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

The LUMINEU program aims at performing a pilot experiment on O nu 2 beta decay of Mo-100 using radiopure ZnMoO4 crystals enriched in Mo-100 operated as cryogenic scintillating bolometers. Large volume ZnMoO4 crystal scintillators (similar to 0.3 kg) were developed and tested showing high performance in terms of radiopurity, energy resolution and alpha/beta particle discrimination capability. Zinc molybdate crystal scintillators enriched in Mo-100 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 similar to 0.5 counts/(yr keV ton) in the region of interest can be reached in a large detector array thanks to the excellent detectors radiopunty 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 LUMINEU technology, capable of approaching and exploring the inverted hierarchy region of the neutrino mass pattern.