Measurements of the linear energy transfer spectra on the Mir orbital station and comparison with radiation transport models

A tissue equivalent proportional counter designed to measure the linear energy transfer spectra (LET) in the range 0.2-1250 keV/μm was flown in the Kvant module on the MIR orbital station during September 1994. The spacecraft was in a 51.65o inclination, elliptical (390 x 402 km) orbit. This is nearly the lower limit of its flight altitude. The total absorbed dose rate measured was 411.3 ± 4.41 μGy/day with an average quality factor of 2.44. The galactic cosmic radiation (GCR) dose rate was 133.6 μGy/day with a quality factor of 3.35. The trapped radiation belt dose was 277.7 μGy/day with an average quality factor of 1.94. The peak rate through the South Atlantic Anomaly was ∼ 12 μGy/min and nearly constant from one pass to another. A detailed comparison of the measured LET spectra has been made with radiation transport models. The GCR results are in good agreement with model calculations; however, this is not the case for radiation belt particles and again points to the need for improving the AP8 omni-directional trapped proton models. (author)