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The Sudbury Neutrino Observatory (SNO), a 1000 ton heavy water Cherenkov detector under construction in INCO's Creighton mine near Sudbury, Ontario (Canada)

Neutrino detectors

Neutrino interactions with matter are extremely rare, making detection difficult. Neutrino detectors are typically large tanks filled with a fluid that reacts to the passage of neutrinos. To take advantage of the high flux of neutrinos passing through the Earth (billions per second), neutrino detectors are made as large as possible. The larger the detector, the more neutrinos can be measured in a reasonable amount of time. For example the Super-Kamionkande device under construction in Japan is designed to detect about 11,000 neutrinos per year.

Early neutrino detectors were filled with perchloroethane (a type of cleaning fluid containing chlorine). A portion of the chlorine is isotope 37 (17 protons and 20 neutrons), which can react with neutrinos to produce Argon-37 (18 protons and 19 neutrons). The amount of Argon-37 created is then used to measure the neutrino flux.

Another fluid used for neutrino detection is water. Neutrino interactions in water produce the Cherenkov effect. Light emitted in this manner is detected by sensitive detectors surrounding the fluid. Cosmic rays can cause unwanted signals in these detectors. To avoid this problem, the detectors are put deep underground, so that layers of rock can shield the detector from cosmic rays.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA