independent of the energy of the
incoming particle. The number of
electron-hole pairs ultimately formed is
thus directly proportional to the energy
of the particle. The electric field in the
depletion region sweeps the electrons
to one terminal and the holes to the
other. The resultant charge pulse is
integrated in a charge sensitive
preamplifier to produce a voltage pulse.
The thickness of the depletion region
depends upon the applied bias voltage,
so that higher voltages give a thicker
region, capable of stopping more
energetic particles. The capacitance of
the detector is given by
Where A represent the surface of the
junction. It is typically 20% higher than
the active area of the detector.
Application
Note
PIPS DETECT
PIPS DETECT
PIPS DETECT
PIPS DETECT
PIPS DETECTORS
ORS
ORS
ORS
ORS
General Characteristics
General Characteristics
General Characteristics
General Characteristics
General Characteristics
Silicon charged particle detectors
produced by diffused-junction or
surface barrier technology have served
the scientific and industrial community
for several decades. Current applica-
tions, however, demand detectors
having lower noise, better resolution,
higher efficiency, greater reliability,
more ruggedness and higher stability
than those older technologies can
produce. Canberra’s Passivated
Implanted Planar Silicon (PIPS)
detector, based on 3 µ CMOS technol-
ogy, brings all these advantages to the
field of charged particle detectors.
Using modern semiconductor process-
ing techniques, proprietary processes,
and device designs, Canberra PIPS
detectors widely surpass the perfor-
mance of conventional charged particle
detectors in almost every respect.
Salient advantages of PIPS technology
include the following:
• Buried Ion Implanted Junctions
• SiO
2
Passivation
• Low Leakage Current
• Low Noise
• Thin windows (< 500 Å eq. Si.)
• Ruggedness (cleanable surface)
• Bakeable at High Temperatures
Operating Principle
Operating Principle
Operating Principle
Operating Principle
Operating Principle
In the detection process, particles are
stopped in the depletion region,
forming electron-hole pairs. The
energy necessary to form a single
electron-hole pair depends on the
detector material, but is essentially
ALPHA PIPS DETECTORS –PROPERTIES and APPLICATIONS
W represents the thickness of the
detector and is given by:
W = 0.562
ρ
V
V is the applied bias in Volts and
ρ
the
resistance in ohm-cm. It is thus
possible to have a partially depleted or
a fully depleted detector with and
without overvoltage as illustrated in
Figure 1.
The noise level of charge-sensitive
preamplifiers is usually given by the
manufacturer as a certain value for zero
input capacitance. The noise level
increases with capacitance and this rate
of increase is also specified. The
detector capacitance is reduced at
higher voltages, so that the lowest noise
and best resolution are obtained at
higher voltages within the recom-
mended range. At voltages above that
recommended by the manufacturer, the
reverse leakage current will likely
increase, causing excessive noise and a
loss of resolution.
Figure 1
Thickness W of the depletion layer as a function of applied bias
a: partially depleted detector
b: fully depleted detector
c: fully depleted detector with overvoltage
Canberra Industries, Inc., 800 Research Parkway, Meriden, CT 06450, USA Tel: (203) 238-2351, FAX: (203) 235-1347
Canberra Semiconductor, N.V., Lammerdries 25, 2250 Olen, Belgium Tel. (32-014) 221975 TLX: 72423 CANDES
C = 1.05 A
W
- survey of nuclear sites
- geological and geomorphological
studies (such as U-Th dating etc.)
Note however that the obtainable
resolution depends not only on the
detector, but also on external factors
such as source preparation, operating
pressure, source-detector distance,
and especially preamplifier and/or
spectrometer quality. At lower bias
voltages and resistivities, the detectors
are partially depleted. Alpha PIPS
detectors have a minimum depletion
depth of 140 microns.
Table 1 shows the detector specifica-
tions and operating characteristics for
the A Series PIPS detectors.
The A Series PIPS
The A Series PIPS
The A Series PIPS
The A Series PIPS
The A Series PIPS
Detector
Detector
Detector
Detector
Detectors
s
s
s
s
Key Properties and
Key Properties and
Key Properties and
Key Properties and
Key Properties and
Applications
Applications
Applications
Applications
Applications
The A Series PIPS Detectors are
optimized for Alpha particle detection
or Alpha Spectroscopy applications
which require high resolution, high
sensitivity and low background.
