Collider

Last updated May 01, 2024

A collider is a type of particle accelerator that brings two opposing particle beams together such that the particles collide.^[1] Colliders may either be ring accelerators or linear accelerators.

Colliders are used as a research tool in particle physics by accelerating particles to very high kinetic energy and letting them impact other particles. Analysis of the byproducts of these collisions gives scientists good evidence of the structure of the subatomic world and the laws of nature governing it. These may become apparent only at high energies and for extremely short periods of time, and therefore may be hard or impossible to study in other ways.

Explanation

In particle physics one gains knowledge about elementary particles by accelerating particles to very high kinetic energy and guiding them to colide with other particles. For sufficiently high energy, a reaction occurs that transforms the particles into other particles. Detecting these products gives insight into the physics involved.

To do such experiments there are two possible setups:

Fixed target setup: A beam of particles (the projectiles) is accelerated with a particle accelerator, and as collision partner, one puts a stationary target into the path of the beam.
Collider: Two beams of particles are accelerated and the beams are directed against each other, so that the particles collide while flying in opposite directions.

The collider setup is harder to construct but has the great advantage that according to special relativity the energy of an inelastic collision between two particles approaching each other with a given velocity is not just 4 times as high as in the case of one particle resting (as it would be in non-relativistic physics); it can be orders of magnitude higher if the collision velocity is near the speed of light.

In the case of a collider where the collision point is at rest in the laboratory frame (i.e. ${\vec {p}}_{1}=-{\vec {p}}_{2}$ ), the center of mass energy $E_{\mathrm {cm} }$ (the energy available for producing new particles in the collision) is simply $E_{\mathrm {cm} }=E_{1}+E_{2}$ , where $E_{1}$ and $E_{2}$ is the total energy of a particle from each beam. For a fixed target experiment where particle 2 is at rest, $E_{\mathrm {cm} }^{2}=m_{1}^{2}+m_{2}^{2}+2m_{2}E_{1}$ .^[2]

History

The first serious proposal for a collider originated with a group at the Midwestern Universities Research Association (MURA). This group proposed building two tangent radial-sector FFAG accelerator rings.^[3] Tihiro Ohkawa, one of the authors of the first paper, went on to develop a radial-sector FFAG accelerator design that could accelerate two counterrotating particle beams within a single ring of magnets.^[4]^[5] The third FFAG prototype built by the MURA group was a 50 MeV electron machine built in 1961 to demonstrate the feasibility of this concept.

Gerard K. O'Neill proposed using a single accelerator to inject particles into a pair of tangent storage rings. As in the original MURA proposal, collisions would occur in the tangent section. The benefit of storage rings is that the storage ring can accumulate a high beam flux from an injection accelerator that achieves a much lower flux.^[6]

The first electron-positron colliders were built in late 1950s-early 1960s in Italy, at the Istituto Nazionale di Fisica Nucleare in Frascati near Rome, by the Austrian-Italian physicist Bruno Touschek and in the US, by the Stanford-Princeton team that included William C.Barber, Bernard Gittelman, Gerry O’Neill, and Burton Richter. Around the same time, the VEP-1 electron-electron collider was independently developed and built under supervision of Gersh Budker in the Institute of Nuclear Physics in Novosibirsk, USSR. The first observations of particle reactions in the colliding beams were reported almost simultaneously by the three teams in mid-1964 - early 1965. ^[7]

In 1966, work began on the Intersecting Storage Rings at CERN, and in 1971, this collider was operational.^[8] The ISR was a pair of storage rings that accumulated and collided protons injected by the CERN Proton Synchrotron. This was the first hadron collider, as all of the earlier efforts had worked with electrons or with electrons and positrons.

