Search for $β^+$EC and ECEC processes in ${}^{112}$Sn and $β^-β^-$ decay of ${}^{124}$Sn to the excited states of ${}^{124}$Te

Abstract

Limits on $β^+$EC and ECEC processes in ${}^{112}$Sn and on $β^-β^-$ decay of ${}^{124}$Sn to the excited states of ${}^{124}$Te have been obtained using a 380 cm${}^3$ HPGe detector and an external source consisting of natural tin. A limit with 90% C.L. on the ${}^{112}$Sn half-life of $0.92\times 10^{20}$ y for the ECEC(0$\hat{I}½$) transition to the $0_3^{+}$ excited state in ${}^{112}$Cd (1871.0 keV) has been established. This transition is discussed in the context of a possible enhancement of the decay rate by several orders of magnitude given that the ECEC$(0\hat{I}½)$ process is nearly degenerate with an excited state in the daughter nuclide. Prospects for investigating such a process in future experiments are discussed. The $β^-β^-$ decay limits for ${}^{124}$Sn to the excited states of ${}^{124}$Te were obtained on the level of $(0.8-1.2)\times 10^{21}$ y at the 90% C.L.

17 pages, 5 figures