The mystery of antimatter

As part of an international research team, UCalgary scientists are helping to unravel one of the universe’s big puzzles.

By Mark Lowey and Erin Guiltenane
February 2016

The power plant that propels the starship Enterprise on Star Trek is science fiction. But an international research team including University of Calgary scientists is working on solving the mystery of a real component in the starship’s engine — antimatter.

Rob Thompson, department head and professor in the Department of Physics and Astronomy, and his research group are members of a world-leading collaborative experiment called ALPHA, which is investigating the properties of antimatter.

Unlike the Enterprise, antimatter actually exists, based on the theories and experiments of particle physics. They tell physicists that antimatter particles should behave like an identical, but mirror, version of the matter that makes up our material world — from microbes to humans to galaxies.

If that is the case, the creation or destruction of matter should always pair with the exact equivalent for antimatter — right from the Big Bang that created the universe.

“This seems a bit problematic right now, because as far as we can tell, the universe we exist in is made up of matter,” says Thompson.

“There’s this matter-antimatter imbalance that doesn’t match. So we’re trying to figure out where that lies ... our goal here is testing the foundations of physics."

To unravel antimatter’s mystery, the ALPHA collaboration, based at the CERN laboratory near Geneva, Switzerland, makes, captures and studies antihydrogen atoms — the antimatter counterpart of the simplest atom, hydrogen.

By making precise measurements of antihydrogen and comparing it with hydrogen, ALPHA hopes to discern any detectable differences between matter and antimatter. That could solve the puzzle and open a window to new physics and technologies.

'Magnetic bottle' traps antimatter particles for study

In 2002, scientists successfully made antihydrogen atoms in the laboratory. By 2010, the ALPHA team had built an ALPHA-1 device, a “magnetic bottle” in which they caught 38 antimatter particles using electromagnetic fields and by cooling the fast-moving particles to a half-a-degree above absolute zero, or to -272.7°C.

By 2011, the team was able to confine or store the antimatter particles within the trap for up to 15 minutes — long enough to study them. For its work, the ALPHA-Canada team received the prestigious John C. Polanyi Award from the Natural Sciences and Engineering Research Council (NSERC).

The team then built a second-generation ALPHA-2 magnetic bottle, with a more efficient antiparticle-collection system, designed specifically to measure the properties of antihydrogen atoms.

Thompson notes that the Faculty of Science and the Vancouver-based TRIUMF subatomic physics laboratories played a “significant role” in jointly designing, building and installing ALPHA-2’s cooling device, called the “cryostat.”

Funding for ALPHA-2 came from NSERC, with institutional support from the University of Calgary and TRIUMF.

Team confirms antihydrogren's electric charge is zero

After making, capturing, and storing antihydrogen, the ALPHA team has now taken another important step in characterizing antimatter.

Previous research had shown that the antihydrogen atom, like its hydrogen counterpart, has a neutral electric charge that was at, or close to, zero — something that was expected from physics theory.

But in the first high-precision measurement with ALPHA-2 in an experiment led by the University of Berkeley in California, the ALPHA team made the most precise measurement yet of antihydrogen’s electric charge, confirming that it is zero.

“This narrowed it down and nailed it,” says Thompson. Precisely measuring antihydrogen’s electric charge was crucial, not only to confirm physics theory, but because it opened the door to measuring other properties of antihydrogen with high precision.

The ALPHA team’s new work is published in Nature, a world-leading science journal. It is the team’s sixth publication in Nature and its affiliated specialized journals.

Next steps: Look at optical properties, build a third-gen system

The team’s next step is to look at antihydrogen’s optical properties, such as the colours of light it emits and absorbs.

The step after that is ALPHA-G, a $17-million project, also supported by Alberta, British Columbia and Ontario, to build a third-generation system to do high-precision measurements on the gravitational interaction between matter and antimatter. It starts in 2017 and the University of Calgary took the lead in securing funding from the Canada Foundation for Innovation for this project.

Unravelling the mystery of antimatter will provide insight into how our universe was created and is behaving now, and the research is expected to lead to new technology applications. In fact, antimatter is already being used in medicine, says Thompson.

A PET (Positron Emission Tomography) scan uses the detection of positrons — the antimatter counterpart of the electron — to produce medical images. A collaboration at CERN is looking at the potential of using a beam of antiprotons to destroy cancer tumours. 

“The strides that ALPHA has taken have exceeded certainly what I’d expected us to accomplish on this sort of timeline. We really are the leaders in working with trapped antimatter,” Thompson says.

“If we figure out how to make antimatter more rapidly and effectively, the ability to store it and manipulate it in a controlled manner are going to be key to the use of it," he says. Perhaps in the far future, the uses may include as fuel in a galaxy-hopping starship. 

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