Large area photon calorimeter with Ir-Pt bilayer transition-edge sensor for the CUPID experiment

TL;DR

This paper presents a novel Ir-Pt bilayer transition-edge sensor for cryogenic light detection in the CUPID neutrinoless double-beta decay experiment, demonstrating improved responsivity and meeting noise and timing requirements.

Contribution

Introduction of a new Ir-Pt bilayer TES design with systematic improvements in thermal coupling and responsivity for CUPID's light detectors.

Findings

Detectors meet CUPID's noise requirement of <100 eV rms.

Detectors have risetimes of ~180 μs.

Timing jitter is <20 μs, suitable for background rejection.

Abstract

CUPID is a next-generation neutrinoless double-beta decay experiment that will require cryogenic light detectors to improve background suppression, via the simultaneous readout of heat and light channels from its scintillating crystals. In this work we showcase light detectors based on a novel Ir-Pt bilayer transition edge sensor. We have performed a systematic study to improve the thermal coupling between the photon absorber and the sensor, and thereby its responsivity. Our first devices meet CUPID's baseline noise requirement of <100~eV rms. Our detectors have risetimes of $\sim$180 $\mu$s and measured timing jitter of <20 $\mu$s for the expected signal-to-noise at the Q-value of the decay, which achieves the CUPID's criterion of rejecting two-neutrino double-beta decay pileup events. The current work will inform the fabrication of future devices, culminating in the final TES design and a scaleable readout scheme for CUPID.