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The neutrino is an elementary particle. It has spin 1/2 and so it is a fermion. Its mass is very small, although recent experiments (see Super-Kamiokande) have shown it to be above zero. It feels neither the strong nor the electromagnetic force, so it only interacts through the weak force and gravitation. Because the neutrino only interacts weakly, when moving through ordinary matter its chance of interacting with it is very small. It would take a light year of lead to block half the neutrinos flowing through it. Neutrino detectors therefore typically contain hundreds of tons of a material constructed so that a few atoms per day would interact with the incoming neutrinos.
1 Types of neutrinos
There are three different kinds, or flavors, of neutrinos: the electron neutrino νe, the muon neutrino νμ and the tau neutrino ντ, named after their partner leptonA lepton lambda;επτ&omicron is also €0. 01 in Greek. See: Greek euro coins. In physics, a particle is a lepton if it has a spin of 1/2 and does not experience the strong nuclear force. The leptons form a family of elementary particles in the Standard ModelThe Standard Model of particle physics is a theory which describes the strong, weak, and electromagnetic fundamental forces, as well as the fundamental particles that make up all matter. It is a quantum field theory, and consistent with both quantum mecha (see table at right). In a phenomenon known as neutrino oscillation neutrinos spontaneously mutate among the three flavors. Whereas the more common view holds, that there are separate neutrinos and antineutrinos, it cannot be ruled out that these particles are actually the same.
2 History
The neutrino was first postulated in 19311931 is the common year starting on Thursday. see link for calendar) Events January January 4 Female aviator Elly Beinhorn begins her flight to Africa January 6 Thomas Edison submits his last patent application. January 22 Sir Isaac Isaacs sworn in as the by Wolfgang Pauli to explain the continuous spectrum of beta decay, the decay of a neutron into a proton and an electron. Pauli theorized that an undetected particle was carrying away the observed difference between the energy and angular momentum of the initial and final particles. Because of their "ghostly" properties, the first experimental detection of neutrinos had to wait until about 25 years after they were first discussed. In 1956 Clyde Cowan, Frederick Reines, F. B. Harrison, H. W. Kruse, and A. D. McGuire published the article "Detection of the Free Neutrino: a Confirmation" in Science (see neutrino experiment), a result that was rewarded with the 1995 Nobel Prize. The name neutrino was coined by Enrico Fermi as a word play on neutrone, the Italian name of the neutron particle. (Neutrone in Italian also means big and neutral, and neutrino means small and neutral.)
In 1962 Leon Max Lederman , Melvin Schwartz and Jack Steinberger found out that more than one type of neutrino exists.
