Improved limits on ${\beta }^{+}$EC and ECEC processes in ${}^{74}$Se

Abstract

New limits on ${\beta }^{+}$EC and ECEC processes in ${}^{74}$Se have been obtained using a 600 cm${}^3$ HPGe detector and an external source consisting of 1600 g of a natural selenium powder. For different ${\beta }^{+}$EC and ECEC transitions (to the ground and excited states) obtained limits are on the level $\sim (0.2-4.8)\times 10^{19}$ yr at 90\% C.L. In particular, for the potentially resonant transition into the 1204.2 keV excited state of ${}^{74}$Ge a lower half-life limit of $1.1\times 10^{19}$ yr at 90\% C.L. has been obtained. Possibility to increase the sensitivity of such measurements is discussed.

16 pages, 3 figures. arXiv admin note: text overlap with arXiv:hep-ex/0610046