KamLAND-Zen is a neutrinoless double beta decay search experiment based on the 136Xe loaded liquid scintillator. KamLAND-Zen 400 project was already terminated and its latest limit for half life of 0νββ is T1/2 > 1.07 ×1026 years at 90% confidence level. It corresponds to Majorana effective mass hmββi < 61−165 meV. After the KamLAND-Zen 400, we have started KamLAND-Zen 800 project which will use 750 kg xenon and new clean nylon balloon called mini-balloon to contain xenon loaded liquid scintillator. We made mini-balloon with various contamination rejection techniques, and we successfully installed it in KamLAND. Currently we are purifying non-xenon-loaded scintillator in mini-balloon. After the purification, we will dissolve xenon in the liquid scintillator.
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