Development of Low-Threshold Detectors for Low-Mass Dark Matter Searches Using an N-Type Germanium Detector at 5.2 K

TL;DR

This study explores charge transport in n-type germanium detectors at 5.2 K to develop low-threshold detectors for enhanced low-mass dark matter detection sensitivity, focusing on charge state binding energies and electric field effects.

Contribution

It introduces a novel approach to low-threshold detector development by analyzing charge states and electric field effects in germanium detectors at cryogenic temperatures.

Findings

Lower binding energy of charge states in the second mode suggests different charge formation.

Measured dipole and cluster dipole binding energies indicate high potential for low-mass dark matter detection.

Different operating modes affect charge state formation and detector sensitivity.

Abstract

We investigated charge transport in an n-type germanium detector at 5.2 K to explore new technology for enhancing low-mass dark matter detection sensitivity. Calculations of dipole and cluster dipole state binding energies and electric field-dependent trapping cross-sections are critical to developing low-threshold detectors. The detector operates in two modes: depleting at 77K before cooling, or directly cooling to 5.2 K and applying different bias voltages. Results indicated lower binding energy of charge states in the second mode, at zero field and under an electric field, suggesting different charge states formed under different operating modes. Measured cluster dipole and dipole state binding energies at zero field were 7.884$\pm$0.644 meV and 8.369$\pm$0.748 meV, respectively, signifying high low-threshold potential for low-mass dark matter searches in the future.