Dynamic microscopic study of pre-equilibrium giant resonance excitation and fusion in the reactions ${}^{132}$Sn+${}^{48}$Ca and ${}^{124}$Sn+${}^{40}$Ca

Abstract

We study pre-equilibrium giant dipole resonance excitation and fusion in the neutron-rich system ${}^{132}$Sn+${}^{48}$Ca at energies near the Coulomb barrier, and we compare photon yields and total fusion cross sections to those of the stable system ${}^{124}$Sn+${}^{40}$Ca. The dynamic microscopic calculations are carried out on a three-dimensional lattice using both the Time-Dependent Hartree-Fock method and the Density Constrained TDHF method. We demonstrate that the peak of the GDR excitation spectrum occurs at a substantially lower energy than expected for an equilibrated system, thus reflecting the very large prolate elongation of the dinuclear complex during the early stages of fusion. Our theoretical fusion cross-sections for both systems agree reasonably well with recent data measured at HRIBF.

Comments: 9 pages, 9 figures