JUNO experiment achieves unprecedented precision in neutrino measurements

JUNO, which began data collection in August 2025, has released its debut scientific findings as a cover article in Nature on June 10, 2026, drawing on 59 days of validated data. The collaboration, led by the Institute of High Energy Physics of the Chinese Academy of Sciences and involving over 700 researchers from 75 institutions across 17 countries, measured two fundamental neutrino oscillation parameters with a precision 1.6 times better than the best previous combined results. The detector detects electron antineutrinos from two nearby nuclear power plants via inverse beta decay, in which antineutrinos interact with protons in the liquid scintillator to produce a prompt positron signal and a delayed neutron capture signal, both captured by the dense array of 20,000 large and 25,600 small photomultiplier tubes visible in construction photographs. The results also confirmed a persistent ~1.5 standard deviation discrepancy between solar and reactor neutrino measurements of one oscillation parameter, known as the 'solar neutrino tension,' though they do not yet resolve it. JUNO's primary long-term goal — determining the neutrino mass ordering, i.e., whether two of the three neutrino flavors are heavier or lighter than the third — remains an open question that the experiment is designed to answer with more data. Nobel laureate Arthur McDonald praised the detector as having met its design objectives in energy resolution, radiopurity, and stability. Future competing detectors, Japan's Hyper-Kamiokande and the U.S.-based Deep Underground Neutrino Experiment, are expected to begin data collection within the next decade and will cross-check JUNO's results using different methodologies.