In 1988, the Beijing Electron-Positron Collider (BEPC) was completed. Zhang Wenyu, along with engineering manager Xie Jialin (second from the right), deputy manager Chen Senyu (first from the right), and chief engineer Xu Shaowang (first from the left), are seen here discussing inside the storage ring tunnel.
Installed Beijing spectrometer successfully.
The storage ring of the Beijing Electron-Positron Collider (BEPC) project has been successfully installed.
During the construction of the Beijing Electron-Positron Collider, researchers installed main drift chamber signal wires on the Beijing Spectrometer.
Central Control Room of the Beijing Electron-Positron Collider.
After the stagnation of the "Project 87", physicists in high-energy physics collectively worked on devising solutions to address the issues.
At a little past 5 a.m. on November 18, 2006, after significant modifications, the Beijing Electron-Positron Collider successfully accumulated electron beams in the storage ring, a moment recorded by researchers in the control room. The images provided were all from the interviewee.
"I believe this will not be wrong!" On October 7, 1984, at the groundbreaking ceremony of the Beijing Electron-Positron Collider held at the Institute of High Energy Physics of the Chinese Academy of Sciences (hereinafter referred to as IHEP), Comrade Deng Xiaoping said so.
That day, Comrade Deng Xiaoping placed the first shovel of soil on the foundation stone of the collider. Zhang Wenyu, the director of IHEP at the time, held his hand and exclaimed excitedly, "My lifelong wish has finally come true today!"
Forty years later, reflecting on the groundbreaking ceremony, the eyes of researcher Zhang Chuang were somewhat moist: "That day, many people waited a lifetime."
Since the 1950s, Chinese scientists have been troubled by the lack of a high-energy physics accelerator in China, with research relying on foreign data for a long time. They always had a dream—to conduct cutting-edge research with their own accelerator. In the midst of turbulence, this dream was ignited seven times and extinguished seven times. The groundbreaking ceremony symbolized that their dream had finally come true.
In just four years, Chinese scientists built the first large-scale scientific device in China—the Beijing Electron-Positron Collider—at a speed that amazed their international peers. And over the next 40 years, the continuous output of scientific achievements, the growing talent pool, and the solid establishment of Chinese high-energy physics have all confirmed Comrade Deng Xiaoping's words: this matter is not wrong.
In March 1975, when the weather was still chilly despite the early signs of spring, Zhang Chuang, working at the Beipiao Mining Bureau in Liaoning Province, seized the opportunity of a business trip to Beijing to visit his university professor, Professor Zhang Li, at Zhongguancun. Zhang Chuang had studied particle accelerators in the Department of Engineering Physics at Tsinghua University and maintained close contact with his professor even after being assigned to work in the coal mines.
Upon knocking on the door and sitting down, before they could exchange pleasantries, Professor Zhang Li excitedly told Zhang Chuang some news: "Premier Zhou has given instructions, and high-energy physics is going up!"
Professor Zhang Li's voice was not loud, but it shook Zhang Chuang. It was like a key, unlocking a long-closed door in Zhang Chuang's heart.
Let's go back three years.
On August 18, 1972, Zhang Wenyu, Zhu Hongyuan, Xie Jialin, and 18 other scientists wrote a letter to Premier Zhou, complaining: "High-energy physics experiments are almost blank, and theoretical research relies entirely on foreign experimental data."
High-energy physics research is at the forefront of understanding the microstructure and motion laws of matter, and high-energy accelerators and corresponding detection devices are important tools for this frontier research.
Shortly after the founding of the People's Republic of China, in October 1950, physicists at the Chinese Academy of Sciences proposed to build a particle accelerator for nuclear physics experiments. In 1953, the world's first high-energy accelerator appeared in the United States, and older Chinese physicists such as Zhao Zhongyao, Zhang Wenyu, and Wang Ganchang began efforts to build China's high-energy accelerator. However, the changes in political winds and the fluctuations of the national economy caused this dream to be "launched" and "cancelled" many times.
