WorldWideScience

Sample records for calculations including coulomb

  1. Three- and Four-Body Scattering Calculations including the Coulomb Force

    OpenAIRE

    Deltuva, A

    2009-01-01

    The method of screening and renormalization for including the Coulomb interaction in the framework of momentum-space integral equations is applied to the three- and four-body nuclear reactions. The Coulomb effect on the observables and the ability of the present nuclear potential models to describe the experimental data is discussed.

  2. Coulomb correction calculations of pp Bremsstrahlung

    International Nuclear Information System (INIS)

    The effects of the Coulomb interaction upon the photon cross section and analyzing power from pp Bremsstrahlung have been studied in detail. Off-shell properties of the Coulomb T matrices have been considered but the associated, Coulomb modified, hadronic T matrices are important elements in any analyses of low energy, forward proton scattering data. At the lowest energy considered (5 MeV), the full calculations gave cross sections that were half the size of those found without Coulomb effects or with a simple model approximation to them. With increasing energy, the cross sections varied to those characteristic of magnetic interaction dominance and the specific differences due to Coulomb effects diminished. 47 refs., 7 figs

  3. Relativistic study of the energy-dependent Coulomb potential including Coulomb-like tensor interaction

    CERN Document Server

    Hamzavi, Majid

    2012-01-01

    The exact Dirac equation for the energy-dependent Coulomb (EDC) potential including a Coulomb-like tensor (CLT) potential has been studied in the presence of spin and pseudospin (p-spin) symmetries with arbitrary spin-orbit quantum number The energy eigenvalues and corresponding eigenfunctions are obtained in the framework of asymptotic iteration method (AIM). Some numerical results are obtained in the presence and absence of EDC and CLT potentials.

  4. Challenges in calculating molecular systems with Coulomb interactions

    Science.gov (United States)

    Kirnosov, Nikita; Sharkey, Keeper; Adamowicz, Ludwik

    2014-03-01

    The highly accurate quantum mechanical calculations are not only crucial for high-resolution experimental data verification, but may also serve as a guide in the field of exotic systems exploration. Including all non-relativistic effects in a single-step variational approach and rigorously separating out the center of mass motion allows us to build a reliable model for calculating bound states of molecular systems with Coulomb interactions. In these calculations the wave function of the system is expanded in terms of explicitly correlated Gaussian (ECG) basis functions. Examples of calculations of energies and other properties of some molecular systems will be presented.

  5. Poisson Green's function method for increased computational efficiency in numerical calculations of Coulomb coupling elements

    Science.gov (United States)

    Zimmermann, Anke; Kuhn, Sandra; Richter, Marten

    2016-01-01

    Often, the calculation of Coulomb coupling elements for quantum dynamical treatments, e.g., in cluster or correlation expansion schemes, requires the evaluation of a six dimensional spatial integral. Therefore, it represents a significant limiting factor in quantum mechanical calculations. If the size or the complexity of the investigated system increases, many coupling elements need to be determined. The resulting computational constraints require an efficient method for a fast numerical calculation of the Coulomb coupling. We present a computational method to reduce the numerical complexity by decreasing the number of spatial integrals for arbitrary geometries. We use a Green's function formulation of the Coulomb coupling and introduce a generalized scalar potential as solution of a generalized Poisson equation with a generalized charge density as the inhomogeneity. That enables a fast calculation of Coulomb coupling elements and, additionally, a straightforward inclusion of boundary conditions and arbitrarily spatially dependent dielectrics through the Coulomb Green's function. Particularly, if many coupling elements are included, the presented method, which is not restricted to specific symmetries of the model, presents a promising approach for increasing the efficiency of numerical calculations of the Coulomb interaction. To demonstrate the wide range of applications, we calculate internanostructure couplings, such as the Förster coupling, and illustrate the inclusion of symmetry considerations in the method for the Coulomb coupling between bound quantum dot states and unbound continuum states.

  6. A unitarized meson model including color Coulomb interaction

    International Nuclear Information System (INIS)

    Ch. 1 gives a general introduction into the problem field of the thesis. It discusses in how far the internal structure of mesons is understood theoretically and which models exist. It discusses from a phenomenological point of view the problem of confinement indicates how quark models of mesons may provide insight in this phenomenon. In ch. 2 the formal theory of scattering in a system with confinement is given. It is shown how a coupled channel (CC) description and the work of other authors fit into this general framework. Explicit examples and arguments are given to support the CC treatment of such a system. In ch. 3 the full coupled-channel model as is employed in this thesis is presented. On the basis of arguments from the former chapters and the observed regularities in the experimental data, the choices underlying the model are supported. In this model confinement is described with a mass-dependent harmonic-oscillator potential and the presence of open (meson-meson) channels plays an essential role. In ch. 4 the unitarized model is applied to light scalar meson resonances. In this regime the contribution of the open channels is considerable. It is demonstrated that the model parameters as used for the description of the pseudo-scalar and vector mesons, unchanged can be used for the description of these mesons. Ch. 5 treats the color-Coulomb interaction. There the effect of the Coulomb interaction is studied in simple models without decay. The results of incorporating the color-Coulomb interaction into the full CC model are given in ch.6. Ch. 7 discusses the results of the previous chapters and the present status of the model. (author). 182 refs.; 16 figs.; 33 tabs

  7. Treating Coulomb exchange contributions in relativistic mean field calculations: why and how

    CERN Document Server

    Van Giai, Nguyen; Gu, Huai-Qiang; Long, Wenhui; Meng, Jie

    2014-01-01

    The energy density functional (EDF) method is very widely used in nuclear physics, and among the various existing functionals those based on the relativistic Hartree (RH) approximation are very popular because the exchange contributions (Fock terms) are numerically rather onerous to calculate. Although it is possible to somehow 'mock up' the effects of meson-induced exchange terms by adjusting the meson-nucleon couplings, the lack of Coulomb exchange contributions hampers the accuracy of predictions. In this note, we show that the Coulomb exchange effects can be easily included with a good accuracy in a perturbative approach. Therefore, it would be desirable for future relativistic EDF models to incorporate Coulomb exchange effects, at least to some order of perturbation.

  8. Quantum calculation of Coulomb reorientation and near-barrier fusion

    OpenAIRE

    Simenel, Cédric; Bender, Michael; Chomaz, P.; Duguet, Thomas; de France, G.

    2006-01-01

    6pages, 2 figures. Proceeding of FUSION06 International audience We investigate the role of deformation on the fusion probability around the barrier using the Time-Dependent Hartree-Fock theory with a full Skyrme force. We obtain a distribution of fusion probabilities around the nominal barrier due to the different contributions of the various orientations of the deformed nucleus at the touching point. It is also shown that the long range Coulomb reorientation reduces the fusion probabi...

  9. The accuracy of the Gaussian-and-finite-element-Coulomb (GFC) method for the calculation of Coulomb integrals

    Science.gov (United States)

    Przybytek, Michal; Helgaker, Trygve

    2013-08-01

    We analyze the accuracy of the Coulomb energy calculated using the Gaussian-and-finite-element-Coulomb (GFC) method. In this approach, the electrostatic potential associated with the molecular electronic density is obtained by solving the Poisson equation and then used to calculate matrix elements of the Coulomb operator. The molecular electrostatic potential is expanded in a mixed Gaussian-finite-element (GF) basis set consisting of Gaussian functions of s symmetry centered on the nuclei (with exponents obtained from a full optimization of the atomic potentials generated by the atomic densities from symmetry-averaged restricted open-shell Hartree-Fock theory) and shape functions defined on uniform finite elements. The quality of the GF basis is controlled by means of a small set of parameters; for a given width of the finite elements d, the highest accuracy is achieved at smallest computational cost when tricubic (n = 3) elements are used in combination with two (γH = 2) and eight (γ1st = 8) Gaussians on hydrogen and first-row atoms, respectively, with exponents greater than a given threshold (α _min^G=0.5). The error in the calculated Coulomb energy divided by the number of atoms in the system depends on the system type but is independent of the system size or the orbital basis set, vanishing approximately like d4 with decreasing d. If the boundary conditions for the Poisson equation are calculated in an approximate way, the GFC method may lose its variational character when the finite elements are too small; with larger elements, it is less sensitive to inaccuracies in the boundary values. As it is possible to obtain accurate boundary conditions in linear time, the overall scaling of the GFC method for large systems is governed by another computational step—namely, the generation of the three-center overlap integrals with three Gaussian orbitals. The most unfavorable (nearly quadratic) scaling is observed for compact, truly three-dimensional systems

  10. Interatomic Coulombic decay widths of helium trimer: Ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Kolorenč, Přemysl, E-mail: kolorenc@mbox.troja.mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, Institute of Theoretical Physics, V Holešovičkách 2, 180 00 Prague (Czech Republic); Sisourat, Nicolas [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France)

    2015-12-14

    We report on an extensive study of interatomic Coulombic decay (ICD) widths in helium trimer computed using a fully ab initio method based on the Fano theory of resonances. Algebraic diagrammatic construction for one-particle Green’s function is utilized for the solution of the many-electron problem. An advanced and universal approach to partitioning of the configuration space into discrete states and continuum subspaces is described and employed. Total decay widths are presented for all ICD-active states of the trimer characterized by one-site ionization and additional excitation of an electron into the second shell. Selected partial decay widths are analyzed in detail, showing how three-body effects can qualitatively change the character of certain relaxation transitions. Previously unreported type of three-electron decay processes is identified in one class of the metastable states.

  11. Calculation of Coulomb energies for uniform charge distributions of arbitrary shape

    International Nuclear Information System (INIS)

    Three distinct surface-integral formulas are derived for calculating the Coulomb energies of uniform charge distributions of arbitrary shape. Of particular interest is an equation obtained by applying Gauss' divergence theorem twice. It is shown that this equation can be simply transformed to another expression which has been widely used for calculating Coulomb energies, with this derivation implying a third formula. The three formulas are also expressed in cylindrical coordinates for charge distributions possessing axial symmetry. For such shapes, numerical studies are presented showing the computational times and errors involved in calculating the Coulomb energies and generalized forces using Gaussian-Legendre quadrature formulas. It is shown that the double-divergence-derived formula is faster and more accurate than the other two surface-integral formulas and other formulas used in the literature

  12. Algebraic Calculation of the Energy Eigenvalues for the Nondegenerate Three-Dimensional Kepler-Coulomb Potential

    Directory of Open Access Journals (Sweden)

    Yannis Tanoudis

    2011-06-01

    Full Text Available In the three-dimensional flat space, a classical Hamiltonian, which has five functionally independent integrals of motion, including the Hamiltonian, is characterized as superintegrable. Kalnins, Kress and Miller (J. Math. Phys. 48 (2007, 113518, 26 pages have proved that, in the case of nondegenerate potentials, i.e. potentials depending linearly on four parameters, with quadratic symmetries, posses a sixth quadratic integral, which is linearly independent of the other integrals. The existence of this sixth integral imply that the integrals of motion form a ternary quadratic Poisson algebra with five generators. The superintegrability of the generalized Kepler-Coulomb potential that was investigated by Verrier and Evans (J. Math. Phys. 49 (2008, 022902, 8 pages is a special case of superintegrable system, having two independent integrals of motion of fourth order among the remaining quadratic ones. The corresponding Poisson algebra of integrals is a quadratic one, having the same special form, characteristic to the nondegenerate case of systems with quadratic integrals. In this paper, the ternary quadratic associative algebra corresponding to the quantum Verrier-Evans system is discussed. The subalgebras structure, the Casimir operators and the the finite-dimensional representation of this algebra are studied and the energy eigenvalues of the nondegenerate Kepler-Coulomb are calculated.

  13. Coulomb Energy of Nuclei

    OpenAIRE

    Shaginyan, V. R.

    2002-01-01

    The density functional determining the Coulomb energy of nuclei is calculated to the first order in $e^2$. It is shown that the Coulomb energy includes three terms: the Hartree energy; the Fock energy; and the correlation Coulomb energy (CCE), which contributes considerably to the surface energy, the mass difference between mirror nuclei, and the single-particle spectrum. A CCE-based mechanism of a systematic shift of the single-particle spectrum is proposed. A dominant contribution to the CC...

  14. Relativistic symmetry of position-dependent mass particles in a Coulomb field including tensor interaction

    Institute of Scientific and Technical Information of China (English)

    M.Eshghi; M.Hamzavi; S.M.Ikhdair

    2013-01-01

    The spatially-dependent mass Dirac equation is solved exactly for attractive scalar and repulsive vector Coulomb potentials,including a tensor interaction under the spin and pseudospin symmetric limits.Closed forms of the energy eigenvalue equation and wave functions are obtained for arbitrary spin-orbit quantum number κ.Some numerical results are also given,and the effect of tensor interaction on the bound states is presented.It is shown that tensor interaction removes the degeneracy between two states in the spin doublets.We also investigate the effects of the spatially-dependent mass on the bound states under spin symmetric limit conditions in the absence of tensor interaction.

  15. Solutions of Dirac Equation for Generalized Hyperbolical Potential Including Coulomb-Like Tensor Potential with Spin Symmetry

    International Nuclear Information System (INIS)

    We solved the Dirac equation for the generalized hyperbolical potential including a Coulomb-like tensor potential under spin symmetry with spin-orbit quantum number k. We used the parametric generalization of the Nikiforov-Uvarov method to obtain the energy eigenvalue and the unnormalized wave function. (author)

  16. First principles calculation of the effect of Coulomb collisions in partially ionized gases

    CERN Document Server

    Donko, Z

    2014-01-01

    Coulomb collisions, at appreciable ratios (\\eta) of the electron to the neutral particle density, influence significantly the electron kinetics in particle swarms and in plasmas of gas discharges. This paper introduces a combination of Molecular Dynamics and Monte Carlo simulation techniques, to provide a novel, approximation free, first principles calculation method for the velocity distribution function of electrons, and related swarm characteristics, at arbitrary \\eta. Simulation results are presented for electrons in argon gas, for density ratios between zero and 0.1, representing the limits of a negligible electron density and an almost complete Maxwellization of the velocity distribution function, respectively.

  17. Can Coulomb Sturmians Be Used as a Basis for N-Electron Molecular Calculations?

    DEFF Research Database (Denmark)

    Avery, John Scales; Avery, James Emil

    2009-01-01

    A method is proposed for using isoenergetic configurations formed from many-center Coulomb Sturmians as a basis for calculations on N-electron molecules. Such configurations are solutions to an approximate N-electron Schrödinger equation with a weighted potential, and they are thus closely...... analogous to the Goscinskian configurations that we have used previously to study atomic spectra. We show that when the method is applied to diatomic molecules, all of the relevant integrals are pure functions of the parameter s=kR, and therefore they can be evaluated once and for all and stored....

  18. An ab-initio calculation of the Coulomb explosion of N2 after heavy-ion bombardment

    International Nuclear Information System (INIS)

    Self-consistent-field calculations for the total potential energy of highly ionized N2 molecules are presented. These calculations are compared to the experimentally observed energy released in the Coulomb explosion of ionized N2 molecules created after collision with fast heavy ions. The most important electronic states of the fragment ions are determined. (Auth.)

  19. Coulomb energy of nuclei

    International Nuclear Information System (INIS)

    The density functional determining the Coulomb energy of nuclei is calculated to the first order in e2. It is shown that the Coulomb energy includes three terms: the Hartree energy; the Fock energy; and the correlation Coulomb energy (CCE), which contributes considerably to the surface energy, the mass difference between mirror nuclei, and the single-particle spectrum. A CCE-based mechanism of a systematic shift of the single-particle spectrum is proposed. A dominant contribution to the CCE is shown to come from the surface region of nuclei. The CCE effect on the calculated proton drip line is examined, and the maximum charge Z of nuclei near this line is found to decrease by 2 or 3 units. The effect of Coulomb interaction on the effective proton mass is analyzed

  20. Coulomb Energy of Nuclei

    CERN Document Server

    Shaginyan, V R

    2001-01-01

    The density functional determining the Coulomb energy of nuclei is calculated to the first order in $e^2$. It is shown that the Coulomb energy includes three terms: the Hartree energy; the Fock energy; and the correlation Coulomb energy (CCE), which contributes considerably to the surface energy, the mass difference between mirror nuclei, and the single-particle spectrum. A CCE-based mechanism of a systematic shift of the single-particle spectrum is proposed. A dominant contribution to the CCE is shown to come from the surface region of nuclei. The CCE effect on the calculated proton drip line is examined, and the maximum charge $Z$ of nuclei near this line is found to decrease by 2 or 3 units. The effect of Coulomb interaction on the effective proton mass is analyzed.

  1. The MV Model of the Color Glass Condensate for a Finite Number of Sources Including Coulomb Interactions

    CERN Document Server

    McLerran, Larry

    2016-01-01

    We modify the McLerran-Venugopalan model to include only a finite number of sources of color charge. We argue that Coulombic interactions between these color charges generates a source-source correlation function that properly includes the effects of color charge screening, a generalization of Debye screening for the Color Glass Condensate. Such a model may be useful for computing angular harmonics of flow measured in high energy hadron collisions for small systems. In this paper we provide a basic formulation of the problem on a lattice.

  2. Algebraic calculation of the energy eigenvalues for the non degenerate three dimensional Kepler Coulomb potential

    CERN Document Server

    Tanoudis, Y

    2011-01-01

    In the three dimensional flat space, a classical Hamiltonian, which has five functionally independent integrals of motion, including the Hamiltonian, is characterized as superintegrable. Kalnins, Kress and Miller (J. Math. Phys. 48, 113518 (2007)) have proved that, in the case of non degenerate potentials, i.e potentials depending linearly on four parameters, with quadratic symmetries, posses a sixth quadratic integral, which is linearly independent of the other integrals. The existence of this sixth integral imply that the integrals of motion form a ternary quadratic Poisson algebra with five generators. The superintegrability of the generalized Kepler Coulomb potential that was investigated by Verrier and Evans (J. Math. Phys. 49, 022902 (2008)) is a special case of superintegrable system, having two independent integrals of motion of fourth order among the remaining quadratic ones. The corresponding Poisson algebra of integrals is a quadratic one, having the same special form, characteristic to the non deg...

  3. Approximate bound state solutions of Dirac equation with Hulth\\'{e}n potential including Coulomb-like tensor potential

    OpenAIRE

    Sameer M. Ikhdair; Sever, Ramazan

    2010-01-01

    We solve the Dirac equation approximately for the attractive scalar $S(r)$ and repulsive vector $V(r)$ Hulth\\'{e}n potentials including a Coulomb-like tensor potential with arbitrary spin-orbit coupling quantum number $\\kappa .$ In the framework of the spin and pseudospin symmetric concept, we obtain the analytic energy spectrum and the corresponding two-component upper- and lower-spinors of the two Dirac particles by means of the Nikiforov-Uvarov method in closed form. The limit of zero tens...

  4. A parallel code to calculate rate-state seismicity evolution induced by time dependent, heterogeneous Coulomb stress changes

    Science.gov (United States)

    Cattania, C.; Khalid, F.

    2016-09-01

    The estimation of space and time-dependent earthquake probabilities, including aftershock sequences, has received increased attention in recent years, and Operational Earthquake Forecasting systems are currently being implemented in various countries. Physics based earthquake forecasting models compute time dependent earthquake rates based on Coulomb stress changes, coupled with seismicity evolution laws derived from rate-state friction. While early implementations of such models typically performed poorly compared to statistical models, recent studies indicate that significant performance improvements can be achieved by considering the spatial heterogeneity of the stress field and secondary sources of stress. However, the major drawback of these methods is a rapid increase in computational costs. Here we present a code to calculate seismicity induced by time dependent stress changes. An important feature of the code is the possibility to include aleatoric uncertainties due to the existence of multiple receiver faults and to the finite grid size, as well as epistemic uncertainties due to the choice of input slip model. To compensate for the growth in computational requirements, we have parallelized the code for shared memory systems (using OpenMP) and distributed memory systems (using MPI). Performance tests indicate that these parallelization strategies lead to a significant speedup for problems with different degrees of complexity, ranging from those which can be solved on standard multicore desktop computers, to those requiring a small cluster, to a large simulation that can be run using up to 1500 cores.

  5. An algorithm for the calculation of the partial wave expansion of the Coulomb-distorted plane wave

    Science.gov (United States)

    Hornyak, I.; Kruppa, A. T.

    2015-12-01

    The partial wave expansion of the Coulomb-distorted plane wave is determined by the help of the complex generalized hypergeometric function 2F2(a , a ; a + l + 1 , a - l ; z) . An algorithm for the calculation of 2F2(a , a ; a + l + 1 , a - l ; z) is created and it is implemented as a FORTRAN-90 code. The code is fast and its accuracy is 14 significant decimal digits.

  6. Free energy calculation of a molecule by removing VDW and Coulomb interactions in a transformation and treating the molecule as non interacting systems

    CERN Document Server

    Farhi, Asaf

    2015-01-01

    Free energy calculations in molecular simulations have a variety of applications including determining the strength of molecular processes such as solvation and binding. It has been recently shown that when removing the VDW and Coulomb potential terms of a group of atoms in a molecule by performing a transformation, the molecule can be treated as non interacting systems in the free energy calculation. This treatment is applicable both when the molecule is in vacuum and in liquid and enables a very simple calculation of the free energies associated with the potentials that depend on the relative spherical coordinates of these atoms. Here we demonstrate the method in the free energy calculation of a Methanethiol molecule and compare the results to these obtained by MD simulations in vacuum and in water. The comparison of free energies associated with the potentials that depend on the relative spherical coordinates shows agreement between the results and faster computation when using the method by factors starti...

  7. LTRACK: Beam-transport calculation including wakefield effects

    International Nuclear Information System (INIS)

    LTRACK is a first-order beam-transport code that includes wakefield effects up to quadrupole modes. This paper will introduce the readers to this computer code by describing the history, the method of calculations, and a brief summary of the input/output information. Future plans for the code will also be described

  8. Coulomb-nucleon phase and spin effects in the diffraction dip domain

    International Nuclear Information System (INIS)

    The total phase of the Coulomb-hadron interaction is calculated with the true hadron scattering amplitude and with the Coulomb amplitude including the form factor of hadrons. This phase includes also the contribution of the phase of the pure coulomb interaction of hadrons taking into account the hadron form factors. The analyzing power AN is calculated in the whole diffraction dip domain of high-energy elastic hadron scattering with the Coulomb-hadron interference effects. (author)

  9. On the Differences Between the Drucker-Prager Criterion and Exact Implementation of the Mohr-Coulomb Criterion in FEM Calculations

    DEFF Research Database (Denmark)

    Clausen, Johan; Andersen, Lars; Damkilde, Lars

    This paper compares calculation results obtained with the Mohr-Coulomb and Drucker-Prager material models. The models are implemented in a finite element code and the exact models are used, i.e. no rounding of yield surface corners or apices is performed. Results for both 2D and 3D calculations are...

  10. Equation of state calculations for two-dimensional dust coulomb crystal at near zero temperature by molecular dynamics simulations

    International Nuclear Information System (INIS)

    Dust particles observed in universe as well as in laboratory and technological plasma devices are still under investigation. At low temperature, these particles are strongly negatively charged and are able to form a 2D or 3D coulomb crystal. In this work, our aim was to check the ideal gas law validity for a 2D single-layer dust crystal recently reported in the literature. For this purpose, we have simulated, using the molecular dynamics method, its thermodynamic properties for different values of dust particles number and confinement parameters. The obtained results have allowed us to invalidate the ideal gas behaviour and to propose an effective equation of state which assumes a near zero dust temperature. Furthermore, the value of the calculated sound velocity was found to be in a good agreement with experimental data published elsewhere

  11. Equation of state calculations for two-dimensional dust coulomb crystal at near zero temperature by molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Djouder, M., E-mail: djouder-madjid@ummto.dz; Kermoun, F.; Mitiche, M. D.; Lamrous, O. [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri Tizi-Ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria)

    2016-01-15

    Dust particles observed in universe as well as in laboratory and technological plasma devices are still under investigation. At low temperature, these particles are strongly negatively charged and are able to form a 2D or 3D coulomb crystal. In this work, our aim was to check the ideal gas law validity for a 2D single-layer dust crystal recently reported in the literature. For this purpose, we have simulated, using the molecular dynamics method, its thermodynamic properties for different values of dust particles number and confinement parameters. The obtained results have allowed us to invalidate the ideal gas behaviour and to propose an effective equation of state which assumes a near zero dust temperature. Furthermore, the value of the calculated sound velocity was found to be in a good agreement with experimental data published elsewhere.

  12. Density-functional calculation of effective Coulomb interactions in nonmetallic systems: Application to Mn in CdTe, CdS, and ZnO

    Science.gov (United States)

    Gunnarsson, O.; Postnikov, A. V.; Andersen, O. K.

    1989-11-01

    The effective Coulomb interaction U between the 3d electrons of Mn impurities in CdTe, CdS, and ZnO is calculated. The influence of the host on the renormalization of U is studied. It is shown that the screening due to charge transfer to the Mn atom is very efficient for Mn in CdTe, less efficient for Mn in CdS, and rather inefficient for ZnO. This is related to the increasing ionic character, which makes charge transfer to Mn increasingly difficult. The total effect of all charge-transfer processes, including charge transfer to the ligand atoms, is nevertheless substantial even for Mn in ZnO.

  13. A tool for standardized collector performance calculations including PVT

    DEFF Research Database (Denmark)

    Perers, Bengt; Kovacs, Peter; Olsson, Marcus;

    2012-01-01

    A tool for standardized calculation of solar collector performance has been developed in cooperation between SP Technical Research Institute of Sweden, DTU Denmark and SERC Dalarna University. The tool is designed to calculate the annual performance of solar collectors at representative locations...... in Europe. The collector parameters used as input in the tool are compiled from tests according to EN12975, without any intermediate conversions. The main target group for this tool is test institutes and certification bodies that are intended to use it for conversion of collector model parameters (derived...... from performance tests) into a more user friendly quantity: the annual energy output. The energy output presented in the tool is expressed as kWh per collector module. A simplified treatment of performance for PVT collectors is added based on the assumption that the thermal part of the PVT collector...

  14. Exact Coulomb exchange calculations in the Skyrme-Hartree-Fock-BCS framework and tests of the Slater approximation

    International Nuclear Information System (INIS)

    An exact treatment of the Coulomb interaction is performed within the Skyrme-Hartree-Fock/Bardeen-Cooper-Schrieffer approach for even-even nuclei ranging from light to superheavy nuclei. A test of the usual Slater approximation for the exchange part is carried out. The error made on the exchange term of the Coulomb interaction when using this approximation follows two schematic patterns. Beyond a decreasing behavior when increasing the mass number A, a more important structural effect has been found. The relative error ranges roughly from 0 to 8% being maximal for light closed proton (sub-)shell nuclei and minimal for open proton (sub-)shell nuclei.

  15. Theory of strongly correlated electron systems. I. Intersite Coulomb interaction and the approximation of renormalized fermions in total energy calculations

    Science.gov (United States)

    Sandalov, I.; Lundin, U.; Eriksson, O.

    The diagrammatic strong-coupling perturbation theory (SCPT) for correlated electron systems is developed for intersite Coulomb interaction and for a nonorthogonal basis set. The construction is based on iterations of exact closed equations for many-electron Green functions (GFs) for Hubbard operators in terms of functional derivatives with respect to external sources. The graphs, which do not contain the contributions from the fluctuations of the local population numbers of the ion states, play a special role: a one-to-one correspondence is found between the subset of such graphs for the many-electron GFs and the complete set of Feynman graphs of weak-coupling perturbation theory (WCPT) for single-electron GFs. This fact is used for formulation of the approximation of renormalized Fermions (ARF) in which the many-electron quasi-particles behave analogously to normal Fermions. Then, by analyzing: (a) Sham's equation, which connects the self-energy and the exchange-correlation potential in density functional theory (DFT); and (b) the Galitskii and Migdal expressions for the total energy, written within WCPT and within ARF SCPT, a way we suggest a method to improve the description of the systems with correlated electrons within the local density approximation (LDA) to DFT. The formulation, in terms of renormalized Fermions LDA (RF LDA), is obtained by introducing the spectral weights of the many-electron GFs into the definitions of the charge density, the overlap matrices, effective mixing and hopping matrix elements, into existing electronic structure codes, whereas the weights themselves have to be found from an additional set of equations. Compared with LDA+U and self-interaction correction (SIC) methods, RF LDA has the advantage of taking into account the transfer of spectral weights, and, when formulated in terms of GFs, also allows for consideration of excitations and nonzero temperature. Going beyond the ARF SCPT, as well as RF LDA, and taking into account the

  16. New insights into the origin of visible-light photocatalytic activity in Se-modified anatase TiO2 from screened coulomb hybrid DFT calculations

    KAUST Repository

    Harb, Moussab

    2013-12-05

    We report a systematic study on the optoelectronic properties of Se-modified anatase TiO2 investigated by DFT (including the perturbation theory approach DFPT) within the screened coulomb hybrid HSE06 formalism to guarantee accurate band gap and electronic excitation predictions. Various selenium species at substitutional sites for O or Ti, at interstitial sites, as well as at mixed substitutional/interstitial sites are studied. Among the explored structures, Ti(1-2x)O2Se2x (containing Se4+ species), TiO(2-x)Sex (containing Se2- species), and TiO(2-x)Se2x (containing Se2 2- species) reveal significant enhanced visible-light optical absorption spectra with new absorption features appearing at 500, 600, and 690 nm, respectively. Our calculated spectra are found to be in good agreement with those obtained in available experimental works. The band gap narrowing in these materials originates from incorporation of newly occupied electronic levels within 0.5-1.5 eV above the original valence band of TiO 2, leading to new narrowed band gaps of 2.5, 2.0, and 1.8 eV respectively. Our calculations also reveal suitable band positions of Ti (1-2x)O2Se2x and TiO(2-x)Se x for overall water splitting, whereas TiO(2-x)Se 2x shows an unsuitable valence band position for the oxygen evolution reaction. In contrast, the localized electronic character of the new occupied states on the Se 4p orbitals and only on the O 2p orbitals linked to the Se species makes the holes mobility limited in this material and the recombination rate of charge carriers greatly increased in the bulk. © 2013 American Chemical Society.

  17. New calculations and measurements of the Coulomb cross-section for the production of direct electron pairs by high energy nuclei

    Science.gov (United States)

    Derrickson, J. H.; Dake, S.; Dong, B. L.; Eby, P. B.; Fountain, W. F.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Iyono, A.; King, D. T.

    1989-01-01

    Recently, new calculations were made of the direct Coulomb pair cross section that rely less in arbitrary parameters. More accurate calculations of the cross section down to low pair energies were made. New measurements of the total direct electron pair yield, and the energy and angular distribution of the electron pairs in emulsion were made for O-16 at 60 and 200 GeV/amu at S-32 at 200 GeV/amu which give satisfactory agreement with the new calculations. These calculations and measurements are presented along with previous accelerator measurements made of this effect during the last 40 years. The microscope scanning criteria used to identify the direct electron pairs is described. Prospects for application of the pair method to cosmic ray energy measurements in the region 10 (exp 13) to 10 (exp 15) eV/amu are discussed.

  18. Coulomb displacement energies in nuclei: a new approach

    International Nuclear Information System (INIS)

    The neutron core polarization gives rise to an important correction to the direct Coulomb contribution when one calculates the Coulomb displacement energies. In the Hartree-Fock model it is shown that this correction is about 2% to 4.5% in medium and heavy nuclei. The core polarization as well as other higher order effects can be included by using a selfconsistent description of the analog state in a complete proton particle-neutron hole space. The Coulomb displacement energies in 48Ca, 88Sr and 208Pb have been calculated using Skyrme interactions SIII and SIV. A good agreement with experiment is obtained

  19. Density fitting for derivatives of Coulomb integrals in ab initio calculations using mixed Gaussian and plane-wave basis

    Czech Academy of Sciences Publication Activity Database

    Čársky, Petr

    2009-01-01

    Roč. 109, č. 620 (2009), s. 1237-1242. ISSN 0020-7608 R&D Projects: GA ČR GA203/07/0070; GA ČR GA202/08/0631; GA AV ČR 1ET400400413; GA AV ČR IAA100400501 Institutional research plan: CEZ:AV0Z40400503 Keywords : Derivatives of Coulomb integrals * mixed Gaussian and plane-wave basis sets * electron scattering * computer time saving Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.315, year: 2009

  20. Characteristics of Coulomb fission

    OpenAIRE

    Oberacker, Volker; Greiner, Walter; Kruse, Hans; Pinkston, William T.

    2006-01-01

    Within an extended semiquantal theory we perform large-sized coupled-channel calculations involving 260 collective levels for Coulomb fission of 238U. Differential Coulomb fission cross sections are studied as a function of bombarding energy and impact parameter for several projectiles. In the Xe + U case, total cross sections are also given. We find a strong dependence on projectile charge number, PCF(180°)∼(Zp)6 in the region 50≤Zp≤92 for a fixed ratio E/ECoul, which might...

  1. Dirac-hyperbolic scarf problem including a coulomb-like tensor potential - doi: 10.4025/actascitechnol.v34i2.13323

    Directory of Open Access Journals (Sweden)

    Mahdi Eshghi

    2012-03-01

    Full Text Available The Dirac equation have been solved for the q-deformed hyperbolic Scarf potential coupled to a Coulomb-like tensor potential under the spin symmetry. The parametric generalization of the Nikiforov-Uvarov method is used to obtain the energy eigenvalues equation and the normalized wave functions.

  2. Nuclear Interference effects in 8B sub-Coulomb breakup

    OpenAIRE

    Nunes, F. M.; Thompson, I.J.

    1998-01-01

    The breakup of $^8$B on $^{58}$Ni below the Coulomb barrier was measured recently with the aim of determining the Coulomb breakup components. We reexamine this reaction, and perform one step quantum-mechanical calculations that include E1, E2 and nuclear contributions. We show that the nuclear contribution is by no means negligible at the intermediate angular range where data was taken. Our results indicate that, for an accurate description of this reaction, Coulomb E1, E2 and nuclear process...

  3. Application of Parallel Hybrid Algorithm in Massively Parallel GPGPU—The Improved Effective and Efficient Method for Calculating Coulombic Interactions in Simulations of Many Ions with SIMION

    Science.gov (United States)

    Saito, Kenichiro; Koizumi, Eiko; Koizumi, Hideya

    2012-09-01

    In our previous study, we introduced a new hybrid approach to effectively approximate the total force on each ion during a trajectory calculation in mass spectrometry device simulations, and the algorithm worked successfully with SIMION. We took one step further and applied the method in massively parallel general-purpose computing with GPU (GPGPU) to test its performance in simulations with thousands to over a million ions. We took extra care to minimize the barrier synchronization and data transfer between the host (CPU) and the device (GPU) memory, and took full advantage of the latency hiding. Parallel codes were written in CUDA C++ and implemented to SIMION via the user-defined Lua program. In this study, we tested the parallel hybrid algorithm with a couple of basic models and analyzed the performance by comparing it to that of the original, fully-explicit method written in serial code. The Coulomb explosion simulation with 128,000 ions was completed in 309 s, over 700 times faster than the 63 h taken by the original explicit method in which we evaluated two-body Coulomb interactions explicitly on one ion with each of all the other ions. The simulation of 1,024,000 ions was completed in 2650 s. In another example, we applied the hybrid method on a simulation of ions in a simple quadrupole ion storage model with 100,000 ions, and it only took less than 10 d. Based on our estimate, the same simulation is expected to take 5-7 y by the explicit method in serial code.

  4. Coulomb drag in graphene

    OpenAIRE

    Hwang, E. H.; Sarma, S. Das

    2011-01-01

    We calculate theoretically the Coulomb drag resistivity for two graphene monolayers spatially separated by a distance "$d$". We show that the frictional drag induced by inter-layer electron-electron interaction goes asymptotically as $T^2/n^3$ and $T^2 \\ln(n)/n$ in the high-density ($k_F d \\gg 1$) and low-density ($k_F d \\ll 1$) limits, respectively.

  5. Six months later: Testing the Coulomb stress change model by examining calculations made immediately after the 12 May, 2008 Ms=8.0 Wenchuan earthquake

    Science.gov (United States)

    Parsons, T.; Ji, C.; Kirby, E.

    2008-12-01

    On the 12th of May, 2008 a devastating Ms=8.0 earthquake struck the eastern edge of the Tibetan Plateau, collapsing buildings and killing thousands in major cities aligned along the western Sichuan basin in China. After a high-magnitude earthquake like the 12 May event, rearrangement of stresses in the crust commonly causes subsequent damaging earthquakes. The Sichuan basin and surroundings are crossed by major active strike-slip and thrust faults. By 72 hours after the earthquake, coseismic stress changes were calculated on models of those faults, with many showing significant stress increases. Rapid mapping of stress changes was intended to locate fault sections with relatively higher odds of producing the largest aftershocks and to enable prospective testing of the static-stress triggering hypothesis. A recent prospective test of the method was conducted by McCloskey et al. [2005] after the great 2004 Sumatra earthquake, and was validated by a M=8.7 shock that struck three months later in a region calculated to have been stressed by the mainshock. Our test begins at the time peer review was completed, 38 days after the mainshock on 19 June, 2008. Thus aftershocks occurring between that time and the present can be used for prospective testing. As of this writing, in our test region magnitude greater than 4.0 aftershocks have been largely confined to the mainshock rupture zone, with virtually no activity on Sichuan basin faults with calculated stress increases. Examination of magnitude-frequency behavior of the aftershocks suggests either a corner magnitude at about magnitude 6, or a deficiency in the magnitude greater than 6 range. This experiment is ongoing, and time will tell if the Coulomb model is confirmed in the Sichuan region; our conclusion at present is that there has been no validation, and that use of a generalized aftershock forecast model would have been sufficient.

  6. Elastic Coulomb breakup of $^{34}$Na

    CERN Document Server

    Singh, G; Chatterjee, R

    2016-01-01

    Purpose : The aim of this paper is to study the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb to give us a core of $^{33}$Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of $^{34}$Na. Method : A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb at 100 MeV/u. The triple differential cross-section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum and angular distributions as well as the average momenta, along with the energy-angular distributions. Results : The total one neutron removal cross-section is calculated to test the possible ground state configurations of $^{34}$Na. The average momentum results along with energy-angular calculations indicate $^{34}$Na to ha...

  7. Use of Dirac-Coulomb Sturmians of the first order for relativistic calculations of two-photon bound-bound transition amplitudes in hydrogen-like ions

    International Nuclear Information System (INIS)

    A fully relativistic treatment of the S-matrix elements describing two-photon bound-bound transition amplitudes in hydrogen-like ions is undertaken in the present work. Several selected transitions from the ground state vertical bar 12S) towards the L and M shells (vertical bar 22S), vertical bar 32S), vertical bar 32D3/2) and vertical bar 32D5/2)) are described. For that purpose, we use the complete set of relativistic Sturmian functions derived by Szmytkowski (1997 J. Phys. B: At. Mol. Opt. Phys. 30 825) from the first-order Sturm-Liouville problems for the Dirac equation. The method followed consists of writing the matrix elements in terms of Green functions expanded over the first-order Dirac-Coulomb Sturmians. Previous approaches used a Sturmian basis associated with the Gell-Mann-Feynman equation. On the other hand, a distinctive feature of our tensor treatment is that the expressions derived are quite general and could be applied to any multipole of the two-photon bound-bound transitions. In the case of dipole transitions, considered also by Szymanowski et al (1997 Phys. Rev. A 56 700) in their calculations, the selection rules derived from our method lead to two additional terms related to l1p = 2 and l2p = 2. The numerical results obtained for the transition from the ground state |12S) towards the L and M shells enable us to draw inferences as to the improvements of our method

  8. Ab initio calculation of the bcc Fe-Al phase diagram including magnetic interactions

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales-Ormeno, Pablo Guillermo [Facultad de Ciencias Naturales y Matematica, Universidad Nacional Federico Villarreal, Calle San Marcos 351, Pueblo Libre, Lima (Peru); Departamento de Fisica dos Materiais e Mecanica, Instituto de Fisica da Universidade de Sao Paulo, CP 66318, CEP 05315-970 Sao Paulo-SP (Brazil); Computational Materials Science Lab., Departamento de Engenharia Metalurgica e de Materiais, Escola Politecnica da Universidade de Sao Paulo, Av. Prof. Mello Moraes, 2463, CEP 05508-900 Sao Paulo-SP (Brazil); Petrilli, Helena Maria [Departamento de Fisica dos Materiais e Mecanica, Instituto de Fisica da Universidade de Sao Paulo, CP 66318, CEP 05315-970 Sao Paulo-SP (Brazil)]. E-mail: hmpetril@macbeth.if.usp.br; Schoen, Claudio Geraldo [Computational Materials Science Lab., Departamento de Engenharia Metalurgica e de Materiais, Escola Politecnica da Universidade de Sao Paulo, Av. Prof. Mello Moraes, 2463, CEP 05508-900 Sao Paulo-SP (Brazil)]. E-mail: schoen@usp.br

    2006-04-15

    metastable phase diagram of the body-centered cubic-based ordering equilibria in the Fe-Al system has been calculated by the cluster expansion method, through the combination of the full potential-linear augmented plane wave and cluster variation methods. The results are discussed with reference to the effect of including the spin polarizations of Fe in the thermodynamic model.

  9. Ab initio calculation of the bcc Fe-Al phase diagram including magnetic interactions

    International Nuclear Information System (INIS)

    The metastable phase diagram of the body-centered cubic-based ordering equilibria in the Fe-Al system has been calculated by the cluster expansion method, through the combination of the full potential-linear augmented plane wave and cluster variation methods. The results are discussed with reference to the effect of including the spin polarizations of Fe in the thermodynamic model

  10. Coulomb-Born calculation of the triple-differential cross section for inner-shell electron-impact ionization of carbon

    International Nuclear Information System (INIS)

    A Coulomb-Born approximation is used to compute the triple-differential cross section for electron-impact inner-shell (1s) ionization of carbon. We employ a perturbation series that allows the use of Coulomb waves with arbitrary Zeff for the incoming, scattered, and ejected electrons. Most of the features of the triple-differential cross section observed experimentally are reproduced, even though these wave functions are distorted by an effective Coulomb potential and therefore do not satisfy the plane-wave boundary conditions at infinity. In order to explain some features that appear in the cross section, and in order to probe the validity of a dipole approximation, we make a multipole expansion of the transition matrix and show that the amplitudes of the multipole components are similar to those obtained in the Born approximation, while the relative phases of the multipoles differ greatly

  11. 3 D diffusion calculation of HIFAR including the coarse control arms and their burnup

    International Nuclear Information System (INIS)

    A 3D model of HIFAR which includes the coarse control arms (CCA) has been developed which is based on a 2-group, relatively coarse mesh, diffusion calculation. Appropriate absorption cross sections to represent the signal arm control blades were obtained by comparison with multigroup discrete ordinates cell calculations. An integral test of the CCA worth using the model showed excellent agreement with a geometrically detailed Monte Carlo calculation. Comparison with the most recent measurement of the CCA reactivity calibration showed good agreement and, in particular, a constant difference of about 6 per cent between calculation and measurement in change of reactivity with arm movement over the normal operating range. Extension of the model to include the burn-up of the CCA control material has provided the first calculation-based estimates of the loss of CCA effectiveness with time. Similar estimates of the worth of europium tipped control blades and their lifetime have been made. This confirmed that blades of this type have almost identical initial reactivity worth to all-cadmium blades and that their lifetime is very much longer. 27 refs., 4 tabs., 10 figs

  12. Practical Calculational Scheme Implementing the Wilsonian RG Results for Nuclear Effective Field Theory Including Pions

    International Nuclear Information System (INIS)

    On the basis of the Wilsonian renormalization group (WRG) analysis of nuclear effective field theory (NEFT) including pions, we propose a practical calculational scheme in which the short-distance part of one-pion exchange (S-OPE) is removed and represented as contact terms. The long-distance part of one-pion exchange (L-OPE) is treated as perturbation. The use of dimensional regularization (DR) for diagrams consisting only of contact interactions considerably simplifies the calculation of scattering amplitude and the renormalization group equations. NLO results for nucleon-nucleon elastic scattering in the S-waves are obtained and compared with experiments. A brief comment on NNLO calculations is given. (author)

  13. Coulomb Potentials between Spherical and Deformed Nuclei

    Institute of Scientific and Technical Information of China (English)

    ZHANG Gao-Long; LE Xiao-Yun; LIU Zu-Hua

    2008-01-01

    @@ Coulomb potentials for spherical-deformed reaction partners are calculated in terms of the double folding model as well as the conventional formulas. Our results show that the Coulomb potentials calculated with different approaches have quite different behaviours in the internal region of the potential. Because fusion process is sensitive to the barrier height and the internal part of the potential, the fusion excitation function, especially the fusion barrier distribution, should provide a strict test of the interaction potentiaLs. Therefore, we calculate the fusion excitation function and barrier distribution for the 16O+154 Sm system with different versions of the Coulomb potentials, in comparison with the experimental results. It is found that the fusion excitation function and barrier distribution of 16 O+154 Sm are obviously different for the different versions of the Coulomb potentials.By means of this comparison, we may conclude that the double folding model with the accurate approximate form can provide rather reasonable Coulomb potentials.

