The world’s deepest and largest underground laboratory – built 2,400 metres (7,874 feet) under the surface in southwest China – has started operations in what could be a major boost to the global search for dark matter.
The launch of the China Jinping Underground Laboratory follows three years of extensive upgrades and expansion, state news agency Xinhua reported on Thursday.
Located at an extreme depth that blocks most cosmic rays, the lab is seen as an ideal “ultra-clean” site for scientists to detect dark matter, an invisible substance believed to make up at least a quarter of the universe.
With a room capacity of 300,000 cubic metres (79.3 million), or about 120 Olympic-sized swimming pools, it is now also the world’s largest underground lab – almost double the size of the Gran Sasso National Laboratory in Italy.
Dark matter does not absorb, reflect or emit light, making it extremely hard to spot, according to the European Organisation for Nuclear Research (CERN), which also hosts equipment that studies the strange and unknown substance.
CERN’s powerful particle accelerator, the Large Hadron Collider, is located 100 metres underground near Geneva on the Franco-Swiss border. The collider is used by international researchers to look for dark matter.
Scientists have been able to infer the existence of dark matter from the gravitational effect it seems to have on visible matter. Unfolding its mystery could help researchers better understand the composition of our universe and how galaxies hold together.
When the first phase of the Jinping lab was completed in 2010, it had a capacity of about 4,000 cubic metres. The joint construction of its second phase by Tsinghua University and the state-owned Yalong River Hydropower Development Company started in December 2020.
Located deep underneath Jinping Mountain in China’s southwestern Sichuan province, the research facility can be accessed by car via a tunnel.
Yue Qian, a professor at Tsinghua’s department of engineering physics, told Xinhua that the lab was only exposed to a tiny flux of cosmic rays, equal to one hundred-millionth of that on the Earth’s surface, offering an ultra-clean space for scientists to seek dark matter.
Other conditions in the lab, including extremely low environmental radiation and concentration of the naturally occurring radioactive gas radon, would also enhance dark matter detection, “so that we can embark on the most significant scientific inquiries”, Yue was quoted as saying.
He added that the lab would also support interdisciplinary research such as in the fields of particle physics, nuclear astrophysics, cosmology, life sciences and rock mechanics.
Ten research teams comprising scientists from the Tsinghua, Shanghai Jiao Tong and Beijing Normal universities, as well as the China Institute of Atomic Energy, Institute of Rock and Soil Mechanics of the Chinese Academy of Sciences and more were already stationed at the facility, Xinhua said.
According to the state-backed China News Service, a team from Sichuan Medical University’s West China Medical Centre, studying deep earth medicine at the lab, had been able to identify molecular targets adapted to extremely low background radiation. The discovery could potentially improve tumour treatment, the report said.