Formation of antihydrogen in the ground state and n=2 level.

Abstract

The cross sections of antihydrogen formation in the ground state and {ital n}=2 level by the impact of antiprotons on the ground state of positronium have been calculated under the framework of the eikonal approximation for incident energy of 30--1000 keV. The excited-state capture cross sections are quite appreciable and are even larger than the ground-state cross sections for impact energies {le}75 keV. The total eikonal cross sections ({sigma}={sigma}{sub 1{ital s}}+{sigma}{sub 2{ital s}}+{sigma}{sub 2{ital p}}) are always higher than the corresponding first-order Born approximation cross section throughout the present energy span.