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MICROCOPY RESOLUTION TEST CHART
NATIONAL BUREAU OF STANDARDS - 1963
til
To be pablished in "Internal Conversion Processes . Including the Proceed-
Rewigs of the Conference on the Internal Conversion Process", Ed. by J. H.
Hamilton; Academic Press.
s
WOV 1 Blogs

RELEASED FOR ANNOUNCEMENT
Conversion coefficient Measurements Employing NUCLEAR SCIDNCE ABSTRACTS
Magnetic and Solid-State Spectrometers
B. van Nooijen,* A. V. Ramayya and J. H. Hamilton, Physics Departinent**
Vanderbilt University, Nashville, Tennessee
and
J. J. Pinajian and N. R. Johnson
Oak Ridge National Laboratory***, Oak Ridge, Tennessee
The development of Lithium-drifted germanium detectors with moderate
efficiency and good energy resolution has made possible the determination
of relative intensities of gamma rays with good accuracy in complex decays.
If the relative conversion electron intensities are measured in a precision
B-ray spectrometer, it is possible to use these in conjunction with relative
gamma ray intensities to determine the internal conversion coefficients
either by accepting the theoretical conversion coefficient of a transition
of known multipolarity or by measuring the conversion coefficient of one of
the stronger transitions by the IEC method for example. The latter method
is illustrated by measuring the conversion coefficients of about twenty gamma
rays of 86sr from the decay of 86.
The gamma rays of Oy were observed with a p-i-n lithium drifted ger-
manium detector having a lithium drift depletion depth of 3 mm and 2 cm
surface area. The full width at half maximum of the 661.6 keV line of b51cs
was 5.5 kev. Typical spectra of the Oy gamma rays are shown in Figs. 1 and
2. The relative gamma-ray intensities are calculated from the peak heights
and the photo efficiency curve obtained by measurements on isotopes emitting
two electromagnetic transitions of known relative intensity (e.g. 203Hg, 60co
and "Y). The relative intensities of the gamma rays of "y are given in
LEGAL NOTICE
Table 1.
RA
This report was prepared as an account of Government sponsored work. Neither the United
Stator, nor the Commission, nor any person soting on behalf of the Commission:
A. Makes any warranty or representation, expressed or implied, with respect to the accus
racy, completeness, or usefulness of the information contained in this report, or that the use
of any information, apparatus, method, or process disclosed in this report may not infringe
privately owned rights; or
B. Assumes any liabilities with respect to the use of, or for damages resulting from the
use of any information, apparatus, method, or process disclosed in this report,
Ag und in the abovo, "person acting on beball of the Commission" include, any em-
ployee or contractor of the Commission, or employee of such contractor, to the extont that
such employee or cor.lractor of the Commission, or employee of such contractor prepares,
disseminate., or provides access to any information pursuant to his employment or contract
Mem
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The relative K-conversion electron intensities were measured in the
Vanderbilt iron-free double focusing spectrometer with a resolution of
about 0.5%. A G-M Counter was used as a detector; the cut-off of the
window was about 10 kev. Sources were prepared by liquid deposition onto
Zapon film and had areas of 5 * 16 mm. The results of the measurements
are shown in Table 1.
The K-external conversion line of the 2+ ++ 1078 keV transition
from the first excited state to ground state has been chosen as a stan-
dard and was measured by the IEC method with a uranium converter. The
uranium converter had an area of 5 x 21 mm and a thickness of 3.71 mg/cm.
The K-conversion coefficient of this 2.078 keV transition was found to be
4.5 * 0.3 which agreed very well with the theoretical E2 K-conversion
coefficient value of 4.3.
K-conversion coefficients of the twenty one Oy gamma rays calcu-
lated in this work are shown in Table 1. The probable multipolarities
assigned to these gamma rays are also shown in Table 1. The accuracy
obtained in these experiments is of the order of 8 to 10% which is more
than sufficient for multipolarity assigaments for a large number of gamma
rays in complicated decay schernes.
*N.S.F. Senior Foreign Scientist on leave from The Technological
University of Delft, Netherlands.
**Work supported in part by a grant from The National Science Foundation.
***Research sponsored by The U. S. Atomic Energy Commission under contract
with the Union Carbide Corporation.
TABLE 1
RELATIVE GAMMA RAY INTENSITIES, RELATIVE CONVERSION ELECTRON
INTENSITIES AND THE K-CONVERSION COEFFICIENTS OF THE GAMMA RAYS OF
Ej
keV
Oy - THEORY
MULTI
M 4 E2 LI POLARITY
x 10-4 x 104
11078 = 100
x 10-4
11078 = 100
El
x 20
4
257
850
137
133
M/E2
M/E2
247
820
62
125
3.15
El
36
75
153
9
EL
188.0 1
190.0
251.0
305.1
441.8
581.6
607.1
626.8
645.1 1
703.3
710.6
570 + 220
760 130
52 I 32
43 I 6
15.2 1.8
20.1 £ 5.1
8.7 +
6.2 +
0.6
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9.7 +
13.4
6.9
6.2
47.5
20.6
18.1
16.8
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16.3
14.7
13.8
13.0
10.5
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2.9
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4.5
15.5
12.1
12.0
MI/E2
73 $ 15
280 = 20
4.2 $ 0.8
39.5 + 3.5
61 5 5
18.0 2.5
4.5 = 0.5
56.0 + 3.5
37.5 2.5
43 = 2
7.5 2.0
58.7 £ 5.0
3 I
10.5 = 0.7
4.4 + 0.4
30.5 + 2.0
4.3 + 1.1
0.8 $ 0.2
2.0 + 0.3
0.6 + 0.2
7.1 $ 1.1
4.2 $ 0.8
4.5
9.0
0.55 + 0.17
1.60 $ 0.24
0.35 + 0.20
4.0 0.4
17.4 1.5
3.9 $ 0.8
2.2 $ 0.8
38.6 + 3.3
13.0 + 1.3
19.2 I 1.6
3.6 $ 0.8
26.5 = 2.1
3.9 0.9
15.3 + 0.7
4.5 $ 0.5
37.6 + 2.5
2.1 10.6
1.8 +0.3
3.2 = 0.7
2.2 £0.5
20.4 + 1.5
28.0 + 2.1
10.4
MI/E2
M/E2
1.1
3.7
8.6
9.6
3.31
3.0 £
7.4
1.3
0.4
9.7
8.2
8.0
4.9
4.2
7.3
4.6
0.6
3
3.5
0.3
3
828.5
834.4
1025.2
2153.7
2162.8
1253.4
1350.0
1804.2
1857.0
1924.1
8.7 +
im
3.2
2.1
1.7
1.7
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1.3
0.8
0.7
0.7
CCO
3.6
3.6
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2.5
1.4
1.4
1.9 $
2.7 +
1.2 $
1.50+
0.65
3.0
2.5
3.3
0.6
0.7
0.5
0.25
0.13
3
1.4
M/E2
1:3
1.3
El
FI
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Figure Captions
Figure 1. :"7 gamma ray spectrum (low energy region) taken with a
lithium drifted germanium detector.
Figure 2. Or gamma ray spectrum (high energy region) taken with a
lithium drifted germanium detector.
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DATE FILMED
11/ 24 /65