SCIENTIFIC ABSTRACT SIROTININ, YE.I. - SIROTKIN, A.A.

• Document Type: CREST
• Collection: Scientific Abstracts
• Document Number (FOIA) /ESDN (CREST): CIA-RDP86-00513R001550830003-6
• Release Decision: RIF
• Original Classification: S
• Document Page Count: 100
• Document Creation Date: November 2, 2016
• Document Release Date: August 24, 2000
• Sequence Number: 3
• Publication Date: December 31, 1967
• Content Type: SCIENTIFIC ABSTRACT

A-
hrmak. -
dV 6, OW B 1029212
AUTHORSs Itileyov, Yu. A., Zamyatnin, Yu. S., Sirotinin, Ye. I.,
Fomushkin, E. F.
TITLEt Spectra of fission neutrons from U235 emitted at angles of
0, 45, and 90 to the direction of flight of the fragments
FERIODICALj Atomnays enorgiya, v. 99 no. 6, 1960, 449-454
TEM The result@ of previous measurements of spectra of fission neutrons
and their angular distribution with respect to the direction of flight of
the fragments agree well with theoretical data (based on an assumption of
isotropic neutron evaporation and Ka"ell neutron distribution)l but this
theory furnishes values for the moan kinetic energy of the fragments,
which are somewhat too low, and, therefore, the correctness of above x
assumptions may be doubted. In order to chock it the authors have
measured again the neutron spectra, and this paper r8ports on the results.
The spectra of the neutrons emitted at 0, 45, and 90 t? the direction of
flight of the fragments in 14-3-Mev neutron induced U23 fissions have been
measured, and also their angular distribution has been determined. The
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Spectra of fission neutronsoot B102[B212
time-of-flight method was utilizodg the distanot of flight was 75 cm and
the resolution time 7 yesc. A detailed description of this method and
the equipment used I given in Ref, 9 (Yu.A.Vasillyev idr. Zh.oksperim. i
toor.fiz. Up 671 (140)). Howeverp the method employed here made use of
a multi-layor fission chamber with fragment oollimation as a fission-
neutron source. A U235 layer had boon deposited on both sides of an
aluminum foil (having a thickness of 0.5 *1 the thickness of the layer
'was 6 mglcm~gq and the total weight of the two layers amounted to 3.5 9-
0-75% of the fission taking place in the uranium have boon recorded. The
chamber was filled with a mixture of argon and carbon dioxide 00%)
(pressure 760 mm Big). The rise time of the pulses was about 0 1/4800 at a
I kv electrode potentia 1, PiS. 2 shows the experiment:1 stup: 0Fig;03
shows the neutron spectra F(En) in arbitrary units mea ur:d at 0 t 4 p and
900. Fig. 5 shows the spectra of neutrons emitted from the fission frag-
monts. The angular distribution has boon calculat 11 d by numerical intogra-
tion with respect to the neutron energy (of. Table). The angular
distribution of the t rays (Er> 0.3 Nov) produced during fission has also
b::n itulatod by assumine an isotppy relative to the direction of flight
0 d A

