Events at LEP's highest energies - so far

27 May 1998

Display high resolution image

The world's largest particle accelerator, the Large Electron Positron collider (LEP), is running at higher energies than ever before. The machine, which is at CERN, the European Laboratory for Particle Physics near Geneva, collides high energy beams of electrons and their antiparticles, positrons. This week, it reached a new highest total energy of 189 GeV (giga electron volts). This image shows a computer reconstruction of the aftermath of one of these high-energy collisions recorded in the experiment known as OPAL, one of four experiments at LEP. The electron and positron (unseen) have collided at the centre of the image and annihilated to produce new particles. These leave tracks in OPAL's tracking detectors (inner circle) and deposit energy (depicted as blocks of colour) in the outer layers of detectors known as calorimeters. Four "jets" of particles are visible, which have been coloured red (2 o'clock), yellow (5 o'clock), green (7 o'clock) and blue (11 o'clock). It is likely that the four jets originate from two pairs of quark and antiquark, each produced by the decay of a W particle (the charged carrier of the weak force that underlies beta-decay).

(The LEP collider was shut down to make way for a new machine, the LHC, in November 2000.)

Credit: CERN / OPAL

Please contact person or institution named for information about permission for public or commercial use.