Multi-turn losses and cleaning in 2011 and 2012

LHC beam collimation is based on a hierarchical multistage cleaning system. Maintaining the correct hierarchy ensures maximal cleaning efficiency and machine protection. The operational collimator positions are established from the beam centres and sizes at each collimator measured in beam-based alignments. These are verified periodically during the year. The improvements made to the collimator alignment algorithm in 2011 are described. The time spent on setup and qualification by loss maps is summarized in detail. The stability of the collimator setup and cleaning efficiency is presented. An outlook to 2012 is given, including detailed considerations on improved setup speed, required frequency of setup and qualification and other possible improvements overall reducing beam time consumption for collimation.