• F. Hellberg, H. Danared, A. Hedqvist
  MSL, Stockholm
• J. Pflüger
  DESY, Hamburg

The undulators of the European free-electron laser (XFEL) are 128 to 226 meters in length and divided into five meter long segments. Each segment ends with a quadrupole magnet to focus the electron beam and to maintain optimum spatial overlap between the electron and photon beams. At the Manne Siegbahn Laboratory a rotating coil instrument has been built to characterize these quadrupoles and to measure the position of the magnetic center. In combination with a coordinate measurement machine the magnetic center can be measured with respect to fiducials on the magnet. The aim is to measure the position of the magnetic center within 0.050 mm. In this work the experimental setup is presented together with fiducialization of test magnets.