Characterisation and Monte Carlo validation of a compact AmBe neutron irradiation facility providing fast and thermal neutron fields for detector development

Abstract

We report the design, commissioning and benchmarking of a compact AmBe-based neutron irradiation facility capable of providing both fast and thermal neutron dominated fields through multiple detector positions within a moderator assembly. Detailed radiation transport simulations using the FLUKA Monte Carlo code were performed to model the radiation environment at different detector positions. The inclusion of a single-crystal CVD diamond neutron detector in the simulations enabled direct comparison with experimental measurements, providing confidence the radiation fields are well understood. The simulations also provided a detailed breakdown of energy deposition mechanisms in the diamond sensors, including nuclear recoil, neutron capture reactions and secondary proton production from surrounding materials, highlighting the influence of detector housing materials on the local radiation environment and detector response. The facility provides a practical and accessible platform for neutron detector development and benchmarking in typical university laboratories, with dose rates outside the facility below typical natural background levels.