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 $\bar{\sigma}_{e}$ 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 $\varepsilon$ and the axioelectric coupling constant $g_{ae}$ are constrained. The minimum 90% confidence-level upper limits within the above mentioned mass ranges are $\bar{\sigma}_{e}\,=\,8.7\times10^{-34}$ cm$^{2}$, $\varepsilon\,=\,3.3\times10^{-14}$, and $g_{ae}\,=\,1.0\times10^{-9}$.
Highlights
During the past two decades, many significant constraints on weakly interacting massive particle (WIMP) dark matter (DM) for masses above 10 GeV=c2 have been published (e.g., [1,2,3,4,5,6,7,8,9,10], and references therein)
We constrain three DM candidates: (i) light DM χ, referring to thermal DM particles that inelastically scatter with electrons via a new dark sector force mediator [15,16]; (ii) dark photons V that kinetically mix with Standard Model photons [17,18,19]; and (iii) axionlike particles (ALPs) that are absorbed by an atom via the axioelectric effect [20,21,22]
Using signal models that include the contributions from charge carrier trapping and impact ionization, we report the constraints obtained from a blind analysis on χ scattering for DM masses from 0.5 to 104 MeV=c2, as well as V and ALP absorption for masses from 1.2 to 50 eV=c2
Summary
During the past two decades, many significant constraints on weakly interacting massive particle (WIMP) dark matter (DM) for masses above 10 GeV=c2 have been published (e.g., [1,2,3,4,5,6,7,8,9,10], and references therein). We constrain three DM candidates: (i) light DM χ, referring to thermal DM particles that inelastically scatter with electrons via a new dark sector force mediator [15,16]; (ii) dark photons V that kinetically mix with Standard Model photons [17,18,19]; and (iii) axionlike particles (ALPs) that are absorbed by an atom via the axioelectric effect [20,21,22] These candidates can create electron-hole (e−hþ) pairs in the phonon-mediated cryogenic silicon HVeV detector. We analyze a slightly larger above-ground exposure of 1.2 g-days of a second-generation Si HVeV
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