Physics Commons^™

Analysis Of One-Nucleon Transfer Cross-Sections, A. K. A. R. Al-Farra

Turkish Journal of Physics

The angular distributions of ^{26}Mg(^3H,^2H)^{27}Mg and ^{30}Si(^3H,^2H)^{31}Si reactions have been successfully studied using distorted wave Born approximation (DWBA) calculations. The optical model potentials are taken to have Woods-Saxon, parity and spin-orbit interactions. The present analysis gives a satisfactory fit to the forward angle data but grossly over estimates the cross-sections in the backward regions. The spin-orbit potential provides the best description of the experimental data and is found to be necessary to account for the large-angle cross sections. The obtained values of the extracted spectroscopic factors are reasonable.

Empirical Correlations Of Global Solar Radiation With Meteorological Data For Onne, Nigeria, Louis E. Akpabio, Sunday O. Udo, Sunday E. Etuk

Turkish Journal of Physics

Multiple linear regression models were developed to estimate the monthly average daily global solar radiation using ten parameters during a period of sixteen years (1984 to 1999) for Onne, Nigeria; the extraterrestrial radiation, average daily temperature, ratio of minimum and maximum daily temperature, relative humidity, ratio of sunshine duration, solar declination, average soil temperature, average pan evaporimeter, average rain fall and average daily dew. Even though up to ten variable correlations has been developed; the results showed that eight variable correlations with the highest value of correlation coefficient R gives the best result when considering the error terms (mean percentage …

On Hamiltonian Formulation Of Non-Conservative Systems, Eqab M. Rabei, Tareq S. Alhalholy, A. A. Taani

Turkish Journal of Physics

Fractional derivatives are used to construct the Lagrangian and the Hamiltonian formulation for non-conservative systems. To clarify the theory of Riewe two interesting examples are given. The potentials are obtained using the Laplace transform operator for fractional derivatives and the Lagrangian and Hamiltonian formulations are constructed for the two systems. Besides, it is shown that the Hamilton equations of motion are in agreement with the Euler-Lagrange equations for these systems.

Self Ionization Probabilities Following De-Excitation Decay Of K-Shell Vacancy In Atoms Z = 10--80, Adel M. El-Shemi

Turkish Journal of Physics

The average number of ejected electrons and the probability of ion charge state distributions following K-shell ionization in atoms from Z = 10 to Z = 80 were calculated. Monte Carlo simulation technique was used to simulate all possible pathways of radiative and non-radiative transitions to fill the inner-shell ionization in excited atoms. The radiative and non-radiative branching ratios were calculated from Multiconfiguration Dirac-Fock (MCDF) and Dirac-Fock-Slater (DFS) wave functions. The average number of ejected electrons in atoms with Z = 10 is about two, because the non-radiative transitions exceed radiative transitions by 98\%. The mean number of ejected electrons …

Determination Of The Rotational Constant A_0 And The Bending Angle Cnc For Ch_3 Nc And Ch_3 ^{15}Nc Molecules, Mohammad Al-Share

Turkish Journal of Physics

The rotational constant A_0 for the ground state of CH_3 NC and CH_3 ^{15}NC isotopomers is calculated using a technique which was used earlier for CH_3CCH [9], CH_3CN [10] and SiH_3CCH [11]. This technique is based on calculating the moment of inertia tensors in the bent configuration due to the \nu_8 vibrational state, which is associated with the CNC bending vibration. These values of the moments of inertia are fitted with the values calculated from the rotational constant B_V, found experimentally by measuring the rotational frequencies in the microwave and infrared regions. From the fitting, the rotational constant A_0, the …

Structure And Dielectric Behaviour Of Barium Cupro Molybdate Ceramic, N. G. Durge, M. S. Nadkarni, S. V. Salvi

Turkish Journal of Physics

The ceramic of new perovskite Ba (Cu_{1/2} Mo_{1/2}) O_3 has been synthesized at 1200 °C for 24 hours. The XRD analysis indicates an ordered hexagonal structure, which is attributed to large valency difference between octahedral cations. The IR spectrum reveals the presence of Cu-O-Mo ordered bond. The room temperature relaxation spectra imply a large conductivity term and multiple `Debye terms' at low frequencies. This is attributed to presence of the space charge. The variation of dielectric constant with temperature has been investigated from room temperature to 800 K. The diffusivity constant equal to 1 implies normal ferroelectric behaviour near room …

