HE Li1,3,SUN Zheng2,NING Chang-chun1,3,TSERING-Nyima1,3
1. School of Science, Tibet University, Lhasa, Tibet 850000, China;
2. College of Physics, Sichuan University, Chengdu, Sichuan 610064; China;
3. Key Laboratory of Cosmic Rays, Ministry of Education, Tibet University, Lhasa, Tibet 850000, China