Achieving a 0.49 keV threshold in the COSINE-100 dark matter experiment

@misc{kim2026achieving,
  title = {{Achieving a 0.49 keV threshold in the COSINE-100 dark matter experiment}},
  author = {J. Kim and N. Carlin and D. F. F. S. Cavalcante and J. Y. Cho and S. J. Cho and S. Choi and A. C. Ezeribe and L. E. França and O. Gileva and C. Ha and I. S. Hahn and E. J. Jeon and H. W. Joo and W. G. Kang and M. Kauer and B. H. Kim and D. Y. Kim and H. J. Kim and K. W. Kim and S. H. Kim and S. K. Kim and W. K. Kim and Y. D. Kim and Y. H. Kim and B. R. Ko and Y. J. Ko and B. C. Koh and D. H. Lee and E. K. Lee and H. Lee and H. S. Lee and H. Y. Lee and I. S. Lee and J. Lee and J. Y. Lee and M. H. Lee and S. H. Lee and S. H. Lee and Y. J. Lee and D. S. Leonard and N. T. Luan and V. H. A. Machado and B. B. Manzato and R. H. Maruyama and R. F. Muhdi and S. L. Olsen and H. K. Park and H. S. Park and J. C. Park and J. S. Park and K. S. Park and K. Park and S. D. Park and R. L. C. Pitta and H. Prihtiadi and C. Rott and K. A. Shin and M. K. Son and L. T. Truc and L. Yang},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.19668},
  eprint = {2610.19668},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.19668},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Achieving a 0.49 keV threshold in the COSINE-100 dark matter experiment
AU  - J. Kim
AU  - N. Carlin
AU  - D. F. F. S. Cavalcante
AU  - J. Y. Cho
AU  - S. J. Cho
AU  - S. Choi
AU  - A. C. Ezeribe
AU  - L. E. França
AU  - O. Gileva
AU  - C. Ha
AU  - I. S. Hahn
AU  - E. J. Jeon
AU  - H. W. Joo
AU  - W. G. Kang
AU  - M. Kauer
AU  - B. H. Kim
AU  - D. Y. Kim
AU  - H. J. Kim
AU  - K. W. Kim
AU  - S. H. Kim
AU  - S. K. Kim
AU  - W. K. Kim
AU  - Y. D. Kim
AU  - Y. H. Kim
AU  - B. R. Ko
AU  - Y. J. Ko
AU  - B. C. Koh
AU  - D. H. Lee
AU  - E. K. Lee
AU  - H. Lee
AU  - H. S. Lee
AU  - H. Y. Lee
AU  - I. S. Lee
AU  - J. Lee
AU  - J. Y. Lee
AU  - M. H. Lee
AU  - S. H. Lee
AU  - S. H. Lee
AU  - Y. J. Lee
AU  - D. S. Leonard
AU  - N. T. Luan
AU  - V. H. A. Machado
AU  - B. B. Manzato
AU  - R. H. Maruyama
AU  - R. F. Muhdi
AU  - S. L. Olsen
AU  - H. K. Park
AU  - H. S. Park
AU  - J. C. Park
AU  - J. S. Park
AU  - K. S. Park
AU  - K. Park
AU  - S. D. Park
AU  - R. L. C. Pitta
AU  - H. Prihtiadi
AU  - C. Rott
AU  - K. A. Shin
AU  - M. K. Son
AU  - L. T. Truc
AU  - L. Yang
PY  - 2026
DA  - 2026/10/14
PB  - arXiv
DO  - 10.48550/arxiv.2610.19668
UR  - https://arxiv.org/abs/2610.19668
AB  - The COSINE-100 experiment searched for weakly interacting massive particles (WIMPs) with NaI(Tl) crystals at the Yangyang Underground Laboratory. Using its full 6-year dataset, we lower the analysis threshold to 0.49 keV. A multi-layer perceptron classifier separates scintillation events from photomultiplier tube noise. It is trained with approximately 3×10^6 simulated scintillation waveforms per crystal, separately for groups of events with similar numbers of photoelectron clusters. The selection keeps more than 10% of scintillation events at 0.49 keV while limiting noise contamination to below 1%. The selection efficiency is validated with ^22Na-calibration data and internal ^22Na events, and the selection performance is stable over the six years of data taking. With this threshold, the median expected upper limit on the spin-dependent WIMP-proton cross section reaches 1.1×10^−36 cm^2 at a WIMP mass of 2.5 GeV/c^2, probing previously unexplored parameter space in the 2.0-2.8 GeV/c^2 mass range.
ER  -