Irvine, California, August 29, 2025
Researchers at the University of California, Irvine, have reached a major milestone at the Jiangmen Underground Neutrino Observatory (JUNO) in southern China, where the massive, state-of-the-art detector has just begun collecting particle physics data. After more than a decade of planning and construction, the JUNO project is now operational, and scientists will use the data to solve one of the biggest mysteries in particle physics: the ordering of the three types of neutrinos by mass.
Key Headlines
* A “Ghost Particle” Hunt: The JUNO detector is designed to capture and measure neutrinos, elusive subatomic particles known as “ghost particles” because they can pass through matter without leaving a trace.
* The Mass Hierarchy Mystery: The primary goal of the JUNO project is to determine whether the third neutrino mass state is heavier or lighter than the second, a fundamental question with profound implications for the Standard Model of particle physics.
* A Decade-Long Effort: The commencement of data collection marks the culmination of a decade-long international effort involving over 700 scientists from 17 countries.
* UC Irvine’s Leadership: Researchers from UC Irvine have played a key leadership role throughout the project, from its initial design to the analysis of the first waves of data.
Deep beneath Dashi Hill in China’s Guangdong province, JUNO’s detector is a multi-purpose experiment designed to measure neutrinos from various sources, including nearby nuclear reactors, the sun, and even supernova explosions. By capturing, counting, and measuring these elusive particles, scientists hope to answer important questions about how the universe works, from the composition of Earth’s interior to the processes that occur within exploding stars.
The project’s innovative approach enables a direct determination of the “neutrino mass hierarchy,” a discovery that could have broad implications for our understanding of the universe. For years, the scientific community has been working to understand the properties of neutrinos, and JUNO’s exceptional energy resolution is expected to provide the most precise measurements yet.
The role of UC Irvine’s team has been crucial. As a key partner in this global research collaboration, the university’s researchers were involved from the project’s inception, contributing to the design and construction of the detector and now taking a leading role in analyzing the data. This monumental project highlights how progress in fundamental particle research today requires a collaborative, worldwide effort to tackle complex scientific challenges.
