Multi-energy neutron detector for counting thermal neutrons, high-energy neutrons, and gamma photons separately

A scintillation detector composed of two scintillators optically coupled and mounted on a single photomultiplier tube is described. The first scintillator is a /sup 6/Li-loaded glass that has high efficiency for thermal neutrons, and the second is a liquid scintillator (BC 501) that has fairly high efficiency for higher-energy neutrons. The /sup 6/Li glass scintillator emits light with a characteristic time constant of approximately 60 ns, whereas light emitted in the liquid scintillator by proton recoil from energetic neurons has a time constant of approximately 30 ns; the time constant for scintillations occurring from gamma-scattered Compton electrons in the liquid scintillator is approximately 3.7 ns. These differences in light decay time constants make this detector conducive to electronic separation of pulses generated by the three different radiations. Thermal neutrons, high-energy neutrons, and gamma radiation can be counted separately by operating this detector with a recently developed pulse-shape discriminator. Experimental data proves the principle of this dual scintillator detector for many applications.<
>