Elastic electron scattering from 13C

Using a target material consisting of methane enriched to 58% in 13 C, we have studied elastic electron scattering of 250 MeV energy incident electrons at a variety of angles. The absolute target density was determined by electron scattering from the nuclei of hydrogen contained in the methane, and by comparing the measured cross sections with known proton cross sections. The contribution to the elastic scattering due to the 12 C in the target material has been subtracted by a calculation which uses previously measured 12 C cross sections. The data are analysed using a harmonic oscillator model. The ratio of the rms radius of the charge distribution for 13 C to that of 12 C is found to be 0.96±0.01.