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Induced radioactivity of LDEF materials and structural components |
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| Authors: | Harmon B A Laird C E Fishman G J Parnell T A Camp D C Frederick C E Hurley D L Lindstrom D J Moss C E Reedy R C Reeves J H Smith A R Winn W G Benton E V |
| Institution: | a ES84 NASA/Marshall Space Flight Center, Huntsville, AL 35812, USA b Physics Department, Eastern Kentucky University, Richmond, KY 40475, USA c Nuclear Chemistry Division, L-232, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA d Western Area Radiological Laboratory, Tennessee Valley Authority, Muscle Shoals, AL 35660, USA e Nuclear Science Division, Lawrence Berkeley National Laboratory, MS 72-131, 1 Cyclotron Road, Berkeley, CA 94720, USA f SN4, NASA Johnson Space Center, Houston, TX 77058, USA g Los Alamos National Laboratory, MS D-436, Los Alamos, NM 87545, USA h Battelle Memorial Institute, Pacific Northwest Laboratory, MS P8-08, Richland, WA 99352, USA i Westinghouse Savannah River Company, Savannah River Site, Aiken, SC 29808, USA j Physics Research Laboratory, University of San Francisco, San Francisco, CA 94117, U.S.A. |
| Abstract: | We present an overview of the Long Duration Exposure Facility (LDEF) induced activation measurements. The LDEF, which was gravity-gradient stabilized, was exposed to the low Earth orbit (LEO) radiation environment over a 5.8 year period. Retrieved activation samples and structural components from the spacecraft were analyzed with low and ultra-low background HPGe gamma spectrometry at several national facilities. This allowed a very sensitive measurement of long-lived radionuclides produced by proton- and neutron-induced reactions in the time-dependent, non-isotropic LEO environment. A summary of major findings from this study is given that consists of directionally dependent activation, depth profiles, thermal neutron activation, and surface beryllium-7 deposition from the upper atmosphere. We also describe a database of these measurements that has been prepared for use in testing radiation environmental models and spacecraft design. |
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