Electron Cloud in the Sps Summary

• The first talk by F. Ruggiero [1] gave a short introduction to some key concepts relevant to the discussion of electron cloud effects and their implications for PS, SPS and LHC operation. • This was followed by a talk given by W. Höfle [2] who reported about strong perturbations on pick-up signals of the SPS transverse feedback system (damper), observed with LHC type beams and attributed to the electron cloud effect. He also presented observations with a solenoid magnetic field and encouraging tests with new electronics, working at a multiple of the bunch frequency. • SPS vacuum observations and, in particular, the dependence of the measured strong pressure rise on various beam parameters were reported in the third talk by J.M. Jimenez [3]. Also electron currents collected by a dedicated, shielded pick-up as well as first indications of some conditioning effect were discussed. • The last talk on SPS experimental observations by G. Arduini [4] focussed on a fast instability, accompanied by emittance blow-up and beam losses. The effect is more pronounced in the horizontal plane and affects mainly the tail of the batch. • N. Hilleret [5] gave an overview of secondary electron yield (SEY) measurements for pure metals versus technical surfaces, performed by an electron gun and a collector cage, with very low primary electron currents. He discussed the effect of oxide layers, adsorbed water, and special surface treatments, including bake-out, freon processing, glow discharge, low emissivity coatings, electron and photon dosing. • Simulation results for SPS and LHC were presented by F. Zimmermann [6], who explained how the electron cloud build-up is modelled and what are the potential implications for the heat load on the LHC beam screen and for beam stability in the SPS and LHC. • I.R. Collins [7] discussed possible remedies, including surface conditioning by photon scrubbing and electron bombardment. • Finally R. Cappi [8] reported about methods to produce gaps in the bunch train of the LHC beam via RF manipulations in the PS.