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ABSTRACT

THE SEARCH FOR THE WEAK (1.14 Mev.) GAMMA RAY

93 CADMIUM115m

AND

g LITERATURE RESEARCH 95 2396, 22119 AND 23121.

by Ricardo S. Pascual, Jr.

To furnish an additional verification of the pre-
viously reported l.l4-Mev. gamma ray from Cadmiumllsm, the
spectrum of Sodium22 (the 1.28-Mev. gamma) and Scandiumg'6
(the 0.88-Mev. gamma) were subtracted from the scintilla-
tion spectrum of the Cadmium isotOpe obtained with the 256-
Channel Analyzer. The resulting spectral neighborhood show-
ed a full-energy peak at 1.14 Mev.

In addition, some of the latest information and
96, Tell9 and Te121
in future experiments on these isot0pes. Furthermore, some
theoretical predictions on the internal conversion coef-

estimates on To were summarized to aid

ficients of these isotopes were made for comparison pur-
poses with the observations of future experiments on these
same isotopes.

THE SEARCH FOR THE WEAK (1.14 Mev.) GAMMA RAY
115m

 

93 CADMIUM

AND

A LITERATURE RESEARCH 91} 3396, 23119 AND 23121.

 

by Ricardo S. Pascual, Jr.

A Thesis

Submitted to
the College of Science and Arts
Michigan State University of Agriculture
and Applied Sciences in partial fulfillment
of the requirements for the degree of

MASTER OF SCIENCE

Department of Physics

1962

Approved: \lfiflm’t B‘JZLLW

ACKNOWLEDGEMENTS

I am greatly indebted to Dr. William Kelly who
suggested the problem and assisted in the actual investi-
gation through his proposal of the subtraction technique;
and to Dr. Herbert Bolotin who later assumed a similar
task. I am very grateful to Dr. Bolotin for his guidance
and help to make the completion of the research possible,
and for his painstaking efforts in checking the manuscript.

ii

TABLE OF CONTENTS

I. Introduction . . . . . . . . .
II. Interaction of Gamma Radiation

with Matter . . . . . . . . .
III. The Scintillation Spectrometer
IV. The 256-Channel Analyzer . . .
V. The Observed Spectra . . . . .
VI. The Search for the Gamma Ray .

VII. The Literatgre Research:
9

l. Technicium . . . . . . . . .
2. Telluriumllg . . . . . . . . .
5. Telluriuml21 . . . . . . . . .

VIII. Internal Conversion Coefficients
IX. Appendix . . . . . . . . . . .
X. Bibliography . . . . . . . . .

- o O o -

iii

LIST 93 TABLES

Table
I. Energies, relative intensities,
and half-lives of the ’Y'S of Tellg. . . .
II. Coincidences in the 4.7d Te isomer . . . .
III. Relative intensities of conversion
lines of Te121 . . . . . . . . . . . . . .
Appendix:
(I - Tables of Internal Conversion Coefficients

IX) for the Gamma Rays

(X - Tables of Internal
XIII) for the Gamma Rays

(XIV - Tables of Internal
XVI) for the Gamma Rays

of Mo96 . . . . . . . .

Conversion Coefficients
of Sb119.

Conversion Coefficients

of Sblal. . . . . . . .

(XVII - Tables of T% for Gamma Transitions

XXV) of M096 . . . . .

(XXVI- Tables of T% for Gamma Transitions

XXIX) of Sb119 . . . . .

(XXX- Tables of T% for Gamma Transitions

XXXII) of Sb121

iv

50

58 -
65

63 -
65

65 -
66

e7-
71

71-
75

74

Figure

LIST 9E FIGURES

Energy Distribution Among Beta-
Particles of Radium E . . . . . . .

2. The Single-Channel Analyzer . . . .
3. The Scintillator-Photomultiplfier
Assembly . . . . . . . . . . . . . .
4. The Preamplifier . . . . . . . . . .
5. The Analyzer Arrangement . . . . . .
6. The Scintillation Spectrum of Cd115m
7. The Scintillation Spectrum of Na22 .
8. The Scintillation Spectrum of Sc46 .
9. The Cd Spectrum (Minus the 0.94- and
1.50-Mev. Peaks) . . . . . . . . . .
10. The Cd Spectrum (Minus the 1.30-Mev.
Peak)
11. The Proposed Beta-Gamma Coincidence
Arrangement . . . . . . . . . . . .
12. Proposed Decay Scheme of T096 . . .
15. PTOposed Decay Scheme of To96 & Nb
l4. Tentative Decay Scheme for Tell9 . .
15. Tentative Decay Scheme for Te121 . .
Appendix:
1. Decay Scheme of Cd115m . . . . . . .
2. Decay Scheme of To96 . . . . . . . .
5. Decay Scheme of Tellg. . . . . . . .
4. Decay Scheme of Telzl. . . . . . . .

Page

10

13
15
19
26
27
28

29

30

51
57
58
47
53

75
76
77
78

INTRODUCTION

RADIOACTIVITY:

Radioactivity is the emission of energetiC'parti-
cles (alpha or beta particles) or electromagnetic radia-
tions (gamma rays) from unstable nuclei. The only means of
detecting and measuring these emissions is through the ob-
servable effects of their interaction with electromagnetic
fields and matter. One of these means is the Scintillation
Technique which is based on the effects of interaction of
the radioactive emission with special substances known as
"phosphors"; this will be explained in necessary detail
in the later portions of this paper.

For this particular presentation, it is necessary to
discuss only two types of radioactive emissions:

(1) Beta Particles:

A number of experiments in the past have proven that
this type of emission is composed of faSt-moving electrons;
the only distinction from the earlier-defined electron be-
the fact that these energetic particles originate from the
nucleus instead of the extranuclear electronic orbits of
the atom. There are no electrons existing as such in the
nucleus. An electron, however, may be formed and ejected
from the nucleus by means of a neutron decay into a proton
and an electron (accompanied by a neutrino). The electri-
cally neutral neutrino with a negligible rest mass is
emitted to conserve the energy and the angular momentum
in this neutron decay process. Beta particle emission is
an isobaric process, producing a daughter nucleus which

1

has the same mass number (the nucleon number; i.e., the
total number of protons and neutrons in the nucleus), but
having an atomic number (i.e., the number of protons or
the number of atomic electrons) which is one more than
that of the parent nucleus. When the transition is from
the ground state (state of lowest excitation energy) of
the parent nucleus to the ground state of the daughter
nucleus, the energy available for the beta decay comes
from the differenceiJlmass of the nuclei involved.

One method for determining the velocities of these
particles (hence their energies) is by the measurement of
'the radii of curvature of their paths in a uniform magnet-
ic field of constant intensity (perpendicular to the beta
beam). By equating the Lorentz force to the Centrifugal
force, the velocities can be obtained as a function of the
known magnetic field intensity or the radius of curvature.
This then, may result in a velocity or momentum distribu-
tion of the beta particles from the radioactive source.

The resulting momentum (or energy) spectrum from a
beta disintegration is distinct from other types of Spec»
tra characteristic of the same atom (viz., optical , char-
acteristic X-rays, etc.); in that, it is a continuous one.
The other characteristic spectra are ling spectra. The
continuous beta Spectrum exhibits a "preferred" energy
(the energy possessed by the greatest number) and a maxi-
mum energy limit. This maximum limit or "end-point energy"
is interpreted as the energy released in this particular
radioactive disintegration. A typical beta spectrum is
shown in Fig. l.

Oftentimes, the continuous beta spectrum is superim-
posed on a "sharp line" spectrum which is an indication of
the presence of electrons which have been ejected from the
extranuclear orbits of the atom. These internal conversion
(IC) electrons are emitted as a result of the interaction

 

 

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of the orbital electrons with the electromagnetic field of
their own nucleus. The ejection of an orbital electron
leaves the extranuclear portion of the atom in an excited
state. There are a number of ways by which this instabili-
ty could be removed by the atom itself. In one, the remain-
ing orbital electrons may rearrange to fill the vacancy
created by the IC electron (inner orbit) and in so doing,
emit fluorescent X-rays. Each X-ray photon represents the
energy released in a particular electronic transition. In
this case, the energy of the X-ray photon is the difference
between the binding energies of the initial and final
states of the particular electron which participated in the
rearrangement to fill the vacancy left by the IC electron.

Another possibility by which the atom may return to
stability is the so-called Auger effect. Here, the photon
energy which would have been manifested as a characteris—
tic X-ray, is utilized to eject another orbital electron,
the Auger electron. This phenomenon is also known as a
radiationless transition Since the X-rays which would have
resulted after internal conversion, are not emitted and
another particle is emitted instead.

(2) Gamma Rays:

After the emission (Alpha or Beta Decay) or capture
(Orbital Capture, Particle Bombardment, etc.) of a parti-
cle, the resulting nucleus is left in an excited state.
One way by which the energy of excitation of this nucleus
may be decreased is through the emission of gamma rays.
The allowed nuclear energy levels are discrete and since
gamma rays are the result of transitions by the nucleus
from one energy level to another, then gamma ray energies
too are discrete; and conversely. The energy of a gamma

photon then is the difference between the excitation ener-
gies of the nuclear energy states involved in the transi-
tion which results in this particular photon. Gamma emis-
sion alone, does not change the proton-neutron composi-
tion of the nucleus but may bring the isotOpe to its
ground state (one of lowest energy) through a number of
such transition steps; each transition giving rise to a
gamma photon emission. The energies of the gamma rays then
are indicative of the energy states which the nucleus oc-
cupied in its transit to the ground state.

Like X-rays, gamma rays are electromagnetic radia-
tions, as Shown by some well-known experiments (e.g.,
crystal diffraction experiments). X-rays, as previously ex-
plained, involve only the extranuclear transitions; while
gamma rays on the other hand, are the result of nuclear
transitions from one energy state to another as the nucleus
proceeds to stability.

There are instances, however, in which the nucleus
undergoes a transition to a state of lower excitation ener-
gy without the emission of a gamma photon. Instead of emit—
ting the photon, the electromagnetic field of the nucleus
interacts with the extranuclear orbits and thereby causes
the ejection of one of these electrons. In this case, the
energy which would have been emitted in the form of a gam-
ma photon is utilized in the ejection of an orbital elec-
tron. The kinetic energy of the ejected electron then is
the nuclear transition energy less the energy which bound
the electron to its former orbit. These energetic elec-
trons which are emitted from the atom through this process
are called internal conversion electrons. Knowledge of the
energies of these IC electrons and the orbital binding
energies then will give the total energy of this transi-
tion.

INTERACTION OE GAMMA RADIATION WITH MATTER

 

As previously introduced, the Scintillation Tech-
nique is based on the interaction of nuclear radiations
with phosphors, a special class of substances which emit
light upon absorption of these radiations. At this point,
it is important to classify the interactions into basic
types, with the understanding that the total absorption of
the gamma ray energy may (as in actual cases) involve com-
binations of a number of these basic interactions:

(1) The Photoelectric Effect:

This is the type of interaction in which the total
energy of the gamma ray is utilized in ejecting an orbital
electron. The resulting energetic electron is called the
photoelectron. A free (unbound) electron cannot absorb the
gamma energy and become a photoelectron; another body, the
nucleus, is necessary for the conservation of momentum in
the process. This requirement (bound electron) added to
the fact that gamma energies-are discrete, explains the
discrete nature of photoelectron energies. The kinetic
energy of the photoelectron is the difference between the
incident-gamma energy and the binding energy of this elec-
tron before the ejection. '

(2) The Compton Effect:

It is quite possible for an electron to be ejected
from the atom even if the energy of the incident gamma ray
is not tetally utilized in the process. In this type of

6

interaction, called the Compton Effect, the gamma ray un-
dergoes a scattering process with an electron (considered
free and stationary) of an atom, analogous to a two-parti-
cle collision (this was predicted by the wave-particle du-
ality of light, or conversely for all electromagnetic ra-
diations in general). This process results with an ejected
electron, the Compton electron, and a scattered gamma ray.
The resulting wavelength of the gamma ray will be longer
due to its loss of energy to the Compton electron. The
energy of the Compton electron and the wavelength of the
scattered gamma ray may be calculated through the applica-
tion of the De Broglie Principle and the Conservation Laws
of Particle Collisions (relativistic).

