eight
values of
G
in Table XXVII are credible, and that the
two results with the smallest uncertainties, UWash-00
and UZur-06, are highly consistent with one another, the
Task Group decided to take as the 2006 CODATA recom-
mended value of
G
the weighted mean of all of the data,
but with an uncertainty of 0.000 67
G
0
, corresponding to
u
r
= 1
.
0
×
10
−
4
:
G
= 6
.
674 28(67)
×
10
−
11
m
3
kg
−
1
s
−
2
.
[1
.
0
×
10
−
4
]
(344)
This value exceeds the 2002 recommended value by the
fractional amount 1
.
2
×
10
−
5
, which is less than one tenth
of the uncertainty
u
r
= 1
.
5
×
10
−
4
of the 2002 value.
Further, the uncertainty of the 2006 value,
u
r
= 1
.
0
×
10
−
4
, is two thirds that of the 2002 value.
In assigning this uncertainty to the 2006 recommended
value of
G
, the Task Group recognized that if the un-
certainty was smaller than really justiï¬ed by the data,
taking into account the history of measurements of
G
, it
might discourage the initiation of new research efforts to
determine
G
, if not the continuation of some of the re-
search efforts already underway. Such efforts need to be
encouraged in order to provide a more solid and redun-
dant data set upon which to base future recommended
values. On the other hand, if the uncertainty was too
large, for example, if the uncertainty of the 2002 recom-
mended value had been retained for the 2006 value, then
the recommended value would not have reflected the fact
that we now have two data that are in excellent agree-
ment, have
u
r
less than 2
×
10
−
5
, and are the two most
accurate values available.
C. Prospective values
New techniques to measure
G
using atom interferom-
etry are currently under development in at least two
laboratories—the Universit`
a de Firenze in Italy and
Stanford University in the United States. This comes
as no surprise since atom interferometry is also being de-
veloped to measure the local acceleration due to gravity
g
(see the last paragraph of Sec. II). Recent proof of
principle experiments combine two vertically separated
atomic clouds forming an atom-interferometer-gravity-
gradiometer that measures the change in the gravity
gradient when a well characterized source mass is dis-
placed. Measuring the change in the gravity gradient
allows the rejection of many possible systematic errors.
Bertoldi
et al.
(2006) at the Universit`
a de Firenze used
a Rb fountain and a fast launch juggling sequence of two
atomic clouds to measure
G
to 1 %, obtaining the value
6
.
64(6)
G
0
; they hope to reach a ï¬nal uncertainty of 1
part in 10
4
. Fixler
et al.
(2007) at Stanford used two
separate Cs atom interferometer gravimeters to measure
G
and obtained the value 6
.
693(34)
G
0
. The two largest
uncertainties from systematic effects were the determi-
nation of the initial atom velocity and the initial atom
position. The Stanford researchers also hope to achieve
a ï¬nal uncertainty of 1 part in 10
4
. Although neither of
these results is signiï¬cant for the current analysis of
G
,
future results could be of considerable interest.
XI. X-RAY AND ELECTROWEAK QUANTITIES
A. X-ray units
Historically, units that have been used to express the
wavelengths of x-ray lines are the copper K
α
1
x unit,
symbol xu(CuK
α
1
), the molybdenum K
α
1
x unit, symbol
xu(MoK
α
1
), and the Ëš
angstrom star, symbol Ëš
A
∗
. They
are deï¬ned by assigning an exact, conventional value to
the wavelength of the CuK
α
1
, MoK
α
1
, and WK
α
1
x-ray
lines when each is expressed in its corresponding unit:
λ
(CuK
α
1
) = 1 537
.
400 xu(CuK
α
1
)
(345)
λ
(MoK
α
1
) = 707
.
831 xu(MoK
α
1
)
(346)
λ
(WK
α
1
) = 0
.
209 010 0 Ëš
A
∗
.
(347)
The experimental work that determines the best values
of these three units was reviewed in CODATA-98, and the
relevant data may be summarized as follows:
λ
(CuK
α
1
)
d
220
(
W4
.
2a
)
= 0
.
802 327 11(24) [3
.
0
×
10
−
7
]
(348)
λ
(WK
α
1
)
d
220
(
N
)
= 0
.
108 852 175(98) [9
.
0
×
10
−
7
] (349)
λ
(MoK
α
1
)
d
220
(
N
)
= 0
.
369 406 04(19) [5
.
3
×
10
−
7
]
(350)
λ
(CuK
α
1
)
d
220
(
N
)
= 0
.
802 328 04(77) [9
.
6
×
10
−
7
]
,
(351)
60
where
d
220
(
W4
.
2a
) and
d
220
(
N
) denote the
{
220
}
lattice
spacings, at the standard reference conditions
p
= 0 and
t
90
= 22
.
5
â—¦
C, of particular silicon crystals used in the
measurements. The result in Eq. (348) is from a collab-
oration between researchers from Friedrich-Schiller Uni-
versity (FSU), Jena, Germany and the PTB (H¨artwig
et al.
, 1991). The lattice spacing
d
220
(
N
) is related to
crystals of known lattice spacing through Eq. (301).
In order to obtain best values in the least-squares sense
for xu(CuK
α
1
), xu(MoK
α
1
), and Ëš
A
∗
, we take these units
to be adjusted constants. Thus, the observational equa-
tions for the data of Eqs. (348) to (351) are
λ
(CuK
α
1
)
d
220
(
W4
.
2a
)
=
1 537
.
400 xu(CuK
α
1
)
d
220
(
W4
.
2a
)
(352)
λ
(WK
α
1
)
d
220
(
N
)
=
0
.
209 010 0 Ëš
A
∗
d
220
(
N
)
(353)
λ
(MoK
α
1
)
d
220
(
N
)
=
707
.
831 xu(MoK
α
1
)
d
220
(
N
)
(354)
λ
(CuK
α
1
)
d
220
(
N
)
=
1 537
.
400 xu(CuK
α
1
)
d
220
(
N
)
,
(355)
where
d
220
(
N
) is taken to be an adjusted constant and
d
220
(
W17
) and
d
220
(
W4
.
2a
) are adjusted constants as well.
B. Particle Data Group input
There are a few cases in the 2006 adjustment where
an inexact constant that is used in the analysis of input
data is not treated as an adjusted quantity, because the
adjustment has a negligible effect on its value. Three
such constants, used in the calculation of the theoretical
expressions for the electron and muon magnetic moment
anomalies
a
e
and
a
µ
, are the mass of the tau lepton
m
Ï„
,
the Fermi coupling constant
G
F
, and sine squared of the
weak mixing angle sin
2
θ
W
, and are obtained from the
most recent report of the Particle Data Group (Yao
et al.
,
2006):
m
Ï„
c
2
= 1776
.
99(29) MeV
[1
.
6
×
10
−
4
]
(356)
G
F
(¯
hc
)
3
= 1
.
166 37(1)
×
10
−
5
GeV
−
2
[8
.
6
×
10
−
6
]
(357)
sin
2
θ
W
= 0
.
222 55(56)
[2
.
5
×
10
−
3
]
.
(358)
To facilitate the calculations, the uncertainty of
m
Ï„
c
2
is symmetrized and taken to be 0.29 MeV rather than
+0
.
29 MeV,
−
0
.
26 MeV. We use the deï¬nition sin
2
θ
W
=
1
−
(
m
W
/m
Z
)
2
, where
m
W
and
m
Z
are, respectively,
the masses of the W
±
and Z
0
bosons, because it is em-
ployed in the calculation of the electroweak contributions
to
a
e
and
a
µ
(Czarnecki
et al.
, 1996). The Particle Data
Group’s recommended value for the mass ratio of these
bosons is
m
W
/m
Z
= 0
.
881 73(32), which leads to the
value of sin
2
θ
W
given above.
XII. ANALYSIS OF DATA
The previously discussed input data are examined in
this section for their mutual compatibility and their po-
tential role in determining the 2006 recommended values
of the constants. Based on this analysis, the data are se-
lected for the ï¬nal least-squares adjustment from which
the recommended values are obtained. Because the data
on the Newtonian constant of gravitation
G
are indepen-
dent of the other data and are analyzed in Sec. X, they
are not examined further. The consistency of the input
data is evaluated by directly comparing different mea-
surements of the same quantity, and by directly compar-
ing the values of a single fundamental constant inferred
from measurements of different quantities. As noted in
the outline section of this paper, the inferred value is for
comparison purposes only; the datum from which it is
obtained, not the inferred value, is the input datum in
the adjustment. The potential role of a particular input
datum is gauged by carrying out a least-squares adjust-
ment using all of the initially considered data. A partic-
ular measurement of a quantity is included in the ï¬nal
adjustment if its uncertainty is not more than about ten
times the uncertainty of the value of that quantity pro-
vided by other data in the adjustment. The measure we
use is the “self sensitivity coefficient†of an input datum
S
c
(see CODATA-98), which must be greater than 0.01
in order for the datum to be included.
The input data are given in Tables XXVIII, XXX, and
XXXII and their covariances are given as correlation co-
efficients in Tables XXIX, XXXI, and XXXIII. The
δ
s
given in Tables XXVIII, XXX, and XXXII are quan-
tities added to corresponding theoretical expressions to
account for the uncertainties of those expressions, as pre-
viously discussed (see, for example, Sec. IV.A.1.l). Note
that the value of the Rydberg constant
R
∞
depends only
weakly on changes, at the level of the uncertainties, of the
data in Tables XXX and XXXII.
61
TABLE XXVIII Summary of principal input data for the determination of the 2006 recommended value of the Rydberg
constant
R
∞
. [The notation for the additive corrections
δ
X
(
n
L
j
) in this table has the same meaning as the notation
δ
X
n
L
j
in
Sec. IV.A.1.l.]
Item
Input datum
Value
Relative standard
Identiï¬cation
Sec.
number
uncertainty
a
u
r
A
1
δ
H
(1S
1
/
2
)
0
.
0(3
.
7) kHz
[1
.
1
×
10
−
12
]
theory
IV.A.1.l
A
2
δ
H
(2S
1
/
2
)
0
.
00(46) kHz
[5
.
6
×
10
−
13
]
theory
IV.A.1.l
A
3
δ
H
(3S
1
/
2
)
0
.
00(14) kHz
[3
.
7
×
10
−
13
]
theory
IV.A.1.l
A
4
δ
H
(4S
1
/
2
)
0
.
000(58) kHz
[2
.
8
×
10
−
13
]
theory
IV.A.1.l
A
5
δ
H
(6S
1
/
2
)
0
.
000(20) kHz
[2
.
1
×
10
−
13
]
theory
IV.A.1.l
A
6
δ
H
(8S
1
/
2
)
0
.
0000(82) kHz
[1
.
6
×
10
−
13
]
theory
IV.A.1.l
A
7
δ
H
(2P
1
/
2
)
0
.
000(69) kHz
[8
.
4
×
10
−
14
]
theory
IV.A.1.l
A
8
δ
H
(4P
1
/
2
)
0
.
0000(87) kHz
[4
.
2
×
10
−
14
]
theory
IV.A.1.l
A
9
δ
H
(2P
3
/
2
)
0
.
000(69) kHz
[8
.
4
×
10
−
14
]
theory
IV.A.1.l
A
10
δ
H
(4P
3
/
2
)
0
.
0000(87) kHz
[4
.
2
×
10
−
14
]
theory
IV.A.1.l
A
11
δ
H
(8D
3
/
2
)
0
.
000 00(48) kHz
[9
.
3
×
10
−
15
]
theory
IV.A.1.l
A
12
δ
H
(12D
3
/
2
)
0
.
000 00(15) kHz
[6
.
6
×
10
−
15
]
theory
IV.A.1.l
A
13
δ
H
(4D
5
/
2
)
0
.
0000(38) kHz
[1
.
9
×
10
−
14
]
theory
IV.A.1.l
A
14
δ
H
(6D
5
/
2
)
0
.
0000(11) kHz
[1
.
2
×
10
−
14
]
theory
IV.A.1.l
A
15
δ
H
(8D
5
/
2
)
0
.
000 00(48) kHz
[9
.
3
×
10
−
15
]
theory
IV.A.1.l
A
16
δ
H
(12D
5
/
2
)
0
.
000 00(16) kHz
[7
.
0
×
10
−
15
]
theory
IV.A.1.l
A
17
δ
D
(1S
1
/
2
)
0
.
0(3
.
6) kHz
[1
.
1
×
10
−
12
]
theory
IV.A.1.l
A
18
δ
D
(2S
1
/
2
)
0
.
00(45) kHz
[5
.
4
×
10
−
13
]
theory
IV.A.1.l
A
19
δ
D
(4S
1
/
2
)
0
.
000(56) kHz
[2
.
7
×
10
−
13
]
theory
IV.A.1.l
A
20
δ
D
(8S
1
/
2
)
0
.
0000(80) kHz
[1
.
6
×
10
−
13
]
theory
IV.A.1.l
A
21
δ
D
(8D
3
/
2
)
0
.
000 00(48) kHz
[9
.
3
×
10
−
15
]
theory
IV.A.1.l
A
22
δ
D
(12D
3
/
2
)
0
.
000 00(15) kHz
[6
.
6
×
10
−
15
]
theory
IV.A.1.l
A
23
δ
D
(4D
5
/
2
)
0
.
0000(38) kHz
[1
.
9
×
10
−
14
]
theory
IV.A.1.l
A
24
δ
D
(8D
5
/
2
)
0
.
000 00(48) kHz
[9
.
3
×
10
−
15
]
theory
IV.A.1.l
A
25
δ
D
(12D
5
/
2
)
0
.
000 00(16) kHz
[7
.
0
×
10
−
15
]
theory
IV.A.1.l
A
26
ν
H
(1S
1
/
2
−
2S
1
/
2
)
2 466 061 413 187
.
074(34) kHz
1
.
4
×
10
−
14
MPQ-04
IV.A.2
A
27
ν
H
(2S
1
/
2
−
8S
1
/
2
)
770 649 350 012
.
0(8
.
6) kHz
1
.
1
×
10
−
11
LK/SY-97
IV.A.2
A
28
ν
H
(2S
1
/
2
−
8D
3
/
2
)
770 649 504 450
.
0(8
.
3) kHz
1
.
1
×
10
−
11
LK/SY-97
IV.A.2
A
29
ν
H
(2S
1
/
2
−
8D
5
/
2
)
770 649 561 584
.
2(6
.
4) kHz
8
.
3
×
10
−
12
LK/SY-97
IV.A.2
A
30
ν
H
(2S
1
/
2
−
12D
3
/
2
)
799 191 710 472
.
7(9
.
4) kHz
1
.
2
×
10
−
11
LK/SY-98
IV.A.2
A
31
ν
H
(2S
1
/
2
−
12D
5
/
2
)
799 191 727 403
.
7(7
.
0) kHz
8
.
7
×
10
−
12
LK/SY-98
IV.A.2
A
32
ν
H
(2S
1
/
2
−
4S
1
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
2S
1
/
2
)
4 797 338(10) kHz
2
.
1
×
10
−
6
MPQ-95
IV.A.2
A
33
ν
H
(2S
1
/
2
−
4D
5
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
2S
1
/
2
)
6 490 144(24) kHz
3
.
7
×
10
−
6
MPQ-95
IV.A.2
A
34
ν
H
(2S
1
/
2
−
6S
1
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
3S
1
/
2
)
4 197 604(21) kHz
4
.
9
×
10
−
6
LKB-96
IV.A.2
A
35
ν
H
(2S
1
/
2
−
6D
5
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
3S
1
/
2
)
4 699 099(10) kHz
2
.
2
×
10
−
6
LKB-96
IV.A.2
A
36
ν
H
(2S
1
/
2
−
4P
1
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
2S
1
/
2
)
4 664 269(15) kHz
3
.
2
×
10
−
6
YaleU-95
IV.A.2
A
37
ν
H
(2S
1
/
2
−
4P
3
/
2
)
−
1
4
ν
H
(1S
1
/
2
−
2S
1
/
2
)
6 035 373(10) kHz
1
.
7
×
10
−
6
YaleU-95
IV.A.2
A
38
ν
H
(2S
1
/
2
−
2P
3
/
2
)
9 911 200(12) kHz
1
.
2
×
10
−
6
HarvU-94
IV.A.2
A
39
.
1
ν
H
(2P
1
/
2
−
2S
1
/
2
)
1 057 845
.
0(9
.
0) kHz
8
.
5
×
10
−
6
HarvU-86
IV.A.2
A
39
.
2
ν
H
(2P
1
/
2
−
2S
1
/
2
)
1 057 862(20) kHz
1
.
9
×
10
−
5
USus-79
IV.A.2
A
40
ν
D
(2S
1
/
2
−
8S
1
/
2
)
770 859 041 245
.
7(6
.
9) kHz
8
.
9
×
10
−
12
LK/SY-97
IV.A.2
A
41
ν
D
(2S
1
/
2
−
8D
3
/
2
)
770 859 195 701
.
8(6
.
3) kHz
8
.
2
×
10
−
12
LK/SY-97
IV.A.2
A
42
ν
D
(2S
1
/
2
−
8D
5
/
2
)
770 859 252 849
.
5(5
.
9) kHz
7
.
7
×
10
−
12
LK/SY-97
IV.A.2
A
43
ν
D
(2S
1
/
2
−
12D
3
/
2
)
799 409 168 038
.
0(8
.
6) kHz
1
.
1
×
10
−
11
LK/SY-98
IV.A.2
A
44
ν
D
(2S
1
/
2
−
12D
5
/
2
)
799 409 184 966
.
8(6
.
8) kHz
8
.
5
×
10
−
12
LK/SY-98
IV.A.2
A
45
ν
D
(2S
1
/
2
−
4S
1
/
2
)
−
1
4
ν
D
(1S
1
/
2
−
2S
1
/
2
)
4 801 693(20) kHz
4
.
2
×
10
−
6
MPQ-95
IV.A.2
A
46
ν
D
(2S
1
/
2
−
4D
5
/
2
)
−
1
4
ν
D
(1S
1
/
2
−
2S
1
/
2
)
6 494 841(41) kHz
6
.
3
×
10
−
6
MPQ-95
IV.A.2
A
47
ν
D
(1S
1
/
2
−
2S
1
/
2
)
−
ν
H
(1S
1
/
2
−
2S
1
/
2
)
670 994 334
.
64(15) kHz
2
.
2
×
10
−
10
MPQ-98
IV.A.2
A
48
R
p
0
.
895(18) fm
2
.
0
×
10
−
2
Rp-03
IV.A.3
A
49
R
d
2
.
130(10) fm
4
.
7
×
10
−
3
Rd-98
IV.A.3
a
The values in brackets are relative to the frequency equivalent of the binding energy of the indicated level.
62
TABLE XXIX Correlation coefficients
r
(
x
i
, x
j
)
≥
0
.
0001 of the input data related to
R
∞
in Table XXVIII. For simplicity, the
two items of data to which a particular correlation coefficient corresponds are identiï¬ed by their item numbers in Table XXVIII.
r
(
A
1,
A
2) = 0
.
9958
r
(
A
6,
A
19) = 0
.
8599
r
(
A
27,
A
28) = 0
.
3478
r
(
A
30,
A
44) = 0
.
1136
r
(
A
1,
A
3) = 0
.
9955
r
(
A
6,
A
20) = 0
.
9913
r
(
A
27,
A
29) = 0
.
4532
r
(
A
31,
A
34) = 0
.
0278
r
(
A
1,
A
4) = 0
.
9943
r
(
A
7,
A
8) = 0
.
0043
r
(
A
27,
A
30) = 0
.
0899
r
(
A
31,
A
35) = 0
.
0553
r
(
A
1,
A
5) = 0
.
8720
r
(
A
9,
A
10) = 0
.
0043
r
(
A
27,
A
31) = 0
.
1206
r
(
A
31,
A
40) = 0
.
1512
r
(
A
1,
A
6) = 0
.
8711
r
(
A
11,
A
12) = 0
.
0005
r
(
A
27,
A
34) = 0
.
0225
r
(
A
31,
A
41) = 0
.
1647
r
(
A
1,
A
17) = 0
.
9887
r
(
A
11,
A
21) = 0
.
9999
r
(
A
27,
A
35) = 0
.
0448
r
(
A
31,
A
42) = 0
.
1750
r
(
A
1,
A
18) = 0
.
9846
r
(
A
11,
A
22) = 0
.
0003
r
(
A
27,
A
40) = 0
.
1225
r
(
A
31,
A
43) = 0
.
1209
r
(
A
1,
A
19) = 0
.
9830
r
(
A
12,
A
21) = 0
.
0003
r
(
A
27,
A
41) = 0
.
1335
r
(
A
31,
A
44) = 0
.
1524
r
(
A
1,
A
20) = 0
.
8544
r
(
A
12,
A
22) = 0
.
9999
r
(
A
27,
A
42) = 0
.
1419
r
(
A
32,
A
33) = 0
.
1049
r
(
A
2,
A
3) = 0
.
9954
r
(
A
13,
A
14) = 0
.
0005
r
(
A
27,
A
43) = 0
.
0980
r
(
A
32,
A
45) = 0
.
2095
r
(
A
2,
A
4) = 0
.
9942
r
(
A
13,
A
15) = 0
.
0005
r
(
A
27,
A
44) = 0
.
1235
r
(
A
32,
A
46) = 0
.
0404
r
(
A
2,
A
5) = 0
.
8719
r
(
A
13,
A
16) = 0
.
0004
r
(
A
28,
A
29) = 0
.
4696
r
(
A
33,
A
45) = 0
.
0271
r
(
A
2,
A
6) = 0
.
8710
r
(
A
13,
A
23) = 0
.
9999
r
(
A
28,
A
30) = 0
.
0934
r
(
A
33,
A
46) = 0
.
0467
r
(
A
2,
A
17) = 0
.
9846
r
(
A
13,
A
24) = 0
.
0002
r
(
A
28,
A
31) = 0
.
1253
r
(
A
34,
A
35) = 0
.
1412
r
(
A
2,
A
18) = 0
.
9887
r
(
A
13,
A
25) = 0
.
0002
r
(
A
28,
A
34) = 0
.
0234
r
(
A
34,
A
40) = 0
.
0282
r
(
A
2,
A
19) = 0
.
9829
r
(
A
14,
A
15) = 0
.
0005
r
(
A
28,
A
35) = 0
.
0466
r
(
A
34,
A
41) = 0
.
0307
r
(
A
2,
A
20) = 0
.
8543
r
(
A
14,
A
16) = 0
.
0005
r
(
A
28,
A
40) = 0
.
1273
r
(
A
34,
A
42) = 0
.
0327
r
(
A
3,
A
4) = 0
.
9939
r
(
A
14,
A
23) = 0
.
0002
r
(
A
28,
A
41) = 0
.
1387
r
(
A
34,
A
43) = 0
.
0226
r
(
A
3,
A
5) = 0
.
8717
r
(
A
14,
A
24) = 0
.
0003
r
(
A
28,
A
42) = 0
.
1475
r
(
A
34,
A
44) = 0
.
0284
r
(
A
3,
A
6) = 0
.
8708
r
(
A
14,
A
25) = 0
.
0002
r
(
A
28,
A
43) = 0
.
1019
r
(
A
35,
A
40) = 0
.
0561
r
(
A
3,
A
17) = 0
.
9843
r
(
A
15,
A
16) = 0
.
0005
r
(
A
28,
A
44) = 0
.
1284
r
(
A
35,
A
41) = 0
.
0612
r
(
A
3,
A
18) = 0
.
9842
r
(
A
15,
A
23) = 0
.
0002
r
(
A
29,
A
30) = 0
.
1209
r
(
A
35,
A
42) = 0
.
0650
r
(
A
3,
A
19) = 0
.
9827
r
(
A
15,
A
24) = 0
.
9999
r
(
A
29,
A
31) = 0
.
1622
r
(
A
35,
A
43) = 0
.
0449
r
(
A
3,
A
20) = 0
.
8541
r
(
A
15,
A
25) = 0
.
0002
r
(
A
29,
A
34) = 0
.
0303
r
(
A
35,
A
44) = 0
.
0566
r
(
A
4,
A
5) = 0
.
8706
r
(
A
16,
A
23) = 0
.
0002
r
(
A
29,
A
35) = 0
.
0602
r
(
A
36,
A
37) = 0
.
0834
r
(
A
4,
A
6) = 0
.
8698
r
(
A
16,
A
24) = 0
.
0002
r
(
A
29,
A
40) = 0
.
1648
r
(
A
40,
A
41) = 0
.
5699
r
(
A
4,
A
17) = 0
.
9831
r
(
A
16,
A
25) = 0
.
9999
r
(
A
29,
A
41) = 0
.
1795
r
(
A
40,
A
42) = 0
.
6117
r
(
A
4,
A
18) = 0
.
9830
r
(
A
17,
A
18) = 0
.
9958
r
(
A
29,
A
42) = 0
.
1908
r
(
A
40,
A
43) = 0
.
1229
r
(
A
4,
A
19) = 0
.
9888
r
(
A
17,
A
19) = 0
.
9942
r
(
A
29,
A
43) = 0
.
1319
r
(
A
40,
A
44) = 0
.
1548
r
(
A
4,
A
20) = 0
.
8530
r
(
A
17,
A
20) = 0
.
8641
r
(
A
29,
A
44) = 0
.
1662
r
(
A
41,
A
42) = 0
.
6667
r
(
A
5,
A
6) = 0
.
7628
r
(
A
18,
A
19) = 0
.
9941
r
(
A
30,
A
31) = 0
.
4750
r
(
A
41,
A
43) = 0
.
1339
r
(
A
5,
A
17) = 0
.
8622
r
(
A
18,
A
20) = 0
.
8640
r
(
A
30,
A
34) = 0
.
0207
r
(
A
41,
A
44) = 0
.
1687
r
(
A
5,
A
18) = 0
.
8621
r
(
A
19,
A
20) = 0
.
8627
r
(
A
30,
A
35) = 0
.
0412
r
(
A
42,
A
43) = 0
.
1423
r
(
A
5,
A
19) = 0
.
8607
r
(
A
21,
A
22) = 0
.
0001
r
(
A
30,
A
40) = 0
.
1127
r
(
A
42,
A
44) = 0
.
1793
r
(
A
5,
A
20) = 0
.
7481
r
(
A
23,
A
24) = 0
.
0001
r
(
A
30,
A
41) = 0
.
1228
r
(
A
43,
A
44) = 0
.
5224
r
(
A
6,
A
17) = 0
.
8613
r
(
A
23,
A
25) = 0
.
0001
r
(
A
30,
A
42) = 0
.
1305
r
(
A
45,
A
46) = 0
.
0110
r
(
A
6,
A
18) = 0
.
8612
r
(
A
24,
A
25) = 0
.
0001
r
(
A
30,
A
43) = 0
.
0901
63
TABLE XXX: Summary of principal input data for the determination
of the 2006 recommended values of the fundamental constants (
R
∞
and
G
excepted).
Item
Input datum
Value
Relative standard Identiï¬cation Sec. and Eq.
number
uncertainty
a
u
r
B
1
A
r
(
1
H)
1
.
007 825 032 07(10)
1
.
0
×
10
−
10
AMDC-03
III.A
B
2
.
1
A
r
(
2
H)
2
.
014 101 777 85(36)
1
.
8
×
10
−
10
AMDC-03
III.A
B
2
.
2
A
r
(
2
H)
2
.
014 101 778 040(80)
4
.
0
×
10
−
11
UWash-06
III.A
B
3
A
r
(
3
H)
3
.
016 049 2787(25)
4
.
0
×
10
−
11
MSL-06
III.A
B
4
A
r
(
3
He)
3
.
016 029 3217(26)
8
.
6
×
10
−
10
MSL-06
III.A
B
5
A
r
(
4
He)
4
.
002 603 254 131(62)
1
.
5
×
10
−
11
UWash-06
III.A
B
6
A
r
(
16
O)
15
.
994 914 619 57(18)
1
.
1
×
10
−
11
UWash-06
III.A
B
7
A
r
(
87
Rb)
86
.
909 180 526(12)
1
.
4
×
10
−
10
AMDC-03
III.A
B
8
b
A
r
(
133
Cs)
132
.
905 451 932(24)
1
.
8
×
10
−
10
AMDC-03
III.A
B
9
A
r
(e)
0
.
000 548 579 9111(12)
2
.
1
×
10
−
9
UWash-95
III.C (5)
B
10
δ
e
0
.
00(27)
×
10
−
12
[2
.
4
×
10
−
10
]
theory
V.A.1 (101)
B
11
.
1
a
e
1
.
159 652 1883(42)
×
10
−
3
3
.
7
×
10
−
9
UWash-87
V.A.2.a (102)
B
11
.
2
a
e
1
.
159 652 180 85(76)
×
10
−
3
6
.
6
×
10
−
10
HarvU-06
V.A.2.b (103)
B
12
δ
µ
0
.
0(2
.
1)
×
10
−
9
[1
.
8
×
10
−
6
]
theory
V.B.1 (126)
B
13
R
0
.
003 707 2064(20)
5
.
4
×
10
−
7
BNL-06
V.B.2 (128)
B
14
δ
C
0
.
00(27)
×
10
−
10
[1
.
4
×
10
−
11
]
theory
V.C.1 (169)
B
15
δ
O
0
.
0(1
.
1)
×
10
−
10
[5
.
3
×
10
−
11
]
theory
V.C.1 (172)
B
16
f
s
(
12
C
5+
)
/f
c
(
12
C
5+
)
4376
.
210 4989(23)
5
.
2
×
10
−
10
GSI-02
V.C.2.a (175)
B
17
f
s
(
16
O
7+
)
/f
c
(
16
O
7+
)
4164
.
376 1837(32)
7
.
6
×
10
−
10
GSI-02
V.C.2.b (178)
B
18
µ
e
−
(H)
/µ
p
(H)
−
658
.
210 7058(66)
1
.
0
×
10
−
8
MIT-72
VI.A.2.a (195)
B
19
µ
d
(D)
/µ
e
−
(D)
−
4
.
664 345 392(50)
×
10
−
4
1
.
1
×
10
−
8
MIT-84
VI.A.2.b (197)
B
20
µ
p
(HD)
/µ
d
(HD)
3
.
257 199 531(29)
8
.
9
×
10
−
9
StPtrsb-03
VI.A.2.c (201)
B
21
σ
dp
15(2)
×
10
−
9
StPtrsb-03
VI.A.2.c (203)
B
22
µ
t
(HT)
/µ
p
(HT)
1
.
066 639 887(10)
9
.
4
×
10
−
9
StPtrsb-03
VI.A.2.c (202)
B
23
σ
tp
20(3)
×
10
−
9
StPtrsb-03
VI.A.2.c (204)
B
24
µ
e
−
(H)
/µ
′
p
−
658
.
215 9430(72)
1
.
1
×
10
−
8
MIT-77
VI.A.2.d (209)
B
25
µ
′
h
/µ
′
p
−
0
.
761 786 1313(33)
4
.
3
×
10
−
9
NPL-93
VI.A.2.e (211)
B
26
µ
n
/µ
′
p
−
0
.
684 996 94(16)
2
.
4
×
10
−
7
ILL-79
VI.A.2.f (212)
B
27
δ
Mu
0(101) Hz
[2
.
3
×
10
−
8
]
theory
VI.B.1 (234)
B
28
.
1
∆
ν
Mu
4 463 302
.
88(16) kHz
3
.
6
×
10
−
8
LAMPF-82
VI.B.2.a (236)
B
28
.
2
∆
ν
Mu
4 463 302 765(53) Hz
1
.
2
×
10
−
8
LAMPF-99
VI.B.2.b (239)
B
29
ν
(58 MHz)
627 994
.
77(14) kHz
2
.
2
×
10
−
7
LAMPF-82
VI.B.2.a (237)
B
30
ν
(72 MHz)
668 223 166(57) Hz
8
.
6
×
10
−
8
LAMPF-99
VI.B.2.b (240)
B
31
.
1
b
Γ
′
p
−
90
(lo)
2
.
675 154 05(30)
×
10
8
s
−
1
T
−
1
1
.
1
×
10
−
7
NIST-89
VII.A.1.a (253)
B
31
.
2
b
Γ
′
p
−
90
(lo)
2
.
675 1530(18)
×
10
8
s
−
1
T
−
1
6
.
6
×
10
−
7
NIM-95
VII.A.1.b (255)
B
32
b
Γ
′
h
−
90
(lo)
2
.
037 895 37(37)
×
10
8
s
−
1
T
−
1
1
.
8
×
10
−
7
KR/VN-98
VII.A.1.c (257)
B
33
.
1
b
Γ
′
p
−
90
(hi)
2
.
675 1525(43)
×
10
8
s
−
1
T
−
1
1
.
6
×
10
−
6
NIM-95
VII.A.2.a (259)
B
33
.
2
b
Γ
′
p
−
90
(hi)
2
.
675 1518(27)
×
10
8
s
−
1
T
−
1
1
.
0
×
10
−
6
NPL-79
VII.A.2.b (262)
B
34
.
1
b
R
K
25 812
.
808 31(62) Ω
2
.
4
×
10
−
8
NIST-97
VII.B.1 (265)
B
34
.
2
b
R
K
25 812
.
8071(11) Ω
4
.
4
×
10
−
8
NMI-97
VII.B.2 (267)
B
34
.
3
b
R
K
25 812
.
8092(14) Ω
5
.
4
×
10
−
8
NPL-88
VII.B.3 (269)
B
34
.
4
b
R
K
25 812
.
8084(34) Ω
1
.
3
×
10
−
7
NIM-95
VII.B.4 (271)
B
34
.
5
b
R
K
25 812
.
8081(14) Ω
5
.
3
×
10
−
8
LNE-01
VII.B.5 (273)
B
35
.
1
b
K
J
483 597
.
91(13) GHz V
−
1
2
.
7
×
10
−
7
NMI-89
VII.C.1 (276)
B
35
.
2
b
K
J
483 597
.
96(15) GHz V
−
1
3
.
1
×
10
−
7
PTB-91
VII.C.2 (278)
B
36
.
1
c
K
2
J
R
K
6
.
036 7625(12)
×
10
33
J
−
1
s
−
1
2
.
0
×
10
−
7
NPL-90
VII.D.1 (281)
B
36
.
2
c
K
2
J
R
K
6
.
036 761 85(53)
×
10
33
J
−
1
s
−
1
8
.
7
×
10
−
8
NIST-98
VII.D.2.a (283)
B
36
.
3
c
K
2
J
R
K
6
.
036 761 85(22)
×
10
33
J
−
1
s
−
1
3
.
6
×
10
−
8
NIST-07
VII.D.2.b (287)
B
37
b
F
90
96 485
.
39(13) C mol
−
1
1
.
3
×
10
−
6
NIST-80
VII.E.1 (295)
64
TABLE XXX:
(Continued).
Summary of principal input data for the
determination of the 2006 recommended values of the fundamental con-
stants (
R
∞
and
G
excepted).
Item
Input datum
Value
Relative standard Identiï¬cation Sec. and Eq.
number
uncertainty
a
u
r
B
38
.
1
c
d
220
(
W4
.
2a
)
192 015
.
563(12) fm
6
.
2
×
10
−
8
PTB-81
VIII.A.1.a (297)
B
38
.
2
c
d
220
(
W4
.
2a
)
192 015
.
5715(33) fm
1
.
7
×
10
−
8
INRIM-07
VIII.A.1.c (299)
B
39
c
d
220
(
NR3
)
192 015
.
5919(76) fm
4
.
0
×
10
−
8
NMIJ-04
VIII.A.1.b (298)
B
40
c
d
220
(
MO
∗
)
192 015
.
5498(51) fm
2
.
6
×
10
−
8
INRIM-07
VIII.A.1.c (300)
B
41
1
−
d
220
(
N
)
/d
220
(
W17
)
7(22)
×
10
−
9
NIST-97
VIII.A.2.a (301)
B
42
1
−
d
220
(
W17
)
/d
220
(
ILL
)
−
8(22)
×
10
−
9
NIST-99
VIII.A.2.a (302)
B
43
1
−
d
220
(
MO
∗
)
/d
220
(
ILL
)
86(27)
×
10
−
9
NIST-99
VIII.A.2.a (303)
B
44
1
−
d
220
(
NR3
)
/d
220
(
ILL
)
34(22)
×
10
−
9
NIST-99
VIII.A.2.a (304)
B
45
d
220
(
NR3
)
/d
220
(
W04
)
−
1
−
11(21)
×
10
−
9
NIST-06
VIII.A.2.a (305)
B
46
d
220
(
NR4
)
/d
220
(
W04
)
−
1
25(21)
×
10
−
9
NIST-06
VIII.A.2.a (306)
B
47
d
220
(
W17
)
/d
220
(
W04
)
−
1
11(21)
×
10
−
9
NIST-06
VIII.A.2.a (307)
B
48
d
220
(
W4
.
2a
)
/d
220
(
W04
)
−
1
−
1(21)
×
10
−
9
PTB-98
VIII.A.2.b (308)
B
49
d
220
(
W17
)
/d
220
(
W04
)
−
1
22(22)
×
10
−
9
PTB-98
VIII.A.2.b (309)
B
50
d
220
(
MO
∗
)
/d
220
(
W04
)
−
1
−
103(28)
×
10
−
9
PTB-98
VIII.A.2.b (310)
B
51
d
220
(
NR3
)
/d
220
(
W04
)
−
1
−
23(21)
×
10
−
9
PTB-98
VIII.A.2.b (311)
B
52
d
220
/d
220
(
W04
)
−
1
10(11)
×
10
−
9
PTB-03
VIII.A.2.b (312)
B
53
c
V
m
(Si)
12
.
058 8254(34)
×
10
−
6
m
3
mol
−
1
2
.
8
×
10
−
7
N/P/I-05
VIII.B (317)
B
54
λ
meas
/d
220
(
ILL
)
0
.
002 904 302 46(50) m s
−
1
1
.
7
×
10
−
7
NIST-99
VIII.C (319)
B
55
c
h/m
n
d
220
(
W04
)
2060
.
267 004(84) m s
−
1
4
.
1
×
10
−
8
PTB-99
VIII.D.1 (322)
B
56
b
h/m
(
133
Cs)
3
.
002 369 432(46)
×
10
−
9
m
2
s
−
1
1
.
5
×
10
−
8
StanfU-02
VIII.D.2 (329)
B
57
h/m
(
87
Rb)
4
.
591 359 287(61)
×
10
−
9
m
2
s
−
1
1
.
3
×
10
−
8
LKB-06
VIII.D.3 (332)
B
58
.
1
R
8
.
314 471(15) J mol
−
1
K
−
1
1
.
8
×
10
−
6
NIST-88
IX.A.1 (338)
B
58
.
2
R
8
.
314 504(70) J mol
−
1
K
−
1
8
.
4
×
10
−
6
NPL-79
IX.A.2 (339)
B
59
λ
(CuK
α
1
)
/d
220
(
W4
.
2a
)
0
.
802 327 11(24)
3
.
0
×
10
−
7
FSU/PTB-91 XI.A (348)
B
60
λ
(WK
α
1
)
/d
220
(
N
)
0
.
108 852 175(98)
9
.
0
×
10
−
7
NIST-79
XI.A (349)
B
61
λ
(MoK
α
1
)
/d
220
(
N
)
0
.
369 406 04(19)
5
.
3
×
10
−
7
NIST-73
XI.A (350)
B
62
λ
(CuK
α
1
)
/d
220
(
N
)
0
.
802 328 04(77)
9
.
6
×
10
−
7
NIST-73
XI.A (351)
a
The values in brackets are relative to the quantities
a
e
,
a
µ
,
g
e
−
(
12
C
5+
),
g
e
−
(
16
O
7+
), or ∆
ν
Mu
as appropriate.
b
Datum not included in the final least-squares adjustment that provides the recommended values of the constants.
c
Datum included in the final least-squares adjustment with an expanded uncertainty.
A. Comparison of data
The classic Lamb shift is the only quantity among the
Rydberg constant data with more than one measured
value, but there are ten different quantities with more
than one measured value among the other data. The
item numbers given in Tables XXVIII and XXX for the
members of such groups of data (
A
39,
B
2,
B
11,
B
28,
B
31,
B
33-
B
36,
B
38, and
B
58) have a decimal point with
an additional digit to label each member.
In fact, all of the data for which there is more than one
measurement were directly compared in either the 1998
or 2002 adjustments except the following new data: the
University of Washington result for
A
r
(
2
H), item
B
2
.
2,
the Harvard University result for
a
e
, item
B
11
.
2, the
NIST watt-balance result for
K
2
J
R
K
item
B
36
.
3, and the
INRIM result for
d
220
(
W4
.
2a
), item
B
38
.
2. The two val-
ues of
A
r
(
2
H) agree well—they differ by only 0.5
u
diff
; the
two values of
a
e
are in acceptable agreement—they differ
by 1.7
u
diff
; the two values of
d
220
(
W4
.
2a
) also agree well–
they differ by 0.7
u
diff
; and the three values of
K
2
J
R
K
are
highly consistent—their mean and implied value of
h
are
K
2
J
R
K
= 6
.
036 761 87(21)
×
10
33
J
−
1
s
−
1
(359)
h
= 6
.
626 068 89(23)
×
10
−
34
J s
(360)
with
χ
2
= 0
.
27 for
ν
=
N
−
M
= 2 degrees of free-
dom, where
N
is the number of measurements and
M
is the number of unknowns, and with Birge ratio
R
B
=
p
χ
2
/ν
= 0
.
37 (see Appendix E of CODATA-98). The
normalized residuals for the three values are 0
.
52,
−
0
.
04,
and
−
0
.
09, and their weights in the calculation of the
weighted mean are 0.03, 0.10, and 0.87.
Data for quantities with more than one directly mea-
sured value used in earlier adjustments are consis-
tent, with the exception of the VNIIM 1989 result for
Γ
′
h
−
90
(lo), which is not included in the present adjust-
ment (see Sec. VII). We also note that none of these
data has a weight of less than 0.02 in the weighted mean
of measurements of the same quantity.
65
TABLE XXXI Non-negligible correlation coefficients
r
(
x
i
, x
j
) of the input data in Table XXX. For simplicity, the two items
of data to which a particular correlation coefficient corresponds are identiï¬ed by their item numbers in Table XXX.
r
(
B
1,
B
2
.
1) = 0
.
073
r
(
B
38
.
1,
B
38
.
2) = 0
.
191
r
(
B
42,
B
46) = 0
.
065
r
(
B
46,
B
47) = 0
.
509
r
(
B
2
.
2,
B
5) = 0
.
127
r
(
B
38
.
2,
B
40) = 0
.
057
r
(
B
42,
B
47) =
−
0
.
367
r
(
B
48,
B
49) = 0
.
469
r
(
B
2
.
2,
B
6) = 0
.
089
r
(
B
41,
B
42) =
−
0
.
288
r
(
B
43,
B
44) = 0
.
421
r
(
B
48,
B
50) = 0
.
372
r
(
B
5,
B
6) = 0
.
181
r
(
B
41,
B
43) = 0
.
096
r
(
B
43,
B
45) = 0
.
053
r
(
B
48,
B
51) = 0
.
502
r
(
B
14,
B
15) = 0
.
919
r
(
B
41,
B
44) = 0
.
117
r
(
B
43,
B
46) = 0
.
053
r
(
B
48,
B
55) = 0
.
258
r
(
B
16,
B
17) = 0
.
082
r
(
B
41,
B
45) = 0
.
066
r
(
B
43,
B
47) = 0
.
053
r
(
B
49,
B
50) = 0
.
347
r
(
B
28
.
1,
B
29) = 0
.
227
r
(
B
41,
B
46) = 0
.
066
r
(
B
44,
B
45) =
−
0
.
367
r
(
B
49,
B
51) = 0
.
469
r
(
B
28
.
2,
B
30) = 0
.
195
r
(
B
41,
B
47) = 0
.
504
r
(
B
44,
B
46) = 0
.
065
r
(
B
49,
B
55) = 0
.
241
r
(
B
31
.
2,
B
33
.
1) =
−
0
.
014
r
(
B
42,
B
43) = 0
.
421
r
(
B
44,
B
47) = 0
.
065
r
(
B
50,
B
51) = 0
.
372
r
(
B
35
.
1,
B
58
.
1) = 0
.
068
r
(
B
42,
B
44) = 0
.
516
r
(
B
45,
B
46) = 0
.
509
r
(
B
50,
B
55) = 0
.
192
r
(
B
36
.
2,
B
36
.
3) = 0
.
140
r
(
B
42,
B
45) = 0
.
065
r
(
B
45,
B
47) = 0
.
509
r
(
B
51,
B
55) = 0
.
258
TABLE XXXII Summary of principal input data for the determination of the relative atomic mass of the electron from
antiprotonic helium transitions. The numbers in parentheses (
n, l
:
n
′
, l
′
) denote the transition (
n, l
)
→
(
n
′
, l
′
).
Item
Input Datum
Value
Relative standard
Identiï¬cation
Sec.
number
uncertainty
a
u
r
C
1
δ
¯
p
4
He
+
(32
,
31 : 31
,
30)
0
.
00(82) MHz
[7
.
3
×
10
−
10
]
JINR-06
IV.B
C
2
δ
¯
p
4
He
+
(35
,
33 : 34
,
32)
0
.
0(1
.
0) MHz
[1
.
3
×
10
−
9
]
JINR-06
IV.B
C
3
δ
¯
p
4
He
+
(36
,
34 : 35
,
33)
0
.
0(1
.
2) MHz
[1
.
6
×
10
−
9
]
JINR-06
IV.B
C
4
δ
¯
p
4
He
+
(39
,
35 : 38
,
34)
0
.
0(1
.
1) MHz
[1
.
8
×
10
−
9
]
JINR-06
IV.B
C
5
δ
¯
p
4
He
+
(40
,
35 : 39
,
34)
0
.
0(1
.
2) MHz
[2
.
4
×
10
−
9
]
JINR-06
IV.B
C
6
δ
¯
p
4
He
+
(32
,
31 : 31
,
30)
0
.
0(1
.
3) MHz
[2
.
9
×
10
−
9
]
JINR-06
IV.B
C
7
δ
¯
p
4
He
+
(37
,
35 : 38
,
34)
0
.
0(1
.
8) MHz
[4
.
4
×
10
−
9
]
JINR-06
IV.B
C
8
δ
¯
p
3
He
+
(32
,
31 : 31
,
30)
0
.
00(91) MHz
[8
.
7
×
10
−
10
]
JINR-06
IV.B
C
9
δ
¯
p
3
He
+
(34
,
32 : 33
,
31)
0
.
0(1
.
1) MHz
[1
.
4
×
10
−
9
]
JINR-06
IV.B
C
10
δ
¯
p
3
He
+
(36
,
33 : 35
,
32)
0
.
0(1
.
2) MHz
[1
.
8
×
10
−
9
]
JINR-06
IV.B
C
11
δ
¯
p
3
He
+
(38
,
34 : 37
,
33)
0
.
0(1
.
1) MHz
[2
.
3
×
10
−
9
]
JINR-06
IV.B
C
12
δ
¯
p
3
He
+
(36
,
34 : 37
,
33)
0
.
0(1
.
8) MHz
[4
.
4
×
10
−
9
]
JINR-06
IV.B
C
13
ν
¯
p
4
He
+
(32
,
31 : 31
,
30)
1 132 609 209(15) MHz
1
.
4
×
10
−
8
CERN-06
IV.B
C
14
ν
¯
p
4
He
+
(35
,
33 : 34
,
32)
804 633 059
.
0(8
.
2) MHz
1
.
0
×
10
−
8
CERN-06
IV.B
C
15
ν
¯
p
4
He
+
(36
,
34 : 35
,
33)
717 474 004(10) MHz
1
.
4
×
10
−
8
CERN-06
IV.B
C
16
ν
¯
p
4
He
+
(39
,
35 : 38
,
34)
636 878 139
.
4(7
.
7) MHz
1
.
2
×
10
−
8
CERN-06
IV.B
C
17
ν
¯
p
4
He
+
(40
,
35 : 39
,
34)
501 948 751
.
6(4
.
4) MHz
8
.
8
×
10
−
9
CERN-06
IV.B
C
18
ν
¯
p
4
He
+
(32
,
31 : 31
,
30)
445 608 557
.
6(6
.
3) MHz
1
.
4
×
10
−
8
CERN-06
IV.B
C
19
ν
¯
p
4
He
+
(37
,
35 : 38
,
34)
412 885 132
.
2(3
.
9) MHz
9
.
4
×
10
−
9
CERN-06
IV.B
C
20
ν
¯
p
3
He
+
(32
,
31 : 31
,
30)
1 043 128 608(13) MHz
1
.
3
×
10
−
8
CERN-06
IV.B
C
21
ν
¯
p
3
He
+
(34
,
32 : 33
,
31)
822 809 190(12) MHz
1
.
5
×
10
−
8
CERN-06
IV.B
C
22
ν
¯
p
3
He
+
(36
,
33 : 34
,
32)
646 180 434(12) MHz
1
.
9
×
10
−
8
CERN-06
IV.B
C
23
ν
¯
p
3
He
+
(38
,
34 : 37
,
33)
505 222 295
.
7(8
.
2) MHz
1
.
6
×
10
−
8
CERN-06
IV.B
C
24
ν
¯
p
3
He
+
(36
,
34 : 37
,
33)
414 147 507
.
8(4
.
0) MHz
9
.
7
×
10
−
9
CERN-06
IV.B
a
The values in brackets are relative to the corresponding transition frequency.
The consistency of measurements of various quantities
of different types is shown mainly by comparing the val-
ues of the ï¬ne-structure constant
α
or the Planck con-
stant
h
inferred from the measured values of the quanti-
ties. Such inferred values of
α
and
h
are given throughout
the data review sections, and the results are summarized
and discussed further here.
The consistency of a signiï¬cant fraction of the data of
Tables XXVIII and XXX is indicated in Table XXXIV
and Figs. 3, 4, and 5, which give and graphically compare
the values of
α
inferred from that data. Figures 3 and 4
compare the data that yield values of
α
with
u
r
<
10
−
7
and
u
r
<
10
−
8
, respectively; Fig. 5 also compares the
data that yield values of
α
with
u
r
<
10
−
7
, but does
so through combined values of
α
obtained from similar
experiments. Most of the values of
α
are in reasonable
agreement, implying that most of the data from which
they are obtained are reasonably consistent. There are,
however, two important exceptions.
The value of
α
inferred from the PTB measurement of
h/m
n
d
220
(
W04
), item
B
55, is based on the mean value
d
220
of
d
220
(
W04
) implied by the four direct
{
220
}
XROI
66
TABLE XXXIII Non-negligible correlation coefficients
r
(
x
i
, x
j
) of the input data in Table XXXII. For simplicity, the two
items of data to which a particular correlation coefficient corresponds are identiï¬ed by their item numbers in Table XXXII.
r
(
C
1,
C
2) = 0
.
929
r
(
C
9,
C
10) = 0
.
925
r
(
C
14,
C
23) = 0
.
132
r
(
C
17,
C
24) = 0
.
287
r
(
C
1,
C
3) = 0
.
912
r
(
C
9,
C
11) = 0
.
949
r
(
C
14,
C
24) = 0
.
271
r
(
C
18,
C
19) = 0
.
235
r
(
C
1,
C
4) = 0
.
936
r
(
C
9,
C
12) = 0
.
978
r
(
C
15,
C
16) = 0
.
223
r
(
C
18,
C
20) = 0
.
107
r
(
C
1,
C
5) = 0
.
883
r
(
C
10,
C
11) = 0
.
907
r
(
C
15,
C
17) = 0
.
