$γ$-soft $^{146}$Ba and the role of non-axial shapes at N ~ 90

A. J. Mitchell; C. J. Lister; E. A. McCutchan; M. Albers; A. D. Ayangeakaa; P. F. Bertone; M. P. Carpenter; C. J. Chiara; P. Chowdhury; J. A. Clark; P. Copp; H. M. David; A. Y. Deo; B. DiGiovine; N. D'Olympia; R. Dungan; R. D. Harding; J. Harker; S. S. Hota; R. V. F. Janssens; F. G. Kondev; S. H. Liu; A. V. Ramayya; J. Rissanen; G. Savard; D. Seweryniak; R. Shearman; A. A. Sonzogni; S. L. Tabor; W. B. Walters; E. Wang; S. Zhu

doi:10.1103/physrevc.93.014306

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arXiv · 1512.06453

$γ$-soft $^{146}$Ba and the role of non-axial shapes at N ~ 90

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Abstract

Low-spin states in the neutron-rich, N = 90 nuclide $^{146}$Ba were populated following $β$-decay of $^{146}$Cs, with the goal of clarifying the development of deformation in Ba isotopes through delineation of their non-yrast structures. Fission fragments of $^{146}$Cs were extracted from a 1.7-Ci $^{252}$Cf source and mass-selected using the CARIBU facility. Low-energy ions were deposited at the center of a box of thin $β$ detectors, surrounded by a high-efficiency HPGe array. The new $^{146}$Ba decay scheme now contains 31 excited levels extending up to ~2.5 MeV excitation energy, double what was previously known. These data are compared to predictions from the Interacting Boson Approximation (IBA) model. It appears that the abrupt shape change found at N = 90 in Sm and Gd is much more gradual in Ba and Ce, due to an enhanced role of the $γ$ degree of freedom.

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A. J. Mitchell, C. J. Lister, E. A. McCutchan, M. Albers, A. D. Ayangeakaa, P. F. Bertone, M. P. Carpenter, C. J. Chiara, P. Chowdhury, J. A. Clark, P. Copp, H. M. David, A. Y. Deo, B. DiGiovine, N. D'Olympia, R. Dungan, R. D. Harding, J. Harker, S. S. Hota, R. V. F. Janssens, F. G. Kondev, S. H. Liu, A. V. Ramayya, J. Rissanen, G. Savard, D. Seweryniak, R. Shearman, A. A. Sonzogni, S. L. Tabor, W. B. Walters, E. Wang, S. Zhu. 2015-12-20. $γ$-soft $^{146}$Ba and the role of non-axial shapes at N ~ 90. https://doi.org/10.1103/physrevc.93.014306

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