Investigations of dipole excitations in even-even Er and Os nuclei

In this thesis, electric dipole excitation of states in even-even deformed nuclei for three energy region (spectroscopic region (0-4 MeV), pygme dipole resonance-PDR (4-8 MeV); Giant dipole resonance-GDR (8-20 MeV) were investigated in the framework Quasi Random Phase Approximation (QRPA). Isoscaler and isovector interactions for the restoration of broken symmetries in the mean-field potential have been determined self-consistently. In this thesis, we have looked into details the effect of zero energy spurious state on the spectrum using the cases of QRPA with no restoration (NTGI), only restoration of Translational Invariance (TI), only restoration of Galileo Invariance (GI) and restoration of both Translational Invariance and Galileo Invariance. The B(E1) reduced transition probabilities of and and ( ) energies have been calculated for the190-192Os ve 166-168Er isotopes using the model.K=1 branch in the spectroscopic and GDR region, K=0 branch in the PDR region were observed that is dominant. Calculated photo absorption cross section ( ) is in good agreement with experimental data for Os isotopes where the peaks in the range of 13-15 MeV comes from K=0 and K=1 branch for deformed nuclei. Furthermore, (E1) decay width, reduced transition probabilities red(E1)have been investigated using some of the feature of electric dipole transitions.