World’s Largest Neutrino Detector “a Historic Milestone”

The world’s largest neutrino detector, or “ghost particles” as they’ve been called, has been turned on, potentially one day helping solve mysteries surrounding the building blocks of matter.

“Completing the filling of the JUNO detector and starting data taking marks a historic milestone. For the first time, […] JUNO will allow us to answer fundamental questions about the nature of matter and the universe,” says Professor Yifang Wang, a researcher at the Institute of High Energy Physics of the Chinese Academy of Sciences.

The Jiangman Underground Neutrino Observatory (JUNO) in Southern China will allow scientists to study neutrino mass ordering, ultimately expanding our understanding of astrophysical phenomena. The JUNO project has been in progress for over a decade and lies 700 meters underground. Its 20,000-ton liquid scintillator was filled and began data intake on August 26, 2025. One key question it is expected to answer is the ordering of neutrino masses – in other words, whether the third mass state (ν₃) is heavier than the second (ν₂). Over 700 researchers across 17 nations are involved in the project, which may profoundly alter and shape our understanding of the universe.