Four-Body Charge Transfer Processes in Proton-Helium Collisions*

Recent advancements in experimental techniques now allow for the study of fully differential cross sections for four body collisions. The simplest four-body problem is a charged particle collision with a helium atom in which both atomic electrons change state. This type of collision can result in many different outcomes, such as double excitation, excitation-ionization, double ionization, transfer-excitation, transfer-ionization, and double charge transfer. Theoretically fully differential cross sections will be presented and compared with absolute experimental data for transfer-excitation in proton helium collisions. The model used is a fully quantum mechanical, first order perturbative method that includes all relevant two particle interactions. Numerically, this requires a full nine-dimensional integral, and is quite computationally expensive. The role of different scattering mechanism will be discussed.