A SiPM-Based Detection Module for 2” LaBr3:Ce Readout for Nuclear Physics Applications

We present a SiPM-based gamma-ray detection module, which allows to read large LaBr3:Ce cylindrical crystals (diameter > 1”), typically adopted in nuclear physics experiments, with spectroscopic performances similar to those achievable with PMTs. High-Density SiPM technology for Near UltraViolet and blue light detection (NUV-HD, Fondazione Bruno Kessler, Italy) were used. These SiPMs show high Photo Detection Efficiency (PDE = 45% at 380 nm) and low Dark Count Rate (DCR < 100 kHz/mm2). The photodetector prototype has a modular structure based on an array of 5 × 6 SiPMs, each one having an active area of 6 × 6 mm2 and 30 μm microcells. This array was used for 1” scintillator readout and it was assembled in 2 × 2 planar format for the 2” scintillator readout. The spectroscopic measurements presented in this work were performed with 2” × 2” LaBr3:Ce irradiated with 57-Co, 133-Ba, 137-Cs and 60-Co calibration sources. An energy resolution of 3.19 ± 0.01% was achieved at 662 keV with 2” LaBr3:Ce. The same crystal was tested with a Super Bialkali PMT (Hamamatsu R6233-100) showing a similar energy resolution of 3.07 ± 0.03% at 662 keV. Therefore, these results support the equivalence between SiPM and PMT for high-resolution spectroscopy