LEP hits 100

24 June 1999


CERN’s LEP electron­positron collider walked onto the stage for its 1999 season and, after its customary greeting at the Z resonance (45 GeV per beam), impressed the waiting audience by quickly taking a shot of electrons to a record 100 GeV. This showed how smoothly its complement of 288 superconducting accelerating cavities can pull together, supplying 3.15 GV (3.3 GV without beam).

Soon after, colliding beams were established with 98 GeV electrons and positrons for radiofrequency tests. After these spectacular opening fireworks, high-energy physics got under way with 96 GeV electron and positron beams. Collision rates were high, with luminosities well above 1031 cm-2s-1, with sizable beam currents and good integrated luminosities (1­2 inverse picobarns per day).

Just 10 years ago, LEP began operations equipped with room temperature copper radiofrequency accelerating cavities, supplying 45 GeV per beam. From 1995, equipped with superconducting cavities, LEP’s beam energy was increased to 65 GeV, then to 80.5 GeV in 1996 with more superconducting accelerating power. Last year, LEP ran routinely at 94.5 GeV per beam.

At these new high energies, the LEP experiments are treading on potentially very fertile physics ground and could soon reveal what makes the electroweak theory tick.

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