Atomic limits in the search for galactic dark matter

TL;DR

This paper revises the Lindhard model for low-energy nuclear recoils in dark matter detection, highlighting the need for a correction at very small energies to improve experimental sensitivity.

Contribution

It identifies a necessary correction to the Lindhard model at very low energies, impacting the interpretation of dark matter detection experiments.

Findings

Revised the Lindhard model for energies below 1 keV

Implications for improving detection sensitivity in dark matter experiments

Highlighted the importance of accurate quenching factor modeling

Abstract

Direct searches for low mass dark matter particles via scattering off target nuclei require detection of recoiling atoms with energies of ~1 keV or less. The amount of electronic excitation produced by such atoms is quenched relative to a recoiling electron of the same energy. The Lindhard model of this quenching, as originally formulated, remains widely used after more than 50 years. The present work shows that for very small energies, a simplifying approximation of that model must be removed. Implications for the sensitivity of direct detection experiments are discussed.