It is worthwhile to mention at this juncture that
since only a partial transfer of gamma ray energy is in-
volved, the Compton electron carries less kinetic energy
than the photoelectron; for incident gamma rays of the
same energy.

(5) Pair Production:

In the presence of matter, a gamma ray of energy
greater than about 1.02 Mev. (the rest energy of two elec-
trons) may be totally converted into a positive (positron)
and a negative (negatron) electron. These particles created
from electromagnetic radiation may lose their kinetic
energies (each about half the difference between the inci-
dent gamma energy and 1.02 Mev.) through ionization by im-
pact on the neighboring atoms, or through their interac-
tion (Coublomb type) with the electromagnetic fields of a
nucleus or some orbital-electron distribution. A positron
which had been stopped in this manner will then combine
with a neighboring electron (free and stationary) to pro-

duce two oppositely-directed gamma photons of 0.511 Mev.
each. This process, in which particles disintegrate and
radiant energy appears in their stead, is called annihila-
Eigg; as contrasted to the creation of an electron pair
(pair production) from a gamma photon. The annihilation
gamma photons may further be converted to particle energies
by means of one of the basic interaction (or combinations
thereof) already explained.

THE SCINTILLATION SPECTROMETER

From the early scintillation method of counting
alpha particle emissions from radioactive substances, has
developed a more complicated but more reliable and useful
technique. The older method was very inconvenient since
visual counting of the number of fluorescences (scintilla-
tions) on the Zinc Sulfide target was the only means of
getting the disintegration rate. Thus, only weak activi-
ties could be investigated.

Recently, the field of nuclear decay studies had
been greatly expanded due to important developments in
electronic counters and in phosphors. These developments
served to give rise to a kind of spectrometric set-up in
popular use today.

It is necessary, at this point, to devote a dis-
cussion to the Single-Channel Anal zer, the basis of multi-
channel Analyzers.

The Single-Channel Analyzer:

This prototype of the multi-channel Analyzer used in
the experiment, is made up of a scintillator-photomultipli-
er assembly (the detector) and some analyzing components
(viz., a preamplifier, a linear amplifier, a discriminator
and a scaler). A block diagram of this arrangement may be
found in Fig. 2.

(l) The Scintillator-Photomultiplier Assembly:

A number of substances have been found to emit

9

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light upon absorption of nuclear radiations. These sub-
stances are called "phosphors"; their means of absorption
of nuclear radiations had been explained in the previous
sections.

Gamma radiation energies that are converted to parti-
cle energies (i.e., photoelectrons, Compton electrons or
electron pairs) are further converted to fluorescent radia-
tion in the phosphor since these particles are easily
stopped and their kinetic energies absorbed by the phos—
phor. On the other hand, gamma rays and X-rays emitted
(produced through the annihilation or the photoelectric
and Compton processes) near the phosphor surface, may
pass through the phosphor without being absorbed and con-
verted to fluorescent radiation. This problem of photon-
escape may be remedied to a large extent, by the use of a
larger-sized phosphor and the provision for normal inci-
dence of the radiations on the phosphor surface, to im-
prove the possibility of absorption.

Another of a number of requirements for the Scintilla-
tion Technique is that as much of the fluorescence (pro-
duced by the phosphor) as possible, Should be received by
the detector, the Photomultiplier tube. The light that is
emitted by the phosphor is randomly-directed and must be
conveyed towards the receiving end of the photomultiplier
tube, the photocathode. This may be accomplished by the
use of reflectors which will internally reflect the light
to the preferred direction. In addition, the light from
other sources than the phosphor must be prevented from
finding its way into the photocathode window. This may be
solved by masking off the scintillator unto the photocath-
ode window, thus keeping the scintillator-photomultiplier
component light-tight from the outside.

The glass encasing the photocathode window also pre-
sents a problem. The fluorescence coming into the window

 

12

may be reflected (and possibly internally reflected) by
this glass layer and thus find its way back into the phos-
phor and thereby be lost through absorption. This light-
loss may be minimized by making an optical joint between
the glass window and the scintillator. For instance, the
Dow Corning Fluid (No. 200), as a joint, will graduate the
optical density of the material confronting the light in
its passage into the photocathode; thereby diminishing the
reflection of light back into the phosphor. In applying
this Fluid on the photocathode window, care must be taken
so as not to form air bubbles in the layer (these bubbles
may themselves cause the reflections we are trying to pre-
vent). These precautionary measures may be fully under-
stood through Fig. 3. Here the Tl-activated NaI crystal
(in the form of a right-circular cylinder 1% inches in
diameter and 1% inches thick) is encased in an aluminum
can (about 0.01 inch thick and with a glass bottom) lined
with MgO (reflector); this type of scintillator is avail-
able commercially (Harshaw).

The light emitted by the phosphor eventually finds
its way to the photocathode, after a series of internal
reflections by the scintillator lining. Through the photo-
electric process, this light ejects electrons from this
photosensitive plate (photosensitivity, in a mild sense,

 

is a measure of the photoelectric response as a function
of the luminance). These photoelectrons are then acceler-
ated to a nearby plate, the dynode, by a higher electric
potential. The photoelectrons hit the surface of the dyn-
ode with such a velocity as to cause the ejection of sev-
eral electrons, called secondary electrons. The secondary

 

electrons are further attracted to another dynode and
their impact gives rise to more secondary emission. These
secondary electrons are attracted in a similar manner, by

15

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ASSEMBLY .

 

14

a number of consecutive dynodes which are higher in poten-
tial than the preceding ones. The net effect of this re-
petitive process then, is a progression of the number of
secondary emissions; and the number of secondary electrons
received by the last plate of the photomultiplier tube,'the
anode, can be made very large. Some photomultiplier tubes
can transfer as much as 106 secondary electrons (or even
more) to the anode, for every single photoelectron ejected
from the photocathode. Thus, a single photoelectron at the
start of this progression will register a voltage pulse in
the plates of a condenser connected to the anode. In this
sense, the photomultiplier component provides pulses which
are sufficient in magnitude to be utilized and analyzed by
the subsequent electronic components.

It is very important to note at this point, that in
the scintillator-photomultiplier pairing, the entire spec—
trum of the phosphor fluorescent emissions must be within
the photosensitivity range of the photocathode.

We have so far, explained what is considered the de-
tector components of the Analyzer; the following sections
will be devoted to a description of the analyzing compo-
nents:

(2) The Preamplifier:

The preamplifier of the photomultiplier serves to
amplify the voltage pulses obtained directly from the pho-
tomultiplier tube. This is a linear amplifier; the choice
of this type of amplification is to preserve the linearity
of fluorescence response of the NaI (crystal) phosphor,
for instance. Provisions are also made so as to present a
low-impedance output to the other portions of the Analyzer,
through the use of a Cathode-Follower type (Fig. 4).

 

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(5) The Linear Amplifier:

The use of this type of amplification results in
output signals of much larger magnitudes and which are in
direct proportion to the input. This then provides the
convenience of plotting the pulse-height range in a linear
scale.

(4) The Discriminator:

In most conventional single-channel analysis, one
essentially plots the number of counts for every pre-se-
lected pulse-height interval (into which the entire pulse-
height range of the spectrum had been divided). In Elemen-
tary Calculus, the entire domain (of independent variables)
is first broken up into small intervals and then the height
of each of these intervals (the ordinate value) is obtain-
ed by integration of the single-valued function under con-
sideration (in each designated interval). Thus, the func-
tion is mapped within the desired range. Of course, better
approximation is obtained by using smaller intervals.

In single-channel analysis, the number of counts for
a pre-selected pulse-height interval (all pulses between
the pulse-height E and E +4AE) must be obtained in order
to plot the pulse-height spectrum, by a similar procedure
as in the above analogy. The function of the discriminator
is to produce an output pulse only when the input pulse-
height is within a designated pulse-height interval. That
is to say, the discriminator must provide for the setting
of the minimum pulse-height value (the Baseline) and the
pulse-height interval (the Channel-Width). After the Chan-
nel-width had been selected, the number of counts (the
value of the "emission" function, refering to the analogy)

17

for a given Baseline setting is obtained and in this man-
ner, the entire spectral range is swept by the Baseline.
The resulting pulse-height spectrum is then the mapping of
the number of counts as a function of the pulse-height.

(5) The Scaler:

In the Analysis, the Scaler performs the process
of addition (more precisely, it gives a cumulative record
of the counts as they take place) and gives the total num-
ber of counts for a given pulse-height interval. At the
end of the desired time interval, the Scaler displays the
total number of counts for the setting. This component is
provided with a Start and a S322 switch in order to allow
the same time interval for counting in each discriminator
setting.

The 256-Channel Analyzer:

In this particular investigation, a modified RIDL
256-Channel Analyzer (Model 5501) was used in conjunction
with the type of detector discussed in the previous para-
graphs (Fig. 5). The phosphor used was a 1%" X 1%" NaI
(Tl-activated) crystal paired with a Dumont N2. 6222 pho-
tomultiplier tube. The circuit diagram of the preamplifi-
er (Cascade Cathode-Follower Type) involved is shown in
Fig. 4.

As the name indicates, the Analyzer effectively com-
bines two hundred and fifty-six Single-channel analyzers
into a single component. The RIDL Analyzer is equipped
with a memory storage, a linear Cathode Ray Display Tube

18

and a Scaler; aside from its built-in amplifier-discrimina—
tor component. The Analyzer may be fed through the Amplifi-
er Input.

The memory-storage component, as the name implies,
stores each channel's counts (the channel capacity is 65,
555 counts) and releases them upon demand (PRINT button).
There are provisions for memory erasures (MEMORY CLEAR but-
tons). The Cathode Ray Tube can be used for graphic dis-
play of all the two-hundred and fifty-six channel contents
(DISPLAY button) simultaneously. The Scaler reproduces the
counts of each channel as stored in the memory bank. For
convenience, the Analyzer is also equipped with an auto-
matic timer which starts at the beginning of the counting
process (COUNT button) and automatically stOps the Analyz-
er at the end of the designated time interval.

A Hewlett-Packard Digital Recorder (Model 560A) was
used to obtain a printed record of the actual counts in
each channel as stored in the memory bank of the Analyzer.
Since the memory capacity for each channel is 65, 555
counts, thereafter the particular channel which over-flow-
ed will immediately start counting from nil; the printed
results then turn out accordingly.

The block diagram of the experimental set-up is
found in Fig. 5.

19

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THE OBSERVED SPECTRA

This portion of the presentation will be devoted
to a description of the typical scintillation spectrum ob-
tained with the use of the 256-Channe1 Analyzer; in partic-
ular, that of a single-gamma (i.e., monochromatic gammas)
emitter. It must be understood that the spectrum of an iso-
tOpe emitting gammas of different energies will simply be
a superposition of this basic spectrum.

