Annual Modulation Study of Dark Matter Using CsI(Tl) crystals in KIMS Experiment

Abstract

Dark Matter contributes about 23% of the total energy and matter in the Universe and encloses galaxies by a halo of WIMPs in particular model. The Sun revolves around the center of the Milky Way and its dark matter halo and the earth also revolves around the Sun at the speed of 30 km/s with the inclined angle of 60 degree. Therefore, the earth can interact with the dark matter wind, which is expected to be stronger in the summer than in the winter. The DAMA group reported the annual modulation effect of 0.0183 ± 0.0022 cpd/kg/keV (2-4 keVee) with 8.3σ in 1 cpd/kg/keV background leve with their NaI(Tl) crystal detectors. The KIMS experiment with CsI(Tl) crystal detectors has been looking for dark matter signals and can be expected to see a similar annual modulation effect if the DAMA result is due to dark matter. The status of the KIMS annual modulation study with a 2.5 year exposure is reported.