1. Key Laboratory of Radiation Physics and Technology (Sichuan University); Ministry of Education; Institute of Nuclear Science and Technology; Sichuan University; 610064 Chengdu P. R. China
2. Laboratory of Nuclear Energy Chemistry; Institute of High Energy Physics; Chinese Academy of Sciences; 100049 Beijing P. R. China
3. Institute of High Energy Physics; Southwestern Institute of Physics; 610041 Chengdu P. R. China
4. Chemical Sciences Division; Institute of High Energy Physics; Lawrence Berkeley National Laboratory; 94720 Berkeley California USA