High resolution is achieved by main-
taining a uniformly thin entrance
window over the detector surface and
by reducing leakage current and noise.
Alpha resolution of < 17 keV (FWHM)
is routinely achieved for a 450 mm
2
active area detector.
High sensitivity is enhanced by the thin
window and ensured by a minimum
depletion depth of 140 microns which
TABLE 1
MODEL
A300
A450
A600
A900
A1200
Active Area (mm²)
300
450
600
900
1200
Active Diameter (mm)
19.5
23.9
27.6
33.9
39.1
Thickness (min/max µ)
150/315
150/315
150/315
150/315
150/315
Bias (min/max V)
+20/100
+20/100
+20/100
+20/100
+20/100
Bias (recommended V)
+20/80
+20/80
+20/80
+20/80
+20/80
Si-Resistivity (min ohm-cm)
2000
2000
2000
2000
2000
Operating Temp (min/max °C)
-20/+40
-20/+40
-20/+40
-20/+40
-20/+40
Storage Temp (max °C)
+100
+100
+100
+100
+100
Leakage current (typ/max)
35/70
50/100
60/120
100/200
150/300
nanoamps at 25 °C
1
Alpha Resolution
2
17/19
18/20
23/25
25/30
30/37
keV (FWHM)
Absolute Efficiency (%)
3
at 2 mm spacing
37
40
42
44
45
at 5 mm spacing
24
28
31
35
37
at 15 mm spacing
7
11
12
16
19
1) These values are 5 to 10 times smaller than those of corresponding surface barrier detectors.
2) For the 5.486 MeV Alpha line of
241
Am at 15 mm Detector-Source spacing using standard Canberra electronics. Detectors are not tested with an alpha source
in order to avoid low level contamination. Beta resolution is 5 keV less than Alpha resolution and is approximated by pulser line width.
3) With a source diameter of 15 mm.
will absorb Alpha particles of up to 15
MeV thus covering the complete range
of all Alpha emitting radionuclides
(Appendix 1).
Absolute efficiency of up to 40% can
be achieved.
Low background is achieved through
the use of carefully selected packaging
materials and through clean manufac-
turing and testing procedures.
Backgrounds of less than 0.05 cts/hr
cm
2
are routinely achieved.
The A series PIPS find applications in
widely different scientific disciplines
such as:
- radiochemical analysis
- environmental studies and
surveys
- health physics
It is seen that even for values of h as
small as 2 mm, the increase of the peak
width stays below 50%.
F
F
F
F
Factor
actor
actor
actor
actors Influencing
s Influencing
s Influencing
s Influencing
s Influencing
Resolution and
Resolution and
Resolution and
Resolution and
Resolution and
Efficienc
Efficienc
Efficienc
Efficienc
Efficiency
y
y
y
y
Detecto
Detecto
Detecto
Detecto
Detector-
r-
r-
r-
r-Source Distance
Source Distance
Source Distance
Source Distance
Source Distance
All Alpha particles reaching the active
surface of an A-series detector will be
counted. The counting efficiency is
thus given by the geometrical
efficiency N under which the detector
sees the source. For the case of a
circular detector coaxial to a circular
isotropic source disc, this solid angle
can be computed by Monte-Carlo
calculations
1
and is available in
tabulated form
2
.
Figures 2, 3, 4 and 5 give Alpha
efficiencies based on such solid angle
evaluations and experimental verifica-
tions (expressed in % of the total
emitted Alpha particles for various
detectors as a function of source to
detector distance for 3 different ideal
sources with diameters of 15, 25 and
32 mm.) Actual efficiencies may be
slightly different, especially at small
source detector distances, due to
factors such as self absorption in the
source, etc. Efficiencies of up to about
40% are obtainable.
