German physicists have detected a signal from the elastic coherent scattering of reactor antineutrinos on atomic nuclei using the germanium detector CONUS+. The statistical significance of the detection was 3.7 standard deviations. The results are available on the preprint site arXiv.org.
Observing the elastic coherent scattering of reactor antineutrinos is a challenging task due to the extremely low recoil energies of the nuclei of the detecting substance. We recently reported that this has not yet been achieved using a liquid xenon detector. However, scientists have already learned to detect this process for accelerator neutrinos, and last year they observed it for solar neutrinos. The CONUS experiment came closest in detecting this process for reactor antineutrinos, but it did not manage to collect sufficient data before the complete shutdown of the Brokdorf Nuclear Power Plant.
A team of scientists from the CONUS collaboration, led by Manfred Lindner of the Max Planck Institute for Nuclear Physics, succeeded in detecting elastic coherent scattering of reactor antineutrinos on germanium (Ge) nuclei. To do this, they transported the CONUS detector to the Leibstadt nuclear power plant in Switzerland and modified it to lower the energy threshold for detecting events. CONUS+ was located 21 meters from the nuclear reactor, providing a flux of 1.5 × 10 antineutrinos per square centimeter per second. The scientists collected data over 119 days of reactor operation.
After analyzing the data, the physicists discovered 395 ± 106 events that outweighed the background. This, according to the authors, is consistent with the Standard Model prediction, which predicted 347 ± 34 events. The statistical significance of the discovery was 3.7 standard deviations.
For more information on elastic coherent scattering of neutrinos on atomic nuclei, read our interview with Dmitry Akimov, a participant in the first experiment to record this process.
