Status of LUMINEU program to search for neutrinoless double beta decay of ¹⁰⁰Mo with cryogenic ZnMoO₄ scintillating bolometers

The LUMTNEU program aims at performing a pilot experiment on 0ν2β decay of ¹⁰⁰Mo using radiopure ZnMoO₄ crystals enriched in ¹⁰⁰Mo operated as cryogenic scintillating bolometers. Large volume ZnMoO₄ crystal scintillators (∼ 0.3 kg) were developed and tested showing high performance in terms of radiopurity, energy resolution and α/β particle discrimination capability. Zinc molybdate crystal scintillators enriched in ¹⁰⁰Mo were grown for the first time by the low-thermal-gradient Czochralski technique with a high crystal yield and an acceptable level of enriched molybdenum irrecoverable losses. A background level of ∼ 0.5 counts/(yr keV ton) in the region of interest can be reached in a large detector array thanks to the excellent detectors radiopurity and particle discrimination capability, suppression of randomly coinciding events by pulse-shape analysis, and anticoincidence cut. These results pave the way to future sensitive searches based on the LUMTNEU technology, capable of approachingand exploring the inverted hierarchy region of the neutrino mass pattern.