Timeline of particle discoveries
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This is a timeline of subatomic particle discoveries, including all particles thus far discovered which appear to be elementary (that is, indivisible) given the best available evidence. It also includes the discovery of composite particles and antiparticles that were of particular historical importance.
More specifically, the inclusion criteria are:
- Elementary particles from the Standard Model of particle physics that have so far been observed. The Standard Model is the most comprehensive existing model of particle behavior. All Standard Model particles except the Higgs boson have been verified, and all other observed particles are combinations of two or more Standard Model particles.
- Antiparticles which were historically important to the development of particle physics, specifically the positron and antiproton. The discovery of these particles required very different experimental methods from that of their ordinary matter counterparts, and provided evidence that all particles had antiparticles—an idea that is fundamental to quantum field theory, the modern mathematical framework for particle physics. In the case of most subsequent particle discoveries, the particle and its anti-particle were discovered essentially simultaneously.
- Composite particles which were the first particle discovered containing a particular elementary constituent, or whose discovery was critical to the understanding of particle physics.
Note that there have been many other composite particles discovered; see list of mesons and list of baryons. See List of particles for a more general list of particles, including hypothetical particles.
- 1801: Johann Wilhelm Ritter made the hallmark observation that invisible rays just beyond the violet end of the visible spectrum were especially effective at lightening silver chloride-soaked paper. He called them "oxidizing rays" to emphasize chemical reactivity and to distinguish them from "heat rays" at the other end of the invisible spectrum (both of which were later determined to be photons). The more general term "chemical rays" was adopted shortly thereafter to describe the oxidizing rays, and it remained popular throughout the 19th century. The terms chemical and heat rays were eventually dropped in favor of ultraviolet and infrared radiation, respectively.[1]
- 1895: Discovery of the ultraviolet radiation below 200 nm, named vacuum ultraviolet (later identified as photons) because it is strongly absorbed by air, by the German physicist Victor Schumann.[2]
- 1895: X-ray produced by Wilhelm Röntgen (later identified as photons)[3]
- 1897: Electron discovered by J.J. Thomson[4]
- 1899: Alpha particle discovered by Ernest Rutherford in uranium radiation[5]
- 1900: Gamma ray (a high-energy photon) discovered by Paul Villard in uranium decay.[6]
- 1911: Atomic nucleus identified by Ernest Rutherford, based on scattering observed by Hans Geiger and Ernest Marsden.[7]
- 1919: Proton discovered by Ernest Rutherford[8]
- 1932: Neutron discovered by James Chadwick[9] (predicted by Rutherford in 1920[10])
- 1932: Antielectron (or positron) the first antiparticle, discovered by Carl D. Anderson[11] (proposed by Paul Dirac in 1927)
- 1937: Muon (or mu lepton) discovered by Seth Neddermeyer, Carl D. Anderson, J.C. Street, and E.C. Stevenson, using cloud chamber measurements of cosmic rays.[12] (It was mistaken for the pion until 1947.[13])
- 1947: Pion (or pi meson) discovered by C. F. Powell's group (predicted by Hideki Yukawa in 1935[14])
- 1947: Kaon (or K meson), the first strange particle, discovered by George Dixon Rochester and Clifford Charles Butler[15]
- 1947: Λ0
discovered during a study of cosmic ray interactions[16] - 1955: Antiproton discovered by Owen Chamberlain, Emilio Segrè, Clyde Wiegand, and Thomas Ypsilantis[17]
- 1956: Electron 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)[18] At the time it was simply referred to as neutrino since there was only one known neutrino.
- 1962: Muon neutrino (or mu neutrino) shown to be distinct from the electron neutrino by a group headed by Leon Lederman[19]
- 1964: Xi baryon discovery at Brookhaven National Laboratory[20]
- 1969: Partons (internal constituents of hadrons) observed in deep inelastic scattering experiments between protons and electrons at SLAC;[21][22] this was eventually associated with the quark model (predicted by Murray Gell-Mann and George Zweig in 1964) and thus constitutes the discovery of the up quark, down quark, and strange quark.
