Multipole correction of stretched-wire measurements of field-gradients in quadrupole accelerator magnets

A correction of field gradients in quadrupole accelerator magnets measured by stretched-wire methods is described. The gradient is first measured by means of the single-stretched-wire method. By using the same experimental setup, the relative multipole-field errors of the quadrupole are then measured by means of the oscillating-wire technique and used for the correction scheme. Results of the experimental validation are presented for a prototype quadrupole for the CLIC accelerator study at CERN.