1. Institute of Physics, University of Tokyo, Meguro, Tokyo 153
2. Physics Laboratory, School of Medicine, Kitasato University, Sagamihara, Kanagawa 228
3. Dept. Industrial Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-03
4. National Research Institute of Police Science, Chiyoda, Tokyo 100
5. Institute for Nuclear Study, University of Tokyo, Tanashi, Tokyo 188