Multipole-field correction of stretched-wire measurements of the gradient in accelerator magnets

A measurement system for the correction of gradient-field measurements using stretched wires is described. Relative field multipoles of a magnet are measured through the oscillating-wire technique. Then, by means of the same setup, the multipoles are used to correct the gradient measurements with the stretched wire technique. In this paper, after an analytical background on stretched and oscillating wire methods, the proposed correction is described. Results of experimental validation of the proposed correction on measurements of a quadrupole for the CLIC accelerator study at CERN in the final full paper will be illustrated.