| Affiliation: | [1]Cyclotron Institute and Department of Physics andAstronomy, Texas A＆M University, College Station, TX 77843, USA [2]Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China [3]Dipartimento di Fisica e Astronomia, Universit6 di Catania, V~a S. Sofia 64, 95125 Catania, Italy [4]Department of Physics, East Carolina University, C-209 Howell Science Complex, Greenville, NC 27858, USA [5]Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China |
