Lowering threshold of NaI(Tl) scintillator to 0.7 keV in the COSINE-100 experiment

TL;DR

COSINE-100 improved its analysis by lowering the energy detection threshold to 0.7 keV using advanced neural network techniques, enhancing its ability to compare with DAMA/LIBRA and detect low-mass dark matter.

Contribution

The paper introduces a new analysis method that reduces the energy threshold in COSINE-100 to 0.7 keV, enabling more sensitive dark matter searches and better comparison with DAMA results.

Findings

Lowered energy threshold to 0.7 keV.

Enhanced sensitivity to sub-GeV dark matter.

Improved comparison with DAMA/LIBRA results.

Abstract

COSINE-100 is a direct dark matter search experiment, with the primary goal of testing the annual modulation signal observed by DAMA/LIBRA, using the same target material, NaI(Tl). In previous analyses, we achieved the same 1 keV energy threshold used in the DAMA/LIBRA's analysis that reported an annual modulation signal with 11.6$\sigma$ significance. In this article, we report an improved analysis that lowered the threshold to 0.7 keV, thanks to the application of Multi-Layer Perception network and a new likelihood parameter with waveforms in the frequency domain. The lower threshold would enable a better comparison of COSINE-100 with new DAMA results with a 0.75 keV threshold and account for differences in quenching factors. Furthermore the lower threshold can enhance COSINE-100's sensitivity to sub-GeV dark matter searches.