Study of the TI 8 optics and beam stability based on beam trajectories

The optics and the stability of the SPS-LHC transfer line TI 8 was studied with beam trajectories during its commissioning in October 2004. Steering magnet response measurements were used to analyze the quality of the steering magnets and of the beam position monitors. A simultaneous fit of the quadrupole strengths was used to search for setting or calibration errors. A large setting error of a quadrupole was identified with this technique, as well as a 1% phase advance error in the vertical plane. Residual coupling between the planes was evaluated using high statistics samples of trajectories. The same high statistics sample were analysed using the Model Independent Analysis technique to understand possible sources of trajectory movements. The transfer line was found to be very stable and the dominant source of position jitter seems to be due to the ripple of the extraction septum.