198
r
(
C
18,
C
21) = 0
.
118
r
(
C
1,
C
6) = 0
.
758
r
(
C
10,
C
12) = 0
.
934
r
(
C
15,
C
18) = 0
.
140
r
(
C
18,
C
22) = 0
.
122
r
(
C
1,
C
7) = 0
.
957
r
(
C
11,
C
12) = 0
.
959
r
(
C
15,
C
19) = 0
.
223
r
(
C
18,
C
23) = 0
.
112
r
(
C
2,
C
3) = 0
.
900
r
(
C
13,
C
14) = 0
.
210
r
(
C
15,
C
20) = 0
.
128
r
(
C
18,
C
24) = 0
.
229
r
(
C
2,
C
4) = 0
.
924
r
(
C
13,
C
15) = 0
.
167
r
(
C
15,
C
21) = 0
.
142
r
(
C
19,
C
20) = 0
.
170
r
(
C
2,
C
5) = 0
.
872
r
(
C
13,
C
16) = 0
.
224
r
(
C
15,
C
22) = 0
.
141
r
(
C
19,
C
21) = 0
.
188
r
(
C
2,
C
6) = 0
.
748
r
(
C
13,
C
17) = 0
.
197
r
(
C
15,
C
23) = 0
.
106
r
(
C
19,
C
22) = 0
.
191
r
(
C
2,
C
7) = 0
.
945
r
(
C
13,
C
18) = 0
.
138
r
(
C
15,
C
24) = 0
.
217
r
(
C
19,
C
23) = 0
.
158
r
(
C
3,
C
4) = 0
.
907
r
(
C
13,
C
19) = 0
.
222
r
(
C
16,
C
17) = 0
.
268
r
(
C
19,
C
24) = 0
.
324
r
(
C
3,
C
5) = 0
.
856
r
(
C
13,
C
20) = 0
.
129
r
(
C
16,
C
18) = 0
.
193
r
(
C
20,
C
21) = 0
.
109
r
(
C
3,
C
6) = 0
.
734
r
(
C
13,
C
21) = 0
.
142
r
(
C
16,
C
19) = 0
.
302
r
(
C
20,
C
22) = 0
.
108
r
(
C
3,
C
7) = 0
.
927
r
(
C
13,
C
22) = 0
.
141
r
(
C
16,
C
20) = 0
.
172
r
(
C
20,
C
23) = 0
.
081
r
(
C
4,
C
5) = 0
.
878
r
(
C
13,
C
23) = 0
.
106
r
(
C
16,
C
21) = 0
.
190
r
(
C
20,
C
24) = 0
.
166
r
(
C
4,
C
6) = 0
.
753
r
(
C
13,
C
24) = 0
.
216
r
(
C
16,
C
22) = 0
.
189
r
(
C
21,
C
22) = 0
.
120
r
(
C
4,
C
7) = 0
.
952
r
(
C
14,
C
15) = 0
.
209
r
(
C
16,
C
23) = 0
.
144
r
(
C
21,
C
23) = 0
.
090
r
(
C
5,
C
6) = 0
.
711
r
(
C
14,
C
16) = 0
.
280
r
(
C
16,
C
24) = 0
.
294
r
(
C
21,
C
24) = 0
.
184
r
(
C
5,
C
7) = 0
.
898
r
(
C
14,
C
17) = 0
.
247
r
(
C
17,
C
18) = 0
.
210
r
(
C
22,
C
23) = 0
.
091
r
(
C
6,
C
7) = 0
.
770
r
(
C
14,
C
18) = 0
.
174
r
(
C
17,
C
19) = 0
.
295
r
(
C
22,
C
24) = 0
.
186
r
(
C
8,
C
9) = 0
.
978
r
(
C
14,
C
19) = 0
.
278
r
(
C
17,
C
20) = 0
.
152
r
(
C
23,
C
24) = 0
.
154
r
(
C
8,
C
10) = 0
.
934
r
(
C
14,
C
20) = 0
.
161
r
(
C
17,
C
21) = 0
.
167
r
(
C
8,
C
11) = 0
.
959
r
(
C
14,
C
21) = 0
.
178
r
(
C
17,
C
22) = 0
.
169
r
(
C
8,
C
12) = 0
.
988
r
(
C
14,
C
22) = 0
.
177
r
(
C
17,
C
23) = 0
.
141
(
α
−
1
−
137
.
03)
×
10
5
597
598
599
600
601
602
603
604
597
598
599
600
601
602
603
604
10
−
8
α
Γ
′
h
−
90
(lo) KR/VN-98
∆
ν
Mu
LAMPF
R
K
NPL-88
R
K
LNE-01
R
K
NMI-97
Γ
′
p
−
90
(lo) NIST-89
R
K
NIST-97
h/m
n
d
220
PTB-mean
h/m
(Cs) Stanford-02
h/m
(Rb) LKB-06
a
e
U Washington-87
a
e
Harvard-06
CODATA-02
CODATA-06
FIG. 3 Values of the ï¬ne-structure constant
α
with
u
r
<
10
−
7
implied by the input data in Table XXX, in order of decreas-
ing uncertainty from top to bottom, and the 2002 and 2006
CODATA recommended values of
α
. (See Table XXXIV.)
Here “mean†indicates the PTB-99 result for
h/m
n
d
220
(
W04
)
using the value of
d
220
(
W04
) implied by the four XROI lattice-
spacing measurements.
(
α
−
1
−
137
.
03)
×
10
5
599.8
600.0
600.2
600.4
599.8
600.0
600.2
600.4
10
−
8
α
h/m
(Cs) Stanford-02
h/m
(Rb) LKB-06
a
e
U Washington-87
a
e
Harvard-06
CODATA-02
CODATA-06
FIG. 4 Values of the ï¬ne-structure constant
α
with
u
r
<
10
−
8
implied by the input data in Table XXX, in order of decreas-
ing uncertainty from top to bottom. (See Table XXXIV.)
lattice spacing measurements, items
B
38
.
1-
B
40. It dis-
agrees by about 2.8
u
diff
with the value of
α
with the
smallest uncertainty, that inferred from the Harvard Uni-
versity measurement of
a
e
. Also, the value of
α
inferred
67
TABLE XXXIV Comparison of the input data in Table XXX through inferred values of the ï¬ne-structure constant
α
in order
of increasing standard uncertainty.
Primary
Item
Identiï¬cation
Sec. and Eq.
α
−
1
Relative standard
source
number
uncertainty
u
r
a
e
B
11
.
2
HarvU-06
V.A.3 (105)
137
.
035 999 711(96)
7
.
0
×
10
−
10
a
e
B
11
.
1
UWash-87
V.A.3 (104)
137
.
035 998 83(50)
3
.
7
×
10
−
9
h/m
(Rb)
B
57
LKB-06
VIII.D.3 (334)
137
.
035 998 83(91)
6
.
7
×
10
−
9
h/m
(Cs)
B
56
StanfU-02
VIII.D.2 (331)
137
.
036 0000(11)
7
.
7
×
10
−
9
h/m
n
d
220
(
W04
)
B
55
PTB-99
d
220
B
38
.
1-
B
40
Mean
VIII.D.1 (324)
137
.
036 0077(28)
2
.
1
×
10
−
8
R
K
B
34
.
1
NIST-97
VII.B.1 (266)
137
.
036 0037(33)
2
.
4
×
10
−
8
Γ
′
p
−
90
(lo)
B
31
.
1
NIST-89
VII.A.1.a (254)
137
.
035 9879(51)
3
.
7
×
10
−
8
R
K
B
34
.
2
NMI-97
VII.B.2 (268)
137
.
035 9973(61)
4
.
4
×
10
−
8
R
K
B
34
.
5
LNE-01
VII.B.5 (274)
137
.
036 0023(73)
5
.
3
×
10
−
8
R
K
B
34
.
3
NPL-88
VII.B.3 (270)
137
.
036 0083(73)
5
.
4
×
10
−
8
∆
ν
Mu
B
28
.
1,
B
28
.
2
LAMPF
VI.B.2.c (244)
137
.
036 0017(80)
5
.
8
×
10
−
8
Γ
′
h
−
90
(lo)
B
32
KR/VN-98
VII.A.1.c (258)
137
.
035 9852(82)
6
.
0
×
10
−
8
R
K
B
34
.
4
NIM-95
VII.B.4 (272)
137
.
036 004(18)
1
.
3
×
10
−
7
Γ
′
p
−
90
(lo)
B
31
.
2
NIM-95
VII.A.1.b (256)
137
.
036 006(30)
2
.
2
×
10
−
7
ν
H
, ν
D
A
26-
A
47
Various
IV.A.1.m (65)
137
.
036 002(48)
3
.
5
×
10
−
7
R
B
13
BNL-02
V.B.2.a (132)
137
.
035 67(26)
1
.
9
×
10
−
6
(
α
−
1
−
137
.
03)
×
10
5
598
599
600
601
602
598
599
600
601
602
10
−
8
α
∆
ν
Mu
Γ
′
p
,
h
−
90
(lo)
h/m
n
d
220
R
K
h/m
a
e
CODATA-02
CODATA-06
FIG. 5 Values of the ï¬ne-structure constant
α
with
u
r
<
10
−
7
implied by the input data in Table XXX, taken as a weighted
mean when more than one measurement of a given type is
considered [see Eqs. (361) to (366)], in order of decreasing
uncertainty from top to bottom.
from the NIST measurement of
Γ
′
p
−
90
(lo) disagrees with
the latter by about 2.3
u
diff
. But it is also worth noting
that the value
α
−
1
= 137
.
036 0000(38) [2
.
8
×
10
−
8
] im-
plied by
h/m
n
d
220
(
W04
) together with item
B
39 alone,
the NMIJ XROI measurement of
d
220
(
NR3
), agrees well
with the Harvard
a
e
value of
α
. If instead one uses the
three other direct XROI lattice spacing measurements,
items
B
38
.
1,
B
38
.
2, and
B
40, which agree among them-
selves, one ï¬nds
α
−
1
= 137
.
036 0092(28) [2
.
1
×
10
−
8
].
This value disagrees with
α
from the Harvard
a
e
by
3.3
u
diff
.
The values of
α
compared in Fig. 5 follow from Ta-
ble XXXIV and are, again in order of increasing uncer-
tainty,
α
−
1
[
a
e
] = 137
.
035 999 683(94)
[6
.
9
×
10
−
10
]
(361)
α
−
1
[
h/m
] = 137
.
035 999 35(69)
[5
.
0
×
10
−
9
]
(362)
α
−
1
[
R
K
] = 137
.
036 0030(25)
[1
.
8
×
10
−
8
]
(363)
α
−
1
[
h/m
n
d
220
] = 137
.
036 0077(28)
[2
.
1
×
10
−
8
]
(364)
α
−
1
[
Γ
′
p
,
h
−
90
(lo)] = 137
.
035 9875(43)
[3
.
1
×
10
−
8
]
(365)
α
−
1
[∆
ν
Mu
] = 137
.
036 0017(80)
[5
.
8
×
10
−
8
]
.
(366)
Here
α
−
1
[
a
e
] is the weighted mean of the two
a
e
values
of
α
;
α
−
1
[
h/m
] is the weighted mean of the
h/m
(
87
Rb)
and
h/m
(
133
Cs) values;
α
−
1
[
R
K
] is the weighted mean
of the ï¬ve quantum Hall effect-calculable capacitor val-
ues;
α
−
1
[
h/m
n
d
220
] is the value as given in Table XXXIV
68
and is based on the measurement of
h/m
n
d
220
(
W04
) and
the value of
d
220
(
W04
) inferred from the four XROI de-
terminations of the
{
220
}
lattice spacing of three dif-
ferent silicon crystals;
α
−
1
[
Γ
′
p
,
h
−
90
(lo)] is the weighted
mean of the two values of
α
−
1
[
Γ
′
p
−
90
(lo)] and one value
of
α
−
1
[
Γ
′
h
−
90
(lo)]; and
α
−
1
[∆
ν
Mu
] is the value as given
in Table XXXIV and is based on the 1982 and 1999 mea-
surements at LAMPF on muonium.
Figures 3, 4, and 5 show that even if all of the data of
Table XXX were retained, the 2006 recommended value
of
α
would be determined to a great extent by
a
e
, and in
particular, the Harvard University determination of
a
e
.
The consistency of a signiï¬cant fraction of the data
of Table XXX is indicated in Table XXXV and Figs. 6
and 7, which give and graphically compare the values of
h
inferred from those data. Figure 6 compares the data
by showing each inferred value of
h
in the table, while
Fig. 7 compares the data through combined values of
h
from similar experiments. The values of
h
are in good
agreement, implying that the data from which they are
obtained are consistent, with one important exception.
The value of
h
inferred from
V
m
(Si), item
B
53, disagrees
by 2.9
u
diff
with the value of
h
from the weighted mean
of the three watt-balance values of
K
2
J
R
K
[uncertainty
u
r
= 3
.
4
×
10
−
8
—see Eq. (360)].
In this regard, it is worth noting that a value of
d
220
of an ideal silicon crystal is required to obtain a value
of
h
from
V
m
(Si) [see Eq. (316)], and the value used to
obtain the inferred value of
h
given in Eq. (318) and Ta-
ble XXXV is based on all four XROI lattice spacing mea-
surements, items
B
38
.
1-
B
40, plus the indirect value from
h/m
n
d
220
(
W04
) (see Table XXIV and Fig. 1). However,
the NMIJ measurement of
d
220
(
NR3
), item
B
39, and the
indirect value of
d
220
from
h/m
n
d
220
(
W04
), yield values
of
h
from
V
m
(Si) that are less consistent with the watt-
balance mean value than the three other direct XROI
lattice spacing measurements, items
B
38
.
1,
B
38
.
2, and
B
40, which agree among themselves (a disagreement of
about 3.8
u
diff
compared to 2.5
u
diff
). In contrast, the
NMIJ measurement of
d
220
(
NR3
) yields a value of
α
from
h/m
n
d
220
(
W04
) that is in excellent agreement with the
Harvard University value from
a
e
, while the three other
lattice spacing measurements yield a value of
α
in poor
agreement with alpha from
a
e
(3.3
u
diff
).
The values of
h
compared in Fig. 7 follow from Ta-
ble XXXV and are, again in order of increasing uncer-
[
h/
(10
−
34
J s)
−
6
.
6260]
×
10
5
5
6
7
8
9
10
5
6
7
8
9
10
10
−
6
h
Γ
′
p
−
90
(hi)
NIM-95
F
90
NIST-80
Γ
′
p
−
90
(hi)
NPL-79
K
J
PTB-91
K
J
NMI-89
V
m
(Si)
N/P/I-05
K
2
J
R
K
NPL-90
K
2
J
R
K
NIST-98
K
2
J
R
K
NIST-07
CODATA-02
CODATA-06
FIG. 6 Values of the Planck constant
h
implied by the input
data in Table XXX, in order of decreasing uncertainty from
top to bottom. (See Table XXXV.)
[
h/
(10
−
34
J s)
−
6
.
6260]
×
10
5
5
6
7
8
9
10
5
6
7
8
9
10
10
−
6
h
F
90
NIST-80
Γ
′
p
−
90
(hi)
K
J
V
m
(Si)
K
2
J
R
K
CODATA-02
CODATA-06
FIG. 7 Values of the Planck constant
h
implied by the input
data in Table XXX, taken as a weighted mean when more than
one measurement of a given type is considered [see Eqs. (367)
to (371)], in order of decreasing uncertainty from top to bot-
tom.
69
TABLE XXXV Comparison of the input data in Table XXX through inferred values of the Planck constant
h
in order of
increasing standard uncertainty.
Primary
Item
Identiï¬cation
Sec. and Eq.
h/
(J s)
Relative standard
source
number
uncertainty
u
r
K
2
J
R
K
B
36
.
3
NIST-07
VII.D.2.b (288)
6
.
626 068 91(24)
×
10
−
34
3
.
6
×
10
−
8
K
2
J
R
K
B
36
.
2
NIST-98
VII.D.2.a (284)
6
.
626 068 91(58)
×
10
−
34
8
.
7
×
10
−
8
K
2
J
R
K
B
36
.
1
NPL-90
VII.D.1 (282)
6
.
626 0682(13)
×
10
−
34
2
.
0
×
10
−
7
V
m
(Si)
B
53
N/P/I-05
VIII.B (318)
6
.
626 0745(19)
×
10
−
34
2
.
9
×
10
−
7
K
J
B
35
.
1
NMI-89
VII.C.1 (277)
6
.
626 0684(36)
×
10
−
34
5
.
4
×
10
−
7
K
J
B
35
.
2
PTB-91
VII.C.2 (279)
6
.
626 0670(42)
×
10
−
34
6
.
3
×
10
−
7
Γ
′
p
−
90
(hi)
B
33
.
2
NPL-79
VII.A.2.b (263)
6
.
626 0729(67)
×
10
−
34
1
.
0
×
10
−
6
F
90
B
37
NIST-80
VII.E.1 (296)
6
.
626 0657(88)
×
10
−
34
1
.
3
×
10
−
6
Γ
′
p
−
90
(hi)
B
33
.
1
NIM-95
VII.A.2.a (261)
6
.
626 071(11)
×
10
−
34
1
.
6
×
10
−
6
tainty,
h
[
K
2
J
R
K
] = 6
.
626 068 89(23)
×
10
−
34
[3
.
4
×
10
−
8
] (367)
h
[
V
m
(Si)] = 6
.
626 0745(19)
×
10
−
34
[2
.
9
×
10
−
7
] (368)
h
[
K
J
] = 6
.
626 0678(27)
×
10
−
34
[4
.
1
×
10
−
7
] (369)
h
[
Γ
′
p
−
90
(hi)] = 6
.
626 0724(57)
×
10
−
34
[8
.
6
×
10
−
7
] (370)
h
[
F
90
] = 6
.
626 0657(88)
×
10
−
34
[1
.
3
×
10
−
6
]
.
(371)
Here
h
[
K
2
J
R
K
] is the weighted mean of the three val-
ues of
h
from the three watt-balance measurements of
K
2
J
R
K
;
h
[
V
m
(Si)] is the value as given in Table XXXV
and is based on all four XROI
d
220
lattice spacing mea-
surements plus the indirect lattice spacing value from
h/m
n
d
220
(
W04
);
h
[
K
J
] is the weighted mean of the two
direct Josephson effect measurements of
K
J
;
h
[
Γ
p
−
90
(hi)]
is the weighted mean of the two values of
h
from the two
measurements of
Γ
p
−
90
(hi); and
h
[
F
90
] is the value as
given in Table XXXV and comes from the silver coulome-
ter measurement of
F
90
. Figures 6 and 7 show that even
if all of the data of Table XXX were retained, the 2006
recommended value of
h
would be determined to a large
extent by
K
2
J
R
K
, and in particular, the NIST 2007 de-
termination of this quantity.
We conclude our data comparisons by listing in Ta-
ble XXXVI the four available values of
A
r
(e).
The
reasonable agreement of these values shows that the
corresponding input data are consistent.
The most
important of these data are the University of Wash-
ington value of
A
r
(e),
δ
C
,
δ
O
,
f
s
(
12
C
5+
)
/f
c
(
12
C
5+
),
f
s
(
12
O
7+
)
/f
c
(
12
O
7+
), and the antiprotonic helium data,
items
B
9,
B
14-
B
17, and
C
1-
C
24.
In summary, the data comparisons of this section
of the paper have identiï¬ed the following potential
problems: (i) the measurement of
V
m
(Si), item
B
53,
is inconsistent with the watt-balance measurements of
K
2
J
R
K
, items
B
36
.
1-
B
36
.
3, and somewhat inconsistent
with the mercury-electrometer and voltage-balance mea-
surements of
K
J
; (ii) the three XROI
{
220
}
lattice
spacing values
d
220
(
W4
.
2a
),
d
220
(
W4
.
2a
), and
d
220
(
MO
∗
),
items
B
38
.
1,
B
38
.
2, and
B
40, are inconsistent with the
value of
d
220
(
NR3
), item
B
39, and the measurement of
h/m
n
d
220
(
W04
), item
B
55; (iii) the NIST-89 measure-
ment of
Γ
′
p
−
90
(lo), item
B
33
.
1, is inconsistent with the
most accurate data that also determine the value of the
ï¬ne-structure constant; (iv) although not a problem in
the sense of (i)-(iii), there are a number of input data
with uncertainties so large that they are unlikely to make
a contribution to the determination of the 2006 CODATA
recommended values.
Furthermore, we note that some of the inferred values
of
α
in Table XXXIV and most of the inferred values of
h
in Table XXXV depend on either one or both of the
relations
K
J
= 2
e/h
and
R
K
=
h/e
2
. The question of
whether relaxing the assumption that these relations are
exact would reduce or possibly even eliminate some of
the observed inconsistencies, considered in Appendix F
of CODATA-02, is addressed in the section following the
next section. This study indeed conï¬rms the Josephson
and quantum Hall effect relations.
B. Multivariate analysis of data
The multivariate analysis of the data is based on the
fact that measured quantities can be expressed as theo-
retical functions of fundamental constants. These expres-
sions, or observational equations, are written in terms of
a particular independent subset of the constants whose
members are here called
adjusted constants
. The goal of
the analysis is to ï¬nd the values of the adjusted constants
that predict values for the measured data that best agree
with the data themselves in the least-squares sense (see
Appendix E of CODATA-98).
The symbol
.
= is used to indicate that an observed
value of an input datum of the particular type shown on
the left-hand side is ideally given by the function of the
adjusted constants on the right-hand side; however, the
70
two sides are not necessarily equal, because the equation
is one of an overdetermined set relating the data to the
adjusted constants. The best estimate of a quantity is
given by its observational equation evaluated with the
least-squares estimated values of the adjusted constants
on which it depends.
In essence, we follow the least-squares approach of
Aitken (1934) [see also Sheppard (1912)], who treated
the case where the input data are correlated. The 150
input data of Tables XXVIII, XXX, and XXXII are of
135 distinct types and are expressed as functions of the
79 adjusted constants listed in Tables XXXVII, XXXIX,
and XLI. The observational equations that relate the
input data to the adjusted constants are given in Ta-
bles XXXVIII, XL, and XLII.
Note that the various binding energies
E
b
(
X
)
/m
u
c
2
in Table XL, such as in the equation for item
B
1, are
treated as ï¬xed quantities with negligible uncertainties.
Similarly, the bound-state
g
-factor ratios in this table,
such as in the equation for item
B
18, are treated in the
same way. Further, the frequency
f
p
is not an adjusted
constant but is included in the equation for items
B
29
and
B
30 to indicate that they are functions of
f
p
. Finally,
the observational equation for items
B
29 and
B
30, based
on Eqs. (215), (216), and (217) of Sec. VI.B, includes the
functions
a
e
(
α, δ
e
) and
a
µ
(
α, δ
µ
) as well as the theoretical
expression for input data of type
B
28, ∆
ν
Mu
. The latter
expression is discussed in Sec. VI.B.1 and is a function
of
R
∞
, α, m
e
/m
µ
, a
µ
(
α, δ
µ
), and
δ
Mu
.
1. Summary of adjustments
A number of adjustments were carried out to gauge
the compatibility of the input data in Tables XXVIII,
XXX, and XXXII (together with their covariances in
Tables XXIX, XXXI, and XXXIII) and to assess their
influence on the values of the adjusted constants. The
results of 11 of these are given in Tables XLIII to XLV
and are discussed in the following paragraphs. Because
the adjusted value of the Rydberg constant
R
∞
is es-
sentially the same for all six adjustments summarized in
Table XLIII and equal to that of adjustment 4 of Ta-
ble XLV, the value of
R
∞
is not listed in Table XLIII. It
should also be noted that adjustment 4 of all three tables
is the same adjustment.
Adjustment 1
. This initial adjustment includes all of
the input data, four of which have normalized residuals
r
i
with absolute magnitudes signiï¬cantly greater than
2; the values of
r
i
for these four data resulting from
adjustments 1-6 are given in Table XLIV. Consistent
with the previous discussion, the four most inconsis-
tent items are the molar volume of silicon
V
m
(Si), the
quotient
h/m
n
d
220
(
W04
), the XROI measurement of the
{
220
}
lattice spacing
d
220
(
NR3
), and the NIST-89 value of
Γ
′
p
−
90
(lo). All other input data have values of
r
i
consid-
erably less than 2, except those for
ν
¯
p
3
He
(32
,
31 : 31
,
30)
and
ν
¯
p
3
He
(36
,
33 : 34
,
32), items
C
20 and
C
22, for which
r
20
= 2
.
09 and
r
22
= 2
.
06. However, the self sensitiv-
ity coefficients
S
c
for these input data are considerably
less than 0.01; hence, because their contribution to the
adjustment is small, their marginally large normalized
residuals are of little concern. In this regard, we see from
Table XLIV that three of the four inconsistent data have
values of
S
c
considerably larger than 0.01; the exception
is
Γ
′
p
−
90
(lo) with
S
c
= 0
.
0099, which is rounded to 0.010
in the table.
Adjustment 2
. Since the four direct lattice spacing
measurements, items
B
38
.
1-
B
40, are credible, as is the
measurement of
h/m
n
d
220
(
W04
), item
B
55, after due con-
sideration the CODATA Task Group on Fundamental
Constants decided that all ï¬ve of these input data should
be considered for retention, but that each of their
a priori
assigned uncertainties should be weighted by the multi-
plicative factor 1.5 to reduce
|
r
i
|
of
h/m
n
d
220
(
W04
) and of
d
220
(
NR3
) to a more acceptable level, that is, to about 2,
while maintaining their relative weights. This has been
done in adjustment 2. As can be seen from Table XLIII,
this increase of uncertainties has an inconsequential im-
pact on the value of
α
, and no impact on the value of
h
.
It does reduce
R
B
, as would be expected.
Adjustment 3
.
Again, since the measurement of
V
m
(Si), item
B
53, as well as the three measurements of
K
2
J
R
K
, items
B
36
.
