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In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. The Standard Model presently recognizes seventeen distinct particles—twelve fermions and five bosons. As a consequence of flavor and color combinations and antimatter, the fermions and bosons are known to have 48 and 13 variations, respectively. Among the 61 elementary particles embraced by the Standard Model number: electrons and other leptons, quarks, and the fundamental bosons. Subatomic particles such as protons or neutrons, which contain two or more elementary particles, are known as composite particles.
In particle physics, proton decay is a hypothetical form of particle decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron. The proton decay hypothesis was first formulated by Andrei Sakharov in 1967. Despite significant experimental effort, proton decay has never been observed. If it does decay via a positron, the proton's half-life is constrained to be at least 1.67×1034 years.
A timeline of atomic and subatomic physics, including particle physics.
In physics, a subatomic particle is a particle smaller than an atom. According to the Standard Model of particle physics, a subatomic particle can be either a composite particle, which is composed of other particles, or an elementary particle, which is not composed of other particles. Particle physics and nuclear physics study these particles and how they interact. Most force-carrying particles like photons or gluons are called bosons and, although they have quanta of energy, do not have rest mass or discrete diameters and are unlike the former particles that have rest mass and cannot overlap or combine which are called fermions. The W and Z bosons, however, are an exception to this rule and have relatively large rest masses at approximately 80GeV and 90GeV respectively.
The tau, also called the tau lepton, tau particle, tauon or tau electron, is an elementary particle similar to the electron, with negative electric charge and a spin of 1/2. Like the electron, the muon, and the three neutrinos, the tau is a lepton, and like all elementary particles with half-integer spin, the tau has a corresponding antiparticle of opposite charge but equal mass and spin. In the tau's case, this is the "antitau". Tau particles are denoted by the symbol
τ−
and the antitaus by
τ+
.
The BaBar experiment, or simply BaBar, is an international collaboration of more than 500 physicists and engineers studying the subatomic world at energies of approximately ten times the rest mass of a proton (~10 GeV). Its design was motivated by the investigation of charge-parity violation. BaBar is located at the SLAC National Accelerator Laboratory, which is operated by Stanford University for the Department of Energy in California.
H1 was a particle detector operated at the HERA collider at the German national laboratory DESY in Hamburg. The first studies for the H1 experiment were proposed in 1981. The H1 detector began operating together with HERA in 1992 and took data until 2007. It consisted of several different detector components, measured about 12 m × 15 m × 10 m and weighed 2800 tons. It was one of four detectors along the HERA accelerator.
The Large Electron–Positron Collider (LEP) was one of the largest particle accelerators ever constructed. It was built at CERN, a multi-national centre for research in nuclear and particle physics near Geneva, Switzerland.
Gargamelle was a heavy liquid bubble chamber detector in operation at CERN between 1970 and 1979. It was designed to detect neutrinos and antineutrinos, which were produced with a beam from the Proton Synchrotron (PS) between 1970 and 1976, before the detector was moved to the Super Proton Synchrotron (SPS). In 1979 an irreparable crack was discovered in the bubble chamber, and the detector was decommissioned. It is currently part of the "Microcosm" exhibition at CERN, open to the public.
HERA was a particle accelerator at DESY in Hamburg. It was operated from 1992 to 30 June 2007. At HERA, electrons or positrons were brought to collision with protons at a center-of-mass energy of 320 GeV. HERA was used mainly to study the structure of protons and the properties of quarks, laying the foundation for much of the science done at the Large Hadron Collider (LHC) at the CERN particle physics laboratory today. HERA is the only lepton–proton collider in the world to date and was on the energy frontier in certain regions of the kinematic range.
In particle physics, deep inelastic scattering is the name given to a process used to probe the insides of hadrons, using electrons, muons and neutrinos. It was first attempted in the 1960s and 1970s and provided the first convincing evidence of the reality of quarks, which up until that point had been considered by many to be a purely mathematical phenomenon. It is an extension of Rutherford scattering to much higher energies of the scattering particle and thus to much finer resolution of the components of the nuclei.
ZEUS was a particle detector at the HERA particle accelerator at the German national laboratory DESY in Hamburg. It began taking data in 1992 and was operated until HERA was decommissioned in June 2007. The scientific collaboration behind ZEUS consisted of about 400 physicists and technicians from 56 institutes in 17 countries.
