Comparison of Double-Differential Cross-Sections from Neutron Spectra Using Improved Small Angle Approximation in the Coupled-Channel Equations

摘要

Quantitative methods of predicting neutron and light-ion spectra from heavy ion collisions are developed using analytical abrasion-ablation model. The abrasion stage of the model is based on the Glauber multiple scattering theory with corrections based on Wallace's perturbation method, while the ablation model uses the classical evaporation model developed by Weisskopf-Ewing. The CC (coupled-channel) equations currently are considered in a small angle approximation which is appropriate at high energies where the forward scattering dominates. Previous work assumes the longitudinal momentum transfer for the scattering amplitude to be small. Thus q.x≈q.b + O(θ~2), where θ the scattering angle is assumed to be small and further expansion of the scattering amplitude only consider first order terms in the approximation. We have included the next two higher order terms and re-derived the phase function expressions used to obtain cross-sections. A comparison phase functions for neutron spectra at different scattering angles, generated using the extended terms for the reaction of 400 MeVucleon ~(40)Ar colliding with ~(12)C target, with previous work is done.