Characterization of 4 × 4ch MPPC array in scintillation spectrometry

Abstract

The aim of this work is an evaluation of MPPC array characteristics in application for scintillation light readout in gamma-ray spectrometry. Hamamatsu MPPC array of 4 × 4 channels format and total area of 12 × 12 mm2 was used as a light readout device with CsI:Tl, BGO, LSO, LaBr3, NaI:Tl, CsI:Na, LaCl3, CaF2:Eu, and CdWO4 scintillators. The measurements presented in this work covered: measurements of the breakdown voltage for each channel of the MPPC array, selection of the optimum operating voltage, evaluation of the linearity range of MPPC response for each of the used crystals, measurements of the number of photoelectrons per MeV and measurements of the energy resolution for 661.6 keV γ-rays from 137Cs. The results of the energy resolution and number of photoelectrons obtained with the tested MPPC and nine scintillators were compared to those obtained for the same scintillators with XP2020Q and XP5212 PMTs. The energy resolution data for 661.6 keV γ-rays, obtained with 12 × 12 × 12 mm3 CsI:Tl, LSO and BGO scintillators coupled to the tested MPPC are equal to: 6.4%, 9.4% and 9.5%, respectively, and are close to the results obtained for the same scintillators coupled to the XP2020Q PMT (6.6%, 9.4% and 10.5%, respectively). The study showed that light readout by means of an MPPC array produces comparable or even slightly better (in the case of a proper match of the MPPC and the scintillator optical surface) results than the XP2020Q PMT readout.