PRODUCTION OF RELATIVISTIC ANTIHYDROGEN ATOMS BY PAIR PRODUCTION WITHPOSITRON CAPTURE

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