Detector performance of the position-sensitive tissue-equivalent proportional chamber for space dosimetry onboard the international space station

We investigated the performance of a flight model of the position-sensitive tissue-equivalent proportional chamber (PS-TEPC) by irradiating with heavy-ion beams prior to launch to the International Space Station. The flight model operated stably with an effective gas gain of 1000 under a sealed gas. This gain was almost consistent with the effective gas gain under a gas flow. Energies of H, C, Si and Fe beams measured using the PS-TEPC flight model agreed well with calculations using the SRIM2008 code. Energy resolutions of 9.7% and 3.8% were obtained for the C and Fe beams, respectively. The uncertainties in dose equivalents were estimated to be better than 30% assuming both the theoretical model and best-fit function of linear energy transfer and referring to previously reported integrated dose fractions for an actual spacecraft. These features of the flight model satisfy the National Council on Radiation Protection and Measurements criteria for space dosimeters.