Gain stabilization and consistency correction approach for multiple SiPM-based gamma-ray detectors on GECAM

Each satellite of the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM, mission) consists of 25 SiPM-based gamma-ray detectors (GRDs). SiPM based GRD benefit from being compact in size and low bias-voltage. However, the drift of the GRD gain with temperature is a severe problem for GRD performance. An adaptive voltage supply source was designed to automatically adjust the SiPM bias voltage to compensate the temperature effects and keep the gain stable. This approach proved to be effective during both the on-ground and in-flight tests. The in-flight measured variation of the GRD gain is within 2%. To reduce the non-uniformity gain of GRDs, an iterative bias voltage adjustment approach is proposed and implemented. The gain non-uniformity is reduced from 17% to 0.6%. In this paper, the gain stabilization and consistency correction approach are presented and discussed in detail.