In the PS209 experiments at CERN two kinds of measurements were performed: the in-beam measurement of X-rays from antiprotonic atoms and the radiochemical, off-line determination of the yield of annihilation products with mass number A_t -1 (less by 1 than the target mass). Both methods give observables which allows to study the peripheral matter density composition and distribution. A comparisons of the PS209 results with the theoretical and semiempirical predictions for neutron and proton densities and with the differences \Delta r_np of the rms radii of neutrons and protons obtained in other experiments are also presented.

PACS numbers: 36.10.--k, 21.10.Gv, 13.75.Cs