1-
B
36
.
3, and the two measurements
of
K
J
, items
B
35
.
1 and
B
35
.
2, are credible, the Task
Group decided that all six should be considered for re-
tention, but that each of their
a priori
assigned uncer-
tainties should be weighted by the multiplicative factor
1.5 to reduce
|
r
i
|
of
V
m
(Si) to about 2, while maintaining
their relative weights. This has been done in adjustment
3. Note that this also reduces
|
r
i
|
of
h/m
n
d
220
(
W04
) from
2
.
03 in adjustment 2 to 1
.
89 in adjustment 3. We see from
Table XLIII that this increase in uncertainty has negligi-
ble consequences for the value of
α
, but it does increase
the uncertainty of
h
by about the same factor, as would
be expected. Also as would be expected,
R
B
is further
reduced.
It may be recalled that faced with a similar situation
in the 2002 adjustment, the Task Group decided to use a
multiplicative weighting factor of 2.325 in order to reduce
|
r
i
|
of
V
m
(Si) to 1.50. The reduced weighting factor of
1.5 in the 2006 adjustment recognizes the new value of
K
2
J
R
K
now available and the excellent agreement with
the two earlier values.
Adjustment 4
. In adjustment 3, a number of input
data, as measured by their self-sensitivity coefficients
S
c
,
do not contribute in a signiï¬cant way to the determina-
tion of the adjusted constants. We therefore omit in ad-
justment 4 those input data with
S
c
<
0
.
01 in adjustment
3 unless they are a subset of the data of an experiment
that provides other input data with
S
c
>
0
.
01. The 14
input data deleted in adjustment 4 for this reason are
B
31
.
1-
B
35
.
2,
B
37, and
B
56, which are the ï¬ve low- and
high-ï¬eld proton and helion gyromagnetic ratio results;
the ï¬ve calculable capacitor values of
R
K
; both values of
K
J
as obtained using a Hg electrometer and a voltage
71
balance; the Ag coulometer result for the Faraday con-
stant; and the recoil/atom interferometry result for the
quotient of the Planck constant and mass of the cesium-
133 atom. The respective values of
S
c
for these data in
adjustment 3 are in the range 0.0000 to 0.0099. Deleting
such marginal data is in keeping with the practice fol-
lowed in the 1998 and 2002 adjustments; see Sec. I.D of
CODATA-98.
Because
h/m
(
133
Cs), item
B
56, has been deleted as an
input datum due to its low weight,
A
r
(
133
Cs), item
B
8,
which is not coupled to any other input datum, has also
been omitted as an input datum and as an adjusted con-
stant from adjustment 4. This brings the total number
of omitted items to 15. Table XLIII shows that deleting
these 15 data has virtually no impact on the values of
α
and
h
.
Adjustment 4 is the adjustment on which the 2006
CODATA recommended values are based, and as such
it is referred to as the “ï¬nal adjustment.â€
Adjustments 5 and 6
. These adjustments are intended
to check the robustness of adjustment 4, the ï¬nal ad-
justment, while adjustments 7-11, which are summarized
in Table XLV, probe various aspects of the
R
∞
data in
Table XXVIII.
Adjustment 5 only differs from adjustment 3 in that
it does not include the input data that lead to the four
most accurate values of
α
: the two measurements of
a
e
,
items
B
11
.
1 and
B
11
.
2, the measurement of
h/m
(
133
Cs),
item
B
56, and the measurement of
h/m
(
87
Rb), item
B
57.
The
u
r
of the inferred values of
α
from these data are
7
.
0
×
10
−
10
, 3
.
7
×
10
−
9
, 7
.
7
×
10
−
9
, and 6
.
7
×
10
−
9
. We
see from Table XLIII that the value of
α
from adjustment
5 is consistent with the 2006 recommended value from ad-
justment 4 (the difference is 0.8
u
diff
), but its uncertainty
is about 20 times larger. Moreover, the resulting value
of
h
is the same as the recommended value.
Adjustment 6 only differs from adjustment 3 in that
it does not include the input data that yield the three
most accurate values of
h
, namely, the watt-balance mea-
surements of
K
2
J
R
K
, items
B
36
.
1-
B
36
.
3. The
u
r
of the
inferred values of
h
from these data, as they are used
in adjustment 3 (that is, after their uncertainties are
multiplied by the weighting factor 1.5), are 5
.
4
×
10
−
8
,
1
.
3
×
10
−
7
, and 3
.
0
×
10
−
7
. From Table XLIII, we see
that the value of
h
from adjustment 6 is consistent with
the 2006 recommended value from adjustment 4 (the dif-
ference is 1.4
u
diff
), but its uncertainty is well over 6 times
larger. Furthermore, the resulting value of
α
is the same
as the recommended value. Therefore adjustments 5 and
6 suggest that the less accurate input data are consistent
with the more accurate data, thereby providing a con-
sistency check on the 2006 recommended values of the
constants.
Adjustments 7-11
. These adjustments differ from ad-
justment 4, the ï¬nal adjustment, in the following ways.
In adjustment 7, the scattering-data input values for both
R
p
and
R
d
, items
A
48 and
A
49, are omitted; in adjust-
ment 8, only
R
p
is omitted, and in adjustment 9, only
R
d
is omitted; adjustment 10 includes only the hydro-
gen data, and adjustment 11 includes only the deuterium
data, but for both, the H-D isotope shift, item
A
47, is
omitted. Although a somewhat improved value of the
1S
1
/
2
-2S
1
/
2
hydrogen transition frequency and improve-
ments in the theory of H and D energy levels have become
available since the completion of the 2002 adjustment,
the value of
R
∞
, which is determined almost entirely by
these data, has changed very little. The values of
R
p
and
R
d
, which are also determined mainly by these data,
have changed by less than one third of their uncertainties.
The experimental and theoretical H and D data remain
highly consistent.
2. Test of the Josephson and quantum Hall effect relations
Investigation of the exactness of the relations
K
J
=
2
e/h
and
R
K
=
h/e
2
is carried out, as in CODATA-02,
by writing
K
J
=
2
e
h
(1 +
ε
J
) =
8
α
µ
0
ch
1
/
2
(1 +
ε
J
)
(372)
R
K
=
h
e
2
(1 +
ε
K
) =
µ
0
c
2
α
(1 +
ε
K
)
,
(373)
where
ε
J
and
ε
K
are unknown correction factors taken
to be additional adjusted constants determined by least-
squares calculations. Replacing the relations
K
J
= 2
e/h
and
R
K
=
h/e
2
with the generalizations in Eqs. (372)
and (373) in the analysis leading to the observational
equations in Table XL leads to the modiï¬ed observational
equations given in Table XLVI.
The results of seven different adjustments are pre-
sented in Table XLVII. In addition to the adjusted values
of
α
,
h
,
ε
J
, and
ε
K
, we also give the normalized residuals
r
i
of the four input data with the largest values of
|
r
i
|
:
V
m
(Si), item
B
53,
h/m
n
d
220
(
W04
), item
B
55,
d
220
(
NR3
),
item
B
39, and the NIST-89 value for
Γ
′
p
−
90
(lo), item
B
31
.
1. The residuals are included as additional indica-
tors of whether relaxing the assumption
K
J
= 2
e/h
and
R
K
=
h/e
2
reduces the disagreements among the data.
The adjusted value of
R
∞
is not included in Ta-
ble XLVII, because it remains essentially unchanged from
one adjustment to the next and equal to the 2006 recom-
mended value. An entry of 0 in the
ε
K
column means
that it is assumed that
R
K
=
h/e
2
in the correspond-
ing adjustment; similarly, an entry of 0 in the
ε
J
column
means that it is assumed that
K
J
= 2
e/h
in the corre-
sponding adjustment. The following comments apply to
the adjustments of Table XLVII.
Adjustment (i) is identical to adjustment 1 of Ta-
bles XLIII and XLIV in the previous section and is in-
cluded here simply for reference; all of the input data are
included and multiplicative weighting factors have not
been applied to any uncertainties. For this adjustment,
N
= 150,
M
= 79,
ν
= 71, and
χ
2
= 92
.
1.
The next three adjustments differ from adjustment (i)
in that in adjustment (ii) the relation
K
J
= 2
e/h
is re-
72
laxed, in adjustment (iii) the relation
R
K
=
h/e
2
is re-
laxed, and in adjustment (iv) both of the relations are
relaxed. For these three adjustments,
N
= 150,
M
= 80,
ν
= 70, and
χ
2
= 91
.
5;
N
= 150,
M
= 80,
ν
= 70, and
χ
2
= 91
.
3; and
N
= 150,
M
= 81,
ν
= 69, and
χ
2
= 90
.
4,
respectively.
It is clear from Table XLVII that there is no evidence
for the inexactness of either of the relations
K
J
= 2
e/h
or
R
K
=
h/e
2
. This conclusion is also true if instead of
taking adjustment 1 of Table XLIII as our starting point,
we had taken adjustment 2 in which the uncertainties of
the ï¬ve x-ray related data are multiplied by the factor
1.5. That is, none of the numbers in Table XLVII would
change signiï¬cantly, except
R
B
would be reduced from
1.14 to about 1.08. The reason adjustments (iii)-(vii)
summarized in Table XLVII give values of
Ç«
K
consistent
with zero within about 2 parts in 10
8
is mainly because
the value of alpha inferred from the mean of the ï¬ve
measured values of
R
K
under the assumption
R
K
=
h/e
2
,
which has
u
r
= 1
.
8
×
10
−
8
, agrees with the value of
α
with
u
r
= 7
.
0
×
10
−
10
inferred from the Harvard University
measured value of
a
e
.
Table XLVI and the uncertainties of the 2006 input
data indicate that the values of
Ç«
J
from adjustments (ii)
and (iv) are determined mainly by the input data for
the quantities
Γ
′
p
−
90
(lo) and
Γ
′
h
−
90
(lo) with observational
equations that depend on
Ç«
J
but not on
h
; and by the
input data for the quantities
Γ
′
p
−
90
(hi),
K
J
,
K
2
J
R
K
, and
F
90
, with observational equations that depend on both
Ç«
J
and
h
. Because the value of
h
in these least-squares
calculations arises primarily from the measured value of
the molar volume of silicon,
V
m
(Si), the values of
Ç«
J
in
adjustments (ii) and (iv) arise mainly from a combination
of individual values of
Ç«
J
that either depend on
V
m
(Si)
or on
Γ
′
p
−
90
(lo) and
Γ
′
h
−
90
(lo). It is therefore of interest
to repeat adjustment (iv), ï¬rst with
V
m
(Si) deleted but
with the
Γ
′
p
−
90
(lo) and
Γ
′
h
−
90
(lo) data included, and then
with the latter deleted but with
V
m
(Si) included. These
are, in fact, adjustments (v) and (vi) of Table XLVII.
In each of these adjustments, the absolute values of
Ç«
J
are comparable and signiï¬cantly larger than the un-
certainties, which are also comparable, but the values
have different signs. Consequently, when
V
m
(Si) and the
Γ
′
p
−
90
(lo) and
Γ
′
h
−
90
(lo) data are included at the same
time as in adjustment (iv), the result for
Ç«
J
is consistent
with zero.
The values of
Ç«
J
from adjustments (v) and (vi) reflect
some of the inconsistencies among the data: the disagree-
ment of the values of
h
implied by
V
m
(Si) and
K
2
J
R
K
when it is assumed that the relations
K
J
= 2
e/h
and
R
K
=
h/e
2
are exact; and the disagreement of the values
of
α
implied by the electron magnetic moment anomaly
a
e
and by
Γ
′
p
−
90
(lo) and
Γ
′
h
−
90
(lo) under the same as-
sumption.
In adjustment (vii), the problematic input data for
V
m
(Si),
Γ
′
p
−
90
(lo), and
Γ
′
h
−
90
(lo) are simultaneously
deleted from the calculation. Then the value of
Ç«
J
arises
mainly from the input data for
Γ
′
p
−
90
(hi),
K
J
,
K
2
J
R
K
,
and
F
90
. Like adjustment (iv), adjustment (vii) shows
that
Ç«
J
is consistent with zero, although not within 8
parts in 10
8
but within 7 parts in 10
7
. However, adjust-
ment (vii) has the advantage of being based on consistent
data.
The comparatively narrow range of values of alpha in
Table XLVII is due to the fact that the input data that
mainly determine alpha do not depend on the Josephson
or quantum Hall effects. This is not the case for the input
data that primarily determine
h
, hence the values of
h
vary over a wide range.
73
TABLE XXXVI Values of
A
r
(e) implied by the input data in Table XXX in order of increasing standard uncertainty.
Primary
Item
Identiï¬cation
Sec. and Eq.
A
r
(e)
Relative standard
source
number
uncertainty
u
r
f
s
(C)
/f
c
(C)
B
16
GSI-02
V.C.2.a (177)
0
.
000 548 579 909 32(29)
5
.
2
×
10
−
10
f
s
(O)
/f
c
(O)
B
17
GSI-02
V.C.2.b (181)
0
.
000 548 579 909 58(42)
7
.
6
×
10
−
10
∆
ν
¯
p He
+
C
1
−
C
24
JINR/CERN-06
IV.B.3 (74)
0
.
000 548 579 908 81(91)
1
.
7
×
10
−
9
A
r
(e)
B
9
UWash-95
III.C (5)
0
.
000 548 579 9111(12)
2
.
1
×
10
−
9
74
TABLE XXXVII The 28 adjusted constants (variables) used
in the least-squares multivariate analysis of the Rydberg-
constant data given in Table XXVIII. These adjusted con-
stants appear as arguments of the functions on the right-hand
side of the observational equations of Table XXXVIII. The
notation for hydrogenic energy levels
E
X
(
n
L
j
) and for addi-
tive corrections
δ
X
(
n
L
j
) in this table have the same meaning
as the notations
E
X
n
L
j
and
δ
X
n
L
j
in Sec. IV.A.1.l.
Adjusted constant
Symbol
Rydberg constant
R
∞
bound-state proton rms charge radius
R
p
bound-state deuteron rms charge radius
R
d
additive correction to
E
H
(1S
1
/
2
)
/h
δ
H
(1S
1
/
2
)
additive correction to
E
H
(2S
1
/
2
)
/h
δ
H
(2S
1
/
2
)
additive correction to
E
H
(3S
1
/
2
)
/h
δ
H
(3S
1
/
2
)
additive correction to
E
H
(4S
1
/
2
)
/h
δ
H
(4S
1
/
2
)
additive correction to
E
H
(6S
1
/
2
)
/h
δ
H
(6S
1
/
2
)
additive correction to
E
H
(8S
1
/
2
)
/h
δ
H
(8S
1
/
2
)
additive correction to
E
H
(2P
1
/
2
)
/h
δ
H
(2P
1
/
2
)
additive correction to
E
H
(4P
1
/
2
)
/h
δ
H
(4P
1
/
2
)
additive correction to
E
H
(2P
3
/
2
)
/h
δ
H
(2P
3
/
2
)
additive correction to
E
H
(4P
3
/
2
)
/h
δ
H
(4P
3
/
2
)
additive correction to
E
H
(8D
3
/
2
)
/h
δ
H
(8D
3
/
2
)
additive correction to
E
H
(12D
3
/
2
)
/h
δ
H
(12D
3
/
2
)
additive correction to
E
H
(4D
5
/
2
)
/h
δ
H
(4D
5
/
2
)
additive correction to
E
H
(6D
5
/
2
)
/h
δ
H
(6D
5
/
2
)
additive correction to
E
H
(8D
5
/
2
)
/h
δ
H
(8D
5
/
2
)
additive correction to
E
H
(12D
5
/
2
)
/h
δ
H
(12D
5
/
2
)
additive correction to
E
D
(1S
1
/
2
)
/h
δ
D
(1S
1
/
2
)
additive correction to
E
D
(2S
1
/
2
)
/h
δ
D
(2S
1
/
2
)
additive correction to
E
D
(4S
1
/
2
)
/h
δ
D
(4S
1
/
2
)
additive correction to
E
D
(8S
1
/
2
)
/h
δ
D
(8S
1
/
2
)
additive correction to
E
D
(8D
3
/
2
)
/h
δ
D
(8D
3
/
2
)
additive correction to
E
D
(12D
3
/
2
)
/h
δ
D
(12D
3
/
2
)
additive correction to
E
D
(4D
5
/
2
)
/h
δ
D
(4D
5
/
2
)
additive correction to
E
D
(8D
5
/
2
)
/h
δ
D
(8D
5
/
2
)
additive correction to
E
D
(12D
5
/
2
)
/h
δ
D
(12D
5
/
2
)
75
TABLE XXXVIII Observational equations that express the input data related to
R
∞
in Table XXVIII as functions of the
adjusted constants in Table XXXVII. The numbers in the ï¬rst column correspond to the numbers in the ï¬rst column of
Table XXVIII. The expressions for the energy levels of hydrogenic atoms are discussed in Sec. IV.A.1. As pointed out in
Sec. IV.A.1.l,
E
X
(
n
L
j
)
/h
is in fact proportional to
cR
∞
and independent of
h
, hence
h
is not an adjusted constant in these
equations. The notation for hydrogenic energy levels
E
X
(
n
L
j
) and for additive corrections
δ
X
(
n
L
j
) in this table have the same
meaning as the notations
E
X
n
L
j
and
δ
X
n
L
j
in Sec. IV.A.1.l. See Sec. XII.B for an explanation of the symbol
.
=.
Type of input
Observational equation
datum
A
1–
A
16
δ
H
(
n
L
j
)
.
=
δ
H
(
n
L
j
)
A
17–
A
25
δ
D
(
n
L
j
)
.
=
δ
D
(
n
L
j
)
A
26–
A
31
ν
H
(
n
1
L
1
j
1
−
n
2
L
2
j
2
)
.
=
ˆ
E
H
`
n
2
L
2
j
2
;
R
∞
, α, A
r
(e)
, A
r
(p)
, R
p
, δ
H
(
n
2
L
2
j
2
)
´
A
38
, A
39
−
E
H
`
n
1
L
1
j
1
;
R
∞
, α, A
r
(e)
, A
r
(p)
, R
p
, δ
H
(
n
1
L
1
j
1
)
´˜
/h
A
32–
A
37
ν
H
(
n
1
L
1
j
1
−
n
2
L
2
j
2
)
−
1
4
ν
H
(
n
3
L
3
j
3
−
n
4
L
4
j
4
)
.
=
n
E
H
`
n
2
L
2
j
2
;
R
∞
, α, A
r
(e)
, A
r
(p)
, R
p
, δ
H
(
n
2
L
2
j
2
)
´
−
E
H
`
n
1
L
1
j
1
;
R
∞
, α, A
r
(e)
, A
r
(p)
, R
p
, δ
H
(
n
1
L
1
j
1
)
´
−
1
4
ˆ
E
H
`
n
4
L
4
j
4
;
R
∞
, α, A
r
(e)
, A
r
(p)
, R
p
, δ
H
(
n
4
L
4
j
4
)
´
−
E
H
`
n
3
L
3
j
3
;
R
∞
, α, A
r
(e)
, A
r
(p)
, R
p
, δ
H
(
n
3
L
3
j
3
)
´˜
o
/h
A
40–
A
44
ν
D
(
n
1
L
1
j
1
−
n
2
L
2
j
2
)
.
=
ˆ
E
D
`
n
2
L
2
j
2
;
R
∞
, α, A
r
(e)
, A
r
(d)
, R
d
, δ
D
(
n
2
L
2
j
2
)
´
−
E
D
`
n
1
L
1
j
1
;
R
∞
, α, A
r
(e)
, A
r
(d)
, R
d
, δ
D
(
n
1
L
1
j
1
)
´˜
/h
A
45–
A
46
ν
D
(
n
1
L
1
j
1
−
n
2
L
2
j
2
)
−
1
4
ν
D
(
n
3
L
3
j
3
−
n
4
L
4
j
4
)
.
=
n
E
D
`
n
2
L
2
j
2
;
R
∞
, α, A
r
(e)
, A
r
(d)
, R
d
, δ
D
(
n
2
L
2
j
2
)
´
−
E
D
`
n
1
L
1
j
1
;
R
∞
, α, A
r
(e)
, A
r
(d)
, R
d
, δ
D
(
n
1
L
1
j
1
)
´
−
1
4
ˆ
E
D
`
n
4
L
4
j
4
;
R
∞
, α, A
r
(e)
, A
r
(d)
, R
d
, δ
D
(
n
4
L
4
j
4
)
´
−
E
D
`
n
3
L
3
j
3
;
R
∞
, α, A
r
(e)
, A
r
(d)
, R
d
, δ
D
(
n
3
L
3
j
3
)
´˜
o
/h
A
47
ν
D
(1S
1
/
2
−
2S
1
/
2
)
−
ν
H
(1S
1
/
2
−
2S
1
/
2
)
.
=
n
E
D
`
2S
1
/
2
;
R
∞
, α, A
r
(e)
, A
r
(d)
, R
d
, δ
D
(2S
1
/
2
)
´
−
E
D
`
1S
1
/
2
;
R
∞
, α, A
r
(e)
, A
r
(d)
, R
d
, δ
D
(1S
1
/
2
)
´
−
ˆ
E
H
`
2S
1
/
2
;
R
∞
, α, A
r
(e)
, A
r
(p)
, R
p
, δ
H
(2S
1
/
2
)
´
−
E
H
`
1S
1
/
2
;
R
∞
, α, A
r
(e)
, A
r
(p)
, R
p
, δ
H
(1S
1
/
2
)
´˜
o
/h
A
48
R
p
.
=
R
p
A
49
R
d
.
=
R
d
76
TABLE XXXIX The 39 adjusted constants (variables) used
in the least-squares multivariate analysis of the input data in
Table XXX. These adjusted constants appear as arguments
of the functions on the right-hand side of the observational
equations of Table XL.
Adjusted constant
Symbol
electron relative atomic mass
A
r
(e)
proton relative atomic mass
A
r
(p)
neutron relative atomic mass
A
r
(n)
deuteron relative atomic mass
A
r
(d)
triton relative atomic mass
A
r
(t)
helion relative atomic mass
A
r
(h)
alpha particle relative atomic mass
A
r
(
α
)
16
O
7+
relative atomic mass
A
r
(
16
O
7+
)
87
Rb relative atomic mass
A
r
(
87
Rb)
133
Cs relative atomic mass
A
r
(
133
Cs)
ï¬ne-structure constant
α
additive correction to
a
e
(th)
δ
e
additive correction to
a
µ
(th)
δ
µ
additive correction to
g
C
(th)
δ
C
additive correction to
g
O
(th)
δ
O
electron-proton magnetic moment ratio
µ
e
−
/µ
p
deuteron-electron magnetic moment ratio
µ
d
/µ
e
−
triton-proton magnetic moment ratio
µ
t
/µ
p
shielding difference of d and p in HD
σ
dp
shielding difference of t and p in HT
σ
tp
electron to shielded proton
magnetic moment ratio
µ
e
−
/µ
′
p
shielded helion to shielded proton
magnetic moment ratio
µ
′
h
/µ
′
p
neutron to shielded proton
magnetic moment ratio
µ
n
/µ
′
p
electron-muon mass ratio
m
e
/m
µ
additive correction to ∆
ν
Mu
(th)
δ
Mu
Planck constant
h
molar gas constant
R
copper K
α
1
x unit
xu(CuK
α
1
)
molybdenum K
α
1
x unit
xu(MoK
α
1
)
Ëš
angstrom star
Ëš
A
∗
d
220
of Si crystal ILL
d
220
(
ILL
)
d
220
of Si crystal N
d
220
(
N
)
d
220
of Si crystal WASO 17
d
220
(
W17
)
d
220
of Si crystal WASO 04
d
220
(
W04
)
d
220
of Si crystal WASO 4.2a
d
220
(
W4
.
2a
)
d
220
of Si crystal MO
∗
d
220
(
MO
∗
)
d
220
of Si crystal NR3
d
220
(
NR3
)
d
220
of Si crystal NR4
d
220
(
NR4
)
d
220
of an ideal Si crystal
d
220
77
TABLE XL Observational equations that express the input data in Table XXX as functions of the adjusted constants in
Table XXXIX. The numbers in the ï¬rst column correspond to the numbers in the ï¬rst column of Table XXX. For simplicity,
the lengthier functions are not explicitly given. See Sec. XII.B for an explanation of the symbol
.
=.
Type of input
Observational equation
datum
Sec.
B
1
A
r
(
1
H)
.
=
A
r
(p) +
A
r
(e)
−
E
b
(
1
H)
/m
u
c
2
III.B
B
2
A
r
(
2
H)
.
=
A
r
(d) +
A
r
(e)
−
E
b
(
2
H)
/m
u
c
2
III.B
B
3
A
r
(
3
H)
.
=
A
r
(t) +
A
r
(e)
−
E
b
(
3
H)
/m
u
c
2
III.B
B
4
A
r
(
3
He)
.
=
A
r
(h) + 2
A
r
(e)
−
E
b
(
3
He)
/m
u
c
2
III.B
B
5
A
r
(
4
He)
.
=
A
r
(
α
) + 2
A
r
(e)
−
E
b
(
4
He)
/m
u
c
2
III.B
B
6
A
r
(
16
O)
.
=
A
r
(
16
O
7+
) + 7
A
r
(e)
−
ˆ
E
b
(
16
O)
−
E
b
(
16
O
7+
)
˜
/m
u
c
2
V.C.2.b
B
7
A
r
(
87
Rb)
.
=
A
r
(
87
Rb)
B
8
A
r
(
133
Cs)
.
=
A
r
(
133
Cs)
B
9
A
r
(e)
.
=
A
r
(e)
B
10
δ
e
.
=
δ
e
B
11
a
e
.
=
a
e
(
α, δ
e
)
V.A.1
B
12
δ
µ
.
=
δ
µ
B
13
R
.
=
−
a
µ
(
α, δ
µ
)
1 +
a
e
(
α, δ
e
)
m
e
m
µ
µ
e
−
µ
p
V.B.2
B
14
δ
C
.
