- Also called:
- collider
- Key People:
- Simon van der Meer
- Gerard K. OâNeill
colliding-beam storage ring
-
What is a colliding-beam storage ring?
A colliding-beam storage ring facilitates energetic interactions between opposing particle beams. Beams can consist of identical particles within separate magnet rings or oppositely charged particles within a single ring.
These rings intersect at interaction regions, where the beams, stored in bunches, collide. Detectors at collision points record particles produced during annihilation. The highest interaction energies are achieved in these rings, positioning them at the forefront of research.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How does a colliding-beam storage ring work?
Colliding-beam storage rings enable energetic interactions between opposing particle beams. Beams can consist of identical particles within separate magnet rings or oppositely charged particles within a single ring.
Particles are accelerated, then injected into storage rings. Beams are bunched to collide at interaction regions, where detectors record post-collision particles. The interaction rate is proportional to the currents in the two beams.
These rings achieve the highest interaction energies, advancing knowledge despite fewer interactions than stationary targets and not producing intense secondary particle beams.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Why do scientists use colliding-beam storage rings instead of single beam accelerators?
Colliding-beam storage rings enable energetic interactions between beams moving in opposite directions. When a moving particle strikes a stationary one, only half of the kinetic energy is usable for heat or deformation because the rest sets the target material in motion, following momentum conservation principles.
In contrast, when particles move in opposite directions with equal speeds, all kinetic energy becomes available upon impact. Although the number of interacting particles is smaller than in fixed-target experiments, the high orbital frequency of circulating beams in storage rings allows useful interaction experiments.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What are the main parts of a colliding-beam storage ring?
A colliding-beam storage ring is a type of cyclic particle accelerator that stores and accelerates two counterrotating beams of charged subatomic particles before they collide head-on.
Main parts:
* Source All accelerators must have a source that generates electrically charged particles.
* Electric fields All accelerators must have electric fields to accelerate the particles.
* Magnetic fields All accelerators must have magnetic fields to control the paths of the particles. The magnets with this "bending" function are dipolesâmagnets with two poles, north and south, built with a C-shaped profile so that the particle beam can pass between the two poles.
* Vacuum The particles must travel through a good vacuum.
* Detectors All accelerators must have some means of detecting, counting, and measuring the particles after they have been accelerated through the vacuum.
* Interaction regions The rings intersect at interaction regions where the beams collide.
* Focusing magnet A second important function of electromagnets in particle accelerators is to focus the particle beams in order to keep them as narrow and intense as possible.3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How do colliding-beam storage rings help scientists study particles?
Colliding-beam storage rings enable energetic interactions between opposing particle beams. When particles moving in opposite directions collide, all kinetic energy converts to heat or deformation. For instance, two 31.4-GeV protons colliding yield 62.3 GeV for interaction, unlike a 400-GeV proton striking a resting proton, which yields only 27.4 GeV.
These rings feature two separate magnet rings where magnetic fields guide particles in opposite directions, intersecting at interaction regions for collisions. Alternatively, beams of oppositely charged particles can circulate in the same vacuum chamber.
Colliding-beam storage rings achieve the highest interaction energies, positioning research at the forefront of knowledge. Researchers use electron-positron storage rings to study subatomic particles.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What important discoveries have been made using colliding-beam storage rings?
Colliding-beam storage rings have facilitated significant discoveries in particle physics. The detection of the J/psi particle in 1974 at SLAC and Brookhaven provided support for the existence of the charmed quark.
These rings enable high-energy interactions between particle beams moving in opposite directions, maximizing the energy available for creating new particles and probing fundamental forces. Notably, experiments at DESY in 1979 confirmed the existence of the gluon through observation of its radiation by quarks.
The highest interaction energies are achieved using colliding-beam storage rings, positioning them at the forefront of the quest for knowledge in particle physics.
4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
colliding-beam storage ring, type of cyclic particle accelerator that stores and then accelerates two counterrotating beams of charged subatomic particles before bringing them into head-on collision with each other. Because the net momentum of the oppositely directed beams is zero, all the energy of the colliding beams is available to produce very-high-energy particle interactions. This is in contrast to interactions produced in fixed-target particle accelerators, in which a beam of accelerated particles strikes particles in a stationary target and only a fraction of the beam energy is transformed into the particle interaction energy. (Most of the beam energy is converted to kinetic energy in the products of the collision, in accordance with the law of conservation of momentum.) In a collider the product or products can be at rest, and virtually all of the combined beam energy is therefore available for new-particle creation via the Einstein mass-energy relation. The hunt for massive subatomic particlesâfor example, the W and Z carrier particles of the weak force or the âtopâ quarkâhas been successful because of the construction of powerful colliding-beam storage ring particle accelerators such as the Large Electron-Positron (LEP) collider at the European Organization for Nuclear Research (CERN) in Geneva and the Tevatron at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois.
The basic structural element of most colliders is a synchrotron (accelerator) ring. The early collider projectsâfor example, the Intersecting Storage Rings (ISR) proton-proton collider, which operated at CERN in the 1970sâwere built to collide beams of identical particles and so required two synchrotron rings that were interlaced to bring the beams into collision at two or more points. Two synchrotron rings are also required if the colliding beams contain particles of different mass, such as at the electron-proton collider that began operation in 1992 at DESY (German Electron Synchrotron) in Hamburg, Germany.
A single synchrotron ring can accommodate two beams of particles traveling in opposite directions, provided the two beams contain particles having the same mass but opposite electric chargeâthat is, if the beams consist of a particle and its antiparticle, for example, an electron and a positron or a proton and an antiproton. Bunches of each type of particle are injected into the synchrotron ring from a preacceleration source. Once a sufficiently large number of particles has accumulated in each beam, the two beams are accelerated simultaneously until they reach the desired energy. The beams are then brought into collision at predetermined points surrounded by particle detectors. Actual interactions between particles are relatively rare (one of the drawbacks of colliding-beam systems), and the beams can typically circulate, colliding on each circuit, for several hours before the beams are âdumpedâ and the machine âfilledâ once again.
" height="20" alt="HEW Logo">
Fermilab was the site of the Tevatron, the worldâs highest-energy proton-antiproton collider, which operated from 1985 to 2011 and delivered particle beams at energies of 900 gigaelectron volts (GeV) per beam to produce total collision energies of 1,800 GeV (equivalent to 1.8 teraelectron volts, TeV). CERN operates the worldâs largest collider ring, with a circumference of 27 km (17 miles). From 1989 to 2000 the ring contained the LEP collider, which was able to reach a maximum energy of 100 GeV per beam. A much-higher-energy collider, the Large Hadron Collider (LHC), which began test operations at CERN in 2008, replaced the LEP collider in the 27-km ring. The LHC project is designed to bring about collisions between two proton beams or between beams of heavy ions, such as lead ions. In 2009 the LHC became the highest-energy particle accelerator when it produced proton beams with energies of 1.18 TeV. As a proton-proton collider, the LHC is expected to deliver a total collision energy of approximately 14 TeV. The large 27-km synchrotron tunnel is occupied by superconducting magnets and houses two separated beam lines with opposite magnetic fields to accommodate collisions between beams of identical particles.