1. Key Laboratory of Beam Technology of Ministry of Education
2. College of Nuclear Science and Technology
3. Beijing Normal University
4. Beijing 100875
5. China
6. Department of Physics and Astronomy
7. Hicks Building
8. University of Sheffield
9. Sheffield S3 7RH
10. UK
11. Beijing National Laboratory for Condensed Matter Physics
12. Institute of Physics
13. Chinese Academy of Sciences
14. Beijing 100190
15. P. R. China
16. Advanced Photon Source
17. Argonne National Laboratory
18. Argonne
19. IL 60439
20. USA