Research

I am an experimental particle physicist working on the fundamental building blocks of the universe. I lead the dark matter search group at the Center for Underground Physics (CUP), Institute for Basic Science, and I serve as spokesperson of the KIMS and NEON experiments and co-spokesperson of COSINE. I am also a member of the AMoRE neutrinoless double beta decay experiment. Our detectors operate at the Yemilab and Yangyang underground laboratories in Korea, and our work covers the whole chain from crystal purification and growth, through detector development and underground operation, to data analysis. See the details of my research from CV (September 2026) If you are interested in any of these research topics and want to work with me, please do not hesitate to contact me.

COSINE is a dark matter search experiment designed to test the DAMA/LIBRA claim of an annual modulation signal using the same NaI(Tl) target material. Analyzing 6.4 years of COSINE-100 data taken at the Yangyang underground laboratory, we found no annual modulation signal and challenged the DAMA/LIBRA result at more than the 3-sigma level. A combined analysis with ANAIS-112 extends the exclusion to 4.7-sigma in the 1-6 keV region.

COSINE-100U started physics operation at Yemilab in September 2025, at a depth of 1,000 m. It uses a new encapsulation design that reaches a light yield of about 23 NPE/keV, a 50% improvement over COSINE-100, which is essential for low-mass dark matter sensitivity. The next phase, COSINE-200, will operate a 200 kg array of ultra-pure NaI(Tl) crystals grown at CUP, extending the search toward sub-GeV dark matter through spin-dependent interactions and the Migdal effect.

AMoRE (Advanced Mo-based Rare process Experiment) searches for the neutrinoless double beta decay of 100Mo using molybdate scintillating crystals operated at milli-Kelvin temperatures with metallic magnetic calorimeter (MMC) sensors. Following AMoRE-pilot at the Yangyang underground laboratory and AMoRE-I, the AMoRE-II phase is being deployed at Yemilab with about 200 kg of enriched crystals. Its goal is a half-life sensitivity beyond 10^{26} years, which covers the inverted neutrino mass hierarchy region.

NEON (Neutrino Elastic-scattering Observation with NaI) is a reactor experiment operating 23.7 m from a 2.8 GW thermal reactor core at the Hanbit Nuclear Power Plant. Its primary goal is the observation of coherent elastic neutrino-nucleus scattering (CEvNS) on sodium with NaI(Tl) crystals. NEON has also produced the best laboratory limits on dark matter-electron scattering below 100 keV and new constraints on axion-like particles near 1 MeV. The detector is now being upgraded with thicker lead shielding and an active muon veto.

Detector R&D at CUP supports all of these programs: purification of raw materials and growth of ultra-low-background NaI(Tl) crystals, high-light-yield encapsulation, undoped halide crystals read out with SiPMs at 77 K, NaI+LiI mixed crystals for spin-dependent searches, cryogenic bolometers with metallic magnetic calorimeter sensors, and machine-learning-based signal discrimination that lowers analysis thresholds toward the sub-GeV dark matter region.

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