Speaker
Description
For optimal sensitivity to low-mass dark matter candidates experiments
like DAMIC-M employ skipper charged-coupled devices (CCDs) with detection
threshold of just a few ionization charges. Ionization signals from
small-angle Compton scatters of environmental gamma-rays - an important
component of the background in dark matter searches – must thus be
characterized down to O(10 eV) energy. Using a Am-241 gamma-ray source,
we report a precise measurement of scattering on silicon atomic shell
electrons in a skipper CCD with single-electron resolution. Notable
differences are observed between data and theoretical expectations in the
L-shell energy region (<150 eV). We also present preliminary data from a
skipper CCD exposed to low-energy neutrons (<24 keV) from a SbBe
photoneutron source, demonstrating a measurement of the nuclear recoil
ionization efficiency in Si down to few ionization charges.
