China opens the deepest underground laboratory in the world to search for dark matter

China opens the deepest underground laboratory in the world to search for dark matter

  • China has just opened the world’s deepest and largest underground laboratory.
  • China’s Jinping Underground Laboratory-2 will seek to uncover the secrets of dark matter.
  • At a depth of about 7,800 feet underground, it should be protected from cosmic radiation.

China has opened the world’s largest and deepest underground laboratory in an attempt to uncover the secrets of dark matter.

China Jinping Underground Laboratory-2 (CJPL-II) in southwestern China’s Sichuan Province opened in December 2023, an expansion of the original CJPL facility, which was first launched in 2010.

CJPL-II is located 7,874 feet underground with a surface area of ​​more than 11.6 million cubic feet, according to a press release. This makes it larger than Italy’s Gran Sasso National Laboratory, which previously held the record, Nature News reported.

With its extensive mountainous cover, the facility aims to provide ideal conditions for studying the elusive matter that makes up an estimated 95% of the universe – dark matter.

Dark matter is really hard to see

Nature News explained that the gravity of visible matter is too weak to explain why fast-moving galaxies do not fly apart.

This leaves us with one overarching theory; That there is another type of matter that affects the universe, or what is called dark matter.

Scientists believe that, by its very nature, dark matter does not want to interact with matter that we can see and feel or even light.

This makes physical detectors very difficult to pick up, and any kind of monitoring is easily thwarted by background radiation that can contaminate the experiment.

An image shows a tunnel inside a Chinese research facility

Image from inside CJPL-II

China’s Jinping underground laboratory



Going inside the Earth to protect from space

Even very weak radiation can spoil the search for dark matter.

Cosmic radiation, for example, is too faint to affect humans, but it can cause background noise that can alter experimental results.

That’s why scientists dig deep to protect their detectors. Thick mountains in Sichuan Province are supposed to help ward off up to 0.000001% of the radiation that hits Earth from space, according to Nature News.

Weak radiation from concrete or water and rocks in the mountain itself can also be harmful. Therefore, the experimental chambers were lined with a mixture of concrete and rubber to protect them from the mountain’s radiation, according to Nature News.

The video below provides more views inside the facility.

New detectors to match the new facility

The laboratory’s new footprint has allowed CJPL to expand its experimental equipment. CJPL hosts the Xenon Particle and Astrophysics Experiments (PandaX) and the China Dark Matter Experiment.

The PandaX now sits inside a water tank with a capacity of about 32,000 cubic feet to protect the 8,800-pound liquid xenon detector from background interference. This is a huge improvement over their previous detector, which contained only 264 pounds of liquid xenon.

This upgrade puts PandaX-4T on a par with existing detectors in Italy and at the Sanford Underground Research Facility in Lead, South Dakota, according to Nature News.

“With better sensitivity, we can play with the detector and test different types of interactions,” team member Ning Zhao, a physicist at Shanghai Jiao Tong University in China, told Nature News.

Whether the detector will transform the field of dark matter physics remains to be seen, Juan Collar, a physicist at the University of Chicago in Illinois, told Nature News.

The PandaX is similar to other detectors around the world, and it’s not clear whether better sensitivity would lead to better results.

“There is enough redundancy already,” he said, adding that it might be better to try to find a new approach in the search for dark matter.

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