The multi-purpose Particle and Heavy Ion Transport code System PHITS

A multi-purpose Particle and Heavy Ion Transport code System PHITS was recently developed[1] based on the NMTC/JAM, a branch of the ORNL code NMTC with newly evaluated cross sections and additional models, and the MCNP4C. In PHITS code, transport calculations for various particles in wide energy range are supported as follows; neutron 1E-5 eV to 200 GeV, proton, meson and baryon 0 to 200 GeV, nucleus 0 to 3 GeV/nucleon, and photon and electron 1 keV to 1 GeV. Concerning the heavy ion transport[2], PHITS uses the JAERI Quantum Molecular Dynamics JQMD[3] and Generalized Evaporation Model GEM[4] for nucleus-nucleus collisions, the Shen model for nucleus-nucleus total reaction cross sections, and the SPAR model for dE/dx. In shielding considerations for high-energy heavy ions, secondary neutrons play an important role because of high production rates and their large penetration ability. We performed systematic comparisons with experimental data[5, 6] for energy spectra of secondary neutrons produced in high-energy heavy ion reactions with different types and thicknesses of targets. We obtained very good agreement in many cases and in some cases the calculated results represent the experimental data at least within a factor of two[2]. The next important subject on the safety design for heavy ion facilities is the evalulation of induced radioactivity in the accelerator components and shielding materials. Results of the PHITS calculation for different projectiles and different targets and depths reproduce in general the measured residual radioactivities within a factor of two, except for light target nuclei cases[7]. Recently the PHITS code was installed at GSI and calculations have been started for various projects. In biophysics, secondary neutron fluences by the high-energy heavy ion reactions of 200 A MeV C on thick water and 1000 A MeV U on thick C and Fe targets were measured[8] and these were compared with PHITS calculations. In radiation protection, PHITS calculations were compared to a shielding experiment[9] performed with 400 MeV/u C beams in CAVE-A (Fig. 1). For the GSI future project, PHITS calculations are used to support the design of the Super-FRS facility, aiming at a realistic estimate of the radiation damage of magnet and coil parts. We are still developing the PHITS code by better parameterizations in the JQMD model, improvement of the models used for calculation of reaction cross sections and dE/dx, and adding routines for calculating elastic scattering of heavy ions, dose, and track average LET distributions, in order to adapt the PHITS code to a wide field of applications such as space research, material sciences, or medical applications. This is a collaboration work between Chalmers (Sweden), RIST and JAERI (Japan), and GSI. 0 50