Characterization of TSV MPPC arrays (4×4 ch and 8×8 ch) in scintillation spectrometry

The main aim of this work was characterization of the newest MPPC arrays (with 12×12mm and 24×24mm active area) made using through silicon via (TSV) technology in gamma-ray spectrometry with five different scintillators: CsI:Tl, NaI:Tl, LSO/LYSO, BGO, LaBr3. The results of the study are compared with that obtained previously with the older sample of the 12×12mm MPPC array made as a monolithic device. TSV MPPC array with the size of 24×24mm is one of the first commercially available SiPM with so large active area and with the dead space between channels minimized to only 0.2mm. Moreover in these devices Hamamatsu introduced resistors made with a new type of material. Such a change allowed lowering of crosstalks and afterpulses. These improved TSV MPPC arrays can be commercially used for scintillation light readout of “large” crystals with diameter of 1×1inch or 2×2inch, suitable for gamma spectrometry. Such combination may allow replacement of PMTs in monitoring handheld devices. The presented studies with MPPCs were carried out in the two main experimental conditions: direct illumination of the SiPM using a LED pulser and measurements with scintillators. The first method allowed the measurements of basic parameters of MPPCs such as breakdown voltage and excess noise factor (ENF). The second method allowed the measurements of the full scintillation detector parameters, such as: optimum operating voltage, number of photoelectrons (number of fired APD cells), photon detection efficiency (PDE), linearity and energy resolution.