[Zhou, X. H.; Fu, X. Y.; Dong, J. M.; Liu, Z.; Yu, X. H.; Li, J. G.; Zhang, W. Q.; Huang, H.] Chinese Acad Sci, Inst Modern Phys, Lanzhou 730000, Peoples R China.
[Zhou, X. H.; Fu, X. Y.; Liu, Z.; Yu, X. H.; Huang, H.] Univ Chinese Acad Sci, Beijing 100049, Peoples R China.
[Andreyev, A. N.] Univ York, Dept Phys, York YO10 5DD, England.
[Andreyev, A. N.] Japan Atom Energy Agcy, Adv Sci Res Ctr ASRC, Tokai, Ibaraki 3191195, Japan.
[Qi, C.] AlbaNova Univ Ctr, KTH, SE-10691 Stockholm, Sweden.