Persistence of the $Z=28$ Shell Gap Around $^{78}\mathrm{Ni}$: First Spectroscopy of $^{79}\mathrm{Cu}$

In-beam γ-ray spectroscopy of Cu79 is performed at the Radioactive Isotope Beam Factory of RIKEN. The nucleus of interest is produced through proton knockout from a Zn80 beam at 270  MeV/nucleon. The level scheme up to 4.6 MeV is established for the first time and the results are compared to Monte Carlo shell-modelcalculations. We do not observe significant knockout feeding to the excited states below 2.2 MeV, which indicates that the Z=28 gap at N=50 remains large. The results show that the Cu79 nucleus can be described in terms of a valence proton outside a Ni78 core, implying the magic character of the latter.