COCOCN

AE-263UDC 539.t44.6:î46.862

Possible Deformed States in 115In and 117ln

A. Bäcklin, B. Fogelberg and S. G. Malmskog

AKTIEBOLAGET ATOMENERGI

STOCKHOLM, SWEDEN 1967

AE-263

POSSIBLE DEFORMED STATES IN ? 1 5In AND H ?In

by

A. Bäcklin*', B. Fogelberg*' and S. G. Malmskog

ABSTRACT

Levels and transitions in In and In have been studied from

the beta decay of 2. 3-day ] ' 5 g Cd and 2. 5-h ' 1 7 g Cd. Using a Ge(Li) de-

tector and a double focussing beta spectrometer) energies» intensities»

conversion coefficients and multipolarities were obtained for the follow-

ing transitions (energies in keV and multipolarities are given): In:

35. 63 (97. 0 % Ml + 3. 0 % E2), 231.47 (El), 260. 80 (Ml), 267, 336. 23

(M4 + < 5 % E5), 492. 14 (96 % El +4 % M2), 527. 70 (El). ? ] ?In: 71. 0,

89. 80 (E2 + < 20 % Ml), 273.32 (Ml, E2), 315. 27 (M4 + < 7 % E2),

344.29 (El), 434. 12 (El).

Using the delayed coincidence technique, half lives were meas-

ured for 2 levels in In and for 3 levels in In. Energies, spins,

parities and half lives are given for the following levels: In: 597. 03,

3/2"; 828.39, 3/2+, 5.4 ns; 863.95, l / 2 + o r 3 / 2 + , 1.1ns. 117In:

588.59, 3/2"; 0.20 ns; 659.56, 3/2+, 58.7 ns; 749.37, l /2 + or 3/2+ ,

4. 3 ns. Reduced transition probabilities are given for several transi-

tions in both nuclei. The E2 transition rates between the two excited

positive parity states in both nuclei were found to be about 1 00 s. p. u.

indicating a possible deformation of these states. The energy spacing

and transition rates between these states can be well accounted for

within the Nilsson model assuming the states to form a K = -j rotational

band. A deformation ô of about 0. 20 is obtained for both nuclei.

x)Institute of Physics, University of Uppsala and the SwedishResearch Councils'* Laboratory} Studsvik, Nyköping, Sweden

Printed and distributed in January 1967.

LIST OF CONTENTS

1. Introduction

2. Instruments and source production 3

2. 1 Instruments 32. 2 Source preparation 4

3. The decay of l l 5 g Cd to 115In 5

3. 1 The gamma ray spectrum 53. 2 The internal conversion spectrum 53. 3 Multipolarities 53.4 Level scheme 63. 5 Half life measurements 7

4. The decay of 117gCd to 117In 8

4. 1 Gamma ray spectrum 84. 2 The internal conversion measurements 94.3 Multipolarities , , ? 94.4 The level scheme of Cd 10

4. 5 Half life measurements 1 1

5. Discussion 12

Acknowledgement 17

References 18

Table captions 21

Figure captions 22

Tables

Figures

- 3 -

1. INTRODUCTION

It is well known that the ground state and the isomeric state of

the odd mass In isotopes, being one proton off a single closed shell,

are well described as gq /? and p /? states in terms of the spherical

shell model . At higher excitation energies one expects to find fur-

ther (quasi)particle states together with levels arising from a coup-2 3 4)

ling of particle states to collective excitations of the core ' ' .

The positions of the levels in In populated in the decay of

*Cd have been known since the work of Varma and Mandeville .

The half life of the 828 keV level has recently been measured .

However, the spin and parity of the 828 and 864 keV levels are not

clear, in spite of the many recent investigations devoted to these

problems . In particular the attempts to determine the multipo-

larity of the 35 keV transition between these levels have given con-6-8)

flicting results > and the parity assignments of the levels rest

only on the log ft value of the feeding beta transitions.

The decay of Cd to In has been studied by several work-

ers . Different level schemes have been proposed by Sharma

et al. ' and Pandharipande et al. . Mancuso and Arn s , and14)

Baskova et al. ' . Pandharipande et al. have reported a 4. 9 nsechalf life of the 749 keV level

10)

This paper presents half life measurements on two levels in

In and three levels in In using the method of delayed coin*

cidences. The gamma ray spectra from Cd and Cd have been

recorded with a Ge(Li) detector. In order to obtain accurate transi-

tion energies and establish the parities and possibly the spins of the

low energy levels, internal conversion lines of some of the transi-

tions in both In isotopes have been recorded in a double focussing

beta spectrometer.

2. INSTRUMENTS AND SOURCE PRODUCTION

2. 1 Instruments

The gamma ray spectra were measured with a commercial

RCA Ge(Li) detector with a depletion depth of 2 mm. With a hybrid

amplifier ' the resolution at 122 keV was 3. 7 keV FWHM.

- 4 -

The internal conversion lines were recorded with a double focus-

sing beta spectrometer ' , which is in operation at the Studsvik R2

reactor, thereby making possible measurements on relatively short-lived

activities. The geometry of the spectrometer was adjusted to yield a

resolution of 0. 2 per cent FWHM. The detector was a small propor-

tional gas filled counter, which was fitted with a 0. 6 rag/cm thick

window of aluminized mylar.

For the half life measurements we used a Gerholm double lens18 19̂

coincidence spectrometer ' . In all the half life measurements

here reported, only one lens, set to 3 % resolution and transmission,

was used for the detection of a conversion line. The other transition

(beta continuum or gamma ray) was detected in a Naton 136 plastic

scintillator placed 3 mm from the source. We preferred such an ar-

rangement to an electron-electron set up partly because of its higher

efficiency but also because of the convenience of changing between de-

tection of the beta continuum and detection of gamma rays (measured with

an Al absorber). Usually we used a time to pulse height converter working

with overlapping pulses and with a time range of 50 ns but for longer

half lives we used a converter which is very similar to the one de-

scribed by Thieberger ' .

2. 2 Source preparation

The Cd and Cd activities were obtained by the reactions

Cd(n,v) Cd and Cd(n,y) Cd respectively. Enriched ma-

terial ' was used for all sources. The enrichment was 99. 1 % for

the U 4 Cd and 97. 2 % for the ? 1 6Cd material.

The internal conversion sources were made by electro-

plating the Cd on to aluminium backing from a neutral cyanide solu-

tion at low current density. The sources for the half life measure-

ments were prepared by centrifuging a cadmium-alcohol suspension

on to a thin mylar backing.

Purchased from Union Carbide Nuclear Company, Oak Ridge,Tennessee.

We are very grateful to Fil. mag. N.E. Bärring for preparationof these sources.

- 5 -

3. THE DECAY OF 1 ' 5§Cd TO H 5In

3. 1 The gamma ray spectrum

A gamma ray spectrum from a Cd source measured with the

Ge(L,i) detector is shown in Fig. 1. They-^ay intensities obtained

from such a measurement with corfection for detector efficiency are

given in Table 1.

3. 2 The internal conversion spectrum

Sources prepared according to section 2. 2 with thicknesses vary-

ing between 0. 05 and 1 mg/cm were irradiated in the R2 reactor in a14 2

neutron flux density of 2x10 neutrons/cm , sec. for 10 days. The1 1 7

short-lived activities (e. g. from Cdj which also was present in the

source) were allowed to decay for one day before the measurements

were started. The lines of interest in the present investigation weïe

recorded several times with various sources. The results of some of the

recordings are shown in Fig. 2. Energy calibration was made relative to

the K conversion line of the 661. 59 keV transition in Ba ' . The re-

sults of the energy and intensity measurements are given in Table 1.

All gamma and conversion lines were compared with lines belong-

ing to the 336 keV isomeric transition in transient equilibrium with the

mother activity. The relative gamma intensities could therefore be con-

verted to absolute units (in % per beta decay) by correcting for the ratio

between the mother and isomer activities, and the 5. 5 % beta branching22)

from the isomeric level. The conversion electron intensities were

then converted to absolute units using the theoretical value of the con-

version coefficient of the 336 keV isomeric transition (see below).

3. 3 Multipolarlties

Our K/L, ratio of the 336 keV transition is compatible with an M4

transition containing less than 5 % E5. This is in agreement with the

original suggestion by Varma and Mandeville , but in contradiction to7, 23)later work ' ' suggesting a strong E5 component.

