MPPC Array in the Readout of CsI:Tl, LSO:Ce:Ca, LaBr$_{3}\!$:Ce, and BGO Scintillators

The aim of this work is to provide the characteristics of MPPC arrays with an active area of 6 × 6 mm² in gamma-ray spectrometry with CsI:Tl, LSO:Ce:Ca, LaBr₃:Ce and BGO scintillators. The chosen scintillators have significantly different decay times of the scintillation pulses and different wavelengths of emission peaks. This allowed an investigation into the dependence of MPPC readout features on the MPPC and scintillator characteristics. The study of influence of effective dead time and the number of MPPC pixels on a readout response in relation to the brightness and speed of the scintillator were performed. The measurements covered a selection of MPPC optimum operating voltage, verification of the linearity range for a given decay time of the crystals, verification of the excess noise factor for the optimal voltage and evaluation of the Photon Detection Efficiency (PDE). The results of energy resolution and non-proportionality obtained with the MPPC array readout of CsI:Tl and BGO were compared to those obtained for the same crystals with the XP2020Q PMT readout. The results show that an MPPC can be used as effectively as a PMT for gamma spectrometry measurements in the whole tested energy ranges (up to 1.3 MeV) and for many types of scintillation crystals (BGO, CsI:Tl).