32 Matching Results

Search Results

Advanced search parameters have been applied.

Photonic equation of motion with application to the Lamb shift

Description: A photonic equation of motion is proposed which is the scalar product of four-vectors and therefore a Lorentz invariant. A photonic equation of motion, which has not been heretofore established in quantum electrodynamics (QED), would capture the quantum nature of light but yet not have the standard field-operator form, thereby making practical calculations easier to perform. The equation of motion proposed here is applied to the Lamb shift. No divergences exist, and the result agrees with the observed Lamb shift for the 1S{sub 1/2} state of hydrogen within experimental error.
Date: December 21, 2006
Creator: Ritchie, A B
Partner: UNT Libraries Government Documents Department

Hamiltonian Light-front Field Theory Within an AdS/QCD Basis

Description: Non-perturbative Hamiltonian light-front quantum field theory presents opportunities and challenges that bridge particle physics and nuclear physics. Fundamental theories, such as Quantum Chromodynamics (QCD) and Quantum Electrodynamics (QED) offer the promise of great predictive power spanning phenomena on all scales from the microscopic to cosmic scales, but new tools that do not rely exclusively on perturbation theory are required to make connection from one scale to the next. We outline recent theoretical and computational progress to build these bridges and provide illustrative results for nuclear structure and quantum field theory. As our framework we choose light-front gauge and a basis function representation with two-dimensional harmonic oscillator basis for transverse modes that corresponds with eigensolutions of the soft-wall AdS/QCD model obtained from light-front holography.
Date: December 16, 2009
Creator: Vary, J.P.; Honkanen, H.; Li, Jun; Maris, P.; U., /Iowa State; Brodsky, S.J. et al.
Partner: UNT Libraries Government Documents Department

Characterizing electrodynamic shakers

Description: An electrodynamic shaker is modeled as a mixed electrical/mechanical system with an experimentally derived two port network characterization. The model characterizes the shaker in a manner that the performance of the shaker with a mounted load (test item and fixture) can be predicted. The characterization depends on the measurements of shaker input voltage and current, and on the acceleration of the shaker armature with several mounted loads. The force into the load is also required, and can be measured directly or inferred from the load apparent mass.
Date: December 31, 1996
Creator: Smallwood, D.O.
Partner: UNT Libraries Government Documents Department

High-Throughput Analysis With 96-Capillary Array Electrophoresis and Integrated Sample Preparation for DNA Sequencing Based on Laser Induced Fluorescence Detection

Description: The purpose of this research was to improve the fluorescence detection for the multiplexed capillary array electrophoresis, extend its use beyond the genomic analysis, and to develop an integrated micro-sample preparation system for high-throughput DNA sequencing. The authors first demonstrated multiplexed capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) separations in a 96-capillary array system with laser-induced fluorescence detection. Migration times of four kinds of fluoresceins and six polyaromatic hydrocarbons (PAHs) are normalized to one of the capillaries using two internal standards. The relative standard deviations (RSD) after normalization are 0.6-1.4% for the fluoresceins and 0.1-1.5% for the PAHs. Quantitative calibration of the separations based on peak areas is also performed, again with substantial improvement over the raw data. This opens up the possibility of performing massively parallel separations for high-throughput chemical analysis for process monitoring, combinatorial synthesis, and clinical diagnosis. The authors further improved the fluorescence detection by step laser scanning. A computer-controlled galvanometer scanner is adapted for scanning a focused laser beam across a 96-capillary array for laser-induced fluorescence detection. The signal at a single photomultiplier tube is temporally sorted to distinguish among the capillaries. The limit of detection for fluorescein is 3 x 10{sup -11} M (S/N = 3) for 5-mW of total laser power scanned at 4 Hz. The observed cross-talk among capillaries is 0.2%. Advantages include the efficient utilization of light due to the high duty-cycle of step scan, good detection performance due to the reduction of stray light, ruggedness due to the small mass of the galvanometer mirror, low cost due to the simplicity of components, and flexibility due to the independent paths for excitation and emission.
Date: December 31, 2001
Creator: Xue, Gang
Partner: UNT Libraries Government Documents Department