In their letter, they appealed: "Quickly determine the policy direction for the development of high-energy physics, and organize to ensure it. Establish a high-energy physics research institute as soon as possible and assign it to the competent authority responsible for basic theoretical research."
On September 11, 1972, Premier Zhou Enlai instructed: "This matter cannot be delayed any longer. The Chinese Academy of Sciences must grasp basic science and theoretical research, while also combining theoretical research with scientific experiments."
On February 1, 1973, under the concern of the leaders of the Party and the state, the Institute of High Energy Physics of the Chinese Academy of Sciences was established. In Zhang Chuang's mind, it was once a "hall" that seemed unattainable.
Two years later, in March 1975, after in-depth research by scientists at IHEP, they submitted a report to the State Council titled "Report on the Prefabrication Research and Construction of High-Energy Accelerators", which explicitly proposed to build a 40 billion electron volt proton synchrotron accelerator within 10 years.
Premier Zhou reviewed and approved the report while lying in a hospital bed. Subsequently, the prefabrication research project for high-energy accelerators had its own code name—"753 Project".
"The school has recommended students who graduated in accelerator specialty to IHEP, and your name is on the list," Professor Zhang Li told Zhang Chuang. To meet the needs of the "753 Project", IHEP began to gather relevant professionals scattered across the country.
That day, when Zhang Chuang walked out of his teacher's house, the fatigue of the business trip was swept away. At this time, the branches on the roadside were still somewhat bare, but flowers had already bloomed in Zhang Chuang's heart—a dream he and his teachers had long awaited.
In the autumn of 1976, scientists, full of confidence, re-evaluated the "753 Project" plan and proposed the more ambitious "87 Project" plan, which was approved by the state.
The "87 Project" was divided into three steps: the first step, with a budget of 300 million CNY, was to build a 30 billion electron volt slow-pulse proton circular accelerator; the second step, with a budget of 700 million CNY, aimed to complete the 40 billion electron volt proton circular accelerator by the end of 1987; the third step, by the end of the 20th century, aimed to build a world-class high-energy accelerator.
However, not long after, due to adjustments in China's national economy and the tightening of infrastructure construction, the high-energy proton accelerator was listed as "cancelled" because it was not deemed a "national urgent need"—this was already the seventh "cancellation" of the project. Upon hearing the news, older scientists like Zhang Wenyu and younger ones like Zhang Chuang were anxious.
In May 1980, Zhang Wenyu, Zhao Zhongyao, Zhu Hongyuan, and 39 other high-energy physicists jointly petitioned, pleading for the "87 Project" not to be "cancelled". Comrade Deng Xiaoping instructed: "This matter has too great an impact and should not be 'cancelled'." This batch left an opportunity for Chinese scientists. Despite the engineering being stalled, there's still hope.
Everyone is reconsidering accelerator schemes more suited to the national situation, moving towards the eighth hope.
In 1981, due to the stagnation of the "Project 87," the Sino-American High Energy Physics Joint Conference failed to take place as scheduled. Upon learning of this, Chinese-American physicists Yuan Tseh Lee and Tsung-Dao Lee, along with their spouses, were deeply concerned. They suggested to national leaders to immediately send experts to the United States for discussions.
In March 1981, Zhu Hongyuan and Xie Jialin from the Institute of High Energy Physics of the Chinese Academy of Sciences went to the United States for discussions. They, along with Tsung-Dao Lee, Yuan Tseh Lee, and American high-energy physicists like Panofsky, discussed the prospects of high-energy physics in China. Eventually, everyone unanimously agreed that building a 2×2.2-billion-electron-volt electron-positron collider in China was the best option.
The new plan, costing only a third of the "Project 87," not only enriched the physics content but also allowed for simultaneous research on synchrotron radiation applications, achieving "dual-use" capabilities.
However, when Zhu Hongyuan and Xie Jialin brought this plan back to China, a fierce debate began.
Developing a collider posed significant technical difficulties and risks. Making two extremely thin, high-speed, and sparse electron beam bunches collide accurately and fully was challenging. There were various concerns: "Can China do it?" "Even if it's developed, will it meet performance standards?" "What if the progress delays and the physics window closes?"
Some even made an analogy: "With China's weak foundation at the time, building an electron-positron collider was like standing on a railway platform, trying to jump onto an oncoming express train. If you catch it, you move forward, but if you miss, you'll be crushed."
In September 1981, the Mathematical and Physical Sciences Department of the Chinese Academy of Sciences held the "Fengtai Conference" for three days to discuss. Meanwhile, the Institute of High Energy Physics also organized several seminars internally. Everyone was seeking the most practical solution for the future of national high-energy physics.
The discussion continued until the end of 1981. During this period, the Chinese Academy of Sciences sent Deng Zhaoming, then head of the relevant department within the academy, along with Xie Jialin and Zhu Hongyuan, back to the United States. With the insistence of Tsung-Dao Lee and others, after nearly an hour of negotiation with the academy leadership over the phone, Deng Zhaoming and the academy leadership approved the plan for the electron-positron collider.
On December 5, 1981, the Chinese Academy of Sciences submitted the "Report on the Prefabricated Research of Building the Beijing Electron-Positron Collider" for approval. After reviewing the report, Comrade Deng Xiaoping instructed: "This project has progressed to this extent and should not be interrupted. The guidelines they proposed are relatively feasible. I agree to approve it without hesitation."
In April 1983, China officially approved the Beijing Electron-Positron Collider project, scheduled to be completed by the end of 1988.
Guxu, who served as the leader of the Beijing Electron-Positron Collider project, once remarked, "This instruction injected vitality into China's high-energy physics industry, liberating it from crisis."
Jumping onto the "express train"
On the morning of October 7, 1984, at 10 o'clock, flags fluttered in the Institute of High Energy Physics in the western suburbs of Beijing on Yuquan Road. Deng Xiaoping, Yang Shangkun, Wan Li, Fang Yi, and other party and state leaders, as well as scientists who had come from the United States specifically for this occasion, gathered here. The long-awaited construction of the Beijing Electron-Positron Collider finally began.
Next, scientists would have to "jump" onto the international high-energy physics "express train" in four years or even less.
The Beijing Electron-Positron Collider consists of injectors, transport lines, storage rings, Beijing spectrometers, synchrotron radiation devices, and other parts. The project involves tens of thousands of specialized equipment, with complex technology and extremely high precision, which China had never done before. The project encountered key issues from the start: whether to fully introduce or independently develop the technology?
As the leader of the project leadership group, Gu Yu led the group to carefully analyze China's scientific and industrial situation. It was ultimately decided, except for computers and a few equipment that China was unable to develop at the time, and some components and materials with minimal usage and not worth the manpower and resources to develop, to mainly rely on our own strength for design and development.
To create an extreme particle collision environment, the technical indicators of various equipment for the Beijing Electron-Positron Collider approached the limits. Among them, technologies involving high-power microwaves, high-performance magnets, stable power supplies, ultra-high vacuum, etc., almost exceeded the technological capabilities at the time.
For example, to accelerate electrons in the collider, stable microwave electromagnetic fields are needed, and a component called the "S-band high-power klystron" is the "heart" of the microwave magnetic field electron system. At that time, the domestically produced S-band high-power klystron with the highest technological level had a pulse output power of 15 to 20 megawatts, which was far from meeting the requirements of the collider project.
Therefore, researchers from the Institute of High Energy Physics and factories worked together, absorbing and digesting all the production processes from abroad in the early 1980s. They transformed the original production lines, not only increasing the microwave power of the klystron to 34 megawatts but also raising the power of domestically produced modulators from 50 megawatts to 100 to 200 megawatts, and extending the working life from 1,000 hours to 10,000 hours.
This breakthrough not only met the technical requirements of the collider for high-power, high-stability, and long-life microwave power sources but also enabled major accelerator projects during China's "Eighth Five-Year Plan" period, such as the Hefei Synchrotron Radiation Source, Beijing Free Electron Laser, Shanghai Free Electron Laser, to gradually use domestically produced microwave power sources and special waveguide components. Similar breakthroughs occur frequently in the development of particle colliders. In order to construct a collider, China has reached higher levels of technological expertise in areas such as vacuum technology, electromagnets, and high-power stable power supplies. Additionally, the Institute of High Energy Physics (IHEP) completed China's first international computer communication line in 1987, paving the way for China's participation in the construction of the "international information superhighway."
One day in October 1988, Ye Minghan, then director of IHEP, approached Zheng Zhipeng, in charge of the construction, installation, and debugging of the Beijing Spectrometer (BES).
"We are about to start high-energy talks with the United States, and American experts are in Beijing. If we could achieve positron-electron collision at this time, it would be an appropriate moment," Ye Minghan said.
Zheng Zhipeng immediately gathered his colleagues responsible for the luminosity detector to discuss how to distinguish between signals and noise. After several days and nights of continuous debugging, they gradually understood the "temperament" of the device.
In the early hours of October 6, 1988, when the Beijing positron-electron collider was in collision mode, the luminosity monitor displayed scattered signals of positrons and electrons, with the count increasing over time. When the collider was switched from collision mode to single-beam mode, the signals disappeared. After numerous repetitions, they finally confirmed, "We collided."
In the hall, everyone jumped for joy, and the fatigue of the night vanished. Ye Minghan, upon hearing the news, arrived at the control room and the spectrometer hall at daybreak to confirm the fact that positron-electron collision had been achieved.
The good news quickly spread throughout IHEP and then across the country through the media.
On October 24, 1988, after a refreshing autumn rain in Beijing, comrade Deng Xiaoping once again visited IHEP. On this day, the Beijing positron-electron collider was announced to be successfully constructed!
"Whether in the past, today, or in the future, China must develop its own high technology and occupy a place in the world of high technology," comrade Deng Xiaoping said at the completion ceremony.
In just four years, Chinese scientists truly boarded the fast-moving train of international high-energy physics.
"The success of the collider is an important milestone in the development of China's science and technology," remarked Nobel laureate physicist Rickert.
From then on, the era of China's major scientific plans officially began.
In 1990, after more than a year of debugging, the Beijing positron-electron collider officially began operation.
It quickly became a "treasure trove" for basic research in high-energy physics in China. With the data it produced, Chinese scientists achieved a number of influential research results in the international high-energy physics community: achieving the most accurate measurement of the tau lepton mass to date; achieving precise measurements of the cross-section (R-value) of positron-electron collision in the energy range of 2 to 5 billion electron volts; discovering a new resonance state at the mass threshold of "proton-antiproton"; discovering the new particle X (1835)...
At the turn of the century, international competition in high-energy physics became increasingly fierce, and the Beijing positron-electron collider had been in operation for 10 years. Chinese scientists had a new idea: upgrade!
Chen Hesheng, then director of IHEP, had been closely following the development of international frontiers in high-energy physics. In 2000, the "Development Goals of Chinese High-Energy Physics and Advanced Accelerators," which he chaired, received the principle agreement of the national science and technology leadership group, including a major overhaul of the Beijing positron-electron collider.
Upon hearing this news, the Cornell University team, which operated the Cornell Electron-Positron Storage Ring (CESR), felt threatened. They claimed that they would use a "short, flat, fast" approach to upgrade CESR, expecting to achieve the same performance indicators as the upgraded Beijing positron-electron collider two years earlier.
This was tantamount to a "declaration of war." "When two armies meet, the brave one wins!" Chen Hesheng told the researchers around him. After repeated discussions with international experts, they found that Cornell University's plan might not be achievable, while the Chinese design could definitely be accomplished with effort.
