There is a "light" that illuminates the past and the future

Focus:

• 1 The original synchrotron radiation light source is "parasitic" on the particle collider, and it is based on the existing particle accelerator to carry out synchrotron radiation research, which is the first generation of synchrotron radiation light source we say;
• 2 The second generation light source is a dedicated synchrotron radiation light source, which no longer relies on particle colliders and particle physics research;
• 3 The third generation of light sources uses a large number of inserts, which improves the performance of synchrotron radiation. At present, synchrotron radiation light sources have been developed to the fourth generation;
• 4 The fourth generation of light sources is based on diffraction-limited storage ring technology, and the electron beam emissivity is 1-2 orders of magnitude lower than that of the previous generation, approaching or even reaching the diffraction-limited emissivity of X-rays, while the average brightness is higher.

It was reported on March 18 that recently, the "13th Five-Year Plan" national major scientific and technological infrastructure high-energy synchrotron radiation light source (HEPS) linear accelerator full energy beam out, successfully accelerated the first electron beam, HEPS entered the parallel stage of scientific research equipment installation and beam regulation. HEPS linear accelerator is a room temperature linear accelerator, about 49 meters long, used to generate electrons, accelerate electrons to 500MeV, is the source of electrons and the first stage accelerator, by the end of the electron gun, beam cluster, acceleration structure, microwave power source and other equipment.

Synchrotron radiation has a history of more than 70 years since it was first discovered, from being "disliked" at the beginning to being "sought after" now, and people's attitudes towards synchrotron radiation have also undergone a huge change. The original synchrotron radiation light source was "parasitic" on the particle collider, and it was based on the existing particle accelerator to carry out synchrotron radiation research, which is what we call the first generation of synchrotron radiation light source. The second generation of light sources is a dedicated synchrotron radiation source that no longer relies on particle colliders and particle physics research. The third generation of light sources uses a large number of inserts, which improves the performance of synchrotron radiation. At present, synchrotron radiation light sources have been developed to the fourth generation.

China has also experienced four generations of synchrotron radiation. At that time, in 1977, the construction of synchrotron radiation devices was included in the national science and technology development plan; At this time, on March 14, 2023, the "13th Five-Year Plan" national major scientific and technological infrastructure, China's fourth generation of synchrotron radiation light source - high-energy synchrotron radiation light source (HEPS) linear accelerator full energy beam, successfully accelerated the first electron beam, which is another important milestone in the construction of HEPS devices and an important milestone in the development of synchrotron radiation in China. In this issue, we will talk about the development process of synchrotron radiation light sources in China.

Inside the HEPS linear accelerator tunnel (Image source: Institute of High Energy Physics, Chinese Academy of Sciences)

The first generation: Beijing synchrotron radiation device - a light source "parasitic" on the Beijing electron-positron collider

In August 1972, Zhang Wenyu and 18 other scientific and technological workers wrote a letter to Premier Zhou Enlai, expressing their opinions and hopes for the development of high-energy physics research in China. On September 11, 1972, Premier Zhou Enlai instructed in his reply: "This matter cannot be postponed any longer... High-energy physics research and prefabricated research of high-energy accelerators should become one of the main projects to be grasped by the Academy of Sciences. In October 1988, the Beijing Positron Collider was built at the Institute of High Energy Physics of the Chinese Academy of Sciences. Three years later, in 1991, the Beijing Synchrotron Radiation Facility (BSRF) was established. Synchrotron radiation is drawn out from multiple points, along the tangential direction, and the corresponding laboratories are set up around the accelerator.

Premier Zhou replied (Image source: Institute of High Energy Physics, Chinese Academy of Sciences)

At the beginning of its construction, the Beijing synchrotron radiation device was open to users, and the research content involved different disciplines and fields such as material science, condensed matter physics, chemistry, chemical engineering, life science, medicine, geology and mining, resources, environmental science, microelectronics and micromechanical technology, etc., and has produced many important scientific research results since its operation for more than 30 years. In June 2003, the research group led by Professor Rao Zihe of Tsinghua University built the first domestic protein crystal structure research beamline and experimental station at the end of 2002 to crack the crystal structure of the main protease of SARS coronavirus, and then used synchrotron radiation experiments to obtain effective drug target molecules for the development of treatment of SARS Viral drugs provide important information.

As the first large-scale synchrotron radiation device built and put into use in the mainland, Beijing synchrotron radiation device has been successfully operating for more than 30 years, although it is the first generation of synchrotron radiation light source, but after continuous improvement and upgrading, its performance has been close to the second generation of synchrotron radiation light source. Today, this "backward" light source is still producing results, which can be described as old and strong!

Schematic diagram of the beamline and test station of the Beijing synchrotron radiation device.

The second generation: Hefei synchrotron radiation source - specially designed for synchrotron radiation applications

The main disadvantage of the first generation of synchrotron radiation light source is that it is "parasitic" on the particle accelerator, and the main task of the particle accelerator is to carry out high-energy physics experiments, which cannot operate according to the requirements of synchrotron radiation, and the actual time to carry out experiments is greatly limited. Therefore, the Beijing synchrotron radiation device only has about 3 months of consumption time a year, which is far from meeting the needs of scientific research. At this time, China's second generation of synchrotron light source, Hefei synchrotron radiation light source, is specially designed for the application of synchrotron radiation.

In fact, Hefei synchrotron radiation light source and Beijing synchrotron radiation light source are basically built at the same time, completed in 1989, which is also the mainland's first independently built dedicated synchrotron radiation light source, its dominant energy area is vacuum ultraviolet and soft X-ray band, electron beam energy up to 0.8GeV, natural emissivity less than 40nm • rad (although we expect all electrons to move on the same orbit in the storage ring, but in reality there will always be deviations, real electrons mostly deviate from the ideal orbit, Therefore, the electron beam group has a certain size and divergence angle, and the results of these two are called "emissivity", obviously, the smaller the emissivity, the more concentrated the light, the better the light source performance).

