1. Department of Physics, Kyoto University, Kyoto 606-8502, Japan
2. Advanced Research Center for Beam Science, Kyoto University, Kyoto 611-0011, Japan
3. Yokohama National University, Faculty of Engineering, Yokohama 240-8501, Japan
4. Department of Physics, Kobe University, Kobe 657-8501, Japan
5. Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
6. Kamioka Observatory, Institute for Cosmic Ray Research, the University of Tokyo, Hida 506-1205, Japan
7. Kavli Institute for the Physics and Mathematics of the Universe (WPI), the University of Tokyo, Kashiwa 277-8568, Japan
8. Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, 980-8578, Japan
9. Research Center for Neutrino Science, Tohoku University, Sendai 980-8578, Japan