Atomic, Molecular and Optical Physics Commons^™

Electron Capture By Multiply Charged Ions From Molecular Targets, Justin Harris

Masters Theses

State-selective differential cross sections for single-electron capture processes in collisions of Ne^q+ (q=2, 3, 5) ions with H₂O and CO₂ have been studied experimentally at laboratory collisions energies between 45 and 250 eV, and at scattering angles between 0^o and 7:20^o by means of translational energy-gain spectroscopy technique. The translational energy spectra show that only a few final states are populated depending on the projectile's charge state, laboratory scattering angle, and the collision energy. In addition, these measurements show that the dominant reaction channels are due to non-dissociative electron capture into excited states of …

Theoretical Modeling Of Near-Threshold Shape Resonance Behaviour In Photodetachment Experiments, Laurentiu Dan Dumitriu

Masters Theses

This thesis attempts to better understand the results obtained from photodetachment experiments of Fe-, made by the Western Michigan University experimental atomic physics group at the Advanced Light Source (ALS), Lawrence Berkeley National laboratory.

After a relevant description of the quantum mechanics and theoretical atomic physics concepts and formulas involved in this subject, a physically realistic model, based on the square well potential, is developed. Based on this model, the theoretical photodetachment cross section is computed in order to reproduce the qualitative behavior of the experimental photodetachment cross section measured at ALS.

This development, involving programming in Fortran and numerical …

Optical Solitons In A Three-State Medium, Talal Ghannam

Masters Theses

When a beam of light propagates within a typical medium, absorption is a common phenomenon. This happens when the frequency of the light is close to a resonant frequency of the atoms composing the medium. But in the past few decades, it has been shown that in certain circumstances, carefully chosen pulse shapes are able to propagate without significant absorption even when the frequency of the light is close to an atomic resonant frequency. It was called Self Induced Transparency (SIT).

This phenomenon was intensively studied in the two-state systems. On the other hand, the three-state systems seems not to …

An Experimental Apparatus For Studying Double Differential Scattering By Low-Energy Multiply Charged Ions From Atomic Targets, Meenatchi S. Gopinathan

Masters Theses

A new differential energy-gain spectrometer with a movable parallel-plate electrostatic energy analyzer has been constructed and tested for the study of double differential (in energy and angle) cross sections for state-selective electron capture processes in collisions of low-energy multiply charged ions with atomic gases. The ion beam is produced by extracting recoil ions from a primary interaction region where these ions are generated in collisions between a neutral target gas and a fast fluorine beam from the WMU tandem Van de Graaff accelerator. An einzel lens is used to focus the ion beam extracted from the recoil-ion source into a …

Construction Of A Lithium Vapor Oven For Electron Capture And Multiple Ionization Experiments, Oliver Woitke

Masters Theses

A Li vapor oven, to be used as a source of Li target atoms in electron capture and multiple ionization experiments, was designed and installed in the beamline of the Van de Graaff accelerator at Western Michigan University. The oven was tested using two different projectile beams, protons and He+. The test results indicate that Li evaporated from the oven in the form of a cloud rather than as a jet spray. For He+ colliding with Li it was found that the projectile single-electron loss yield is about three orders of magnitude larger than the single-electron capture yield, as expected …

Resonant Electron Transfer And K-Shell Excitation Of Lithiumlike Projectiles In Collisions With Molecular Hydrogen, M. Anwar Kamal

Masters Theses

An experimental investigation of resonant transfer and excitation (RTE) for collisions of Mg⁹⁺ (lithiumlike) projectile ions with a molecular hydrogen gas target has been made. The experimental cross sections for projectile K-shell x rays coincident with electron capture in the energy of 33- to 60-MeV are found to be in good agreement with theoretical RTE calculations. The present results confirm the agreement between experiment and theory which has been reported for RTE involving K-shell excitation for projectiles with atomic numbers between 9 and 92 incident on H₂ and He targets.

Cross sections for total K-shell x-ray production and …

Double Ionization Of Helium By Intermediate To High Velocity He+ Projectiles, Jun Forest

Masters Theses

Ionization of helium target atoms by He⁺ projectiles colliding with helium at energies of 0.125 to 3.0 MeV/u is investigated. Cross sections for single and double ionization, and ratios o f double-to-single ionization are determined for each outgoing projectile charge state, and are compared to previous studies. For the lowest energies investigated, the ratios are consistent with the two-step mechanism in which the projectile interacts separately with each target electron. At the highest energies, the ratios reach nearly constant values indicating approach to the high velocity limit. At these high energies, however, the ratios are all higher than the …

Resonant Electron Transfer And K-Shell Excitation Of FQ+ (Q=6,8) In Collisions With Neutral He And H2 Targets, Konstantinos E. Zaharakis

Masters Theses

Measurements of resonant transfer and excitation (RTE) were conducted for 16.5-38 MeV F⁶⁺ (Li-like) ions colliding with H₂. In the RTE process electron capture and projectile excitation take place simultaneously due to the electronelectron interaction. In previous work, for the same collision system, at the Oak Ridge National Laboratory (Oak Ridge, TN) , the magnitude of the measured RTE cross sections was found to be nearly a factor of two smaller than theory. In order to investigate RTE in F⁶⁺ H₂ collisions more completely, we undertook measurements at Western Michigan University using the EN tandem …

Single-Electron Capture And Loss Cross Sections Vs. Target Z For 1 Mev/U Oxygen Ions Incident On Gases, Scott Avery Boman

Masters Theses

Cross sections for 1 MeV/u oxygen projectile ions which have gained or lost an electron after passing through a gas target were measured as a function of target Z for several incident projectile charge states. The targets used were D_2, He, Ne, Ar and Kr, and the projectiles had charges of 5+, 6+, 7+ and 8+.

