Protection of LEP Experiments against Particle Background at Highest Beam Energies

The protection system used to shield LEP experiments against particle backgrounds has been upgraded in view of the much higher photon background rates expected at LEP2 energies. General experience with background rates in the LEP experiments at highest beam energies is reported and special features are highlighted

Particle Background at LEP with Head-On colliding Bunch Trains

The vertical closed orbit bumps around the interaction points in LEP, which are needed to separate counter rotating bunches at their parasitic collision points, generate additional particle backgrounds at the LEP detectors. Monte Carlo simulations of photon and electron backgrounds have been performed and their predictions compared with experimental data. This has led to a good understanding of the bunch train specific background sources and allowed efficient protection measures to be devised

Beam Tails in LEP

Beam tails have been measured in LEP using scraping collimators and loss monistors for separated and colliding beams. Significant non-Gaussian beam tails have been observed with colliding beams for high beam-beam tune shift parameters and bunch currents