1. Department of Physics; Norwegian University of Science and Technology; Høgskoleringen 5 N-7491 Trondheim Norway
2. Paul Scherrer Institut; CH-5232 Villigen PSI Switzerland
3. Department of Structural Engineering; Norwegian University of Science and Technology; Høgskoleringen 5 N-7491 Trondheim Norway
4. Department of Energy Conversion and Storage; Technical University of Denmark; Frederiksborgvej 399 DK-4000 Roskilde Denmark