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Title: 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

Abstract

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 aremore » 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.« less

Authors:
;  [1]
  1. Los Alamos National Laboratory (United States)
Publication Date:
OSTI Identifier:
20804767
Resource Type:
Journal Article
Journal Name:
Nuclear Science and Engineering
Additional Journal Information:
Journal Volume: 140; Journal 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); Journal ID: ISSN 0029-5639
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BERYLLIUM 10; BERYLLIUM 9 TARGET; BERYLLIUM OXIDES; CROSS SECTIONS; EXCITED STATES; FAST NEUTRONS; GAMMA RADIATION; GE SEMICONDUCTOR DETECTORS; KEV RANGE; LITHIUM 7; MEV RANGE; NEUTRON REACTIONS; NUCLEAR STRUCTURE; PHOTON EMISSION

Citation Formats

Nelson, R O, and Michaudon, A. 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. United States: N. p., 2002. Web.
Nelson, R O, & Michaudon, A. 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. United States.
Nelson, R O, and Michaudon, A. Fri . "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". United States.
@article{osti_20804767,
title = {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},
author = {Nelson, R O and Michaudon, A},
abstractNote = {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.},
doi = {},
url = {https://www.osti.gov/biblio/20804767}, journal = {Nuclear Science and Engineering},
issn = {0029-5639},
number = 3,
volume = 140,
place = {United States},
year = {2002},
month = {3}
}