The various interactions of gamma rays with the phos-
phor resulting in discrete particle or radiation energieS'
(i.e., photoelectrons, Auger electrons, X-rays and annihi-
lation gammas) when absorbed and converted to fluorescence,
turn out as pulse-height distributions in the scintilla-
tion spectrum. This is because the scintillation, as well
as the photomultiplication processes are statistical in
nature. Hence, instead of having sharp lines at these
energies, Gaussian-like distributions are observed at each
of these energy sites. The positions of these peaks then
are indicative of the associated energies of these events.

The advantage derived from the use of phosphors which
provide pulse-heights per Mev. which are very nearly inde-
pendent of the energy (e.g., Tl-activated NaI crystal) is
that any combination of events in which the gamma energy
is totally absorbed in the phosphor produces the same
pulse-heights. For instance, a photoelectric event in an
iodine atom (this element contributes most, since the pro-
cess has a high coefficient the higher the atomic number;
the concentration of T1 is such that the photoelectric con-
tribution from this element may be considered insignifi-
cant) followed by the substantially simultaneous absorp-
tion of iodine X-rays, produces the same pulse-height as
that due to the total absorption of another gamma of the

20

21

same energy through substantially simultaneous events
(e.g., Compton events, followed by a photoelectric absorp-
tion and the absorption of the associated X-rays). These
pulses result in a distribution at the maximum energy. The
full-energy pgak (as this distribution is most accurately
referred to) may be attributed to the most-probable photo-
electric process (hence, also called the "photopeak") but
in general, it may be attributed to any combination of e-
vents which result in total absorption of the gamma ener-
gy.

On the high-energy side, this distribution degrades
to nil since no possible combination of events (beyond the
limits of simultaneity) will produce greater pulse-heights
than those from the total absorption of the gamma energy.
On the low-energy side, however, the distribution degrades
to non-zero counts due to the contributions from pure Comp-
ton events. It is quite poSsible to observe contributions
(even another pulse-height distribution, an escape pppk)
.in this region since the associated X-rays have a possibil-
ity of escaping from the phosphor when the photoelectric
events associated with low-energy gammas (low penetrabil-
ity) take place near the phosphor surface. In this event,
the photoelectric distribution will be below (by an amount
equal to the energy of the escaped X-ray photon) the full-
energy peak.

The nature of the Compton process itself, leads one
to expect a pulse-height distribution at the lower energy
range, considering the wide distribution of energies of
the Compton electrons. This distribution exhibits a sharp
drop or "edge" at the high energy side; this represents
the maximum energy that the gamma ray can impart to the
Compton electrons. The Compton edge is more pronounced in
the spectrum of high-energy gammas since the cross section
for the process decreases more slowly with increasing ener-

22

gy than the cross section for the photoelectric process,
and the escape probability for the scattered photons is
larger.

The Compton process could take place outside the scin-
tillator; the resulting gammas being scattered into the
phosphor. In this event, another pulse distribution, the
back-scattered p235, may be superimposed on the Compton
distribution. Likewise, the photons scattered by the phos-
phor may be back-scattered by the materials outside the
scintillator (mainly by the glass layers between the phos-
phor and the photocathode).

Events which result in discrete electromagnetic ener-
gies (annihilation gammas) may produce subsidiary pulse
distributions when only the associated electron energies
(the kinetic energies of the electron pairs) are absorbed
and converted to fluorescence by the phosphor. If both an-
nihilation gammas escape the phosphor (i:e., when the pair
is produced near the surface of the phosphor), the pair
kinetic energies will appear as a pulse distribution 1.02
Mev. below the full energy peak. If only one annihilation
gamma escapes, the electron pair energy distribution will
be 0.511 Mev. below the full-energy site.

Bremmstrahlupg events (emission of inhomogeneous

 

gammas as a result of the changing dipole moment of the
atom when the electronic charge is suddenly shifted from
the nucleus to a region outside, by the emission of a beta
particle) may be manifested as a negative pulse-height dis-
tribution, with the maxima at the low-energy limit of the
spectrum. This type of distribution is similar to that re-
sulting from amplifier noise (low-energy pulses put out
by the amplifier itself), but may be distinguished from
the former by analyzing without any radioactive source.
This procedure may also be used to investigate extraneous
effects on the spectrum (viz., radiations from other

25

sources nearby, cosmic rays, etc.).
Sample Spectra exhibiting some of these characteris-
tics are Shown in Figs. 6, 7 and 8.

THE SEARCH FOR THE GAMMA RAY

This particular investigation was prompted by the-
incompleteness of the data summarized in the Nuclear 2333
sheets. It was observed that in the proposed decay scheme
for Cadmium115m (Fig. 9), there was no definitely estab-
lished transition which leads to the pOpulation of the
1.14 Mev. energy level of the isotope, although a gamma
transition from that state to the ground state had been in-
corporated in the said scheme.

The latest investigation of the decay is summarized in
an article by 0. E. Johnson and W. G. Smith* wherein the
1.14 Mev. gamma ray was first announced. The experiment was
accomplished with the aid of a 256-channel analyzer in con-
junction with a 5" x 5" NaI (T1) crystal scintillator. A
full-energy peak was observed at 1.14 (i 0.017) Mev., a-
mong other gammas. The relative intensity of this gamma did
not change after cadmium chemical separation and for over a
period of 1.5 half-lives. No further investigation was made
on the origin of the 1.14 Mev. energy level; but it was hy-
pothesiZed that this level may be populated by either a
beta or a gamma transition from any of the two over-lying
energy states (the 1.50- or the 1.42-Mev state) of the Cd
isotope.

These estimates prompted a more-or-less clear-cut plan
to support the prOposed decay scheme. To constitute an ad-
ditional experimental proof of the existence of the report-
ed gamma transition, it was planned to diSplay 1.14-Mev
photopeak alone (i.e., to remove the superposition effects
on the spectrum produced by the two precariously-near gamma
rays of 0.935- and 1.50-Mev.). This was to be done by Spec-
trum Subtraction, using the gamma rays (of energies close

 

* 0. E. Johnson & W. G. Smith, Phys. Rev. 116: 992 (1959).
24

25

to those of the interfering gammas of Cd) of available iso-
topes which have simpler gamma spectra (i.e., emitting only
one gamma of the desired energy; the presence of an unneed-
ed gamma is also feasible if the energy separation is wide

enough so that the Compton distribution of the desired gam-
ma is not masked off by the extraneous one). These require-
ments are amply satisfied by the isotopes, Na22, and Sc46

The scintillation spectrum of Cd115m (Fig. 6) obtain-
ed with the 1%" x 1%" NaI (T1) crystal phosphor showed
very poor resolution at the 1.14 Mev. site. To remedy this,
the Spectra of Na22 and So46 were obtained through the same
conditions as the Cd analysis, except that the amplifier
gain was adjusted such that the 1.28-Mev. photopeak of Na22
falls on the same site as the 1.50-Mev. photopeak of Cd115m
and the 0.88-Mev. photopeak of So46 falls on the same site
as the 0.955—Mev. photOpeak of od115m.(Figs. 7 and 8). The
legitimacy of this procedure lies in the fact that the
spectral width (or resolution) varies linearly with the
amplifier gain. The linearity of the pulse-heights as a
function of the scintillation intensity (this may be taken
as the energy of the incident gamma ray) allows the effec-
tive conversion of the energy of the gamma rays to the de-
sired one by adjustment of the amplifier gain. The gamma
rays of Na22 and Sc]+6 then had been effectively converted
to the energy of the Cd gammas.

These converted spectra (pulse counts as a function of
the analyzer channel) can now be subtracted from the Spec-
trum of Cd115111 channel-by-channel and counts for counts.

First, both gammas were subtracted from the Cd spec-
trum. The result of this procedure was poor (Fig. 9). Then
the Na22 spectrum alone was subtracted from the vicinity of
the 1.14 Mev. site, the result was much better (Fig. 10).
The reason for this better result may be clarified by a
comparison of Figs. 6 and 7. It will be noticed that the

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Compton peak of the 1.30-Mev. gamma falls at the low-energy
$10pe of the 1.14-Mev. photopeak. The result of this par-
ticular step showed a great deal of improvement as compared
to that obtained by Johnson et al., using a bigger phos-
phor. This indicates an importance of the spectrum subtrac-
tion in scintillation analysis, especially for very weak
intensities (in this case, 0.05%) present in a compound
gamma spectrum.

Furthermore, it was observed that the "rise" at the
1.14-Mev. site in both the unsubtracted and in the subtract-
ed Spectrum of Cd, grew in the course of the analyses made
up to 1.5 half-lives. The improvement can be seen through a
comparison of Figs. 9 and 10.

There had been no Cd chemical separation done on the
source* and in view of the behavior of this peak as stated
above, this gamma is suspected to be emitted by some traces
of Zn65 (245 days half-life) which may be present in the
source. Chemical purification is necessary to ascertain the
origin of this weak gamma.

In addition to displaying the 1.14-Mev. photOpeak
through the spectrum subtraction, a gamma-gamma and a beta-
gamma coincidence experiment was also prOposed in order to
definitely establish the origin of this particular Cd
state. A block diagram of the proposed coincidence set-up
may be seen in Fig. 11. This experimental arrangement is
designed for the beta-gamma portion of the coincidence ex-
periment. For gamma-gamma coincidences, the beta detector
need only be replaced by a gamma detector (i.e., adding a
beta absorber to the said detector).

However, a closer examination of the Cd decay scheme
(Appendix B, Fig. I) revealed a number of difficulties
confronting such a coincidence investigation. First, if
the 1.14—Mev. state is populated by a beta decay of Cdllsm,

 

* Cd (N03)2 in HNOB solution, prepared at Oak Ridge.

55

then we are faced with the problem of shielding off the
0.485-Mev. gammas (populating the 0.955-Mev. level) from
the 0.49-Mev. betas (if any) which is hypothesized to
populate the level under investigation. This then requires
the use of a high efficiency beta detector (in view of the
weak intensity of the betas involved) which is not ener-
gized by gammas (of virtually the same energy as the expect-
ed betas) which have no relevance to the 1.14-Mev. level.
The presence of these extraneous gammas would contribute

to the increase of the "chance-coincidence" count rate
which in turn, may lead to a doubtful conclusion. Increas-
ing the beta-sensitivity and minimizing the gamma-sensi-
tivity (i.e., using phosphors which are only beta-sensi-
tive) would minimize the "chance" rate, at the detection
stage in the analysis. Also, the use of high—efficiency
detectors (i.e., larger phOSphors) would minimize the error
in counting the weak intensities involved.

If the 1.14-Mev. level is pOpulated by gamma transi-
tions from either the 1.42-Mev. level (i.e., a 0.28-Mev.
gamma transition) or the 1.30-Mev. level (i.e., a 0.16-Mev.
gamma transition), the low-intensity (0.05%) of the re-
lated ground state gamma transition would present similar
difficulties as in the above possibility. The counts in
the low-energy region (below 0.485-Mev.) are extremely
high (See Fig. 6), this again would raise the "chance"
rate. Another contributory factor to the high count rate in
this region is the amplifier noise (these are spurrious
voltage pulses put out by the amplifier itself); besides
the "background" counts (radiations from other sources).

These difficulties (mainly the unavailability of the
vital equipments) gave cause for not pursuing the coinci-
dence investigation any further than evaluation of the
problems confronting any future investigation along this
same path.

THE LITERATURE RESEARCH

A literature research was undertaken to summarize
the latest data on the isotopes: Tc96, Te119 and Telal;
the findings to serve as a point of embarkation for fur-
ther investigations of these isotopes. The latest hypoth-
eses as well as some of the informative and novel proce-
dures were included in the summary in order to aid in any
future experiments on these isotopes, as well as on any
other which may be related.

I. TECHNICIUM96

(1) Source Preparation:

A. Naturally occurring Mo was irradiated with 7-Mev.
protons. The sample was then chemically separated

from Mo and electrolytically deposited on a foill.

