Rejection of randomly coinciding events in Li$_2^{100}\mathrm{MoO}_4$ scintillating bolometers using light detectors based on the Neganov–Luke effect

• Published in: The European physical journal. C, Particles and fields Vol. 77; no. 1
• Main Authors: Chernyak, D.M., Danevich, F.A., Dumoulin, L., Giuliani, A., Mancuso, M., de Marcillac, P., Marnieros, S., Nones, C., Olivieri, E., Poda, D.V., Tretyak, V.I.
• Format: Journal Article
• Language: English
• Published: Springer Verlag (Germany) 2017
• Subjects: Instrumentation and Detectors; Nuclear Experiment; Physics; pile-up; lithium; efficiency; bolometer; background; double-beta decay: (0neutrino); noise; molybdenum: oxygen; shape analysis; photon: detector; molybdenum: nuclide
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-016-4565-z

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$_2^{100}\,\mathrm{MoO}_4$ 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 ${\sim }750$ 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 ${\sim }6\times 10^{-5}$  counts/(keV $\cdot $ kg $\cdot $ y), to the background counting rate in the region of interest for a large volume ( ${\sim }90$  cm$^3$ ) Li$_2^{100}\,\mathrm{MoO}_4$ detector. This background level is very encouraging in view of a possible use of the Li$_2^{100}\,\mathrm{MoO}_4$ solution for a bolometric tonne-scale next-generation experiment as that proposed in the CUPID project.