(SANITIZED)UNCLASSIFIED SOVIET PAPERS ON LOW-ENERGY NUCLEAR REACTIONS(SANITIZED)

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80T00246A044100140001-6
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 52
• Document Creation Date: December 22, 2016
• Document Release Date: June 1, 2010
• Sequence Number: 1
• Content Type: REPORT

Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
FOR OFFICIAL USE. ONL '
page
Reactions with light nuclei . . . . . . . . . . . 1
Polarization effects at nuClear reactions .
Neutron reactions 14
Deuteron reations . . ? ? ? ? .
Coulomb excitation of nuclei and the proton
reactions 25
Photonuclear reactions 31
Nuclear reactions induced by heavy ions .40
Nuclear models 44
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
t6~w~. v-
REACTIONS WITH LIGHT NUCLEI
G. F. BOGDANOV, N.A. VLASOV, S. P. KALININ,
B. V. RYBAKOV, L. N. SAHOYLOV, V. A. SIDOROV
Experimental data concerning the excited states of He4 are considered.The
T(p,n)He3 excitation function and neutron angular distributions have been measured
from the threshold up to 12 Mev. The excitation function and the energy dependence
of the angular-distributions have a resonant character due to the 22 Mev excited
state of He4. Neutron spectra at several angles and a proton spectrum at 30? of the
(T+d) and (He3+d) reactions have been measured by the time-of-flight method at
18 Mev deuteron energy. The comparison of the T+d and He3+d spectra and cross sec-
tions confirms the existence of the excited state in He4 and points to the absence
of similar states in Li4 and H4. Due to this fact the isotopic'spin of the He4 exci-
ted'state is believed to be T=O.
MEASUREMENT OF THE ENERGY DEPENDENCE OF THE REACTIONS
He3(n,p); Li6(n,a); B10(n,a) and N14(n,p)
A.A.BERGMAN, A.I.ISAKOV, YU.P.POPOV,
F. L.SHAPIRO
A lead slowing down time neutron spectrometer was used to compare the energy
dependence of the cross sections of the (n,a) and (n,p) reactions for energies up
to 25 kev. The results of the measurements are compared with predictions that can be
made on basis of data pertaining to, the nuclear levels of Liz, B11 and N15 which are
the nearest to the neutron binding energy. It is concluded that for E < 25 kev the
-1-
FOR OfflC AL USE ONLY
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01 : CIA-RDP80T00246AO44100140001-6
q
FOR OFFICIAL USE ONLY,
cross section for the B10(n,a) reaction does not depart. from the 1/v law by more than
5 - 10%. For the Li6(n,a) cross section the departure from 1/v is even less. The ratio
for the N14(n,p) cross section to that for Lie(n,a) is constant to within 3% up to
-6 kev; at higher energies it begins to increase. The increase is of 'the order of 10%
at E-25 kev. The cross section ratios He3(n,p)/Li6(n,a) and He3(n,p)/B10(n,(.) decrease
with increasing energy, the magnitude of the dip exceeding 15% at E-25 kev. This sig-
nifies that the-He3(n,p) cross section decreases with, the energy considerably more
rapidly than the 1/v law predicts. The energy dependence of the He3(n,p) reaction up
to energies -1 Mev can be satisfactorily described if an excited level with an angular
momentum 0; is assumed to exist in the He4 nucleus.
Analysis of variation of the B10(n,a) cross section indicates the existence of a
level in B11 which possesses an angular momentum 5/2+ or 7/2k, an energy Ea-250 kev
and widths I'a-100 kev, Pn 200 kev.
Li7(p,t) Lib REACTION
The triton spectra of Li(p,t) reaction at several angles have been obtained with
12 Mev protons. The group of tritons corresponding to the ground state of Lib has
been observed in all spectra. In the small angle region a peak has been observed on
the continuous background due presumably to the Li7(p,p)Li7x He4 + t reaction, at
the energy corresponding to the expected group of tritons associated with the exci-
ted state of Lib The angular distribution of the main group of tritons shows that
the Li7(p,t)Heb reaction proceeds essentially without formation of compound-state.
The total cross section of tritium production has been measured as a function of pro-
ton energy. It amounts to 250 mb at Ep e 8 Mev and remains approximately constant
with further increase of energy.
SPECTRA OF NEUTRONS AND PROTONS FROM He4 + d REACTION AND
ENERGY LEVELS OF Lis AND He5
K. P. ARTENOV, 0.?. BOGWOV, N. A. VLASOV,
S.F. %ALININ, B. V. RYBAKOV, V.A. SIDOROV
The energy spectra of neutrons and protons from the bombardment of He4 by 18 Mev
deuterons have been measured. Neutron spectra were studied by the time-of-flight
FOd ~,d r~hedl':i. US-F, ONLY.
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
method and proton spectra by the time-of-flight method as well as by the nuclear
emulsion technique. Energy groups. corresponding to the ground states of Lib and Her
as well as continuous spectra due to, the deuteron breakup have been observed. The
shape of the spectra is discussed in connection with the problem of the existence
of Lib and He5 excited states at 2 - 3 Mev, on which there is no"agreement in the
literature.
ENERGY LEVELS OF Lie AND He5
E. A. ALBITZEAYA, E. I. KARPUSHKINA, YU. L. SOKOLOV,
N. N. SULKOVSLAYA.
The interaction of fast deuterons (up to 17.5 Mev) and neutrons (14 Mev) with Lie
and Liz nuclei has been studied using lithium impregnated nuclear emulsions. The adop-
ted experimeptal method permitted the identification of reactions resulting in the
emission of several particles. These reactions were shown to involve the formation
of the following Lie levels:
E1 = 2.2 Mev (T ^ 0) Ea 4.5 Mev (T - 0) E* = 5.2 Mev (T - 1)
E** = 5 7 Mev (T ^ 0) E*b "6.7 Mev (T - 1) Ee = 7.5 Mev (T = 0)
E; 8.3 Mev (T ^ 0)x E*e = 9.3 Mev (T = 0) Ee = 10.0 Mev (T ^ 0)
Ei070.7 Mev (T - 0) E* '-`11,,7 Mev (T - 0) (?)
