Status of the CALDER project: Cryogenic light detectors for background suppression

The development of large area cryogenic light detectors is one of the priorities of next generation bolometric experiments searching for neutrinoless double beta decay. The simultaneous read-out of the heat and light signals enables particle identification, provided that the energy resolution and the light collection are sufficiently high. CALDER (Cryogenic wide-Area Light Detectors with Excellent Resolution) is developing phonon-mediated silicon light detectors using KIDs, with the goal of sensing an area of 5 × 5 cm2 with a resolution of 20 eV RMS. We present the latest results obtained with aluminum chips and with newly developed multi-layer titanium–aluminum chips featuring a remarkable sensitivity.