The K conversion coefficients of the other transitions were nor-24)

malized to the theoretical value ' for the 336 keV transition, assum-

ing it to be pure M4. The conversion coefficients thus obtained are

given in Table 2. In Fig. 3, the experimental conversion coefficients

are compared with the theoretical values. The 261 keV transition is

clearly Ml with at most 50 % E2.

- 6 -

The K conversion coefficients of the 231, 492 and 527 keV transi-

tions are compatible with predominantly El multipolarity. The mag-

nitude of the conversion coefficient of the 492 keV transition may be ex-

plained by a small M2 admixture. However, as the transition is con-

siderably retarded (see below)* the possibility of an anomalous conver-

sion coefficient due to penetration effects should not be overlooked.

The multipolarity of the 35. 63 keV transition has earlier been

determined as Ml or El ' ' from measurements of the K conver-

sion coefficient using scintillation detectors» We have determined the

multipolarity from the intensity ratios of the L conversion lines. These

were obtained by resolving the 35. 63 keV L group into components as

indicated in Fig. 2. The LT/LTT and L.V,,.. ratios are compatible with

an Ml transition with 3. 0+^* | per cent E2» This result is consistent

with the above result that the 492 and 527 keV transitions have the same

multipolarity (El). In Fig. 2, the dashed line shows the calculated con-

tour of the L group of a pure El transition? clear disagreement with

the experimental points is observed. An M2 admixture would make the

discrepancy still larger.

3.4 Level Scheme

The accurate energy .measurements of the present work lend

further support to the levels deduced in earlier work , Fig. 4*

The spin and parity of the ground state and isomeric state have been

determined as 9/2 and l/2 respectively ' .

The 597 keV level has been assigned as a 5/2 state from an-

gular correlation measurements and from the log ft value and shape

of the beta branch to the level . On the other hand, inelastic

scattering data and recent angular correlation measurements in-

dicate spin 3/2 ' . The Ml multipolarity found for the 261 keV tran-

sition excludes the 5/2 alternative in favour of a 3/2~ assignment.

It has been suggested that the 829 and 865 keV levels have nega-

tive parity on the basis of the log ft values of the feeding transitions ' ' ',

However, the El multipolarity found by us for the 492 and 528 keV

transitions determines the parity of these states as positive. The

log ft values of the feeding beta transitions exclude all spin values

but l/2 and 3/2. The possible M2 component of the 492 keV transi-

tion favours a spin of 3/2 for the 828 keV level, in agreement with

- 7 -

7)angular correlation results ' . The log ft values of the beta transitions

shown in Fig. 4 were deduced from the intensity balance of the levels,

assuming the feeding from the 43 d 11 /2 Cd to be negligible.

3. 5 Half life measurements

L_.M_J:Y. !eZe-i; T l i e m a i n feeding of the 828 keV level is via

a beta transition of 639 keV and a 35. 6 keV transition from the 864 keV

level. The de-excitation takes place by two transitions of 231 and 492

keV respectively. In order to measure the half life of the 828 keV

level the electron lens was focused ön the part of the ß continuum

with an energy of 350 keV and a Nal crystal was set on the low energy

side of the 492 + 528 keV photo peak. A typical delayed coincidence

spectrum from such a measurement is shown in Fig. 5a. The slope

of this decay curve corresponds to a half life of 5. 4± 0. 2 nsec, in good

agreement with the value 5. 5± 0. 2 reported by Tandon and Devare ' .

To make a definite level assignment for this half life we made a

further experiment by exchanging the Nal crystal for a 2 mm

Ge(JLi) detector with 4 keV energy resolution (FWHM) at 5Ï1 keV.22With a Na source the latter combination had a time resolution

(FWHM) of 4 nsec , which should be enough for assigning the 5. 4

nsec half life to the right level. A series of three different types of

experiments were performed. In the first type we registered ß -y

coincidences with the gamma channel carefully set to the 492 keV photo

peak, while in the second case we just moved the gamma channel to

the 528 keV peak. In the third experiment a prompt curve was taken22

with a Na source where one 51 1 keV gamma ray was registered in

an unchanged ß plastic detector and the Ge(Li) channel was set on the

other 51 1 keV gamma transition. Owing to the low efficiency of the

Ge(Li) detector these experiments were run for several days

each and still only a few thousand coincidences were registered.

The statistics, however, were good enough to establish definitely a

half life of about 5 nsec for the 828 level both from the slope and the

centroid shift of the ß - 492 keV decay curve. From the slope of ß -

528 keV decay curve it was concluded that the half life of the 864

keV level was less than 2 nsec.

- 8 -

^L_^l.-SZIi^i; T h e 8 6 4 k e V l e v e l i s f e d by a 59° k e V $~branch and de-excited by three transitions of 35. 6, 267 and 528 keV

respectively. From the electron intensities measured by the dou-

ble focussing beta spectrometer (see above) it was concluded that it

was realistic to make aß - 36 L coincidence experiment in order to

determine the half life of the 864 keV leveL although the 35. 6 keV

line was too weak to be detected above the ß continuum in the lens

spectrometer. We therefore made a series of 0 - electron coincidence

measurements where the ß continuum was detected directly in a plas-

tic scintillator while electron energies around 36 L (32 keV) were fo-

cused into one lens. This conversion electron channel was moved

to four energy settings, two on the 36 L tail one on the expected peak

and one above the peak. A typical decay curve taken with the lens fo^

cused on the 36 L peak and measured for 24 hours is shown in Fig.

5b. The slope to the left is caused by the registration of the ß con-

tinuum in the lens and the 492 keV gamma transition in the plastic

scintillator. A prompt contribution is expected from ß -y coinci-

dence in the decay of Cd (43 days) and the slope to the right is

believed to originate from the ß - 36 JL cascade. The latter state-

ment was confirmed by the fact that the normalized number of de-

layed electron coincidences increased with the energy in the elec-

tron channel but disappeared in the last experiment with the lens fo-

cused above the 36 L peak. In another experiment with the lens fo-

cused on the 36 L peak, the slope on the right side of the decay curve

also disappeared when a thin Al absorber was placed in the electron

channel» which shows that low energy electrons were responsible for

the observed slope. From five delayed coincidence curves we conclude

that the half life of the 864 keV level is 1.1 ±0.1 ns.

4. THE DECAY OF I 1 7 g CdTO ] 1 ?In

4. 1 ' Gamma ray spectrum

117 —

A low energy gamma ray spectrum from a Cd source meas-

ured with the Ge(Li) detector is shown in Fig. 6. The gamma ray in-

tensities obtained from such a spectrum corrected for detector effi-

ciency and absorption in the detector vacuum shield are given in Table

3. The 71.0 keV transition has not been reported before. Special

attention was given to the expected 161 keV transition to the 588 keV

- 9 -

level which has been indicated in the decay schemes of Ref. ' but

has been omitted from the level scheme of Mancuso and Arns . It is

well known that there is a strong 159 keV transition in the daughter

nucleus Sn,but none of the authors mentioned above have tried to

distinguish between the two transitions mentioned. With the Ge(Li)

detector the intensity of the 159 keV peak was measured as a function

of time. From a comparison between calculated curves of gamma in-

tensity versus time for different 161 keV In/l 59 keV Sn values and the

experimentally determined time variation of the J59 keV line it was1Î7

concluded that the intensity of the 161 keV transition in In is less

than I % of the 273 keV transition. The half life of gCd was found

to be (2.5±0. 1) h.

4. 2 The internal conversion measurements

Sources of nominal thicknesses from 0. 2 to 0. 8 mg/cm prepared

as described in section 2 were irradiated in 10 neutrons/cm, sec for

2 hours. The conversion lines were measured several times with vari-

ous sources. Some of the lines recorded are shown in Fig. 7. As the

multipolarity of the 315 keV isomeric transition was found to be

almost pure M4 (see below), it could be used to normalize the conver-

sion coefficients of the other transitions. A special measure-

ment was made in order to compare the intensities of the 273 K

and 315 K lines. The irradiation time was accurately measured and in

order to minimize effects of uncertainties in the decay constants involved,

the two lines were recorded (together with the corresponding gamma

spectrum) close in time to the calculated moment of ideal equilibrium.

The corrections for decay were made assuming the half lives of the

mother activity and the In isomer to be 2. 5 h and I. 9 h respectively.

