Silicon photomultipliers for the HADAR imaging atmospheric Cherenkov telescope: key performance parameters relevant to HADAR experiment implementation

Abstract

Silicon photomultipliers (SiPMs) have emerged as the core photoelectric detection components in next-generation imaging atmospheric Cherenkov telescope cameras because of their high gain, compact structure, and robust immunity toward magnetic fields. Therefore, accurately characterizing the performance of SiPMs is highly critical for ensuring the overall sensitivity and energy resolution of the telescope system.However, a systematic characterization dataset for this specific SiPM under HADAR-relevant operating conditions (including batch uniformity and temperature dependence) has not been fully reported in the existing literature. To address this gap, a high-precision automated test system is developed in this study to comprehensively measure the key performance parameters of the Hamamatsu Photonics S14466 SiPM, a detector employed in experiments for high-altitude detection of astronomical radiation (HADAR). Specifically, the breakdown voltage, V bd, is derived using the inverse logarithmic derivative method, revealing a linear temperature coefficient of approximately 55 mV/°, along with a bimodal distribution attributable to different wafer batches utilized during the fabrication process. Additionally, the multi-photoelectron spectrum is analyzed to calibrate the linear correlation of the gain, G, with the overvoltage, V ov (with a slope of approximately 7.7 × 104/V). The dark count rate, with an average value of 533 kHz at 17°, follows Arrhenius behavior dominated by thermal excitation, and the mean optical crosstalk probability is 4.9%. Finally, the nonlinear response, characterized via the double pulse test, demonstrates good agreement between the measured data and pixel saturation model over a wide and dynamic range. By quantitatively comparing these measured parameters against the HADAR experimental requirements — including the NSB-induced trigger rate, bias-voltage compensation needs, and expected photoelectron yields — we establish the operational feasibility of the S14466 array for the HADAR camera. Overall, our study findings provide essential data support for optimizing the SiPM operating point, designing the temperature control system, and simulating detector performance in HADAR experiments, while also offering methodological and data references for the selection and characterization of SiPMs in similar telescopes with wide fields of view.