Physicists build bigger 'bottles' of antimatter to unlock nature's secrets

Once regarded as the stuff of science fiction, antimatter-the mirror image of the ordinary matter in our observable universe-is now the focus of laboratory studies around the world.

While physicists routinely produce antimatter with radioisotopes and particle colliders, cooling these antiparticles and containing them for any length of time is another story. Once antimatter comes into contact with ordinary matter it ''annihilates''-or disappears in a flash of gamma radiation.

UCSD physicists James Danielson, Clifford Surko and Craig Schallhorn (left to right) inspect the apparatus they are using to develop the world's largest trap for low-energy positrons, which is expected to hold a trillion or more antiparticles. Photo Credit: Kim McDonald, UCSD

Clifford Surko, a professor of physics at UC San Diego who is constructing what he hopes will be the world's largest antimatter container, said physicists have recently developed new methods to make special states of antimatter in which they can create large clouds of antiparticles, compress them and make specially tailored beams for a variety of uses.

Surko says since ''positrons'' - the anti-electrons predicted by English physicist Paul Dirac some 80 years ago - disappear in a burst of gamma rays whenever they come in contact with ordinary matter, accumulating and storing these antimatter particles is no small feat. But over the past few years, he added, researchers have developed new techniques to store billions of positrons for hours or more and cool them to low temperatures in order to slow their movements so they can be studied.

Surko says physicists are now able to slow positrons from radioactive sources to low energy and accumulate and store them for days in specially designed ''bottles'' that have magnetic and electric fields as walls rather than matter. They have also developed methods to cool them to temperatures as low as that of liquid helium and to compress them to high densities.

''One can then carefully push them out of the bottle in a thin stream, a beam, much like squeezing a tube of toothpaste,'' said Surko, adding that there are a variety of uses for such positrons.