LET distributions from CR-39 plates on Space Shuttle missions STS-84 and STS-91 and a comparison of the results of the CR-39 plates with those of RRMD-II and RRMD-III telescopes

H. Tawara, T. Doke, T. Hayashi, J. Kikuchi, A. Kyan, S. Nagaoka, T. Nakano, S. Takahashi, K. Terasawa, E. Yoshihira

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19 Citations (Scopus)

Abstract

The LET distributions during the Space Shuttle missions STS-84 (altitude 270-412 km, average 375 km; inclination angle, 51.6°) and STS-91 (altitude 328-397 km, average 373 km; inclination angle, 51.6°) were measured using CR-39 plastic nuclear track detectors. A correction for the dip-angle dependence of the track-formation sensitivity of the CR-39 plates was applied to the data analysis. The absorbed doses and the dose equivalents around RRMD Detector Units, estimated from the LET distributions in the LET region of 4-200 keV/μm, fluctuated with standard deviations of ±21% to ±35% in both flight experiments. The LET distributions obtained from the CR-39 plates agreed well with that obtained from RRMD-II in STS-91. However, the particle fluxes obtained from RRMD-III in STS-84 and STS-91 were two or three times higher than those obtained from RRMD-II and the CR-39 plates. It was concluded that the LET distributions obtained from RRMD-II and the CR-39 plates in the present flight experiments did not include the contribution of target-fragmented secondary heavy particles produced by low-LET particles, such as relativistic or semi-relativistic protons and helium ions, whereas RRMD-III was able to detect these secondary particles because of its low triggering level.

Original languageEnglish
Pages (from-to)119-126
Number of pages8
JournalRadiation Measurements
Volume35
Issue number2
DOIs
Publication statusPublished - 2002 Jan 1

ASJC Scopus subject areas

  • Radiation
  • Instrumentation

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