https://doi.org/10.1140/epja/i2006-08-040-7
Nuclear Physics in Astrophysics II
Nuclear structure far off stability --Implications for nuclear astrophysics
1
GSI, D-64291, Darmstadt, Germany
2
University of Sofia, Sofia, Bulgaria
3
Department of Physics and Astronomy, University of Tennessee, 37996, Knoxville, TN, USA
4
ISV, Uppsala University, Nyköping, Sweden
5
RRC Kurchatov Institute, RU-123481, Moscow, Russia
6
Katholieke Universiteit Leuven, Leuven, Belgium
* e-mail: h.grawe@gsi.de
Received:
20
June
2005
Accepted:
20
December
2005
Published online:
15
March
2006
The single-particle structure and shell gap of 100Sn as inferred from previous in-beam γ-ray spectroscopy has been confirmed in recent studies of seniority and spin-gap isomers by γγ, βγ, βpγ, pγ and 2pγ spectroscopy. The results for 94, 95Ag, 98Cd and its N = 50 isotones 96Pd and 94Ru stress the importance of large-scale shell model calculations employing realistic interactions for the isomerism, np-nh excitations, seniority mixing and E2 polarisation of the 100Sn core. The strong monopole interaction of the Δl = 0, 1 spin/isospin-flip partners πg 9/2- νg 7/2 along the N = 50 isotones and the πf 5/2- νg 9/2 pair of nucleons along the Z = 28 Ni isotopes are decisive for the evolution of the shell structure towards 100Sn and 78Ni. It can be traced back to the tensor force in the effective nucleon-nucleon interaction and provides a straightforward explanation for new shells in neutron-rich light nuclei, implying qualitative predictions for new N = 32, 34 subshells in Ca isotopes, persistence of the 78Ni proton and neutron shell gaps and non-equivalence of the g 9/2 valence mirror Ni isotopes and N = 50 isotones. This is corroborated by recent experimental data on 56, 58Cr and 70-76Ni. The implication of monopole driven shell evolution for apparent spin-orbit splitting towards N ≫ Z and structure along the astrophysical r-path between N = 50 and N = 82 is discussed.
PACS: 21.60.Cs Shell model – / 23.20.-g Electromagnetic transitions – / 27.30.+t 16 ⩽ A ⩽ 68 – / 27.60.+j 78 ⩽ A ⩽ 132 – / 26.50.+x Nuclear physics aspects of the r-process –
© Società Italiana di Fisica and Springer-Verlag, 2006