Dual scintillator with pulse shaping electronics as a wide-energy range neutron detector

Because of continued concern and need for improved neutron monitoring and surveillance around nuclear facilities and weapons, where the possibility of fission excursions exists, we are investigating several neutron-sensitive scintillators and combinations for development into a smaller, more compact, wide-energy neutron detector. The scintillation detector reported here is comprised of two scintillators optically coupled and mounted on a single photomultiplier tube. The first scintillator is a /sup 6/Li-loaded glass, which has a high efficiency for thermal neutrons, and the second is a plastic scintillator (BC 400), which has fairly high efficiency for higher energy neutrons. The /sup 6/Li glass scintillator emits light with a time constant of /approximately/60 ns, whereas the time constant of light emission from the plastic scintillator is /approximately/3 ns. This difference in characteristic time constants between the two scintillators is conducive to electronic separation of the pulses occurring in each scintillator. Pulse shaping and timing electronics have been combined to accomplish this, allowing the thermal neutron activity as well as the activity of the higher energy neutrons present to be counted. 1 ref., 5 figs.