In the science fiction TV series "Three-Body Problem", the "Three-Body Man" affects the operation of particle accelerators on the earth through their own technology, which ultimately makes the results of the experiment irregular. The particle accelerator that appears in the TV series is my country's first particle accelerator. A large scientific facility—Beijing Electron Positron Collider (BEPC). What does the
collider device look like? What can it do for us? What kind of scientific research sparks has such a large machine "crash" out?
01
The Institute of High Energy Physics, Chinese Academy of Sciences, is one of the filming locations for the TV series "Three Body". The Beijing Electron Positron Collider is placed underground in a building on the west side of it, covering an area of 57,500 square meters.
Chen Hesheng, an academician of the Chinese Academy of Sciences and director of the Beijing Electron Positron Collider National Laboratory, said that the working principle of the Beijing Electron Positron Collider is to achieve collision of electrons and positrons after acceleration.
Chen Hesheng: It will generate 1.5 billion to 2 billion electron volts of electrons and positrons, and then collide at the collision point. We have a large detector called the Beijing Spectrometer, which covers this collision point and records all the particles produced. Then we can know what kind of scientific phenomena are produced by the physical process of the collision.
△ Chen Hesheng, academician of the Chinese Academy of Sciences and director of the Beijing Electron Positron Collider National Laboratory
This large scientific device consists of a 202-meter-long linear accelerator, a transport line, and a 240-meter-circumference circular accelerator (also called a storage ring) It consists of several parts, including the 6-meter-tall and 500-ton Beijing spectrometer and the synchrotron radiation experimental device surrounding the storage ring. From a bird's eye view, the installation looks like a huge badminton racket.
Chen Hesheng: First use a linear accelerator to generate electrons, and then use a target to generate positrons. To accelerate its energy to 2 billion electron volts, a length of 200 meters is required, and it is accelerated by accelerating tubes. The "racquet" is a storage ring with a circumference of 240 meters. One ring each for positrons and negative electrons, which collide at the collision point.
The Beijing spectrometer is the core component and is also the place where information generated by the collision of electrons and positrons is obtained. Wang Zheng, a researcher at the Institute of High Energy Physics of the Chinese Academy of Sciences, said that the Beijing spectrometer is like the shutter of a camera, which can accurately detect particles obtained after the collision of electrons and positrons. The
accelerator was once vividly known as the "atom crusher". It is a tool for physicists to understand the composition and movement laws of microscopic matter. It has been serving mankind for nearly a hundred years.
Chen Hesheng said that the Beijing Electron Positron Collider studies the interaction rules of the smallest units that make up matter. “According to the latest developments in physics, the smallest units that make up the material structure of the universe are smaller than protons and neutrons. There are quarks that are one level smaller, electrons, muons of cosmic rays, and various neutrinos. The research scope covers different energy regions, and the range of 3 billion to 4 billion electron volts is our bepc research. "
02
As my country's first large-scale scientific facility, the Beijing Electron Positron Collider embodies the efforts of several generations.
On October 7, 1984, the Beijing Electron Positron Collider finally broke ground. Not everyone was so sure at first. Someone made an analogy: "With China's weak foundation at that time, trying to build an electron-positron collider was like standing on a railway platform and trying to jump on a speeding express." If you jump on the train, it will fly forward. If you don't catch it, you will fall off and be shattered! "
It took four years for Chinese scientists to overcome technical problems one by one and finally build the Beijing Electron Positron Collider on their own.
△Aerial view of Beijing Electron Positron Collider
The success of the collider caused a sensation. In 1990, after more than a year of debugging, the collider was officially put into operation and became a "treasure land" for high-energy physics research in China. A number of international Important results that had an impact on the high-energy physics community were born.
In 1992, the Beijing Electron Positron Collider improved the mass measurement accuracy of Tao leptons by nearly an order of magnitude, allowing my country to occupy a leading position in this field. To this day, some new physics knowledge that has caused a stir at home and abroad has been obtained based on this device. Results.
It is worth mentioning that this machine can also be used for "two purposes." A synchrotron radiation device is installed in the tangential direction of the "racquet". The laboratory can carry out experiments related to synchrotron radiation. Research on uncovering the structure of the main protease of the SARS virus, searching for the nemesis of the SARS virus, and revealing the mechanism of arsenic treatment of leukemia at the molecular level are all conducted through synchronization. The radiation device is completed.
03
Even though it is 36 years old, the collider, which has undergone several modifications, is still a first-class device in its field.
Chen Hesheng: We have recently made a very important discovery - gluon balls. The gluon ball is a key particle predicted by the basic theory of particle physics. It has not been found in the past. A few months ago, based on various experimental results, we believe that we have found a candidate for this particle. This is a breakthrough in particle physics. A major breakthrough.
Currently, scientists are modifying its accelerator part, which will increase its brightness by three times in the high-energy section and is expected to operate until about 2030.
Chen Hesheng has been asked countless times: What is the use of studying the collision of electrons and positrons?
He replied: "Today's science is tomorrow's technology. Together with other particle physics research in the world, it will make an important contribution to our understanding of the microstructure of the universe."
(China Central Radio and Television China (voice)
