MICROSCOPIC STRUCTURE OF THE DIPOLE COMPRESSION MODE IN HEAVY NUCLEI

Abstract

Neutron decay of the isoscalar giant dipole resonance (ISGDR) has been studied in90Zr ,116Sn and208Pb using the (α,α′) reaction at a bombarding energy of 200 MeV. The same reaction was used to study proton decay of the ISGDR in58Ni and208Pb . Neutron and proton decay of the ISGDR to low-lying neutron and proton hole states in the daughter nuclei, respectively, allowed an experimental determination of the ISGDR microscopic structures. The determined branching ratios are compared to recent continuum random-phase-approximation (CRPA) calculations. Reasonable agreement was observed for208Pb and58Ni , whereas strong differences for90Zr and116Sn were found.