CERN

The European Laboratory for Particle Physics (CERN) is located just outside Geneva, Switzerland and overlaps the border between France and Switzerland. It has a 27 kilometer circumference circular tunnel which houses the Large Electron-Positron Collider (LEP). Under development is another facility called the Large Hadron Collider which should produce proton-antiproton collisions in the energy range 10-14 TeV. This should enable it to produce a large number of top quarks and offers a chance of seeing the proposed Higgs particle.

The Super Proton Synchrotron (SPS) at CERN is one of the worlds largest protron synchrotrons, reaching energies of 450 GeV.

Another major facility at CERN is the Intersecting Storage Rings (ISR), the first proton-proton collider to be put into operation (1971). It had a maximum proton energy of 31 GeV per beam.

LEP

The world's largest electron synchrotron is the Large Electron-Positron Collider (LEP) at CERN. It has a radius of about 4 km. For the electron synchrotrons, the maximum energy is limited by the losses to synchrotron radiation which increases with the fourth power of the particle energy. Since those losses are inversely proportional to the square of the orbit radius, these accelerators are made as large as possible.

A part of CERN, the Large Electron-Positron Collider (LEP) occupies a 27 kilometer circumference circular tunnel near Geneva which overlaps the Swiss-French border. It was designed to study electron-positron collisions at a center of mass energy equal to the Z⁰ mass energy, about 100 GeV.

Large Hadron Collider

The Large Hadron Collider is latest member of CERN's collection of extraordinary high-energy facilities and is the world's largest and highest-energy accelerator. It occupies a 27 kilometer circumference circular tunnel near Geneva which overlaps the Swiss-French border, the same tunnel that contains the LEP. Successful particle beams were produced in the LHC in 2008 and in 2010 the two beams reached 3.5 TeV, half the target maximum for the accelerator.

Currently the work at the LHC is divided into six experiments denoted by the names ATLAS, CMS, ALICE, LHCb, TOTEM and LHCf.

A major current objective for the LHC is the search for the Higgs boson. Announcements as of November 2011 suggest that the energy range for the Higgs boson has been narrowed to between 114 and 141 GeV.

Currently some excitement is being generated by results at the LHCb or "Beauty" detector, a portion of which is shown at left. A 0.8% imbalance between the decay rates of the D-meson and its antiparticle has been discovered.

Though a small difference, it is a newly discovered difference between matter and antimatter and could contribute to the solution of the "antimatter problem" in cosmology.

References:

CERN Home

CERN Document Server

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