https://doi.org/10.1140/epjc/s10052-025-13775-0
Regular Article - Experimental Physics
Improved background modeling for dark matter search with COSINE-100
1
Department of Physics, Sungkyunkwan University, 16419, Suwon, Republic of Korea
2
Center for Underground Physics, Institute for Basic Science (IBS), 34126, Daejeon, Republic of Korea
3
Physics Institute, University of São Paulo, 05508-090, São Paulo, Brazil
4
Department of Physics, Kyungpook National University, 41566, Daegu, Republic of Korea
5
Department of Physics and Astronomy, Seoul National University, 08826, Seoul, Republic of Korea
6
Department of Physics and Astronomy, University of Sheffield, S3 7RH, Sheffield, UK
7
Department of Physics, Chung-Ang University, 06973, Seoul, Republic of Korea
8
Center for Exotic Nuclear Studies, Institute for Basic Science (IBS), 34126, Daejeon, Republic of Korea
9
Department of Science Education, Ewha Womans University, 03760, Seoul, Republic of Korea
10
IBS School, University of Science and Technology (UST), 34113, Daejeon, Republic of Korea
11
Department of Physics and Wright Laboratory, Yale University, 06520, New Haven, CT, USA
12
Department of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin-Madison, 53706, Madison, WI, USA
13
Korea Research Institute of Standards and Science, 34113, Daejeon, Republic of Korea
14
Department of Accelerator Science, Korea University, 30019, Sejong, Republic of Korea
15
Department of Physics and IQS, Chungnam National University, 34134, Daejeon, Republic of Korea
16
Department of Physics, Universitas Negeri Malang, 65145, Malang, Indonesia
17
Department of Physics and Astronomy, University of Utah, 84112, Salt Lake City, UT, USA
18
Department of Physics, University of California San Diego, 92093, La Jolla, CA, USA
19
Center for Underground Physics, Institute for Basic Science (IBS), 34126, Daejeon, Republic of Korea
Received:
19
August
2024
Accepted:
20
December
2024
Published online:
20
January
2025
COSINE-100 aims to conclusively test the claimed dark matter annual modulation signal detected by DAMA/LIBRA collaboration. DAMA/LIBRA has released updated analysis results by lowering the energy threshold to 0.75 keV through various upgrades. They have consistently claimed to have observed an annual modulation. In COSINE-100, it is crucial to lower the energy threshold for a direct comparison with DAMA/LIBRA, which also enhances the sensitivity of the search for low-mass dark matter, enabling COSINE-100 to explore this area. Therefore, it is essential to have a precise and quantitative understanding of the background spectrum across all energy ranges. This study expands the background modeling from 0.7 to 4000 keV using 2.82 years of COSINE-100 data. The modeling has been improved to describe the background spectrum across all energy ranges accurately. Assessments of the background spectrum are presented, considering the nonproportionality of NaI(Tl) crystals at both low and high energies and the characteristic X-rays produced by the interaction of external backgrounds with materials such as copper. Additionally, constraints on the fit parameters obtained from the alpha spectrum modeling fit are integrated into this model. These improvements are detailed in the paper.
© The Author(s) 2025
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