Energy calibration was made relative to the Ba transition .

The results of the energy and intensity measurements are given in

Table 3.

4. 3 Multipolarities

The K/L ratio of the 315 keV transition is compatible with an M4

transition with less than 7 % E5. The K conversion coefficients of the24)

other transitions were normalized to the theoretical value of the

- io -

315 keV transition assuming it to be pure M4. The resulting conversion

coefficients are given in Table 4> In Fig4 3 the experimental and theo-

retical K conversion coefficients are compared* Multipolarity assign-

ments based on the conversion data are given in the last column of Table

4. The E2 assignment of the 90 keV transition is consistent with the re-

sult that the 344 and 434 keV transitions have the same multipolarity

(El). Also the K/L ratio of the 90 keV transition was consistent with

an E2 transition with less than 20 % Ml.

1 1 74.4 The level scheme of Cd

From the accurate energy measurements and the delayed coinci-

dence experiments (see below) levels were deduced at 558« 59» 659« 59

and 749. 37 keV (see Fig. 4). Of the three recently suggested level

schemes ' ' , our decay scheme agrees best with that of

Pandharipande et al. ' . The delay of the 344 keV transition following

the 90 keV transition definitely rules out the reversed order of these

transitions and the 400 keV level suggested in reference . As was

discussed above, we found only an upper limit for the intensity of the

transition between the 749 and 588 keV levels. The weak 71. 0 keV tran-

sition was fitted on an energy basis between the 659. 56 and 588. 59 keV

levels.

The spins of the ground state and isomeric state have been deter-

mined as 9/2 ' and l/2 respectively* in agreement with the shell

model predictions . From angular correlation measurements the

spin of the 588 keV level has been determined as 3/2 1 0 > 13)4 T^e y j

or E2 multipolarity of the 273 keV transition determines the parity as

negative.

On the basis of the high log ft value of the feeding beta branch, the

749 keV level has been suggested as having negative parity ' while

no assignment has been made for the 660 keV level. The El character

of the 344 and 434 keV transitions, however, implies positive parity

of the 660 and 749 keV levels and a spin of either l/2 or 3/2. As the

90 keV transition is E2, both cannot be l/2. Mancuso and Arns

found the angular correlation of the 90-344 keV cascade to be aniso-

tropic, which then indicates a spin of 3/2 for the 660 keV intermediate

level.

- 11 -

4. 5 Half life measurements

The 588 keV level} The 588 keV level has been shown to be strong-

ly populated by a 1300 keV y transition and by a 1970 keV ß branch

The de-excitation takes place via a 273 keV transition! for which the K

conversion line is partly resolved in the lens spectrometer. For the life

time studies we focused the 273 K line in the spectrometer, while the

J300 keV y or the 1970 keV ß~ branch were detected in a Naton 136 plas-

tic scintillator. A centroid shift measurement was then performed. For

comparison we used a Co source. Without changing any energy settings

we then detected Y rays in the plastic scintillator while an appropriate

part of the feeding ß transition was detected in the spectrometer. From

several such sets of measurements the following results were ob-

tained:

ß" - 273 K T] y2 = 0. 20± 0. 02 ns

1300 keV y - 273 K T jz - 0. 20± 0. 02 ns

where the half life was obtained ffom a momentum analysis» From these

measurements we conclude that the half life of the 588 keV level in In

is 0. 20± 0. 02 ns.

The 660 keV level; The main feeding to the 660 keV level is via

a 90 keV highly converted E2 transition,while the de-excitation takes

place mainly via a 344 keV El transition» For the half life measure-

ment the 90 K conversion line was focused into the electron lens while

the 345 keV gamma transition was detected in a 1"xl" Nal crystal.

The resulting delayed coincidence curve is shown in Fig. 8a. The

prompt part originates from the Compton distribution of higher energy

gamma rays in coincidence with the feeding (3 continuum» while the

flat parts at both ends are accidental coincidences. Four such meas-

urements were made and then analysed by a least squares fit to a func-

tion consisting of a prompt decay, a single exponential decay and a con-'

stant back-ground. From the result obtained we conclude that the half

life of the 660 keV level in ] 1 In is 58. 7± 2. 0 nscc-

-T^e_7!9_kJ:Z!pZel; T h e 7 4 9 k e V level is principally fed by a strong

1815 keV ß branch while the de-excitation Lakes place via two tran-

sitions of 90 and 434 keV respectively. For the half life measurement

the 90 K or L. lines were focused into the lens while the high energy part

of the 1815 keV ß continuum was detected in a Naton 136 plastic sein-

- 12 -

tillator. A typical example of the observed delayed coincidence curve

is shown in Fig. 8b. The half life was obtained from a least squares

fit to the experimental curve. The following results were obtained.

ß~ - 90 K (3 measurements) T i / 2 s 4* 3 6 ± °' ' 8 n s

ß~ - 90 L, (2 measurements) T, ,^ = 4. 25± 0, 25 ns

From our measurements we conclude that the half life of the

749. 3 keV level in In is 4. 3± 0. 2 ns. This is a slightly lower value

than the T, /-, = 4. 9 £ 0. 2 very recently reported by Pandharipande et10) ' /

al. . Their value was based on a delayed coincidence distribution

obtained between the ß~ continuum of 1200± 100 keV and the 434 keV

gamma transition.

5. DISCUSSION

The low energy level schemes of In and In (Fig. 4) are

strikingly similar. Above the well known isomeric state in both nuclei

there is a 3/2 state at almost the same energy and above that two rath-

er close-lying positive parity states with spins l/2 or 3/2, both having

a half life in the nanosecond region. The decay characteristics of the

levels are given in Table 5 and will be discussed below.

One may expect that the In nuclei, being only one proton from

a single closed shell, should be well described by the spherical shell

model. It is well known that this is the case for the ground state and

the isomeric state, the M4 transition rate being close to the single par-

ticle estimate. The systematic behaviour of the distance between these

two levels is well accounted for by taking into account pairing and quad-2,3,4)

rupole residual interactions ' .

From the half life measured for the 3/2 level at 588 keV in In

one finds that the Ml transition to the 1 /Z level is retarded at least a29)

factor of 190 compared to the Weisskopf single particle estimate .

The E2 transition between the same levels is enhanced less than a fac-

tor of 5. The considerable retardation of the Ml transition indicates

that the 3/2 level is not a pure P, /-> particle state but is strongly ad-

mixed, possibly with the p, /., particle + phonon state.

Two 3/2 states can be expected at relatively low excitation en-

ergy: the (p_/,) particle state and the 3/2 member of the doublet

obtained by coupling the p.. /? state to one phonon of quadrupole surface

- 13 -

vibration of the core. F rom a perturbation calculation, Silverberg

predicts the former of these s ta tes , being the lowest in energy, at4)around 1 MeV above the ground state. Kissl inger and Sorensen '

predict a 3/2 state at 1 MeV in the In isotopes, unfortunately no mix-

ing amplitudes are given for that state, but one may conjecture that it

consists predominantly of a mixture of the Pw? part icle state and the

p1 /~+ phonon state.

Excited positive parity states in In isotopes may be supposed to

be formed by coupling the g q / ? part icle to one or several quadrupole

vibration phonons, by coupling the negative parity part icle states to an

octupole vibration, or as man y-par t ic le s ta tes . Forming a 1 /Z or

3/2 state according to the first of these al ternatives requires at least

two phonons. As the phonon energy in this mass region is around 1

MeV, such states are expected to distribute around 2 MeV above the

ground state and it seems most improbable that such states should

occur as low as 600- 800 keV. The second alternative is not very prob-

able either, as the octupole vibrational energy is around 2 MeV in this

mass region. As the pairing energy is well above 1 MeV even the third

alternative seems to be unlikely. Another way of forming these levels

must thus be looked for.

The present investigation has disclosed two remarkable features

of the positive parity doublets in both nuclei. The reduced transition

probability of the E2 transition between these levels is extremely large

for transit ions in spherical nuclei («100 single particle units in both

nuclei). Fur the rmore , the El transit ions to the lower lying negative

parity levels have very large hindrance factors, F\y being around

5*10 for the transit ions in In and 5*10 in In, while all El

transit ions in odd spherical nuclei measured so far have hindrance

factors smal ler than 2 • 10 , cf. Réf. . These large retardations

indicate a radical difference between the positive parity states and the

lower states.

