Lowering the energy threshold in COSINE-100 dark matter searches

在COSINE-100实验中将NaI(Tl)闪烁体的阈值降至0.7 keV

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

COSINE-100实验通过应用多层感知机网络和频率域波形的新似然参数，将NaI(Tl)探测器的能量阈值从1 keV降至0.7 keV，以更好地对比DAMA/LIBRA结果并提升对亚GeV暗物质的搜寻灵敏度。

Lowering the background level and the energy threshold of Micromegas x-ray detectors for axion searches

Axion helioscopes search for solar axions by their conversion in x-rays in the presence of high magnetic fields. The use of low background x-ray detectors is an essential component contributing to the sensitivity of these searches. In this work, we review the recent advances on Micromegas detectors used in the CERN Axion Solar Telescope (CAST) and proposed for the future International Axion Observatory (IAXO). The actual setup in CAST has achieved background levels below 10$^{-6}$ keV$^{-1}$ cm$^{-2}$ s$^{-1}$, a factor 100 lower than the first generation of Micromegas detectors. This reductio…

Measurement of the cosmic muon annual and diurnal flux variation with the COSINE-100 detector

We report measurements of annual and diurnal modulations of the cosmic-ray muon rate in the Yangyang underground laboratory (Y2L) using 952 days of COSINE-100 data acquired between September 2016 and July 2019. A correlation of the muon rate with the atmospheric temperature is observed and its amplitude on the muon rate is determined. The effective atmospheric temperature and muon rate variations are positively correlated with a measured effective temperature coefficient of $α_{T}$ = 0.80 $\pm$ 0.11. This result is consistent with a model of meson production in the atmosphere. We also searched…

Three-year annual modulation search with COSINE-100

COSINE-100 is a direct detection dark matter experiment that aims to test DAMA/LIBRA's claim of dark matter discovery by searching for a dark matter-induced annual modulation signal with NaI(Tl) detectors. We present new constraints on the annual modulation signal from a dataset with a 2.82 yr livetime utilizing an active mass of 61.3 kg, for a total exposure of 173 kg$\cdot$yr. This new result features an improved event selection that allows for both lowering the energy threshold to 1 keV and a more precise time-dependent background model. In the 1-6 keV and 2-6 keV energy intervals, we obser…

利用COSINE-100改进暗物质探测的本底建模

Improved background modeling for dark matter search with COSINE-100

为检验DAMA/LIBRA的暗物质年调制信号并提升低质量暗物质探测灵敏度，COSINE-100研究利用2.82年数据扩展并改进了0.7–4000 keV能段的本底建模，纳入晶体非正比性、特征X射线及α能谱参数约束以提升精度。

Review on non-directional direct dark matter searches

An overview of non-directional direct detection methods is given. The currently leading experiments for spin independent WIMPs interactions are using simultaneous measurement of two quantities for event-by-event background discrimination in cryogenic bolometers and noble gas like xenon. Besides these, several interesting techniques have been developped, each having a specific advantage concerning e.g energy threshold lowering or strong immunity to ionizing radiations background. Technologies used and most recent results about spin-dependent and spin-independent cases are presented.