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Radiation from a cloud of antihydrogen atoms
By Dr David Whitehouse
BBC News Online science editor
Physicists have mass produced antimatter, a crucial first step towards precision studies of its properties that may help solve one of the greatest mysteries of the Universe.
Antihydrogen has been made before, but only a handful of atoms at a time.
Now, the Cern particle accelerator in Geneva, Switzerland, has produced more than 50,000.
Antimatter is the mirror image of ordinary matter and both should have been created in equal quantities at the birth of the Universe. That everything around is predominantly ordinary matter is therefore a major puzzle.
Cern is the European Organisation for Nuclear Research.
Pool of positrons
"This is a milestone that has opened up new horizons, to enable scientists to study symmetry in nature and explore the fundamental laws of physics which govern the Universe," said Professor Michael Charlton University of Wales at Swansea.
In the latest experiment, researchers used the Cern accelerator to create antiprotons and trapped them in a vacuum chamber.
A radioactive source, meanwhile, was used to create positrons, which were held in a separate trap. The antiprotons were then fed into the pool of positrons, where the two combined to form antihydrogen.
The antimatter was short-lived being destroyed when it bumped into normal matter. Detectors picked up the unique radiation signatures of antimatter as it was annihilated.
Early stages
For years researchers have wanted to create significant amounts of antimatter to test the so-called Standard Model, which describes fundamental particles and their interactions.
Such a test is important because if antihydrogen does not behave the same way as normal hydrogen "the textbooks would have to be rewritten", says Cern's Jeffrey Hangst.
Antimatter is destroyed whenever it collides with matter, turning both into bursts of radiation. Scientists believe this process was crucial in the earliest stages of the Universe billions of years ago.
Today, the Universe consists of predominantly one form of matter and scientists are not sure why this is so.
Praise and doubt
David Christian of Fermilab in the US praised Cern's achievement.
"They've got a lot more big steps they need to make, but this one is a big step," he said.
However, not everyone is convinced by the latest research which has been published in the journal Nature.
Even within Cern, there are questions being raised. A spokesman for a rival research group said he doubted that antihydrogen had been produced in the latest experiment.
Harvard physicist Gerald Gabrielse said: "Our long experience with these very difficult experiments warns that antihydrogen may not have really been produced."
He added that upcoming publications by his group "will show how it is possible to be fooled".
Any thoughts of using antimatter to power a starship or create a weapon is still in the realm of science fiction.
Making antiprotons requires 10 billion times more energy than it produces. For example, the antimatter produced each year at Cern could power a 100 watt light bulb for just 15 minutes.
http://news.bbc.co.uk/2/hi/science/nature/2266503.stm
