JUNO sharpens neutrino-oscillation picture, edging toward mass hierarchy

With about two months of data, the Jiangmen Underground Neutrino Observatory (JUNO) measured two key reactor-neutrino oscillation parameters with 1.6× better precision than decades of previous experiments. The results, published in Nature, advance the effort to determine the neutrino mass ordering and shed light on the origin of neutrino masses, using a 20,000‑ton scintillator detector instrumented with 43,000 photomultiplier tubes observing reactor antineutrinos ~53 km away.