[Reading Science] 1 in 1,000,000 nm, Opening the Door to the Atomic World

Visiting Next Year's Full Operation of the Korean Heavy Ion Accelerator Raon (RAON)

[Asia Economy Reporter Kim Bong-su] The Korean heavy-ion accelerator RAON, dubbed the "largest science project since Dangun," with an investment of a staggering 1.5 trillion won, will begin full-scale operation starting next year. It is expected to become a strong ally for South Korea's semiconductor industry, which is leading the world. It will also be used for various practical purposes such as basic scientific research exploring the secrets of the universe, advanced material development, and cancer treatment drug development. On the 15th, the Institute for Basic Science (IBS) revealed the grandeur of RAON through an official briefing and on-site tour following the first successful beam extraction. Curious about what exactly this device is used for, we headed to the IBS Heavy Ion Accelerator Research Center located in the Daedeok Research and Development Special Zone in Daejeon.

What is a Heavy Ion Accelerator?

Human civilization began with efforts to satisfy curiosity about nature. The fundamental purpose of a heavy ion accelerator is to study microscopic particles such as atomic nuclei to understand their properties. Lee Jae-heun, Director of the International Science Business Belt Promotion Team at the Ministry of Science and ICT, who was met on site, explained, "It is a facility that accelerates heavy particles like uranium in a superconducting state to create rare isotopes or conduct research using them." He added, "Its applications are broad, including nuclear physics, new material development, semiconductor development, breed improvement, and production of medical isotopes for cancer treatment." Hong Seung-woo, Director of the IBS Heavy Ion Accelerator Research Center, also said, "In the early universe, only the lightest elements existed, but now various substances exist. Accelerator research started from the question of how such substances were created." He explained, "RAON's initial research focus will be on studying the process by which light elements evolve diversely through various nuclear reactions."

In particular, RAON has been designed and manufactured with world-class specifications by Korean technology and domestic companies over approximately 11 years since 2011. Except for the high-energy section accelerator, most of the facilities have been completed, and the first beam extraction was successfully achieved on October 7th. Director Hong recalled, "When we first started 11 years ago, there were no people, no land, nothing, but only the dreams and passion of scientists. Fortunately, the government provided a large budget, allowing us to experience the realization of that dream."

According to Director Hong, the first beam extraction, i.e., accelerating argon ions, means above all that the core equipment, the superconducting accelerator cavity, operated normally. The superconducting accelerator cavity must be cooled to an absolute temperature of 4K, that is, below minus 269.15 degrees Celsius, to facilitate ion movement. Only a few companies worldwide, including those in Germany and France, possess this challenging technology. Director Hong explained, "It was like breathing life into a can; high-frequency waves entered the accelerator cavity and successfully accelerated particles." He added, "It is significant because it confirmed that all the installed systems operate normally." He also said, "We can still see it as a baby taking its first steps. There is a process ahead to grow and mature to become the world's best as planned." He continued, "It is not easy. There were sleepless nights, difficulties, and hardships. Please continue to watch over and encourage us."

The Magical Machine Unlocking the Secrets of the Universe

After hearing this explanation, the on-site tour began immediately. We first saw the central control center filled with large monitors, reminiscent of NASA's spacecraft launch control center. Then we arrived at the helium cooling facility called the 'Cryogenic Facility Building.' Here, liquid helium used for cooling the accelerator was being produced. This facility lowers the temperature by repeatedly compressing and expanding helium gas to transform it into liquid helium at an absolute temperature of 4K. It requires complex machinery, special materials, and operational technology, so it was imported from overseas and is the largest of its kind in South Korea. It was impressive that detection and alarm devices were installed on every wall due to the risk of fatal accidents if helium gas leaks.

Leaving the helium cooling facility, we arrived at the underground high-frequency power generation facility. To accelerate uranium ions, the main acceleration material of RAON, a strong microbeam must be fired at electrons. This facility generates power for a powerful high-frequency wave (325 MHz) that oscillates approximately 80 million times per second between positive and negative charges applied to uranium ions knocked loose by electrons. Although it sounds complicated, it is similar to the principle of a magnetic levitation train. If the N-pole is applied to the main body and the S-pole is sequentially applied to the rail in front at high speed, the train accelerates to hundreds of kilometers per hour.

Afterward, we were able to see the accelerator facility where ions actually move. Currently, only 54 accelerators in the low-energy section have been installed. On October 7th, the initial operation of the first five accelerators in this low-energy section succeeded, accelerating argon ions to a speed of 30,000 km/s. RAON's ultimate goal is to accelerate ions to half the speed of light, i.e., 150,000 km/s. IBS plans to conduct one or two more trial operations by next year and then begin full-scale beam extraction in the second half of the year for various research uses. Kwon Myeon, head of the IBS Heavy Ion Accelerator Project Group, said, "We are currently compiling a research list, and there is a lot of interest not only domestically but also globally, with various proposals coming in." He explained, "Using the beam in semiconductor design, inspection, and manufacturing processes can help improve the yield and quality of ultra-fine precision semiconductors, so related companies are showing great interest."

Overview of the RAON heavy ion accelerator.

RAON is a kind of gigantic ultra-precise observation equipment. It can explore the world of atoms, neutrons, and protons at sizes below one-millionth of a nanometer, that is, femtometers (fm). After accelerating ions, it can collide, split, and filter them to create various atomic nuclei and verify their properties. Notably, it can reproduce the state three minutes after the Big Bang. By ionizing particles such as uranium and accelerating them to 150,000 km/s to collide with target materials, the 'KoBRA' recoil spectrometer facility observes the secrets of early universe material formation. Additionally, RAON is the world's first to simultaneously establish the 'Online Isotope Separator (ISOL)' and the 'In-Flight Fragment Separator (IF),' raising expectations for the discovery of rare isotopes.

There are still remaining challenges. The facility must be completed by constructing the high-energy section, which was originally planned but postponed due to technical issues, to enable research on life phenomena, muon material structures, magnetic materials, and material development. Director Lee said, "The high-energy accelerator section was designed and prototypes were made, but there was a lack of experience in engineering fields such as precision and post-processing needed to secure sufficient performance, resulting in trial and error." He added, "To overcome this, we will begin preliminary research and development (R&D) from next year, aiming to complete the design and start construction by 2025 at the earliest."