Cern scientists trap antimatter

Researchers have produced and captured anti-hydrogen atoms using strong magnetic fields in the Alpha experiment at Cern

Physicists at Cern have taken a major step forward in antimatter research, according to the European science organisation.

For the first time, scientists have managed to produce antimatter atoms and trap them using magnetic fields, the world's premier particle physics laboratory announced in a statement on Wednesday.

Learning how to trap the antimatter atoms, which were anti-hydrogen, will allow scientists from Cern's Alpha experiment to study the antiparticles, Cern told ZDNet UK on Wednesday. "This is a momentous step in the study of antimatter," Alpha experiment spokesman Jeffrey Hangst said.

While thousands of anti-hydrogen atoms were created, 38 were captured. The anti-hydrogen atoms were trapped for 0.17 seconds — long enough to study the antimatter, Hangst said — but can theoretically be held for much longer.

Normally, when antimatter particles are produced, they are annihilated when they come into contact with matter, Hangst explained. Anti-hydrogen is produced in a vacuum, but still has a short life expectancy.

The study of antimatter is further hampered as magnetic fields, which can be used to prevent matter and antimatter colliding, have little effect on neutrally charged antimatter. Anti-hydrogen atoms consist of an antiproton, which has a negative charge, and a positron, which is positively charged, Hangst said. When these particles combine, they have a neutral charge.

Nevertheless, there is still a weak interaction between anti-hydrogen and a strong magnetic field, if the antimatter is cold enough. Hangst said that anti-hydrogen needs to be 0.5 degrees above absolute zero to be trapped.

The next stage of the experiment is to work out for how long antimatter atoms can be captured, and how many can be produced. After that, the Alpha experiment will be taken apart and rebuilt so that scientists can shine lasers into the antimatter to see if it absorbs light. The Standard Model of physics, a group of hypotheses about how physics works, predicts that matter and antimatter should behave in the same way. The anti-hydrogen should therefore absorb the same wavelengths of light as hydrogen atoms, Hangst said.