1. SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
2. European XFEL GmbH, Holzkoppel 4, D-22869 Schenefeld, Germany
3. University of Nevada at Reno, Reno, Nevada 89506, USA
4. Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305, USA
5. Sorbonne Universités, UPMC, LULI, UMR 7605, Case 128, 4 Place Jussieu, 75252 Paris Cedex 05, France
6. LULI, Ecole Polytechnique, CEA-CNRS-UPS, 91228 Palaiseau, France
7. Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
8. Dipartimento di Fisica, Università di Trento, via Sommarive 14, Povo 38123, TN, Italy
9. Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, D-91058 Erlangen, Germany
10. Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
11. Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
12. Department of Physics, Stanford University, Stanford, California 94305, USA
13. Universität Rostock, Institut für Physik, D-18051 Rostock, Germany