In 1968 construction began on the highest energy proton accelerator complex at Fermilab. It was eventually upgraded to become the Tevatron collider and in October 1985 the first proton-antiproton collisions were recorded at a center of mass energy of 1.6 TeV, making it the highest energy collider in the world, at the time. The energy had later reached 1.96 TeV and at the end of the operation in 2011 the collider luminosity exceeded 430 times its original design goal. ^[9]

Since 2009, the most high-energetic collider in the world is the Large Hadron Collider (LHC) at CERN. It currently operates at 13 TeV center of mass energy in proton-proton collisions. More than a dozen future particle collider projects of various types - circular and linear, colliding hadrons (proton-proton or ion-ion), leptons (electron-positron or muon-muon), or electrons and ions/protons - are currently under consideration for detail exploration of the Higgs/electroweak physics and discoveries at the post-LHC energy frontier. ^[10]

Operating colliders

Sources: Information was taken from the website Particle Data Group.^[11]

Accelerator	Centre, city, country	First operation	Accelerated particles	Max energy per beam, GeV	Luminosity, 10³⁰ cm⁻²s⁻¹	Perimeter (length), km
VEPP-2000	INP, Novosibirsk, Russia	2006	e⁺ e⁻	1.0	100	0.024
VEPP-4М	INP, Novosibirsk, Russia	1994	e⁺ e⁻	6	20	0.366
BEPC II	IHEP, Beijing, China	2008	e⁺ e⁻	2.45^[12]	1000	0.240
DAFNE	LNF, Frascati, Italy	1999	e⁺ e⁻	0.510	453^[13]	0.098
SuperKEKB	KEK, Tsukuba, Japan	2018	e⁺ e⁻	7 (e⁻ ), 4 (e⁺ )	24000^[14]	3.016
RHIC	BNL, New York, United States	2000	pp, Au-Au, Cu-Cu, d-Au	255, 100/n	245, 0.0155, 0.17, 0.85	3.834
LHC	CERN, Geneva, Switzerland/France	2008	pp, Pb-Pb, p-Pb, Xe-Xe	6500 (planned 7000), 2560/n (planned 2760/n)	21000,^[15] 0.0061, 0.9, 0.0004	26.659

Related Research Articles

Particle physics or high-energy physics is the study of fundamental particles and forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the scale of protons and neutrons, while the study of combination of protons and neutrons is called nuclear physics.

<span class="mw-page-title-main">Tevatron</span> Defunct American particle accelerator at Fermilab in Illinois (1983–2011)

The Tevatron was a circular particle accelerator in the United States, at the Fermi National Accelerator Laboratory, east of Batavia, Illinois, and was the highest energy particle collider until the Large Hadron Collider (LHC) of the European Organization for Nuclear Research (CERN) was built near Geneva, Switzerland. The Tevatron was a synchrotron that accelerated protons and antiprotons in a 6.28 km (3.90 mi) circumference ring to energies of up to 1 TeV, hence its name. The Tevatron was completed in 1983 at a cost of $120 million and significant upgrade investments were made during its active years of 1983–2011.

<span class="mw-page-title-main">Large Hadron Collider</span> Particle accelerator at CERN, Switzerland

The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundreds of universities and laboratories across more than 100 countries. It lies in a tunnel 27 kilometres (17 mi) in circumference and as deep as 175 metres (574 ft) beneath the France–Switzerland border near Geneva.

ISABELLE was a 200+200 GeV proton–proton colliding beam particle accelerator partially built by the United States government at Brookhaven National Laboratory in Upton, New York, before it was cancelled in July, 1983.

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.

A synchrotron is a particular type of cyclic particle accelerator, descended from the cyclotron, in which the accelerating particle beam travels around a fixed closed-loop path. The magnetic field which bends the particle beam into its closed path increases with time during the accelerating process, being synchronized to the increasing kinetic energy of the particles. The synchrotron is one of the first accelerator concepts to enable the construction of large-scale facilities, since bending, beam focusing and acceleration can be separated into different components. The most powerful modern particle accelerators use versions of the synchrotron design. The largest synchrotron-type accelerator, also the largest particle accelerator in the world, is the 27-kilometre-circumference (17 mi) Large Hadron Collider (LHC) near Geneva, Switzerland, built in 2008 by the European Organization for Nuclear Research (CERN). It can accelerate beams of protons to an energy of 7 tera electronvolts (TeV or 10¹² eV).

