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TY - UNPB AU - Freund, W. AU - Fröhlich, L. AU - Grünert, J. AU - Karabekyan, S. AU - Koch, A. AU - Liu, J. AU - Nölle, D. AU - Wilgen, J. ED - Schaa, Volker R.W. ED - Decking, Winfried ED - Sinn, Harald ED - Geloni, Gianluca ED - Schreiber, Siegfried ED - Marx, Michaela TI - Undulator Adjustment with the K-Monochromator System at the European XFEL J2 - Proc. of FEL2019, Hamburg, Germany, 26-30 August 2019 CY - Hamburg, Germany T2 - Free Electron Laser Conference T3 - 39 LA - english AB - The SASE1 and SASE2 undulator systems of the European XFEL consist of 35 segments with variable-gap planar undulators which are initially tuned to precise on-axis magnetic field strengths in a magnetic measurement lab. After tunnel installation only photon based methods can determine the K-values of undulator segments with a similar accuracy. The spontaneous radiation of single or few undulator cells is spectrally filtered with the K-monochromator (K-mono) and recorded with a sensitive spontaneous radiation imager (SR-imager). By processing the images from the SR-imager and geometrical fitting of the spatial distribution of the spontaneous radiation we obtain very fast the K-parameter and the beam pointing of single segments. This information is used for adjustments of the gap settings and vertical offset positions of the single undulator segments. In this presentation we describe the K-mono system at the European XFEL, the measurement principle, and the measurements that were performed [1]. PB - JACoW Publishing CP - Geneva, Switzerland ER -