First observation of single beta decay of ${}^{96}$Zr

Abstract

The single beta decay of ${}^{96}$Zr has been detected for the first time using a 211 cm${}^3$ low-background HPGe detector and an external source consisting of two samples of enriched zirconium (atomic fraction of ${}^{96}$Zr is 88.28%, total mass is 140.65 g). During the search for the ${\hat{I}}^2$ decay of ${}^{96}$Zr, the ${\hat{I}}^2$ decay of the daughter nucleus ${}^{96}$Nb to the excited states of ${}^{96}$Mo has been observed. The ${\hat{I}}^3$-ray cascade produced by the ${}^{96}$Mo nucleus while de-exciting to the ground state has been detected with the HPGe detector. The experiment has been carried out at the Baksan Neutrino Observatory. It has produced 12625.34 h of data. The half-life of the single beta decay of ${}^{96}$Zr is measured to be $T_{1/2}=[2.27_{-0.36}^{+0.53}(stat)\pm 0.27(syst)]\times 10^{20}$ yr.