Monte Carlo and experimental evaluation of BC-454 for use as a multienergy neutron detector

A boron-substituted plastic scintillator has been evaluated for use as a multienergy neutron detector in the Navy RADIAC Development Program. Monte Carlo codes were run for a 1 in. diameter×1 in. long scintillator and a 2 in. diameter×2 in. long scintillator. Additional calculations were run with each scintillator encased in 2 in. of polyethylene moderator. Response curves for neutron sensitivity as a function of energy were plotted from these calculations. Results show a close approximation between the analytically modeled response and the response obtained from a commercially available multienergy neutron detector. The scintillators also were evaluated experimentally for comparison with Monte Carlo results. Each scintillator was coupled to a photomultiplier tube and subjected to neutron irradiation. Results indicate that the experimental configuration used was rejecting proton recoil events <1 MeV. This proton recoil cutoff energy resulted in an underrepresented intermediate energy region