Although it is the second generation of light source, after all, the construction time is relatively early, and like the Beijing synchrotron radiation device, the performance and machine time provided by Hefei synchrotron radiation light source are far from meeting the needs of scientific research. In addition, the energy of Hefei light source is low, mainly for vacuum ultraviolet and soft X-ray research, can not produce hard X-rays.

Hefei Light Source Synchrotron Radiation Hall (Image source: National Synchrotron Radiation Laboratory, University of Science and Technology of China)

A corner of the storage ring of Hefei synchrotron radiation light source (Image source: National Synchrotron Radiation Laboratory, University of Science and Technology of China)

The third generation: Shanghai synchrotron radiation light source - a special light source with low emissivity and a large number of inserts

By the 90s of the 20th century, the third generation of synchrotron radiation light sources has appeared internationally, this generation of light sources use a large number of inserts - a series of periodically arranged north and south pole magnet groups, the emission of the light source is very small, the number is stable for a long time, the brightness is very high, and the quality in polarization and coherence is also superior.

In December 2004, Shanghai synchrotron radiation light source started construction and opened for operation in 2009, which is the first third-generation synchrotron radiation light source in Chinese mainland (the third-generation light source located in Taiwan, China-Taiwan light source was completed in 1994). The Shanghai light source increases the energy of the electron beam to 3.5 GeV, while the emissivity is reduced to 4 nm•rad, which is much lower than the Hefei light source.

Shanghai synchrotron radiation light source (Image source: Shanghai Zhangjiang Advanced Light Source Big Scientific Device Cluster)

In addition to the Shanghai light source, DIAMOND in the UK, SOLEIL in France, ALBA in Spain, NSLS-II in the United States are also representative third-generation synchrotron radiation light sources.

At the beginning of 2020, mainland researchers took the lead in analyzing the high-resolution structure of key proteins of the new coronavirus with the help of Shanghai Light Source.

Crystal structure of new crown main hydrolase protein and N3 complex.

The fourth generation: high-energy synchrotron radiation light source - brighter light illuminates the microscopic world

At present, the fourth generation of synchrotron radiation light source has been developed internationally, this generation of light source is based on diffraction limit storage ring technology, electron beam emissivity is 1-2 orders of magnitude lower than the previous generation, close to or even reach the diffraction limit emissivity of X-rays, and the average brightness is higher. In fact, it was not until around 2010 that the key physics and technology breakthroughs of diffraction-limited storage rings made the realization of diffraction-limited storage rings possible. Sirius in Brazil, ESRF-EBS in Europe, APS-U in the United States, etc. are all fourth-generation light sources.

The High Energy Photon Source (HEPS) currently under construction in Huairou, Beijing, is the fourth generation of synchrotron radiation sources. HEPS is approved by the National Development and Reform Commission, and the high-energy institute of the Chinese Academy of Sciences undertakes the construction, which is a major national science and technology infrastructure in the "13th Five-Year Plan", and all preliminary preparations will be completed in mid-2019, and the construction will start on June 29, with a construction period of about 6.5 years, and is expected to be completed and accepted by the end of 2025.

High-energy synchrotron radiation source (HEPS) is a high-performance high-energy synchrotron radiation light source with an electron energy of 6GeV and an emissivity of less than or equal to 0.6 nm·rad, and its primary goal is to provide high-energy, high-brightness hard X-rays, which is to meet the needs of research related to national development strategies, such as aero-engine materials, nuclear materials research must rely on this high-performance X-rays. At the same time, it will also provide a better support platform for the industrial field and the field of basic science. After completion, it will be the first high-energy synchrotron radiation light source owned by China, and it will also be one of the world's brightest fourth-generation synchrotron radiation light sources, which will complement the existing light source in the mainland to form an energy area, which is of great significance to enhance the mainland's national development strategy and the original innovation ability in the field of cutting-edge basic science and high technology.

High-energy synchrotron radiation light source (rendering) (Image source: Institute of High Energy Physics, Chinese Academy of Sciences)

On March 14, 2023, the high-energy synchrotron radiation source (HEPS) linear accelerator successfully accelerated the first electron beam at full energy, which is an important milestone for the high-energy synchrotron radiation light source!

In addition, the Hefei Advanced Light Facility (HALF) proposed by the National Synchrotron Radiation Laboratory of the University of Science and Technology of China is also the fourth generation light source, which is conceptual as a fourth-generation storage ring light source in a low-energy region, which is expected to be completed in 2027. At that time, Hefei Advanced Light Source will become a spatial coherent diffraction limit light source with the highest brightness in the full radiation spectrum. At the same time, relying on Hefei's advanced light source, it will expand the construction of advanced low-energy zone free electron laser devices and the world's only terahertz storage ring light source, so as to jointly form the "Hefei Advanced Light Source" cluster, become the world's leading light source center in the low-energy region, open to domestic and foreign scientists, and provide a public platform for cutting-edge research in the fields of quantum information, energy and environment, and life sciences.

Rendering of Hefei Advanced Light Source (Image source: University of Science and Technology of China)

From the Beijing synchrotron radiation device "parasitic" on the Beijing electron-positron collider to the world's leading high-energy synchrotron radiation light source, China has gone through an extraordinary 30 years in the field of synchrotron light source. As the first light source, the Beijing synchrotron radiation device is still in operation; As the latest light source, high-energy synchrotron radiation light source is just the beginning. More scientific development, let us be full of expectations!

Produced by: Popular Science China

Author: Zigan

Executive Producer: China Science Expo