  We calculate differential cross sections for proton-nucleus elastic
scattering by using a Glauber theory in the optical limit approximation and
nucleon distributions that can be obtained in the framework of macroscopic
nuclear models in a way dependent on the equation of state of uniform nuclear
matter near the saturation density. We find that the peak angle calculated for
unstable neutron-rich nuclei in the small momentum transfer regime increases as
the parameter L characterizing the density dependence of the symmetry energy
decreases. This is a feature associated with the L dependence of the predicted
matter radii.