The strong enhancement of the E2 transitions require quadrupole

moments consistent with a constant deformation of these s ta tes . Exam-

ining the Nilsson level energy diagram one finds that for Z » 49 the

l/2 (431) state rapidly falls in energy with increasing positive de-

formation and might thus be energetically favourable as an excited

state in the In isotopes. Such a behavior should show up as a second

minimum in the potential energy curve of the In isotopes some dis-

- 14 -

tance away from the axis of zero deformation. In a recent calculation

S. G. Nilsson and coworkers have demonstrated that such a second1 97

minimum should occur in Au , where the Nilsson levels are expected

to behave in a similar manner as in the In region.

If we accept the idea of deformed states» the two low spin, posi-

tive parity levels could be interpreted as forming a rotational band.

From the experimental B(E2)i value of the 1 /2 -* 3/2. transition, the

intrinsic quadrupole moment Q can be calculated by the following

1 °formula for a K = -j band:

where T, / ? (E2) is the partial E2 gamma transition rate and I and

I are the spins of the ground state and first excited rotational state

respectively. E is given in keV and Q is given in barns. By insert-

ing our experimental values in eq. (l) we obtain the following values

of Q :o

Q (115In; I =î)= 3.78 b; Q ( 1 1 5 I n ; I = | ) = 2. 67 b

Qo(' ] 7In; I e = f ) = 4. 50 b; Q Q ( 1 ] ?In; I = 1) = 3.18b

where the two values for each isotope depends on whether the spin of3 1

the highest excited state is y or y . From the formula

Q = 0 . 8 Z R 27 6 ( l + 0.56 + . . . ) (2)

inserting R = 1.2* A ' fm, the following deformation parameters

are obtained

6(115In; Ie = | ) = 0.25; ô(115In; I = I ) = 0. 18

ô( H 7 In ; I =|-) = 0.29i 6(117In; I = 1) = 0. 22

The energies of the levels in the rotational band are given by

.2 i + 'K(I) =E + | 2EK(I) = E ° + | j L l ( l + 1) + a(-l) 2 ( l + j ) 6 K 1 ] (3)

- 15 -

and thus the enejrgy difference between the y and y components in a] ù

K = y band is given by

For nuclei with a deformation parameter 6 ~ 0. 2 a value for

yy around 20 keV seems to be reasonable» In Fig. 9 the decoupling

parameter "a", as calculated by inserting the experimental values

for E /_ -E / in eq. (4), is given as a function of &-? . The theo-

retical value of "a" calculated within the framework of the Nilsson

model is given by

a = ( - I ) * E ( a 2 Q + 2 a t o ^ V 1 ( 1 + l ) j ( 5 )

Fig. 9 also includes the theoretical values of "a" for two different

deformations. From a comparison with these predictions it is obvious

that the best agreement is obtained if the 3/2 state is below the ?/2

state. This is in agreement with the experimental findingS4

The experimental B(Ml) values within the supposed rotational

bands can also be compared with the Nilsson model« Generally '

B(M1; I.K -

+iL) 2

The quantities g^ and b (g^-g-a) can be calculated from theA O IS. XVA. O IS. XV o T \

following expressions for a K = 1/2 band '

and

' eff-gJ£s

(8)

Here we have introduced different values of the effective g factor for

the longitudinal and the transverse spin polarization* g" c*ff and g eff34) S S

respectively .

- 16 -

Theoretical predictions of the observed B(M1) -J y - y =-) values

can now be obtained from eqs. (6), (7) and (8) as a function of the gyro-

magnetic ratios g , g" eff and g eff. For odd proton transitions gxv S S K.

is fairly constant» with a value of about 0. 4, which was used in the

following calculation. The values of g" eff and g eff are, however,S S

not so certain but are generally found from the comparison with ex-

perimental data to have values about 40 to 80 per cent of the gyro-

magnetic ratio for a free proton (g = 5.585). Fig» 10 shows the results 11 3 l "f~

from a calculation of the B ( M 1 ) valuesfor the -g y [431 ] - y y [431 ]

transition as a function of the déformation of the nucleus. The g" eff

and g eff coefficients were used as parameters) taking values which areS

100, 80, 60 and 40 per cent of the full g value. CHir" experimental

results for U 5In[ 6 a 0. 18; B(Ml) • (8+J • | ) x 1°~3(ff§£-)] and117In[6 s 0 . 22; B(M1) ^ 4. 6 x 1 0" 4 (~ |^ ) ] are also included. Agree-

ment with experiments is obtained for g eff ~ 0» ? g ( In) and-L 1 1 7 S

g eff ~ 0. 8 g ( In) while the result is rather insensitive to theS S

choice of g" eff. This shows that it is possible to describe even thes , ,

Ml transition rates between the excited l/2 and 3/2 levels in both

In and In within the Nils son modeL using reasonable values for

the parameters g„ , g eff and g" eff.xv S S

The above discussion may be summarized as follows: the char-

acters and decay modes of the 829 and 864 keV levels in In and the

660 and 749 keV levels in In are not easily interpreted in terms of

the spherical shell model. Assuming the levels to be (in order) the

3/2 and l/2 members of a K = 1/2 rotational band of a deformed

nucleus with reasonable assumptions of the unknown parameters,

the experimental data are found to be consistent with the Nilsson

model, and imply deformation parameters around Ö* 20 for the lev-

els of both nuclei.

We therefore tentatively suggest these stateä to form a Ksl/2

rotational band, the most plausible Nilsson state being l/2 [43T].

However, no definite conclusions can be drawn until more experimen-

tal data have been collected. It is thus desirable to determine the

spins of the 864 and 749 keV levels in In and In respectively,

and to search for further members of the bands.

ACKNOWLEDGEMENT

We want to express our gratitude to Professor Kai Siegbahn and

Dr. Nils Starfelt for their sponsorship of parts of this work.

We are deeply indebted to Professor S. G. Nilsson for many val-

uable discussions and suggestions.

- 18 -

REFERENCES

1. SIEGBAHN K, (ed.)Alpha-, beta- and gamma-ray spectroscopy. Chap» 10.Goeppert-Mayer M and Jensen J H D.North-Holland Publ. Co., Amsterdam 1965.

2. SILVERBERG L,On the change of the single-particle energies due to a variationof the pair distribution in nuclei of type single closed shell i 1.Arkiv Fysik 2£ (1961) 341.

3. SILVERBERG L,The neutron-proton residual interaction in a quasi-particle re-presentation.Nuclear Physics j60 (1964) 483.

4. KISSLINGER L S and SORENSEN R A*Spherical nuclei with simple residual forces.Rev. Mod. Phys. 3J5 (1963) 853.

5. VARMA J and MANDEVLLUE C E,Level scheme of In' ' 5.Phys. Rev. 97_ (1955) 977.

6. TANDON P N and DEVARE H G, , , , .The lifetime of the 820 keV state of In *Physics Letters J_0 (1964) 113.

7. HANS H S and RAO G N,Decay of Cd115 (2- 3 d).Nuclear Physics 44 (1963) 320.

8. BORNEMEIER D D et al. , n g

Nuclear energy states of In »Phys. Rev. J3_4B (1964) 740.

9. VAN DER KOOI J B, n 5

Metingen met scintillatietellei's aan het verval van Cd,1 1 5 Cd m , 77Ge and 7 7 Ge m . 1964.Diss. Rijksuniversiteit te Utrecht, tr. Groningen.

1 0. PANDHARIPANDE V R et al. ,Low-lying excited states in In ' ' * and In'17,Phys Rev. j_43 (1966) 740.

11. Nuclear data sheets, National Academy of Sciences, Washington,D. C. 1958-65.

12. SHARMA R P, GOPINATHAN K P and AMTE Y S R,Decay of Cd1 ' 7 .Phys. Rev. 134B (1964) 730.

- 19 -

1 3. MANCUSO R V and ARNS R G,The decay of Cd^ ^ a n d Cd^ ^ m and directional correlation of

- 117gamma rays in In ' ' .Nuclear Physics 6̂8 (1965) 504.

14. BASK OVA K A et al. , m

Investigation of the radiation of /tgCdSoviet J. ofNucl. Phys. jî (1966} 288.

