Precise predictions and new insights for atomic ionisation from the Migdal effect

Abstract

The scattering of neutral particles by an atomic nucleus can lead to electronic ionisation and excitation through a process known as the Migdal effect. We revisit and improve upon previous calculations of the Migdal effect, using the Dirac-Hartree-Fock method to calculate the atomic wavefunctions. Our methods do not rely on the use of the dipole approximation, allowing us to present robust results for higher nuclear recoil velocities than was previously possible. Our calculations provide the theoretical foundations for future measurements of the Migdal effect using neutron sources, and searches for dark matter in direct detection experiments. We show that multiple ionisation must be taken into account in experiments with fast neutrons, and derive the semi-inclusive probability for processes that yield a hard electron above a defined energy threshold. We present results for the noble elements up to and including xenon, as well as carbon, fluorine, silicon and germanium. The transition probabilities from our calculations are publicly available.

19 pages, 12 figures; v2: journal version

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• Spin-dependent sub-GeV Inelastic Dark Matter-electron scattering and Migdal effect: (I). Velocity Independent Operator
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• On the impact of the Migdal effect in reactor CE$\nu$NS experiments
• Signatures and Detection Prospects for sub-GeV Dark Matter with Superfluid Helium
• Dark Matter (H)eats Young Planets
• Accurate electron-recoil ionization factors for dark matter direct detection in xenon, krypton and argon
• Exploring light dark matter with the Migdal effect in hydrogen-doped liquid xenon
• Probing Dark Matter Electromagnetic Properties in Direct Detection Experiments
• 3D track reconstruction of low-energy electrons in the MIGDAL low pressure optical time projection chamber
• Low-mass constraints on WIMP effective models of inelastic scattering using the Migdal effect
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• Nuclear and electron scattering by neutrinos and dark matter in condensed systems
• The Migdal effect in solid crystals and the role of non-adiabaticity
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