Structure of the Isovector Dipole Resonance in Neutron-Rich ${}^{60}Ca$ Nucleus and Direct Decay from Pygmy Resonance

Abstract

The structure of the isovector dipole resonance in neutron-rich calcium isotope, ${}^{60}Ca$, has been investigated by implementing a careful treatment of the differences of neutron and proton radii in the continuum random phase approximation ($RPA$). The calculations have taken into account the current estimates of the neutron skin. The estimates of the escape widths for direct neutron decay from the pygmy dipole resonance ($PDR$) were shown rather wide, implicating a strong coupling to the continuum. The width of the giant dipole resonance ($GDR$) was evaluated, bringing on a detailed discussion about its microscopic structure.

13 pages, 2 figures, RevTex4