Study of Plastic Scintillators for Fast Neutron Measurements and the Potential Application to Neutron Cameras

Abstract

In this research, we measured pulse spectra of fast neutrons in an energy range from 1 to 7 MeV by using plastic scintillators. The fast neutrons emitted by spontaneous fission decays of a 5-mu Ci (252)Cf isotope, whose mean energy was similar to 2.1 MeV, were used for the measurements of the energy-dependent pulse spectra of the fast neutrons. The neutron energies were determined by using a time-of-flight method. The gamma rays, emitted together with fission neutrons, were eliminated by applying a proper cut in the time-of-flight spectrum. Monte-Carlo simulations based on a GEANT4 program were performed to predict the neutron sensitivities and the deposit energies in the scintillators. Furthermore, we performed a feasibility study on the potential application of the plastic scintillators to the measurement of neutron tracks for searching for special nuclear materials (SNM).