Optics model

The LHC optics quality after the 2015 commissioning is reviewed. Optics corrections were limited due to a variety of problems. This includes disturbed dispersion measurements due to orbit drifts and an unexpected shift of the IP β-function (β *) waist. The resulting issues will become more critical at the smaller β * of 40 cm foreseen for 2016. Therefore , an improved optics correction strategy with desired actions for the 2016 commissioning is proposed. The optics quality during combined ramp and squeeze is presented and the benefits of ballistic optics measurements are discussed. The optics stability over time and the correction of interaction region (IR) non-linearities are also reviewed.