The Canadian Press
STOCKHOLM—A Canadian is co-winner of the 2015 Nobel Prize in Physics for his work on tiny particles called neutrinos.
Arthur McDonald, a professor emeritus at Queen’s University in Kingston, Ont. and the director of the Sudbury Neutrino Observatory in Northern Ontario, and Japanese scientist Takaaki Kajita were cited for the discovery of neutrino oscillations and their contributions to experiments showing that neutrinos change identities.
“The discovery has changed our understanding of the innermost workings of matter and can prove crucial to our view of the universe,” the Royal Swedish Academy of Sciences said in announcing the award early today.
McDonald, who spoke to reporters by phone from his home in Kingston immediately after the prize was announced, said being named by the committee is a “very daunting experience, needless to say.”
“Fortunately, I have many colleagues, as well, who share this prize with me,” he noted.
McDonald said they have put in a “tremendous amount of work,” and that he benefited from having a “very friendly collaboration among scientists from Canada, the United States, Britain, and Portugal.”
He noted that group will help him “enjoy the moment” when he has a chance to speak with them.
McDonald said there was a “eureka moment” when they were able to see that neutrinos could change from one type to another in travelling from the sun to the Earth.
“Neutrinos are among the fundamental particles [which] we do not know how to subdivide any further,” he noted.
“Therefore, their position within the models of physics at the most fundamental level is very important.
“When you do not know whether they have mass, it’s otherwise difficult to understand how to incorporate them into those theories that give us a more complete understanding of the world of physics at the most fundamental level,” McDonald added.
“Discovering this property helps us tremendously in this regard.”
McDonald, 72, is a native of Sydney, N.S. who studied at Dalhousie University in Halifax in the mid-1960s and later at the California Institute of Technology.
He was made an Officer of the Order of Canada in 2006.
McDonald and Kajita, who is the director of the Institute for Cosmic Ray Research and professor at the University of Tokyo, will split the prize money—the equivalent of about $1.3 million Cdn. (eight million Swedish kronor).
Kajita, meanwhile, seemed flummoxed at a news conference organized by his university.
“My mind has gone completely blank,” he said after taking the stage.
“I don’t know what to say.”
After getting his composure back, he stressed that many people had contributed to his work—and that there was much work still to do.
“The universe where we live in is still full of unknowns,” Kajita said.
“I would like to see young people try to join our pursuit of mystery solving.”
Neutrinos are minuscule particles created in nuclear reactions, such as in the sun and other stars.
For decades the neutrino remained a hypothetical particle until American researchers proved that it was real in 1956.
There are three kinds (or flavours) of neutrinos and the laureates showed they oscillate from one flavour to another, dispelling the long-held notion that they were massless.
Kajita showed in 1998 that neutrinos captured at the Super-Kamiokande detector in Japan underwent a metamorphosis in the atmosphere, the academy said.
Three years later, in Canada, while working at the Sudbury Neutrino Observatory, McDonald found neutrinos coming from the sun also switched identities.
But McDonald said scientists still would like to know the actual masses of the various forms of neutrino.
And experiments are looking at whether there are other types of neutrinos beyond the three clearly observed.