=
δ
C
B
15
δ
O
.
=
δ
O
B
16
f
s
`
12
C
5+
´
f
c
`
12
C
5+
´
.
=
−
g
C
(
α, δ
C
)
10
A
r
(e)
"
12
−
5
A
r
(e) +
E
b
`
12
C
´
−
E
b
`
12
C
5+
´
m
u
c
2
#
V.C.2.a
B
17
f
s
`
16
O
7+
´
f
c
`
16
O
7+
´
.
=
−
g
O
(
α, δ
O
)
14
A
r
(e)
A
r
(
16
O
7+
)
V.C.2.b
B
18
µ
e
−
(H)
µ
p
(H)
.
=
g
e
−
(H)
g
e
−
„
g
p
(H)
g
p
«
−
1
µ
e
−
µ
p
VI.A.2.a
B
19
µ
d
(D)
µ
e
−
(D)
.
=
g
d
(D)
g
d
„
g
e
−
(D)
g
e
−
«
−
1
µ
d
µ
e
−
VI.A.2.b
B
20
µ
p
(HD)
µ
d
(HD)
.
= [1 +
σ
dp
]
µ
p
µ
e
−
µ
e
−
µ
d
VI.A.2.c
B
21
σ
dp
.
=
σ
dp
B
22
µ
t
(HT)
µ
p
(HT)
.
= [1
−
σ
tp
]
µ
t
µ
p
VI.A.2.c
B
23
σ
tp
.
=
σ
tp
B
24
µ
e
−
(H)
µ
′
p
.
=
g
e
−
(H)
g
e
−
µ
e
−
µ
′
p
VI.A.2.d
B
25
µ
′
h
µ
′
p
.
=
µ
′
h
µ
′
p
B
26
µ
n
µ
′
p
.
=
µ
n
µ
′
p
78
TABLE XL
(Continued).
Observational equations that express the input data in Table XXX as functions of the adjusted
constants in Table XXXIX. The numbers in the ï¬rst column correspond to the numbers in the ï¬rst column of Table XXX. For
simplicity, the lengthier functions are not explicitly given. See Sec. XII.B for an explanation of the symbol
.
=.
Type of input
Observational equation
datum
Sec.
B
27
δ
Mu
.
=
δ
Mu
B
28
∆
ν
Mu
.
= ∆
ν
Mu
R
∞
, α, m
e
m
µ
, δ
µ
, δ
Mu
!
VI.B.1
B
29
, B
30
ν
(
f
p
)
.
=
ν
f
p
;
R
∞
, α, m
e
m
µ
,
µ
e
−
µ
p
, δ
e
, δ
µ
, δ
Mu
!
VI.B
B
31
Γ
′
p
−
90
(lo)
.
=
−
K
J
−
90
R
K
−
90
[1 +
a
e
(
α, δ
e
)]
α
3
2
µ
0
R
∞
µ
e
−
µ
′
p
!
−
1
VII.A.1
B
32
Γ
′
h
−
90
(lo)
.
=
K
J
−
90
R
K
−
90
[1 +
a
e
(
α, δ
e
)]
α
3
2
µ
0
R
∞
µ
e
−
µ
′
p
!
−
1
µ
′
h
µ
′
p
VII.A.1
B
33
Γ
′
p
−
90
(hi)
.
=
−
c
[1 +
a
e
(
α, δ
e
)]
α
2
K
J
−
90
R
K
−
90
R
∞
h
µ
e
−
µ
′
p
!
−
1
VII.A.2
B
34
R
K
.
=
µ
0
c
2
α
VII.B
B
35
K
J
.
=
„
8
α
µ
0
ch
«
1
/
2
VII.C
B
36
K
2
J
R
K
.
=
4
h
VII.D
B
37
F
90
.
=
cM
u
A
r
(e)
α
2
K
J
−
90
R
K
−
90
R
∞
h
VII.E
B
38-
B
40
d
220
(
X
)
.
=
d
220
(
X
)
B
41-
B
52
d
220
(
X
)
d
220
(
Y
)
−
1
.
=
d
220
(
X
)
d
220
(
Y
)
−
1
B
53
V
m
(Si)
.
=
√
2
cM
u
A
r
(e)
α
2
d
3
220
R
∞
h
VIII.B
B
54
λ
meas
d
220
(
ILL
)
.
=
α
2
A
r
(e)
R
∞
d
220
(
ILL
)
A
r
(n) +
A
r
(p)
[
A
r
(n) +
A
r
(p)]
2
−
A
2
r
(d)
VIII.C
B
55
h
m
n
d
220
(
W04
)
.
=
A
r
(e)
A
r
(n)
cα
2
2
R
∞
d
220
(
W04
)
VIII.D.1
B
56
, B
57
h
m
(
X
)
.
=
A
r
(e)
A
r
(
X
)
cα
2
2
R
∞
VIII.D
B
58
R
.
=
R
B
59
, B
62
λ
(CuK
α
1
)
d
220
(
X
)
.
=
1 537
.
400 xu(CuK
α
1
)
d
220
(
X
)
XI.A
B
60
λ
(WK
α
1
)
d
220
(
N
)
.
=
0
.
209 010 0 Ëš
A
∗
d
220
(
N
)
XI.A
B
61
λ
(MoK
α
1
)
d
220
(
N
)
.
=
707
.
831 xu(MoK
α
1
)
d
220
(
N
)
XI.A
79
TABLE XLI The 12 adjusted constants (variables) relevant
to the antiprotonic helium data given in Table XXXII. These
adjusted constants appear as arguments of the theoretical ex-
pressions on the right-hand side of the observational equations
of Table XLII.
Transition
Adjusted constant
¯
p
4
He
+
: (32
,
31)
→
(31
,
30)
δ
¯
p
4
He
+
(32
,
31: 31
,
30)
¯
p
4
He
+
: (35
,
33)
→
(34
,
32)
δ
¯
p
4
He
+
(35
,
33: 34
,
32)
¯
p
4
He
+
: (36
,
34)
→
(35
,
33)
δ
¯
p
4
He
+
(36
,
34: 35
,
33)
¯
p
4
He
+
: (37
,
34)
→
(36
,
33)
δ
¯
p
4
He
+
(37
,
34: 36
,
33)
¯
p
4
He
+
: (39
,
35)
→
(38
,
34)
δ
¯
p
4
He
+
(39
,
35: 38
,
34)
¯
p
4
He
+
: (40
,
35)
→
(39
,
34)
δ
¯
p
4
He
+
(40
,
35: 39
,
34)
¯
p
4
He
+
: (37
,
35)
→
(38
,
34)
δ
¯
p
4
He
+
(37
,
35: 38
,
34)
¯
p
3
He
+
: (32
,
31)
→
(31
,
30)
δ
¯
p
3
He
+
(32
,
31: 31
,
30)
¯
p
3
He
+
: (34
,
32)
→
(33
,
31)
δ
¯
p
3
He
+
(34
,
32: 33
,
31)
¯
p
3
He
+
: (36
,
33)
→
(35
,
32)
δ
¯
p
3
He
+
(36
,
33: 35
,
32)
¯
p
3
He
+
: (38
,
34)
→
(37
,
33)
δ
¯
p
3
He
+
(38
,
34: 37
,
33)
¯
p
3
He
+
: (36
,
34)
→
(37
,
33)
δ
¯
p
3
He
+
(36
,
34: 37
,
33)
80
TABLE XLII Observational equations that express the input data related to antiprotonic helium in Table XXXII as functions
of adjusted constants in Tables XXXIX and XLI. The numbers in the ï¬rst column correspond to the numbers in the ï¬rst
column of Table XXXII. Deï¬nitions of the symbols and values of the parameters in these equations are given in Sec. IV.B. See
Sec. XII.B for an explanation of the symbol
.
=.
Type of input
Observational equation
datum
C
1–
C
7
δ
¯
p
4
He
+
(
n, l
:
n
′
, l
′
)
.
=
δ
¯
p
4
He
+
(
n, l
:
n
′
, l
′
)
C
8–
C
12
δ
¯
p
3
He
+
(
n, l
:
n
′
, l
′
)
.
=
δ
¯
p
3
He
+
(
n, l
:
n
′
, l
′
)
C
13–
C
19
ν
¯
p
4
He
+
(
n, l
:
n
′
, l
′
)
.
=
ν
(0)
¯
p
4
He
+
(
n, l
:
n
′
, l
′
) +
a
¯
p
4
He
+
(
n, l
:
n
′
, l
′
)
"
„
A
r
(e)
A
r
(p)
«
(0)
„
A
r
(p)
A
r
(e)
«
−
1
#
+
b
¯
p
4
He
+
(
n, l
:
n
′
, l
′
)
"
„
A
r
(e)
A
r
(
α
)
«
(0)
„
A
r
(
α
)
A
r
(e)
«
−
1
#
+
δ
¯
p
4
He
+
(
n, l
:
n
′
, l
′
)
C
20–
C
24
ν
¯
p
3
He
+
(
n, l
:
n
′
, l
′
)
.
=
ν
(0)
¯
p
3
He
+
(
n, l
:
n
′
, l
′
) +
a
¯
p
3
He
+
(
n, l
:
n
′
, l
′
)
"
„
A
r
(e)
A
r
(p)
«
(0)
„
A
r
(p)
A
r
(e)
«
−
1
#
+
b
¯
p
3
He
+
(
n, l
:
n
′
, l
′
)
"
„
A
r
(e)
A
r
(h)
«
(0)
„
A
r
(h)
A
r
(e)
«
−
1
#
+
δ
¯
p
3
He
+
(
n, l
:
n
′
, l
′
)
TABLE XLIII Summary of the results of some of the least-squares adjustments used to analyze all of the input data given in
Tables XXVIII, XXIX, XXX, and XXXI. The values of
α
and
h
are those obtained in the adjustment,
N
is the number of
input data,
M
is the number of adjusted constants,
ν
=
N
−
M
is the degrees of freedom, and
R
B
=
p
χ
2
/ν
is the Birge ratio.
See the text for an explanation and discussion of each adjustment, but in brief, 1 is all the data; 2 is 1 with the uncertainties
of the key x-ray/silicon data multiplied by 1.5; 3 is 2 with the uncertainties of the key electrical data also multiplied by 1.5; 4
is the ï¬nal adjustment from which the 2006 recommended values are obtained and is 3 with the input data with low weights
deleted; 5 is 3 with the four data that provide the most accurate values of
α
deleted; and 6 is 3 with the three data that provide
the most accurate values of
h
deleted.
Adj.
N
M
ν
χ
2
R
B
α
−
1
u
r
(
α
−
1
)
h
/(J s)
u
r
(
h
)
1 150
79
71
92.1
1.14
137
.
035 999 687(93)
6
.
8
×
10
−
10
6
.
626 068 96(22)
×
10
−
34
3
.
4
×
10
−
8
2 150
79
71
82.0
1.07
137
.
035 999 682(93)
6
.
8
×
10
−
10
6
.
626 068 96(22)
×
10
−
34
3
.
4
×
10
−
8
3 150
79
71
77.5
1.04
137
.
035 999 681(93)
6
.
8
×
10
−
10
6
.
626 068 96(33)
×
10
−
34
5
.
0
×
10
−
8
4 135
78
57
65.0
1.07
137
.
035 999 679(94)
6
.
8
×
10
−
10
6
.
626 068 96(33)
×
10
−
34
5
.
0
×
10
−
8
5 144
77
67
72.9
1.04
137
.
036 0012(19)
1
.
4
×
10
−
8
6
.
626 068 96(33)
×
10
−
34
5
.
0
×
10
−
8
6 147
79
68
75.4
1.05
137
.
035 999 680(93)
6
.
8
×
10
−
10
6
.
626 0719(21)
×
10
−
34
3
.
2
×
10
−
7
TABLE XLIV Normalized residuals
r
i
and self-sensitivity coefficients
S
c
that result from the six least-squares adjustments
summarized in Table XLIII for the four input data whose absolute values of
r
i
in Adj. 1 exceed 1.50.
S
c
is a measure of how
the least-squares estimated value of a given type of input datum depends on a particular measured or calculated value of that
type of datum; see Appendix E of CODATA-98. See the text for an explanation and discussion of each adjustment; brief
explanations are given at the end of the caption to the previous table.
Item
Input
Identiï¬cation
Adj. 1
Adj. 2
Adj. 3
Adj. 4
Adj. 5
Adj. 6
number
quantity
r
i
S
c
r
i
S
c
r
i
S
c
r
i
S
c
r
i
S
c
r
i
S
c
B
53
V
m
(Si)
N/P/I-05
−
2
.
82 0
.
065
−
2
.
68 0
.
085
−
1
.
86 0
.
046
−
1
.
86 0
.
047
−
1
.
79 0
.
053
−
0
.
86 0
.
556
B
55
h/m
n
d
220
(
W04
)
PTB-99
−
2
.
71 0
.
155
−
2
.
03 0
.
118
−
1
.
89 0
.
121
−
1
.
89 0
.
121
−
1
.
57 0
.
288
−
1
.
82 0
.
123
B
39
d
220
(
NR3
)
NMIJ-04
2
.
37 0
.
199
1
.
86 0
.
145
1
.
74 0
.
148
1
.
74 0
.
148
1
.
78 0
.
151
−
1
.
00 0
.
353
B
31
.
1
Γ
′
p
−
90
(lo)
NIST-89
2
.
31 0
.
010
2
.
30 0
.
010
2
.
30 0
.
010
deleted
2
.
60 0
.
143
2
.
30 0
.
010
81
TABLE XLV Summary of the results of some of the least-squares adjustments used to analyze the input data related to
R
∞
.
The values of
R
∞
,
R
p
, and
R
d
are those obtained in the indicated adjustment,
N
is the number of input data,
M
is the
number of adjusted constants,
ν
=
N
−
M
is the degrees of freedom, and
R
B
=
p
χ
2
/ν
is the Birge ratio. See the text for an
explanation and discussion of each adjustment, but in brief, 4 is the ï¬nal adjustment; 7 is 4 with the input data for
R
p
and
R
d
deleted; 8 is 4 with just the
R
p
datum deleted; 9 is 4 with just the
R
d
datum deleted; 10 is 4 but with only the hydrogen
data included; and 11 is 4 but with only the deuterium data included.
Adj.
N
M
ν
χ
2
R
B
R
∞
/
m
−
1
u
r
(
R
∞
)
R
p
/fm
R
d
/fm
4
135
78
57
65.0
1.07
10 973 731
.
568 527(73)
6
.
6
×
10
−
12
0
.
8768(69)
2
.
1402(28)
7
133
78
55
63.0
1.07
10 973 731
.
568 518(82)
7
.
5
×
10
−
12
0
.
8760(78)
2
.
1398(32)
8
134
78
56
63.8
1.07
10 973 731
.
568 495(78)
7
.
1
×
10
−
12
0
.
8737(75)
2
.
1389(30)
9
134
78
56
63.9
1.07
10 973 731
.
568 549(76)
6
.
9
×
10
−
12
0
.
8790(71)
2
.
1411(29)
10
117
68
49
60.8
1.11
10 973 731
.
568 562(85)
7
.
8
×
10
−
12
0
.
8802(80)
11
102
61
41
54.7
1.16
10 973 731
.
568 39(13)
1
.
1
×
10
−
11
2
.
1286(93)
TABLE XLVI Generalized observational equations that express input data
B
31-
B
37 in Table XXX as functions of the adjusted
constants in Tables XXXIX and XXXVII with the additional adjusted constants
ε
J
and
ε
K
as given in Eqs. (372) and (373).
The numbers in the ï¬rst column correspond to the numbers in the ï¬rst column of Table XXX. For simplicity, the lengthier
functions are not explicitly given. See Sec. XII.B for an explanation of the symbol
.
=.
Type of input
Generalized observational equation
datum
B
31
∗
Γ
′
p
−
90
(lo)
.
=
−
K
J
−
90
R
K
−
90
[1 +
a
e
(
α, δ
e
)]
α
3
2
µ
0
R
∞
(1 +
ε
J
)(1 +
ε
K
)
µ
e
−
µ
′
p
!
−
1
B
32
∗
Γ
′
h
−
90
(lo)
.
=
K
J
−
90
R
K
−
90
[1 +
a
e
(
α, δ
e
)]
α
3
2
µ
0
R
∞
(1 +
ε
J
)(1 +
ε
K
)
µ
e
−
µ
′
p
!
−
1
µ
′
h
µ
′
p
B
33
∗
Γ
′
p
−
90
(hi)
.
=
−
c
[1 +
a
e
(
α, δ
e
)]
α
2
K
J
−
90
R
K
−
90
R
∞
h
(1 +
ε
J
)(1 +
ε
K
)
µ
e
−
µ
′
p
!
−
1
B
34
∗
R
K
.
=
µ
0
c
2
α
(1 +
ε
K
)
B
35
∗
K
J
.
=
„
8
α
µ
0
ch
«
1
/
2
(1 +
ε
J
)
B
36
∗
K
2
J
R
K
.
=
4
h
(1 +
ε
J
)
2
(1 +
ε
K
)
B
37
∗
F
90
.
=
cM
u
A
r
(e)
α
2
K
J
−
90
R
K
−
90
R
∞
h
(1 +
ε
J
)(1 +
ε
K
)
B
62
∗
ε
J
.
=
ε
J
B
63
∗
ε
K
.
=
ε
K
82
TABLE XLVII Summary of the results of several least-squares adjustments carried out to investigate the effect of assuming
the relations for
K
J
and
R
K
given in Eqs. (372) and (373). The values of
α
,
h
,
ε
K
, and
ε
J
are those obtained in the indicated
adjustments. The quantity
R
B
=
p
χ
2
/ν
is the Birge ratio and
r
i
is the normalized residual of the indicated input datum (see
Table XXX). These four data have the largest
|
r
i
|
of all the input data and are the only data in Adj. (i) with
|
r
i
|
>
1
.
50. See
the text for an explanation and discussion of each adjustment, but in brief, (i) assumes
K
J
= 2
e/h
and
R
K
=
h/e
2
and uses all
the data; (ii) is (i) with the relation
K
J
= 2
e/h
relaxed; (iii) is (i) with the relation
R
K
=
h/e
2
relaxed; (iv) is (i) with both
relations relaxed; (v) is (iv) with the
V
m
(Si) datum deleted; (vi) is (iv) with the
Γ
′
p
−
90
(lo) and
Γ
′
h
−
90
(lo) data deleted; and (vii)
is (iv) with the
V
m
(Si),
Γ
′
p
−
90
(lo), and
Γ
′
h
−
90
(lo) data deleted.
Adj.
R
B
α
−
1
h
/(J s)
ε
K
ε
J
r
B
53
r
B
55
r
B
39
r
B
31
.
1
(i)
1.14
137
.
035 999 687(93)
6
.
626 068 96(22)
×
10
−
34
0
0
−
2
.
82
−
2
.
71 2
.
37
2
.
31
(ii)
1.14
137
.
035 999 688(93)
6
.
626 0682(10)
×
10
−
34
0
−
61(79)
×
10
−
9
−
3
.
22
−
2
.
75 2
.
39
1
.
77
(iii)
1.14
137
.
035 999 683(93)
6
.
626 069 06(25)
×
10
−
34
16(18)
×
10
−
9
0
−
2
.
77
−
2
.
71 2
.
36
2
.
45
(iv)
1.14
137
.
035 999 685(93)
6
.
626 0681(11)
×
10
−
34
20(18)
×
10
−
9
−
77(80)
×
10
−
9
−
3
.
27
−
2
.
75 2
.
39
1
.
79
(v)
1.05
137
.
035 999 686(93)
6
.
626 0653(13)
×
10
−
34
23(18)
×
10
−
9
−
281(95)
×
10
−
9
deleted
−
2
.
45 2
.
19
0
.
01
(vi)
1.05
137
.
035 999 686(93)
6
.
626 0744(19)
×
10
−
34
24(18)
×
10
−
9
407(143)
×
10
−
9
−
0
.
05
−
2
.
45 2
.
19 deleted
(vii) 1.06
137
.
035 999 686(93)
6
.
626 0722(95)
×
10
−
34
24(18)
×
10
−
9
238(720)
×
10
−
9
deleted
−
2
.
45 2
.
19 deleted
83
XIII. THE 2006 CODATA RECOMMENDED VALUES
A. Calculational details
As indicated in Sec. XII.B, the 2006 recommended
values of the constants are based on adjustment 4 of
Tables XLIII to XLV. This adjustment is obtained by
(i) deleting 15 items from the originally considered 150
items of input data of Tables XXVIII, XXX, and XXXII,
namely, items
B
8,
B
31
.
1-
B
35
.
2,
B
37, and
B
56, because
of their low weight (self sensitivity coefficient
S
c
<
0
.
01);
and (ii) weighting the uncertainties of the nine input data
B
36
.
1-
B
36
.
3,
B
38
.
1-
B
40,
B
53, and
B
55 by the multi-
plicative factor 1.5 in order to reduce the absolute values
of their normalized residuals
|
r
i
|
to less than 2. The cor-
relation coefficients of the data, as given in Tables XXIX,
XXXI, and XXXIII, are also taken into account. The
135 ï¬nal input data are expressed in terms of the 78 ad-
justed constants of Tables XXXVII, XXXIX, and XLI,
corresponding to
N
−
M
=
ν
= 57 degrees of freedom.
Because
h/m
(
133
Cs), item
B
56, has been deleted as an
input datum due to its low weight,
A
r
(
133
Cs), item
B
8,
has also been deleted as an input datum and as an ad-
justed constant.
For the ï¬nal adjustment,
χ
2
= 65
.
0,
p
χ
2
/ν
=
R
B
=
1
.
04, and
Q
(65
.
0
|
57) = 0
.
22, where
Q
(
χ
2
|
ν
) is the proba-
bility that the observed value of
χ
2
for degrees of freedom
ν
would have exceeded that observed value (see Appendix
E of CODATA-98). Each input datum in the ï¬nal ad-
justment has
S
c
>
0
.
01, or is a subset of the data of
an experiment that provides an input datum or input
data with
S
c
>
0
.
01. Not counting such input data with
S
c
<
0
.
01, the six input data with the largest
|
r
i
|
are
B
55,
B
53,
B
39,
C
18,
B
11
.
1, and
B
9; their values of
r
i
are
−
1
.
89,
−
1
.
86, 1
.
74,
−
1
.
73, 1
.
69, and 1
.
45, respec-
tively. The next largest
r
i
are 1
.
22 and 1
.
11.
The output of the ï¬nal adjustment is the set of best
estimated values, in the least-squares sense, of the 78
adjusted constants and their variances and covariances.
Together with (i) those constants that have exact val-
ues such as
µ
0
and
c
; (ii) the value of
G
obtained in
Sec. X; and (iii) the values of
m
Ï„
,
G
F
, and sin
2
θ
W
given
in Sec. XI.B, all of the 2006 recommended values, includ-
ing their uncertainties, are obtained from the 78 adjusted
constants. How this is done can be found in Sec. V.B of
CODATA-98.
B. Tables of values
The 2006 CODATA recommended values of the basic
constants and conversion factors of physics and chemistry
and related quantities are given in Tables XLIX to LVI.
These tables are very similar in form to their 2002 coun-
terparts; the principal difference is that a number of new
recommended values have been included in the 2006 list,
in particular, in Table L. These are
m
P
c
2
in GeV, where
m
P
is the Planck mass; the
g
-factor of the deuteron
g
d
;
b
′
=
ν
max
/T
, the Wien displacement law-constant for fre-
quency; and for the ï¬rst time, 14 recommended values of
a number of constants that characterize the triton, in-
cluding its mass
m
t
, magnetic moment
µ
t
,
g
-factor
g
t
,
and the magnetic moment ratios
µ
t
/µ
e
and
µ
t
/µ
p
. The
addition of the triton-related constants is a direct con-
sequence of the improved measurement of
A
r
(
3
H) (item
B
3 in Table XXX) and the new NMR measurements on,
and re-examined shielding correction differences for, the
HT molecule (items
B
22 and
B
23 in Table XXX).
Table XLIX is a highly abbreviated list containing the
values of the constants and conversion factors most com-
monly used. Table L is a much more extensive list of
values categorized as follows: UNIVERSAL; ELECTRO-
MAGNETIC; ATOMIC AND NUCLEAR; and PHYSIC-
OCHEMICAL. The ATOMIC AND NUCLEAR cate-
gory is subdivided into 11 subcategories: General; Elec-
troweak; Electron, e
−
; Muon,
µ
−
; Tau,
Ï„
−
; Proton, p;
Neutron, n; Deuteron, d; Triton, t; Helion, h; and Al-
pha particle,
α
. Table LI gives the variances, covari-
ances, and correlation coefficients of a selected group of
constants. (Application of the covariance matrix is dis-
cussed in Appendix E of CODATA-98.) Table LII gives
the internationally adopted values of various quantities;
Table LIII lists the values of a number of x-ray related
quantities; Table LIV lists the values of various non-SI
units; and Tables LV and LVI give the values of various
energy equivalents.
All of the values given in Tables XLIX to LVI are
available on the Web pages of the Fundamental Con-
stants Data Center of the NIST Physics Laboratory at
physics.nist.gov/constants. This electronic version of the
2006 CODATA recommended values of the constants also
includes a much more extensive correlation coefficient
matrix. Indeed, the correlation coefficient of any two con-
stants listed in the tables is accessible on the Web site,
as well as the automatic conversion of the value of an
energy-related quantity expressed in one unit to the cor-
responding value expressed in another unit (in essence,
an automated version of Tables LV and LVI).
As discussed in Sec. V, well after the 31 December 2006
closing date of the 2006 adjustment and the 29 March
2007 distribution date of the 2006 recommended values
on the Web, Aoyama
et al.
(2007) reported their discov-
ery of an error in the coefficient
A
(8)
1
in the theoretical
expression for the electron magnetic moment anomaly
a
e
.
