Measurement of reactor neutrino oscillation with the first JUNO data

The Jiangmen Underground Neutrino Observatory (JUNO) released its first data, providing high-precision measurements of neutrino oscillation parameters, as reported on June 10, 2026, in Nature. This initial dataset significantly improves existing measurements and demonstrates the observatory's capability to determine the neutrino mass ordering. The data collected by JUNO, a massive liquid scintillator detector located 700 meters underground in China, allows for precise analysis of electron antineutrinos produced by nuclear reactors. The experiment aims to resolve one of the fundamental mysteries in particle physics: the ordering of the three neutrino mass states. Achieving this will require further data collection and analysis, but the current results represent a substantial step forward. The observatory's design and the quality of its initial data collection underscore its readiness for this complex scientific endeavor, which has implications for our understanding of the universe's evolution and the fundamental properties of matter. The successful operation of JUNO and the early scientific output highlight the collaborative international effort involved in such large-scale physics experiments.