w' decaying to lepton plus heavy neutrino

They were negatively charged but curved less sharply than electrons, but more sharply than protons, for particles of the same velocity. Anderson noticed particles that curved differently from electrons and other known particles when passed through a magnetic field. Anderson and Seth Neddermeyer at Caltech in 1936 while studying cosmic radiation. Μ, which differs from the electron neutrino and participates in different nuclear reactions. These interactions usually produce pi mesons initially, which almost always decay to muons.Īs with the other charged leptons, the muon has an associated muon neutrino, denoted by Nonetheless, they are produced in great amounts in high-energy interactions in normal matter, in certain particle accelerator experiments with hadrons, and in cosmic ray interactions with matter. For example, so-called secondary muons, created by cosmic rays hitting the atmosphere, can penetrate the atmosphere and reach Earth's land surface and even into deep mines.īecause muons have a greater mass and energy than the decay energy of radioactivity, they are not produced by radioactive decay. This allows muons of a given energy to penetrate far deeper into matter because the deceleration of electrons and muons is primarily due to energy loss by the bremsstrahlung mechanism. There is also a third lepton, the tau, approximately 17 times heavier than the muon.ĭue to their greater mass, muons accelerate slower than electrons in electromagnetic fields, and emit less bremsstrahlung (deceleration radiation). Muons have a mass of 105.66 MeV/ c 2, which is approximately 206.768 2830(46) times that of the electron, m e. Formerly, muons were called mu mesons, but are not classified as mesons by modern particle physicists (see § History), and that name is no longer used by the physics community. Like all elementary particles, the muon has a corresponding antiparticle of opposite charge (+1 e) but equal mass and spin: the antimuon (also called a positive muon). Muon decay almost always produces at least three particles, which must include an electron of the same charge as the muon and two types of neutrinos. As with the decay of the non-elementary neutron (with a lifetime around 15 minutes), muon decay is slow (by subatomic standards) because the decay is mediated only by the weak interaction (rather than the more powerful strong interaction or electromagnetic interaction), and because the mass difference between the muon and the set of its decay products is small, providing few kinetic degrees of freedom for decay. The muon is an unstable subatomic particle with a mean lifetime of 2.2 μs, much longer than many other subatomic particles. As with other leptons, the muon is not thought to be composed of any simpler particles that is, it is a fundamental particle. Anderson, Seth Neddermeyer (1936)Ī muon ( / ˈ m( j) uː ɑː n/ M(Y)OO-on from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 e and a spin of 1 / 2, but with a much greater mass. The Moon's cosmic ray shadow, as seen in secondary muons generated by cosmic rays in the atmosphere, and detected 700 meters below ground, at the Soudan 2 detectorĬarl D.

W' decaying to lepton plus heavy neutrino