  14. Convergence of Feynman integrals in Coulomb gauge QCD

    International Nuclear Information System (INIS)

    At 2-loop order, Feynman integrals in the Coulomb gauge are divergent over the internal energy variables. Nevertheless, it is known how to calculate the effective action, provided that the external gluon fields are all transverse. We show that, for the two-gluon Greens function as an example, the method can be extended to include longitudinal external fields. The longitudinal Greens functions appear in the BRST identities. As an intermediate step, we use a flow gauge, which interpolates between the Feynman and Coulomb gauges

  15. A method for including external feed in depletion calculations with CRAM and implementation into ORIGEN

    International Nuclear Information System (INIS)

    Highlights: • A method for handling external feed in depletion calculations with CRAM. • Source term can have polynomial or exponentially decaying time-dependence. • CRAM with source term and adjoint capability implemented to ORIGEN in SCALE. • The new solver is faster and more accurate than the original solver of ORIGEN. - Abstract: A method for including external feed with polynomial time dependence in depletion calculations with the Chebyshev Rational Approximation Method (CRAM) is presented and the implementation of CRAM to the ORIGEN module of the SCALE suite is described. In addition to being able to handle time-dependent feed rates, the new solver also adds the capability to perform adjoint calculations. Results obtained with the new CRAM solver and the original depletion solver of ORIGEN are compared to high precision reference calculations, which shows the new solver to be orders of magnitude more accurate. Furthermore, in most cases, the new solver is up to several times faster due to not requiring similar substepping as the original one

  16. Optical Software to Calculate Terrestrial Planet Finder Contrast Including Polarization Effects Project

    Data.gov (United States)

    National Aeronautics and Space Administration — BRO will provide commercially available optics software that dependably calculates image plane irradiance to the precision required by TPF missions. Calculations...

  17. Coulomb effects in relativistic laser-assisted Mott scattering

    International Nuclear Information System (INIS)

    We reconsider the influence of the Coulomb interaction on the process of relativistic Mott scattering in a powerful electromagnetic plane wave for which the ponderomotive energy is of the order of the magnitude of the electron's rest mass. Coulomb effects of the bare nucleus on the laser-dressed electron are treated more completely than in the previous work of Li et al. [J. Phys. B: At. Mol. Opt. Phys. 37 (2004) 653]. To this end we use Coulomb-Dirac-Volkov functions to describe the initial and the final states of the electron. First-order Born differential cross sections of induced and inverse bremsstrahlung are obtained for circularly and linearly polarized laser light. Numerical calculations are carried out from both polarizations, for various nucleus charge values, three angular configurations and an incident energy in the MeV range. It is found that for parameters used in the present work, incorporating Coulomb effects of the target nucleus either in the initial state or in the final state yields cross sections which are quite similar whatever the scattering geometry and polarization considered. When Coulomb distortions are included in both states, the cross sections are strongly modified with the increase of Z, as compared to the outcome of the prior form of the T-matrix treatment. (author)

  18. Infinite momentum frame calculation of semileptonic heavy Λb→Λc transitions including HQET improvements

    International Nuclear Information System (INIS)

    We calculate the transition form factors that occur in heavy Λ-type baryon semileptonic decays such as, e.g., in Λb→Λc++l-+bar νl. We use Bauer-Stech-Wirbel-type infinite momentum frame wave functions for the heavy Λ-type baryons which we assume to consist of a heavy quark and a light spin-isospin zero diquark system. The form factors at q2=0 are calculated from the overlap integrals of the initial and final Λ-type baryon states. To leading order in the heavy mass scale the structure of the form factors agrees with the HQET predictions including the normalization at zero recoil. The leading order ω dependence of the form factors is extracted by scaling arguments. By comparing the model form factors with the HQET predictions at O(1/mQ) we obtain a consistent set of model form factors up to O(1/mQ). With our preferred choice of parameter values we find that the contribution of the nonleading form factor is practically negligible. We use our form factor predictions to compute rates, spectra, and various asymmetry parameters for the semileptonic decay Λb→Λc++l-+bar νl. copyright 1997 The American Physical Society

  19. Modifications of the Fourier approach for magnetic field calculations to include axial shields in superconducting magnets

    International Nuclear Information System (INIS)

    Martinelli and Morini have used an analytical method for calculating values and distribution of the magnetic field in superconducting magnets. Using Fourier series the magnetic field is determined by carrying out a series expansion of the current density distribution of the system of coils. This Fourier method can be modified to include axial iron to a far greater accuracy (for finite permeability) by incorporating the image series approach of Caldwell and Zisserman. Also an exact solution can be obtained for the case of infinite permeability. A comparison of the results derived from the expansion of Martinelli and Morini with the exact solution of Caldwell and Zisserman shows excellent agreement for the iron-free case but the accuracy deteriorates as the permeability μ/sub z/ increases. The exact solution should be used for infinite permeability and also gives satisfactory results for permeability μ/sub z/ >100. A symmetric geometry is used throughout the communication for simplicity of presentation

  20. Ion Coulomb Crystals

    CERN Document Server

    Thompson, Richard C

    2014-01-01

    Ion Coulomb crystals (ICC), formed by atomic ions at low temperatures in radiofrequency and Penning ion traps, are structures that have remarkable properties and many applications. Images of Coulomb crystals are striking and reveal the crystal structure, which arises from a balance between the trapping forces acting on the ions and their mutual Coulomb repulsion. Applications of these structures range from frequency standards and quantum simulation through to measurement of the cross sections of chemical reactions of ions.

  1. Multi-reference approach to the calculation of photoelectron spectra including spin-orbit coupling

    CERN Document Server

    Grell, Gilbert; Winter, Bernd; Seidel, Robert; Aziz, Emad F; Aziz, Saadullah G; Kühn, Oliver

    2015-01-01

    X-ray photoelectron spectra provide a wealth of information on the electronic structure. The extraction of molecular details requires adequate theoretical methods, which in case of transition metal complexes has to account for effects due to the multi-configurational and spin-mixed nature of the many-electron wave function. Here, the Restricted Active Space Self-Consistent Field method including spin-orbit coupling is used to cope with this challenge and to calculate valence and core photoelectron spectra. The intensities are estimated within the frameworks of the Dyson orbital formalism and the sudden approximation. Thereby, we utilize an efficient computational algorithm that is based on a biorthonormal basis transformation. The approach is applied to the valence photoionization of the gas phase water molecule and to the core ionization spectrum of the $\\text{[Fe(H}_2\\text{O)}_6\\text{]}^{2+}$ complex. The results show good agreement with the experimental data obtained in this work, whereas the sudden approx...

  2. Multi-reference approach to the calculation of photoelectron spectra including spin-orbit coupling

    International Nuclear Information System (INIS)

    X-ray photoelectron spectra provide a wealth of information on the electronic structure. The extraction of molecular details requires adequate theoretical methods, which in case of transition metal complexes has to account for effects due to the multi-configurational and spin-mixed nature of the many-electron wave function. Here, the restricted active space self-consistent field method including spin-orbit coupling is used to cope with this challenge and to calculate valence- and core-level photoelectron spectra. The intensities are estimated within the frameworks of the Dyson orbital formalism and the sudden approximation. Thereby, we utilize an efficient computational algorithm that is based on a biorthonormal basis transformation. The approach is applied to the valence photoionization of the gas phase water molecule and to the core ionization spectrum of the [Fe(H2O)6]2+ complex. The results show good agreement with the experimental data obtained in this work, whereas the sudden approximation demonstrates distinct deviations from experiments

  3. Multi-reference approach to the calculation of photoelectron spectra including spin-orbit coupling

    Energy Technology Data Exchange (ETDEWEB)

    Grell, Gilbert; Bokarev, Sergey I., E-mail: sergey.bokarev@uni-rostock.de; Kühn, Oliver [Institut für Physik, Universität Rostock, D-18051 Rostock (Germany); Winter, Bernd; Seidel, Robert [Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany); Aziz, Emad F. [Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany); Department of Physics, Freie Universität Berlin, Arnimalle 14, D-14159 Berlin (Germany); Aziz, Saadullah G. [Chemistry Department, Faculty of Science, King Abdulaziz University, 21589 Jeddah (Saudi Arabia)

    2015-08-21

    X-ray photoelectron spectra provide a wealth of information on the electronic structure. The extraction of molecular details requires adequate theoretical methods, which in case of transition metal complexes has to account for effects due to the multi-configurational and spin-mixed nature of the many-electron wave function. Here, the restricted active space self-consistent field method including spin-orbit coupling is used to cope with this challenge and to calculate valence- and core-level photoelectron spectra. The intensities are estimated within the frameworks of the Dyson orbital formalism and the sudden approximation. Thereby, we utilize an efficient computational algorithm that is based on a biorthonormal basis transformation. The approach is applied to the valence photoionization of the gas phase water molecule and to the core ionization spectrum of the [Fe(H{sub 2}O){sub 6}]{sup 2+} complex. The results show good agreement with the experimental data obtained in this work, whereas the sudden approximation demonstrates distinct deviations from experiments.

  4. SU-E-T-397: Include Organ Deformation Into Dose Calculation of Prostate Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: Prostate brachytherapy is an important curative treatment for patients with localized prostate cancer. In brachytherapy, rectal balloon is generally needed to adjust for unfavorable prostate position for seed placement. However, rectal balloon causes prostate deformation, which is not accounted for in dosimetric planning. Therefore, it is possible that brachytherapy dosimetry deviates significantly from initial plan when prostate returns to its non-deformed state (after procedure). The goal of this study is to develop a method to include prostate deformation into the treatment planning of brachytherapy dosimetry. Methods: We prospectively collected ultrasound images of prostate pre- and post- rectal balloon inflation from thirty five consecutive patients undergoing I-125 brachytherapy. Based on the cylinder coordinate systems, we learned the initial coordinate transformation parameters between the manual segmentations of both deformed and non-deformed prostates of each patient in training set. With the nearest-neighbor interpolation, we searched the best transformation between two coordinate systems to maximum the mutual information of deformed and non-deformed images. We then mapped the implanted seeds of five selected patients from the deformed prostate into non-deformed prostate. The seed position is marked on original pre-inflation US image and it is imported into VariSeed software for dose calculation. Results: The accuracy of image registration is 87.5% as quantified by Dice Index. The prostate coverage V100% dropped from 96.5±0.5% of prostate deformed plan to 91.9±2.6% (p<0.05) of non-deformed plan. The rectum V100% decreased from 0.44±0.26 cc to 0.10±0.18 cc (p<0.05). The dosimetry of the urethra showed mild change but not significant: V150% changed from 0.05±0.10 cc to 0.14±0.15 cc (p>0.05) and D1% changed from 212.9±37.3 Gy to 248.4±42.8 Gy (p>0.05). Conclusion: We have developed a deformable image registration method that allows

  5. Biostatistics with emphasis on life table survival rate calculations (including Kaplan Meier) and the logrank test

    International Nuclear Information System (INIS)

    Purpose/Objective: To explain some of the most useful statistical calculation procedures which are relevant to radiation oncologists and to provide insights on what tests and procedures should be used in various situations such as when survival rates and their associated standard errors have to be determined. To describe some of the problems and pitfalls in clinical trial designs which have to be overcome if a trial is to have the possibility of reaching a successful conclusion. To review methods of computing criteria to quantitatively describe criteria of success (eg. quality of life, long-term survival, cure) of radiation oncology and to suggest possible future statistical improvements in this area. Chi-Squared Test: The chi-squared test is probably the most useful of the tests of statistical significance for the radiation oncologist. Applications will be described, including goodness of fit tests and 2x2 contingency tables which are the simplest of the generalized nxm contingency tables. Degrees of Freedom and P<0.05 for Significance Testing: An Introduction will be given to the meaning of P<0.05 in relation to significance testing and the use of tables of critical values of a test statistic (eg. chi-squared) which are given as a function of degrees of freedom and P-values. Survival Rate Calculations for Grouped and Ungrouped Data: The life-table method (sometimes termed the actuarial method) will be explained for both grouped data (eg. survival times grouped in annual intervals for patients who have died and for those who are still alive or lost to follow-up) and for ungrouped data (when individual survival times are used). The method for ungrouped data is variously termed the Kaplan-Meier or Product Limit method. Logrank Test: This is the most useful test for comparison of the survival experience of two groups of patients and its use will be explained. In part the computation is similar to that for the Kaplan-Meier/Product Limit method

  6. Accurate spectroscopic calculations of 21 electronic states of ClO radical including transition properties.

    Science.gov (United States)

    Wang, Xinxin; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2016-08-01

    The potential energy curves were calculated for the 21 states (X(2)Π, A(2)Π, 3(2)Π, 4(2)Π, 5(2)Π, 1(2)Σ(+), 2(2)Σ(+), 3(2)Σ(+), 1(2)Σ(-), 2(2)Σ(-), 3(2)Σ(-), 1(2)Δ, 2(2)Δ, 3(2)Δ, 1(2)Φ, 1(4)Σ(+), a(4)Σ(-), 2(4)Σ(-), 1(4)Π, 2(4)Π and 1(4)Δ), which originated from the two lowest dissociation channels of ClO radical. The calculations were done for internuclear separations approximately from 0.08 to 1.10nm using the CASSCF method, which was followed by the icMRCI approach with the aug-cc-pV5Z basis set. Of these 21 states, the 1(4)Π, 2(4)Π, 3(2)Δ, 4(2)Π, 5(2)Π, 1(2)Φ, 3(2)Σ(+), 1(4)Δ and 2(4)Σ(-) states are repulsive. The 1(2)Δ, 1(2)Σ(-), 1(4)Σ(+), 2(2)Σ(-), 1(2)Σ(+), 2(2)Σ(+), 2(2)Δ and 3(2)Σ(-) states are very weakly bound. Only the A(2)Π state has one barrier. The avoided crossing exists between the A(2)Π and the 3(2)Π state. However, the avoided crossing does not generate any double wells. Core- valence correlation correction was accounted for at the level of an aug-cc-pCVQZ basis set. Scalar relativistic correction was included by the third-order Douglas-Kroll Hamiltonian approximation at the level of an aug-cc-pVQZ basis set. All the potential energy curves were extrapolated to the complete basis set limit. The spectroscopic parameters were determined. The 1(2)Σ(-), 2(2)Σ(-), 3(2)Σ(-) and 1(4)Σ(+) states may be very difficult to be detected in an experiment, since each of these Λ-S states has only one or two vibrational states. The Franck-Condon factors and radiative lifetimes were calculated for several low vibrational levels of the A(2)Π - X(2)Π, 3(2)Π - a(4)Σ(-), 2(2)Δ - a(4)Σ(-) and 3(2)Σ(-) - 1(2)Σ(-) transitions. The spin-orbit coupling effect on the spectroscopic parameters of the X(2)Π, A(2)Π, 3(2)Π, a(4)Σ(-) and 2(2)Σ(+) states were discussed. The spectroscopic properties reported here can be expected to be reliably predicted ones. PMID:27111157

  7. Spatial modelling of marine organisms in Forsmark and Oskarshamn. Including calculation of physical predictor variables

    Energy Technology Data Exchange (ETDEWEB)

    Carlen, Ida; Nikolopoulos, Anna; Isaeus, Martin (AquaBiota Water Research, Stockholm (SE))

    2007-06-15

    GIS grids (maps) of marine parameters were created using point data from previous site investigations in the Forsmark and Oskarshamn areas. The proportion of global radiation reaching the sea bottom in Forsmark and Oskarshamn was calculated in ArcView, using Secchi depth measurements and the digital elevation models for the respective area. The number of days per year when the incoming light exceeds 5 MJ/m2 at the bottom was then calculated using the result of the previous calculations together with measured global radiation. Existing modelled grid-point data on bottom and pelagic temperature for Forsmark were interpolated to create surface covering grids. Bottom and pelagic temperature grids for Oskarshamn were calculated using point measurements to achieve yearly averages for a few points and then using regressions with existing grids to create new maps. Phytoplankton primary production in Forsmark was calculated using point measurements of chlorophyll and irradiance, and a regression with a modelled grid of Secchi depth. Distribution of biomass of macrophyte communities in Forsmark and Oskarshamn was calculated using spatial modelling in GRASP, based on field data from previous surveys. Physical parameters such as those described above were used as predictor variables. Distribution of biomass of different functional groups of fish in Forsmark was calculated using spatial modelling based on previous surveys and with predictor variables such as physical parameters and results from macrophyte modelling. All results are presented as maps in the report. The quality of the modelled predictions varies as a consequence of the quality and amount of the input data, the ecology and knowledge of the predicted phenomena, and by the modelling technique used. A substantial part of the variation is not described by the models, which should be expected for biological modelling. Therefore, the resulting grids should be used with caution and with this uncertainty kept in mind. All

  8. Spatial modelling of marine organisms in Forsmark and Oskarshamn. Including calculation of physical predictor variables

    International Nuclear Information System (INIS)

    GIS grids (maps) of marine parameters were created using point data from previous site investigations in the Forsmark and Oskarshamn areas. The proportion of global radiation reaching the sea bottom in Forsmark and Oskarshamn was calculated in ArcView, using Secchi depth measurements and the digital elevation models for the respective area. The number of days per year when the incoming light exceeds 5 MJ/m2 at the bottom was then calculated using the result of the previous calculations together with measured global radiation. Existing modelled grid-point data on bottom and pelagic temperature for Forsmark were interpolated to create surface covering grids. Bottom and pelagic temperature grids for Oskarshamn were calculated using point measurements to achieve yearly averages for a few points and then using regressions with existing grids to create new maps. Phytoplankton primary production in Forsmark was calculated using point measurements of chlorophyll and irradiance, and a regression with a modelled grid of Secchi depth. Distribution of biomass of macrophyte communities in Forsmark and Oskarshamn was calculated using spatial modelling in GRASP, based on field data from previous surveys. Physical parameters such as those described above were used as predictor variables. Distribution of biomass of different functional groups of fish in Forsmark was calculated using spatial modelling based on previous surveys and with predictor variables such as physical parameters and results from macrophyte modelling. All results are presented as maps in the report. The quality of the modelled predictions varies as a consequence of the quality and amount of the input data, the ecology and knowledge of the predicted phenomena, and by the modelling technique used. A substantial part of the variation is not described by the models, which should be expected for biological modelling. Therefore, the resulting grids should be used with caution and with this uncertainty kept in mind. All

  9. Non-Born-Oppenheimer calculations of the pure vibrational spectrum of T₂ including relativistic corrections.

    Science.gov (United States)

    Stanke, Monika; Adamowicz, Ludwik

    2014-10-21

    We report very accurate calculations of the complete pure vibrational spectrum of the T2 molecule with an approach where the Born-Oppenheimer (BO) approximation is not assumed. As the considered states correspond to the zero total angular momentum, their non-BO wave functions are spherically symmetric and are expanded in terms of all-particle, one-center, spherically symmetric explicitly correlated Gaussian functions multiplied by even nonnegative powers of the internuclear distance. The nonrelativistic energies of the states obtained in the non-BO calculations are corrected for the relativistic effects of the order of α(2) (where α is the fine structure constant) calculated as expectation values of the operators representing these effects. PMID:25338891

  10. Coulomb dissociation of N,2120

    Science.gov (United States)

    Röder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J. G.; Burgunder, G.; Caamaño, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkäll, Joakim; Chakraborty, S.; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Datta Pramanik, Ushasi; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A.; Farinon, F.; Fraile, Luis M.; Freer, Martin; Freudenberger, M.; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhäuser, Roman; Göbel, Kathrin; Golubev, Pavel; Gonzalez Diaz, D.; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G.; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hâkan; Jonson, Björn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knöbel, Ronja; Kröll, Thorsten; Krücken, Reiner; Kurcewicz, J.; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Le Bleis, Tudi; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Mostazo Caro, Magdalena; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S.; Plag, Ralf; Prochazka, A.; Rahaman, Md. Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M. Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; Sanchez del Rio Saez, Jose; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V.; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J.; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G.; Wimmer, Christine; Winfield, J. S.; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai; R3B Collaboration

    2016-06-01

    Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N,2120 are reported. Relativistic N,2120 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the 19N (n ,γ )20N and 20N (n ,γ ) 21N excitation functions and thermonuclear reaction rates have been determined. The 19 (n ,γ )20N rate is up to a factor of 5 higher at T <1 GK with respect to previous theoretical calculations, leading to a 10% decrease in the predicted fluorine abundance.

  11. A quark model calculation of yy->pipi including final-state interactions

    CERN Document Server

    Blundell, H G; Hay, G; Swanso, E

    2000-01-01

    A quark model calculation of the processes yy->pi+pi- and yy->pipi is performed. At tree level, only charged pions couple to the initial state photons and neutral pions are not exceeded in the final state. However a small but significant cross section is observed. We demonstrate that this may be accounted for by a rotation in isospin space induced by final-state interactions.

  12. Coulombic Fluids Bulk and Interfaces

    CERN Document Server

    Freyland, Werner

    2011-01-01

    Ionic liquids have attracted considerable interest in recent years. In this book the bulk and interfacial physico-chemical characteristics of various fluid systems dominated by Coulomb interactions are treated which includes molten salts, ionic liquids as well as metal-molten salt mixtures and expanded fluid metals. Of particular interest is the comparison of the different systems. Topics in the bulk phase concern the microscopic structure, the phase behaviour and critical phenomena, and the metal-nonmetal transition. Interfacial phenomena include wetting transitions, electrowetting, surface freezing, and the electrified ionic liquid/ electrode interface. With regard to the latter 2D and 3D electrochemical phase formation of metals and semi-conductors on the nanometer scale is described for a number of selected examples. The basic concepts and various experimental methods are introduced making the book suitable for both graduate students and researchers interested in Coulombic fluids.

  13. Adventures in Coulomb Gauge

    Energy Technology Data Exchange (ETDEWEB)

    Greensite, J.; Olejnik, S.

    2003-09-26

    We study the phase structure of SU(2) gauge theories at zero and high temperature, with and without scalar matter fields, in terms of the symmetric/broken realization of the remnant gauge symmetry which exists after fixing to Coulomb gauge. The symmetric realization is associated with a linearly rising color Coulomb potential (which we compute numerically), and is a necessary but not sufficient condition for confinement.

  14. Adventures in Coulomb Gauge

    International Nuclear Information System (INIS)

    We study the phase structure of SU(2) gauge theories at zero and high temperature, with and without scalar matter fields, in terms of the symmetric/broken realization of the remnant gauge symmetry which exists after fixing to Coulomb gauge. The symmetric realization is associated with a linearly rising color Coulomb potential (which we compute numerically), and is a necessary but not sufficient condition for confinement.

  15. Coulomb Drag in Graphene

    OpenAIRE

    Tse, Wang-Kong; Hu, Ben Yu-Kuang; Sarma, S. Das

    2007-01-01

    We study the Coulomb drag between two single graphene sheets in intrinsic and extrinsic graphene systems with no interlayer tunneling. The general expression for the nonlinear susceptibility appropriate for single-layer graphene systems is derived using the diagrammatic perturbation theory, and the corresponding exact zero-temperature expression is obtained analytically. We find that, despite the existence of a non-zero conductivity in an intrinsic graphene layer, the Coulomb drag between int...

  16. Coulomb functions with complex angular momenta

    International Nuclear Information System (INIS)

    The subroutine CCOULM calculates regular and irregular Coulomb functions and their derivatives associated with complex angular momenta. This program may thus be used, for example, in locating Regge poles that appear in atomic and nuclear scattering problems. The calculation utilized the asymptotic expansion method of Froeberg. (Auth.)

  17. Numerical calculation of electromagnetic properties including chirality parameters for uniaxial bianisotropic media

    Science.gov (United States)

    Amirkhizi, Alireza V.; Nemat-Nasser, Sia

    2008-02-01

    Through the use of conductive straight wires or coils the electromagnetic properties of a composite material can be modified. The asymmetric geometry of the coils creates an overall chiral response. The polarization vectors rotate as an electromagnetic wave travels through such a medium. To calculate the chirality of a medium prior to its manufacturing, we developed a method to extract all four electromagnetic material parameter tensors for a general uniaxial bianisotropic composite based on the numerical simulation of the electromagnetic fields. Our method uses appropriate line and surface field averages in a single unit cell of the periodic structure of the composite material. These overall field quantities have physical meaning only when the microscopic variation of the electromagnetic fields in the scale of the unit cell is not important, that is when the wavelength of interest is significantly larger than the maximum linear dimension of the unit cell. The overall constitutive relations of the periodic structure can then be obtained from the relations among the average quantities.

  18. Numerical calculation of electromagnetic properties including chirality parameters for uniaxial bianisotropic media

    International Nuclear Information System (INIS)

    Through the use of conductive straight wires or coils the electromagnetic properties of a composite material can be modified. The asymmetric geometry of the coils creates an overall chiral response. The polarization vectors rotate as an electromagnetic wave travels through such a medium. To calculate the chirality of a medium prior to its manufacturing, we developed a method to extract all four electromagnetic material parameter tensors for a general uniaxial bianisotropic composite based on the numerical simulation of the electromagnetic fields. Our method uses appropriate line and surface field averages in a single unit cell of the periodic structure of the composite material. These overall field quantities have physical meaning only when the microscopic variation of the electromagnetic fields in the scale of the unit cell is not important, that is when the wavelength of interest is significantly larger than the maximum linear dimension of the unit cell. The overall constitutive relations of the periodic structure can then be obtained from the relations among the average quantities

  19. Elastic Coulomb breakup of 34Na

    Science.gov (United States)

    Singh, G.; Shubhchintak, Chatterjee, R.

    2016-08-01

    Background: 34Na is conjectured to play an important role in the production of seed nuclei in the alternate r -process paths involving light neutron rich nuclei very near the β -stability line, and as such, it is important to know its ground state properties and structure to calculate rates of the reactions it might be involved in, in the stellar plasma. Found in the region of `island of inversion', its ground state might not be in agreement with normal shell model predictions. Purpose: The aim of this paper is to study the elastic Coulomb breakup of 34Na on 208Pb to give us a core of 33Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of 34Na. Method: A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of 34Na on 208Pb at 100 MeV/u. The triple differential cross section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum, and angular distributions as well as the average momenta, along with the energy-angular distributions. Results: The total one neutron removal cross section is calculated to test the possible ground state configurations of 34Na. The average momentum results along with energy-angular calculations indicate 34Na to have a halo structure. The parallel momentum distributions with narrow full widths at half-maxima signify the same. Conclusion: We have attempted to analyze the possible ground state configurations of 34Na and in congruity with the patterns in the `island of inversion' conclude that even without deformation, 34Na should be a neutron halo with a predominant contribution to its ground state most probably coming from 33Na(3 /2+)⊗ 2 p3 /2ν configuration. We also surmise that it would certainly be useful and rewarding to test our

  20. Vacuum structure of the Coulomb gas in two dimensions

    International Nuclear Information System (INIS)

    We study the plasma phase of the two-dimensional Coulomb gas in the small density limit. The analysis is done using the correspondence of the Coulomb gas with the 1 + 1 sine-Gordon model, which has been exactly solved by the quantum inverse method. We construct the correct vacuum of the field theory, improving the former results. We obtain exact results for the Coulomb gas, which confirm the previous perturbative calculations. (orig.)

  1. Coulomb corrections for interferometry analysis of expanding hadron systems

    International Nuclear Information System (INIS)

    The problem of the Coulomb corrections to the two-boson correlation functions for the systems formed in ultra-relativistic heavy ion collisions is considered for large effective system volumes. The modification of the standard zero-distance correction (so called Gamow or Coulomb factor) has been proposed for such a kind of systems. For the π+π+ and K+K+ correlation functions the analytical calculations of the Coulomb correction are compared with the exact numerical results. (author)

  2. Yang-Mills theory in Coulomb gauge

    International Nuclear Information System (INIS)

    In this thesis we study the Yang-Mills vacuum structure by using the functional Schroedinger picture in Coulomb gauge. In particular we discuss the scenario of colour confinement, which was originally formulated by Gribov. After a short introduction, we recall some basic aspects of Yang-Mills theories, its canonical quantization in the Weyl gauge and the functional Schroedinger picture. We then consider the minimal Coulomb gauge and the Gribov problem of the gauge theory. The gauge fixing of the Coulomb gauge is done by using the Faddeev-Popov method, which enables the resolution of the Gauss law - the constraint on physical states. In the third chapter, we variationally solve the stationary Yang-Mills Schroedinger equation in Coulomb gauge for the vacuum state. Therefor we use a vacuum wave functional, which is strongly peaked at the Gribov horizon. The vacuum energy functional is calculated and minimized resulting in a set of coupled Schwinger-Dyson equations for the gluon energy, the ghost and Coulomb form factors and the curvature in gauge orbit space. Using the angular approximation these integral equations have been solved analytically in both the infrared and the ultraviolet regime. The asymptotic analytic solutions in the infrared and ultraviolet regime are reasonably well reproduced by the full numerical solutions of the coupled Schwinger-Dyson equations. In the fourth chapter, we investigate the dependence of the Yang-Mills wave functional in Coulomb gauge on the Faddeev-Popov determinant. (orig.)

  3. Screening corrections to the Coulomb crystal elastic moduli

    CERN Document Server

    Baiko, D A

    2016-01-01

    Corrections to elastic moduli, including the effective shear modulus, of a solid neutron star crust due to electron screening are calculated. At any given mass density, the crust is modelled as a body-centred cubic Coulomb crystal of fully ionized atomic nuclei of a single type with a polarizable charge-compensating electron background. Motion of the nuclei is neglected. The electron polarization is described by a simple Thomas-Fermi model of exponential electron screening. The results of numerical calculations are fitted by convenient analytic formulae. They should be used for precise neutron star oscillation modelling, a rapidly developing branch of stellar seismology.

  4. Numerical and experimental study of a radiotherapy treatment planning system including Monte Carlo calculations: heterogeneities and small beams applications

    International Nuclear Information System (INIS)

    Improvements relative to the MC dose calculation speed have been made within the European project MAESTRO by the development of the fast MC code PENFAST and within the TELEDOS project by the parallelization of this code. This PhD work, based on these two projects, focuses on the evaluation of the technical and dosimetric performances of the MC code. These issues are crucial before the use of the MC code in clinical applications. First, variance reduction techniques included in the MC code as well as the parallelization of the calculation have been validated and evaluated in terms of gain in the computing time. The second part of this work has exposed a new, fast and accurate method to determine the initial energy spectrum of the accelerator. This spectrum is required for the MC dose calculation. Afterwards, dose calculations with the fast MC code PENFAST have been evaluated under metrological and clinical conditions. The results showed the ability of the MC code to quickly calculate an accurate dose in both photon and electron modes, even in electronic disequilibrium situations. However, this study revealed an uncertainty, in the TPS-MC, in the conversion of the CT image to voxelized geometry which is used for MC dose calculation. The quality of this voxelization may be improved through an artefacts correction software and by including additional materials in the database of the code. (author)

  5. Third-order transfer matrices calculated for an electrostatic toroidal sector condenser including fringing-field effects

    CERN Document Server

    Mordik, S N

    2002-01-01

    The third-order transfer matrices are calculated for an electrostatic toroidal sector condenser using a rigorously conserved matrix method that implies the conservation of the beam phase volume at each step in the calculations. The transfer matrices (matrizants) obtained, include the fringing-field effect due to the stray fields. In the case of a rectangular distribution of the field components along the optical axis, the analytical expressions for all aberration coefficients, including the dispersion ones, are derived accurate to the third-order terms. In simulations of real fields with the stray field width other than zero, a smooth distribution of the field components is used for which similar aberration coefficients were calculated by means of the conserved numerical method . It has been found that for a smooth model, as the stray field width tends to zero, the aberration coefficients approach the corresponding aberration values in the rectangular model.

  6. Third-order transfer matrices calculated for an electrostatic toroidal sector condenser including fringing-field effects

    International Nuclear Information System (INIS)

    The third-order transfer matrices are calculated for an electrostatic toroidal sector condenser using a rigorously conserved matrix method that implies the conservation of the beam phase volume at each step in the calculations. The transfer matrices (matrizants) obtained, include the fringing-field effect due to the stray fields. In the case of a rectangular distribution of the field components along the optical axis, the analytical expressions for all aberration coefficients, including the dispersion ones, are derived accurate to the third-order terms. In simulations of real fields with the stray field width other than zero, a smooth distribution of the field components is used for which similar aberration coefficients were calculated by means of the conserved numerical method . It has been found that for a smooth model, as the stray field width tends to zero, the aberration coefficients approach the corresponding aberration values in the rectangular model

  7. On Confinement in Coulomb Gauge QCD

    International Nuclear Information System (INIS)

    Full text: We study the quark propagator in Coulomb gauge QCD and employ the corresponding results to calculate meson properties. We demonstrate a mechanism how color non-singlets as e.g. diquarks in the color anti-triplet state are confined. (author)

  8. Bound - states for truncated Coulomb potentials

    OpenAIRE

    Odeh, Maen; Mustafa, Omar

    2000-01-01

    The pseudoperturbative shifted - $l$ expansion technique PSLET is generalized for states with arbitrary number of nodal zeros. Bound- states energy eigenvalues for two truncated coulombic potentials are calculated using PSLET. In contrast with shifted large-N expansion technique, PSLET results compare excellently with those from direct numerical integration.

  9. Analysis of Spent Nuclear Fuel Imaging Using Multiple Coulomb Scattering of Cosmic Muons

    CERN Document Server

    Chatzidakis, Stylianos; Tsoukalas, Lefteri H

    2016-01-01

    Cosmic ray muons passing through matter lose energy from inelastic collisions with electrons and are deflected from nuclei due to multiple Coulomb scattering. The strong dependence of scattering on atomic number Z and the recent developments on position sensitive muon detectors indicate that multiple Coulomb scattering could be an excellent candidate for spent nuclear fuel imaging. Muons present significant advantages over existing monitoring and imaging techniques and can play a central role in monitoring nuclear waste and spent nuclear fuel stored in dense well shielded containers. The main purpose of this paper is to investigate the applicability of multiple Coulomb scattering for imaging of spent nuclear fuel dry casks stored within vertical and horizontal commercial storage dry casks. Calculations of muon scattering were performed for various scenarios, including vertical and horizontal fully loaded dry casks, half loaded dry casks, dry casks with one row of fuel assemblies missing, dry casks with one fu...

  10. MSTor: A program for calculating partition functions, free energies, enthalpies, entropies, and heat capacities of complex molecules including torsional anharmonicity

    Science.gov (United States)

    Zheng, Jingjing; Mielke, Steven L.; Clarkson, Kenneth L.; Truhlar, Donald G.

    2012-08-01

    We present a Fortran program package, MSTor, which calculates partition functions and thermodynamic functions of complex molecules involving multiple torsional motions by the recently proposed MS-T method. This method interpolates between the local harmonic approximation in the low-temperature limit, and the limit of free internal rotation of all torsions at high temperature. The program can also carry out calculations in the multiple-structure local harmonic approximation. The program package also includes six utility codes that can be used as stand-alone programs to calculate reduced moment of inertia matrices by the method of Kilpatrick and Pitzer, to generate conformational structures, to calculate, either analytically or by Monte Carlo sampling, volumes for torsional subdomains defined by Voronoi tessellation of the conformational subspace, to generate template input files, and to calculate one-dimensional torsional partition functions using the torsional eigenvalue summation method. Catalogue identifier: AEMF_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEMF_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 77 434 No. of bytes in distributed program, including test data, etc.: 3 264 737 Distribution format: tar.gz Programming language: Fortran 90, C, and Perl Computer: Itasca (HP Linux cluster, each node has two-socket, quad-core 2.8 GHz Intel Xeon X5560 “Nehalem EP” processors), Calhoun (SGI Altix XE 1300 cluster, each node containing two quad-core 2.66 GHz Intel Xeon “Clovertown”-class processors sharing 16 GB of main memory), Koronis (Altix UV 1000 server with 190 6-core Intel Xeon X7542 “Westmere” processors at 2.66 GHz), Elmo (Sun Fire X4600 Linux cluster with AMD Opteron cores), and Mac Pro (two 2.8 GHz Quad-core Intel Xeon

  11. Holographic Coulomb branch vevs

    CERN Document Server

    Skenderis, K; Skenderis, Kostas; Taylor, Marika

    2006-01-01

    We compute holographically the vevs of all chiral primary operators for supergravity solutions corresponding to the Coulomb branch of N=4 SYM and find exact agreement with the corresponding field theory computation. Using the dictionary between 10d geometries and field theory developed to extract these vevs, we propose a gravity dual of a half supersymmetric deformation of N=4 SYM by certain irrelevant operators.

  12. Remarks on Coulomb effects in multiple scattering theories

    International Nuclear Information System (INIS)

    We investigate the problem of introducing the Coulomb potential in Watson's multiple scattering expansion: in particular we formally analyse the implications for the optical potential and discuss various approximations necessary in order to make practical calculations

  13. Coulomb vs. physical string tension on the lattice

    CERN Document Server

    Burgio, G; Reinhardt, H; Vogt, H

    2015-01-01

    We investigate the precise relationship between the Coulomb and the physical (Wilson) string tension on the lattice, as the former is generally known to give an upper bound for the latter. We give evidence that the two string tensions are in a one to one correspondence at zero temperature, while they become unrelated at finite temperatures. More precisely, we show that the standard lattice calculations of the Coulomb gauge confinement scenario are always tied to the spatial string tension, which is known to survive the deconfinement phase transition and to cause screening effects in the quark-gluon plasma. Our analysis is based on the identification and elimination of center vortices which allows to control the physical string tension and study its effect on the Coulomb gauge observables. We also show how alternative definitions of the Coulomb potential may sense the deconfinement transition, although a true static Coulomb gauge order parameter for the phase transition is still elusive on the lattice.

  14. Quantum defect theory for Coulomb and other potentials in the framework of configuration interaction and implementation to the calculation of 2 D and 2 F o perturbed spectra of Al

    International Nuclear Information System (INIS)

    In continuation of our earlier work on the ab initio calculation of perturbed spectra and on a corresponding quantum defect theory (QDT), we discuss certain essential characteristics having to do with the unification of the continuous and the discrete spectra via the formal and practical construction of smooth quantities without invoking the pair of analytic forms of regular and irregular functions. The theory and its computational methodology are in the framework of configuration interaction (CI), and its structure shows how wavefunctions and properties of excited states of atoms and molecules can be computed provided one uses reliable zero-order basis functions, regardless of whether the relevant potential is, asymptotically, Coulombic or some other type. The mathematical connection with smooth reaction matrices in the discrete spectrum is demonstrated via the Mittag-Leffler theorem for the construction of analytic functions. We compare results for the quantum defects and fine structure from the present theory, as implemented by Komninos et al ( 1995 J. Phys. B: At. Mol. Opt. Phys. 28 2049 , 1996 J. Phys. B: At. Mol. Opt. Phys. 29 L193 ), of the Al spectra of 2 D symmetry (strongly perturbed) and of 2 F o symmetry (weakly perturbed), with the recently reported measurements on high-lying states ( Dyubko et al 2003 J. Phys. B: At. Mol. Opt. Phys. 36 3797 and 4827 ), as well as with those of Eriksson and Isberg (1963 Ark. Fys. 23 527) for the low-lying states. The comparison reveals for the first time very good agreement between theory and experiment for both series. In addition, predictions for the other states of the series are made. Previous computations of the quantum defects of the 2 D spectrum, in general, do not agree among themselves while they deviate from the experimental values

  15. Coulomb pair-creation

    International Nuclear Information System (INIS)

    Electron-positron pair production in strong Coulomb fields is outlined. It is shown that the singular behaviour of the adiabatic basis can be removed if solutions of the time dependent external field Dirac equation are used as a basis to expand the fermion field operator. This latter 'asymptotic basis' makes it possible to introduce Feynman-propagator. Applying the reduction technique, the computation of all of the basic quantities can be reduced to the solution of an integral equation. The positron spectrum for separable potential model with Lorentzian time dependence and for potential jump is analyzed in the pole approximation. (author)

  16. CFD - neutronic coupled calculation of a quarter of a simplified PWR fuel assembly including spacer pressure drop and turbulence enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Pena, C.; Pellacani, F.; Macian Juan, R., E-mail: carlos.pena@ntech.mw.tum.de, E-mail: pellacani@ntech.mw.tum.de, E-mail: macian@ntech.mw.tum.de [Technische Universitaet Muenchen, Garching (Germany). Ntech Lehrstuhl fuer Nukleartechnik; Chiva, S., E-mail: schiva@emc.uji.es [Universitat Jaume I, Castellon de la Plana (Spain). Dept. de Ingenieria Mecanica y Construccion; Barrachina, T.; Miro, R., E-mail: rmiro@iqn.upv.es, E-mail: tbarrachina@iqn.upv.es [Universitat Politecnica de Valencia (ISIRYM/UPV) (Spain). Institute for Industrial, Radiophysical and Environmental Safety

    2011-07-01

    been developed for calculation and synchronization purposes. The data exchange is realized by means of the Parallel Virtual Machine (PVM) software package. In this contribution, steady-state and transient results of a quarter of PWR fuel assembly with cold water injection are presented and compared with obtained results from a RELAP5/PARCS v2.7 coupled calculation. A simplified model for the spacers has been included. A methodology has been introduced to take into account the pressure drop and the turbulence enhancement produced by the spacers. (author)

  17. Practical Methods for Including Torsional Anharmonicity in Thermochemical Calculations on Complex Molecules: The Internal-Coordinate Multi-Structural Approximation

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, J.; Yu, T.; Papajak, E.; Alecu, I. M.; Mielke, S. L.; Truhlar, D. G.

    2011-01-01

    Many methods for correcting harmonic partition functions for the presence of torsional motions employ some form of one-dimensional torsional treatment to replace the harmonic contribution of a specific normal mode. However, torsions are often strongly coupled to other degrees of freedom, especially other torsions and low-frequency bending motions, and this coupling can make assigning torsions to specific normal modes problematic. Here, we present a new class of methods, called multi-structural (MS) methods, that circumvents the need for such assignments by instead adjusting the harmonic results by torsional correction factors that are determined using internal coordinates. We present three versions of the MS method: (i) MS-AS based on including all structures (AS), i.e., all conformers generated by internal rotations; (ii) MS-ASCB based on all structures augmented with explicit conformational barrier (CB) information, i.e., including explicit calculations of all barrier heights for internal-rotation barriers between the conformers; and (iii) MS-RS based on including all conformers generated from a reference structure (RS) by independent torsions. In the MS-AS scheme, one has two options for obtaining the local periodicity parameters, one based on consideration of the nearly separable limit and one based on strongly coupled torsions. The latter involves assigning the local periodicities on the basis of Voronoi volumes. The methods are illustrated with calculations for ethanol, 1-butanol, and 1-pentyl radical as well as two one-dimensional torsional potentials. The MS-AS method is particularly interesting because it does not require any information about conformational barriers or about the paths that connect the various structures.

  18. Calculation of Ground State Rotational Populations for Kinetic Gas Homonuclear Diatomic Molecules including Electron-Impact Excitation and Wall Collisions

    Energy Technology Data Exchange (ETDEWEB)

    David R. Farley

    2010-08-19

    A model has been developed to calculate the ground-state rotational populations of homonuclear diatomic molecules in kinetic gases, including the effects of electron-impact excitation, wall collisions, and gas feed rate. The equations are exact within the accuracy of the cross sections used and of the assumed equilibrating effect of wall collisions. It is found that the inflow of feed gas and equilibrating wall collisions can significantly affect the rotational distribution in competition with non-equilibrating electron-impact effects. The resulting steady-state rotational distributions are generally Boltzmann for N≥3, with a rotational temperature between the wall and feed gas temperatures. The N=0,1,2 rotational level populations depend sensitively on the relative rates of electron-impact excitation versus wall collision and gas feed rates.

  19. EMPLOY: Step-by-step guidelines for calculating employment effects of renewable energy investments [including annex 2

    Energy Technology Data Exchange (ETDEWEB)

    Breitschopf, Barbara [Fraunhofer Inst. for Systems and Innovation Research (Germany); Nathani, Carsten [Ruetter and Partner Socioeconomic Research and Consulting (Switzerland); Resch, Gustav [Vienna Univ. of Technology, Energy Economics Group (EEG) (Austria

    2012-07-15

    The EMPLOY project aimed to help achieve the IEA-RETD’s objective to 'empower policy makers and energy market actors through the provision of information, tools and resources' by underlining the economic and industrial impacts of renewable energy technology deployment and providing reliable methodological approaches for employment – similar to those available for the incumbent energy technologies. The EMPLOY project resulted in a comprehensive set of methodological guidelines for estimating the employment impacts of renewable energy deployment in a coherent, uniform and systematic way. Guidelines were prepared for four different methodological approaches. In the introduction section of the guidelines policy makers are guided in their choice for the most suited approach, depending on the policy questions to be answered, the data availability and budget. The guidelines were tested for the IEA-RETD member state countries and Tunisia. The results of these calculations are included in the annex to the guidelines.

