Experimental studies on the SPS electron cloud

One of the most important limitations in the performances of the CERN-SPS is presently the Electron Cloud Instability (ECI). Hence, defining its dependence on energy with confidence is an indispensable asset to direct the efforts for all the upgrade studies. Macroparticle simulations carried out with the HEADTAIL code have shown that the ECI mechanism is subtle and the scaling laws valid for the Transverse Mode Coupling Instability cannot be applied to it . The reason lies in the fact that the electron dynamics, while a bunch is going through an electron cloud, is heavily affected by the transverse beam size. In fact, transversely smaller beams can enhance the electron pinch and lower the intensity threshold for the bunch to be unstable. Hence, higher energy beams, though more rigid, can be more unstable due to their smaller transverse size (with constant transverse normalized emittance). During the 2007 run a measurement campaign has been carried out at the CERN-SPS to prove experimentally the outcomes of macroparticle simulations

Work effort in the LHC injector complex for the upgrade scenarios

This document describes the work in the PSB, PS and SPS that is required for upgrade scenario 1. It will be shown that the requirements on the hardware work needed for upgrade scenario 1 are identical to the ones of the upgrade scenario 2 [1]. The various activities are detailed as well as their dependencies and an estimate given for the duration of the necessary shutdowns and recommissioning periods with beam. It is mentioned whether some decisions are still to be taken and are related to information to be obtained after LS1. Another important aspect is the evaluation of the risks related to the upgrade interventions and operational complexity, which concern schedule, beam characteristics as well as reliability and overall performance. It has been studied if part of the activities could be spread out over several machine stops, and as conclusion the preferred scenario will be presented

Beam Loss and Collimation at LHC, CERN-LHC-Project-Report-663

After a short review of past collimation work at LHC, the conception and baseline of the LHC collimation system are described. Abort-gap cleaning and beam loss monitoring are also discussed