15. DISSING E and LARSSON Â,1965. AB Atomenergi, Sweden, (internal Report SSI-1 68. )

1 6. SIEGBAHN K and SVARTHOLM N,Focusing of electrons in two dimensions by an inhomogeneousmagnetic field.Nature 2_57 (1946) 872.

17. BÄCKSTRÖM G et al. ,A magnetic spectrometer for neutron capture experiments.Nucl. Instr. and Methods J_6 (1 962) 199.

18. GERHOLM T R and LINDSKOG J,A magnetic coincidence spectrometer for the measurement ofshort nuclear lifetimes.Arkiv Fysik 2A (1963) 171.

19. BÄCKLIN A and MALMSKOG S G,(To be published in Arkiv Fysik.)

20. THIEBERGER P,Wide range time to pulse height converter.Arkiv Fysik 22, (1962) 127.

21. GRAHAM R L, EWAN G T and GEIGER J S, , ^A one-meter-radius iron-free double-focusing TT V 2 spectrometerfor ß-ray spectroscopy with a precision of 1:10^.Nucl. Instr. and Methods 9_ (1960) 245.

22. LANGER L M, MOFFAT R D and GRAVES G A,The decay of the metastable state in In' ' 5 .Phys. Rev. J36A (1952) 632.

23. ESTULIN I V and MOISEEVA E M,Measurement of the coefficients of internal conversion of "v - raysof Sr87*, In1 1 3 *, In1 ] 5 * and V51* on the electrons of the atoms.Soviet Physics-JETP j _ (1955) 463.

24. SLIV L A and BAND I M,Akad. Nauk. SSSR, Moscow 1956.

25. KING H J et al. ,The nuclear spin of indium-11 5m.Can. J. Phys. 39 (1961) 230.

- 20 -

26. VOGT E W,Determination of d-wawe neutron strength functions from in-elastic neutron scattering to isomeric states.Phys. Letters 1_ (1 963) 61.

27. CAMERON J A and SUMMERS-GILL R G,The nuclear spin of indium-11 7m.Can. J. Phys. 40 (1962) 1041.

28. CAMERON J A and SUMMERS-GILL R G,The spin of indium-1 17.Can. J. Phys. _4[_(1963) 823.

29. WAPSTRA A H, NIJGH G J and VAN LIESHOUT R,Nuclear spectroscopy tables.North-Holland Publ. Co., Amsterdam 1959.

30. PERDRISAT C F,Survey of some systematic properties of the nuclear El transi-tion probability.Rev. Mod. Phys. 3^ (19 66) 41.

31. NILSSON S G,Report at a conference in Lysekil, Sweden (Aug. 1966) andprivate communication.

32. SIEGBAHN K, (ed.)Alpha-, beta- and gamma-ray spectroscopy.Nathan O and Nils s on S G.North-Holland Publ. Co., Amsterdam 1959.

33. NILSSON S G,Binding states of individual nucléons in strongly deformed nuclei.Mat.-Fys. Medd. Dan. Vid. Selsk. 22(1955) 16.

34. BOCHNACKI Z and OGAZA S,Transverse spin polarization in odd-mass deformed nuclei.Nuclear Physics J33_ (1966) 619.

35. O'CONNELL R F and CARROLL C O,Internal conversion coefficients: General formulation for allshells and application to low-energy transitions.Phys. Rev. 138(1965) 1042.

- 21 -

TABLE CAPTIONS

Table 1 Energies and intensities of conversion electrons and gamma

rays from the decay of Cd to In. The intensities are

relative but have been converted to absolute units according

to the text. The errors given are estimated standard devia-

tions with liberal allowance for possible systematic error's.

24)Table 2 Experimental and theoretical ' conversion coefficients of

• 1 1 5T

transitions in In.

Table 3 Energies and intensities of conversion electrons and gamma

rays from the decay of Cd to In. Regarding the errors»

see caption of Table 1.

24)Table 4 Experimental and theoretical ' conversion coefficients of

• 1 1 7 Ttransitions in In.

Table 5 Half lives, reduced transition probabilities and hindrance

factors of transitions in In and In.

- 22 -

FIGURE CAPTIONS

Fig. I The gamma ray spectrum of the decay of feCd to In

recorded with a Ge(Li) detector.

Fig. 2 Internal conversion lines in In. The abscissa is propor-

tional to the momentum. The points of each line have been

corrected for decay, but the lines can not generally be di-

rectly compared to each other» as the lines were recorded

at different times, and different sources were used. The

dashed contour at the 35» 6 keV L. group indicates the shape

for multipolarity El .

Fig. 3 Experimental and theoretical K conversion coefficients of

transitions in In and In (the latter indicated with a *).

Fig. 4 Low energy levels in In and In populated in the (3 -decay

of l/2 ^Cd and ^Cd respectively. For the levels are

given the spin, parity, energy in keV and half life as deter-

mined in the present work. The small numbers following the

energy values denote the error of the last digit. The inten-

sities and log ft values of the beta transitions to the In

levels and the 659 and 749 keV levels in In were deduced

from the intensity balance of the levels, assuming the feeding

from the 1 l/2 isomeric Cd levels to be negligible. The same1 1 7

quantities of the 315 and 588 keV levels in In are those of

Ref. . For the transitions are given the energy in keV and

the multipolarity. The widths of the arrows are approximately

proportional to the intensities, the unfilled part denoting the

internal conversion intensity.

Fig. 5a Delayed coincidence curve taken between the ß continuum

and a mixture of the 492 and 528 keV gamma transitions. The

slope of this decay curve corresponds to a half life of 5. 4 ±

± 0. 2 nsec, which could in a separate experiment be assigned

to the 828. 4 keV level in 115In.

- 23 -

Fig. 5b Delayed coincidence curve taken between the ß continuum

and 32 keV conversion elections (35. 6 L). The slope to the

left originates from Y - ß coincidences from the 828 keV

level, the prompt contribution mainly from Y - ß coincidences

in the decay of Cd while the slope to the right comes

from the ß" - 35. 6 L cascade and gives a half life of 1. 1 ±

± 0. 1 nsec for the 864. 0 keV level in In.

Fig. 6 Low energy part of the decay of Cd to In recorded with

a Ge(Li) detector. The 159 keV transition mainly takes place. 117Cm Sn.

Fig. 7 Internal conversion lines in In* The points of the lines

have been corrected for radioactive decay, but the lines are

not generally directly comparable to each other.

Fig. 8a Delayed coincidence curve taken between the 90 K conversion

electrons and the 345 keV gamma transition. From the slope

the half life of tl

58. 7±2. 0 nsec.

] ? 7the half life of the 660 keV level in In was determined to

Fig. 8b Delayed coincidence curve taken between the ß continuum

and the 90 K conversion electrons» From the slope the half

life of the 749 keV level in In was determined to 4. 3 ± 0. 2

nsec.

Fig. 9 The decoupling factor a as a function of the inertial param-

eter-5-7 for the experimental values of the level distancesj p

inserted in eq. (4). For a value of ^-=- around 20 keV (in-117

dicated by the large shaded area) the value of _a for In

agrees well with the value of a computed from eq. (5) with

a deformation parameter between 0. 15 and 0. 20 (the small

shaded area). The agreement for In is not so good, but

can not be considered as unreasonable in view of the uncer-

tainty of the parameters.

Fig. 10 The value of [B(Ml)}1/2 for the 1 ~ 1.431 ] - | i [43 1 ] tran-

sition calculated within the Nilsson model (formula 6) is

given as a function of the deformation parameter ô, using

- 24 -

the effective values of the gyromagnetic factors in eqs. (7)

and (8) (g" eff and g eff) as free parameters. gR was chosen

to 0. 4. Our experimental results for1 1 5 I n : 6 « 0.18, £ B ( M 1 ) }

] / Z « 0. 089+°' °J \ and

1 1 ?In: 6 a 0. 22, { B ( M I ) } 1 ' 2 ^± 2. 2 X 10~2 are compared

with the theoretical predictions. Agreement with experiment

is obtained for g eff ~ 0.7 g ( In) and g eff ~ 0. 8 g, j - ö s &s v ' & s & s

( In) while the result is rather insensitive to the value of

g' e f £ -

Table 1

Electronenergy

keV

31.39

31. 69

31.90

34.96

35. 64

203.53

232.86

308.29

332.21

335.64

464.20

492. 76

Electronshell

L IL I ILIIIM

N+O

K

K

K

L

M+N

K

K

Transi-tion en-ergy-

keV

35. 63

231.47

260. 80

267

336. 23

492. 14

527.70

Error

eV

50

100

60

2000

50

60

60

Electronintensity

%

0.37

0. 19

0;23

0.21

0. 037

0. 012

0. 069

39.3

8 , 7

1.6

0.025

0.058

Relativeerïor

%

10

25

15

30

50

30

10

5

10

10

10

Gammaintensity

%

0.36a>

0.76

2.05

0.06

44.9

9.45

30.3

Relativeerror

%

12

10

/ +50\ -25

5

5

a) Calculated from the theoretical value of a

Table 2

Transi-tion en-ergykeV

35. 63

231.47

260. 80

336.23

492. 14

527. 70

Totalconversioncoefficient

x 102

1500±500a)

2. 0±0. 7

4. 2±0.6

lll±10

0. 32±0. 05

0. 23±0. 04

Experimen-tal value of

x 102

î. 6±0.5

3.5±O. 5

(87)

0.28±0. 04

0. 20±0. 03

Theoretical values of oi xl 0xS.

