700 meters underground in Jiangmen, Guangdong Province, deeply hides the most complex super equipment ever built in China, the Jiangmen Neutrino Experiment Station, which is an artifact that will raise the level of Basic Research in China, and even the future breakthroughs in physics and the ultimate mystery of the universe are hidden here.
Since the neutrino was first discovered in 1956, it has ruthlessly upended our understanding of the material world, and the United States has even stopped other major experiments other than the Large Particle Collider for it, focusing on it.
So what are neutrinos?
It is an extremely small elementary particle, and each of us is penetrated by trillions of neutrinos almost every moment without any sensation, because it is so small, smaller than the gap that makes up the particles of our human body.
What magic does such a small neutrino have that can make China and the United States invest heavily in it? Why was the Jiangmen Neutrino Experimental Station built at a depth of 700 meters underground? What is the use of catching neutrinos for China?
This is the third issue of the "Measuring China with Technology" series, we are the pop brothers who love to think, pay attention to and long press likes, take you to broaden your horizons, and appreciate the unknown map of Chinese science and technology.
<h1 class="pgc-h-arrow-right" data-track="14" > underground super equipment</h1>
Jiangmen neutrino experiment renderings, the glass ball in the picture is about 40 meters high (more than a dozen floors)
Jiangmen Neutrino Experiment Station in Jiangmen, Guangdong Province, 700 meters deep under the Kaiping Stone Mountain, dug a 40-meter-high hole, the hole is supported by a 1,000 tons of stainless steel structure to support a huge plexiglass ball, the ball contains 20,000 tons of the world's most transparent liquid scintillator to detect neutrinos, how transparent? The dust mixed with the 20,000-ton liquid should not exceed 0.1 grams, otherwise all of them will be unqualified. The entire glass ball detector is immersed in 35,000 tons of super pure water, and around the ball, 45,000 photoelectric eyes are staring at the front, waiting for the ghosts from the universe to cast their nets.
Inside the Japanese Kamika neutrino detector
In the face of such a magnificent and gorgeous heavy weapon, I believe you must have a lot of questions, how does it capture the ghost neutrino, why is it built at a depth of 700 meters underground? What are those 45,000 beautiful eyes?
<h1 class="pgc-h-arrow-right" data-track="37" > capture principle</h1>
Photomultiplier tube
When the neutrinos from the outside enter the glass sphere detector, as long as there is a neutrino acting with a liquid scintillator, it will emit a faint fluorescence. This fluorescence is indistinguishable to the naked eye, and we must use optics, and these 45,000 beautiful eyes on the periphery are actually photomultiplier tubes, which can amplify this faint flash by 10 million times, so that we can see neutrinos.
However, it is not so simple, the probability of neutrinos interacting with liquid scintillators is extremely low, neutrinos have strong penetration, it hardly interacts with any matter, even if there are 10 trillion solar neutrinos passing through the earth, at most only 1 can interact with the earth. Therefore, in order to improve the probability of capture, the detector of the Jiangmen Neutrino Experimental Station was simply made into a capacity of 20,000 tons.
Extremely penetrating makes neutrinos extremely difficult to capture
However, light is not enough, since the liquid scintillator can produce flash with neutrinos, it can also interact with other radiation, on Earth, mountains and rivers and trees can produce radiation, while there is cosmic ray interference from outer space, if these can also enter the glass ball, the tens of thousands of photoelectric eyes have to be busy blind.
So we set the site at a depth of 700 meters underground, relying on deep rocks to block most of the radiation interference. At the same time, 35,000 tons of super pure water were refined to soak the glass ball.
All you see now is a 40-meter cave 700 meters underground
After this series of anti-jamming technologies, cosmic rays have been forcibly reduced by 200,000 times, and even so, 20,000 tons of liquid scintillators can still detect 100,000 cosmic rays per day, compared with only more than 150 neutrinos detected every day. Research work is still difficult.
