Nuclear charge distribution and rms radius ofC12from absolute elastic electron scattering measurements

Elastic electron scattering cross sections for the nucleus ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ have been measured in a momentum transfer range from 0.25 to 2.75 ${\mathrm{fm}}^{-1\mathrm{}}$. The data were analyzed in a model independent way with a Fourier-Bessel parametrization of the charge distribution. For the rms radius, the value ${〈r^2〉}^{\frac{1}{2}}=(2.464\mathrm{}\pm 0.012)$ fm (no dispersion corrections applied) has been obtained, and agrees with those of other electron scattering experiments and with muonic atom experiments, but disagrees with data obtained from measurements of muonic x-ray transitions with a crystal spectrometer which show a larger rms radius. The extracted distribution disagrees with Hartree-Fock calculations in both the radial dependence and the rms radius. The behavior of the form factor in the diffraction minimum was investigated in detail. The experimentally determined cross sections in the minimum are always larger than those obtained from the Fourier-Bessel analysis. These deviations amounted to 5% for a primary energy of 320 MeV and to 2% for 240 MeV and may be interpreted as an indication of dispersion effects.