用于稀有事例探测实验的固氩探测器关键技术研究

暗物质直接探测和无中微子双贝塔衰变（0νββ）实验是当前物理学的重大前沿研究。这两类实验因为极低的反应截面都属于稀有事例探测，其灵敏度极大依赖于本底事例率的压制，其中氡被认为是主要的本底来源之一。在使用高纯锗探测器的暗物质直接探测和0νββ实验中，低温管路和容器中氡的析出与扩散难以克服。针对此类问题，项目组提出了利用液氮环境将氩冻结成固氩作为反符合探测器以压制本底的方案。这一方案既可以通过固氩阻止氡扩散，也可通过反符合极大地降低本底事例率，还能利用高纯锗所需的液氮环境简化固氩恒温和蒸发回流管路装置的复杂性。此外固氩探测器也可以作为主探测器开展研究。为此，本项目拟通过液氮冻结液氩为固氩，与硅光倍增电器件组成原型探测器，进行固氩发光特性及其影响因素的研究，发展包括事件甄别、粒子事件空间定位等在内的数据处理方法。研究成果将为稀有事例探测实验提供新的方法与技术，有望在相关重大物理研究中得到应用。

The detection of dark matter and neutrinoless double-beta decay (0νββ) are the major research topics related to particle physics, astrophysics and cosmology, also are the rare events experiments due to the extreme low cross section. The sensitivity of the rare events experiments greatly depends on the suppression of the background case rate, while radon is considered to be one of the main background sources. In the direct detection of dark matter and direct detection of dark matter and the neutrinoless double beta decay using high-purity germanium detector, neither the passive shielding of liquid nitrogen nor the active shielding of liquid argon can overcome the radon releasing and diffusion of pipelines and vessels in low temperature. In this project, a solution was proposed to freeze liquid argon into solid argon in a liquid nitrogen environment and make an anti-coincidence detector to suppress the background. This scheme can not only prevent the diffusion of radon by solid argon, but also greatly reduce the background case rate by anti-coincidence, and simplify the complexity of constant temperature and evaporative reflux pipeline installation of liquid argon by utilizing the low-temperature liquid nitrogen environment required for high purity germanium. In addition, solid argon detector can also be used as the main detector. Therefore, this project plans to study the influence factors of solid argon as scintillation crystal in the formation process, and carry out performance research through the combination of solid argon and silicon optoelectronic devices (SiPM) to form prototype detector, and develop data processing methods including event screening, particle event spatial positioning, etc. The research results will enrich the detection technology of argon, provide methods and techniques for background suppression in rare case detection experiments, and is expected to be applied in important and frontier physical research.