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

TL;DR

This paper details the design, simulation, and validation of a compact AmBe neutron source for detector testing, offering both fast and thermal neutron fields suitable for university labs.

Contribution

It introduces a novel, well-characterized neutron irradiation facility with validated Monte Carlo simulations and experimental measurements for detector development.

Findings

Simulations closely match experimental measurements of neutron fields.

The facility provides low-background neutron irradiation suitable for detector testing.

Energy deposition mechanisms in diamond detectors are comprehensively modeled.

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.