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Neutron dosimetry in low-earth orbit using passive detectorsThis paper summarizes neutron dosimetry measurements made by the USF Physics Research Laboratory aboard US and Russian LEO spacecraft over the past 20 years using two types of passive detector. Thermal/resonance neutron detectors exploiting the 6Li(n,T) alpha reaction were used to measure neutrons of energies <1 MeV. Fission foil neutron detectors were used to measure neutrons of energies above 1 MeV. While originally analysed in terms of dose equivalent using the NCRP-38 definition of quality factor, for the purposes of this paper the measured neutron data have been reanalyzed and are presented in terms of ambient dose equivalent. Dose equivalent rate for neutrons <1 MeV ranged from 0.80 microSv/d on the low altitude, low inclination STS-41B mission to 22.0 microSv/d measured in the Shuttle's cargo bay on the highly inclined STS-51F Spacelab-2 mission. In one particular instance a detector embedded within a large hydrogenous mass on STS-61 (in the ECT experiment) measured 34.6 microSv/d. Dose equivalent rate measurements of neutrons >1 MeV ranged from 4.5 microSv/d on the low altitude STS-3 mission to 172 microSv/d on the ~6 year LDEF mission. Thermal neutrons (<0.3 eV) were observed to make a negligible contribution to neutron dose equivalent in all cases. The major fraction of neutron dose equivalent was found to be from neutrons >1 MeV and, on LDEF, neutrons >1 MeV are responsible for over 98% of the total neutron dose equivalent. Estimates of the neutron contribution to the total dose equivalent are somewhat lower than model estimates, ranging from 5.7% at a location under low shielding on LDEF to 18.4% on the highly inclined (82.3 degrees) Biocosmos-2044 mission. c2001 Elsevier Science Ltd. All rights reserved.
Document ID
20040088457
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Benton, E. R.
(Inc. P.O. Box 150788, San Rafael, CA 94915-0788, United States)
Benton, E. V.
Frank, A. L.
Date Acquired
August 21, 2013
Publication Date
June 1, 2001
Publication Information
Publication: Radiation measurements
Volume: 33
Issue: 3
ISSN: 1350-4487
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Flight Experiment
Non-NASA Center
Cosmos Project
LDEF Project
unmanned
Review, Tutorial
long duration
Review
STS Shuttle Project
manned
short duration
Mir Project
NASA Discipline Radiation Health

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