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Higher order corrections to energy levels of muonic atoms

Description: In order to facilitate the analysis of muonic x-ray spectra, the results of numerical computations of all higher order quantum electrodynamical corrections to the energy levels of muonic atoms are presented in tabular and graphical form. These corrections include the vacuum polarization corrections caused by emission and reabsorption of virtual electron pairs to all orders, including ''double-bubble'' and ''cracked-egg'' diagrams. An estimate of the Delbruecke scattering-type correction is presented. The Lamb-shift (second- and fourth-order vertex) corrections have been calculated including the correction for the anomalous magnetic moment of the muon. The relativistic nuclear motion (or recoil) correction as well as the correction caused by the screening of the atomic electrons is presented in graphs. For the sake of completeness a graph of the nuclear polarization as computed on the basis of Chen's approach has been included. All calculations were made with a two-parameter Fermi distribution of the nuclear charge density. 7 figures, 23 references. (auth)
Date: August 1, 1975
Creator: Rinker, G.A. Jr. & Steffen, R.M.
Partner: UNT Libraries Government Documents Department

QED Corrections to the 4p - 4d Transition Energies of Copperlike Heavy Ions

Description: Quantum electrodynamic (QED) corrections to 4p-4d transition energies of several copper-like ions with Z = 70-92 are calculated non-perturbatively in strong external fields to all orders in binding corrections. Dirac-Kohn-Sham potentials are used to account for screening and core-relaxation effects. For the 4p{sub 1/2}-4d{sub 3/2} transition in copperlike bismuth, thorium and uranium, results are in good agreement with empirical QED corrections deduced from differences between transition energies obtained from recent high-precision electron-beam ion-trap (EBIT) measurements and those calculated with the relativistic many-body perturbation theory (RMBPT). These comparisons provide sensitive tests of QED corrections for high angular momentum states in many-electron heavy ions and illustrate the importance of core-relaxation corrections. Comparisons are also made with other theories and with experiment on the 4s-4p transition energies of high-Z Cu-like ions as accuracy checks of the present RMBPT and QED calculations.
Date: August 21, 2006
Creator: Chen, M H; Cheng, K T; Johnson, W R & Sapirstein, J
Partner: UNT Libraries Government Documents Department

Shielding of External Magnetic Perturbations By Torque In Rotating Tokamak Plasmas

Description: The imposition of a nonaxisymmetric magnetic perturbation on a rotating tokamak plasma requires energy and toroidal torque. Fundamental electrodynamics implies that the torque is essentially limited and must be consistent with the external response of a plasma equilibrium ƒ = j x B. Here magnetic measurements on National Spherical Torus eXperiment (NSTX) device are used to derive the energy and the torque, and these empirical evaluations are compared with theoretical calculations based on perturbed scalar pressure equilibria ƒ = ∇p coupled with the theory of nonambipolar transport. The measurement and the theory are consistent within acceptable uncertainties, but can be largely inconsistent when the torque is comparable to the energy. This is expected since the currents associated with the torque are ignored in scalar pressure equilibria, but these currents tend to shield the perturbation.
Date: August 24, 2009
Creator: Jong-Kyu Park, Allen H. Boozer, Jonathan E. Menard, Stefan P. Gerhardt, and Steve A. Sabbagh
Partner: UNT Libraries Government Documents Department

Progress Report No. 50 for the Period June 1, 1957 Through August 31, 1957

Description: Progress is reported in fission elements chemistry, organic and inorganic nuclear chemistry, cosmic ray research, high-energy accelerator experimentation and physics, bubble chamber experimentation, and theoretical physics. Considerable attention was given to the ionization of mineral acids and hydrogen haloraetallates in inorganic solvents and to anion exchnnge behavior in metal complexes. Studies of various chemical reaction mechanisms were continued. The self-energy of a Dirac particle coupled through its charge with the electromagnetic field was investigated without perturbation theory. (For preceding period see AECU-3580.) (D.E.B.)
Date: August 31, 1957
Partner: UNT Libraries Government Documents Department

