[en] Summary of session 6, held at the workshop on accelerator operations at Villars-sur-Ollon, 2001. (author)

[en] During the last three years the LEP energy has been steadily increased from 45 GeV (Z₀-physics) to 92.5 GeV (W-physics) and recently up to 100 GeV (Higgs search). In this paper an overview of the beam-physics aspects, the technological aspects and some operational aspects of the LEP high energy running will be presented. (author)

[en] This paper reports that the original design report on the Large Electron-Positron storage ring (LEP) proposed a LEP injector based on a new 22 GeV synchrotron. Subsequently, in order to reduce the cost of the project it was proposed to use the existing Super Proton Synchrotron (SPS) together with its injector, the CERN Proton Synchrotron (CPS) in order to accelerate electrons and positrons up to 20 GeV/c for injection into LEP. It was further proposed to accelerate leptons in the dead time between proton cycles imposed by the average power consumption in the SPS magnets. This implied major changes to the SPS software and hardware, in particular to the master timing generator and to the function generators, in order to operate in a multicycling mode with at least one hadron and four lepton cycles per supercycle. Commissioning of the injector chain started in 1987 and continued into the first half of 1988

[en] The injection of positrons into the first octant of LEP during the LEP injection tests in 1988 required the SPS being operational as an injector for LEP. Positrons were accelerated in the SPS from an energy of 3.5 GeV to about 18 GeV and extracted into LEP during the test which lasted one week. This test as well as the further commissioning of the SPS with leptons could be made without any perturbation to the physics program. The leptons were accelerated in three cycles, interleaved in between the proton cycles and 4 bunches of positrons or electrons were accelerated on each of them. Bunches with intensities exceeding the design value of 0.8 x 10¹⁰ were accelerated. Following preliminary studies countermeasures against various collective effects allowed the acceleration of up to 2.6 x 10¹⁰ particles per bunch. The required momentum for LEP injection of 20 GeV for next year could also be achieved. 11 refs., 2 figs., 2 tabs

[en] This paper reports on the SPS designed to accelerate protons up to 450 GeV and to eject the particles to fixed target experiments. Nowadays it also operates as a p bar p collider with constant or pulsing energy, as an ion synchrotron (O⁸, S¹⁶) and in the future it will serve as an electron/positron injector for LEP. The total operational time must be used in the most efficient way. By interleaving the lepton cycles between the cycles to accelerate protons or ions, the lepton acceleration can be achieved with very little perturbations to the fixed target physics program. In addition, changing the mode of operation should be possible without substantial delays. The control system must allow multicycling as well as fast changes of the operational mode. To fulfill these requirements the hardware of the control system was substantially upgraded: a new timing system and new function generators providing the reference functions for various types of equipment replaced a major part of the old equipment, new console computers and a new computer network were added to the old control system

[en] During the proton-anti proton collider run several experiments were carried out in order to understand the effect of the beam-beam interaction on backgrounds and lifetimes. In this talk a selection of these experiments will be presented. From these experiments, the importance of relative beam sizes and tune ripple could be demonstrated

[en] Future high luminosity hadron colliders such as the LHC at CERN and the SSC will have many bunches and therefore require a non-zero crossing angle to avoid multiple bunch crossings outside the interaction point. Long range beam-beam interactions as well as the possible excitation of synchrobetatron resonances due to this crossing angle have been studied theoretically and with computer simulations. However, very little experimental data is available on the effect of a crossing angle in hadron colliders with bunched beams. The electrostatic separators of the CERN SPS used to separate the orbits in its normal operation as a proton-antiproton collider were used to establish a horizontal crossing angle in one of the interaction regions. The authors have studied the effect of the crossing angle on the beam dynamics to compare with the expectations from theory and to identify possible limitations for future high luminosity colliders, in particular for the Large Hadron Collider currently under study at CERN

[en] A presentation is made of an angular correlation experiment by which we could identify the two fonon O⁺-states in ¹⁰²Pd and ¹⁰⁸Cd. In the case of Pd a comparison is shown with IBA calculations and a levelstructure calculated with a asymmetric rotor vibratormodel. (orig.)

No abstract available

[en] The operation of LEP at high energies (LEP energy upgrade) implies the development of a new low emittance lattice with 90 degrees phase advance in the arcs. It was established that the maximum accumulated intensity was strongly depending on the actual bunchlength. Wigglers are used to artificially lengthen the bunch, which otherwise would be extremely small in this lattice. Depending on the wigglers settings, the onset of vertical instabilities at different thresholds could be observed. A preliminary analysis of both the identification and the behaviour of these spectral lines is presented. (author) 4 refs.; 3 figs