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Angular distribution of gamma rays from the fission of {sup 235}U induced by 14-MeV neutrons

Conference:

Abstract

Experiments are reported which were performed to study the angular distribution of the gamma radiation following fast-neutron-induced nuclear fission. The investigations were, in particular, focussed on the influence which the angular momentum imparted to the compound nucleus by the fast neutrons has on the angular distribution of the {gamma}-rays. The fission of {sup 235}U is induced by 14-MeV-energy neutrons from the T(d, n) {alpha} reaction. The fission fragments are detected by a gas-scintillation counter filled with a mixture of Ar and Ni gases, the {gamma}-rays by 5 cm x 5 cm Nal(Tl) crystal with an energy threshold of 120 keV. The intensity of the {gamma}-rays is measured at 90 deg. and 174 deg. to the direction of fragment motion. The flight times of fission neutrons and {gamma}-rays are measured with a 20-ns overlap-type time-to-pulse height converter while the background was covered simultaneously with another converter delayed with respect to the former. The signals from both converters are analysed by a multichannel analyser with divisible memory. The flight path, which is chosen to be about 70 cm, makes it possible to separate the neutron from the gamma counts. The geometry is designed to keep the direction of the outflying fission fragments  More>>
Authors:
Jeki, L; Kluge, G; Lajtai, A [1] 
  1. Central Research Institute for Physics, Hungarian Academy of Sciences (Hungary)
Publication Date:
Dec 15, 1969
Product Type:
Conference
Report Number:
IAEA-SM-122/10
Resource Relation:
Conference: 2. IAEA symposium on physics and chemistry of fission, Vienna (Austria), 28 Jul - 1 Aug 1969; Other Information: 12 refs, 1 fig; Related Information: In: Physics and chemistry of fission. Proceedings of the second IAEA symposium, Proceedings series, 1001 pages.
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ANGULAR DISTRIBUTION; ANGULAR MOMENTUM; ANISOTROPY; COMPOUND NUCLEI; FAST NEUTRONS; FISSION; FISSION FRAGMENTS; FISSION NEUTRONS; GAMMA RADIATION; MEV RANGE 01-10; SCINTILLATION COUNTERS; THERMAL NEUTRONS; URANIUM 235
OSTI ID:
21102101
Research Organizations:
International Atomic Energy Agency, Vienna (Austria)
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
Other: ISSN 0074-1884; TRN: XA0800750112301
Submitting Site:
INIS
Size:
page(s) 561-565
Announcement Date:
Dec 12, 2008

Conference:

Citation Formats

Jeki, L, Kluge, G, and Lajtai, A. Angular distribution of gamma rays from the fission of {sup 235}U induced by 14-MeV neutrons. IAEA: N. p., 1969. Web.
Jeki, L, Kluge, G, & Lajtai, A. Angular distribution of gamma rays from the fission of {sup 235}U induced by 14-MeV neutrons. IAEA.
Jeki, L, Kluge, G, and Lajtai, A. 1969. "Angular distribution of gamma rays from the fission of {sup 235}U induced by 14-MeV neutrons." IAEA.
@misc{etde_21102101,
title = {Angular distribution of gamma rays from the fission of {sup 235}U induced by 14-MeV neutrons}
author = {Jeki, L, Kluge, G, and Lajtai, A}
abstractNote = {Experiments are reported which were performed to study the angular distribution of the gamma radiation following fast-neutron-induced nuclear fission. The investigations were, in particular, focussed on the influence which the angular momentum imparted to the compound nucleus by the fast neutrons has on the angular distribution of the {gamma}-rays. The fission of {sup 235}U is induced by 14-MeV-energy neutrons from the T(d, n) {alpha} reaction. The fission fragments are detected by a gas-scintillation counter filled with a mixture of Ar and Ni gases, the {gamma}-rays by 5 cm x 5 cm Nal(Tl) crystal with an energy threshold of 120 keV. The intensity of the {gamma}-rays is measured at 90 deg. and 174 deg. to the direction of fragment motion. The flight times of fission neutrons and {gamma}-rays are measured with a 20-ns overlap-type time-to-pulse height converter while the background was covered simultaneously with another converter delayed with respect to the former. The signals from both converters are analysed by a multichannel analyser with divisible memory. The flight path, which is chosen to be about 70 cm, makes it possible to separate the neutron from the gamma counts. The geometry is designed to keep the direction of the outflying fission fragments nearly the same as that of the incident fast neutrons. In this way the angular momenta of the fast neutrons are normal to the flight path of the fragments. The measured gamma intensities are extrapolated to 180 deg on a computer using Strutinski's formula n({theta}) {approx} 1 + B sin {theta}. On transformation of the measured data from the laboratory system to the system of fragments the anisotropy is found to be A = I(180 deg.)/I (90 deg.) = 1.33 {+-} 0.05. The main angular momentum of fission fragments is calculated from the anisotropy as 15 (h/2{pi}) units. As compared with the thermal-neutron-induced fission the present results indicate an additional contribution from the angular momentum of the compound nucleus to the anisotropy of the angular distribution attributed to the effect of the angular momentum imparted to the fission fragments by non collinear scission. (author)}
place = {IAEA}
year = {1969}
month = {Dec}
}