Physics Commons^™

Magnetic Shielding Studies For The Neutron Electric Dipole Moment Experiment At The Spallation Neutron Source, Susan Kate Malkowski

Theses and Dissertations--Physics and Astronomy

The neutron Electric Dipole Moment Experiment at the Spallation Neutron Source requires an overall magnetic shielding factor of order 10⁵ to attenuate external background magnetic fields. At present, the shielding design includes an external (room-temperature) multi-layer μ-metal magnetic shield, a cryogenic (4 Kelvin) Pb superconducting shield, and a cryogenic (4 Kelvin) ferromagnetic shield composed of Metglas ribbon. This research determined how to construct a Metglas shield using minimal material that produced axial and transverse shielding factors of ~267 and ~1500. In addition, the μ-metal and Metglas shields were modeled using finite element analysis. The FEA model includes external coils …

Electrons Trajectories In Electromagnetically Pumped Free Electron Laser With A Constant Reverse Guide Magnetic Field, Ahmad Omar

Turkish Journal of Physics

An exact solution to the quartic equation in the wiggler frequency \omega_w, which represents the dispersion relation for this system, is obtained. The effects of the frequency of the wiggler \omega_w on the electron's velocities (v_{\vert \vert} and v_w) are investigated. The regions of interest for the allowed wiggler frequency \omega_w for both group I and group II electron trajectories are discussed.

Influence Of Doping And Heat Treatments On Carriers Mobility In Polycrystalline Silicon Thin Films For Photovoltaic Application, Beddiaf Zaidi, Bouzid Hadjoudja, Houda Felfli, Allaoua Chibani

Turkish Journal of Physics

In this work, we investigate the influence of doping as well as heat treatments on the mobility of the carriers in polycrystalline silicon layers. It was found that any increase in both parameters leads to an increase in the mobility of the carriers. Such mobilities were shown to be higher in boron doped layers that those doped with arsenic. Moreover, for strong arsenic doping, after the initial increase, we observed a saturation region followed by a final decrease of carrier mobility.

Characteristics Cd_{0.3}Sn_{0.7}Se Thin Films As Absorber Materials For Solar Cell Devices, Salma Mahdi Shaban, Raad Mohammad Saleh, Ahmed Saleh Ahmed

Turkish Journal of Physics

Cadmium Tin Selenide compound Cd_{0.3}Sn_{0.7}Se was prepared by direct reaction of high-purity elemental Cadmium, Tin and selenium. Cd_{0.3}Sn_{0.7}Se thin films were prepared on to well-cleaned glass substrates by vacuum thermal evaporation technique at room temperature of different thicknesses. The X-ray diffraction studies revealed that all the deposited films are amorphous in nature and exhibiting polycrystalline structure when are annealed at 348 K and 373 K. The crystallites were found to have a preferred orientation along the (111) direction. The analysis of its optical characteristics indicated the ability of these films to absorb the visible light due to its graded energy …

Dynamical Behavior Of Traveling Wave Solutions For The K(2,2) Equation, Lina Zhang

Turkish Journal of Physics

In this paper, we discuss the qualitative behavior of degenerate singular points for the K(2,2) equation. By analyzing the different dynamical behaviors of the singular system and its associated regular system, we come to the conclusion that for the singular system the smoothness property of its orbits, which have intersection point(s) with the singular straight line, will not be destroyed. Meanwhile, the corresponding smooth traveling wave solutions for the K(2,2) equation are obtained.

Hydromagnetic Thermal Boundary Layer Flow Of A Perfectly Conducting Fluid, Kalidas Das

Turkish Journal of Physics

Using successive approximation technique, an analysis of unsteady hydromagnetic boundary layer flow with thermal relaxation of perfectly conducting, viscous incompressible fluid past a semi-infinite porous plate in presence of heat absorbing sinks is carried out. The expression for velocity and temperature fields, local skin friction coefficient, local heat transfer coefficient etc have been derived when the free stream velocity exponentially depends on time. The effects of different parameters entering into the problem are shown graphically and discussed numerically.

Evanescent Wave Coupling Using Different Subwavelength Gratings For A Mems Accelerometer, Al-Aakhir A. Rogers

USF Tampa Graduate Theses and Dissertations

A novel technique of coupling near-field evanescent waves by means of variable period subwavelength gratings (1.2 ìm and 1.0 ìm), using a 1.55 ìm infrared semiconductor laser is presented for the use of an optical MEMS accelerometer. The subwavelength gratings were fabricated on both glass and silicon substrates respectively.