E l

1.45

K05

0.53

0. 197

0.17

M l

4.45

3.3

1. 68

0.64

0.57

E 2

6.8

4.6

U97

0.62

0.5?

M2

23

15.5

6.8

2,2

1.8

M4

87

E 5

66

Multipole Assignment

Ml + (3. 0+°* l) % E2 fromi . l/, ll

El +< 3 % M2 from avis.

Mî +< 50 % E2 from a„K.

M4+< 5 % E5 from K/L

El + (4±2>% M2 from aK

El +< 4 % M2 from o-„is.

a) o> obtained from réf. [35]

Table 3

Electronenergy

keV

61.86

85.9689.77

129. 30a)154. 07a)157. 80a)

133.9245.38269.20

287.33

311.33314.56

316.35

406. 18

ElectronShell

K

L

M+N

KL

M+N

K

K

L

K

L

M+N

K

K

Transi-tion en-ergy

keV

71. 089.80

158.50

160.8

273.32

315.27

344. 29434. 12

Error

eV

500

50

100

60

60

60

200

Relativeelectronintensity

700

230

100

(200)

(33)

on< 2

100

13

1840b>

390b>

nob>10, 0

3

Errorc)

%

15

20

25

10

20

8

10

15

70

Relativegammaintensity

1.1

15

< 1

100

55b)

59

30

Errorc)

%

30

13

5

5

7

a) Transition in Sn

b) At ideal equilibriumc) A 10 % er ror corresponding to the uncertainty in the comparison

between the intensities of the isomeric transition and the other tran-sitions has not been included in the e r rors given4

Table 4

Transi-tion en-ergy

keV

89. 80

273.32

315. 27

344. 29

434. 2

Totalconversioncoefficient

x 102

250±90

4. l±0. 7

149

0.7±0. 2

0. 35±0.Z5

Experimen-tal value of

aK ?x 10*

160±60

3. 5±0. 6

(117)

0.59±0. 12

0.3±0.2

Theoretical values of otis.

E l

20.5

0.93

0.53

0.50

0.27

Ml

60

2 . 8

1.98

T. 57

0.89

E 2

170

3 .9

2.42

1.75

0.90

M2

610

13

8 . 3

6 . 3

3. >5

xlO2

M4

m

E 5

89

Multipole Assignment

E2 + < 20 % Ml from c* and K/L

E2 or Ml from <x

M4 + < 7 % E5 from K/L

El +< 3. 5 % from a-

E.^ + < T % M2. from a__JK.

Table 5

Nucleus(level inkeV)

115,In

(828.4)

11 5T

In(863.9)

117-In

(588. 3)

11 7T

In(659. 6)

M7-In

(749. 3)

T1 /2(exp)of levelin sec.

5.4xlO"9

±0. 2

1. ixlO"9

±0. 1

2.0xl0"TQ

±0. 2

58. 7x1 0~9

±2. 0

4.3xlO"9

±0.2

Transi-tion en-ergy in

keV

492. 1

231. 5

527.7

267. 035. 6

273.3

344.3

71.0

434. 1

160. 889.8

Initial state

(1/2,3/2) +

(1/2,3/2) +

3/2"

0/2,3/2) +

0/2,3/2) +

Final state

1/2-

3/2"

1/2"

3/2"(1/2,3/2) +

1/2-

T/2-

3/2"

1/2-

3 / 2 ~ +(1/2,3/2)+

Multi-polari-

ty

ElM2EÎM2

E lM2~E lM lE2

MlE2

ElM2Et

ElM2EÏMlE2

RelativeNY

9.50.380.76

<0. 023

30.3<1.2

0.060.36o. o? \

<ÎOO

<too

59<2.1

30<2. }<1.0<315

RelativeNe

| 0. 027

| 0.012

| 0. 061

I 5. 6

} 0.350.5

1 0.09<0. 05

}3.

T, /2(exp)in

sec.

6. 1x7 0"9

1.5xlO-7

7. 6x10-8

>2. 5x1 0-6

1.3xlO"9

>3. 3x>O~ö

6.7xlO-7

1. Txl Or7

3.6xlO~6

ä2.1xK>~>0

S2. 1x1 0 ^ °

6. lxl 0 ' 8

>1.7xlO-6

3.3x10-6

1.2xï(>"8

>>. 7x?O-7

>3. 6x10~7

>1.2x>0-7

2.4x>0-8

Fw

6. ixJO7

3.37. 4x107

>1.2

7.4xlO5

>1. 04. 3xlO7

2201.2x10-2

s 190>0. 20

8. 8x1O6

>6. 34. 2x1 O6

3.5xlO6

>2. 0>5. 3xlO6

>3.9xlO3

8.6x10-3

CO

o

10 b -•

10J £

10 E

-

-

•• •_ X

5

~ 4

ii m

i •

r

2 3 1 . 51 •4*»,

* " " V " ' > H i

V*" •

'•

'

260.8I 2671

0

-

'*••••.•

• * • • '•%.

1 336,2f

•

•

*

1

I

1

492.1I

;;

I

527.7

I* t

*

*

—

-

E

I I

I I

—-

—i

— ;

|

200 300 400 500 KeV

Fig. 1

oo

uiQ.

O

8000

7000

6000

5000

4000

3000 4400 4500 4600 4700 4600 4900VOLTAGE DIVIDER SETTING

231KoCD

O

-110000

-105000

-100000

12600 700 800

261K

•270000

13600 700 800 9&C

01

8(?)

•noooo

492 K

105000 j

527 K

ftoooo

•100000 \ 1 hUOOOO

21100 200 '3O0|220O0100 2Q0 300 400

VOLTAGE DIVIDER SETTINGS

Fig. Z.

* 1000

SLJZUJ

500

100

Ez"--^!1 M2-^E«-^M; Es 117,n1,5|nH

ICF*COWVERSfOM COEFFtDENTS

Fig. 3.

log ft31% 6.5

1.3% 8.3

58% 7.2

CMUJ•

COCDin

863.959

IUJr-

COCM

\ 3/2- 1CM

CM

ÖCOCM

ID

CM

828.39 8 1.1 ns5.4 ns

» - CMLU uj

log ft

V/2,3/2O CO «P

O> Ooo CD

597.03 8

<4.5%>8.0 \ 3/2 •

9% 7.7 \ 3/2-

UJO

r<CMin

( 1/2-

9/2 +

336.

23

i \ I 336.23 5\

0

4.5 b 8% 7.8 Y j / 2 -

9/2*11749

659.56 9 EQ.,58.7 ns

588 59 90 20ns

r 9

Irr

Fig. 4.

Coincidences Coincidences

10-

10?

10

864.0 z828. L -

I I

103 =-

102 -

10 -

AC 50 60 nsec. 30 nsec

Fig. 5 a and b.

O) -

cZJoo

106 -

105 _

10A r

10 KeV

Fig. 6.

inou>tr 50000a.

40000

30000 -

20000

10000

315 K

8000

7000

6000

5000

4000

3000

1

-

-

-

y

»*£—- i

315

M j M j

1 I N,

A >rNl

A\— —*"~̂

i344 K

1

—

-

-

1 ~

16500 16600

315M 344 K

_L _L JL _L15500 15600 15700 16400 16500 16600 16700 16800

VOLTAGE OIVIDER SETTING

'60S

10

COU

•1500

•1000

s500,«v

t^L.

