Physics Commons^™

Simulating Strongly Coupled Many-Body Systems With Quantum Algorithms, Manqoba Qedindaba Hlatshwayo

Dissertations

The complexity of the nuclear many-body problem is a severe obstacle to finding a general and accurate numerical approach needed to simulate medium-mass and heavy nuclei. Even with the advent of exascale classical computing, the impediment of exponential growth of the Hilbert space renders the problem intractable for most classical calculations. In the last few years, quantum algorithms have become an attractive alternative for practitioners because quantum computers are more efficient in simulating quantum physics than classical computers. While a fully fault-tolerant universal quantum computer will not be realized soon, this dissertation explores quantum algorithms for simulating nuclear physics suitable …

Studying The Synthesis Of 196Hg At Astrophysically Relevant Energies Through The Measurement Of Capture Reaction Cross-Sections Of (P, Γ) (P, N) And (P, Α) Reactions, Khushi Bhatt

Dissertations

Understanding the origin of all the chemical elements is an important question for the nuclear-astrophysics community. There are many unanswered questions like: What astrophysical events are responsible for the synthesis of what particular chemical elements? How many different elements were made in total? What is the abundance of each synthesized element? etc. Currently, scientists are largely depending upon theory and simulations to define nuclear and astrophysical reaction. This makes it critical to have accurate experimental nuclear physics data to input in astrophysical theoretical models. However, out of more than 20000 reactions involved in these calculations, only a very few are …

Probing The Equation Of State Of Neutron Stars With Heavy Ion Collisions, Om Bhadra Khanal

Dissertations

The equation of state (EOS) is a fundamental property of nuclear matter, important for studying the structure of systems as diverse as the atomic nucleus and the neutron star. Nuclear reactions, especially heavy-ion collisions in the laboratories, can produce the nuclear matter similar to those contained in neutron stars. The density and the momentum dependence of the EOS of asymmetric nuclear matter, especially the symmetry energy term, is widely unconstrained. Finding appropriate constrains, especially at higher densities of the nuclear matter, requires the development of new devices, new experimental measurements as well as advances in theoretical understanding of nuclear collisions …

Dielectronic Recombination Calculations For Silicon-Like Ions And The S2+ Orion Nebula Abundance Conundrum, Jagjit Kaur

Dissertations

Modern astronomical spectroscopy and imaging data are of an unprecedented quality, and span the full electromagnetic spectrum. To take full advantage of these data and successfully model the physical conditions in and elemental abundances of astrophysical plasmas, an accurate and complete description of relevant atomic processes occurring in a wide range of cosmic environments is required. The primary focus of this project is to investigate one of the atomic processes, dielectronic recombination (DR), for the entire silicon-like isoelectronic sequence. Dielectronic recombination is generally the most important contribution to the total recombination rate of atomic ions. This study will serve as …

Time-Dependent Photoionization Of Gaseous Nebulae, Ehab Elsayed Elhoussieny Ahmed

Dissertations

We study time-dependent photoionization of gaseous nebulae, i.e. the physical conditions and spectra of astronomical plasmas photoionized by a time-dependent source of ionizing radiation. Our study proceeds in two chief steps: First, we start with a simplified model of plasmas of pure H. Second, we develop a more realistic model of plasmas composed of a mixture of chemical elements. For the first step, we wrote a time-dependent photoionization code (TDP) that solves the coupled system of equations for ionization, energy balance, and radiation transfer in their full time-dependent forms For the second step, we developed a more realistic code (TDXSTAR) …

Electron Transmission Through Micrometer Sized Funnelshaped Tapered Glass Capillaries And Electron Micro-Beam Production, Samanthi Jayamini Wickramarachchi

Dissertations

The prime motivation of this work is to understand the fundamental transmission process of an electron beam through a funnel-shaped capillary taking into account its shape together with the energy, angular and time dependence of the transmitted electrons produce a microsized electron beam. The utilized capillaries had inlet/outlet diameters of 800/16 μm, 800/100 μm and lengths of 35 mm. Considerable transmission of 800 and 1000 eV electrons for tilt angles up to 1.5^o and only small transmission for 500 eV electrons was observed for the capillary with the smaller outlet diameter of 16 μm. Incident electrons with energies of …

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 …

Modeling Transmission Of Photonic Crystal Waveguide Modes Enhanced By Kerr Nonlinearity, Buddhi M. Rai

Dissertations

Nonlinear modes of electromagnetic fields propagating in photonic crystal systems have been studied by implementing various computer simulation techniques using electromagnetic theory. The fundamentals of simulation of photonic crystals are analyzed using general purpose methodologies such as the FDTD or PWE methods. Information derived from the underlying physical insights into the systems could be utilized to describe the control mechanisms over the propagation of the modes around impurities in the photonic crystal lattice. The impurities trap the resonantly localized electromagnetic modes having a frequency in a stop band of the photonic crystal, suggesting novel optical controls in the photonic crystal …

