CERN ups the anti

January 12, 1996

The world of Star Trek, with its antimatter-driven starship, has come one step nearer. For the first time physicists at CERN, the Geneva-based particle-smashing laboratory, have produced antimatter.

The international team responsible for the breakthrough produced nine atoms of anti-hydrogen, each of which existed for just 40 billionths of a second. During this time the atoms zoomed across ten metres at almost the speed of light before being annihilated by ordinary matter. The characteristics of the signal produced by the annihilation provided the scientists with the proof they needed that antimatter atoms had indeed been created.

The existence of antimatter was first predicted by Nobel prize-winning physicist Paul Dirac in the late 1920s. The first confirmation of the existence of antimatter particles - as opposed to CERN's whole atoms - came with the discovery of the positron, the antiparticle of the electron, in the 1930s. In the early 1950s, the antiparticle of the proton, another basic constituent of ordinary matter, was confirmed.

Sandy Donnachie, head of the faculty of science and engineering at the University of Manchester, said that apart from mass, antiparticles have the opposite basic characteristics to their ordinary counterparts. The electrical charge of the proton, for example, is positive while that of an antiproton is negative. Similarly, an electron carries a negative charge but its antiparticle, the positron, carries a positive one.

Professor Donnachie, a former UK delegate to the CERN council, said that the creation of antimatter depends on years of work on antiparticles, in particular the ability of scientists to slow down the antiparticles sufficiently so that they "stick" together.

"The whole aim of creating these atoms of antimatter in the long term is to see how their behaviour compares with that of their ordinary counterparts, which we already know so much about," he says. The smallest deviations in the behaviour between the two types - for example between hydrogen and anti-hydrogen - could cause major headaches for physicists, forcing a rethink of many accepted ideas on the relationship between matter and antimatter.

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