10μBq/m3量级氡浓度测量及低温活性炭除氡设备研制

The dark matter experiment is one of the leading direction of particle physics, and the result will greatly deepen the human cognition of the universe. The cross section of dark matter and ordinary matter is very small, thus the dark matter searching experiments have very strict requirements on background. Radon decay is one of the most important sources of background. To satisfy the radon concentration measurement and radon removal requirement of dark matter searching experiments, “The development of 10µBq/m3 level radon concentration measurement and low temperature activated carbon radon removal equipment” project has been proposed.. In the aspect of radon concentration measurement equipment, on the basis of early radon concentration measurement equipment, the researchers will try to increase the sensitivity 25 times by means of treating the surface of stainless steel to reduce the radon emanation and improving the detecting efficiency by optimizing the geometry of the electrode and increasing the collecting high voltage. In the aspect of activated carbon radon absorption equipment, based on the industrial level of China, the researchers will fulfill the goal of enriching the radon concentration by 40 times and producing the µBq/m3 level radon by developing low background carbon and the high efficiency radon removal and radon enrichment equipment.. The output of this project will be the most sensitive radon concentration measurement equipment in China, which also reach the international advanced level and meet the requirements of dark matter searching experiment in radon concentration measurement. The radon removal equipment which developed in this project can also be used in other low background experiments and other low radon background environment. This project has very strong frontier and practical application value.

暗物质探测是粒子物理最为前沿的发展方向之一，其结果将大大影响人类对宇宙世界的认识。由于暗物质与普通物质作用截面非常小，因此暗物质探测实验对本底有极高的要求，氡衰变是其重要的本底来源。为满足暗物质实验对测氡、除氡方面的使用需求，本项目提出“10µBq/m3量级氡浓度测量及低温活性炭除氡设备研制”计划。. 在氡浓度测量研究方面，将以现有设备为基础深入开展不锈钢表面处理控制氡析出、优化电极分布增大收集电压提高探测效率等工作，将探测器灵敏度提高25倍；在活性炭氡吸附研究方面，将自主开展低本底活性炭研制、高效除氡及氡富集设备研制工作，实现40倍以上的氡富集与产生氡浓度低至µBq/m3量级的气体。. 本项目研究成果将获得国内灵敏度最高的氡浓度测量设备，与国际先进水平相当，满足暗物质实验测氡需求，本项目研制的除氡设备同样可用于其它低本底实验和低氡环境，具有很强的前沿性与实际应用价值。

中微子研究与暗物质探测是目前粒子物理领域的热门研究方面，其研究结果将可能大大改变人类对于物质世界的认知。中微子和暗物质与普通物质的作用截面极低，因此该类实验均对探测器的本底有着极高的要求。. 氡气作为一种放射性气体，广泛存在与环境之中，是粒子物理实验中最为难以控制的本底之一。能否做好探测器氡本底的控制将直接关系到实验的物理目标能否实现。本项目“10μBq/m3量级氡浓度测量及低温活性炭除氡装置研制”旨在解决低本底探测器中的氡本底问题。. 依托于本项目支持，研究人员研制出单日测量灵敏度为0.7mBq/m3的静电收集氡浓度测量装置、灵敏度为60μBq/样品的氡析出率检测装置、吸附系数达200m3/g的低温活性炭氡吸附装置以及镭附着率99.8%、氡射气系数为96.2%的固体氡源，以上研究成果均处于国际先进水平。除此之外，研究人员还研制出氡析出率为16mBq/kg的低本底活性炭，这是国内目前本底最低的活性炭。. 得益于以上多个方面的发展，本项目研究人员已完成项目既定研究目标，成功研制出测量灵敏度为μBq/m3量级的气体氡浓度测量装置以及基于活性炭的低温除氡装置。. 本项目的研究成果已应用于江门中微子实验、液氩暗物质探测实验之中并为实验的氡本底控制提供了测量数据支持，对于实验物理目标的实现具有重要意义。