Aguilar-Arevalo A, Amidei D, Baxter D, Cancelo G, Vergara B A Cervantes, Chavarria A E, D'Olivo J C, Estrada J, Favela-Perez F, Gaïor R, Guardincerri Y, Hoppe E W, Hossbach T W, Kilminster B, Lawson I, Lee S J, Letessier-Selvon A, Matalon A, Mitra P, Overman C T, Piers A, Privitera P, Ramanathan K, Da Rocha J, Sarkis Y, Settimo M, Smida R, Thomas R, Tiffenberg J, Traina M, Vilar R, Virto A L
Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico.
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA.
Phys Rev Lett. 2020 Dec 11;125(24):241803. doi: 10.1103/PhysRevLett.125.241803.
We present constraints on the existence of weakly interacting massive particles (WIMPs) from an 11 kg d target exposure of the DAMIC experiment at the SNOLAB underground laboratory. The observed energy spectrum and spatial distribution of ionization events with electron-equivalent energies >200 eV_{ee} in the DAMIC CCDs are consistent with backgrounds from natural radioactivity. An excess of ionization events is observed above the analysis threshold of 50 eV_{ee}. While the origin of this low-energy excess requires further investigation, our data exclude spin-independent WIMP-nucleon scattering cross sections σ_{χ-n} as low as 3×10^{-41} cm^{2} for WIMPs with masses m_{χ} from 7 to 10 GeV c^{-2}. These results are the strongest constraints from a silicon target on the existence of WIMPs with m_{χ}<9 GeV c^{-2} and are directly relevant to any dark matter interpretation of the excess of nuclear-recoil events observed by the CDMS silicon experiment in 2013.
我们展示了来自位于SNOLAB地下实验室的DAMIC实验11千克·天目标曝光量对弱相互作用大质量粒子（WIMP）存在的限制。在DAMIC电荷耦合器件（CCD）中观测到的电子等效能量大于200电子伏特的电离事件的能谱和空间分布与天然放射性背景一致。在50电子伏特的分析阈值之上观测到了过量的电离事件。虽然这种低能量过量的来源需要进一步研究，但我们的数据排除了质量mχ在7至10吉电子伏特·光速平方的WIMP的自旋无关WIMP-核子散射截面σχ-n低至3×10-41平方厘米的情况。这些结果是来自硅靶对mχ<9吉电子伏特·光速平方的WIMP存在的最强限制，并且与2013年CDMS硅实验观测到的核反冲事件过量的任何暗物质解释直接相关。
