The effect of the neutron and proton numbers ratio in colliding nuclei on the formation of the evaporation residues in the 34 S + 208 Pb and 36 S + 206 Pb reactions

The difference between observed cross sections of the evaporation residues (ER) of the 34S + 208Pb and 36S + 206Pb reactions formed in the 2n and 3n channels has been explained by two reasons related with the entrance channel characteristics of these reactions. The first reason is that the capture cross section of the latter reaction is larger than the one of the 34S + 208Pb reaction since the nucleus-nucleus potential is more attractive in the 36S + 206Pb reaction due to two more neutrons in isotope 36S. The second reason is the difference in the heights of the intrinsic fusion barrier \(B^{\ast}_{\mathrm{fus}}\) appearing on the fusion trajectory by nucleon transfer between nuclei of the DNS formed after the capture. The value of \( B^{\ast}_{\mathrm{fus}}\) calculated for the 34S + 208Pb reaction is higher than the one obtained for the 36S + 206Pb reaction. This is due to the difference between the \( N/Z\)-ratios in the light fragments of the DNS formed during the capture in these reactions. The \( N/Z\)-ratio has been found by the solution of the transport master equations for the proton and neutron distributions between fragments of the DNS formed at the capture with the different initial neutron numbers \( N=18\) and \( N=20\) for the reactions with the 34S and 36S, respectively.