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

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

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.