B. To96 alone was produced by irradiation of Nb93
foils with alphas of 15.5 and 15 Mev. These energies
were chosen to insure mostly (if not totally) an
(4:,n) reaction on the target.

C. Chemical separation of To activities was made by
heating the bombarded molybdenum oxide in a glass
tube which was cpen at one end. By temperature control

 

1 H. Medicus, A Mukerji, P. Preiswerk & G. de Saussure,

Ihys. Rev. 74: 859 (1948).

H. Easterday & H. Medicus, Phys. Rev. 89: 752 (1955)
(2nd Ser.).

54

2

(2).

55

the technicium oxide was made to condense in the
cooler part of the tube, whereas the less volatile
molybdenum oxide was not affected. The activity was
then removed with a drop of dilute ammonium hydroxide
and mounted on a thin Tygon foil.5

Findings of Various Experiments:

A. Gamma-rays:

The 770-, 804-, 840-, 1119- and 512-kev. group
was first reported through the discovery of a number
of conversion-electron lines using a magnetic lens
spectrometer. Furthermore, coincidence experiments
showed that the first three of these gammas are emit-
ed in a triple cascade (using Bi cathode counters in
accord with the measurements in a similar arrangement
with A1 cathode counters). From the intensity of the
lll9-kev. line (estimated from the recoil electrons
from brass in the spectrometer) and the coincidence
rate, it was concluded that this line is also emitted
in the same cascade. The 512-kev. line could only be
observed through its converted part. It was also
found that the number of cascade transitions is equal
to the number of orbital electron captures.4

B. Positron Emission:

From a sample prepared by irradiating Nb93 with
l7-Mev. alphas, a 51.5-minute positron activity was
observed using a trochoidal analyzer. Through a com-
parison of intensities, it was found that there is
one positron for every 104 transitions to the ground

 

3 Easterday, et al., 100. cit.

4

Medicus, et al., 100. cit.

56

state. Indirect estimation of the maximum positron
energy led to a value of approximately 400 kev. This
emission constitutes approximately 1% of all beta

5

transitions .

C. Conversion-Electron Lines:
The 751-, 786-, 822-kev. lines together with
those corresponding to gamma rays of 1119- and 512-
kev. were observed by means of a magnetic lens spec-
trometer. It was also found that 80% of all conver-
sions belong to the first electron group6.

D. Weak Cross-over Transitions:
The following were reported: 1.65-, 1.89-, and
2.59-Mev. transitions7.

E. Spin-States and Nature of Transitions:

The data for the 104-hour ground state of Tc96,
the absence of strong cross-over transitions in the
triple gamma cascade, the absence of positrons as well
as a direct transition to the ground state; were the
assumptions made in assigning a Spin of +7 (at least)
to this state. Also, the half-life of 51.5 minutes
and a K/L ratio of 1.2 i 0.5 agree with an assignment
of a magnetic 25 to the isomeric transition (54.4 kev)
and a spin of +4 to the isomeric state. A proton in
the g% state and a neutron in the g% state might add
to a spin of 7. For the Spin 4, the proton might re-
main in the g% state while the neutron goes over into

an 3, state .
2

 

03‘J<m\n

Medicus, et al., loc. cit.

Ibid.

Preiswerke.& Stehelin, Helv. Phys. Acta 24: 501 (1951).
Easterday, et al., 100. cit.

F.

I+6

+6

+4

+2

+0

57

Proposed Decay Schemes:

(i) From the investigation of conversion lines
(From Easterday, et al.; see footnote 2):

96

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 12 Proposed Decay Scheme of To .
%
Tc
i‘h4
0.0344
+ 7

I
I
l
' T
| I
l I
I I “‘9
I I
| I
I I -
| l i
i | I 047' (Broken lines represent
I : I weak cross-over transi-

| I

I I

I I

l i 0.842

I I

I i

1 y

 

 

58

(ii) From spectrometric studies on both Nb96 and
To96 (From Preiswerke, et al.; see footnote

7):

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

96
Te
45
\ I I
.......... luau/“....
§a__4e- * :
I
I
560 1- '
(en-.07? 80"} : |||9
[m5 16,0] 14’ i
[3514] I
2.38 00:377. (“337° I
as? + 4 k 'w] ;
E3215):.1 If”? 311/4
3" 11': 5 *7 ° 0 3
15" t "5 1 g: 41%
£214}
77!)
I002
[$2,0‘tzaol

 

 

95
Mo

42
Fig. 15 Proposed Decay Scheme of Tc96 and Nb96.

(?)--- Not ascertained.

II. TELLURIUM119

(1) Source Preparation:

A. Metallic Tin was bombarded with 22-Mev. alphas

from a cyclotron. A thin layer of the target (1 - 5
mils) was then dissolved in 12N H01 and then TS and
Sb carriers were added. The Te metal was then precip-
itated by adding SO2 and hydrazine hydrochloride and
centrifuged. After decanting and washing, the precip-
itate was redissolved in dilute ENC}. SOme more Sb
carrier was added and the same procedure was repeated.
The source was finally obtained by evaporation of the
nitrate

Sources derived from the oxides were prepared by
fusing with KHFa, diluting and depositing the Te on a
capper plate by the electrochemical process. Then the
Te was dissolved and further purified by the S02 meth-
od. For use with a permanent-field Spectrometer, the
electrochemical deposit of Te.on the thin c0pper plate
can be used directlyg.

B. In another instance, the crosssection was obtain-

ed as a function of the bombarding deuteron energy

and in this particular investigation, 50-Mev. deuterons
resulted in a maximum cross section of 77 millibarns

on the 1 mm. thick antimony target 10.

In the Spallation study mentioned above, a num-
ber of radioactive nuclides have been identified from
the result of irradiation of metallic antimony. Chem?
ical separation of Te had been achieved by the follow-

 

90. Kocher, Allan C. Mitchell, C. Creager & T. Nainan,

10

M. Lindger 8:. I. Perlman,

Ph 3. Rev. 120:1548 (l960fi.
ev.
39

78: 499 (1950).

4O

ing process. The irradiated antimony metal was dis-
solved by covering with concentrated hydrofluoric acid
and the dr0pwise addition of concentrated nitric acid.
After dilution, Te carrier was added and the solution
made 0.1M in H01. Yttrium and Silver products were
precipitated as yttrium fluoride and silver chloride.
The remaining solution was then buffered with sodium
acetate and the sulfide-insoluble activities were re-
moved by the addition of indium and precipitation of
indium sulfide with hydrogen sulfide. After expelling
the excess hydrogen sulfide, the supernatant solution
was then evaporated to dryness and taken up in 2M H01.
Tellurium was reduced to the elemental state by treat-
ment of the hot solution with sulfur dioxidell.

(2) Apparatus:

A variety of instrumental set-up were used in
one particular investigation of the Te119 isotope. To
study and measure the positron distribution and the
energies and intensities of IC electrons, for instance,
a magnetic lens Spectrometer was used. To measure the
lower-energy IC electrons, a permanent field photo-
graphic recording magnetic Spectrograph was usedla.

In another case, 10 electrons of 0.2-Mev. and 0.5—Mev.
were measured with a low-resolution beta-ray Spectro-
meterla.

The gamma-rays and their relative intensities
were studied by means of a scintillation Spectrometer.
The 5" X 5" NaI (Tl) crystal was used in conjunction
with a 5—inch (dia.) Dumont Type 6564 photomultiplier

tube, and the pulse-height distribution was fed into a

 

i; Lindner, et al., 10c. cit.

15 Kocher, et al., .op. cit., p. 1549.
M. Lindner & I. Perlman, Phys. Rev. 75: 1124 (1948).

41

loo-channel analyzerl4.

The gamma-gamma coincidence investigation was
carried out using two 1%" X 1%" Hal (T1) crystals,
while anthracene ph08phors were used in the positron-
gamma coincidences. Two types of coincidence circuits
were used for both cases. A "fast-slow" coincidence
circuit with a resolving time of 0.1,flsec. was used
with two single-channel analyzer, and also with a
loo-channel analyzer having a single-channel analyzer
as the selector. The other type of circuit used two
RCA 6810-A fourteen-dynode tubes. The anode Signal was
first put through a limiter, clipped and then fed into
a fast coincidence circuit. The pulses which allow
energy selection were taken from the seventh dynode,
passed through a linear amplifier and single-channel
pulse-height analyzer and into a triple coincidence
circuit, into which the pulses from the fast coinci-
dence circuit were also fed. To display the coinci-
dence Spectrum on the loo-channel analyzer, the ana-
lyzer was placed in one leg of the Slow coincidence
circuit. A single-channel analyzer on the other leg
selects the energy of the gamma-ray of interest. The
resolving time of this circuit was approximately 15
flsec.15.

(3) Experimental FindingS:

A. Pbsitrons:
(a) Higher-Energy group:
This group showed a half-life of 5.6 days, an
end-point energy of 2.7 Mev., and a log ft of 7.90.

 

'14 Kocher, et al., op. cit., p. 1549.
15 Ibid.-

42

This log ft value is too high to fit in the systemat-
ics of Tellg. However, if this positron group is as-
cribed to the 5.5-min. Sbl18 which is in equilibrium
with its parent Te118 as a result of an (&,2n) reac-
tion; its end-point energy and log ft value (5.6) are
in reasonable agreement with the previous information
on Sb118

that these high energy positrons come from Sb

. Further study was made in order to verify
118 as

a result of the nuclear reaction on the metallic anti-
mony. Plates 0.001 mm. thick were milled off from the
antimony target and the ratio of the number of posi-
trons of the higher energy to those of lower energy
were studied as a function of the depth in the target.
The ratios decrease very rapidly as a finction of the
depth below the surface, indicating that it is by an
(.6, 2n) reaction. 16

(b) Lower-Energy Group:

After correcting for the higher energy group,
this particular positron group exhibited a half-life
of approximately 15 hours (this value is not consider-
ed very accurate), and an end-point energy of 0.627
1 0.002 Mev..l7

B. Gamma Rays:

The following table gives the Observations from
the gamma ray investigations. The results given there
were obtained when ordinary metallic tin was alpha-
bombarded so that lines owing to other long-lived Te

 

16 Kocher, et al., 0p.'cit., p. 1550.

17 Ibid.

45

activities were present. These served as checks on the
energy calibration of the permanent field and the mag-
netic lens spectrometers. The relative intensities
were taken early enough in the run so that the lines
arising from long-lived activities made a negligible
contribution:

Table I. Energies, relative intensities, and half-

 

 

 

lives of the gamma rays of Te119

Energies from IC lines: Scintillation spectrometer:
Gamma—ray Half- Gamma-ray Relative Half-
Energy (kev.) Life Ener Intensity Life

(kev.
155.0 1 0.1 5.5 days 155 112
270.0 i 0.1 4.58 ,, 270 54
. . . . . . 511 ...
(ann. rad.)

645.0 1 1 15 i 2 hr 645 (20) 15 i.1 hr

. . . . . . 950 22

. . . . . . 1100 21
1221 i l 4.6 days 1220 100 4.8 i 0.2 d.

. . . . . . 1760 (1) 18.5 i 1 hr.

. . . . . . 2120 7 4.5 i 0.5 d.

