  Reaction cross sections of carbon isotopes for proton scattering are
calculated in large energy region. Density distributions of carbon isotopes are
obtained from relativistic mean field results. Calculations are based on two
procedures: the Glauber theory and relativistic impulse approximation, and
results are compared with each other as well as with experimental data. A
strong relationship between reaction cross section and root-mean-square radius
is clearly shown for 12C using a model distribution.
