Investigation of double beta decay of ${}^{100}$Mo to excited states of ${}^{100}$Ru

Abstract

Double beta decay of ${}^{100}$Mo to the excited states of daughter nuclei has been studied using a 600 cm${}^3$ low-background HPGe detector and an external source consisting of 2588 g of 97.5% enriched metallic ${}^{100}$Mo, which was formerly inside the NEMO-3 detector and used for the NEMO-3 measurements of ${}^{100}$Mo. The half-life for the two-neutrino double beta decay of ${}^{100}$Mo to the excited 0${}_1^{+}$ state in ${}^{100}$Ru is measured to be $T_{1/2}=[7.5\pm 0.6(stat)\pm 0.6(syst)]\cdot 10^{20}$ yr. For other $(0\nu +2\nu )$ transitions to the 2${}_1^{+}$, 2${}_2^{+}$, 0${}_2^{+}$, 2${}_3^{+}$ and 0${}_3^{+}$ levels in ${}^{100}$Ru, limits are obtained at the level of $\sim (0.25-1.1)\cdot 10^{22}$ yr.

19 pages, 4 figures. arXiv admin note: text overlap with arXiv:0904.1924