Long-term temporal stability of the DarkSide-50 dark matter detector

TL;DR

This paper evaluates the long-term stability of the DarkSide-50 dark matter detector over nearly three years, emphasizing its consistent electroluminescence performance and stable background event rate, crucial for detecting dark matter signals.

Contribution

It provides the first detailed analysis of the detector's stability over multiple years, demonstrating reliable performance for dark matter searches.

Findings

Electroluminescence yield stability better than 0.5%

Observed event rate consistent with background predictions

Detector performance maintained over almost three years

Abstract

The stability of a dark matter detector on the timescale of a few years is a key requirement due to the large exposure needed to achieve a competitive sensitivity. It is especially crucial to enable the detector to potentially detect any annual event rate modulation, an expected dark matter signature. In this work, we present the performance history of the DarkSide-50 dual-phase argon time projection chamber over its almost three-year low-radioactivity argon run. In particular, we focus on the electroluminescence signal that enables sensitivity to sub-keV energy depositions. The stability of the electroluminescence yield is found to be better than 0.5%. Finally, we show the temporal evolution of the observed event rate around the sub-keV region being consistent to the background prediction.