Scientists to capture atoms of antimatter

Rolf Landua, German physicist and spokesman of the "Athena" project, stands in the antiproton decelerator room of the European Laboratories for Particle Physics on Wednesday,

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GENEVA (AP) -- European scientists searching for answers to some of science's most basic questions announced plans Thursday to build atoms of antimatter and then "cage" them for use in experiments.

The researchers at the European Laboratory for Particle Physics, or CERN, said they plan to make atoms of antihydrogen. It would be the first time that antiatoms have been slowed down enough to be caught and studied, intensifying global competition between scientists trying to decode the mystery of antimatter.

Physicists believe that antimatter is the mirror image of conventional matter in the universe. For every subatomic particle in the universe, there appears to be another identical in appearance and structure, but with its electric or magnetic properties reversed.

Scientists have been puzzling for years over the disappearance of antimatter. The Big Bang should have created the same amount of matter and antimatter, and in principle the two should have wiped each other out.

But somehow there was enough matter left over to create the universe, and antimatter only exists now in cosmic rays and particle accelerators.

CERN, famed for its 16.75-mile (27-km) particle accelerator, this time is using a small decelerator -- 616 feet (185 meters) around -- to create its "antimatter factory."

The CERN scientists plan to test the antihydrogen atoms to see if they behave in the same way as ordinary hydrogen.

"We are looking at how the universe would look if it was made out of antimatter. Would there be the slightest difference between our universe and the universe of antiatoms?" said Rolf Landua, spokesman for one of three projects at CERN looking at the issue.

If antimatter differs from matter, even by one part in a hundred billion, that could explain why the world is made up of matter and why antimatter has disappeared, he added.

The decelerator takes antiprotons -- the opposite of protons -- which have been created in the accelerator, groups them together and then slows them down to a tenth the speed of light.

These can then be captured, either in electromagnetic fields or by inserting them into ordinary atoms, which is possible because antiprotons destroy normal protons but not other matter.

Then, positrons -- antielectrons emitted by a radioactive source -- are added to the antiprotons. Just as one proton and one electron creates hydrogen, so one antiproton and one positron creates antihydrogen. Manufacturing antiatoms is the next step to understanding the fundamental properties of an antimatter world.

"To really understand whether this mirror world is out there, you have to test its ingredients and see if they behave the way we would expect them to behave," said Kurt Riesselmann, a physicist and spokesman for the Fermi National Accelerator Laboratory outside Chicago.

When they collide, matter and antimatter release tremendous energy. Some scientists dream of harnessing this energy to send spacecraft to other solar systems orbiting distant stars.

However, Riesselmann said antimatter propulsion and other practical applications of the mirror world is a long way off. The CERN experiments would trap small amounts of antimatter in magnetic fields for experiments, but that wouldn't be practical on a larger scale.

"How would you store it?" he said. "You couldn't put it in a vessel or a container made of matter."

Copyright 2000 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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