 

It was observed that the lines can be classified
according to their half-lives: the 0.645- and the
1.76-Mev. lines (15-20 hr. half-lives), and the rest
(of about 5 days half-life). The experiments showed
that there seems to be no growth or decay of one sys-
tem from the other; implying that the lifetimes of the

of the isomeric states involved are governed to a
large extent by their several transition probabilities

 

18 K0

cher, et al., 0p. cit., p. 1549.

to the states of Sbllg, rather than by the gamma-ray

lifetime for isomeric transitions in Tellg. Similar
situations exist in a number of Te isomers.19

(a). Results of Coincidence Experiments:

Table II. Coincidences in the 4.7-day Te isomer20
W

 

Selected Gamma-rays Gamma-rays in
(Mev.) Coincidence
2.12 0.270
1.22 0.950, 0.155
1.10 0.270

 

There was no coincidence between the 0.645- and
the 1.76-Mev. gamma-rays. PoSitron-gamma coincidence
tests produced null results with the 0.645-, the 1.76-
or the 0.155-Mev. gamma-rays. With this particular
coincidence experiments on the 16-day Te isomer, the
extraneous effects of an (£,2n) reaction on the tar-
get have been corrected for.

(b). Internal Conversion Coefficient of the 0.645-
Mev. transition:

A comparison method was used with the aid of a
magnetic lens Spectrometer, with 03137 as the stand-
ard. IC electrons were counted for both isot0pes and
the intensities of their respective gamma-rays were
then measured with a calibrated scintillation count-
er. This yielded an IC coefficient and = 4 X 10’5

 

19 Kocher, et al., loc. cit.
20 Ibid.
21 Kocher, et al., op. cit., p. 1551.

45

(i 10%), on the 0.645-Mev. gamma-ray. The theoretical
value for the (K.+ L) is either 5.9 X 10-3 or 4.9 X
10-5; the experiments are not good enough to differen-
tiate between 22 and /€!1 but it iS quite clear that
this particular line cannot have either an E5 or an
M5. This particular gamma-ray is of M1 or E2 charac-
ter so that its State of origin must be of Short life
compared with the resolving time (10-7 sec.) of the
positron-gamma coincidence experiments. An assumption
of a long-lived state cannot account for the absence
of positron-gamma coincidence with this particular
line.

(4) Hypotheses:23

The product nucleus, 51Sb119 has one proton out-
side of a closed Shell. The ground-state configuration
for this nucleus would be 5/2 +, 7/2 +, 5/2 +, and
1/2 + . However, these experiments are not detailed
enough to give definite information on these predic-
tions. The reported half-life of the 0.155-Mev. state,
0.84 X 10'9 sec.24 is in agreement with an M1 (10%) +
E2 (90%) mixture for the transition from this state to
the ground state. The K/(L + M) ratio of this line
was found to be 7.850. The theoretical values are M1 =
8.55 and E2 = 5.48. Such a hypothesized mixture would
then agree with a 7/2 + to 5/2 + transition. The
K/(L + M) ratio for the 0.270-Mev line has also been
measured and found to be 5.77 which when compared
with the theoretical values, M1 = 5.52 and E2 = 4.16
(Similar mixture as the 0.155-Mev. transition) would

 

22 Kocher, et al., op. cit., p. 1551.

25 Kocher, et al., op. cit., p. 1552.
24 T. D. Nainan, Bull. Am. Phys. Soc. 5: 239 (1960).

46

agree with a 5/2 + to 5/2 + transition. This im-
plies that the level assignments for the excited

states of Sb119
fication by means of an angular correlation experiment

may be correct, although a final veri-

may be necessary Since the above ratios are not very
sensitive functions of the multipole order in this
region.

The ratio of the relative number of IC electrons
of the 0.645-Mev. line to the number of positrons of
the low-energy group, the figures for the IC coeffi-
cients and the relative intensities of the two gamma-
rays (from the Short-lived isomer); these estimates
led to a log ft value of 6.9 for the positron transi—
tion and 5.2 for the transition to the 0.645-Mev.
state. This implies that the latter transition is a
once forbidden.

It was also hypothesized that the hfi state lies
higher than the 3% state and that the (13/2 state lies,
close to the hfi state, insuring a transition of long
half-life (about 200 days) which cannot compete with
the 5-day electron capture. Hence the gamma-ray result-
ing from this transition would be extremely weak. The
weak positron group would be in agreement with a tran-
sition to a 5/2 + state but not to a 5/2 + state.

A contribution from the weak 16-hour positron activ-
ity may account for the somewhat-Shorter half-life
(4.58 days) of the 0.270-Mev. state as compared to the
other states associated with the 5-day decay. The al-
lowed nature (once forbidden) of the 0.645-Mev. state
would suggest that this iS the 1/2 + state of Sbllg.
If the assumptions are correct, the 3% state oflfg
would lie 1.92 Mev. above the ground state of Sb

and the hwz state at greater than 2.59 Mev. The hWQ-
5%: energy difference would then be 400 to 500 kev.

47

(5) Proposed Decay Schemes:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

______ 1M}?~
239 h.,-—«*”’V’ no
_ 5,9.
O. 30 .
2(7) Mev. 292) Mev
[0 O4] OAS]
2nuf
I.37 ‘59
[0.05]
no Mev
(20
[“21 |.22 Mev. o' 5‘
(mm 5
[0.60] / o... o, 62.7 Mev.
/ (Ice)
0.270 3/z+
“'53 "—Womv. wig-v.7 . ”72*
J (54) (IIZ) /
[0.32] [o 6"]
O 5 +
II9 {2
38 hr. SB

Fig. 14 Tbntative decay scheme for TS

119

For the 5-day activity the relative intensities of the
gamma-rays are given in parentheses, with the intensi-
ty of the 1.22-Mev. gamma ray = 100. The fraction per

disintegration is given in square brackets.

 

25 Kocher, et al., op. cit., p. 1552.

25

2

III. TELLURIUM121

(1) Source Preparation:

A. Hilger Sb metal lab No. 11707 was activated with

lO-Mev. deuterons. This metal was then dissolved in
aqaa regia and then evaporated to dryness. The resi-
due was taken up by the hot dilute HCl and an excess
of tartaric acid. Te was precipitated from this solu-
tion by hydrazine dihydrochloride.26

B. Naturally-occuring antimony was irradiated with

l5-Mev. deuterons from a cyclotron; a (d,2n) reaction

produced mixed Te121 and Te125. 0ne gram of the irra-
diated antimony and 1 mg. of Te-free selenium were
dissolved in aqaa re is, heated to dryness, and then
redissolved in 5N H01. Both the selenium and the rae
dioactive Te were precipitated by bubbling 802 through
the solution. The selenium acts as a carrier which e-
liminates the need for adding Te carrier in this step.
The precipitate was then dissolved in the smallest
possible quantity of 12N HCl (about 5 ml.). One micro-
gram of Te, which had been dissolved in aqaa re is,
heated to dryness and then redissolved in 12N H01, was
added as a carrier. This minute amount suffices be-
cause we have only a very small amount of material at
this point, the great bulk of material being removed
in the first separation. 802 was again bubbled through
the solution. Only Se is precipitated with 12N HCl,
the Te remaining in the solution. By this method a
source of 100,Mcuries activity having a mass of 1,Mg.

was prepared.

 

6 J. E. Edwards a M. L. Pbol, Phys. Rev. 69: 140 (1946).

48

49

The Te was vacuum-evaporated from a small pyrex
oven unto a formvar film.(<9yug/cm.2) which had been
coated with either aluminum or silver conducting lay-
yerS (<4,ug/cm.2). The thickness of the source mate-

rial itself was less than 1,I.I.g/cm.2.2'7

(2). Results of Various Experiments:

A. The high intensity of the observed Te X-rays is
accounted for by K-capture in Te121 followed immedi-
ately by internal conversion of the 0.214-Mev. gamma-
ray in the singly-ionized K-shell. The X-ray is then
emitted by the Sb atom having both K-electrons miss-

ing. The X-ray wavelength emitted by this process
would differ slightly from that of Te.28

Furthermore, since both Sb X-rays and a 0.575-
Mev. gamma are associated with the 154-day as well as

the 17-day Telzl; these two activities logically con-

29

stitute the isomeric pair.

B. Gamma-rays:

(a). 0.070 Mev. (scintillation spectrometer?o

(b). 0.082 Mev. (through 10 electron-gamma
coincidences

(0)0 00214 MGV ( 99 a: :9 a9 )52

(d). 0.506 Mev. (scintillation spectrometer?)

 

3211. Goldberg 8. s. Frankel, Phys. Rev. 100: 1551 (1955).
Edwards, et al., 100. cit.

29 Edwards, et al., op. cit., p. 144.

OBhatki, Gupta, Jha & Madan, Nuovo Cimento 6: 1466 (1957).
1R. Katz, R. Hill, a. M. Goldhaber, Phys. Rev. 78: 9(1950).
32 Bhatki, et al., 10c. cit.

35 Ibid.

50

(e). 0.575 Mev. (scintillation Spectrometer)54
(f). 1.150 Mev. ( ,, ,, >55

C. Radiations in Coincidence:

(a). The 0.214-Mev. gamma and electrons from the
82 kev. transition (through a variable field, 1800
focusing beta-ray Spectrometer with a "double-Slit"
Spectrograph insert).56

(b). The 0.506-Mev. and the 0.070-Mev. gammas
(scintillation Spectrometer).57

D. Relative Intensities of Conversion Lines:58
Table III.

MILL:

IC Line Area under line Peak height Relative

 

 

 

 

(arbitr. units) (arbitrary I ' Intensity
(kev.) units) (ave. of
area &
peaks)
82-K 5420 i 850 506 i 26 75
82-L 3950 1 980 475 1'26 100
82-M 560 i 140 107 i 52 18
214-K 571 i 57 108 i 7 16
214-L 55 i 5 14 i 5 2.2

 

 

54 Bhatki, et al., loc. cit.

55 Ibid.

56 Katz, et al., 100. cit.

57 Bhatki, et al., op. cit., p. 1467.
58 Katz, et al., op. cit., p. 10.

51

E. Nature of the Isomeric Transitions:59

Using the above relative intensity values, IC co-
efficients and NK/NL ratios were computed and the
values so obtained are between a 24 (mag.*) and a 25
(elec.*) for the 282 kev transition, and between a 21
(mag.**) and a 22 (elec.*) for the 214-kev. transition.
Furthermore, the NK/NL ratio so obtained for the 214-
kev. transition is between a 21 (mag.+) and a 22
(elec.+). The theoretically obtained half-life
x-(1 + Ne/Nqo was found to be 1.0 X 1010 sec. for the
82-kev. transition.

F. Angular Correlation Measurementszl+0

Using a thin-lens beta Spectrometer as the fixed
detector a scintillation counters for the movable de-
tectors, the measured correlation was found to be of
the form: 1 + A2Ph(cos 0); in agreement with the the-
oretically predicted angular correlation for the known
5/2
1/2). The measured values of A2 (corrected for geome-
try) are: -0. 015 + 0.007, -0.007 1 0.007, and -0.10
+ 0.04 for the K-, L—, and the K-K cascades respec-
tively for Telal. Comparing the first of these coef-
ficients with theory, Shows that the second transi-
tion is a mixture of (5.6 i 0.50)% E2 and 94.4%IM1.

 

 

spin sequence in the Te isomers (ll/2

 

39

**

40

Katz, et al., 0p. cit., pp. 10-11
Theoretical values for this ratio was obtained from Hebb

& Nelson (Phys. Rev. 58:486, 1940) and Drell (Phys. Rem

TgéoreticaTAvalues for this ratio was 9fr m the curves
by Lowen et a1.(Phys. Rev. 75: 529,149)

Theoretical values for this ratio was 9from Rose, et al.,
"Tables of K-Shell Conversion coefficients" (privately

distributed).
Goldberg, et al., 0p. cit., p. 1550.