SpQctra of fissio n neutrons...
- rrnu~
S/08,6/60/009/006/001/011
3102/B212
of the fragments. Here are th e values obtained; n,"~00):n (450).-n (900),
(1-31+0-07):(1.22+0.o6):1.00. The neutron distribution showed a con-
sriderab'fe anisotropy: b N(OO)IN(900) = 3.23:LO.12. The following
14
value has been obtained after subtracting the neutrons evaporated before
a fission bt -.4.03 :t 0.23; this value agrees within the limits of error
14
with that obtained for -thermal neutrons (b t - 4.3510.19). In order to
describe these experimental results theorotically, calculations have bedn
done and various assumptions have been made regarding the neutron spectra
in the coordinate system of the fragments. However, no variant.was able
to yield satisfactory results that agreed 'with all three spectra which
have been examined. The authors thank P. V. Toropov, Yu. Ya. Glazunov,
k. N. 11olaslov, N. I. Nemudrov,' V. A. Parshina, V.. S. Khorkhordin,
V. k. Komarova, 14. P. Novikova, G. A. Peretokina,.and L. A. Chernova for
assistance. There are 6 figures, 1 table, and 14 references: 6 Soviet-
bloc and 8 non-Soviet-bloc. The three references to English-language
publications read. as follows: Rbf. 7: V.Stein.Phys.Rev. 108, 94 (1957);
Ref. 10: S. Whetstone. Phys.Rev., 114, 581 (1959); Ref. 12: Terrell,
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S,p4-ctra of fissibn neutrons... B102/B212
Phys.Rev., lu, 127 (1959).
SUBMITTED: February 29, 1960
17yvex eedm
Legend to Fig. 2: 1) U 235, lay4r; #MAU,-, -10
2) deuteron beam; 3) target;
4) collimators.
.01
N-e 0*
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S/ 056/60/036/03/02/033
B006/BG14
AUTHURSt Vaail'Zev, Yu, A., Zamyajij~n, Yu..S., Illin, Yu. I..,
Sirotinin, Ye. ., Toropov,_P. -,-Fomushkin, E.J.
TITLE: Measurement of Spectra and the Average Neutron-Number in the
Fission of U 235 and U238 by 14-3-Mev Neutrons
I't
PERIODICALz Zhurnal eksperimentallnoy i teoreticheskoy fizikig 1960~
Vol- 38, No- 39 pp. 671-684
TEXT: The present article deals in detail with the experimental inve8ti-
gations made in the energy range 0-4 - 5 Mev by means of the time-of-flight
technique and a pulsed neutron source. The experimental arrangement is
schematically shown in Fig. 1. The reaction T(dvn)He4 served as primary neutror,
source in the target of an accelerator. The target was bombarded with 150-kev
deuterons. The time-of-flight determination was carried out electronically
by measuring the time integrals between the pulses in the detector. The
deuteron impulses were obtained by modulation; i.e., by means of a sinusidal
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Measurement of Spectra and the Average Neutron S105616010381031021033
Number in the Fission of U235 and U238 by B006/BO14
14.3-Mev Neutrons
electric field (f - ale/sec); the pulses of the '14-3-Mev neutrons lasted
3mtksec and had a frequency of 4 Mo/sec. On the average, 4 neutrons were ob-
tainedf~r:pulse. Two fission chambers were used (with U235 (90 per cent) and
U238 (natural isotope compositlor)); the chambers were filled with a mixture
of argon and CO2-gas (10 per cent) at 760 torr. A tolan crystal (diameter
60 um., thickj~jeps 25 mm with a photomultiplier of the type FEU-33 served as
neutron detector, The efficiency of the detector was determined according to
Hardy. Fig. 2 shows the efficiency as a function of the energy of three
threshold energies: 0.2, 0.25, and 0-3 Mev. The electronic apparatus used to
measure the pulse distribution in the detector with respect to time is de-
scribed in detail. Fig- 3 illustrates a block schemej Fig. 4 a recorded pulse
versus time diagram. Fig. 5 shows the time distribution of the pulses re-
corded with the measurement of the neutron spectrum of the U238 fission.
Besides neutrons and g--rays of the fission the following were also recordeds
14-Mev primary neutrons, neutrons, and r-qxianta due to interaction between
primary neutrons and parts of the apparatus, radiations of the activated
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~, 2-4orl'
Measurement of 'Spectra azid the Averr-,qt; Neutron S/'056/60/038/03/02/033
Number in the Fission of U235 and U238 by B006/BO14
14-3-PIOV Neutrons
substances, neutronst and C-quanta due to primary neutron scattering, and
2-5-Mev neutrons from the accelerator. Details and accuracy of the "Separation"
of the measured values from the background are discussed. The neutron spectra
of U235 and U238 fission are shown in Figs- 7a and 7b. All curves show a
similar course; a steep ascent, a peakq and an even descent. Figs. Oa and 8b
show the diagrams made for the analysis of the spectra in the coordinates
ln (F(E)/E) and E p. The spectra may be satisfactorily represented by
QXP 1(7~-W/Tf ) -
E 2 UvE
F(E) -o( exp (-E/T) + (I - cK) (-E/Tf) sh -T
pr ;;~-f-- --r f
The analytical results are listed in Table 1~ The following parameter values
are indicated: for U 2351 Tf = (1,o6Vw*,1v.3-)-PIev; T = (0-37 � 0.04) Nev;
0((fraction of evaporated neutrons) = (0~16 + 0.02)%-, for U238,
Tf - (1.16 + 0,03) Nev; T = (0-40 -+ 0.04) Mev; C( (0.21 + 0.02)~C The average
number of neutrons emitted in the fi Iss4.on'v7: 4~17 0-30 (U 235) and
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Measurement of Spectra and the Average Neutron S/056/60/038/03/02/033
Number in the Fission of U 235 and U 238 by B006/BO14
14-3-Mev Neutrons
4.28 + 0.30 (U 238), the ratio ~(U2311)/V (U135) - 1-03 � 0-03. The following
data were obtained: U 235: d~/dE n = 0.112 + 0.011 and U238-. dV/dEn =
0.115 � 0.011; (E n - neutron energy)* In conclusiong the authors thank
Yu. Ya. Glazunov, A,--N~ Maslov. N. I, Nemudrov, V. A. Parshina, A. I~ Re-
~hetov, V. S. Khorkhordin, And,,Ir. N Is:~Shikin for ht-vinC participated in the
measurements and for their Koma-rova for,'Oonputer caldula-t
tions. Mention is also made of the group of V. A. Ivanov. Yu. S, Zamyatnin,
G. A. Bat', and L. P. Kudrin. There are 9 figures, 2 ',ables, and-21 ref-
erences, 12 of which are Soviet.
SUBMITTED: August 5, 1959
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AUTHORt Sirotinin, Ye. I
h3h63
S/oag/62/013/006/002/027
B102/B186
TITLEs Calculation of *the fission neutron spectra emitted at 0, 45,
and 900 angles to the direction of flight of fragments
PERIODICALs Atomnaya energiya, y. 13, no. 6, 1962, 530 - 533
TEXTi Results of measuring the U 235 fission neutron spectra at 0, 45, and
900 were published in "Atomnaya energiyall 9, no. 6, 449, 1960 and in Zh.
eksperim. i teor. fiz., 38, 1657, 1960.. In the first-mentioned paper the
spectra also were calculated but without taking account of the fragment
excitation. Here'these spectra are again calculated and the fragment ex-
citation energy distribution is taken into account according to Terrell
(Phys. Rev. 113, 527, 1959). The neutron spectrum is
P-(E,9,Tf) J, where W(E-,Q Tf) is th~e neutron'
W a.m.'
spectrum in the fragment system, 0 is the neutron emission angle in the
-f-E case -f-W
lab system, E - E+w-2YwE coag, cos 9
a.m.
;E wE2f`wT cos 0
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Calculation of the fission.,., 31021Bi86
D(~ Qc.M.)
~E/i:; the subscript Windicates that the neutron-emittent
D(E'rd) - I
fragment has a kinetic energy of w per nucleon., After averaging over the
temperature distribution of the residual fragment nuclei and separating
the light from the heavy fragment component contribution, the spectrum
of neutrons emitted at 9 can ;be written as (E,9) +'k (E,9),
21: W,
VIhere4 (E,0) +A;(Er,(R-Q)] , 00,< 9