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: detector
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%.
Space radiation measurements were made on the International Space Station (ISS) with the Bulgarian Liulin-E094 instrument, which contains 4 Mobile Dosimetry Units (MDU), and the NASA ) during the time period May 11–July 26, 2001. In the time span 11–27 May 2001 four MDUs were placed at fixed locations: one unit (MDU #1) in the ISS “Unity” Node-1 and three (MDU #2–#4) units were located in the US Laboratory module. The MDTissue Equivalent Proportional Counter (TEPCU #2 and the TEPC were located in the US Laboratory module Human Research Facility (rack #1, port side). In this paper we discuss the flight observed asymmetries in different detectors on the ascending and descending parts of the ISS orbits. The differences are described by the shielding differences generated by different geometry between the predominating eastward drifting protons and the orientation and placement of the MDUs within the ISS. Shielding distributions were generated for the combined ISS and detector shielding models. The AP8MAX and AE8MAX trapped radiation models were used to compute the daily absorbed dose for the five detectors and are compared with the flight measurements. In addition, the trapped proton incident spectra inside of ISS were calculated using calibration curve of MDU obtained during the tests with protons at the Louvain-la-Neuve cyclotron facility. The energy of incident spectra maximums were analyzed against L value for the individual passes through the South Atlantic Anomaly.