Multiple photon counting coincidence (MPCC) technique for scintillator characterisation and its application to studies of CaWO4 and ZnWO4 scintillators

We describe a new method for measurements of the scintillation characteristics of crystals. The multiple photon counting coincidence (MPCC) technique involves recording the sequence of individual photon pulses resulting from a scintillation event. The timing of the individual photons allows determination of the scintillation decay time constants. The number of photons recorded per scintillation event is proportional to the scintillation light yield. The decay time constants and the relative light yield of CaWO4 and ZnWO4 scintillators have been investigated in the temperature range 9-350 K. An important advantage of the MPCC method is the possibility to reject spurious events through off-line analysis, taking into account the entire data set of scintillation events. This procedure allows cleaning of the data set from multiple scintillation events (pile-up). The MPCC technique is an excellent complement to conventional characterisation techniques and is particularly suited for investigation of slow scintillation processes.