1. Nuclear Science and Engineering Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195, Japan
2. Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology (QST), Tokai, Ibaraki 319-1106, Japan
3. Department of Materials Physics, Eötvös University, P.O. Box 32, H-1518 Budapest, Hungary
4. GSI Helmholzzentrum für Schwerionenforschung, Planckstr.1, D-64291 Darmstadt, Germany
5. Technische Universit㲠Darmstadt, D-64287 Darmstadt, Germany