Doctoral Dissertations

Abstract

"Singly, doubly, and triply differential measurements of single and multiple ionization of Ar by 1 keV positron and electron impact have been measured for projectile energy losses from 0 to 200 eV, scattering angles of 0° to ±5°, and electron emission angles from 45° to 135°. For single ionization, both projectiles show similar overall energy loss distributions but differ with respect to varying scattering angles. Triply differential yields for the electron emission demonstrate the binary and recoil features but the lobes are distorted because of extraction field effects plus variations in grid transmission and solid angle as a function of the electron emission angle. Limited statistics and effects due to electric fields and solid angles mask observing definitive differences between positron and electron impact outside of error bars in the triply differential electron emission binary to recoil ratios. However clear differences in the magnitudes between positron and electron impact are observed. To study double ionization, ratios of double to single ionization, R2, were used. It was found that the doubly differential (DD) projectile and the singly differential (SD) electron emission ratios show differences in magnitude and intensity consistent with the expectations due to interference between a first order and a second order double ionization model. Triply differential (TD) electron emission double ionization ratios also exhibit a lower yield for positron impact, though the difference is much greater than that expected from interference effects"--Abstract, page iii.

Advisor(s)

DuBois, R. D. (Robert D.), 1951-

Committee Member(s)

Peacher, Jerry
Jean, Yanching J.
Schulz, Michael, 1959-
Hale, Barbara N.

Department(s)

Physics

Degree Name

Ph. D. in Physics

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2009

Pagination

ix, 83 pages

Note about bibliography

Includes bibliographical references (pages 78-82).

Rights

© 2009 Jared Martin Gavin, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

ArgonIonization of gasesPositrons

Thesis Number

T 9513

Print OCLC #

436170648

Electronic OCLC #

320113872

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