1. Key Laboratory of Radiation Beam Technology and Materials, Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, P. R. China
2. Guangdong Pharmaceutical University, Guangzhou Higher Education Mega Center, Guangzhou 510006, P. R. China
3. Department of Physics, Nanchang University, Nanchang 330031, P. R. China