Study Of The Structure Of 9C Via Single Neutron Transfer, Scott T. Marley

Dissertations

This thesis describes a study of the nucleus ⁹C, produced in the single-neutron transfer reaction d(¹⁰C, t) ⁹C using a radioactive ¹⁰C beam. The structure of the neutron-deficient nucleus ⁹C is poorly known. Only a few excited states have been observed and no information exists of their single-particle characteristics. The measured ground-state magnetic dipole moment of ⁹C is anomalously small and could imply large contributions from sd-shell orbitals in the ground-state wave function. The positions of the ⁹C excited states and their single-particle properties are vital to furthering the …

Electron Transmission Characteristics And The Production Of Narrow Beams Using Glass Optics, Buddhika Senarath Dassanayake

Dissertations

Transmission of electrons through an insulating single cylindrically-shaped glass capillary of microscopic dimension has been investigated. Samples made with Borosilicate glass (PYREX 7740) were subjected to bombardment of 300-1000 eV electrons. Transmitted electrons were analyzed using a parallel-plate spectrometer coupled to a channel electron multiplier.

The transmitted electron intensity was found to decrease with increasing sample tilt angle relative to the direction of the primary beam. Two regions of transmission were found: direct where there is no interaction of the beam with the inner capillary wall, and indirect where the beam does interact with the wall. The rate of transmission …

Oxidation Resistance Studies Of Crain Coatings On 430 Stainless Steel, Kurtis Wickey

Honors Theses

The requirements of low cost and high-cost temperature corrosion resistance for interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. We have investigated the performance of stainless steel plates with homogenous coatings of CrAIN. The coatings were deposited using RF magnetron sputtering, with Ar as a sputtering gas and N as reactive gas. The Cr/A1 composition ratio in the coatings was varied in a combinatorial approach. The coatings were subsequently annealed in air for up to 25 hours at 800°C. The composition of the coated plates and the …

Inelastic X-Ray Scattering Studies In Lithium And Metal Ammonia Solutions, Ayman Hasan Said

Dissertations

In this work, inelastic x-ray scattering was used to measure the ionic collective excitations of a metal-ammonia system and the atomic form factor of lithium in a single crystal. For lithium and sodium ammonia systems, the measurements were carried out for different metal concentrations (lithium-ammonia with 2 0 , 16, and 13 mole percent metal [MPM] at T'=240K and sodium-ammonia with 18, 14, and 10 MPM at T=222K). These data were analyzed to determine the acoustic collective excitation dispersion relation and the linewidth. Deviations from the Bohm-Staver model for electron-ion coupling are discussed for the low electronic densities. For the …

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 …

Electron Correlation Leading To Double-K-Shell Vacancy Production In Li-Like Ions Colliding With Helium, Ali Sami Alnaser

Dissertations

Single and double K-shell vacancies in Li-like ions colliding with neutral helium target have been investigated using high-resolution Auger projectile spectroscopy. Be⁺, B²⁺, C³⁺, and O⁵⁺ Li-like ions were produced and accelerated to intermediate-to-high collision velocities where perturbative models are expected to be valid, using the Tandem Van de Graaff accelerator at Western Michigan University. Double-K-shell vacancies in atomic systems or so-called “ hollow ions” can be induced by different mechanism in ion-atom collisions. For intermediate-to-high velocity collisions where the collision time is small, the projectile ion can interact with only one of …

Electron Emission Following The Interaction Of Slow Highly Charged Ions With Solids, Joseph W. Mcdonald

Dissertations

The interaction of highly-charged ions with surfaces involves many excitation processes of the surface atoms and the bulk material. One such process, the emission of electrons from surfaces due to the potential energy of the incident ions has been studied. The experimental results presented here confirm that the majority of electrons emitted as a result of highly-charged ions interacting with a solid surface have energies of about 20 eV. Auger processes contribute a smaller fraction of the total emitted electrons with increasing Z o f the projectile. This contribution to the total electron emission yield is found to be less …

Angle-Resolved Study Of Ar 2p₁/₂,₃/₂⁻1Ns,D Resonant Auger Decay, Marc Andrew Humphrey

Honors Theses

Angle-resolved measurements of the Ar 2p_1/2,3/2^-14s,3d,4d and 2p_3/2^-14s,3d,4d resonant Auger transitions have been carried out using photons from an undulator beamline at the Advanced Light Source of Lawrence Berkeley National Laboratory. The intensity distributions and angular distribution anisotropy (β) parameters have been reported for nearly all of the possible 3p⁴nl final ionic states. These results further verify the predictions of the spectator model for the 2p_1/2,3/2^-14s resonances and the subsequent breakdown of this model for the 2p_1/2,3/2^-13d and 2p_1/2,3/2^-14d relative intensities. This work …

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 …

Design And Construction Of A Lithium Vapor Oven, Corey A. Leon

Honors Theses

A lithium vapor oven to be used as a source of lithium target atoms in atomic collision experiments was designed and constructed. The oven was installed in the beamline of the Van de Graaff accelerator at Western Michigan University. Test results indicated the oven produced a diffuse cloud of evaporated lithium instead of the intended concentrated jet spray. Recommendations concerning the design are made for future efforts.

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 …

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 …

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 …

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 …

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.