A Novel Radiative Substrate Heater, Abdullah Ceylan, Erdal Kaynak, Şadan Özcan, Tezer Firat

Turkish Journal of Physics

In this work, we have developed a new low cost radiative substrate heater for deposition of high-T_c superconducting thin films. It has all the features required for the preparation of high quality superconducting thin films. It is possible to reach ~ 800 °C substrate temperature with it by using only one 250 W halogen projector bulb.

Effect Of Development Time On Polymer Phase Separation In A Pmma Resist, Mohammad Naeem Khalid, Shazia Yasin, Mohammad Riaz Khan

Turkish Journal of Physics

Developer composition type and development technique are known to influence surface and edge roughness in polymethylemethacrylate (PMMA); and it is during development, we believe, that the result is most influenced by the phase separation into polymer-rich and polymer-poor regions. This polymer phase separation is more prominent in a weaker developer and low temperature. In this paper, we investigate the effect of development time on the extent of polymer phase separation in an exposed PMMA developed in a standard developer i.e. 1:3 MIBK:IPA at 20 °C and rinsed in pure IPA for 30 sec. The polymer phase separation is found to …

Physical Characteristics Of Polymer Magnetic Microspheres, Rasim A. Ali-Zade

Turkish Journal of Physics

In this study the structure and the magnetic properties of polymer microspheres, filled with magnetite nanoparticles are investigated. Average particle size of magnetite nanoparticles before and after being introduced into polymer microspheres, and the distance between nanoparticles in the polymer microspheres, are measured. Magnetization curve of polymer magnetic microspheres (PMMS) is determined. The magnetic susceptibility of PMMS with various diameters, and the dependence of PMMS magnetic susceptibility on diameter are determined. Magnetization occurs due to the orientation of PMMS as a magnetic moment. The total magnetic moment of PMMS is the sum of magnetic moments of PMMS sections which consist …

Cyclotron Resonant Heating And Acceleration Of Protons, O Vi & Mg X Ions In The North Polar Coronal Hole, E. Rennan Pekünlü, Kadri̇ Yakut, Hi̇cran Şart

Turkish Journal of Physics

Ultraviolet Coronograph Spectrometer aboard Solar and Heliospheric Observatory (SOHO) has revealed the existence of temperature anisotropy of many minor ion species that populate the north solar polar coronal hole. In this study, we examined the propagation characteristics of ion-cyclotron waves which resonate with protons, O VI and Mg X ions. In our empirical model, radial variation of the magnetic field, electron and ion number densities, perpendicular and parallel temperature of protons, O VI and Mg X ions are adopted from the measurements of various instruments aboard SOHO. Since most of the measurements of SOHO instruments begin at 1.5 R (=r/R_{\odot}) …

An Investigation Of The Relationship Between In-Vitro And In-Vivo Ultrasound Image Quality Parameters, Jacinta Browne, Amanda Watson, Cathy Muir, Peter Hoskins, Alex Elliott

Articles

The aim of this paper is to investigate the relationship between Bmode and colour Doppler technical test methods with the clinical perception of Bmode and Doppler invivo test parameters. It was found that technical and clinical comparisons between the Bmode test parameters: lateral resolution versus clinical resolution; anechoic target detection versus clinical noise; and penetration depth versus clinically useful penetration depth, demonstrated moderate correlations, (r= 0.69, p

Validation Of A Sensitivity Performance Index Test Protocol And Evaluation Of Colour Doppler Sensitivity For A Range Of Ultrasound Scanners, Jacinta Browne, Amanda Watson, Peter Hoskins, Alex Elliott

