POSITRON-ALKALI COLLISIONS WITH POSITRONIUM FORMATION AT INTERMEDIATE AND HIGH ENERGIES O. A. Foj=A2n*, R. Gayet+, J. Hanssen#, P. A. Hervieux# and R.D. Rivarola* * Instituto de F=A1sica Rosario (CONICET-UNR), Av. Pellegrini 250, (2000) Rosario, Argentina + Centre de Physique Th=82orique et de Mod=82lisations, Universit=82 de Bor= deaux I, Talence, France # Laboratoire de Physique Mol=82culaire et des Collisions, Institut de Physique Rue Arago, T=82chnop=93le 2000, Metz, France In this work, positronium formation through electron capture from ground state alkali targets is studied at intermediate and high impact energies by means of a distorted wave model. In particular, the interest is focused on electron capture from the inner shells of the target. Total cross sections are computed for several alkali targets and a comparison with other theories and experimental results is given. As expected from matching velocity arguments, as the impact energy increases the formation cross section is dominated by capture from the inner shells of the target.= =20