CERN
CERN is the European Organization for Particle Physics Research, the world's largest particle physics laboratory, situated on the border between France and Switzerland, just west of Geneva. The convention establishing it was signed on September 29, 1954. From the original 12 signatories of the CERN convention, membership has grown to the present 20 Member States.CERN currently employs just under 3000 people full-time. Some 6500 scientists and engineers (representing 500 universities and 80 nationalities), about half of the world's particle physics community, work on experiments conducted at CERN.
The acronym
The acronym originally stood, in French, for Conseil Européen pour la Recherche Nucléaire (European Council for Nuclear Research), which was a provisional council for setting up the laboratory, established by 11 European governments in 1952. The acronym was retained for the new laboratory after the provisional council was dissolved, and informally changed to Centre Européen pour la Recherche Nucléaire (European Centre for Nuclear Research).
The accelerator complex
The CERN accelerator complex has six main accelerators:
- Two linear accelerators generating low energy particles for injection into the Proton Synchroton. One is for protons and the other for heavy ions. These are known as Linac2 and Linac3 respectively.
- The PS Booster, which increases the energy of particles generated by the linear accelerators before they are transferred to the other accelerators.
- The 28 GeV Proton Synchroton (PS) built 1959.
- The Super Proton Synchrotron (SPS), a 2 km diameter circular accelerator built in a tunnel, which started operation in 1971. It originally had an energy of 300 GeV (but has been upgraded several times). As well as having its own beamlines for fixed-target experiments, it has been operated as a proton-antiproton collider, and for accelerating high energy electrons and positrons which were injected into the Large Electron Positron (LEP) collider.
- Isotope Separator On-line (ISOLDE), which was used to study unstable nuclei and first commissioned in 1967. Particles are initially accelerated in the PS Booster before entering ISOLDE.
The accelerator of the future: the LHC
Construction of the CMS detector for LHC at CERN
It also has very impressive computer and wide-area networking facilities which are primarily used for experimental data analysis.
Most of the activities at CERN are currently directed towards building a new collider, the Large Hadron Collider (LHC) and the experiments for it, due to start operation in 2007. This will use the 27 km circumference circular tunnel previously occupied by LEP which was closed down in November 2000, and the PS/SPS complex to pre-accelerate protons which will be injected into it. The tunnel is located 100 m. underground, in the region between the Geneva airport and the nearby Jura mountains. Four experiments (CMS, ATLAS, LHCb and ALICE) are currently being built, and will be running on the collider; each of them will study particle collisions under a different point of view, and with different technologies. Construction for these experiments needed an extraordinary engineering effort. Just as an example, to lower the pieces for the CMS experiment into the underground cavern which will host it, a special crane will have to be rented from Belgium, which will be able to lift the almost 2000 tons of each piece.
Decommissioned accelerators
As the SPS and the LEP tunnels cross the Franco-Swiss border, there are several experimental areas on the French side in addition to the main site which is in Switzerland for legal purposes (although since 1965 it actually occupies land on both sides of the border).
There is also the Antiproton Decelerator (AD), which reduces the speed of antiprotons (which are created travelling at nearly the speed of light) for research into antimatter.
The World Wide Web began as a CERN project. On April 30th 1993 CERN announced that the World Wide Web would be free to anyone, with no fees due.
Computer Science and CERN
Member States
The original CERN signatories were:
Since then:
Bringing the current number of member countries to 20.Footnote
External links