52

Using the Biedenharn and Rose notation, the ratio of
reduced matrix elements is plus. The results of the
K—K angular correlation is consistent with the K—‘7
correlations and are used to prove that the correla-
tions, which are smaller than the M4—Ml correlation,
cannot result from reduction of the M4-Ml correlation
by the action of extra-nuclear fields.

G. Utilizing the data obtained by microwave tech-
niques, the electric quadrupole moment for this daugh-
ter nucleus was found to be; Q = -1.5 X 10-24cm2. 41

In another investigation, where a hollow-cathode
discharge tube was used and a Fabry-Perot etalon for
resolving the hfs; the result was, Q = (-O.55 i 0.10)
X 10'24 cm? It was further explained why the original

value given above is not valid.42

 

41
42

G. Sprague & D. Tomboulian, Phys. Rev. 92: 105 (1955).
K. Murakawa, Phys. Rev. 100: 1569 (1955).

55

H. PTOposed Decay Schemes:

(i) Izun1f

 

 

 

 

 

 

 

 

 

 

 

 

 

9“ d Te m.
// 82 ml /2
/1 d3/2
,/ 2J4 kan
/
,/ / / :74 Tel“ 5":
||30 kev. /
Ec
8W2
187.
. 575 kev.
506.166» / 70k".
0 d5,
ESLIZI

Fisoléi Tentative Decay Scheme for Telel"

(From Bhatki et al.45)

 

43 Bhatki, et al., op. cit., p. 1468.

INTERNAL CONVERSION COEFFICIENTS

 

An excited nucleus with excitation energy less
than the binding energy of any nuclear particle may de-ex-
cite by either one of two competing processes: (1) by
emission of gamma rays; or (2) by internal conversion. The
ratio of the transition probability of (l) to that of (2)
is defined as the internal conversion coefficient (total).
This total conversion coefficient is found to depend very
strongly on the transition energy, the atomic number Z of
the emitter, the binding energy of the shell (or subshell)
from which the IC electron originated, the multipOlarity L
or angular momentum of the radiated field (the competing
gamma emission) and the character of the nuclear transition
(electric or magnetic) which in turn uniquely determines
the nuclear parity change once L is fixed. It does not,
however, depend on the nuclear wave function, since it is
only a measure of the probabilty of one of the competing‘
processes (as compared to the other) and not a measure of
the transition probability of the nuclear decay itself. It
may, however, give a clue to the nature of the electro-
magnetic emission.

Comparison of the theoretical (e.g., the independent-
particle model) and the experimental (e.g., half-lives of
gamma transitions) would allow a deduction of the multi-
polarities of the gamma transitions. In addition, this may
give information on the angular momenta and the parities of
nuclear states by direct measurements through angular cor—
relation experiments.

To furnish the theoretical side of the comparison, the
internal conversion coefficients tabulated by Rose* (for

 

* M. E. Ross, Internal Conversion Coefficients (North-
Holland Publ. 00., Amsterdam, 1958).

54

 

55

the atomic numbers 42 and 51) were plotted as a function of
the gamma-ray energy (in units of the electron rest-energy
in Mev.). From the resulting curves, the associated inter-
nal conversion coefficients for 42111096, 51Te119 and SlTelal
(for their respective gamma rays of energies up to about
200 kev.) were interpolated (the results are in Tables I
to XVI, Appendix). Using the equations on p.56 (Appendix),
the half-lives associated with each gamma transition (for
both electric and magnetic; up to L = 5) were calculated
and tabulated (See Tables XVII to XXXII, Appendix).

These theoretical estimates (Weissk0pf) are to be
compared with the results of angular correlation experi-
ments in the future.

APTENDIX

Half-lives of Gamma Transitions:

Using the independent—particle model, Blatt and
1

 

Weisskopf arrived at expression (currently known as the

Weissk0pf estimate) for the (partial) half-lives of gamma
transitions. These expressions have been tabulated2 in
more convenient forms (for different multipolarities) us-
ing a nuclear radius constant of 1.2 x 10'15 cm. The Table

is partly reproduced here:

Half-lives of Gamma Transitions

 

 

 

 

 

 

L Tfi (e1)
1 6.75 1'2/5 E‘3 x 10'15 sec.
. 2 9.57 1'4/5 3’5 x 10'9 sec.
5 1.98 1'2 E‘7 x 10“2 sec.
L T% (magn)
1 2.24 A0 E.3 x 10'14 sec.
2 5.12 1'2/5 E‘5 x 10"8 sec.
5 6.60 A-4/3 E'7 x 10"2 sec.
1 J. M. Blatt and V. F. Weisskopf, Theoretical Nuclear
Physics (Wiley & Sons, N. Y.,Il952) p.627.
2

A. H. Wapstra, G. J. Nij h and R. Van Lieshout, Nuclear
Spectroscopy Tables North—Holland Publ. 00.,

Amsterdam, 1959) p. 71.

56

57

Appendix: (Continued)

The tabulated expressions refer to the transition
probability associated with the emission of multipole
radiation. In order to get the actual lifetimes of the
associated gamma transitions it is necessary to correct
for the transition probability associated with the in-
ternal conversion process:

e1
magn

(1 + OCT) T 91 (1)
agn

T75 (v)

where “:T is the total conversion coefficient,
given by:

OCT = OCK + 1.28 (OCLI + OCLII + OCLIII).

The .dC-subscripts refer to the particular shell (or sub-
shell).

58

Appendix: (Continued)

Tables of Internal Conversion Coefficients*:

I. For Gamma Rays of M096:

 

 

]:,For the 0.216-Mev. Gamma Ray (k = 0.4227)

C21 C12 C23 /5L zég .433
K" 5'16“ My (.13 6,37 c-z) 2.9.51.4) 2,74 {-2) /.5‘2 [-0 7'37 ['0
LI-Subshe“ A22 [—3) 6.50 («3) 2.3%- (—2) 3.27 {—3) 45/0 {—2.} 220 {—2.

 

LI—Sutshcll .5100 {—r) 1.x: («3) A75! {-2) /.27 {—y) /.27 /-3) /.,7 (‘2.

 

L

Ln I SubsI-uc" Z7! f—S’) /.25'/-3) ”7(4) 4.20 [—5) [.20 (4) Mi: {-2.}

 

 

 

 

 

 

 

 

 

 

 

21" /.35‘(—-3) fiflK-J) 6.17/4.) 3.41% {-3) 2.0/f—2) /.26 {-0
K/ 2L £74 7. /5' 4!. 7f 50.: 7:37 5775'"
L1 / / I / / /
(#1,, o.°¢lo 0. I715 (1.6/05 0.03” o-o7aL oJ/Iz.
L / / / / / K
m- 0. 0‘3! 04723 05374 0.012! 0.0.156 04° "°

 

* Interpolated from curves constructed with the values
given by Rose (CZ'S for electric, A3's for magnetic;
numbers in parenthesis are the powers of the factor,,
10). Subscripts of the coefficients stand for the multi-
polarity, 1. The R value stands for the gamma energy in
units of the electron rest energy (in Mev.).

Appendix:

59

(Continued)

 

 

 

 

 

 

 

 

 

 

 

 

II.For the 0.258-Mev. Gamma Ray (k = 0.466)
C11 2 C1: .AZ /55 /45
K-Shell 7.;0 (~3) 41.50 {-2 2.0/ (4) Z./6 {-2) /./3 [-1) 51m {—4)
H-Suhskcil 9.40 («4] 4.63 {—3) A94 {—2) 2.57/15) /.30 {—2) 6.5314)
LfiI-Subshell 3.60 {—5) 7. 5'0 {—7) /.03 {—2) 7.4! (4} 7.7514) 7. 757-:
L111: -Subsh¢ll 5260 {—5) 7.00 [—7) 9./0 {—3) 3.34 {-5) 5130(4) £70 {-3)
21‘ A03 {-3) é./i'/-3) 3196-2) 2.67/4) AWN-2) raw—.2)
K/ZL 2m 7.5/4! mi two 738/ 6.2:”
L1 / / / / ~/ /
1/ / / / / / /
//L 00333 07420 0.5307 0.0376 0.068! 0-//37
L / / / / / /
I 0.05% 0.1723 0747/ 0-0/3/ 0.0.10: 04344!

 

 

 

 

 

 

 

 

 

Appendix:

III,For the 0.512-Mev. Gamma Ray
=:

60

(Continued)

 

 

 

(k = 00611)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

01 02 0: fli fl: fls

K "SheH 4.37 {—3) /.P2 {—2) 4.70 {-2) LOPEZ) éééof-J /.77(—/)
LI—Subshcll 4,5054) L176 (’3) 5.70 (,3) /.2¢{—3) 53/0 {—3) 2./7[*Z)
LI ..Subshell A42 {—5) gas—r45) 2.517(4) 7/77—55 3.33 {—7) 2.x; {-3)
Ln; - Subshc“ 2.2/ {-5) 2.21 {—4) ”WK—3) A4745) /.6/ {—90 2./o/-3)

ZL 74/1 {—40 2.3/ {—3) /./2 {—23 A3043) 5.7063) 2.4042)

K/ZL flfl/é 721’? 5.07 £33 7.70 5-7/

IV.For the 0.451-Mev. Gamma Ray (k = 0.885)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a, a, a, A”, A A
K-She“ /.47(-:) 516363) ALI/#2) 44375-5) /.¢?[-2) 445362)
LI-SUBSMH /.7{/[—-{l) {Jo/.7) ma (.3) goo/«40 /.7.2/-3) 51706:)
LII-5‘49“" 7.27/4) 7.73M) 3.90M) 734 x-r) 24177-0 4427M)
LI-Subshefl 4.77/1) 4.204;) 2.4414} 51077—4) 3.3.51.5) 2.77/49
21.: /. 187—4!) Lad—4!) 2.39 {—3) .57/7/—¢j AF¢é3J 4J2 f—3)
K/ 2L £0.25“ [ti/A? 29¢ £5425“ r.” 714/2

 

 

 

Appendix:

61

(Continued)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VLFbr the 0.560-Mev. Gamma Ray (k = 1.096)
r___ _
Cir1 a, (23 fl, fl, fl;

K- Shell 9.9967) 2.97f—3) 727.763) 2.6343) 7.7763) 2.5442)
L: 5055“" /.06 {—4) 3.): {—7) Mezzo 3.0/7.7) 9.00440 .25: (.3)
LI ..Subshell 2./7(—6) 2.0/ {-5') 734/ fl7) 7.20 («6) 3.7765) /. 70 (~70
Lm—Subshcll 3.53M) 470(4) 7. 751-5) 271(4) Aarfir) 2 7.7/10

21' /-/-Z {—50 3.53/40 A06 (“3) 3.///—¢J Raf-40 2.173(4)

K/ 2L 1’. 7.3% 550/ 2369’! 145157 1.37% 7.54

V]. For the 0.725-Mev. Gamma Ray (1: = 1.418)

fl fl fl

01

 

 

 

 

 

 

 

92 a: 1 2 3
K’Sl’m" 550(4) /,y;{..3) 3451-3) A5614) 3.70653) z/Of-J)
LI—Substcu 577.515) “7(4) 3. 74%;!) “7(4) {1.4/rfl-flA/0f-3)
Ln—Subshcll 400(4) zai/K—c) mafia 3.51M) xii/J) 571/Ar)
Lm-Subsh¢|| We.) 4.0.4.) 2.0/4) 7375-.) won) 2.57m)
2L 4.” (4) /.72 [-40 5436(4) A72 [-7) 4.41/4) /./7 [—.:]
K/ :1. am? I. M: 7.7% 873/ nafl’ 7.7.2/

 

 

 

 

 

 

 

 

62

Appendix: (Continued)

