The Large Electron Positron collider (LEP) with a 27 km circumference,
is the biggest machine in the world. Housed deep underground, LEP collides electrons with
their antimatter counterparts, positrons, inside four huge detectors:
which probe the electromagnetic and weak forces in minute detail. Each of the detectors
has been optimised differently to study various physics aspects.
LEP was designed to study the weak force, the mechanism which fuels the sun and is
responsible for some forms of natural radioactivity. The weak force is carried between
particles of matter by 'messenger-particles' called W+, W- and Z. In
its first phase from 1989 to 1995, LEP produced collisions with just the right energy to
make the Z. In its second phase, known as LEP2 which began in 1996, LEP runs at twice this
energy, sufficient to produce W+ and W- in pairs, completing studies
of the weak force. Detection of millions of Z0s and hundreds of Ws has allowed the LEP
experiments to make extremely precise tests of the Standard Model of particles and their
interactions.
© Copyright CERN - Last modified on 1998-08-21 - Tradotto da Sofia Sabatti
