China adds ‘ghost particle’ detector to South China Sea observation network

In the darkness of the ocean depths, Chinese scientists are hoping to solve one of the enduring mysteries of the universe

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Chinese scientists have placed detectors in the South China Sea, as they plan to build a huge underwater observatory in a bid to observe neutrinos, and discover the origin of cosmic rays. Photo: The Institute of High Energy Physics, Chinese Academy of Sciences

Published: 4:00pm, 8 Feb 2025

Prototype detectors have been sent deep into the South China Sea by Chinese scientists to test the possibility of building a massive underwater observatory that would be used to search for neutrinos – tiny, elusive subatomic particles from deep space.

If it all goes as planned, it could take scientists a step closer to uncovering the mysterious origin of cosmic rays.

Equipment, including self-developed, highly sensitive detector units and an LED light source for calibration, was placed at a depth of precisely 1,600 metres (5,250 feet) last month with the help of the submersible Shenhai Yongshi, or Deep-Sea Warrior, according to the Institute of High Energy Physics in Beijing, which is leading the project.

Now connected to China’s national underwater scientific observation network for power and data transmission, the detectors were waiting in the darkness to capture faint flashes of light when neutrinos pass through, the institute said on Wednesday via WeChat.

It is all part of a bid to build the High-energy Underwater Neutrino Telescope (HUNT), which would be the world’s largest underwater neutrino observatory with more than 55,000 detectors suspended along thousands of strings, covering 30 cubic km (7.2 cubic miles) of ocean.

“The stable operation of the prototype detectors marks a significant step forward in our preliminary research for the HUNT project,” the institute said. “Once complete, it will position China at the forefront of neutrino astronomy.”

The South China Sea is not the only candidate site for HUNT. Last spring, researchers deployed prototype detectors at a depth of 1,300m in Siberia’s Lake Baikal, and conducted on-site testing with Russian scientists involved in the Baikal-GVD neutrino experiment, according to the institute.