Measuring the Migdal effect in semiconductors for dark matter detection

TL;DR

This paper extends theoretical calculations of the Migdal effect to neutron-nucleus scattering in silicon, proposing an experimental approach to measure it and validate its role in dark matter detection.

Contribution

It provides the first detailed calculation of the Migdal effect for neutron scattering in silicon and suggests an experimental setup for its measurement.

Findings

Identified kinematic regimes suitable for neutron calibration of the Migdal effect.

Proposed an experimental strategy using cryogenic silicon detectors at Fermilab.

Demonstrated the feasibility of measuring the Migdal effect with existing neutron sources.

Abstract

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 viable neutron calibration schemes. We then apply this framework to propose an experimental strategy to measure the Migdal effect in cryogenic silicon detectors using an upgrade to the NEXUS facility at Fermilab.