Collider
A collider is a type of
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. ), the center of mass energy (the energy available for producing new particles in the collision) is simply , where and is the total energy of a particle from each beam. For a fixed target experiment where particle 2 is at rest, .[2]
History
The first serious proposal for a collider originated with a group at the
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
In 1966, work began on the
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−2 s−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 | p p , 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 |
See also
- List of colliders
- Fixed-target experiment
- Large Electron–Positron Collider
- Large Hadron Collider
- Very Large Hadron Collider
- Relativistic Heavy Ion Collider
- International Linear Collider
- Storage ring
- Tevatron
- International Conference on Photonic, Electronic and Atomic Collisions
- Future Circular Collider
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.
- .
- ^ US patent 2890348, Tihiro Ohkawa, "Particle Accelerator", issued 1959-06-09
- ^ Science: Physics & Fantasy, Time, Monday, Feb. 11, 1957.
- doi:10.1103/PhysRev.102.1418. Archived from the original(PDF) on 2012-03-06.
- arXiv:1307.3116 [physics.hist-ph].
- ^ Kjell Johnsen, The ISR in the time of Jentschke, CERN Courier, June 1, 2003.
- S2CID 118385635.
- S2CID 214605600.
- ^ "High Energy Collider Parameters" (PDF). Retrieved 2021-06-03.
- ISBN 978-981-121-772-2.
- PMID 20482112.
- ^ "SuperKEKB collider achieves the world's highest luminosity". 2020-06-26. Retrieved 2020-06-26.
- S2CID 202538006.