World’s largest neutrino detector built in China surpasses expectations in physics results

China’s Jiangmen Underground Neutrino Observatory (JUNO), the world’s largest and most advanced neutrino detector, has exceeded expectations in its initial physics results. After more than a decade of development and international collaboration, JUNO began operations in August 2025 and quickly demonstrated unprecedented precision in measuring neutrino oscillation parameters. Within just 59 days of data collection, JUNO measured the solar neutrino oscillation parameters θ12 and Δm221 with 1.6 times better precision than all previous experiments combined. This measurement confirmed a previously observed mild discrepancy between solar and reactor neutrino results, known as the solar neutrino tension, which JUNO is uniquely positioned to investigate further. The detector, featuring a 20-kiloton liquid scintillator core surrounded by a water Cherenkov veto and plastic scintillator veto layers, was constructed underground to minimize background interference. Its design and performance reflect cutting-edge technology and the combined expertise of international research groups. JUNO’s early success signals its