On January 18th, the Jiangmen Underground Neutrino Observatory (JUNO) project construction summary meeting was held at the project site in Jiangmen, Guangdong. As the world's first next-generation, ultra-large-scale, ultra-high-precision neutrino experiment facility to be completed and put into operation, this "cosmic exploration marvel" buried 700 meters underground announced the conclusion of its construction phase, embarking on a new journey to explore the profound laws of the universe.
At the meeting, 83 crystal-clear acrylic trophies were particularly eye-catching; they were awarded to national technology enterprises that made outstanding and significant contributions to the project. The unique aspect of these trophies lies in their material, which is identical to the core component of the neutrino experiment facility - the acrylic sphere, and they were all manufactured by Jiangsu Tangchen New Material Technology Co., Ltd. Tang Yuesheng, Chairman of Tangchen New Material, who had just received the Outstanding Contribution Award, carefully placed the trophy before answering the reporter's call. "Being able to contribute to a national key project makes this honor more precious than anything," his voice brimming with pride on the other end of the line.
Many people are curious: what exactly is a neutrino? Dubbed the universe's most ancient and mysterious "ghost particle," it has an extremely small mass, barely interacts with matter, yet holds the core secrets to the birth and evolution of the cosmos. Detecting this "invisible messenger" requires an unprecedented "super equipment," and the JUNO facility is like a giant laboratory buried deep underground. The 700-meter-thick rock layer acts as a natural barrier, blocking out interfering signals and creating an almost "absolutely silent" detection environment.
The core of this "super equipment" is a detector as tall as a 13-story building, featuring a central acrylic sphere with a diameter of 35.4 meters, filled with 20,000 tons of liquid scintillator. When the rare neutrino interacts with atomic nuclei in the liquid, it produces a faint flash of light. Over 40,000 photomultiplier tubes surrounding the sphere act like countless "eyes," amplifying this flash millions of times and converting it into electronic signals for scientists to analyze.
"This acrylic sphere is the lifeline of the entire project. If we couldn't produce it, the project would have utterly failed," recalled Tang Yuesheng. In March 2017, Tangchen New Material signed a 108 million yuan contract to undertake the production and assembly of this world's largest acrylic sphere. Prior to this, the largest sphere of its kind internationally was only 12 meters in diameter; the 35.4-meter size meant the manufacturing difficulty increased exponentially.
This "crystal ball" is composed of 263 seamlessly joined acrylic panels, each 12 centimeters thick, with a total weight of approximately 600 tons. Yet, it required the precision and thinness of an eggshell. The deviation of the sphere's center from its theoretical position could not exceed 20 millimeters on the X, Y, or Z axes—equivalent to an error no greater than the diameter of a coin on a sphere over a dozen stories tall. To control light transmittance loss to within 2% and prevent material yellowing at high temperatures, the team spent over a year researching the thermoforming process alone.
The rigor of the production process was beyond imagination. Microscopic dust particles in the air could interfere with the experiment. Tangchen New Material specially built sealed, dust-free workshops and a 24-hour constant-temperature production line to isolate the process from contamination from raw materials to finished product. "The project party, when inspecting the acrylic panel surfaces, even required that water used for washing them be guaranteed free of any impurities. The requirements were苛刻到近乎 'abnormal,' but we gritted our teeth and persevered," said Tang Yuesheng.
During seven years of攻坚, the team broke through multiple technical barriers, including seamless joining and low-background control, and even built a dedicated intelligent production line to meet special requirements. In July 2022, the sphere panels were transported to the underground 700-meter laboratory for installation. Subsequently, after 8 months of filling, the ultrapure water was replaced with liquid scintillator, finally transforming the hollow "glass sphere" into a "crystal ball" filled with detection medium. This technology is now applied in fields like aquarium tunnels and building structural components, and the company has become an industry leader, exporting its products to over 70 countries.
If the acrylic sphere is the "container" for neutrino detection, then the photomultiplier tubes are the "sensitive eyes" that capture the signals. Sun Jianning, General Manager of North Night Vision Technology (Nanjing) Research Institute Co., Ltd., led his team to accomplish another seemingly impossible task: manufacturing 15,000 20-inch photomultiplier tubes with high detection efficiency.
"This device is like an amplifier for faint light. Even a single photon passing through it can be transformed into a recognizable electrical signal," explained Sun Jianning. The flash produced by a neutrino interaction is fainter than firefly light; without these "super eyes," the signal would be impossible to capture. The path of research and development was fraught with thorns. In 2014, after three years of R&D, the team discovered the detection efficiency failed to meet standards, plunging everyone into despair. "At that time, we felt all previous efforts were wasted, and the technical path might be fundamentally unfeasible."
Despair gave way to regrouping. The team collaborated with experts from the Institute of High Energy Physics of the Chinese Academy of Sciences, studying literature day and night, conducting repeated experiments, and ultimately identified a偏差 in process understanding, innovating an internationally cutting-edge technical path. "The breakthrough after崩溃 is even more gratifying; that sense of achievement is unforgettable for a lifetime," Sun Jianning said. The team not only successfully overcame the "two major challenges" of vacuum environment control and photoelectric conversion amplification but also achieved leading international standards in several technical indicators.
Even more振奋 was that this breakthrough shattered an international monopoly. Previously, over 90% of the domestic market for large-size photomultiplier tubes was occupied by foreign companies at high prices. Through an industry-university-research alliance, North Night Vision completed the journey from development to mass production within four years, forcing foreign competitors to lower prices and improve services. "Backed by a central state-owned enterprise, we shoulder the responsibility of the national team and must achieve full domestic production," Sun Jianning stated.
In the initial phase of the project, the enterprise invested 140 million yuan in building production lines and purchasing hardware. Coupled with low yield rates, it一度处于亏损状态. However, as the technology matured, the products not only supplied the neutrino experiment but also entered fields like dark matter detection, medical imaging, and security. The product range expanded from a few types to dozens, with expectations to surpass one hundred types by 2026. "Now, large scientific research facilities in Europe and America are paying attention to our products. We have completely solved the 'chokepoint' problem in this field," Sun Jianning's tone full of pride.
"Jiangsu enterprises have made monumental contributions to the project," Wang Yifang, an academician of the Chinese Academy of Sciences and project manager of JUNO, gave high praise to the Jiangsu contribution at the summary meeting. "Without their technological breakthroughs and perseverance, the experimental facility simply could not have been built."
Now, just two months into operation, the Jiangmen Underground Neutrino Observatory has broken two world records for neutrino oscillation parameters, achieving data accumulation results that surpass those of similar international experiments by 10 to 20 years. Behind this lies Tangchen New Material's seven years of perseverance in honing a single skill, North Night Vision's decade of dedicated攻关, and a vivid practice of the deep integration of industry, academia, and research among Jiangsu's technology enterprises.
Jiangsu's strength is leveraging hardcore technology as a fulcrum to propel the construction of major national scientific and technological infrastructure. In the future, the technological achievements born from these "national key projects" will bear fruit in even more fields, injecting a continuous stream of momentum into the building of a technologically powerful nation.