Speaker
Description
KamLAND-Zen is a double beta decay experiment that exploits the existing KamLAND neutrino detector which realizes an ultra-low background environment. The xenon-loaded liquid scintillator in a spherical nylon balloon was deployed at the center of the KamLAND detector. The first search for neutrinoless double-beta decay of 136Xe with 381 kg of xenon (KamLAND-Zen 400) demonstrated excellent sensitivity. To enhance the sensitivity, the KamLAND-Zen detector was upgraded to larger volume containing 745 kg xenon (KamLAND-Zen 800), corresponding to a twofold increase. In this talk, we will present the result of the improved search using complete KamLAND-Zen dataset, corresponding to an exposure of about 2 ton-yr of 136Xe. In the future, the KamLAND detector is planned to be upgraded to improve the search sensitivity (KamLAND2-Zen), and final optimizations of design are ongoing.
