title: Effects of increased shielding on gamma-radiation levels within spacecraft.
abstract: The Shuttle Activation Monitor (SAM) experiment was flown on the Space Shuttle Columbia (STS-28) from 8-13 August, 1989 in a 57 degrees, 300 km orbit.  One objective of the SAM experiment was to determine the relative effect of different amounts of shielding on the gamma-ray backgrounds measured with similarly configured sodium iodide (NaI) and bismuth germante (BGO) detectors.  To achieve this objective twenty-four hours of data were taken with each detector in the middeck of the Shuttle on the ceiling of the airlock (a high-shielding location) as well as on the sleep station wall (a low-shielding location).  For the cosmic-ray induced background the results indicate an increased overall count rate in the 0.2 to 10 MeV energy range at the more highly shielded location, while in regions of trapped radiation the low shielding configuration gives higher rates at the low energy end of the spectrum.
authors.affiliation: Space Astronomy Laboratory, University of Florida, Gainesville 32609, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: Haskins
authors.forename: J E
authors.initials: JE
authors.lastname: McKisson
authors.forename: A G
authors.initials: AG
authors.lastname: Weisenberger
authors.forename: D W
authors.initials: DW
authors.lastname: Ely
authors.forename: T A
authors.initials: TA
authors.lastname: Ballard
authors.forename: C S
authors.initials: CS
authors.lastname: Dyer
authors.forename: P R
authors.initials: PR
authors.lastname: Truscott
authors.forename: R B
authors.initials: RB
authors.lastname: Piercey
authors.forename: A V
authors.initials: AV
authors.lastname: Ramayya
authors.forename: D C
authors.initials: DC
authors.lastname: Camp
mesh_terms: D000535:Aluminum / Q000592:standards; D001729:Bismuth; D003359:Cosmic Radiation; D005720:Gamma Rays; D006046:Gold / Q000592:standards; D009532:Nickel / Q000592:standards; D011522:Protons; D011834:Radiation Monitoring / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D011835:Radiation Protection / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D012974:Sodium Iodide; D013026:Space Flight; D018531:Spacecraft / Q000295:instrumentation / Q000592:standards*; D013819:Thermoluminescent Dosimetry
chemical_list: D011522:Protons; D006046:Gold; D009532:Nickel; D000535:Aluminum; D012974:Sodium Iodide; D001729:Bismuth