Affiliation: | aUniv. Simon Bolivar, Nuclear Physics Section, Apdo. 89000, Caracas, Venezuela bAtomic Energy Research Institute P.O.B. 49, H-1525 Budapest, Hungary cInst. for Biomedical Problems, Moscow 123007, Russian Federation dRes. Inst. for Technical Phys. & Material Sci. P.O.B. 49, H-1525 Budapest, Hungary |