1. Max-Planck-Institut für Plasmaphysik, Garching, Germany
2. Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
3. ISIS Facility, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot OX11 0QX, United Kingdom
4. Dipartimento di Fisca “G. Occhialini,” Università degli Studi di Milano-Bicocca, Milano, Italy
5. Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark