European Center for Nuclear Research (Cern)
The European Center for Nuclear Research (CERN) houses the largest magnet in the world. During its course of operation, many of the world's foremost particle physicists have worked or conducted research at the CERN facility. Medical imaging and the World Wide Web were both derived from CERN research. The World Wide Web portion of the Internet actually began as a method for computer scientists at CERN to track high-energy collaborations from physicists all over the world.
CERN was completed in 1954 and is located near Geneva, Switzerland. The facility was one of the first joint scientific ventures built in Europe. Membership has grown from 12 original countries to more than 20 participating countries. About 3,000 people work at CERN, along with visiting scientists who customarily remain on the roster of their home university or research institute. It is not uncommon for researchers at CERN to represent more than 500 universities and more than 80 nationalities.
CERN houses the world's largest particle accelerator, the Large Electron Positron (LEP) collider, built in 1989. Power-generated by electromagnets, the LEP sends subatomic particles around a circular tunnel at the rate of 11,200 times per second. The tunnel has four points where the magnets can push electrons and their antimatter positrons into collision. Banks of computers record the reactions.
The LEP has helped scientists learn about the conditions in the early universe as it evolved following the big bang, about 15 billion years ago. In October 2000, the LEP is scheduled for shut down to make way for a new experiment, the Large Hadron Collider (LHC), which is scheduled to be operational by 2005. The LHC will be able to make particles collide with greater velocity and at much higher energies than the LEP.
When a particle and an antiparticle collide, they annihilate and produce a burst of electromagnetic radiation. A landmark experiment performed at CERN in September 1995 used xenon gas to force particles and antiparticles together. Most of the protons and antiprotons were destroyed, but a few of the collisions resulted in a positron by-product. From these positrons, an even smaller number combined with antiprotons to form antihydrogen. Over the three-week course of the experiment, nine antihydrogen atoms were observed. Once researchers proved that antihydrogen exists, they started looking for other methods of creating it. Scientists at CERN continue to experiment with a technique that traps and cools positrons and antiprotons with a system of magnets, electrical fields, and lasers.
Plans for international physics research did an about-face in 1993 when the U. S. Congress canceled an $11 billion superconducting supercollider project, after first spending $1.9 to dig a tunnel for the supercollider. The Congressional cancellation of the supercollider project in the United States put pressure on CERN to upgrade. When the $2.15 billion construction of the Large Hadron Converter is completed at CERN in 2005, protons will be able to collide at energy levels never attempted before (e.g., about 7,000 billion electron volts or more than 140 times more energy than CERN collisions currently produce).
Other research at CERN involves the use of a super proton synchrotron. When LHC is ready, two of the main experiments will involve compact muon solenoid (CMS), working with unstable leptons; and ATLAS, doughnut-shaped apparatus specifically designed to work with LHC. Both experiments will register high-momentum transfer events. Other experiments planned for LHC include ALICE, a large ion collision experiment to track collisions between heavy ions; and LHC-B, an experiment to study charge conjugation and parity inversion.
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