Development of the PHITS Code and its Application to the Optimum Shielding Design for Neutron Scattering Instruments

Abstract

The general purpose Monte Carlo Particle and Heavy Ion Transport code System (PHITS) is being developed and widely used in various research and development fields, such as nuclear technology, accelerator design, medical physics, and cosmic-ray research. Particularly for the shielding design of neutron scattering instruments at a 1-MW spallation neutron source facility in J-PARC, the PHITS code has been extensively used so far. In order to optimize the shielding design and estimate the dose correctly, we have introduced some special functions to simulate the optical and mechanical devices (supper mirror, T0 chopper), and to reduce the statistical errors of transport particles in the long beam lines (duct source). We present the overview of the PHITS code and show the simulation results of the neutron scattering instruments.