An Etymological Dictionary of Astronomy and Astrophysics

A short-lived → elementary particle with negative → electric charge, represented by the symbol μ^-. The muon was discovered in 1936 by Carl Anderson (1905-1991) in → cosmic rays. It shares several properties with the electron: it is a → lepton with the same charge and → spin as the electron. But it is heavier than the electron (105 MeV/c²), about 200 times more massive. The muon is instable and decays after 2.197 × 10^-6 s into → electron, → neutrino, and → antineutrino (μ^-→ e^- + ν_μ + anti ν_e) .

See also: A shortening of mu meson, from mu the 12th letter of the Gk. alphabet, + → meson.