Articles

The ability to detect flow is the most crucial aspect of an ultrasound (US) system because, if flow cannot be detected, no other aspect of performance matters. The objectives of this study were to validate a Doppler “sensitivity performance index,” a figure of merit, and to determine if it could be used to differentiate colour Doppler sensitivity performance in scanners of varying complexity. The sensitivity performance index was developed to give a combined measure of related aspects of sensitivity, such as the lowest detectable velocity, the vessel size and the penetration depth. The colour Doppler sensitivity was evaluated objectively as …

Radiation Transport Modeling Using Parallel Computational Techniques, William Culbreth, Denis Beller

Reactor Campaign (TRP)

The second year of this project involved modeling several aspects of the LANCSE beam experiments:

• Modeling targets of varying diameter in air, in a vacuum, and in the presence of humid air;
• Modeling various proton beam profiles;
• Modeling the effects of off-axis proton beam impingement on the target;
• Modeling the asymmetry introduced by the steel table below the target;
• Modeling the effect of varying ratios of Pb to Bi and the effect of impurities; and
• Modeling the system, including other structures within the test room.

With the experience gained through modeling these systems, the UNLV researchers plan, with the assistance …

Investigation Of Optical Spectroscopy Techniques For On-Line Materials Accountability In The Solvent Extraction Process, Gary Cerefice, Kenneth Czerwinski

Safeguards Campaign (TRP)

The goal of this project is to examine the potential for using optical spectroscopy techniques, such as UV-Visible Spectroscopy and Laser Fluorescence Spectroscopy, for special nuclear materials accountability applications for the UREX+ and other solvent extraction processes. To increase the inherent proliferation resistance of the solvent extraction process, it is necessary to develop on-line techniques to directly measure the concentrations of special nuclear materials in-process. By providing on-line materials accountability for the processes, the potential for covert diversion of the materials streams becomes much more difficult to implement. On-line monitoring of material streams will also allow for improved plant operation, …

Corrosion Of Steel By Lead Bismuth Eutectic, John Farley, Allen L. Johnson, Dale L. Perry

Transmutation Sciences Materials (TRP)

There is an active international interest in lead-bismuth eutectic and similar liquid lead systems because of the relevance to the transmutation of nuclear waste, fast reactors, and spallation neutron sources. A successful program in nuclear waste processing that includes transmutation in accelerator-driven systems and fast reactors, would significantly decrease the space requirements for geological repositories.

Materials in these systems must be able to tolerate high neutron fluxes, high temperatures, and chemical corrosion. For lead bismuth eutectic (LBE) systems, there is an additional challenge because the corrosive behaviors of materials in LBE are not well understood. Most of the available information …

Stress Corrosion Cracking Of Target Material, Mohammad K. Hossain

Transmutation Sciences Materials (TRP)

The primary objective of this paper is to evaluate the effect of hydrogen on environment assisted cracking of candidate target materials for transmutation applications. Transmutation refers to transformation of long-lived actinides and fission products from spent nuclear fuels (SNF), and occurs when the nucleus of an atom changes because of natural radioactive decay, nuclear fission, nuclear fusion, neutron capture, or other related processes. Martensitic Alloy EP 823 was selected to be the candidate alloy for this investigation. During the initial phase, the stress corrosion cracking (SCC) behavior of this alloy was evaluated in neutral (pH: 6-7) and acidic (pH: 2-3) …

Development Of Dose Coefficients For Radionuclides Produced In Spallation Targets, Phillip W. Patton, Mark Rudin

Transmutation Sciences Physics (TRP)

Dose coefficients permit simple determination of radiation dose associated with various exposure scenarios, and ultimately permit radiation safety personnel to assess the health risks to workers in a nuclear facility. Specifically, radiation safety personnel use dose coefficients to determine the radiation dose incurred to a tissue or organ system from a given exposure. These parameters are often expressed in terms of Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs).

