Probing the isovector transition strength of the low-lying nuclear excitations induced by inverse kinematics proton scattering

A compact approach based on the folding model is suggested for the determination of the isoscalar and isovector transition strengths of the low-lying (∆S = ∆T = 0) excitations induced by inelastic proton scattering measured with exotic beams. Our analysis of the recently measured inelastic O+p scattering data at Elab = 30 and 43 MeV/nucleon has given for the first time an accurate estimate of the isoscalar β0 and isovector β1 deformation parameters (which cannot be determined from the (p,p’) data alone by standard methods) for 2+1 and 3 − 1 excited states in O. Quite strong isovector mixing was found in the 2+1 inelastic O+p scattering channel, where the strength of the isovector form factor F1 (prototype of the Lane potential) corresponds to a β1 value almost 3 times larger than β0 and a ratio of nuclear transition matrix elements Mn/Mp ≃ 4.2.