Effect of magnet alignment jittering in the damping ring and RTL on wake fields in the linac

In order to reduce the beam emittance blow-up due to wake fields in the linac to a tolerable level, it is necessary that the beam injection into the linac does not jitter too much. The tolerance is set to be +- 13 μm in displacement or +- 0.3 μrad in angle at the injection point where E = 1.2 GeV. This tolerance assumes β = 42 m at the injection point and represents about 2% of the local rms beam size. One potential source of injection jitter comes from the damping ring ejection kicker. Another - which is the subject of this study - is due to the jittering in the alignments of the damping ring and RTL magnets (due to earth motion, nearby pumps, etc.). We assume this alignment jittering is random from magnet to magnet. (If we do not plan to have a fast feedback at the linac injection point; these misalignments do not have to jitter from pulse to pulse; they could be slowly oscillating in time and be equally harmful.) We estimate the tolerance on the magnet alignment jittering to be 0.1 μm