Speaker
Description
Electromagnetic breakup of weakly bound nuclei is a standard probe of halo structure at radioactive-ion beam facilities. In post-form DWBA, the reduced transition amplitude requires evaluating highly oscillatory six-dimensional integrals containing Coulomb distorted waves, for which straightforward numerical quadrature converges very slowly.
In this work, our main focus is the efficient and stable numerical evaluation of these long-range oscillatory integrals using the Vincent–Fortune (VF) contour integration method. By rotating the asymptotic part of the integral into the complex plane, VF converts the problematic oscillatory tail into an exponentially damped, fast-converging contribution.
We benchmark VF against direct Gaussian quadrature for representative test cases relevant to breakup calculations: products of spherical Bessel functions, Coulomb wave functions, and combinations involving partial-wave expansions. VF achieves stable convergence with orders-of-magnitude fewer integration points, giving a major reduction in computation time while maintaining accuracy, and we discuss practical choices of contour parameters controlling the damping and convergence.
As a physics context, we outline the $^{11}$Be $\rightarrow\,^{10}$Be $+ n$ breakup setup on a heavy target to motivate the structure of the DWBA amplitude. The results support VF as a reliable computational tool for breakup reaction modelling with long-range Coulomb interactions, relevant to analyses for experiments at RIBF and similar facilities.