The journey to find 'dark matter,' which fills the universe but whose true nature is veiled, has made another step forward.
The research team from the Institute for Basic Science (IBS) Axion group has announced on the 28th that they successfully expanded the search into the high-mass (high-frequency) range, which was difficult to approach due to technical limitations, in experiments aimed at finding 'axions,' a leading candidate for dark matter, and significantly improved sensitivity.
Axions are theoretical particles first proposed in 1977, and they are very light and electrically neutral. While direct detection of axions is challenging, they can be captured by converting very weak electromagnetic signals using strong magnetic fields and resonators. A resonator is a device like a metallic sound box that amplifies signals at the desired frequency. Scientists finely tune the frequency of the resonator like adjusting a radio channel to find traces of axions. However, previous explorations have mainly focused on lower mass ranges.
The research team newly fabricated a resonator that applies a special electromagnetic wave resonant method. Compared to existing methods, it can detect higher frequency signals even in resonators of the same size, making it suitable for exploring high-mass axions. Additionally, the team combined it with a precision frequency tuning device developed in-house.
The actual experiment was conducted in an environment of absolute zero at minus 273.11 degrees Celsius, under a strong magnetic field of 12T (Tesla), which is 240,000 times that of Earth's magnetic field. As a result, the first exploratory experiment was implemented in the frequency band similar to that of smartphone Wi-Fi.
This achievement is significant as it showed search performance levels close to the predictions of the representative axion theory 'KSVZ model.' This model theoretically indicates what level of signal strength would appear at a certain mass range if axions exist. The research team reached a sensitivity capable of detecting about 1.7 times the theoretical predictions in the explored range, getting a step closer to directly capturing traces of axions.
Yoon Seong-woo noted, 'This research is the first case to empirically prove the possibility of axion searches using high-order resonant modes, which will significantly impact the design and strategy of next-generation axion detection experiments.' He added, 'The efforts to broaden the axion search area are a continuous accumulation process to uncover the secrets of the universe,' and expressed hope that 'this research will serve as an important foundation for elucidating the nature of dark matter and expanding humanity's knowledge.'
The results of this study were published in the international journal of physics, Physical Review Letters, on the 26th.
References
Physical Review Letters (2025), DOI: https://doi.org/10.1103/f11t-qy8z