用于 MeV 伽马射线测量的液氩时间投影室的低噪声 SiPM 光读出和基于 ASIC 的电荷读出
Low-Noise SiPM Light Readout and ASIC-Based Charge Readout of a Liquid Argon Time Projection Chamber for MeV Gamma-Ray Measurements
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中文总结 AI 辅助
研究开发紧凑型液氩时间投影室 NanoGRAMS 用于 MeV 伽马射线测量，通过低噪声 SiPM 光读出和基于 ASIC 的电荷读出系统，结合蒙特卡罗模拟，经钴源照射实验验证，证明其作为康普顿相机用于伽马射线成像光谱的可行性。
中文摘要 AI 辅助
我们开发了一个紧凑型液氩时间投影室（LArTPC）NanoGRAMS，作为伽马射线与反物质测量（GRAMS）的技术验证器。LArTPC 有潜力在 MeV 伽马射线波段实现具有前所未有的有效面积的康普顿相机。NanoGRAMS 的有效体积为$5.12×5.12×10$立方厘米，配备了低噪声闪烁和电荷读出系统。闪烁光由 16 个 SiPM 阵列检测，其信号由可在液氩温度下工作的低噪声跨阻放大器求和与放大。电离电子通过 3.2 毫米间距的像素读出并由 VATA - SGD ASIC 处理，由基于 FPGA 的数据采集系统提供同步。我们用$^{[60]}\mathrm{Co}$源（1173 和 1332 keV）照射探测器，成功检测到单击中击和双击中击事件。利用现象学复合模型将收集到的电荷转换为沉积能量，并通过基于 Geant4 的蒙特卡罗模拟评估探测器响应。重建能谱在 963 和 1118 keV 处显示出康普顿边缘，与预期值一致。对于双击中击事件，确定了相互作用序列，重建的反投影图像与源位置一致。这些结果证明了 NanoGRAMS 作为 MeV 伽马射线成像光谱康普顿相机的可行性。
英文摘要
We have developed a compact liquid argon time projection chamber (LArTPC), NanoGRAMS, as a technology demonstrator for the Gamma-Ray and AntiMatter Survey (GRAMS). LArTPCs have the potential to enable Compton cameras with unprecedented effective area in the MeV gamma-ray band. NanoGRAMS has an active volume of $5.12 \times 5.12 \times 10~\mathrm{cm^3}$ and is equipped with a low-noise scintillation and charge readout system. The scintillation light is detected by an array of 16 SiPMs ($6 \times 6~\mathrm{mm^2}$ each), whose signals are summed and amplified by a low-noise transimpedance amplifier operable at liquid argon temperature. Ionization electrons are read out with $3.2\,\mathrm{mm}$-pitch pixels and processed by VATA-SGD ASICs, with synchronization provided by an FPGA-based data acquisition system. We irradiated the detector with a $^{60}\mathrm{Co}$ source (1173 and $1332\,\mathrm{keV}$) and successfully detected both 1-hit and 2-hit events. The collected charge was converted to deposited energy using a phenomenological recombination model, and the detector response was evaluated with a Geant4-based Monte Carlo simulation. The reconstructed energy spectrum shows Compton edges at 963 and $1118\,keV$, consistent with the expected values. For 2-hit events, the sequence of interactions was identified, and the reconstructed back-projection image agrees with the source position. These results demonstrate the feasibility of NanoGRAMS as a Compton camera for MeV gamma-ray imaging spectroscopy.