6400

I)1./

1

j

/

90K

\ . .

500 600 700

100S

J.N

COU

1500

•1000 •

^r

500

7700

901

i\Il'

/

/

800

90M+N

i A.

900 8000 100' • •

r30

S

t/it—

COU

•2500

2000

1500

I1

"./•

JJ

Uioo 200

• 272K

I

i.300

'20

0S

t/>t -

cou

•9000

8000

7OOO"-* *• */ \J\J\r •

•

19200 300

434K

A '__——̂—• •490 590

VOLTAGE DIVIDER SETTINGS

Fig. 7.

Coincidences

103 __

10" =

un

- •

- • x->

— fr

- -

-

—

^» •

•» • *

• t • •

— «*s *

I f

I'

v

I

I

117Cd

<

f

1 1

(~2.8h)

\\

w *

1 1 1

- ^ T T - 659.• 588.I* 315.

n-u

Î T 7 l r>•- *

9>m • *

E t I

—

cn

en

•

3 1-

0* —• M

Coincidences

= 103 _

-MO -

200 400 600 800 nsec. 30 nsec.

Fig. 8 a and b.

Fig. 9.

0.3

0.2

0.7

g"eff 1OÛ% 80% 60 % 40°/

.3 VB(MI) '

Fig. ÎO.

LIST OF PUBLISHED AE-REPORTS

1-180. (See the back cover earlier reports.)181. Studies of the fission integrals of U235 and Pu239 with cadmium and

boron filters. By E. Hellstrand. 1965. 32 p. Sw. cr. 8 : - .182. The handling of liquid waste at the research station of Studsvik, Sweden.

By S. Lindhe and P. Linder. 196S. 18 p. Sw. cr. 8 : - .183. Mechanical and instrumental experiences from the erection, commissioning

and operation of a small pilot plant for development work on aqueousreprocessing of nuclear fuels. By K. JSnsson. 1965. 21 p. Sw cr. 8:- .

184. Energy dependent removal cross-sections in fast neutron shielding theory.By H. Gronroos. 1965. 75 p. Sw. cr. 8:—.

185. A new method for predicting the penetration and slowing-down of neutronsin reactor shields. By L. Hjarne and M. Leimdorfer. 1965. 21 p. Sw. cr. 8 : - .

186. An electron microscope study of the thermal neutron induced loss in hightemperature tensile ductility of Nb stabilized austenitic steels. By R. B.Roy. 1965. 15 p. Sw. cr. 8 : - .

187. The non-destructive determination of burn-up means of the Pr-144 2.18MeV gamma activity. By R. S. Forsyth and W. H. Blackadder. 1965. 22 p.Sw. cr. 8 : - .

188. Trace elements in human myocardial infarction determined by neutronactivation analysis. By P. O. Wester. 1965. 34 p. Sw. cr. 8 : - .

189. An electromagnet for precession of the polarization of fast-neutrons. ByO. Aspelund, i. Bjorkman and G. Trumpy. 1965. 28 p. Sw. cr. 8:- .

190. On the use of importance sampling in particle transport problems. ByB. Eriksson. 1965. 27 p. Sw. cr. 8:- .

191. Trace elements in the conductive tissue of beef heart determined byneutron activation analysis. By P. O. Wester. 1965. 19 p. Sw. cr. 8 : - .

192. Radiolysis of aqueous benzene solutions in the presence of inorganicoxides. By H. Christensen. 12 p. 1965. Sw. cr. 8 : - .

193. Radiolysis of aqueous benzene solutions at higher temperatures. By H.Christensen. 1965. 14 p. Sw. cr. 8 : - .

194. Theoretical work for the fast zero-power reactor FR-0. By H. Haggblom.1965. 46 p. Sw. cr. 8:- .

195. Experimental studies on assemblies 1 and 2 of the fast reactor FRO.Part 1. By T. L. Andersson, E. Hellstrand, S-O. Londen and L. I. Tiren.1965. 45 p. Sw. cr. 8:- .

196. Measured and predicted variations in fast neutron spectrum when pene-trating laminated Fe-DiO. By E. Aalto, R. Sandlin and R. Fraki. 1965. 20 p.Sw. cr. 8 : - .

197. Measured and predicted variations in fast neutron spectrum in massiveshields of water and concrete. By E. Aalto, R. Fraki and R. Sandlin. 1965.27 p. Sw. cr. 8:—.

198. Measured and predicted neutron fluxes in, and leakage through, a con-figuration of perforated Fe plates in D J O . By E. Aalto. 1965. 23 p. Sw.cr. 8:—.

199. Mixed convection heat transfer on the outside of a vertical cylinder. ByA. Bhattacharyya. 1965. 42 p. Sw. cr. 8 : - .

200. An experimental study of natural circulation in a loop with parallel flowtest sections. By R. P. Mathisen and O. Eklind. 1965. 47 p. Sw. cr. 8 : - .

201. Heat transfer analogies. By A. Bhattacharyya. 1965. 55 p. Sw. cr. 8 : - .202. A study of the "384" KeV complex gamma emission from plutonium-239.

By R. S. Forsyth and N. Ronqvist. 1965. 14 p. Sw. cr. 8:—.203. A scintillometer assembly for geological survey. By E. Dissing and O.

Landstrom. 1965. 16 p. Sw. cr. 8:- .204. Neutron-activation analysis of natural water applied to hydrogeology. By

O. Landstrom and C. G. Wenner. 1965. 28 p. Sw. cr. 8 : - .205. Systematics of absolute gamma ray transition probabilities in deformed

odd-A nuclei. By S. G. Malmskog. 1965. 60 p. Sw. cr. 8:- .206. Radiation induced removal of stacking faults in quenched aluminium. By

U. Bergenlid. 1965. 11 p. Sw. cr. 8 : - .207. Experimental studies on assemblies 1 and 2 of the fast reactor FRO. Part 2.

By E. Hellstrand, T. Andersson, B. Brunfelter, J. Kockum, S-O. Londenand L. I. Tiren. 1965. 50 p. Sw. cr. 8 : - .

208. Measurement of the neutron slowing-down time distribution at 1.46 eVand its space dependence in water. By E. Moller. 1965. 29 p. Sw. cr. 8 : - .

209. Incompressible steady flow with tensor conductivity leaving a transversemagnetic field. By E. A. Witalis. 1965. 17 p. Sw. cr. 8 : - .

210. Methods for the determination of currents and fields in steady two-dimensional MHD flow with tensor conductivity. By E. A. Witalis. 1965.13 p. Sw. cr. 8 : - .

211. Report on the personnel dosimetry at AB Atomenergi during 1964. ByK. A. Edvardsson. 1966. 15 p. Sw. cr. 8 : - .

212. Central reactivity measurements on assemblies 1 and 3 of the fast reactorFRO. By S-O. Londen. 1966. 58 p. Sw. cr. 8 : - .

213. Low temperature irradiation applied to neutron activation analysis ofmercury in human whole blood. By D. Brune. 1966. 7 p. Sw. cr. 8:—.

214. Characteristics of linear MHD generators with one or a tew loads. ByE. A. Witalis. 1966. 16 p. Sw. cr. 8:- .

215. An automated anion-exchange method for the selective sorption of fivegroups of trace elements in neutron-irradiated biological material. ByK. Samsahl. 1966. 14 p. Sw. cr. 8 : - .

216. Measurement of the time dependence of neutron slowing-down and therma-lization in heavy water. By E. Moller. 1966. 34 p. Sw. cr. 8:- .

217. Electrodeposition of actinide and lanthanide elements. By N-E. Barring.1966. 21 p. Sw. cr. 8:- .

218. Measurement of the electrical conductivity of He1 plasma induced byneutron irradiation. By J. Braun and K. Nygaard. 1966. 37 p. Sw. cr. 8 : - .

219. Phytoplankton from Lake Magelungen, Central Sweden 1960-1963. By T.Willen. 1966. 44 p. Sw. cr. 8 : - .

220. Measured and predicted neutron flux distributions in a material surround-ing av cylindrical duct. By J. Nilsson and R. Sandlin. 1966. 37 p. Sw.cr. 8 : - .

221. Swedish work on brittle-fracture problems in nuclear reactor pressurevessels. By M. Grounes. 1966. 34 p. Sw. cr. 8 : - .

