title: Induced radioactivity of LDEF materials and structural components.
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.
authors.affiliation: NASA/Marshall Space Flight Center, Huntsville, AL 35812, USA.
authors.forename: B A
authors.initials: BA
authors.lastname: Harmon
authors.forename: C E
authors.initials: CE
authors.lastname: Laird
authors.forename: G J
authors.initials: GJ
authors.lastname: Fishman
authors.forename: T A
authors.initials: TA
authors.lastname: Parnell
authors.forename: D C
authors.initials: DC
authors.lastname: Camp
authors.forename: C E
authors.initials: CE
authors.lastname: Frederick
authors.forename: D L
authors.initials: DL
authors.lastname: Hurley
authors.forename: D J
authors.initials: DJ
authors.lastname: Lindstrom
authors.forename: C E
authors.initials: CE
authors.lastname: Moss
authors.forename: R C
authors.initials: RC
authors.lastname: Reedy
authors.forename: J H
authors.initials: JH
authors.lastname: Reeves
authors.forename: A R
authors.initials: AR
authors.lastname: Smith
authors.forename: W G
authors.initials: WG
authors.lastname: Winn
authors.forename: E V
authors.initials: EV
authors.lastname: Benton
mesh_terms: D000535:Aluminum / Q000528:radiation effects; D016880:Anisotropy; D001608:Beryllium; D016208:Databases, Factual; D005118:Extraterrestrial Environment; D019216:Metals, Heavy; D009501:Neutron Activation Analysis; D009502:Neutrons; D011522:Protons; D011851:Radioactivity; D011868:Radioisotopes; D012106:Research; D019445:Solar Activity; D013026:Space Flight / Q000295:instrumentation*; D018531:Spacecraft / Q000295:instrumentation*; D013051:Spectrometry, Gamma / Q000379:methods
chemical_list: D019216:Metals, Heavy; D011522:Protons; D011868:Radioisotopes; D000535:Aluminum; D001608:Beryllium