[1] Chinese Acad Sci, Inst Modern Phys, Lanzhou 730000, Peoples R China
[2] Univ Chinese Acad Sci, Sch Nucl Sci & Technol, Beijing 100049, Peoples R China
[3] Chinese Acad Sci, Inst Modern Phys, CAS Key Lab High Precis Nucl Spect, Lanzhou 730000, Peoples R China
[4] Indian Inst Technol, Dept Phys, Mumbai 400076, India
[5] Iowa State Univ, Dept Phys & Astron, Ames, IA 50011 USA