- 1974: J/ψ meson discovered by groups headed by Burton Richter and Samuel Ting, demonstrating the existence of the charm quark[23][24] (proposed by James Bjorken and Sheldon Lee Glashow in 1964[25])
- 1975: Tau discovered by a group headed by Martin Perl[26]
- 1977: Upsilon meson discovered at Fermilab, demonstrating the existence of the bottom quark[27] (proposed by Kobayashi and Maskawa in 1973)
- 1979: Gluon observed indirectly in three jet events at DESY[28]
- 1983: W and Z bosons discovered by Carlo Rubbia, Simon van der Meer, and the CERN UA1 collaboration[29][30] (predicted in detail by Sheldon Glashow, Abdus Salam, and Steven Weinberg)
- 1995: Top quark discovered at Fermilab[31][32]
- 1995: Antihydrogen produced and measured by the LEAR experiment at CERN[33]
- 2000: Tau neutrino first observed directly at Fermilab[34]
- 2011: Antihelium-4 produced and measured by the STAR detector
- 2011: Chi_b (3P) discovered by LHC.
[edit] References
- V.V. Ezhela et al. (1996). Particle Physics: One Hundred Years of Discoveries: An Annotated Chronological Bibliography. Springer–Verlag. ISBN 1-56396-642-5.
- ^ Hockberger, P. E. (2002). "A history of ultraviolet photobiology for humans, animals and microorganisms". Photochem. Photobiol. 76 (6): 561–579. doi:10.1562/0031-8655(2002)076<0561:AHOUPF>2.0.CO;2. ISSN 0031-8655. PMID 12511035. http://www.bioone.org/doi/abs/10.1562/0031-8655%282002%29076%3C0561%3AAHOUPF%3E2.0.CO%3B2.
- ^ The ozone layer protects humans from this. Lyman, T. (1914). "Victor Schumann". Astrophysical Journal 38: 1–4. Bibcode 1914ApJ....39....1L. doi:10.1086/142050.
- ^ W.C. Röntgen (1895). "Über ein neue Art von Strahlen. Vorlaufige Mitteilung". Sitzber. Physik. Med. Ges. 137: 1. http://web.lemoyne.edu/~giunta/roentgen.html. as translated in A. Stanton (1896). "On a New Kind of Rays". Nature 53 (1369): 274. Bibcode 1896Natur..53R.274.. doi:10.1038/053274b0.
- ^ J.J. Thomson (1897). "Cathode Rays". Philosophical Magazine 44: 293. http://web.lemoyne.edu/~GIUNTA/thomson1897.html.
- ^ E. Rutherford (1899). "Uranium Radiation and the Electrical Conduction Produced by it". Philosophical Magazine 47: 109.
- ^ P. Villard (1900). "Sur la Réflexion et la Réfraction des Rayons Cathodiques et des Rayons Déviables du Radium". Comptes Rendus de l'Académie des Sciences 130: 1010.
- ^ E. Rutherford (1911). "The Scattering of α- and β- Particles by Matter and the Structure of the Atom". Philosophical Magazine 21: 669.
- ^ E. Rutherford (1919). "Collision of α Particles with Light Atoms IV. An Anomalous Effect in Nitrogen". Philosophical Magazine 37: 581.
- ^ J. Chadwick (1932). "Possible Existence of a Neutron". Nature 129 (3252): 312. Bibcode 1932Natur.129Q.312C. doi:10.1038/129312a0.
- ^ E. Rutherford (1920). "Nuclear Constitution of Atoms". Proceedings of the Royal Society A 97: 324.
- ^ C.D. Anderson (1932). "The Apparent Existence of Easily Deflectable Positives". Science 76 (1967): 238–9. Bibcode 1932Sci....76..238A. doi:10.1126/science.76.1967.238. PMID 17731542.
- ^ S.H. Neddermeyer, C.D. Anderson (1937). "Note on the nature of Cosmic-Ray Particles". Physical Review 51 (10): 884. Bibcode 1937PhRv...51..884N. doi:10.1103/PhysRev.51.884.
- ^ M. Conversi, E. Pancini, O. Piccioni (1947). "On the Disintegration of Negative Muons". Physical Review 71 (3): 209. Bibcode 1947PhRv...71..209C. doi:10.1103/PhysRev.71.209.
- ^ C.D. Anderson (1935). "On the Interaction of Elementary Particles". Proceedings of the Physico-Mathematical Society of Japan 17: 48.
- ^ G.D. Rochester, C.C. Butler (1947). "Evidence for the Existence of New Unstable Elementary Particles". Nature 160 (4077): 855. Bibcode 1947Natur.160..855R. doi:10.1038/160855a0.
- ^ The Strange Quark
- ^ O. Chamberlain, E. Segrè, C. Wiegand, T. Ypsilantis (1955). "Observation of Antiprotons". Physical Review 100 (3): 947. Bibcode 1955PhRv..100..947C. doi:10.1103/PhysRev.100.947.
