Gamma rays from the interactions of reactor fast neutrons ordered by increasing gamma-ray energy

Technical Report · Mon Nov 01 04:00:00 EST 1982

OSTI ID:6555491

Moss, C E

Radioactive material handled in nuclear safeguards often emits both gamma rays and neutrons. The gamma rays emitted by the radioactive isotopes are listed in several compilations, which can be used for identification and quantitative analysis of the radioactive isotopes present. Some of the neutrons are moderated and undergo thermal capture. The capture gamma rays are also listed in several compilations that can be used for analysis. However, some of the unmoderated neutrons undergo fast reactions with both radioactive and nonradioactive target isotopes. The dominant type of reaction is usually (n,n'..gamma..). Data on gamma rays from the interaction of fast neutrons are not extensive, and the available ordered lists give only the most common elements. This report presents a table of these gamma rays in order of increasing energy for 77 elements. The present table is based primarily on data acquired at the Baghdad Nuclear Research Institute and analyzed at the I.V. Kurchatov Institute of Atomic Energy. The intensities were measured at 90/sup 0/ to the neutron beam with a Ge(Li) detector and were corrected for self-absorption in the target. In addition to the (n,n'..gamma..) reaction, the (n,p..gamma..) and (n,..cap alpha gamma..) reactions were observed on some elements with Z < 40. The fast neutron spectrum at E/sub n > 1.5 MeV used for these measurements can be approximated by exp (-0.75 E/sub n/), where E/sub n/ is the neutron energy in MeV. The relative intensities of transitions from levels above 0.5 MeV are not critically dependent on the exponent. The present table includes only the five most intense gamma rays from each element.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6555491
• Report Number(s): LA-9604-MS; ON: DE83005601
• Country of Publication: United States
• Language: English

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