A lattice formulation of chiral gauge theories

Description: We present a method for implementing gauge theories of chiral fermions on the lattice. Discussed topics include: the lattice as a UV regulator, a chiral QED model, modification of the fermion determinant, large gauge-field momenta, and a non-perturbative problem.
Date: August 1, 1996
Creator: Bodwin, G.T.
Partner: UNT Libraries Government Documents Department

Nonperturbative renormalization of QED in light-cone quantization

Description: As a precursor to work on QCD, we study the dressed electron in QED non-perturbatively. The calculational scheme uses an invariant mass cutoff, discretized light cone quantization, a Tamm-Dancoff truncation of the Fock space, and a small photon mass. Nonperturbative renormalization of the coupling and electron mass is developed.
Date: August 1, 1996
Creator: Hiller, J.R. & Brodsky, S.J.
Partner: UNT Libraries Government Documents Department

NOVEL SIGNAL PROCESSING WITH NONLINEAR TRANSMISSION LINES

Description: Nonlinear dielectrics offer uniquely strong and tunable nonlinearities that make them attractive for current devices (for example, frequency-agile microwave filters) and for future signal-processing technologies. The goal of this project is to understand pulse propagation on nonlinear coplanar waveguide prototype devices. We have performed time-domain and frequency-domain experimental studies of simple waveguide structures and pursued a theoretical understanding of the propagation of signals on these nonlinear waveguides. To realistically assess the potential applications, we used a time-domain measurement and analysis technique developed during this project to perform a broadband electrodynamics characterization in terms of nonlinear, dispersive, and dissipative effects. We completed a comprehensive study of coplanar waveguides made from high-temperature superconducting thin-film YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} electrodes on nonlinear dielectric single-crystal SrTiO{sub 3} substrates. By using parameters determined from small-signal (linear) transmission characteristics of the waveguides, we develop a model equation that successfully predicts and describes large-signal (nonlinear) behavior.
Date: August 1, 2000
Creator: REAGOR, D. & AL, ET
Partner: UNT Libraries Government Documents Department

Residual meson-meson interaction from lattice gauge simulation in a simple QED{sub 2+1} model

Description: The residual interaction for a meson-meson system is computed utilizing the cumulant, or cluster, expansion of the momentum-space time correlation matrix. The cumulant expansion serves to define asymptotic, or free, meson-meson operators. The definition of an effective interaction is then based on a comparison of the full (interacting) and the free (noninteracting) time correlation matrices. The proposed method, which may straight forwardly be transcribed to other hadron-hadron systems, here is applied to a simple 2+1 dimensional U(1) lattice gauge model tuned such that it is confining. Fermions are treated in the staggered scheme. The effective interaction exhibits a repulsive core and attraction at intermediate relative distances. These findings are consistent with an earlier study of the same model utilizing L{umlt u}scher's method where scattering phase shifts are obtained directly.
Date: August 1, 1995
Creator: Canosa, J. & Fiebig, H.
Partner: UNT Libraries Government Documents Department

Enigmatic electrons, photons, and ``empty`` waves

Description: A spectroscopic analysis is made of electrons and photons from the standpoint of physical realism. In this conceptual framework, moving particles are portrayed as localized entities which are surrounded by ``empty`` waves. A spectroscopic model for the electron Stands as a guide for a somewhat similar, but in essential respects radically different, model for the photon. This leads in turn to a model for the ``zeron``. the quantum of the empty wave. The properties of these quanta mandate new basis states, and hence an extension of our customary framework for dealing with them. The zeron wave field of a photon differs in one important respect from the standard formalism for an electromagnetic wave. The vacuum state emerges as more than just a passive bystander. Its polarization properties provide wave stabilization, particle probability distributions, and orbit quantization. Questions with regard to special relativity are discussed.
Date: August 22, 1995
Creator: MacGregor, M.H.
Partner: UNT Libraries Government Documents Department