Electrokinetic decontamination of concrete

Description: Concrete structures which have been contaminated with uranium and other radioisotopes may be decontaminated using in-situ electrokinetic remediation. By placing an electrode cell on the concrete surface and using the concrete`s rebar, a ground rod, or another surface cell as the counter electrode, the radioisotopes may be migrated from the concrete into this cell. The process is highly dependent upon the chemical parameters of the species involved; namely, the concrete, the contaminants, and the solubilizers used to mobilize the contaminants. In a preliminary study conducted at the K-25 Site of the Oak Ridge National Labs, an estimated removal of >40 percent of uranium has been observed for a short duration run. This removal occurred using traditional uranium solubilizers in contact with the contaminated surface.
Date: December 31, 1994
Creator: Lomasney, H.L. & Yachmenev, V.
Partner: UNT Libraries Government Documents Department

Conceptual design analysis of an MHD power conversion system for droplet-vapor core reactors. Final report

Description: A nuclear driven magnetohydrodynamic (MHD) generator system is proposed for the space nuclear applications of few hundreds of megawatts. The MHD generator is coupled to a vapor-droplet core reactor that delivers partially ionized fissioning plasma at temperatures in range of 3,000 to 4,000 K. A detailed MHD model is developed to analyze the basic electrodynamics phenomena and to perform the design analysis of the nuclear driven MHD generator. An incompressible quasi one dimensional model is also developed to perform parametric analyses.
Date: December 31, 1995
Creator: Anghaie, S. & Saraph, G.
Partner: UNT Libraries Government Documents Department

Thermodynamics and electrodynamics of unusual narrow-gap semiconductors

Description: This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL) that has led to a fully funded DOE program to continue this work. The project was directed toward exploring the Ettingshausen effect, which is the direct extension of the familiar Peltier-effect refrigerator (the process used in popular coolers that run off automotive electrical power) in which a magnetic field is used to enhance refrigeration effects at temperatures well below room temperature. Such refrigeration processes are all-solid-state and are of potentially great commercial importance, but essentially no work has been done since the early 1970s. Using modern experimental and theoretical techniques, the authors have advanced the state-of-the-art significantly, laying the groundwork for commercial cryogenic solid-state refrigeration.
Date: December 1998
Creator: Migliori, A.; Darling, T. W.; Trugman, S. A.; Freibert, F.; Moshopoulou, E. & Sarrao, J. L.
Partner: UNT Libraries Government Documents Department

Task 38 - commercial mercury remediation demonstrations: Thermal retorting and physical separation/chemical leaching. Topical report, December 1, 1994--June 30, 1996

Description: Results are presented on the demonstration of two commercial technologies for the removal of mercury from soils found at natural gas metering sites. Technologies include a thermal retorting process and a combination of separation, leaching, and electrokinetic separation process.
Date: December 31, 1998
Creator: Charlton, D.S.; Fraley, R.H. & Stepan, D.J.
Partner: UNT Libraries Government Documents Department

Microfluidic Engineering

Description: The ability to generate high pressures using electrokinetic pumping of liquid through porous media is reported. Pressures in excess of 8000 psi have been achieved using capillaries (< 100 {micro}m i.d.) packed with micron-size silica beads. A model is presented which accurately predicts absolute pressures, flowrates and power conversion efficiencies as well as the experimentally observed dependencies on pore size, applied electric field and electrical properties of the fluid. This phenomenon offers the possibility of creating a new class of microscale fluid devices, electrokinetic pumps and valves, where the performance improves with scale-down by taking advantage of microscale processes.
Date: December 1, 1998
Creator: Paul, Phillip H.
Partner: UNT Libraries Government Documents Department

ELECTROKINETIC DENSIFICATION OF COAL FINES IN WASTE PONDS

Description: The objective of this research was to demonstrate that electrokinetics can be used to remove colloidal coal and mineral particles from coal-washing ponds and lakes without the addition of chemical additives such as salts and polymeric flocculants. The specific objectives were: Design and develop a scaleable electrophoresis apparatus to clarify suspensions of colloidal coal and clay particles; Demonstrate the separation process using polluted waste water from the coal-washing facilities at the coal-fired power plants in Centralia, WA; Develop a mathematical model of the process to predict the rate of clarification and the suspension electrical properties needed for scale up.
Date: December 18, 1999
Creator: Davis, E. James
Partner: UNT Libraries Government Documents Department

