Researchers have a chat at Yemi Lab, a research complex built under Mt. Yemi in Jeongseon-gun, Gangwon-do, on the 29th of last month. A research facility will soon be installed in this empty space. [사진 제공 = IBS]‘thud…’
A vibration was felt with a roar. The influence of dynamite blown to mine iron ore at the nearby Handeok Iron Mine. Workers wearing hard hats were busy moving, not paying attention to the sound. Light from the lights hanging from the ceiling was reflected, illuminating the slightly smoky interior of the cave. This is Yemi Lab, the Institute of Basic Science (IBS), which will reveal the secrets of the universe through research on dark matter and neutrinos, 1,000 meters underground in Jeongseon, Gangwon-do, on the 29th of last month.
Searching for the secrets of the underground universe, it sounds paradoxical, but there is a reason. There are two main types of research conducted here. One of them is the dark matter search research, the COSINE project.
In the universe, which cannot be expressed in terms of vastness, matter is only 4% energy known to mankind. Dark matter makes up about 26% of the total, and the remaining 70% is dark energy. Along with inactive axons and neutrinos, WIMP is considered one of the dark matters. This WIMP, which means ‘weakly interacting heavy particles’, is the substance that Yemi Lab is trying to find.
Kim Young-duk, head of the IBS Underground Experimental Research Center, said, “It takes five times more mass than the combined mass of all known materials to explain the motion of stars.” “There are many undeniable experimental results that prove the existence. of dark matter.” he explained.
“(The identity of dark matter) is one of the biggest questions of all the natural sciences beyond modern physics,” he added.
Dark matter is difficult to detect from earth. This is because the signal emitted by dark matter is very weak. Cosmic radiation coming down from space makes noise, making it almost impossible to catch the signal from dark matter even if a detector is installed. But the situation is different in the basement. Rocks and soil act as a ‘natural shield’. Cosmic radiation can be reduced compared to the Earth’s surface by a million. It is possible to capture the signal emitted by dark matter relatively without the influence of noise.
Even after going underground, there are still many obstacles. Not only can dust cause disturbances, but even rocks can emit radiation and cause noise. Fortunately, Mt. Yemi where Yemi Lab is located is a limestone mountain that emits much less radiation than granite. The research team also tried to find a product that emits little or no radiation, even looking for paint painted on the surface of the oyster to prevent dust from flying.
The sensor, the core of the research facility, was surrounded more tightly. The reporters could only see the polyethylene around the sensor outside the shield door. Another layer of neutron-blocking polyethylene is made inside the giant shield. A water tank is then filled with water, and the sensor is located in it. The temperature where the sensor is located is minus 272.99 degrees. It is only 0.01 degrees higher than ‘Absolute Zero’, where all energy flows are zero.
The sensor includes a 200 kg scale by making a number of sodium iodide crystals. When dark matter collides with the detector, a microscopic signal is recorded. Park Kang-soon, a senior researcher at the IBS Underground Experimental Research Center, said, “It’s enough to catch a signal from the sensor even if you’re breathing.” He added, “Once the door is closed and the sensor starts operating, it does not open under any circumstances.”
Another key challenge is the study of non-neutrino emission double beta decay (AMoRE). A neutrino is one of the smallest unit particles of matter that cannot be split further. So far, only three neutrinos have been discovered: electron, tau, and muon. Experiments are carried out at Yemi Lab to confirm the mass of the neutrinos and to confirm the existence of ‘inactive neutrinos’, which are also candidates for dark matter. The existence of ‘anti-neutrinos’ with the same physical properties as neutrinos but with different charges is one of the main experimental purposes.
Director Kim said, “Many neutrinos were created in the early stages of the universe, but what remains so far is in a very weak state. It can also influence revealing
Research is actively conducted in laboratories built underground around the world. In 2015, the Nobel Prize in Physics was also awarded to Professor Takaaki Kajita, who discovered that neutrinos have mass in the ‘Super Kamiokande’, an underground laboratory in Japan.
The Yemi Lab scale is the sixth among the world’s underground experimental facilities. The IBS explained that it was made in the form of an anthill that drilled a long road and connected the space necessary for each experiment to the road only, so that the space was used more efficiently. Organizations such as the Korea Meteorological Administration, the Korea Geological Research Institute and the National Institute of Mathematical Sciences also plan to secure space at Yemi Lab and conduct observation and research.
Oh Tae-seok, 1st Vice Minister of Science, Technology, Information and Communication attended the completion ceremony on the 5th and said, “Large research facilities are essential for creating first-class research results,” he said.
IBS President Noh Do-young said, “I am proud that Yemi Lab was successfully established without a single safety incident.
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