1. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
2. European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
3. Department of Applied Physics, Stanford University, Stanford, California 94305, USA
4. Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
5. Department of Physics, Stockholm University, Stockholm 10691, Sweden
6. Department of Physics, Stanford University, Stanford, California 94305, USA
7. van der Waals-Zeeman Institute, University of Amsterdam, 1018XE Amsterdam, The Netherlands
8. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
9. San Jose Research Center, HGST a Western Digital Company, 3403 Yerba Buena Road, San Jose, California 95135, USA
10. Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany
11. Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
12. Department of Applied Physics, Institute for Photonic Integration, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
13. Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden