Double-beta decay: recent progress in experimental activity

The review deals with consideration of today's situation in experiments aimed at studying double beta-decay. Radical increase in the volume of experimental information on two-neutrino mode of the process occurred in recent 10 years. In direct and geochemical experiments the 2β2ν-decay of ten nuclei was observed: 48Ca, 76Ge, 82Se, 96Zr, 100Mo, 116Cd, 128Te, 130Te, 150Nd, 238U. However, the main fundamental problem is still open: no non-neutrino double beta-decay was detected, despite the fact that sensitivity of up-to-date facilities with Ge-detectors exceeds 1025 years. Restriction of the Majorana effective mass of neutrino on the basis of the results obtained is set at the level (mν) < 0.4-1.1 eV. Further essential progress in search of 2β0ν-decay involves the necessity to create new in principle experimental facilities, since capabilities of the existing facilities have been largely exhausted