Close-Coupling R-Matrix Approach to Simulating Ion Atom Collisions for Accelerator Applications

We have used an R-matrix close coupling algorithm to calculate capture, ionization and excitation cross sections for 0.5 to 8.0 MeV K+ incident on argon and neon. These energies, ions and gasses are relevant to the High Current Experiment (HCX) at Lawrence Berkeley National Laboratory, where impact ionization of background gasses is a main source of contaminant electrons. The R-matrix close coupling algorithm is a semi-classical algorithm that uses quantum mechanics to describe the particle interactions and classical mechanics to describe the nuclei trajectories. We find for argon, ionization and capture cross sections are roughly equal and on the order of a few 10^-17cm². For neon, we find the cross section for ionization is a few 10^-16cm², while the cross section for capture is a few 10^-17cm².