Institution: | [1]Department of Physics, Jilin University, Changchun 130021 [2]Institute of Physics and Tandem Accelerator Center, University Of Tsukuba, Ibaraki 305, Japan [3]Insititute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 [4]Department of Space Science and Applied Physics, Shandong University at Weihai, Weihai 264209 |