Investigation of giant dipole resonance in heavy deformed nuclei with the EQMD model

Abstract

The deformation evolution of giant dipole resonance (GDR), in the chains of Sm and Nd isotopes, are investigated in the framework of an extended quantum molecular dynamics (EQMD) model. The mass number dependence of resonance peak position $(E_{m})$ in the major and minor axis directions of deformed nuclei as well as the difference $\Delta E_{m}$ between them are described in detail. The correlation between the splitting ($\Delta E_{m} /\bar{E}_m $) of the GDR spectra and the deformation($ \beta_{2}$) is further studied. The results confirm that $\Delta E_{m} /\bar{E}_m $ is proportional to $ \beta_{2}$. By comparing the calculation with the experimental data on photon absorption cross section $\sigma_{\gamma}$, it shows that the EQMD model can quite well reproduce the shape of GDR spectra from spherical to prolate shape. The GDR shapes in $^{134}$Sm, $^{136}$Sm, $^{138}$Sm, $^{130}$Nd, $^{132}$Nd and $^{134}$Nd are also predicted. In addition, the symmetry energy coefficient $(E_{sym})$ dependence of GDR spectra of $^{150}$Nd is also discussed. It is found that the calculated GDR spectrum in the EQMD model is perfectly consistent with the experimental results when $E_{sym}$ equals to 32 MeV.