Canadian researchers detect and test antihydrogen atoms
SASKATOON (CUP) — Science fiction writers have long fantasized about antimatter and the applications it might have, from the matter-antimatter engines that allow Star Trek ships to run faster than the speed of light to opposite, mirror-image copies of each and every person on earth, usually in negative colouring.
Until recent years, antimatter was merely a theoretical convenience and a plot device. Now, however, and thanks in large part to researchers from across Canada, antimatter has not only been proven to exist, but has also been trapped long enough to have tests performed on it.
Rob Thompson is the head of the astrology and physics department at the University of Calgary. He is also one of 16 group leaders in the Antihydrogen Laser Physics Apparatus, a project run out of the European Organization for Nuclear Research reactor, or CERN. He and two graduate students at the U of C travel to Geneva for months at a time to conduct experiments on antimatter at CERN.
“As head of the department [at U of C], I don’t get to go for as long as Richard and Tim,” Thompson said of graduate students Richard Hydomako and Tim Friesen. “They are at CERN for six months in the year doing shift work — they’re on the team running the experiment, they’re analyzing data.”
Of the 45 researchers involved in the project, Thompson estimates that about one third are from Canada. Calgary, York University and the University of British Columbia are all represented in the groundbreaking project. Hydomako was the first student to receive a master’s degree from the project and is now finishing his PhD.
Experimental attempts to create antihydrogen began in 2002 and were first successful in 2004, according to Thompson.
“It would still annihilate almost immediately,” Thompson said. “We couldn’t study it. Now we’ve achieved not only to make antihydrogen, but to store it. Then you can study it.”
The creation of antihydrogen requires an antiproton and an antielectron, or positron, to be combined by force, which can be difficult, especially because the two antiparticles must be forced to join without being manipulated by matter.
English physicist Paul Dirac was the first to theorize the existence of antimatter in a 1928 paper, though Carl Anderson detected it in 1932 when he proved the existence of the positron.
Antimatter is composed of antiparticles in the same way that matter is composed of particles. For every type of particle there is a type of antiparticle that has an opposite electric charge. When antimatter and matter meet, they annihilate and create a burst of energy.
This is one of the largest problems the ALPHA team has to work around.
Because antihydrogen is neutral, like hydrogen, it doesn’t react strongly with magnetic fields, and is difficult to keep in place. It must be kept inside a vacuum so it doesn’t instantly annihilate upon creation, as the antimatter particles created in some reactors do.
“The actual trapping involves a ‘magnetic bottle,’ which is a low magnetic field some particles will be attracted to,” Thompson explained. “It’s basically a magnetic containment field, if you want to use the sci-fi term.”
Antimatter particles are hyperactive, though, and need to be cooled down so that they do not jump out of the magnetic field too quickly. For antihydrogen to slow down enough to be studied, it must be “no warmer than half a degree Kelvin,” — or 272 Celsius.
The holding time for the 38 antihydrogen atoms ALPHA trapped was only about one tenth of one second. Thompson explained that these initial tests were merely for “proof of principle,” to prove that they had successfully created and trapped antihydrogen.
“Even a tenth of a second is long enough for initial experiments,” said Thompson. “Ideally, some day we will be able to hold them for seconds, minutes or even an hour. But we can begin doing studies now.”
When he says now, Thompson really means in six months. The project concluded for the winter on Nov. 21, and it will begin again in 2011. There will be a meeting in early December to discuss what the researchers want to study next year. Thompson mentioned the improvement of their trapping techniques and generation efficiency.
But one of the main goals, he says, will be studying the make-up of antihydrogen for similarities to and differences from hydrogen.
“If you look at hydrogen and antihydrogen, they should basically look the same,” he said. “If they do, that’s an incredible confirmation of the fundamental theories of physics. If they don’t, it raises questions of why that is, and it opens up whole new vistas of exploration in physics.”