Optical simulation of the subwavelength gratings was carried out to obtain the maximum coupling efficiency of the two subwavelength gratings; the grating thickness, grating width, and the grating separation were optimized. This was performed for both silicon and glass substrates.

The simulations were used to determine the total system noise, including …

Comparative Imaging Study In Ultrasound Mri, Ct And Dsa Using A Multi-Modality Renal Artery Phantom, Deirdre King, Andrew Fagan, Carmel Moran, Jacinta Browne

Articles

A range of anatomically-realistic multi-modality renal artery phantoms consisting of vessels with varying degrees of stenosis was developed and evaluated using four imaging techniques currently used to detect renal artery stenosis (RAS). The spatial resolution required to visualize vascular geometry and the velocity detection performance required to adequately characterize blood flow in patients suffering from RAS is currently ill-defined, with the result that no one imaging modality has emerged as a gold standard technique for screening for this disease.

Methods: The phantoms, which contained a range of stenosis values (0, 30, 50, 70 and 85%), were designed for use with …

Dqtunepipe: A Set Of Python Tools For Ligo Detector Characterization, Brooke Anne Rankins

Electronic Theses and Dissertations

When LIGO's interferometers are in operation, many auxiliary data channels monitor and record the state of the instruments and surrounding environmental conditions. Analyzing these channels allows LIGO scientists to evaluate the quality of the data collected and veto data segments of poor quality. A set of scripts were built up in an ad hoc fashion, sometimes with limited documentation, to assist in this analysis. In this thesis, we present DQTunePipe , a set of Python modules to replace these scripts and aid in the detector characterization of the LIGO instruments. The use of Python makes the analysis method more compatible …

High Temperature And Pressure Resonant Ultrasound Spectroscopy Study Of Metal Hydride Systems, Rasheed Adebisi

Electronic Theses and Dissertations

The goal of this dissertation is to characterize the elastic properties of palladium hydride near the tri-critical point as a classic example of metal hydride systems using the resonant ultrasound spectroscopy. A high temperature and high pressure resonant ultrasound spectroscopy system which include the RUS cell and the direct contact transducer set-up was designed and constructed. The temperature and pressure dependent of elastic moduli of palladium hydride and palladium crystals were obtained at five isotherms near the critical temperature, 293 °C and for pressure range of 250–500 psi. A strong softening of the shear modulus was observed at temperature and …

Modeling Electric Fields In Support Of A Measurement Of The Neutron Electric Dipole Moment, Samuel Schaub

Symposium on Undergraduate Research and Creative Expression (SOURCE)

This research focuses on calculating electric fields in support of a proposed experiment to measure the electric dipole moment (EDM) of the neutron at Las Alamos National Laboratory. The experiment will employ a very strong electric field to exert a torque on the neutrons EDM, if any exists. Field Precision software is used to calculate the theoretical electric fields in and around the central detector region of the proposed experimental setup. This research has two goals. The first is to seek out areas of high electric field in the apparatus that will cause arcing and disrupt the experiment. When these …

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

Masters Theses

No abstract provided.

Special Topics In Physics: Electricity And Magnetism, Ken Smith

A with Honors Projects

With all the problems humanity faces, every solution seems to require more and more energy. Visionaries and scientists alike seem to agree that one of humanity's major hurdles in the future is providing for the enormous need of clean renewable energy. While many mediums to transfer energy exist, electricity is by far the most popular, with petroleum a close second. For electricity, many techniques exist for its generation, but the most common is some type of electromechanical generator. With the increasing need for clean energy, more generating devices will be needed. In order to facilitate this increase it is prudent …

Scaffolding With Video Prior To Sophomore Physics Lab: The Addition And Resolution Of Vectors, David J. Sitar

Master's Theses and Doctoral Dissertations

No abstract provided.

