Orbit drifts at the LHC interaction points during the squeeze

When the LHC beams were in collision during Run 1, ground motion was the dominant source of orbit changes. Typical drifts over all were below one beam sigma. Maintaining the beams in collision did not pose a significant problem since the drifts occurred over few hours. New schemes likeBeta*-leveling and squeezing with colliding beams represent new challenges for beam control. For such schemes the optics changes that are applied with colliding beams will lead to larger and faster changes as compared to the drifts in stable beams. This note evaluates the impact of correction strategies and optics changes on the beam separation of the IPs.