Neutrinos are extremely elusive elementary particles. Day and night, 60 billion of them stream from the sun through every square centimeter of Earth every second, which is transparent to them. After the first theoretical prediction of their existence, decades passed before they were actually detected. These experiments are usually extremely large to account for the very weak interaction of neutrinos with matter.

Scientists at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg have now succeeded in detecting antineutrinos from the reactor of a nuclear power plant using the CONUS+ experiment, with a detector mass of just 3 kg. The work is published in Nature.

Originally based at the Brokdorf nuclear power plant, the CONUS experiment was relocated to the Leibstadt nuclear power plant (KKL) in Switzerland in the summer of 2023. Improvements to the 1 kg germanium semiconductor detectors, as well as the excellent measurement conditions at KKL, made it possible for the first time to measure what is known as Coherent Elastic Neutrino-Nucleus Scattering (CEvNS).