1. School of Science, Huzhou Teachers College, Huzhou 313000, Zhejiang Province, P.R. China
2. Research Center for Nuclear Physics, Osaka University, 10-1 Mihogaoka, Ibaraki, 567-0047/Osaka, Japan
3. GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen cedex 5, France
4. Univ. of Caen, B.P. 5186, F-14032 Caen Cedex, France
5. Department of Physics, Omsk University, Omsk, 644077, Russia
6. Institute of Theoretical Physics, Chinese Academy of Science, Beijing 100080, P.R. China