Aspects of GEANT4 Monte-Carlo calculations of the BC501A neutron detector

The response function of a commercial 2 in.×2 in. BC501A neutron detector has been studied through the general-purpose Monte-Carlo (MC) simulation toolkit GEANT4. For neutron energies below 8 MeV, where the dominant detection mechanism originates from the knockout protons, the results of MC calculations reproduce remarkably well the experimental pulse-height spectra. This is not the case, however, at higher neutron energies, where the contribution of heavier charged particles to the detection mechanism becomes significant. The calculated detector efficiency is also compared at three indicative energies to the experimental one via the neutron activation technique.