The ν -cleus experiment: a gram-scale fiducial-volume cryogenic detector for the first detection of coherent neutrino–nucleus scattering

We discuss a small-scale experiment, called ν-cleus, for the first detection of coherent neutrino–nucleus scattering by probing nuclear-recoil energies down to the 10 eV regime. The detector consists of low-threshold CaWO₄ and Al₂O₃ calorimeter arrays with a total mass of about 10 g and several cryogenic veto detectors operated at millikelvin temperatures. Realizing a fiducial volume and a multi-element target, the detector enables active discrimination of γ, neutron and surface backgrounds. A first prototype Al₂O₃ device, operated above ground in a setup without shielding, has achieved an energy threshold of ∼ 20 eV and further improvements are in reach. A sensitivity study for the detection of coherent neutrino scattering at nuclear power plants shows a unique discovery potential (5σ) within a measuring time of ≲ 2 weeks. Furthermore, a site at a thermal research reactor and the use of a radioactive neutrino source are investigated. With this technology, real-time monitoring of nuclear power plants is feasible.