COSINE-100 full dataset challenges the annual modulation signal of DAMA/LIBRA.

Carlin, Nelson; Cho, Jae Young; Choi, Jae Jin; Choi, Seonho; Ezeribe, Anthony C; França, Luis Eduardo; Ha, Chang Hyon; Hahn, In Sik et al. · Sci Adv · 2025

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Abstract

For over 25 years, the DAMA/LIBRA collaboration has claimed to observe an annual modulation signal, suggesting the existence of dark matter interactions. However, no experiment using different target materials has observed a dark matter signal consistent with their result. To address this puzzle, the COSINE-100 collaboration conducted a model-independent test using sodium iodide crystal detectors, the same target material as DAMA/LIBRA. Analyzing data collected over 6.4 years by the effective mass of 61.3 kilograms, with improved energy calibration and time-dependent background modeling, we found no evidence of an annual modulation signal, challenging the DAMA/LIBRA result with a confidence level greater than 3σ. This finding represents a substantial step toward resolving the long-standing debate surrounding DAMA/LIBRA's dark matter claim, indicating that the observed modulation is unlikely to be caused by dark matter interactions.