Multiplexed TES Based Light Detectors using a transition edge sensors for CUPID and beyond

CUPID is a proposed upgrade to the tonne-scale neutrinoless double beta decay experiment, CUORE. CUORE is currently operating at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. Degraded α's are the primary background in CUORE, and CUPID aims to improve this background by over a factor of 100 via a two channel energy collection approach using scintillation light and heat. The primary crystal will be scintillating Li₂MoO₄ crystals enriched in ¹⁰⁰Mo with a thin wafer instrumented nearby to collect the scintillation light. This will allow for event by event discrimination of α and γ/β interactions. Large area light detectors using low-Tc IrPt bilayer transition edge sensors deposited on Si wafers are a promising technology to meet the energy and timing resolution requirements of CUPID and beyond. In order to manage the large number of TES based calorimeters required in a CUPID scale experiment, a frequency-domain multiplexing (fMUX) readout is needed to reduce the number of SQUIDs and cabling in the cryostat. We have worked to adapt a fMUX technology developed for cosmic microwave background experiment to work with our TES sensors. Here we present the characterization of the TES light detectors, the implementation of the modified fMUX readout chain, and the integration of these in a demonstrator consisting of 10 TES based light detectors.