Arthur Bruce McDonald, P.Eng, (born August 29, 1943) is a Canadian CC OOnt ONS FRS FRSC astrophysicist. McDonald is the director of the Sudbury Neutrino Observatory Collaboration and held the Gordon and Patricia Gray Chair in Particle Astrophysics at Queen's University in Kingston, Ontario from 2006 to 2013. He was awarded the 2015 Nobel Prize in Physics jointly with Japanese physicist Takaaki Kajita.
McDonald was born on August 29, 1943,
in  Sydney, Nova Scotia. He graduated with a  B.Sc. in physics in 1964 and M.Sc. in physics in 1965 from Dalhousie University in Nova Scotia. He then obtained his  Ph.D. in physics in 1969 from the California Institute of Technology. McDonald cited a high school math teacher and his first-year physics professor at Dalhousie as his inspirations for going into the field of physics. 
McDonald worked as a Research Officer at the
Chalk River Nuclear Laboratories northwest of Ottawa from 1969 to 1982. He became professor of physics at Princeton University from 1982 to 1989, leaving Princeton to join Queen's University where he became Professor from 1989 to 2013.
McDonald was a visiting scientist at the
European Organization for Nuclear Research (CERN) in Geneva in 2004.
In 2013 McDonald became
Professor Emeritus of Queen's University in Kingston, Canada. He continues to be active in basic research in Neutrinos and Dark Matter at the SNOLAB underground Laboratory and as member of the Board of the Perimeter Institute for Theoretical Physics.  
McDonald presenting himself and his research
Physicists have been investigating whether or not
neutrinos have mass. Since the late 1960s, experiments have hinted that neutrinos may have mass. Theoretical models of the Sun predict that neutrinos should be made in large numbers. Neutrino detectors on the Earth have repeatedly seen fewer than the expected number of neutrinos. Because neutrinos come in three varieties (electron, muon, and tau neutrinos), and because solar neutrino detectors have been primarily sensitive only to electron neutrinos, the preferred explanation over the years is that those "missing" neutrinos had changed, or oscillated, into a variety for which the detectors had little or no sensitivity. If a neutrino oscillates, according to the laws of quantum mechanics, then it must have a mass.
In 1984, McDonald's collaborator
Herb Chen at the University of California at Irvine suggested the advantages of using heavy water as a detector for solar neutrinos. Unlike previous detectors, using heavy water would make the detector sensitive to two reactions, one reaction sensitive to all neutrino flavours, the other sensitive to only the electron neutrino. Thus, such a detector could measure neutrino oscillations directly. Chen, McDonald, and collaborators formed the  Sudbury Neutrino Observatory (SNO) to exploit this idea in 1984.  SNO was to be a detector facility using 1000 tonnes of heavy water located 6,800 feet (2,100 m) underground in a mine outside Sudbury, Ontario. Chen died of leukemia in November 1987, however.
In August 2001, the
Sudbury Neutrino Observatory, now led by McDonald, reported observations that directly suggested electron neutrinos from the Sun were oscillating into muon and tau neutrinos. McDonald is a co-recipient of the 2007 Benjamin Franklin Medal in Physics, the 2015 Nobel Prize in Physics, and the 2015 Fundamental Physics Prize for the discovery of neutrino oscillations and demonstrating that neutrinos have mass. 
Honours and awards
1964, Governor General's Medal, Dalhousie
1983, Fellow of the
American Physical Society 1997, awarded an honorary doctorate from
Dalhousie 1999, awarded an honorary doctorate from
University College of Cape Breton 2001, awarded an honorary doctorate from
Royal Military College 2003, awarded the T.W. Bonner Prize in Nuclear Physics from the
American Physical Society 2003, awarded the
Canadian Association of Physicists Medal for Lifetime Achievement in Physics 2003, awarded the
Natural Sciences and Engineering Research Council of Canada Award of Excellence 2003, awarded the
Gerhard Herzberg Canada Gold Medal for Science and Engineering 2004, awarded the Sigma Xi Fund of Canada Award for Scientific Achievement
2005, awarded the
Bruno Pontecorvo Prize in Particle Physics, JINR, Dubna 2006, awarded an honorary doctorate from the
University of Chicago 2006, received the NSERC John C. Polanyi Award to the SNO team
2006, made an Officer of the
Order of Canada  2007, awarded the
Benjamin Franklin Medal in Physics with Yoji Totsuka  2009, elected a
Fellow of the Royal Society (FRS) of the UK and Commonwealth  2009, awarded an honorary doctorate from
St Francis Xavier University 2009, became a Member of
Canadian Science and Engineering Hall of Fame 2010, awarded the Canada Council Killam Prize in Natural Sciences for lifetime achievement in the field
2011, awarded an honorary doctorate from the
University of Alberta 2011, awarded the
Royal Society of Canada's Henry Marshall Tory Medal in recognition for having "brought great honour and intellectual wealth to Canada".  2012, awarded an honorary doctorate from the
University of Waterloo 2012, became member of the
Order of Ontario 2013, awarded the European Physics Society HEP Division Giuseppe and Vanna Cocconi Prize
2015, awarded the Nobel Prize in Physics jointly with
Takaaki Kajita for the discovery of neutrino oscillations, which shows that neutrinos have mass.  2015, promoted to
Companion of the Order of Canada  2016, asteroid
229781 Arthurmcdonald, discovered by Vincenzo Casulli at Vallemare di Borbona in 2008, was named in his honor. The official  naming citation was published by the Minor Planet Center on 20 June 2016 ( ). M.P.C. 100610  2016, awarded an honorary doctorate from
Mount Allison University 2016, awarded an honorary doctorate from the
University of British Columbia 2016, awarded the
Breakthrough Prize in Fundamental Physics (with the SNO Collaboration) 2016, foreign associate of the
National Academy of Sciences  2016, made a member of the
Order of Nova Scotia  2017, awarded an honorary doctorate from
McGill University 2017, awarded an honorary doctorate from
Queen's University 2017, awarded an honorary doctorate from the
University of Toronto  2017, awarded the W.B. Lewis Medal of the Canadian Nuclear Society
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