222. Total cross-sections of U, UOi and ThO: for thermal and subthermalneutrons. By S. F. Beshai. 1966. 14 p. Sw. cr. 8 : - .

223. Neutron scattering in hydrogenous moderators, studied by the time de-pendent reaction rate method. By L. G. Larsson, E, Moller and S. N.Purohit. 1966. 26 p. Sw. cr. 8:- .

224. Calcium and strontium in Swedish waters and fish, and accumulation ofstrontium-90. By P-O. Agnedal. 1966. 34 p. Sw. cr. 8 : - .

225. The radioactive waste management at Studsvik. By R. Hedlund and A.Lindskog. 1966. 14 p. Sw. cr. 8 : - .

226. Theoretical time dependent thermal neutron spectra and reaction ratesin H.O and DiO. S. N. Purohit. 1966. 62 p. Sw. cr. 8 : - .

227. Integral transport theory in one-dimensional geometries. By I. Carlvik.1966. 65 p. Sw. cr. 8:- .

228. Integral parameters of the generalized frequency spectra of moderators.By S. N. Purohit. 1966. 27 p. Sw. cr. 8 : - .

229. Reaction rate distributions and ratios in FRO assemblies 1 , 2 and 3. ByT. L. Andersson. 1966. 50 p. Sw. cr. 8 : - .

230. Different activation techniques for the study of epithermal spectra, app-lied to heavy water lattices of varying fuel-to-moderator ratio. By E. K.Sokolowski. 1966. 34 p. Sw. cr. 8 : - .

231. Calibration of the failed-fuel-element detection systems in the Agestareactor. By O. Strindehag. 1966. 52 p. Sw. cr. 8 : - .

232. Progress report 1965. Nuclear chemistry. Ed. by G. Carleson. 1966. 26 p.Sw. cr. 8:- .

233. A Summary Report on Assembly 3 of FRO. By T. L. Andersson, B. Brun-felter, P. F. Cecchi, E. Hellstrand, J. Kockum, S-O. Londen and L. I.Tiren. 1966. 34 p. Sw. cr. 8 : - .

234. Recipient capacity of Tvaren, a Baltic Bay. By P.-O. Agnedal and S. O. W.Bergstrdm. 21 p. Sw. cr. 8:- .

235. Optimal linear filters for pulse height measurements in the presence ofnotise. By K. Nygaard. 16 p. Sw. cr. 8 : - .

236. DETEC, a subprogram for simulation of the fast-neutron detection pro-cess in a hydro-carbonous plastic scintillator. By B. Gustafsson and O.Aspelund. 1966. 26 p. Sw. cr. 8:- .

237. Microanalys of fluorine contamination and its depth distribution in zircaloyby the use of a charged particle nuclear reaction. By E. Moller and N.Starfelt. 1966. 15 p. Sw. cr. 8 : - .

238. Void measurements in the regions of sub-cooled and low-quality boiling.P. 1. By S. Z. Rouhani. 1966. 47 p. Sw. cr. 8:- .

239. Void measurements in the regions of sub-cooled and low-quality boiling.P. 2. By S. Z. Rouhani. 1966. 60 p. Sw. cr. 8:- .

240. Possible odd parity in "°Xe. By L. Broman and S. G. Malmskog. 1966.10 p. Sw. cr. 8:—.

241. Burn-up determination by high resolution gamma spectrometry: spectrafrom slightly-irradiated uranium and plutonium between 400-830 keV. ByR. S. Forsyth and N. Ronqvist. 1966. 22 p. Sw. cr. 8 : - .

242. Half life measurements in 1 "Gd. By S. G. Malmskog. 1966. 10 p. Sw.cr. 8:- .

243. On shear stress distributions for flow in smooth or partially rough annuli.By B. Kjellstrom and S. Hedberg. 1966. 66 p. Sw. cr. 8 : - .

244. Physics experiments at the Agesta power station. By G. Apelqvist, P.-A.Bliselius, P. E. Blomberg, E. Jonsson and F. Akerhielm. 1966. 30 p. Sw.cr. 8:- .

245. Intel-crystalline stress corrosion cracking of inconel 600 inspection tubes inthe Agesta reactor. By B. Gronwall, L. Ljungberg, W. Hiibner and W.Stuart. 1966. 26 p. Sw. cr. 8 : - .

246. Operating experience at the Agesta nuclear power station. By S. Sand-strom. 1966. 113 p. Sw. cr. 8:- .

247. Neutron-activation analysis of biological material with high radiation levels.By K. Samsahl. 1966. 15 p. Sw. cr. 8:- .

248. One-group perturbation theory applied to measurements with void. By R.Persson. 1966. 19 p. Sw. cr. 8 : - .

249. Optimal linear filters. 2. Pulse time measurements in the presence ofnoise. By K. Nygaard. 1966. 9 p. Sw. cr. 8:—.

250. The interaction between control rods as estimated by second-order one-group perturbation theory. By R. Persson. 1966. 42 p. Sw. cr. 8 : - .

251. Absolute transition probabilities from the 453.1 keV level in 183W. By S. G.Malmskog. 1966. 12 p. Sw. cr. 8:- .

252. Nomogram for determining shield thickness for point and line sources ofgamma rays. By C. JSnemalm and K. Malen. 1966. 33 p. Sw. cr. 8 : - .

253. Report on the personnel dosimetry at AB Atomenergi during 1965. By K. A.Edwardsson. 1966. 13 p. Sw. cr. 8 : - .

254. Buckling measurements up to 250°C on lattices of Agesta clusters and onDiO alone in the pressurized exponential assembly TZ. By R. Persson,A. J. W. Andersson and C.-E. Wikdahl. 1966. 56 p. Sw. cr. 8:- .

255. Decontamination experiments on intact pig skin contaminated with beta-gamma-emitting nuclides. By K. A. Edwardsson, S. Hagsg&rd and A. Swens-son. 1966. 35 p. Sw. cr. 8:- .

256. Perturbation method of analysis applied to substitution measurements ofbuckling. By R. Persson. 1966. 57 p. Sw. cr. 8 : - .

257. The Dancoff correction in square and hexagonal lattices. By I. Carlvik. 1966.35 p. Sw. cr. 8 : - .

258. Hall effect influence on a highly conducting fluid. By E. A. Witalis. 1966.13 p. Sw. cr. 8:- .

259. Analysis of the quasi-elastic scattering of neutrons in hydrogenous liquids.By S. N. Purohit. 1966. 26 p. Sw. cr. 8:- .

260. High temperature tensile properties of unit-radiated and neutron irradiated20Cr-35Ni austenitic steel. By R B Roy and B Solly. 1966. 25 p. Sw.cr. 8:- .

261. On the attenuation of neutrons and photons in a duct filled with a helicalplug. By E. Aalto and A. Krell. 1966. 24 p. Sw. cr. 8 : - .

262. Design and analysis of the power control system of the fast zero energyreactor FR-O. By N. J. H. Schuch. 1966. 70 p. Sw. cr. 8:- .

263. Possible deformed states in "5 ln and ' " In . By A. Backlin, B. Fogelberg andS. G. Malmskog. 1967. 39 p. Sw. cr. 10:-.

Forteckning over publicerade AES-rapporter

1. Analys medelst gamma-spektrometri. Av D. Brune. 1961. 10 s. Kr 6:—.2. BesiraJningsforandringar och neutronatmosfar i reaktortrycktankar — n£gra

synpunkter. Av M. Grounes. 1962. 33 s. Kr 6:—.3. Studium av strackgransen i miukt st i l . Av G. Dstberg och R. Attermo.

1963. 17 s. Kr 6:- .4. Teknisk upphandling inom reaktoromradet. Av Erik Jonson. 1963. 64 s.

Kr 8: - .5. Agesta Kraftvarmeverk. Sammansta1 lining av tekniska data, beskrivningar

m. m. for reaktordelen. Av B. Lilliehook. 1964. 336 s. Kr 15:-.6. Atomdagen 1965. Sammanstallning av foredrag och diskussioner. Av S.

SandstrSm. 1966. 321 s. Kr 15:-.Additional copies available at the library of AB Atomenergi, Studsvik, Ny-koping, Sweden. Micronegatives of the reports are obtainable through Film-produkter, Gamla landsvagen 4, Ektorp, Sweden.

EOS-tryckerierna, Stockholm 1967