Double beta decay experiments: beginning of a new era

Abstract

The review of current experiments on search and studying of double beta decay processes is done. Results of the most sensitive experiments are discussed and values of modern limits on effective Majorana neutrino mass ($<m_{\nu}>) are given. New results on two neutrino double beta decay are presented. The special attention is given to new current experiments with mass of studied isotopes more than 100 kg, EXO--200 and KamLAND--Zen. These experiments open a new era in research of double beta decay. In the second part of the review prospects of search for neutrinoless double beta decay in new experiments with sensitivity to $<m_{\nu}>$ at the level of $\sim 0.01-0.1$ eV are discussed. Parameters and characteristics of the most perspective projects (CUORE, GERDA, MAJORANA, SuperNEMO, EXO, KamLAND--Zen, SNO+) are given.