Measurement of the double-βdecay half-life of ^{136}Xe with the KamLAND-Zen experiment

Abstract

We present results from the KamLAND-Zen double-beta decay experiment based on an exposure of 77.6 days with 129 kg of ${}^{136}$Xe. The measured two-neutrino double-beta decay half-life of ${}^{136}$Xe is $T_{1/2}^{2\hat{I}½}=2.38\pm 0.02(stat)\pm 0.14(syst)\times 10^{21}$ yr, consistent with a recent measurement by EXO-200. We also obtain a lower limit for the neutrinoless double-beta decay half-life, $T_{1/2}^{0\hat{I}½}>5.7\times 10^{24}$ yr at 90% confidence level (C.L.), which corresponds to almost a five-fold improvement over previous limits.

6 pages, 4 figures. Version as published in PRC