Induced radioactivity of LDEF materials and structural components.
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.
Harmon
B A
BA
NASA/Marshall Space Flight Center, Huntsville, AL 35812, USA.
Laird
C E
CE
Fishman
G J
GJ
Parnell
T A
TA
Camp
D C
DC
Frederick
C E
CE
Hurley
D L
DL
Lindstrom
D J
DJ
Moss
C E
CE
Reedy
R C
RC
Reeves
J H
JH
Smith
A R
AR
Winn
W G
WG
Benton
E V
EV
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
D019216:Metals, Heavy; D011522:Protons; D011868:Radioisotopes; D000535:Aluminum; D001608:Beryllium