  20. Calculation of the response behaviour of a modern German BWR reactor building including fluid-structure interaction

    International Nuclear Information System (INIS)

    Recent concepts for future german PWR and BWR provide for high-layer water storage pools to ensure core cooling by gravitation (passive system) in the event of loss-of-coolant accidents with small pipes ruptures. Dynamic excitation (e.g. earthquakes) will lead to an interaction between the water in the pools and the reactor building structure. The response behaviour of the reactor building under dynamic excitation is calculated using the finite element codes ABAQUS and PERMAS including fluid-structure interaction and the influence of the subsoil conditions on the response behaviour. The use of nonlinear constitutive equations leads to cracks in the concrete in those regions of the floors where the tensile strength is exceeded. (author). 11 refs., 3 figs

  1. Calculation of the response behaviour of a modern German BWR reactor building including fluid-structure interaction

    Energy Technology Data Exchange (ETDEWEB)

    Altes, J. [Research Center, Juelich GmbH (Germany); Kloster, R. [Essen Univ. (Germany); Wang, T. [Qinghua Univ., Beijing, BJ (China)

    1995-12-31

    Recent concepts for future german PWR and BWR provide for high-layer water storage pools to ensure core cooling by gravitation (passive system) in the event of loss-of-coolant accidents with small pipes ruptures. Dynamic excitation (e.g. earthquakes) will lead to an interaction between the water in the pools and the reactor building structure. The response behaviour of the reactor building under dynamic excitation is calculated using the finite element codes ABAQUS and PERMAS including fluid-structure interaction and the influence of the subsoil conditions on the response behaviour. The use of nonlinear constitutive equations leads to cracks in the concrete in those regions of the floors where the tensile strength is exceeded. (author). 11 refs., 3 figs.

  2. Calculation of Ground State Rotational Populations for Kinetic Gas Homonuclear Diatomic Molecules including Electron-Impact Excitation and Wall Collisions

    International Nuclear Information System (INIS)

    A model has been developed to calculate the ground-state rotational populations of homonuclear diatomic molecules in kinetic gases, including the effects of electron-impact excitation, wall collisions, and gas feed rate. The equations are exact within the accuracy of the cross sections used and of the assumed equilibrating effect of wall collisions. It is found that the inflow of feed gas and equilibrating wall collisions can significantly affect the rotational distribution in competition with non-equilibrating electron-impact effects. The resulting steady-state rotational distributions are generally Boltzmann for N (ge) 3, with a rotational temperature between the wall and feed gas temperatures. The N = 0,1,2 rotational level populations depend sensitively on the relative rates of electron-impact excitation versus wall collision and gas feed rates.

  3. X-ray microbeam radiation therapy calculations, including polarisation effects, with the Monte Carlo code EGS5

    Energy Technology Data Exchange (ETDEWEB)

    Hugtenburg, Richard P., E-mail: r.p.hugtenburg@swansea.ac.u [School of Medicine, Swansea University, Swansea SA2 8PP (United Kingdom); Department of Medical Physics and Clinical Engineering, Abertawe Bro Morgannwg University, LHB, Swansea SA2 8QA (United Kingdom); Adegunloye, A.S.; Bradley, David A. [Department of Physics, Surrey University, Guildford (United Kingdom)

    2010-07-21

    Microbeam radiation therapy (MRT) is currently being considered for the treatment of glioblastoma multiforme. A high degree of dosimetric accuracy (around 5%) is known to be required for a successful outcome in conventional radiation therapy, Modelling of MRT beams, measurements and treatments have been performed with Monte Carlo methods using the code EGS5, which features improved physics models for low energy scattering processes including linear polarisation. Polarisation of the X-ray source leads to distortions in beam profiles that exceed the usual clinical tolerances. Changes in the energy spectrum also effect the response of many dosimetry systems. Anatomical (CT) data has been used in the dose calculations and the manipulation of dose data with the open-source software treatment planning system, PlanUNC, is demonstrated, in order that the therapeutic effects of the different components, e.g. the microbeam and scattered photons, can examined separately in relation to relevant anatomy.

  4. Analytical linear energy transfer model including secondary particles: calculations along the central axis of the proton pencil beam

    Science.gov (United States)

    Marsolat, F.; De Marzi, L.; Pouzoulet, F.; Mazal, A.

    2016-01-01

    In proton therapy, the relative biological effectiveness (RBE) depends on various types of parameters such as linear energy transfer (LET). An analytical model for LET calculation exists (Wilkens’ model), but secondary particles are not included in this model. In the present study, we propose a correction factor, L sec, for Wilkens’ model in order to take into account the LET contributions of certain secondary particles. This study includes secondary protons and deuterons, since the effects of these two types of particles can be described by the same RBE-LET relationship. L sec was evaluated by Monte Carlo (MC) simulations using the GATE/GEANT4 platform and was defined by the ratio of the LET d distributions of all protons and deuterons and only primary protons. This method was applied to the innovative Pencil Beam Scanning (PBS) delivery systems and L sec was evaluated along the beam axis. This correction factor indicates the high contribution of secondary particles in the entrance region, with L sec values higher than 1.6 for a 220 MeV clinical pencil beam. MC simulations showed the impact of pencil beam parameters, such as mean initial energy, spot size, and depth in water, on L sec. The variation of L sec with these different parameters was integrated in a polynomial function of the L sec factor in order to obtain a model universally applicable to all PBS delivery systems. The validity of this correction factor applied to Wilkens’ model was verified along the beam axis of various pencil beams in comparison with MC simulations. A good agreement was obtained between the corrected analytical model and the MC calculations, with mean-LET deviations along the beam axis less than 0.05 keV μm-1. These results demonstrate the efficacy of our new correction of the existing LET model in order to take into account secondary protons and deuterons along the pencil beam axis.

  5. Vacuum polarization of planar Dirac fermions by a superstrong Coulomb potential

    CERN Document Server

    Khalilov, V R

    2016-01-01

    We study the vacuum polarization of planar charged Dirac fermions by a strong Coulomb potential. Induced vacuum charge density is calculated and analyzed at the subcritical and supercritical Coulomb potentials for massless and massive fermions. For the massless case the induced vacuum charge density is localized at the origin when the Coulomb center charge is subcritical while it has a power-law tail when the Coulomb center charge is supercritical. The finite mass contribution into the induced charge due to the vacuum polarization is small and insignificantly distorts the Coulomb potential only at distances of order of the Compton length. The induced vacuum charge has a screening sign. As is known the quantum electrodynamics vacuum becomes unstable when the Coulomb center charge is increased from subcritical to supercritical values. In the supercritical Coulomb potential the quantum electrodynamics vacuum acquires the charge due to the so-called real vacuum polarization. We calculate the real vacuum polarizat...

  6. Reconfiguration and Control of Non-Equal Mass Three-Craft Coulomb Formation

    Science.gov (United States)

    Ting, Wang; Guangqing, Xia; Nan, Zhao

    2016-03-01

    The paper studied reconfiguration of Coulomb formation from three-craft system to four-craft system. Assumed that three-craft Coulomb system already formed a triangle configuration, then, the fourth Coulomb craft is scheduled to join the existing system so as to form a new static configuration. New possible configurations such as quadrilateral in 2-dimension and tetrahedron in 3-dimension for four-craft Coulomb formation are discussed in the paper. The processing of reconfiguration will not change the original origin and triangle formation. Through the Particle Swarm Optimization (PSO) algorithm, the mass, the charge and the position of the fourth Coulomb craft can be calculated for these configurations.

  7. Shot noise in Graphene with long range Coulomb interaction and the local Fermi distribution

    OpenAIRE

    Golub, Anatoly; Horovitz, Baruch

    2009-01-01

    We calculate the shot noise power in ballistic graphene using the kinetic equation approach based on the Keldysh technique. We find that the local energy distribution function obeys Poisson's equation, indicating a mapping into a diffusive metal system. We derive the conductance and noise including the long range Coulomb interaction to first order. We find that the shot noise increases due to interaction, leading to a frequency dependence. Furthermore, we find that the Fano factor at degenera...

  8. Large scale GW calculations

    International Nuclear Information System (INIS)

    We present GW calculations of molecules, ordered and disordered solids and interfaces, which employ an efficient contour deformation technique for frequency integration and do not require the explicit evaluation of virtual electronic states nor the inversion of dielectric matrices. We also present a parallel implementation of the algorithm, which takes advantage of separable expressions of both the single particle Green's function and the screened Coulomb interaction. The method can be used starting from density functional theory calculations performed with semilocal or hybrid functionals. The newly developed technique was applied to GW calculations of systems of unprecedented size, including water/semiconductor interfaces with thousands of electrons

  9. Third order Bose-Einstein correlations by means of Coulomb wave function revisited

    OpenAIRE

    Biyajima, Minoru; Mizoguchi, Takuya; Suzuki, Naomichi

    2005-01-01

    In previous works, in order to include correction by the Coulomb wave function in Bose-Einstein correlations (BEC), the two-body Coulomb scattering wave functions have been utilized in the formulation of three-body BEC. However, the three-body Coulomb scattering wave function, which satisfies approximately the three-body Coulomb scattering Schrodinger equation, cannot be written by the product of the two-body scattering wave functions. Therefore, we reformulate the three-body BEC, and reanaly...

  10. Coulomb's law modification in nonlinear and in noncommutative electrodynamics

    OpenAIRE

    Gaete, Patricio(Departmento de Física and Centro Científico-Tecnológico de Valparaíso, Universidad Técnica Federico Santa María, Valparaiso, Chile); Schmidt, Iván

    2003-01-01

    We study the lowest-order modifications of the static potential for Born-Infeld electrodynamics and for the $\\theta$-expanded version of the noncommutative U(1) gauge theory, within the framework of the gauge-invariant but path-dependent variables formalism. The calculation shows a long-range correction ($1/r^5$-type) to the Coulomb potential in Born-Infeld electrodynamics. However, the Coulomb nature of the potential (to order $e^2$) is preserved in noncommutative electrodynamics.

  11. PREFACE: Strongly Coupled Coulomb Systems

    Science.gov (United States)

    Fortov, Vladimir E.; Golden, Kenneth I.; Norman, Genri E.

    2006-04-01

    This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS) which was held during the week of 20 24 June 2005 in Moscow, Russia. The Moscow conference was the tenth in a series of conferences. The previous conferences were organized as follows. 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (organized by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (organized by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, NY, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) After 1995 the name of the series was changed from `Strongly Coupled Plasmas' to the present name in order to extend the topics of the conferences. The planned frequency for the future is once every three years. The purpose of these conferences is to provide an international forum for the presentation and discussion of research accomplishments and ideas relating to a variety of plasma liquid and condensed matter systems, dominated by strong Coulomb interactions between their constituents. Strongly coupled Coulomb systems encompass diverse many-body systems and physical conditions. Each meeting has seen an evolution of topics and emphasis as new discoveries and new methods appear. This year, sessions were organized for invited presentations and posters on dense plasmas and warm matter, astrophysics and dense hydrogen, non-neutral and ultracold plasmas, dusty plasmas, condensed matter 2D and layered charged-particle systems, Coulomb liquids, and statistical theory of SCCS. Within

  12. Parameterized cross sections for Coulomb dissociation in heavy-ion collisions

    Science.gov (United States)

    Norbury, John W.; Cucinotta, F. A.; Townsend, L. W.; Badavi, F. F.

    1988-01-01

    Simple parameterizations of Coulomb dissociation cross sections for use in heavy-ion transport calculations are presented and compared to available experimental dissociation data. The agreement between calculation and experiment is satisfactory considering the simplicity of the calculations.

  13. Dose calculation models for proton treatment planning using a dynamic beam delivery system: an attempt to include density heterogeneity effects in the analytical dose calculation

    International Nuclear Information System (INIS)

    The gantry for proton radiotherapy at the Paul Scherrer Institute (PSI) is designed specifically for the spot-scanning technique. Use of this technique to its full potential requires dose calculation algorithms which are capable of precisely simulating each scanned beam individually. Different specialized analytical dose calculations have been developed, which attempt to model the effects of density heterogeneities in the patient's body on the dose. Their accuracy has been evaluated by a comparison with Monte Carlo calculated dose distributions in the case of a simple geometrical density interface parallel to the beam and typical anatomical situations. A specialized ray casting model which takes range dilution effects (broadening of the spectrum of proton ranges) into account has been found to produce results of good accuracy. This algorithm can easily be implemented in the iterative optimization procedure used for the calculation of the optimal contribution of each individual scanned pencil beam. In most cases an elemental pencil beam dose calculation has been found to be most accurate. Due to the long computing time, this model is currently used only after the optimization procedure as an alternative method of calculating the dose. (author)

  14. Coulomb Excitation of the N = 50 nucleus 80Zn

    International Nuclear Information System (INIS)

    Neutron rich Zinc isotopes, including the N = 50 nucleus 80Zn, were produced and post-accelerated at the Radioactive Ion Beam (RIB) facility REX-ISOLDE (CERN). Low-energy Coulomb excitation was induced on these isotopes after post-acceleration, yielding B(E2) strengths to the first excited 2+ states. For the first time, an excited state in 80Zn was observed and the 21+ state in 78Zn was established. The measured B(E2,21+→01+) values are compared to two sets of large scale shell model calculations. Both calculations reproduce the observed B(E2) systematics for the full Zinc isotopic chain. The results for N = 50 isotones indicate a good N = 50 shell closure and a strong Z = 28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni

  15. Coulomb dissociation of $^{20,21}$N

    CERN Document Server

    Röder, Marko; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J G; Burgunder, G; Caamano, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkall, Joakim; Chakraborty, S; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Pramanik, Ushasi Datta; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A; Farinon, F; Fraile, Luis M; Freer, Martin; Freudenberger, M; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhäuser, Roman; Göbel, Kathrin; Golubev, Pavel; Diaz, Diego Gonzalez; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hakan; Jonson, Björn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knöbel, Ronja; Kröll, Thorsten; Krücken, Reiner; Kurcewicz, J; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Bleis, Tudi Le; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Caro, Magdalena Mostazo; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S; Plag, Ralf; Prochazka, A; Rahaman, Md Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; Saez, Jose Sanchez del Rio; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G; Wimmer, Christine; Winfield, J S; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai

    2016-01-01

    Neutron-rich light nuclei and their reactions play an important role for the creation of chemical elements. Here, data from a Coulomb dissociation experiment on $^{20,21}$N are reported. Relativistic $^{20,21}$N ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the $^{19}\\mathrm{N}(\\mathrm{n},\\gamma)^{20}\\mathrm{N}$ and $^{20}\\mathrm{N}(\\mathrm{n},\\gamma)^{21}\\mathrm{N}$ excitation functions and thermonuclear reaction rates have been determined. The $^{19}\\mathrm{N}(\\mathrm{n},\\gamma)^{20}\\mathrm{N}$ rate is up to a factor of 5 higher at $T<1$\\,GK with respect to previous theoretical calculations, leading to a 10\\,\\% decrease in the predicted fluorine abundance.

  16. Electroweak Sudakov logarithms in the Coulomb gauge

    OpenAIRE

    Beenakker, W.; Werthenbach, A.

    2000-01-01

    We describe a formalism for calculating electroweak Sudakov logarithms in the Coulomb gauge. This formalism is applicable to arbitrary electroweak processes. For illustration we focus on the specific reactions e^+e^- -> f \\bar{f} and e^+e^- -> W_T^+W_T^-, W_L^+W_L^-, which contain all the salient details of dealing with the various types of particles. We discuss an explicit two-loop calculation and have a critical look at the (non-)exponentiation and factorisation properties of the Sudakov lo...

  17. HPGe detector photopeak efficiency calculation including self-absorption and coincidence corrections for Marinelli beaker sources using compact analytical expressions

    International Nuclear Information System (INIS)

    Direct mathematical methods to calculate total and full-energy peak (photopeak) efficiencies, coincidence correction factors and the source self-absorption of a closed end coaxial HPGe detector for Marinelli beaker sources have been derived. The source self-absorption is determined by calculating the photon path length in the source volume. The attenuation of photons by the Marinelli beaker and the detector cap materials is also calculated. In the experiments gamma aqueous sources containing several radionuclides covering the energy range from 60 to 1836 keV were used. By comparison, the theoretical and experimental full-energy peak efficiency values are in good agreement

  18. Ionic Coulomb Blockade and Resonant Conduction in Biological Ion Channels

    CERN Document Server

    Kaufman, I Kh; Eisenberg, R S

    2014-01-01

    The conduction and selectivity of calcium/sodium ion channels are described in terms of ionic Coulomb blockade, a phenomenon based on charge discreteness and an electrostatic model of an ion channel. This novel approach provides a unified explanation of numerous observed and modelled conductance and selectivity phenomena, including the anomalous mole fraction effect and discrete conduction bands. Ionic Coulomb blockade and resonant conduction are similar to electronic Coulomb blockade and resonant tunnelling in quantum dots. The model is equally applicable to other nanopores.

  19. Coulomb interactions within halo EFT

    International Nuclear Information System (INIS)

    Preliminary results of an effective field theory applied to nuclear cluster systems are presented, where Coulomb interactions play a significant role. Presented at the 20th Few-Body Conference, Pisa, Italy, 10-14 September 2007. (author)

  20. Accurate non-Born-Oppenheimer calculations of the complete pure vibrational spectrum of D2 with including relativistic corrections.

    Science.gov (United States)

    Bubin, Sergiy; Stanke, Monika; Adamowicz, Ludwik

    2011-08-21

    In this work we report very accurate variational calculations of the complete pure vibrational spectrum of the D(2) molecule performed within the framework where the Born-Oppenheimer (BO) approximation is not assumed. After the elimination of the center-of-mass motion, D(2) becomes a three-particle problem in this framework. As the considered states correspond to the zero total angular momentum, their wave functions are expanded in terms of all-particle, one-center, spherically symmetric explicitly correlated Gaussian functions multiplied by even non-negative powers of the internuclear distance. The nonrelativistic energies of the states obtained in the non-BO calculations are corrected for the relativistic effects of the order of α(2) (where α = 1/c is the fine structure constant) calculated as expectation values of the operators representing these effects. PMID:21861559

  1. Complete pure vibrational spectrum of HD calculated without the Born-Oppenheimer approximation and including relativistic corrections

    International Nuclear Information System (INIS)

    All 18 bound pure vibrational levels of the HD molecule have been calculated within the framework that does not assume the Born-Oppenheimer (BO) approximation. The nonrelativistic energies of the states have been corrected for the relativistic effects of the order of α2 (where α is the fine structure constant), calculated using the perturbation theory with the nonrelativistic non-BO wave functions being the zero-order approximation. The calculations were performed by expanding the non-BO wave functions in terms of one-center explicitly correlated Gaussian functions multiplied by even powers of the internuclear distance and by performing extensive optimization of the Gaussian nonlinear parameters. Up to 10 000 basis functions were used for each state.

  2. Analysis and core-life calculation of 3 MW Triga Mark II research reactor including effects of central thimble modification

    International Nuclear Information System (INIS)

    The principal objective of this study was to formulate an effective optimal fuel management strategy for TRIGA MARK II research reactor at AERE, Savar. The core management study has been performed by utilizing four basic types of information calculated for the reactor: criticality, power peaking, neutron flux and burnup calculation. Reshuffling at 20,000 MWh step gives the longest core life of the reactor which is 64500 MWh. Central thimble modification altered the shape of the flux which increased the core reactivity by c 12 and the core-life by 500 MWh. Besides, the study gives valuable insight into the behaviour of the reactor

  3. An independent dose calculation algorithm for MLC-based radiotherapy including the spatial dependence of MLC transmission

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, Friedlieb [Department of Radiation Oncology, Mannheim Medical Centre, University of Heidelberg, Mannheim (Germany); Nalichowski, Adrian [Department of Radiation Oncology, Dana Farber/Brigham and Women' s Cancer Centre, Harvard Medical School, Boston, MA 02115 (United States); Rosca, Florin [Department of Radiation Oncology, Dana Farber/Brigham and Women' s Cancer Centre, Harvard Medical School, Boston, MA 02115 (United States); Killoran, Joseph [Department of Radiation Oncology, Dana Farber/Brigham and Women' s Cancer Centre, Harvard Medical School, Boston, MA 02115 (United States); Wenz, Frederik [Department of Radiation Oncology, Mannheim Medical Centre, University of Heidelberg, Mannheim (Germany); Zygmanski, Piotr [Department of Radiation Oncology, Dana Farber/Brigham and Women' s Cancer Centre, Harvard Medical School, Boston, MA 02115 (United States)

    2008-02-07

    An analytical dose calculation algorithm was developed and commissioned to calculate dose delivered with both static and dynamic multileaf collimator (MLC) in a homogenous phantom. The algorithm is general; however, it was designed specifically to accurately model dose for large and complex IMRT fields. For such fields the delivered dose may have a considerable contribution from MLC transmission, which is dependent upon spatial considerations. Specifically, the algorithm models different MLC effects, such as interleaf transmission, the tongue-and-groove effect, rounded leaf ends, MLC scatter, beam hardening and divergence of the beam, which results in a gradual MLC transmission fall-off with increasing off-axis distance. The calculated dose distributions were compared to measured dose using different methods (film, ionization chamber array, single ionization chamber), and the differences among the treatment planning system, the measurements and the developed algorithm were analysed for static MLC and dynamic IMRT fields. It was found that the calculated dose from the developed algorithm agrees very well with the measurements (mostly within 1.5%) and that a constant value for MLC transmission is insufficient to accurately predict dose for large targets and complex IMRT plans with many monitor units.

  4. HPGe detector photopeak efficiency calculation including self-absorption and coincidence corrections for cylindrical sources using compact analytical expressions

    International Nuclear Information System (INIS)

    Direct mathematical methods to calculate total and photopeak efficiencies, coincidence correction factors and the source medium self-absorption of closed end coaxial HPGe detector for cylindrical sources have been derived. By comparison, the theoretical and experimental efficiency values are in good agreement. (author)

  5. HPGe detector photopeak efficiency calculation including self-absorption and coincidence corrections for cylindrical sources using compact analytical expressions

    International Nuclear Information System (INIS)

    Total and full-energy peak efficiencies, coincidence correction factors and the source self-absorption of a p-type coaxial HPGe detector for cylindrical sources have been calculated using direct analytical expressions. In the experiments gamma aqueous sources containing several radionuclides covering the energy range from 60 to 1836 keV were used. By comparison, the theoretical and experimental full-energy peak efficiency values are in good agreement. (author)

  6. PWR simplified fuel element simulation using calculation trailer ANSYS CFX and PARCS including pressure drop and turbulence in the spacer

    International Nuclear Information System (INIS)

    With the recent development of a new computational tool for calculations of nuclear reactors based on the coupling between the PARCS neutron transport code and computational fluid dynamics commercial code (CFD) ANSYS CFX opens new possibilities in the fuel element design that contributes to a better understanding and a better simulation of the processes of heat transfer and specific phenomena of fluid dynamics as the crossflow.

  7. Enhanced population of side band of {sup 155}Gd in heavy-ion Coulomb excitation

    Energy Technology Data Exchange (ETDEWEB)

    Oshima, Masumi; Hayakawa, Takehito; Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

    1998-03-01

    In the Coulomb excitation of {sup 155}Gd with heavy projectiles, {sup 32}S, {sup 58}Ni and {sup 90}Zr, unexpectedly large enhancement of a positive-parity side band has been observed. This enhancement could not be reproduced by a Coulomb-excitation calculation taking into account the recommended upper limits of E1 or E3 transitions, which are compiled in the whole mass region, and is proportional to the electric field accomplished in the Coulomb-scattering process. (author)

  8. Coulomb screening effect on the nuclear-pasta structure

    OpenAIRE

    Maruyama, Toshiki; Tatsumi, Toshitaka; Voskresensky, Dmitri N.; Tanigawa, Tomonori; Chiba, Satoshi; Maruyama, Tomoyuki

    2004-01-01

    Using the density functional theory (DFT) with the relativistic mean field (RMF) model, we study the non-uniform state of nuclear matter, ``nuclear pasta''. We self-consistently include the Coulomb interaction together with other interactions. It is found that the Coulomb screening effect is significant for each pasta structure but not for the bulk equation of state (EOS) of the nuclear pasta phase.

  9. Poisson's equation solution of Coulomb integrals in atoms and molecules

    Science.gov (United States)

    Weatherford, Charles A.; Red, Eddie; Joseph, Dwayne; Hoggan, Philip

    The integral bottleneck in evaluating molecular energies arises from the two-electron contributions. These are difficult and time-consuming to evaluate, especially over exponential type orbitals, used here to ensure the correct behaviour of atomic orbitals. In this work, it is shown that the two-centre Coulomb integrals involved can be expressed as one-electron kinetic-energy-like integrals. This is accomplished using the fact that the Coulomb operator is a Green's function of the Laplacian. The ensuing integrals may be further simplified by defining Coulomb forms for the one-electron potential satisfying Poisson's equation therein. A sum of overlap integrals with the atomic orbital energy eigenvalue as a factor is then obtained to give the Coulomb energy. The remaining questions of translating orbitals involved in three and four centre integrals and the evaluation of exchange energy are also briefly discussed. The summation coefficients in Coulomb forms are evaluated using the LU decomposition. This algorithm is highly parallel. The Poisson method may be used to calculate Coulomb energy integrals efficiently. For a single processor, gains of CPU time for a given chemical accuracy exceed a factor of 40. This method lends itself to evaluation on a parallel computer.

  10. The Coulomb integrals and the diffraction model of transfer reactions

    International Nuclear Information System (INIS)

    New asymptotic expressions for the Coulomb integrals are derived and compared with numerical results, the Watson asymptotics and the WKB approximations. The analytical expressions for the Coulomb integrals are used in cross section calculations for single-nucleon transfer reactions in the framework of the diffraction model. The case of the zero orbital angular momentum transfer is considered. The interference of the Fresnel and Fraunhofer parts of the reaction amplitude are discused in detail. The undertaken treatment can be useful for the interpretation of the associated experimental data and the results of DWBA calculations. (orig.)

  11. Coulomb drag in multiwall armchair carbon nanotubes

    DEFF Research Database (Denmark)

    Lunde, A.M.; Jauho, Antti-Pekka

    2004-01-01

    We calculate the transresistivity rho(21) between two concentric armchair nanotubes in a diffusive multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F). We approximate the tight-binding band structure by two crossing bands with a linear dispersion near the Fermi...... surface. The cylindrical geometry of the nanotubes and the different parities of the Bloch states are accounted for in the evaluation of the effective Coulomb interaction between charges in the concentric nanotubes. We find a broad peak in rho(21) as a function of temperature at roughly T similar to 0.4T...

  12. Calculations of the flow past bluff bodies, including tilt-rotor wing sections at alpha = 90 deg

    Science.gov (United States)

    Raghavan, V.; Mccroskey, W. J.; Baeder, J. D.; Van Dalsem, W. R.

    1990-01-01

    An attempt was made to model in two dimensions the effects of rotor downwash on the wing of the tilt-rotor aircraft and to compute the drag force on airfoils at - 90 deg angle of attack, using a well-established Navier-Stokes code. However, neither laminar nor turbulent calculations agreed well with drag and base-pressure measurements at high Reynolds numbers. Therefore, further efforts were concentrated on bluff-body flows past various shapes at low Reynolds numbers, where a strong vortex shedding is observed. Good results were obtained for a circular cylinder, but the calculated drag of a slender ellipse at right angles to the freestream was significantly higher than experimental values reported in the literature for flat plates. Similar anomalous results were obtained on the tilt-rotor airfoils, although the qualitative effects of flap deflection agreed with the wind tunnel data. The ensemble of results suggest that there may be fundamental differences in the vortical wakes of circular cylinders and noncircular bluff bodies.

  13. Abinitio calculations of the spectral shapes of CO2 isolated lines including non-Voigt effects and comparisons with experiments

    Science.gov (United States)

    Hartmann, J.-M.; Tran, H.; Ngo, N. H.; Landsheere, X.; Chelin, P.; Lu, Y.; Liu, A.-W.; Hu, S.-M.; Gianfrani, L.; Casa, G.; Castrillo, A.; Lepère, M.; Delière, Q.; Dhyne, M.; Fissiaux, L.

    2013-01-01

    We present a fully ab initio model and calculations of the spectral shapes of absorption lines in a pure molecular gas under conditions where the influences of collisions and of the Doppler effect are significant. Predictions of the time dependence of dipole autocorrelation functions (DACFs) are made for pure CO2 at room temperature using requantized classical molecular dynamics simulations. These are carried, free of any adjusted parameter, on the basis of an accurate anisotropic intermolecular potential. The Fourier-Laplace transforms of these DACFs then yield calculated spectra which are analyzed, as some measured ones, through fits using Voigt line profiles. Comparisons between theory and various experiments not only show that the main line-shape parameters (Lorentz pressure-broadening coefficients) are accurately predicted, but that subtle observed non-Voigt features are also quantitatively reproduced by the model. These successes open renewed perspectives for the understanding of the mechanisms involved (translational-velocity and rotational-state changes and their dependences on the molecular speed) and the quantification of their respective contributions. The proposed model should also be of great help for the test of widely used empirical line-shape models and, if needed, the construction of more physically based ones.

  14. Wave functions of a particle with polarizability in the Coulomb potential

    CERN Document Server

    Kisel, V; Ovsiyuk, E; Amirfachrian, M; Red'kov, V

    2011-01-01

    Quantum mechanical scalar particle with polarizability is considered in the presence of the Coulomb field. Separation of variables is performed with the use of Wigner $D$-functions, the radial system of 15 equations is reduced to a single second order differential equation, which among the Coulomb term includes an additional interaction term of the form \\sigma \\alpha^{2} / M^{2}r^{4}. Various physical regimes exist that is demonstrated by examining the behavior of the curves of generalized squared radial momentum P^{2}(r). Eigenstates of the equations can be constructed in terms of double confluent Heun functions. Numerical analysis proves the existence of the bound states in the system; the lowest energy level and corresponding solution are calculated based on generalization of Ritz variational procedure.

  15. Partial filling affinity capillary electrophoresis including adsorption energy distribution calculations--towards reliable and feasible biomolecular interaction studies.

    Science.gov (United States)

    Witos, Joanna; Samuelsson, Jörgen; Cilpa-Karhu, Geraldine; Metso, Jari; Jauhiainen, Matti; Riekkola, Marja-Liisa

    2015-05-01

    In this work, a method to study and analyze the interaction data in free solution by exploiting partial filling affinity capillary electrophoresis (PF-ACE) followed by adsorption energy distribution calculations (AED) prior model fit to adsorption isotherms will be demonstrated. PF-ACE-AED approach allowed the possibility to distinguish weak and strong interactions of the binding processes between the most common apolipoprotein E protein isoforms (apoE2, apoE3, apoE4) of high density lipoprotein (HDL) and apoE-containing HDL2 with major glycosaminoglycan (GAG) chain of proteoglycans (PGs), chondroitin-6-sulfate (C6S). The AED analysis clearly revealed the heterogeneity of the binding processes. The major difference was that they were heterogeneous with two different adsorption sites for apoE2 and apoE4 isoforms, whereas interestingly for apoE3 and apoE-containing HDL2, the binding was homogeneous (one site) adsorption process. Moreover, our results allowed the evaluation of differences in the binding process strengths giving the following order with C6S: apoE-containing HDL2 > apoE2 > apoE4 > apoE3. In addition, the affinity constant values determined could be compared with those obtained in our previous studies for the interactions between apoE isoforms and another important GAG chain of PGs - dermatan sulfate (DS). The success of the combination of AED calculations prior to non-linear adsorption isotherm model fit with PF-ACE when the concentration range was extended, confirmed the power of the system in the clarification of the heterogeneity of biological processes studied. PMID:25751597

  16. Weak interaction rate Coulomb corrections in big bang nucleosynthesis

    International Nuclear Information System (INIS)

    We have applied a fully relativistic Coulomb wave correction to the weak reactions in the full Kawano/Wagoner big bang nucleosynthesis (BBN) code. We have also added the zero-temperature radiative correction. We find that using this higher accuracy Coulomb correction results in good agreement with previous work, giving only a modest ∼0.04% increase in helium mass fraction over correction prescriptions applied previously in BBN calculations. We have calculated the effect of these corrections on other light element abundance yields in BBN, and we have studied these yields as functions of electron neutrino lepton number. This has allowed insights into the role of the weak neutron-proton interconversion processes in the setting of the neutron-to-proton ratio during the BBN epoch. We find that the lepton capture processes' contributions to this ratio are only second order in the Coulomb correction.

  17. Coulomb explosion of "hot spot"

    CERN Document Server

    Oreshkin, V I; Chaikovsky, S A; Artyomov, A P

    2016-01-01

    The study presented in this paper has shown that the generation of hard x rays and high-energy ions, which are detected in pinch implosion experiments, may be associated with the Coulomb explosion of the hot spot that is formed due to the outflow of the material from the pinch cross point. During the process of material outflow, the temperature of the hot spot plasma increases, and conditions arise for the plasma electrons to become continuously accelerated. The runaway of electrons from the hot spot region results in the buildup of positive space charge in this region followed by a Coulomb explosion. The conditions for the hot spot plasma electrons to become continuously accelerated have been revealed and estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.

  18. Dose conversion coefficients for electron exposure of the human eye lens: Calculations including a whole body phantom

    International Nuclear Information System (INIS)

    In this work, conversion coefficients from electron fluence to absorbed dose to the eye lens were calculated using Monte Carlo simulations based on a detailed stylised eye model and a very simple but whole body phantom. These data supersede and complement data published earlier based on the simulation of only a single stylised eye. The new data differ from the old ones by not more than 3, 4, 7 and 16 % for angles of radiation incidence of α=0 deg., 15 deg., 30 deg. and 45 deg., respectively, due to the inclusion of the whole body phantom. The data presented in the present work also complement those of a recent report of the International Commission on Radiological Protection (ICRP) (ICRP Publication 116), where conversion coefficients from electron fluence to absorbed dose to the lens of the eye are shown for solely 0 deg., 180 deg. and isotropic radiation incidence (but for a much broader range of energies). In this article, values are provided for angles of incidence of 0 deg. up to 180 deg. in steps of 15 deg. and for rotational geometry; no systematic deviation was observed from the values given in ICRP Publication 116 for 0 deg. (based on the application of a bare eye) and 180 deg. (based on the application of a voxel whole body phantom). Data are given for monoenergetic electrons from 0.1 up to 10 MeV and for a broad parallel beam geometry in vacuum. (authors)

  19. Method for calculating carbon footprint of cattle feeds – including contribution from soil carbon changes and use of cattle manure

    DEFF Research Database (Denmark)

    Mogensen, Lisbeth; Kristensen, Troels; Nguyen, T Lan T;

    2014-01-01

    ready to feed’. Included in the study were fodder crops that are grown in Denmark and typically used on Danish cattle farms. The contributions from the growing, processing and transport of feedstuffs were included, as were the changes in soil carbon (soil C) and from land use change (LUC). For each....... However, the livestock system is also credited for the fact that the use of manure reduces the amount of artificial fertilizer being used. Consequently, a manure handling system was set up as a subsystem to the cattle system. This method allowed a comparison between different fodder crops on an equal...... basis. Furthermore, the crop-specific contribution from changes in soil C was estimated based on estimated amounts of C input to the soil....

  20. Coulomb interactions in particle beams

    International Nuclear Information System (INIS)

    This book develops analytical and computer models for beams in which Coulomb interactions are important. The research into the different phenomena of Coulomb interactions in particle beams is stimulated by developments in the field of electron beam lithography for VLSI electronics. The standard theory of charged particle optics breaks down for intense beams in which interactions between particles are significant. This monograph is devoted to the theory of these intense beams, which are not only used in VLSI electronics but also in scanning electron microscopes. The theory is also applicable to focused ion beams, which are used in VLSI mask repair

  1. Renormalization in Coulomb gauge QCD

    International Nuclear Information System (INIS)

    Research highlights: → The Hamiltonian in the Coulomb gauge of QCD contains a non-linear Christ-Lee term. → We investigate the UV divergences from higher order graphs. → We find that they cannot be absorbed by renormalization of the Christ-Lee term. - Abstract: In the Coulomb gauge of QCD, the Hamiltonian contains a non-linear Christ-Lee term, which may alternatively be derived from a careful treatment of ambiguous Feynman integrals at 2-loop order. We investigate how and if UV divergences from higher order graphs can be consistently absorbed by renormalization of the Christ-Lee term. We find that they cannot.

  2. Orientation effect of coulomb interactions in superconducting phase of Rb3 C60 crystal

    International Nuclear Information System (INIS)

    Calculating the Coulomb interaction energies in superconducting phase of Rb3 C60 we find the essential dependences of the ground state energy on rotational angles of spheroidal anions of C603-. The results obtained assume of frozen rotations of fullerene ions in the crystal due to Coulomb fields. 17 refs., 3 figs

  3. Coulomb Correction to the Screening Angle of the Moliere Multiple Scattering Theory

    OpenAIRE

    Kuraev, E. A.; Voskresenskaya, O. O.; Tarasov, A. V.

    2012-01-01

    High-energy Coulomb correction to the screening angular parameter of the Moliere multiple scattering theory is found. Numerical calculations are presented in the range of nuclear charge from Z=4 to Z=82. The accuracy of the Moliere theory in determining the Coulomb correction to the screening angle is estimated.

  4. Role of transfer reactions in heavy-ion collisions at the Coulomb barrier

    Directory of Open Access Journals (Sweden)

    Pollarolo Giovanni

    2011-10-01

    Full Text Available One and two neutron transfer reactions are discussed in the semiclassical formalism. The twoneutrons transfer cross sections are calculated in the successive approximation. Comparisons with new experimental data below the Coulomb barrier are discussed in term of transfer probabilities as a function of the distance of closest approach for Coulomb scattering.

  5. NNLL soft and Coulomb resummation for squark and gluino production at the LHC

    CERN Document Server

    Beneke, Martin; Schwinn, Christian; Wever, Christopher

    2016-01-01

    We present predictions for the total cross sections for pair production of squarks and gluinos at the LHC including a combined NNLL resummation of soft and Coulomb gluon effects. We derive all terms in the NNLO cross section that are enhanced near the production threshold, which include contributions from spin-dependent potentials and so-called annihilation corrections. The NNLL corrections at $\\sqrt{s}=13$ TeV range from up to $20\\%$ for squark-squark production to $90\\%$ for gluino pair production relative to the NLO results and reduce the theoretical uncertainties of the perturbative calculation to the $10\\%$ level. Grid files with our numerical results are publicly available.

  6. Entropic Corrections to Coulomb's Law

    Science.gov (United States)

    Hendi, S. H.; Sheykhi, A.

    2012-04-01

    Two well-known quantum corrections to the area law have been introduced in the literatures, namely, logarithmic and power-law corrections. Logarithmic corrections, arises from loop quantum gravity due to thermal equilibrium fluctuations and quantum fluctuations, while, power-law correction appears in dealing with the entanglement of quantum fields in and out the horizon. Inspired by Verlinde's argument on the entropic force, and assuming the quantum corrected relation for the entropy, we propose the entropic origin for the Coulomb's law in this note. Also we investigate the Uehling potential as a radiative correction to Coulomb potential in 1-loop order and show that for some value of distance the entropic corrections of the Coulomb's law is compatible with the vacuum-polarization correction in QED. So, we derive modified Coulomb's law as well as the entropy corrected Poisson's equation which governing the evolution of the scalar potential ϕ. Our study further supports the unification of gravity and electromagnetic interactions based on the holographic principle.

  7. Intershell resistance in multiwall carbon nanotubes: A Coulomb drag study

    DEFF Research Database (Denmark)

    Lunde, Anders Mathias; Flensborg, Karsten; Jauho, Antti-Pekka

    2005-01-01

    We calculate the intershell resistance R-21 in a multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F) (e.g., a gate voltage), varying the chirality of the inner and outer tubes. This is done in a so-called Coulomb drag setup, where a current I-1 in one shell induces a...

  8. Algebraization of elliptic Coulomb wave functions in the continuous spectrum

    International Nuclear Information System (INIS)

    Trinomial recurrent relations specifying in the continuous spectrum decomposition of elliptical Coulomb wave functions by polar basis of two-dimensional hydrogen atoms are found. This algebraization is suitable for development of the perturbation theory when calculating elliptical corrections to the polar basis

  9. Propagator for an Aharonov-Bohm-Coulomb system

    OpenAIRE

    Park, D. K.; Yoo, Sahng-Kyoon; Lee, Soo-Young; Kahng, Jae-Rok; Park, Chang Soo; Yim, Eui-Soon; Lee, C.H.

    1997-01-01

    The propagator of three-dimensional Aharonov-Bohm-Coulomb system is calculated by following the Duru-Kleinert method. It is shown that the system is reduced to two independent two dimensional Aharonov-Bohm plus harmonic oscillator systems through dimensional extension and Kustaanheimo-Stiefel transformation. The energy spectrum is deduced.

  10. Exchange Coulomb interaction in nanotubes: Dispersion of Langmuir waves

    International Nuclear Information System (INIS)

    The microscopic derivation of the Coulomb exchange interaction for electrons located on the nanotubes is presented. The derivation is based on the many-particle quantum hydrodynamic method. We demonstrate the effect of curvature of the nanocylinders on the force of exchange interaction. We calculate corresponding dispersion dependencies for electron oscillations on the nanotubes

  11. Finiteness of the Coulomb gauge QCD perturbative effective action

    Energy Technology Data Exchange (ETDEWEB)

    Andraši, A., E-mail: aandrasi@irb.hr [Vlaška 58, Zagreb (Croatia); Taylor, J.C., E-mail: jct@damtp.cam.ac.uk [DAMTP, University of Cambridge, Cambridge (United Kingdom)

    2015-05-15

    At 2-loop order in the Coulomb gauge, individual Feynman graphs contributing to the effective action have energy divergences. It is proved that these cancel in suitable combinations of graphs. This has previously been shown only for transverse external fields. The calculation results in a generalization of the Christ–Lee term which was inserted into the Hamiltonian.

  12. Finiteness of the Coulomb gauge QCD perturbative effective action

    CERN Document Server

    Andrasi, A

    2015-01-01

    At 2-loop order in the Coulomb gauge, individual Feynman graphs contributing to the effective action have energy divergences. It is proved that these cancel in suitable combinations of graphs. This has previously been shown only for transverse external fields. The calculation results in a generalization of the Christ-Lee term which was inserted into the Hamiltonian.

  13. Molecular integrals for slater type orbitals using coulomb sturmians

    DEFF Research Database (Denmark)

    Avery, James Emil; Avery, John Scales

    2014-01-01

    The use of Slater type orbitals in molecular calculations is hindered by the slowness of integral evaluation. In the present paper, we introduce a method for overcoming this problem by expanding STO's in terms of Coulomb Sturmians, for which the problem of evaluating molecular integrals rapidly has...

  14. Heavy ion reactions around the Coulomb barrier

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The angular distributions of fission fragments for the 32S+184W reaction near Coulomb barrier energies are measured. The ex perimental fission excitation function is obtained. The measured fission cross sections are decomposed into fusion-fission, quasi-fission and fast fission contributions by the dinuclear system (DNS) model. The hindrance to completing fusion both at small and large collision energies is explained. The fusion excitation functions of 32S+90,96Zr in an energy range from above to below the Coulomb barrier are measured and analyzed within a semi-classical model. The obvious effect of positive Q-value multi-neutron transfers on the sub-barrier fusion enhancement is observed in the 32S+96Zr system. In addition, the excitation functions of quasi-elastic scattering at a backward angle have been measured with high precision for the systems of 16O+208Pb, 196Pt, 184W, and 154,152Sm at energies well below the Coulomb barrier. Considering the deformed coupling effects, the extracted diffuseness parameters are close to the values extracted from the systematic analysis of elastic and inelastic scattering data. The elastic scattering angular distribution of 17F+12C at 60 MeV is measured and calculated by using the continuum-discretized coupled-channels (CDCC) approach. It is found that the diffuseness parameter of the real part of core-target potential has to be increased by 20% to reproduce the experimental result, which corresponds to an increment of potential depth at the surface re gion. The breakup cross section and the coupling between breakup and elastic scattering are small.

