1. Key Laboratory of Nuclear Resources and Environment (East China Institute of Technology), Ministry of Education, Nanchang 330013, P. R. China
2. School of Nuclear Engineering and Technology, East China Institute of Technology, Fuzhou 344000, Jiangxi, P. R. China
3. School of Physics, Peking University, Beijing 100871, P. R. China
4. School of Science, Zhongyuan University of Technology, Zhengzhou 450007, Henan, P. R. China
5. Department of Physics, North University of China, Taiyuan 030051, P. R. China
6. China Institute of Atomic Energy, P.O. Box 275(18), Beijing 102413, P. R. China
7. Henan University of Technology, Zhengzhou 450052, Henan, P. R. China
8. College of Food Engineering and Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, P. R. China
9. Shanghai Institute of Applied Physics, The Chinese Academy of Sciences, Shanghai 201800, P. R. China