标题： 在$^{112}$Sn 和$β^-β^-$衰变中搜索$β^+$EC 和 ECEC 过程，以及到$^{124}$Te 激发态的$^{124}$Sn 衰变 显示英文标题

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

摘要： 对 $\beta^+$EC 和 ECEC 过程在 $^{112}$Sn 中以及对 $\beta^-\beta^-$ 的 $^{124}$Sn 到 $^{124}$Te 激发态的衰变进行了研究，使用了 380 cm$^3$HPGe 探测器和由天然锡组成的外部源。90% 置信度的限制 在$^{112}$Sn 的半衰期为$0.92\times 10^{20}$y 的情况下，ECEC(0$\nu$) 转变到$0^+_3$激发态在$^{112}$Cd (1871.0 keV) 中已经确定。 该转变是在可能的衰变率增强几个数量级的背景下讨论的，因为 ECEC$(0\nu)$过程与子核素中的激发态几乎简并。 讨论了在未来实验中研究此类过程的前景。 $\beta^-\beta^-$衰变限制对于$^{124}$Sn 到$^{124}$Te 激发态的测量是在 90% 置信度水平上达到$(0.8-1.2)\times 10^{21}$的。 显示英文摘要

摘要： Limits on $\beta^+$EC and ECEC processes in $^{112}$Sn and on $\beta^-\beta^-$ 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$\nu$) 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$(0\nu)$ process is nearly degenerate with an excited state in the daughter nuclide. Prospects for investigating such a process in future experiments are discussed. The $\beta^-\beta^-$ 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.