Beam-based validation of LHC collimator settings

Abstract

The collimator system provides efficient beam halo cleaning and plays an important role in passive machine protection. About 100 movable collimators are precisely aligned to the beam orbit with gaps as small as 2 mm. In order to ensure the required collimation functionality, the collimator positions need to be validated. This is done by acquiring regularly controlled loss maps in each machine configuration. During 2012, the use of the transverse damper (ADT) to excite transversally the beams in a controlled way has reduced the time to produce betatron loss maps. However, the validation of the off-momentum losses and asynchronous dumps still determines the minimum number of required fills. The experience with the loss maps in the 2010-2013 running period is reviewed and possible improvements are discussed. Aspects related to the minimum time between re-validation by loss maps, possible further improvements such as loss maps at the end of every physics fill and better online monitoring are also discussed.