Physics: JUNO’s first data advance neutrino physics (Nature)
11 June 2026
First data from the Jiangmen Underground Neutrino Observatory (JUNO) neutrino experiment in China provide the most precise measurements of neutrino oscillation reported to date. The results, reported in Nature, set the foundation for JUNO’s work advancing the basic understanding of neutrinos, including determining their mass and ordering, and may probe possible new physics.
Neutrinos are tiny fundamental particles that weakly interact with matter, making it difficult to measure their mass. One method to probe this property is measuring neutrino oscillations, a quantum effect in which neutrinos change between three ‘flavours’, or types. Such measurements may answer outstanding questions about the ordering of their masses.
The JUNO neutrino experiment launched in August 2025 with the aim of determining the mass ordering of neutrinos and testing the three-flavour neutrino theory. The JUNO detector is a large spherical tank filled with 20,000 tonnes of liquid, buried 700 metres underground. Whenever an antineutrino interacts, a tiny flash of light is emitted and then captured in the dark environment by tens of thousands of photosensors. In its initial 59.1 days of operation, by reconstructing the energy of incoming neutrinos as they oscillate, JUNO enabled the precise determinations of transitions between the three ‘flavours’ of neutrino. The paper finds JUNO measures neutrino energies with the most accurate precision to date, at around 3% at 1 MeV. These data also provide the first known simultaneous high-precision measurement of key oscillation parameters, reducing the associated uncertainties by a factor of 1.6 compared to the combined experimental results in the past decades.
These first results from JUNO demonstrate that it is operating at its designed performance, the authors note. The findings indicate that JUNO may be able to solve the neutrino mass ordering problem when more data are available.
- Article
- Published: 10 June 2026
The JUNO Collaboration. Measurement of reactor neutrino oscillation with the first JUNO data. Nature 654, 343–348 (2026). https://doi.org/10.1038/s41586-026-10538-z
News & Views: JUNO experiment ushers in next generation of neutrino experiments
https://www.nature.com/articles/d41586-026-01585-7
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