Effects of N/Z on Post-Saddle γ Emission as an Observable of Post-Saddle Nuclear Friction

Based on a dynamical Langevin equation coupled with a statistical decay model, we calculate the variation of the post-saddle giant dipole resonance (GDR) γ-ray multiplicity of the heavy nuclei 240Cf, 246Cf, 252Cf, and 240U with the post-saddle friction strength (β). We find that the sensitivity of the post-saddle γ emission to β decreases considerably with increasing the neutron-to-proton ratio (N/Z) of the system. Moreover, for 240U, the γ emission is no longer sensitive to β. We suggest that to accurately obtain information of the post-saddle friction strength by measuring pre-scission GDR γ-ray multiplicities, it is optimal to choose among the various compound systems those with low N/Z. (nuclear physics)