Tagging and localisation of ionizing events using NbSi transition edge phonon sensors for Dark Matter searches

TL;DR

This paper presents a novel technique using NbSi transition edge phonon sensors to tag ionizing events in germanium detectors, significantly reducing background noise and improving dark matter detection sensitivity.

Contribution

The study introduces a new phonon-based tagging method with NbSi sensors for dark matter searches, enhancing background rejection and detection limits.

Findings

Background rejection improved by over 5 times at 90% C.L.

Detection sensitivity increased by a factor of 2.8 for 1 GeV/c2 WIMPs.

Effective localization of ionization events in the detector.

Abstract

In the context of direct searches of sub-GeV Dark Matter particles with germanium detectors, the EDELWEISS collaboration has tested a new technique to tag ionizing events using NbSi transition edge athermal phonon sensors. The emission of the athermal phonons generated by the Neganov-Trofimov-Luke effect associated with the drift of electrons and holes through the detectors is used to tag ionization events generated in specific parts of the detector localized in front of the NbSi sensor and to reject by more than a factor 5 (at 90% C.L.) the background from heat-only events that dominates the spectrum above 3 keV. This method is able to improve by a factor 2.8 the previous limit on spin-independent interactions of 1 GeV/c2 WIMPs obtained with the same detector and data set but without this tagging technique.