Dark Matter Search Experiment with Double Phase Xenon Detector at Kamioka Underground Laboratory

点击翻译按钮获取中文摘要

We built the detector with 0.3-liter fiducial volume and measured its basic performance. We succeeded to utilize a PTFE reflector for liquid Xenon scintillation light and have been able to distinguish nuclear recoil from electron recoil using the direct scintillation and the proportional scintillation. From 2001, we started an underground experiment using a prototype detector in Kamioka mine. The background study, the radioactivity of all the materials used for this detector, was carried out using high purity Ge detector in the mine. Low background PMTs were developed by our group. The result of the prototype detector was 1 order of magnitude worse than the current limit in the WIMP-nucleon cross section. However, the origin of the radioactive source has been identified and the background level is understood quantitatively. The expected results with a 15 kg detector in the next phase will be three orders of magnitude better than the current limit.