Abstract
The excited states of were investigated via -ray spectroscopy following decay. By exploiting angular correlation analysis, the , , , and states in were firmly established. The -ray branching and mixing ratios for transitions deexciting the , , and states were measured, allowing for the extraction of relative values. In particular, the and transitions were observed for the first time. The results show excellent agreement with new microscopic large-scale shell-model calculations, and are discussed in terms of underlying shapes, as well as the role of neutron excitations across the gap. Enhanced axial shape asymmetry (triaxiality) is suggested to characterize in its ground state. Furthermore, an excited band with a significantly larger softness in its shape is identified. A shore of the “island of inversion” appears to manifest above , previously thought as its northern limit in the chart of the nuclides.
- Received 2 August 2022
- Revised 28 November 2022
- Accepted 9 February 2023
DOI:https://doi.org/10.1103/PhysRevLett.130.122502
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