Abstract: The Migdal Effect (ME) is an atomic ionization process caused by the sudden displacement of an atomic nucleus from its electron cloud due to a nuclear recoil. It has been demonstrated that the ME can dramatically improve the sensitivity of dark matter direct detection experiments to the dark matter nucleon scattering cross section below dark matter masses below a GeV. The ME, however has only recently been confirmed in a gaseous detector, and has yet to be understood and calibrated in liquid noble element and semiconductor detectors used for cutting edge direct detection experiments.
In this talk, I will discuss the atomic physics of the ME for isolated atoms and semiconductors, and demonstrate the applications to dark matter direct detection experiments. I will then cover previous work I have done on a proposed setup to measure the ME in silicon using neutrons as a proxy for dark matter particles. I will then talk about an ongoing experimental campaign to measure the ME in liquid Xe to which I have contributed calculations and ideas for the experimental design. Results from the first run will be discussed, including a non-observation of the expected Migdal signal as well as a novel multi-track recombination model that was developed.