标题： GRBAlpha和VZLUSAT-2立方星上SiPM在轨辐射损伤超过三年的特性研究 显示英文标题

标题： Characterization of more than three years of in-orbit radiation damage of SiPMs on GRBAlpha and VZLUSAT-2 CubeSats

摘要： 硅光电倍增管（SiPM）容易受到辐射损伤的影响，这种损伤会导致暗计数率增加。 这会导致基于SiPM和闪烁体的伽马射线探测器的低能阈值上升。 尽管存在这一缺点，但由于其低工作电压、小尺寸、对低光强的线性响应以及快速响应特性，它们正成为立方星上基于闪烁体的伽马射线探测器的首选。 SiPM在新型空间任务中的日益流行使得对其在太空环境中的长期性能进行表征变得尤为重要。 在这项工作中，我们报告了由滨松公司生产的S13360-3050多像素光子计数器（MPPC）的暗计数率和低能阈值的变化情况，这些数据来自GRBAlpha和VZLUSAT-2立方星在近地轨道（LEO）长达三年的测量结果。 在此之前，尚未有对MPPC在太空中的性能进行如此长时间测量的公开报道。 GRBAlpha是一颗于2021年3月22日发射升空至550公里高度太阳同步极地轨道（SSO）的1U立方星，携带了一个基于CsI(Tl)闪烁体并通过八个MPPC读出的伽马射线探测器，并定期检测能量范围约为30-900 keV的伽马射线瞬变事件，如伽马射线暴和太阳耀斑。 VZLUSAT-2是一颗于2022年1月13日发射升空至535公里高度SSO的3U立方星，携带了包括两个类似于GRBAlpha上的伽马射线探测器在内的多个有效载荷。 我们已经通过飞行验证证明了滨松公司的S13360-3050 PE MPPC，并展示了当MPPC被2.5毫米厚的铅锑合金屏蔽时，可以在超过三年的科学任务中用于近地轨道（LEO）环境。 这表明了MPPC在未来卫星中的潜在应用价值。 显示英文摘要

摘要： Silicon photomultipliers (SiPMs) are prone to radiation damage which causes an increase of dark count rate. This leads to an increase in low-energy threshold in a gamma-ray detector combining SiPM and a scintillator. Despite this drawback, they are becoming preferred for scintillator-based gamma-ray detectors on CubeSats due to their low operation voltage, small size, linear response to low light intensity and fast response. This increasing popularity of SiPMs among new spaceborne missions makes it important to characterize their long-term performance in the space environment. In this work, we report the change of the dark count rate and low-energy threshold of S13360-3050 PE multi-pixel photon counters (MPPCs) by Hamamatsu, using measurements acquired by the GRBAlpha and VZLUSAT-2 CubeSats at low Earth orbit (LEO) spanning over three years. Such a long measurement of the performance of MPPCs in space has not been published before. GRBAlpha is a 1U CubeSat launched on March 22, 2021, to a 550 km altitude sun-synchronous polar orbit (SSO) carrying on board a gamma-ray detector based on CsI(Tl) scintillator readout by eight MPPCs and regularly detecting gamma-ray transients such as gamma-ray bursts and solar flares in the energy range of ~30-900 keV. VZLUSAT-2 is a 3U CubeSat launched on January 13, 2022 also to a 535 km altitude SSO carrying on board, among other payloads, two gamma-ray detectors similar to the one on GRBAlpha. We have flight-proven the Hamamatsu MPPCs S13360-3050 PE and demonstrated that MPPCs, shielded by 2.5 mm of PbSb alloy, can be used in LEO environment on a scientific mission lasting beyond three years. This manifests the potential of MPPCs being employed in future satellites.