Quadrupole Misalignments and Steering in Long Linacs
  We present a study of orbit jitter and emittance growth in a long linac caused by misalignment of quadrupoles. First, assuming a FODO lattice, we derive analytical formulae for the RMS deviation of the orbit and the emittance growth caused by random uncorrelated misalignments of all quadrupoles. We then consider an alignment algorithm based on minimization of BPM readings with a given BPM resolution and finite mover steps. 
G. V. Stupakov