PNNL

Abstract

This article presents an analysis and the resulting limits on light dark matter inelastically scattering off of electrons, and on dark photon and axion-like particle absorption, using a second-generation SuperCDMS high-voltage eV-resolution detector. The 0.93 gram 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 gram-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 s¯e is constrained for dark matter masses from 0.5--10^4 MeV/c^2; in the mass range from 1.2--50 eV/c^2 the dark photon kinetic mixing parameter e and the axioelectric coupling constant gae are constrained. The minimum 90% confidence-level upper limits within the above mentioned mass ranges are s¯e=8.7×10^-34 cm^2, e=3.3×10^-14, and gae=1.0×10^-9.