Improved limits on ${\beta }^{+}$EC and ECEC processes in ${}^{112}\mathrm{Sn}$

Limits on ${\beta }^{+}$EC and ECEC processes in ${}^{112}\mathrm{Sn}$ have been obtained using a 380 cm${}^3$ HPGe detector and an external source consisting of 100 g enriched tin (94.32% of ${}^{112}\mathrm{Sn}$). A limit with 90% C.L. on the ${}^{112}\mathrm{Sn}$ half-life of $1.3\times {10}^{21}$ yr for the ECEC(0$\nu$) transition to the $0_3^{+}$ excited state in ${}^{112}\mathrm{Cd}$ (1871 keV) has been established. This transition has been discussed in the context of a possible enhancement of the decay rate. The limits on other ${\beta }^{+}$EC and ECEC processes in ${}^{112}\mathrm{Sn}$ have also been obtained on the level of $(0.1-1.6)\times {10}^{21}$ yr at the 90% C.L.

Figure 1

Decay scheme of ${}^{112}\mathrm{Sn}$. Only the investigated levels associated with $\gamma$ rays are shown. Transition probabilities are given in percents.

Figure 2

Energy spectrum with 100 g of enriched Sn for 3175.23 h of measurement in investigated energy ranges [(500–630) and (650–750) keV].

Figure 3

Energy spectrum with 100 g of enriched Sn for 3175.23 h of measurement in investigated energy ranges [(780–880) and (1230–1330) keV].

Figure 4

Energy spectrum with 100 g of enriched Sn for 3175.23 h of measurement in investigated energy ranges [(1400–1500) and (1840–1940) keV].