Neutron Slowing Down Efficiency Depending on the Proton Energy for Accelerator Based BNCT

Abstract

We have studied an accelerator-based Be(p,n) neutron source for the boron neutron capture therapy (BNCT) which can be installed near a hospital and can treat a deeply placed tumour. With higher proton energy, accelerator beam power becomes lower because efficiency for generating neutrons per proton increases. However, the generation efficiency for epithermal neutrons may decrease because the energy of the generated neutrons becomes higher. We have, therefore, calculated the proton energy dependence of the required accelerator beam power and the epithermal neutron generation efficiencies for several proton energies from 8 to 30 MeV. We found that the required beam power of the accelerator for the proton energy of 30 MeV is one third of that of 8 MeV and that the epithermal neutron generation efficiency at 8 MeV is twice as that at 30 MeV.