Phonon Quasidiffusion in Cryogenic Dark Matter Search Large Germanium Detectors

TL;DR

This study investigates phonon quasidiffusion in large cryogenic germanium detectors used for dark matter searches, comparing experimental data with Monte Carlo simulations to understand phonon behavior at millikelvin temperatures.

Contribution

It provides new insights into phonon quasidiffusion in large germanium detectors and compares different detector configurations with detailed Monte Carlo modeling.

Findings

Phonon quasidiffusion behavior characterized at 50 mK.

Comparison of experimental data with Monte Carlo simulations.

Impact of detector design on phonon propagation.

Abstract

We present results on quasidiffusion studies in large, 3 inch diameter, 1 inch thick [100] high purity germanium crystals, cooled to 50 mK in the vacuum of a dilution refrigerator, and exposed with 59.5 keV gamma-rays from an Am-241 calibration source. We compare data obtained in two different detector types, with different phonon sensor area coverage, with results from a Monte Carlo. The Monte Carlo includes phonon quasidiffusion and the generation of phonons created by charge carriers as they are drifted across the detector by ionization readout channels.