FORMATION OF ANTIHYDROGEN FROM ANTIPROTON COLLISIONS WITH POSITRONIUM

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