Use of the new coefficient would lead to an increase in
the 2006 recommended value of
α
by 6.8 times its un-
certainty, and an increase of its uncertainty by a factor
of 1.02. The recommended values and uncertainties of
constants that depend solely on
α
, or on
α
in combina-
tion with other constants with
u
r
no larger than a few
parts in 10
10
, would change in the same way. However,
the changes in the recommended values of the vast ma-
jority of the constants listed in the tables would lie in the
range 0 to 0
.
5 times their 2006 uncertainties, and their
uncertainties would remain essentially unchanged.
84
XIV. SUMMARY AND CONCLUSION
We conclude this report by (i) comparing the 2006 and
2002 CODATA recommended values of the constants and
identifying those new results that have contributed most
to the changes from the 2002 values; (ii) presenting some
of the conclusions that can be drawn from the 2006 rec-
ommended values and analysis of the 2006 input data;
and (iii) looking to the future and identifying experimen-
tal and theoretical work that can advance our knowledge
of the values of the constants.
A. Comparison of 2006 and 2002 CODATA recommended
values
The 2006 and 2002 recommended values of a represen-
tative group of constants are compared in Table XLVIII.
Regularities in the numbers in columns 2-4 arise because
many constants are obtained from expressions propor-
tional to
α
,
h
, or
R
raised to various powers. Thus, the
ï¬rst six quantities in the table are calculated from ex-
pressions proportional to
α
a
, where
|
a
|
= 1, 2, 3, or 6.
The next 15 quantities,
h
through
µ
p
, are calculated from
expressions containing the factor
h
a
, where
|
a
|
= 1 or
1
2
.
And the ï¬ve quantities
R
through
σ
are proportional to
R
a
, where
|
a
|
= 1 or 4.
Further comments on the entries in Table XLVIII are
as follows.
(i) The uncertainty of the 2002 recommended value
of
α
has been reduced by nearly a factor of ï¬ve by the
measurement of
a
e
at Harvard University and the im-
proved theoretical expression for
a
e
(th). The difference
between the Harvard result and the earlier University of
Washington result, which played a major role in the de-
termination of
α
in the 2002 adjustment, accounts for
most of the change in the recommended value of
α
from
2002 to 2006.
(ii) The uncertainty of the 2002 recommended value
of
h
has been reduced by over a factor of three due to
the new NIST watt-balance result for
K
2
J
R
K
and because
the factor used to increase the uncertainties of the data
related to
h
(applied to reduce the inconsistencies among
the data), was reduced from 2.325 in the 2002 adjust-
ment to 1.5 in the 2006 adjustment. That the change in
value from 2002 to 2006 is small is due to the excellent
agreement between the new value of
K
2
J
R
K
and the ear-
lier NIST and NPL values, which played a major role in
the determination of
h
in the 2002 adjustment.
(iii) The updating of two measurements that con-
tributed to the determination of the 2002 recommended
value of
G
reduced the spread in the values and rein-
forced the most accurate result, that from the University
of Washington. On this basis, the Task Group reduced
the assigned uncertainty from
u
r
= 1
.
5
×
10
−
5
in 2002
to
u
r
= 1
.
0
×
10
−
5
in 2006. This uncertainty reflects the
historical difficulty of measuring
G
. Although the recom-
mended value is the weighted mean of the eight available
TABLE XLVIII Comparison of the 2006 and 2002 CODATA
adjustments of the values of the constants by the comparison
of the corresponding recommended values of a representative
group of constants. Here
D
r
is the 2006 value minus the 2002
value divided by the standard uncertainty
u
of the 2002 value
(
i.e.,
D
r
is the change in the value of the constant from 2002
to 2006 relative to its 2002 standard uncertainty).
Quantity
2006 rel. std.
Ratio 2002
u
r
D
r
uncert.
u
r
to 2006
u
r
α
6
.
8
×
10
−
10
4
.
9
−
1
.
3
R
K
6
.
8
×
10
−
10
4
.
9
1
.
3
a
0
6
.
8
×
10
−
10
4
.
9
−
1
.
3
λ
C
1
.
4
×
10
−
9
4
.
9
−
1
.
3
r
e
2
.
1
×
10
−
9
4
.
9
−
1
.
3
σ
e
4
.
1
×
10
−
9
4
.
9
−
1
.
3
h
5
.
0
×
10
−
8
3
.
4
−
0
.
3
m
e
5
.
0
×
10
−
8
3
.
4
−
0
.
3
m
h
5
.
0
×
10
−
8
3
.
4
−
0
.
3
m
α
5
.
0
×
10
−
8
3
.
4
−
0
.
3
N
A
5
.
0
×
10
−
8
3
.
4
0
.
3
E
h
5
.
0
×
10
−
8
3
.
4
−
0
.
3
c
1
5
.
0
×
10
−
8
3
.
4
−
0
.
3
e
2
.
5
×
10
−
8
3
.
4
−
0
.
3
K
J
2
.
5
×
10
−
8
3
.
4
0
.
3
F
2
.
5
×
10
−
8
3
.
4
0
.
2
γ
′
p
2
.
7
×
10
−
8
3
.
2
0
.
2
µ
B
2
.
5
×
10
−
8
3
.
4
−
0
.
4
µ
N
2
.
5
×
10
−
8
3
.
4
−
0
.
4
µ
e
2
.
5
×
10
−
8
3
.
4
0
.
4
µ
p
2
.
6
×
10
−
8
3
.
3
−
0
.
4
R
1
.
7
×
10
−
6
1
.
0
0
.
0
k
1
.
7
×
10
−
6
1
.
0
0
.
0
V
m
1
.
7
×
10
−
6
1
.
0
0
.
0
c
2
1
.
7
×
10
−
6
1
.
0
0
.
0
σ
7
.
0
×
10
−
6
1
.
0
0
.
0
G
1
.
0
×
10
−
4
1
.
5
0
.
1
R
∞
6
.
6
×
10
−
12
1
.
0
0
.
0
m
e
/m
p
4
.
3
×
10
−
10
1
.
1
0
.
2
m
e
/m
µ
2
.
5
×
10
−
8
1
.
0
0
.
3
A
r
(e)
4
.
2
×
10
−
10
1
.
0
−
0
.
1
A
r
(p)
1
.
0
×
10
−
10
1
.
3
−
0
.
9
A
r
(n)
4
.
3
×
10
−
10
1
.
3
0
.
7
A
r
(d)
3
.
9
×
10
−
11
4
.
5
0
.
1
A
r
(h)
8
.
6
×
10
−
10
2
.
3
0
.
7
A
r
(
α
)
1
.
5
×
10
−
11
0
.
9
−
0
.
4
d
220
2
.
6
×
10
−
8
1
.
4
−
2
.
9
g
e
7
.
4
×
10
−
13
5
.
0
1
.
3
g
µ
6
.
0
×
10
−
10
1
.
0
−
1
.
4
µ
p
/µ
B
8
.
1
×
10
−
9
1
.
2
0
.
2
µ
p
/µ
N
8
.
2
×
10
−
9
1
.
2
0
.
2
µ
n
/µ
N
2
.
4
×
10
−
7
1
.
0
0
.
0
µ
d
/µ
N
8
.
4
×
10
−
9
1
.
3
−
0
.
2
µ
e
/µ
p
8
.
1
×
10
−
9
1
.
2
0
.
2
µ
n
/µ
p
2
.
4
×
10
−
7
1
.
0
0
.
0
µ
d
/µ
p
7
.
7
×
10
−
9
1
.
9
−
0
.
3
85
values, the assigned uncertainty is still over four times the
uncertainty of the mean multiplied by the corresponding
Birge ratio
R
B
.
(iv) The large shift in the recommended value of
d
220
from 2002 to 2006 is due to the fact that in the 2002
adjustment only the NMIJ result for
d
220
(
NR3
) was in-
cluded, while in the 2006 adjustment this result (but up-
dated by more recent NMIJ measurements) was included
together with the PTB result for
d
220
(
W4
.
2a
) and the new
INRIM results for
d
220
(
W4
.
2a
) and
d
220
(
MO
∗
). Moreover,
the NMIJ value of
d
220
inferred from
d
220
(
NR3
) strongly
disagrees with the values of
d
220
inferred from the other
three results.
(v) The marginally signiï¬cant shift in the recom-
mended value of
g
µ
from 2002 to 2006 is mainly due
to the following: In the 2002 adjustment, the principal
hadronic contribution to the theoretical expression for
a
µ
was based on both a calculation that included only e
+
e
−
annihilation data and a calculation that used data from
hadronic decays of the
Ï„
in place of some of the e
+
e
−
annihilation data. In the 2006 adjustment, the principal
hadronic contribution was based on a calculation that
used only annihilation data because of various concerns
that subsequently arose about the reliability of incorpo-
rating the
Ï„
data in the calculation; the calculation based
on both e
+
e
−
annihilation data and
Ï„
decay data was only
used to estimate the uncertainty of the hadronic contri-
bution. Because the results from the two calculations are
in signiï¬cant disagreement, the uncertainty of
a
µ
(th) is
comparatively large:
u
r
= 1
.
8
×
10
−
6
.
(vi) The reduction of the uncertainties of the mag-
netic moment ratios
µ
p
/µ
B
,
µ
p
/µ
N
,
µ
d
/µ
N
,
µ
e
/µ
p
,
and
µ
d
/µ
p
are due to the new NMR measurement of
µ
p
(HD)
/µ
d
(HD) and careful re-examination of the cal-
culation of the D-H shielding correction difference
σ
dp
.
Because the value of the product (
µ
p
/µ
e
)(
µ
e
/µ
d
) implied
by the new measurement is highly consistent with the
same product implied by the individual measurements of
µ
e
(H)
/µ
p
(H) and
µ
d
(D)
/µ
e
(D), the changes in the values
of the ratios are small.
In summary, the most important differences between
the 2006 and 2002 adjustments are that the 2006 ad-
justment had available new experimental and theoretical
results for
a
e
, which provided a dramatically improved
value of
α
, and a new result for
K
2
J
R
K
, which provided
a signiï¬cantly improved value of
h
. These two advances
from 2002 to 2006 have resulted in major reductions in
the uncertainties of many of the 2006 recommended val-
ues compared with their 2002 counterparts.
B. Some implications of the 2006 CODATA recommended
values and adjustment for physics and metrology
A number of conclusions that can be drawn from the
2006 adjustment concerning metrology and the basic the-
ories and experimental methods of physics are presented
here, where the focus is on those conclusions that are new
or are different from those drawn from the 2002 and 1998
adjustments.
Conventional electric units
.
One can interpret
the adoption of the conventional values
K
J
−
90
=
483 597
.
9 GHz/V and
R
K
−
90
= 25 812
.
807 Ω for the
Josephson and von Klitzing constants as establishing con-
ventional, practical units of voltage and resistance,
V
90
and
Ω
90
, given by
V
90
= (
K
J
−
90
/K
J
) V and
Ω
90
=
(
R
K
/R
K
−
90
) Ω. Other conventional electric units fol-
low from
V
90
and
Ω
90
, for example,
A
90
=
V
90
/
Ω
90
,
C
90
=
A
90
s,
W
90
=
A
90
V
90
,
F
90
=
C
90
/V
90
, and
H
90
=
Ω
90
s, which are the conventional, practical units
of current, charge, power, capacitance, and inductance,
respectively (Taylor and Mohr, 2001). For the relations
between
K
J
and
K
J
−
90
, and
R
K
and
R
K
−
90
, the 2006
adjustment gives
K
J
=
K
J
−
90
[1
−
1
.
9(2
.
5)
×
10
−
8
]
(374)
R
K
=
R
K
−
90
[1 + 2
.
159(68)
×
10
−
8
]
,
(375)
which lead to
V
90
= [1 + 1
.
9(2
.
5)
×
10
−
8
] V
(376)
Ω
90
= [1 + 2
.
159(68)
×
10
−
8
] Ω
(377)
A
90
= [1
−
0
.
3(2
.
5)
×
10
−
8
] A
(378)
C
90
= [1
−
0
.
3(2
.
5)
×
10
−
8
] C
(379)
W
90
= [1 + 1
.
6(5
.
0)
×
10
−
8
] W
(380)
F
90
= [1
−
2
.
159(68)
×
10
−
8
] F
(381)
H
90
= [1 + 2
.
159(68)
×
10
−
8
] H
.
(382)
Equations (376) and (377) show that
V
90
exceeds V and
Ω
90
exceeds Ω by 1
.
9(2
.
5)
×
10
−
8
and 2
.
159(68)
×
10
−
8
,
respectively. This means that measured voltages and re-
sistances traceable to the Josephson effect and
K
J
−
90
and
the quantum Hall effect and
R
K
−
90
, respectively, are too
small relative to the SI by these same fractional amounts.
However, these differences are well within the 40
×
10
−
8
uncertainty assigned to
V
90
/
V and the 10
×
10
−
8
uncer-
tainty assigned to
Ω
90
/
Ω by the Consultative Commit-
tee for Electricity and Magnetism (CCEM) of the CIPM
(Quinn, 1989, 2001).
Josephson and quantum Hall effects
. The study in
Sec. XII.B.2 provides no statistically signiï¬cant evidence
that the fundamental Josephson and quantum Hall ef-
fect relations
K
J
= 2
e/h
and
R
K
=
h/e
2
are not exact.
The theories of two of the most important phenomena of
condensed-matter physics are thereby further supported.
Antiprotonic helium
. The good agreement between the
value of
A
r
(e) obtained from the measured values and
theoretical expressions for a number of transition fre-
quencies in antiprotonic
4
He and
3
He with three other
values obtained by entirely different methods indicates
that these rather complex atoms are reasonably well un-
derstood both experimentally and theoretically.
Newtonian constant of gravitation
. Although the in-
consistencies among the values of
G
have been reduced
somewhat as a result of modiï¬cations to two of the eight
86
results available in 2002, the situation remains problem-
atic; there is no evidence that the historic difficulty of
measuring
G
has been overcome.
Tests of QED
. The good agreement of the highly
accurate values of
α
inferred from
h/m
(
133
Cs) and
h/m
(
87
Rb), which are only weakly dependent on QED
theory, with the values of
α
inferred from
a
e
, muonium
transition frequencies, and H and D transition frequen-
cies, provide support for the QED theory of
a
e
as well
as the bound-state QED theory of muonium and H and
D. In particular, the weighted mean of the two values
of
α
inferred from
h/m
(
133
Cs) and
h/m
(
87
Rb),
α
−
1
=
137
.
035 999 34(69) [5
.
0
×
10
−
9
], and the weighted mean
of the two values of
α
inferred from the two experimen-
tal values of
a
e
,
α
−
1
= 137
.
035 999 680(94) [6
.
9
×
10
−
10
],
differ by only 0.5
u
diff
, with
u
diff
= 5
.
1
×
10
−
9
. This is a
truly impressive conï¬rmation of QED theory.
Physics beyond the Standard Model
.
If the princi-
pal hadronic contribution to
a
µ
(th) obtained from the
e
+
e
−
annihilation-data plus
Ï„
hadronic-decay-data cal-
culation (see previous section) is completely ignored, and
the value based on the annihilation-data-only calcula-
tion with its uncertainty of 45
×
10
−
11
is used in
a
µ
(th),
then the value of
α
inferred from the BNL experimen-
tally determined value of
a
µ
(exp),
α
−
1
= 137
.
035 670(91)
[6
.
6
×
10
−
7
], differs from the
h/m
(
133
Cs)-
h/m
(
87
Rb)
mean value of
α
by 3
.
6
u
diff
. Although such a large dis-
crepancy may suggest “New Physics,†the consensus is
that such a view is premature (Davier, 2006).
Electrical and silicon crystal-related measurements
.
The previously discussed inconsistencies involving the
watt-balance determinations of
K
2
J
R
K
, the mercury elec-
trometer and voltage balance measurements of
K
J
, the
XROI determinations of the
{
220
}
lattice spacing of var-
ious silicon crystals, the measurement of
h/m
n
d
220
(
W04
),
and the measurement of
V
m
(Si) hint at possible problems
with one or more of these these rather complex experi-
ments. This suggests that some of the many different
measurement techniques required for their execution may
not be as well understood as is currently believed.
Redefinition of the kilogram
. There has been consider-
able discussion of late about the possibility of the 24th
General Conference on Weights and Measures (CGPM),
which convenes in 2011, redeï¬ning the kilogram, ampere,
kelvin, and mole by linking these SI base units to ï¬xed
values of
h
,
e
,
k
, and
N
A
, respectively (Mills
et al.
, 2006;
Stock and Witt, 2006), in much the same way that the
current deï¬nition of the meter is linked to a ï¬xed value of
c
(BIPM, 2006). Before such a deï¬nition of the kilogram
can be accepted,
h
should be known with a
u
r
of a few
parts in 10
−
8
. It is therefore noteworthy that the 2006
CODATA recommended value of
h
has
u
r
= 5
.
0
×
10
−
8
and the most accurate measured value of
h
(the 2007
NIST watt-balance result) has
u
r
= 3
.
6
×
10
−
8
.
C. Outlook and suggestions for future work
Because there is little redundancy among some of the
key input data, the 2006 CODATA set of recommended
values, like its 2002 and 1998 predecessors, does not rest
on as solid a foundation as one might wish. The constants
α
,
h
, and
R
play a critical role in determining many other
constants, yet the recommended value of each is deter-
mined by a severely limited number of input data. More-
over, some input data for the same quantity have uncer-
tainties of considerably different magnitudes and hence
these data contribute to the ï¬nal adjustment with con-
siderably different weights.
The input datum that primarily determines
α
is the
2006 experimental result for
a
e
from Harvard University
with
u
r
= 6
.
5
×
10
−
10
; the uncertainty
u
r
= 37
×
10
−
10
of
the next most accurate experimental result for
a
e
, that
reported by the University of Washington in 1987, is 5.7
times larger. Furthermore, there is only a single value of
the eighth-order coefficient
A
(8)
1
, that due to Kinoshita
and Nio; it plays a critical role in the theoretical expres-
sion for
a
e
from which
α
is obtained and requires lengthy
QED calculations.
The 2007 NIST watt-balance result for
K
2
J
R
K
with
u
r
= 3
.
6
×
10
−
8
is the primary input datum that deter-
mines
h
, since the uncertainty of the next most accurate
value of
K
2
J
R
K
, the NIST 1998 result, is 2.4 times larger.
Further, the 2005 consensus value of
V
m
(Si) disagrees
with all three high accuracy measurements of
K
2
J
R
K
cur-
rently available.
For
R
, the key input datum is the 1998 NIST value
based on speed-of-sound measurements in argon using a
spherical acoustic resonator with
u
r
= 1
.
7
×
10
−
6
. The
uncertainty of the next most accurate value, the 1979
NPL result, also obtained from speed of sound measure-
ments in argon but using an acoustic interferometer, is
4.7 times larger.
Lack of redundancy is, of course, not the only difficulty
with the 2006 adjustment. An equally important but
not fully independent issue is the several inconsistencies
involving some of the electrical and silicon crystal-related
input data as already discussed, including the recently
reported preliminary result for
K
2
J
R
K
from the NPL watt
balance given in Sec VII.D.1. There is also the issue of
the recently corrected (but still tentative) value for the
coefficient
A
(8)
1
in the theoretical expression for
a
e
given
in Sec V, which would directly effect the recommended
value of
α
.
With these problems in mind, some of which impact
the possible redeï¬nition of the kilogram, ampere, kelvin,
and mole in terms of exact values of
h
,
e
,
k
, and
N
A
in 2011, we offer the following “wish list†for new work.
If these needs, some of which appeared in our similar
2002 list, are successfully met, the key issues facing the
precision measurement-fundamental constants and fun-
damental metrology ï¬elds should be resolved. As a conse-
quence, our knowledge of the values of the constants, to-
gether with the International System of Units (SI), would
87
be signiï¬cantly advanced.
(i) A watt-balance determination of
K
2
J
R
K
from a lab-
oratory other than NIST or NPL with a
u
r
fully compet-
itive with
u
r
= 3
.
6
×
10
−
8
, the uncertainty of the most
accurate value currently available from NIST.
(ii) A timely completion of the current international ef-
fort to determine
N
A
with a
u
r
of a few parts in 10
8
using
highly enriched silicon crystals with
x
(
28
Si)
>
0
.
999 85
(Becker
et al.
, 2006). This will require major advances
in determining the
{
220
}
lattice spacing, density, and
molar mass of silicon.
(iii) A determination of
R
(or Boltzmann constant
k
=
R/N
A
) with a
u
r
fully competitive with
u
r
= 1
.
7
×
10
−
6
,
the uncertainty of the most accurate value of
R
currently
available, preferably using a method other than measur-
ing the velocity of sound in argon.
(iv) An independent calculation of the eighth order
coefficient
A
(8)
1
in the QED theoretical expression for
a
e
.
(v) A determination of
α
that is only weakly dependent
on QED theory with a value of
u
r
fully competitive with
u
r
= 7
.
0
×
10
−
10
, the uncertainty of the most accurate
value currently available as obtained from
a
e
(exp) and
a
e
(th).
(vi) A determination of the Newtonian constant of
gravitation
G
with a
u
r
fully competitive with
u
r
=
1
.
4
×
10
−
5
, the uncertainty of the most accurate value
of
G
currently available.
(vii) A measurement of a transition frequency in hy-
drogen or deuterium, other than the already well-known
hydrogen 1S
1
/
2
−
2S
1
/
2
frequency, with an uncertainty
within an order of magnitude of the current uncertainty
of that frequency,
u
r
= 1
.
4
×
10
−
14
, thereby providing an
improved value of the Rydberg constant
R
∞
.
(viii) Improved theory of the principal hadronic con-
tribution to the theoretical expression for the muon mag-
netic moment anomaly
a
µ
(th) and improvements in the
experimental data underlying the calculation of this con-
tribution so that the origin of the current disagreement
between
a
µ
(th) and
a
µ
(exp) can be better understood.
(ix) Although there is no experimental or theoretical
evidence that the relations
K
J
= 2
e/h
and
R
K
=
h/e
2
are not exact, improved calculable-capacitor measure-
ments of
R
K
and low-ï¬eld measurements of the gyro-
magnetic ratios of the shielded proton and shielded he-
lion, which could provide further tests of the exactness of
these relations, would not be unwelcome, nor would high
accuracy results (
u
r
≈
10
−
8
) from experiments to close
the “quantum electrical triangle†(Drake and Grigorescu,
2005; Piquemal
et al.
, 2007).
It will be most interesting to see what portion, if any,
of this very ambitious program of work is completed by
the 31 December 2010 closing date of the next CODATA
adjustment of the values of the constants. Indeed, the
progress made, especially in meeting needs (i)-(iii), may
very likely determine whether the 24th CGPM, which
convenes in October 2011, will approve new deï¬nitions
of the kilogram, ampere, kelvin, and mole as discussed in
the previous section. If such new deï¬nitions are adopted,
h
,
e
,
k
, and
N
A
as well as a number of other fundamen-
tal constants, for example,
K
J
,
R
K
(assuming
K
J
= 2
e/h
and
R
K
=
h/e
2
),
R
, and
σ
, would be exactly known, and
many others would have signiï¬cantly reduced uncertain-
ties. The result would be a signiï¬cant advance in our
knowledge of the values of the constants.
XV. ACKNOWLEDGMENTS
We gratefully acknowledge the help of our many col-
leagues who provided us results prior to formal publica-
tion and for promptly and patiently answering our many
questions about their work.
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TABLE XLIX An abbreviated list of the CODATA recommended values of the fundamental constants of physics and chemistry
based on the 2006 adjustment.
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
speed of light in vacuum
c, c
0
299 792 458
m s
−
1
(exact)
magnetic constant
µ
0
4
Ï€
×
10
−
7
N A
−
2
= 12
.
566 370 614
...
×
10
−
7
N A
−
2
(exact)
electric constant 1/
µ
0
c
2
Ç«
0
8
.
854 187 817
...
×
10
−
12
F m
−
1
(exact)
Newtonian constant
of gravitation
G
6
.
674 28(67)
×
10
−
11
m
3
kg
−
1
s
−
2
1
.
0
×
10
−
4
Planck constant
h
6
.
626 068 96(33)
×
10
−
34
J s
5
.
0
×
10
−
8
h/
2
Ï€
¯
h
1
.
054 571 628(53)
×
10
−
34
J s
5
.
0
×
10
−
8
elementary charge
e
1
.
602 176 487(40)
×
10
−
19
C
2
.
5
×
10
−
8
magnetic flux quantum
h
/2
e
Φ
0
2
.
067 833 667(52)
×
10
−
15
Wb
2
.
5
×
10
−
8
conductance quantum 2
e
2
/h
G
0
7
.
748 091 7004(53)
×
10
−
5
S
6
.
8
×
10
−
10
electron mass
m
e
9
.
109 382 15(45)
×
10
−
31
kg
5
.
0
×
10
−
8
proton mass
m
p
1
.
672 621 637(83)
×
10
−
27
kg
5
.
0
×
10
−
8
proton-electron mass ratio
m
p
/
m
e
1836
.
152 672 47(80)
4
.
3
×
10
−
10
ï¬ne-structure constant
e
2
/
4
Ï€
Ç«
0
¯
hc α
7
.
297 352 5376(50)
×
10
−
3
6
.
8
×
10
−
10
inverse ï¬ne-structure constant
α
−
1
137
.
035 999 679(94)
6
.
8
×
10
−
10
Rydberg constant
α
2
m
e
c/
2
h
R
∞
10 973 731
.
568 527(73)
m
−
1
6
.
6
×
10
−
12
Avogadro constant
N
A
, L
6
.
022 141 79(30)
×
10
23
mol
−
1
5
.
0
×
10
−
8
Faraday constant
N
A
e
F
96 485
.
3399(24)
C mol
−
1
2
.
5
×
10
−
8
molar gas constant
R
8
.
314 472(15)
J mol
−
1
K
−
1
1
.
