We study a three stage dark matter and neutrino observatory based on multi-ton two-phase liquid Xe and Ar detectors with sufficiently low backgrounds to be sensitive to WIMP dark matter interaction cross sections down to 10E-47 cm^2, and to provide both identification and two independent measurements of the WIMP mass through the use of the two target elements in a 5:1 mass ratio, giving an expected similarity of event numbers. The same detection systems will also allow measurement of the pp solar neutrino spectrum, the neutrino flux and temperature from a Galactic supernova, and neutrinoless double beta decay of 136Xe to the lifetime level of 10E27 - 10E28 y corresponding to the Majorana mass predicted from current neutrino oscillation data. The proposed scheme would be operated in three stages G2, G3, G4, beginning with fiducial masses 1-ton Xe + 5-ton Ar (G2), progressing to 10-ton Xe + 50-ton Ar (G3) then, dependent on results and performance of the latter, expandable to 100-ton Xe + 500-ton Ar (G4). This method of scale-up offers the advantage of utilizing the Ar vessel and ancillary systems of one stage for the Xe detector of the succeeding stage, requiring only one new detector vessel at each stage. Simulations show the feasibility of reducing or rejecting all external and internal background levels to a level <1 events per year for each succeeding mass level, by utilizing an increasing outer thickness of target material as self-shielding. The system would, with increasing mass scale, become increasingly sensitive to annual signal modulation, the agreement of Xe and Ar results confirming the Galactic origin of the signal. Dark matter sensitivities for spin-dependent and inelastic interactions are also included, and we conclude with a discussion of possible further gains from the use of Xe/Ar mixtures.
Attenuation of vacuum ultraviolet light in pure and xenon-doped liquid argon - an approach to an assignment of the near-infrared emission from the mixture
Progress on the ALETHEIA project and a new approach to mitigate events overlap
China Institute of Atomic Energy（中国原子能科学研究院）；Peking University（北京大学）；Dark Matter Key Laboratory of Sichuan Province（四川省暗物质重点实验室）；Yalong River Hydropower Development Company, Ltd（雅砻江流域水电开发有限公司）
Pulseshape discrimination against low-energy Ar-39 beta decays in liquid argon with 4.5 tonne-years of DEAP-3600 data
DEAP-3600探测器搜索3.3吨液态氩靶上散射的暗物质粒子的闪烁信号。最大的背景来自$^{39}$ Ar β衰变，并使用脉冲形状鉴别（PSD）来抑制。我们使用了两种类型的PSD算法：的闪烁分数，它认为在一个狭窄的和宽的时间窗口周围的事件峰值的闪烁信号的分数，和对数似然比，它比较观察到的光子到达时间的信号和背景模型。我们还使用两种算法来确定在给定时间检测到的光子数：（1）简单地将每个PMT脉冲的电荷除以单个光电子的电荷，以及（2）基于闪烁脉冲形状和光检测器中的后脉冲的模型，考虑在给定时间检测到一定数量的光子的概率的可能性分析。如果光子探测时间不受探测器效应的影响，则该分数近似地执行对数似然比PSD算法。我们解释了这一结果使用的闪烁光子作为一个函数的时间时，他们被检测到的信息模型。
