Researchers at the University of California, Irvine have reached a significant milestone as data collection has begun at the Jiangmen Underground Neutrino Observatory (JUNO) in southern China. The project, which has taken over a decade to plan and construct, is located deep beneath Dashi Hill in Guangdong province. JUNO’s advanced detector is designed to help scientists understand the ordering of the three neutrinos by mass, an unresolved question in particle physics. UC Irvine is currently the only institution in the United States with full membership in the JUNO scientific collaboration.
The detector uses a novel system to detect neutrinos—particles that are difficult to observe because they rarely interact with matter. Frederick Reines, a physicist from UC Irvine, co-discovered the neutrino and was awarded the Nobel Prize in Physics in 1995 for this achievement.
By capturing and measuring these particles, researchers hope JUNO will provide answers about processes inside exploding stars and insights into Earth’s interior composition. The UC Irvine team has played a leading role throughout all stages of JUNO’s development and is now analyzing its first sets of data.
“Making progress in fundamental particle research these days requires experts from all over the world collaborating on very large, complex projects such as JUNO,” said J. Pedro Ochoa-Ricoux, professor of physics and astronomy at UC Irvine. “This is an incredibly exciting time for us. After working on the design and construction of this project for over a decade, the time has finally come when we can turn on this cutting-edge scientific instrument.”
Neutrinos are among the least understood particles due to their small mass and ability to change type—a process known as neutrino oscillation. JUNO aims to determine whether one specific neutrino mass state (ν₃) is heavier than another (ν₂), which could impact understanding of both current physics models and potential new theories.
Determining which neutrino state is heaviest would advance knowledge about fundamental particle structure and allow scientists to better use neutrinos for investigating their sources and roles within the universe.
“JUNO is especially suited for measuring low-energy neutrinos from reactors, the sun, Earth and supernova explosions,” Ochoa-Ricoux explained. “The measurements we will make with this detector are complementary to those from experiments such as the Deep Underground Neutrino Experiment, in which UCI is also a key collaborator.”
UC Irvine’s involvement includes contributions from postdoctoral scholar Sindhujha Kumaran; graduate students Katherine Dugas, Adrienne Jacobi, Roberto Mandujano and Zhongyi Wu; as well as undergraduate students Brian Wen Cheng and Samantha Cantu Olea. Their participation is supported by funding from the National Science Foundation.
UC Irvine launched its Brilliant Future campaign publicly on October 4, 2019 with goals that include engaging 75,000 alumni and raising $2 billion for student success initiatives, health research efforts, wellness programs and other university priorities through philanthropic investment by visiting https://brilliantfuture.uci.edu/uci-school-of-physical-sciences.
Founded in 1965, UC Irvine belongs to the Association of American Universities and ranks among America’s top public universities according to U.S. News & World Report rankings. The campus community consists of more than 36,000 students enrolled across 224 degree programs under Chancellor Howard Gillman’s leadership; it has produced five Nobel laureates since its founding while contributing significantly both locally ($7 billion annually) and statewide ($8 billion annually). Additional information about UC Irvine can be found at www.uci.edu.
