Modeling interactions of intermediate-energy neutrons in a plastic scintillator array with Geant4

A Monte Carlo simulation of a large-area neutron time-of-flight detector, built on the Geant4 framework, has been compared with an experimental measurement of the B16→B15+n decay produced from a 55 MeV/u17C beam. The ability of the Monte Carlo simulation to reproduce the intermediate-energy neutron interactions within the detector has been explored using both the stock Geant4 physics processes and a custom neutron interaction model, menate_r. The stock Geant4 physics processes were unable to reproduce the experimental observables, while excellent agreement was obtained through the inclusion of the menate_r model within Geant4. The differences between the two approaches are shown to be related to the modeling of the neutron–carbon inelastic reactions. Additionally, the use of menate_r provided accurate reproduction of experimental signals associated with neutron scattering within the detector. These results provide validation of the Monte Carlo simulation for modeling measurements of multiple neutrons where the identification and removal of false neutron signals, due to multiple neutron scattering, are required.