Beam-based magnetic alignment of the Final Focus Test Beam

In order to optimize tunability and backgrounds in linear collider final focus systems, it is necessary to align strong quadrupole and sextupole magnets with beam-based measurements. Algorithms for alignment have been used successfully on the Final Focus Test Beam (FFTB) beamline at SLAC. Quadrupole magnets were aligned using a shunt technique, with resolutions from 50 microns down to 700 nanometers. Sextupole magnets were aligned by moving the magnets transverse to the beam and observing the kick on downstream beam position monitors. This procedure resulted in sextupole misalignment resolutions of 5 to 20 microns. All magnets were then moved into aligned positions via remote-controlled stages capable of sub-micron resolution. Details of the fitting algorithms, results of the measurement, and potential improvements in the system are discussed.