Constraints on low-mass, relic dark matter candidates from a surface-operated SuperCDMS single-charge sensitive detector

Abstract

This article presents an analysis and the resulting limits on light dark matter inelastically scattering off of electrons, and on dark photon and axionlike particle absorption, using a second-generation SuperCDMS high-voltage eV-resolution detector. The 0.93 g Si detector achieved a 3 eV phonon energy resolution; for a detector bias of 100 V, this corresponds to a charge resolution of 3% of a single electron-hole pair. The energy spectrum is reported from a blind analysis with 1.2 g-days of exposure acquired in an above-ground laboratory. With charge carrier trapping and impact ionization effects incorporated into the dark matter signal models, the dark matter-electron cross section ${\overline{\ensuremath{\sigma}}}_{e}$ is constrained for dark matter masses from 0.5 to ${10}^{4}\text{ }\text{ }\mathrm{MeV}/{c}^{2}$; in the mass range from 1.2 to $50\text{ }\text{ }\mathrm{eV}/{c}^{2}$ the dark photon kinetic mixing parameter $ϵ$ and the axioelectric coupling constant ${g}_{ae}$ are constrained. The minimum 90% confidence-level upper limits within the above-mentioned mass ranges are ${\overline{\ensuremath{\sigma}}}_{e}=8.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}34}\text{ }\text{ }{\mathrm{cm}}^{2}$, $ϵ=3.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}$, and ${g}_{ae}=1.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$.