7
×
10
−
6
Boltzmann constant
R
/
N
A
k
1
.
380 6504(24)
×
10
−
23
J K
−
1
1
.
7
×
10
−
6
Stefan-Boltzmann constant
(
Ï€
2
/60)
k
4
/
¯
h
3
c
2
σ
5
.
670 400(40)
×
10
−
8
W m
−
2
K
−
4
7
.
0
×
10
−
6
Non-SI units accepted for use with the SI
electron volt: (
e
/C) J
eV
1
.
602 176 487(40)
×
10
−
19
J
2
.
5
×
10
−
8
(uniï¬ed) atomic mass unit
1 u =
m
u
=
1
12
m
(
12
C)
u
1
.
660 538 782(83)
×
10
−
27
kg
5
.
0
×
10
−
8
= 10
−
3
kg mol
−
1
/N
A
95
TABLE L: The CODATA recommended values of the fundamental con-
stants of physics and chemistry based on the 2006 adjustment.
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
UNIVERSAL
speed of light in vacuum
c, c
0
299 792 458
m s
−
1
(exact)
magnetic constant
µ
0
4
Ï€
×
10
−
7
N A
−
2
= 12
.
566 370 614
...
×
10
−
7
N A
−
2
(exact)
electric constant 1/
µ
0
c
2
Ç«
0
8
.
854 187 817
...
×
10
−
12
F m
−
1
(exact)
characteristic impedance
of vacuum
p
µ
0
/Ç«
0
=
µ
0
c
Z
0
376
.
730 313 461
...
Ω
(exact)
Newtonian constant
of gravitation
G
6
.
674 28(67)
×
10
−
11
m
3
kg
−
1
s
−
2
1
.
0
×
10
−
4
G/
¯
hc
6
.
708 81(67)
×
10
−
39
(GeV
/c
2
)
−
2
1
.
0
×
10
−
4
Planck constant
h
6
.
626 068 96(33)
×
10
−
34
J s
5
.
0
×
10
−
8
in eV s
4
.
135 667 33(10)
×
10
−
15
eV s
2
.
5
×
10
−
8
h/
2
Ï€
¯
h
1
.
054 571 628(53)
×
10
−
34
J s
5
.
0
×
10
−
8
in eV s
6
.
582 118 99(16)
×
10
−
16
eV s
2
.
5
×
10
−
8
¯
hc
in MeV fm
197
.
326 9631(49)
MeV fm
2
.
5
×
10
−
8
Planck mass (¯
hc/G
)
1
/
2
m
P
2
.
176 44(11)
×
10
−
8
kg
5
.
0
×
10
−
5
energy equivalent in GeV
m
P
c
2
1
.
220 892(61)
×
10
19
GeV
5
.
0
×
10
−
5
Planck temperature (¯
hc
5
/G
)
1
/
2
/k
T
P
1
.
416 785(71)
×
10
32
K
5
.
0
×
10
−
5
Planck length ¯
h/m
P
c
= (¯
hG/c
3
)
1
/
2
l
P
1
.
616 252(81)
×
10
−
35
m
5
.
0
×
10
−
5
Planck time
l
P
/c
= (¯
hG/c
5
)
1
/
2
t
P
5
.
391 24(27)
×
10
−
44
s
5
.
0
×
10
−
5
ELECTROMAGNETIC
elementary charge
e
1
.
602 176 487(40)
×
10
−
19
C
2
.
5
×
10
−
8
e/h
2
.
417 989 454(60)
×
10
14
A J
−
1
2
.
5
×
10
−
8
magnetic flux quantum
h/
2
e
Φ
0
2
.
067 833 667(52)
×
10
−
15
Wb
2
.
5
×
10
−
8
conductance quantum 2
e
2
/h
G
0
7
.
748 091 7004(53)
×
10
−
5
S
6
.
8
×
10
−
10
inverse of conductance quantum
G
−
1
0
12 906
.
403 7787(88)
Ω
6
.
8
×
10
−
10
Josephson constant
a
2
e/h
K
J
483 597
.
891(12)
×
10
9
Hz V
−
1
2
.
5
×
10
−
8
von Klitzing constant
b
h/e
2
=
µ
0
c/
2
α
R
K
25 812
.
807 557(18)
Ω
6
.
8
×
10
−
10
Bohr magneton
e
¯
h/
2
m
e
µ
B
927
.
400 915(23)
×
10
−
26
J T
−
1
2
.
5
×
10
−
8
in eV T
−
1
5
.
788 381 7555(79)
×
10
−
5
eV T
−
1
1
.
4
×
10
−
9
µ
B
/h
13
.
996 246 04(35)
×
10
9
Hz T
−
1
2
.
5
×
10
−
8
µ
B
/hc
46
.
686 4515(12)
m
−
1
T
−
1
2
.
5
×
10
−
8
µ
B
/k
0
.
671 7131(12)
K T
−
1
1
.
7
×
10
−
6
nuclear magneton
e
¯
h/
2
m
p
µ
N
5
.
050 783 24(13)
×
10
−
27
J T
−
1
2
.
5
×
10
−
8
in eV T
−
1
3
.
152 451 2326(45)
×
10
−
8
eV T
−
1
1
.
4
×
10
−
9
µ
N
/h
7
.
622 593 84(19)
MHz T
−
1
2
.
5
×
10
−
8
µ
N
/hc
2
.
542 623 616(64)
×
10
−
2
m
−
1
T
−
1
2
.
5
×
10
−
8
µ
N
/k
3
.
658 2637(64)
×
10
−
4
K T
−
1
1
.
7
×
10
−
6
ATOMIC AND NUCLEAR
General
ï¬ne-structure constant
e
2
/
4
Ï€
Ç«
0
¯
hc
α
7
.
297 352 5376(50)
×
10
−
3
6
.
8
×
10
−
10
inverse ï¬ne-structure constant
α
−
1
137
.
035 999 679(94)
6
.
8
×
10
−
10
Rydberg constant
α
2
m
e
c/
2
h
R
∞
10 973 731
.
568 527(73)
m
−
1
6
.
6
×
10
−
12
a
See Table LII for the conventional value adopted internationally for realizing representations of the volt using the Josephson effect.
b
See Table LII for the conventional value adopted internationally for realizing representations of the ohm using the quantum Hall effect.
96
TABLE L:
(Continued).
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
R
∞
c
3
.
289 841 960 361(22)
×
10
15
Hz
6
.
6
×
10
−
12
R
∞
hc
2
.
179 871 97(11)
×
10
−
18
J
5
.
0
×
10
−
8
R
∞
hc
in eV
13
.
605 691 93(34)
eV
2
.
5
×
10
−
8
Bohr radius
α/
4
Ï€
R
∞
= 4
Ï€
Ç«
0
¯
h
2
/m
e
e
2
a
0
0
.
529 177 208 59(36)
×
10
−
10
m
6
.
8
×
10
−
10
Hartree energy
e
2
/
4
Ï€
Ç«
0
a
0
= 2
R
∞
hc
=
α
2
m
e
c
2
E
h
4
.
359 743 94(22)
×
10
−
18
J
5
.
0
×
10
−
8
in eV
27
.
211 383 86(68)
eV
2
.
5
×
10
−
8
quantum of circulation
h/
2
m
e
3
.
636 947 5199(50)
×
10
−
4
m
2
s
−
1
1
.
4
×
10
−
9
h/m
e
7
.
273 895 040(10)
×
10
−
4
m
2
s
−
1
1
.
4
×
10
−
9
Electroweak
Fermi coupling constant
c
G
F
/
(¯
hc
)
3
1
.
166 37(1)
×
10
−
5
GeV
−
2
8
.
6
×
10
−
6
weak mixing angle
d
θ
W
(on-shell scheme)
sin
2
θ
W
=
s
2
W
≡
1
−
(
m
W
/m
Z
)
2
sin
2
θ
W
0
.
222 55(56)
2
.
5
×
10
−
3
Electron, e
−
electron mass
m
e
9
.
109 382 15(45)
×
10
−
31
kg
5
.
0
×
10
−
8
in u,
m
e
=
A
r
(e) u (electron
relative atomic mass times u)
5
.
485 799 0943(23)
×
10
−
4
u
4
.
2
×
10
−
10
energy equivalent
m
e
c
2
8
.
187 104 38(41)
×
10
−
14
J
5
.
0
×
10
−
8
in MeV
0
.
510 998 910(13)
MeV
2
.
5
×
10
−
8
electron-muon mass ratio
m
e
/m
µ
4
.
836 331 71(12)
×
10
−
3
2
.
5
×
10
−
8
electron-tau mass ratio
m
e
/m
Ï„
2
.
875 64(47)
×
10
−
4
1
.
6
×
10
−
4
electron-proton mass ratio
m
e
/m
p
5
.
446 170 2177(24)
×
10
−
4
4
.
3
×
10
−
10
electron-neutron mass ratio
m
e
/m
n
5
.
438 673 4459(33)
×
10
−
4
6
.
0
×
10
−
10
electron-deuteron mass ratio
m
e
/m
d
2
.
724 437 1093(12)
×
10
−
4
4
.
3
×
10
−
10
electron to alpha particle mass ratio
m
e
/m
α
1
.
370 933 555 70(58)
×
10
−
4
4
.
2
×
10
−
10
electron charge to mass quotient
−
e/m
e
−
1
.
758 820 150(44)
×
10
11
C kg
−
1
2
.
5
×
10
−
8
electron molar mass
N
A
m
e
M
(e)
, M
e
5
.
485 799 0943(23)
×
10
−
7
kg mol
−
1
4
.
2
×
10
−
10
Compton wavelength
h/m
e
c
λ
C
2
.
426 310 2175(33)
×
10
−
12
m
1
.
4
×
10
−
9
λ
C
/
2
Ï€
=
αa
0
=
α
2
/
4
Ï€
R
∞
λ
C
386
.
159 264 59(53)
×
10
−
15
m
1
.
4
×
10
−
9
classical electron radius
α
2
a
0
r
e
2
.
817 940 2894(58)
×
10
−
15
m
2
.
1
×
10
−
9
Thomson cross section (8
Ï€
/
3)
r
2
e
σ
e
0
.
665 245 8558(27)
×
10
−
28
m
2
4
.
1
×
10
−
9
electron magnetic moment
µ
e
−
928
.
476 377(23)
×
10
−
26
J T
−
1
2
.
5
×
10
−
8
to Bohr magneton ratio
µ
e
/µ
B
−
1
.
001 159 652 181 11(74)
7
.
4
×
10
−
13
to nuclear magneton ratio
µ
e
/µ
N
−
1838
.
281 970 92(80)
4
.
3
×
10
−
10
electron magnetic moment
anomaly
|
µ
e
|
/µ
B
−
1
a
e
1
.
159 652 181 11(74)
×
10
−
3
6
.
4
×
10
−
10
electron
g
-factor
−
2(1 +
a
e
)
g
e
−
2
.
002 319 304 3622(15)
7
.
4
×
10
−
13
electron-muon
magnetic moment ratio
µ
e
/µ
µ
206
.
766 9877(52)
2
.
5
×
10
−
8
electron-proton
magnetic moment ratio
µ
e
/µ
p
−
658
.
210 6848(54)
8
.
1
×
10
−
9
electron to shielded proton
magnetic moment ratio
µ
e
/µ
′
p
−
658
.
227 5971(72)
1
.
1
×
10
−
8
(H
2
O, sphere, 25
â—¦
C)
c
Value recommended by the Particle Data Group (Yao
et al.
, 2006).
d
Based on the ratio of the masses of the W and Z bosons
m
W
/m
Z
recommended by the Particle Data Group (Yao
et al.
, 2006).
The value for sin
2
θ
W
they recommend, which is based on a particular variant of the modified minimal subtraction (
MS
) scheme, is
sin
2
ˆ
θ
W
(
M
Z
) = 0
.
231 22(15).
97
TABLE L:
(Continued).
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
electron-neutron
magnetic moment ratio
µ
e
/µ
n
960
.
920 50(23)
2
.
4
×
10
−
7
electron-deuteron
magnetic moment ratio
µ
e
/µ
d
−
2143
.
923 498(18)
8
.
4
×
10
−
9
electron to shielded helion
magnetic moment ratio
µ
e
/µ
′
h
864
.
058 257(10)
1
.
2
×
10
−
8
(gas, sphere, 25
â—¦
C)
electron gyromagnetic ratio 2
|
µ
e
|
/
¯
h
γ
e
1
.
760 859 770(44)
×
10
11
s
−
1
T
−
1
2
.
5
×
10
−
8
γ
e
/
2
Ï€
28 024
.
953 64(70)
MHz T
−
1
2
.
5
×
10
−
8
Muon,
µ
−
muon mass
m
µ
1
.
883 531 30(11)
×
10
−
28
kg
5
.
6
×
10
−
8
in u,
m
µ
=
A
r
(
µ
) u (muon
relative atomic mass times u)
0
.
113 428 9256(29)
u
2
.
5
×
10
−
8
energy equivalent
m
µ
c
2
1
.
692 833 510(95)
×
10
−
11
J
5
.
6
×
10
−
8
in MeV
105
.
658 3668(38)
MeV
3
.
6
×
10
−
8
muon-electron mass ratio
m
µ
/m
e
206
.
768 2823(52)
2
.
5
×
10
−
8
muon-tau mass ratio
m
µ
/m
Ï„
5
.
945 92(97)
×
10
−
2
1
.
6
×
10
−
4
muon-proton mass ratio
m
µ
/m
p
0
.
112 609 5261(29)
2
.
5
×
10
−
8
muon-neutron mass ratio
m
µ
/m
n
0
.
112 454 5167(29)
2
.
5
×
10
−
8
muon molar mass
N
A
m
µ
M
(
µ
)
, M
µ
0
.
113 428 9256(29)
×
10
−
3
kg mol
−
1
2
.
5
×
10
−
8
muon Compton wavelength
h/m
µ
c
λ
C
,
µ
11
.
734 441 04(30)
×
10
−
15
m
2
.
5
×
10
−
8
λ
C
,
µ
/
2
Ï€
λ
C
,
µ
1
.
867 594 295(47)
×
10
−
15
m
2
.
5
×
10
−
8
muon magnetic moment
µ
µ
−
4
.
490 447 86(16)
×
10
−
26
J T
−
1
3
.
6
×
10
−
8
to Bohr magneton ratio
µ
µ
/µ
B
−
4
.
841 970 49(12)
×
10
−
3
2
.
5
×
10
−
8
to nuclear magneton ratio
µ
µ
/µ
N
−
8
.
890 597 05(23)
2
.
5
×
10
−
8
muon magnetic moment anomaly
|
µ
µ
|
/
(
e
¯
h/
2
m
µ
)
−
1
a
µ
1
.
165 920 69(60)
×
10
−
3
5
.
2
×
10
−
7
muon
g
-factor
−
2(1 +
a
µ
)
g
µ
−
2
.
002 331 8414(12)
6
.
0
×
10
−
10
muon-proton
magnetic moment ratio
µ
µ
/µ
p
−
3
.
183 345 137(85)
2
.
7
×
10
−
8
Tau,
Ï„
−
tau mass
e
m
Ï„
3
.
167 77(52)
×
10
−
27
kg
1
.
6
×
10
−
4
in u,
m
Ï„
=
A
r
(
Ï„
) u (tau
relative atomic mass times u)
1
.
907 68(31)
u
1
.
6
×
10
−
4
energy equivalent
m
Ï„
c
2
2
.
847 05(46)
×
10
−
10
J
1
.
6
×
10
−
4
in MeV
1776
.
99(29)
MeV
1
.
6
×
10
−
4
tau-electron mass ratio
m
Ï„
/m
e
3477
.
48(57)
1
.
6
×
10
−
4
tau-muon mass ratio
m
Ï„
/m
µ
16
.
8183(27)
1
.
6
×
10
−
4
tau-proton mass ratio
m
Ï„
/m
p
1
.
893 90(31)
1
.
6
×
10
−
4
tau-neutron mass ratio
m
Ï„
/m
n
1
.
891 29(31)
1
.
6
×
10
−
4
tau molar mass
N
A
m
Ï„
M
(
Ï„
)
, M
Ï„
1
.
907 68(31)
×
10
−
3
kg mol
−
1
1
.
6
×
10
−
4
tau Compton wavelength
h/m
Ï„
c
λ
C
,
Ï„
0
.
697 72(11)
×
10
−
15
m
1
.
6
×
10
−
4
λ
C
,
Ï„
/
2
Ï€
λ
C
,
Ï„
0
.
111 046(18)
×
10
−
15
m
1
.
6
×
10
−
4
Proton, p
proton mass
m
p
1
.
672 621 637(83)
×
10
−
27
kg
5
.
0
×
10
−
8
in u,
m
p
=
A
r
(p) u (proton
e
This and all other values involving
m
Ï„
are based on the value of
m
Ï„
c
2
in MeV recommended by the Particle Data Group (Yao
et al.
,
2006), but with a standard uncertainty of 0
.
29 MeV rather than the quoted uncertainty of
−
0
.
26 MeV, +0
.
29 MeV.
98
TABLE L:
(Continued).
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
relative atomic mass times u)
1
.
007 276 466 77(10)
u
1
.
0
×
10
−
10
energy equivalent
m
p
c
2
1
.
503 277 359(75)
×
10
−
10
J
5
.
0
×
10
−
8
in MeV
938
.
272 013(23)
MeV
2
.
5
×
10
−
8
proton-electron mass ratio
m
p
/m
e
1836
.
152 672 47(80)
4
.
3
×
10
−
10
proton-muon mass ratio
m
p
/m
µ
8
.
880 243 39(23)
2
.
5
×
10
−
8
proton-tau mass ratio
m
p
/m
Ï„
0
.
528 012(86)
1
.
6
×
10
−
4
proton-neutron mass ratio
m
p
/m
n
0
.
998 623 478 24(46)
4
.
6
×
10
−
10
proton charge to mass quotient
e/m
p
9
.
578 833 92(24)
×
10
7
C kg
−
1
2
.
5
×
10
−
8
proton molar mass
N
A
m
p
M
(p),
M
p
1
.
007 276 466 77(10)
×
10
−
3
kg mol
−
1
1
.
0
×
10
−
10
proton Compton wavelength
h/m
p
c
λ
C
,
p
1
.
321 409 8446(19)
×
10
−
15
m
1
.
4
×
10
−
9
λ
C
,
p
/
2
Ï€
λ
C
,
p
0
.
210 308 908 61(30)
×
10
−
15
m
1
.
4
×
10
−
9
proton rms charge radius
R
p
0
.
8768(69)
×
10
−
15
m
7
.
8
×
10
−
3
proton magnetic moment
µ
p
1
.
410 606 662(37)
×
10
−
26
J T
−
1
2
.
6
×
10
−
8
to Bohr magneton ratio
µ
p
/µ
B
1
.
521 032 209(12)
×
10
−
3
8
.
1
×
10
−
9
to nuclear magneton ratio
µ
p
/µ
N
2
.
792 847 356(23)
8
.
2
×
10
−
9
proton
g
-factor 2
µ
p
/µ
N
g
p
5
.
585 694 713(46)
8
.
2
×
10
−
9
proton-neutron
magnetic moment ratio
µ
p
/µ
n
−
1
.
459 898 06(34)
2
.
4
×
10
−
7
shielded proton magnetic moment
µ
′
p
1
.
410 570 419(38)
×
10
−
26
J T
−
1
2
.
7
×
10
−
8
(H
2
O, sphere, 25
â—¦
C)
to Bohr magneton ratio
µ
′
p
/µ
B
1
.
520 993 128(17)
×
10
−
3
1
.
1
×
10
−
8
to nuclear magneton ratio
µ
′
p
/µ
N
2
.
792 775 598(30)
1
.
1
×
10
−
8
proton magnetic shielding
correction 1
−
µ
′
p
/µ
p
σ
′
p
25
.
694(14)
×
10
−
6
5
.
3
×
10
−
4
(H
2
O, sphere, 25
â—¦
C)
proton gyromagnetic ratio 2
µ
p
/
¯
h
γ
p
2
.
675 222 099(70)
×
10
8
s
−
1
T
−
1
2
.
6
×
10
−
8
γ
p
/
2
Ï€
42
.
577 4821(11)
MHz T
−
1
2
.
6
×
10
−
8
shielded proton gyromagnetic
ratio 2
µ
′
p
/
¯
h
γ
′
p
2
.
675 153 362(73)
×
10
8
s
−
1
T
−
1
2
.
7
×
10
−
8
(H
2
O, sphere, 25
â—¦
C)
γ
′
p
/
2
Ï€
42
.
576 3881(12)
MHz T
−
1
2
.
7
×
10
−
8
Neutron, n
neutron mass
m
n
1
.
674 927 211(84)
×
10
−
27
kg
5
.
0
×
10
−
8
in u,
m
n
=
A
r
(n) u (neutron
relative atomic mass times u)
1
.
008 664 915 97(43)
u
4
.
3
×
10
−
10
energy equivalent
m
n
c
2
1
.
505 349 505(75)
×
10
−
10
J
5
.
0
×
10
−
8
in MeV
939
.
565 346(23)
MeV
2
.
5
×
10
−
8
neutron-electron mass ratio
m
n
/m
e
1838
.
683 6605(11)
6
.
0
×
10
−
10
neutron-muon mass ratio
m
n
/m
µ
8
.
892 484 09(23)
2
.
5
×
10
−
8
neutron-tau mass ratio
m
n
/m
Ï„
0
.
528 740(86)
1
.
6
×
10
−
4
neutron-proton mass ratio
m
n
/m
p
1
.
001 378 419 18(46)
4
.
6
×
10
−
10
neutron molar mass
N
A
m
n
M
(n)
, M
n
1
.
008 664 915 97(43)
×
10
−
3
kg mol
−
1
4
.
3
×
10
−
10
neutron Compton wavelength
h/m
n
c
λ
C
,
n
1
.
319 590 8951(20)
×
10
−
15
m
1
.
5
×
10
−
9
λ
C
,
n
/
2
Ï€
λ
C
,
n
0
.
210 019 413 82(31)
×
10
−
15
m
1
.
5
×
10
−
9
neutron magnetic moment
µ
n
−
0
.
966 236 41(23)
×
10
−
26
J T
−
1
2
.
4
×
10
−
7
to Bohr magneton ratio
µ
n
/µ
B
−
1
.
041 875 63(25)
×
10
−
3
2
.
4
×
10
−
7
to nuclear magneton ratio
µ
n
/µ
N
−
1
.
913 042 73(45)
2
.
4
×
10
−
7
neutron
g
-factor 2
µ
n
/µ
N
g
n
−
3
.
826 085 45(90)
2
.
4
×
10
−
7
neutron-electron
magnetic moment ratio
µ
n
/µ
e
1
.
040 668 82(25)
×
10
−
3
2
.
4
×
10
−
7
99
TABLE L:
(Continued).
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
neutron-proton
magnetic moment ratio
µ
n
/µ
p
−
0
.
684 979 34(16)
2
.
4
×
10
−
7
neutron to shielded proton
magnetic moment ratio
µ
n
/µ
′
p
−
0
.
684 996 94(16)
2
.
4
×
10
−
7
(H
2
O, sphere, 25
â—¦
C)
neutron gyromagnetic ratio 2
|
µ
n
|
/
¯
h
γ
n
1
.
832 471 85(43)
×
10
8
s
−
1
T
−
1
2
.
4
×
10
−
7
γ
n
/
2
Ï€
29
.
164 6954(69)
MHz T
−
1
2
.
4
×
10
−
7
Deuteron, d
deuteron mass
m
d
3
.
343 583 20(17)
×
10
−
27
kg
5
.
0
×
10
−
8
in u,
m
d
=
A
r
(d) u (deuteron
relative atomic mass times u)
2
.
013 553 212 724(78)
u
3
.
9
×
10
−
11
energy equivalent
m
d
c
2
3
.
005 062 72(15)
×
10
−
10
J
5
.
0
×
10
−
8
in MeV
1875
.
612 793(47)
MeV
2
.
5
×
10
−
8
deuteron-electron mass ratio
m
d
/m
e
3670
.
482 9654(16)
4
.
3
×
10
−
10
deuteron-proton mass ratio
m
d
/m
p
1
.
999 007 501 08(22)
1
.
1
×
10
−
10
deuteron molar mass
N
A
m
d
M
(d)
, M
d
2
.
013 553 212 724(78)
×
10
−
3
kg mol
−
1
3
.
9
×
10
−
11
deuteron rms charge radius
R
d
2
.
1402(28)
×
10
−
15
m
1
.
3
×
10
−
3
deuteron magnetic moment
µ
d
0
.
433 073 465(11)
×
10
−
26
J T
−
1
2
.
6
×
10
−
8
to Bohr magneton ratio
µ
d
/µ
B
0
.
466 975 4556(39)
×
10
−
3
8
.
4
×
10
−
9
to nuclear magneton ratio
µ
d
/µ
N
0
.
857 438 2308(72)
8
.
4
×
10
−
9
deuteron
g
-factor
µ
d
/µ
N
g
d
0
.
857 438 2308(72)
8
.
4
×
10
−
9
deuteron-electron
magnetic moment ratio
µ
d
/µ
e
−
4
.
664 345 537(39)
×
10
−
4
8
.
4
×
10
−
9
deuteron-proton
magnetic moment ratio
µ
d
/µ
p
0
.
307 012 2070(24)
7
.
7
×
10
−
9
deuteron-neutron
magnetic moment ratio
µ
d
/µ
n
−
0
.
448 206 52(11)
2
.
4
×
10
−
7
Triton, t
triton mass
m
t
5
.
007 355 88(25)
×
10
−
27
kg
5
.
0
×
10
−
8
in u,
m
t
=
A
r
(t) u (triton
relative atomic mass times u)
3
.
015 500 7134(25)
u
8
.
3
×
10
−
10
energy equivalent
m
t
c
2
4
.
500 387 03(22)
×
10
−
10
J
5
.
