Soft Repulsive Core Effects in (d + d) Scattering and Reaction

Using the single-channel resonating group method, in which a central nucleon-nucleon potential containing a soft repulsive core (SRC) is adopted, the (d + d) scattering phase shifts, differential scattering cross sections, and total reaction cross sections at a series of energies <20 MeV with and without imaginary potentials are calculated. The agreement between the theoretical and experimental results is quite good. The main conclusions are: The (d + d) nonlocal kernel function K_S (R, R') deduced is correct; hence, the discrepancy between the kernels in other similar work is clarified. The SRC causes a decrease in the total strength of the (d − d) direct potential V_Ns(R) and, in particular, the strength of V_Ns for short range and small channel spin s decreases much more. The SRC causes a decrease in the phase shifts δ_ls(E) (toward the negative direction); the decrease is especially large when E is at or near a resonating energy. The SRC reduces the total reaction cross sections σ_R appreciably and causes a distinct increase in the differential scattering cross sections dσ/dΩ(θ) at the forward and backward angles; however, it does not greatly influence the differential cross sections at other angles.