  Results for elastic electron scattering by nuclei, calculated with charge
densities of Skyrme forces and covariant effective Lagrangians that accurately
describe nuclear ground states, are compared against experiment in stable
isotopes. Dirac partial-wave calculations are performed with an adapted version
of the ELSEPA package. Motivated by the fact that studies of electron
scattering off exotic nuclei are intended in future facilities in the
commissioned GSI and RIKEN upgrades, we survey the theoretical predictions from
neutron-deficient to neutron-rich isotopes in the tin and calcium isotopic
chains. The charge densities of a covariant interaction that describes the
low-energy electromagnetic structure of the nucleon within the Lagrangian of
the theory are used to this end. The study is restricted to medium and heavy
mass nuclei because the charge densities are computed in mean field approach.
Since the experimental analysis of scattering data commonly involves
parameterized charge densities, as a surrogate exercise for the yet unexplored
exotic nuclei, we fit our calculated mean field densities with Helm model
distributions. This procedure turns out to be helpful to study the
neutron-number variation of the scattering observables and allows us to
identify correlations of potential interest among some of these observables
within the isotopic chains.