0
×
10
−
8
in MeV
2808
.
920 906(70)
MeV
2
.
5
×
10
−
8
triton-electron mass ratio
m
t
/m
e
5496
.
921 5269(51)
9
.
3
×
10
−
10
triton-proton mass ratio
m
t
/m
p
2
.
993 717 0309(25)
8
.
4
×
10
−
10
triton molar mass
N
A
m
t
M
(t)
, M
t
3
.
015 500 7134(25)
×
10
−
3
kg mol
−
1
8
.
3
×
10
−
10
triton magnetic moment
µ
t
1
.
504 609 361(42)
×
10
−
26
J T
−
1
2
.
8
×
10
−
8
to Bohr magneton ratio
µ
t
/µ
B
1
.
622 393 657(21)
×
10
−
3
1
.
3
×
10
−
8
to nuclear magneton ratio
µ
t
/µ
N
2
.
978 962 448(38)
1
.
3
×
10
−
8
triton
g
-factor 2
µ
t
/µ
N
g
t
5
.
957 924 896(76)
1
.
3
×
10
−
8
triton-electron
magnetic moment ratio
µ
t
/µ
e
−
1
.
620 514 423(21)
×
10
−
3
1
.
3
×
10
−
8
triton-proton
magnetic moment ratio
µ
t
/µ
p
1
.
066 639 908(10)
9
.
8
×
10
−
9
triton-neutron
magnetic moment ratio
µ
t
/µ
n
−
1
.
557 185 53(37)
2
.
4
×
10
−
7
Helion, h
helion mass
e
m
h
5
.
006 411 92(25)
×
10
−
27
kg
5
.
0
×
10
−
8
in u,
m
h
=
A
r
(h) u (helion
relative atomic mass times u)
3
.
014 932 2473(26)
u
8
.
6
×
10
−
10
100
TABLE L:
(Continued).
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
energy equivalent
m
h
c
2
4
.
499 538 64(22)
×
10
−
10
J
5
.
0
×
10
−
8
in MeV
2808
.
391 383(70)
MeV
2
.
5
×
10
−
8
helion-electron mass ratio
m
h
/m
e
5495
.
885 2765(52)
9
.
5
×
10
−
10
helion-proton mass ratio
m
h
/m
p
2
.
993 152 6713(26)
8
.
7
×
10
−
10
helion molar mass
N
A
m
h
M
(h)
, M
h
3
.
014 932 2473(26)
×
10
−
3
kg mol
−
1
8
.
6
×
10
−
10
shielded helion magnetic moment
µ
′
h
−
1
.
074 552 982(30)
×
10
−
26
J T
−
1
2
.
8
×
10
−
8
(gas, sphere, 25
â—¦
C)
to Bohr magneton ratio
µ
′
h
/µ
B
−
1
.
158 671 471(14)
×
10
−
3
1
.
2
×
10
−
8
to nuclear magneton ratio
µ
′
h
/µ
N
−
2
.
127 497 718(25)
1
.
2
×
10
−
8
shielded helion to proton
magnetic moment ratio
µ
′
h
/µ
p
−
0
.
761 766 558(11)
1
.
4
×
10
−
8
(gas, sphere, 25
â—¦
C)
shielded helion to shielded proton
magnetic moment ratio
µ
′
h
/µ
′
p
−
0
.
761 786 1313(33)
4
.
3
×
10
−
9
(gas/H
2
O, spheres, 25
â—¦
C)
shielded helion gyromagnetic
ratio 2
|
µ
′
h
|
/
¯
h
γ
′
h
2
.
037 894 730(56)
×
10
8
s
−
1
T
−
1
2
.
8
×
10
−
8
(gas, sphere, 25
â—¦
C)
γ
′
h
/
2
Ï€
32
.
434 101 98(90)
MHz T
−
1
2
.
8
×
10
−
8
Alpha particle,
α
alpha particle mass
m
α
6
.
644 656 20(33)
×
10
−
27
kg
5
.
0
×
10
−
8
in u,
m
α
=
A
r
(
α
) u (alpha particle
relative atomic mass times u)
4
.
001 506 179 127(62)
u
1
.
5
×
10
−
11
energy equivalent
m
α
c
2
5
.
971 919 17(30)
×
10
−
10
J
5
.
0
×
10
−
8
in MeV
3727
.
379 109(93)
MeV
2
.
5
×
10
−
8
alpha particle to electron mass ratio
m
α
/m
e
7294
.
299 5365(31)
4
.
2
×
10
−
10
alpha particle to proton mass ratio
m
α
/m
p
3
.
972 599 689 51(41)
1
.
0
×
10
−
10
alpha particle molar mass
N
A
m
α
M
(
α
)
, M
α
4
.
001 506 179 127(62)
×
10
−
3
kg mol
−
1
1
.
5
×
10
−
11
PHYSICOCHEMICAL
Avogadro constant
N
A
, L
6
.
022 141 79(30)
×
10
23
mol
−
1
5
.
0
×
10
−
8
atomic mass constant
m
u
=
1
12
m
(
12
C) = 1 u
m
u
1
.
660 538 782(83)
×
10
−
27
kg
5
.
0
×
10
−
8
= 10
−
3
kg mol
−
1
/N
A
energy equivalent
m
u
c
2
1
.
492 417 830(74)
×
10
−
10
J
5
.
0
×
10
−
8
in MeV
931
.
494 028(23)
MeV
2
.
5
×
10
−
8
Faraday constant
f
N
A
e
F
96 485
.
3399(24)
C mol
−
1
2
.
5
×
10
−
8
molar Planck constant
N
A
h
3
.
990 312 6821(57)
×
10
−
10
J s mol
−
1
1
.
4
×
10
−
9
N
A
hc
0
.
119 626 564 72(17)
J m mol
−
1
1
.
4
×
10
−
9
molar gas constant
R
8
.
314 472(15)
J mol
−
1
K
−
1
1
.
7
×
10
−
6
Boltzmann constant
R/N
A
k
1
.
380 6504(24)
×
10
−
23
J K
−
1
1
.
7
×
10
−
6
in eV K
−
1
8
.
617 343(15)
×
10
−
5
eV K
−
1
1
.
7
×
10
−
6
k/h
2
.
083 6644(36)
×
10
10
Hz K
−
1
1
.
7
×
10
−
6
k/hc
69
.
503 56(12)
m
−
1
K
−
1
1
.
7
×
10
−
6
molar volume of ideal gas
RT /p
T
= 273
.
15 K
, p
= 101
.
325 kPa
V
m
22
.
413 996(39)
×
10
−
3
m
3
mol
−
1
1
.
7
×
10
−
6
f
The numerical value of
F
to be used in coulometric chemical measurements is 96 485
.
3401(48) [5
.
0
×
10
−
8
] when the relevant current
is measured in terms of representations of the volt and ohm based on the Josephson and quantum Hall effects and the internationally
adopted conventional values of the Josephson and von Klitzing constants
K
J
−
90
and
R
K
−
90
given in Table LII.
TABLE L:
(Continued).
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
Loschmidt constant
N
A
/V
m
n
0
2
.
686 7774(47)
×
10
25
m
−
3
1
.
7
×
10
−
6
T
= 273
.
15 K
, p
= 100 kPa
V
m
22
.
710 981(40)
×
10
−
3
m
3
mol
−
1
1
.
7
×
10
−
6
Sackur-Tetrode constant
(absolute entropy constant)
g
5
2
+ ln[(2
Ï€
m
u
kT
1
/h
2
)
3
/
2
kT
1
/p
0
]
T
1
= 1 K
, p
0
= 100 kPa
S
0
/R
−
1
.
151 7047(44)
3
.
8
×
10
−
6
T
1
= 1 K
, p
0
= 101
.
325 kPa
−
1
.
164 8677(44)
3
.
8
×
10
−
6
Stefan-Boltzmann constant
(
Ï€
2
/
60)
k
4
/
¯
h
3
c
2
σ
5
.
670 400(40)
×
10
−
8
W m
−
2
K
−
4
7
.
0
×
10
−
6
ï¬rst radiation constant 2
Ï€
hc
2
c
1
3
.
741 771 18(19)
×
10
−
16
W m
2
5
.
0
×
10
−
8
ï¬rst radiation constant for spectral radiance 2
hc
2
c
1L
1
.
191 042 759(59)
×
10
−
16
W m
2
sr
−
1
5
.
0
×
10
−
8
second radiation constant
hc/k
c
2
1
.
438 7752(25)
×
10
−
2
m K
1
.
7
×
10
−
6
Wien displacement law constants
b
=
λ
max
T
=
c
2
/
4
.
965 114 231
...
b
2
.
897 7685(51)
×
10
−
3
m K
1
.
7
×
10
−
6
b
′
=
ν
max
/T
= 2
.
821 439 372
... c/c
2
b
′
5
.
878 933(10)
×
10
10
Hz K
−
1
1
.
7
×
10
−
6
g
The entropy of an ideal monoatomic gas of relative atomic mass
A
r
is given by
S
=
S
0
+
3
2
R
ln
A
r
−
R
ln(
p/p
0
) +
5
2
R
ln(
T /
K)
.
102
TABLE LI The variances, covariances, and correlation coefficients of the values of a selected group of constants based on the
2006 CODATA adjustment. The numbers in bold above the main diagonal are 10
16
times the numerical values of the relative
covariances; the numbers in bold on the main diagonal are 10
16
times the numerical values of the relative variances; and the
numbers in italics below the main diagonal are the correlation coefficients.
a
α
h
e
m
e
N
A
m
e
/m
µ
F
α
0
.
0047
0
.
0002
0
.
0024
−
0
.
0092
0
.
0092
−
0
.
0092
0
.
0116
h
0
.
0005
24
.
8614
12
.
4308
24
.
8611
−
24
.
8610
−
0
.
0003
−
12
.
4302
e
0
.
0142
0
.
9999
6
.
2166
12
.
4259
−
12
.
4259
−
0
.
0048
−
6
.
2093
m
e
−
0
.
0269
0
.
9996
0
.
9992
24
.
8795
−
24
.
8794
0
.
0180
−
12
.
4535
N
A
0
.
0269
−
0
.
9996
−
0
.
9991
−
1
.
0000
24
.
8811
−
0
.
0180
12
.
4552
m
e
/m
µ
−
0
.
0528
0
.
0000
−
0
.
0008
0
.
0014
−
0
.
0014
6
.
4296
−
0
.
0227
F
0
.
0679
−
0
.
9975
−
0
.
9965
−
0
.
9990
0
.
9991
−
0
.
0036
6
.
2459
a
The relative covariance is
u
r
(
x
i
, x
j
) =
u
(
x
i
, x
j
)
/
(
x
i
x
j
), where
u
(
x
i
, x
j
) is the covariance of
x
i
and
x
j
; the relative variance is
u
2
r
(
x
i
) =
u
r
(
x
i
, x
i
): and the correlation coefficient is
r
(
x
i
, x
j
) =
u
(
x
i
, x
j
)
/
[
u
(
x
i
)
u
(
x
j
)].
TABLE LII Internationally adopted values of various quantities.
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
relative atomic mass
a
of
12
C
A
r
(
12
C)
12
(exact)
molar mass constant
M
u
1
×
10
−
3
kg mol
−
1
(exact)
molar mass of
12
C
M
(
12
C)
12
×
10
−
3
kg mol
−
1
(exact)
conventional value of Josephson constant
b
K
J
−
90
483 597.9
GHz V
−
1
(exact)
conventional value of von Klitzing constant
c
R
K
−
90
25 812.807
Ω
(exact)
standard atmosphere
101 325
Pa
(exact)
a
The relative atomic mass
A
r
(
X
) of particle
X
with mass
m
(
X
) is defined by
A
r
(
X
) =
m
(
X
)
/m
u
, where
m
u
=
m
(
12
C)
/
12 =
M
u
/N
A
=
1 u is the atomic mass constant,
M
u
is the molar mass constant,
N
A
is the Avogadro constant, and u is the unified atomic mass unit.
Thus the mass of particle
X
is
m
(
X
) =
A
r
(
X
) u and the molar mass of
X
is
M
(
X
) =
A
r
(
X
)
M
u
.
b
This is the value adopted internationally for realizing representations of the volt using the Josephson effect.
c
This is the value adopted internationally for realizing representations of the ohm using the quantum Hall effect.
TABLE LIII Values of some x-ray-related quantities based on the 2006 CODATA adjustment of the values of the constants.
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
Cu x unit:
λ
(CuK
α
1
)
/
1 537
.
400
xu(CuK
α
1
)
1
.
002 076 99(28)
×
10
−
13
m
2
.
8
×
10
−
7
Mo x unit:
λ
(MoK
α
1
)
/
707
.
831
xu(MoK
α
1
)
1
.
002 099 55(53)
×
10
−
13
m
5
.
3
×
10
−
7
Ëš
angstrom star:
λ
(WK
α
1
)
/
0
.
209 010 0
Ëš
A
∗
1
.
000 014 98(90)
×
10
−
10
m
9
.
0
×
10
−
7
lattice parameter
a
of Si
a
543
.
102 064(14)
×
10
−
12
m
2
.
6
×
10
−
8
(in vacuum, 22.5
â—¦
C)
{
220
}
lattice spacing of Si
a/
√
8
d
220
192
.
015 5762(50)
×
10
−
12
m
2
.
6
×
10
−
8
(in vacuum, 22.5
â—¦
C)
molar volume of Si
M
(Si)
/Ï
(Si) =
N
A
a
3
/
8
V
m
(Si)
12
.
058 8349(11)
×
10
−
6
m
3
mol
−
1
9
.
1
×
10
−
8
(in vacuum, 22.5
â—¦
C)
a
This is the lattice parameter (unit cell edge length) of an ideal single crystal of naturally occurring Si free of impurities and imperfections,
and is deduced from measurements on extremely pure and nearly perfect single crystals of Si by correcting for the effects of impurities.
103
TABLE LIV The values in SI units of some non-SI units based on the 2006 CODATA adjustment of the values of the constants.
Relative std.
Quantity
Symbol
Numerical value
Unit
uncert.
u
r
Non-SI units accepted for use with the SI
electron volt: (
e/
C) J
eV
1
.
602 176 487(40)
×
10
−
19
J
2
.
5
×
10
−
8
(uniï¬ed) atomic mass unit:
1 u =
m
u
=
1
12
m
(
12
C)
u
1
.
660 538 782(83)
×
10
−
27
kg
5
.
0
×
10
−
8
= 10
−
3
kg mol
−
1
/N
A
Natural units (n.u.)
n.u. of velocity:
speed of light in vacuum
c, c
0
299 792 458
m s
−
1
(exact)
n.u. of action:
reduced Planck constant (
h/
2
Ï€
)
¯
h
1
.
054 571 628(53)
×
10
−
34
J s
5
.
0
×
10
−
8
in eV s
6
.
582 118 99(16)
×
10
−
16
eV s
2
.
5
×
10
−
8
in MeV fm
¯
hc
197
.
326 9631(49)
MeV fm
2
.
5
×
10
−
8
n.u. of mass:
electron mass
m
e
9
.
109 382 15(45)
×
10
−
31
kg
5
.
0
×
10
−
8
n.u. of energy
m
e
c
2
8
.
187 104 38(41)
×
10
−
14
J
5
.
0
×
10
−
8
in MeV
0
.
510 998 910(13)
MeV
2
.
5
×
10
−
8
n.u. of momentum
m
e
c
2
.
730 924 06(14)
×
10
−
22
kg m s
−
1
5
.
0
×
10
−
8
in MeV/
c
0
.
510 998 910(13)
MeV/
c
2
.
5
×
10
−
8
n.u. of length (¯
h/m
e
c
)
λ
C
386
.
159 264 59(53)
×
10
−
15
m
1
.
4
×
10
−
9
n.u. of time
¯
h/m
e
c
2
1
.
288 088 6570(18)
×
10
−
21
s
1
.
4
×
10
−
9
Atomic units (a.u.)
a.u. of charge:
elementary charge
e
1
.
602 176 487(40)
×
10
−
19
C
2
.
5
×
10
−
8
a.u. of mass:
electron mass
m
e
9
.
109 382 15(45)
×
10
−
31
kg
5
.
0
×
10
−
8
a.u. of action:
reduced Planck constant (
h/
2
Ï€
)
¯
h
1
.
054 571 628(53)
×
10
−
34
J s
5
.
0
×
10
−
8
a.u. of length:
Bohr radius (bohr) (
α/
4
Ï€
R
∞
)
a
0
0
.
529 177 208 59(36)
×
10
−
10
m
6
.
8
×
10
−
10
a.u. of energy:
Hartree energy (hartree)
E
h
4
.
359 743 94(22)
×
10
−
18
J
5
.
0
×
10
−
8
(
e
2
/
4
Ï€
Ç«
0
a
0
= 2
R
∞
hc
=
α
2
m
e
c
2
)
a.u. of time
¯
h/E
h
2
.
418 884 326 505(16)
×
10
−
17
s
6
.
6
×
10
−
12
a.u. of force
E
h
/a
0
8
.
238 722 06(41)
×
10
−
8
N
5
.
0
×
10
−
8
a.u. of velocity (
αc
)
a
0
E
h
/
¯
h
2
.
187 691 2541(15)
×
10
6
m s
−
1
6
.
8
×
10
−
10
a.u. of momentum
¯
h/a
0
1
.
992 851 565(99)
×
10
−
24
kg m s
−
1
5
.
0
×
10
−
8
a.u. of current
eE
h
/
¯
h
6
.
623 617 63(17)
×
10
−
3
A
2
.
5
×
10
−
8
a.u. of charge density
e/a
3
0
1
.
081 202 300(27)
×
10
12
C m
−
3
2
.
5
×
10
−
8
a.u. of electric potential
E
h
/e
27
.
211 383 86(68)
V
2
.
5
×
10
−
8
a.u. of electric ï¬eld
E
h
/ea
0
5
.
142 206 32(13)
×
10
11
V m
−
1
2
.
5
×
10
−
8
a.u. of electric ï¬eld gradient
E
h
/ea
2
0
9
.
717 361 66(24)
×
10
21
V m
−
2
2
.
5
×
10
−
8
a.u. of electric dipole moment
ea
0
8
.
478 352 81(21)
×
10
−
30
C m
2
.
5
×
10
−
8
a.u. of electric quadrupole moment
ea
2
0
4
.
486 551 07(11)
×
10
−
40
C m
2
2
.
5
×
10
−
8
a.u. of electric polarizability
e
2
a
2
0
/E
h
1
.
648 777 2536(34)
×
10
−
41
C
2
m
2
J
−
1
2
.
1
×
10
−
9
a.u. of 1
st
hyperpolarizability
e
3
a
3
0
/E
2
h
3
.
206 361 533(81)
×
10
−
53
C
3
m
3
J
−
2
2
.
5
×
10
−
8
a.u. of 2
nd
hyperpolarizability
e
4
a
4
0
/E
3
h
6
.
235 380 95(31)
×
10
−
65
C
4
m
4
J
−
3
5
.
0
×
10
−
8
a.u. of magnetic flux density
¯
h/ea
2
0
2
.
350 517 382(59)
×
10
5
T
2
.
5
×
10
−
8
a.u. of magnetic
dipole moment (2
µ
B
)
¯
he/m
e
1
.
854 801 830(46)
×
10
−
23
J T
−
1
2
.
5
×
10
−
8
a.u. of magnetizability
e
2
a
2
0
/m
e
7
.
891 036 433(27)
×
10
−
29
J T
−
2
3
.
4
×
10
−
9
a.u. of permittivity (10
7
/c
2
)
e
2
/a
0
E
h
1
.
112 650 056
. . .
×
10
−
10
F m
−
1
(exact)
104
TABLE LV The values of some energy equivalents derived from the relations
E
=
mc
2
=
hc/λ
=
hν
=
kT
, and based on the
2006 CODATA adjustment of the values of the constants; 1 eV = (
e/
C) J, 1 u =
m
u
=
1
12
m
(
12
C) = 10
−
3
kg mol
−
1
/N
A
, and
E
h
= 2
R
∞
hc
=
α
2
m
e
c
2
is the Hartree energy (hartree).
Relevant unit
J
kg
m
−
1
Hz
1 J
(1 J) =
(1 J)/
c
2
=
(1 J)/
hc
=
(1 J)/
h
=
1 J
1
.
112 650 056
. . .
×
10
−
17
kg 5
.
034 117 47(25)
×
10
24
m
−
1
1
.
509 190 450(75)
×
10
33
Hz
1 kg
(1 kg)
c
2
=
(1 kg) =
(1 kg)
c/h
=
(1 kg)
c
2
/h
=
8
.
987 551 787
. . .
×
10
16
J
1 kg
4
.
524 439 15(23)
×
10
41
m
−
1
1
.
356 392 733(68)
×
10
50
Hz
1 m
−
1
(1 m
−
1
)
hc
=
(1 m
−
1
)
h/c
=
(1 m
−
1
) =
(1 m
−
1
)
c
=
1
.
986 445 501(99)
×
10
−
25
J 2
.
210 218 70(11)
×
10
−
42
kg 1 m
−
1
299 792 458 Hz
1 Hz
(1 Hz)
h
=
(1 Hz)
h/c
2
=
(1 Hz)/
c
=
(1 Hz) =
6
.
626 068 96(33)
×
10
−
34
J 7
.
372 496 00(37)
×
10
−
51
kg 3
.
335 640 951
. . .
×
10
−
9
m
−
1
1 Hz
1 K
(1 K)
k
=
(1 K)
k/c
2
=
(1 K)
k/hc
=
(1 K)
k/h
=
1
.
380 6504(24)
×
10
−
23
J
1
.
536 1807(27)
×
10
−
40
kg
69
.
503 56(12) m
−
1
2
.
083 6644(36)
×
10
10
Hz
1 eV
(1 eV) =
(1 eV)
/c
2
=
(1 eV)
/hc
=
(1 eV)
/h
=
1
.
602 176 487(40)
×
10
−
19
J 1
.
782 661 758(44)
×
10
−
36
kg 8
.
065 544 65(20)
×
10
5
m
−
1
2
.
417 989 454(60)
×
10
14
Hz
1 u
(1 u)
c
2
=
(1 u) =
(1 u)
c/h
=
(1 u)
c
2
/h
=
1
.
492 417 830(74)
×
10
−
10
J 1
.
660 538 782(83)
×
10
−
27
kg 7
.
513 006 671(11)
×
10
14
m
−
1
2
.
252 342 7369(32)
×
10
23
Hz
1
E
h
(1
E
h
) =
(1
E
h
)
/c
2
=
(1
E
h
)
/hc
=
(1
E
h
)
/h
=
4
.
359 743 94(22)
×
10
−
18
J 4
.
850 869 34(24)
×
10
−
35
kg 2
.
194 746 313 705(15)
×
10
7
m
−
1
6
.
579 683 920 722(44)
×
10
15
Hz
105
TABLE LVI The values of some energy equivalents derived from the relations
E
=
mc
2
=
hc/λ
=
hν
=
kT
, and based on the
2006 CODATA adjustment of the values of the constants; 1 eV = (
e/
C) J, 1 u =
m
u
=
1
12
m
(
12
C) = 10
−
3
kg mol
−
1
/N
A
, and
E
h
= 2
R
∞
hc
=
α
2
m
e
c
2
is the Hartree energy (hartree).
Relevant unit
K
eV
u
E
h
1 J
(1 J)/
k
=
(1 J) =
(1 J)/
c
2
=
(1 J) =
7
.
242 963(13)
×
10
22
K
6
.
241 509 65(16)
×
10
18
eV
6
.
700 536 41(33)
×
10
9
u
2
.
293 712 69(11)
×
10
17
E
h
1 kg
(1 kg)
c
2
/k
=
(1 kg)
c
2
=
(1 kg) =
(1 kg)
c
2
=
6
.
509 651(11)
×
10
39
K
5
.
609 589 12(14)
×
10
35
eV
6
.
022 141 79(30)
×
10
26
u
2
.
061 486 16(10)
×
10
34
E
h
1 m
−
1
(1 m
−
1
)
hc/k
=
(1 m
−
1
)
hc
=
(1 m
−
1
)
h/c
=
(1 m
−
1
)
hc
=
1
.
438 7752(25)
×
10
−
2
K 1
.
239 841 875(31)
×
10
−
6
eV 1
.
331 025 0394(19)
×
10
−
15
u 4
.
556 335 252 760(30)
×
10
−
8
E
h
1 Hz
(1 Hz)
h/k
=
(1 Hz)
h
=
(1 Hz)
h/c
2
=
(1 Hz)
h
=
4
.
799 2374(84)
×
10
−
11
K 4
.
135 667 33(10)
×
10
−
15
eV 4
.
439 821 6294(64)
×
10
−
24
u 1
.
519 829 846 006(10)
×
10
−
16
E
h
1 K
(1 K) =
(1 K)
k
=
(1 K)
k/c
2
=
(1 K)
k
=
1 K
8
.
617 343(15)
×
10
−
5
eV
9
.
251 098(16)
×
10
−
14
u
3
.
166 8153(55)
×
10
−
6
E
h
1 eV
(1 eV)/
k
=
(1 eV) =
(1 eV)
/c
2
=
(1 eV) =
1
.
160 4505(20)
×
10
4
K
1 eV
1
.
073 544 188(27)
×
10
−
9
u
3
.
674 932 540(92)
×
10
−
2
E
h
1 u
(1 u)
c
2
/k
=
(1 u)
c
2
=
(1 u) =
(1 u)
c
2
=
1
.
080 9527(19)
×
10
13
K
931
.
494 028(23)
×
10
6
eV
1 u
3
.
423 177 7149(49)
×
10
7
E
h
1
E
h
(1
E
h
)
/k
=
(1
E
h
) =
(1
E
h
)
/c
2
=
(1
E
h
) =
3
.
157 7465(55)
×
10
5
K
27
.
211 383 86(68) eV
2
.
921 262 2986(42)
×
10
−
8
u 1
E
h