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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| CERN | 2/8 | https://en.wikipedia.org/wiki/CERN | reference | science, encyclopedia | 2026-05-05T12:40:06.396246+00:00 | kb-cron |
CERN operates a network of seven accelerators and two decelerators, and some additional small accelerators. Each machine in the chain increases the energy of particle beams before delivering them to experiments or to the next more powerful accelerator. The decelerators naturally decrease the energy of particle beams before delivering them to experiments or further accelerators/decelerators. Before an experiment is able to use the network of accelerators, it must be approved by the various Scientific Committees of CERN. Currently (as of 2022) active machines are the LHC accelerator and:
The LINAC 3 linear accelerator generating low energy particles. It provides heavy ions at 4.2 MeV/Da for injection into the Low Energy Ion Ring (LEIR). The Low Energy Ion Ring (LEIR) accelerates the ions from the ion linear accelerator LINAC 3, before transferring them to the Proton Synchrotron (PS). This accelerator was commissioned in 2005, after having been reconfigured from the previous Low Energy Antiproton Ring (LEAR). The Linac4 linear accelerator accelerates negative hydrogen ions to an energy of 160 MeV. The ions are then injected to the Proton Synchrotron Booster (PSB) where both electrons are then stripped from each of the hydrogen ions and thus only the nucleus containing one proton remains. The protons are then used in experiments or accelerated further in other CERN accelerators. Linac4 serves as the source of all proton beams for CERN experiments. The Proton Synchrotron Booster increases the energy of particles generated by the proton linear accelerator before they are transferred to the other accelerators. The 28 GeV Proton Synchrotron (PS), built during 1954–1959 and still operating as a feeder to the more powerful SPS and to many of CERN's experiments. The Super Proton Synchrotron (SPS), a circular accelerator with a diameter of 2 kilometres built in a tunnel, which started operation in 1976. It was designed to deliver an energy of 300 GeV and was gradually upgraded to 450 GeV. As well as having its own beamlines for fixed-target experiments (currently COMPASS and NA62), it has been operated as a proton–antiproton collider (the SppS collider), and for accelerating high energy electrons and positrons which were injected into the Large Electron–Positron Collider (LEP). Since 2008, it has been used to inject protons and heavy ions into the Large Hadron Collider (LHC). The On-Line Isotope Mass Separator (ISOLDE), which is used to study unstable nuclei. The radioactive ions are produced by the impact of protons at an energy of 1.0–1.4 GeV from the Proton Synchrotron Booster. It was first commissioned in 1967 and was rebuilt with major upgrades in 1974 and 1992. The Antiproton Decelerator (AD), which reduces the velocity of antiprotons to about 10% of the speed of light for research of antimatter. The AD machine was reconfigured from the previous Antiproton Collector (AC) machine. The Extra Low Energy Antiproton ring (ELENA), which takes antiprotons from AD and decelerates them into low energies (speeds) for use in antimatter experiments. The AWAKE experiment, which is a proof-of-principle plasma wakefield accelerator. The CERN Linear Electron Accelerator for Research (CLEAR) accelerator research and development facility.
==== Large Hadron Collider ====
Many activities at CERN currently involve operating the Large Hadron Collider (LHC) and the experiments for it. The LHC represents a large-scale, worldwide scientific cooperation project.