1. Japan Atomic Energy Agency, Tokai-mura Naka-gun, Ibaraki 319-1195, Japan
2. Cyclotron and Radioisotope Center, Tohoku University, 6-3 Aoba, Aramaki, Aoba, Sendai, Miyagi 980-8578, Japan
3. Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-34, O-okayama, Meguro-ku, Tokyo 152-8550, Japan
4. Institute of Radiochemistry, Forschungszentrum Dresden-Rossendorf, P.O. Box 51 01 19, 01314 Dresden, Germany
5. Mitsubishi Materials Corporation, 1002-14, Mukohyama, Naka-city, Ibaraki 311-0102, Japan