Decay Of A Negative Molecular Ion In A Constant Electric Field, S. V. Borzunov, N. L. Manakov, Anthony F. Starace, M. V. Frolov

Anthony F. Starace Publications

The problem of the shift and broadening of the electron energy levels in the field of two 3D short-range potentials (e.g., the model of a negative molecular ion) by a constant electric field F is considered. The interaction of an electron with attraction centers is taken into account in the effective range approximation. We analyze the cases when both centers maintain weakly bound s states and when the electron state in the field of one of the centers is a p state. Exact numerical results for the shift and the width of the energy levels of a quasi-molecule as functions …

Coupled Photonic Crystal Micro-Cavities With Ultra-Low Threshold Power For Stiumulated Raman Scattering, Qiang Liu, Zhengbiao Ouyang, Sacharia Albin

Electrical & Computer Engineering Faculty Publications

We propose coupled cavities to realize a strong enhancement of the Raman scattering. Five sub cavities are embedded in the photonic crystals. Simulations through finite-difference time-domain (FDTD) method demonstrate that one cavity, which is used to propagate the pump beam at the optical-communication wavelength, has a Q factor as high as 1.254 × 10⁸ and modal volume as small as 0.03μm³ (0.3192(λ/n)³). These parameters result in ultra-small threshold lasing power ~17.7nW and 2.58nW for Stokes and anti-Stokes respectively. The cavities are designed to support the required Stokes and anti-Stokes modal spacing in silicon. The proposed structure …

Ignition Of A Large Volume Plasma With A Plasma Jet, M. Laroussi, M. A. Akman

Electrical & Computer Engineering Faculty Publications

Here we report on a method to generate a long plasma plume and to ignite a large volume plasma by means of the jet. The plasma plume is generated by our tube reactor and then introduced into a chamber where the pressure is controlled. We discovered there are three operating phases:Aphasewhere the plume length remains approximately constant, followed by a second phase where the jet increases in length as the pressure decreases. Then at pressures below 70 Torr a mode transition occurs where the plume length decreases and the plasma expands until the entire chamber is filled.

Unitary-Quantum-Lattice Algorithm For Two-Dimensional Quantum Turbulence, Bo Zhang, George Vahala, Linda L. Vahala, Min Soe

Electrical & Computer Engineering Faculty Publications

Quantum vortex structures and energy cascades are examined for two-dimensional quantum turbulence (2D QT) at zero temperature. A special unitary evolution algorithm, the quantum lattice algorithm, is employed to simulate the Bose-Einstein condensate governed by the Gross-Pitaevskii (GP) equation. A parameter regime is uncovered in which, as in 3D QT, there is a short Poincare recurrence time. It is demonstrated that such short recurrence times are destroyed by stronger nonlinear interaction. The similar loss of Poincare recurrence is also seen in the 3D GP equation. Various initial conditions are considered in an attempt to discern if 2D QT exhibits inverse …

Anisotropic Response Of Nanosized Bismuth Films Upon Femtosecond Laser Excitation Monitored By Ultrafast Electron Diffraction, Ahmed R. Esmail, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

The lattice response of 5 nm thick bismuth film to femtosecond laser excitation is probed by ultrafast electron diffraction. The transient decay time after laser excitation is greater for diffraction from (012) lattice planes compared to (110) planes and is reduced for both planes with the increased laser fluence. These results indicate that different energy coupling mechanisms to the lattice occur depending on the crystal direction. The behavior of the diffraction peak width indicates partial disorder of the film upon photoexcitation that increases together with the laser fluence. © 2011 American Institute of Physics. [doi:10.1063/1.3652919]

Poincare Recurrence And Spectral Cascades In Three-Dimensional Quantum Turbulence, George Vahala, Jeffrey Yepez, Linda L. Vahala, Min Soe, Bo Zhang, Sean Ziegeler

Electrical & Computer Engineering Faculty Publications

The time evolution of the ground state wave function of a zero-temperature Bose-Einstein condensate (BEC) gas is well described by the Hamiltonian Gross-Pitaevskii (GP) equation. Using a set of appropriately interleaved unitary collision-stream operators, a qubit lattice gas algorithm is devised, which on taking moments, recovers the Gross-Pitaevskii (GP) equation under diffusion ordering (time scales as length²). Unexpectedly, there is a class of initial states whose Poincaré recurrence time is extremely short and which, as the grid resolution is increased, scales with diffusion ordering (and not as length³). The spectral results of J. Yepez et al. …

Design Of Superconducting Spoke Cavities For High-Velocity Applications, Jean R. Delayen, Subashini De Silva, C. S. Hopper

Physics Faculty Publications

Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β₀ ~ 0.15 to β₀ ~ 0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of spoke cavities optimized for β₀ = 0.8 and β₀ = 1.

Design Of Superconducting Parallel Bar Deflecting/Crabbing Cavities, Jean R. Delayen, Subashini De Silva

Physics Faculty Publications

The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. We present an analysis of several designs of parallel-bar cavities and their electromagnetic properties.

