High-Resolution Cross-Section Measurements for Production of the 0.478-MeV Gamma Ray from the {sup 9}Be(n,x{gamma}){sup 7}Li Reaction for Neutron Energies Between 12 and 200 MeV with Insight into the {sup 10}Be Level Scheme
- Los Alamos National Laboratory (United States)
Because of the low-energy threshold and relatively large cross section of the {sup 9}Be(n,2n) reaction, beryllium is a very attractive neutron multiplier for some fast-neutron systems, such as those used in the production of fusion energy. But, tritium is also produced when beryllium is irradiated with 14-MeV neutrons emitted from the fusion of deuterium and tritium ions. Among the two exit channels of the {sup 9}Be(n,t){sup 7}Li reaction of {approx}14-MeV incident-neutron energy, the {sup 9}Be(n,t{sub 1}{gamma}){sup 7}Li channel also emits a 0.478-MeV gamma ray. The purpose of the present study is to measure the cross section for the {sup 9}Be(n,t{sub 1}{gamma}){sup 7}Li reaction and also that of the more general {sup 9}Be(n,x{gamma}){sup 7}Li reaction with the production of the same 0.478-MeV gamma ray for incident-neutron energies from the 12-MeV threshold to 200 MeV. Because the {sup 7}Li levels excited above 0.478 MeV are unstable against particle emission, the study of the {sup 9}Be(n,t{sub 1}{gamma}){sup 7}Li reaction gives direct access to the cross section for the formation of {sup 7}Li* in its 0.478-MeV excited state. The few previous experimental data for this reaction are restricted to incident-neutron energies of {approx}14 MeV with large discrepancies between the results. The present data are obtained with a BeO sample, using the pulsed source of high-energy neutrons of the Weapons Neutron Research Facility (WNR) at the Los Alamos Neutron Science Center (LANSCE). The 478-keV gamma rays emitted in {sup 9}Be(n,x{gamma}){sup 7}Li reactions are detected with two high-resolution Ge detectors. The data thus obtained are presented and compared with previous data on the {sup 9}Be(n,t{sub 1}{gamma}){sup 7}Li and the {sup 9}Be(n,t){sup 7}Li reactions. Examination of the present data also provides insight into the {sup 10}Be level scheme.
- OSTI ID:
- 20804767
- Journal Information:
- Nuclear Science and Engineering, Vol. 140, Issue 3; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); ISSN 0029-5639
- Country of Publication:
- United States
- Language:
- English
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