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%'e report high resolution measurements of inelastic electron scattering to all narrow normalparity states of '60 up to 12.05 MeV, which include states with J"(E"MeV): 0~+(6.049),The measurements were performed primarily at 90' and 160' and span momentum transfers between 0.6 and 2.6 fm '. Improved line shape fitting techniques have been developed. These are the first electron scattering measurements for the 4~+ state and of second form-factor maxima for several states. The form factor for excitation of the 2+2 state is strikingly different from that of the other 2+ states and indicates a transition density peaked in the interior. Transition charge densities were extracted from a combined data set that includes earlier electron scattering data renormalized to a recent analysis of elastic scattering from ' O. Comparisons have been made with several structure models, including the Brown-Green model, the weak-coupling model, a Pun shell model, and the tetrahedral alpha-cluster model.

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We report electron scattering form factors for known 4 states in ' 0 at 17.79 and 18.98 MeV.We also report statistical upper bounds for the 4 state at 19.80 MeV. The ratios of these form factors are consistent with the isospin amplitudes derived from pion scattering data. The form factors of levels observed in (e, e') at 17.880+0.015, 18.635+0.020, and 20. 510+0.025 MeV are compatible with 4 T =1 assignments. Existing (n, m') and (p, p') spectra do not contradict these identifications.The 4 form factors are well described by a harmonic-oscillator density with oscillator length b =1.58 fm. This value is substantially smaller than the value of 1.77 fm obtained from the ground state charge density. The form factor of the 18.98 MeV state can also be fitted by a Woods-Saxon transition density, with parameters fitted to the elastic M5 multipole of "O. The fit is improved by inclusion of meson-exchange currents. However, the isoscalar-isovector differences in the WoodsSaxon plus meson-exchange current form factors result in a poor fit to the 17.79 MeV state. The total isovector and isoscalar strengths observed for the established 4 states are 41% and 23%, respectively, of a pure single-particle prediction.

Photoejection of both electrons from the H" ion by a single incident photon has been observed with use of a crossed-relativistic-beam technique. The dipole selection rules for a single photon pick out the i P° final state. The relative cross section was measured over a 0.30-eV range of photon energies near threshold in steps of 0.007 eV with a resolution of 0.007 eV full width at half maximum. The energy dependence of the cross section in this region was consistent with a Wannier threshold law.