Department of Physics;
Fudan University;
Shanghai 200433;
China;
Department of Physics and Astronomy;
University ofCalifornia;
Los Angeles;
CA 90095;
USA;
Key Laboratory of Nuclear Physics and Ion-beamApplication (MOE);
Institute of Modem Physics;
FudanUniversity;
Shanghai 200433;
China;
Shanghai Institute of Applied Physics;
Chinese Academy ofSciences;
Shanghai 201800;
China;