Effect on Dark Matter Exclusion Limits from New Silicon Photoelectric Absorption Measurements

TL;DR

This paper highlights how recent precise measurements of silicon's photoelectric absorption cross section at cryogenic temperatures impact dark matter detection sensitivity, emphasizing the importance of accurate low-energy interaction data.

Contribution

It provides the first precise measurements of silicon's photoelectric absorption cross section at cryogenic temperatures relevant for dark matter searches.

Findings

Accurate low-energy cross section data reduces uncertainties in dark matter exclusion limits.

Cryogenic measurements significantly differ from room temperature data, affecting detection sensitivity.

Enhanced understanding of silicon's photoelectric properties improves dark matter search strategies.

Abstract

Recent breakthroughs in cryogenic silicon detector technology allow for the observation of single electron-hole pairs released via particle interactions within the target material. This implies sensitivity to energy depositions as low as the smallest band gap, which is $\sim1.2$ eV for silicon, and therefore sensitivity to eV/$c^2$-scale bosonic dark matter and to thermal dark matter at masses below 100 MeV/$c^2$. Various interaction channels that can probe the lowest currently accessible masses in direct searches are related to standard photoelectric absorption. In any of these respective dark matter signal models any uncertainty on the photoelectric absorption cross section is propagated into the resulting exclusion limit or into the significance of a potential observation. Using first-time precision measurements of the photoelectric absorption cross section in silicon recently performed at Stanford University, this article examines the importance having accurate knowledge of this parameter at low energies and cryogenic temperatures for these dark matter searches.