When the source approaches the
detector, line broadening (FWHM) is
expected, as the mean slope of the
alpha particles entering the detector is
increased, resulting in an effectively
increased thickness of the entrance
window and subsequent higher energy
straggling
3
. For Alpha PIPS this
energy straggling is minimized due to
the very thin entrance window of 500
Å. Figure 6 shows the experimental
mean percent variation of the resolu-
tion for a 300 to 600 mm
2
detector
as a function of the source detector
distance, h.
For a model A300-17 AM detector the
alpha resolution at 3 mm source to
detector distance is thus expected to be:
R = 17(1+0.41) = 25 keV (FWHM).
Figure 5
Geometric efficiency as a function of
source-detector distance for a circular
32 mm diameter source coaxial with
the detector.
Figure 2
Geometric efficiency as a function of the
source-detector distance for a circular
15 mm diameter source coaxial with
the detector.
Figure 3
Geometric efficiency as a function of
source-detector distance for a circular
25 mm diameter source coaxial with
the detector.
Figure 4
Geometric efficiency as a function of
source-detector distance for a circular
25 mm diameter source coaxial with
the detector.
When estimating the source thickness
of a non carrier-free source, all isotopes
deposited together with the isotope of
interest must be considered. This can
be due either to a different isotope of
the same element or to the simulta-
neous deposition of other elements
during source preparation.
Problems can also arise with very
intense sources as self-absorption is
proportional to the total source activity.
For a same total activity the specific
activity can be reduced by choosing a
larger source diameter. In this case,
preference should be given to a
detector with a diameter about equal to
that of the source in order to increase
its efficiency (Figures 2-5) and to
reduce the energy straggling as fewer
Alpha particles will strike the detector
at an acute angle.
F
F
F
F
Factor
actor
actor
actor
actors Influencing
s Influencing
s Influencing
s Influencing
s Influencing
Contamination and
Contamination and
Contamination and
Contamination and
Contamination and
Stability
Stability
Stability
Stability
Stability
Oil Contamination
Oil Contamination
Oil Contamination
Oil Contamination
Oil Contamination
Typical Alpha Spectroscopy Systems
use a rotary vane vacuum pump to
evacuate the Alpha Spectrometer(s).
When static conditions are established
in the vacuum system (the ultimate
pressure has been reached) and there is
no substantial gas flow towards the
pump, oil particles can back-stream
towards the spectrometer and deposit
on the detector and the source surfaces.
The same can happen in a more
dramatic fashion if the pump is
disabled and the spectrometer draws
air backwards through the manifold
connecting the two.
For this reason it is recommended that
a backstreaming filter be used between
the pump and the plumbing to prevent
oil contamination.
Particulate and Recoil
Particulate and Recoil
Particulate and Recoil
Particulate and Recoil
Particulate and Recoil
Contamination
Contamination
Contamination
Contamination
Contamination
Contamination of detectors can take
place when particles from sources
gravitate to the detector surface and
stick there or are splattered, sputtered,
or splashed on the detector surface by
the recoil energy imparted to the
nucleus of an Alpha-emitting atom.
In the latter case the energy of the
particulates may be sufficient to
implant them in the detector so that
they cannot be removed non-
destructively.
Much of the casual contamination can
be removed from PIPS detectors by
cleaning with a cotton ball saturated
with acetone. Vigorous scrubbing will
not harm the PIPS detector.
Recoil contamination is almost never
100% removable so it is best avoided
by careful sample preparation, avoiding
hot samples, or by using the techniques
reported by Sill & Olsen
5
which
involve operating the spectrometer with
an air barrier and a bias voltage
between detector and source. They
show that recoil contamination can be
reduced by a factor of up to 1000 if an
air layer of about 12mg/cm
2
exists
between the detector and source and if
the source is biased negatively by a few
volts. The air gap will increase the
width of alpha peaks by a few keV
which is probably acceptable in all but
the most demanding of applications.
Canberra Alpha Spectrometers and
Accessories are available with sample
bias, pressure control, and monitoring
capability.
Figure 6
Empirical mean percent increase of peak
line width.
