Angular distributions were measured for excitation of the $2_1^{+}$(1.98), $2_2^{+}$(3.92), and $2_3^{+}$(5.26) states of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ by ${\pi }^{+}$ and ${\pi }^{\mathrm{-}}$ scattering at $T_{\pi }$=164 MeV. The data have been compared with distorted-wave impulse-approximation calculations using transition densities from the collective model, from electron scattering, and from the coexistence model. The calculations using (e,e’) transition densities reproduce the shapes of the angular distributions very well and the magnitudes of the cross sections to within 15%. The collective-model transition densities fail to fit the data unless the radius is adjusted from the ground-state value.

• Received 8 June 1987

DOI:https://doi.org/10.1103/PhysRevC.37.2057