Mechanism of formation and decay of the compound nuclei150Gd produced by two entrance channels (16O+134Ba) and (40Ar+110Pd)

Abstract

Excitation functions have been drawn for evaporation residues issued from 15~ a compound nucleus produced either by 160 ions on 13~Ba, or by 4~ on 1 lOpd" Absolute cross sections were measured for 145-~47Gd,~45-~47Eu, 14~"8m, 143"Sm, ~4~ and 39raNd" Complete fusion cross sections have been obtained and compared to calculated estimations based, at low energies, on the simple expression aCF = ~R~u~ (1 -V~) where dV eFu s and VFu ~ are respectively the distance and the potential for fusion at ~-r =0. For high energies O-cF--/~Rcr 1--with the model of critical distance Rcr and critical potential Vor. Thresholds energies have been determined with a particular care. The analysis of the shape and the width of excitation functions, particularly for the emission of 4 and 5 neutrons, has been carried out and compared to calculated values. The difference between argon and oxygen induced reactions has been attributed to the difference in 1 population in the entrance channel.