Results from this study will be used to produce ALIs and DACs for these rare radionuclides created by spallation target systems that are not included in Federal Guidance Report …

Nuclear Criticality, Shielding, And Thermal Analyses Of Separations Processes For The Transmutation Fuel Cycle, William Culbreth

Separations Campaign (TRP)

The first step in any transmutation strategy is the separation of radionuclides in used nuclear fuel. The current separation strategy supporting the Advanced Fuel Cycle Initiative (AFCI) program is based on the use of a solvent extraction separation process to separate the actinides, fission products, and uranium from used commercial nuclear fuel, and on the use of pyrochemical separation technologies to process used transmuter fuels. To separate the fission products and transuranic elements from the uranium in used fuel, the national program is developing a new solvent extraction process, the Uranium Extraction Plus, or UREX+, process based on the traditional …

Performance Characteristics Of Beamline 6.3.1 From 200 Ev To 2000 Ev At The Advanced Light Source, Ponnusamy Nachimuthu, J. H. Underwood, C. D. Kemp, Eric M. Gullikson, Dennis W. Lindle, David K. Shuh, Rupert C. Perera

Chemistry and Biochemistry Faculty Research

Bend magnet beamline 6.3.1 at the Advanced Light Source operates from 200 eV to 2000 eV, primarily used for x-ray absorption fine structure investigations. The beamline optics consist of a compact, entrance-slitless, Hettrick-Underwood type variable-line-spacing plane-grating monochromator and refocusing mirrors to provide a 25 μm × 500 μm spot at the focal point in the reflectometer end station. Wavelength is scanned by the simple rotation of the grating and illuminates a fixed exit slit. The LabView based beamline control and data acquisition computer code has been implemented to provide a convenient interface to the user. The dedicated end station is …

Design And Analysis Of A Process For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Yitung Chen, Darrell Pepper, Randy Clarksean

Fuels Campaign (TRP)

The goal of this project is to investigate the casting processes for metallic fuels to help design a process that minimizes the loss of the volatile actinide elements from the fuel. The research effort centers on the development of advanced numerical models to assess conditions that significantly impact the transport of volatile actinides during the melt casting process and represents a joint effort between researchers at UNLV and Argonne National Laboratory (ANL). Assessing critical equipment and process variables is required to build a successful system that will operate efficiently.

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix, Kenneth Czerwinski

Fuels Campaign (TRP)

This project will examine inert fuels containing ZrO₂ and MgO as the inert matrix, with the relative amount of MgO varied from 30% to 70% in ZrO₂. Reactor physics calculations will be used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf with reactor grade Pu providing the fissile component, with up to 10 % of ²³⁹Pu. Ceramics will be synthesized and characterized based on the reactor physics results. The solubility the fuel ceramics, in reactor conditions, reprocessing conditions, and repository conditions, will be investigated in a manner to provide …

Multiple Scattering Of Light In Inhomogeneous Media And Applications, Claudia Mujat

Electronic Theses and Dissertations

Light scattering-based techniques are being developed for non-invasive diagnostics of inhomogeneous media in various fields, such as medicine, biology, and material characterization. However, as most media of interest are highly scattering and have a complex structure, it is difficult to obtain a full analytical solution of the scattering problem without introducing approximations and assumptions about the properties of the system under consideration. Moreover, most of the previous studies deal with idealized scattering situations, rarely encountered in practice. This dissertation provides new analytical, numerical, and experimental solutions to describe subtle effects introduced by the properties of the light sources, and by …

Electron Injection-Induced Effects In Iii-Nitrides: Physics And Applications, William Charles Burdett

Electronic Theses and Dissertations

This research investigated the effect of electron injection in III-Nitrides. The combination of electron beam induced current and cathodoluminescence measurements was used to understand the impact of electron injection on the minority carrier transport and optical properties. In addition, the application of the electron injection effect in optoelectronic devices was investigated. The impact of electron injection on the minority carrier diffusion length was studied at various temperatures in Mg-doped p-GaN, p-Al[subscript x]Ga[subscript 1-x]N, and p-Al[subscript x]Ga[subscript 1-x] N/GaN superlattices. It was found that Lsubscript n] experienced a multi-fold linear increase and that the rate of change of L[subscript n] decreased …

Individual Carbon Nanotube Probes And Field Emitters Fabrication And T, Guangyu Chai

