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Scientific Seminars

[Astro] New Channels in the Search for Dark Matter


Speaker:  Daniel Baxter, University of Chicago

Abstract:  In direct detection experiments, interpreting an observed rate as a limit on (or detection of) dark matter requires assumptions about the type of interaction. Typically, this breaks down as elastic nuclear scattering (for energies >1 keV) or electron scattering (for energies 1-50 eV). The first challenge to this conventional way of thinking came in the form of the Migdal effect, wherein a sub-threshold nuclear recoil produces some amount of detectable ionization due to coupling between the scattered nucleus and atomic system. I will demonstrate how this inelastic channel could be the dominant interaction channel for dark matter masses between 0.1-1 GeV. I will also show how, in semiconductors, this effect may be superseded by inelastic collective effects, such as plasmon resonance, which cannot be described by single particle wavefunctions. Both of these new inelastic channels have the potential to amplify the sensitivity of existing (and future) detectors to dark matter, but have large theoretical uncertainties which need to be calibrated in order to fully understand their impact.