1. State Key Laboratory of Particle Detection and Electronics, Department of Modern Physics, University of Science and Technology of China, 230026 Hefei, People's Republic of China
2. School of Physics and Information Technology, Shaanxi Normal University, 710119 Xian, China
3. Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088, China
4. Macedonian Academy of Sciences and Arts, P.O. Box 428, 1000 Skopje, Macedonia