Reaction dynamics of Pt*isotopes formed using stable and radioactive Sn beams

Abstract

The decay of various isotopes of Pt${}^{*}$ formed using stable and neutron-rich radioactive beams of Sn is studied by using the dynamical cluster-decay model (DCM). The entrance channel effect in ${}^{190}$Pt${}^{*}$ compound nuclei is investigated using different targets and projectiles. For both entrance channels, i.e., ${}^{132}$Sn+${}^{58}$Ni and ${}^{126}$Sn+${}^{64}$Ni, the fragmentation potential and preformation probability of decaying fragments are almost identical at comparable center-of-mass energies (${E}_{\mathrm{c}.\mathrm{m}.}$), enabling us to conclude that decay of ${}^{190}$Pt${}^{*}$ is independent of its formation effects. In order to check for the persistence of entrance channel independence in the decay of Pt${}^{*}$ compound nuclei, various versions of nuclear proximity potentials and different values of level density parameter are employed in the calculations, and the results are sustained. It is also observed that, with inclusion of deformation effects up to quadrupole (${\ensuremath{\beta}}_{2}$) within the optimum orientation approach, the structure of potential energy surfaces changes significantly. Besides this, the fission mass distribution of Pt${}^{*}$ isotopes is investigated and consequently the barrier modification is estimated to account for the phenomena of fusion hindrance. The ${}^{132}$Sn+${}^{58}$Ni reaction is also studied using four proximity potentials, i.e., Prox 1977, Prox 1988, mod-Prox 1988, and Denisov 2002 within the framework of the $\ensuremath{\ell}$-summed extended-Wong model for addressing the fusion hindrance phenomena. We find that Prox 77 and Prox 88 fit the total fusion cross-section data only at above-barrier energies, whereas Denisov 2002 underestimates the data at all energies due to being least sensitive towards asymmetry and isospin. So a stronger nuclear interaction potential mod-Prox 1988 that accounts for isospin effect and asymmetry of the colliding nuclei is employed, which fits the data with smooth variation of ${\ensuremath{\ell}}_{\mathrm{max}}$(${E}_{\mathrm{c}.\mathrm{m}.}$). Our calculations indicate that the isospin and asymmetry of colliding nuclei also play an important role in the fusion dynamics, particularly in the below-barrier region.