1. Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo , Kamioka, Gifu 506-1205, Japan
2. Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, University of Tokyo , Kashiwa, Chiba 277-8583, Japan
3. Department of Theoretical Physics, University Autonoma Madrid , Madrid, 28049, Spain
4. Laboratorio Subterraneo de Canfranc, Canfranc Estacion , Huesca, 22880, Spain
5. High Energy Accelerator Research Organization (KEK), Tsukuba , Ibaraki 305-0801, Japan
6. Department of Physics, Okayama University , Okayama, Okayama 700-8530, Japan
7. Department of Physics and Astronomy, The University of Sheffield , Sheffield S3 7RH, UK
8. Boulby Underground Laboratory, Saltburn-by-the-Sea , Redcar & Cleveland TS13 4UZ, UK
9. Tohoku University Research Center for Neutrino Science , Sendai, Miyagi 980-8578, Japan
10. Department of Physics, University of Tokyo , Bunkyo, Tokyo 113-0033, Japan
11. Department of Physics and Astronomy, University of California , Irvine, Irvine, CA 92697-4575, USA
12. Department of Physics, Faculty of Science and Technology, Tokyo University of Science , Noda, Chiba 278-8510, Japan
13. Faculty of Pure and Applied Science, University of Tsukuba , Tsukuba, Ibaraki 305-8577, Japan
14. Nippon Yttrium Co., Ltd., Omuta , Fukuoka 836-0003, Japan