TES Based Light Detectors using an IrPt bi-layer transition edge sensor 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. This will allow for event by event discrimination of α and β/γ interactions. In order to meet the timing and energy resolution requirements of CUPID or beyond, large area light detectors which use low-T_c transition edge sensors (TES) deposited on Si wafers are a promising technology. We will present the current state of R&D performed at UC Berkeley, in collaboration with LBNL and ANL, to develop light detectors using an IrPt bilayer TES with Au pads to enhance thermal conductivity to the Si wafer. We report on the preliminary measures of timing and energy resolution, and possible differences in response due to position. Additionally we will discuss ongoing plans to explore multiplexed readout and other improvements.