Physics Commons^™

The Dissemination And Effective Use Of Physics Education Research In Undergraduate Instruction, Trevor Stefanick

Masters Theses

Based on the results of a national survey of physics faculty, a set of interviews was conducted of 70 physics faculty from a diverse set of institutions. The interviews included questions about the dissemination and effective use of curricula and instructional strategies based on Physics Education Research (PER), focused to obtain recommendations to the PER community that might help to spread the use of these PER-based materials. Approximately half of the interviews (those with faculty who indicated knowledge about or use of Peer Instruction) have been previously analyzed. This project is the analysis of the 38 interviews that were conducted …

The Variation Of Hydrogen Concentration In Ni/Mgh Thin Film With Temperature, Rex Nyadaufe Taibu

Masters Theses

The thermal stability of Ni/MgH thin film deposited on Si substrate by Unbalanced Magnetron Physical Vapor Deposition has been investigated using Ion Beam analysis (DBA) techniques. Rutherford Backscattering Spectrometry (RBS) and Non-Rutherford Backscattering Spectrometry (NRBS) have been used to find the composition of Magnesium, Nickel and Oxygen. Elastic Recoil Detection Analysis (ERDA) has been used to determine the concentration of hydrogen at each level of heating. Heating was done in the Ultra High Vacuum (UHV) environment using a non gassy button heater. Ni/MgH sample had lost most of its hydrogen after being heated to a temperature of about 125°C in …

An Application Of Optical Tweezers, Patrick W. Swanson

Masters Theses

Oxycyte is a perfluorocarbon-based material that can mimic the oxygen carrying capabilities of hemoglobin and is in the testing stages of acting for use as a blood substitute. However, a problem associated with using Oxycyte as a blood substitute is that it clumps together too easily and does not coagulate. An approach for studying the problem uses optical tweezers to help model the forces between Oxycyte particles. Elements of optical tweezers, including laser beams, microscopes, and operation by trapping particles with light will be outlined. An experimental system created to study the forces between particles is presented. Experimental issues and …

Novel Transparent Conductive Materials: Understanding And Prediction, Yaou Song

Masters Theses

"Transparent conductive oxides (TCOs) such as doped In₂O₃, ZnO, SnO₂ or CdO are highly attractive due to their special properties, which are electrical conductivity and optical transparency. The lack of complete understanding of the fundamentals behind this unique phenomena and rapidly increasing commercial demand draw a lot of interest in investigating this kind of materials. More efficient, environmentally friendly and less expensive transparent conductive materials are needed for a variety of applications, and a general understanding of the origins of the unusual behavior would help further search for potential transparent conductive (TC) candidates. Understanding the basic properties of conventional TCOs …

The Influence Of Taking High School Physics As [A] Junior On Act Science Scores, Bartholomew T. Frey

Masters Theses

In recent years, policymakers, parents, and business leaders have expressed concern about the lack of student success on standardized tests in science. While the consensus is that the problem needs to be addressed, there is little agreement about how to achieve the increased test scores. This study examines the role of the specific science sequencing of biology, chemistry and physics completed by the junior year and increased ACT science test scores. This study compared the achievement of students who took physics as a junior with students who took physics as a senior on the ACT science test. This study continued …

The Physics Of Electron Degenerate Matter In White Dwarf Stars, Subramanian Vilayur Ganapathy

Masters Theses

White dwarfs are the remnant cores of medium and low mass stars with initial mass less than 8 times the mass of our sun. As the aging giant star expels its surface layers as planetary nebulae, the core is exposed as a white dwarf progenitor. The density of matter in white dwarfs is so high that thermal or radiation pressure no longer supports the star against the relentless pull of gravity. The white dwarf is supported by a new kind of pressure known as the degeneracy pressure, which is forced on the electrons by the laws of quantum mechanics. The …

The Effect Of A Skyrme Interaction On Nucleon Induced Reactions, Yingfa Zhang

Masters Theses

The main goal of this Master thesis is the theoretical study of the interaction between a nucleon and a nucleus. This is a fundamental method to study the structure and dynamics of nuclear systems. This thesis concentrates on the study of nucleon scattering on light nuclei, ⁶Li, ⁷Li and ¹⁴N, with the effective interaction M3Y and its modification by adding a Skyrme force. This is the first time the Skyrme interaction has been employed in scattering calculations. From a comparison of the measured differential cross section σ (θ) and the analyzing power Ay (θ) for ⁶Li …

