More details of China’s top neutrino lab revealed

Recently, a laboratory hidden 700 meters below the mountain in Jiangmen, Guangdong Province, has become a trending topic. It is the Jiangmen Underground Neutrino Observatory (JINO), currently the largest and most sensitive liquid scintillator neutrino detector in the world.

Thanks to a popular science program, the mysterious laboratory is once again in the spotlight. Some questions about the JINO were also further answered.

What does the JINO look like?

Unlike ordinary laboratories, the main body of the JINO is like a watermelon soaked in ice water.

The outermost part of the detector is a network frame composed of low-radioactive stainless steel. This is the largest single stainless steel structure in China. The entire structure is fixed by 120,000 sets of high-strength bolts.

Inside the network frame is a plexiglass ball with a diameter of 35.4 meters and a thickness of only 120 millimeters. Although thin as an eggshell, the plexiglass ball is extremely strong. The entire sphere constitutes the world’s most accurate and largest liquid scintillator detector.

In the future, the entire neutrino experimental device will be surrounded by 35,000 tons of ultra-pure water, and 20,000 tons of the world’s most transparent scintillator will be poured into the sphere.

Why is it necessary to capture neutrinos 700 meters underground?

Do you have a concept of the “700 meters deep”? The height of the Canton Tower, one of Guangzhou’s famous landmarks, is 600 meters. That is to say, if we turn the Canton Tower upside down and put it underground, the tip of the tower is still 100 meters away from the JINO.

Why is it necessary to capture neutrinos 700 meters underground? There are many natural cosmic rays in our daily life, and the signals generated by these rays are much stronger than those generated by neutrinos. Therefore, the neutrino laboratory is built underground by using the thickness of the mountain and the rock layer. It is like forming a natural filter, which can shield most natural cosmic rays and make it easier to capture neutrinos.

Going 700 meters underground is not that easy. Scientists and workers in the laboratory have to take a small train and travel along the 1,300-meter inclined shaft tunnel for nearly 20 minutes to reach the JINO.

Why is the JINO built in Jiangmen, Guangdong?

Nuclear reactors are the most concentrated places on Earth that produce neutrinos. Guangdong’s Jiangmen is 53 kilometers away from both Yangjiang and Taishan nuclear power plants. After the two plants were fully completed, the total power ranks first in the world, and the experimental samples can be doubled. Thus Jiangmen can be credibly described as the most suitable place in the world for neutrino experiments.

The JINO has been built for 10 years. Scientists, engineers, construction workers, and logistics personnel are all doing heavy, but extremely romantic jobs. They stand 700 meters deep underground and look up at the starry sky.

The plexiglass ball in the JINO will be filled with liquid scintillator next year, and no human will set foot in it again in the next twenty or thirty years. The ball will be like a match in the dark, quietly waiting for the neutrino to strike it.

What secrets of the universe can be unlocked here? Let's look forward to it!

Author: Ariel

Editor: Olivia, Steven, Will, James

Photo: CCTV, Jiangmen Fabu, Jiangmen Daily