Calculation of neutron spectra inside spacecrafts by 3-dimensional particle and heavy ion transport code system PHITS

3次元重イオン輸送計算コードPHITSを用いた宇宙船内中性子スペクトルの計算

佐藤 達彦   ; 仁井田 浩二*; 岩瀬 宏*; 中島 宏; 山口 恭弘; Sihver, L.*

Sato, Tatsuhiko; Niita, Koji*; Iwase, Hiroshi*; Nakashima, Hiroshi; Yamaguchi, Yasuhiro; Sihver, L.*

宇宙飛行士の被ばく線量や宇宙空間で使用する半導体のエラー発生率を評価するには、宇宙船内における中性子や荷電粒子のスペクトルを評価する必要がある。したがって、われわれは、3次元輸送計算コードPHITSを用いて宇宙船内の中性子スペクトルを計算し、実験値と比較した。その結果、両者は極めてよく一致することが明らかとなった。

Radiological protection for astronauts or semiconductor devices against cosmic rays has been an essential issue in the planning of long-term space mission. Estimation of neutron spectra inside spacecrafts as well as those of HZE particles is of prime importance in the issue. We therefore calculated the spectra inside pseudo-spacecrafts using the Particle and Heavy Ion Transport code System PHITS. The agreements between the calculated neutron spectra and the corresponding experimental data were quite satisfactory. The soft error rates (SERs) of a typical SRAM cell were estimated from the spectra by employing the MBGR model.