LHC Orbit Stabilisation Tests at the SPS

The LHC, presently being built at CERN, is the first proton collider that requires a continuous orbit control for safe and reliable machine operation. A realistic test of the orbit feedback system was performed in 2004 using already-present LHC instrumentation and infrastructure on a 270GeV coasting beam in the Super-Proton-Synchrotron. It has been demonstrated that the chosen feedback architecture can stabilise the beam better than 10 micrometres and is essentially limited by the noise of the beam position monitor and the bandwidth of the corrector magnets. The achieved orbit stability is comparable to those found at modern light sources and gives enough operational margin with respect to the requirements of the LHC Cleaning System (70 µ m). Estimates for the longterm drifts and achievable stability will be presented based on the experimental results.