A technician checks the wires of a wire chamber forming part of the DELPHI detector at CERN, the European centre for particle physics near Geneva. DELPHI is one of 4 giant particle detectors at the LEP collider. LEP collides electrons & positrons accelerated to an energy of 50 GeV in a circular tunnel 100m underground & 27km in circumference. DELPHI is a cylindrical assembly of many types of apparatus - wire chambers, calorimeters, Cerenkov counters, & a time projection chamber - which fit together like layers of an onion around the point where the particles collide. DELPHI is a collaboration of some 400 physicists & 400 support staff from 40 institutions in 18 countries.