Extended Quantum Diffusion Approach to Capture Reactions with Actinides

The Extended Quantum Diffusion Approach (EQDA), incorporating coordinate-dependent friction, is applied to a systematic study of capture cross sections for various projectile-target combinations involving the actinide nuclei (²³⁸U, ²⁴⁴Pu, and ²⁴⁸Cm). For reactions with positive Q₂ₙ values, the two-neutron transfer is assumed to occur before capture, leading to an effective post-transfer entrance channel with modified nuclear properties and quadrupole deformations. The calculated excitation functions describe the available experimental data reasonably well down to deep sub-barrier energies, reaching about 15 MeV below the spherical Coulomb barrier. The systematic analysis shows that the sub-barrier slopes of excitation functions are governed by an interplay between nuclear deformation and the dissipative entrance-channel dynamics. The comparison of the initial and effective post-transfer channels illustrates the influence of the adopted effective-channel prescription, including the change in the projectile deformation description, while the comparison with constant friction demonstrates the role of coordinate-dependent dissipation in the deep sub-barrier region.