  15. Coulomb chronometry to probe the decay mechanism of hot nuclei

    CERN Document Server

    Gruyer, Diego; Bonnet, E; Chbihi, A; Ademard, G; Boisjoli, M; Borderie, B; Bougault, R; Galichet, E; Gauthier, J; Guinet, D; Lautesse, Philippe; Neindre, N Le; Legouée, E; Lopez, O; Marini, P; Mazurek, K; Nadtochy, P N; Pârlog, M; Rivet, M F; Roy, R; Rosato, E; Spadaccini, G; Verde, G; Vient, E; Vigilante, M; Wileczko, J -P

    2013-01-01

    In $^129$Xe+$^{nat}$Sn central collisions from 12 to 25 MeV/A, the three-fragment exit channel occurs with a significant cross section. We show that these fragments arise from two successive binary splittings of a heavy composite system. The sequence of fragment production is unambiguously determined. Strong Coulomb proximity effects are observed in the three fragment final state. A comparison with Coulomb trajectory calculations shows that the time scale between the consecutive break-ups decreases with increasing bombarding energy, becoming quasi-simultaneous above excitation energy $E^*=4.0\\pm0.5$ MeV/A.

  16. Parity Violating Elastic Electron Scattering and Coulomb Distortions

    CERN Document Server

    Horowitz, C J

    1998-01-01

    Parity violating elastic electron-nucleus scattering provides an accurate and model independent measurement of neutron densities, because the $Z^0$ couples primarily to neutrons. Coulomb distortion corrections to the parity violating asymmetry $A_l$ are calculated exactly using a relativistic optical model. Distortions significantly reduce $A_l$ in a heavy nucleus. However even with distortions, an experiment to measure the neutron radius is feasible. This will aid the interpretation of future atomic parity violation measurements and provide fundamental nuclear structure information. Coulomb distortions and small differences between neutron and proton radii could be important for a standard model test on $^4$He, $^{12}$C or $^{16}$O.

  17. Gribov horizon and Gribov copies effect in lattice Coulomb gauge

    CERN Document Server

    Burgio, Giuseppe; Reinhardt, Hugo; Vogt, Hannes

    2016-01-01

    Following a recent proposal by Cooper and Zwanziger we investigate via lattice simulations the effect on the Coulomb gauge propagators and on the Gribov-Zwanziger confinement mechanism of selecting the Gribov copy with the smallest non-trivial eigenvalue of the Faddeev-Popov operator, i.e. the one closest to the Gribov horizon. Although such choice of gauge drives the ghost propagator towards the prediction of continuum calculations, we find that it actually overshoots the goal. With increasing computer time, we observe that Gribov copies with arbitrarily small eigenvalues can be found. For such a method to work one would therefore need further restrictions on the gauge condition to isolate the physically relevant copies, since e.g. the Coulomb potential $V_C$ defined through the Faddeev-Popov operator becomes otherwise physically meaningless. Interestingly, the Coulomb potential alternatively defined through temporal link correlators is only marginally affected by the smallness of the eigenvalues.

  18. Quark Coulomb Interactions and the Mass Difference of Mirror Nuclei

    CERN Document Server

    Horowitz, C J

    2001-01-01

    We study the Okamoto-Nolen-Schiffer (ONS) anomaly in the binding energy of mirror nuclei at high density by adding a single neutron or proton to a quark gluon plasma. In this high-density limit we find an anomaly equal to two-thirds of the Coulomb exchange energy of a proton. This effect is dominated by quark electromagnetic interactions---rather than by the up-down quark mass difference. At normal density we calculate the Coulomb energy of neutron matter using a string-flip quark model. We find a nonzero Coulomb energy because of the neutron's charged constituents. This effect could make a significant contribution to the ONS anomaly.

  19. Coulomb field in a constant electromagnetic background

    CERN Document Server

    Adorno, T C; Shabad, A E

    2016-01-01

    Nonlinear Maxwell equations are written up to the third-power deviations from a constant-field background, valid within any local nonlinear electrodynamics including QED with Euler-Heisenberg effective Lagrangian. Linear electric response to imposed static finite-sized charge is found in the vacuum filled by an arbitrary combination of constant and homogeneous electric and magnetic fields. The modified Coulomb field, corrections to the total charge and to the charge density are given in terms of derivatives of the effective Lagrangian with respect to the field invariants.

  20. Plane density of induced vacuum charge in a supercritical Coulomb potential

    CERN Document Server

    Khalilov, V R

    2016-01-01

    An expression for the density of a planar induced vacuum charge is obtained in a strong Coulomb potential in coordinate space. Treatment is based on a self-adjoint extension approach for constructing of the Green's function of a charged fermion in this potential. Induced vacuum charge density is calculated and analyzed at the subcritical and supercritical Coulomb potentials for massless and massive fermions. The behavior of the obtained vacuum charge density is investigated at long and short distances from the Coulomb center. The induced vacuum charge has a screening sign. Screening of a Coulomb impurity in graphene is briefly discussed. We calculate the real vacuum polarization charge density that acquires the quantum electrodynamics vacuum in the supercritical Coulomb potential due to the so-called real vacuum polarization. It is shown that the vacuum charge densities essentially differ in massive and massless cases. We expect that our results can, as a matter of principle, be tested in graphene with a supe...

  1. Coulomb excitation of radioactive {sup 79}Pb

    Energy Technology Data Exchange (ETDEWEB)

    Lister, C.J.; Blumenthal, D.; Davids, C.N. [and others

    1995-08-01

    The technical challenges expected in experiments with radioactive beams can already be explored by using ions produced in primary reactions. In addition, the re-excitation of these ions by Coulomb excitation allows a sensitive search for collective states that are well above the yrast line. We are building an experiment to study Coulomb excitation of radioactive ions which are separated from beam particles by the Fragment Mass Analyzer. An array of gamma detectors will be mounted at the focal plane to measure the gamma radiation following re-excitation. Five Compton-suppressed Ge detectors and five planar LEPS detectors will be used. The optimum experiment of this type appears to be the study of {sup 79}Rb following the {sup 24}Mg ({sup 58}Ni,3p) reaction. We calculate that about 5 x 10{sup 5} {sup 79}Rb nuclei/second will reach the excitation foil. This rubidium isotope was selected for study as it is strongly produced and is highly deformed, so easily re-excited. The use of a {sup 58}Ni re-excitation foil offers the best yields. After re-excitation the ions will be subsequently transported into a shielded beamdump to prevent the accumulation of activity.

  2. Coulomb dissociation in nonrelativistic and relativistic collisions

    International Nuclear Information System (INIS)

    Electromagnetic excitations in the Coulomb field of nuclei have been studied using quantum as well as semiclassical methods. Even at relatively modest incident energies, the Coulomb dissociation cross sections of projectiles with relatively low particle thresholds could be of sizeable order of magnitude. Such a study complements our knowledge about radiative capture processes, which are of interest for nuclear astrophysics. Quite a few questions remain to be answered, like the importance of nuclear interactions for small angle scattering, interference of different multipolarities for triple differentiial cross sections and distortion effects on the three-body final states. In the case of dissociation at relativistic energies it is shown that only for the total cross section both semiclassical and quantim-mechanical methods yield the same results. As an example the Primakoff effect is considered, where in an M1 excitation of ≅ 80 MeV a Λ hyperion is converted into a Σo hyperion by means of the virtual photon field of heavy target nuclei. Virtual photon spectra for all multipolarities can be calculated. This provides a sound basis for the analysis of electromagnetic dissociation experiments at relativistic heavy ion accelerators, like the BEVALAC. 10 figs., 25 refs

  3. A variational approach to the structure and thermodynamics of linear polyelectrolytes with Coulomb and screened Coulomb interactions

    CERN Document Server

    Jönsson, B; Söderberg, B

    1993-01-01

    A variational approach is used to calculate free energy and conformational properties in polyelectrolytes. The true bond and Coulomb potentials are approximated by a trial isotropic harmonic energy containing monomer-monomer force constants as variational parameters. By a judicious choice of representation and the use of incremental matrix inversion, an efficient and fast-convergent iterative algorithm is constructed, that optimizes the free energy. The computational demand scales as N^3. The method has the additional advantage that the entropy is easily computed. An analysis of the high and low temperature limits is given. Also, the variational formulation is shown to respect the appropriate virial identities. The accuracy of the approximations introduced are tested against Monte Carlo simulations for problem sizes ranging from N=20 to 1024. Very good performance is obtained for chains with unscreened Coulomb interactions. The addition of salt is described through a screened Coulomb interaction, for which th...

  4. Coulomb interactions in Ga LMIS

    Czech Academy of Sciences Publication Activity Database

    Radlička, Tomáš; Lencová, Bohumila

    2008-01-01

    Roč. 108, č. 5 (2008), s. 445-454. ISSN 0304-3991 Grant ostatní: EC 5RP(XE) G5RD-CT-2000-00344 Institutional research plan: CEZ:AV0Z20650511 Source of funding: R - rámcový projekt EK Keywords : liquid-metal ion sources * Coulomb interactions * energy width * virtual source size Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.629, year: 2008

  5. Coulomb Corrections to the Parameters of the Moliere Multiple Scattering Theory

    OpenAIRE

    Kuraev, Eduard; Voskresenskaya, Olga; Tarasov, Alexander

    2013-01-01

    High-energy Coulomb corrections to the parameters of the Moliere multiple scattering theory are obtained. Numerical calculations are presented in the range of the nuclear charge number of the target atom 4

  6. Multiple Coulomb excitation experiment of 68Zn

    International Nuclear Information System (INIS)

    Coulomb excitation experiment was carried out with a 68Zn beam bombarding a natPb target. Two E2 matrix elements and the quadrupole moment of the 21+ state were newly derived with the least-squares search code GOSIA. The potential energy surface (PES) was calculated with the Nilsson-Strutinsky model, showing two shallow minima: the first minimum does not contain the 1g9/2 orbit below the Fermi surface, while the second minimum does. The ground state band and the intruder band seem to be constructed on the first and the second minimum, respectively. As for the ground state band, the asymmetric rotor model and the IBM in O(6) limit reproduced the experimental values rather well. The shallow PES may suggest instability of the shape. The ground state band structure may be explained assuming a soft triaxial deformation

  7. Retardation effects and the Coulomb pseudopotential in the theory of superconductivity

    OpenAIRE

    Bauer, Johannes; Han, Jong E.; Gunnarsson, Olle

    2012-01-01

    In the theory of electron-phonon superconductivity both the magnitude of the electron-phonon coupling $\\lambda$ as well as the Coulomb pseudopotential $\\mu^*$ are important to determine the transition temperature $T_c$ and other properties. We calculate corrections to the conventional result for the Coulomb pseudopotential. Our calculation are based on the Hubbard-Holstein model, where electron-electron and electron-phonon interactions are local. We develop a perturbation expansion, which acc...

  8. Ab initio effective core potentials including relativistic effects and their application to the electronic structure calculations of heavy atoms and molecules

    International Nuclear Information System (INIS)

    The effects of the 4f shell of electrons and the relativity of valence electrons are compared. The effect of 4f shell (lanthanide contraction) is estimated from the numerical Hartree-Fock (HF) calculations of pseudo-atoms corresponding to Hf, Re, Au, Hg, Tl, Pb and Bi without 4f electrons and with atomic numbers reduced by 14. The relativistic effect estimated from the numerical Dirac-Hartree-Fock (DHF) calculations of those atoms is comparable in the magnitude with that of the 4f shell of electrons. Both are larger for 6s than for 5d or 6p electrons. The various relativistic effects on valence electrons are discussed in detail to determine the proper level of the approximation for the valence electron calculations of systems with heavy elements. An effective core potential system has been developed for heavy atoms in which relativistic effects are included in the effective potentials

  9. Ab initio effective core potentials including relativistic effects and their application to the electronic structure calculations of heavy atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.S.

    1977-11-01

    The effects of the 4f shell of electrons and the relativity of valence electrons are compared. The effect of 4f shell (lanthanide contraction) is estimated from the numerical Hartree-Fock (HF) calculations of pseudo-atoms corresponding to Hf, Re, Au, Hg, Tl, Pb and Bi without 4f electrons and with atomic numbers reduced by 14. The relativistic effect estimated from the numerical Dirac-Hartree-Fock (DHF) calculations of those atoms is comparable in the magnitude with that of the 4f shell of electrons. Both are larger for 6s than for 5d or 6p electrons. The various relativistic effects on valence electrons are discussed in detail to determine the proper level of the approximation for the valence electron calculations of systems with heavy elements. An effective core potential system has been developed for heavy atoms in which relativistic effects are included in the effective potentials.

  10. Coherent superposition in the coulomb explosion spectra of H2+

    International Nuclear Information System (INIS)

    Graphical abstract: Schematic diagram for charge-resonance enhanced ionization (CREI) and the calculated kinetic energy spectra of proton from the Coulomb explosion of H2+ with 100 fs, 791 nm laser pulses, the peak laser intensities are from 5.0 x 1013 to 8.8 x 1013 W/cm2. Display Omitted Highlights: → Our quantum dynamics calculations confirm the multi-peak structures in CE spectra. → The main sharp peaks are attributed to vibrationally coherent superposition. → The structures disappear at relative higher laser intensities. - Abstract: Quantum wave packet calculations have been carried out to interpret the multi-peak structures in the Coulomb explosion spectra at low laser intensities from 5.0 x 1013 to 8.8 x 1013 W/cm2. A clear mechanism in comparison with experiment is presented. The calculated results confirm the previous experimental observations. The main sharp peaks can be attributed to vibrationally coherent superposition. It is different from the proposed explanation of the recent experimental measurements, in which each main peak is attributed to Coulomb explosion occurring at the same critical internuclear distance for all definite vibrational levels after the dissociation of the molecular ion. Moreover, our calculations indicate that these structures disappear at relative higher laser intensities, which is also consistent with the experiment.

  11. Quantum confinement effect and effective coulomb interaction in doped T-shaped semiconductor quantum wire

    International Nuclear Information System (INIS)

    In this paper, we study the quantum confinement effect and effective Coulomb interaction in doped semiconductor quantum wire based on a two-band model. Single particle wave-function of carriers in T-shaped GaAs quantum wire can be obtained by finite-element solution of Schrodinger equation with complex boundary condition. The effective Coulomb interactions are calculated by using envelop function approximation. Due to their heavier mass, the quantum confinement effect of heavy holes is stronger than the electrons, The effective h-h Coulomb interaction increases with the intensity of electric field, while e-e Coulomb interaction decreases with increasing intensity of electric field. The e-h Coulomb interaction shows complicated dependency on electric field, which indicates competition of localization and delocalization characters in electron and hole. (authors)

  12. CubeSat testing of Coulomb drag propulsion

    CERN Document Server

    Janhunen, Pekka; Toivanen, Petri; Rauhala, Timo; Haeggström, Edward; Grönland, Tor-Arne

    2016-01-01

    In Coulomb drag propulsion, a long high voltage tether or system of tethers gathers momentum from a natural plasma stream such as solar wind or ionospheric plasma ram flow. A positively polarised tether in the solar wind can be used for efficient general-purpose interplanetary propellantless propulsion (the electric solar wind sail or E-sail), whereas a negatively polarised tether in LEO can be used for efficient deorbiting of satellites (the plasma brake). Aalto-1 is a 3-U cubesat to be launched in May 2016. The satellite carries three scientific experiments including 100 m long Coulomb drag tether experiment. The tether is made of four 25 and 50 micrometre diameter aluminium wires that are ultrasonically bonded together every few centimetre intervals. The tether can be charged by an onboard voltage source up to one kilovolt positive and negative. The Coulomb drag is measured by monitoring the spin rate.

  13. Strong Coulomb effects in hole-doped Heisenberg chains

    Science.gov (United States)

    Schnack, J.

    2005-06-01

    Substances such as the “telephone number compound” Sr14Cu24O41 are intrinsically hole-doped. The involved interplay of spin and charge dynamics is a challenge for theory. In this article we propose to describe hole-doped Heisenberg spin rings by means of complete numerical diagonalization of a Heisenberg Hamiltonian that depends parametrically on hole positions and includes the screened Coulomb interaction among the holes. It is demonstrated that key observables like magnetic susceptibility, specific heat, and inelastic neutron scattering cross section depend sensitively on the dielectric constant of the screened Coulomb potential.

  14. The effect of Coulombic friction on spatial displacement statistics

    CERN Document Server

    Menzel, Andreas M

    2010-01-01

    The phenomenon of Coulombic friction enters the stochastic description of dry friction between two solids and the statistic characterization of vibrating granular media. Here we analyze the corresponding Fokker-Planck equation including both velocity and spatial components, exhibiting a formal connection to a quantum mechanical harmonic oscillator in the presence of a delta potential. Numerical solutions for the resulting spatial displacement statistics show a crossover from exponential to Gaussian displacement statistics. We identify a transient intermediate regime that exhibits multiscaling properties arising from the contribution of Coulombic friction. These results are relevant to recent experimental studies of the displacement of colloidal particles along bilayer membrane tubes.

  15. Study of ultrasonic attenuation in f-electron systems in the paramagnetic limit of Coulomb interaction

    International Nuclear Information System (INIS)

    We report here a microscopic model study of ultrasonic attenuation in f-electron systems based on Periodic Anderson Model in which Coulomb interaction is considered within a mean-field approximation for a weak interaction. The Phonon is coupled to the conduction band and f-electrons. The phonon Green's function is calculated by Zubarev's technique of the Green's function method. The temperature dependent ultrasonic attenuation co-efficient is calculated from the imaginary part of the phonon self-energy in the dynamic and long wave length limit. The f-electron occupation number is calculated self-consistently in paramagnetic limit of Coulomb interaction. The effect of the Coulomb interaction on ultrasonic attenuation is studied by varying the phonon coupling parameters to the conduction and f-electrons, hybridization strength, the position of f-level and the Coulomb interaction Strength. Results are discussed on the basis of experimental results

  16. PREFACE: Strongly Coupled Coulomb Systems Strongly Coupled Coulomb Systems

    Science.gov (United States)

    Neilson, David; Senatore, Gaetano

    2009-05-01

    This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS), held from 29 July-2 August 2008 at the University of Camerino. Camerino is an ancient hill-top town located in the Apennine mountains of Italy, 200 kilometres northeast of Rome, with a university dating back to 1336. The Camerino conference was the 11th in a series which started in 1977: 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (hosted by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (hosted by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, New York, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) 2005: Moscow, Russia (hosted by Vladimir E Fortov and Vladimir Vorob'ev). The name of the series was changed in 1996 from Strongly Coupled Plasmas to Strongly Coupled Coulomb Systems to reflect a wider range of topics. 'Strongly Coupled Coulomb Systems' encompasses diverse many-body systems and physical conditions. The purpose of the conferences is to provide a regular international forum for the presentation and discussion of research achievements and ideas relating to a variety of plasma, liquid and condensed matter systems that are dominated by strong Coulomb interactions between their constituents. Each meeting has seen an evolution of topics and emphases that have followed new discoveries and new techniques. The field has continued to see new experimental tools and access to new strongly coupled conditions, most recently in the areas of warm matter, dusty plasmas

  17. Coulomb-Blockade Oscillations in Semiconductor Nanostructures

    OpenAIRE

    Houten, van, H.; Beenakker, C. W. J.; Staring, A.A.M.

    2005-01-01

    I. Introduction (Preface, Basic properties of semiconductor nanostructures). II. Theory of Coulomb-blockade oscillations (Periodicity of the oscillations, Amplitude and lineshape). III. Experiments on Coulomb-blockade oscillations (Quantum dots, Disordered quantum wires, Relation to earlier work on disordered quantum wires). IV. Quantum Hall effect regime (The Aharonov-Bohm effect in a quantum dot, Coulomb blockade of the Aharonov-Bohm effect, Experiments on quantum dots, Experiments on disor...

  18. Coseismic Coulomb stress changes caused by the Mw6.9 Yutian earthquake in 2014 and its correlation to the 2008 Mw7.2 Yutian earthquake

    Science.gov (United States)

    Li, Yujiang; Chen, Lianwang; Liu, Shaofeng; Yang, Shuxin; Yang, Xingyue; Zhang, Guangwei

    2015-06-01

    A three-dimensional viscoelastic finite element model of the Qinghai-Tibet Plateau and its adjacent regions was used to explore the relationship between the Mw7.2 Yutian earthquake in 2008 and the 2014 Mw6.9 Yutian earthquake. We further analyzed the Coulomb failure stress change caused by the Yutian Mw6.9 earthquake on faults surrounding the Bayan Har block and discussed the relationship between the Coulomb stress change and aftershock distribution. The preliminary results showed that: (1) The Coulomb failure stress change caused by the Mw7.2 Yutian earthquake in 2008, which was projected on the slip direction of the 2014 Yutian Mw6.9 earthquake, exceeded the earthquake triggering threshold of 0.01 MPa, implying an apparent triggering effect. Specifically, the coseismic Coulomb failure stress changes were 0.0167 MPa and 0.0170 MPa when assuming apparent friction coefficients of 0.4 and 0.6, respectively. The Coulomb failure stress changes, including viscoelastic relaxation effects, were 0.0187 MPa and 0.0194 MPa respectively. Combined with the tectonic stressing rate, the Mw6.9 Yutian earthquake in 2014 was advanced 21.4-24.9 years by the 2008 Mw7.2 Yutian earthquake; (2) The stress changes derived from the viscoelastic relaxation effect were much less than that from the coseismic effect, which was possibly interpreted as the shorter elapsed time between the two earthquakes relative to the characteristic time; (3) The Coulomb failure stresses increased on the mid-northern segment of the Altyn Tagh fault, the middle segment of the Mani-Yushu fault and the western segment of the eastern Kunlun fault, which demonstrated increasing seismic potential. In particular, the Coulomb failure stress on the middle segment of the Altyn Tagh fault increased by 2.8 × 103 Pa, the most significant increase. In contrast, the Coulomb failure stress decreased on the western segment of the Mani-Yushu and Minjiang faults, with the western segment of the Mani-Yushu fault dropping by 3

  19. Triangular Spin-Orbit-Coupled Lattice with Strong Coulomb Correlations: Sn Atoms on a SiC(0001) Substrate.

    Science.gov (United States)

    Glass, S; Li, G; Adler, F; Aulbach, J; Fleszar, A; Thomale, R; Hanke, W; Claessen, R; Schäfer, J

    2015-06-19

    Two-dimensional (2D) atom lattices provide model setups with Coulomb correlations that induce competing ground states. Here, SiC emerges as a wide-gap substrate with reduced screening. We report the first artificial high-Z atom lattice on SiC(0001) by Sn adatoms, based on experimental realization and theoretical modeling. Density-functional theory of our triangular structure model closely reproduces the scanning tunneling microscopy. Photoemission data show a deeply gapped state (∼2  eV gap), and, based on our calculations including dynamic mean-field theory, we argue that this reflects a pronounced Mott-insulating scenario. We also find indications that the system is susceptible to antiferromagnetic superstructures. Such artificial lattices on SiC(0001) thus offer a novel platform for coexisting Coulomb correlations and spin-orbit coupling, with bearing for unusual magnetic phases and proposed topological quantum states of matter. PMID:26197013

  20. Experimental Studies of the Coulomb Force Effects in Deuteron-Proton Break-up Reaction at Medium Energy Regime

    Science.gov (United States)

    Ciepał, I.; Parol, W.; Kalantar-Nayestanaki, N.; Khatri, G.; Kistryn, St.; Kłos, B.; Kozela, A.; Kulessa, P.; Messchendorp, J.; Skwira-Chalot, I.; Stephan, E.; Włoch, B.

    2016-03-01

    A set of differential cross-section data of the 1H(d, pp)n breakup reaction at 130 and 160 MeV deuteron beam energies has been measured in the forward polar angles domain. The data were collected with the use of the Germanium Wall (FZ Jülich) and BINA (KVI Groningen) detectors. This part of the phase-space is special with respect to the dominant Coulomb force influence on the system dynamics. The data are compared with the theoretical calculations based on the Argonne V18 potential supplemented with the long-range electromagnetic component. The predictions also include the Urbana IX three nucleon force model. The strongest Coulomb effects are found in regions where the relative energy of the two protons is the smallest.

  1. Revised variational approach to QCD in Coulomb gauge

    CERN Document Server

    Campagnari, Davide R; Reinhardt, Hugo; Vastag, Peter

    2016-01-01

    The variational approach to QCD in Coulomb gauge is revisited. By assuming the non-Abelian Coulomb potential to be given by the sum of its infrared and ultraviolet parts, i.e.~by a linearly rising potential and an ordinary Coulomb potential, and by using a Slater determinant ansatz for the quark wave functional, which contains the coupling of the quarks and the gluons with two different Dirac structures, we obtain variational equations for the kernels of the fermionic vacuum wave functional, which are free of ultraviolet divergences. Thereby, a Gaussian type wave functional is assumed for the gluonic part of the vacuum. By using the results of the pure Yang--Mills sector for the gluon propagator as input, we solve the equations for the fermionic kernels numerically and calculate the quark condensate and the effective quark mass in leading order. Assuming a value of $\\sigma_{\\mathrm{C}} = 2.5 \\sigma$ for the Coulomb string tension (where $\\sigma$ is the usual Wilsonian string tension) the phenomenological valu...

  2. Scaling laws for near barrier Coulomb and Nuclear Breakup

    CERN Document Server

    Hussein, M S; Lubian, J; Otomar, D R; Canto, L F

    2013-01-01

    We investigate the nuclear and the Coulomb contributions to the breakup cross sections of $^6$Li in collisions with targets in different mass ranges. Comparing cross sections for different targets at collision energies corresponding to the same $E/V_{\\mathrm{\\scriptscriptstyle B}}$, we obtain interesting scaling laws. First, we derive an approximate linear expression for the nuclear breakup cross section as a function of $A_{\\mathrm{% \\scriptscriptstyle T}}^{1/3}$. We then confirm the validity of this expression performing CDCC calculations. Scaling laws for the Coulomb breakup cross section are also investigated. In this case, our CDCC calculations indicate that this cross section has a linear dependence on the atomic number of the target. This behavior is explained by qualitative arguments. Our findings, which are consistent with previously obtained results for higher energies, are important when planning for experiments involving exotic weakly bound nuclei.

  3. Theory of charge transport in molecular junctions: From Coulomb blockade to coherent tunneling

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yao-Wen; Jin, Bih-Yaw, E-mail: byjin@ntu.edu.tw [Department of Chemistry and Center for Emerging Material and Advanced Devices and Center for Quantum Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2014-08-14

    We study charge transport through molecular junctions in the presence of electron-electron interaction using the nonequilibrium Green's function techniques and the renormalized perturbation theory. In the perturbation treatment, the zeroth-order Hamiltonian of the molecular junction is composed of independent single-impurity Anderson's models, which act as the channels where charges come through or occupy, and the interactions between different channels are treated as the perturbation. Using this scheme, the effects of molecule-lead, electron-electron, and hopping interactions are included nonperturbatively, and the charge transport processes can thus be studied in the intermediate parameter range from the Coulomb blockade to the coherent tunneling regimes. The concept of quasi-particles is introduced to describe the kinetic process of charge transport, and then the electric current can be studied and calculated. As a test study, the Hubbard model is used as the molecular Hamiltonian to simulate dimeric and trimeric molecular junctions. Various nonlinear current-voltage characteristics, including Coulomb blockade, negative differential resistance, rectification, and current hysteresis, are shown in the calculations, and the mechanisms are elucidated.

  4. Theory of charge transport in molecular junctions: From Coulomb blockade to coherent tunneling

    International Nuclear Information System (INIS)

    We study charge transport through molecular junctions in the presence of electron-electron interaction using the nonequilibrium Green's function techniques and the renormalized perturbation theory. In the perturbation treatment, the zeroth-order Hamiltonian of the molecular junction is composed of independent single-impurity Anderson's models, which act as the channels where charges come through or occupy, and the interactions between different channels are treated as the perturbation. Using this scheme, the effects of molecule-lead, electron-electron, and hopping interactions are included nonperturbatively, and the charge transport processes can thus be studied in the intermediate parameter range from the Coulomb blockade to the coherent tunneling regimes. The concept of quasi-particles is introduced to describe the kinetic process of charge transport, and then the electric current can be studied and calculated. As a test study, the Hubbard model is used as the molecular Hamiltonian to simulate dimeric and trimeric molecular junctions. Various nonlinear current-voltage characteristics, including Coulomb blockade, negative differential resistance, rectification, and current hysteresis, are shown in the calculations, and the mechanisms are elucidated

  5. HCI-induced molecule fragmentation: non-Coulombic explosion and three-body effects

    International Nuclear Information System (INIS)

    The study of highly charged ion-induced diatomic (CO) and triatomic (CO2) molecules fragmentation by the coincident measurement of the fragment momenta is presented. It is shown that the experimental results together with ab initio calculations including a large number of potential energy curves evidence the limitation of the Coulomb explosion model to reproduce the dynamics of the fragmentation. The geometry modification of the CO2 molecule during the breakup is explored and the concerted or sequential nature of the dissociation is discussed for two fragmentation channels. Finally, the fragmentation of the H2 molecules following collisions with slow multicharged ions is analysed for various projectiles and energies. From the energy spectra, the effect of the projectile on the H+ fragments is evidenced. This three-body effect is discussed in connection with the results of two model calculations including or not the role of the projectile. (orig.)

  6. Superheavy Elements and Beyond: - Supercritical Coulomb Field and Giant Quasiatoms

    International Nuclear Information System (INIS)

    The status of theory of Superheavy Nuclei is reviewed. Based with the Two-Center Shell Model Potential Energy Surfaces are calculated. Fusion, fission, quasifission and other processes are discussed. I particular time-delay during the formation of giant quasi atoms/molecules will be crucial for observing the change of the Dirac vacuum in supercritical Coulomb fields by spontaneous positron emission. It will be shown how the various phenomena are interrelated

  7. Three-body processes in the presence of Coulomb forces

    International Nuclear Information System (INIS)

    Rigorous definitions are provided for the scattering amplitudes describing elastic, inelastic and rearrangement reactions of one charged particle and a bound state of two other charged bodies, and of break-up amplitudes with one neutral and two charged particles. The resulting expressions confirm, and give precise meaning to, what is intuitively anticipated in conventional approaches. Furthermore, integral equations for these transition amplitudes are available which render feasible practical calculations of Coulomb corrections in three-particle reactions. 2 references

  8. Quantum Monte Carlo calculations of electromagnetic moments and transitions in A{<=}9 nuclei including meson-exchange currents derived from chiral effective field theory

    Energy Technology Data Exchange (ETDEWEB)

    Saori Pastore, S.C. Pieper, Rocco Schiavilla, Robert Wiringa

    2013-03-01

    Quantum Monte Carlo calculations of electromagnetic moments and transitions are reported for A{<=}9 nuclei. The realistic Argonne v{sub 18} two-nucleon and Illinois-7 three-nucleon potentials are used to generate the nuclear wave functions. Contributions of two-body meson-exchange current (MEC) operators are included for magnetic moments and M1 transitions. The MEC operators have been derived in both a standard nuclear physics approach and a chiral effective field theory formulation with pions and nucleons including up to one-loop corrections. The two-body MEC contributions provide significant corrections and lead to very good agreement with experiment. Their effect is particularly pronounced in the A=9, T=3/2 systems, in which they provide up to ~20% (~40%) of the total predicted value for the {sup 9}Li ({sup 9}C) magnetic moment.

  9. Thermodynamic Curvature and Phase Transitions from Black Hole with a Coulomb-Like Field

    Institute of Scientific and Technical Information of China (English)

    HAN Yi-Wen; BAO Zhi-Qing; HONG Yun

    2011-01-01

    In this paper, we first investigate the thermodynamic features of the black hole with a coulomb-like field.Moreover, we obtain the geometric description of the black hole thermodynamics.We find that for the black hole with a coulomb-like field the Weinhold geometry is flat, whereas its Ruppeiner geometry is curved.For the heat capacity and curvature calculation shows the Ruppeiner geometry has a transition point.

  10. The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.

    Science.gov (United States)

    Francisco, E.; And Others

    1988-01-01

    Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)

  11. Numerical calculation of MHD equilibria including static magnetic islands in a straight heliotron configuration by means of a field line tracing method

    International Nuclear Information System (INIS)

    Magnetohydrodynamics (MHD) equilibria including static magnetic islands for the reduced MHD equations in a straight heliotron plasma are calculated. The equilibria are obtained as the solution of the coupled equations of the constant pressure along each field line and the force balance. The former and the latter equations are solved by means of a field line tracing method and a relaxation method, respectively. There exist two kinds of solutions. One is the equilibrium of which the pressure profile is flat at the O-point and steep at the X-point. In this case, the pressure gradient is discontinuous at the separatrix of the magnetic island. The other is the equilibrium of which the pressure profile is flat at not only the O-point but also the X-point. In the case, the pressure gradient is continuous at the separatrix. (author)

  12. The comparison among distorted wave,plane wave and coulomb wave in the calculation of triple differential cross section for ionization of hydrogen%氢原子电离三重微分截面计算中扭曲波、平面波和库仑波的比较

    Institute of Scientific and Technical Information of China (English)

    章韦芳; 贾昌春; 肖全志; 陈姣姣

    2011-01-01

    在玻恩近似理论中分别采用扭曲波、平面波、库仑波,计算在250、150、54.4 eV三种入射能下氢原子(e,2e)反应的三重微分截面(TDCS),并与实验数据进行对比.发现在这些入射能下,采用扭曲波和平面波描述入射电子所得的TDCS相差不大;但当考虑散射电子与核的库仑相互作用时,其计算结果比扭曲波描述的更符合实验数据.%In the(e,2e)reaction of hydrogen,distorted wave,plane wave and Coulomb wave in the Born approximation theory were to calculate the triple differential cross sections(TDCS)at incident energies of 250,150 and 54.4 eV respectively,and the theoretical results were compared with experiments.The authors found that there was little difference between the results from the two models,one using the description of plane wave and the other of distorted wave.However,if the interaction between the scattered electron and the nucleus was considered,the result of the calculation coincided with the result of the experiments was better-than the calculation resulted from the description of distorted wave.

  13. Coulomb effects in low-energy nuclear fragmentation

    Science.gov (United States)

    Wilson, John W.; Chun, Sang Y.; Badavi, Francis F.; John, Sarah

    1993-01-01

    Early versions of the Langley nuclear fragmentation code NUCFRAG (and a publicly released version called HZEFRG1) assumed straight-line trajectories throughout the interaction. As a consequence, NUCFRAG and HZEFRG1 give unrealistic cross sections for large mass removal from the projectile and target at low energies. A correction for the distortion of the trajectory by the nuclear Coulomb fields is used to derive fragmentation cross sections. A simple energy-loss term is applied to estimate the energy downshifts that greatly alter the Coulomb trajectory at low energy. The results, which are far more realistic than prior versions of the code, should provide the data base for future transport calculations. The systematic behavior of charge-removal cross sections compares favorably with results from low-energy experiments.

  14. Hadron diffractive scattering at ultrahigh energies and coulomb interaction

    CERN Document Server

    Anisovich, V V

    2016-01-01

    We study the interplay of hadronic and Coulomb interactions for $pp$ scattering at LHC energies on the basis of the previous determination of the real part of the amplitude [{\\it V.V. Anisovich, V.A. Nikonov, J. Nyiri}, Int. J. Mod. Phys. A{\\bf 30}, 1550188 (2015)]. The interference of hadron and Coulomb interactions is discussed in terms of the $K$-matrix function technique. Supposing the black disk mode for the asymptotic interaction of hadrons, we calculate interference effects for the energies right up to $\\sqrt{s}= 10^6$ TeV. It turns out that the real part of the amplitude is concentrated in the impact parameter space at the border of the black disk that results in a growth of interplay effects with the energy increase.

  15. Suitability of linear quadrupole ion traps for large Coulomb crystals

    CERN Document Server

    Tabor, D A; Odom, B

    2011-01-01

    Growing and studying large Coulomb crystals, composed of tens to hundreds of thousands of ions, in linear quadrupole ion traps presents new challenges for trap implementation. We consider several trap designs, first comparing the total driven micromotion amplitude as a function of location within the trapping volume; total micromotion is an important point of comparison since it can limit crystal size by transfer of radiofrequency drive energy into thermal energy. We also compare the axial component of micromotion, which leads to first-order Doppler shifts along the preferred spectroscopy axis in precision measurements on large Coulomb crystals. Finally, we compare trapping potential anharmonicity, which can induce nonlinear resonance heating by shifting normal mode frequencies onto resonance as a crystal grows. We apply a non-deforming crystal approximation for simple calculation of these anharmonicity-induced shifts, allowing a straightforward estimation of when crystal growth can lead to excitation of diff...

  16. Coulomb field of an accelerated charge physical and mathematical aspects

    CERN Document Server

    Alexander, F J; Alexander, Francis J.; Gerlach, Ulrich H.

    1991-01-01

    The Maxwell field equations relative to a uniformly accelerated frame, and the variational principle from which they are obtained, are formulated in terms of the technique of geometrical gauge invariant potentials. They refer to the transverse magnetic (TM) and the transeverse electric (TE) modes. This gauge invariant "2+2" decomposition is used to see how the Coulomb field of a charge, static in an accelerated frame, has properties that suggest features of electromagnetism which are different from those in an inertial frame. In particular, (1) an illustrative calculation shows that the Larmor radiation reaction equals the electrostatic attraction between the accelerated charge and the charge induced on the surface whose history is the event horizon, and (2) a spectral decomposition of the Coulomb potential in the accelerated frame suggests the possibility that the distortive effects of this charge on the Rindler vacuum are akin to those of a charge on a crystal lattice.

  17. Antiproton-Nucleus Interaction and Coulomb Effect at High Energies

    Institute of Scientific and Technical Information of China (English)

    ZHOU Li-Juan; WU Qing; GU Yun-Ting; MA Wei-Xing; TAN Zhen-Qiang; HU Zhao-Hui

    2005-01-01

    The Coulomb effect in high energy antiproton-nucleus elastic and inelastic scattering from 12C and 16O is studied in the framework of Glauber multiple scattering theory for five kinetic energies ranged from 0.23 to 1.83 GeV.A microscopic shell-model nuclear wave functions, Woods-Saxon single-particle wave functions, and experimental pN amplitudes are used in the calculations. The results show that the Coulomb effect is of paramount importance for filling up the dips of differential cross sections. We claim that the present result for inelastic scattering of antiproton-12C is sufficiently reliable to be a guide for measurements in the very near future. We also believe that antiproton nucleus elastic and inelastic scattering may produce new information on both the nuclear structure and the antinucleon-nucleon interaction, in particular the p-neutron interaction.

  18. Scalar-QED ℎ-corrections to the Coulomb potential

    International Nuclear Information System (INIS)

    The leading long-distance 1-loop quantum corrections to the Coulomb potential are derived for scalar QED and their gauge-independence is explicitly checked. The potential is obtained from the direct calculation of the 2-particle scattering amplitude, taking into account all relevant 1-loop diagrams. Our investigation should be regarded as first step towards the same programme for effective Quantum Gravity. In particular, with our calculation in the framework of scalar QED, we are able to demonstrate the incompleteness of some previous studies concerning the quantum Gravity counterpart. (author)

  19. Halo nuclei with the Coulomb-Sturmian basis

    CERN Document Server

    Caprio, M A; Vary, J P

    2014-01-01

    The rapid falloff of the oscillator functions at large radius (Gaussian asymptotics) makes them poorly suited for the description of the asymptotic properties of the nuclear wave function, a problem which becomes particularly acute for halo nuclei. We consider an alternative basis for ab initio no-core configuration interaction (NCCI) calculations, built from Coulomb-Sturmian radial functions, allowing for realistic (exponential) radial falloff. NCCI calculations are carried out for the neutron-rich He isotopes, and estimates are made for the RMS radii of the proton and neutron distributions.

  20. Triple-differential cross section of the 208Pb(6Li, αd)208 Pb Coulomb breakup and astrophysical S-factor of the d(α,γ)6 Li reaction at extremely low energies

    International Nuclear Information System (INIS)

    A method of calculation of the triple-differential cross section of the 208Pb(6Li, αd)208Pb Coulomb breakup at astrophysically relevant energies E of the relative motion of the breakup fragments, taking into account the three-body (α - d - 208Pb) Coulomb effects and the contributions from the E1- and E2- multipoles, including their interference, has been proposed. The new results for the astrophysical S-factor of the direct radiative capture d(α, γ)6 Li reaction at E ≤ 250 keV have been obtained. It is shown that the experimental triple-differential cross section of the 208Pb(6Li, αd)208Pb Coulomb breakup can also be used to give information about the value of the modulus squared of the nuclear vertex constant for the virtual 6Li → α + d. (author)

  1. Simulation of Coulomb interaction effects in electron sources

    International Nuclear Information System (INIS)

    Over many years, we have developed electron source simulation software that has been used widely in the electron optics community to aid the development of rotationally symmetric electron and ion guns. The simulation includes the modelling of cathode emission and the effects of volumetric space charge. In the present paper we describe the existing software and explain how we have extended this software to include the effects of discrete Coulomb interactions between the electrons as they travel from the cathode surface to the exit of the gun. In the paper, we will describe the numerical models we have employed, the techniques we have used to maximize the speed of the Coulomb force computation and present several illustrative examples of cases analyzed using the new software, including thermal field emitters, LaB6 guns and flat dispenser-type cathodes.

  2. Simulation of Coulomb interaction effects in electron sources

    Science.gov (United States)

    Rouse, John; Zhu, Xieqing; Liu, Haoning; Munro, Eric

    2011-07-01

    Over many years, we have developed electron source simulation software that has been used widely in the electron optics community to aid the development of rotationally symmetric electron and ion guns. The simulation includes the modelling of cathode emission and the effects of volumetric space charge. In the present paper we describe the existing software and explain how we have extended this software to include the effects of discrete Coulomb interactions between the electrons as they travel from the cathode surface to the exit of the gun. In the paper, we will describe the numerical models we have employed, the techniques we have used to maximize the speed of the Coulomb force computation and present several illustrative examples of cases analyzed using the new software, including thermal field emitters, LaB 6 guns and flat dispenser-type cathodes.

  3. Simulation of Coulomb interaction effects in electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Rouse, John, E-mail: john@mebs.co.uk [Munro' s Electron Beam Software Ltd., 14 Cornwall Gardens, London SW7 4AN (United Kingdom); Zhu Xieqing; Liu Haoning; Munro, Eric [Munro' s Electron Beam Software Ltd., 14 Cornwall Gardens, London SW7 4AN (United Kingdom)

    2011-07-21

    Over many years, we have developed electron source simulation software that has been used widely in the electron optics community to aid the development of rotationally symmetric electron and ion guns. The simulation includes the modelling of cathode emission and the effects of volumetric space charge. In the present paper we describe the existing software and explain how we have extended this software to include the effects of discrete Coulomb interactions between the electrons as they travel from the cathode surface to the exit of the gun. In the paper, we will describe the numerical models we have employed, the techniques we have used to maximize the speed of the Coulomb force computation and present several illustrative examples of cases analyzed using the new software, including thermal field emitters, LaB{sub 6} guns and flat dispenser-type cathodes.

  4. Coulomb continuum effects in molecular interference

    International Nuclear Information System (INIS)

    We study analytically the interference in photoionization of molecules by monochromatic and attosecond x-ray pulses. Using the hydrogen molecule ion as a test case, we obtain simple analytical factors describing the Coulomb continuum molecular interference. We show how chirped attosecond pulse with a frequency-dependent phase and broad bandwidth creates the continuous photoelectron spectra. Due to the long-range Coulomb forces, the plane wave interference patterns are strongly modified by two-centre Coulomb continuum even at large internuclear distances. (letter to the editor)

  5. Comparison of simplified sum-over-state expressions to calculate resonance Raman intensities including Franck-Condon and Herzberg-Teller effects

    Science.gov (United States)

    Guthmuller, Julien

    2016-02-01

    Sum-over-state (SOS) expressions to simulate absorption spectroscopy and resonance Raman (RR) scattering including Franck-Condon (FC) and Herzberg-Teller (HT) effects are described. Starting from the general SOS method, several simplified SOS formulae are derived. In particular, within the so-called independent mode displaced harmonic oscillator model, it is shown that including the vibronic structure in the absorption and RR spectra only requires the calculation of FC overlap integrals of the type , where g, e, and v stand for the electronic ground state, excited state, and vibrational quantum number, respectively. Additionally, an approximation of the latter approach is introduced, referred as the simplified Φe method, in which the FC factors are neglected. This method is advantageous from the computational point of view and it is demonstrated that it reproduces the main characteristics of the more involved approaches. The merits and drawbacks of the different methods are discussed by applying them to the prototypical compound of Rhodamine 6G. Overall, this work intends to unravel and clarify some differences in the SOS theories of RR scattering.

