Affiliation: | (1) Physical Institute, University of Münster, D-48149 Münster, Germany (Fax: +49-251/83-33602, E-mail: florshl@nwz.uni-muenster.de), DE;(2) Applied Physics, University of Paderborn, D-33098 Paderborn, Germany (Fax: +49-5251/60-3422, E-mail: Sohler@physik.uni-paderborn.de), DE;(3) Institute for Medical Physics and Biophysics, University of Münster, D-48149 Münster, Germany (Fax: +49-251/83-55121, E-mail: kubitsc@uni-muenster.de), DE |