Beta Decay of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>68</mml:mn><mml:mo>–</mml:mo><mml:mn>74</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi>Ni</mml:mi></mml:math>and Level Structure of Neutron-Rich Cu Isotopes

The isotopes ${}^{68--74}\mathrm{Ni}$, of interest both for nuclear physics and astrophysics, have been produced in proton-induced fission of ${}^{238}\mathrm{U}$ and ionized in a laser ion guide coupled to an on-line mass separator. Their $\ensuremath{\beta}$ decay was studied by means of $\ensuremath{\beta}$- $\ensuremath{\gamma}$ and $\ensuremath{\gamma}$- $\ensuremath{\gamma}$ spectroscopy. Half-lives have been determined and production cross sections extracted. A partial level scheme is presented for ${}^{73}\mathrm{Cu}$ and additional levels for ${}^{71}\mathrm{Cu}$, providing evidence for a sharply lowered position of the $\ensuremath{\pi}{1f}_{5/2}$ orbital as occupancy of the $\ensuremath{\nu}{1g}_{9/2}$ state increases. The latter may have a clear impact on the predicted structure and decay properties of doubly magic ${}^{78}\mathrm{Ni}$.