Precision measurement of transport components

We report on the methods and results of magnetic measurements of the centers and moments of magnetic focusing elements for the Final Focus Test Beam at SLAC. The magnetic center is located by observing an electromotive force (EMF) generated on a vibrating wire within the magnetic aperture. It is found that the center can be located with a precision of a few microns. The multipole coefficients can also be measured by using a grid of stretched-wire sweeps, and mapping the time-integrated voltage throughout the aperture. By fitting directly to this map, the dipole, quadrupole, and sextupole terms of the magnetic field are extracted. The design fields of quadrupoles and sextupoles can be measured with a precision better than 0.1%, and the resolution of sextupole aberrations of quadrupole magnets is well below design tolerances. This method has been used to process twenty-five quadrupoles and four sextupoles. Results of these measurements are presented