The original LEP machine: Exhibition LEPFest 2000

With a circumference of 27 kilometres,LEP is the largest particle collider in the world.At about 100 metres underground,bunches of electrons and positrons race around in opposite directions as they are accelerated to almost the speed of light.In its first phase of operation,LEP was designed to collide electrons and positrons at an energy of around 100 GeV.After accumulating data on the decay of the Z particle -electrically neutral messenger of the weak force with a mass of 91.2 GeV -everything was done to boost the energy of LEP 's particle beams as high as possible.