Theoretical aspects of light meson spectroscopy

Description: In this pedagogical review the authors discuss the theoretical understanding of light hadron spectroscopy in terms of QCD and the quark model. They begin with a summary of the known and surmised properties of QCD and confinement. Following this they review the nonrelativistic quark potential model for q{anti q} mesons and discuss the quarkonium spectrum and methods for identifying q{anti q} states. Finally, they review theoretical expectations for non-q{anti q} states (glueballs, hybrids and multiquark systems) and the status of experimental candidates for these states.
Date: December 31, 1995
Creator: Barnes, T.
Partner: UNT Libraries Government Documents Department

Electrokinetic decontamination of concrete

Description: The US Department of Energy has assigned a priority to the advancement of technology for decontaminating concrete surfaces which have become contaminated with radionuclides, heavy metals, and toxic organics. This agency is responsible for decontamination and decommissioning of thousands of buildings. Electrokinetic extraction is one of the several innovative technologies which emerged in response to this initiative. This technique utilizes an electropotential gradient and the subsequent electrical transport mechanism to cause the controlled movement of ionics species, whereby the contaminants exit the recesses deep within the concrete. The primary objective was to demonstrate the feasibility of this approach as a means to achieve ``release levels`` which could be consistent with unrestricted use of a decontaminated building. The secondary objectives were: To establish process parameters; to quantify the economics; to ascertain the ALARA considerations; and to evaluate wasteform and waste volume. The work carried out to this point has achieved promising results to the extent that ISOTRON{reg_sign} has been authorized to expand the planned activity to include the fabrication of a prototype version of a commercial device.
Date: December 31, 1995
Creator: Lomasney, H.
Partner: UNT Libraries Government Documents Department

Investigation of electrokinetic decontamination of concrete

Description: Experiments have been conducted to investigate the capabilities of electrokinetic decontamination of concrete. Batch equilibration studies have determined that the loading of cesium and strontium on concrete may be decreased using electrolyte solutions containing competing cations, while solubilization of uranium and cobalt, that precipitate at high pH, will require lixiviants containing complexing agents. Dynamic electrokinetic experiments showed greater mobility of cesium than strontium, while some positive results were obtained for the transport of cobalt through concrete using EDTA and for uranium using carbonate.
Date: December 31, 1995
Creator: DePaoli, D.W.; Harris, M.T.; Morgan, I.L. & Ally, M.R.
Partner: UNT Libraries Government Documents Department

Development of the integrated in situ Lasagna process

Description: Contamination in deep, low permeability soils poses a significant technical challenge to in-situ remediation efforts. Poor accessibility to the contaminants and difficulty in uniform delivery of treatment reagents have rendered existing in-situ methods such as bioremediation, vapor extraction, and pump and treat rather ineffective when applied to low permeability soils present at many contaminated sites.
Date: December 31, 1995
Creator: Ho, S.; Athmer, C. & Sheridan, P.
Partner: UNT Libraries Government Documents Department

BASIC ENGINEERING RESEARCH FOR D&D OF R REACTOR STORAGE POND SLUDGE: ELECTROKINETICS, CARBON DIOXIDE EXTRACTION, AND SUPERCRITICAL WATER OXIDATION

