Formation of antihydrogen from antiproton collisions with positronium

Abstract

The cross section for antihydrogen formation in the n=1, 2 and 3 levels from antiproton-positronium collisions is computed in the unitarized Born approximation (UBA). Six physical states of antihydrogen (1s, 2s, 2p, 3s, 3p, 3d) and three physical states (1s, 2s, 2p) of positronium are included in the UBA basis. The cross section for antihydrogen formation from excited positronium targets is found to be much larger than that from a ground state positronium target at sufficiently low incident energies. This has implications for increasing the production of antihydrogen for planned high resolution spectroscopic experiments.