  6. Coulomb Friction Driving Brownian Motors

    International Nuclear Information System (INIS)

    We review a family of models recently introduced to describe Brownian motors under the influence of Coulomb friction, or more general non-linear friction laws. It is known that, if the heat bath is modeled as the usual Langevin equation (linear viscosity plus white noise), additional non-linear friction forces are not sufficient to break detailed balance, i.e. cannot produce a motor effect. We discuss two possibile mechanisms to elude this problem. A first possibility, exploited in several models inspired to recent experiments, is to replace the heat bath's white noise by a “collisional noise”, that is the effect of random collisions with an external equilibrium gas of particles. A second possibility is enlarging the phase space, e.g. by adding an external potential which couples velocity to position, as in a Klein—Kramers equation. In both cases, non-linear friction becomes sufficient to achieve a non-equilibrium steady state and, in the presence of an even small spatial asymmetry, a motor effect is produced. (general)

  7. Deep inelastic scattering near the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Gehring, J.; Back, B.; Chan, K. [and others

    1995-08-01

    Deep inelastic scattering was recently observed in heavy ion reactions at incident energies near and below the Coulomb barrier. Traditional models of this process are based on frictional forces and are designed to predict the features of deep inelastic processes at energies above the barrier. They cannot be applied at energies below the barrier where the nuclear overlap is small and friction is negligible. The presence of deep inelastic scattering at these energies requires a different explanation. The first observation of deep inelastic scattering near the barrier was in the systems {sup 124,112}Sn + {sup 58,64}Ni by Wolfs et al. We previously extended these measurements to the system {sup 136}Xe + {sup 64}Ni and currently measured the system {sup 124}Xe + {sup 58}Ni. We obtained better statistics, better mass and energy resolution, and more complete angular coverage in the Xe + Ni measurements. The cross sections and angular distributions are similar in all of the Sn + Ni and Xe + Ni systems. The data are currently being analyzed and compared with new theoretical calculations. They will be part of the thesis of J. Gehring.

  8. Electromagnetic load calculation of the ITER machine using a single finite element model including narrow slits of the in-vessel components

    International Nuclear Information System (INIS)

    Highlights: • Electromagnetic (EM) loads were calculated on the ITER machine for various disruption scenarios. • Plenty of narrow slits in the in-vessel components were numerically modeled without increase of the computation memory. • Time-varying plasma data obtained from plasma simulation were precisely converted to the finite element model. • We investigated the worst disruption case and its consequent design-driving force for each ITER system. • Effect of the narrow slits on EM loads was also investigated. -- Abstract: We evaluate electromagnetic (EM) loads on the main systems of the ITER machine using a single finite element model. The 20° sector of the full ITER machine includes the main in-vessel components as well as the vacuum vessel. Narrow slits of the in-vessel components are effectively modeled by using the element splitting method without significant increase of computation memory and time as well as without sacrificing the accuracy. Furthermore, the halo current is taken into account at the same time together with the plasma current. To apply both currents concurrently, dedicated conversion codes are utilized to transfer the plasma simulation results by DINA to the electromagnetic analysis by ANSYS-EMAG used here. The electromagnetic loads on the ITER machine are calculated for various disruption scenarios. Investigation on the analysis results is made to find the worst plasma disruption case and the design-driving load component for each system as well as to compare load contribution from eddy and halo currents. The effect of the narrow slits on load reduction is also examined

  9. On the effect of Coulomb interaction on the multiphoton ionization probability

    International Nuclear Information System (INIS)

    The nonresonant multiphoton ionization problem is considered in the case of one-dimensional Coulomb potential. The continuous spectrum wave function in the presence of electromagnetic field and Coulomb interaction is calculated in the quasiclassical approximation. The Coulomb interaction is taken into account by the use of the perturbation theory in that part of action which arises due to interaction with an electromagnetic field. Criteria of this approximation validity are found and it is shown that such an approach allows the process of nonresonant multiphoton ionization to be described in the field range εa (εa is the characteristic atomic field) for arbitrary values of the adiabaticity parameter γ. Within the range γ>>1 the Coulomb factor in the ionization probability is independing of the field strength and has to be taken into account

  10. Quarks in Coulomb gauge perturbation theory

    CERN Document Server

    Popovici, C; Reinhardt, H

    2008-01-01

    Coulomb gauge quantum chromodynamics within the first order functional formalism is considered. The quark contributions to the Dyson-Schwinger equations are derived and one-loop perturbative results for the two-point functions are presented.

  11. Numerical path integration with Coulomb potential

    OpenAIRE

    Myrheim, Jan

    2003-01-01

    A simple and efficient method for quantum Monte Carlo simulation is presented, based on discretization of the action in the path integral, and a Gaussian averaging of the potential, which works well e.g. with the Coulomb potential.

  12. Aspects of Confinement in Coulomb Gauge

    CERN Document Server

    Greensite, Jeff

    2009-01-01

    I present some new results regarding confinement as it appears in Coulomb gauge. It is found that: i) a recently proposed Yang-Mills vacuum wavefunctional in temporal gauge and 2+1 dimensions yields a Coulomb-gauge ghost propagator and linear Coulomb potential in good agreement with lattice Monte Carlo results; ii) adding a few constituent gluons to heavy quark-antiquark states brings the interaction energy much closer to that of the static quark potential, and suggests the beginnings of gluon-chain formation at roughly one fermi; iii) a perturbative approach to Faddeev-Popov eigenvalues indicates that the zero eigenvalue at the Gribov horizon may occur either at, or away from, p=0, depending on the gauge choice and spacetime dimension. This last result may be relevant to the qualitatively different infrared behavior of the ghost propagator in Coulomb and Landau gauges.

  13. Coulomb Interaction Does Not Spread Instantaneously

    CERN Document Server

    Tzontchev, R I; Rivera-Juarez, J M

    2000-01-01

    The experiment is described which shows that Coulomb interaction spreads with a limit velocity and thus this kind of interaction cannot be considered as so called "instantaneous action at a distance".

  14. Coulomb dissociation at nonrelativistic and relativistic energies

    International Nuclear Information System (INIS)

    The author studies the breakup of deuterons on nuclei in the framework of DWBA theories which are based on the spectator model. The discrepancies for heavy targets are explained by the mechanism of the Coulomb dissociation. (HSI)

  15. Comments on Coulomb pairing in aromatic hydrocarbons

    CERN Document Server

    Huber, D L

    2013-01-01

    Recently reported anomalies in the double-photonionization spectra of aromatic molecules such as benzene, naphthalene, anthracene and coronene are attributed to Coulomb-pair resonances of pi electrons.

  16. On the modelling of Coulomb friction

    Science.gov (United States)

    Cull, S. J.; Tucker, R. W.

    1999-03-01

    This paper analyses two different representations of Coulomb friction in the context of a dynamic simulation of the torsional vibrations of a driven drill-string. A simple model is used to compare the relative merits of a piecewise analytic approach using a discontinuous friction profile to a numerical integration using a smooth nonlinear representation of the Coulomb friction. In both cases the effects of viscous damping on the excitation of torsional relaxation oscillations are exhibited.

  17. Cavity QED experiments with ion Coulomb crystals

    DEFF Research Database (Denmark)

    Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan; Albert, Magnus; Drewsen, Michael

    Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained.......Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained....

  18. Coulomb interaction effect in tilted Weyl fermion in two dimensions

    OpenAIRE

    Isobe, Hiroki; Nagaosa, Naoto

    2015-01-01

    Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor $\\alpha$-(BEDT-TTF)$_2$I$_3$ and three-dimensional WTe$_2$. The Coulomb interaction between electrons modifies the velocities in an essential way in the low-energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the...

  19. Exponential representation in the Coulomb three-body problem

    International Nuclear Information System (INIS)

    The exponential representation in the Coulomb three-body problem is considered. It is shown that the exponential variational expansion in relative coordinates r32, r31 and r21 has a number of advantages for the bound state calculations in Coulomb three-body systems. Moreover, it appears that the exponential (or Laplace-Fourier) representation of the Coulomb three-body problem is an optimal approach to analyse and solve various three-body problems. The optimization of nonlinear parameters in the trial wavefunctions is also considered. The developed methods are used to determine the highly accurate ground 11S(L = 0)-state energies and other bound state properties for a number of He-like two-electron ions (Li+, Be2+, B3+, C4+, N5+, O6+, F7+ and Ne8+). To represent the ground state energies of these He-like ions we apply the Z-1 expansion. The asymptotic form of the ground state wavefunctions at large electron-nuclear distances for the He-like ions is briefly discussed. Considered hypervirial theorems are of great interest for these ions, since they allow one to obtain some useful relations between different expectation values. The generalization of the exponential variational expansion in relative coordinates to the four-body non-relativistic systems is also considered

  20. Dynamical Coulomb blockade of tunnel junctions driven by alternating voltages

    Science.gov (United States)

    Grabert, Hermann

    2015-12-01

    The theory of the dynamical Coulomb blockade is extended to tunneling elements driven by a time-dependent voltage. It is shown that, for standard setups where an external voltage is applied to a tunnel junction via an impedance, time-dependent driving entails an excitation of the modes of the electromagnetic environment by the applied voltage. Previous approaches for ac driven circuits need to be extended to account for the driven bath modes. A unitary transformation involving also the variables of the electromagnetic environment is introduced which allows us to split off the time dependence from the Hamiltonian in the absence of tunneling. This greatly simplifies perturbation-theoretical calculations based on treating the tunneling Hamiltonian as a perturbation. In particular, the average current flowing in the leads of the tunnel junction is studied. Explicit results are given for the case of an applied voltage with a constant dc part and a sinusoidal ac part. The connection with standard dynamical Coulomb blockade theory for constant applied voltage is established. It is shown that an alternating voltage source reveals significant additional effects caused by the electromagnetic environment. The hallmark of the dynamical Coulomb blockade in ac driven devices is a suppression of higher harmonics of the current by the electromagnetic environment. The theory presented basically applies to all tunneling devices driven by alternating voltages.

  1. Photoelectron wave function in photoionization: plane wave or Coulomb wave?

    Science.gov (United States)

    Gozem, Samer; Gunina, Anastasia O; Ichino, Takatoshi; Osborn, David L; Stanton, John F; Krylov, Anna I

    2015-11-19

    The calculation of absolute total cross sections requires accurate wave functions of the photoelectron and of the initial and final states of the system. The essential information contained in the latter two can be condensed into a Dyson orbital. We employ correlated Dyson orbitals and test approximate treatments of the photoelectron wave function, that is, plane and Coulomb waves, by comparing computed and experimental photoionization and photodetachment spectra. We find that in anions, a plane wave treatment of the photoelectron provides a good description of photodetachment spectra. For photoionization of neutral atoms or molecules with one heavy atom, the photoelectron wave function must be treated as a Coulomb wave to account for the interaction of the photoelectron with the +1 charge of the ionized core. For larger molecules, the best agreement with experiment is often achieved by using a Coulomb wave with a partial (effective) charge smaller than unity. This likely derives from the fact that the effective charge at the centroid of the Dyson orbital, which serves as the origin of the spherical wave expansion, is smaller than the total charge of a polyatomic cation. The results suggest that accurate molecular photoionization cross sections can be computed with a modified central potential model that accounts for the nonspherical charge distribution of the core by adjusting the charge in the center of the expansion. PMID:26509428

  2. Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule.

    Science.gov (United States)

    Cloët, Ian C; Bentz, Wolfgang; Thomas, Anthony W

    2016-01-22

    In light of the forthcoming high precision quasielastic electron scattering data from Jefferson Lab, it is timely for the various approaches to nuclear structure to make robust predictions for the associated response functions. With this in mind, we focus here on the longitudinal response function and the corresponding Coulomb sum rule for isospin-symmetric nuclear matter at various baryon densities. Using a quantum field-theoretic quark-level approach which preserves the symmetries of quantum chromodynamics, as well as exhibiting dynamical chiral symmetry breaking and quark confinement, we find a dramatic quenching of the Coulomb sum rule for momentum transfers |q|≳0.5  GeV. The main driver of this effect lies in changes to the proton Dirac form factor induced by the nuclear medium. Such a dramatic quenching of the Coulomb sum rule was not seen in a recent quantum Monte Carlo calculation for carbon, suggesting that the Jefferson Lab data may well shed new light on the explicit role of QCD in nuclei. PMID:26849589

  3. A description of two methods for calculation of low frequency wind turbine noise, including applications for the Swedish prototype Wind Energy Conversion System (WECS) Maglarp

    Science.gov (United States)

    Meijer, S.; Lindblad, I.

    1983-12-01

    Computer programs to calculate the noise due to the passage of wind turbine blades through the wake of the tower of a downwind turbine, and to calculate the noise due to the steady loading of the blades (Gutin noise) are described. Results obtained from the programs are given with results from a program that calculates the noise from the unsteady loads due to atmospheric turbulence.

  4. Coulomb interactions in particle beams

    International Nuclear Information System (INIS)

    This thesis presents a theoretical description of the Coulomb interaction between identical charged particles (electrons or ions) in focussed beam. The charge-density effects as well as the various statistical interaction effects, known as the Boersch effect and the 'trajectory displacement effect', are treated. An introductory literature survey is presented from which the large differences in theoretical approach appear. Subsequently the methods are investigated which are used in studies of comparable problems in plasma physics and stellar dynamics. These turn out to be applicable to particle beams only for certain extreme conditions. The approach finally chosen in this study is twofold. On the one hand use is made of a semi-analytical model in which the statistical and dynamical aspects of the N-particle problem are reduced to two-particle problem. This model results in a number of explicit equations in the experimental parameters, with ties of the beam can be determined directly. On the other hand use has been made of a purely numerical Monte Carlo model in which the kinematical equations of an ensemble interacting particles with 'at random' chosen starting conditions are solved exactly. This model does not lead to general expressions, but yields a specific numerical prediction for each simulated experimental situation. The results of both models appear to agree well mutually. This yields a consistent theory which complements the existing knowledge of particle optics and which allow the description of systems in which the interaction between particles can not be neglected. The predictions of this theory are qualitatively and quantitatively compared with those from some other models, recently reported in literature. (author). 256 refs.; 114 figs.; 1180 schemes; 5 tabs

  5. 16O Coulomb decomposition project '93

    International Nuclear Information System (INIS)

    The adaptability of magnetic analyzers in Japan to this research project was compared and investigated, and the Coulomb decomposition process and the experimental conditions for 16O were examined. By the measurement of the delayed-α spectrum in 16N decay, a new restriction was set to the E1 reaction rate of 12C(α, γ)16O reaction. Hereafter, the research on the E2 reaction rate is urgently needed. There is large expectation for the Coulomb decomposition reaction of 16O as the probe especially sensitive to the E2 reaction rate of the important reaction for celestial body physics. At the meeting held on July 30, the RIKEN SMART spectrometer (F2) was judged as optimal, and its merits are explained. Also a demerit is pointed out. The ion optic parameters of the SMART F2 are shown. In the meeting held on December 17, investigation was carried out on α-12C coincidence count rate and projectile fragmentation background, Coulomb decomposition process and focal plane detector. The reaction cross section of Coulomb E2 excitation was evaluated by Monte Carlo method. As to the possibility of applying Coulomb decomposition process under the circumstance that nuclear force and Coulomb force compete, the new direction was indicated. The experimental plan is shown. (K.I.)

  6. Coulomb Sturmians as a basis for molecular calculations

    DEFF Research Database (Denmark)

    Avery, John Scales; Avery, James Emil

    2012-01-01

    Almost all modern quantum chemistry programs use Gaussian basis sets even though Gaussians cannot accurately represent the cusp at atomic nuclei, nor can they represent the slow decay of the wave function at large distances. The reason that Gaussians dominate quantum chemistry today is the great...

  7. Low-energy Coulomb excitation of neutron-rich zinc isotopes

    International Nuclear Information System (INIS)

    At the radioactive ion beam facility REX-ISOLDE, neutron-rich zinc isotopes were investigated using low-energy Coulomb excitation. These experiments have resulted in B(E2,21+→01+) values in 74-80Zn, B(E2,41+→21+) values in 74,76Zn and the determination of the energy of the first excited 21+ states in 78,80Zn. The zinc isotopes were produced by high-energy proton- (A=74,76,80) and neutron- (A=78) induced fission of 238U, combined with selective laser ionization and mass separation. The isobaric beam was postaccelerated by the REX linear accelerator and Coulomb excitation was induced on a thin secondary target, which was surrounded by the MINIBALL germanium detector array. In this work, it is shown how the selective laser ionization can be used to deal with the considerable isobaric beam contamination and how a reliable normalization of the experiment can be achieved. The results for zinc isotopes and the N=50 isotones are compared to collective model predictions and state-of-the-art large-scale shell-model calculations, including a recent empirical residual interaction constructed to describe the present experimental data up to 2004 in this region of the nuclear chart

  8. Theory of intervalley Coulomb interactions in monolayer transition-metal dichalcogenides

    Science.gov (United States)

    Dery, Hanan

    2016-08-01

    Exciton optical transitions in transition-metal dichalcogenides offer unique opportunities to study rich many-body physics. Recent experiments in monolayer WSe2 and WS2 have shown that, while the low-temperature photoluminescence from neutral excitons and three-body complexes is suppressed in the presence of elevated electron densities or strong photoexcitation, new dominant peaks emerge in the low-energy side of the spectrum. I present a theory that elucidates the nature of these optical transitions showing the role of the intervalley Coulomb interaction. After deriving a compact dynamical form for the Coulomb potential, I calculate the self-energy of electrons due to their interaction with this potential. For electrons in the upper valleys of the spin-split conduction band, the self-energy includes a moderate redshift due to exchange and, most importantly, a correlation-induced virtual state in the band gap. The latter sheds light on the origin of the luminescence in monolayer WSe2 and WS2 in the presence of pronounced many-body interactions.

  9. Femtosecond Studies Of Coulomb Explosion Utilizing Covariance Mapping

    CERN Document Server

    Card, D A

    2000-01-01

    The studies presented herein elucidate details of the Coulomb explosion event initiated through the interaction of molecular clusters with an intense femtosecond laser beam (≥1 PW/cm2). Clusters studied include ammonia, titanium-hydrocarbon, pyridine, and 7-azaindole. Covariance analysis is presented as a general technique to study the dynamical processes in clusters and to discern whether the fragmentation channels are competitive. Positive covariance determinations identify concerted processes such as the concomitant explosion of protonated cluster ions of asymmetrical size. Anti- covariance mapping is exploited to distinguish competitive reaction channels such as the production of highly charged nitrogen atoms formed at the expense of the protonated members of a cluster ion ensemble. This technique is exemplified in each cluster system studied. Kinetic energy analyses, from experiment and simulation, are presented to fully understand the Coulomb explosion event. A cutoff study strongly suggests that...

  10. Observation of multistep Coulomb excitation during ion-atom collisions

    International Nuclear Information System (INIS)

    Well below the Coulomb barrier energies two colliding nuclei may share the energy via electromagnetic interactions and it can lead to excite the nuclear states of one or both the participating nuclei. This long range Coulombic interaction leading to nuclear excitation is called Coulomb excitation. In the present work, we have studied heavy ion induced Coulomb excitation process in 12C nuclei at the sub-Coulomb barrier energies using x-ray spectroscopy technique in combination with the nuclear techniques.

  11. Dark excitons due to direct Coulomb interactions in silicon quantum dots

    International Nuclear Information System (INIS)

    Electron-hole exchange interactions can lead to spin-forbidden ''dark'' excitons in direct-gap quantum dots. Here, we explore an alternative mechanism for creating optically forbidden excitons. In a large spherical quantum dot made of a diamond-structure semiconductor, the symmetry of the valence band maximum (VBM) is t2. The symmetry of the conduction band minimum (CBM) in direct-gap material is a1, but for indirect-gap systems the symmetry could be (depending on size) a1, e, or t2. In the latter cases, the resulting manifold of excitonic states contains several symmetries derived from the symmetries of the VBM and CBM (e.g., t2xt2=A1+E+T1+T2 or t2xe=T1+T2). Only the T2 exciton is optically active or ''bright,'' while the others A1, E, and T1 are ''dark.'' The question is which is lower in energy, the dark or bright. Using pseudopotential calculations of the single-particle states of Si quantum dots and a direct evaluation of the screened electron-hole Coulomb interaction, we find that, when the CBM symmetry is t2, the direct electron-hole Coulomb interaction lowers the energy of the dark excitons relative to the bright T2 exciton. Thus, the lowest energy exciton is forbidden, even without an electron-hole exchange interaction. We find that our dark-bright excitonic splitting agrees well with experimental data of Calcott et al., Kovalev et al., and Brongersma et al. Our excitonic transition energies agree well with the recent experiment of Wolkin et al. In addition, and contradicting simplified models, we find that Coulomb correlations are more important for small dots than for intermediate sized ones. We describe the full excitonic spectrum of Si quantum dots by using a many-body expansion that includes both Coulomb and exchange electron hole terms. We present the predicted excitonic spectra. (c) 2000 The American Physical Society

  12. Yang-Mills theory in Coulomb gauge; Yang-Mills-theorie in Coulombeichung

    Energy Technology Data Exchange (ETDEWEB)

    Feuchter, C.

    2006-07-01

    In this thesis we study the Yang-Mills vacuum structure by using the functional Schroedinger picture in Coulomb gauge. In particular we discuss the scenario of colour confinement, which was originally formulated by Gribov. After a short introduction, we recall some basic aspects of Yang-Mills theories, its canonical quantization in the Weyl gauge and the functional Schroedinger picture. We then consider the minimal Coulomb gauge and the Gribov problem of the gauge theory. The gauge fixing of the Coulomb gauge is done by using the Faddeev-Popov method, which enables the resolution of the Gauss law - the constraint on physical states. In the third chapter, we variationally solve the stationary Yang-Mills Schroedinger equation in Coulomb gauge for the vacuum state. Therefor we use a vacuum wave functional, which is strongly peaked at the Gribov horizon. The vacuum energy functional is calculated and minimized resulting in a set of coupled Schwinger-Dyson equations for the gluon energy, the ghost and Coulomb form factors and the curvature in gauge orbit space. Using the angular approximation these integral equations have been solved analytically in both the infrared and the ultraviolet regime. The asymptotic analytic solutions in the infrared and ultraviolet regime are reasonably well reproduced by the full numerical solutions of the coupled Schwinger-Dyson equations. In the fourth chapter, we investigate the dependence of the Yang-Mills wave functional in Coulomb gauge on the Faddeev-Popov determinant. (orig.)

  13. Resonant and nonresonant Coulomb break up of 6Li

    International Nuclear Information System (INIS)

    The resonant and nonresonant cross section for break up of 6Li in the Coulomb field of a heavy nucleus is theoretically studied on the basis of a DWBA approach and analysed in view of a possible experimental access to electromagnetic transition matrix elements between the ground state of the projectile and α+d continuum states at small relative energies. The calculation explicitly uses some simplifications appearing in the particular case of quadrupole transitions which dominate the considered case. Various sensitivities of the cross sections are discussed. (orig.)

  14. Coulomb screening in low-energy nuclear reactions

    International Nuclear Information System (INIS)

    Coulomb screening effects are studied in very low-energy nuclear reactions. The two-potential formalism is shown to be a convenient method for the separation of long-range (molecular) and short-range (nuclear) dynamics. As specific applications, electron screening effects and muon catalysis in nuclear reactions are investigated. In the case of electron screening in very low-energy nuclear reactions a method is elaborated for calculation of the enhancement of the astrophysical factor. For muon catalyzed fusion reactions the sudden approximation is shown to be valid even if the reaction is dominated by a long lived nuclear resonance. (author) 37 refs

  15. On low energy scattering theory with Coulomb potentials

    International Nuclear Information System (INIS)

    The scattering length is a very useful characteristic of the scattering phenomena. But in the presence of a combined potential (e.g. in nuclear physics, when Coulomb, the polarization and the strong potentials are to be added), the analytical definition of the scattering length in not unambigous and strictly defined. This problem is discussed in detail, the various alternatives are examined and compared. A practical suggestion is given for the proper choice of the definition and for the calculation of scattering length. Numerical solutions of the Schroedinger equation are compared with the results of different definitions. Some questions of application to nuclear physics are discussed. (D.Gy.)

  16. The simplest model for non-congruent fluid-fluid phase transition in Coulomb system

    Science.gov (United States)

    Stroev, N. E.; Iosilevskiy, I. L.

    2015-11-01

    The simplest model for non-congruent phase transition of gas-liquid type was developed in frames of modified model with no associations of a binary ionic mixture (BIM) on a homogeneous compressible ideal background (or non-ideal) electron gas /BIM(˜)/. The analytical approximation for equation of state equation of state of Potekhin and Chabrier of fully ionized electron-ionic plasma was used for description of the ion-ion correlations (Coulomb non-ideality) in combination with “linear mixture” (LM) approximation. Phase equilibrium for the charged species was calculated according to the Gibbs-Guggenheim conditions. The presently considered BIM(˜) model allows to calculate full set of parameters for phase boundaries of non-congruent variant of phase equilibrium and to study all features for this non-congruent phase transition realization in Coulomb system in comparison with the simpler (standard) forced-congruent evaporation mode. In particular, in BIM(˜) there were reproduced two-dimensional remarkable (“banana-like”) structure of two-phase region P — T diagram and the characteristic non-monotonic shape of caloric phase enthalpy-temperature diagram, similar to the non-congruent evaporation of reactive plasma products in high-temperature heating with the uranium-oxygen system. The parameters of critical points (CP) line were calculated on the entire range of proportions of ions 0 < X < 1, including two reference values, when CP coincides with a point of extreme temperature and extreme pressure, XT and Xp. Finally, it is clearly demonstrated the low-temperature property of non-congruent gas-liquid transition — “distillation”, which is weak in chemically reactive plasmas.

  17. Gaussian and finite-element Coulomb method for the fast evaluation of Coulomb integrals

    Science.gov (United States)

    Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko

    2007-04-01

    The authors propose a new linear-scaling method for the fast evaluation of Coulomb integrals with Gaussian basis functions called the Gaussian and finite-element Coulomb (GFC) method. In this method, the Coulomb potential is expanded in a basis of mixed Gaussian and finite-element auxiliary functions that express the core and smooth Coulomb potentials, respectively. Coulomb integrals can be evaluated by three-center one-electron overlap integrals among two Gaussian basis functions and one mixed auxiliary function. Thus, the computational cost and scaling for large molecules are drastically reduced. Several applications to molecular systems show that the GFC method is more efficient than the analytical integration approach that requires four-center two-electron repulsion integrals. The GFC method realizes a near linear scaling for both one-dimensional alanine α-helix chains and three-dimensional diamond pieces.

  18. Level lifetimes and quadrupole moments from Coulomb excitation in the Ba chain

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Christopher; Guastalla, Giulia; Leske, Joerg; Moeller, Thomas; Pietralla, Norbert; Stahl, Christian; Stegmann, Robert; Wiederhold, Johannes [Technische Univ. Darmstadt (Germany). Inst. fuer Kernphysik; Seweryniak, Darek; Zhu, Shaofei [Argonne National Lab., Chicago, IL (United States); Collaboration: IS411-Collaboration

    2013-07-01

    The chain of Barium isotopes enables us to study experimentally the evolution of nuclear quadrupole collectivity from the shell closure at N=82 towards neutron-deficient or neutron-rich deformed nuclei. The TU Darmstadt group has investigated several nuclei from stable {sup 130,132}Ba up to radioactive {sup 140,142}Ba with the projectile-Coulomb excitation technique including the use of the Doppler-shift attenuation method (DSAM). Lifetimes of quadrupole-collective states of {sup 132}Ba and {sup 140}Ba were obtained for the first time as well as the static electric quadrupole moments Q(2{sup +}{sub 1}) for {sup 130,132}Ba and {sup 140,142}Ba. The results are compared to Monte Carlo shell model and Beyond-Mean-Field calculations.

  19. Effects of large-angle Coulomb collisions on inertial confinement fusion plasmas.

    Science.gov (United States)

    Turrell, A E; Sherlock, M; Rose, S J

    2014-06-20

    Large-angle Coulomb collisions affect the rates of energy and momentum exchange in a plasma, and it is expected that their effects will be important in many plasmas of current research interest, including in inertial confinement fusion. Their inclusion is a long-standing problem, and the first fully self-consistent method for calculating their effects is presented. This method is applied to "burn" in the hot fuel in inertial confinement fusion capsules and finds that the yield increases due to an increase in the rate of temperature equilibration between electrons and ions which is not predicted by small-angle collision theories. The equilibration rate increases are 50%-100% for number densities of 10(30)  m(-3) and temperatures around 1 keV. PMID:24996093

  20. Coulomb collisional effects on high energy particles in the presence of driftwave turbulence

    CERN Document Server

    Huang, B; Cheng, C Z

    2013-01-01

    High energy particles' behavior including fusion born alpha particles in an ITER like tokamak in the presence of background driftwave turbulence is investigated by an orbit following calculation. The background turbulence is given by the toroidal driftwave eigenmode combined with a random number generator. The transport level is reduced as the particle energy increase; the widths of the guiding center islands produced by the passing particles are inverse proportional to the square root of parallel velocities. On the other hand, the trapped particles are sensitive to $E \\times B$ drift at the banana tips whose radial displacement is larger for lower energy particles. Coulomb collisional effects are incorporated which modifies the transport process of the trapped high energy particles whose radial excursion resides in limited radial domains without collisions.

  1. Coulomb fission of a charged dust cloud in an afterglow plasma

    Science.gov (United States)

    Merlino, Robert; Meyer, John

    2015-11-01

    A dust cloud of 1 micron diameter silica microspheres was confined in a DC glow discharge dusty plasma in argon at a pressure of 100 mTorr (13 Pa). Laser sheet illumination and a fast video camera (2000 frames/s) was used to record the dynamics of this cloud following the switch-off of the plasma and confining forces. Due to the rapid decay of the plasma, and the substantial residual charge on the particles in the plasma afterglow, the cloud evolved under the mutual Coulomb repulsion forces. A variety of dynamic evolutions were observed with different clouds and under different conditions including, Coulomb explosion and expansion. In one case, the cloud underwent a Coulomb fission process, fragmenting into two clouds. Observations and analysis of this Coulomb fission event will be presented. Work supported by DOE.

  2. A graphical user interface (GUI) toolkit for the calculation of three-dimensional (3D) multi-phase biological effective dose (BED) distributions including statistical analyses.

    Science.gov (United States)

    Kauweloa, Kevin I; Gutierrez, Alonso N; Stathakis, Sotirios; Papanikolaou, Niko; Mavroidis, Panayiotis

    2016-07-01

    A toolkit has been developed for calculating the 3-dimensional biological effective dose (BED) distributions in multi-phase, external beam radiotherapy treatments such as those applied in liver stereotactic body radiation therapy (SBRT) and in multi-prescription treatments. This toolkit also provides a wide range of statistical results related to dose and BED distributions. MATLAB 2010a, version 7.10 was used to create this GUI toolkit. The input data consist of the dose distribution matrices, organ contour coordinates, and treatment planning parameters from the treatment planning system (TPS). The toolkit has the capability of calculating the multi-phase BED distributions using different formulas (denoted as true and approximate). Following the calculations of the BED distributions, the dose and BED distributions can be viewed in different projections (e.g. coronal, sagittal and transverse). The different elements of this toolkit are presented and the important steps for the execution of its calculations are illustrated. The toolkit is applied on brain, head & neck and prostate cancer patients, who received primary and boost phases in order to demonstrate its capability in calculating BED distributions, as well as measuring the inaccuracy and imprecision of the approximate BED distributions. Finally, the clinical situations in which the use of the present toolkit would have a significant clinical impact are indicated. PMID:27265044

  3. Coulomb-dominated low-energy deuteron stripping

    International Nuclear Information System (INIS)

    Analysis of a three-body model shows that Coulomb polarization of the deuteron has very little influence on the branching ratio A(d,p)/A(d,n) for transfer reactions on target nucleus A at very low deuteron energies (the Oppenheimer-Phillips effect). We see that polarization effects in transfer reactions are not related to the long range of the Coulomb field, but are caused by the more intense fields near the target nucleus. However, even in that region the induced dipole moment is limited by the deuteron binding, and it is small for low Z targets. We see in addition that the transfer amplitudes tend to be insensitive to any polarization admixtures in the entrance channel. On the other hand, the branching ratio can be affected by the Coulomb barrier for the bound final-state wave function of the proton, especially for very weakly bound final states. Brief remarks about the relation of stripping theory to special properties of the d+d system are included

  4. Coulomb displacement energies in nuclei

    International Nuclear Information System (INIS)

    In the present work the positions of the isobaric analog resonances (IAR) are calculated using the HF-TDA theory with a complete proton particle-neutron hole basis. The important feature of this approach is the fact that the HF potential and the particle-hole interaction used in the TDA are derived from the same two-body interactions. In this theroy all the higher order effects are taken into account in one consistent framework. The calculations are performed for several N > Z, closed shell nuclei. For these nuclei good agreement between the experimental and theoretical excitation energies of the IAR is obtained. (orig.)

  5. Wannier function approach to realistic Coulomb interactions in layered materials and heterostructures

    Science.gov (United States)

    Rösner, M.; Şaşıoǧlu, E.; Friedrich, C.; Blügel, S.; Wehling, T. O.

    2015-08-01

    We introduce an approach to derive realistic Coulomb interaction terms in freestanding layered materials and vertical heterostructures from ab initio modeling of the corresponding bulk materials. To this end, we establish a combination of calculations within the framework of the constrained random-phase approximation, Wannier function representation of Coulomb matrix elements within some low-energy Hilbert space, and continuum medium electrostatics, which we call Wannier function continuum electrostatics (WFCE). For monolayer and bilayer graphene we reproduce full ab initio calculations of the Coulomb matrix elements within an accuracy of 0.3 eV or better. We show that realistic Coulomb interactions in bilayer graphene can be manipulated on the eV scale by different dielectric and metallic environments. A comparison to electronic phase diagrams derived in M. M. Scherer et al. [Phys. Rev. B 85, 235408 (2012), 10.1103/PhysRevB.85.235408] suggests that the electronic ground state of bilayer graphene is a layered antiferromagnet and remains surprisingly unaffected by these strong changes in the Coulomb interaction.

  6. Orbital Ordering Induced by Direct Coulomb Repulsion

    Institute of Scientific and Technical Information of China (English)

    HUANG Yuan-Yie; ZHANG Yu-Heng

    2011-01-01

    We consider the covalence characters of the 3d electron with the eg orbital freedoms and put forward a new mechanism of the orbital ordering (OO) based on the direct coulomb repulsion in this article. The results show that the orbital-orbital interaction (OO-I) between the adjacent ions in 180-degree configuration is dominated by the superexchange energy accompanied by a weak orbital-spin coupling, and the OO-I in 90-degree configuration is monitored by the oxygen on-site coulomb repulsion. The ferro-OO is the stable ground state for the one-dimensional chain in the case of the 90-degree configuration.

  7. Coulomb interaction in few-nucleon systems

    International Nuclear Information System (INIS)

    Mathematical aspects of scattering quantum theory are considered. A brief review of methods proposed for solution of the following problems is presented: a) description of properties of resolvant nucleus for the operator of energy of three charged particles system, 2) definition of total system of Coulomb wave functions, 3) definition of unitary Coulomb scattering operator, 4) study of singularity of its nucleus, 5) establishing of relation between stationary and non stationary formulations of the scattering theory. The solution of these problems is obtained by means of a new form of Faddeev integral equations. The equations are formulated and studied in configuration space

  8. Testing of Coulomb-Volkov functions

    International Nuclear Information System (INIS)

    A time-dependent generalization of the Siegert theorem is applied to test the accuracy of the Coulomb-Volkov functions (CVFs) widely used for the description of electron motion in a laser field combined with the Coulomb field of the atomic core. Free-free transitions in the case of arbitrary elliptic polarization of the electromagnetic field are investigated. It is shown that the ratio between the strength of the light wave electric field and its frequency (in atomic units) has crucial importance for estimation of the CVF accuracy. (author)

  9. Efficient evaluation of the Coulomb force in the Gaussian and finite-element Coulomb method

    Science.gov (United States)

    Kurashige, Yuki; Nakajima, Takahito; Sato, Takeshi; Hirao, Kimihiko

    2010-06-01

    We propose an efficient method for evaluating the Coulomb force in the Gaussian and finite-element Coulomb (GFC) method, which is a linear-scaling approach for evaluating the Coulomb matrix and energy in large molecular systems. The efficient evaluation of the analytical gradient in the GFC is not straightforward as well as the evaluation of the energy because the SCF procedure with the Coulomb matrix does not give a variational solution for the Coulomb energy. Thus, an efficient approximate method is alternatively proposed, in which the Coulomb potential is expanded in the Gaussian and finite-element auxiliary functions as done in the GFC. To minimize the error in the gradient not just in the energy, the derived functions of the original auxiliary functions of the GFC are used additionally for the evaluation of the Coulomb gradient. In fact, the use of the derived functions significantly improves the accuracy of this approach. Although these additional auxiliary functions enlarge the size of the discretized Poisson equation and thereby increase the computational cost, it maintains the near linear scaling as the GFC and does not affects the overall efficiency of the GFC approach.

  10. Relativistic many-body calculations of energies for n=3 states in aluminiumlike ions

    International Nuclear Information System (INIS)

    Energies of the 148 (3l3l'3l'') states for aluminiumlike ions with Z =14-100 are evaluated to second order in relativistic many-body perturbation theory. Second-order Coulomb and Breit-Coulomb interactions are included. Corrections are made to lowest order for the frequency-dependent Breit interaction and for the Lamb shift. A detailed discussion of the various contributions to the energy levels is given for aluminiumlike germanium (Z=32). Comparisons of the calculated energy levels with available experimental data are made for the entire sequence. (author)

  11. Relativistic many-body calculations of energies for n=3 states in aluminiumlike ions

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, U.I.; Namba, C. [National Inst. for Fusion Science, Toki, Gifu (Japan); Johnson, W.R.; Safronova, M.S. [Department of Physics, Univ. of Notre Dame, Notre Dame, IN (United States)

    2001-01-01

    Energies of the 148 (3l3l'3l'') states for aluminiumlike ions with Z =14-100 are evaluated to second order in relativistic many-body perturbation theory. Second-order Coulomb and Breit-Coulomb interactions are included. Corrections are made to lowest order for the frequency-dependent Breit interaction and for the Lamb shift. A detailed discussion of the various contributions to the energy levels is given for aluminiumlike germanium (Z=32). Comparisons of the calculated energy levels with available experimental data are made for the entire sequence. (author)

  12. Analysis of thrust augmentation of turbojet engines by water injection at compressor inlet including charts for calculating compression processes with water injection

    Science.gov (United States)

    Wilcox, E Clinton; Trout, Arthur M

    1951-01-01

    A psychrometric chart having total pressure (sum of partial pressures of air and water vapor) as a variable, a Mollier diagram for air saturated with water vapor, and charts showing the thermodynamic properties of various air-water vapor and exhaust gas-water vapor mixtures are presented as aids in calculating the thrust augmentation of a turbojet engine resulting from the injection of water at the compressor inlet. Curves are presented that show the theoretical performance of the augmentation method for various amounts of water injected and the effects of varying flight Mach number, altitude, ambient-air temperature, ambient relative humidity, compressor pressure ratio, and inlet-diffuser efficiency. Numerical examples, illustrating the use of the psychrometric chart and the Mollier diagram in calculating both compressor-inlet and compressor-outlet conditions when water is injected at the compressor inlet, are presented.

  13. Module of System Galactica with Coulomb's Interaction

    OpenAIRE

    Smulsky, Joseph J

    2014-01-01

    The system Galactica of free access is supplemented module for the Coulomb interaction. It is based on a high-precision method for solving differential equations of motion of N charged particles. The paper presents all the theoretical and practical issues required to use this module of system Galactica so that even the beginning researcher could study the motion of particles, atoms and molecules.

  14. Coulomb drag in coherent mesoscopic systems

    DEFF Research Database (Denmark)

    Mortensen, Niels Asger; Flensberg, Karsten; Jauho, Antti-Pekka

    2001-01-01

    We present a theory for Coulomb drag between two mesoscopic systems. Our formalism expresses the drag in terms of scattering matrices and wave functions, and its range of validity covers both ballistic and disordered systems. The consequences can be worked out either by analytic means, such as the...

  15. BRST invariance in Coulomb gauge QCD

    CERN Document Server

    Andrasi, A

    2015-01-01

    In the Coulomb gauge, the Hamiltonian of QCD contains terms of order h^2, identified by Christ and Lee, which are non-local but instantaneous. The question is addressed how these terms fit in with BRST invariance. Our discussion is confined to the simplest, O(g^4), example.

  16. BRST invariance in Coulomb gauge QCD

    Science.gov (United States)

    Andraši, A.; Taylor, J. C.

    2015-12-01

    In the Coulomb gauge, the Hamiltonian of QCD contains terms of order ħ2, identified by Christ and Lee, which are non-local but instantaneous. The question is addressed how do these terms fit in with BRST invariance. Our discussion is confined to the simplest, O(g4) , example.

  17. Dynamical features of Coulomb-fission

    International Nuclear Information System (INIS)

    Fission following quasielastic scattering was investigated in the reactions 208Pb -> 238U below the Coulomb Barrier and 7.5 MeV/u 238U -> 238U at scattering angles forward of the grazing angle (870). A kinematically complete analysis of 3-body coincidences was carried out measuring position and time-of-flight of the scattered projectile-like particle and 2 fission fragments in large parallel plate detectors. In the reaction 208Pb -> 238U, measured at backward angles, the slope of the differential cross section at 5.4 MeV/u is in qualitative agreement with the theoretical expectation for Coulomb-fission. The angular distribution of the fission fragments, measured with respect to the semisector axis (apex line towards the projectile), is close to 1/sinTHETA and does not show any of the significant structures predicted by several theories. The anisotropy is smaller in all other coordinate systems investigated. The fission probability in the reaction 238U -> 238U, measured down to 5x10-4 at THETAsub(cm)=540 (corresponding to 75% Esub(cb) at the distance of closest approach) as well as the low excitation energy 0 as expected for Coulomb-fission. The absence of a detectable final state Coulomb interaction yields a lower limit of 1-2x10-20s for the lifetime of the fissioning nucleus. (orig./HSI)

  18. Frictional Coulomb drag in strong magnetic fields

    DEFF Research Database (Denmark)

    Bønsager, Martin Christian; Flensberg, Karsten; Hu, Ben Yu-Kuang;

    1997-01-01

    A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21) is...

  19. Coulomb drag in coherent mesoscopic systems

    DEFF Research Database (Denmark)

    Mortensen, Asger; Flensberg, Karsten; Jauho, Antti-Pekka

    2001-01-01

    random matrix theory, or by numerical simulations. We show that Coulomb drag is sensitive to localized states. which usual transport measurements do not probe. For chaotic 2D systems we find a vanishing average drag, with a nonzero variance. Disordered 1D wires show a finite drag, with a large variance...

  20. Electronically Excited States of Vitamin B12: Benchmark Calculations Including Time-Dependent Density Functional Theory and Correlated Ab Initio Methods

    CERN Document Server

    Kornobis, Karina; Wong, Bryan M; Lodowski, Piotr; Jaworska, Maria; Andruniów, Tadeusz; Rudd, Kenneth; Kozlowski, Pawel M; 10.1021/jp110914y

    2011-01-01

    Time-dependent density functional theory (TD-DFT) and correlated ab initio methods have been applied to the electronically excited states of vitamin B12 (cyanocobalamin or CNCbl). Different experimental techniques have been used to probe the excited states of CNCbl, revealing many issues that remain poorly understood from an electronic structure point of view. Due to its efficient scaling with size, TD-DFT emerges as one of the most practical tools that can be used to predict the electronic properties of these fairly complex molecules. However, the description of excited states is strongly dependent on the type of functional used in the calculations. In the present contribution, the choice of a proper functional for vitamin B12 was evaluated in terms of its agreement with both experimental results and correlated ab initio calculations. Three different functionals, i.e. B3LYP, BP86, and LC-BLYP, were tested. In addition, the effect of relative contributions of DFT and HF to the exchange-correlation functional ...

  1. On effect of Coulomb correlation energy on characteristics of atomic nuclei

    International Nuclear Information System (INIS)

    Coulomb correlation energy (CCE) of semi-infinite nuclear matter is studied. The CCE contribution to the surface tension is calculated. Mass differences of mirror nuclei in the range A=16 and A=40 are evaluated taking CCE into account. The results agree well with the experiment

  2. Coulomb Correction to the Screening Angle of the Moliere Multiple Scattering Theory

    CERN Document Server

    Kuraev, E A; Tarasov, A V

    2012-01-01

    Coulomb correction to the screening angular parameter of the Moliere multiple scattering theory is found. Numerical calculations are presented in the range of nuclear charge from Z=4 to Z=82. Comparison with the approximate Moliere result for the screening angle reveals up to 30% deviation from it for sufficiently heavy elements of the target material.

  3. Coulomb correction to the screening angle of the Moliere multiple scattering theory

    International Nuclear Information System (INIS)

    Coulomb correction to the screening angular parameter of the Moliere multiple scattering theory is found. Numerical calculations are presented in the range of nuclear charge 4 ≤ Z ≤ 82. Comparison with the Moliere result for the screening angle reveals up to 30% deviation from it for sufficiently heavy elements of the target material

  4. Covariant formulation of Coulomb excitation in heavy ion collisions at ultra relativistic energies

    International Nuclear Information System (INIS)

    Derivation of Coulomb excitation cross sections at relativistic energies is presented for the case where both projectile and target are considered as extended objects. Cross sections for projectile and/or target excitations are calculated as a function of bombarding energy in the context of a covariant theory. Several systems are analyzed and compared with available data. (author)

  5. Ca(AlH4)2, CaAlH5, and CaH2+6LiBH4: Calculated dehydrogenation enthalpy, including zero point energy, and the structure of the phonon spectra

    NARCIS (Netherlands)

    Marashdeh, A.; Frankcombe, T.J.

