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Measurement of LET distribution and dose equivalent on board the space shuttle STS-65Space radiation dosimetry measurements have been made on board the Space Shuttle STS-65 in the Second International Microgravity Laboratory (IML-2). In these measurements, three kinds of detectors were used; one is a newly developed active detector telescope called "Real-time Radiation Monitoring Device (RRMD)" utilizing silicon semi-conductor detectors and others are conventional detectors of thermoluminescence dosimeters (TLDs) and CR-39 plastic track detectors. Using the RRMD detector, the first attempt of real-time monitoring of space radiation has been achieved successfully for a continuous period of 251.3 h, giving the temporal variations of LET distribution, particle count rates, and rates of absorbed dose and dose equivalent. The RRMD results indicate that a clear enhancement of the number of trapped particles is seen at the South Atlantic Anomaly (SAA) without clear enhancement of dose equivalent, while some daily periodic enhancements of dose equivalent due to high LET particles are seen at the lower geomagnetic cutoff regions for galactic cosmic ray particles (GCRs). Therefore, the main contribution to dose equivalent is seen to be due to GCRs in this low altitude mission (300 km). Also, the dose equivalent rates obtained by TLDs and CR-39 ranged from 146.9 to 165.2 microSv/day and the average quality factors from 1.45 to 1.57 depending on the locations and directions of detectors inside the Space-lab at this highly protected orbit for space radiation with a small inclination (28.5 degrees) and a low altitude (300 km). The LET distributions obtained by two different detectors, RRMD and CR-39, are in good agreement in the region of 15-200 keV/mm and difference of these distributions in the regions of LET < 15 keV/mm and LET > 200 keV/mm can be explained by considering characteristics of CR-39 etched track formation especially for the low LET tracks.
Document ID
20040089393
Acquisition Source
Johnson Space Center
Document Type
Reprint (Version printed in journal)
Authors
Hayashi, T.
(Advanced Research Center for Science and Engineering, Waseda University Tokyo, Japan)
Doke, T.
Kikuchi, J.
Takeuchi, R.
Hasebe, N.
Ogura, K.
Nagaoka, S.
Kato, M.
Badhwar, G. D.
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)
Distribution Limits
Public
Copyright
Other
Keywords
manned
STS-65 Shuttle Project
NASA Discipline Radiation Health
NASA Center JSC
short duration
Flight Experiment

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