Electroexcitation of negative-parity states in O18

Form-factor measurements in the momentum-transfer range 0.6q2.7 fm-1 are presented for the 1- levels in O18 at 4.46, 6.20, 7.62, and 8.04 MeV, the 3- levels at 5.10, 6.40, and 8.29 MeV, and the 5- levels at 7.86 and 8.13 MeV. These are the first measurements of the 5- states by inelastic scattering and the first electron-scattering measurements of the higher 1- and 3- states. A Rosenbluth separation of the longitudinal and transverse form factors was performed by fitting the data with a phenomenological polynomial-times-Gaussian parametrization motivated by the form of theoretical form factors when harmonic-oscillator wave functions are used. Comparisons are made with structure models. The Coulomb form factors of several levels indicate the significance of small admixtures of 3Latin small letter h with stroke components in the negative-parity wave functions.