ELECTROEXCITATION OF NE-20 GIANT ELECTRIC-DIPOLE AND ELECTRIC-QUADRUPOLE RESONANCES

Electrons at five energies between 60 and 120 MeV were used to study the giant electric-dipole and -quadrupole resonances in Ne20. Prominent electric-dipole peaks were found at 17.7, 19.1, 20.2, and 23 MeV in good agreement with photoreaction results. In addition our analysis reveals weaker fragmented electric-dipole strength in the region between 12.5 and 15 MeV. Prominent electric-quadrupole peaks were found at 13.0, 13.7, and 16.2 MeV, and a broad peak was found from 14.2 to 15.9 MeV. Two different analyses reveal a broad quadrupole excitation between 16 and 25 MeV. The dipole and quadrupole resonances deplete about 65% and 100% of the energy-weighted sum rule, respectively. [NUCLEAR REACTIONS Ne20(e,e′), E=59.5,84,7,89.8,109.6,119.7 MeV, q=0.35 ∼ 0.9 fm-1, enriched gas target, measured σ(E′θ) up to 25 MeV in excitation energy; deduced dipole and quadrupole strengths in giant resonance region.] © 1978 The American Physical Society.