Nonproportionality of NaI(Tl) Scintillation Detector for Dark Matter Search Experiments

Abstract

We present a comprehensive study of the nonproportionality of NaI(Tl) scintillation detectors within the context of dark matter search experiments. Our investigation, which integrates COSINE-100 data with supplementary $\gamma$ spectroscopy, measures light yields across diverse energy levels from full-energy $\gamma$ peaks produced by the decays of various isotopes. These $\gamma$ peaks of interest were produced by decays supported by both long and short-lived isotopes. Analyzing peaks from decays supported only by short-lived isotopes presented a unique challenge due to their limited statistics and overlapping energies, which was overcome by long-term data collection and a time-dependent analysis. A key achievement is the direct measurement of the 0.87 keV light yield, resulting from the cascade following electron capture decay of ${}^{22}$Na from internal contamination. This measurement, previously accessible only indirectly, deepens our understanding of NaI(Tl) scintillator behavior in the region of interest for dark matter searches. This study holds substantial implications for background modeling and the interpretation of dark matter signals in NaI(Tl) experiments.

12 pages, 7 figures

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Cited by in corpus (6)

• Upgrading the COSINE-100 Experiment for Enhanced Sensitivity to Low-Mass Dark Matter Detection
• COSINE-100 Full Dataset Challenges the Annual Modulation Signal of DAMA/LIBRA
• Lowering threshold of NaI(Tl) scintillator to 0.7 keV in the COSINE-100 experiment
• New Constraints on Axion-Like Particles with the NEON Detector at a Nuclear Reactor
• Constraints on sub-GeV dark matter scattering on electrons with COSINE-100
• Scintillation pulse characterization with spectrum-inspired temporal neural networks: case studies on particle detector signals