The results of the double beta decay investigations were reported. The investigations are carried out with the TGV-2 andObelix low-background HPGe spectrometers at the Modane underground laboratory (France) at a depth of 4800 m water equivalent. The main goal of the measurements with the 32-detector spectrometer TGV-2 is direct detection of the two-neutrino double electron capture in the 106Cd decay.
The above double beta decay mode has not been observed in direct experiments so far. In our investigations, the best experimental limits on this decay mode were obtained within the range theoretically predicted for this rare process.The ultralow-background spectrometer Obelix with the sensitive volume of 600 cm3 is used to investigate double beta decay to excited states of daughter nuclei. Among the results are a more accurate value for the half-life of the 2ν2β¯ decay 100Mo - 100Ru (0+1, 1130.3 keV) and more than an order of magnitude improvement of the experimental limits on the 2νβ+ EC, 2νEC/EC, and0νEC/EC decays of 58Ni.