Low-Temperature Light Detectors: Neganov-Luke Amplification and Calibration

TL;DR

This paper demonstrates how Neganov-Luke amplification significantly enhances low-temperature light detectors' sensitivity, enabling better background discrimination in dark matter searches through improved energy thresholds and calibration methods.

Contribution

It introduces a novel application of Neganov-Luke amplification in low-temperature light detectors and presents a calibration technique for precise energy measurements.

Findings

Signal-to-noise ratio improved by a factor of ~9

Energy threshold achieved at ~21 eV

Effective calibration method using LED

Abstract

The simultaneous measurement of phonons and scintillation light induced by incident particles in a scintillating crystal such as CaWO4 is a powerful technique for the active rejection of background induced by gamma's and beta's and even neutrons in direct Dark Matter searches. However, less than ~1% of the energy deposited in a CaWO4 crystal is detected as light. Thus, very sensitive light detectors are needed for an efficient event-by-event background discrimination. Due to the Neganov-Luke effect, the threshold of low-temperature light detectors based on semiconducting substrates can be improved significantly by drifting the photon-induced electron-hole pairs in an applied electric field. We present measurements with low-temperature light detectors based on this amplification mechanism. The Neganov-Luke effect makes it possible to improve the signal-to-noise ratio of our light detectors by a factor of ~9 corresponding to an energy threshold of ~21 eV. We also describe a method for an absolute energy calibration using a light-emitting diode.