York researchers contribute to Canadian-led study detailing antimatter forensics

A Canadian-led investigation involving York researchers has opened a new chapter in antimatter research.

In a study published in Nature today (Aug. 3), the ALPHA Collaboration – a group of international physicists including physics Professor Scott Menary and his graduate students Melissa Mathers and James Thompson in the Faculty of Science at York University – reported the first detailed observation of spectral lines from an antimatter atom.

The ALPHA experimental pit

“Spectral lines are like fingerprints,” said lead author Michael Hayden, a Simon Fraser University physics professor. “Every element has its own unique pattern.”

There is one possible exception: matter and antimatter are believed to be mirror images of one another, and so the spectral lines of antimatter atoms should be precisely the same as those of their normal atom counterparts. Until now, however, scientists have only had glimpses of antimatter spectral lines, and comparisons with normal matter spectral lines have been coarse.

Using antihydrogen (the antimatter counterpart of the ordinary hydrogen atom), the ALPHA Collaboration showed that a particular set of spectral lines in antihydrogen match those in hydrogen very well. At the CERN laboratory in Geneva, researchers irradiated antihydrogen atoms with microwaves which revealed their identity by emitting or absorbing energy at very specific frequencies. That pattern, or spectrum, of frequencies corresponds to the fingerprint.

The team plans to zoom in much closer to check if subtle discrepancies exist between the two atoms on a yet finer scale.

Scott Menary

“ALPHA again has done a precision measurement that can be compared to the value one finds for hydrogen,” said Menary, whose contribution to the research was on the mechanics of the analysis and on the annihilation vertex recognition. “We continue to search for differences between the matter and antimatter system. Hopefully one day we’ll see one.”

ALPHA is a collaboration of about 50 physicists from 17 institutions in Canada, Brazil, Denmark, Israel, Japan, Sweden, the U.K. and the U.S. ALPHA-Canada comprises about 40 per cent of the ALPHA Collaboration. The team is studying the fundamental symmetries between matter and antimatter in an effort to understand why there is very little antimatter in the universe now.

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