Development of ZnO:Ga as an Ultra-Fast Alpha Particle Detector

We report on ZnO:Ga to produce a high luminosity, ultra fast alpha detector as a system component that provides associated particle imaging (API) capability to neutron generators. ZnO:Ga has been shown to be well suited as the scintillator screen of the detector. Fast luminescence is observed but its intensity and decay time is strongly dependent on the method used for dopant incorporation. We compare samples made by diffusion of Ga metal to samples doped by solid state reaction with Ga₂O₃ followed by reduction in hydrogen. The ZnO:Ga prepared with reduction of Ga₂O₃ has a strong blue photoluminescence and a fast decay of the X-ray excited luminescence. The luminosity of the material increases dramatically at cryogenic temperatures. We also present the results of an alternate low-temperature synthesis that produces luminescent particles with a more uniform size distribution.