The Relativistic Heavy Ion Collider is the first and one of only two operating heavy-ion colliders, and the only spin-polarized proton collider ever built. Located at Brookhaven National Laboratory (BNL) in Upton, New York, and used by an international team of researchers, it is the only operating particle collider in the US. By using RHIC to collide ions traveling at relativistic speeds, physicists study the primordial form of matter that existed in the universe shortly after the Big Bang. By colliding spin-polarized protons, the spin structure of the proton is explored.

The International Linear Collider (ILC) is a proposed linear particle accelerator. It is planned to have a collision energy of 500 GeV initially, with the possibility for a later upgrade to 1000 GeV (1 TeV). Although early proposed locations for the ILC were Japan, Europe (CERN) and the USA (Fermilab), the Kitakami highland in the Iwate prefecture of northern Japan has been the focus of ILC design efforts since 2013. The Japanese government is willing to contribute half of the costs, according to the coordinator of study for detectors at the ILC.

<span class="mw-page-title-main">High-energy nuclear physics</span> Intersection of nuclear physics and high-energy physics

High-energy nuclear physics studies the behavior of nuclear matter in energy regimes typical of high-energy physics. The primary focus of this field is the study of heavy-ion collisions, as compared to lighter atoms in other particle accelerators. At sufficient collision energies, these types of collisions are theorized to produce the quark–gluon plasma. In peripheral nuclear collisions at high energies one expects to obtain information on the electromagnetic production of leptons and mesons that are not accessible in electron–positron colliders due to their much smaller luminosities.

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.

The ISR was a particle accelerator at CERN. It was the world's first hadron collider, and ran from 1971 to 1984, with a maximum center of mass energy of 62 GeV. From its initial startup, the collider itself had the capability to produce particles like the J/ψ and the upsilon, as well as observable jet structure; however, the particle detector experiments were not configured to observe events with large momentum transverse to the beamline, leaving these discoveries to be made at other experiments in the mid-1970s. Nevertheless, the construction of the ISR involved many advances in accelerator physics, including the first use of stochastic cooling, and it held the record for luminosity at a hadron collider until surpassed by the Tevatron in 2004.

The Proton Synchrotron is a particle accelerator at CERN. It is CERN's first synchrotron, beginning its operation in 1959. For a brief period the PS was the world's highest energy particle accelerator. It has since served as a pre-accelerator for the Intersecting Storage Rings (ISR) and the Super Proton Synchrotron (SPS), and is currently part of the Large Hadron Collider (LHC) accelerator complex. In addition to protons, PS has accelerated alpha particles, oxygen and sulfur nuclei, electrons, positrons, and antiprotons.

A hadron collider is a very large particle accelerator built to test the predictions of various theories in particle physics, high-energy physics or nuclear physics by colliding hadrons. A hadron collider uses tunnels to accelerate, store, and collide two particle beams.

<span class="mw-page-title-main">Particle accelerator</span> Research apparatus for particle physics

A particle accelerator is a machine that uses electromagnetic fields to propel charged particles to very high speeds and energies, and to contain them in well-defined beams.

The Low Energy Ion Ring (LEIR) is a particle accelerator at CERN used to accelerate ions from the LINAC 3 to the Proton Synchrotron (PS) to provide ions for collisions within the Large Hadron Collider (LHC).

A Muon Collider is a proposed particle accelerator facility in its conceptual design stage that collides muon beams for precision studies of the Standard Model and for direct searches of new physics. Muons belong to the second generation of leptons, they are typically produced in high-energy collisions either naturally or artificially. The main challenge of such a collider is the short lifetime of muons.

An energy recovery linac (ERL) is a type of linear particle accelerator that provides a beam of electrons used to produce x-rays by synchrotron radiation. First proposed in 1965 the idea gained interest since the early 2000s.

