Doctoral Dissertations

Madhav Dhital

Keywords and Phrases

Few-body problem; Fully-differential study; Higher-order contributions; Ionization of H2 and He; Post-collision Interaction; Velocity-matching

Abstract

”Advancing our understanding of the few-body dynamics in simple atomic systems is one of the most important goals of atomic scattering research. In perturbation theory, this goal entails accurately describing the relative contributions from first versus higher-order mechanisms. One higher-order mechanism that is particularly important for target ionization by a charged-particle impact is known as post-collision interaction (PCI). There, the projectile and the ejected electron interact with each other at least twice. In the first interaction, the projectile transfers sufficient energy for the electron to be lifted to the continuum. The second interaction occurs in the outgoing part of the collision, where the projectile and the electron attract each other towards the initial beam axis. It is well known that PCI maximizes when the electrons are ejected with a speed close to that of the projectiles. However, a systematic study on a fully differential level of ionization by ion impact was lacking for this kinematic regime. Kinematically complete experiments on ionization of H2 and He by 75 keV proton impact were performed. Fully differential cross sections (FDCS) were extracted for a broad range of fixed electron energies for each of the targets. Pronounced post-collisional effects between the projectile and the ejected electrons were observed. The results were compared with two conceptually similar calculations, both based on distorted wave approaches. Surprising discrepancies were observed between the experimental data and theory, and also between conceptually similar theoretical models. This shows that the FDCS are very sensitive to the details of the underlying few-body dynamics in this region. Data also indicated the limitations of perturbative methods and the need for non-perturbative approaches”--Abstract, page iv.

Advisor(s)

Schulz, Michael, 1959-

Committee Member(s)

Madison, Don H.
Parris, Paul Ernest, 1954-
Fischer, Daniel
Madria, Sanjay Kumar

Department(s)

Physics

Degree Name

Ph. D. in Physics

Comments

This work was supported by the National Science Foundation under grant nos. PHY-1703109 and PHY-1505819.

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2020

Journal article titles appearing in thesis/dissertation

  • Few-body dynamics underlying postcollision effects in the ionization of H2 by 75-keV proton impact
  • Target dependence of postcollision interaction effects on fully differential ionization cross sections
  • Ejected-electron-energy and angular dependence of fully differential ionization cross sections in medium-velocity proton collisions with He and H2

Pagination

ix, 114 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2020 Madhav Dhital, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11781

Electronic OCLC #

1240361915

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