[1] Fraunhofer-Inst. Nondestr. T., D-01326 Dresden, Germany
[2] Fraunhofer-Inst. Nondestr. T., D-66123 Saarbrücken, Germany
[3] LURE, Université Paris Sud, F-91405 Orsary, France
[4] Europ. Synchrt. Radiation Facility, BP 220, F-38043 Grenoble Cedex, France