Resonant And Non-Resonant Inelastic X-Ray Scattering Of Copper Phthalocyanine, Michelle Deleene Tuel-Benckendorf

Masters Theses

With the ever-changing demands of technology and the desire to use new materials to replace the old, researchers have the job to not only find alternative materials, but also understand their properties. There continues to be extensive research in the properties of organic semiconductors, for use in many microelectronic applications. There is very little known about the excitation properties of these materials. For my research, I have chosen to study the electronic excitations of copper phthalocyanine (CuPc), one specific organic semiconductor. To do this, we used resonant and non-resonant inelastic x-ray scattering to measure the evolution of excitations as a …

Electrical Conductivity Measurements Of Lithium-Ammonia Solutions, Mariana Constantin Barbu

Masters Theses

The topic covered in this thesis is the study of electronic interactions for liquid metal-ammonia solutions, lithium-ammonia solutions in particular. To obtain a theoretical understanding of so-called correlated electron systems.

The work focuses on sample creation and measurement of electrical conductivity of lithium-ammonia solutions varying with temperature for different concentrations. We have taken measurements in liquid lithium-ammonia mixtures using four-wire method to minimize the contact resistance. We have shown how it is possible to carry out accurate measurements of the electrical conductivity in these systems with the four wire measurements.

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 …

Control And Data Acquisition For An Electron Spectrometer System, Stanislav Rumega

Masters Theses

An electron spectrometer system, installed on one of the beam lines in the WMU Van de Graaff accelerator laboratory, consists of two 45^o parallel-plate electrostatic analyzers, a decelerating grid, and a channeltron. It allows the energy analysis, angular analysis, and the detection of continuum electrons ejected following the bombardment of a target with accelerated ions or electrons. First, the principles of operation of the spectrometer itself are discussed with emphasis on the energy analysis. Next, the electronics and computer interfacing required for control of the spectrometer functions and for acquisition of data are described. Finally, the control and data …

A Large Scintillation Detector For Nuclear Physics Experiments At Indiana University Cyclotron Facility, Apurva Pathak

Masters Theses

A new, large, scintillation detector, called the "K" detector has been designed and built for use in a series of nuclear physics experiments being performed at the Indiana University Cyclotron Facility (IUCF). This project describes the design, construction and testing of this scintillation detector. The K detector was designed to augment an existing detector stack at IUCF, and will serve to increase the energy range of previous studies of neutral pion production in proton-proton collisions near threshold. The test data for the current project came from a proton-proton scattering experiment, during which several runs were carried out between the bombarding …

L-Shell Resonant Electron Transfer And Excitation In Cu18-19+ + H2 Collisions, Jeffrey A. Wroblewski

Masters Theses

Measurements of L-shell resonant electron transfer and excitation (RTE) were conducted for 45-72 MeV Cu^18-19+ (Na-like and Ne-like, respectively) ions colliding with H₂ using the Western Michigan University EN tandem Van de Graaff accelerator. The RTE process involves an electron-electron interaction between the projectile and the target where electron capture occurs simultaneously with projectile excitation. In previous measurements involving RTE with subsequent L x-ray relaxation for Nb^q+ (q=28-31) ions, the magnitudes of the RTE cross sections were found to be nearly a factor of two smaller than theory. In the analogous electron-ion process of dielectronic recombination, measurements …

Band Structure For Acoustic Waves Propagating In A Periodic Elastic Media And Impurity Modes Arising From Slab Substitutions, Abdur Rahman

Masters Theses

In this thesis I study the band structure for acoustic waves propagating in a one-dimensional elastic array which forms a periodic elastic system in which band gaps are opened in the frequency spectrum. Specifically, I study the single impurity problem in this system. An impurity is introduced in the system by replacing one of the acoustic slabs with a new slab of different acoustic medium or by changing the thickness of impurity slab. I study the very narrow (in frequency) impurity modes in the band gaps which are localized about the impurity sites. Then I study the frequency of impurity …

An Experimental Apparatus For Studying Differential Scattering Of Multiply-Charged Ions From Neutral Targets Following Capture, John Edward Edens

