When a nucleus in an atom undergoes a collision, there is a small probability to inelastically excite an electron as a result of the Migdal effect. In this Letter, we present a first complete derivation of the Migdal effect from dark matter-nucleus scattering in semiconductors, which also accounts for multiphonon production. The rate can be expressed in terms of the energy loss function of the material, which we calculate with density functional theory (DFT) methods. Because of the smaller gap for electron excitations, we find that the rate for the Migdal effect is much higher in semiconductors than in atomic targets. Accounting for the Migdal effect in semiconductors can therefore significantly improve the sensitivity of experiments such as DAMIC, SENSEI and SuperCDMS to sub-GeV dark matter.
@article{arxiv.2011.09496,
title = {The Migdal effect in semiconductors},
author = {Simon Knapen and Jonathan Kozaczuk and Tongyan Lin},
journal= {arXiv preprint arXiv:2011.09496},
year = {2021}
}
Comments
5+11 pages. v2: journal version with results updated to include ion effective charge