The Jiangmen Underground Neutrino Observatory (JUNO), housing the world's most advanced neutrino detector, has started operation, according to the WeChat public account of Chinese Academy of Sciences.
Neutrinos, elusive subatomic particles essential for understanding the universe, are abundant in the cosmos but difficult to detect due to their weak interactions with matter. The JUNO project aims to measure the neutrino mass hierarchy and oscillation parameters, potentially helping scientists unravel the mysteries of supernova explosions, the origins of the universe, and new physical phenomena.
Embedded 700 meters underground, JUNO can detect neutrinos produced by the Taishan and Yangjiang nuclear power plants — 53 kilometers away — and measure their energy spectrum with high precision.
This engineering marvel, equipped with 45,000 ultra-sensitive "eyes", which are actually photomultiplier tubes, will achieve an unprecedented 3 percent energy resolution — triple the sensitivity of current detectors.
When neutrinos interact with the scintillator — a material that produces flashes of light upon absorbing energy — they emit faint light signals that are amplified by a factor of 10 million. These signals are crucial for unlocking fundamental mysteries, including identifying the heaviest type of neutrino, simulating stellar explosion mechanisms, and tracing the universe's evolution since the Big Bang.
Proposed by the Institute of High Energy Physics of the Chinese Academy of Sciences in 2008, the construction of JUNO tunnel and underground laboratory began in 2015. Installation of the detector in the underground laboratory began after the laboratory construction was completed in December 2021. By December 2024, the construction of the detector was completed, followed by the injection of ultra-pure water and liquid scintillator.
An international endeavor uniting 700 scientists from 17 countries, including Nobel laureate Arthur McDonald's team, JUNO now forms a neutrino research "trinity" with Japan's Hyper-Kamiokande and America's DUNE.