Electronic Theses and Dissertations

Since the discovery of carbon nanotubes (CNT) in 1999, they have attracted much attention due to their unique mechanical and electrical properties and potential applications. Yet their nanosize makes the study of individual CNTs easier said than done. In our laboratory, carbon fibers with nanotube cores have been synthesized with conventional chemical vapor deposition (CVD) method. The single multiwall carbon nanotube (MWNT) sticks out as a tip of the carbon fiber. In order to pick up the individual CNT tips, focused ion beam (FIB) technique is applied to cut and adhere the samples. The carbon fiber with nanotube tip was …

Polarimetric Characterization Of Random Electromagnetic Beams And Applications, Mircea Mujat

Electronic Theses and Dissertations

Polarimetry is one of the principal means of investigating the interaction of light with matter. Theoretical models and experimental techniques are presented in this dissertation for polarimetric characterization of random electromagnetic beams and of signatures of random media in different scattering regimes and configurations. The degree of polarization rather than the full description of the state of polarization is of interest in multiple scattering and free space propagation where the statistical nature and not the deterministic component of light bears the relevant information. A new interferometric technique for determining the degree of polarization by measuring the intensity fluctuations in a …

Quadratic Spatial Soliton Interactions, Ladislav Jankovic

Electronic Theses and Dissertations

Quadratic spatial soliton interactions were investigated in this Dissertation. The first part deals with characterizing the principal features of multi-soliton generation and soliton self-reflection. The second deals with two beam processes leading to soliton interactions and collisions. These subjects were investigated both theoretically and experimentally. The experiments were performed by using potassium niobate (KNBO3) and periodically poled potassium titanyl phosphate (KTP) crystals. These particular crystals were desirable for these experiments because of their large nonlinear coefficients and, more importantly, because the experiments could be performed under non-critical-phase-matching (NCPM) conditions. The single soliton generation measurements, performed on KNBO3 by launching the …

Stable Spatial Solitons In Semiconductor Optical Amplifiers, Erdem Ultanir

Electronic Theses and Dissertations

A spatial soliton is a shape invariant self guided beam of light or a self induced waveguide. Spatial solitons appear as a result of the balance of diffraction and nonlinear focusing in a system. They have been observed in many different conservative media in the last couple of years. Solitons are ubiquitous, because of the probability of using their interactions in optical data processing, communications etc. Up to now due to the power required to generate the solitons, and the response times of the soliton supporting media, these special waves of nature could not penetrate the applications arena. Semiconductors, with …

Dispersion-Managed Breathing-Mode Semiconductor Mode-Locked Ring Laser, Bojan Resan

Electronic Theses and Dissertations

A novel dispersion-managed breathing-mode semiconductor mode-locked ring laser is developed. The "breathing-mode" designation derives from the fact that intracavity pulses are alternately stretched and compressed as they circulate around the ring resonator. The pulses are stretched before entering the semiconductor gain medium to minimize the detrimental strong integrating self-phase modulation and to enable efficient pulse amplification. Subsequently compressed pulses facilitate bleaching the semiconductor saturable absorber. The intracavity pulse compression ratio is higher than 50. Down chirping when compared to up chirping allows broader mode-locked spectra and shorter pulse generation owing to temporal and spectral semiconductor gain dynamics. Pulses as short …

Towards Direct Writing Of 3-D Photonic Circuits Using Ultrafast Lasers, Arnaud Zoubir

Electronic Theses and Dissertations

The advent of ultrafast lasers has enabled micromachining schemes that cannot be achieved by other current techniques. Laser direct writing has emerged as one of the possible routes for fabrication of optical waveguides in transparent materials. In this thesis, the advantages and limitations of this technique are explored. Two extended-cavity ultrafast lasers were built and characterized as the laser sources for this study, with improved performance over existing systems. Waveguides are fabricated in oxide glass, chalcogenide glass, and polymers, these being the three major classes of materials for the telecommunication industry. Standard waveguide metrology is performed on the fabricated waveguides, …

New Methods For Exafs Analysis In Structural Genomics, Grant Bunker, Nicholas Dimakis, Gocha Kelashvili

Physics & Astronomy Faculty Publications

Data analysis is one of the remaining bottlenecks in high-throughput EXAFS for structural genomics. Here some recent developments in methodology are described that offer the potential for rapid and automated XAS analysis of metalloproteins.