Development of cryogenic optical-photon detectors with Ir/Pt-based transition edge sensors for CUPID

CUPID, a natural successor to the CUORE experiment, is a proposed, future tonne-scale bolometric neutrinoless double beta (0νββ) decay experiment, which will attempt to extend the search of lepton number violation in the so-called inverted hierarchy region of the neutrino mass. However, in order to achieve its goal, CUPID will need to introduce new detection strategies with lower background components and enhanced target masses. A way forward is to develop detectors that will use a scintillating (or Cherenkov light-emitting) crystal and readout the phonon and light signal simultaneously, allowing us to do an event-by-event discrimination, thereby, enhancing the ability to reject background. I will talk about the ongoing R&D efforts at ANL/LBNL/UCB towards developing sensitive optical-photon detectors that can measure tiny amounts of light from the target mass. I will present the initial results from the characterization of these detectors and its performance in terms of energy and timing resolution. The detectors use a novel Iridium/Platinum -bilayer superconducting transition-edge-sensor (TES) that can be operated at temperatures below ~40 mK. To the best knowledge of the authors, this is the first reported study of an Ir/Pt-based TES device operating below ~40 mK.