Elastic electron scattering from 23 Na, 25 Mg and 27 Al and a shell-model interpretation

Elastic electron scattering cross sections for odd-A nuclei in the 1s-0d shell have been analysed in terms of large-basis shell-model wavefunctions. Even though these wavefunctions are expected to describe the configuration mixing adequately, the magnetic elastic scattering can only be explained if the valence orbitals are given a size which is 6-12% smaller than that required by the root-mean-square radius. No evidence is found to support the hypothesis that neutron and proton orbitals have different sizes. The M3 and M5 moments have been determined from the data.