Shell structure from 100Sn to 78Ni: Implications for nuclear astrophysics.

The single-particle structure and shell gap of ¹⁰⁰Sn is inferred from prompt in-beam and delayed γ-ray spectroscopy of seniority and spin-gap isomers. Recent results in ^{94, 95}Ag and ⁹⁸Cd stress the importance of large-scale shell model calculations employing realistic interactions for the isomerism, np- nh excitations and E2 polarisation of the ¹⁰⁰Sn core. The strong monopole interaction of the Δ l = 0 spin-flip partners π g_9/2- ν g_7/2 in N = 51 isotones below ¹⁰⁰Sn is echoed in the Δ l = 1 π f_5/2- ν g_9/2 pair of nucleons, which is decisive for the persistence of the N = 50 shell gap in ⁷⁸Ni. This is corroborated by recent experimental data on ^{70, 76}Ni, ⁷⁸Zn. The importance of monopole driven shell evolution for the appearance of new shell closures in neutron-rich nuclei and implications for r-process abundances near the N = 82 shell is discussed. [ABSTRACT FROM AUTHOR]