Canada's National Laboratory for Particle and Nuclear Physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules

ALPHA Collaboration captures antimatter

17 November 2010

(Vancouver, BC) – Boldly going where the universe has not gone before, scientists at the CERN laboratory near Geneva, Switzerland have succeeded in capturing anti-matter atoms. In a paper published today in Nature, physicists of the ALPHA Collaboration, including key Canadian contributors, describe how they succeeded in containing for the first time atoms of antihydrogen, the antimatter partner of ordinary hydrogen. This breakthrough will allow future detailed measurements of antihydrogen, giving scientists a powerful new tool to help solve the age-old question: “Why is there something, rather than nothing, in the universe?”

Antimatter, or the lack of it, remains one of the biggest mysteries of science. At the Big Bang, matter and antimatter should have been produced in equal amounts, but since they annihilate upon contact, shortly thereafter nothing should have remained but pure energy (light). However, to date all observations suggest that all the antimatter has vanished. To try to understand what happened to “the lost half of the universe”, scientists are eager to determine whether there is a difference in the properties of matter versus antimatter that might offer an explanation. The approach taken by the ALPHA collaboration will be to compare a well-known system in physics, the hydrogen atom, consisting of one proton and one electron, with its antimatter counterpart, antihydrogen, consisting of an antiproton and an antielectron.

Antihydrogen atoms were first made at CERN eight years ago, but couldn’t be stored, since the anti-atoms touched the ordinary-matter walls of the experiments within millionths of a second after forming and were instantly annihilated. The ALPHA collaboration succeeded by developing a sophisticated “magnetic bottle” using a state-of-the-art superconducting magnet to suspend the antiatoms away from the walls. The experiment showed definitive proof of antihydrogen atom capture for about a tenth of a second. Very few were captured (nowhere near enough to power a starship engine!), but their longevity was more than enough to allow study. This result is the crucial step before commencing detailed studies of antihydrogen. These antihydrogen atoms very well may be the first contained antiatoms in the history of the universe.

A well-known aphorism proclaims that to understand the hydrogen atom is to understand all physics. Makoto Fujiwara, spokesperson for the ALPHA-Canada group, points out, “That is only half right - we still have to understand antihydrogen.” CERN Director General Rolf Heuer said, “These are significant steps in antimatter research and an important part of the very broad research programme at CERN.” CERN is the only laboratory in the world with a dedicated low-energy antiproton facility to enable this type of research.

ALPHA-Canada scientists have been playing leading roles in the antihydrogen detection and data analysis aspects of the experiment, and also the development towards forthcoming antiatomic structure studies. Richard Hydomako, a Ph.D. student of Pro