The new design and validation of an epithermal neutron flux detector using 71Ga(n, γ)72Ga reaction for BNCT

The epithermal neutron (0.5 eV-10 keV) flux is an essential characteristic for the boron neutron capture therapy (BNCT) neutron beam. The epithermal neutron flux measurement of a BNCT neutron beam is always a critical issue to its quality assessment and radiation dose evaluation. In this work, a cylindrical activation detector using Ga-71(n, gamma)Ga-72 reaction is designed by Monte Carlo simulations to determine the epithermal neutron flux of the BNCT neutron beam. In the detector, the activation material, i.e., gallium nitride (GaN) wafer, is positioned in the geometrical center of a high-density polyethylene (HDPE) cylinder covered with cadmium (Cd) foil. On completion of the design, the performance of the detector is validated by Monte Carlo simulations using reactor- and accelerator-based BNCT neutron beams. It is concluded from the performance validation results that the detector can accurately determine the epithermal neutron flux of the BNCT neutron beam. The designed epithermal neutron flux detector will be efficiently applicable to characterize the field of the BNCT neutron beam.