1. Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
2. Photon Science Division, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
3. UCL Department of Medical Physics and Biomedical Engineering, Malet Place, Gower Street, London WC1E BT, United Kingdom
4. EMPA, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
5. Department of Physics, Technical University of Denmark, Anker Engelundsvej 1, 2800 Kgs Lyngby, Denmark