Real-time measurement system with automatic gain detection and autocalibration for silicon photomultipliers

The silicon photomultiplier (SiPM) is a semiconductor device the gain of which strongly depends on temperature. When performing precise measurements, the gain has to be kept stable without fluctuations. This paper presents a novel method that estimates the gain of the SiPM based on acquired signals. The method is implemented in FPGA architecture and extends the applicability of SiPM's gain stabilisation by bias correction. The correction is based on the function: G(V, T) = aT + bV + c (G - gain; T - temperature; V - bias voltage; a, b, c - coefficients representing SiPM model). When coefficients of the specific SiPM have been determined prior to the measurement, the system reads the temperature of the detector and calculates the appropriate bias. However, when the coefficients of the specific SiPM are unknown, the system is capable of calculating them at the time of measurement and applying the bias. This is possible due to the system's ability to automatically define the gain of the photodetector.