Effects of N/Z on Spin Distribution of Evaporation Residue Cross Section as a Probe of Nuclear Dissipation

The spin distribution of the evaporation residue cross section of nuclei 194Pb, 200Pb, 206Pb, and 200Os are calculated via a Langevin equation coupled with a statistical decay model. It is shown that with increasing the neutron-to-proton ratio (N/Z) of the system, the sensitivity of the spin distribution to the nuclear dissipation is decreased significantly. Moreover, for 200Os this spin distribution is no longer sensitive to the nuclear dissipation. These results suggest that to obtain a more accurate pre-saddle viscosity coefficient through the measurement of the evaporation residue spin distribution, it is best to yield those compound systems with low N/Z