The solar neutrino unit (abbreviation SNU, sometimes snu) is a unit of measurement not recognized by the International System of Units, intended to describe the rate of events captured by a neutrino detector emitted by the Sun. p>
Neutrinos are particles that do not interact much with matter. Neutrino detectors must therefore include an extremely large amount of material to expect an event rate of a few units per day. For example, an experiment like GALLEX included 30 tons of reagent (gallium), about 2.5 × 10 atoms, and detected in the order of one interaction per day between a neutrino and a gallium atom.
To properly account for this very low event rate, the SNU was introduced. It corresponds to 10 neutrino uptake per atom per second. For the GALLEX experiment, this corresponds to a few dozen SNUs. code
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