Inelastic electron scattering fromO18

Inelastic electron scattering from the low-lying even-parity states of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ has been performed. The measurements span a range in momentum transfer from 0.6 to 2.7 ${\mathrm{fm}}^{-1\mathrm{}}$. Form factors have been determined for the two lowest $0^{+}$ excitations, the three lowest $2^{+}$ excitations, and the three lowest $4^{+}$ excitations. Transition densities for the $2^{+}$ and $4^{+}$ excitations have been obtained from a Fourier-Bessel analysis of these data. Comparisons were made with the predictions of various theoretical calculations and the agreement was found generally to be poor. A coexistence model was used to decompose the measured form factors into their single-particle and collective components, which in turn were compared with their counterparts in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$. The results indicate that this model provides a useful framework within which to understand the structure of the oxygen isotopes. Transition densities also were obtained within the context of this model.