<span class="mw-page-title-main">LHeC</span> Accelerator study for a possible upgrade of the existing LHC storage ring

The Large Hadron Electron Collider (LHeC) is an accelerator study for a possible upgrade of the existing LHC storage ring - the currently highest energy proton accelerator operating at CERN in Geneva. By adding to the proton accelerator ring a new electron accelerator, the LHeC would enable the investigation of electron-proton and electron-ion collisions at unprecedented high energies and rate, much higher than had been possible at the electron-proton collider HERA at DESY at Hamburg, which terminated its operation in 2007. The LHeC has therefore a unique program of research, as on the substructure of the proton and nuclei or the physics of the newly discovered Higgs boson. It is an electron–ion collider, similar to the plans in the US and elsewhere, although the present design would not include polarized protons.

The Future Circular Collider (FCC) is a proposed particle accelerator with an energy significantly above that of previous circular colliders, such as the Super Proton Synchrotron, the Tevatron, and the Large Hadron Collider (LHC). The FCC project is considering three scenarios for collision types: FCC-hh, for hadron-hadron collisions, including proton-proton and heavy ion collisions, FCC-ee, for electron-positron collisions, and FCC-eh, for electron-hadron collisions.

A fixed-target experiment in particle physics is an experiment in which a beam of accelerated particles is collided with a stationary target. The moving beam consists of charged particles such as electrons or protons and is accelerated to relativistic speed. The fixed target can be a solid block or a liquid or a gaseous medium. These experiments are distinct from the collider-type experiments in which two moving particle beams are accelerated and collided. The famous Rutherford gold foil experiment, performed between 1908 and 1913, was one of the first fixed-target experiments, in which the alpha particles were targeted at a thin gold foil.

References

↑ "Fixed-target vs. Collider". 2 August 2013. Archived from the original on 21 January 2022. Retrieved 17 December 2019.
↑ Herr, Werner; Muratori, Bruno (2003). "Concept of Luminosity". CERN Accelerator School: 361–378. Retrieved 2 November 2016.
↑ Kerst, D. W.; Cole, F. T.; Crane, H. R.; Jones, L. W.; et al. (1956). "Attainment of Very High Energy by Means of Intersecting Beams of Particles". Physical Review . 102 (2): 590–591. Bibcode:1956PhRv..102..590K. doi:10.1103/PhysRev.102.590.
↑ USpatent 2890348,Tihiro Ohkawa,"Particle Accelerator",issued 1959-06-09
↑ Science: Physics & Fantasy, Time, Monday, Feb. 11, 1957.
↑ O'Neill, G. (1956). "Storage-Ring Synchrotron: Device for High-Energy Physics Research" (PDF). Physical Review . 102 (5): 1418–1419. Bibcode:1956PhRv..102.1418O. doi:10.1103/PhysRev.102.1418. Archived from the original (PDF) on 2012-03-06.
↑ Shiltsev, V. (2013). "The first colliders: AdA, VEP-1 and Princeton-Stanford". arXiv: 1307.3116 [physics.hist-ph].
↑ Kjell Johnsen, The ISR in the time of Jentschke, CERN Courier, June 1, 2003.
↑ Holmes, Stephen D.; Shiltsev, Vladimir D. (2013). "The Legacy of the Tevatron in the Area of Accelerator Science". Annual Review of Nuclear and Particle Science . 63: 435–465. arXiv: 1302.2587 . Bibcode:2013ARNPS..63..435H. doi:10.1146/annurev-nucl-102212-170615. S2CID 118385635.
↑ Shiltsev, Vladimir; Zimmermann, Frank (2021). "Modern and future colliders". Reviews of Modern Physics . 93 (1): 015006. arXiv: 2003.09084 . Bibcode:2021RvMP...93a5006S. doi:10.1103/RevModPhys.93.015006. S2CID 214605600.
↑ "High Energy Collider Parameters" (PDF). Retrieved 2021-06-03.
↑ Ye, Minghan; Yuan, Changzheng (2020). 30 Years of Bes Physics: Proceedings of the Symposium. World Scientific. p. 319. ISBN 978-981-121-772-2.
↑ Zobov, M. (2010). "Test of crab-waist collisions at DAΦNE Φ factory". Physical Review Letters . 104 (17): 174801. Bibcode:2010PhRvL.104q4801Z. doi:10.1103/PhysRevLett.104.174801. PMID 20482112.
↑ "SuperKEKB collider achieves the world's highest luminosity". 2020-06-26. Retrieved 2020-06-26.
↑ ATLAS Collaboration (2020). "Performance of electron and photon triggers in ATLAS during LHC Run 2". The European Physical Journal C . 80 (1): 47. arXiv: 1909.00761 . Bibcode:2020EPJC...80...47A. doi:10.1140/epjc/s10052-019-7500-2. S2CID 202538006.

