PandaX实验的进展与展望

Progress and Prospect of PandaX Experiment

PandaX是位于四川的中国锦屏地下实验室(CJPL)内的,利用氙作为工作物质,探测暗物质等其它极稀有事件的大型地下粒子探测实验计划。Panda X探测器中的氙工作在气液两相的模式。通过检测液相和气相中闪烁光强的比例,实现对目标粒子包括WIMP和Axion等疑似信号的鉴别。Panda X已顺利完成了有效区体积约为120 kg氙的一期计划,目前正在运行实施有效区体积约为500 kg氙的二期计划。在WIMP质量为45 Ge V/c^2附近,探测灵敏度达2.97×10^(-45)cm^2(90%置信度),没有发现WIMP疑似信号。本工作介绍了Panda X一期和二期的进展,以及后续升级计划,其中包括升级Panda X的时间投影室至4吨,建造用于屏蔽岩石放射性本底的水屏蔽,以及^(136)Xe双贝塔衰变的研究计划等。

Panda X is a xenon-based dark matter and other rare events searching project located at China Jin Ping underground Laboratory（CJPL）, Sichuan province, China. Dual phases, liquid and gas phase of xenon are used in the detector. Particles, including Weak Interaction Massive Particles（WIMPs） or axions etc., may induce scintillating signals in both liquid（S1 signal） and gas（S2 signal） phases, and then are identified by analyzing the ratio of S1 and S2. The Panda X had completed its first stage, the 120 kg in fiducial volume, and now is running in its stage II with fiducial volume of 500 kg. The running results show that the WIMP-matter cross section detecting sensitivity of about 2.97×10^（-45） cm^2（90% C.L.） has been achieved at a WIMP mass of 44.7 Ge V/c^2,and no WIMP candidates are identified. The upgrading plan of the Panda X is discussed, which include to build a larger Time project chamber（TPC） of about 4 tons, a water tank for radiation shielding, and the plan of^（136） Xe double beta decay studies.