Production of antihydrogen in relativistic collisions

The production of antihydrogen atoms H̄0 ≡ p̄e+ has been observed by the PS210 collaboration at LEAR. The method assumes an e+e- -pair creation via the two-photon mechanism in the antiproton-nucleus interaction. Neutral H̄0 atoms are identified by a unique sequence of characteristics. The typical signature of eleven produced antihydrogen atoms is reported including possibly 2±1 background signals. The observed yield agrees with theoretical predictions.