Description: Large quantities of mixed low level waste (MLLW) that fall under the Toxic Substances Control Act (TSCA) exist and will continue to be generated during D&D operations at DOE sites across the country. Currently, the volume of these wastes is approximately 23,500 m3, and the majority of these wastes (i.e., almost 19,000 m3) consist of PCBs and PCB-contaminated materials. Further, additional PCB-contaminated waste will be generated during D&D operations in the future. The standard process for destruction of this waste is incineration, which generates secondary waste that must be disposed, and the TSCA incinerator at Oak Ridge has an uncertain future. Beyond incineration, no proposed process for the recovery and/or destruction of these persistent pollutants has emerged as the preferred choice for DOE cleanup. The main objective of the project was to investigate and develop a deeper understanding of the thermodynamic and kinetic reactions involved in the extraction and destruction of polychlorinated biphenyls (PCBs) from low-level mixed waste solid matrices in order to provide data that would permit the design of a combined-cycle extraction/destruction process. The specific research objectives were to investigate benign dense-fluid extraction with either carbon dioxide (USC) or hot water (CU), followed by destruction of the extracted PCBs via either electrochemical (USC) or hydrothermal (CU) oxidation. Two key advantages of the process are that it isolates and concentrates the PCBs from the solid matrices (thereby reducing waste volume greatly and removing the remaining low-level mixed waste from TSCA control), and little, if any, secondary solvent or solid wastes are generated. This project was a collaborative effort involving the University of South Carolina (USC), Clemson University (CU), and Westinghouse Savannah River Company (WSRC) (including the Savannah River Technology Center, Facilities Decommissioning Division and Regulatory Compliance). T he project was directed and coordinated by the South Carolina Universities Research ...
Date: December 31, 2001
Creator: Matthews, Michael A.; Bruce,David; Davis,Thomas; Thies, Mark; Weidner, John & White, Ralph
Partner: UNT Libraries Government Documents Department

Rf Gun with High-Current Density Field Emission Cathode

Description: High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes
Date: December 19, 2005
Creator: Hirshfield, Jay L.
Partner: UNT Libraries Government Documents Department

Thirteen years of pair production

Description: This talk surveys a thirteen-year collaboration with Chris Bottcher on various aspects of strong field electrodynamics. Most of the work centers on the atomic physics associated with the peripheral collisions of ultrarelativistic heavy atoms. The earliest, beginning in about 1979, dealt with the spontaneous emission of positrons from nuclear quasimolecules and touched briefly on the formation of axions as a possible explanation of the anomalous peaks in the spectrum. This work stimulated the extensive studies of particle production from coherent fields that laid the foundations for investigations of nuclear form factors, structure functions, and production mechanisms for the Higgs and other exotic particles. Chris conjectured that the strong fields that are present in these collisions would give rise to nonperturbative effects. Thus, during this time, Chris also worked to develop basis-spline collocation methods for solving dynamical relativistic fermions in super strong fields. This was perhaps one of the best of times for Chris; on these problems alone, he co-authored fifty articles with more than twenty different collaborators.
Date: December 31, 1994
Creator: Strayer, M.R.
Partner: UNT Libraries Government Documents Department

Quarks and gluons in hadrons and nuclei

Description: These lectures discuss the particle-nuclear interface -- a general introduction to the ideas and application of colored quarks in nuclear physics, color, the Pauli principle, and spin flavor correlations -- this lecture shows how the magnetic moments of hadrons relate to the underlying color degree of freedom, and the proton's spin -- a quark model perspective. This lecture reviews recent excitement which has led some to claim that in deep inelastic polarized lepton scattering very little of the spin of a polarized proton is due to its quarks. This lecture discusses the distribution functions of quarks and gluons in nucleons and nuclei, and how knowledge of these is necessary before some quark-gluon plasma searches can be analyzed. 56 refs., 2 figs.
Date: December 1, 1989
Creator: Close, F. E.
Partner: UNT Libraries Government Documents Department

Operator Gauge Transformations in Nonrelativistic Quantum Electrodynamics

Description: A system of nonrelativistic charged particles and radiation is canonically quantized in the Coulomb gauge and Maxwell's equations in quantum electrodynamics are derived. By requiring form invariance of the Schrodinger equation under a space and time dependent unitary transformation, operator gauge transformations on the quantized electromagnetic potentials and state vectors are introduced. These gauge transformed potentials have the same form as gauge transformations in non-Abelian gauge field theories. A gauge-invariant method for solving the time-dependent Schrodinger equation in quantum electrodynamics is given. Maxwell's equations are written in a form which holds in all gauges and which has formal similarity to the equations of motion of non-Abelian gauge fields. A gauge-invariant derivation of conservation of energy in quantum electrodynamics is given. An operator gauge transformation is made to the multipolar gauge in which the potentials are expressed in terms of the electromagnetic fields. The multipolar Hamiltonian is shown to be the minimally coupled Hamiltonian with the electromagnetic potentials in the multipolar gauge. The model of a charged harmonic oscillator in a single-mode electromagnetic field is considered as an example. The gauge-invariant procedure for solving the time-dependent Schrodinger equation is used to obtain the gauge-invariant probabilities that the oscillator is in an energy eigenstate For comparison, the conventional approach is also used to solve the harmonic oscillator problem and is shown to give gauge-dependent amplitudes.
Date: December 1982
Creator: Gray, Raymond Dale
Partner: UNT Libraries

