Sub-barrier heavy-ion fusion/capture: Accurate accounting for zero-point quadrupole shape oscillations with realistic nucleus-nucleus potential

Abstract

Although the study of collisions of heavy ions resulting in formation of dinuclear systems has a long history this process still is a subject of experimental and scientific activities, partly because nowadays the heavy-ion fusion process is the only practical way for extending further the Periodic Table. Yet the heavy-ion capture cross sections are calculated theoretically with significant uncertainties. In particular, these cross sections below the barrier sometimes underestimate the experimental ones by orders of magnitude. In the literature, it had been shown that accounting for the Zero-Point Oscillations (ZPO) of the shape of colliding nuclei increased significantly the calculated capture cross sections. However, those calculations had been performed in a simplified way with a schematic nucleus-nucleus potential and for few reactions. The purpose of the present paper is to account for the ZPO in a more realistic way and to compare systematically the resulting capture cross sections with the experimental data. In the present paper, the nucleus-nucleus potential is evaluated using the semi-microscopical double-folding model with M3Y-Paris nucleon-nucleon forces. The nucleon densities needed for finding this potential are generated from the experimental three-parameter Fermi charge densities. The calculated capture cross sections are compared with the data for reactions 16O+54Fe, 58Ni, 144Nd, 148Sm, and 58Ni+54Fe, 58Ni, 60Ni. We show that there are certain regularities in the relationship between the experimental and theoretical cross sections with respect to the period of the quadrupole vibrations of the colliding nuclei at their ground states.