Photoelectric absorption cross section of silicon near the band gap from room temperature to sub-Kelvin temperature

TL;DR

This paper presents direct measurements of silicon's photoelectric absorption cross section near the band gap at cryogenic temperatures, crucial for dark matter detection sensitivity, resolving previous data discrepancies.

Contribution

It introduces a novel technique for direct low-temperature measurement of silicon's absorption cross section near the band gap, addressing prior data inconsistencies.

Findings

Measured cross section at cryogenic temperatures near the band gap.

Resolved discrepancies in previous high-temperature data.

Provides data critical for dark matter detector design.

Abstract

The use of cryogenic silicon as a detector medium for dark matter searches is gaining popularity. Many of these searches are highly dependent on the value of the photoelectric absorption cross section of silicon at low temperatures, particularly near the silicon band gap energy, where the searches are most sensitive to low mass dark matter candidates. While such cross section data has been lacking from the literature, previous dark matter search experiments have attempted to estimate this parameter by extrapolating it from higher temperature data. However, discrepancies in the high temperature data have led to order-of-magnitude differences in the extrapolations. In this paper, we resolve these discrepancies by using a novel technique to make a direct, low temperature measurement of the photoelectric absorption cross section of silicon at energies near the band gap.