Aluminum Relaxation as the Source of Excess Low Energy Events in Low Threshold Calorimeters

TL;DR

This paper proposes that relaxation of stressed aluminum films, through dislocation motion, explains the Low Energy Excess background observed in low threshold calorimeters used in dark matter and neutrino experiments.

Contribution

It introduces a novel explanation for the Low Energy Excess, linking aluminum relaxation to dislocation dynamics as a source of background noise.

Findings

Aluminum relaxation can produce low energy events in calorimeters.

Dislocation motion in aluminum films correlates with observed excess events.

The model explains the background in various low threshold calorimeter experiments.

Abstract

A previously unexplained background called the Low Energy Excess (LEE) has negatively impacted the reach of a variety of low threshold calorimeters including light dark matter direct detection and coherent elastic neutrino-nucleus scattering experiments. The relaxation of stressed aluminium films as mediated by the motion of dislocations may account for these observations.