Double Beta Decays into Excited States in ${}^{110}$Pd and ${}^{102}$Pd

Abstract

A search for double beta decays of ${}^{110}$Pd and ${}^{102}$Pd into excited states of the daughter nuclides has been performed using three ultra-low background gamma-spectrometry measurements in the Felsenkeller laboratory, Germany, the HADES laboratory, Belgium and at the LNGS, Italy. The combined Bayesian analysis of the three measurements sets improved half-life limits for the $2\hat{I}½{\hat{I}}^2{\hat{I}}^2$ and $0\hat{I}½{\hat{I}}^2{\hat{I}}^2$ decay modes of the $2_1^{+}$, $0_1^{+}$ and $2_2^{+}$ transitions in ${}^{110}$Pd to $2.9\cdot 10^{20}$ yr, $4.0\cdot 10^{20}$ yr and $3.0\cdot 10^{20}$ yr respectively and in ${}^{102}$Pd to $7.6\cdot 10^{18}$ yr, $8.8\cdot 10^{18}$ yr and $1.4\cdot 10^{19}$ yr respectively with 90% credibility.