Introduction to the L3 Experiment at LEP

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L3 is a High Energy Physics Experiment running at the Large Electron Positron, or LEP, collider, which is operated by the European Organisation for Nuclear Research (CERN) in Geneva, Switzerland.

Click on the LEP map below for a perspective view.

The electrons (e-) and positrons (e+) are accelerated by the LEP machine to energies of approximately 45GeV (48 times the proton mass) and collided together at four equidistant points around the 27km LEP ring. The e+ and e- annihilate to form a Z boson, the electrically neutral mediator of the Weak Interaction, which subsequently decays into a fermion-antifermion pair.

The particles produced in these decays are observed in the four LEP detectors, ALEPH, DELPHI, L3, and OPAL, which are situated in large underground experimental halls.

Schematic view of the L3 underground experimental hall.

The L3 detector in the final stages of construction is shown below, together with some of the 500 members of the L3 collaboration, from China, Europe, India, Russia, and the U.S.A.

The L3 Collaboration beside the detector.