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Members of the ALPHA collaboration during shift work in the control room

ALPHA – Antihydrogen Laser PHysics Apparatus

Neutral trap to capture and analyse antihydrogen

The ALPHA experiment is a successor of an earlier antimatter experiment, ATHENA. Set up in late 2005 with similar overall research goals as its predecessor, ALPHA will make, capture and study atoms of antihydrogen and compare these with hydrogen atoms. This time, the physicists are using equipment of a different design which has evolved from the previous experiment.

Creating antihydrogen depends on bringing together the two component antiparticles, antiprotons and positrons, in a device for trapping particles with an electric charge. However, since antihydrogen atoms have no electric charge, they are not confined: once made the antiatoms drifted naturally to the walls of the trap. Because these walls were made of ordinary matter, the contact caused the antiatoms to annihilate a few microseconds after they were created.

ALPHA is picking up from where ATHENA left off. As well as the standard trap, ALPHA also makes use of a different trapping method to hold the antihydrogen atoms, and will keep them for a longer period before they annihilate with ordinary atoms. This should give the physicists time to take measurements and to find more answers to the antimatter mystery.

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