Speaker
Description
The observation of a neutrino-less double-beta (0$\nu\beta\beta$) decay
would be evidence of neutrino's Majorana nature, and it might be a clue
to explain the baryon asymmetry and the extremely light neutrino masses.
The half-life of 0$\nu\beta\beta$ decay is more than 10$^{26}$ year in
case of $^{136}$Xe, thus it is important to make radiopure detector to
find the very rare decay.
KamLAND-Zen is a 0$\nu\beta\beta$ decay search experiment with Xe loaded
liquid scintillator (XeLS) containing 90.77\% enriched $^{136}$Xe.
The mini-balloon is a container for holding XeLS at the center of the
KamLAND detector without impairing the extremely low radiation
environment.
We have installed a new mini-balloon with a thickness of 25 $\mu$m and a
radius of 1.92 m, which was made in a class 1 clean room and is almost
twice as large as the last one. The mini-balloon is going to hold about
750 kg of Xe gas in the XeLS and 0$\nu\beta\beta$ decay search will
start soon.
After the KamLAND-Zen experiment, it is planned to do a 0$\nu\beta\beta$
decay search experiment with a remodeled KamLAND detector to improve the
energy resolution (KamLAND2-Zen).
I will also talk about novel hardware improvements to collect data
without loss just after a large light yield event such as a cosmic ray
muon spallation at KamLAND2-Zen.
