Observation of antihydrogen production in flight at CERN

The observation of the production of antihydrogen atoms overlineH ⁰equivbarpe⁺, the simplest atomic bound state of antimatter, is presented. A method has been used by the PS210 collaboration at LEAR which assumes that the production of overlineH⁰ is predominantly mediated by the e⁺e^--pair creation via the two-photon mechanism in the antiproton--nucleus interaction. Neutral overlineH⁰ atoms are indentified by a unique sequence of characteristics. In principle overlineH⁰ is well suited for investigations of fundamental CPT violation studies under different forces, however, in our investigations we concentrate on the production of this antimatter object, since so far it had not been observed. The production of eleven antihydrogen atoms is reported including possibly 2± 1 background signals, the observed yield agrees with theoretical predictions. This revised version was published online in August 2006 with corrections to the Cover Date.