Production of relativistic antihydrogen atoms by pair production with positron capture

A beam of relativistic antihydrogen atoms, the bound state (bar pe+), can be created by circulating the beam of an antiproton storage ring through an internal gas target. An antiproton that passes through the Coulomb field of a nucleus of charge Z will create e+e- pairs, and antihydrogen will form when a positron is created in a bound rather than a continuum state about the antiproton. The cross section for this process is calculated to be ∼4Z2 pb for antiproton momenta above 6 GeV/c. The gas target of Fermilab Accumulator experiment E760 has already produced ∼34 unobserved antihydrogen atoms, and a sample of ∼760 is expected in 1995 from the successive experiment E835. No other source of antihydrogen exists. A simple method for detecting relativistic antihydrogen is proposed and a method outlined of measuring the antihydrogen Lamb shift to ∼1%