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for the LEP teamThe Large Electron Positron collider LEP at CERN was commissioned in 1989 and finished operation in November 2000. During this period it was operated in different modes, with different optics, at different energies, and with varied performance. In the end, LEP surpassed all relevant design parameters. It has provided a large amount of data for the precision study of the standard model, first on the Z 0 resonance, and then above the W + pair threshold. Finally, with beam energies above 100 GeV, a tantalizing glimpse of what might have been the Higgs boson was observed. A brief history of the main modes of operation, associated performance, the highlights and the challenges met over the 12 years of running is presented. The Large Electron Positron collider LEP at CERN was commissioned in 1989 and finished operation in November 2000. During this period it was operated in different modes, with different optics, at different energies, and with varied performance. In the end, LEP surpassed all relevant design parameters. It has provided a large amount of data for the precision study of the standard model, first on the Z 0 resonance, and then above the W ± pair threshold. Finally, with beam energies above 100 GeV, a tantalizing glimpse of what might have been the Higgs boson was observed. A brief history of the main modes of operation, associated performance, the highlights and the challenges met over the 12 years of running is presented.

The Large Hadron Collider (LHC) will collide proton beams at 14 TeV c.m. with unprecedented stored intensities. The transverse energy density in the beam will be about three orders of magnitude larger than previously handled in the Tevatron or in HERA, if compared at the locations of the betatron collimators. In particular, the population in the beam halo is much above the quench level of the superconducting magnets. Two LHC insertions are dedicated to collimation with the design goals of preventing magnet quenches in regular operation and preventing damage to accelerator components in case of irregular beam loss. We discuss the challenges for designing and building a collimation system that withstands the high power LHC beam and provides the required high cleaning efficiency. Plans for future work are outlined. * Members of CERN-Russia and CERN-Canada Collaborations to the LHC Project Large Hadron Collider Project AbstractThe Large Hadron Collider (LHC) will collide proton beams at 14 TeV c.m. with unprecedented stored intensities. The transverse energy density in the beam will be about three orders of magnitude larger than previously handled in the Tevatron or in HERA, if compared at the locations of the betatron collimators. In particular, the population in the beam halo is much above the quench level of the superconducting magnets. Two LHC insertions are dedicated to collimation with the design goals of preventing magnet quenches in regular operation and preventing damage to accelerator components in case of irregular beam loss. We discuss the challenges for designing and building a collimation system that withstands the high power LHC beam and provides the required high cleaning efficiency. Plans for future work are outlined.

Magnets are at the core of both circular and linear accelerators. The main function of a magnet is to guide the charged particle beam by virtue of the Lorentz force, given by the following expression: F = q v × B, (8.1) where q is the electrical charge of the particle, v its velocity, and B the magnetic field induction. The trajectory of a particle in the field depends hence on the particle Coordinated by F. Bordry

The Compact Linear Collider (CLIC) aims at colliding e^+e^-beams at 1:5 TeV with effective transverse spot sizes of 60nm (horizontal) times 0:7nm (vertical). Strict stability tolerances must be respected in order to achieve a sufficient overlap of the two colliding beams. A stability test stand has been set up at CERN, bringing latest stabilization technology to the accelerator field. Using this technology, a CLIC prototype magnet was stabilized in a normal CERN working environment to less than 1-nm vertical RMS motion above 4 Hz. Detailed simulations of the time-dependent luminosity performance of CLIC are discussed. They include the beam-beam interaction, the beam-based feedbacks and the measured data on magnet stability EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH CERN -AB Division AbstractThe Compact LInear Collider (CLIC) aims at colliding e + e − beams at 1.5 TeV with effective transverse spot sizes of 60 nm (horizontal) times 0.7 nm (vertical). Strict stability tolerances must be respected in order to achieve a sufficient overlap of the two colliding beams. A stability test stand has been set up at CERN, bringing latest stabilization technology to the accelerator field. Using this technology, a CLIC prototype magnet was stabilized in a normal CERN working environment to less than 1-nm vertical RMS motion above 4 Hz. Detailed simulations of the timedependent luminosity performance of CLIC are discussed. They include the beam-beam interaction, the beam-based feedbacks and the measured data on magnet stability.