Isoscalar giant dipole resonance for several nuclei with A ≥ 90 Original Research Article

The giant resonance region in several nuclei in A ≥ 90 have been re-measured using 240 MeV α particle scattering with a detector provides that both horizontal and vertical angles. Slice analyses with multipole fits were performed and strength due to both low and high energy components of the isoscalar giant dipole resonance (ISGDR) was identified. E1 strengths for the high energy component corresponding to 70±15%,68±15% and 67±14% of the isoscalar E1 energy-weighted sum rule were identified, with centroid energies of 26.3±0.6 MeV, 24.7±0.6 MeV and 21.7±0.6 MeV for90Zr,144Sm and208Pb, respectively. The centroid of the high energy component of the strength distribution is in closer agreement with the microscopic prediction generated using compressibilities obtained from the isoscalar giant monopole resonance data.