They decided to face the challenge head-on, making significant adjustments to the upgrade plan for the Beijing positron-electron collider (BEPCII), adopting an internationally advanced double-ring scheme. The plan aimed to increase the performance of the Beijing positron-electron collider by 100 times, in order to gain the initiative in international competition.
In January 2004, BEPCII officially started construction, including injector renovation, construction of a double-ring storage ring collider, construction of the Beijing Spectrometer III, and renovation of general facilities, among other aspects.
Thus began an intense international competition.
In addition to IHEP, other institutions such as the University of Science and Technology of China, the Institute of Physical and Chemical Research of the Chinese Academy of Sciences, the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, the Shanghai Institute of Ceramics of the Chinese Academy of Sciences, the Shanghai Institute of Applied Physics of the Chinese Academy of Sciences, and related non-institutional research institutions and enterprises participated, forming a systematic research force.
In five years, they raised the luminosity and comprehensive performance of the Beijing positron-electron collider to the international leading level, with over 85% of the engineering equipment being independently developed.
The upgraded Beijing positron-electron collider achieved precise collision of micrometer-sized high-intensity beam bunches, with a peak luminosity about 100 times that before the upgrade. Coupled with the improvement in detector performance and operational efficiency, the daily integrated luminosity increased by more than 100 times compared to before the upgrade.
By the completion of the BEPCII project in 2009, the collider at Cornell University only achieved a quarter of its design specifications and had to be shut down. Many high-energy physicists who conducted experiments on that collider joined the Beijing Spectrometer III collaboration.
"This is another major leap forward in China's experimental research in high-energy physics, laying a solid foundation for China to continue to lead the world in research on charm physics and high-energy research on the tau lepton," commented Li Zhengdao.
Higher performance leads to more fruitful scientific research. In March 2013, the Beijing Spectrometer III collaboration announced the discovery of a new resonance structure, Zc(3900), which is highly likely to be the "tetraquark matter" that scientists have long been searching for. It was selected as one of the eleven important achievements in the field of physics for 2013 by the American journal "Physics," ranking first. From its operation in 2008 to the end of June 2015, they also observed new particles X(1870), X(2120), X(2370), etc. In the realm of scientific research, young physicists in the field of high-energy physics are also growing. A continuous stream of excellent doctoral candidates and postdoctoral researchers is being supplied to various research institutions and universities nationwide, injecting fresh blood into the development of high-energy physics in China.
Reflecting on this, Wang Yifang, the current director of the Institute of High Energy Physics, remarked, "In hindsight, the decision to build the Beijing Electron-Positron Collider was the best choice at the time. It has enabled Chinese high-energy physics to have a presence in the international arena, nurtured a team with international standards, and propelled the construction of other major scientific facilities domestically."
As of today, renovations of the Beijing Electron-Positron Collider are still ongoing. "We are currently refurbishing the accelerator section to triple its luminosity. After this, we expect the Beijing Electron-Positron Collider to operate until around 2030," Wang Yifang stated.
To many observers, the construction of the Beijing Electron-Positron Collider represents the collective efforts of several generations of technologists and is an achievement made possible by the concerted efforts of many institutions nationwide, also benefiting from international cooperation following the reform and opening-up policies.
In Wang Yifang's view, the "lessons" left behind by the Beijing Electron-Positron Collider include considerations such as "comprehensively assessing the forefront scientific goals, national capabilities and needs, and the development objectives of the discipline when choosing construction plans for facilities," "daring to accept challenges and competition from the international community," "domestic experimental facilities always being a solid foundation for consolidating and enhancing international status," "construction plans for facilities should strive to accommodate the needs of other disciplines as much as possible," and "adhering to a combination of independent innovation and international cooperation."
Looking back, the beginnings of high-energy physics in China were arduous and full of twists and turns, but scientists never lost hope and passion. The setbacks and glories of the past have shaped the courage and temperament of Chinese high-energy physicists. They have also accumulated invaluable experience for future generations—persevering in adversity and advancing with hope.
(Intern Kang Yuxuan also contributed to this article)
