1. Center for Materials Science and Nanotechnology Department of Chemistry University of Oslo P.O. Box 1033 Blindern 0315 Oslo Norway
2. Department for Neutron Materials Characterization Institute for Energy Technology PO Box 40 2027 Kjeller Norway
3. Institute of Physics Academy of Sciences of the Czech Republic v.v.i, Na Slovance 2 18221 Prague Czech Republic
4. Laboratoire CRISMAT UMR 6508 CNRS ENSICAEN 6 bd du Maréchal Juin 14050 Caen Cedex 4 France