Thursday, March 8, 2012

First it was caught. Then it was stored. And now it is being made to jump. "It" is the elusive antihydrogen atom.

Researchers at CERN, in an international effort led by a Canadian team, have used microwaves to manipulate antihydrogen atoms. In doing so, they've provided the world with its first glimpse of an "anti-atomic fingerprint." Their work is published today in the prestigious journal Nature, for the third time in a little more than a year.

"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, a physicist with Simon Fraser University (SFU) and a member of the ALPHA collaboration.

"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."

Antimatter is a staple of science fiction, but it also stands out as one of the biggest mysteries of science fact. Fundamental theories predict perfect symmetry between matter and antimatter, but the glaring absence of antimatter in our universe suggests there might be a difference. Enter microwave spectroscopy, one of the most sensitive techniques for probing the structure of atoms.

"This study demonstrates the feasibility of applying microwave spectroscopy to fiendishly difficult-to-handle anti-atoms," says co-author Walter Hardy from the University of British Columbia (UBC). "ALPHA is about to enter an intensive upgrade phase that promises to create an ever-clearer picture of the inner structure of anti-matter atoms."

The present measurement 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, kicking atoms out of the trap, and revealing information about their properties. Hardy and Hayden 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.

"Hydrogen is the most abundant element in the universe, and we understand its structure extremely well," says ALPHA collaboration spokesperson Jeffrey Hangst of Aarhus University in Denmark. "Now we can finally begin to coax the truth out of antihydrogen. Are they different? Today, we can confidently say 'time will tell.'"

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Simon Fraser University: http://www.sfu.ca