KamLAND-Zen has started a search for neutrino-less double beta decay with 320kg of 90% enriched 136Xe in September 2011. Results from initial 112 day of measurement are presented. It provides so far the most precise two-neutrino-mode half-life of 136Xe and the most stringent upper limit of the coupling constant of the ordinary Majoron-emitting double-beta-decay. The search for neutrino-less mode has achieved top class sensitivity but is struggling with unexpected backgrounds. Origin of the background and prospects for the future improvements are also discussed.
- Double beta decay
- Majorana neutrino mass
- Majoron coupling constant
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics