High-Energy Electron Scattering and the Charge Distribution of Carbon-12 and Oxygen-16

The scattering of high-energy electrons from C/sup 12/ reported previously, was extended to 420 Mev. The elastic and inelastic scattering from the first excited level at 4.43 Mev was studied between 33 and 70 . The new data are in good agreement with what one would expect from the earlier measurements on C/sup 12/ performed at 187 Mev. Additional measurements of the elastic Ott-scattering cross sections of 240-, 360-, and 420-Mev electrons as functions of the scattering angle furnish information on the size and shape of the 0/sup 16/ nucleus. Pronounced diffraction minima in the angular distributions were observed for C/sup 12/ and O/sup 16/. The experimental results are compared with the predictions of a theoretical phaseshift analysis derived for the harmonic-well independent-particle model of the nucleus. Preliminary best fits confirm the shell-model predictions for the charge density distribution of these p-shell nuclei. The preliminary analysis of the data shows that the length parameter of the well is 1.66 x 10/sup -13/ cm for C/sup 12/, and 1.76 x 10/sup -13/cm for O/sup 16/, thus indicatirg a slight variation of the curvature of the harmonic well as the p shell is filled in. (auth)