Source diameter: 15 mm
Detector area: 300 to 600 mm
2
Source Thickness
Source Thickness
Source Thickness
Source Thickness
Source Thickness
Sources must be homogeneous and thin
in order to avoid energy straggling due
to self-absorption
4
. Self-absorption is
proportional to the thickness of the
source and inversely proportional to the
specific activity. For typical values of
specific activities in the order of 100
Bq/cm
2
, the self-absorption is generally
negligible for carrier-free sources.
Note, however, that the thickness of the
carrier-free source depends on the
transition probability of the isotope in
question and thus increases with
increasing half-life. Expressed in
energy loss, it is on the order of 0.03
keV for “short” lived isotopes such
as
239
Pu (2.4 x 10
4
y) and
230
Th
(7.5 x 10
4
y), while for “long” lived
isotopes such as
238
U (4.7 x 10
9
y) it is
on the order of 5 keV.
Stability
Stability
Stability
Stability
Stability
Both long-term and temperature
stability are important in detectors used
for Alpha Spectroscopy because count
times are often many hours or days and
gain shifts during data accumulation
lead to erroneous or unusable spectra.
Long Term Stability
Long Term Stability
Long Term Stability
Long Term Stability
Long Term Stability
The long-term stability is affected by
the impact of the environment on
detector junctions. SSB detectors
sometimes fail with prolonged ex-
posure to room atmosphere and at other
times they fail when operated for
prolonged periods under high vacuum.
This instability is caused by the epoxy
edge encapsulation that is required for
this type of detector. The PIPS detector
has junctions that are buried in the
silicon bulk. No epoxy encapsulation is
needed or used so the PIPS detector has
intrinsic long-term stability.
Temperature Stability
Temperature Stability
Temperature Stability
Temperature Stability
Temperature Stability
The leakage current of silicon diodes
doubles for every 5.5 to 7.5 °C change
in ambient temperature. Since the
preamp H.V. bias resistor is a noise
contributor, it is necessarily of high
value, typically 100 megohm. With a
SSB detector having leakage current of
0.5 µA, the change in bias voltage at
the detector for a 2 °C change in
ambient temperature can be as much as
13 V. This is enough bias change to
affect overall gain of the detector-
preamplifier by a substantial amount.
The PIPS detector has a typical leakage
current of about 1/10 that of SSB or
Diffused Junction detectors.
Consequently system gain change as
a function of temperature is proportion-
ally less, so that up to operational
temperature of 35 °C no significant
peak shifts are observed.
Where A(s) represents the area of the
source. In the case where the source
area equals the detector area Figure 7
gives this SMDA in function of the
detector size (expressed in mm
2
) for
three different source to detector
distances of 2, 5 and 15 mm, respec-
tively. The advantages of choosing a
large diameter detector is readily seen.
In order to maintain good resolution
and high efficiency (and thus a small
SMDA) the source diameter should not
exceed the detector diameter.
The Minim
The Minim
The Minim
The Minim
The Minimum
um
um
um
um
Detectab
Detectab
Detectab
Detectab
Detectable Activity
le Activity
le Activity
le Activity
le Activity
MD
MD
MD
MD
MDA
A
A
A
A
For Single Radionuclide
For Single Radionuclide
For Single Radionuclide
For Single Radionuclide
For Single Radionuclide
Samples
Samples
Samples
Samples
Samples
The minimum detectable activity
(MDA) is a measure of the lowest
level at which sample activity can be
distinguished from background. For a
95% confidence limit it is given by
6
:
MDA (Bq) = 2.71 + 4.65 b
t N P
t = counting time
N = counting efficiency
P = yield of the Alpha in question
b = background counts
The two detector-bound parameters,
background (b) and the efficiency (N)
are particularly favorable in the case of
an Alpha PIPS detector as seen from
Table 1 and Figures 2-5. For a 450
mm
2
detector (N = 0.40, b = 6 cts/day)
and an overnight run (t = 15 hr =
54 000 s) one has:
MDA = 0.54 mBq
(100% yield is assumed.)
This is a worst case condition which
assumes that all the background counts
are in the peak or region of interest.
The choice of a particular detector will
be governed very often by this MDA.
However, as seen earlier, the limiting
factor will very often not be the
absolute MDA expressed in Bq, but
rather the specific minimum detectable
activity SMDA expressed in Bq/cm
2
:
SMDA = MDA
A (s)
Figure 7
Specific minimum detectable activity as a
function of detector size for three different
values of source-detector distance h.
