Enriched Zn\(^{100}\)MoO\(_4\) scintillating bolometers to search for \(0\nu 2\beta \) decay of \(^{100}\)Mo with the LUMINEU experiment

The LUMINEU project is a demonstrator experiment that will search for the neutrinoless double beta decay of the isotope \(^{100}\)Mo embedded in zinc molybdate (ZnMoO\(_4\)) scintillating bolometers. In this context, a zinc molybdate crystal boule enriched in \(^{100}\)Mo to 99.5 % with a mass of 171 g was grown for the first time by the low-thermal-gradient Czochralski technique. The production cycle provided a high yield (the crystal boule mass was 84 % of the initial charge) and an acceptable level—around 4 %—of irrecoverable losses of the costly enriched material. Two crystals of 59 and 63 g, obtained from the enriched boule, were tested above ground at millikelvin temperatures as scintillating bolometers. They showed a good detection performance, equivalent to that of previously developed natural ZnMoO\(_4\) detectors. 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.