Both channels of the reaction
Lie +
were investigated, one of them involving the formation of Heb. The formation of a
Heb nucleus in the ground state with E -1 Mev with respect to a + n has been observed.
The possible existence of an excited state of He5 is discussed..
xAocording to some indications this level seems to. have isotopic spin T ^.1.
JOR OFFICIAL USE ONLY
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
FOR OFFICIAL US ONLY
(p,n) REAC'T'ION ON LITHIUM AND THE GROUND STATE OF Bee.
G. F. BOGDANOV, N. A. VLASOV, S.F. KALININ,
B. V. RYBAKOV, V. A. SIDOROV
The neutron spectra of (LO' + p) and (Li7 + p) reactions have been studied by the
time-of-flight method with 9 Mev protons. Groups of neutrons resulting from the
(p,n) reaction due to the ground state of Be6 and to the three lower levels of Be7
have been.observed, as well as a continuous distribution of low energy neutrons re-
sulting from many-particle reactions. The observation of a neutron group from the
.Li6(p,n)Be6 reaction is the first experimental evidence of the existence of Beg. The
energy of the Li6(p,n)Be6 reaction is 5.2 Mev and the width of the ground state is
no more than 0.3 Mev. The differential cross sections have been measured for-the ang-
les of 0,15,30,60. and 1.20
ON THE RADIUS OF THE ALPHA PARTICLE
The potential parameters of the a particle are estimated and compared on the ba-
sis of cross section and polarization data for protons scattered at low (7 10 Mev)
ana high (ti 315 Mev) energies.
The a particle potential is chosen in the form
vlp(r) + vs r de ( -)
where p(r) is a function resembling nucleon density distribution; vl, vs are real
'Wt. low energies and complex at high energies. The potential is real at low energies
due to the fact that the a particle is an especially compact system.
The reliability of the experimental data together with the specific properties
of the a particle connected with its zero spin, small radius and high binding energy
makes possible unambiguous analysis with sufficient accuracy.
FOR urrk, I_ Ut)l ONLY
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
141
PAL
The following potential parameters were obtained for the p - He4 interaction:
p - He4 phase
shifts
1 - 10 Mev
Shape of
distribution
exp (-Erj2
0)
r0 ? 1013 cm
lvlj Mev
.ICI.10272
vi
p - He4 cross
section and pola-
rization, 315 Mev
Scattering of
185 Mev electrons
expl r2 )
i o
It is especially interesting to note that the interaction radius ro decreases by
30% when the proton energy rises to 300 Mev. The pronounced decrease in the p-He4 ra-
dius observed already at p ~ 0.7 is a reflection of a general property of nuclear for-
ces and is apparently related to the "delay" effects which should be.inherent 'in the
short range exchange forces.,
INTERACTION OF LOW ENERGY DEUTERONS WITH DEUTERIUM
AND TRITIUM
YU. G. BALASH%0, I. IA. BARIT
The scattering of low energy deuterons by. deuterium and tritium and the D-T
reaction at low.energies of the bombarding particles have been studied. The flux of
the bombarding particles in the scattering measurements has been determined from the
yield of the nuclear reaction accompanying the scattering using previously 'obtained
values of cross sections for the reaction. In order to. eliminate foreign pulses
(background, scattering on admixtures, etc.), coincidences between the scattered
particles and recoil nucleus have been measured. The scattered particles were recor-
ded with proportional counters which were not separated from the gaseous target by a
window and which together with the target were filled to a pressure of 2 -.5 mm Hg.
D-D scattering has been measured at an angle e - 56:5? in the 100 to-600 kev energy,
range (laboratory system). The ratios of the measured effective scattering cross sec-
tion to the effective cross, section for scattering in a Coulomb field are listed b-how
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
,FOR OFFICIAL USE Q KY,
Ed, ke
94
156
206
262
,300
350
410
470
532
595
a/ak
0.95?
.12
1.06?
?0.13
1.12?
?0.08
1.29?
?0.10
1.38?
?0.12
1.35?
?0.11
1.76?
?0.13
1.85?
?0.15
2.10?
?0.16
2.60?
?0.18
Analysis of the results of the measurements makes possible the estimation of the
phase shift in the 5S2 state. The effective scattering cross section can be described
as a purely potential one.
D-T scattering has been measured at an angle of 900 in the c.m.s. and in the tri-
ton energy range from 100 to 700 kev. The results are listed in the table in the same
units as those pertaining to D-D scattering:
N
ET, kev
a/aK
I
72?2
'0.64?0.08
2
90 ? 2
0.62 ? 0.06
3
?102?2
0.54?0.05
4
133 ? 2
0.55 ? 0.04
5
163 ? 2
0.63 ? 0.04
6
187?2
0.77?0.05
7
220 ? 5
1.12 ? 0.07
8 '
246?3.
1.35?0.08
9
300 ? 4
1.82 ? 0.10
10
362?5
2.50?0.17
11
418?6
3.20?0.18
12
472 ? 5
3.60 ? 0.22
13
655 ? 7
4.81?0.31
Measurements of the effective cross section for the D-T reaction were carried out
by Katsaurov et al. by means of a differentially pumped gas target and a thin zir-
conium target. Use of a differentially pumped target permits an accurate determina-
tion of the magnitude of the cross section in the vicinity of its maximum. The mea-
surements yielded a value of 107 ? 1 kev for the peak deuteron energy and '
(5.22 ? 0.1)10-24om2 for the effective cross section. The excited level in Heb should
also affect the scattering cross section. The. latter was calculated for reso-
nance parameters determined by analyzing the reaction taking into account potenti-
al scattering. The experimental scattering cross section values are close to those
obtained from the computed curves but lower by some 10 - 20%. A study of D-T scat-
tering along with the D-T reaction makes possible a better check of the applicabi-
lity of the resonance theory to the lightest nuclei and presumably also a more
precise determination of the resonance parameters of the He5 level.
