“Bi-modal” isoscalar giant dipole strength in 58Ni

The strength distribution of the isoscalar giant dipole resonance (ISGDR) in 58Ni has been obtained over the energy range 10.5-49.5 MeV via extreme forward angle scattering (including 0°) of 386 MeV α particles. We observe a “bi-modal” E1 strength distribution for the first time in an A<90 nucleus. The observed ISGDR strength distribution is in reasonable agreement with the predictions of a recent RPA calculation.