Date of Award
Doctor of Philosophy (PhD)
The many-body problem refers to any physical problem made of more than two interacting particles. With increasing number of particles in a system, their coupling and entanglement becomes more complex, and there is no general analytic solution even for a three-body classical or quantum systems. However, some of the most fascinating phenomena in nature are products of collective effects. Therefore, significant efforts have been made in both experiment and theory to unravel some specific many-body problems. If we look at still unanswered physics questions we see that for most of these problems addressing the many-body interactions is a key issue. This field of research is very active, and with the theory relying on multiple approximations specific for the problem at hand, it has become one of the most computationally intensive areas of physics. In this work we address several many-body problems that are still puzzling the scientific community, using different theoretical and computational techniques:
1. Recent experiments in atomic physics considering the proton impact ionization of hydrogen revealed that experimental observations can not be explained with the available theoretical models, developed for more complex helium atom. We used the approximate solution for a three-body Coulomb system to calculate double differential cross sections for proton impact ionization of hydrogen atom, to describe the new experimental findings.
2. One of the central problems in the accelerator science is the interaction of a charged particle beam within itself and matter. Thus, it is crucial that we understand the collective effects governing the scattering of many particles in the bunch on multi center targets. We have developed the particle-particle computational code, based on classical scattering theory, which allows us to include close range interactions between the particles in the study of these many-body effects.
3. In this work we have also considered plasmas, which are manifestation of many-body collective effects. To study the formation of plasmoid-like object in supersonic flow microwave discharge, we have refined the tomographic diagnostic method, so we can take a glance inside this plasma object without disturbing it. The tomographic analysis provided us with spatial distributions of plasma constituents that we need for understanding of the collective-effects in its formation.
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"Case Studies in Many-Body Physics"
(2012). Doctor of Philosophy (PhD), Dissertation, Physics, Old Dominion University, DOI: 10.25777/maaq-cm05