Observation of isoscalar multipole strengths in exotic doubly-magic 56 Ni in inelastic α scattering in inverse kinematics

The Isoscalar Giant Monopole Resonance (ISGMR) and the Isoscalar Giant Dipole Resonance (ISGDR) compression modes have been studied in the doubly-magic unstable nucleus Ni-56. They were measured by inelastic alpha-particle scattering in inverse kinematics at 50MeV/u with the MAYA active target at the GANIL facility. The centroid of the ISGMR has been obtained at E-x= 19.1 +/- 0.5 MeV. Evidence for the low-lying part of the ISGDR has been found at E-x = 17.4 +/- 0.7 MeV. The strength distribution for the dipole mode shows similarity with the prediction from the Hartree-Fock (HF) based random-phase approximation (RPA)[1]. These measurements confirm inelastic a-particle scattering as a suitable probe for exciting the ISGMR and the ISGDR modes in radioactive isotopes in inverse kinematics. (C) 2015 The Authors. Published by Elsevier B.V.