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Radioactivities induced in some LDEF samplesRadioactivities induced in several Long Duration Exposure Facilities (LDEF) samples were measured by low-level counting at Los Alamos and elsewhere. These radionuclides have activities similar to those observed in meteorites and lunar samples. Some trends were observed in these measurements in terms of profiles in trunnion layers and as a function of radionuclide half-life. Several existing computer codes were used to model the production by the protons trapped in the Earth's radiation belts and by the galactic cosmic rays of some of these radionuclides, Mn-54 and Co-57 in steel, Sc-46 in titanium, and Na-22 in alloys of titanium and aluminum. Production rates were also calculated for radionuclides possibly implanted in LDEF, Be-7, Be-10, and C-14. Enhanced concentrations of induced isotopes in the surfaces of trunnion sections relative to their concentrations in the center are caused by the lower-energy protons in the trapped radiation. Secondary neutrons made by high-energy trapped protons and by galactic cosmic rays produce much of the observed radioactivities, especially deep in an object. Comparisons of the observed to calculated activities of several radionuclides with different half-lives indicate that the flux of trapped protons at LDEF decreased significantly at the end of the mission.
Document ID
19930020439
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Reedy, Robert C. (Los Alamos National Lab. NM, United States)
Moss, Calvin E. (Los Alamos National Lab. NM, United States)
Bobias, S. George (Los Alamos National Lab. NM, United States)
Masarik, Jozef (Los Alamos National Lab. NM, United States)
Date Acquired
September 6, 2013
Publication Date
April 1, 1993
Publication Information
Publication: NASA. Langley Research Center, LDEF: 69 Months in Space. Part 1: Second Post-Retrieval Symposium
Subject Category
Atomic And Molecular Physics
Accession Number
93N29628
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19930020432Collected WorksLDEF: 69 Months in Space. Part 1: Second Post-Retrieval Symposium
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