Crab Crossing Consideration For Meic, S. Ahmed, Y. Derbenev, Geoffrey A. Krafft, Y. Zhang, Subashini De Silva, Jean R. Delayen, A. Castilla

Physics Faculty Publications

Crab crossing of colliding electron and ion beams is essential for accommodating the high bunch repetition frequency in the conceptual design of MEIC – a high luminosity polarized electron-ion collider at Jefferson Lab. The scheme eliminates parasitic beam-beam interactions and avoids luminosity reduction by restoring head-on collisions at interaction points. In this paper, we report the possible crabbing schemes and requirements for both electron and proton beams.

Multipacting Analysis Of The Superconducting Parallel-Bar Cavity, Subashini De Silva, Jean R. Delayen

Physics Faculty Publications

The superconducting parallel-bar cavity [1] is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. Multipacting can be a limiting factor to the performance of in any superconducting structure. In the parallel-bar cavity the main contribution to the deflection is due to the transverse deflecting voltage, between the parallel bars, making the design potentially prone to multipacting. This paper presents the results of analytical calculations and numerical simulations of multipacting in the parallel-bar cavity with resonant voltage, impact energies and corresponding particle trajectories.

Analysis Of Hom Properties Of Superconducting Parallel-Bar Deflecting/Crabbing Cavities, Subashini De Silva, Jean R. Delayen

Physics Faculty Publications

The superconducting parallel-bar cavity is currently being considered for a number of deflecting and crabbing applications due to improved properties and compact design geometries. The 499 MHz deflecting cavity proposed for the Jefferson Lab 12 GeV upgrade and the 400 MHz crab cavity for the proposed LHC luminosity upgrade are two of the major applications. For high current applications the higher order modes must be damped to acceptable levels to eliminate any beam instabilities. The frequencies and R/Q of the HOMs and mode separation are evaluated and compared for different parallel-bar cavity designs.

Precise Measurements Of Beam Spin Asymmetries In Semi-Inclusive Π0 Production, M. Aghasyan, H. Avakian, P. Rossi, E. De Sanctis, D. Hasch, M. Mirazita, D. Adikaram, M. J. Amaryan, M. Anghinolfi, H. Baghdasaryan, R. P. Bennett, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein

Physics Faculty Publications

We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial sin phi(h) amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle φh of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations. (C) 2011 Elsevier B.V.

Photon Impact Factor In The Next-To-Leading Order, Ian Balitsky, Giovanni A. Chirilli

Physics Faculty Publications

An analytic coordinate-space expression for the next-to-leading order photon impact factor for small-x deep inelastic scattering is calculated using the operator expansion in Wilson lines.

Comparing Optical Sensing Using Slab Waveguides And Total Internal Reflection Ellipsometry, Sofyan A. Taya, Taher M. El-Agez

Turkish Journal of Physics

The sensitivity of the effective refractive index of slab waveguide sensors to variations in the refractive index of the cladding is compared to that of the ellipsometric parameters. The changes of the effective refractive index of a waveguide and the ellipsometric parameter \Delta , due to the index change of the cladding, were derived and plotted as a function of the guiding layer thickness and with the index of the cladding. It is found that these changes almost have the same overall feature but the ellipsometric parameters showed considerable higher sensitivity than the effective index of the conventional waveguide optical …

Nuclear Structure Of Even-Even Ge Isotopes By Means Of Interacting Boson Models, Abdul R. H. Subber

Turkish Journal of Physics

Interacting Boson Models IBM-1and IBM-2, have been used to calculate energy levels and nuclear properties of the even-even Ge isotopes from A = 64 to A = 80. Energy levels of the low lying states of these nuclei were produced, the electric quadruple reduced transition probabilities B(E2) were calculated as well. Mixing ratios \delta (E2/M1) for transitions with \Delta I=0, I \ne 0 were calculated. All the results are compared with available experimental data and other IBM versions and calculations. Satisfactory agreements were produced.

Analytical Expression For Mode-Coherence Coefficient Of A Uniformly-Distributed Wave Propagating In Different Homogeneous Media, Noor Ezzulddin Naji

Turkish Journal of Physics

Presented is a derivation of an analytical expression for the mode-coherence coefficients of uniform-distributed wave propagating within different homogeneous media-as in the case of hyperbolic Gaussian beams-and a simple method involving the superposition of two such beams is proposed. The results obtained from this work are very applicable to study and analysis of Hermite-Gaussian beam propagation, especially in the problems of radiation-matter interaction, and laser beam propagation such as employed in free-space and fiber optical communications.