Department of Physics, University of Houston, Houston, Texas 77204, USA.
Instituto de Física, Universidade de São Paulo, São Paulo 05508-090, Brazil.
Phys Rev Lett. 2018 Aug 24;121(8):081307. doi: 10.1103/PhysRevLett.121.081307.
We present the results of a search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 20 GeV/c^{2} using a target of low-radioactivity argon with a 6786.0 kg d exposure. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso. The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully efficient at 0.1 keVee. The observed rate in the detector at 0.5 keVee is about 1.5 event/keVee/kg/d and is almost entirely accounted for by known background sources. We obtain a 90% C.L. exclusion limit above 1.8 GeV/c^{2} for the spin-independent cross section of dark matter WIMPs on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8-6 GeV/c^{2}.
我们展示了使用暴露于 6786.0 kg 的低放射性氩的目标在低于 20 GeV/c^{2} 的质量范围内搜索暗物质弱相互作用大质量粒子（WIMP）的结果。数据是使用位于 Gran Sasso 国家实验室的 DarkSide-50 仪器获得的。该分析基于电离信号，对于该信号，DarkSide-50 时间投影室在 0.1 keVee 时具有完全效率。在 0.5 keVee 的探测器中观察到的速率约为 1.5 个事件/keVee/kg/d，几乎完全由已知背景源解释。我们在 1.8 GeV/c^{2}以上获得了暗物质 WIMP 与核子的自旋独立截面的 90%置信度限制，将暗物质的排除区域扩展到了以前的 1.8-6 GeV/c^{2}范围内的限制之外。
