Elementary Particles emitted during the decay of certain other particles. It was first postulated
in 1930 by Pauli, Wolfgang in order to maintain the law of conservation (see Conservation Laws) of Energy during beta decay (see Beta Particle; Radioactivity). Further studies showed that the neutrino was also necessary to maintain the
conservation laws of Momentum and spin. The neutrino was not detected directly until 1956. The neutrinos
associated with the Electron and other particles are distinct; each has its own Antiparticle. Neutrinos are stable; they are created and destroyed only by particle decays
involving the Weak Interaction. Neutrinos appear to have little or no Mass, although some experiments have suggested otherwise.