Evolution of the N=50 gap from Z=30 to Z=38 and extrapolation towards 78Ni

Abstract

The evolution of the N=50 gap is analyzed as a function of the occupation of the proton f5/2 and p3/2 orbits. It is based on experimental atomic masses, using three different methods of one or two-neutron separation energies of ground or isomeric states. We show that the effect of correlations, which is maximized at Z=32 could be misleading with respect to the determination of the size of the shell gap, especially when using the method with two-neutron separation energies. From the methods that are the least perturbed by correlations, we estimate the N=50 spherical shell gap in 78Ni. Whether 78Ni would be a rigid spherical or deformed nucleus is discussed in comparison with other nuclei in which similar nucleon-nucleon forces are at play.

7 pages, 8 figures, accepted for publication PRC (22 december 2011)

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Cited by in corpus (6)

• Large scale shell model calculations along Z=28 and N=50 closures: towards the doubly-magic 78Ni
• Evolution of the N=28 shell closure: a test bench for nuclear forces
• Dipole and quadrupole moments of ${}^{73-78}$Cu as a test of the robustness of the $Z=28$ shell closure near ${}^{78}$Ni
• Shape coexistence in even-even nuclei: A theoretical overview
• Extinction of the N=20 neutron-shell closure for 32Mg examined by direct mass measurements
• Suddenly shortened half-lives beyond ${}^{78}$Ni: $N=50$ magic number and high-energy non-unique first-forbidden transitions