    2008-01-01

    The dehydrogenation enthalpies of Ca(AlH4)2, CaAlH5, and CaH2+6LiBH4 have been calculated using density functional theory calculations at the generalized gradient approximation level. Harmonic phonon zero point energy (ZPE) corrections have been included using Parlinski’s direct method. The dehydrog

  6. Stability of the three-body Coulomb systems with J=1 in the oscillator representation

    International Nuclear Information System (INIS)

    The oscillator representation is applied to calculate the energy spectrum of three-body Coulomb systems with J total angular momentum. For the three-body Coulomb systems with J=1 and arbitrary masses the region of stability is determined. For the systems (A+A-e-), (pe-C+), (pB-e-) and (D+e-e+), the values for the critical masses of A-, B-, C- and D-particles are obtained: mA=2.22me, mB=1.49me, mC=2.11me and mD=4.15me. 18 refs., 1 fig., 3 tabs

  7. Computational Analysis of Intermolecular Coulombic Decay Effects in DNA nucleotide Photoionization

    Science.gov (United States)

    Vargas, E. L.; Robertson, J.; Andrianarijaona, V. M.

    2016-03-01

    Intermolecular Coulombic Decay (ICD) is the process of how electrons return to their original state after excitation and how this affects their immediate environment. In a previous research presentationwe had considered the hypothetical applications of Intermolecular Coulombic Decay on the adhesiveness of coding proteins within DNA molecules. This presentation is a continuation of the previous in that the results of our DFT-based computational calculations of the ionization potentials of nucleotides and their excitation energies will be presented, as well as how they influence their surroundings. Author would like to acknowledge the PUC Student Senate for financial assistance.

  8. A shortcut through the Coulomb gas method for spectral linear statistics on random matrices

    International Nuclear Information System (INIS)

    In the last decade, spectral linear statistics on large dimensional random matrices have attracted significant attention. Within the physics community, a privileged role has been played by invariant matrix ensembles for which a two-dimensional Coulomb gas analogy is available. We present a critical revision of the Coulomb gas method in random matrix theory (RMT) borrowing language and tools from large deviations theory. This allows us to formalize an equivalent, but more effective and quicker route toward RMT free energy calculations. Moreover, we argue that this more modern viewpoint is likely to shed further light on the interesting issues of weak phase transitions and evaporation phenomena recently observed in RMT. (paper)

  9. Translationally Invariant Calculations of Form Factors, Densities and Momentum Distributions for Finite Nuclei with Short–Range Correlations Included: A Fresh Look

    International Nuclear Information System (INIS)

    The approach proposed in the 70s (Dementiji et al. in Sov J Nucl Phys 22:6–9, 1976), when describing the elastic and inelastic electron scattering off 4He, and elaborated in (Shebeko et al.in Eur Phys J A27:143–155, 2006) for calculations of the one-body, two-body and more complex density matrices of finite bound systems has been applied (Shebeko and Grigorov in Ukr J Phys 52:830–842, 2007; Shebeko et al. in Eur. Phys. J. A48:153–172, 2012) in studying a combined effect of the center-of-mass motion and nucleon–nucleon short-range correlations on the nucleon density and momentum distributions in light nuclei beyond the independent particle model. Unlike a common practice, suitable for infinite bound systems, these distributions are determined as expectation values of appropriate intrinsic operators that depend upon the relative coordinates and momenta (Jacobi variables) and act on the intrinsic ground–state wave functions (WFs). The latter are constructed in the so-called fixed center-of-mass approximation, starting with a mean–field Slater determinant modified by some correlator (e.g., after Jastrow or Villars). Our numerical calculations of the charge form factors (FCH (q)), densities and momentum distributions have been carried out for nuclei 4 He and 16 O choosing, respectively, the 1s and 1s−1p Slater determinants of the harmonic oscillator model as trial, nontranslationally invariant WFs. (author)

  10. Probing the quadrupole collectivity of 128Cd using Coulomb excitation

    International Nuclear Information System (INIS)

    128Cd is only two proton and two neutron holes away from the doubly magic nucleus 132Sn. The excitation energy of the first excited 2+-state decreases when approaching the neutron shell closure. This unexpected behaviour makes this nucleus interesting for investigation. So far, contradicting theoretical predictions for the B(E2,0+ → 2+) value of 128Cd exist. While shell model calculations conclude an almost spherical shape of 128Cd, beyond mean field calculations predict an already considerable quadrupole collectivity. In this contribution the experimental details of the Coulomb excitation of 128Cd at REX-ISOLDE, investigated with MINIBALL (experiment IS477), are presented. Furthermore the current status of the analysis to determine the transition strength of the ground state into the first excited 2+ state is shown.

  11. Quasiclassical Coulomb matrix elements in supersymmetric quantum mechanics

    International Nuclear Information System (INIS)

    Supersymmetric WKB (SWKB) wave functions diverging at the turning points and quantization relations up to the order h6 are derived directly from the supersymmetric partner Schroedinger equations. The resulting supersymmetric partner wave functions are used, without any Langer-type correction, for dipole radial integral calculations for bound-bound transitions in the Coulomb approximation. To our knowledge, this is the first analytical calculation of matrix elements using SWKB wave functions. The bosonic SWKB partner wave function yields the WKB radial integral formula of Pankratov and Meyer-ter-Vehn which was derived by applying the Langer correction to the centrifugal potential. The new dipole radial integral expression obtained from the fermionic SWKB partner wave function overestimates the oscillator strengths with respect to accepted values. However, we verify that in the classical limit both supersymmetric partner SWKB results converge to the same value. (author). 48 refs, 2 tabs

  12. Sensor Craft Control Using Drone Craft with Coulomb Propulsion System

    OpenAIRE

    Joe, Hyunsik

    2005-01-01

    The Coulomb propulsion system has no exhaust plume impingement problem with neighboring spacecraft and does not contaminate their sensors because it requires essentially no propellant. It is suitable to close formation control on the order of dozens of meters. The Coulomb forces are internal forces of the formation and they influence all charged spacecraft at the same time. Highly nonlinear and strongly coupled equations of motion of Coulomb formation makes creating a Coulomb control method a...

  13. The influence of the mean charge state on the Coulomb heating of fast diclusters through the Si direction

    Science.gov (United States)

    Nascimento, C. D.; Fadanelli, R. C.; Behar, M.

    2016-04-01

    In the present work, we report a theoretical and experimental study of the Coulomb heating of H2+ and C2+ in Si channel, covering an energy range from 200 keV/ion to 2200 keV/ion. The experimental values for Coulomb heating were obtained by combining the Rutherford backscattering spectrometry (RBS) and the particle induced X-ray emission (PIXE) techniques under channeling conditions. Theoretical values were obtained by performing classical trajectory Monte-Carlo (CTMC) simulations of the ion paths inside the Si channel, using Dirac-Hartree-Fock-Slater (DHFS) results for the interionic potential. As seen for the case, it is shown that the use of a DHFS potential based on the ion mean charge states in amorphous targets leads to a disagreement between the Coulomb heating values and the expected potential energies stored in the dicluster prior to the Coulomb explosion. Therefore, a numerical procedure was used in order to calculate the mean charge state values for ions traveling in Si. The use of the resulting charge states led to a linear relationship between the Coulomb heating values and the stored potential energy per ion of the diclusters. Finally, the Coulomb heating/stored potential energy ratio amounts to about 2/3, as expected from an isotropic Coulomb explosion.

  14. High-order harmonic generation spectrum of an excited one-dimensional Coulomb atom in an intense laser field

    Institute of Scientific and Technical Information of China (English)

    Zhou Zhao-Yan; Yuan Jian-Min

    2007-01-01

    Response of the wave packet of a one-dimensional Coulomb atom to an intense laser field is calculated using the symmetrized split operator fast Fourier method.The high-order harmonic generation (HHG) of the initial state separately being the ground and excited states is presented.When the hardness parameter α in the soft Coulomb potential V(x) =-1/(x2+α) is chosen to be small enough,the so-called hard Coulomb potential V(x) =-1/|x| can be obtained.It is Well knawn that the hard one-dimensional Coulomb atom has an unstable ground state with an energy eigenvalue of ~0.5 and it has no states corresponding to physical states in the true atoms,and has the first and second excited states being degenerate.The parity effects on the HHG can be seen from the first and second excited states of the hard one-dimensional Coulomb atom.The HHG spectra of the excited states from both the soft and hard Coulomb atom models are shown to have more complex structures and to be much stronger than the corresponding HHG spectrum of the ground state of the soft Coulomb model with α=2 in the same laser field.Laser-induced non-resonant one-photon emission is also observed.

  15. Development of a novel ArcCHECK{sup Trade-Mark-Sign} insert for routine quality assurance of VMAT delivery including dose calculation with inhomogeneities

    Energy Technology Data Exchange (ETDEWEB)

    Fakir, H.; Gaede, S.; Mulligan, M.; Chen, J. Z. [Department of Physics, London Regional Cancer Program, London, Ontario N6A 4L6 (Canada)

    2012-07-15

    Purpose: To design a versatile, nonhomogeneous insert for the dose verification phantom ArcCHECK{sup Trade-Mark-Sign} (Sun Nuclear Corp., FL) and to demonstrate its usefulness for the verification of dose distributions in inhomogeneous media. As an example, we demonstrate it can be used clinically for routine quality assurance of two volumetric modulated arc therapy (VMAT) systems for lung stereotactic body radiation therapy (SBRT): SmartArc{sup Registered-Sign} (Pinnacle{sup 3}, Philips Radiation Oncology Systems, Fitchburg, WI) and RapidArc{sup Registered-Sign} (Eclipse{sup Trade-Mark-Sign }, Varian Medical Systems, Palo Alto, CA). Methods: The cylindrical detector array ArcCHECK{sup Trade-Mark-Sign} has a retractable homogeneous acrylic insert. In this work, we designed and manufactured a customized heterogeneous insert with densities that simulate soft tissue, lung, bone, and air. The insert offers several possible heterogeneity configurations and multiple locations for point dose measurements. SmartArc{sup Registered-Sign} and RapidArc{sup Registered-Sign} plans for lung SBRT were generated and copied to ArcCHECK{sup Trade-Mark-Sign} for each inhomogeneity configuration. Dose delivery was done on a Varian 2100 ix linac. The evaluation of dose distributions was based on gamma analysis of the diode measurements and point doses measurements at different positions near the inhomogeneities. Results: The insert was successfully manufactured and tested with different measurements of VMAT plans. Dose distributions measured with the homogeneous insert showed gamma passing rates similar to our clinical results ({approx}99%) for both treatment-planning systems. Using nonhomogeneous inserts decreased the passing rates by up to 3.6% in the examples studied. Overall, SmartArc{sup Registered-Sign} plans showed better gamma passing rates for nonhomogeneous measurements. The discrepancy between calculated and measured point doses was increased up to 6.5% for the nonhomogeneous

  16. Ab initio MRCI + Q calculations on the low-lying excited states of the MgBr radical including spin-orbit coupling

    Science.gov (United States)

    Wu, Dong-lan; Tan, Bin; Wen, Yu-feng; Zeng, Xue-feng; Xie, An-dong; Yan, Bing

    2016-05-01

    Accurate theoretical calculations on the MgBr radical have been carried out by using the high-level relativistic multireference configuration interaction method with Davidson correction (MRCI + Q) using correlation-consistent Quintuple-ζ quality basis set. The potential energy curves (PECs) of the 14 Λ-S states of MgBr have been computed. In order to improve the PECs, the core-valence correlation, scalar relativistic effect, and spin-orbit coupling effect are taken into account in the computations. The spectroscopic constants of the bound states have been determined from the computed PECs. The results of the ground state X2Σ+ and the first excited state A2Π are in good agreement with those from the available experiments, while spectroscopic constants of the other electronic states are firstly reported. The low-lying ion-pair state B2Σ+ correlated to ion-pair dissociation limit Mg+ (2Sg) + Br- (1Sg) is characterized. The permanent dipole moments (PDMs) of Λ-S states and the R-dependent spin-orbit (SO) matrix elements are computed. The results indicate that the abrupt changes of PDMs and the SO matrix elements are attributed to the changes of the electronic configurations near the avoided crossing point. After taking the SOC effect into account, the 14 Λ-S states split into 30 Ω states, and the SOC splitting for the A2Π is calculated to be 102.58 cm- 1. The SOC effect, leading to the double-well potential of the Ω = (3)1/2 state, is found to be substantial for MgBr. In order to further illustrate the SOC effect and the avoided crossing phenomenon of the PECs, the Λ-S compositions in the Ω state wavefunctions are analyzed in detail. Finally, the transition dipole moments (TDMs) of several transitions from upper Ω states to the ground X2Σ+1/2 state and the corresponding radiative lifetimes have been studied. It is shown that the (1)3/2-X2Σ+1/2 and (2)3/2-X2Σ+1/2 are particularly important to the observed transitions A2Π-X2Σ+ and C2Π-X2Σ+. The

  17. Ca(AlH4)2, CaAlH5, and CaH2+6LiBH4: Calculated dehydrogenation enthalpy, including zero point energy, and the structure of the phonon spectra.

    Science.gov (United States)

    Marashdeh, Ali; Frankcombe, Terry J

    2008-06-21

    The dehydrogenation enthalpies of Ca(AlH(4))(2), CaAlH(5), and CaH(2)+6LiBH(4) have been calculated using density functional theory calculations at the generalized gradient approximation level. Harmonic phonon zero point energy (ZPE) corrections have been included using Parlinski's direct method. The dehydrogenation of Ca(AlH(4))(2) is exothermic, indicating a metastable hydride. Calculations for CaAlH(5) including ZPE effects indicate that it is not stable enough for a hydrogen storage system operating near ambient conditions. The destabilized combination of LiBH(4) with CaH(2) is a promising system after ZPE-corrected enthalpy calculations. The calculations confirm that including ZPE effects in the harmonic approximation for the dehydrogenation of Ca(AlH(4))(2), CaAlH(5), and CaH(2)+6LiBH(4) has a significant effect on the calculated reaction enthalpy. The contribution of ZPE to the dehydrogenation enthalpies of Ca(AlH(4))(2) and CaAlH(5) calculated by the direct method phonon analysis was compared to that calculated by the frozen-phonon method. The crystal structure of CaAlH(5) is presented in the more useful standard setting of P2(1)c symmetry and the phonon density of states of CaAlH(5), significantly different to other common complex metal hydrides, is rationalized. PMID:18570508

  18. Screened Coulomb interactions in metallic alloys. I. Universal screening in the atomic-sphere approximation

    DEFF Research Database (Denmark)

    Ruban, Andrei; Skriver, Hans Lomholt

    2002-01-01

    of the alloy composition, lattice spacing, and crystal structure. A formalism which allows a consistent treatment of the screened Coulomb interactions within the single-site mean-field approximation is outlined. We also derive the contribution of the screened Coulomb interactions to the S-(2) formalism...... the Madelung potential energy of a random alloy in the single-site, mean-field approximation. The Madelung potential makes density-functional calculations by the conventional single-site, coherent potential approximation practically identical to the more rigorous LSGF supercell results obtained with a single......-site local interaction zone. We demonstrate that the basic mechanism that governs the charge distribution is the screening of the net charges of the alloy components that makes the direct Coulomb interactions short ranged. In the atomic-sphere approximation, this screening appears to be almost independent...

  19. Spin diffusion in doped semiconductors: the role of Coulomb interactions

    OpenAIRE

    D'Amico, Irene; Vignale, Giovanni

    2000-01-01

    We examine the effect of the Coulomb interaction on the mobility and diffusion of spin packets in doped semiconductors. We find that the diffusion constant is reduced, relative to its non-interacting value, by the combined effect of Coulomb-enhanced spin susceptibility and spin Coulomb drag. In ferromagnetic semiconductors, the spin diffusion constant vanishes at the ferromagnetic transition temperature.

  20. The thermodynamics of a strictly non-ideal Coulomb system

    International Nuclear Information System (INIS)

    Using the equation of state for a symmetric quantum Coulomb system with strong interactions, the phase transition and the existence of the plasma state are analyzed. With a reduction potential which includes quantum effects, a generalization of Saha's formula is obtained. The thermodynamics stability of the system is demonstrated analytically. The isotherms for equilibrium ionization are presented and the stability of the system is studied. The electrical conductivity is analyzed in a region of critical values, and the predictions are compared with experimental data for which one observes a quantitative change in the conductivity. (L.C.)

  1. Proton radiography, nuclear cross sections and multiple Coulomb scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sjue, Sky K. [Los Alamos National Laboratory

    2015-11-04

    The principles behind proton radiography including multiple Coulomb scattering are discussed for a purely imaginary square well nucleus in the eikonal approximation. It is found that a very crude model can reproduce the angular dependence of the cross sections measured at 24 GeV/c. The largest differences are ~3% for the 4.56 mrad data, and ~4% for the 6.68 mrad data. The prospect of understanding how to model deterministically high-energy proton radiography over a very large range of energies is promising, but it should be tested more thoroughly.

  2. Coulomb excitation of the N=50 nucleus 80Zn

    OpenAIRE

    van de Walle, Jarno; Aksouh, Farouk; Ames, F.; Behrens, Thomas; Bildstein, V.; Blazhev, A.; Cederkall, Joakim; Clement, Emmanuel; Cocolios, Thomas Elias; Davinson, T.; Delahaye, Pierre; Eberth, J.; Ekstrom, Andreas; Fedorov, Dima V; Fedosseev, Valentin N.

    2008-01-01

    Neutron rich Zinc isotopes, including the N = 50 nucleus 80Zn, were produced and post-accelerated at the Radioactive Ion Beam (RIB) facility REX-ISOLDE (CERN). Low-energy Coulomb excitation was induced on these isotopes after post-acceleration, yielding B(E2) strengths to the first excited 2+ states. For the first time, an excited state in 80Zn was observed and the 21+ state in 78Zn was established. The measured B(E2,21+->01+) values are compared to two sets of large scale shell model calcula...

  3. A Variational Approach to the Structure and Thermodynamics of Linear Polyelectrolytes with Coulomb and Screened Coulomb Interactions

    CERN Document Server

    Jönsson, B; Söderberg, B

    1995-01-01

    A variational approach, based on a discrete representation of the chain, is used to calculate free energy and conformational properties in polyelectrolytes. The true bond and Coulomb potentials are approximated by a trial isotropic harmonic energy containing force constants between {\\em all}monomer-pairs as variational parameters. By a judicious choice of representation and the use of incremental matrix inversion, an efficient and fast-convergent iterative algorithm is constructed, that optimizes the free energy. The computational demand scales as $N^3$ rather than $N^4$ as expected in a more naive approach. The method has the additional advantage that in contrast to Monte Carlo calculations the entropy is easily computed. An analysis of the high and low temperature limits is given. Also, the variational formulation is shown to respect the appropriate virial identities.The accuracy of the approximations introduced are tested against Monte Carlo simulations for problem sizes ranging from $N=20$ to 1024. Very g...

  4. Simbuca, using a graphics card to simulate Coulomb interactions in a penning trap

    CERN Document Server

    Van Gorp, S; Friedag, P; De Leebeeck, V; Tandecki, M; Weinheimer, C; Breitenfeldt, M; Traykov, E; Severijn, N; Mader, J; Soti, G; Iitaka, T; Herlert, A; Wauters, F; Zakoucky, D; Kozlov, V; Roccia, S

    2011-01-01

    In almost all cases, N-body simulations are limited by the computation time available. Coulomb interaction calculations scale with O(N(2)) with N the number of particles. Approximation methods exist already to reduce the computation time to O(NlogN) although calculating the interaction still dominates the total simulation time. We present Simbuca, a simulation package for thousands of ions moving in a Penning trap which will be applied for the WITCH experiment. Simbuca uses the output of the Cunbody-1 library, which calculates the gravitational interaction between entities on a graphics card, and adapts it for Coulomb calculations. Furthermore the program incorporates three realistic buffer gas models, the possibility of importing realistic electric and magnetic fieldmaps and different order integrators with adaptive step size and error control. The software is released under the GNU General Public License and free for use. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

  5. Simbuca, using a graphics card to simulate Coulomb interactions in a penning trap

    Energy Technology Data Exchange (ETDEWEB)

    Van Gorp, S., E-mail: simon.vangorp@fys.kuleuven.b [Instituut voor Kern- en Stralingsfysica, K.U.Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Beck, M. [Universitaet Muenster, Institut fuer Kernphysik, Wilhelm-Klemm-Strasse 9, D-48149 Muenster (Germany); Breitenfeldt, M.; De Leebeeck, V. [Instituut voor Kern- en Stralingsfysica, K.U.Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Friedag, P. [Universitaet Muenster, Institut fuer Kernphysik, Wilhelm-Klemm-Strasse 9, D-48149 Muenster (Germany); Herlert, A. [CERN, CH-1211 Geneve 23 (Switzerland); Iitaka, T. [Computational Astrophysics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Mader, J. [Universitaet Muenster, Institut fuer Kernphysik, Wilhelm-Klemm-Strasse 9, D-48149 Muenster (Germany); Kozlov, V. [Karlsruhe Institute of Technology, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany); Roccia, S.; Soti, G.; Tandecki, M.; Traykov, E.; Wauters, F. [Instituut voor Kern- en Stralingsfysica, K.U.Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Weinheimer, Ch. [Universitaet Muenster, Institut fuer Kernphysik, Wilhelm-Klemm-Strasse 9, D-48149 Muenster (Germany); Zakoucky, D. [Nuclear Physics Institute, ASCR, CZ-250 68 Rez (Czech Republic); Severijns, N. [Instituut voor Kern- en Stralingsfysica, K.U.Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium)

    2011-05-11

    In almost all cases, N-body simulations are limited by the computation time available. Coulomb interaction calculations scale with O(N{sup 2}) with N the number of particles. Approximation methods exist already to reduce the computation time to O(NlogN), although calculating the interaction still dominates the total simulation time. We present Simbuca, a simulation package for thousands of ions moving in a Penning trap which will be applied for the WITCH experiment. Simbuca uses the output of the Cunbody-1 library, which calculates the gravitational interaction between entities on a graphics card, and adapts it for Coulomb calculations. Furthermore the program incorporates three realistic buffer gas models, the possibility of importing realistic electric and magnetic fieldmaps and different order integrators with adaptive step size and error control. The software is released under the GNU General Public License and free for use.

  6. Coulomb stress interactions among M≥5.9 earthquakes in the Gorda deformation zone and on the Mendocino Fracture Zone, Cascadia megathrust, and northern San Andreas fault

    Science.gov (United States)

    Rollins, John C.; Stein, Ross S.

    2010-01-01

    The Gorda deformation zone, a 50,000 km2 area of diffuse shear and rotation offshore northernmost California, has been the site of 20 M ≥ 5.9 earthquakes on four different fault orientations since 1976, including four M ≥ 7 shocks. This is the highest rate of large earthquakes in the contiguous United States. We calculate that the source faults of six recent M ≥ 5.9 earthquakes had experienced ≥0.6 bar Coulomb stress increases imparted by earthquakes that struck less than 9 months beforehand. Control tests indicate that ≥0.6 bar Coulomb stress interactions between M ≥ 5.9 earthquakes separated by Mw = 7.3 Trinidad earthquake are consistent with the locations of M ≥ 5.9 earthquakes in the Gorda zone until at least 1995, as well as earthquakes on the Mendocino Fault Zone in 1994 and 2000. Coulomb stress changes imparted by the 1980 earthquake are also consistent with its distinct elbow-shaped aftershock pattern. From these observations, we derive generalized static stress interactions among right-lateral, left-lateral and thrust faults near triple junctions.

  7. Manifestation of nuclear cluster structure in Coulomb sums

    CERN Document Server

    Buki, A Yu

    2016-01-01

    Experimental Coulomb sum values of 6^Li and 7^Li nuclei have been obtained, extending the earlier reported momentum transfer range of Coulomb sums for these nuclei up to q = 0.750 ... 1.625 fm^-1. The dependence of the Coulomb sums on the momentum transfers of 6^Li and 7^Li is shown to differ substantially from similar dependences for all the other nuclei investigated. Relationship between the nuclear cluster structure and Coulomb sums has been considered. The momentum transfer value, above which the Coulomb sum becomes constant, is found to be related to the cluster isolation parameter x, which characterizes the degree of nuclear clusterization.

  8. Coulomb interaction in Eliashberg theory of superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Davydov, Arkady; Sanna, Antonio [Max-Planck-Institute of Microstructure Physics, Halle (Saale) (Germany)

    2013-07-01

    The Eliashberg theory of superconductivity allows to describe materials with strong pairing interaction. In the non magnetic case it leads to a system of coupled integral multidimensional equations. Computational costs are usually reduced by an isotropic limit, and by restricting the Coulomb interaction to the use of one single parameter, μ{sup *}, often chosen to give the experimental T{sub c}. In this work we present the parameter-free approach in which the screened Coulomb interaction fully accounted within the Random Phase Approximation, entering the Eliashberg's equations on the same footing as the phononic interaction. We will compare this approach with Density Functional Theory for Superconductors where the corresponding approximation leads to a good agreement with experiments.

  9. Feynman rules for Coulomb gauge QCD

    International Nuclear Information System (INIS)

    The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ–Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the sub-graph structure of ordinary Feynman graphs. The CL terms do not have a sub-graph structure. We show how to carry out renormalization in the presence of CL terms, by re-expressing these as ‘pseudo-Feynman’ integrals. We also explain how energy divergences cancel. - Highlights: ► In Coulomb gauge QCD, we re-express Christ–Lee terms in the Hamiltonian as pseudo-Feynman integrals. ► This gives a subgraph structure, and allows the ordinary renormalization process. ► It also leads to cancellation of energy-divergences.

  10. Coulomb Bound States of Strongly Interacting Photons

    Science.gov (United States)

    Maghrebi, M. F.; Gullans, M. J.; Bienias, P.; Choi, S.; Martin, I.; Firstenberg, O.; Lukin, M. D.; Büchler, H. P.; Gorshkov, A. V.

    2015-09-01

    We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasibound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wave function resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.

  11. Coulomb drag in topological insulator films

    Science.gov (United States)

    Liu, Hong; Liu, Weizhe Edward; Culcer, Dimitrie

    2016-05-01

    We study Coulomb drag between the top and bottom surfaces of topological insulator films. We derive a kinetic equation for the thin-film spin density matrix containing the full spin structure of the two-layer system, and analyze the electron-electron interaction in detail in order to recover all terms responsible for Coulomb drag. Focusing on typical topological insulator systems, with a film thicknesses d up to 6 nm, we obtain numerical and approximate analytical results for the drag resistivity ρD and find that ρD is proportional to T2d-4 na-3/2 np-3/2 at low temperature T and low electron density na,p, with a denoting the active layer and p the passive layer. In addition, we compare ρD with graphene, identifying qualitative and quantitative differences, and we discuss the multi-valley case, ultra thin films and electron-hole layers.

  12. Coulomb bound states of strongly interacting photons

    CERN Document Server

    Maghrebi, M F; Bienias, P; Choi, S; Martin, I; Firstenberg, O; Lukin, M D; Büchler, H P; Gorshkov, A V

    2015-01-01

    We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasi-bound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wavefunction resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.

  13. Coulomb interaction in Eliashberg theory of superconductivity

    International Nuclear Information System (INIS)

    The Eliashberg theory of superconductivity allows to describe materials with strong pairing interaction. In the non magnetic case it leads to a system of coupled integral multidimensional equations. Computational costs are usually reduced by an isotropic limit, and by restricting the Coulomb interaction to the use of one single parameter, μ*, often chosen to give the experimental Tc. In this work we present the parameter-free approach in which the screened Coulomb interaction fully accounted within the Random Phase Approximation, entering the Eliashberg's equations on the same footing as the phononic interaction. We will compare this approach with Density Functional Theory for Superconductors where the corresponding approximation leads to a good agreement with experiments.

  14. On the effects of nuclear structure and the coulomb interaction at diffraction deuteron-nucleus scattering

    International Nuclear Information System (INIS)

    Within diffraction model framework it has been proposed the method of cross section calculation of deuteron-nucleus scattering at intermediate energies. The deuteron wave function was chosen as Hulten one, the Coulomb interaction and nuclear surface diffuseness of targets were taken into account. The calculating cross sections of 700 MeV deuteron elastic scattering from 40Ca and 58Ni satisfactorily fit the experimental data

  15. On the effects of nuclear structure and the coulomb interaction at diffraction deuteron-nucleus scattering

    CERN Document Server

    Kovalchuk, V I; Ivanova, O I

    2003-01-01

    Within diffraction model framework it has been proposed the method of cross section calculation of deuteron-nucleus scattering at intermediate energies. The deuteron wave function was chosen as Hulten one, the Coulomb interaction and nuclear surface diffuseness of targets were taken into account. The calculating cross sections of 700 MeV deuteron elastic scattering from sup 4 sup 0 Ca and sup 5 sup 8 Ni satisfactorily fit the experimental data.

  16. Coulomb blockade at almost perfect transmission

    OpenAIRE

    Matveev, K. A.

    1994-01-01

    We study the equilibrium properties of a quantum dot connected to a bulk lead by a single-mode quantum point contact. The ground state energy and other thermodynamic characteristics of the grain show periodic dependence on the gate voltage (Coulomb blockade). We consider the case of almost perfect transmission, and show that the oscillations exist as long as the transmission coefficient of the contact is less than unity. Near the points where the dot charge is half-integer the thermodynamic c...

  17. Chaos near the Coulomb barrier. Nuclear molecules

    International Nuclear Information System (INIS)

    The present work examines in detail the classical behavior of the α + 14C and the 12C + 12C(O+) collison at energies near the Coulomb barrier. The long-time motion of the compound nuclear system is identified in terms of its classical quasiperiodic and chaotic behavior. The consequences of this motion are discussed and interpreted in terms of the evolution of the system along a dynamical energy surface. 45 references

  18. Lorenz or Coulomb in Galilean Electromagnetism ?

    OpenAIRE

    Rousseaux, Germain

    2005-01-01

    PDF version International audience Galilean Electromagnetism was discovered thirty years ago by Levy-Leblond & Le Bellac. However, these authors only explored the consequences for the fields and not for the potentials. Following De Montigny & al., we show that the Coulomb gauge condition is the magnetic limit of the Lorenz gauge condition whereas the Lorenz gauge condition applies in the electric limit of Lévy-Leblond & Le Bellac. Contrary to De Montigny & al. who used Galilean tensor c...

  19. Coulomb drag in the mesoscopic regime

    DEFF Research Database (Denmark)

    Mortensen, N.A.; Flensberg, Karsten; Jauho, Antti-Pekka

    2002-01-01

    We present a theory for Coulomb drag between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....

  20. Coulomb drag in the mesoscopic regime

    DEFF Research Database (Denmark)

    Mortensen, N. Asger; Flensberg, Karsten; Jauho, Antti-Pekka

    2002-01-01

    We present a theory for Coulomb drug between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....

  1. Module of System Galactica with Coulomb's Interaction

    Directory of Open Access Journals (Sweden)

    Joseph J. Smulsky

    2014-12-01

    Full Text Available The system Galactica of free access is supplemented module for the Coulomb interaction. It is based on a high-precision method for solving differential equations of motion of N charged particles. The paper presents all the theoretical and practical issues required to use this module of system Galactica so that even the beginning researcher could study the motion of particles, atoms and molecules.

  2. Coulomb dissociation studies for astrophysical thermonuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Motobayashi, T. [Dept. of Physics, Rikkyo Univ., Toshima, Tokyo (Japan)

    1998-06-01

    The Coulomb dissociation method was applied to several radiative capture processes of astrophysical interest. The method has an advantage of high experimental efficiency, which allow measurements with radioactive nuclear beams. The reactions {sup 13}N(p,{gamma}){sup 14}O and {sup 7}Be(p,{gamma}){sup 8}B are mainly discussed. They are the key reaction in the hot CNO cycle in massive stars and the one closely related to the solar neutrino problem, respectively. (orig.)

  3. Coulomb drag in the mesoscopic regime

    DEFF Research Database (Denmark)

    Mortensen, N. Asger; Flensberg, Karsten; Jauho, Antti-Pekka

    We present a theory for Coulomb drug between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....

  4. Efficient Finite Element Calculation of Nγ

    DEFF Research Database (Denmark)

    Clausen, Johan; Damkilde, Lars; Krabbenhøft, K.

    2007-01-01

    This paper deals with the computational aspects of the Mohr-Coulomb material model, in particular the calculation of the bearing capacity factor Nγfor a strip and a circular footing.......This paper deals with the computational aspects of the Mohr-Coulomb material model, in particular the calculation of the bearing capacity factor Nγfor a strip and a circular footing....

  5. Dynamics of Coulombic and gravitational periodic systems

    Science.gov (United States)

    Kumar, Pankaj; Miller, Bruce N.

    2016-04-01

    We study the dynamics and the phase-space structures of Coulombic and self-gravitating versions of the classical one-dimensional three-body system with periodic boundary conditions. We demonstrate that such a three-body system may be reduced isomorphically to a spatially periodic system of a single particle experiencing a two-dimensional potential on a rhombic plane. For the case of both Coulombic and gravitational versions, exact expressions of the Hamiltonian have been derived in rhombic coordinates. We simulate the phase-space evolution through an event-driven algorithm that utilizes analytic solutions to the equations of motion. The simulation results show that the motion exhibits chaotic, quasiperiodic, and periodic behaviors in segmented regions of the phase space. While there is no evidence of global chaos in either the Coulombic or the gravitational system, the former exhibits a transition from a completely nonchaotic phase space at low energies to a mixed behavior. Gradual yet striking transitions from mild to intense chaos are indicated with changing energy, a behavior that differentiates the spatially periodic systems studied in this Rapid Communication from the well-understood free-boundary versions of the three-body problem. Our treatment of the three-body systems opens avenues for analysis of the dynamical properties exhibited by spatially periodic versions of various classes of systems studied in plasma and gravitational physics as well as in cosmology.

  6. Coseismic and postseismic Coulomb stress changes on intra-continental dip-slip faults and the role of viscoelastic relaxation in the lower crust: insights from 3D finite-element models

    Science.gov (United States)

    Bagge, Meike; Hampel, Andrea

    2016-04-01

    Investigating the stress interaction of faults plays a crucial role for assessing seismic hazard of a region. The calculation of Coulomb stress changes allows quantifying stress changes on so-called receiver faults in the surrounding of a source fault that was ruptured during an earthquake. Positive Coulomb stress changes bring receiver faults closer to failure, while a negative value indicates a delay of the next earthquake. Besides the coseismic ('static') stress changes, postseismic ('transient') stress changes induced by postseismic viscoelastic relaxation occur. Here we use 3D finite-element models with arrays of normal or thrust faults to study the coseismic stress changes and the stress changes arising from postseismic relaxation in the lower crust. The lithosphere is divided into an elastic upper crust, a viscoelastic lower crust and a viscoelastic lithospheric mantle. Gravity is included in the models. Driven by extension or shortening of the model, slip on the fault planes develops in a self-consistent way. We modelled an earthquake on a 40-km-long source fault with a coseismic slip of 2 m and calculated the displacement fields and Coulomb stress changes during the coseismic and postseismic phases. The results for the coseismic phase (Bagge and Hampel, Tectonophysics in press) show that synthetic receiver faults in the hanging wall and footwall of the source fault exhibit a symmetric distribution of the coseismic Coulomb stress changes on each fault, with large areas of negative stress changes but also some smaller areas of positive values. In contrast, faults positioned in along-strike prolongation of the source fault and outside of its hanging wall and footwall undergo mostly positive stress changes. Postseismic stress changes caused by viscous flow modify the static stress changes in a way that the net Coulomb stress changes on the receiver faults change significantly through space and time. Our models allow deciphering the combined effect of stress

  7. Proton and alpha-particle capture reactions at sub-Coulomb energies relevant to the p process

    Energy Technology Data Exchange (ETDEWEB)

    Harissopulos, S [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Lagoyannis, A [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Spyrou, A [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Zarkadas, Ch [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Galanopoulos, S [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Perdikakis, G [Tandem Accelerator Facility, Institute of Nuclear Physics, NCSR ' Demokritos' , 153.10 Aghia Paraskevi, Athens (Greece); Becker, H-W [Dynamitron-Tandem-Laboratorium, Ruhr Universitaet Bochum, 44801 Bochum (Germany); Rolfs, C [Institut fuer Physik mit Ionenstrahlen, EP-II, Ruhr-Universitaet BochumI, 44801 Bochum (Germany); Strieder, F [Institut fuer Physik mit Ionenstrahlen, EP-II, Ruhr-Universitaet BochumI, 44801 Bochum (Germany); Kunz, R [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Fey, M [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Hammer, J W [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Dewald, A [Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Cologne (Germany); Zell, K-O [Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Cologne (Germany); Brentano, P von [Institut fuer Kernphysik, Universitaet zu Koeln, 50937 Cologne (Germany); Julin, R [Department of Physics, University of Jyvaeskylae, 40014 Jyvaeskylae (Finland); Demetriou, P [Institut d' Astronomie et d' Astrophysique, Universite Libre de Bruxelles, CP226, 1050 Brussels (Belgium)

    2005-10-01

    Several cross-section measurements of proton as well as {alpha}-particle capture reactions in the Se-Sb region have been carried out at sub-Coulomb energies with the aim to obtain global input parameters for Hauser-Feshbach (HF) calculations. Some of the results are compared with HF calculations using various optical model potentials and nuclear level densities.

  8. On Calculation of Amplitudes in Quantum Electrodynamics

    OpenAIRE

    Karplyuk, Kostyantyn; Zhmudsky, Oleksandr

    2012-01-01

    A new method of calculation of amplitudes of different processes in quantum electrodynamics is proposed. The method does not use the Feynman technique of trace of product of matrices calculation. The method strongly simplifies calculation of cross sections for different processes. The effectiveness of the method is shown on the cross-section calculation of Coulomb scattering, Compton scattering and electron-positron annihilation.

  9. Electrostatics of Coulomb gas, lattice paths and discrete polynuclear growth

    International Nuclear Information System (INIS)

    We study the partition function of a two-dimensional Coulomb gas on a circle, in the presence of external pointlike charges, in a double scaling limit where both the external charges and the number of gas particles are large. Our original motivation comes from studying amplitudes for multi-string emission from a decaying D-brane in the high-energy limit. We analyze the scaling limit of the partition function and calculate explicit results. We also consider applications to random matrix theory. The partition functions can be related to random scattering or to weights of lattice paths in certain growth models. In particular, we consider the discrete polynuclear growth model and use our results to compute the cumulative probability density for the height of long level-1 paths. We also obtain an estimate for an almost certain maximum height.

  10. Coulomb-potential-dependent decohesion of Magneli phases

    International Nuclear Information System (INIS)

    Transition metal oxide Magneli phases are traditionally described as crystallographic shear structures. Some of these phases feature a layered crystal structure based on deformed metal-oxygen octahedra. Here, we describe the correlation between structure, decohesion energies and elastic properties of WO3, ReO3, MoO2, VO2, V2O5 and TiO2 using ab initio calculations. Decohesion energies and elastic constants C44 are inversely proportional to the original distance between the cleaved layers and correspond to the screened Coulomb potential. This can be understood based on the electronic structure. The bond strength decreases rapidly as the distance is increased, resulting in weak coupling between the layers, which in turn causes the formation of easily plastically deformable structures. (fast track communication)

  11. Upper-division student understanding of Coulomb's law: Difficulties with continuous charge distributions

    Science.gov (United States)

    Wilcox, Bethany R.; Caballero, Marcos D.; Pepper, Rachel E.; Pollock, Steven J.

    2013-01-01

    Utilizing the integral expression of Coulomb's Law to determine the electric potential from a continuous charge distribution is a canonical exercise in Electricity and Magnetism (E&M). In this study, we use both think-aloud interviews and responses to traditional exam questions to investigate student difficulties with this topic at the upper-division level. Leveraging a theoretical framework for the use of mathematics in physics, we discuss how students activate, construct, execute and reflect on the integral form of Coulomb's Law when solving problems with continuous charge distributions. We present evidence that junior-level E&M students have difficulty mapping physical systems onto the mathematical expression for the Coulomb potential. Common challenges include difficulty expressing the difference vector in appropriate coordinates as well as determining expressions for the differential charge element and limits of integration for a specific charge distribution. We discuss possible implications of these findings for future research directions and instructional strategies.

  12. Upper-division Student Understanding of Coulomb's Law: Difficulties with Continuous Charge Distributions

    CERN Document Server

    Wilcox, Bethany R; Pepper, Rachel E; Pollock, Steven J

    2012-01-01

    Utilizing the integral expression of Coulomb's Law to determine the electric potential from a continuous charge distribution is a canonical exercise in Electricity and Magnetism (E&M). In this study, we use both think-aloud interviews and responses to traditional exam questions to investigate student difficulties with this topic at the upper-division level. Leveraging a theoretical framework for the use of mathematics in physics, we discuss how students activate, construct, execute and reflect on the integral form of Coulomb's Law when solving problems with continuous charge distributions. We present evidence that junior-level E&M students have difficulty mapping physical systems onto the mathematical expression for the Coulomb potential. Common challenges include difficulty expressing the difference vector in appropriate coordinates as well as determining expressions for the differential charge element and limits of integration for a specific charge distribution. We discuss possible implications of t...

  13. Recoil ions from molecular targets: sequential Coulomb explosions

    International Nuclear Information System (INIS)

    Fast ion collision processes appear to be ideal for producing multiply charged molecular ions. The advantage of this technique has not been appreciated so far and very little work has been carried out so far. We have initiated a programme to study the formation of multiply charged molecular ions and their dissociation dynamics using fast ion beam from the pelletron. Measurements have been carried out on several molecules including N2, CO, CO2, CS2, CH4 and CH3I. Measurements of the kinetic energy distributions of the fragment ions provided novel results on the fragmentation of CS2 and CO2 ions. As expected the positive ions of S and O possessed very large kinetic energies resulting from the Coulomb explosion of highly charged molecular ions. The surprising result was that the positive ions (C+ and C2+) from the central carbon atom of the linear symmetric molecules possessed much larger energies that what is expected from the conventional physical picture of Coulomb explosion. It is concluded that the observed high kinetic energy C+ and C2+ ions are formed by sequential fragmentation of CO2n+ ions through an intermediate K-shell excited CO+* ions. (author). 4 refs., 1 fig

  14. Wavelength calculation of highly stripped ions S10+→S13+, Br23+, Br24+, Ge20+, Ge21+

    International Nuclear Information System (INIS)

    Wavelengths of highly stripped ions S10+ →S13+ , Br23+ , Br24+ , Ge20+ , Ge21+ are calculated by means of GRASP code. The calculations are performed based on multiconfiguration Dirac-Fock technique. Corrections to the energy levels due to the retarded Coulomb interaction (Breit interaction) and the polarization of the vacuum by the nuclear distribution and electron self-energy are included in a perturbation approximation. Comparisons with the new experimental data by CIAE group are presented

  15. Role of the Coulomb interaction in the flow and the azimuthal distribution of kaons from heavy ion reactions

    CERN Document Server

    Wang, Z S; Fuchs, C; Maheswari, V S U; Kosov, D S; Faessler, Amand

    1998-01-01

    Coulomb final-state interaction of positive charged kaons in heavy ion reactions and its impact on the kaon transverse flow and the kaon azimuthal distribution are investigated within the framework of QMD (Quantum Molecular Dynamics) model. The Coulomb interaction is found to tend to draw the flow of kaons away from that of nucleons and lead to a more isotropic azimuthal distribution of kaons in the target rapidity region. The recent FOPI data have been analyzed by taking into accout both the Coulomb interaction and a kaon in-medium potential of the strong interaction. It is found that both the calculated kaon flows with only the Coulomb interaction and with both the Coulomb interaction and the strong potential agree within the error bars with the data. The kaon azimuthal distribution exhibits asymmetries of similar magnitude in both theoretical approaches. This means, the inclusion of the Coulomb potential makes it more difficult to extract information of the kaon mean field potential in nuclear matter from ...

  16. Coulomb drag in anisotropic systems: a theoretical study on a double-layer phosphorene

    Science.gov (United States)

    Saberi-Pouya, S.; Vazifehshenas, T.; Farmanbar, M.; Salavati-fard, T.

