Localized 1ħω particle-hole strength in nuclei

A cross section enhancement, persisting to high momentum transfer, has been observed around 1ħω in excitation energy in spectra from inelastic proton-, alpha- and electron scattering on 90Zr, 116Sn, 196Pt and 208Pb. Data are presented for (p,p') at 201 MeV, (α, α') at 120 MeV and analyzed together with existing data obtained with 133.8 MeV polarized (p,p') on 116Sn and electron-scattering data on 116Sn and 196Pt. Two different interpretations of the observed enhancement are discussed: that of the incoherent sum of all 1ħω cross section and alternatively the sum over the isoscalar normal modes of all multipolarities.