Inside the detector, which resembles a large thermos filled with germanium, faint flashes are born. Neutrinos, tiny particles that barely interact with matter, occasionally bump into germanium nuclei. The nucleus recoils, and the detector registers the jolt. But to distinguish a real signal from noise, the instrument needs precise calibration.

Scientists from the CONUS+ experiment irradiated the detector with neutrons from an americium-beryllium source. Neutrons, like neutrinos, can push nuclei, but their flux can be controlled. By comparing the known energy of the neutrons with the detector's readings, physicists fine-tuned the energy scale. Now the measurement uncertainty is less than 4%—previously it was 14%.

This precision will allow the detector to catch neutrinos from the Leibstadt nuclear power plant reactor and search for signs of new physics beyond the Standard Model. Perhaps it will uncover dark matter particles or other exotic phenomena.