Physicists win for discovery showing neutrinos have mass

CBC News Posted: Oct 06, 2015 5:56 AM ET Last Updated: Oct 06, 2015 7:27 AM ET

Arthur McDonald, a professor emeritus at Queen’s University in Kingston, Ont., is the co-winner of the 2015 Nobel Prize in physics.

McDonald will share the prize with Takaaki Kajita of the University of Tokyo.

The winners were announced by a committee at the Royal Swedish Academy of Sciences in Stockholm on Tuesday.

The academy said the two men won the prize for their contributions to experiments demonstrating that neutrinos change identities.

The metamorphosis requires that neutrinos have mass, the academy said, adding that the discovery has changed our understanding of the innermost workings of matter.

Working at the Super-Kamiokande detector in Japan, Kajita, in 1998, showed that neutrinos captured at the detector underwent a metamorphosis in the atmosphere.

Meanwhile, researchers at the Sudbury Neutrino Observatory, as also known as SNOLAB, where looking at neutrinos that come from the sun. McDonald, who has been director of the observatory since 1989, discovered in 2001 that those neutrinos from the sun also changed their identities.

‘Eureka moment’

​”Yes, there certainly was a Eureka moment in this experiment when we were able to see that neutrinos appeared to change from one type to the other in travelling from the Sun to the Earth,” McDonald told a news conference in Stockholm by telephone.

If you don’t know whether neutrinos have mass, it is difficult to understand how to incorporate them into basic theories of fundamental physics, so finding that they have mass helps in that regard, McDonald said.

He also said scientists still want to know what the actual mass of the neutrino is, and whether there are other types beyond the three currently known.

McDonald and Kajita will split the 800,000 Swedish kronor (almost $1.3 million Cdn) prize.

Born in Sydney, N.S. in 1943, McDonald earned Bachelor’s and Master’s degrees from Dalhousie University. He got his Ph.D. in physics from California Institute of Technology in 1969.

He worked for Atomic Energy of Canada from the late 1960s until 1982, when he moved to Princeton University for seven years.

He has been at Queen’s since 1989 and has been a professor emeritus since 2013.

McDonald was invested as an Officer of the Order of Canada in 2008.

Second Canadian winner

The late Willard S. Boyle of Nova Scotia was the only previous Canadian winner in physics, one of four to be honoured in 2009.

On Monday the 2015 Nobel Prize in medicine went to scientists from Japan, the U.S. and China who discovered drugs that are now used to fight malaria and other tropical diseases.

The prize announcements continue with chemistry on Wednesday, literature on Thursday, the Nobel Peace Prize on Friday and the economics award next Monday.