Capillary Electrophoresis - Optical Detection Systems

Description: Molecular recognition systems are developed via molecular modeling and synthesis to enhance separation performance in capillary electrophoresis and optical detection methods for capillary electrophoresis. The underpinning theme of our work is the rational design and development of molecular recognition systems in chemical separations and analysis. There have been, however, some subtle and exciting shifts in our research paradigm during this period. Specifically, we have moved from mostly separations research to a good balance between separations and spectroscopic detection for separations. This shift is based on our perception that the pressing research challenges and needs in capillary electrophoresis and electrokinetic chromatography relate to the persistent detection and flow rate reproducibility limitations of these techniques (see page 1 of the accompanying Renewal Application for further discussion). In most of our work molecular recognition reagents are employed to provide selectivity and enhance performance. Also, an emerging trend is the use of these reagents with specially-prepared nano-scale materials. Although not part of our DOE BES-supported work, the modeling and synthesis of new receptors has indirectly supported the development of novel microcantilevers-based MEMS for the sensing of vapor and liquid phase analytes. This fortuitous overlap is briefly covered in this report. Several of the more significant publications that have resulted from our work are appended. To facilitate brevity we refer to these publications liberally in this progress report. Reference is also made to very recent work in the Background and Preliminary Studies Section of the Renewal Application.
Date: August 6, 2001
Creator: Sepaniak, M. J.
Partner: UNT Libraries Government Documents Department

THE ELECTROMAGNETIC PINCH EFFECT FOR SPACE PROPULSION

Description: The phenomenon of the electromagnetic pinch effect is used to accelerate ionized gases for space propulsion. Electrical energy, initially stored in capacitors, is discharged across two nozzle shaped electrodes wherein the radial pinch is converted to axial motion of the effected gases instead of confinement at the axis. The gas dynamics of a pinch using the hydrodynamical model of a msgnetic piston driving a shock wave is combined with the electrodynamics of the circuit to calculate the discharge behavior. Experiments on three different electrode designs are discussed and results compared with calculated values. Results are applied to one particular space propulsion system consisting of a nuclear energy source, a space radiator, a turbine-generator, capacitor, and a pinch tube. The specific mission analyzed is a one-way unmanned flight to a Mars orbit, starting from an Earth orbit. (auth)
Date: August 1, 1959
Creator: Kunen, A.E. & McIlroy, W.
Partner: UNT Libraries Government Documents Department

Quantum electrodynamics with complex fermion mass

Description: The quantum electrodynamics (QED) with a complex fermion mass -- that is, a fermion mass with a chiral phase -- is restudied, together with its chirally rotated version. We show how fake electric dipole moment can be obtained and how to avoid it. 10 refs.
Date: August 1, 1991
Creator: McKellar, B.J.H. (Melbourne Univ., Parkville (Australia). School of Physics) & Wu, D.D. (Melbourne Univ., Parkville (Australia). School of Physics Academia Sinica, Beijing, BJ (China). Inst. of High Energy Physics Superconducting Super Collider Lab., Dallas, TX (United States))
Partner: UNT Libraries Government Documents Department

Family number non-conservation induced by the supersymmetric mixing of scalar leptons

Description: The most egregious aspect of (N = 1) supersymmetric theories is that each particle state is accompanied by a 'super-partner', a state with identical quantum numbers save that it differs in spin by one half unit. For the leptons these are scalars and are called ''sleptons'', or scalar leptons. These consist of the charged sleptons (selectron, smuon, stau) and the scalar neutrinos ('sneutrinos'). We examine a model of supersymmetry with soft breaking terms in the electroweak sector. Explicit mixing among the scalar leptons results in a number of effects, principally non-conservation of lepton family number. Comparison with experiment permits us to place constraints upon the model. 49 refs., 12 figs.
Date: August 1, 1987
Creator: Levine, M.J.S.
Partner: UNT Libraries Government Documents Department

