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Absorbed dose measurements on LDEF and comparisons with predictionsThe radiation environment on LDEF was monitored by cumulative absorbed dose measurements made with TLDs at different locations and shielding depths. The TLDs were included in four experiments: A0015(a) Biostack, P0004 Seeds in Space and P0006 Linear Energy Transfer Spectrum Measurements at the trailing edge (west side) of the satellite; M0004 Fiber Optics Data Link at the leading edge (east side); and A0015(b) Biostack at the Earth side. The shielding depths varied between 0.48 and 15.4 g/cm2, Al equivalent. Both the directional dependence of trapped protons incident on the satellite and the shielding thickness were reflected in absorbed dose values. The trapped proton anisotropy was measured by TLDs at the east and west sides of LDEF. At the east side doses ranged from 2.10 to 2.58 Gy under shielding of 2.90 to 1.37 g/cm2 (M0004) while on the west side doses ranged from 2.66 to 6.48 Gy under shielding of 15.4 to 0.48 g/cm2 (P0006). The west side doses were more than a factor of two higher, where the vertical shielding thicknesses to space were equal. Other west side doses of 3.04 to 4.49 Gy under shielding of 11.7 to 3.85 g/cm2 (A0015(a)) and 2.91 to 6.64 Gy under shielding of 11.1 to 0.48 g/cm2 (P0004) generally agreed with the P0006 results. The Earth side doses of 2.41 to 3.93 Gy under shielding of 10.0 to 1.66 g cm2 (A0015(b)) were intermediate between the east side and west side doses. Calculations utilizing a model of trapped proton spectra were performed by Watts et al. (1993) and comparisons of dose measurement and calculations may be found in a companion paper (Armstrong et al., 1996).
Document ID
20040089398
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Benton, E. V.
(University of San Francisco CA 94117-1080, United States)
Frank, A. L.
Benton, E. R.
Armstrong, T. W.
Colborn, B. L.
Date Acquired
August 21, 2013
Publication Date
November 1, 1996
Publication Information
Publication: Radiation measurements
Volume: 26
Issue: 6
ISSN: 1350-4487
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAG8-168
CONTRACT_GRANT: NAG8-282
CONTRACT_GRANT: NAGW-4154
Distribution Limits
Public
Copyright
Other
Keywords
Flight Experiment
long duration
unmanned
LDEF Project
NASA Discipline Radiation Health
Non-NASA Center

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