The effect of deformation in the isoscalar giant dipole resonance

Background-free inelastic scattering spectra have been obtained for 144,148,150,152,154Sm with 386 MeV alpha particles at forward angles (including 0degrees) to investigate the effect of deformation on the isoscalar giant dipole resonance. The strength distributions for isoscalar giant resonances have been extracted via a multipole decomposition analysis using angular distributions calculated in the framework of the density-dependent single-folding model. The effects of deformation are found to be different for the low- and high-excitation energy components of the isoscalar giant dipole resonance. Evidence has been obtained for the theoretically-predicted mixing between the isoscalar giant dipole resonance and the high energy octupole resonance