Absence of Low-Energy Shape Coexistence in ${}^{80}$Ge: The Nonobservation of a Proposed Excited 0${}_2^{+}$ Level at 639 keV

Abstract

The ${}^{80}$Ge structure was investigated in a high-statistics ${\hat{I}}^2$-decay experiment of ${}^{80}$Ga using the GRIFFIN spectrometer at TRIUMF-ISAC through ${\hat{I}}^3$, ${\hat{I}}^2$-$e$, $e$-${\hat{I}}^3$ and ${\hat{I}}^3$-${\hat{I}}^3$ spectroscopy. No evidence was found for the recently reported 0${}_2^{+}$ 639-keV level suggested as evidence for low-energy shape coexistence in ${}^{80}$Ge. Large-scale shell model calculations performed in ${}^{78,80,82}$Ge place the $0_2^{+}$ level in ${}^{80}$Ge at 2\,MeV. The new experimental evidence combined with shell model predictions indicate that low-energy shape coexistence is not present in ${}^{80}$Ge.