Uncertainties in modeling the capture process in heavy-ion collisions

Abstract

In the present paper, we study the uncertainties in modeling the collision of complex nuclei (heavy ions) resulting in capture of the nuclei into orbital motion. The effective interaction energy of the nuclei (effective potential) consists of three terms: the Coulomb potential, the strong nucleus-nucleus potential, and the centrifugal term related to the orbital motion. The last term usually is considered in the literature as the simplest one. However, we found in the literature at least two different approaches for the centrifugal potential. To see the effect of using these different prescriptions, we evaluate the capture cross sections using the standard quantum-mechanical formula with the transmission coefficients calculated within the quasi-classical approximation. For the Coulomb- and strong nuclear terms we apply the semi-microscopical double-folding model with the effective nucleon-nucleon forces of Yukawa type. For the nucleon densities the two parameter Fermi formula is used with the parameters from the IAEA data base. Our calculations show that the two approaches for the centrifugal potential result in theoretical capture cross sections which are 20-40 percent different. This result holds for any collision energies.