Impact of dark counts in low-light level silicon photomultiplier multi-readout applications

The Silicon Photomultiplier (SiPM) generates noise due to thermal excitation, producing dark counts. This may be a critical performance drawback of the SiPM for low light level applications, despite its otherwise promising features such as high internal gain and quantum efficiency, low power consumption and insensitivity to magnetic fields. The dark count rate is highly dependent on temperature and bias voltage, increasing with both. Dark count pulses are similar to single photon interactions and introduce complex challenges in low light level measurements. In applications where the pulse integration time is dependent on the decay time of a slow scintillation counter, the longer the signal integration the higher the probability of dark counts during the integration period, and this can be critical for detecting very low number of photons in that period. For higher light levels, the effects of dark counts can be reduced by setting an appropriate threshold. This work presents Monte Carlo simulation techniques to evaluate the impact of dark counts into position detection algorithms, in low light level imaging applications where multiple SiPMs are used to detect position of interaction.