The universities in Lanzhou represent invaluable scientific and intellectual assets for the city, serving as essential innovation hubs in the provincial capital enhancement initiative. Over the years, while cultivating generations of talent for the province and the nation, these institutions have focused on cutting-edge scientific fields, achieving significant results in translating research into practical applications and supporting local economic development. Starting today, this newspaper launches a series highlighting the research strengths and technological innovations of Lanzhou's universities.

Conducting a health "CT scan" on Xi'an's ancient city walls, performing comprehensive "health monitoring" on the Maijishan Grottoes in Tianshui and the Yungang Grottoes in Shanxi... While these tasks may seem unimaginable to ordinary people, they represent work already accomplished or currently underway by Lanzhou University's muon research team.

How can we probe the interiors of large-scale objects? The novel, eco-friendly, and safe cosmic ray muon imaging technology offers a groundbreaking solution. Through long-term accumulation and research, Professor Liu Zhiyi's team at the Ministry of Education's Frontier Science Center for Rare Isotopes at Lanzhou University and the National Nuclear Industry Research Institute has successfully developed the cosmic ray muon CORMIS imaging system through multidisciplinary collaboration. They have implemented China's first application in cultural heritage preservation and Asia's first application in mineral exploration, providing crucial technical support for effectively solving the challenge of deep internal imaging of large-scale objects.

Performing a "CT Scan" on Ancient City Walls to Explore Gold Deposits

Muon imaging technology holds broad application prospects

Cosmic-ray muons exist naturally in the environment, possessing high energy and strong penetrating power, making them a natural, non-destructive "probe" for fundamental particles. In 2020, a team from the College of Nuclear Science and Technology at Lanzhou University and the Frontier Science Center for Rare Isotopes successfully developed China's first cosmic-ray muon imaging system based on triangular prism plastic scintillators, which passed expert acceptance with flying colors.

In 2021, Professor Liu Zhiyi from the School of Nuclear Science and Technology at Lanzhou University led a team to the ancient capital of Xi'an. They conducted a specialized "CT scan" health check for the Xi'an City Wall using cosmic ray muon imaging technology. This marked China's first experimental application of muon imaging technology on a large-scale cultural heritage site. The research findings hold significant implications for the archaeology and conservation of major cultural relics and monuments, as well as for advancing the Origins of Chinese Civilization Project.

In 2024, leveraging natural cosmic ray muon imaging technology, the team upgraded detection equipment tailored for mining exploration environments. Field tests were conducted at the Zaozigou Gold Mine in Gannan Tibetan Autonomous Prefecture, Gansu Province, offering novel approaches for mineral exploration and geological structure imaging in China.

Currently, the team is actively collaborating with the Maijishan Grottoes and Yungang Grottoes to conduct "health" monitoring for these major cultural heritage sites. The team possesses six domestically developed muon imaging systems, with two sets currently collecting data at the Yungang Grottoes in Shanxi Province and the remaining four conducting experimental surveys at the Maijishan Grottoes in Tianshui, Gansu Province.

"Natural ray muon imaging technology is a novel, green, and non-destructive detection method," explained Associate Professor Liu Juntao, a key member of the team. Muon imaging functions similarly to X-ray scans of the human body, creating images by penetrating and visualizing internal structures. This principle also applies to imaging the internal structures of large objects like mountains, buildings, and historical sites. Conventional geophysical methods often require destructive exploration, struggle to penetrate targets, or lack sufficient precision-making internal detection of large objects a long-standing challenge. Cosmic ray muon imaging technology offers a novel, eco-friendly, and safe solution to these issues.

Complementing the evolving imaging technology are continuously expanding application scenarios. When asked about potential future applications of muon imaging, Liu Juntao confidently shared that beyond monitoring large cultural relics and historical sites, the technology could be applied to border security and cargo inspection, volcano monitoring, mineral and geological structure exploration, and other possibilities currently under active research and development by the team.

Leading domestically, keeping pace internationally

Lanzhou University's Unique Technique Fills International Gap

Muon technology has remained a cutting-edge field both domestically and internationally over the years. Particularly in 2017, scientists from Egypt, France, and Japan conducted muon imaging of the pyramids, reigniting a new wave of development for this technology. Internationally, some countries and regions have already achieved significant breakthroughs in this area, demonstrating the immense potential and advantages of muon technology. Domestically, development began relatively later. Currently, numerous scholars, universities, and research institutes are continuously investing resources, and progress has accelerated in recent years. For us, it should be a level where we are running alongside the international first tier. Domestically, our team has truly taken the muon imaging system from the laboratory testing stage to practical application, achieving mass production and industrialization capabilities." Speaking of the team's current achievements, Liu Juntao was visibly delighted.

From hardware components like instrument assembly materials to algorithmic software systems, the Nuclear Technology Innovation and Industrialization Team at Lanzhou University is committed to localization. "China's vast territory offers numerous fields where muon technology can be applied, making independent hardware development particularly crucial. Since 2019, our team has been determined to build muon systems and solve domestic surveying and detection challenges." Liu Juntao explained that collaborations with domestic partner universities and component manufacturers have not only enabled the application of natural radiation muon imaging technology in more real-world scenarios but also resolved the localization of this detection system, significantly reducing costs. Currently, the localization rate of this technology has reached approximately 95%.

Additionally, the team developed a simple yet effective method for correcting muon measurement data at high altitudes, substantially mitigating the impact of elevation on imaging accuracy. "Our mineral exploration test site is located on a plateau at around 3,000 meters above sea level. In this sense, we can say we've filled a gap in the relevant field," Liu Zhiyi remarked.

Strengthen industry-academia-research collaboration

Hope Muon Imaging Technology Takes Root in Lanzhou

Time rewinds to 2019, the year Liu Juntao arrived at Lanzhou University.

For Liu Juntao, who grew up in Qingdao, the most challenging aspect of adjusting to Lanzhou was the dry climate. His lips were often encrusted with a layer of dry skin. Five years later, Liu Juntao has grown to love this bold and warm-hearted city, settling down here and making Lanzhou his second home.

"Lanzhou University provides an excellent platform," Liu Juntao reflects. "Looking back at my professional achievements over these five years, had I not come here, it might have taken me much longer elsewhere to reach the level of research I'm doing now."

Ultimately, scientific research must serve the nation and society. Liu emphasized that the university possesses strong capabilities in fundamental research and preliminary breakthroughs. Once transformed into applications, these can resolve technical challenges in industrial development. The preliminary trials for muon imaging technology have been largely perfected. Currently, active discussions are underway with the government and local enterprises in Lanzhou to bring these scientific achievements to fruition in the city, including expanding application scenarios and achieving mass production. We can also recruit talent, bringing in scientists from abroad and other 

high-level universities to join our team, thereby providing new scientific and technological capabilities for both the team and the local region. (Reporter Liu Baoli)