Affiliation: | (1) Physics Department, Texas A&M University, 77843 College Station, Texas, USA;(2) Present address: Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing, China;(3) Present address: Universität (TH), D-7500 Karlsruhe, FRG;(4) Present address: General Dynamics, Pomona Division, P.O. Box 2507, 91769 Pomona, CA, USA |