Theory and phenomenology of strong and weak interaction high energy physics

Description: This paper deals with research being conducted at the University of Arizona in the theory of strong and weak interactions. Topics in Quantum chromodynamics, quantum electrodynamics, symmetry principle, hadronic structure of the photon and other are discussed. (LSP)
Date: August 29, 1990
Creator: Carruthers, P. & Thews, R.L.
Partner: UNT Libraries Government Documents Department

Measurement of the 2 sup 2 S sub 1/2 -2 sup 2 P sub 3/2 fine structure interval in muonium

Description: The (2{sup 2}S{sub 1/2} {minus} 2{sup 2}P{sub 3/2}) fine structure transition in muonium has been observed for the first time. The measured value is 9895 {sub {minus}30}{sup {plus}35}MHz. This measurement, when included with the theoretical value for the 2{sup 2}P{sub 1/2} {minus} 2{sup 2}P{sub 3/2} fine structure interval, gives a value for the Lamb shift (2{sup 2}S{sub 1/2} {minus} 2{sup 2}P{sub 1/2}) independent of previous direct measurements. From the theoretical value for the fine structure interval, 10921.833(3) MHz, the value for the Lamb shift determined from this experiment is 1027{sub {minus}35}{sup {plus}30} MHz and is in agreement with the prediction of quantum electrodynamics (QED) of 1047.5(3) MHz. Previous experimental values for the Lamb shift (2{sup 2}S{sub 1/2} {minus}2{sup 2}P{sub 1/2}) in muonium are 1070{sub {minus}15}{sup {plus} 12} MHz and 1042{sub {minus}23}{sup {plus}21} MHz. Combining this result with these previous results gives a new experimental value of 1058{sub {minus}12}{sup {plus}10} for the Lamb shift in muonium. Muonium, the bound state of two structureless leptons ({mu}{sup +}e{sup {minus}}), is an ideal system for testing bound state QED because of the lack of hadronic structure as exists in the hydrogen system. The measurement makes use of the techniques of atomic beam microwave spectroscopy. Muonium atoms ({mu}{sup +}e{sup {minus}}) in the 2S states are produced by the beam-foil technique at the Clinton P. Anderson Meson Physics Facility with a low momentum, sub-surface muon beam. A variable frequency microwave field is applied to drive the atoms from the 2S to the 2P states, with the subsequent observation of the Lyman alpha photon from the decay of the 2P state to the 1S ground state. The frequency is varied from 9.0--11.0 GHz, driving the F = 0 {yields} F = 1, F = 1, F = 1 and F = 1 {yields} F = 2 transitions.
Date: August 1, 1990
Creator: Kettell, S.H.
Partner: UNT Libraries Government Documents Department

Studies of nonlinear electrodynamics of high-temperature superconductors

Description: Nonlinear electrodynamics of high-{Tc} superconductors are studied both theoretically and experimentally. For powdered samples, a novel model is presented in which the metallographically observed superconducting grains in the powder are modeled as superconducting current loops of various areas with weak links. Surprising harmonic generation behavior in an arc field, H{sub 1} cos({omega}t), is predicted by the model; the power at high harmonics show sharp dips almost periodic in a superposing dc magnetic field, revealing flux quantization in the prototype loops in the model. Such oscillation of the harmonic power in dc magnetic field P{sub nf}(H{sub dc}), is indeed experimentally observed in powdered YBa{sub 2}Cu{sub 3}O{sub 7}. Other experimental aspects also agree with model predictions. For bulk sintered cylindrical samples, a generalized critical state model is presented. In this model, the nonlinear electrodynamics are due to flux-pinning, somewhat similar to low-temperature type-II superconductors, but with a more generalized critical current densities' dependence on magnetic field -- J{sub c}(H){approximately}H{sub local}{sup -{beta}}, with {beta} being an adjustable parameter. Experiments in ac and dc magnetic fields on a sintered cylindrical rod of YBa{sub 2}Cu{sub 3}O{sub 7} yield unambiguous evidence of independent inter- and intragranular contributions to the complex harmonic permeability {tilde {mu}}{sub n} = {mu}{prime}{sub n} -i{mu}{double prime}{sub n}. Temperature- dependence measurements reveal that, while the intragranular supercurrents disappear at {Tc}{ge}91.2 K, the intergranular supercurrents disappear at T{ge}86.6 K. This result is, to our knowledge, the first clear measurement of the phase-locking temperature of the 3-D matrix formed by YBa{sub 2}Cu{sub 3}O{sub 7} grains, which are in electrical contact with one another through weak links.
Date: August 1, 1991
Creator: Lam, Quan-Chiu H.
Partner: UNT Libraries Government Documents Department

