Measurement of the electron cloud properties by means of a multistrip detector in the CERN SPS

Electron cloud effects presently limit the performances of the CERN SPS with LHC type beams and are of concern for the LHC itself. Electron multipacting in the SPS produces dramatic dynamic pressure increases and strong transverse instabilities K. Cornelis et al. In the LHC the electron cloud is expected to significantly increase the heat load in the cryogenics system. Estimates of these effects are based on computer simulations of the electron cloud build-up and of its spatial distribution in field free regions and in strong magnetic fields. The accuracy of such simulations is therefore a key issue for component design and for the definition of the operating strategies for the LHC. In 2001 a multistrip detector has been installed in the SPS to study the electron cloud and to provide experimental data to validate the models and to better constrain their input parameters. After a description of the monitor characteristics and of its associated electronics an overview of its performance and of the results of the measurements conducted with different proton beam parameters are presented. The measurements are compared with simulation results. Possible monitor upgrades are also discussed. (7 refs).