59. Space Radiation Dosimetry Using SolidState Integrating Detectors
Hiroshi Yasuda, Masashi Takada, Kazunobu Fujitaka, Sayaka Sato1 and Tatsuto Komiyama2 (1Tohoku University, 2NASDA)
Keywords: space radiation dosimetry, solid-state detectors, HIMAC
In the early 21st century, Japanese astronauts will begin to continuously stay in the International Space Station (ISS) . Even without a severe solar-particle event (SPED, the personal dose equivalent in a ISS mission will be higher than the occupational dose limit recommended by ICRP. Thus, career dose to each astronaut must be monitored and controlled in keeping with radiological protectuon practuces. However, much uncertainty still remains on the availability of existing personal dosemeters for use in space. In the present study, responses of several solid-state passive detectors were examined at HIMAC using heavy-ion beams with energy compa rable to galactic cosmic rays. The detectors employed herein were : radiophoto-luminescent glass (RPL-glass) (SC-1, Toshiba Glass), thermoluminescent dosemeters of Mg2 SiO4:Tb (MSO-rod/ disk, Kasei-optonics), Bed:Na (UD-170A, Matsushita Electric Industrial Co Ltd.) Be0 (BeO ceramic sheet, Goodfellow), 6LiF:Mg,Ti (TLD-GOD Harshaw), 7LiF:Mg, Ti, (TLD-700, Harshaw), and plastic nuclear-track detectors (CR-39) (HARZLAS TD-1, Fukuvi Chemical Industry Inc.). Radiophotoluminescent glass and several TLDs showed differ ent dependence on LET. Glow-curve shapes of selected TLDs also changed for different particles. Strong dependence on beam incident angles was found in the track-formation sensitivity (S) of TD-1 plastic. Such systematic errors (type-B uncertainty) need to be conservatively incorporated in view of ra diological protectton.
The detectors listed above were used for spaceradiation measurements in three recent missions at the low-Earth orbit (40Okm X 51.6
) relevant to that of the ISS: the Mir Mission in 1997 the 8th Shuttle-Mir Mission (STS-89) in 1998, and the 9th Shuttle-Mir Mission (STS 91) in 1998. Different type detectors showed different dose values as gamma-ray equivalent. Based on the calibration data obtained in the ground-based experiments, spatial variations of both dose and quality in the spacecrafts were successfully evaluated by selected combinations of the solid-state detectors.
Publications:
1)Yasuda, H.: Radioisotopes. 48, 645-647, 1999.
2)Yasuda, H.: J. Nucl. Sci. Technol., 36, 1105-1107 1999.
3) Yasuda, H.: J. Health Phys. 34, 387-390, 1999.
4)Yasuda, H., Komiyama, T., and Fujitaka, K.: J. J Aerospace Environ. Med. 36, 105-112, 1999.
5)Yasuda, H. and Fujitaka, K. : Radial. Prot. Dosim. 87, 115-120 2000.
6)Yasuda, H. and Fujitaka, K.: Radiat. Prot. Dosim. 87, 203-206 2000.