    2016-07-01

    We theoretically study the Coulomb drag resistivity in a double-layer electron system with highly anisotropic parabolic band structure using Boltzmann transport theory. As an example, we consider a double-layer phosphorene on which we apply our formalism. This approach, in principle, can be tuned for other double-layered systems with paraboloidal band structures. Our calculations show the rotation of one layer with respect to another layer can be considered a way of controlling the drag resistivity in such systems. As a result of rotation, the off-diagonal elements of the drag resistivity tensor have non-zero values at any temperature. In addition, we show that the anisotropic drag resistivity is very sensitive to the direction of momentum transfer between two layers due to highly anisotropic inter-layer electron–electron interaction and also the plasmon modes. In particular, the drag anisotropy ratio, {ρyy}/{ρxx} , can reach up to ∼ 3 by changing the temperature. Furthermore, our calculations suggest that including the local field correction in the dielectric function changes the results significantly. Finally, We examine the dependence of drag resistivity and its anisotropy ratio on various parameters like inter-layer separation, electron density, short-range interaction and insulating substrate/spacer.

  17. The effect of the nuclear Coulomb field on atomic ionization at positron-electron annihilation in β+- decay

    Directory of Open Access Journals (Sweden)

    Fedotkin Sergey

    2015-01-01

    Full Text Available We consider the process of the annihilation of a positron emitted at β+- decay and a K-electron of the daughter atom. A part of energy during this process is passed to another K- electron and it leaves the atom. The influence of the Coulomb field on the positron and the ejected electron is considered. It was calculated the probability of this process for an atom with arbitrary Z is calculated. For the nucleus Ti the effect of the Coulomb field essentially increases the probability of the considered process.

  18. The effect of the nuclear Coulomb field on atomic ionization at positron-electron annihilation in β+- decay

    OpenAIRE

    Fedotkin Sergey

    2015-01-01

    We consider the process of the annihilation of a positron emitted at β+- decay and a K-electron of the daughter atom. A part of energy during this process is passed to another K- electron and it leaves the atom. The influence of the Coulomb field on the positron and the ejected electron is considered. It was calculated the probability of this process for an atom with arbitrary Z is calculated. For the nucleus Ti the effect of the Coulomb field essentially increases the probability of the cons...

  19. Dynamic properties of the Coulomb fission

    International Nuclear Information System (INIS)

    The heavy ion induced fission after quasi-elastic scattering was studied in the systems 208Pb -> 238U for central collision at energies below the Coulomb barrier and 238U -> 238U for peripheral collisions at scattering angles smaller than the grazing angle. The dynamical properties and the phase-space distributions of the reactions could be determined by the method of the kinematical coincidences where positions and time-of-flight of two fission fragments and a scattered projectile-like nucleus were measured at the same time in large-area gas-filled parallel plate counters. (orig./HSI)

  20. Multiple Coulomb scattering in thin silicon

    International Nuclear Information System (INIS)

    We present a measurement of multiple Coulomb scattering of 1 to 6 GeV/c electrons in thin (50–140 μm) silicon targets. The data were obtained with the EUDET telescope Aconite at DESY and are compared to parametrisations as used in the Geant4 software package. We find good agreement between data and simulation in the scattering distribution width but large deviations in the shape of the distribution. In order to achieve a better description of the shape, a new scattering model based on a Student's t distribution is developed and compared to the data

  1. Resonances in the two centers Coulomb system

    Energy Technology Data Exchange (ETDEWEB)

    Seri, Marcello

    2012-09-14

    In this work we investigate the existence of resonances for two-centers Coulomb systems with arbitrary charges in two and three dimensions, defining them in terms of generalized complex eigenvalues of a non-selfadjoint deformation of the two-center Schroedinger operator. After giving a description of the bifurcation of the classical system for positive energies, we construct the resolvent kernel of the operators and we prove that they can be extended analytically to the second Riemann sheet. The resonances are then defined and studied with numerical methods and perturbation theory.

  2. Expectation values in relativistic Coulomb problems

    Energy Technology Data Exchange (ETDEWEB)

    Suslov, Sergei K, E-mail: sks@asu.ed [School of Mathematical and Statistical Sciences and Mathematical, Computational, and Modeling Sciences Center, Arizona State University, Tempe, AZ 85287-1804 (United States)

    2009-09-28

    We evaluate the matrix elements (Or{sup p}), where O = {l_brace}, {beta},i{alpha}n{beta}{r_brace} are the standard Dirac matrix operators and the angular brackets denote the quantum-mechanical average for the relativistic Coulomb problem, in terms of generalized hypergeometric functions {sub 3}F{sub 2}(1) for all suitable powers. Their connections with the Chebyshev and Hahn polynomials of a discrete variable are emphasized. As a result, we derive two sets of Pasternack-type matrix identities for these integrals, when p -> -p - 1 and p -> -p - 3, respectively. Some applications to the theory of hydrogenlike relativistic systems are reviewed.

  3. Ordering transitions induced by Coulomb interactions

    International Nuclear Information System (INIS)

    We briefly review recent progress in treating phase transitions to ordered states driven by Coulomb interactions. Wigner crystallization of the one-component plasma, in the degenerate Fermi limit and in the classical limit, is the foremost example and developments in its theory are discussed in some detail. Attention is also given to quasi-twodimensional realizations of the plasma model in the laboratory. The usefulness of these ideas in relation to freezing and ordering transitions is illustrated with reference to alkali metals, elemental and polar semiconductors, and various types of ionic systems (molten salts, colloidal suspensions and astrophysical plasmas). (author). 70 refs, 5 figs

  4. Feynman rules for Coulomb gauge QCD

    CERN Document Server

    Andrasi, A

    2012-01-01

    The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ-Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the subgraph structure of ordinary Feynamn graphs. The CL terms do not have subgraph structure. We show how to carry out enormalization in the presene of CL erms, by re-expressing these as `pseudo-Feynman' inegrals. We also explain how energy divergences cancel.

  5. Overlap Quark Propagator in Coulomb Gauge QCD

    CERN Document Server

    Mercado, Ydalia Delgado; Schröck, Mario

    2014-01-01

    The chirally symmetric Overlap quark propagator is explored in Coulomb gauge. This gauge is well suited for studying the relation between confinement and chiral symmetry breaking, since confinement can be attributed to the infrared divergent Lorentz-vector dressing function. Using quenched gauge field configurations on a $20^4$ lattice, the quark propagator dressing functions are evaluated, the dynamical quark mass is extracted and the chiral limit of these quantities is discussed. By removing the low-lying modes of the Dirac operator, chiral symmetry is artificially restored. Its effect on the dressing functions is discussed.

  6. Resonances in the two centers Coulomb system

    International Nuclear Information System (INIS)

    In this work we investigate the existence of resonances for two-centers Coulomb systems with arbitrary charges in two and three dimensions, defining them in terms of generalized complex eigenvalues of a non-selfadjoint deformation of the two-center Schroedinger operator. After giving a description of the bifurcation of the classical system for positive energies, we construct the resolvent kernel of the operators and we prove that they can be extended analytically to the second Riemann sheet. The resonances are then defined and studied with numerical methods and perturbation theory.

  7. Action principle for Coulomb collisions in plasmas

    CERN Document Server

    Hirvijoki, Eero

    2015-01-01

    In this letter we derive an action principle for Coulomb collisions in plasmas. Although no natural Lagrangian exists for the Landau-Fokker-Planck equation, an Eulerian variational formulation is found considering the system of partial differential equations that couple the distribution function and the Rosenbluth potentials. Exact conservation laws are derived after generalizing the energy-momentum stress tensor for second order Lagrangians and, in the case of a test-particle population in a given plasma background, the action principle is shown to correspond to the Langevin equation for individual particles. Being suitable for discretization, the presented action allows construction of variational integrators. Numerical implementation is left for a future study.

  8. Static color-Coulomb force from restriction to Gribov region

    International Nuclear Information System (INIS)

    The static color-Coulomb interaction potential is determined as the solution of a non-linear integral equation. This equation expresses a self-consistency condition which arises in the Coulomb Hamiltonian formulation of lattice gauge theory when the restriction to the interior of the Gribov horizon is implemented. The potential obtained is in qualitatively agreement with expectations, being Coulombic with logarithmic corrections at short range, and confining at long range. (author)

  9. Coulomb sum rules in the relativistic Fermi gas model

    International Nuclear Information System (INIS)

    Coulomb sum rules are studied in the framework of the Fermi gas model. A distinction is made between mathematical and observable sum rules. Differences between non-relativistic and relativistic Fermi gas predictions are stressed. A method to deduce a Coulomb response function from the longitudinal response is proposed and tested numerically. This method is applied to the 40Ca data to obtain the experimental Coulomb sum rule as a function of momentum transfer

  10. From the Coulomb breakup of halo nuclei to neutron radiative capture

    CERN Document Server

    Capel, Pierre

    2016-01-01

    Coulomb breakup is used to infer radiative-capture cross sections at astrophysical energies. We test theoretically the accuracy of this indirect technique in the particular case of 15C, for which both the Coulomb breakup to ^{14}C+n and the radiative capture 14C(n,{\\gamma})15C have been measured. We analyse the dependance of Coulomb-breakup calculations on the projectile description in both its initial bound state and its continuum. Our calculations depend not only on the Asymptotic Normalisation Coefficient (ANC) of the 15C ground state, but also on the 14C-n continuum. This questions the method proposed by Summers and Nunes [Phys. Rev. C 78, 011601 (2008), ibid. 78, 069908 (2008)], which assumes that an ANC can be directly extracted from the comparison of calculations to breakup data. Fortunately, the sensitivity to the continuum description can be absorbed in a normalisation constant obtained by a simple {\\chi}2 fit of our calculations to the measurements. By restricting this fit to low 14C-n energy in the...

  11. Electrostatic Energy Calculations for Molecular Dynamics

    CERN Document Server

    Love, M J; Comment, Henri J.F. Jansen; Love, Michael J.

    1995-01-01

    The evaluation of Coulomb forces is a difficult task. The summations that are involved converge only conditionally and care has to be taken in selecting the appropriate procedure to define the limits. The Ewald method is a standard method for obtaining Coulomb forces, but this method is rather slow, since it depends on the square of the number of atoms in a unit cell. In this paper we have adapted the plane-wise summation method for the evaluation of Coulomb forces. The use of this method allows for larger computational cells in molecular dynamics calculations.

  12. Effect of Coulomb interaction on multi-electronwave packet dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Shiokawa, T. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571 (Japan); Takada, Y. [Faculty of Engineering, Tokyo University of Science, Chiyoda, Tokyo, 102-0073, Japan and CREST, Japan Science and Technology Agency (Japan); Konabe, S.; Hatsugai, Y. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and CREST, Japan Science and Technology Agency (Japan); Muraguchi, M. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and CREST, Japan Science and Technology Agency (Japan); Endoh, T. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and Center for Spintronics Integrated Systems, Tohoku University, Sendai, 980-8577, Japan and CREST, Japan Science and Technology Agency (Japan); Shiraishi, K. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and Center for Computational Science, University of Tsukuba, Tsukuba, 305-8577, Japan and CREST, Japan Science and Technology Agency (Japan)

    2013-12-04

    We have investigated the effect of Coulomb interaction on electron transport in a one-dimensional nanoscale structure using a multi-electron wave packet approach. To study the time evolution, we numerically solve the time-dependent Hartree-Fock equation, finding that the electron wave packet dynamics strongly depends on the Coulomb interaction strength. When the Coulomb interaction is large, each electron wave packet moves separately in the presence of an electric field. With weak Coulomb interaction, however, the electron wave packets overlap, forming and moving as one collective wave packet.

  13. Long range effects on the optical model of 6He around the Coulomb barrier

    CERN Document Server

    Fernandez-Garcia, J P; Alvarez, M A G; Moro, A M

    2010-01-01

    We present an optical model (OM) analysis of the elastic scattering data of the reactions 6He+27Al and 6He+208Pb at incident energies around the Coulomb barrier. The bare part of the optical potential is constructed microscopically by means of a double folding procedure, using the Sao Paulo prescription without any renormalization. This bare interaction is supplemented with a Coulomb dipole polarization (CDP) potential, which takes into account the effect of the dipole Coulomb interaction. For this CDP potential, we use an analytical formula derived from the semiclassical theory of Coulomb excitation. The rest of the optical potential is parametrized in terms of Woods-Saxon shapes. In the 6He+208Pb case, the analysis confirms the presence of long range components, in agreement with previous works. Four-body Continuum-Discretized Coupled-Channels calculations have been performed in order to better understand the features of the optical potentials found in the OM analysis. This study searches to elucidate some ...

  14. Probing single-particle and collective states in atomic nuclei with Coulomb excitation

    CERN Document Server

    DiJulio, Douglas

    A series of experiments and developments, related to stable and radioactive isotopes, have been carried out. These studies have focused on measuring the low-lying excitations of spherical and deformed nuclei using electromagnetic (Coulomb) excitation and also on developments in detector technology for upcoming radioactive ion beams facilities. The low-lying excitations in the nuclei 107,109Sn and 107In have been investigated using low-energy Coulomb excitation at the REX-ISOLDE facility at CERN. The measured reduced transition probabilities were compared to predictions of nuclear structure models. In addition, a relativistic Coulomb excitation experiment was carried out using the FRS at GSI with the nucleus 104Sn. These radioactive ion beam experiments provide important constraints for large-scale-shell-model calculations in the region of the doubly magic nucleus 100Sn. A stable Coulomb excitation experiment was also carried out in order to explore the properties of low-lying structures in the nucleus 170Er...

  15. Effects of level inversion on the Coulomb displacement energies of the Ar-K isobaric analog state pairs

    CERN Document Server

    Wang, Zaijun; Xu, Renli

    2016-01-01

    The Coulomb displacement energies of the neutron-rich Ar-K isobaric analog state pairs with mass number $A=35-47$ are calculated within the relativistic mean field model and the effects of level inversion on the Coulomb displacement energies of the Ar-K isobaric analog state pairs are studied. The calculations are carried out in two cases, with and without consideration of the possible $2s_{1/2}$ and $1d_{3/2}$ proton level inversion of the neutron-rich Ar isotopes. Results show that the $2s_{1/2}$ and $1d_{3/2}$ level inversion of the neutron-rich Ar isotopes may reduce the Coulomb displacement energy by 0.06$\\sim$0.17 MeV for the Ar-K isobaric analog state pairs. The results may provide a reference for experimental investigations of nuclear level inversion and a new test of the relativistic mean field model.

  16. The 6He Optical Potential at energies around the Coulomb barrier

    International Nuclear Information System (INIS)

    We present an Optical Model (OM) study of 6He on 208Pb elastic scattering data, measured at laboratory energies around the Coulomb barrier (Elab = 14, 16, 18, 22, and 27 MeV)[1]. For the projectile-target bare interaction, we use the microscopic Sao Paulo Potential (SPP). This bare interaction is supplemented with a Coulomb Dipole Polarization (CDP) potential, as well as a diffuse complex Woods-Saxon potential. Four-body Continuum-Discretized-Coupled-Channels (CDCC) calculations have been performed in order to support the optical model analysis. We have also studied the α channel, which is the dominant reaction process. In the analysis of this channel, we compare the angular and energy distributions of the α particles measured at 22 MeV, with Distorted Wave Born Approximation (DWBA) calculations.

  17. The 6He Optical Potential at energies around the Coulomb barrier

    Science.gov (United States)

    Fernández-García, J. P.; Rodríguez-Gallardo, M.; Alvarez, M. A. G.; Moro, A. M.

    2010-04-01

    We present an Optical Model (OM) study of 6He on 208Pb elastic scattering data, measured at laboratory energies around the Coulomb barrier (Elab = 14, 16, 18, 22, and 27 MeV) [1]. For the projectile-target bare interaction, we use the microscopic São Paulo Potential (SPP). This bare interaction is supplemented with a Coulomb Dipole Polarization (CDP) potential, as well as a diffuse complex Woods-Saxon potential. Four-body Continuum-Discretized-Coupled-Channels (CDCC) calculations have been performed in order to support the optical model analysis. We have also studied the α channel, which is the dominant reaction process. In the analysis of this channel, we compare the angular and energy distributions of the α particles measured at 22 MeV, with Distorted Wave Born Approximation (DWBA) calculations.

  18. Eigenvalues of the Schroedinger equation with Coulomb potentials plus linear and harmonic radial terms

    International Nuclear Information System (INIS)

    Analytic approximations for the eigenvalues have been obtained using the two-point quasifractional approximants method. Here we extend and generalize previous work where the method was applied to determine eigenenergies of two-dimensional Coulomb potentials in the presence of a magnetic field of arbitrary strength. We have also shown the advantage of our results with respect to other calculations using the shifted 1/N method or Pade approximants. (author)

  19. Theory of electron-phonon superconductivity: Does retardation really lead to a small Coulomb pseudopotential?

    OpenAIRE

    Bauer, Johannes; Han, Jong E.; Gunnarsson, Olle

    2012-01-01

    The theory of electron-phonon superconductivity depends on retardation drastically reducing effects of the strong Coulomb repulsion. The standard theory only treats the lowest order diagram, which is an uncontrolled approximation. We study retardation in the Hubbard-Holstein model in a controlled way using perturbation theory and dynamical mean-field theory. We calculate analytically second order results for the pseudopotential $\\mu^*$ and demonstrate the validity up to intermediate couplings...

  20. Coulomb Corrections to the Parameters of the Moliere Multiple Scattering Theory

    CERN Document Server

    Kuraev, Eduard; Tarasov, Alexander

    2013-01-01

    High-energy Coulomb corrections to the parameters of the Moliere multiple scattering theory are obtained. Numerical calculations are presented in the range of the nuclear charge number of the target atom 4

  1. The giant-dipole-resonance effect in coulomb excitation of 10B

    International Nuclear Information System (INIS)

    Coulomb excitation of the 0.718-MeV, Jsup(π) = 1+, first excited state of 10B has been studied using projectile excitation by 208Pb and observing the backward scattered particles. The results give a clear indication of the virtual excitation of the giant dipole resonance as a second-order effect. The observed magnitude is consistent with the usual hydrodynamic model estimate and with a recent shell-model calculation

  2. Primakoff production of $\\pi^0$, $\\eta$ and $\\eta'$ in the Coulomb field of a nucleus

    OpenAIRE

    Kaskulov, Murat M.; Mosel, Ulrich

    2011-01-01

    Photoproduction of neutral pseudoscalar mesons $\\pi^0,\\eta(547)$ and $\\eta'(958)$ in the Coulomb field of an atomic nucleus is studied using a model which describes the Primakoff and nuclear parts of the production amplitude. At high energies the nuclear background is dominated by the exchange of $C$-parity odd Regge trajectories. In the coherent production the isospin filtering makes the $\\omega(782)$ a dominant trajectory. The calculations are in agreement with $\\pi^0$ data from JLAB provid...

  3. Coulomb dissociation and momentum distributions for 11Li → 9Li + n + n breakup reactions

    International Nuclear Information System (INIS)

    Momentum distributions for the 11Li → 9Li+n+n breakup reaction, generated by Coulomb dipole excitations, axe calculated in a 3-body model for 11Li. The relative momentum distribution of the two neutrons is in good agreement with recent 3-body coincidence measurements but the momentum distribution for the 9Li recoil and the decay energy spectrum are much narrower than observed. These discrepancies may be due to higher order dynamical effects which have been ignored

  4. J-Matrix approach for the exponential-cosine-screened Coulomb potential

    Energy Technology Data Exchange (ETDEWEB)

    Nasser, I; Abdelmonem, M S [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Abdel-Hady, Afaf, E-mail: msmonem@kfupm.edu.s [Faculty of Engineering, Al-Asher University, Al-Asher City (Egypt)

    2011-10-15

    The bound state energies for the exponential-cosine-screened Coulomb potential were calculated by using the Gauss quadrature method. The resonance energies were calculated using the complex rotation method and were then used as a seed for our J-matrix approach in order to achieve improved results. The calculated bound and resonance state energies are compared with the available numerical data in this paper. The trajectories of the resonance states in the complex E-plane are also shown. New data, for both bound and resonance state energies close to the crossover region of the transition from bound to resonance, have been reported for guiding future studies.

  5. Aspects of the confinement mechanism in Coulomb-gauge QCD

    International Nuclear Information System (INIS)

    Full text: Phenomenological consequences of the infrared singular, instantaneous part of the gluon propagator in Coulomb gauge are investigated. The corresponding quark Dyson-Schwinger equation is solved, neglecting retardation and transverse gluons and regulating the resulting infrared singularities. While the quark propagator vanishes as the infrared regulator goes to zero, the frequency integral over the quark propagator, and thus the quark condensate, stays finite and well-defined. Solutions of the homogeneous Bethe-Salpeter equation for the pseudoscalar and vector mesons as well as for scalar and axial-vector diquarks are obtained. In the limit of a vanishing infrared regulator the diquark masses diverge, while meson properties and diquark radii remain finite and well-defined. These features are interpreted with respect to the resulting aspects of confinement for colored quark-quark correlations. The qualitative features are stable when including transverse gluons. Corresponding preliminary results are presented. (author)

  6. Coulomb interaction effect in tilted Weyl fermion in two dimensions

    Science.gov (United States)

    Isobe, Hiroki; Nagaosa, Naoto

    Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor α-(BEDT-TTF)2I3 and three-dimensional WTe2. The Coulomb interaction between electrons modifies the velocities in an essential way in the low energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted Weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the velocity of light c to result in the Cherenkov radiation. Especially, the system restores the isotropic Weyl cone even when the bare Weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions.

  7. Impact Cratering Calculations

    Science.gov (United States)

    Ahrens, Thomas J.

    2001-01-01

    We examined the von Mises and Mohr-Coulomb strength models with and without damage effects and developed a model for dilatancy. The models and results are given in O'Keefe et al. We found that by incorporating damage into the models that we could in a single integrated impact calculation, starting with the bolide in the atmosphere produce final crater profiles having the major features found in the field measurements. These features included a central uplift, an inner ring, circular terracing and faulting. This was accomplished with undamaged surface strengths of approximately 0.1 GPa and at depth strengths of approximately 1.0 GPa. We modeled the damage in geologic materials using a phenomenological approach, which coupled the Johnson-Cook damage model with the CTH code geologic strength model. The objective here was not to determine the distribution of fragment sizes, but rather to determine the effect of brecciated and comminuted material on the crater evolution, fault production, ejecta distribution, and final crater morphology.

  8. Spherical Calogero model with oscillator/Coulomb potential: quantum case

    CERN Document Server

    Correa, Francisco; Lechtenfeld, Olaf; Nersessian, Armen

    2016-01-01

    We consider the quantum mechanics of Calogero models in an oscillator or Coulomb potential on the N-dimensional sphere. Their Hamiltonians are obtained by an appropriate Dunkl deformation of the oscillator/Coulomb system on the sphere and its restriction to (Coxeter reflection) symmetric wave functions. By the same method we also find the symmetry generators and compute their algebras.

  9. Coulomb interaction between a spherical and a deformed nuclei

    CERN Document Server

    Takigawa, N; Ihara, N; Takigawa, Noboru; Rumin, Tamanna; Ihara, Naoki

    2000-01-01

    We present analytic expressions of the Coulomb interaction between a spherical and a deformed nuclei which are valid for all separation distance. We demonstrate their significant deviations from commonly used formulae in the region inside the Coulomb radius, and show that they remove various shortcomings of the conventional formulae.

  10. Coulomb corrections in the low-energy scattering

    International Nuclear Information System (INIS)

    Renormalization of the coefficients of the ''effective range expansion'' is considered for the short-range Coulomb problem. The exactly solvable model of the Coulomb plus short range potential is considered. Exact solutions are compared with approximations frequently used in the theory of hadronic atoms

  11. Effect of operational parameters on Coulombic efficiency in bioelectrochemical systems

    NARCIS (Netherlands)

    Sleutels, T.H.J.A.; Darus, L.; Hamelers, H.V.M.; Buisman, C.J.N.

    2011-01-01

    To create an efficient bioelectrochemical system, a high Coulombic efficiency is required. This efficiency is a direct measure for the competition between electrogens and methanogens when acetate is used as substrate. In this study the Coulombic efficiency in a microbial electrolysis cell was invest

  12. Correlated Coulomb drag in capacitively coupled quantum-dot structures

    DEFF Research Database (Denmark)

    Kaasbjerg, Kristen; Jauho, Antti-Pekka

    2016-01-01

    We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs) -- a biasdriven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach which accounts for higher-order tunneling (cotunneli...

  13. Antilocalization of Coulomb Blockade in a Ge-Si Nanowire

    DEFF Research Database (Denmark)

    Higginbotham, Andrew P.; Kuemmeth, Ferdinand; Larsen, Thorvald Wadum;

    2014-01-01

    The distribution of Coulomb blockade peak heights as a function of magnetic field is investigated experimentally in a Ge-Si nanowire quantum dot. Strong spin-orbit coupling in this hole-gas system leads to antilocalization of Coulomb blockade peaks, consistent with theory. In particular, the peak...

  14. Short-time dynamics of correlated quantum Coulomb systems

    Science.gov (United States)

    Bonitz, Michael

    2007-03-01

    Strong correlations in dense Coulomb systems are attracting increasing interest in many fields ranging from dense astrophysical plasmas, dusty plasmas and semiconductors to metal clusters and ultracold trapped ions [1]. Examples are bound states in dense plasmas (atoms, molecules, clusters) and semiconductors (excitons, trions, biexcitons) and many-particle correlations such as Coulomb and Yukawa liquids and crystals. Of particular current interest is the response of these systems to short excitations generated e.g. by femtosecond laser pulses and giving rise to ultrafast relaxation processes and build up of binary correlations. The proper theoretical tool are non-Markovian quantum kinetic equations [1,2] which can be derived from Nonequilibrium Green's Functions (NEGF) and are now successfully solved numerically for dense plasmas and semiconductors [3], correlated electrons [4] and other many-body systems with moderate correlations [5]. This method is well suited to compute the nonlinear response to strong fields selfconsistently including many-body effects [6]. Finally, we discuss recent extensions of the NEGF-computations to the dynamics of strongly correlated Coulomb systems, such as single atoms and molecules [7] and electron and exciton Wigner crystals in quantum dots [8,9]. [1] H. Haug and A.-P. Jauho, Quantum Kinetics in Transport and Optics of Semiconductors, Springer 1996; M. Bonitz Quantum Kinetic Theory, Teubner, Stuttgart/Leipzig 1998; [2] Progress in Nonequilibrium Green's Functions III, M. Bonitz and A. Filinov (Eds.), J. Phys. Conf. Ser. vol. 35 (2006); [3] M. Bonitz et al. Journal of Physics: Condensed Matter 8, 6057 (1996); R. Binder, H.S. K"ohler, and M. Bonitz, Phys. Rev. B 55, 5110 (1997); [4] N.H. Kwong, and M. Bonitz, Phys. Rev. Lett. 84, 1768 (2000); [5] Introduction to Computational Methods for Many-Body Systems, M. Bonitz and D. Semkat (eds.), Rinton Press, Princeton (2006); [6] H. Haberland, M. Bonitz, and D. Kremp, Phys. Rev. E 64

  15. Coulomb blockade of spin-dependent shuttling

    Science.gov (United States)

    Park, Hee Chul; Kadigrobov, Anatoli M.; Shekhter, Robert I.; Jonson, M.

    2013-12-01

    We show that nanomechanical shuttling of single electrons may enable qualitatively new functionality if spin-polarized electrons are injected into a nanoelectromechanical single-electron tunneling (NEM-SET) device. This is due to the combined effects of spin-dependent electron tunneling and Coulomb blockade of tunneling, which are phenomena that occur in certain magnetic NEM-SET devices. Two effects are predicted to occur in such structures. The first is a reentrant shuttle instability, by which we mean the sequential appearance, disappearance and again the appearance of a shuttle instability as the driving voltage is increased (or the mechanical dissipation is diminished). The second effect is an enhanced spin polarization of the nanomechanically assisted current flow.

  16. Study on Coulomb explosions of ion mixtures

    CERN Document Server

    Boella, E; D'Angola, A; Coppa, G; Silva, L O

    2015-01-01

    The paper presents a theoretical work on the dynamics of Coulomb explosion for spherical nanoplasmas composed by two different ion species. Particular attention has been dedicated to study the energy spectra of the ions with the larger charge-to-mass ratio. The connection between the formation of shock shells and the energy spread of the ions has been the object of a detailed analysis, showing that under particular conditions the width of the asymptotic energy spectrum tends to become very narrow, which leads to a multi-valued ion phase-space. The conditions to generate a quasi mono-energetic ion spectrum have been rigorously demonstrated and verifed by numerical simulations, using a technique that, exploiting the spherical symmetry of the problem, allows one to obtain very accurate and precise results.

  17. Gauge Theories on the Coulomb branch

    CERN Document Server

    Schwarz, John H

    2014-01-01

    We construct the world-volume action of a probe D3-brane in $AdS_5 \\times S^5$ with $N$ units of flux. It has the field content, symmetries, and dualities of the $U(1)$ factor of ${\\cal N} =4$ $U(N+1)$ super Yang--Mills theory, spontaneously broken to $U(N) \\times U(1)$ by being on the Coulomb branch, with the massive fields integrated out. This motivates the conjecture that it is the exact effective action, called a `highly effective action' (HEA). We construct an $SL(2,Z)$ multiplet of BPS soliton solutions of the D3-brane theory (the conjectured HEA) and show that it reproduces the electrically charged massive states that have been integrated out as well as magnetic monopoles and dyons. Their charges are uniformly spread on a spherical surface, called a `soliton bubble', which is interpreted as a phase boundary.

  18. Relativistic Aharonov endash Bohm endash Coulomb problem

    International Nuclear Information System (INIS)

    The ((2+1)-dimensional) Aharonov endash Bohm effect is analyzed for a spin-1/2 particle in the case that a 1/r potential is present. Scalar and vector couplings are each considered. It is found that the approach in which the flux tube is given a finite radius that is taken to zero only after a matching of boundary conditions does not give physically meaningful results. Specifically, the operations of taking the limit of zero flux tube radius and the Galilean limit do not commute. Thus there appears to be no satisfactory solution of the relativistic Aharonov endash Bohm endash Coulomb problem using the finite radius flux tube method. Copyright copyright 1996 Academic Press, Inc

  19. Coulomb dissociation of light unstable nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Kido, Toshihiko [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Yabana, Kazuhiro; Suzuki, Yoshiyuki

    1997-05-01

    The aim of this study is that a simulation method applicable to the atomic nucleus with neutron halo structure developed till now is applied to a wider range unstable nucleus containing proton excess nucleus to also attribute understanding of nuclear reaction with interest in astronomical nuclear reaction. The proton dissociation energy in {sup 8}B nucleus is small value of 138 eV, which is thought to have a structure of proton at the most outer shell bound much weakly by core nucleus and spread in thinner thickness. For the coulomb excitation of such weak bound system, quantum theoretical and non-perturbational treatment is important. Therefore, 3-dimensional time-dependent Schroedinger equation on relative wave function of the core nucleus {sup 7}Be and halo proton p will be dissolved in time space and will execute a time developmental simulation. (G.K.)

  20. Simplistic Coulomb Forces in Molecular Dynamics

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt; Schrøder, Thomas; Dyre, J. C.

    2012-01-01

    salt model the SF approximation overall reproduces the structural and dynamical properties as accurately as does the Wolf method. It is shown that the optimal Wolf damping parameter depends on the property in focus and that neither the potential energy nor the radial distribution function are useful...... measures for the convergence of the Wolf method to the Ewald summation method. The SF approximation is also tested for the SPC/Fw model of liquid water at room temperature, showing good agreement with both the Wolf and the particle mesh Ewald methods; this confirms previous findings [Fennell, C. J......In this paper we compare the Wolf method to the shifted forces (SF) method for efficient computer simulation of bulk systems with Coulomb forces, taking results from the Ewald summation and particle mesh Ewald methods as representing the true behavior. We find that for the Hansen–McDonald molten...

  1. Range effects of the Coulombic forces on structures, thermodynamic properties and potential energy landscapes: (KCl)32 and related systems

    International Nuclear Information System (INIS)

    Graphical abstract: The caloric curve (T vs. E), heat capacity (C) (per ion), and relative rms fluctuation in the interatomic distances (δ) of the 64-atom binary cluster for three different sets of values of the (γ, B) shielding parameters (0.000, 1.000), (0.350, 5.230), and (0.500, 9.723) (see the text for details). As the range of the Coulomb part of the interaction potential becomes shorter, the energy of the most preferred structure of the cluster decreases, and the structure itself changes from rocksalt cubic, which is the native form of (KCl)32, through an amorphous, to a hollow cage type. The energy segment in which the heat capacity is negative narrows and eventually vanishes. Highlights: ► Effects of the range of Coulombic interactions on structures of binary systems. ► Effects of the range of Coulombic interactions on dynamics of binary systems. ► Effects of the range of Coulombic interactions on energy landscapes. ► We explain changes in structures and dynamics through changes in energy landscapes. - Abstract: By introducing two shielding parameters into the Coulombic part of the Coulomb plus Born–Mayer potential originally developed for (KCl)n systems, we study the effects of the range of the Coulombic interactions on the structures, thermodynamic properties and the potential energy landscapes of binary ionically bonded systems as illustrated by the case of n = 32. Our calculations show that shortening of the Coulomb interaction range leads to a decrease in the energy of the most stable structure, and the structure itself changes from the rocksalt cubic to a hollow cage type. The energy range, in which the heat capacity exhibits a negative value, gradually narrows and eventually disappears. The number of stationary points on the potential energy surface increases, and their energies get spread over a larger interval. The extent of the Coulombic interaction also affects the energy difference (gap) between the most stable structure and the

  2. Many-Body Coulomb Gauge Exotic and Charmed Hybrids

    CERN Document Server

    Llanes-Estrada, F J; Llanes-Estrada, Felipe J.; Cotanch, Stephen R.

    2001-01-01

    Utilizing a QCD Coulomb gauge Hamiltonian with linear confinement specified by lattice, we report a relativistic many-body calculation for the light exotic and charmed hybrid mesons. The Hamiltonian successfully describes both quark and gluon sectors, with vacuum and quasiparticle properties generated by a BCS transformation and more elaborate TDA and RPA diagonalizations for the meson ($q\\bar{q}$) and glueball ($gg$) masses. Hybrids entail a computationally intense relativistic three quasiparticle ($q\\bar{q}g$) calculation with the 9 dimensional Hamiltonian matrix elements evaluated variationally by Monte Carlo techniques. Our new TDA spectrum for the nonexotic $1^{--}$ charmed ($c\\bar{c}$ and $c\\bar{c}g$) system provides an explanation for the overpopulation of the observed $J/\\psi$ states. For the important $1^{-+}$ light exotic channel we obtain hybrid masses above 2 $GeV$, in broad agreement with lattice and flux tube models, indicating that the recently observed resonances at 1.4 and 1.6 $GeV$ are of di...

  3. Coulomb excitation effects on alpha-particle optical potential below the Coulomb barrier

    CERN Document Server

    Avrigeanu, V; Mănăilescu, C

    2016-01-01

    A competition of the low-energy Coulomb excitation (CE) with the compound nucleus (CN) formation in alpha-induced reactions below the Coulomb barrier has recently been assumed in order to make possible the description of the latter as well as the alpha-particle emission by the same optical model (OM) potential. On the contrary, we show in the present work that the corresponding partial waves and integration radii provide evidence for the distinct account of the CE cross section and OM total-reaction cross section $\\sigma_R$. Thus the largest contribution to CE cross section comes by far from partial waves larger than the ones contributing to the $\\sigma_R$ values.

  4. The Coulomb potential in quantum mechanics and related topics

    International Nuclear Information System (INIS)

    This dissertation consists of an analytic study of the Coulomb interaction in nonrelativistic quantum mechanics and some related topics. The author investigates in a number of self-contained articles various interesting and important properties of the Coulomb potential. Some of these properties are shared by other potentials which also play a role in quantum mechanics. For such related interactions a comparative study is made. The principal difficulties in the description of proton-deuteron scattering and break-up reactions, due to the Coulomb interaction, are studied by working out a simple model. The bound states are studied for the Coulomb plus Yamaguchi potential, for the symmetric shifted Coulomb potential, and for local potentials with an inverse-distance-squared asymptotic behaviour. (Auth.)

  5. Heat-kernel expansion and counterterms of the Faddeev-Popov determinant in Coulomb and Landau gauge

    International Nuclear Information System (INIS)

    The Faddeev-Popov determinant of Landau gauge in d dimensions and Coulomb gauge in d+1 dimensions is calculated in the heat-kernel expansion up to next-to-leading order. The UV-divergent parts in d=3,4 are isolated and the counterterms required for a non-perturbative treatment of the Faddeev-Popov determinant are determined. (orig.)

  6. Cold transfer between deformed, Coulomb excited nuclei; Kalter Transfer zwischen deformierten, Coulomb-angeregten Kernen

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, H.

    1998-12-31

    The scattering system {sup 162}Dy {yields} {sup 116}Sn has been examined at energies in the vicinity of the Coulomb barrier using the Heidelberg-Darmstadt Crystal Ball spectrometer combined with 5 Germanium-CLUSTER detectors. In order to study pairing correlations as a function of angular momentum cold events were selected in the 2n stripping channel by identifying and suppressing the dominant hot part of the transfer with the Crystal Ball. The CLUSTER detectors with their high {gamma}-efficiency were used to identify the transfer channel and to resolve individual final states. Cross sections for the population of individual yrast states in a cold transfer reaction have been measured for the first time indicating the strong influence of higher transfer multipolarities. At small surface distances Coulomb-nuclear interferences were found to be responsible for the stronger decline of the population of higher yrast states in the transfer channel as compared to the Coulex channel. As a preparatory study for 2n transfer measurements between high spin yrast states in the backbending region of deformed nuclei the Coulomb excitation process in the crossing region of two bands in {sup 162}Dy has been analyzed. The gross properties of the measured population probabilities could be interpreted in a simple band mixing model. (orig.)

  7. Semiclassical Green's function for electron motion in combined Coulomb and electric fields

    Science.gov (United States)

    Ambalampitiya, Harindranath; Fabrikant, Ilya

    2016-05-01

    We are developing an extension of the Green-function approach to the theory of ionization of a multielectron atom in a strong laser field by using the semiclassical Van Vleck-Gutzwiller propagator. For a static field the exact quantum mechanical Green's function can be calculated with an arbitrary accuracy. Therefore, as a first step towards solution of the problem, we apply the semiclassical method to the static field case for the energies above the ionization threshold where all classical trajectories contributing to the Green's function are real. Required trajectories are determined by solving the problem of finding initial velocity and traveling time corresponding to two position points. For the pure electric field case of two trajectories the semiclassical Green's function agrees very well with the exact Green's function. With the inclusion of the Coulomb field, the number of classical trajectories between two points grows rapidly and here we observe that the agreement between the semiclassical and exact Green's functions increases when more trajectories are included in the computation. Supported by the National Science Foundation.

  8. Numerical path integral solution to strong Coulomb correlation in one dimensional Hooke's atom

    CERN Document Server

    Ruokosenmäki, Ilkka; Kylänpää, Ilkka; Rantala, Tapio T

    2015-01-01

    We present a new approach based on real time domain Feynman path integrals (RTPI) for electronic structure calculations and quantum dynamics, which includes correlations between particles exactly but within the numerical accuracy. We demonstrate that incoherent propagation by keeping the wave function real is a novel method for finding and simulation of the ground state, similar to Diffusion Monte Carlo (DMC) method, but introducing new useful tools lacking in DMC. We use 1D Hooke's atom, a two-electron system with very strong correlation, as our test case, which we solve with incoherent RTPI (iRTPI) and compare against DMC. This system provides an excellent test case due to exact solutions for some confinements and because in 1D the Coulomb singularity is stronger than in two or three dimensional space. The use of Monte Carlo grid is shown to be efficient for which we determine useful numerical parameters. Furthermore, we discuss another novel approach achieved by combining the strengths of iRTPI and DMC. We...

  9. Study of the elastic scattering of 6He on 208Pb at energies around the Coulomb barrier

    International Nuclear Information System (INIS)

    The elastic scattering of 6He on 208Pb has been measured at laboratory energies of 14, 16, 18 and 22 MeV. These data were analyzed using phenomenological Woods-Saxon form factors and optical model calculations. A semiclassical polarization potential was used to study the effect of the Coulomb dipole polarizability. Evidence for long range absorption, partially arising from Coulomb dipole polarizability, is reported. The energy variation of the optical potential was found to be consistent with the dispersion relations which connect the real and imaginary parts of the potential

  10. Coulomb blockade model of permeation and selectivity in biological ion channels

    Science.gov (United States)

    Kaufman, I. Kh; McClintock, P. V. E.; Eisenberg, R. S.

    2015-08-01

    Biological ion channels are protein nanotubes embedded in, and passing through, the bilipid membranes of cells. Physiologically, they are of crucial importance in that they allow ions to pass into and out of cells, fast and efficiently, though in a highly selective way. Here we show that the conduction and selectivity of calcium/sodium ion channels can be described in terms of ionic Coulomb blockade in a simplified electrostatic and Brownian dynamics model of the channel. The Coulomb blockade phenomenon arises from the discreteness of electrical charge, the strong electrostatic interaction, and an electrostatic exclusion principle. The model predicts a periodic pattern of Ca2+ conduction versus the fixed charge Qf at the selectivity filter (conduction bands) with a period equal to the ionic charge. It thus provides provisional explanations of some observed and modelled conduction and valence selectivity phenomena, including the anomalous mole fraction effect and the calcium conduction bands. Ionic Coulomb blockade and resonant conduction are similar to electronic Coulomb blockade and resonant tunnelling in quantum dots. The same considerations may also be applicable to other kinds of channel, as well as to charged artificial nanopores.

  11. Analysis of uncertainties in alpha-particle optical-potential assessment below the Coulomb barrier

    CERN Document Server

    Avrigeanu, V

    2016-01-01

    Background: Recent high-precision measurements of alpha-induced reaction data below the Coulomb barrier have pointed out questions of the alpha-particle optical-model potential (OMP) which are yet open within various mass ranges. Purpose: The applicability of a previous optical potential and eventual uncertainties and/or systematic errors of the OMP assessment at low energies can be further considered on this basis. Method: Nuclear model parameters based on the analysis of recent independent data, particularly gamma-ray strength functions, have been involved within statistical model calculation of the (alpha,x) reaction cross sections. Results: The above-mentioned potential provides a consistent description of the recent alpha-induced reaction data with no empirical rescaling factors of the and/or nucleon widths. Conclusions: A suitable assessment of alpha-particle optical potential below the Coulomb barrier should involve the statistical-model parameters beyond this potential on the basis of a former analysi...

  12. On the Aharonov-Casher system subject to a Coulomb-type potential

    Science.gov (United States)

    Barboza, P. M. T.; Bakke, K.

    2016-02-01

    By considering the confinement of the Aharonov-Casher system to a Coulomb-type potential, we show that the energy levels depends on the Aharonov-Casher geometric phase and obtain the persistent spin currents. Besides, we investigate the influence of the Coulomb-type potential on the Landau-Aharonov-Casher system by showing that bound states solutions to the Schrödinger-Pauli equation can be obtained. We show that the Landau-Aharonov-Casher cyclotron frequency is modified and discuss a quantum characterized by the dependence of the angular frequency on the quantum numbers of the system. As a particular case, we calculate the possible values of the angular frequency associated with the ground state.

  13. Determining astrophysical three-body radiative capture reaction rates from inclusive Coulomb break-up measurements

    Science.gov (United States)

    Casal, J.; Rodríguez-Gallardo, M.; Arias, J. M.; Gómez-Camacho, J.

    2016-04-01

    A relationship between the Coulomb inclusive break-up probability and the radiative capture reaction rate for weakly bound three-body systems is established. This direct link provides a robust procedure to estimate the reaction rate for nuclei of astrophysical interest by measuring inclusive break-up processes at different energies and angles. This might be an advantageous alternative to the determination of reaction rates from the measurement of B (E 1 ) distributions through exclusive Coulomb break-up experiments. In addition, it provides a reference to assess the validity of different theoretical approaches that have been used to calculate reaction rates. The procedure is applied to 11Li (9Li+n +n ) and 6He (4He+n +n ) three-body systems for which some data exist.

  14. Determining astrophysical three-body radiative capture reaction rates from inclusive Coulomb break-up measurements

    CERN Document Server

    Casal, J; Arias, J M; Gómez-Camacho, J

    2016-01-01

    A relationship between the Coulomb inclusive break-up probability and the radiative capture reaction rate for weakly-bound three-body systems is established. This direct link provides a robust procedure to estimate the reaction rate for nuclei of astrophysical interest by measuring inclusive break-up processes at different energies and angles. This might be an advantageous alternative to the determination of reaction rates from the measurement of $B(E1)$ distributions through exclusive Coulomb break-up experiments. In addition, it provides a reference to assess the validity of different theoretical approaches that have been used to calculate reaction rates. The procedure is applied to $^{11}$Li ($^{9}$Li+n+n) and $^6$He ($^{4}$He+n+n) three-body systems for which some data exist.

