Patent Number: 061635871
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of atomic particle physics. More specifically, the present invention relates to a process for the production of antihydrogen. 2. Description of the Prior Art Antihydrogen is the simplest of the antimatter elements. It comprises a nucleus of a single antiproton enveloped by a single orbiting positron. In the absence of reaction with normal matter, antihydrogen is a stable species having an indefinite half-life. Antihydrogen is a potent energy storage medium and is an important reactant in matter-antimatter anihilation reactions. There have been a number of schemes proposed for producing antihydrogen. Unfortunately, many of the schemes result in low yields of high-energy antihydrogen which is not suitable for study. One proposed process for producing antihydrogen in detectable quantities at low energies is the subject of U.S. patent Ser. No. 4,867,939 to Deutch which issued on Sep. 19, 1989. Deutch teaches a process for producing antihydrogen from antiproton-positronium collision via Auger capture. Specifically, the process comprises the interaction of antiprotons having an average energy of less than about 50 KeV and positronium having an average energy on the order of thermal energies. The positronium utilized in the process is ground-state positronium produced by bombarding an aluminum-based positronium converter with a high-energy positron beam. It is this ground-state positronium which undergoes charge-exchange with antiprotons to produce antihydrogen. Although the Deutch process is superior to earlier processes, there is still a requirement for an improved process which can be used to produce higher yield of antihydrogen in a stable state suitable for study. It is an object of the present invention to provide such a process. SUMMARY OF THE INVENTION Accordingly, in one aspect the present invention provides a process for the production of antihydrogen, comprising the steps of: (i) exciting atoms to a Rydberg state; PA1 (ii) charge-exchanging the excited atoms with positrons to produce Rydberg-state positronium; and PA1 (iii) charge-exchanging the Rydberg-state positronium with antiprotons to produce Rydberg-state antihydrogen. Preferrably, the Rydberg-state antihydrogen is permitted to decay to ground-state antihydrogen which can be trapped in a magnetic trap. Recent successes in trapping large numbers of cold antiprotons (10.sup.5 at 4.2K) and even larger numbers of cold positrons (10.sup.6, also at 4.2K), provide the building blocks for the production of cold antihydrogen. Several methods for production of cold antihydrogen from these building blocks have been proposed, but none has a very high efficiency. Cold antihydrogen production would allow for trapping antihydrogen in a magnetic trap, similar to that used to trap neutral hydrogen atoms or molecules. Spectroscopy on such trapped antihydrogen could provide a strong test of CPT, as well as allowing for many precision tests of the physics of antimatter. Accordingly, in a preferred embodiment, the present invention provides a process using two stages of Rydberg-state charge-exchange to produce cold antihydrogen atoms from the cold trapped components.