1. Department of Physics, Norwegian University of Science and Technology, Hoegskoleringen
5, N-7491 Trondheim, Norway
2. Department of Cancer Research
and Molecular Medicine, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
3. Centre for Advanced Study (CAS)
at the Norwegian Academy of Science and Letters, Drammensveien 78, N-0271 Oslo, Norway
4. MAX IV Laboratory, Lund University, SE-221 00 Lund, Sweden