In the frame of the joint experiment BRADOS-1, absorbed dose and average linear energy transfer were assessed by means of 7LiF:Mg,Ti (TLD-700) thermoluminescence detectors for different panels onboard the Russian Segment of the International Space Station in the timeframe between February and October 2001 (248 days). A technique is presented to correct the measured absorbed dose values for thermoluminescent efficiency in the radiation climate onboard the spacecraft. Average linear energy transfer is determined from the high-temperature thermoluminescence emission in the TLD-700 glowcurve and used as a parameter in the thermoluminescent-efficiency correction. Depending on the shielding distribution, the efficiency–corrected absorbed dose varies between 168(2) μGy/d in panel No. 318 (core block ceiling) and 249(4) μGy/d in panel No. 443 (starboard-side commander cabin). The experimental data are compared with model calculations using detailed shielding distributions and orbit parameters as input.
Research Containing: BRADOS
The Russian BRADOS experiment onboard the International Space Station (ISS) was aimed at developing methods in radiation dosimetry and radiobiology to improve the reliability of risk estimates for the radiation environment in low-Earth orbit. Experimental data from thermoluminescence detectors (TLDs) and solid state nuclear track detectors (SSNTDs) gathered during the BRADOS-1 (24 February–31 October 2001) mission are reviewed and convolved to obtain absorbed dose and dose equivalent from primary and secondary cosmic-ray particles. Absorbed dose rates in the ISS Russian Segment (Zvezda) ranged from 208 ± 14 to 275 ± 14 μ Gy d – 1 . Dose equivalent rates were determined to range from 438 ± 29 to 536 ± 32 μ Sv d – 1 , indicating a quality factor between 1.95 ± 0.15 and 2.11 ± 0.20 . The contribution of densely ionizing particles ( LET ⩾ 10 keV μ m – 1 ) to dose equivalent made up between 54% and 64%.
Cosmic ray detection on the ISS by a 3 axes track etch detector stack and the complementary calibration studies
The complex radiation field inside the International Space Station (ISS) as well as the dose received by its crew was studied for several years in the BRADOS ( 1 – 5 ) projects organized by the Institute for Biomedical Problems (IBMP, Moscow) with the participation of different laboratories. The results of the measurements performed during the BRADOS-5 project by a 3 axes solid state nuclear track detector (SSNTD) stack as LET spectra and dose values are presented. According to the results, no remarkable directional dependence could be observed in the radiation field. The averaged absorbed dose rate and dose equivalent rate values above ∼ 12 keV μ m – 1 were 27.0 ± 1.6 μ Gy d – 1 and 211.4 ± 14.4 μ Sv d – 1 , respectively, resulting in an averaged quality factor of 7.9 ± 0.1 .