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
MEASUR [ENTS OF CROSS SECTIONS OF THE B10(p,Y) and B10(d,n)
REACTIONS
A. K. WALT&R, A. S. DEYNE%0, A. YA. TARANOV
The absolute cross sections of the B10(p,y) and B10(d,n) reactions have been mea-
sured in the low-energy region of bombarding particles produced by the electrostatic
accelerator.
The method of absolute cross section measurements of the above reactions consisted
in the accumulation of the radioactive C11 nuclei in the bombarded target with a sub-
sequent measurement of their radioactive decay. The positron activity was detected
using a tube-electrometer of peculiar construction, a ring-type multi-filament coun-
ter and an end-window counter.
The reaction cross sections were measured at different energies of the bombarding
particles:
for B10(p,y) -.in the 325 - 1500 kev range,
for B10(d,n) - in the 100 - 400 kev range.
The following values of the cross sections have been obtained at low energies of
the bombarding particles:
a(p,y) - 5.10-31 cm2 by Ep - 350 kev,
o(d,n) - 8.10-29 cm2 by Ed - 95 kev.
SLOW NEUTRONS SCATTERING BY ORTHO - AND
PARA-TRITIUM
V. Z. KOLGANOV, A. P. LEBEDEV, S. YA. NIKITIN,
V. T. SNOLYANKIN, A. P. SOKOLOV, D. B. DIATROPTOV
The scattering cross sections of ortho-and pars-tritium for slow neutrons have been
determined by the transmission method. The measurements have been performed with an appatwr
tua previously used for hydrogen and deuterium investigations. A method of production
and of analysis of big quantities of ortho-and pars-tritium in gas form has been deve-
loped. Palladium metal was used as a catalyst in ortho-and para-conversion. Special
precautions for xorking with such high gas activities (20.000 curie) have been deve-
loped.
Two gas mixtures have been used to fill the scattering chamber:
a) 75% ortho-end 25% pars-tritium
b) 35% ortho-end 65% pars-tritium.
FOR OFFICIAL USE ONL
i Key
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01 CIA-RDP80T00246AO44100140001-6
FOR OFFr06 AL USE ONLY,
.The gas has been carefully purified since the presence of even a small admixture
of Ha (decay product of tritium) is very undesirable. Owing to its very large neutron
cross section (3.104 barns) such an admixture can introduce considerable incertainties.
Six runs have been made (three with each mixture).
The results are:
rogen temperature.
The first mixture is at equilibrium at room temperature, the second at liquid hyd
? Para-tritium - 1.0 t 1.5 barns.
4.5 ? 1.0 barns
ortho-tritium ':
INTERPRETATION OF TRANSITION PROBABILITIES
FOR REACTIONS IN LIGHT NUCLEI
Using the intermediate coupling methods of the shell model one can calculate
transition probabilities for several kinds of nuclear reaction. Results will be pre-
sented for reduced widths of some (n,y) and (d,p) stripping reactions in isotopes of
Li, C, N, and 0, for the p--decay of Lie, C14, N16, and 019, and for some branching
ratios and lifetimes of y-ray emitting levels. Particular attention is given to the
enhancement of electric quadrupole transitions due to collective vibrations of the
core.
u'LL
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
E p -V v r q _ USE O .
POLARIZATION EFFECTS AT NUCLEAR REACTIONS
SOURCES OF POLARIZED PARTICLES
B. P. ADYASEVICE, S. T . BELYAEV, YU. P. POL U-
NIN, E. E. ZAVOYSEY
The study of spin dependence of nuclear forces is of great importance. Experi-
ments on polarization effects occurring in nuclear.reactions require double and
sometimes triple scattering which presents great experimental difficulties.
Modern types of accelerators make it possible to accelerate beams of polarized
particles without practically any depolarization of these particles in the process
of acceleration.
The construction of sources of polarized particles may be based on the followiq
principles:
a) the use of nuclear scattering;
b) the polarization of atoms through electronic spin;
o) the use of metastable states 251/2.
The report discusses intensities which may be achieved with sources of this type
as well as several source designs.
POLARIZATION OF PROTONS SCATTERED BY 018 SPIN AND
PARITY OF THE 3.11 Mev LEVEL 'OF THE .F17 NUCLEUS
P. V. SOROKIN, A.K. FALTER, B. V. GAVRILOVSKY,
K. V. BARAD.IEV, V. I. IANKO, A. Y. TARANOV
The study of polarization produced in the elastic scattering of protons in the
2.6-2.8 Mev range by 016 has been unaertaken with the aim of determining the moment
and parity. of the 3.11 Mev state of the F17 nucleus.
The degree of polarization of the proton beam after scattering by oxygen nuclei
was determined from the asymmetry in the elastic scattering-by He4. It was shown
WiQm~ 4 3 Mev by the threshold detector
method.
The angular distributions of photoneutrons from Bi, Au and Ta are different. The
highest anisotropy. is found for Bi. The results are compared with Wilkinson's cal-
culations.
LOW ENERGY GAMMA-RAYS IN THE F19(p,xy)O16 REACTION
S. A. E. JOHANSSON, H.;IORINAGA
The gamma-ray spectrum' resulting from proton bombardment of fluorine has been ca-
refully investigated in order to find gamma-transitions between the first four exci-
ted states in 018. The transition between''the 6.91 Mev and the 6.14 Mev states was
-3U-
FOR OEf t 1 L USE ONLY
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
. v it .. .J i.~
found. Upper limits were set for the other three possible transitions. These values.
furnish information about the strength of the isotopic spin selection rules.
