R. Giachino

OBSERVATIONS OF BEAM-BEAM EFFECTS AT THE LHC

This paper introduces a list of observations related to the beam‐beam interaction that were collected over the first years of LHC proton physics operation (2010‐12). Beam‐ beam related effects not only have been extensively observed and recorded, but have also shaped the operation of the LHC for high-intensity proton running in a number of ways: the construction of the filling scheme, the choice of luminosity levelling techniques, measures to mitigate instabilities, and the choice of settings for improving performance (e.g. to reduce losses), among others.

LONG-RANGE BEAM-BEAM EFFECTS IN THE LHC

We report on the experience with long-range beam‐ beam effects in the LHC, in dedicated studies as well as the experience from operation. Where possible, we compare the observations with the expectations.

Coherent beam-beam mode in the LHC

Observations of single bunch beam‐beam coherent modes during dedicated experiments in the LHC are presented. Their role in standard operation for physics is discussed and, in particular, candidates of beam‐beam coherent mode driven unstable by the machine impedance are presented.

LHC Dry-runs and Machine Check-out

During LS1 most of the equipment groups took the opportunity to upgrade, improve and refactor their hardware and software. A particular care is necessary for the operation team during the testing phase before beam commissioning. Some equipment and software tests from the control room have already started early in the year, including the communication with the experiments, RF frequency ramp, LBDS arming sequence etc… The results will be presented. In parallel, regular meetings between OP and the equipment’s group have started for the establishment of a working plan for the final machine check-out. The strategy for the machine preparation from now to the beam commissioning will explained.