For Multiple Radionuclide
For Multiple Radionuclide
For Multiple Radionuclide
For Multiple Radionuclide
For Multiple Radionuclide
Samples
Samples
Samples
Samples
Samples
The background in practical
applications is often compromised by
the presence of higher energy Alpha
lines which produce counts in the
spectrum at lower energies.
Alpha PIPS detectors are notably free
of these tailing effects in comparison to
SSB detectors of equivalent size in part
because of their thin entrance window.
Comparisons between the two types
of detectors have shown a difference
of as much as a factor of three in this
background tailing or continuum. This
translates into an improvement in MDA
of 3 or 1.7 for the Alpha PIPS
detectors.
The critical level
The critical level
The critical level
The critical level
The critical level
The MDA and the SMDA discussed so
far are the a priori minimum detectable
activities. In order to decide after the
completion of the measurement,
whether a peak has been actually
observed or not, the critical level
should be considered
6
:
L
c
= 2.33 b
where b = background counts.
Two cases are possible:
S>L
c
: The peak has been observed and
its intensity I is given by:
I = S ± k
T + b
where S = T-b represents the signal
(total counts T minus background).
For a 95% confidence limit, k = 1.96.
S<L
c
: The peak has not been observed
and an upper limit should be stated:
I < + k
′
T + b
For a 95% confidence limit k
′
= 1.645
Conc
Conc
Conc
Conc
Conclusions
lusions
lusions
lusions
lusions
Alpha PIPS detectors distinguish
themselves from other detector types
(such as SSB and diffused junction
detectors) not only by their extremely
rugged nature (cleanability) but also by
their very thin entrance windows which
result in excellent resolution, high
efficiency and low detection limits.
Finally the special construction features
of a PIPS detector result in a 10-100
times smaller reverse current insuring
increased temperature stability. This
improves system performance for long
counting times associated with low
level Alpha spectroscopy.
References
References
References
References
References
1. I.R. Williams, Nucl. Instr. Meth.
44, 160 (1966).
R. Carchon, E. Van Camp, G.
Knuyt, R. Van De Vijver, J. Devos
and H. Ferdinande, Nucl. Instr.
Meth. 128, 195 (1975).
2. R. Gardner, K. Verghese and H.M.
Lee, Nucl. Instr. Meth. 176, 615
(1980).
3. Experimental Evaluation of the
Characteristic Features of
Passivated Ion Implanted and
Surface Barrier Detectors for Alpha
Spectrometry of Plutonium. S.K.
Aggarwal, R.K. Duggal, P.M.
Shah, R. Rao, H.C. Jain, Journal of
Radioanalytical and Nuclear
Chemistry, 120, 29 (1988).
4. P. Burger, K. De Backer, W.
Schoenmaeckers, 2nd International
Technical Symposium on Optical
and Electro-optical Science and
Engineering, 25-29 Nov., and 2-6
Dec., 1985, Cannes, France.
5. Sources and Prevention of Recoil
Contaminations of Solid State
Alpha Detectors C.W. Sill, D.G.
Olson, An. Chem., 42, 1596 (1970).
6. L.A. Currie, An. Chem. 40, 587
(1968).
7. Handbook of Radiological Health,
US Department of Health,
Education and Welfare, Bureau of
Radiological Health, Rockville,
Maryland 20852 (1970).
8. W. Seelman-Eggebert, G. Pfenning,
H. Münzel, H. Klewe-Nebenius,
“Chart of the Nuclides”, KFK-
Karlsruhe, Gersbach u. Sohn
Verlag, München (1981).