A.N.GORBONOV and V.M.SPIRIDONOV
Protodisintegration of helium was studied with a cloud-chamber located in' the
magnetic field and operating in the bremsstrahlung beam of the synchrotron of the
Lebedev Physical Institute.
At 170 Mev maximum energy about 10 000 pictures were obtained. The number of pho-
todisintegrations in helium registered on these pictures is shown below:
He4(yp)H3. . . . . . . 2835
He4 (yn) He3 . . . . . . . . 2684
He4(ypn)D.He4(y,2p,2n) 547'-`
He4(y,2d). . . . . . . . < 59
The cross sections and angular distributions for yp, yn and Ypnd reactions have
been measured. The results show that
1) the electrical dipole absorption of the photons makes the principal contribu-
tion to the cross section for yp and yn reactions at energies below 30 Mev. At ener-
gies above 30 Mev the electrical quadrupole absorptiog of photons leads to a strong
forward asymmetry in the. angular distribution of protons for the yp reaction in the
center-of-mass system. For the yn reaction this asymmetry relative to.90? C.M. is
absent within the experimental errors, the angular distribution below and above
30 Mev remaining close to since c:m,
2)'the angular distributions. of protons and neutrons-for the He4(y,pn)D reaction
are similar to angular distributions of particles from the photodisintegration of
deuteron. This shows that the two-nucleon mechanism plays an.appreciable role in the
photon absorption at energies above 30 Mev;
3), from the experimental cross sections for yp, 'Yn and ypnd reactions the. integral
cross section for the photon absorption by the helium nucleus has.been calculated. The
obtained value aint = fc(w)dw = 100.?7 Mev-mbn is in satisfactory agreement with the
sum rule calculations for electrical dipole. absorption. The experimental. value
5 oabw(w) dw.= 2.4 ?0.15 mbn leads to the nuclear radius parameter ro=(1.12to.o4)x1O-13cm
which is in good agreement with the value ro obtained from the electron scattering
experiments in helium;
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
4) the approximate equality of yields of the He4(jp)H3 and He4(yn)He3 reactions
(X = 0.95 ?0.04) and the low yield of the He4(yd)d reaction (Yp 12--d 1 0?.02) are in
good agreement with the predictions of the charge-independence hypothesis.
PHOTODISINTEGRATION OF NUCLEI BY GAMMA- RADIATION FROM LENINGRAD
SYNChROTRON AT 60- 90 Mev
E. B. BAZHANOW, J. P. JAWOR, A. P. KOMAR,
L.A. KULTSHITZKY, E. D. NACHNOWSBY,
W.P. TSHIZHOW and J. N. YOLKOW.
In the last few years the research-staff of the X- and y- ray Laboratory of the
Physical-Technical Institute of the USSR Academy of Sciences investigated photonuclear
reactions with the following apparatus:
a) fast overcompression cloud chamber;
b) scintillation telescopes;
c) ionization chambers;
d) chambers with nuclear plates.
The following results were obtained:
a) The angular distributions of 2 to 10 Mev protons from argon and of 1 to 15 Mev
protons from neon.
Apparatus: fast overcompression cloud chamber.
b) The energy and angular distributions of 15 to 65 Mev protons from Be, Al, Ni
and Au in the laboratory system. Apparatus: scintillation telescopes.
c) The ratios of photodeuteron yield to the yield of photoprotons from Au for
EYmax = 70 Mev. Apparatus: chamber with nuclear plates and scintillation telescopes.
The angular distribution of photoprotons from neon may be described by a formula
of the type:
a+bsinae,
where a = 2.5, i.e. they have a maximum of angular distribution at a= 90?.
The maximum of the angular distribution of protons from argon is shifted to the
70? region. The shift is due to the interference of dipole and quadrupole absorption
of y-rays.
The maximum of angular distribution of 15 to 65 Mev protons from Ni and Al
is shifted towards small angles with increasing proton energy,.. The angular distribu-
tions of 30 to 65 Mev protons exhibits a maximum at angles < 45?. There is no simple
explanation of this fact.
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
~4r
OTE L1
The energy distribution curves for 15 to 65 Mev protons from Be, Al, Ni and Au,
and for 15 to 65 Mev deuterons from Be show sharp breaks when plotted in log-log
scale. The break in the proton spectrum is in accordance with the deuteron model of
Levinger.
The sharp break in the deuteron spectrum seems to be in accordance with the
a particle model of y-ray absorption.
Investigations of d-d, p-p and p-n coincidences are in progress.
PHOTODISINTEGRATION OF DEUTERON AT 50 - 150 Mev
U. A. ALE%ANDROV, N. B. DELONE; L. I. SLOVOBO-
TOV, G.A.SOEOL, L.N.SHTARKOV
The reaction of deuteron photodisintegration has been investigated at the 265-Mev
synchrotron of the P.N.Lebedev Physical Institute, USSR Academy of Sciences. Protons
from D20 and Hs0 targets have been detected by a two-counter telescope.
The differential cress section has been measured for six points of photon ener-
gies from 50 to 150 Mev and for seven points of angles from 22.5 to 157.5 degrees in
the laboratory system. The obtained values of cross sections in the center of mass
system are listed in Table 1. Energy uncertainty is about ? 7.5 Me-v. Standart statis-
tic errors are about 10%. The systematic uncertainty of the absolute cross section
value,is about 15%.
Photon
energies,
Mev
Angles and differential cross section, ?barn/sterad.
25?
500
740
97?
1180
139?
160?
6.0
11.2
13.3
-
9.1
5.7
3.7
260
510
75?
98?
1190
140?
160?
5.5
11.1
10.8
6.8
4.1
3.0
27?
52?
76?
99?
120
140?
160?
7.0
9.8
9.0
6.1
6.6
3.5
5.2
27?
