Quadrupole and octupole collectivity and cluster structures in neon isotopes

Abstract

The lowest positive- and negative-parity bands of ${}^{20}$Ne and neutron-rich even-even Ne isotopes are investigated using a theoretical framework based on energy density functionals. Starting from a self-consistent relativistic Hartree-Bogoliubov calculation of axially-symmetric and reflection-asymmetric deformation energy surfaces, the collective symmetry-conserving states are built using projection techniques and the generator coordinate method. Overall a good agreement with the experimental excitation energies and transition rates is obtained. In particular, the model provides an accurate description of the excitation spectra and transition probabilities in ${}^{20}$Ne. The contribution of cluster configurations to the low-energy states is discussed, as well as the transitional character of the ground state. The analysis is extended to ${}^{22}$Ne and the shape-coexisting isotope ${}^{24}$Ne, and to the drip-line nuclei ${}^{32}$Ne and ${}^{34}$Ne. The role of valence neutrons in the formation of molecular-type bonds between clusters is discussed.

Comments: 16 pages, 15 figures, 2 tables, Accepted for Publication in Physical Review C