Liu, S. Balandin, V. Beutner, B. Decking, W. Fröhlich, L. Golubeva, N. Lensch, T. JACoW Geneva, Switzerland 978-3-95450-179-3 10.18429/JACoW-FEL2017-TUP003 English 255-258 TUP003 ion collimation FEL optics detector Contribution to a conference proceedings 2018 2018-02 https://doi.org/10.18429/JACoW-FEL2017-TUP003 http://jacow.org/fel2017/papers/tup003.pdf Beam halo measurements and collimations are of great importance at the European XFEL, especially for the operation at high repetition rates (27000 pulses/s). First beam halo measurements have been performed during the commissioning using the wire scanners installed before and after the ~200 m long post-linac collimation section. We present the measurement results and the comparison of beam halo distributions before and after the collimation section.