POSITRONIUM FORMATION IN COLLISIONS BETWEEN POSITRONS AND MONO AND DIELECTRONIC TARGETS

We study the formation of positronium through electron capture in collisions of positrons impacting on mono and dielectronic atoms (ions). We obtain the scattering amplitude of the charge exchange process by using the Coulomb Born Approximation (CBA). We apply the CBA approximation to the system e(+) + H(2s) and e(+) + He+(2s) with formation of positronium in the ground state. We also study the process e(+) + He(1s(2)) with formation of positronium in 1s, 2s and 2p states analysing the influence of the non-captured electron on the reaction. We compute differential and total cross sections for these reactions. The energy range varies from some eV to hundreds of eV. We compare our results with other theories and recent experimental data.