CERN - The European Organisation for Nuclear Research
While exploring the properties and components of atoms particle physicists
found a an astonishing number of new and unstable particles. For investigating
them further the European Community founded a research center in 1954: CERN, the European Organisation for Nuclear Research.
In the meantime much has happened: CERN - situated at the French/Swiss border near Geneva - developped to be among the largest research facilities for particle physics worldwide. Many new particles were found with the help of CERNīs accelerators and their experiments. In consequence a number of CERN physicists won Nobel Prices.
A very good presentation of CERN, its experimetns and achievements can be found at
their public pages
The Machinery
CERN operates several accelerators to accelerate different types of particles to very high energies. The two most important accelerators are the SPS and the LEP. The SPS (Super Proton Synchrotron) is able to accelerate electrons, protons and heavy ions. Its main use is in producing proton beams with an energy of 450 GeV.
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The electrons from SPS are not directly used for experiments. They are first transferred to the LEP (Large Electron Positron Collider). This is a storage ring with a circumference of 27km which is able to accelerate the electrons and positrons to an energy of more than 100GeV. This makes it be the most powerful electron-positron collider worldwide.
The Achievements
The CERN experiments led to a great number of discoveries and insights in different fields of particle physics. Among these are:
- Proton structure
- Neutrino physics
- Weak force and the W and Z particles
- Antimatter and anti-hydrogen
The Future
In November 2000 the operation of the very successful LEP collider has ended. But only to give its tunnel to the LHC (Large Hadron Collider) project which will be its successor. This collider will accelerate two beams of protons to 7000GeV each. Thus it will be the most powerful proton collider. Physicists hope to find answers to many open questions of the actual particle physics: They might find the Higgs particle which is supposed to be giving mass to all other particle. Some theoretical models propose a whole bunch of so called supersymmetric particles which are something like a mirror image of the known particles. If they exist they will probably be found by the LHC experiments too.
But after LHC there will probably still new colliders be built at CERN. CLIC -a linear collider- is one of the projects under investigation.
Visiting CERN
CERN is definitely worth visiting for everyone who has the opporunity to do so. There is an excellent exposition called Microcosm. Of course it is also possible to see some of the experiments. There are guided tours which are organised by the visitor service.
1 GeV: Giga electron volt, the energy an electron gains when going through an acceleration voltage of 1 billion volts.
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