Timeline of particle discoveries
From Wikipedia, the free encyclopedia
Timeline of subatomic particle discoveries.
- 1858 - Cathode rays produced by Julius Plücker (later identified as electrons)
- 1886 - Anode rays produced by Eugene Goldstein (later identified as positive ions)
- 1897 - Electron discovered by J.J. Thompson
- 1899 - Alpha particle discovered by Ernest Rutherford in uranium radiation
- 1900 - Gamma ray (high-energy photon) discovered by Paul Villard in uranium decay.
- 1911 - Atomic nucleus identified by Ernest Rutherford, based on scattering observed by Hans Geiger and Ernest Marsden.
- 1919 - Proton discovered by Ernest Rutherford
- 1932 - Neutron discovered by James Chadwick
- 1932 - Positron discovered by Carl D. Anderson (proposed by Paul Dirac in 1927)
- 1937 - Muon discovered by Seth Neddermeyer, Carl Anderson, J.C. Street, and E.C. Stevenson, using cloud chamber measurements of cosmic rays. (It was mistaken for the pion until 1946.)
- 1947 - Pion discovered by Cecil Powell (predicted by Hideki Yukawa in 1934)
- 1947 - Kaon, the first strange particle, discovered by G.D. Rochester and C.C. Butler
- 1955 - Antiproton discovered by Owen Chamberlain, Emilio Segrè, Clyde Wiegand, and Thomas Ypsilantis
- 1956 - Neutrino detected by Frederick Reines and Clyde Cowan (proposed by Wolfgang Pauli in 1931 to explain the apparent violation of energy conservation in beta decay)
- 1962 - Muon neutrino proved distinct from electron neutrino by group headed by Leon Lederman
- 1969 - Partons (internal constituents of hadrons) observed in deep inelastic scattering experiments between protons and electrons at SLAC; this was eventually associated with the quark model (predicted by Murray Gell-Mann and George Zweig in 1963) and thus constitutes the discovery of the up quark, down quark, and strange quark.
- 1974 - J/ψ particle discovered by groups headed by Burton Richter and Samuel Ting, demonstrating the existence of the charm quark (proposed by Sheldon Glashow, John Iliopoulos, and Luciano Maiani in 1970)
- 1975 - Tau lepton discovered by group headed by Martin Perl
- 1977 - Upsilon particle discovered at Fermilab, demonstrating the existence of the bottom quark (proposed by Kobayashi and Maskawa in 1973)
- 1979 - Gluon observed indirectly in three jet events at DESY
- 1983 - W and Z bosons discovered by Carlo Rubbia, Simon van der Meer, and the CERN UA-1 collaboration (predicted in detail by Sheldon Glashow, Abdus Salam, and Steven Weinberg in the 1960s)
- 1995 - Top quark discovered at Fermilab
- 2000 - Tau neutrino proved distinct from other neutrinos at Fermilab
