The spectra of 146-MeV $\alpha$ particles scattered inelastically from ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ exhibit a giant-resonance-type structure between excitation energies of 15.9 and 27.3 MeV. The analysis of angular distributions shows its quadrupole nature and yields a strength exhausting about 65% of the isoscalar $E2\mathrm{}$ energy-weighted sum rule.

• Received 16 June 1975

DOI:https://doi.org/10.1103/PhysRevLett.35.779