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[1] "Fixed-target vs. Collider". 2 August 2013. Archived from the original on 21 January 2022. Retrieved 17 December 2019.

[2] Herr, Werner; Muratori, Bruno (2003). "Concept of Luminosity". CERN Accelerator School: 361–378. Retrieved 2 November 2016.

[3] Kerst, D. W.; Cole, F. T.; Crane, H. R.; Jones, L. W.; et al. (1956). "Attainment of Very High Energy by Means of Intersecting Beams of Particles". Physical Review . 102 (2): 590–591. Bibcode:1956PhRv..102..590K. doi:10.1103/PhysRev.102.590.

[4] USpatent 2890348,Tihiro Ohkawa,"Particle Accelerator",issued 1959-06-09

[5] Science: Physics & Fantasy, Time, Monday, Feb. 11, 1957.

[6] O'Neill, G. (1956). "Storage-Ring Synchrotron: Device for High-Energy Physics Research" (PDF). Physical Review . 102 (5): 1418–1419. Bibcode:1956PhRv..102.1418O. doi:10.1103/PhysRev.102.1418. Archived from the original (PDF) on 2012-03-06.

[7] Shiltsev, V. (2013). "The first colliders: AdA, VEP-1 and Princeton-Stanford". arXiv: 1307.3116 [physics.hist-ph].

[8] Kjell Johnsen, The ISR in the time of Jentschke, CERN Courier, June 1, 2003.

[9] Holmes, Stephen D.; Shiltsev, Vladimir D. (2013). "The Legacy of the Tevatron in the Area of Accelerator Science". Annual Review of Nuclear and Particle Science . 63: 435–465. arXiv: 1302.2587 . Bibcode:2013ARNPS..63..435H. doi:10.1146/annurev-nucl-102212-170615. S2CID 118385635.

[10] Shiltsev, Vladimir; Zimmermann, Frank (2021). "Modern and future colliders". Reviews of Modern Physics . 93 (1): 015006. arXiv: 2003.09084 . Bibcode:2021RvMP...93a5006S. doi:10.1103/RevModPhys.93.015006. S2CID 214605600.

[11] "High Energy Collider Parameters" (PDF). Retrieved 2021-06-03.

[12] Ye, Minghan; Yuan, Changzheng (2020). 30 Years of Bes Physics: Proceedings of the Symposium. World Scientific. p. 319. ISBN 978-981-121-772-2.

[13] Zobov, M. (2010). "Test of crab-waist collisions at DAΦNE Φ factory". Physical Review Letters . 104 (17): 174801. Bibcode:2010PhRvL.104q4801Z. doi:10.1103/PhysRevLett.104.174801. PMID 20482112.

[14] "SuperKEKB collider achieves the world's highest luminosity". 2020-06-26. Retrieved 2020-06-26.

[15] ATLAS Collaboration (2020). "Performance of electron and photon triggers in ATLAS during LHC Run 2". The European Physical Journal C . 80 (1): 47. arXiv: 1909.00761 . Bibcode:2020EPJC...80...47A. doi:10.1140/epjc/s10052-019-7500-2. S2CID 202538006.

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