A simple phoswich system

Normal phoswich detector systems use a combination of NaI(Tl) and CsI(Na) scintillators and require the application of careful pulse-shape discriminator techniques to resolve the two components in the scintillation light output which have decay constants of 250 and 630 ns respectively. These techniques provide a good anticoincidence veto efficiency for a relatively narrow range in the ratio of energy deposits in the two crystals and for a detector system whose temperature is carefully controlled. This paper describes the performance of a simple phoswich which makes use of the fast UV signal from a BaF2 crystal to provide a prompt veto signal. The performance to be expected from various combinations of a BaF2 anticoincidence crystal with other primary detectors is presented. These simulations have been verified by simple experimental tests. (orig.)