Elementary particle theory

Description: The present state of the art in elementary particle theory is reviewed. Topics include quantum electrodynamics, weak interactions, electroweak unification, quantum chromodynamics, and grand unified theories. 113 references. (WHK)
Date: December 1, 1984
Creator: Marciano, W.J.
Partner: UNT Libraries Government Documents Department

Topics in gauge theories and the unification of elementary particle interactions

Description: We report on work done by the principal investigators and their collaborators on phenomenology of low and medium p{sub t} physics, standard model results for macroscopic systems, same sign dilepton signals from massive Majorana neutrinos, Casimir effects for charged particles, further macroscopic effects in quantum electrodynamics, and n-particle amplitudes for large n beyond the tree approximation, renormalization group analysis of unified gauge theories.
Date: December 1, 1990
Creator: Srivastava, Y.N. & Vaughn, M.T.
Partner: UNT Libraries Government Documents Department

Signatures of the various regions of the outer magnetosphere in the pitch angle distributions of energetic particles

Description: An account is given of the obervations of the pitch angle distributions of energetic particles in the near equatorial regions of the Earth's magnetosphere. The emphasis is on relating the observed distributions to the field configuration responsible for the observed effects. The observed effects relate to drift-shell splitting, to the breakdown of adiabatic guiding center motion in regions of sharp field curvature relative to partial gyro radii, to wave-particle interactions, and to moving field configurations. 39 references.
Date: December 11, 1978
Creator: West, H.I. Jr.
Partner: UNT Libraries Government Documents Department

A detailed study of nonperturbative solutions of two-body Dirac equations

Description: In quark model calculations of the meson spectrums fully covariant two-body Dirac equations dictated by Dirac's relativistic constraint mechanics gave a good fit to the entire meson mass spectrum for light quark mesons as well as heavy quark mesons with constituent world scalar and vector potentials depending on just one or two parameters. In this paper, we investigate the properties of these equations that made them work so well by solving them numerically for quantum electrodynamics (QED) and related field theories. The constraint formalism generates a relativistic quantum mechanics defined by two coupled Dirac equations on a sixteen component wave function which contain Lorentz covariant constituent potentials that are initially undetermined. An exact Pauli reduction leads to a second order relativistic Schroedinger-like equation for a reduced eight component wave function determined by an effective interaction -- the quasipotential. We first determine perturbatively to lowest order the relativistic quasipotential for the Schroedinger-like equation by comparing that form with one derived from the Bethe-Salpeter equation. Insertion of this perturbative information into the minimal interaction structures of the two-body Dirac equations then completely determines their interaction structures. Then we give a procedure for constructing the full sixteen component solution to our coupled first-order Dirac equations from a solution of the second order equation for the reduced wave function. Next, we show that a perturbative treatment of these equations yields the standard spectral results for QED and related interactions.
Date: December 1, 1992
Creator: Crater, H.W.; Becker, R.L.; Wong, C.Y. & Van Alstine, P.
Partner: UNT Libraries Government Documents Department

Summary of the Physics Opportunities Working Group

Description: The Physics Opportunities Working Group was convened with the rather general mandate to explore physic opportunities that may arise as new accelerator technologies and facilities come into play. Five topics were considered during the workshop: QED at critical field strength, novel positron sources, crystal accelerators, suppression of beamstrahlung, and muon colliders. Of particular interest was the sense that a high energy muon collider might be technically feasible and certainly deserves serious study.
Date: December 1, 1992
Creator: Chen, Pisin (Stanford Linear Accelerator Center, Menlo Park, CA (United States)) & McDonald, K.T. (Princeton Univ., NJ (United States). Joseph Henry Labs.)
Partner: UNT Libraries Government Documents Department