Arthur B. McDonald, a member of the Perimeter Institute Board of Directors and Professor Emeritus at Queen’s University, has been awarded the 2015 Nobel Prize in Physics, “for the discovery of neutrino oscillations, which shows that neutrinos have mass.”

“On behalf of the entire Perimeter Institute Board, I would like to congratulate Dr. Art McDonald on winning the Nobel Prize in Physics and for his tremendous contributions to science and to Canada,” said Mike Lazaridis, Perimeter Founder and Board Chair. “What a great day for Art and his colleagues, his family, SNOLAB, Queen’s, Canada, physics, and PI. Congratulations Art!”

McDonald and co-winner Takaaki Kajita of the University of Tokyo were recognized as the leaders of two large research collaborations that demonstrated that elementary subatomic particles, called neutrinos, have mass and change identities. This work was crucial to our understanding of how the sun shines, and to modern particle physics.

“This is a tremendous honour for me and my Canadian and international collaborators on the SNO experiment,” said McDonald. “We are very pleased to have been able to add to our scientific knowledge in a very fundamental way.”

For more than 20 years, McDonald served as the Director of the Sudbury Neutrino Observatory, the first major experiment in what has become SNOLAB, an international underground laboratory near Sudbury. There, using 1,000 tonnes of heavy water to make measurements of neutrinos from the sun, they discovered that neutrinos change from one type to another while travelling to the Earth. Their experiments also confirmed that neutrinos have a tiny, but non-zero mass.

“We could be definitive about that because, with the heavy water, we could measure the type produced in the core of the sun and also the sum of all types of neutrinos. In comparing those two, we found that only about a third of the neutrinos reaching us were actually the electron neutrinos produced in the core,” McDonald explained during an interview at Perimeter Institute this past June.

“This meant that, first of all, we had a clear indication that neutrinos change their flavour and therefore have a finite mass,” he said. “We were also able to determine that the model of how the sun burns, and in particular the nuclear reaction that we were measuring, was being calculated very accurately. Those measurements were quite significant, it was felt, in the world of physics and astrophysics.”

Perimeter Director Neil Turok said: “Perimeter Institute is a happy place today! We are so proud of Art McDonald, who has served on our Board of Directors since 2011. His trailblazing discoveries and contributions to building physics in Canada are an example to us all. His recognition as Nobel laureate serves as a powerful reminder of how breakthroughs can be accomplished through foresight, focus, and an insatiable curiosity about our universe.”

The Nobel Prize in Physics is given annually by the Royal Swedish Academy of Sciences, recognizing outstanding contributions in the field of physics. Since the first prize was awarded in 1901, there have been 200 Nobel laureates in physics, including Albert Einstein, Niels Bohr, Erwin Schrödinger, and Marie Curie. McDonald is the fourth Canadian to win the award.

UPDATE, Nov. 9, 2015: Further congratulations to McDonald and his collaborators for being named among the winners of the 2016 Breakthrough Prize in Fundamental Physics. Five research teams (three in Japan, one in China, and McDonald’s group) shared the $3 million prize in recognition of groundbreaking experiments in neutrino oscillation. 

MEDIA COVERAGE

• Takaaki Kajita and Arthur McDonald Share Nobel in Physics for Work on Neutrinos (The New York Times)
• Canadian shares Nobel Prize in Physics for work on neutrinos (The Globe and Mail)
• 2015 Nobel Prize in Physics: Canadian Arthur B. McDonald shares win with Japan's Takaaki Kajita (CBC)
• Art McDonald and Takaaki Kajita win 2015 Nobel Prize for Physics (Physics World)