Monte Carlo simulation of a scintillation crystal read by a SiPM with GATE

Silicon photomultipliers (SiPMs) have recently emerged as a replacement for photomultiplier tubes (PMTs) for light detection in many applications, including high-energy physics and medical imaging. Recently, detailed Monte Carlo simulation of SiPMs has been implemented in GATE to quantify the impact of SiPM specifications on the linearity, energy and time resolution of a scintillation crystal read by a SiPM. In this paper, GATE simulations of a LYSO crystal coupled to a SiPM are compared to measurements. The energy spectra of the 241Am and 22Na radioactive sources are found to agree with less than 2% difference. The linearity of the SiPM response is duly affected by the SiPM saturation and, as seen above 511 keV with our configuration, it is slightly enhanced by the generation of crosstalk. Furthermore, with an over-voltage close to that recommended by the manufacturer, all sources of SiPM noise contribute about equally to the degradation of the energy resolution at low energies, which is downgraded by more than 15% at 60 keV, but have less impact at higher energies. In addition, the GATE simulations show that crosstalk plays an important role on the time resolution of the installation.