China’s study of ‘ghost particles’ yields first results in country’s goal to be science powerhouse
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The Jiangmen Underground Neutrino Observatory consists of a giant sphere to detect the elusive neutrino particle.
PHOTO: BLOOMBERG
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- China's JUNO, a S$496 million neutrino observatory, has reported its first high-precision results, measuring solar neutrino oscillation parameters within two months of operation.
- JUNO aims to solve physics mysteries by studying neutrinos, tiny particles, and contributes to China's goal of becoming a science and technology powerhouse via basic research.
- Experts highlight JUNO's world-leading position and complementarity with US and Japanese facilities, attracting global talent and promising new results in neutrino oscillation.
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BEIJING – China is on track to unlock the mysteries behind a particle that is everywhere on earth yet extremely hard to detect, with the completion of a next-generation science experiment dedicated to detecting neutrinos with high precision.
The Jiangmen Underground Neutrino Observatory
Located in Guangdong province, JUNO consists of a giant sphere 700m underground and surrounded by more than 40,000 light detectors, a set-up meant to detect the elusive neutrino, dubbed the “ghost particle”.
Fundamental particles are the smallest building blocks of matter. Neutrinos, which are tiny, sub-atomic particles, are still poorly understood despite being ubiquitous – trillions of neutrinos pass through the human body every second without being felt.
Studying them could solve some of the deepest mysteries of physics. Major countries like China and the US, and Europe, have invested millions in such large-scale experiments, which draw top scientific talent and investment in cutting-edge technologies.
Professor Wen Liangjian, physics coordinator at JUNO, said that the first set of data from measuring solar neutrino oscillation parameters – a set of numbers that describes how neutrinos that travel from the Sun to Earth change – has been measured at a higher precision than in previous experiments.
“Achieving such precision within only two months of operation shows that JUNO is performing exactly as designed,” Dr Wang Yifang, who leads JUNO, said of the China-led international collaboration. Data collected is shared among participating institutions.
JUNO is one of the few high-end facilities in the world at the frontier of the detection and study of neutrinos. Others include the Deep Underground Neutrino Experiment (DUNE) in the US and Japan’s Hyper-Kamiokande, both of which are still under construction.
The project is part of China’s longer-term aim of becoming a science and technology powerhouse. Studying neutrinos is a form of basic research, which has no immediate applications but is key to future breakthroughs.
China’s leaders view boosting basic research as a solution to the problem of technological “choke points”, or the reliance on other countries for critical technologies. National spending on basic research hit a record 250 billion yuan in 2024.
Professor of physics Jennifer Thomas from the University College London described JUNO as “world-leading”. She noted that the US’ DUNE and Japan’s Hyper-Kamiokande are still a few years away from coming online, with both set to turn operational around 2028.
China has pulled ahead in a sub-part of the field of neutrino oscillation measurements with the advent of the Daya Bay experiment, she told The Straits Times, referring to another neutrino experiment in Guangdong that operated mainly from 2011 to 2020.
“Since then, it has held the lead here, and JUNO is the next, very large step forward.”
Prof Thomas added: “I think one of the advantages the Chinese have over the rest of the world right now is a focus and willingness to spend large amounts of money on scientific research… JUNO will definitely be front and centre of new results for the next five years in the field of neutrino oscillations.”
Professor J. Pedro Ochoa-Ricoux, a particle physicist from the University of California at Irvine, said that the US and Japanese facilities are not necessarily in competition with JUNO.
“While there is some overlap, DUNE and Hyper-Kamiokande are after different questions than JUNO. The three experiments are highly complementary,” he told ST.
Prof Ochoa-Ricoux is among more than 700 researchers from 17 countries and regions involved in JUNO, including the French National Centre for Scientific Research, the largest fundamental science research agency in Europe.
He added: “Together with other neutrino projects like DUNE and Hyper-Kamiokande, JUNO is at the top of the field and has a multi-decade physics programme ahead, so I expect it will continue to attract some of the world’s top minds.”
The acrylic sphere at JUNO is filled with 20,000 tonnes of a liquid material that emits flashes of light when a neutrino collides with an atom there. The thousands of light detectors around the sphere then capture and measure such light bursts.
The detector measures neutrinos coming from two nuclear power plants – Yangjiang and Taishan – both located 53km away. The granite mountain the sphere is built under shields it against cosmic rays from outer space that might interfere with its measurements.
Professor Oh Choo Hiap from the National University of Singapore’s Department of Physics said there is valuable knowledge that can be gained when countries host and conduct such cutting-edge experiments.
“For frontier research, there will be new techniques and technologies involved, which may end up being useful later on.
“These technical know-hows, when you develop them yourself, you would understand the... experimental design better than scientists from other countries or labs not working in this area,” he told ST.