Masters Theses

An experimental apparatus has been designed, enabling measurement of angular differential cross sections for single-electron capture (SEC). The design consists of a microchannel plate detector with a one-dimensional position sensitive anode. A bow-time shaped aperture was employed to convert a radially scattered distribution into an approximate linear one. An electrostatic retarding grid was used to separate SEC contributions from the reaction products. Measurements were made of the angular differential cross sections for SEC of Ar^q+ (q=4-6,8) ions scattering from He and Ar at impact energies of 600 to 3000 eV and angles between 0 and 23 mrad. The experimental …

Determination Of The Bulk Modulus Of A Lennard-Jones Solid, Spencer A. Van Roekel

Masters Theses

The quantum Monte Carlo method is used to determine the bulk modulus of a Lennard-Jones solid. The quantum Monte Carlo method is discussed in detail and is compared with other numerical methods used previously.

The zero pressure bulk modulus of a Lennard-Jones solid is computed at a number of different temperatures and compared with experimental data.

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 …

The Photonic Band Structure Of Dielectric Systems With A Frequency Dependent Dielectric Function, Jiezhou Liu

Masters Theses

The concepts of band theory for electrons can be employed to describe the behavior of electromagnetic waves propagaiting in periodic dielectric structures with a frequency independent dielectric function. These periodic structures can produce photonic band gaps in which the propagation of electromagnetic waves is strictly prohibited. The introduction of a frequency dependent dielectric function in such systems gives rise to strong changes of the photonic bands in the neighborhood of the frequency resonance of the dielectric function.

In my thesis, the photonic band structure of a dielectric system with a frequency dependent dielectric function which undergoes a dielectric resonance will …

A Procedure For G-Matrix Calculation From A Momentum Space Potential, Zhaohui Gao Busche

Masters Theses

In this work a numerical procedure was found to calculate the G-matrix in momentum space with a momentum space potential. The integral equation for the G-matrix was solved by conversion to a matrix equation. Two numerical integral methods, three-point Simpson method and Gaussian integral method, were employed in this process to determine the more efficient method.

The resulting G-matrix in momentum space was Fourier transformed into coordinate space. This was compared with the results of the G-matrix calculated from coordinate space directly as well as the results from solving the Bethe-Goldstone equation. A 2% accuracy was achieved with both the …

Laser-Rf Double Resonance Measurements Of The Hyperfine Structure Of V Ii, Gregory Michael Matous

Masters Theses

We have measured the hyperfine structure of ⁵¹V II using the technique of collinear fast-ion-beam laser spectroscopy. The output of a dye laser was applied collinearly to an accelerated 50 ke V ion beam to produce laser induced fluorescence spectra for the metastable 3d³4s and 3d⁴ configurations. The technique of laserradio- frequency double resonance, which utilizes an optical photon to deplete a hyperfine state and an rf photon to repopulate the state, was used to measure the hyperfine intervals to a high precision. These measurements of the hyperfine intervals allowed the determination of the magnetic …

Size Imperfections In One-Dimensional Periodic Optical Arrays, Yan Zhong

Masters Theses

The concepts of band theory for electrons can also be employed to describe the behavior of electromagnetic waves propagating in periodic dielectric structures. These periodic structures can produce photonic band gaps in which the propagation of electromagnetic waves is strictly prohibited. The introduction of impurities in such system gives rise to donor and acceptor gap modes in electron system and to energy gap modes in photonic system.

In my thesis, the impurity modes in one-dimensional, periodic, dielectric system will be studied. These modes are introduced in the 1-d dielectric structure by altering the thickness of one slab in an otherwise …

Enhanced Retroreflection Of Light From Rough Metal Surfaces, Sivakumar Natarajan

Masters Theses

The optical constants n and k measured by Johnson and Christy (1972) for the noble metals (gold, silver and copper) are used to analyze the relationship between the surface characteristics and the peak height and half-width of the backscattering peak which is observed in the angular distribution of the intensity of diffusely reflected light at a vacuum-metal interface in a direction antiparallel to the original incident beam. Surfaces with surface roughness of heights less than 200 A to 300 A will be considered and a recently developed perturbation treatment will be used in these studies.