PLUTO was a detector for experimental high-energy particle physics at the German national laboratory DESY in Hamburg. It was operated from 1974 to 1978 at the DORIS synchrotron and was substantially upgraded between 1977 and 1978 for operation at the PETRA accelerator, where it took data until 1979.
The photon structure function, in quantum field theory, describes the quark content of the photon. While the photon is a massless boson, through certain processes its energy can be converted into the mass of massive fermions. The function is defined by the process e + γ → e + hadrons. It is uniquely characterized by the linear increase in the logarithm of the electronic momentum transfer logQ2 and by the approximately linear rise in x, the fraction of the quark momenta within the photon. These characteristics are borne out by the experimental analyses of the photon structure function.
David George Charlton is Professor of Particle Physics in the School of Physics and Astronomy at the University of Birmingham, UK. From 2013 to 2017, he served as Spokesperson of the ATLAS experiment at the Large Hadron Collider at CERN. Prior to becoming Spokesperson, he was Deputy Spokesperson for four years, and before that Physics Coordinator of ATLAS in the run-up to the start of collision data-taking.
Terence Richard Wyatt is a Professor in the School of Physics and Astronomy at the University of Manchester, UK.
Graham Garland Ross was a Scottish theoretical physicist who was the Emeritus Professor of Physics at the University of Oxford and Emeritus Fellow of Wadham College.
Jonathan Mark Butterworth is a Professor of Physics at University College London (UCL) working on the ATLAS experiment at CERN's Large Hadron Collider (LHC). His popular science book Smashing Physics, which tells the story of the search for the Higgs boson, was published in 2014 and his newspaper column / blog Life and Physics is published by The Guardian.
Sinéad Farrington is a British particle physicist who works on the ATLAS experiment at the Large Hadron Collider.
The Double-Ring Storage Facility (DORIS) was an electron–positron storage ring at the German national laboratory DESY. It was DESY's second circular accelerator and its first storage ring, with a circumference of nearly 300 m. After construction was completed in 1974, DORIS provided collision experiments with electrons and their antiparticles at energies of 3.5 GeV per beam. In 1978, the energy of the beams was raised to 5 GeV each.
References
- 1 2 3 Anon (1996). "Marshall, Prof. Robin" . Who's Who (online Oxford University Press ed.). A & C Black. doi:10.1093/ww/9780199540884.013.U26756.(Subscription or UK public library membership required.)
- ↑ Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H. (2011). "Measurement of underlying event characteristics using charged particles in pp collisions at √s = 900 GeV and 7 TeV with the ATLAS detector". Physical Review D. 83 (11): 112001. arXiv: 1012.0791 . Bibcode:2011PhRvD..83k2001A. doi:10.1103/physrevd.83.112001. ISSN 1550-7998. S2CID 119253282.
- ↑ Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; AbouZeid, O. S. (2012). "Search for Pair Production of a Heavy Up-Type Quark Decaying to a W Boson and a b Quark in the lepton + jets Channel with the ATLAS Detector". Physical Review Letters . 108 (26): 261802. arXiv: 1202.3076v2 . Bibcode:2012PhRvL.108z1802A. doi:10.1103/physrevlett.108.261802. ISSN 0031-9007. PMID 23004963. S2CID 39230566.
- ↑ Cox, Brian Edward (1998). Double diffraction dissociation at large momentum transfer (PDF). desy.de (PhD thesis). University of Manchester. OCLC 644443338. EThOS uk.bl.ethos.675409.
- 1 2 Marshall, Robin (2005). "Professor Robin Marshall FRS: Lean mean home page". robinmarshall.eu.
- ↑ Wightman, R.; Marshall, R.; Turner, S. R. (2009). "A Cellulose Synthase-Containing Compartment Moves Rapidly Beneath Sites of Secondary Wall Synthesis". Plant and Cell Physiology. 50 (3): 584–594. doi: 10.1093/pcp/pcp017 . ISSN 0032-0781. PMID 19188260.
- 1 2 Anon (1995). "Professor Robin Marshall". royalsociety.org. London: Royal Society. Archived from the original on 4 March 2016. One or more of the preceding sentences incorporates text from the royalsociety.org website where:
"All text published under the heading 'Biography' on Fellow profile pages is available under Creative Commons Attribution 4.0 International License." -- "Royal Society Terms, conditions and policies". Archived from the original on 25 September 2015. Retrieved 9 March 2016.
{{cite web}}: CS1 maint: bot: original URL status unknown (link) - ↑ http://www.robinmarshall.eu/NC.html [ bare URL ]
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