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29Na: Defining the edge of the Island of Inversion for Z=11

Vandana Tripathi·S. L. Tabor·P. F. Mantica·C. R. Hoffman·M. Wiedeking·A. D. Davies·S. N. Liddick·W. F. Mueller·T. Otsuka·A. Stolz·B. E. Tomlin·Y. Utsuno·A. Volya
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Abstract

The low-energy level structure of the exotic Na isotopes 28,29Na has been investigated through beta-delayed gamma spectroscopy. The N=20 isotones for Z=10-12 are considered to belong to the ``island of inversion'' where intruder configurations dominate the ground state wave function. However, it is an open question as to where and how the transition from normal to intruder-dominated configurations happens in an isotopic chain. The present work, which presents the first detailed spectroscopy of 28,29Na, clearly demonstrates that such a transition in the Na isotopes occurs between 28Na (N=17) and 29Na (N=18), supporting the smaller N=20 shell gap in neutron rich sd shell nuclei. The evidence for inverted shell structure is found in intruder dominated spectroscopy of low-lying states, beta-decay branching ratios and shell model analysis.

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Vandana Tripathi, S. L. Tabor, P. F. Mantica, C. R. Hoffman, M. Wiedeking, A. D. Davies, S. N. Liddick, W. F. Mueller, T. Otsuka, A. Stolz, B. E. Tomlin, Y. Utsuno, A. Volya. 2004-11-17. 29Na: Defining the edge of the Island of Inversion for Z=11. https://doi.org/10.1103/physrevlett.94.162501

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