The European Organization for Nuclear Research, also called European Laboratory for Particle Physics, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in Meyrin, a western suburb of Geneva, on the France–Switzerland border. It comprises 25 member states. Israel, admitted in 2013, is the only full member geographically out of Europe. CERN is an official United Nations General Assembly observer.
The acronym CERN is also used to refer to the laboratory; in 2024, it had scientific, technical, and administrative staff members, and hosted about users from institutions in more than 80 countries. In 2016, CERN generated 49 petabytes of data.
CERN's main function is to provide the particle accelerators and other infrastructure needed for high-energy physics research – consequently, numerous experiments have been constructed at CERN through international collaborations. CERN is the site of the Large Hadron Collider (LHC), the world's largest and highest-energy particle collider. The main site at Meyrin hosts a large computing facility, which is primarily used to store and analyze data from experiments, as well as simulate events. As researchers require remote access to these facilities, the lab has historically been a major wide area network hub. CERN is also the birthplace of the World Wide Web.
History The convention establishing CERN was ratified on 29 September 1954 by 12 countries in Western Europe. The acronym CERN originally represented the French words for ('European Council for Nuclear Research'), which was a provisional council for building the laboratory, established by 12 European governments in 1952. During these early years, the council worked at the University of Copenhagen under the direction of Niels Bohr before moving to its present site near Geneva.
The acronym was retained for the new laboratory after the provisional council was dissolved, even though the name changed to the current ('European Organization for Nuclear Research') in 1954. According to Lew Kowarski, a former director of CERN, when the name was changed, the abbreviation could have become the awkward OERN, and Werner Heisenberg said that this could "still be CERN even if the name is [not]".
CERN's first president was Sir Benjamin Lockspeiser. Edoardo Amaldi was the general secretary of CERN at its early stages when operations were still provisional, and the first Director-General (1954) was Felix Bloch.
Founding members
At the sixth session of the CERN Council in Paris from 29 June to 1 July 1953, the convention establishing the organization was signed, subject to ratification, by 12 states. The convention was gradually ratified by the 12 founding Member States: Belgium, Denmark, France, the Federal Republic of Germany, Greece, Italy, the Netherlands, Norway, Sweden, Switzerland, the United Kingdom, and Yugoslavia.
Scientific achievements Several major achievements in particle physics have occurred in experiments at CERN. They include: 1973: The discovery of neutral currents in the Gargamelle bubble chamber 1983: The discovery of W and Z bosons in the UA1 and UA2 experiments 1989: The determination of the number of light neutrino families at the Large Electron–Positron Collider (LEP) operating on the Z boson peak 1995: The first creation of antihydrogen atoms in the PS210 experiment 1995–2005: Precision measurement of the Z lineshape, based predominantly on LEP data collected on the Z resonance from 1990 to 1995 1999: The discovery of direct CP violation in the NA48 experiment 2000: The Heavy Ion Programme discovered a new state of matter, quark–gluon plasma. 2010: The isolation of 38 atoms of antihydrogen 2011: Maintaining antihydrogen for over 15 minutes 2012: The discovery of a boson with mass around consistent with the long-sought Higgs boson
In September 2011, CERN attracted media attention when the OPERA Collaboration reported the detection of possibly faster-than-light neutrinos.Adrian Cho, "Neutrinos Travel Faster Than Light, According to One Experiment" , Science NOW, 22 September 2011. Further tests showed that the results were flawed due to an incorrectly connected GPS synchronization cable.
The 1984 Nobel Prize for Physics was awarded to Carlo Rubbia and Simon van der Meer for the developments that resulted in the discoveries of the W and Z bosons. The 1992 Nobel Prize for Physics was awarded to CERN staff researcher Georges Charpak "for his invention and development of particle detectors, in particular the multiwire proportional chamber". The 2013 Nobel Prize for Physics was awarded to François Englert and Peter Higgs for the theoretical description of the Higgs mechanism in the year after the Higgs boson was found by CERN experiments.
Computer science
CERN pioneered the introduction of TCP/IP for its intranet, beginning in 1984. This played an influential role in the adoption of the TCP/IP in Europe (see History of the Internet and Protocol Wars).
In 1989, the World Wide Web was invented at CERN by Tim Berners-Lee. Based on the concept of hypertext, the idea was designed to facilitate information sharing between researchers. This stemmed from Berners-Lee's earlier work at CERN on a database named ENQUIRE. A colleague, Robert Cailliau, became involved in 1990.
In 1995, Berners-Lee and Cailliau were jointly honoured by the Association for Computing Machinery for their contributions to the development of the World Wide Web. A copy of the first webpage, created by Berners-Lee, is still published on the World Wide Web Consortium's website as a historical document. The first website was activated in 1991. On 30 April 1993, CERN announced that the World Wide Web would be free to anyone. It became the dominant way through which most users interact with the Internet.
More recently, CERN has become a facility for the development of grid computing, hosting projects including the Enabling Grids for E-sciencE (EGEE) and LHC Computing Grid. It also hosts the CERN Internet Exchange Point (CIXP), one of the two main internet exchange points in Switzerland. , CERN employs ten times more engineers and technicians than research physicists.
Particle accelerators Current complex
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 2026) active machines are: 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 SpS 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.
The LHC tunnel is located 100 metres underground, in the region between Geneva International Airport and the nearby Jura mountains. The majority of its length is on the French side of the border. It uses the 27 km circumference circular tunnel previously occupied by the Large Electron–Positron Collider (LEP), which was shut down in November 2000. CERN's existing PS/SPS accelerator complexes are used to pre-accelerate protons and lead ions which are then injected into the LHC.
Eight experiments (CMS, ATLAS, LHCb, MoEDAL, TOTEM, LHCf, FASER and ALICE) are located along the collider; each of them studies particle collisions from a different aspect, and with different technologies. Construction for these experiments required an extraordinary engineering effort. For example, a special crane was rented from Belgium to lower pieces of the CMS detector into its cavern, since each piece weighed nearly tons. The first of the approximately magnets necessary for construction was lowered down a special shaft at in March 2005.
The LHC has begun to generate vast quantities of data, which CERN streams to laboratories around the world for distributed processing, making use of a specialized grid infrastructure, the LHC Computing Grid. In April 2005, a trial successfully streamed 600 MB/s to seven different sites across the world.
In August 2008, the initial particle beams were injected into the LHC. The first beam was circulated through the entire LHC on 10 September 2008, but the system failed 10 days later because of a faulty magnet connection, and it was stopped for repairs on 19 September 2008.
The LHC resumed operation on 20 November 2009 by successfully circulating two beams, each with an energy of 3.5 teraelectronvolts (TeV). The challenge for the engineers was then to line up the two beams so that they smashed into each other. This is like "firing two needles across the Atlantic and getting them to hit each other" according to Stephen Myers, director for accelerators and technology.