53?
770
100?
121?
1410
161?
6.7
8.1
7.7
4.0
2.8
27?
54?
78?
100
122
42
7.3
5.8
4.9
4.9
4.7
3.6
2.9
280
54?
79?
101?
122?
1420
1610
6.2
.6.9
5.6
5.4
5.3
3.4
4.3
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
a
The angle distributions in the center of mass system are in satisfactory agreement
with the forma _ (V + P + Q ? cos9, where (a5) is the differential cross sec-
tion M. G.
obtained by Marshall and Guth, P and Q are approximation parameters. The values
of parameters obtained by the least square method are listed in table 2. The value 4n?P
is the total cross section of transitions leading to isotropic angle distribution.
at is the value of the total cross section of photodisintegration calculated from the
equation at = (at) M. G. 479-P-
Photon
Photon
energies,
Mev
P
wbarn/ster.
Q
Nbarn/ster.
4n'P
barn
at
ibarn
t
ybarn
54
1.30
-0.76
16.3
129.1
5.1
70
2.72
0.92
34.2
105.2
3.6
88
3.50
0.81
44.2
89.5
4.6
110
3.80
1.11
47.8
77.2
3.5
129
3.27
0.42
41.1
61.9
3.6
148
4.27
1.00
53.7
69.1
4.1
Interpretation of data is based on Marshall and Guth's calculations and on Wilson's
idea about photodisintegration by meson production and reabsorption. Calculated va-
lues of the total cross section of multipole transitions are in reasonable agreement
with Wilson's results and Nagahara and Fudsimura's calculations.
SOME PHOTOREACTIONS ON LIGHT NUCLEI
A number of reactions on C12, N14 and 018 nuclei, produced in photoemulsions by
Bremsstrahlung spectrum with maximum energies of 150 Mev and 250 Mev are investigated.
i. C12(Y,3a) and C1?(Y,4a) reactions
340 events of oxygen nucleus disintegration and 180 events of hydrogen disintegra-
tion have been observed. The dependence of the reaction cross section on the y-ray
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
~jl
.energy has been determined. No events have been found in which the photon energy exceed-
ed > 50 Mev. The sharp decrease in the reaction cross.section in the 35 Mev energy
range may possibly be connected with the competition of (y,pa) reactions on 012 and
Ole nuclei.
2. Ci12(Y,pa), N14(Y,p2.) and O16(Y,Pc) reactions
473, 209 and 316 stars have been found corresponding to the three above reactions
respectively. Dependence of cross sections on Y-ray energy, angular and energy distri-
butions of disintegration products have been obtained. The analysis of experimental ,
data from the point of view of the Y-ray energy distribution between the reaction pro-
ducts shows that:
a) the interactions of Y-rays with carbon and oxygen nuclei leading to the above
reactions are apparently of the same nature:
b) the absorption of photons by nuclei varies with the increase of Y-ray energy.
In the energy region EY=25 - 50 Mev the energy of the absorbed photon is distributed
"symmetrically" between the reaction products so that the energy distribution of par-
ticles is determined only by the phase space volume. The results are not in contra-
diction with the model of series decay, but may likewise be explained from the point
of view of simultaneous disintegration into three non-interacting particles;
c) in the energy region EY > 50 Mev, protons are energetically favoured in compa-
rison with other particles and carry off from 60 to 90 per cent of the available ener-
gy Eo =E y - Fbound* The interaction of the photon with the nuclei is apparently local
(direct photoeffect). The formation of an intermediate nucleus in the reaction is not
excludes.
3. c'2(Y,pa)2a reaction
Preliminary results have been obtained. The integral cross section of the reaction
between 30 and 80 Mev is 5 mb/Mev. The energy distributions of protons and tritons
have maxima near 4 Mev and 3 Mev respectively.. The angular distribution of protons
shows a small isotropic part and a forward shift of maximum from 90?. The investigated
reactions play an important part in photostdr production. Thus, the cross sections
of C12(y,pa)Li7 and Ga2(y,pt)2a reactions in the 30-80 Mev energy range contribute
ti 50 per cent of the total photostar production.
ON THE WIDTH OF THE GIANT RESONANCE IN PhOTONUCLEAR
REACTIONS
S.A.E.JOHANSSON
The shape of the giant resonance in photonuclear'reactions will be discussed in
terms of various models. The available experimdntal material is reviewed. It is shown
in what cases the measured cross section curves give the shape of the total cross
FGR ! t C t.. USE ONL
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
FOR WOOL WE W
section curve for photon absorption. It turns out that there exists a good correla-
tion between the width of the giant resonance and the shiape of the nucleus. Deformed
nuclei have a?considerablybroader resonance than other ones. This fact is easiest
to explain by the collective model for photonuclear reactions. li
ON THE MECHANISM OF GIANT RESONANCE
V. V. DARAGAN, Yu. N. SHIROKOV
A two-nucleon model is suggested for the explanation of the Giant Resonance in the
photo-nuclear reactions. According to the model, the photon is absorbed by two mu-
tually interacting nucleons. The existence of this interaction in the giant resonance
energy interval is indicated by the occurrence of the direct nucleon-nucleon interac-
tion in this region. The model agrees with the principal experimental data on the
giant resonance. Particularly, it leads to the correct position of the resonance ma-
ximum. Our considerations include the one-nucleon model suggested by Wilkinson, which
also contributes to the absorption cross section but plays an important role in the
energy region below the giant resonance. Therefore if the one-nucleon maximum is
above the photo nucleon threshold the absorption cross section must possess in gene-
ral two dipole maxima. The existence of the two maxima has been observed in the expe-
riments on C13 and N14
In the numerous former investigations of interaction of photons with nuclei the
influence of nuclear spin on this interaction was not considered. It may be shown
that nuclear spin can play an essential role in such processes.
The general expression for the electric dipole scattering amplitude has the form:
S = S, I) + S1'(I 1) 6.1) + S3(i.a f)
where the a and r' = polarization vectors of the incoming and outgoing pnotons respec-
tively, f = operator of nuclear spin, S1 and S. = parameters independent of a and
scattering angles.
-38 FOR OFF CIAL USL UNLt
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
As follows from calculations the angular distribution of the scattered photons con-
tains terms of the type (1- singe cos2cp) , where e = scattering angle, y= asimuthal
scattering angle at Sl # 0. The value of such terms is dependent on the relationship
between S1 and S3 and on magnitude of nuclear spin.
The cross section of any photonuclear reaction on nuclei with large spins is de-
pendent on orientation of the spin with respect to the direction of the photon beam.
The magnitude of the above mentioned effects (the relationship between parameters
such as S1 and S3) depends to a high degree on the accepted model. The comparison of
experimental data with results of calculations with different models can help in un-
derstanding the mechanism of interaction of electromagnetic field with nuclei and
the nature of nuclear spin.
D. A. WILKINSON
A brief survey is presented of the chief facts of nuclear photodisintegration
especially in the region of the fiant resonance (EY < 30 Mev). The systematics of
the various processes are sketched and related to other parameters that characteri-
ze the nuclear system.
The two chief models so far adduced to account for the phenomena - the model of
nuclear polarization and the shell model - are described with particular reference
to refinements recently introduced into each. Recent attempts to reconcile the ap-
parently conflicting physical pictures lying behind these two models are described
and their possible equivalence is indicated.
Experiments in which detailed comparison appear: possible with one or other mo-
del (in the light elements for the shell model and in the heavy elements for the
collective model) are reported. A qualitative account is given of certain aspects
of the photonuclear process at slightly higher energies.
INTERPRETATION OF THE GIANT RESONANCE
PHENOMENON IN THE PHOTODISINTEGRATION OF 016
A shell model calculation has been performed for the odd parity states of 016
which arise from the almost degenerate configurations p-1s and p-1d. In terms of
these states a natural explanation can be given of the giant resonance, of, its fine
structure, and of the associated nucleon emission characteristics, all of which lend
strong support to Wilkinson's picture of the giant-resonance phenomenon.
r' - IU L, USE ONLY
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
NUCLEAR REACTIONS INDUCED
BY HEAVY IONS
It follows from experimental data that in the interaction of heavy ions with
nuclei the formation of excited compound nuclei plays a predominant role, the excita-
tion energy -eaching several hundred Mev. The production of such highly excited nuclei
by any other method is impossible.
The characteristic feature of the reactions induced by heavy ions is that com-
pound nuclei receive a large angular momentum. The. investigation of highly excited
nuclei with large angular momenta is one of a whole ser'.es of investigations using
heavy ions.
The interaction of heavy ions with nuclei gives rise to an exchange of nucleons
or complexes of nucleons between interacting nuclei.
These processes proceed at the periphery of the nucleus and their investigation
may furnish information on the surface structure of the nucleus. In addition to the
above-mentioned lines of investigation, heavy ions may be used for the production of
new isomers (both by Coulomb excitation and by means of compound nuclei formation),
new isotopes and elements. Recently the interaction of heavy ions with different nuc-
lei has been investigated in several laboratories, the greater part of these investi-
gations being devoted to the solution of the problem wether the formation of compound
nuclei is the principal process in the reactions induced by heavy ions.
The process of nucleon exchange has been investigated and some new isotopes and
elements produced. The greater part of this work has been performed using a beam
of nonmonoenergetic ions.
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
Intensive beams of monoenergetic carbon, nitrogen and oxygen ions with energies
upwards of 100 Mev were obtained in 1956. It has made possible a series of new inves-
tigations, from which a sufficiently complete idea about the character of the nuclear
reactions induced by heavy ions may be derived.
It may be assumed that the formation of compound nucleus is the predominant pro-
cess in the reactions with heavy ions.
Heavy nuclei are characterized by evaporation of neutrons and fission. For light
and intermediate nuclei the emission of a number of charged particles,besides neut-
rons, has been observed.
INTERACTION BETWEEN NITROGEN IONS AND HEAVY
ELEMENT NUCLEI
S. A. BARABOSHEIN, V.A. DRUIN, A. S. KARA-
NIAN, S. N. POLIKANOV, G. N. FLEROV
The monoenergetic 115-Mev beam of nitrogen ions N14 from the cyclotron of the Ato-
mic Energy Institute, USSR Academy of Sciences, has been used to investigate the de-
pendence of the cross sections on nitrogen energy for Au (N, 4n), Au(N,5n), Au(N,6n)
reactions.
In accordance with the theory of competitive processes curves with pronounced
peaks have been obtained.
The measured Au(N,4n), Au(N,5n), Au(N,6n) excitation functions have been compared
to the excitation functions predicted by the compound nucleus theory. The excitation
functions from this experiment are displaced in energy by 10-15 Mev which is not pre-
dicted by the theory.
It is possible that the observed energy shift may be explained by a very high an-
gular momentum imparted to the heavy compound nucleus by the 100 Mev N14 nucleus.
Experiments in fission of U235, U238, Bi, Au and Re induced by accelerated nitro-
gen ions are likewise describes. The measurements have been conducted with an ioniza-
tion chamber.
The dependence of the fission cross sections for these nuclei on the nitrogen ion
energy has been studied in the energy range from 70 to 110 Mev. The obtained. re-
sults are analyzed from the viewpoint of the influence of the Z and A parameters and
the excitation energy on fission probability.
