At 7 AM in the morning twilight, Jiao Yi hurriedly walked from the user service building of the "small ring" at the High Energy Photon Source in Huairou Science City to the accelerator central control room of the "big ring" about 100 meters away. Front-line researchers had already taken their seats, and more than 30 people attending remotely on the big screen were also standing by—this was an ordinary morning meeting during the National Day and Mid-Autumn Festival holidays, but Jiao Yi and his team had already entered "battle mode."
The Phase I construction of the major scientific facility—High Energy Photon Source (HEPS)—will be completed this year and begin trial operation. Throughout the entire holiday, the construction work of the "Big Light Source" continues non-stop with great intensity.
Jiao Yi serves as deputy director of the "Big Light Source" accelerator department, acting as both a "commander" and "firefighter." So far, he has been working continuously for two weeks, and during this double holiday, he still needs to stay at his post. Jiao Yi's beam tuning team works in two shifts—day and night—while Jiao Yi follows the entire process, organizing meetings at 9 AM and 9 PM daily to summarize each shift's beam tuning progress, existing problems, and subsequent plans, connecting the daily and weekly beam tuning work.
Besides "commanding" meetings, he must serve as a "firefighter," ready to mobilize whenever there are coordination matters or emergencies that need resolution.
"Please pay attention to these two matters during the double holidays!" Jiao Yi sat at the conference table, carefully examining the work plan. Inside the central control room, three walls were covered with huge screens displaying constantly fluctuating data parameters. Rows of computers were neatly arranged in the control room, with researchers sitting in front of screens, each precisely controlling different parameters.
Jiao Yi outlined the recent core tasks: "We need to cooperate with beamline commissioning to optimize the performance of each beamline. In the coming days, we need to focus on two things: first, maintain beam stability to provide stable conditions for beamline commissioning; second, closely coordinate with beamline commissioning to precisely adjust the 'insertion devices' on the light source."
He explained to reporters that the storage ring accelerator consists of 48 magnetic focusing structures, with a series of straight sections reserved between these structures where insertion devices and other equipment are installed, with each insertion device corresponding to one beamline.
Jiao Yi used an analogy: "When more than ten beamlines operate simultaneously, almost all related operations need to be coordinated in the central control room. It's like a bus opening its doors with more than ten people wanting to board—we need to ensure everyone can get on while maintaining order."
As soon as the meeting ended, Jiao Yi received a call requesting cooperation with researchers for beam tuning, which is one of the current work challenges. Jiao Yi explained, "Beam tuning means precisely modulating X-rays so that 'customized' light passes through a series of optical elements to reach the experimental station. To achieve this goal, the accelerator needs to slightly 'bend' the electron beam according to beamline requirements, allowing the light generated by the accelerator to pass through the central area of the vacuum pipeline and finally transmit to the experimental area of the beamline."
The "Big Light Source" is one of the world's most advanced major scientific facilities, with extremely complex underlying physics and technical relationships. This slight "movement" involves very complex physical parameter relationships. "For example, when I disturb the beam in one place, other places in the ring are affected—it's like pulling one hair affects the whole body," Jiao Yi described. "Our beam tuning work is about central coordination, keeping all beamlines stable. While adjusting the light position and angle of one beamline, we precisely control the beam orbit to keep the beam orbits in other parts of the ring basically unchanged, with changes controlled at the micrometer level. This is our 'challenge'—everyone must dare to act and strive."
The construction of the High Energy Photon Source has been a long journey. On June 29, 2019, the "Big Light Source" began construction. From 2022 to 2023, equipment installation, alignment, and commissioning work continued. At the end of 2023, the storage ring of the "Big Light Source" achieved closed-loop installation of main equipment. In July 2024, the "racetrack" for high-energy electrons was preliminarily positioned.
Jiao Yi introduced that from July 2024 to now, the light source construction team has mainly been conducting storage ring beam commissioning and beamline commissioning. "The current work is the final and most critical link in the overall light source construction."
Although it's holiday time, due to work progress, Jiao Yi has recently reduced his running exercise time—previously, running two laps around the "Big Light Source" for 4 kilometers was Jiao Yi's habit. "Running is also to recharge myself and build a good physical foundation. After getting through this phase, I'll need to run again."
For Jiao Yi's family, his absence during holidays has become routine. When asked how he coordinates family and work relationships, Jiao Yi frankly said he's most grateful for his family's understanding and support.
Not only Jiao Yi, but during this holiday, about 100 researchers are staying at their posts to serve the "Big Light Source," contributing their light and heat to its construction. Stable beam flow illuminates not just experimental samples, but also the ordinary yet persistent dedication of a group of scientific workers.
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