Measurement of Low Energy Nuclear Recoil Events with the phonon-mediated Voltage-Assisted Hybrid Detector for Rare Event Searches

TL;DR

This paper presents a phonon-mediated hybrid silicon detector capable of distinguishing electron and nuclear recoils at low energies, achieving measurements of nuclear recoils around 500 eV and reducing electron recoil background by 95%.

Contribution

The study introduces a novel hybrid detector design with a software triggering technique that enhances low-energy nuclear recoil detection and background suppression.

Findings

Measured nuclear recoil events at approximately 500 eV_{ee}.

Achieved up to 95% reduction in electron recoil background.

Demonstrated effective differentiation between electron and nuclear recoils.

Abstract

The phonon-mediated hybrid detector is made out of a monolithic silicon crystal characterized by two interconnected regions linked through a narrow neck. Operating solely on phonon signal measurements, the hybrid design facilitates the differentiation between electron recoil and nuclear recoil events, effectively discerning two types of interaction down to low energy levels. With a newly implemented software triggering technique (SWT), low-energy nuclear recoil events of approximately $500~eV_{ee}$ have been measured. In addition to this, an electron recoil background reduction of up to $95\%$ has been successfully demonstrated.