Arthur B. McDonald

From Wikipedia, the free encyclopedia

Arthur B. McDonald is a Canadian physicist and the Director of Sudbury Neutrino Observatory Institute. He also holds Gordon and Patricia Gray Chair in Particle Astrophysics at Queen’s University in Kingston, Ontario.

1 Early life
2 Academic career
3 Research
4 References

[edit] Early life

McDonald graduated with a B.Sc. in Physics in 1964 and M.Sc. in Physics in 1965 from Dalhousie University in Nova Scotia. He completed his Ph.D. in Physics from the California Institute of Technology.

[edit] Academic career

McDonald worked as a research officer at the Chalk River Nuclear Laboratories northwest of Ottawa from 1970 to 1982. He became professor of physics at Princeton University from 1982 to 1989, leaving Princeton to join Queen’s University. He is currently holds a University Research Chair at Queen’s University.

[edit] Research

Physicists have been investigating whether neutrinos have mass or not. Since the late 1960s, experiments have hinted neutrino may have mass. Theoretical models of the Sun predict that neutrinos should be made in staggering numbers. Neutrino detectors on the Earth have repeatedly seen less than expected 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 flavor for which the detectors had little or no sensitivity. And if a neutrino oscillates, according to the laws of quantum mechanics, then it must have a mass.

In August 2001, a collaboration at the Sudbury Neutrino Observatory, a detector facility located 6,800 feet underground in a mine outside Sudbury, Ontario, which was led by Arthur B. McDonald, checked in with a direct observation suggesting that electron neutrinos from the Sun really were oscillating into muon and tau neutrinos. SNO published its report in the August 13, 2001, issue of Physical Review Letters, and it is widely considered as a very important result. McDonald and Yoji Totsuka were awarded the 2007 Benjamin Franklin Medal in Physics "for discovering that the three known types of elementary particles called neutrinos change into one another when traveling over sufficiently long distances, and that neutrinos have mass".