The backscattering of light from …

Non-Resonant Transfer And Excitation For S^13+ Projectiles Colliding With Neutral Gas Targets, Liang Duo

Masters Theses

Non-resonant Transfer and Excitation (NTE) by 20-70 Mev S,3+ projectiles in collisions with neutral gas targets of He, Ne and Ar is investigated. For NTE, positively charged projectiles undergo excitation and electron capture in a single collision in which the capture and excitation processes are independent events. The mechanisms involved in the NTE process are electron-nucleus interactions, and the combination of projectile excitation and capture is a two-step process. In this work, NTE cross sections, along with total K x-ray production cross sections and total single-electron capture and loss cross sections, were measured as a function of projectile energy. The …

Impurity Modes In Photonic Band Structures, Yi-Fen Chang

Masters Theses

In this thesis I study a theoretical model of one-dimensional dielectric array (a layered system of dielectric slabs) which forms a periodic dielectric system in which band gaps are opened in the frequency spectrum. Specifically, we study such a one-dimensional array with linear impurities introduced in the periodic dielectric system. In these impurity structures narrow resonant modes are found in the band gaps as impurity modes and these impurity modes change with the dielectric constant. This impurity problem is similar to the donor and acceptor state problem in electronic semiconductors. The calculations presented in this thesis are based on numerically …

A Study Of The Transfer Matrix Method For The Classical Statistical Mechanics Of One Dimensional Systems, Dietmar R.A. Johlen

Masters Theses

Two formalisms using the transfer matrix technique, the first one by Gupta and Sutherland (1976) and the second one by Guyer and Miller (1979), are investigated and a proof is given for their equivalence.

Furthermore, it is pointed out that previous studies neglected the difficulties that arise from nonhermitian pseudo Hamiltonian. This work proves that the same results are obtained by taking into account the nonhermiticity of the pseudo Hamiltonian.

Thus, the transfer integral technique is extended to nonhermitian pseudo Hamiltonians.

Localization Of Light In One Dimensional Randomly Disordered Dielectric Medium, K. Balaji

Masters Theses

The concept of localization of electrons in semiconductors has been known ever since the 1960's when P. W. Anderson and N. F. Mott made detail investigations on the transport properties of alloys. At the end of the last decade, however, physicist started looking for localization in other systems. Specifically, they looked at the localization of light and acoustic waves in disordered systems. Localization is a property which arises for all wavelike excitations in disordered media.

In this study we analyze the localization of light in one dimensional randomly disordered dielectric medium using computer simulation (numerical integration method) technique. The results …

Charge Conservation In The Incommensurate-Commensurate Transition Of Charge Density Waves, Jörg Kastrup

Masters Theses

W ith the complex continuation method, introduced by Gupta and Sutherland (1976), the grand partition function for the sine-Gordon model of charge density waves may be calculated without violation of charge conservation. Contrary to previous works by Okwamoto, Takayama and Shiba (1979) and Turkevich and Doniach (1982) the chemical potential becomes temperature dependent. By direct comparison of numerical results with those of the above mentioned authors it is shown that the incommensurate-commensurate transition does not occur in the previously predicted temperature range.

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 …

Double Differential Cross Sections For State-Selective Electron Capture By Low-Energy Ar4+ And Ar5+ Ions From He And Ar, Serefettin Yaltkaya

Masters Theses

Doubly differential cross sections, in angle and energy, for state-selective single-electron capture from He and Ar by Ar⁴⁺ and Ar⁵⁺ ions have been studied experimentally at laboratory impact energies of 25q, 50q, and lOOq eV (q = 4 and 5, where q is the ion charge state) and at laboratory scattering angles between 0° and 5.5°, by means of translational energy spectroscopy. The translational energy-gain spectra show that only a few final states are selectively populated. Final-state transition probabilities were found to depend strongly on the charge state of the projectile ion and the ionization potential of the …

Prediction Of Paper Color: A Process Simulation Approach, Mayank Chaturvedi

Masters Theses

A simulation model was developed for a dye mixing process and for the prediction of the optical properties of the paper. The model was integrated with the MAPPS (Modular Analysis of Pulp and Paper Systems) simulation software package. The model was validated using dyed handsheets made in a laboratory and dyed paper made on a pilot papermachine. Validation comprised of prediction of the optical properties of the handsheets and the machine-made paper which contained various combinations of three non-fluorescent dyes. Sheet reflectances were predicted at 20 nanometer intervals for discrete light wavelength range of 400 to 700 nanometers and verified …