<h1 class="pgc-h-arrow-right" data-track="40" > the three world highests</h1>
And this study, currently China is in the forefront, Jiangmen Neutrino Experimental Station began to build in 2015, is expected to be completed in 2022, is currently the most cutting-edge experimental station under construction by humans, compared to the United States and Japan's competition program, it has created three world's largest, namely:
1. The world's most transparent liquid scintillator (attenuation length>20 meters);
2. The world's largest plexiglass container (diameter 35.4 meters);
3. There is also the world's most efficient photomultiplier tube (> 30%).
Mass production of 20 inch photomultiplier tubes
Among them, this high-end 20-inch photomultiplier tube has been monopolized by Japan for a long time, the selling price is very expensive, which seriously restricts the development of China's detectors, so led by the Chinese Academy of Sciences, united with the North Night Vision Technology Co., Ltd., after 10 years of research and development, finally broke the monopoly of Japan, the localization rate of 100%, but also became the highest detection efficiency of the international leading products. By 2023, after the experimental station begins to take the number, it is believed that it will once again create a miracle in Daya Bay and usher in a major technological breakthrough.
<h1 class="pgc-h-arrow-right" What's the use of data-track="45" >? You are ignorant! </h1>
The depths of the underground were pitch black
Eh, after watching it for half a day, you may have to ask, is there any practical use for this kind of experiment? The answer is, I really don't know!
The Dongguan underground artifact China spallation neutron source introduced by the Pop Brothers in the early video, it belongs to the scientific application level of equipment, the specific uses are not finished, but the neutrino experiment is a pure category of basic physics research, it needs to endure loneliness, ten years of deep ploughing to see the breakthrough results, but even the breakthrough results, but even the breakthrough results, only theoretical, from the basic science to the transformation of technology, the need for generations of scientists to continue to work.
Now I have to say what is the use, but to give some abstract answers, such as opening the door to study the mystery of the disappearance of antimatter, using its penetration as a celestial probe, studying the planet of the universe and so on.
But in the final analysis, only by studying the nature of neutrinos thoroughly can it be possible to know its true usefulness. It is as if human beings have mastered the theory of atomic nuclei and invented nuclear weapons and nuclear energy, but just imagine, science is a double-edged sword, rather than being the first to make breakthroughs by other countries, it is better to take cutting-edge science into their own hands.
<h1 class="pgc-h-arrow-right" data-track="48" > new scientific research site</h1>
There is no doubt that with the blessing of the heavy equipment of a big country, Jiangmen will cultivate an international leading scientific research team, so that China's basic physics research will be at the forefront of the world, and will also promote the technological innovation of domestic supporting enterprises and achieve the goal of a scientific and technological power.
And such a large project settled in Jiangmen, will also promote the development of Jiangmen, to a small extent, the holding of international conferences, the introduction of high-end talents, the development of tourism, etc. will flourish, to the larger extent, Jiangmen's international influence will be further enhanced, maybe the future here is a new international scientific research holy land.
So, you might as well re-recognize this historic and vibrant city. Although Jiangmen's fame is no better than that of Guangzhou and Shenzhen, it is a place rich in celebrities:
Academic Liang Qichao Liang Sicheng father and son from Jiangmen, the father of China Aviation Feng Ru, the founder of China's anti-epidemic cause Wu Liande from Jiangmen, and the literary and art circles, Jiangmen is known as the hometown of Chinese film and television stars, giving birth to more than 120 performing arts stars including Zhou Runfa, Andy Lau, Zhen Zidan, Liang Chaowei and so on.
Jiangmen talents: academic culture and sports are blooming
Jiangmen can be used as the next attraction you travel, and personally feel the unique scenery of Jiangmen.
There is a Kaiping Diaolou that integrates defense, residential buildings and Chinese and Western art, taking you to appreciate the cultural impact of Western architecture into the Chinese countryside.
There is also the earthy stone, the surging shimi-kamigawa island;
and the intoxicating bird paradise of the writer Barkin;
The 400-year-old banyan tree holds up a bird paradise
When you are tired of playing, you can also go to Xinhui and taste the sweet aroma of Chen Pi Pu'er tea.
Maybe even have the opportunity to enjoy the spectacular scene 700 meters below the neutrino experiment station.
The first two issues of the "Science and Technology on China" series of videos we talked about the Dongguan underground artifacts and Fujian Dragon Axis Group, this video we endorse the future of scientific research holy land Jiangmen, the next issue of which city's science and technology story do you want to see?
Measuring China with Science and Technology
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