Testing mean-field models near the N=Z line: γ-ray spectroscopy of the Tz=1/2 nucleus 73Kr

N. S. Kelsall*, S. M. Fischer, D. P. Balamuth, G. C. Ball, M. P. Carpenter, R. M. Clark, J. Durell, P. Fallon, S. J. Freeman, P. A. Hausladen, R. V.F. Janssens, D. G. Jenkins, M. J. Leddy, C. J. Lister, A. O. Macchiavelli, D. G. Sarantites, D. C. Schmidt, D. Seweryniak, C. E. Svensson, B. J. VarleyS. Vincent, R. Wadsworth, A. N. Wilson, A. V. Afanasjev, S. Frauendorf, I. Ragnarsson, R. Wyss

*Corresponding author for this work

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Excited states in the N=Z+1 nucleus 73Kr have been investigated using the 40Ca(36Ar, 2pn) and 40Ca(40Ca, α2pn) reactions at 145 and 160 MeV, respectively. γ rays were detected using the Gammasphere array and events were recorded in coincidence with charged-particle and neutron detectors. The three previously observed bands were extended to high spin, and a new unfavored positive-parity band has been observed. The alignment characteristics and decay properties of the bands are all consistent with large-deformation prolate rotation, with no clear evidence for oblate bands or shape coexistence. This is quite different from neighboring 72,74Kr, indicating a strong shape-stabilizing role for the valence neutron. The experimental results are compared to extended total Routhian surface, cranked Nilsson Strutinsky, and cranked relativistic mean-field calculations. The results suggest that the paired calculations lack some important physics. Neutron-proton correlations may be the missing ingredient. There is also evidence for an unusual band crossing in the negative-parity bands, which may indicate the presence of T=0 pairing correlations. At high spin all the models can reproduce the experimental data.

Original languageEnglish
Pages (from-to)443311-4433113
Number of pages3989803
JournalPhysical Review C - Nuclear Physics
Issue number4
Publication statusPublished - 1 Apr 2002

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