VILFor the 0.770-Mev. Gamma Ray (1: = 1.507)

a a a fl fl fl

1 2 3 1 2 3

 

K’She“ {7 726.41) 727 (.3) :7. 705-3) /.26 (‘3) 33306-3) ZFD/“3J

 

LI —Suhshe|| 5125' {—5) 7. 357.4) 3. 73 Q7) 7. 4/3 [—7) 3.77M!) K 77/4

 

Ln: “S“bShe" 7.30M) 51737-7) 3.7365) 2751—4) 72:77.5) 7473(4)

 

Ln-Subslaell 7376-0) 4.77fi7) 7.57 6.5-) 7,776.7) 3.7.36.0) 10665")

 

 

 

 

 

 

 

 

 

 

 

21' 1747/45") 7. 7’6 [—7’) 3.57450 74/7670 3.77/40 257/41)
K/ZL £7774! 7.7.7.7 [4067 £523 [ca/’3 307,2
VII/.For the 0.804-Mev. Gamma Ray (k = 1.575)

C2, C22 a: 51 fl: 4:

 

K-Slaell 571/[67) 7741—3) 2.5243) 7.73 {—3) 2.73/-:) 6.77(-:)

 

 

LIISub‘he" firs-(d) A2365!) 2.77%;1) /. 37 [—51] 3.3.9140 7.7757)

Ln ..Sulnshcll Z3of-7) 44751-4) 2.6/ [-59 2.62 64) 7.70(—-:) 3.701;)

 

Lm-SUBSHCH [,7/_4) 7407/4) /.3,2/-$’) /.&7/—6) 3.3? {-6) /.6f(-59

 

214 5707/45) 7.3.: («40 3./i6¢) 7.35'{-y) 3.577(7) {4.73440

 

K/ 2L 7. £45? I. 777 7: 04/3 )7. 370 P. 3Y6 7. 933

 

 

 

 

 

 

 

 

 

Appendix:

65

(Continued)

lX.For the 0.840-Mev. Gamma Ray

(k = 1.644)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C71 02 03 fl: fl: fl:
K—Shell .70.- “) 703 7.3) 2.27 7—3) 7.0.2 {-3) 2.07 70) £77 {-3)
LI-SUBSM" 77.77- 7.5-) 72/ (~40 2.77 {-7) 7.77 {—7) 277 M} 7.77 67)
LI-SUbSHe“ 7.7/2 {—7) 7.2.2 (*6) .7./£ Ad 2.32 [—6) 7.442 6-6) 2.77 fig
LM‘SUbshen /. 04 [-5) 3.77/2) 7.07 (J) 9.5:: [-7) 2.1"? (1)/.377 fl!)
2L 7.6.2 {—5) 7.77 41/] 2.27 {-7) 7.22 {-7) 3.07 [—7] 7.73 {—71}
K/ 21- 57957 E 4717/ £02/9’ KJ/Ja £3735 £37ZI
II. For the Gamma Rays of Sbllg:
X.Fbr*the 0.155-Mev. Gamma Ray (k = 0.299)
CZ; C12 as fit ”2 fl:
K—Shell 075’ [—2) 2.90 {—7) /.7/7 0) 7.6? [-7) 7.77 (0) 4.30 (0)
LI-Subshe" 510;— 74) 2.00 [—2) 727(4) /.£’2 (.2) /.r2 {-7) 7.77 {a}
LI”SUb$h¢” £30 [4!) 7. 70 [-2] 3.527(4) /.07 {—3) 7.?0 £2) Ah {—7)
Lm—Subshell 6.0: [-6 717/4.) 235(4) 3.3 75:/[0) 54f7fl/J
ZL 1.0/£3) (./7/«2) 709/4) 7.76 {-2) 7.7! ('7) /.P/ (a)
K/ 2L 7,970 47.700 7.777 2577/ 0.3” 3.77.?
1;; / / 0.363% / / /
’1’: / / / / / /
/ 0.0!)? 0.473! / 0. 05,7 0.77/94 0.7.436
1L]! .JZEJT- «03;;2 <;;;:; 1:07;; 2:;72 ;:;;;0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix: (Continued)
XI.For the 0.270-Mev. Gamma Ray k = 0.528
= E (— — j.
C21 02 as ”1 fl: p3
K’sl13” A03 (_2) 51.3,? fig) 743 [—4) 3.60K—2) A66 {4.) 6.650 [-4)
LI ‘5u5"‘¢” 7.07 {.3} 7.512 (a) 7;; Fe) 377/0) 2.70 (4) 7751—2)
1.1;" 5055“” 7.57 7.53 7357—3) 7.72 {-2) 2.0.2 {—7) 7. 77 (3) 7.30 {—2)
Lm’sub’h‘" 7.77053 7.77 7.3) 7. 777—2) 5170 (~59 7.0700 7.7/7.2)
2L 7.22 (~3) 7.0514) 7357—2) 44-23(6) 2-4/0/'3) AZVK-U
K/ZL 7735' 4.2/3 3.75/7 5575' 6.73/ 522/1
LI / / oil/r / / /
/
J, 0.06/3 0.2977 / 0.0.6' 009/0 0.7374
L / / / /,_., / /
II 0.0790 0.247/ 0-7037 0071,47 00¢?! 0-7735
xu.For the 0.645-Mev. Gamma Ray (k = 1.262)

 

 

 

 

 

 

 

 

 

 

 

 

 

C11 C12 C13 /61 K3: /eb
K’SHQH 7.77 (-3) 3,77 (3) 7251—3) 7.03 [—3) 7.27 7,2) 27:” 6.2)
LI-SUbs‘W" 7.27/40 3.77 {—7) 7.77/4) 4477(7) 7.37 6:) 3.47/4)
LI-Subflvell 3. 77/4) 3.72 («5) 2.37 [-7) 7. 7/ ('5) (JOY-5') 1.2/(7
Lm-Subshe" 577/2) 2.717(4) 7.72 [—7) 5200/2) 2.73/4) (72 fif’]
2L 737(7) 2277—7) 727(3) 777(7) 7777—3) 777 («7
K/ZL £722 7.74/7 6.646 77.273 7.7.27 7,074

 

 

65

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix: (Continued)
XFor the 0.950-Mev. Gamma Ray (k = 1.819)
a1 a2 03 fit flz fl;
K-‘Shell 5.70 {-4) 7.37/4) 2.9r7f-3) 7.77 {-3) 7.2763) 701-3)
LI-Subshell 0.23 {—s') 7.52 {—4) 3.24 {-40 7. 77/47) 5207(4) 7.77/4)
Ln" Subsheu /.6/6 [—4) 710 (4) 411/ {—5) 5170 [-6] 015/{'65) Ziof-f
LI-Subbhefl 1,074,) 7.7, [.7] 74777-5) 7.7.2 {—7) 07751—4) 2.73/4")
21' 6-5'7Z—5) 7.67/4!) 3. 90(4) 7. 77/40 073/ A77) 7. :22 («3
“/2L 7.7367 7.760 7. 737 57.957 £067 7'57”
III. For the Gamma Rays of Sblal:
XIV. For the 0.070-Mev. Gamma Ray (k = 0.136)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a1 a: as fli flz ”3
K-Shell 574/514) 3. 0'0 (0) 2.7517) 7. 0'0 {0) 7.70 [7) 7.4112)
LI’Subd‘d' 54705-2) 3.00 {4) /.4/5'/o) /-65'[-—/) 3.75' [0) 44520)
Ln-Subskcll 6.7043) 410(4) 3.70 {7) 7257-2) arr/a7) 7. 4/0 {0)
LL-Subshcll 0, 007.3) 7207.7) 7. 0077) 0.30 -—3) 7.7047) 7.27/7)
2L 0'. 77f-2) 7. 70 70) 7.24477) 7. 707 {-7) 7775' 70) 9.07 (7)
K/ ZL 7.77.2 /. {/2 2.97? {-7) [12% «flfflo 7.73.5”
L1 / 0.326! 00342 / / /
1:” / / / / / /
/L 0.7773 0737/ 077:0 0. 070': 0-7727 0.77.“!
I 0. 2370 7 7 0. 0200 0. 2757 07/99

 

 

 

Appendix:

(Continued)

66

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

XVCFor the 0.506-Mev. Gamma Ray (k = 0.99)
C21 (ii C23 .K% /32 /65
K“Sh€u 2737-3) 7457—3) 7701—2) 7770 73) 2.37 {—2) 7.70/4)
LI—Subshcll 2.27 (~47) 6157—4!) 7.7773) 7. 70 [—41] 2.77/4) 7.7063)
LI‘S‘A’SMN 7.70 {—7) 9757—5) 7.20/4) 3.57 (—5') 7. 97 (~60 1’. 75(4)
I‘m" 5""553" 7. 77 (‘5) 7.00759 0.70640 arr/7) 0077-0) 0777—7)
21. 2.4/7 {-7) 7.52 HQ 2.77/4) 30-0-77) 3.73 [—3] 7.07/4)
K/ZL 7.77/7 7.570 0:72;! 7.757 7.5177 7.57%
XVLFor the 0.575-Mev. Gamma Ray (k = 1.125)

 

 

 

 

 

 

 

 

 

 

 

 

a1 a: as fl; flz fls
K- Shell Air/«3) 44737-3) 7.77/4) 0730 {—3) 7.77 /—2J 44351—2]
L1 ..Subshell 7. 77 [—7) 7.77/4) 7.27/5) 7.07/47) 7. 77/3) 5700/4)
L1-Subshel! 51777—7) {.77 {—r) 3.70/4) 2.7.770) 7.27/7) star/.7)
LII-3055M” 7777—7) 77.22 7.0) 7. 707—7) 7.75/7) 3.77/4”) 3.02 {—7)
2L 7.7067] sin/(4) 7.77/3) 7.37. {—7) 2.///—3) 7.37/—3)
K/ZL 7.723 7.777 7.777 7.375 7.777 7.777

 

 

 

6’7

Appendix: (Continued)

Tables of .HaIf-lives of Gamma Transitions for Different
multipolarities:

1. For M096

 

 

 

 

 

 

 

 

 

 

 

 

 

     

 

XVII. E = 0.216 Mev.
1.28 (0C, 1..) ‘CT T72 ($60.) T’ih) (sec)
E1 /. 725' {-3) /. 352 {—2) 3.74/54 {—717) 3. /i’7 [-750
E2 7770 /-2) 7. 570 («2) 4!. .275“ /—9) 7.732 {—7)
E3 Z f7?/— 2) J. 7410/ —/) 7. 7.27 {—7) 7. 777/ (. 7 )
Ml {77702 (.3) 3.200(4) 2. 757 [—72)‘ 2.223 (—— AZ)
M3 7.7/3 [-7) 7. 770 [—7) 3.707! (0) 6. 741.2 (a)
XVIII. E = 0°g?§_nEY1__ “pm“ ,_u -M_- __
1.28(0CL) OCT T’L (sen) 132(7) (SEC.)
BI 7. 32763) 70/72 {-2) .2. 372 (-77) 2.357 {—74)

 

E2 7.77043) 5339/ L2) «$770 [—3) 2.76/7 [—F)

 

E3 7.777(4) 2.5'07/-7) %777(—/) 3.977 {—7)

 

M1 3.775(4) 2.507 {—2) 7. 772 {—72) 7.727 f 41)
M2 7. 7751.2) 7777/7) 7777 /- 5) 7.723 {—7)
M3 page/4) {./4/7 (’7) 3.4/70 [0) .2./4/.7 ( 0)

 

 

 

 

 

 

 

 

 

