[1] Univ Tokyo, Ctr Nucl Study, Wako, Saitama 3510198, Japan
[2] VAST, Inst Phys, Hanoi, Vietnam
[3] Japan Atom Energy Agcy, Tokai, Ibaraki 3511195, Japan
[4] Kyushu Univ, Dept Phys, Fukuoka 8128581, Japan
[5] Tohoku Univ, Dept Phys, Sendai, Miyagi 9808578, Japan
[6] Univ Tsukuba, Dept Phys, Tsukuba, Ibaraki 3058571, Japan
[7] Yamagata Univ, Fac Sci, Yamagata 9908560, Japan
[8] McMaster Univ, Dept Phys, Hamilton, ON L8S 4L8, Canada
[9] Univ Catania, Catania, Italy
[10] INFN LNS, Catania, Italy
[11] Seoul Natl Univ, Dept Phys, Seoul 151742, South Korea
[12] Ewha Womans Univ, Seoul, South Korea
[13] Inst Modern Phys, Lanzhou, Peoples R China
[14] Chung Ang Univ, Dept Phys, Seoul 156756, South Korea
[15] Max Planck Inst Astrophys, D-85748 Garching, Germany