We present constraints on the existence of weakly interacting massive particles (WIMPs) from a 11 kg-day 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 $>$200 eV$_{\rm 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$_{\rm ee}$. While the origin of this low-energy excess requires further investigation, our data exclude spin-independent WIMP-nucleon scattering cross sections $\sigma_{\chi-n}$ as low as $3\times 10^{-41}$ cm$^2$ for WIMPs with masses $m_{\chi}$ from 7 to 10 GeV$c^{-2}$ . These results are the strongest constraints from a silicon target on the existence of WIMPs with $m_{\chi}$$
Revised: January 6, 2021 |
Published: December 11, 2020
Citation
Aguilar-Arevalo A., D. Amidei, D. Baxter, G. Cancelo, B.A. Cervantes Vergara, A. Chavarria, and J. D'Olivo, et al. 2020.Results on low-mass weakly interacting massive particles from an 11 kg d target exposure of DAMIC at SNOLAB.Physical Review Letters 125, no. 24:Article No. 241803.PNNL-SA-155070.doi:10.1103/PhysRevLett.125.241803