Investigation of ${\hat{I}}^2{\hat{I}}^2$ decay in ${}^{150}$Nd and ${}^{148}$Nd to the excited states of daughter nuclei

Abstract

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 $T_{1/2}=[1.33_{-0.23}^{+0.36}(stat{)}_{-0.13}^{+0.27}(syst)]\cdot 10^{20}$ y. For other $(0\hat{I}½+2\hat{I}½)$ 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 $(0\hat{I}½+2\hat{I}½)$ 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.

13 pages, 6 figures