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

TL;DR

This study uses microscopic simulations to analyze pre-equilibrium giant dipole resonance excitation and fusion in neutron-rich and stable tin-calcium systems near the Coulomb barrier, revealing early-stage elongation effects and matching experimental fusion data.

Contribution

It introduces a detailed microscopic approach using TDHF and DCTDHF to investigate pre-equilibrium GDR and fusion dynamics in specific tin-calcium reactions, highlighting early elongation effects.

Findings

GDR excitation spectrum peaks at lower energy due to elongation.

Fusion cross-sections align with experimental measurements.

Early-stage dinuclear elongation influences resonance behavior.

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.