Rejection of randomly coinciding events in Li2100MoO4 scintillating bolometers using light detectors based on the Neganov-Luke effect

Random coincidences of nuclear events can be one of the main background sources in low-temperature calorimetric experiments looking for neutrinoless double-beta decay, especially in those searches based on scintillating bolometers embedding the promising double-beta candidate (100) Mo, because of the relatively short half-life of the two-neutrino double-beta decay of this nucleus. We show in this work that randomly coinciding events of the two-neutrino double-beta decay of (100) Mo in enriched Li-2(100) MoO4 detectors can be effectively discriminated by pulse-shape analysis in the light channel if the scintillating bolometer is provided with a Neganov-Luke light detector, which can improve the signal-to-noise ratio by a large factor, assumed here at the level of similar to 750 on the basis of preliminary experimental results obtained with these devices. The achieved pile-up rejection efficiency results in a very low contribution, of the order of similar to 6 x 10(-5) counts/( keV.kg.y), to the background counting rate in the region of interest for a large volume (similar to 90 cm(3)) Li-2(100) MoO4 detector. This background level is very encouraging in view of a possible use of the Li-2(100) MoO4 solution for a bolometric tonne-scale next-generation experiment as that proposed in the CUPID project.