IMAL U 6nI
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
F FF C AL USE ONLY
STRIPPING REACTION PRODUCED BY ACCELERATED
IONS N14 ON SOME NUCLEI
The formation of a radioactive isotope Ni. has been observed due to stripping
reaction under bombardment of thin Al, Ni, Cu, Ag, Co, Sn and Pt foils by nitrogen
ions N14 (E ti 100 Mev) from the cyclotron of the Atomic Energy Institute USSR Aca-
demy of Sciences. The angular distribution of N13 is characterized by narrow inter-
val angles of particle emission (20? - 30?). For the incident N14 energy of about
60 Mev an intensity maximum of N13 for Al at about 10?, for Ni -at 30?, for Sn and
Ag -at 600 has been observed. The cross section of N13 formation for Al and Ni has
been measured in the energy range from 30 Mev to 105 Mev. The cross section varies
but slightly at energies higher than the Coulomb barrier and is 10 mb for Al and
30 mb for Ni in this range.
MASS DISTRIBUTION OF FISSION FRAGMENTS
FORMED BY NITROGEN IONS ON GOLD AND URANIUM NUCLEI
N. I. TARANTIN, Ju. B. GERLIT, L. I. GUSEVA,
B. F. IYASOEDOV, K. V. FILIPPOVA; 0. N. FLEROV
In the present paper the mass spectrum of fission products formed on irradiation
of 30 ? thick gold and uranium targets with 115 Mev N14 ions has been investigated.
Fourteen different elements have been chemically separated from the irradiated tar-
gets. The isolated radioisotopes have been identified by the half-life, beta-energy
and the sigg.of the beta-particle charge.
Mass distribution of fission fragments from the gold target irradiated with nitro-
gen ions is represented by a single curve with a broad maximum. The width of the
curve at half--maximum is about 20 mass units. The maximum of the curve corresponds
toA-100.
Mass spectrum of fission fragments formed on irradiation of uranium with nitrogen
ions is found to be-considerably more narrow. The width of the curve at half-maximum
contains more than 50 mass units.
FOR OFFICIAL USE ONLt
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
The influence of nuclear rotation on the fission barrier height is calculated
using the nuclear drop model. This influence is connected with the moment of inertia
change due to deformation. For large angular momentum > 50;h (such nuclei are formed
by the capture of heavy ions by atomic nuclei) the rotation essentially influences
the fission barrier height. The nucleus becomes unstable owing to fission for a cri-
tical value of the angular momentum. The dependence of mass distribution of fragments
on the momentum is slight.
STATISTICAL THEORY OF ANGULAR DISTRIBUTION
OF FISSION FRAGMENTS
The angular distribution of fission fragments is.considered in case when the an-
gular moment of compound system is distributed. among a large number of nucleons and
one can describe nucleus with statistical model approximation. The distribution of K
values (where K is the projection of angular moment of"transition" nucleus in the
direction of the symmetry axis) is calculated. The state with K- 0 turns out to be
the most probable one which gives maxima in e= 0, n directions for fission fragment
angular distribution in nucleon - induced fission and in e= direction in case of
photofissiou. The comparison with experimental data allows to determine the value of
the moment of inertia in relation to symmetry axis. Fong's theory of assymmetrical
fission is discussed from the point of view of-angular distribution of fragments.
FGA Ursa i L USt Qlvti
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
'R, 3RIK Wc a, 3,
NUCLEAR MODELS
P. E. NEHIROVSIY
The up-to-date state of the theory of neutron interaction with nuclei at low and
intermediate energies is analyzed.: The processes at very low energies are discussed,
the strength function and potential scattering data are compared with theory.
The total cross sections and angular distributions are considered in the usual
scheme, and also taking account of the spin - orbit forces.: It is shown that addi-
tion of the spin - orbit interaction makes the agreement with experiment better.: For
400 kev neutrons the theory is compared with polarization experiments. For higher
energies the estimation of polarization is made.
The variation of optical parameters (the well depth, the absorption factor) with
ei.ergy is discussed.
For 14 - 20 Mev neutron energies several theoretical papers dealing with experi-
mental data are critically discussed.
Finally, some considerations about the relation between optical potential and
shell model - potential are advanced.
Time 40 minutes.
INTERACTION OF SLOW NEUTRONS WITH SPHERICAL AND
ELONGATED NUCLEI
The paper reports on the results of calculations of slow neutron interaction with
elongated nuclei, according to the cloudy crystal model of the nucleus, carried out
by V. V.Vladimirsky and by I.L.Ilyina, and on interaction of slow neutrons with nuclei,
MR OFF C A USE ONLY
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
as reviewed by V. V. Vladimirsky, I. A. Radkevich, V. V. Sokolovsky and A. A. Panov. The solu-
tion of the problem of neutron motion in a complex potential well for an elongated
nucleus has shown that the position and the shape of the giant neutron absorption re-
sonances, depending on the atomic number, changes appreciably in the transition from
spherical to'elongated nuclei. This enables one to explain qualitatively the washed
out character of the giant resonance near A-150 without recourse to an increase of
the imaginary part of the complex potential.
TOTAL NEUTRON CROSS.SECTIONS AT 1-14 Mev
ACCORDING TO THE OPTICAL MODEL OF THE NUCLEUS
Total neutron cross sections in the 1-14 Mev range for Fe, Sn, Pb nuclei have
been calculated according to the optical.model of the nucleus with potential in the
form of a rectangular well.
A good agreement with experimental data has been obtained for the three nuclei
'belonging to three different regions of the periodic table.
OPTICAL MODEL OF NUCLEONS - NUCLEI INTERACTION
IN THE RESONANCE REGION OF THE COMPOUND NUCLEUS
Y. H. AGRAHOVICH, A. S. DAVYDOV
The energy dependence of the real and imaginary parts of the effective potential
of the optical model is investigated taking into account all states of the compound
nucleus. It is shown that only the real part of the effective potential of the opti-??
cal model is the smooth function of the neutron energy in the resonance regior of..
the compound nucleus.
