Wednesday, May 4, 2011

Fleeting antimatter trapped for a quarter of an hour

What can you do with a quarter of an hour? Write a few emails, cook rice – or store antimatter.

The team working on the Antihydrogen Laser Physics Apparatus (ALPHA) at the CERN particle physics laboratory near Geneva, Switzerland, have stored atoms of antihydrogen for 1000 seconds – roughly 10,000 times longer than before. This should help reveal if antimatter and matter are true mirror images.

Antihydrogen atoms are annihilated by hydrogen. The ALPHA team want to keep antimatter intact long enough to study it, so last year they worked out how to hold a cloud of antihydrogen in a magnetic trap. Not for long, though: collisions with trace gases would have either annihilated the anti-atoms or given them the energy to escape, so the team opened the trap after 170 milliseconds and observed the resulting annihilations, verifying that antimatter had been made.

Now they have repeated the experiment, this time waiting much longer before opening the trap. They also cooled the antiprotons used to create the antihydrogen much further, which lowered the energy of the antimatter, allowed more to be squeezed into the trap and raised the chance that some would last longer (arxiv.org/abs/1104.4982).

Antimatter's life extension will permit experiments, such as checking whether antihydrogen occupies the same energy levels as hydrogen, "perhaps within the next few years", says Daniel Kaplan of the Illinois Institute of Technology in Chicago, who is not on the ALPHA team.

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