Speaker
Description
KamLAND-Zen is searching for neutrinoless double-beta (0νββ) decay in Xe-136 using a xenon-loaded liquid scintillator. The KamLAND-Zen detector was recently upgraded with almost double the amount of xenon and an ultra-low radioactivity container. With almost 1-ton-year of $^{136}$Xe exposure, we are exploring the double-beta decay parameter space corresponding to the inverted hierarchy for the first time. We have not yet observed 0νββ decay, but these results make use of novel algorithms to perform beta-gamma separation using ML and tag spallation products on day-long time scales. We obtain a lower limit for the 0νββ decay half-life of $2.3 \times 10^{26}$ yr at 90% C.L., corresponding to upper limits on the effective Majorana neutrino mass of 36-156 meV using commonly adopted nuclear matrix element calculations.
