暗物质地下探测的前沿技术预研2013年年度报告

Annual Report 2013 of Advanced Study for Frontier Technologies of Underground Dark Matter Detection

“暗物质地下探测的前沿技术预研”主要研究内容是综合前一阶段惰性液体探测器方案、晶体探测器方案、过热液滴探测器方案均基本按计划进行：惰性液体探测器方面,实现液氩模型探测器系统的搭建,实现低温系统、氩气液化、模型探测器系统密封与检测、TPB波长位移板镀膜、高纯氩气纯化、单相液氩发光并探测,为下一步研究、发展液氩探测技术,研究相关探测器参数,实现液氩探测器在锦屏进行地下暗物质的探测打下了基础;并将进一步研究单相液氩探测器的相关参数,研究两相探测方案;晶体探测器已利用北京大学中子束流的进行了n/gamma的相关测试,测试结果表明探测系统、方法工作正常,本底可控,并可以进一步预期使用原子能院更高（3~4个量级）强度束流测试将可达到比较好的测试结果,并实现对晶体n/gamma鉴别能力的定量测量,以确定晶体探测器方案的本底;同时我们将进行18 kg晶体模型探测器的最后组装及测试工作,研究探测器耦合介质、探测器响应、本底水平等;晶体探测技术成熟,大质量的晶体探测器在暗物质探测的截面测量方面仍有一定的优势,特别是在质子自旋相关的暗物质探测方面有显著的优势;过热液滴的气泡探测技术仍然在不断地进步中,截止目前,该课题组已发展并使用放射源测量了过热液滴探测器,实现了探测器对中子的灵敏响应、对gamma的惰性响应;研究了气泡探测器声音信号的频谱特征,设计并初步开发了信号的声频识别系统。我们将继续跟踪国际最新动向,发展相关探测、识别技术。

The topic of advanced study for frontier technologies of underground dark matter detection is aimed to comprehensive analysis of current world detectors/technologies to study and make high sensitive and low background deep underground detectors preparing for direct detection of dark matter in Galaxy, to design special detecting system for different dark matter models. Here we intend to study the options with mature liquid argon/ Xenon and crystals technologies with international cooperation, and further to study new detecting technologies. All the three detector options are going on plan in last stage： liquid argon, crystal and superheated liquid： Firstly, for the liquid argon detecting option, we are contributing to the Dark Side collaboration and improving ourselves at the same time. We are building our own liquid argon detector at IHEP to study its performance, and we already have made some achievements： the prototype detector is built, get liquid argon from gas, leakage test of the system with He and RGA, coating TPB to a Teflon plate, purification of argon gas, scintillation and detection light of liquid argon： all of these are very helpful for further study and development of liquid argon detector, next two phase stage, and even for the dark matter detection in Jinping underground laboratory. We have do the 1st stage test for the n/gamma discrimination of crystal with Peking university neutron beam, which has confirmed that the system is working well, and we can expect good results for the measurement with CIAE neutron beam which has about 3~4 magnitude higher intensity; and we will run a 18 kg crystal prototype soon at IHEP to study the coupling quantity among crystals/PMT, the background and the performance of the system. Crystal is a mature technology which can be easily used with high quality in dark matter measurements, especially in the proton spin mode which has a significant advantage. Superheated droplets bubble detection technology is still in progress , until now, our group has measured the detector with radioactive sources and achieved a good sensitivity to neutron not gamma; studied the spectral characteristics of the sound signal of the detector, designed and realized an audio recognition system. We will continue to follow the latest international trends, and develop further technologies.