Evolution of shell structure in neutron-rich calcium isotopes

Abstract

We employ interactions from chiral effective field theory and compute the binding energies and low-lying excitations of calcium isotopes with the coupled-cluster method. Effects of three-nucleon forces are included phenomenologically as in-medium two-nucleon interactions, and the coupling to the particle continuum is taken into account using a Berggren basis. The computed ground-state energies and the low-lying 2+ states for the isotopes 42,48,50,52Ca are in good agreement with data, and we predict the excitation energy of the first 2+ state in 54Ca at 1.9 MeV, displaying only a weak sub-shell closure. In the odd-mass nuclei 53,55,61Ca we find that the positive parity states deviate strongly from the naive shell model.

5 pages, 4 figures; small correction of effective 3NF and slight change of the corresponding parameters; updated figures and tables; main results and conclusions unchanged

References in corpus (13)

• Chiral effective field theory and nuclear forces
• Nuclear magic numbers: new features far from stability
• Improved nuclear matter calculations from chiral low-momentum interactions
• Shell Model in the Complex Energy Plane
• Three-Nucleon Low-Energy Constants from the Consistency of Interactions and Currents in Chiral Effective Field Theory
• Coupled-cluster theory for three-body Hamiltonians
• Shell Structure of Exotic Nuclei
• Medium-mass nuclei from chiral nucleon-nucleon interactions
• Cross-shell excitation in two-proton knockout: Structure of ${}^{52}$Ca
• Evidence for a change in the nuclear mass surface with the discovery of the most neutron-rich nuclei with 17<Z <25
• Chiral three-nucleon interaction and the carbon-14 dating beta decay
• Ab initio coupled-cluster theory for open-shell nuclei
• Study of neutron-rich calcium isotopes with a realistic shell-model interaction

Cited by in corpus (6)

• Three-body forces: From cold atoms to nuclei
• A monopole-optimized effective interaction for tin isotopes
• Three-body forces and proton-rich nuclei
• Elastic proton scattering of medium mass nuclei from coupled-cluster theory
• Living on the edge of stability, the limits of the nuclear landscape
• Spectroscopy of ${}^{26}$F to probe proton-neutron forces close to the drip line