Measurements of fast neutron scattering in plastic scintillator with energies from 20 to 200 MeV

Abstract

Scattering of neutrons with energies ranging from 20 to 200 MeV was observed in an organic plastic scintillator array as a test for accuracy of simulation by two GEANT4-based models. The experiment was conducted at the LANSCE WNR facility at Los Alamos National Laboratory using a collimated neutron beam of well-defined energy and trajectory impinging on 16 BC-408 plastic scintillator detectors arranged in a horizontal array 2 detectors tall and 8 deep. Results from neutron scattering observations include hit-multiplicity distributions, beam attenuation depth, crosstalk events, scattering angle, attenuation depth between hits, and dark-scattering of neutrons from carbon nuclei, all as a function of the incident neutron energy. Measurement results are compared with predictions from two GEANT4-based Monte Carlo simulations, and agreement varies considerably over neutron energy, becoming poor at higher energies, pointing to needed improvement in simulation of neutrons in plastic scintillator.