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Core-coupled protons, f 7 / 2 intruder states, and competing g 9 / 2 proton and neutron structures in<mml:math xmlns:…

2012; American Institute of Physics; Volume: 85; Issue: 2 Linguagem: Inglês

10.1103/physrevc.85.024309

1538-4497

C. J. Chiara, I. Ştefânescu, W. B. Walters, S. Zhu, R. V. F. Janssens, M. P. Carpenter, R. Broda, B. Fornal, A. A. Hecht, N. Hoteling, E.G. Jackson, B. P. Kay, W. Królas, T. Lauritsen, E. A. McCutchan, T. Pawłat, D. Seweryniak, X. Wang, A. Wöhr, J. Wrzesiński,

Atomic and Molecular Physics

The nuclei ${}^{65,67}$Cu were studied in reactions between a 430-MeV ${}^{64}$Ni beam and a thick ${}^{238}$U target with the Gammasphere array. Decay schemes for both nuclei have been extended, with spin and parity assignments of observed states constrained by measured $\ensuremath{\gamma}$-ray angular distributions and correlations. Positive-parity level structures, based on ${p}_{3/2}$ protons coupled to negative-parity states in the Ni cores, have been identified above the known $9/{2}^{+}$ states. In ${}^{67}$Cu, a negative-parity dipole band built upon a $\ensuremath{\pi}{f}_{7/2}^{\ensuremath{-}1}$ state has been observed, as were two shorter negative-parity sequences. A qualitative description of the level structures has been obtained through comparison with systematics of the odd-$A$${}^{57--71}$Cu isotopes and with states in the neighboring even-even Ni and Zn cores. Shell-model calculations using JUN45 and jj44b effective interactions were performed for ${}^{65,67}$Cu, with jj44b providing overall better agreement with the data. Both are limited, however, by the restriction that the ${f}_{7/2}$ and ${g}_{9/2}$ orbitals are not available simultaneously in the basis. Proton ${f}_{7/2}$ and neutron ${g}_{9/2}$ orbitals are required for the full negative-parity spectrum of states, while ${g}_{9/2}$ protons and neutrons are both important for positive-parity levels. The latter states are found to be better described in terms of weak coupling of a proton to the Ni core.