68

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix: (Continued)
XIX. E = 00312 “ev.
1.28 («(1') OCT TY; (SEC.) T3 (7) (sec)
E1 7. z 25 {-4) 4. 77.2 {-3) /. 0.522 (47) /. 057 [—740
E2 2.952 /. 3) 2.”; [-2) Z 07/ /- 9] 7.2/0 (— 9)
E23 A42? (.2) 0.2.2? [—.2) 7.777 [#3) 7.475” («3)
M1 745-073) 7.24/7 [-2) 7.27; {—3) 7.375" {—3)
M2" 7. 575/71) 5.357 72) 7.777 (27) 5033 7- 7)
M3 3.323 {—2) /. 903 (4) 9’43” [—0 5.2/7 {-x)
XX. E = 0.451 Mev.
1.28 («L 1.) 0C '1‘ Tyz (556-) TyggY) (sec)
El .7. 377 (as!) 7707 7— 3) 3. 49.2 {—5) 3.4/77 {—Is')
E2 73527 («4) 7. 41777—3) /. /35' 7— 7) 7/4/2 '7— 7)
E 3 3' 053 {—3) /. 7757—2) 5355/ [—4) 5. 77/, (~40
M1 7. 737 (— 5‘) 52 034/ (’3) .2. 7130 {—759 .2. 776/2 (.45)
M2 2.353 {—3) 7725 {—2) 73%” {—7) 72775” [—7)
M3 7.737 (.3) 53/74 {—2) 3. 757 [#2) 3.717 {—2)

 

 

 

 

 

 

 

 

69

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix: (Continued)
XXI. E = 0.560 Mev.
1.2807.) 0C1: ’ Ty2 (sea) Tyzh') (5m)
E1 74/30 (.0) /./4/(-3) 772? (.45) 7.727 («6)
E2 44520 (...) 3.723 (.3) 3. 757 7x0) 3.0]. (-—/0_)
E3 7352 {-3) 7032 {-3) 723.; (~41) 7:47 {—7)
M1 3. 97/ {—4) 3.020 {—3) 7.272 (~43) /. 2.74 [—0)
M2 7220 {-3) 7. /20 {—3) .2. 77 {-7) .2. 702 {—7)
M3 3.722 {-3) 2.502 {-2) £477 (—/) (5674/ {-0
XXII. E = 0.725 Mev.
1.28 (0C I.) OCT T72 (SEC.) 135(1) (55c)
E1 Z722 {-5‘) 7.3.6261) 7.7/7 (~46) £7.23 (4‘)
E2 2.207(4) /.7// [—3) 7072 {—/0) /.07I/ 740)
E3 5:572 67) 44007 {—3) 2.03.2 {—5) @0510 [—5)
M1 2.20/ (.4) 7770 {—3) 5:”? {-77} 5:777 [-40
M2 5:70 7+0 7770 {—3) 7.377 («7) 77.2? [-7)
M3 7577 (.3) 70727-2) 77/0 {—0 77.27 [—0

 

 

 

 

 

 

 

 

7O

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix: (Continued)
XXIII. E = 0.770 Mev.
_—_¥__———
l.28 (oCL) .CT Ty.(sec) Tyz (’7) (sec;
El 7.777 {—5) 5.470 {-7) 7.027 (47) 7.0.3/ 777)
E2 7777 (.7) 77.77 7:) 7.777(4)) 7.77.7 (—//)
E3 .7, gm (.7) 3.370 (.3) 7377—!) /.337 f- 6')
MI 7773 44’) 7777 73) 77777 (47) 7. 777 (77/)
M2 5037(4) 3.7077— 3) 02777 /-7) £77.? £7)
M3 /. .237 7.3) 7. 037 (.32 7. 272 L7) 7.357 77)
XXIV. E = 0.804 Mev.

 

 

 

 

 

 

 

 

 

 

|.28(0CL) 0(1- T yz ($20.) Tyzh) (530.)
El 7. 7577-5) 5:77 {—7) 7477 (47) 7./73 {-M)
EZ 7770 [—7) 73/7 [—3) 7.375" {—7) 7.337 [-7)
E3 4407777) 27777:) 7.773 M) 7. 777 {—7)
MI /. 72¢ 77) /. 372 {-3) 74 3/0 {—70 7.307 (77)
M2 4.7172 [—7) 3.377 («3) 7.7/30 («7) 644/76“ (*7)
M3 /. 072 {—3) 7. m {—3) 7. 7/7 (~47) 7.700 [-7)

 

 

 

7l

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix: (Continued)
XXV. E = 0.840 Mev. J11
1.28 (ea!) OCT T7. (550.) Tysz) (550.)
E1 .2 7/47 7.5-) 7. 77/ 77) 0777.7 {~/7) 53 W7 (47)
E2 7579 /_ ,7) /./7’.2 [—5) 507/ [—//) 5:077 /—//)
E3 3.703 L7) 2.7.20€3) 7327/ {—7) 7.270 (*4)
M1 7575‘ {—7) /. /77 [—3) 3. 770‘ {—40 3. 777 [—40
M2 3‘. 7577-7) 2. 7f7f-3) 3:544" /-7] 3.507 {-7)
M3 9. /.23 (.51) 71$? [—3) 5:05.? {—3) 5:07? [—3)
2. For Sbllg:
XXVI. E = 0.15} Mev.
1.2802(1) °CT TX? (520) TVZC'Y ) (550.)
E1 7777 {—5) 7:727 [-2) 7.3.73 (47) 7.777 {—00
E2 7. 77742) 0.770(4) 4375' [-7) 7709 {-7)
E 3 /, 04/77.) 2.737(0) .2. 0/3 (v) 7. /2(/ 7— /)
M1 2.5'0ff—2) /. 73/ {-9 52.272 (—/.2J 7.257 (42.)
M2 2.37360 7707 [0) 6. 370 fit) /. 573” [—5)
M3 2.3/7 (0) 37/7 [0) 5:77! (0) 5274/5” 67)

 

 

 

 

 

 

 

 

 

 

72

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix: (Cnntinued)

XXVII. E = 0.270 Mev.

[28(0CL) aCT Tyz (St-Le.) Tyzh) (sec)
El 7573 {—3) 7x27 {—2) 7397 {—7) 74/3 747)
E2 7. 027(7) 527.2 [—2) 7077 [—7) /.//7 {-7)
EB 557772) 2.777 fix) 7777 [—2) 73.37 {—2)
MI 527/273) 77/77 #2) 7773 («72] /./3f/ /—/2)
M2 3. 777 {—2) 77/7 («4) 7.570 7— 7) ' 74977 (4)
M3 7.5% [-4) 7.077 M) r. 770 [—0 707? {7)
XXVIII. E = 0.645 M33;

|,23( oCL) °CT T}; (sum) Tyzh) (sea)
El /. 752 {—7) 73537—3) 7035’ [47“) /. 7737 (4;)
E2 5717/ (.7) 3. 759 {—3) 772.? [40) 76/37! {—M)
E 3 7777 L3) 7.77/0 {—3) :20 7W [- 5) 3. a// [-73
MI 7.2356 4) 7475363) 7' 307 {—450 17:37? (45/)
M2 A707 {—3) 7717/ (.2) /./37 [-7) /,/5-7' {—7)
M3 5327 (.3) 3.7173 {—2) 2.37/7 {—5) 2.4/27 [—3)

 

 

 

 

 

 

 

 

'73

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix: (Continued)
:5 XXIX. g: 0.950 Mev.
|.28(OCL) OCT T22 (553-) Tyz(’7) (sec)
El 7430 {—7) 7.773 {—7) 3.777 747) 3.777 {—7)
E2 2.777 {-7) 7777- 7-3) 2.277 {-7) 2.50/ (.7)
E3 4!. 777 f— 7!) 3. 770 («3) 2.327 [—7) 2. 334/ {—7 )
Ml 2.5/7/41) 2.0/2{-3) 2. 777 £77) 2.7.77 (47/)
M2 7. 700 {—7) 7.970 {—3) 774/7“ {—7) 7.7717 67)
M3 A537 43) 7.077 {—2) A757 [—7) 5777/ {-40
5. For Sblalz
m. E = 0.070 Mev.
l-23(°CL) °CT Tyz (sen) T12”) (sen)
El ’7. 376 (’2) .53/Y9 (—/) 57270 {43) £020 /—/3)
E2 .2. 432 (o) 5". 732 (0) /. 37/7! {—7) 7.3/7- {—7)
E 3 7. 2737 (w) x. 71237 (+2) /. 7.25- 7—2) /. 77/2 [0)
MI 2.3/4! {—0 /. 73/ '(0) 2.37/ {—7) 7.73/ {—7)
ML 5.3777 [0) 2.7357767) 2. 773 (— 5') 7.777 {—7)
M3 72/727772) 2.777276%) 41.757 (,0 7.337 [42)

 

 

 

 

 

 

 

 

74-

Appendix: ‘ (Continued)

XXXI. E = 00506 Mev.

[28(oCL) aC-T Tyz (sec) T337) (sat)

 

El 32/541 {-7) 2. 7757-3) 2.///’ £45“) 2.723 [.ny

 

E2 7 090 73) 7.770 [-3) 77757—70) 4. 720 {—xo)

 

E3 3.702 [—3) 2.070 («2) 7570 {-71} /. 5'72 («7)

MI 7097/73) 7777/ {-3) 7 7/5/ [43) 77.27 {-7)
M2 71.007 (.3) 7.77/ {—2) 3.77/ A?) 3.747 {—7)

 

 

 

 

 

 

 

 

M3 72777-2) 72777 7.2) 7277 {—2) 7.277 («2)

 

 

 

 

XXXII. E a 0.575 Mev.
|.28(0CL) OCT Ty. (SECo) 13/207) (SEC.)
El 2.30/ 77) 7 770 (.3) 7 777 {—7) 747/7 77:)

 

52 7.777 {—7) 72277 £3) 7.777 [—M) 2.7/7/ [—xo)

 

 

E3 .2. 37:73) 7377 {-2) 7.7/7 flfj 7,707 {—5)

MI 70737—7) . 7./07 {—3) 7/7/ [—0) M77 {-8)

 

M2 7.773 {-3) 7737 7—2) 7770 (,7) 2.027 {—7)

 

 

 

 

 

 

 

M3 7.773 («3) 5777(4) 520767 {—3) 5.307 {—3)

 

 

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BIBLIOGRAPHY

. M. Blatt & V. F. Weisskopf, Theoretical Nuclear

 

Physics (Wiley & Sons, N. Y., 1952) p. 627.

E. Rose, Internal Conversion Coefficients (North-
Holland Publ. 00., Amsterdam, 1958).

Siegbahn, Beta- And Gamma-Ray §pectroscoPy (North-
Holland Publ. 00., Amsterdam, 1955).

H. Wapstra, G. J. Nijgh &.R. Van Lieshout, Nuclear
§pectroscopy Tables (North-Holland Publ. 00.,
Amsterdam, 1959) p. 71.

S. Bhatki, R. K. Gupta, S. Jha, & B. K. Madan,
Nuovo Cimento 6: 1466 (1957).

Easterday & H. Medicus, Phys. Rev. 89: 752 (1955).
Edwards & M. Pbol, Phys. Rev. 69: 140 (1946).
Goldberg & S. Frankel, Phys. Rev. 100: 1551 (1955).

W. Kocher, A. C. Mitchell, 0. B. Creager & T. D.
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Lindner & I. Perlman, Phys. Rev. 75: 1124 (1948).
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Medicus, A. Mukerji, P. Preiswerke & G. de Saussure,

Phys. Rev. 74: 859 (1948).
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Sprague & D. Tomboulian, Phys. Rev. 92: 105 (1955).

79

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