Energy
(MeV)
Radioiso-
tope
Half-life
Yield
(%)
Energy
(MeV)
Radioiso-
tope
Half-life
Yield
(%)
1.83
Nd-144
2.4x10
15
y
100
2.14
Gd-152
1.1x10
14
y
100
2.234
Sm-147*
1.05x10
11
y
100
2.46
Sm-146
7x10
7
y
100
2.50
Hf-174
2x10
15
y
100
2.73
Gd-150
2.1x10
6
y
100
3.183
Gd-148*
84 y
100
3.18
Pt-190
6x10
11
y
100
3.954
Th-232*
1.41x10
10
y
23
4.013
Th-232*
1.41x10
10
y
77
4.150
U-238*
4.51x10
9
y
23
4.197
U-238*
4.51x10
9
y
77
4.368
U-235*
7.1x10
8
y
18
4.400
U-235*
7.1x10
8
y
57
4.415
U-235
7.1x10
8
y
4
4.445
U-236*
2.39x10
7
y
26
4.494
U-236*
2.39x10
7
y
74
4.556
U-235
7.1x10
8
y
4
4.57
Bi-210m
3x10 y
6
4.597
U-235
7.1x10
8
y
5
4.600
Ra-226*
1602 y
6
4.621
Th-230*
8.0x10
4
y
24
4.688
Th-230*
8.0x10
4
y
76
4.722
U-234
2.47x10
5
y
28
4.733
Pa-231
3.25x10
4
y
11
4.765
Np-237
2.14x10
6
y
17
4.770
Np-237
2.14x10
6
y
19
4.775
U-234*
2.47x10
5
y
72
4.778
U-233
1.62x10
5
y
15
4.784
Ra-226*
1602 y
95
4.787
Np-237
2.14x10
6
y
51
4.811
Th-229
7340 y
11
4.821
U-233
1.62x10
5
y
83
4.842
Th-229
7340 y
58
4.863
Pu-242
3.79x10
5
y
24
4.896
Pu-241
13.2 y
0.002
4.899
Th-229
7340 y
11
4.903
Pu-242
3.79x10
5
y
76
4.92
Bi-210m
3x10
6
y
36
4.954
Ac-227*
21.6 y
1.2
4.952
Pa-231
3.25x10
4
y
22
4.96
Bi-210m
3x10
6
y
58
4.967
Th-229
7340 y
6
5.014
Pa-231*
3.25x10
4
y
24
5.028
Pa-231*
3.25x10
4
y
23
5.054
Th-229
7340 y
7
5.058
Pa-231
3.25x10
4
y
11
5.105
Pu-239*
24,400 y
12
5.124
Pu-240*
6580 y
24
5.144
Pu-239*
24,400 y
15
5.157
Pu-239*
24,400 y
73
5.168
Pu-240*
6580 y
76
Appendix 1
Appendix 1
Appendix 1
Appendix 1
Appendix 1
Alpha Emitter
Alpha Emitter
Alpha Emitter
Alpha Emitter
Alpha Emitters b
s b
s b
s b
s by Increasing Ener
y Increasing Ener
y Increasing Ener
y Increasing Ener
y Increasing Energy
gy
gy
gy
gy
7
7
7
7
7
Alpha yields are given in % of total decay. Lines marked by an * are often used as
calibration lines
8
, while lines underlined represent the most intense
α
-line of a given
radioisotope.
