Electroexcitation of isoscalar states in sup16O

We report high resolution measurements of inelastic electron scattering to all narrow normal-parity states of O16 up to 12.05 MeV, which include states with Jn(Ex MeV): 02+(6.049), 03+(12.049), 11-(7.117), 21+(6.917), 22+(9.845), 23+(11.52), 31-(6.130), 41+(10.356), and 42+(11.097). The measurements were performed primarily at 90°and 160°and span momentum transfers between 0.6 and 2.6 fm-1. Improved line shape fitting techniques have been developed. These are the first electron scattering measurements for the 42+ state and of second form-factor maxima for several states. The form factor for excitation of the 22+ 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 O16. Comparisons have been made with several structure models, including the Brown-Green model, the weak-coupling model, a 2Latin small letter h with stroke shell model, and the tetrahedral alpha-cluster model.