THE POSITRON HYDROGEN SYSTEM IN A 6 STATE MODEL

Close coupling calculations of positron-hydrogen scattering using a si x state model (H(1s, 2s, 2p), Ps(1s, 2s, 2p)) are completed for incide nt energies from zero to 4.0 Rydberg. The calculations are very compre hensive and all cross sections and phaseshifts for the e+-H(1s)entranc e channels have been computed. The cross sections for positronium form ation in the Ps(1s), Ps(2s) and Ps(2p) levels underestimate the latest experimental values. Cross sections are also computed for the Ps(1s)- p entrance channel, and these to our knowledge represent the first det ailed calculation of the Ps(1s)-p scattering. Particular attention is paid to the cross sections for electron transfer since these are relev ant to proposed experiments to form antihydrogen in sufficient quantit ies to perform spectroscopic experiments. Resonances are identified at incident positron energies both below and above the ionization thresh old.