Elastic and inelastic electron scattering from ${\mathrm{C}}^{12}$ and ${\mathrm{O}}^{16}$ has been studied for various scattered electron angles, using primary beam energies from 600 to 800 MeV. These studies cover a range of the square of the momentum transferred to the nucleus of 2.79 to 11.45 ${\mathrm{F}}^{-2\mathrm{}}$ for ${\mathrm{C}}^{12}$, and 2.79 to 8.52 ${\mathrm{F}}^{-2\mathrm{}}$ for ${\mathrm{O}}^{16}$. A procedure for subtracting the effects of energy loss due to radiation of the electrons is developed. With the resolution obtained in this experiment it is possible to resolve elastically scattered electrons from inelastically scattered electrons. In many instances it is also possible to resolve electrons which have excited discrete nuclear levels in ${\mathrm{C}}^{12}$ and ${\mathrm{O}}^{16}$. Inelastic electron scattering due to excitation of nuclear levels is observed for the 4.43-MeV $2^{+}$ and 9.6-MeV $3^{-}$ levels in ${\mathrm{C}}^{12}$, and for the 6.1-MeV levels in ${\mathrm{O}}^{16}$. Differential cross sections for excitation of these levels as well as for elastic scattering are determined. Absolute values of the cross sections are obtained by comparison with known absolute proton cross sections. Analysis of the data using the first Born approximation shows that the root-mean-square radii of ${\mathrm{C}}^{12}$ and ${\mathrm{O}}^{16}$ are 2.40±0.02 F and 2.65±0.04 F, respectively.

• Received 3 March 1966

DOI:https://doi.org/10.1103/PhysRev.148.1107