Development of Neganov-Trofimov-Luke light detectors for CUPID

CUPID (Cuore Upgrade with Particle IDentification) will be the direct successor of the CUORE experiment to search for neutrinoless double beta decays (0ν2β) at the Gran Sasso National Laboratory in Italy. It will use scintillating bolometers, i.e Li₂MoO₄ scintillating cryogenic absorber embedding ¹⁰⁰Mo as the 0ν2β candidate coupled with a thin Ge cryogenic light detector, both equipped with NTD Ge for dual heat-light readout. This technique permits discrimination of the alpha background, the main contribution to the background of CUORE, and so an enhancement of the sensitivity. In addition, CUPID has to reduce other background sources that could prevent it from reaching its objective. One of them is the contribution of the random coincidences between two two-neutrino-double-beta-decay events, which is the expected dominating one due to the relatively fast ¹⁰⁰Mo half-life for this process. A solution to mitigate it is to use enhanced light detectors using the so-called Neganov-Trofimov-Luke effect, which provides an amplification of the light signal. The faster response of these detectors compared to the main heat bolometers allows for a better rejection of these events. In this contribution, I will summarize the R&D efforts pursued within the collaboration to include these detectors in the CUPID baseline design.