The CERN-based ALPHA experiment, an international collaboration that aims to trap stable atoms of antihydrogen, has successfully measured and interacted with antimatter for the first time.

Antihydrogen isn't found in nature, so it had to be lab-created using antiprotons (made in an Antiproton Decelerator) and positrons from a radioactive source.

After mixing the two inside a magnetic "trap" to create antihydrogen, scientists used microwave radiation to release the antiprotons, and measured their energy as they collided with matter and were annihilated.

The measurements, published yesterday in Nature, reveal that antihydrogen is very similar to its matter counterpart, hydrogen.

"There's no wildly different result. It looks like an ordinary hydrogen atom," said Mike Hayden of Canada's Simon Fraser University, one of the ALPHA researchers.

The goal of the experiment is to find differences between matter and antimatter that would explain why the universe seems to have a preference for one over the other, but this first measurement was too rough to detect anything to distinguish the two.

"If there's a difference," Hayden added, "everyone's betting it's going to be subtle."

Having proven that they can create and measure antihydrogen, the ALPHA researchers are now improving their equipment to take more precise measurements.

[cbc]