Energy
(MeV)
Radioiso-
tope
Half-life
Yield
(%)
Energy
(MeV)
Radioiso-
tope
Half-life
Yield
(%)
Energy
(MeV)
Radioiso-
tope
Half-life
Yield
(%)
5.742
Cm-243
32 y
12
5.745
Ra-223
11.43 d
9
5.757
Th-227*
18.2 d
20
5.763
Cm-244
17.6 y
23
5.786
Cm-243
32 y
73
5.79
Ac-225
10.0 d
28
5.806
Cm-244
17.6 y
77
5.812
Cf-249
360 y
84
5.816
U-230
20.8 d
32
5.83
Ac-225
10.0 d
54
5.851
Cf-251*
800 y
45
5.868
At-211
7.21 h
41
5.87
Bi-213
47 m
2
5.887
U-230
20.8 d
68
5.977
Th-227*
18.2 d
23
5.987
Cf-250
13 y
17
5.994
Cm-243
32 y
6
6.002
Po-218*
3.05 m
100
6.031
Cf-250*
13 y
83
6.038
Th-227*
18.2 d
24
6.051
Bi-212*
60.6 m
25
6.061
Cm-243
32 y
6
6.071
Cm-242
163 d
26
6.076
Cf-252
2.65 y
15
6.090
Bi-212*
60.6 m
10
6.115
Cm-242
163 d
74
6.118
Cf-252*
2.65 y
84
6.126
Fr-221
4.8 m
15
6.22
Th-226
30.9 m
19
5.234
Am-243
7.95x10
3
y
11
5.267
U-232
72 y
32
5.275
Am-243*
7.95x10
3
y
88
5.304
Po-210*
138.4 d
100
5.304
Cm-245*
9.3x10
3
y
7
5.324
U-232
72 y
68
5.342
Cm-246
5.5x10
3
y
19
5.340
Th-228*
1.910 y
28
5.362
Cm-245*
9.3x10
3
y
80
5.386
Cm-246
5.5x10
3
y
81
5.42
Bk-249
314 d
0.0015
5.423
Th-228*
1.910 y
71
5.443
Am-241
458 y
13
5.447
Ra-224
3.64 d
6
5.448
Bi-214
19.7 m
0.012
5.456
Pu-238*
86
28
5.486
Am-241*
458 y
86
5.490
Rn-222
3.823 d
100
5.499
Pu-238*
86 y
72
5.512
Bi-214
19.7 m
0.008
5.52
Bk-247
1.4x10
3
y
58
5.537
Ra-223
11.43 d
9
5.607
Ra-223*
11.43 d
26
5.666
Cf-251
800 y
55
5.68
Bk-247
1.4x10
3
y
37
5.685
Ra-224*
3.64 d
94
5.707
Th-227
18.2 d
8
5.716
Ra-223*
11.43 d
54
5.73
Ac-225
10.0 d
10
6.278
Bi-211
2.15 m
16
6.28
At-219
0.9 m
97
6.288
Rn-220*
55 s
100
6.34
Th-226
30.9 m
79
6.340
Fr-221
4.8 m
82
6.424
Rn-219
4.0 s
90
6.437
Es-254
276 d
6
6.551
Rn-219
4.0 s
94
6.56
Ra-222
38 s
100
6.623
Bi-211*
2.15 m
81
6.640
Es-253
20.47 d
93
6.65
At-218
2 s
6
6.694
At-218*
2 s
90
6.777
Po-216
0.15 s
14
6.819
Rn-219*
4.0 s
85
7.027
Fm-255
20.1 h
91
7.07
At-217
32 ms
100
7.14
Rn-218
35 ms
99
7.145
Fm-254
3.24 h
14
7.187
Fm-254
3.24 h
85
7.28
Po-211m
25 s
100
7.386
Po-215*
1.78 ms
7
7.450
Po-211*
0.52 s
97
7.687
Po-214*
164 µs
100
8.376
Po-213*
4.2 µs
99
8.784
Po-212*
0.30 µs
97
8.88
Po-211m
25 s
7
11.65
Po-212m
45 s
97
Canberra Industries Inc.,
Canberra Industries Inc.,
Canberra Industries Inc.,
Canberra Industries Inc.,
Canberra Industries Inc., 800 Research Parkway, Meriden, Connecticut 06450 (203) 238-2351 FAX: 203-235-1347
TWX: 710-461-0192 TX: 643251
Canberra Semiconductor, N.V.,
Canberra Semiconductor, N.V.,
Canberra Semiconductor, N.V.,
Canberra Semiconductor, N.V.,
Canberra Semiconductor, N.V., Lammerdries 25, 2250 Olen, Belgium Tel. (32-014) 221975
TLX: 72423 CANDES
Canberra International offices:
Canberra International offices:
Canberra International offices:
Canberra International offices:
Canberra International offices:
Australia
Australia
Australia
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Australia, Victoria 008-335638, Mt Waverley 543-4266; Austria
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Austria
Austria
Austria, Vienna 43-1-302504-0; Belgium
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Belgium, Brussels 32-2-4668210; Olen 32-14-221975; Canada
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Denmark
Denmark, Greve 45-42909023; France
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France
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France, Savigny-le-Temple (33) 1 64.41.10.10; Germany
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NAN0010
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Printed in U.S.A.