Proposal for making a beam of antihydrogen by two charge exchange events

We have performed calculations of two successive charge transfers in a geometry that could generate a beam of antihydrogen atoms (H̄) or reliably produce cold H̄ without having to reach extremely cold plasma temperatures. The basic idea is similar to that proposed by Hessels et al (1998 Phys. Rev. A 57 1668) except that the order of the charge transfers is reversed. A beam of highly-excited (Rydberg) Cs atoms passes through an antiproton (p̄) plasma where a charge transfer can take place; the result is an exotic Rydberg atom (Cs+ ion and a bound p̄) which has approximately the original velocity of the Cs atom since the Cs+ mass is much greater than that of the p̄. This exotic Rydberg atom travels into a positron plasma where a second charge exchange gives antihydrogen (H̄). The velocity distribution of the resulting H̄ is directly related to the original velocity of the Rydberg Cs atom. The binding energy of the H̄ is roughly that of the original Cs Rydberg atom; thus, the starting state of the H̄ can be controlled by choosing the initial state of the Cs atom. Because the p̄Cs+ binding energy can be controlled in the charge transfer, this first step, by itself, could be of interest to the exotic atom community.