Measuring the Migdal Effect in Semiconductors

The Migdal effect has received much attention from the dark matter direct detection community, in particular due to its power in setting limits on sub-GeV particle dark matter. Currently, there is no experimental confirmation of the Migdal effect through nuclear scattering using Standard Model probes. In this work, we extend existing calculations of the Migdal effect to the case of neutron-nucleus scattering, with a particular focus on neutron scattering angle distributions in silicon. We identify kinematic regimes wherein the assumptions present in current calculations of the Migdal effect hold for neutron scattering, and demonstrate that these include many viable neutron calibration schemes. We then apply this framework to propose an experimental strategy to measure the Migdal effect in cryogenic silicon detectors using the NEXUS facility at Fermilab.