Study of four-lepton final states in electron-positron interactions at 29 GeV

Description: This thesis presents a study of electron-positron scattering to four light leptons. The motivations behind it are twofold. Firstly, the study is a test of the theory of electron-positron interactions to 4th order in the fine structure constant {alpha}. A deviation from the theory could indicate the existence of a heavy new particle. Secondly, a measurement of these processes may prove useful in the understanding of other QED-type reactions. The method for simulating the four-lepton processes by the Monte Carlo event generator of Berends, Daverveldt and Kleiss is described. Theoretical predictions are compared to data from the Mark II and HRS experiments at the PEP storage ring. The observed events consist of four leptons at large angles. Data for all three e{sup +}e{sup -}e{sup +}e{sup -}, e{sup +}e{sup -}{mu}{sup +}{mu}{sup -} and {mu}{sup +}{mu}{sup -}{mu}{sup +}{mu}{sup -} processes are well described by the QED Monte Carlo calculation. The various kinematical distributions are in good agreement with QED to order {alpha}{sup 4}. 18 refs., 64 figs., 19 tabs.
Date: August 1, 1989
Creator: Petradza, A.
Partner: UNT Libraries Government Documents Department

Studies of nonlinear electrodynamics of high-temperature superconductors

Description: Nonlinear electrodynamics of high-{Tc} superconductors are studied both theoretically and experimentally. For powdered samples, a novel model is presented in which the metallographically observed superconducting grains in the powder are modeled as superconducting current loops of various areas with weak links. Surprising harmonic generation behavior in an arc field, H{sub 1} cos({omega}t), is predicted by the model; the power at high harmonics show sharp dips almost periodic in a superposing dc magnetic field, revealing flux quantization in the prototype loops in the model. Such oscillation of the harmonic power in dc magnetic field P{sub nf}(H{sub dc}), is indeed experimentally observed in powdered YBa{sub 2}Cu{sub 3}O{sub 7}. Other experimental aspects also agree with model predictions. For bulk sintered cylindrical samples, a generalized critical state model is presented. In this model, the nonlinear electrodynamics are due to flux-pinning, somewhat similar to low-temperature type-II superconductors, but with a more generalized critical current densities` dependence on magnetic field -- J{sub c}(H){approximately}H{sub local}{sup -{beta}}, with {beta} being an adjustable parameter. Experiments in ac and dc magnetic fields on a sintered cylindrical rod of YBa{sub 2}Cu{sub 3}O{sub 7} yield unambiguous evidence of independent inter- and intragranular contributions to the complex harmonic permeability {tilde {mu}}{sub n} = {mu}{prime}{sub n} -i{mu}{double_prime}{sub n}. Temperature- dependence measurements reveal that, while the intragranular supercurrents disappear at {Tc}{ge}91.2 K, the intergranular supercurrents disappear at T{ge}86.6 K. This result is, to our knowledge, the first clear measurement of the phase-locking temperature of the 3-D matrix formed by YBa{sub 2}Cu{sub 3}O{sub 7} grains, which are in electrical contact with one another through weak links.
Date: August 1, 1991
Creator: Lam, Quan-Chiu H.
Partner: UNT Libraries Government Documents Department