Optical model was developed to describe the following reactions: elastic scattering of deuteron-like particles at heavy nuclei at sub-barrier energies; the break-up of deuteron, scattering at the nuclei by the above-barrier anergies; and polarization of protons by scattering at nuclei at intermediate energies.
In the sub-barrier energy scattering reactions, the nuclear optical potential (NOP) of a weakly coupled particle, obtained from the fit of the experimental data, has non-physical parameters (large values of potential shape parameters, like radii or diffusivity). For the theoretical construction of the optical potential that can predict the magnitudes of the elastic scattering cross sections of such particles, the proposed model has a simple physical content: a weakly bound deuteron-like particle is considered as a composite particle, which is polarized in the Coulomb field, which causes the neutron to fall into the field of action target nuclei. Particle polarization is described by an electrical optical potential within an adiabatic model that has no fitting parameters. For the first time, an analytical expression for electrical optical potential (EOP) has been obtained for the calculations of the elastic scattering of light weakly bound deuteron nuclei in the electric field of heavy nuclei in the area of turning points.
Using of EOP allows the construction of the deuteron-like particle nuclear optical potential without parameter fitting, within the folding model, on the basis of constituent particles ("proton" and "neutron") optical potentials, which are obtained from experimental data on the elastic scattering of these particles. Using the EOP, the wave function of the polarized deuteron in the region of turning points was calculated, and the NOP was obtained as a folding of the sum of the NOP of the proton and neutron with the function of the distribution of these particles in the polarized deuteron. This model allows the use of global optical potentials of nucleons to describe reactions with such composite, weakly-bound particles as deuteron,6He et al.
The cross-sections for deuterons elastic scattering at the energies of 7, 7.3, and 8 MeV on 208Pb nuclei were calculated; for scattering energies of 4, 5.5 and 5 MeV at 124Sn nuclei; for scattering energies of 3.5, 4.5, and 5.16 MeV at 58, 62Ni nuclei. It is shown that taking into account the polarization enhances the nuclear optical potential in the peripheral region and gives a satisfactory description for the experimental data on the scattering of deuterons on nuclei. This confirms the applicability of the proposed model, makes it possible to explain the cause of non-physical parameters of traditional optical potentials in the theoretical interpretation of the data from elastic scattering.
Interaction of deuterons with heavy nuclei by above-barrier energy was investigated. At such energy, the adiabatic approximation is not applicable, since the turning points lie deep in the nuclear field of the target nucleus. The interaction of the deuteron with the target nucleus was considered as an example of the deuteron break-up to a neutron and a proton, with the scattering of the reaction products at small angles. Under this condition, the reaction is predominantly elastic and has been investigated in the Distorted Wave Born Approximation (DWBA). Taking into account only the Coulomb mechanism of the break-up reaction does not sufficiently describe the available experimental data, taking into account the standard NOP of the deuteron and its components further impress the divergence of the calculations with the experiment data. In the proposed approach, the effect of deuteron and its constituents on reaction cross sections was investigated. A zero-point model of a deuteron NOP is proposed, where the interaction potential of a deuteron with a target nucleus is expressed by the sum of the neutron-proton NOP and the folding model of the neutron-proton NOP by the Hülten function of the deuteron ground state.
It is shown that the shape of the break-up reaction cross-section depends on the choice of the model of the deuteron EOP model, but the absolute value of the cross-section exceeds the experimental data almost twice. The model that empirically considered the deuteron internal structure was proposed and gave a satisfactory description of the data. Comparison of the calculated cross sections of the deuteron splitting reaction at 56 MeV with 12C, 40Ca and 90Zr nuclei is compared with the available experimental data, and it is shown that taking into account the internal structure of the deuteron significantly influences the behavior of the calculated characteristics of the splitting reaction at the above-barrier energies.
