In the present work we briefly describe the architecture of a photo-detection module, designed in the framework of the INSERT (INtegrated SPECT/MRI for Enhanced Stratification in Radio-chemoTherapy) project, supported by the European Community. We focus on two main elements of the module: the SiPM photo-detector unit and the multi-channel ASIC. These two components have been investigated with dedicated and independent setups to assess preliminary performance of INSERT architecture. In details, we designed a 25.30 mm x 25.85 mm tile, comprising 9 pixels, each one with an 8 mm x 8mm active area. We developed an Anger camera to characterize the tile coupled to a CsI:Tl scintillator (6 mm thick). We measured an average spatial resolution (FWHM) of 2 mm in the central region of the Field of View and a 15.3% energy resolution using a Co-57 source (122 keV), when the tile is cooled down to 0 degrees C to reduce the impact of the dark count rate. Furthermore, we developed ANGUS, a 36-channels 0.35 mu m CMOS technology ASIC designed to cope with input capacitance up to 5 nF, typical of large area SiPM pixels. The spectroscopic capability of single readout channels were evaluated by coupling an 8 mm x 8 mm pixel with a cylindrical CsI:Tl scintillator (8 mm diameter, 10 mm thickness). Energy resolution at room temperature provided values between 13% and 13.5% (FWHM) at the 122 keV line for the nine pixels

In this paper, we present a silicon photomultiplier (SiPM)-based photodetector module designed to readout large cerium-doped lanthanum bromide (LaBr 3 :Ce) scintillators (cylindrical 1" × 1" and 2" × 2") for nuclear physics experiments. The detector prototype has a modular structure and implements a real-time stabilization of the SiPM gain to compensate for the gain drift with temperature. The SiPM module consists of an array of 5 by 6 near-ultraviolet high-density SiPMs (Fondazione Bruno Kessler, Italy), each one having an active area of 6 mm × 6 mm and 30-µm microcells. The single array is used for the 1" crystal readout, and it is assembled in a 2×2 format to read the 2" scintillator. Spectroscopic measurements were performed with both crystals. The 2" crystal was irradiated with different radioactive sources in an energy range between 122 keV and 1.3 MeV, and an energy resolution of 3.19 ± 0.01% full-width at half-maximum (FWHM) has been achieved at 662 keV. The result is very close to the 3.07 ± 0.03% FWHM measured with Super Bialkali photomultiplier tube (PMT) (Hamamatsu R6233-100) at the same energy with the same 2" crystal. In the framework of the comparison between SiPM and PMT for LaBr 3 :Ce readout, we provide an analysis of the energy resolution contributions based on the measurements performed with the developed gamma-ray detection system.

FBK) (Trento, Italy) has recently introduced High Density (HD) and Ultra High-Density (UHD) SiPMs, featuring very small micro-cell pitch. The high cell density is a very important factor to improve the linearity of the SiPM in high-dynamic-range applications, such as the scintillation light readout in high-energy gamma-ray spectroscopy and in prompt gamma imaging for proton therapy. The energy resolution at high energies is a trade-off between the excess noise factor caused by the non-linearity of the SiPM and the photon detection efficiency of the detector. To study these effects, we developed a new setup that simulates the LYSO light emission in response to gamma photons up to 30 MeV, using a pulsed light source. We measured the non-linearity and energy resolution vs. energy of the FBK RGB-HD e RGB-UHD SiPM technologies. We considered five different cell sizes, ranging from 10 µm up to 25 µm. With the UHD technology we were able to observe a remarkable reduction of the SiPM non-linearity, less than 5% at 5 MeV with 10 µm cells, which should be compared to a non-linearity of 50% with 25 µm-cell HD-SiPMs. With the same setup, we also measured the different components of the energy resolution (intrinsic, statistical, detector and electronic noise) vs. cell size, over-voltage and energy and we separated the different sources of excess noise factor. K: Gamma detectors (scintillators, CZT, HPG, HgI etc); Photon detectors for UV, visible and IR photons (solid-state); Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA)