A Canadian-led team of scientists, including two York University students, has offered the world its first glimpse of antihydrogen’s properties, in the first experiment ever performed on the anti-atom.
Researchers at the European Organization for Nuclear Research (CERN), in an international collaboration led by Canadians, used microwave spectroscopy – one of the most sensitive techniques for probing the structure of atoms – to manipulate antihydrogen. Their work was published March 7 in the prestigious journal, Nature.
Hydrogen is considered the fundamental building block of physics; by comparing it with its antimatter counterpart, scientists hope to answer a crucial question: if antimatter and matter were created in equal amounts during the Big Bang, where did all the antimatter go?
York University physics graduate students Chanpreet Amole and Andrea Capra worked on the experiment and are co-authors on the Nature paper, along with their supervisor, Professor Scott Menary. The collaboration, dubbed ALPHA (Antihydrogen Laser Physics Apparatus experiment), includes scientists from Canada, Brazil, Denmark, Israel, Sweden, the UK and the US. Five Canadian institutions are represented: University of Calgary, University of British Columbia, Simon Fraser University, York University and TRIUMF, Canada’s national particle and nuclear physics lab.
Electrodes for the ALPHA Penning trap are inserted into the vacuum chamber and cryostat assembly. Positrons and antiprotons combine in the trap to form antihydrogen. Photograph: Niels Madsen ALPHA/Swansea
Amole and Capra logged 50-hour weeks at CERN in Geneva, preparing the antihydrogen sample and assisting with measurements.
“Every day was a learning experience,” says Amole. “At CERN, you get to work with some of the top minds in the world. Many times, [one of the scientists] would casually walk in and strike up a conversation on some very complex, yet interesting physics phenomenon that would just blow your mind.”
The experiment involved confining anti-atoms in a magnetic trap and irradiating them with microwaves. Precise tuning of the microwave frequency and magnetic field enabled researchers to hit an internal resonance that made atoms literally jump out of the trap and reveal information about their properties.
Researchers at SFU designed the apparatus for this latest experiment, working closely with PhD candidates Mohammad Ashkezari of SFU and Tim Friesen from the University of Calgary. Meanwhile, researchers from the Vancouver-based TRIUMF laboratory and York University teased faint signals from a sophisticated detector system, pinpointing matter-antimatter annihilation events.
Menary, professor in York’s Department of Physics & Astronomy, Faculty of Science & Engineering, says the current experiment represents the collaboration’s biggest milestone to date.
“It was a scientific tour de force just to trap the antihydrogen atoms. Now we’re actually doing physics with them. This, in my mind, is an even bigger achievement,” he says. Click to view a video of Amole, Capra and Menary explaining the experiment.
ALPHA-Canada researchers played a key role in two other recent antimatter milestones: in November 2010, ALPHA scientists successfully trapped antihydrogen atoms for the first time, and in June 2011, they demonstrated they could hold on to them for 1,000 seconds.
“For decades, scientists have wanted to study the intrinsic properties of antimatter atoms in the hope of finding clues that might help answer fundamental questions about our universe,” says lead author Mike Hayden, physicist with SFU. “In the middle of the last century, physicists were developing and using microwave techniques to study ordinary atoms like hydrogen. Now, 60 or 70 years down the road, we have just witnessed the first-ever microwave interactions with an anti-atom.”