SNO INSTITUTE MEMBERS
BACKGROUND INFORMATION ON THE SUDBURY NEUTRINO OBSERVATORY AND SNOLAB
The Sudbury Neutrino Observatory (SNO) is a unique neutrino telescope, the size of a ten-storey
building, two kilometers underground in Inco's Creighton Mine near Sudbury, Ontario. SNO was
planned, constructed and operated by a 130-member team of scientists from Canada, the United States
and the United Kingdom. Through its use of heavy water, the SNO detector provides new ways to detect
neutrinos from the sun and other astrophysical objects and measure their properties.
For many years, the number of solar neutrinos measured by other underground detectors has been found
to be smaller than expected from theories of energy generation in the sun. This had led scientists to infer
that either the understanding of the Sun is incomplete, or that the neutrinos are changing from one type
to another in transit from the core of the Sun. SNO scientists have used the capability of the SNO detector
to measure all three types of neutrinos to determine that solar neutrinos are changing their type en-route
to Earth, thus providing answers to questions about neutrino properties and solar energy generation.
The SNO detector consists of 1000 tonnes of ultra-pure heavy water enclosed in a 12-meter diameter
acrylic plastic vessel, which in turn is surrounded by ultra-pure ordinary water in a giant 22-meter
diameter by 34-meter high cavity. Outside the acrylic vessel is a 17-meter diameter geodesic sphere