Thursday, March 27, 2008

Update on antimatter research:
[Harvard professor Gerald Gabrielse] explains the process of creating antihydrogen in the ATRAP technique: First, antiprotons are slowed by lowering their temperatures to close to four degrees above absolute zero. Positrons are also cooled down. "Next, we get the positrons and the antiprotons to interact – we get them to collide," Gabrielse says. "If we do it at a low enough energy, there is a probability that they will get attached and form an antihydrogen atom."

The problem is that, without charge, the antihydrogen doesn't trap very well. The ATRAP Collaboration overcame this problem by "creating a trap within a trap," Gabrielse explains. A Penning trap, which is designed for the antiprotons and positrons, is located inside an Ioffe trap with four current-carrying poles. This creates a region where the magnetic field is at a minimum. "Antiydrogen atoms that are cold enough and in the right quantum state will preferentially stay in the place where the magnetic field is lowest," Gabrielse explains. The Ioffe trap is designed to keep the antihydrogen, once it's formed, in place.

...Once this is done, it should be possible to study the properties of antihydrogen and compare them to the properties of hydrogen. "If we discover they have different properties," Gabrielse says, "it will have huge implications at a fundamental level. If we find that they are the same, that reality does conform to theory, it's still a winning situation."