kb/data/en.wikipedia.org/wiki/CERN-3.md

title	chunk	source	category	tags	date_saved	instance
CERN	4/8	https://en.wikipedia.org/wiki/CERN	reference	science, encyclopedia	2026-05-05T12:40:06.396246+00:00	kb-cron

=== Decommissioned accelerators === The original linear accelerator LINAC 1. Operated 1959–1992. The LINAC 2 linear accelerator injector. Accelerated protons to 50 MeV for injection into the Proton Synchrotron Booster (PSB). Operated 1978–2018. The 600 MeV Synchro-Cyclotron (SC) which started operation in 1957 and was shut down in 1991. Was made into a public exhibition in 2012–2013. The Intersecting Storage Rings (ISR), an early collider built from 1966 to 1971 and operated until 1984. The Super Proton–Antiproton Synchrotron (SppS), operated 1981–1991. A modification of Super Proton Synchrotron (SPS) to operate as a proton-antiproton collider. The Large Electron–Positron Collider (LEP), which operated 1989–2000 and was the largest machine of its kind, housed in a 27 km-long circular tunnel which now houses the Large Hadron Collider. The LEP Pre-Injector (LPI) accelerator complex, consisting of two accelerators, a linear accelerator called LEP Injector Linac (LIL; itself consisting of two back-to-back linear accelerators called LIL V and LIL W) and a circular accelerator called Electron Positron Accumulator (EPA). The purpose of these accelerators was to inject positron and electron beams into the CERN accelerator complex (more precisely, to the Proton Synchrotron), to be delivered to LEP after many stages of acceleration. Operational 1987–2001; after the shutdown of LEP and the completion of experiments that were directly fed by the LPI, the LPI facility was adapted to be used for the CLIC Test Facility 3 (CTF3). The Low Energy Antiproton Ring (LEAR) was commissioned in 1982. LEAR assembled the first pieces of true antimatter, in 1995, consisting of nine atoms of antihydrogen. It was closed in 1996, and superseded by the Antiproton Decelerator. The LEAR apparatus itself was reconfigured into the Low Energy Ion Ring (LEIR) ion booster. The Antiproton Accumulator (AA), built 1979–1980, operations ended in 1997 and the machine was dismantled. Stored antiprotons produced by the Proton Synchrotron (PS) for use in other experiments and accelerators (for example the ISR, SppS and LEAR). For later half of its working life operated in tandem with Antiproton Collector (AC), to form the Antiproton Accumulation Complex (AAC). The Antiproton Collector (AC), built 1986–1987, operations ended in 1997 and the machine was converted into the Antiproton Decelerator (AD), which is the successor machine for Low Energy Antiproton Ring (LEAR). Operated in tandem with Antiproton Accumulator (AA) and the pair formed the Antiproton Accumulation Complex (AAC), whose purpose was to store antiprotons produced by the Proton Synchrotron (PS) for use in other experiments and accelerators, like the Low Energy Antiproton Ring (LEAR) and Super Proton–Antiproton Synchrotron (SppS). The Compact Linear Collider Test Facility 3 (CTF3), which studied feasibility for the future normal conducting linear collider project (the CLIC collider). In operation 2001–2016. One of its beamlines has been converted, from 2017 on, into the new CERN Linear Electron Accelerator for Research (CLEAR) facility.

=== Possible future accelerators ===

CERN, in collaboration with groups worldwide, is investigating two main concepts for future accelerators: A linear electron-positron collider with a new acceleration concept to increase the energy (CLIC) and a larger version of the LHC, a project currently named Future Circular Collider.

== Sites ==

The smaller accelerators are on the main Meyrin site, also known as the West Area, which was originally built in Switzerland alongside the French border, but has been extended to span the border since 1965. The French side is under Swiss jurisdiction and there is no obvious border within the site, apart from a line of marker stones. The SPS and LEP/LHC tunnels are almost entirely outside the main site, and are mostly buried under French farmland and invisible from the surface. They have surface sites at points around them, either as the location of buildings associated with experiments or other facilities needed to operate the colliders such as cryogenic plants and access shafts. The experiments are located at the same underground level as the tunnels at these sites. Three of these experimental sites are in France, with ATLAS in Switzerland, and some of the ancillary cryogenic and access sites are in Switzerland. The largest of the experimental sites is the Prévessin site, also known as the North Area, which is the target station for non-collider experiments on the SPS accelerator. Other sites are the ones which were used for the UA1, UA2 and the LEP experiments. The latter are used by LHC experiments. Outside of the LEP and LHC experiments, most are officially named and numbered after the site where they were located. For example, NA32 was an experiment looking at the production of so-called "charmed" particles and located at the Prévessin (North Area) site. WA22 used the Big European Bubble Chamber (BEBC) at the Meyrin (West Area) site to examine neutrino interactions. The UA1 and UA2 experiments were considered to be in the Underground Area, i.e. situated underground at sites on the SPS accelerator. Most of the roads on the CERN Meyrin and Prévessin sites are named after famous physicists, such as Niels Bohr, who pushed for CERN's creation. Other notable names are Richard Feynman, Albert Einstein, and Wolfgang Pauli.

== Participation and funding ==

=== Member states and budget === Since its foundation by 12 members in 1954, CERN regularly accepted new members. All new members have remained in the organization continuously since their accession, except Spain and Yugoslavia. Spain first joined CERN in 1961, withdrew in 1969, and rejoined in 1983. Yugoslavia was a founding member of CERN but quit in 1961. Of the 24 members, Israel joined CERN as a full member in January 2014, becoming the first, and currently only, non-geographically European full member. The budget contributions of member states are computed based on their Net National Income at factor cost.

=== Enlargement === Associate Members, Candidates: