1. Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, P. R. China
2. State Key Laboratory of Nuclear Physics and Technology, School of Physics, CAPT, HEDPS, and IFSA Collaborative Innovation Center of MoE College of Engineering, Peking University, Beijing 100871, P. R. China
3. Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, P. R. China