In the computation of the imaginary part of the effective potential the deviatjaa
from the potential of the optical model was considered as a perturbation leading to
the compound nucleus formation. Interpretation is given for the broad resonances-in
the interaction between neutrons and nuclei.
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246A044100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
a' OFFICIAL USE UNL'
Contrary to the theory of Lane,. Thomas and Wigner, it is shown that the imaginary
part of the potential -in the, resonance region is considerably smaller than the root
square of the second moment and essentially depends on the level density of the com-
pound nucleus. This result coincides with those of Bloch.
YD .1f. SHIROKOV, %. A. TUMANOV A. W. BALASHOV,
0.F. DOROFEYEV, N. N. %ALITKIN, A. K. KANINSKY,
YU. F. SNIRNOV,
A method for deriving ground and first excited energy levels and wave functions
of light nuclei is suggested. Charge-independent nucleon-nucleon interaction is as-
sumed, many-body forces being neglected. The Coulomb energies.are taken into consi-
deration separately. In contra distinction to the usual procedure a form of two-body
interaction hamiltonian is not preset. The matrix elements of this hamiltonian ne-
cessary for the calculation are derived from the experimental values of nuclear
energy levels.
The problem of separation of nucleus centre-mass movement is. solved by substrac-
tion of kinetic energy of the whole nucleus from the complete hamiltonian. It is
thus possible not to apply Jacoby coordinates using ordinary antisymmetricalfunc-
tions.
A nucleus wave function is given by resolution into the configurations of harmo-
nic oscillator states. This resolution is believed to converge rapidly with regard
to the main quantum number and so it is cut short, all the allowed configurations
within the taken quantum numbers (lb, llp - shells for the nuclei to 0) being consi-
dered. Then the Schrodinger equations for the different nuclei and-levels are formed
in this oscillator representation. Matrix elements of the interaction hamiltonian
,can be expressed in terms of two-body configuration matrix elements. There are only
32 such elements within 1s, lp-states (spin and isobaric spin to be taken into ac-
count). Owing to the conservation laws for two-body interaction, these 32 elements
are not independent. One can obtain 16 independent matrix elements by excluding the
movement of centre of inertia of two, interacting nucleons by Talmi method. The mat-
rix elements of Coulomb interaction are calculated in the same way
Thus for the ground and excited states of light nuclei we have secular equations
including as unknown variables 16 parameters of nucleon-nucleon interaction. If one
considers only the states with undestroyed S-shell for nuclei between He4 and 018
three parameters out of sixteen drop. out of this equation. The equations include
also two parameters associated with nuclear dimensions.
The derived system of equations is solved using computing machine technique.
-4d
,F!l,R OFFIC,14 USE ONLY
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
owl
INTERMEDIATE ENERGY NEUTRON SCATTERING
BY NON-SPHERICAL NUCLEI
In the work on neutron scattering by non-s1,:ierical nuclei examination was carried
out either in the approximation kR>1, where k is neutron wave-vector and R, the nuc-
leus radius, i.e. for high energy neutrons or according to the perturbation theory
which is probably incorrect in this case.
The author considers the case of neutrons of intermediate energy, of a few- -Mev. This..
case is--interesting from the point of view of comparison with the experiment. The
calculations are made in the adiabatic approximation, where the nucleus is consider-
ed to be at rest during the time of collision. The approximation is valid when
? kR < 1,
En
where e is the energy of the first excited rotation state,
En is the energy of the incident neutron.
In the adiabatic approximation the case is reduced to the problem of the partic-
le scattering in a given field.
The latter is considered as constant inside the nucleus which has the rotation
ellipsoid (spheroidal) form,and as equal to zero outside the nucleus. This problem
is solved with the.aid of well-known and partially tabulated spheroidal functions.
The necessary averaging is performed over the nucleus orientations and expressions
for the cross section of the elastic and inelastic scattering are obtained.
A numerical example is computed showing the effect of non-sphericity of the nuc
leus to be considerable.
THE ROLE OF PAIRING INTERACTION ON FORMATION OF DEFORMED NUCLEI
B. L. BIRBRAIR AND L. A.,SLIY-
TheF if of static deformation of nuclei is observed. If; we-itake into,;ac05iuii only,
of nucleohp.outside'closed"shells then, as is known, ttie;energyy decrea-
wiKth..deformation.
Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
 Sanitized Copy Approved for Release 2010/06/01: CIA-RDP80T00246AO44100140001-6
The core deformation energy increases quadratically with deformation. That is the
reason why for every nucleus a minimum energy deformation exists and all nuclei would
be deformed (Fig.1).
But we have to take into consideration a new factor: spe-
cific pairing energy which decreases when we go over from
spherical to deformed state of nucleus. The shape of pairing
interaction curve for two nucleons is calculated as perturba-
tion using '8-forces and other short-range forces (Fig.2).
The difference AEp can be taken from mass-defect data which
give about 2 Mev for light and 0.5 Mev for heavy nuclei.
All the three factors taken together create such a situa-
tion for nuclei between closed shells that nuclei are deform-
ed only in definite region Al A2 between closed shells
(Fig.3).
If we assume for AEp (per one pair) 0.7 Mev in rare-earth
region and 0.5 Mev for heavy elements we get the correct
boundaries for deformed nuclei. We have also found out that
deformed states are-theoretically possible only in three
(known) regions throughout the,periodical table.
.COLLECTIVE EXCITATIONS OF EVEN-EVEN ATOMIC NUCLEI
The problem of collective excitations in an even-even nucleus possessing axial .
symmetry is considered without assuming the rotational energy to be much smaller
than the vibrational energy.
The energy levels of the. collective excitations and the succession of spins have
been computed for different parameters of deformation. It is shown.that the energy
of .the collective excitations can be represented. as the function of only two para-
meters: co, - FB' and 8 = P, CBC /1/4. In the 8>2.5 region the excitation spectrum
can be represented as a system of rotational vibrational bands. In the 8