Energy loss in low energy nuclear recoils in dark matter detector materials

TL;DR

This paper investigates how crystalline defects in detector materials affect the energy spectrum measurements of low-energy nuclear recoils, which is crucial for dark matter detection accuracy.

Contribution

It introduces molecular dynamics simulations to quantify defect-related energy storage and its impact on observed recoil spectra in dark matter detectors.

Findings

Defects store a significant portion of recoil energy.

The energy spectrum is notably altered by defect effects.

Different detector materials show varying defect impacts.

Abstract

Recent progress in phonon-mediated detectors with eV-scale nuclear recoil energy sensitivity requires an understanding of the effect of the crystalline defects on the energy spectrum expected from dark matter or neutrino coherent scattering. We have performed molecular dynamics simulations to determine the amount of energy stored in the lattice defects as a function of the recoil direction and energy. This energy can not be observed in the phonon measurement, thus affecting the observed energy spectrum compared to the underlying true recoil energy spectrum. We describe this effect for multiple commonly used detector materials and demonstrate how the predicted energy spectrum from dark matter scattering is modified.