  The chemical evolution of the Galaxy is followed for the elements affected by
neutron capture, in particular for those in the atomic number range 56 to 63
(Ba, La, Ce, Pr, Nd, Sm and Eu). Neutrons by the major 13^C source, released in
radiative conditions in the interpulse periods of TP-AGB stars, give rise to an
efficient s-processing, making low-mass AGB the major contributors to the
chemical evolution of heavy elements. The s-process scenario, characterized is
analyzed using AGB stellar evolutionary calculations with the FRANEC Code
(FRASCATI Raphson-Newton Evolutionary Code), and are applied over a wide range
of stellar masses and metallicities. The presence of r-process elements in low
metallicity stars is indicative of a prompt enrichment of the Galaxy by early
generation of stars, and low mass SNII appear to be good candidates for primary
production of r-nuclei. The chemical evolution model used here is organized
over three-zone, halo, thick and thin disk.
