China completes core construction of underground neutrino detector

The core part of the Jiangmen Underground Neutrino Observatory. (Photo provided to China Daily)

Construction of the core component of China's Jiangmen Underground Neutrino Observatory (JUNO), a major scientific facility located 700 meters (2,300 feet) underground in Guangdong province, has been completed, officials said Wednesday.

The observatory, launched in 2015 by the Chinese Academy of Sciences and the Guangdong provincial government, is entering its final construction phase, according to the CAS Institute of High Energy Physics, which leads the project.

At the heart of the facility is a 35.4-meter acrylic sphere, the world's largest transparent spherical detector designed to capture elusive neutrinos — subatomic particles that play a fundamental role in the universe's structure and evolution. Standing 12 stories tall, the detector represents a major engineering breakthrough in neutrino research.

JUNO is expected to begin operations in August 2025 and will run for at least 30 years. It aims to measure the neutrino mass hierarchy and oscillation parameters, critical to understanding supernova explosion mechanisms, the origins and evolution of the universe, and potentially discovering new physical phenomena.

"Our country's neutrino experiment has achieved significant breakthroughs in design and experimental accuracy, overcoming numerous technological challenges," said Cao Jun, director of the Institute of High Energy Physics.

Wang Yifang, a former director of the institute, highlighted the observatory's global significance. "The primary scientific goal of JUNO is to measure neutrino properties that are crucial to fundamental physics research and advancing our understanding of the universe," he said.