Electric dipole response in 156–170Er nuclei

Abstract

For the first time, this study investigated an energy region that covers both the Pygmy Dipole Resonance (PDR) and the Giant Dipole Resonance (GDR) for a broad set of even-even erbium isotopes. More specifically, translational and Galilean invariant (TGI-) quasiparticle random phase approximation (QRPA) was applied to investigate eight even-even 156–170Er isotopes. Through cross-section calculations, we obtained information about the structure of the GDR and PDR modes, as well as the splitting between the K = 0 and K = 1 branches. The PDR region was explored in more detail by investigating the region up to both 8 MeV and 10 MeV to determine the main distribution area of the PDR. It was found that only the E1 strengths below 8 MeV matched well with the well-known systematics of the PDR.