Performance of a Large Area Photon Detector For Rare Event Search Applications

TL;DR

This paper introduces a large-area cryogenic photon detector optimized for rare event searches, demonstrating high energy and timing resolution suitable for neutrino and dark matter experiments.

Contribution

The paper presents the design, calibration, and characterization of a novel large-area cryogenic photon detector with advanced phonon sensing technology.

Findings

Energy resolution of 3.86 eV RMS achieved

Noise equivalent power of 1e-17 W/√Hz measured

Timing resolution of 2.3 μs for 5σ events

Abstract

We present the design and characterization of a large-area Cryogenic PhotoDetector (CPD) designed for active particle identification in rare event searches, such as neutrinoless double beta decay and dark matter experiments. The detector consists of a $45.6$ $\mathrm{cm}^2$ surface area by 1-mm-thick $10.6$ $\mathrm{g}$ Si wafer. It is instrumented with a distributed network of Quasiparticle-trap-assisted Electrothermal feedback Transition-edge sensors (QETs) with superconducting critical temperature $T_c=41.5$ $\mathrm{mK}$ to measure athermal phonons released from interactions with photons. The detector is characterized and calibrated with a collimated $^{55}$Fe X-ray source incident on the center of the detector. The noise equivalent power is measured to be $1\times 10^{-17}$ $\mathrm{W}/\sqrt{\mathrm{Hz}}$ in a bandwidth of $2.7$ $\mathrm{kHz}$. The baseline energy resolution is measured to be $\sigma_E = 3.86 \pm 0.04$ $(\mathrm{stat.})^{+0.23}_{-0.00}$ $(\mathrm{syst.})$ $\mathrm{eV}$ (RMS). The detector also has an expected timing resolution of $\sigma_t = 2.3$ $\mu\mathrm{s}$ for $5$ $\sigma_E$ events.