1. Institute of Modern Physics Lanzhou, Chinese Academy of Sciences, 730000 Lanzhou, China
2. GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
3. Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198, Japan
4. Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
5. Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
6. Niigata University, Niigata, Niigata 950-2181, Japan