Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Inaugural Lecture for the Gordon and Patricia Gray Chair in Particle Astrophysics entitled "A Deeper Understanding of our Universe: SNO and the new SNOLAB"

Prof. Art McDonald
Department of Physics, Queen's University

Wednesday, October 10, 2007
11:30 AM @ Dunning Hall, Rm 14

Abstract:

Why do scientists from Queen's and institutions around the world go 2 km underground in a mine near Sudbury to study particles that are the tiniest and most elusive known? It turns out that these sub-atomic particles, such as neutrinos, play extremely important roles in the fundamental laws of physics and in the evolution of our Universe so it is worth going to great lengths to unlock their secrets. By creating a location that is essentially free from radioactive background, ultra-sensitive measurements can be performed to test fundamental theories of physics with neutrinos from the Sun, Dark Matter particles left over from the Big Bang and extremely rare forms of radioactivity. The presentation will illustrate the unique scientific and engineering aspects of the Sudbury Neutrino Observatory (SNO) project, where an ultra-clean laboratory and a detector the size of a ten-story building have been constructed in CVRD-INCO's Creighton mine. The neutrinos can pass easily through the rock, but other cosmic-ray particles are stopped and prevented from interfering with the experiments. Using 1000 tonnes of heavy water from Canada's reserves, SNO scientists have observed neutrinos produced in the core of Sun and have found clear evidence for a change from the type of neutrino originally produced in the Sun to other types before reaching the Earth.. This requires modification of the Standard Physics Model for elementary particles and confirms theories of energy generation in the Sun with great accuracy. The underground facility is now being expanded to create a long-term international facility for underground science (SNOLAB) with the lowest radioactive background available anywhere. Future measurements will study Dark Matter, thought to make up about 25% of the Universe, and Double Beta Decay, a rare form of radioactivity that can provide insight into the creation of matter following the original Big Bang. The results from SNO to date, their impact on fundamental physics and astrophysics, and the future scientific program for SNO and SNOLAB will be described.