Investigation of ββ\beta\beta decay in 150^{150}Nd and 148^{148}Nd to the excited states of daughter nuclei

Double beta decay of $^{150}$Nd and $^{148}$Nd to the excited states of daughter nuclei have been studied using a 400 cm$^3$ low-background HPGe detector and an external source consisting of 3046 g of natural Nd$_2$O$_3$ powder. The half-life for the two-neutrino double beta decay of $^{150}$Nd to the excited 0$^+_1$ state in $^{150}$Sm is measured to be $T_{1/2}=[1.33^{+0.36}_{-0.23}(stat)^{+0.27}_{-0.13}(syst)]\cdot 10^{20}$ y. For other $(0\nu + 2\nu)$ transitions to the 2$^+_1$, 2$^+_2$, 2$^+_3$, and 0$^+_2$ levels in $^{150}$Sm, limits are obtained at the level of $\sim (2-8)\cdot 10^{20}$ y. In the case of $^{148}$Nd only limits for the $(0\nu + 2\nu)$ transitions to the 2$^+_1$, 0$^+_1$, and 2$^+_2$ excited states in $^{148}$Sm were obtained and are at the level of \sim (4-8)\cdot 10^{20}$ y.Comment: 13 pages, 6 figure

Average and recommended half-life values for two neutrino double beta decay: upgrade-2013

All existing positive results on two neutrino double beta decay in different nuclei were analyzed. Using the procedure recommended by the Particle Data Group, weighted average values for half-lives of $^{48}$Ca, $^{76}$Ge, $^{82}$Se, $^{96}$Zr, $^{100}$Mo, $^{100}$Mo - $^{100}$Ru ($0^+_1$), $^{116}$Cd, $^{130}$Te, $^{136}$Xe, $^{150}$Nd, $^{150}$Nd - $^{150}$Sm ($0^+_1$) and $^{238}$U were obtained. Existing geochemical data were analyzed and recommended values for half-lives of $^{128}$Te and $^{130}$Ba are proposed. I recommend the use of these results as the most currently reliable values for half-lives.Comment: 9 p, Invited talk at MEDEX'13 (Prague, Czech Republic, June 11-14, 2013

Main features of detectors and isotopes to investigate double beta decay with increased sensitivity

The current situation in double beta decay experiments , the characteristics of modern detectors and the possibility of increasing the sensitivity to neutrino mass in future experiments are discussed. The issue of the production and use of enriched isotopes in double beta decay experiments is discussed in addition.Comment: 25 pages, 2 figures, 10 table