- ^ F. Reines, C.L. Cowan (1956). "The Neutrino". Nature 178 (4531): 446. Bibcode 1956Natur.178..446R. doi:10.1038/178446a0.
- ^ G. Danby 'et al. (1962). "Observation of High-Energy Neutrino Reactions and the Existence of Two Kinds of Neutrinos". Physical Review Letters 9 (1): 36. Bibcode 1962PhRvL...9...36D. doi:10.1103/PhysRevLett.9.36.
- ^ R. Nave. "The Xi Baryon". Hyperphysics. http://hyperphysics.phy-astr.gsu.edu/hbase/particles/xi.html. Retrieved 20 June 2009.
- ^ E.D. Bloom et al. (1969). "High-Energy Inelastic e–p Scattering at 6° and 10°". Physical Review Letters 23 (16): 930. Bibcode 1969PhRvL..23..930B. doi:10.1103/PhysRevLett.23.930.
- ^ M. Breidenbach et al. (1969). "Observed Behavior of Highly Inelastic Electron-Proton Scattering". Physical Review Letters 23 (16): 935. Bibcode 1969PhRvL..23..935B. doi:10.1103/PhysRevLett.23.935.
- ^ J.J. Aubert et al. (1974). "Experimental Observation of a Heavy Particle J". Physical Review Letters 33 (23): 1404. Bibcode 1974PhRvL..33.1404A. doi:10.1103/PhysRevLett.33.1404.
- ^ J.-E. Augustin et al. (1974). "Discovery of a Narrow Resonance in e+e− Annihilation". Physical Review Letters 33 (23): 1406. Bibcode 1974PhRvL..33.1406A. doi:10.1103/PhysRevLett.33.1406.
- ^ B.J. Bjørken, S.L. Glashow (1964). "Elementary Particles and SU(4)". Physics Letters 11 (3): 255. Bibcode 1964PhL....11..255B. doi:10.1016/0031-9163(64)90433-0.
- ^ M.L. Perl et al. (1975). "Evidence for Anomalous Lepton Production in e+–e− Annihilation". Physical Review Letters 35 (22): 1489. Bibcode 1975PhRvL..35.1489P. doi:10.1103/PhysRevLett.35.1489.
- ^ S.W. Herb et al. (1977). "Observation of a Dimuon Resonance at 9.5 GeV in 400-GeV Proton-Nucleus Collisions". Physical Review Letters 39 (5): 252. Bibcode 1977PhRvL..39..252H. doi:10.1103/PhysRevLett.39.252.
- ^ D.P. Barber et al. (1979). "Discovery of Three-Jet Events and a Test of Quantum Chromodynamics at PETRA". Physical Review Letters 43 (12): 830. Bibcode 1979PhRvL..43..830B. doi:10.1103/PhysRevLett.43.830.
- ^ J.J. Aubert et al. (European Muon Collaboration) (1983). "The ratio of the nucleon structure functions F2N for iron and deuterium". Physics Letters B 123 (3–4): 275. Bibcode 1983PhLB..123..275A. doi:10.1016/0370-2693(83)90437-9.
- ^ G. Arnison et al. (UA1 collaboration) (1983). "Experimental observation of lepton pairs of invariant mass around 95 GeV/c2 at the CERN SPS collider". Physics Letters B 126 (5): 398. Bibcode 1983PhLB..126..398A. doi:10.1016/0370-2693(83)90188-0.
- ^ F. Abe et al. (CDF collaboration) (1995). "Observation of Top quark production in p–p Collisions with the Collider Detector at Fermilab". Physical Review Letters 74 (14): 2626–2631. arXiv:hep-ex/9503002. Bibcode 1995PhRvL..74.2626A. doi:10.1103/PhysRevLett.74.2626. PMID 10057978.
- ^ S. Arabuchi et al. (D0 collaboration) (1995). "Observation of the Top Quark". Physical Review Letters 74 (14): 2632–2637. arXiv:hep-ex/9503003. Bibcode 1995PhRvL..74.2632A. doi:10.1103/PhysRevLett.74.2632. PMID 10057979.
- ^ G. Baur et al. (1996). "Production of Antihydrogen". Physics Letters B 368 (3): 251–258. Bibcode 1996PhLB..368..251B. doi:10.1016/0370-2693(96)00005-6.
- ^ "Physicists Find First Direct Evidence for Tau Neutrino at Fermilab" (Press release). Fermilab. 20 July 2000. http://www.fnal.gov/pub/presspass/press_releases/donut.html. Retrieved 20 March 2010.
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