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.
The LET distributions during the Space Shuttle missions STS-84 (altitude 270-412 km, average 375 km; inclination angle, 51.6 degrees) and STS-91 (altitude 328-397 km, average 373 km; inclination angle, 51.6 degrees) 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/micrometers, 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.
Tawara
H
H
High Energy Accelerator Research Organization, Radiation Science Center, Oho 1-1, Tsukuba-shi, Ibaraki 305-0801, Japan. hiroko.tawara@kek.jp
Doke
T
T
Hayashi
T
T
Kikuchi
J
J
Kyan
A
A
Nagaoka
S
S
Nakano
T
T
Takahashi
S
S
Terasawa
K
K
Yoshihira
E
E
D003359:Cosmic Radiation; D020450:Heavy Ions; D006371:Helium; D018499:Linear Energy Transfer; D011092:Polyethylene Glycols; D011522:Protons; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000295:instrumentation*; D011835:Radiation Protection; D011874:Radiometry; D013026:Space Flight / Q000295:instrumentation*; D014893:Weightlessness
D011522:Protons; D006371:Helium; C028827:CR 39; D011092:Polyethylene Glycols