Pygmy and isovector giant dipole resonance in Lu-175

Abstract

The isovector electric giant dipole (E1) resonance (IVGDR) in well-deformed odd-proton Lu-175 is investigated using the Translational and Galilean Invariant-Quasiparticle Phonon Nuclear Model (TGI-QPNM) for the first time. E1 transition probabilities, radiation widths, photoabsorption cross-sections, and integrated moments (sigma(-2), sigma(-1), sigma(0), sigma(+1) and sigma(+2)) have been calculated up to 25 MeV using this model. The photoabsorption cross-section results show that Delta K = 0 and Delta K = +/- 1 modes split in I75 Lu due to large quadrupole deformation (prolate). Thus, a two-peak shape occurs, which is consistent with the available experimental data. The centroid energies and the widths of these peaks are also reproduced well. Besides, special attention is paid to the low-energy tail of GDR, particularly around the neutron separation energy, where an enhancement of electric dipole strength has been observed for many nuclei in recent years.