Neutronics Design of a Beam Shaping Assembly in an Accelerator-Based Neutron Source for the Boron Neutron Capture Therapy System at the University of Osaka

An accelerator-based neutron source (ABNS) for boron neutron capture therapy (BNCT) is under development at the University of Osaka, Japan. It can supply a sufficiently intense epi-thermal neutron flux of ~8 × 108 n/s/cm2 and, at the same time, enable the whole-body dose to be substantially suppressed (~0.26 Sv/irradiation) by employing a p-Li reaction as a neutron emission reaction. At present, we are designing all the equipment to be implemented in the BNCT machine. Previously, prior to the design of the real machine, we carried out mock-up experiments to demonstrate epi-thermal neutron production and check our neutronics design code system with a prototype beam shaping assembly (BSA). The series of experiments was conducted with a Dynamitron accelerator at Birmingham University, UK. Based on the experimental results, the first neutronics design of the real machine was completed. The design result was described, together with details of the neutronics design goal and design code system. Now, our p-liquid Li-based ABNS-BNCT system is planned to be constructed in the Institute of Free Electron Laser at the University of Osaka, Osaka, Japan.