The structure of ${}^{80}\mathrm{Ge}$ has been investigated at the ISOLDE facility at CERN. A previous study reported for the first time a low-lying $0_2^{+}$ intruder state at 639 keV, based on the coincidence with a previously unobserved 1764-keV $\gamma$ ray, and suggested it as evidence for shape coexistence in ${}^{80}\mathrm{Ge}$. We used the $\beta$ decay from the $3^{-}$ 22.4-keV state in ${}^{80}\mathrm{Ga}$ to enhance the population of low-spin states in ${}^{80}\mathrm{Ge}$, including any excited $0^{+}$ level, and $\gamma \gamma$ coincidences to investigate it. We observed a 1764-keV $\gamma$ ray in coincidence with strong transitions in ${}^{80}\mathrm{Ge}$, thus not feeding the proposed 639-keV $0_2^{+}$. No connecting transitions from previously known levels to the 639-keV and 2403-keV $2_3^{+}$ states could be established either. Shell-model calculations for Ge isotopes and $N=48$ isotones were performed. They succeed to explain most of the experimental levels, but fail to reproduce the presence of a $0_2^{+}$ state below $\approx 1200$ keV in ${}^{80}\mathrm{Ge}$. Our experimental findings and shell-model calculations are difficult to reconcile with a very low-lying $0_2^{+}$ state in ${}^{80}\mathrm{Ge}$.

• Received 20 October 2020
• Revised 23 July 2021
• Accepted 27 July 2021

DOI:https://doi.org/10.1103/PhysRevC.104.024317

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Published by the American Physical Society