The European Organization for Nuclear Research, also called European Laboratory for Particle Physics, known as CERN (; French pronunciation: [sɛʁn]; Organisation européenne pour la recherche nucléaire), 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 2,704 scientific, technical, and administrative staff members, and hosted about 12,406 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.
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 Conseil Européen pour la Recherche Nucléaire ('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 Organisation européenne pour la recherche nucléaire ('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.
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.
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 125 GeV/c2 consistent with the long-sought Higgs boson