Shape coexistence and the role of axial asymmetry in $^{72}$Ge

A. D. Ayangeakaa; R. V. F. Janssens; C. Y. Wu; J. M. Allmond; J. L. Wood; S. Zhu; M. Albers; S. Almaras-Calderon; B. Bucher; M. P. Carpenter; C. J. Chiara; D. Cline; H. L. Crawford; H. M. David; J. Harker; A. B. Hayes; C. R. Hoffman; B. P. Kay; K. Kolos; A. Korichi; T. Lauritsen; A. O. Macchiavelli; A. Richard; D. Seweryniak; A. Wiens

doi:10.1016/j.physletb.2016.01.036

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arXiv · 1603.04484

Shape coexistence and the role of axial asymmetry in $^{72}$Ge

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Abstract

The quadrupole collectivity of low-lying states and the anomalous behavior of the $0^+_2$ and $2^+_3$ levels in $^{72}$Ge are investigated via projectile multi-step Coulomb excitation with GRETINA and CHICO-2. A total of forty six $E2$ and $M1$ matrix elements connecting fourteen low-lying levels were determined using the least-squares search code, gosia. Evidence for triaxiality and shape coexistence, based on the model-independent shape invariants deduced from the Kumar-Cline sum rule, is presented. These are interpreted using a simple two-state mixing model as well as multistate mixing calculations carried out within the framework of the triaxial rotor model. The results represent a significant milestone towards the understanding of the unusual structure of this nucleus.

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A. D. Ayangeakaa, R. V. F. Janssens, C. Y. Wu, J. M. Allmond, J. L. Wood, S. Zhu, M. Albers, S. Almaras-Calderon, B. Bucher, M. P. Carpenter, C. J. Chiara, D. Cline, H. L. Crawford, H. M. David, J. Harker, A. B. Hayes, C. R. Hoffman, B. P. Kay, K. Kolos, A. Korichi, T. Lauritsen, A. O. Macchiavelli, A. Richard, D. Seweryniak, A. Wiens. 2016-03-14. Shape coexistence and the role of axial asymmetry in $^{72}$Ge. https://doi.org/10.1016/j.physletb.2016.01.036

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