Factors affecting the characterization of very fast scintillators with low light output

The characterization of very fast and low light output scintillators is very challenging. We illustrate how Cerenkov radiation in the PMT window can obscure the signal from a sample. We measured the light output and timing properties of ZnO:Ga crystals (supplied by Cermet Inc. of Atlanta, GA). We confirmed the previously published result that this scintillator has an extremely fast decay time (< 1 ns). The estimated light output of this scintillator when measured with alpha particles is about 70% of BC-408 plastic scintillator light output.