First scintillating bolometer tests of a CLYMENE R&D on Li₂MoO₄ scintillators towards a large-scale double-beta decay experiment

A new R&D on lithium molybdate scintillators has begun within a project CLYMENE (Czochralski growth of Li$_2$MoO$_4$ crYstals for the scintillating boloMeters used in the rare EveNts sEarches). One of the main goals of the CLYMENE is a realization of a Li$_2$MoO$_4$ crystal growth line to be complementary to the one recently developed by LUMINEU in view of a mass production capacity for CUPID, a next-generation tonne-scale bolometric experiment to search for neutrinoless double-beta decay. In the present paper we report the investigation of performance and radiopurity of 158-g and 13.5-g scintillating bolometers based on a first large-mass (230 g) Li$_2$MoO$_4$ crystal scintillator developed within the CLYMENE project. In particular, a good energy resolution (2--7 keV FWHM in the energy range of 0.2--5 MeV), one of the highest light yield (0.97 keV/MeV) amongst Li$_2$MoO$_4$ scintillating bolometers, an efficient alpha particles discrimination (10$\sigma$) and potentially low internal radioactive contamination (below 0.2--0.3 mBq/kg of U/Th, but 1.4 mBq/kg of $^{210}$Po) demonstrate prospects of the CLYMENE in the development of high quality and radiopure Li$_2$MoO$_4$ scintillators for CUPID.