RUI: Path Integral Approach to Ion-Impact Collisions

Board Of Trustees Of Illinois State University, Normal IL

Investigators

Abstract

The study of atomic collisions provides important information about one of the fundamental forces of nature. The results of atomic collisions research are widely used in fields such as plasma physics, astrophysics, biophysics, and many other areas. In addition to providing a better overall understanding of heavy-ion collisions, which is the principal focus of the effort, this work will bring a well-known technique from other areas of physics into atomic and molecular collisions research, and possibly lead to additional overlap and collaborations between the atomic collisions community and other related fields. Another important aspect of this project is the inclusion of undergraduate students in cutting-edge research. By participating in this project, students will gain valuable hands-on research experience through code development and data analysis. They will also present their results at regional and national conferences, which will hopefully give them a more global view of scientific research. The few-body problem is one of the most fundamental, unsolved problems in physics. When more than two particles interact through the Coulomb force, the dynamics of the system cannot be described exactly. As a result, theory must resort to approximations, and any discrepancies that result between theory and experiment must be a result of the approximations. A comparison of current theoretical models with recent experimental results reveals some striking limitations of the current models. In particular, the dynamics of collisions in which some of the collision fragments are found in a full 3-dimensional geometry is not understood. The underlying mechanism behind these 3-dimensional collisions is known to be a result of quantum mechanical effects, but current theories cannot accurately describe the collision dynamics. The objective of this project is to develop a novel quantum mechanical theoretical model for the study of ion-impact atomic collisions through the use of the path integral technique. The path integral method is a well-known technique used in other areas of physics, but has not been applied to the study of heavy-ion collisions. This particular technique will allow for the inclusion of important quantum mechanical interactions, as well as provide an intuitive understanding of particle trajectories during the collision. The technical details of the project include the development of a computational model using the path integral method for ionization and capture processes with heavy-ion projectiles. The method will utilize an expansion of the Lagrangian around the classical path, where the deviation from the classical path represents the quantum fluctuations of the particle. For electron capture collisions, the role of the projectile-nuclear interaction and target electron correlation will be studied. Electron capture collisions with high projectile energy and large scattering angle will also be studied with the objective of better understanding the Thomas mechanism, and determining if possible diffraction effects exist in these collisions. For ionization processes, collisions in which the ejected electron is found outside of the scattering plane will be studied, with a focus on projectile-nuclear interactions and the role of close collisions between the projectile and the target nucleus.