Workers are seen at the construction site of the second phase of the China Jinping Underground Laboratory in southwest China's Sichuan Province, Sept. 19, 2023. (Xinhua/Xue Chen)

A 2,400-meter-deep physics laboratory in southwest China's Sichuan Province became operational on Thursday, making it the deepest and largest underground lab in the world.

Scientists believe the laboratory provides a "clean" space for them to pursue the invisible substance known as dark matter. They said the extreme depth helps block most cosmic rays that mess with the observation.

The Deep Underground and Ultra-low Radiation Background Facility for Frontier Physics Experiments (DURF) is located beneath Jinping Mountain in Sichuan's Liangshan Yi Autonomous Prefecture.

The DURF, with a total room capacity of 330,000 cubic meters, is the second phase of China Jinping Underground Laboratory. It started construction in December 2020 and was jointly built by Tsinghua University and Yalong River Hydropower Development Company, Ltd.

The DURF will become a world-class interdisciplinary deep underground scientific research center integrating multiple disciplines including particle physics, nuclear astrophysics and life sciences, to facilitate the development of China's research in relevant frontier fields, said Yue Qian, a professor at Tsinghua University.