The electron capture measurements are generally in reasonable agreement with existing theoretical and empirical scaling rules. The electron loss cross sections differ appreciably from predictions of the PWBA, particularly for the heaviest targets studied. Empirical scaling relationships are derived for the present capture …

A Study Of Ion Implanted Silicon Using Rutherford Backscattering Spectroscopy With Ion Channeling, Thomas J. Pollock

Masters Theses

Rutherford Backscattering Spectroscopy with channeling is the only nondestructive method for analyzing crystals which have been ion implanted. An RBS with channeling procedure has been established at the Accelerator Lab of Western Michigan University. It utilizes a tandem Van de Graaff accelerator for an incident helium beam, a goniometer for crystal alignment, and a computer for experimental control and data aquisition. State of the art measurements can be made with accuracies comparable to other labs. Specifically, ion implanted silicon was studied wherein crystal damage due to implanting was found to vary directly with implanting energy and fluence and was also …

The Impeachment And Trial Of Secretary Of War William Worth Belknap, Duane Edward Holthof

Masters Theses

The purpose of this thesis is to give an account of the events which lead to the resignation of Secretary of War William Worth Belknap in 1876, to examine the circumstances surrounding his impeachment, and to study the testimony in his Senate trial.

Although Belknap was not convicted on charges of accepting bribes, most of those senators who voted to acquit him did so on the technical ground that the Senate lacked the jurisdiction to try a private citizen. The evidence in the case clearly indicated Belknap's involvement, and there seems little doubt that if Belknap did not know what …

Construction And Testing Of A New Atomic Physics Beam Line At The Western Michigan University Accelerator Laboratory, William Andrew Hollerman

Masters Theses

A new beam line containing a differentially-pumped gas cell and charge state analyzing magnet was constructed for the purpose of measuring a wide variety of atomic inner-shell processes, such as excitation, ionization, and charge transfer. The completed system will be able to measure these individual atomic processes using coincidence techniques. Initial testing of the beam line was performed using 40MeV S⁺⁷+Ar collisions to determine the effect of the collimating slit size on the measured x-ray cross sections. These measurements showed that the slip size on the measured x-ray cross sections. These measurements showed that the slit size affects …

Non-Equilibrium L-Shell Effects On K-Shell X Rays For 20-54 Mev S+C Collisions, Donald Solon Shippy

Masters Theses

Projectile K x-ray yields have been measured as a function of target thickness (2.0-150 μg/ cm²⁾ for 20-54 MeV S^q+ ions incident on this carbon foils using the WMU EN tandem Van de Graaff accelerator. The measured K x-ray yields were fond to increase for thicknesses < 15 μg/cm² and decease for thicknesses > 15 μg/cm² . The increasing yield is attributed to L-Shell non-equilibrium as the ion traverses the foil, while the decreasing yield is attributed to K-shell non-equilibrium. Analysis of the data was performed by modifying the "two-component" model of Betz et al. to include the effect of …

A Laser Interferometric Study Of Electric Field Effects On Methane-Oxygen Flame Plasmas, Mark D. Prairie

Masters Theses

A laser interferometer is developed to study the refractive index field, aerodynamic structure, and three dimensional temperature profile of a methane-oxygen flame system under the influence of D.C. electric fields. A combined graphical-numerical method is used to transform the observed interference patterns into radial temperature distributions. The results indicate that the electric field exerts a marked influence on the flame stability, geometry, and charged particle flow. Experimental evidence shows that these effects are most apparent under fuel rich conditions. It is suggested an electric field may change the concentration gradients of reacting species, leading to an altered course of fuel …

Detector Geometry For Cascade Photon Experiments, Roger Minoru Munechika

Masters Theses

An observation of cascading optical photons can be used to determine an absolute excitation cross section for the intermediate state without the need of standard lamp calibration. In order to reduce the data an angular correlation function and an angular distribution function must be known. These functions depend on the alignment of the upper excited state and the polarization of the light emitted in the lower part of the cascade. However, at certain angles of observation the values of the required functions are known regardless of the alignment or polarization. A computer search is done to find these angles for …

A Study Of The Target Thickness Effect For Chlorine On Germanium From 25 To 49.5 Mev, James Robert Slusser

Masters Theses

No abstract provided.

Development Of A System For Water Quality Analysis Using Particle Induced X-Ray Emission, James Albert Andrus

Masters Theses

Particle induced x-ray emission (PIXE) has been in use for several years at Western's accelerator laboratory. Its primary purpose has been to provide trace element analysis of various types of solid samples. The analysis of water samples has not been done because of problems involving target preparation for the accelerator. A process called vapor filtration, developed at Purdue University, allows adequate sample preparation for the accelerator. This process is being adapted for use here at WMU. When completely operational, this system will give the WMU accelerator program the additional capability of performing water quality analyses to concentrations of parts per …

Analysis Of Chert By Particle Induced X-Ray Emission, Jeanette E. Gibeson

Masters Theses

No abstract provided.

Method Of Variational Secular Equation For The Ground State Of Helium Atom, Mih-Seh Kong

Masters Theses

No abstract provided.

The Construction Of Two Light Sources With Adequate Intensity For Magneto-Optical Rotatory Dispersion Experiments, Norman D. Love

Masters Theses

Chapter I

Introduction

The phenomenon known as the Faraday Effect was discovered by Michael Faraday in the year 1845.¹ He discovered that when an isotropic substance of high refractive index is placed in a strong magnetic field which is parallel to a beam of plane polarized light, the plane of polarization is rotated. The rotation is proportional to H, the strength of the magnetic field; and to 1, the length of the light path in the sample. If X represents the rotation in minutes then

X = VH1.

The proportionality constant V is known as Verdet's constant. The units …