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Sudbury Neutrino ObservatoryThe Sudbury Neutrino Observatory (SNO) is located 6800 feet underground in an active nickel mine in Greater Sudbury, Ontario, Canada. The detector is designed to detect solar neutrinos with the Cherenkov effect resulting from extremely rare interactions on the deuterium nuclei in 1000 tonnes of heavy water in a spherical acrylic tank, surrounded by around 9600 light sensors called Photomultiplier Tubes (PMTs). Most PMTs are mounted on a geodesic sphere and look inward at the heavy water. The inner tank and the sensors sit inside a large tank of ordinary water. This detector is large enough to statistically determine the arrival direction of neutrinos, and has the objectives of understanding the solar neutrino problem, neutrino oscillations and neutrino mass. The first measurements of the number of solar neutrinos reaching the earth were taken in the 1960s, and all experiments prior to SNO observed a third to a half fewer neutrinos than were predicted by the Standard Solar Model. One of the possible explanations for the reduced flux was the theory of neutrino flavor oscillation: the neutrinos emitted by the sun would undergo fundamental changes into other types of neutrinos as they travel through the sun. On June 18th, 2001, the first scientific results of the Observatory were published, bringing the first clear evidence that this theory was correct. The actual flux of neutrinos measured by SNO coincides with the theoretical output. Further measurements carried out by the Observatory have since confirmed this result. SNO is also capable of detecting a supernova within our galaxy. As neutrinos emitted by a supernova are released earlier than the photons, it would be possible to alert the astronomical community before the supernova be visible. SNO is a funding member of SNEWS with Super-Kamiokande and LVD. Asteroid (14724) SNO is named in honor of the Observatory. The Sudbury Neutrino Observatory is a major setting in the Neanderthal Parallax trilogy by Canadian science fiction author Robert J. Sawyer. The SNO project used the KDE tools. Related topics Other neutrino observatories External links
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