First Nuclear-Recoil Ionization-Yield Measurement Down to 100 eV in Silicon

Direct-detection experiments searching for dark matter-nucleus interactions or coherent elastic neutrino-nucleus scattering often use a charge-based readout and are commonly calibrated using sources interacting with the electrons of the detector. However, nuclear and electron interactions produce a different amount of charges for the same energy deposition. Therefore, the precise knowledge of the nuclear recoil ionization yield – which quantifies the amount of energy involved in generating charge carriers for a given nuclear recoil – is essential for these science measurements.

A silicon-based SuperCDMS HVeV cryogenic calorimetric detector was operated in a monochromatic neutron beam at the Triangle Universities Nuclear Laboratory (Durham, North Carolina) as part of the IMPACT (Ionization Measurement with Phonons At Cryogenic Temperatures) program. In this talk, we will present results from the first nuclear-recoil ionization yield measurement in silicon down to an energy of 100 eV.