Roles of Isospin in Evaporation Residue Cross Section as a Probe of Nuclear Dissipation

<Abstract>The influence of isospin on the excess of evaporation residue cross section over its standard statistical-model value for nuclei ^(194)Pb,^(200)Pb,and ^(206)pb is studied via a Langevin equation coupled with a statistical decay model.The magnitude of this excess for a low-isospin fissioning nucleus is shown to be larger and its dependence on the nuclear viscosity coefficient to be stronger than those of a high-isospin fissioning nucleus.These results suggest that to obtain a more accurate information of viscosity coefficient inside the saddle point by measuring evaporation residue cross sections, we had better choose those compound systems with small isospin.

The influence of isospin on the excess of evaporation residue cross section over its standard statistical-model value for nuclei ^194pb, ^200Pb, and ^206pb is studied via a Langevin equation coupled with a statistical decay model. The magnitude of this excess for a low-isospin fissioning nucleus is shown to be larger and its dependence on the nuclear viscosity coefficient to be stronger than those of a high-isospin fissioning nucleus. These results suggest that to obtain a more accurate information of viscosity coefficient inside the saddle point by measuring evaporation residue cross sections, we had better choose those compound systems with small isospin.