  15. Thickness effects on the Coulomb drag rate in double quantum layer systems

    Science.gov (United States)

    Vazifehshenas, T.; Eskourchi, A.

    2007-02-01

    In this paper, we have investigated the effect of quantum layer thickness on Coulomb drag phenomenon in a double quantum well (DQW) system, in which the electrons momentum can transfer from one layer to another. We have applied the full random phase approximation (RPA) in dynamical dielectric matrix of this coupled two-dimensional electron gas (2DEG) system in order to obtain an improved result for temperature-dependent rate of momentum transfer. We have calculated the drag rate transresistivity for various well thicknesses at low and intermediate temperatures in Fermi-scale and for different electron gas densities. It has been obtained that the Coulomb drag rate increases with increasing the well width when the separation between the wells remains unchanged.

  16. Exact solution to the Coulomb wave using the linearized phase-amplitude method

    Directory of Open Access Journals (Sweden)

    Shuji Kiyokawa

    2015-08-01

    Full Text Available The author shows that the amplitude equation from the phase-amplitude method of calculating continuum wave functions can be linearized into a 3rd-order differential equation. Using this linearized equation, in the case of the Coulomb potential, the author also shows that the amplitude function has an analytically exact solution represented by means of an irregular confluent hypergeometric function. Furthermore, it is shown that the exact solution for the Coulomb potential reproduces the wave function for free space expressed by the spherical Bessel function. The amplitude equation for the large component of the Dirac spinor is also shown to be the linearized 3rd-order differential equation.

  17. Coulomb excitation of the two proton-hole nucleus $^{206}$Hg

    CERN Multimedia

    We propose to use Coulomb excitation of the single magic two-proton-hole nucleus $^{206}$Hg. In a single-step excitation both the first 2$^{+}$ and the highly collective octupole 3$^{-}$ states will be populated. Thus, information on both quadrupole and octupole collectivity will be gained in this neutron-rich nucleus. Due to the high beam intensity, we will be able to observe multi-step Coulomb excitation as well, providing further test on theoretical calculations. The results will be used to improve the predictive power of the shell model for more exotic nuclei as we move to lighter N=126 nuclei. The experiment will use the new HIE-ISOLDE facility and the MINIBALL array, and will take advantage of the recently developed $^{206}$Hg beam from the molten lead target.

  18. Vacuum polarization of planar charged fermions with Coulomb and Aharonov-Bohm potentials

    Science.gov (United States)

    Khalilov, V. R.; Mamsurov, I. V.

    2016-02-01

    Vacuum polarization of charged massless fermions is investigated in the superposition of Coulomb and Aharonov-Bohm (AB) potentials in 2 + 1 dimensions. For this purpose, we construct the Green function of the two-dimensional Dirac equation with Coulomb and AB potentials (via the regular and irregular solutions of the radial Dirac equation) and then calculate the vacuum polarization charge density in the so-called subcritical and supercritical regimes. In the supercritical regime, the Green function has a discontinuity in the complex plane of “energy” due to the singularities on the negative energy axis; these singularities are situated on the unphysical sheet and related to the creation of infinitely many quasistationary fermionic states with negative energies. We expect that our results will be helpful in gaining deeper understanding of the fundamental problem of quantum electrodynamics which can be applied to the problems of charged impurity screening in graphene taking into consideration the electron spin.

  19. Hamiltonian approach to QCD in Coulomb gauge: From the vacuum to finite temperatures

    CERN Document Server

    Reinhardt, H; Heffner, J; Quandt, M; Vastag, P

    2015-01-01

    The variational Hamiltonian approach to QCD in Coulomb gauge is reviewed and the essential results obtained in recent years are summarized. First the results for the vacuum sector are discussed, with a special emphasis on the mechansim of confinement and chiral symmetry breaking. Then the deconfinement phase transition is described by introducing temperature in the Hamiltonian approach via compactification of one spatial dimension. The effective action for the Polyakov loop is calculated and the order of the phase transition as well as the critical temperatures are obtained for the color group SU(2) and SU(3). In both cases, our predictions are in good agreement with lattice calculations.

  20. Scalar-QED {Dirac_h}-corrections to the Coulomb potential

    Energy Technology Data Exchange (ETDEWEB)

    Helayel-Neto, J.A. [Centro Brasileiro de Pesquisas Fisica (CBPF), Rio de Janeiro, RJ (Brazil). E-mail: helayel@cbpf.br; Penna-Firme, A.B. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Faculdade de Educacao. E-mail: andrepf@cbpf.br; Shapiro, I.L. [Juiz de Fora Univ., MG (Brazil). Dept. de Fisica. E-mail: shapiro@fisica.ufjf.br

    2000-05-01

    The leading long-distance 1-loop quantum corrections to the Coulomb potential are derived for scalar QED and their gauge-independence is explicitly checked. The potential is obtained from the direct calculation of the 2-particle scattering amplitude, taking into account all relevant 1-loop diagrams. Our investigation should be regarded as first step towards the same programme for effective Quantum Gravity. In particular, with our calculation in the framework of scalar QED, we are able to demonstrate the incompleteness of some previous studies concerning the quantum Gravity counterpart. (author)

  1. Coulomb versus nuclear break-up of 11Be halo nucleus in a non perturbative framework

    CERN Document Server

    Fallot, M; Lacroix, D; Chomaz, P; Margueron, J; Chomaz, Ph.

    2002-01-01

    The 11Be break-up is calculated using a non perturbative time-dependent quantum calculation. The evolution of the neutron halo wave function shows an emission of neutron at large angles for grazing impact parameters and at forward angles for large impact parameters. The neutron angular distribution is deduced for the different targets and compared to experimental data. We emphasize the diversity of diffraction mechanisms, in particular we discuss the interplay of the nuclear effects such as the towing mode and the Coulomb break-up. A good agreement is found with experimental data.

  2. Modeling the self-similarity in complex networks based on Coulomb's law

    Science.gov (United States)

    Zhang, Haixin; Wei, Daijun; Hu, Yong; Lan, Xin; Deng, Yong

    2016-06-01

    Recently, self-similarity of complex networks have attracted much attention. Fractal dimension of complex network is an open issue. Hub repulsion plays an important role in fractal topologies. This paper models the repulsion among the nodes in the complex networks in calculation of the fractal dimension of the networks. Coulomb's law is adopted to represent the repulse between two nodes of the network quantitatively. A new method to calculate the fractal dimension of complex networks is proposed. The Sierpinski triangle network and some real complex networks are investigated. The results are illustrated to show that the new model of self-similarity of complex networks is reasonable and efficient.

  3. Self-consistent inclusion of classical large-angle Coulomb collisions in plasma Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Turrell, A.E., E-mail: a.turrell09@imperial.ac.uk; Sherlock, M.; Rose, S.J.

    2015-10-15

    Large-angle Coulomb collisions allow for the exchange of a significant proportion of the energy of a particle in a single collision, but are not included in models of plasmas based on fluids, the Vlasov–Fokker–Planck equation, or currently available plasma Monte Carlo techniques. Their unique effects include the creation of fast ‘knock-on’ ions, which may be more likely to undergo certain reactions, and distortions to ion distribution functions relative to what is predicted by small-angle collision only theories. We present a computational method which uses Monte Carlo techniques to include the effects of large-angle Coulomb collisions in plasmas and which self-consistently evolves distribution functions according to the creation of knock-on ions of any generation. The method is used to demonstrate ion distribution function distortions in an inertial confinement fusion (ICF) relevant scenario of the slowing of fusion products.

  4. Self-consistent inclusion of classical large-angle Coulomb collisions in plasma Monte Carlo simulations

    International Nuclear Information System (INIS)

    Large-angle Coulomb collisions allow for the exchange of a significant proportion of the energy of a particle in a single collision, but are not included in models of plasmas based on fluids, the Vlasov–Fokker–Planck equation, or currently available plasma Monte Carlo techniques. Their unique effects include the creation of fast ‘knock-on’ ions, which may be more likely to undergo certain reactions, and distortions to ion distribution functions relative to what is predicted by small-angle collision only theories. We present a computational method which uses Monte Carlo techniques to include the effects of large-angle Coulomb collisions in plasmas and which self-consistently evolves distribution functions according to the creation of knock-on ions of any generation. The method is used to demonstrate ion distribution function distortions in an inertial confinement fusion (ICF) relevant scenario of the slowing of fusion products

  5. Molecular dynamics calculations for sodium using pseudopotential theory

    International Nuclear Information System (INIS)

    The equation of state of sodium is studied using the molecular dynamics technique whereby the classical motion of a system of ions is solved with the aid of computers. The interaction potential between pairs of sodium ions consists of Coulomb and Born-Mayer repulsion terms and an effective ion-ion interaction derived from pseudopotential theory. This theory includes the effects of electron gas screening, exchange, and correlation. A model pseudopotential with parameters fit to experimental low-temperature data is used. By using this technique, an atomic description of a simple metal proceeds to the calculation of macroscopic thermodynamic properties

  6. Non-Perturbative Relativistic Calculation of the Muonic Hydrogen Spectrum

    OpenAIRE

    Carroll, J D; Thomas, A. W.; Rafelski, J.; Miller, G A

    2011-01-01

    We investigate the muonic hydrogen 2P^{F=2}_{3/2} to 2S^{F=1}_{1/2} transition through a precise, non-perturbative numerical solution of the Dirac equation including the finite-size Coulomb force and finite size vacuum polarization. The results are compared with earlier perturbative calculations of (primarily) Borie, Martynenko, and Pachucki; and experimental results recently presented by Pohl et al., in which this very comparison is interpreted as requiring a modification of the proton charg...

  7. Characterizing intra-exciton Coulomb scattering in terahertz excitations

    International Nuclear Information System (INIS)

    An intense terahertz field is applied to excite semiconductor quantum wells yielding strong non-equilibrium exciton distributions. Even though the relaxation channels involve a complicated quantum kinetics of Coulomb and phonon effects, distinct relaxation signatures of Coulomb scattering are identified within time-resolved photoluminescence by comparing the experiment with a reduced model that contains all relevant microscopic processes. The analysis uncovers a unique time scale for the Coulomb scattering directly from experiments and reveals the influence of phonon relaxation as well as radiative decay

  8. On Coulomb disintegration of relativistic nuclei and hypernuclei

    International Nuclear Information System (INIS)

    The dependence of the total cross-section of excitation and disintegration of a relativistic nucleus in the Coulomb field on the energy and parameters characterizing nuclear dimensions is investigated. The analogy with the problem of atomic ionization at the passage of charged particles through matter is used. The results are applied to the description of the Coulomb dissociation of nuclei with small binding energies. An explicit expression for the effective cross-section of the Coulomb disintegration of the hypernucleus-Λ3H into a deuteron and Λ-particle. 12 refs

  9. Positron scattering from hydrogen atom with screened Coulomb potentials

    International Nuclear Information System (INIS)

    Elastic positron-hydrogen collisions with screened Coulomb potentials have been investigated using a second-order distorted wave Born approximation in the momentum space. Two types of potentials have been considered, namely, static screened Coulomb potential and exponential cosine-screened Coulomb potential. Using a simple variationally determined hydrogenic wave function it has been possible to obtain the scattering amplitude in a closed form. A detailed study has been made on the differential and total cross sections in the energy range 20–300 eV

  10. Accelerated Monte Carlo Methods for Coulomb Collisions

    Science.gov (United States)

    Rosin, Mark; Ricketson, Lee; Dimits, Andris; Caflisch, Russel; Cohen, Bruce

    2014-03-01

    We present a new highly efficient multi-level Monte Carlo (MLMC) simulation algorithm for Coulomb collisions in a plasma. The scheme, initially developed and used successfully for applications in financial mathematics, is applied here to kinetic plasmas for the first time. The method is based on a Langevin treatment of the Landau-Fokker-Planck equation and has a rich history derived from the works of Einstein and Chandrasekhar. The MLMC scheme successfully reduces the computational cost of achieving an RMS error ɛ in the numerical solution to collisional plasma problems from (ɛ-3) - for the standard state-of-the-art Langevin and binary collision algorithms - to a theoretically optimal (ɛ-2) scaling, when used in conjunction with an underlying Milstein discretization to the Langevin equation. In the test case presented here, the method accelerates simulations by factors of up to 100. We summarize the scheme, present some tricks for improving its efficiency yet further, and discuss the method's range of applicability. Work performed for US DOE by LLNL under contract DE-AC52- 07NA27344 and by UCLA under grant DE-FG02-05ER25710.

  11. Electron attraction mediated by Coulomb repulsion

    Science.gov (United States)

    Hamo, A.; Benyamini, A.; Shapir, I.; Khivrich, I.; Waissman, J.; Kaasbjerg, K.; Oreg, Y.; von Oppen, F.; Ilani, S.

    2016-07-01

    One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed ‘excitonic’, promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the ‘glue’ that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter.

  12. Monopole defects and magnetic Coulomb blockade

    International Nuclear Information System (INIS)

    Magnetic monopoles, predicted by Dirac, entered a new paradigm with the discovery of emergent monopoles within dipole lattices known as bulk and artificial spin ices. The observation of monopoles in certain artificial systems, and their absence from other similar structures, is a significant puzzle. Connected artificial spin-ice structures attract much attention in terms of the possibility to read states electrically, and offer the possibility of monopole defect control via well-understood domain wall processes. Nevertheless, full comprehension of the underlying processes is lacking. Here, we establish one of the overriding components. We demonstrate using high-resolution scanning transmission x-ray microscopy (STXM) the cooperative process associated with two transverse domain walls that creates the monopole defect in NiFe. The feature size of the array is large compared to the exchange length in the ferromagnet, and the two transverse domain walls give a rich internal structure to the monopole defect vertex. The magnetic Coulomb repulsion between two domain walls carrying the same sign of magnetic charge stabilizes the monopole defects at fields greater than the depinning field for a single wall at that vertex. These observations allow us to form an overview of monopole defect control possibilities from extrinsic pinning as in Co arrays (the extreme extrinsic limit being isolated bar structures) to intrinsic pinning captured here.

  13. Dark Coulomb binding of heavy neutrinos of fourth family

    Science.gov (United States)

    Belotsky, K. M.; Esipova, E. A.; Khlopov, M. Yu.; Laletin, M. N.

    2015-11-01

    Direct dark matter searches put severe constraints on the weakly interacting massive particles (WIMPs). These constraints cause serious troubles for the model of stable neutrino of fourth generation with mass around 50GeV. Though the calculations of primordial abundance of these particles make them in the charge symmetric case a sparse subdominant component of the modern dark matter, their presence in the universe would exceed the current upper limits by several orders of the magnitude. However, if quarks and leptons of fourth generation possess their own Coulomb-like y-interaction, recombination of pairs of heavy neutrinos and antineutrinos and their annihilation in the “neutrinium” atoms can play important role in their cosmological evolution, reducing their modern abundance far below the experimental upper limits. The model of stable fourth generation assumes that the dominant part of dark matter is explained by excessive Ū antiquarks, forming (ŪŪŪ)-- charged clusters, bound with primordial helium in nuclear-interacting O-helium (OHe) dark atoms. The y charge conservation implies generation of the same excess of fourth generation neutrinos, potentially dangerous WIMP component of this scenario. We show that due to y-interaction recombination of fourth neutrinos with OHe hides these WIMPs from direct WIMP searches, leaving the negligible fraction of free neutrinos, what makes their existence compatible with the experimental constraints.

  14. Scattering of 11Be around the Coulomb barrier

    International Nuclear Information System (INIS)

    The 11Be is a halo nucleus composed of a 10Be core and a weakly bound neutron. Due to its loosely bound structure, the coupling of the ground and exited states to the continuum should strongly affect the elastic cross sections at energies around the Coulomb barrier [1, 2]. Another important issue is the role played by the highly deformed 10Be core on the scattering cross sections [3]. Accurate data on 11Be scattering are needed to study these effects. However, existing data for 11Be + 209Bi scattering [4, 5], suffer of large experimental uncertainties, and elastic and other reaction channels could not be studied separately. Aiming to improve the experimental situation we have recently performed measurements of 11Be scattered on 120Sn at 32 MeV (Lab) at the REX-ISOLDE facility at CERN (Geneva), covering a wide angular range. In this work, we present preliminary results of the experiment for the 11Be+120Sn quasi-elastic scattering as well as for the 11Be→ 10Be + n breakup. The accuracy and angular range of the presented results provide stronger constrains to the theoretical interpretation than existing published results. We compare the experimental results with CDCC and DWBA calculations performed as in references [6-8] for the 6He + 208Pb system. The role played by transfer and breakup channels in the elastic scattering is discussed.(author)

  15. Hyperspherical calculations for four-nucleon systems

    International Nuclear Information System (INIS)

    We develop hyperspherical calculations on the bound states of four-nucleon systems and particularly the fundamental level and the first 0+ excited states. With neglect of the Coulomb effect, we analyze the convergence of the optimal subset expansion for the binding energies calculated for central or realistic potentials. 35 refs

  16. Capture cross-section and rate of the 14C(, )15C reaction from the Coulomb dissociation of 15C

    Indian Academy of Sciences (India)

    Shubhchintak; Neelam; R Chatterjee

    2014-10-01

    We calculate the Coulomb dissociation of 15C on a Pb target at 68 MeV/u incident beam energy within the fully quantum mechanical distorted wave Born approximation formalism of breakup reactions. The capture cross-section and the subsequent rate of the 14C(, )15C reaction are calculated from the photodisintegration of 15C, using the principle of detailed balance. Our theoretical model is free from the uncertainties associated with the multipole strength distributions of the projectile.

  17. Structure effects in the 15N(n ,γ )16N radiative capture reaction from the Coulomb dissociation of 16N

    Science.gov (United States)

    Neelam, Shubhchintak, Chatterjee, R.

    2015-10-01

    Background: The 15N(n ,γ )16N reaction plays an important role in red giant stars and also in inhomogeneous big bang nucleosynthesis. However, there are controversies regarding spectroscopic factors of the four low-lying states of 16N, which have direct bearing on the total direct capture cross section and also on the reaction rate. Direct measurements of the capture cross section at low energies are scarce and available only at three energies below 500 keV. Purpose: The aim of this paper is to calculate the 15N(n ,γ )16N radiative capture cross section and its subsequent reaction rate by an indirect method and in that process investigate the effects of spectroscopic factors of different levels of 16N to the cross section. Method: A fully quantum mechanical Coulomb breakup theory under the aegis of post-form distorted wave Born approximation is used to calculate the Coulomb breakup of 16N on Pb at 100 MeV/u . This is then related to the photodisintegration cross section of 16N(γ ,n )15N and subsequently invoking the principle of detailed balance, the 15N(n ,γ )16N capture cross section is calculated. Results: The nonresonant capture cross section is calculated with spectroscopic factors from the shell model and those extracted (including uncertainties) from two recent experiments. The data seem to favor a more single particle nature for the low-lying states of 16N. The total neutron capture rate is also calculated by summing up nonresonant and resonant (significant only at temperatures greater than 1 GK) contributions and comparison is made with other charged particle capture rates. In the typical temperature range of 0.1 -1.2 GK, almost all the contributions to the reaction rate come from capture cross sections below 0.25 MeV. Conclusion: We have attempted to resolve the discrepancy in the spectroscopic factors of low-lying 16N levels and conclude that it would certainly be useful to perform a Coulomb dissociation experiment to find the low energy capture

  18. The calibration of sub-Coulomb heavy ion proton transfer reactions

    International Nuclear Information System (INIS)

    Measurements were made of the cross sections for the 27Al(16O,15N)28Si, 89Y(15N,16O)88Sr and 89Y(27Al,28Si)88Sr reactions at energies near and below the Coulomb barrier. The first reaction required separate measurements of the transfer to elastic cross section ratio for particular charge states, the charge state distribution for 27Al and 28Si ions, and the absolute elastic scattering cross section for the 27Al + 16O system. The ratio measurement required the combined use of two relatively new scientific instruments: the momentum filter and the Bragg curve spectrometer. The latter two transfer measurements were performed using the same setup involving surface barrier detectors at backward angles. Additional elastic scattering data for the 15N + 28Si, 89Y + 15N, 89Sr + 27Al, and 88Sr + 28Si systems was collected to provide entrance and exit channel parameters needed for the theoretical calculations of the transfer reaction cross sections. The calculations were made using the DWBA code, LOLA, which assumes a one-step direct reaction mechanism. A correction was made to the code to properly include the effects of the spin-orbit force in the proton binding potentials. The original goal of these measurements was to combine the three normalization factors to determine the ground state proton spectroscopic factors for 16O, 28Si and 89Y. Such an analysis was found to yield a spectroscopic factor which significantly exceeded the shell model limit in the case of 16O. It is possible that the inclusion of multi-step processes may resolve this disagreement. 36 refs., 109 figs., 21 tabs

  19. Fano effect through parallel-coupled double Coulomb islands

    International Nuclear Information System (INIS)

    By means of the nonequilibrium Green function and equation of motion method, the electronic transport is theoretically studied through a parallel-coupled double quantum dot (DQD) in the presence of on-dot Coulomb interaction U. With focus on the quantum interference in the U-dominant parallel-coupled DQD, we find two types of Fano interferences in the conductance spectra. If the one-particle DQD bonding and antibonding bands are well separated from their Coulomb blockade counterparts, the main features of Fano interference in usual DQD systems are recovered with minor revisions. The most interesting is the hybridization between the antibonding state and the Coulomb counterpart of the bonding state, which gives rises to two new channels for Fano resonance. The Fano interference in the Coulomb hybridized systems can be controlled by the electrostatic and magnetic approaches, and exhibits properties quite different from what are reported in the noninteracting Fano-Anderson model

  20. Correlated Coulomb Drag in Capacitively Coupled Quantum-Dot Structures

    Science.gov (United States)

    Kaasbjerg, Kristen; Jauho, Antti-Pekka

    2016-05-01

    We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs)—a bias-driven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach that accounts for higher-order tunneling (cotunneling) processes as well as energy-dependent lead couplings, and identify a mesoscopic Coulomb drag mechanism driven by nonlocal multielectron cotunneling processes. Our theory establishes the conditions for a nonzero drag as well as the direction of the drag current in terms of microscopic system parameters. Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments on Coulomb drag in CQD systems.

  1. COULOMB BLOCKADE OSCILLATIONS OF Si SINGLE-ELECTRON TRANSISTORS

    Institute of Scientific and Technical Information of China (English)

    王太宏; 李宏伟; 周均铭

    2001-01-01

    Coulomb blockade oscillations of Si single-electron transistors, which are fabricated completely by the conventional photolithography technique, have been investigated. Most of the single-electron transistors clearly show Coulomb blockade oscillations and these oscillations can be periodic by applying negative voltages to the in-plane gates. A shift of the peak positions is observed at high temperatures. It is also found that the fluctuation of the peak spacing cannot be neglected.

  2. Primakoff effect: synchrotron and coulomb mechanisms of axion emission

    International Nuclear Information System (INIS)

    For the first time the axion radiative emission by alternating electromagnetic field Fa → γa is considered due to Primakoff effect. As a concrete supplement, the synchrotron and Coulomb mechanisms are discussed and in the last case the alternating field is formed at the infinite motion of a charge in a Coulomb center field. The estimates for contributions of these effects into axion luminosity of magnetic neutron stars and the Sun are determined

  3. Primakoff effect: Synchrotron and Coulomb mechanisms of axion emission

    International Nuclear Information System (INIS)

    The Primakoff effect-induced radiative emission of axions by an alternating electromagnetic field, Fa → γa, is considered for the first time. The synchrotron mechanism and the Coulomb mechanism--in the latter case, the alternating field is formed when a charge executes an infinite motion in the field of a Coulomb center--are considered as specific examples. The contributions of these effects to the axion emissivity of magnetic neutron stars and of the Sun are estimated

  4. Charged colloids, polyelectrolytes and biomolecules viewed as strongly coupled Coulomb systems

    CERN Document Server

    Löwen, H; Likos, C N; Blaak, R; Dzubiella, J; Jusufi, A; Hoffmann, N; Harreis, H M

    2003-01-01

    A brief review is given on recent studies of charged soft matter solutions, as modelled by the 'primitive' approach of strongly coupled Coulomb systems, where the solvent just enters as a dielectric background. These include charged colloids, biological macromolecules such as proteins and DNA, polyelectrolytes and polyelectrolyte stars. Also some original results are presented on colloid-polyelectrolyte complex formation near walls and on the anomalous fluid structure of polyelectrolyte stars as a function of increasing concentration.

  5. Charged colloids, polyelectrolytes and biomolecules viewed as strongly coupled Coulomb systems

    International Nuclear Information System (INIS)

    A brief review is given on recent studies of charged soft matter solutions, as modelled by the 'primitive' approach of strongly coupled Coulomb systems, where the solvent just enters as a dielectric background. These include charged colloids, biological macromolecules such as proteins and DNA, polyelectrolytes and polyelectrolyte stars. Also some original results are presented on colloid-polyelectrolyte complex formation near walls and on the anomalous fluid structure of polyelectrolyte stars as a function of increasing concentration

  6. Coulomb interaction effects in many-particle nuclear reactions with two-fragment resonance formation

    International Nuclear Information System (INIS)

    The modified final-state interaction theory taking into consideration the Coulomb interaction between two-fragment nuclear resonance decay products and accompanying reaction products is developed including the case of near-threshold resonances. The branching ratio change is also studied for the near-threshold resonance 7Li*(Ex = 7.45 MeV), which is formed in the reaction 7Li(α,α)7Li*at Eα = 27.2 MeV

  7. Computation of doses for large-angle Coulomb scattering of proton pencil beams

    International Nuclear Information System (INIS)

    In this work we present a study of the impact of considering higher order terms in Moliere's multiple Coulomb scattering (MCS) theory for the purpose of calculating scanning proton pencil beam lateral dose profiles in water. The proton beam profile in air, just before entering the target medium, was modeled with a sum of Gaussians fitted with measured data. The subsequent proton scattering in water was described using the three-term Moliere distribution, which covers both small- and large-angle scatterings. We compared measured and computed lateral dose profiles at the 2 cm and at the near-Bragg peak depths for proton pencil beams with energies of 72.5 MeV, 121.2 MeV, 163.9 MeV and 221.8 MeV. At shallow depths, the Coulomb interaction model provided a good description of the profiles for all energies, except for 221.8 MeV. At the near-Bragg peak depths, the Coulomb interaction model provided a good description of the profiles only for the 72.5 MeV. The observed discrepancies may be attributed to the additional contributions from nuclear interactions, which may be quantified only after an accurate description of the MCS. The analysis presented in this work did not require user-adjustable parameters and may be carried out in a similar way for any other media, depths and proton energies.

  8. Testing refined shell-model interactions in the sd shell: Coulomb excitation of Na26

    CERN Document Server

    Siebeck, B; Blazhev, A; Reiter, P; Altenkirch, R; Bauer, C; Butler, P A; De Witte, H; Elseviers, J; Gaffney, L P; Hess, H; Huyse, M; Kröll, T; Lutter, R; Pakarinen, J; Pietralla, N; Radeck, F; Scheck, M; Schneiders, D; Sotty, C; Van Duppen, P; Vermeulen, M; Voulot, D; Warr, N; Wenander, F

    2015-01-01

    Background: Shell-model calculations crucially depend on the residual interaction used to approximate the nucleon-nucleon interaction. Recent improvements to the empirical universal sd interaction (USD) describing nuclei within the sd shell yielded two new interactions—USDA and USDB—causing changes in the theoretical description of these nuclei. Purpose: Transition matrix elements between excited states provide an excellent probe to examine the underlying shell structure. These observables provide a stringent test for the newly derived interactions. The nucleus Na26 with 7 valence neutrons and 3 valence protons outside the doubly-magic 16O core is used as a test case. Method: A radioactive beam experiment with Na26 (T1/2=1,07s) was performed at the REX-ISOLDE facility (CERN) using Coulomb excitation at safe energies below the Coulomb barrier. Scattered particles were detected with an annular Si detector in coincidence with γ rays observed by the segmented MINIBALL array. Coulomb excitation cross sections...

  9. Exact analytical solutions of continuity equation for electron beams precipitating in Coulomb collisions

    Energy Technology Data Exchange (ETDEWEB)

    Dobranskis, R. R.; Zharkova, V. V., E-mail: valentina.zharkova@northumbria.ac.uk [Department of Mathematics and Information Sciences, University of Northumbria, Newcastle upon Tyne NE1 2XP (United Kingdom)

    2014-06-10

    The original continuity equation (CE) used for the interpretation of the power law energy spectra of beam electrons in flares was written and solved for an electron beam flux while ignoring an additional free term with an electron density. In order to remedy this omission, the original CE for electron flux, considering beam's energy losses in Coulomb collisions, was first differentiated by the two independent variables: depth and energy leading to partial differential equation for an electron beam density instead of flux with the additional free term. The analytical solution of this partial differential continuity equation (PDCE) is obtained by using the method of characteristics. This solution is further used to derive analytical expressions for mean electron spectra for Coulomb collisions and to carry out numeric calculations of hard X-ray (HXR) photon spectra for beams with different parameters. The solutions revealed a significant departure of electron densities at lower energies from the original results derived from the CE for the flux obtained for Coulomb collisions. This departure is caused by the additional exponential term that appeared in the updated solutions for electron differential density leading to its faster decrease at lower energies (below 100 keV) with every precipitation depth similar to the results obtained with numerical Fokker-Planck solutions. The effects of these updated solutions for electron densities on mean electron spectra and HXR photon spectra are also discussed.

  10. Transport coefficients of graphene: Interplay of impurity scattering, Coulomb interaction, and optical phonons

    Science.gov (United States)

    Xie, Hong-Yi; Foster, Matthew S.

    2016-05-01

    We study the electric and thermal transport of the Dirac carriers in monolayer graphene using the Boltzmann-equation approach. Motivated by recent thermopower measurements [F. Ghahari, H.-Y. Xie, T. Taniguchi, K. Watanabe, M. S. Foster, and P. Kim, Phys. Rev. Lett. 116, 136802 (2016), 10.1103/PhysRevLett.116.136802], we consider the effects of quenched disorder, Coulomb interactions, and electron-optical-phonon scattering. Via an unbiased numerical solution to the Boltzmann equation we calculate the electrical conductivity, thermopower, and electronic component of the thermal conductivity, and discuss the validity of Mott's formula and of the Wiedemann-Franz law. An analytical solution for the disorder-only case shows that screened Coulomb impurity scattering, although elastic, violates the Wiedemann-Franz law even at low temperature. For the combination of carrier-carrier Coulomb and short-ranged impurity scattering, we observe the crossover from the interaction-limited (hydrodynamic) regime to the disorder-limited (Fermi-liquid) regime. In the former, the thermopower and the thermal conductivity follow the results anticipated by the relativistic hydrodynamic theory. On the other hand, we find that optical phonons become non-negligible at relatively low temperatures and that the induced electron thermopower violates Mott's formula. Combining all of these scattering mechanisms, we obtain the thermopower that quantitatively coincides with the experimental data.

  11. Functional theory of extended Coulomb systems

    International Nuclear Information System (INIS)

    A consistent formulation is presented for a functional theory of extended quantum many-particle systems with long-range Coulomb interactions, which extends the density-functional theory of Hohenberg and Kohn to encompass the theory of dielectrics formulated in terms of electric fields and polarization. We show that a complete description of insulators in the thermodynamic limit requires a functional of density and macroscopic polarization; nevertheless, for any insulator the state with zero macroscopic electric field can be considered a reference state that is a functional of the density alone. Dielectric phenomena involve the behavior of the material in the presence of macroscopic electric fields that induce changes of the macroscopic polarization from its equilibrium value in the reference state. In the thermodynamic limit there is strictly no ground state and constraints must be placed upon the electronic wave functions in order to have a well-defined energy functional; within these constrained subspaces the Hohenberg-Kohn theorems can be generalized in terms of the density and the change in the macroscopic polarization. The essential role of the polarization is shown by an explicit example of two potentials that lead to the same periodic density in a crystal, but different macroscopic electric fields and polarization. In the Kohn-Sham approach both the kinetic and the exchange-correlation energy are shown to depend upon the changes in polarization; this leads to generalized Kohn-Sham equations with a nonlocal operator. The effect can be traced to the polarization of the average exchange-correlation hole itself in the presence of macroscopic fields, which is essential for an exact description of static dielectric phenomena. copyright 1997 The American Physical Society

  12. Coulomb sink effect on coarsening of metal nanostructures on surfaces

    Institute of Scientific and Technical Information of China (English)

    Yong HAN; Feng LIU

    2008-01-01

    We discuss Coulomb effects on the coarsening of metal nanostructures on surfaces. We have proposed a new concept of a "Coulomb sink" [Phys. Rev. Lett., 2004, 93: 106102] to elucidate the effect of Coulomb charging on the coarsening of metal mesas grown on semiconductor surfaces. A charged mesa, due to its reduced chemical potential, acts as a Coulomb sink and grows at the expense of neighboring neu-tral mesas. The Coulomb sink provides a potentially useful method for the controlled fabrication of metal nanostructures. In this article, we will describe in detail the proposed physical models, which can explain qualitatively the most salient fea-tures of coarsening of charged Pb mesas on the Si(111) sur-face, as observed by scanning tunneling microscopy (STM). We will also describe a method of precisely fabricating large-scale nanocrystals with well-defined shape and size. By using the Coulomb sink effect, the artificial center-full-hol-lowed or half-hollowed nanowells can be created.

  13. Efros-Shklovskii variable range hopping conductivity without Coulomb gap

    Science.gov (United States)

    Chen, Tianran; Skinner, Brian

    In doped semiconductors and Coulomb glasses, in the limit of weak coupling, the electron conductivity primarily proceeds by phonon-assisted tunneling or hopping between different sites through the insulating gaps that separate them. Electron conduction can occur both through nearest-neighbor hopping and through cotunneling of electrons between distant sites via a chain of intermediate virtual states. In the presence of some disorder, the latter mechanism dominates at low temperatures, where the length of the hops grows to optimize the conductivity. This transport mechanism was introduced by Mott, and is called variable range hopping. When the Coulomb interaction between localized electrons is taken into account, it can be shown that at a sufficiently low temperature, variable range hopping conductivity obeys the Efros-Shklovskii (ES) law, which has been observed in a number of amorphous semiconductors and granular metal systems at low temperatures. ES conductivity has been long understood as the result of a soft, Coulomb gap at the Fermi level. However, such a theory overlooks the presence of spatial correlations between site energies and their possible effects on electrical conductivity. In this talk, we show both analytically and numerically that in systems where spatial correlations must be taken into account, ES conductivity may persist far outside the Coulomb gap, in contrast to conventional transport theory for doped semiconductors and Coulomb glasses where ES conductivity only occurs within the Coulomb gap.

  14. Ejection of Coulomb Crystals from a Linear Paul Ion Trap for Ion-Molecule Reaction Studies.

    Science.gov (United States)

    Meyer, K A E; Pollum, L L; Petralia, L S; Tauschinsky, A; Rennick, C J; Softley, T P; Heazlewood, B R

    2015-12-17

    Coulomb crystals are being increasingly employed as a highly localized source of cold ions for the study of ion-molecule chemical reactions. To extend the scope of reactions that can be studied in Coulomb crystals-from simple reactions involving laser-cooled atomic ions, to more complex systems where molecular reactants give rise to multiple product channels-sensitive product detection methodologies are required. The use of a digital ion trap (DIT) and a new damped cosine trap (DCT) are described, which facilitate the ejection of Coulomb-crystallized ions onto an external detector for the recording of time-of-flight (TOF) mass spectra. This enables the examination of reaction dynamics and kinetics between Coulomb-crystallized ions and neutral molecules: ionic products are typically cotrapped, thus ejecting the crystal onto an external detector reveals the masses, identities, and quantities of all ionic species at a selected point in the reaction. Two reaction systems are examined: the reaction of Ca(+) with deuterated isotopologues of water, and the charge exchange between cotrapped Xe(+) with deuterated isotopologues of ammonia. These reactions are examples of two distinct types of experiment, the first involving direct reaction of the laser-cooled ions, and the second involving reaction of sympathetically-cooled heavy ions to form a mixture of light product ions. Extensive simulations are conducted to interpret experimental results and calculate optimal operating parameters, facilitating a comparison between the DIT and DCT approaches. The simulations also demonstrate a correlation between crystal shape and image shape on the detector, suggesting a possible means for determining crystal geometry for nonfluorescing ions. PMID:26406306

  15. The effects of coulomb distortion on the first, second, and third sturcture functions for (e, e'p) reactions

    CERN Document Server

    Kim, K S; Cheon, I T; Chung, Y G

    1998-01-01

    In this paper, we study the electron Coulomb distortion effects on the first, second, and third structure functions for the exclusive reaction (e, e'p) in the quasielastic region. For a heavy target ( sup 2 sup 0 sup 8 Pb) or a light nucleus ( sup 1 sup 6 O), these structure functions calculated using the distorted wave Born approximation for the electron Coulomb distortion have shapes similar to those calculated using the plane wave Born approximation, but the effects are changed in magnitude. We use the approximate Moeller potential which has a 'plane-wave-like' form and hence permits the separation of the cross section into five structure functions. We investigate the dependence of the azimuthal angle for the outgoing proton on each structure functions. In this calculation, we use the Dirac-Hartree single particle wave functions for the ground state and the relativistic optical wave functions for the continuum proton.

  16. Accuracy of the geometric-mean method for determining spatial resolutions of tracking detectors in the presence of multiple Coulomb scattering

    CERN Document Server

    Zhang, Aiwu

    2016-01-01

    The geometric-mean method is often used to estimate the spatial resolution of a position-sensitive detector probed by tracks. It calculates the resolution solely from measured track data without using a detailed tracking simulation and without considering multiple Coulomb scattering effects. Two separate linear track fits are performed on the same data, one excluding and the other including the hit from the probed detector. The geometric mean of the widths of the corresponding exclusive and inclusive residual distributions for the probed detector is then taken as a measure of the intrinsic spatial resolution of the probed detector: $\\sigma=\\sqrt{\\sigma_{ex}\\cdot\\sigma_{in}}$. The validity of this method is examined for a range of resolutions with a stand-alone Geant4 Monte Carlo simulation that specifically takes multiple Coulomb scattering in the tracking detector materials into account. Using simulated as well as actual tracking data from a representative beam test scenario, we find that the geometric-mean ...

  17. Fusion and Direct Reactions of Halo Nuclei at Energies around the Coulomb Barrier

    CERN Document Server

    Keeley, N; Raabe, R; Sida, J L

    2007-01-01

    The present understanding of reaction processes involving light unstable nuclei at energies around the Coulomb barrier is reviewed. The effect of coupling to direct reaction channels on elastic scattering and fusion is investigated, with the focus on halo nuclei. A list of definitions of processes is given, followed by a review of the experimental and theoretical tools and information presently available. The effect of couplings on elastic scattering and fusion is studied with a series of model calculations within the coupled-channels framework. The experimental data on fusion are compared to "bare" no-coupling one-dimensional barrier penetration model calculations. On the basis of these calculations and comparisons with experimental data, conclusions are drawn from the observation of recurring features. The total fusion cross sections for halo nuclei show a suppression with respect to the "bare" calculations at energies just above the barrier that is probably due to single neutron transfer reactions. The dat...

  18. Excitation and ionization of hydrogen and helium atoms by femtosecond laser pulses: theoretical approach by Coulomb-Volkov states

    International Nuclear Information System (INIS)

    We present a theoretical approach using Coulomb-Volkov states that appears useful for the study of atomic multi-photonic processes induced by intense XUV femtosecond laser pulses. It predicts hydrogen ionization spectra when it is irradiated by laser pulses in perturbations conditions. Three ways have been investigated. Extension to strong fields when ℎω > Ip: it requires to include the hydrogen ground state population, introducing it in standard Coulomb-Volkov amplitude leads to saturated multi-photonic ionization. Extension to multi-photonic transitions with ℎω p: new quantum paths are open by the possibility to excite the lower hydrogen bound states. Multiphoton excitation of these states is investigated using a Coulomb-Volkov approach. Extension to helium: two-photon double ionization study shows the influence of electronic correlations in both ground and final state. Huge quantity of information such as angular and energetic distributions as well as total cross sections is available. (author)

  19. Strain induced ferroelectricity in GdN: first-principles calculations.

    Science.gov (United States)

    Liu, H M; Ma, C Y; Zhu, C; Liu, J-M

    2011-06-22

    Using first-principles density functional calculations and the generalized gradient approximation functional including the on-site Coulomb interaction of 4f orbitals, we show that ferroelectricity can be induced by appropriate epitaxial tensile strain in GdN with a simple rock-salt structure, and that the polarization is sensitive to the strain. The calculated phonon spectra of strained GdN also confirm the existence of ferroelectric polarization. In addition, the electronic structure and magnetic properties of strained GdN as a function of strain are investigated. The present work opens up the possibility of epitaxially tensioned GdN thin films as potential multiferroics. PMID:21625033

  20. Direct Observation of a Semi-Bare Electron Coulomb Field Recover

    CERN Document Server

    Naumenko, G; Shevelev, M

    2011-01-01

    The problem of "semi-bare electron" was first considered in frame of quantum electrodynamics by E.L. Feinberg in 1980. In theory in frame of classical electrodynamics this problem was touched on in articles of N.F. Shul'ga and X. Artru. In 2008 the experimental investigations of this phenomenon in millimeter wavelength region were started by the group of scientists, including authors of this article. Used technique allowed us to study this effect in macroscopic mode. In this paper we present the results of direct observation of a semi-bare electron coulomb field recovery. The semi-bare state was obtained by passing of electron beam through the hole in a conductive screen. Measured spatial distribution of electromagnetic field shows the process of recover of the electron coulomb field, which is followed by a forward radiation. The experiments were performed on the relativistic electron beam of the microtron of Tomsk Polytechnic University.

  1. Systematic study of breakup effects on complete fusion at energies above the Coulomb barrier

    CERN Document Server

    Wang, Bing; Gomes, P R S; Zhao, En-Guang; Zhou, Shan-Gui

    2014-01-01

    A large number of complete fusion excitation functions of reactions including the breakup channel were measured in recent decades, especially in the last few years. It allows us to investigate the systematic behavior of the breakup effects on the complete fusion cross sections. To this end, we perform a systematic study of the breakup effects on the complete fusion cross sections at energies above the Coulomb barrier. The reduced fusion functions $F(x)$ are compared with the universal fusion functions which are used as a uniform standard reference. The complete fusion cross sections at energies above the Coulomb barrier are suppressed by the breakup of projectiles. This suppression effect for reactions induced by the same projectile is independent of the target and mainly determined by the lowest energy breakup channel of the projectile. There holds a good exponential relation between the suppression factor and the energy corresponding to the lowest breakup threshold.

  2. Realization of collective strong coupling with ion Coulomb crystals in an optical cavity

    DEFF Research Database (Denmark)

    Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan; Albert, Magnus; Drewsen, Michael

    2009-01-01

    information 10 . At present, photons are the best carriers of quantum information between physically separated sites 11, 12 and quantum-information processing using stationary qubits 10 is most promising, with the furthest advances having been made with trapped ions 13, 14, 15 . The implementation of complex...... quantum-information-processing networks 11, 12 hence requires devices to efficiently couple photons and stationary qubits. Here, we present the first CQED experiments demonstrating that the collective strong-coupling regime 2 can be reached in the interaction between a solid in the form of an ion Coulomb...... crystal 16 and an optical field. The obtained coherence times are in the millisecond range and indicate that Coulomb crystals positioned inside optical cavities are promising for realizing a variety of quantum-information devices, including quantum repeaters 12 and quantum memories for light 17, 18...

  3. Charge separation in organic solar cells: Effects of Coulomb interaction, recombination and hole propagation

    Science.gov (United States)

    Nemati Aram, Tahereh; Asgari, Asghar; Mayou, Didier

    2016-07-01

    Bulk heterojunction (BHJ) organic photovoltaic cells are analysed within a simple efficient model that includes the important physical properties of such photovoltaic systems. In this model, in contrast with most of the previous studies, we take into account the motion of both the electron and the hole in the separation process at the donor-acceptor interface. We theoretically examine the exciton dissociation yield under the influences of charge Coulomb interaction and non-radiative recombination. We find that the electron-hole local Coulomb attraction and charge carriers' coupling parameters play an important role in the system performance and in the optimal energy conversion efficiency of the BHJ photocell. We show that the fixed-hole models tend to underestimate the yield.

  4. Onset of collectivity in $^{96,98}$Sr studied via Coulomb excitation

    CERN Document Server

    Clement, E; Dijon, A; de France, G; Bastin, B; Blazhev, A; Bree, N; Butler, P; Delahaye, P; Ekstrom, A; Georgiev, G; Hasan, N; Iwanicki, J; Jenkins, D; Korten, W; Larsen, A C; Ljungvall, J; Moschner, K; Napiorkowski, P; Pakarinen, J; Petts, A; Renstrom, T; Seidlitz, M; Siem, S; Sotty, C; Srebrny, J; Stefanescu, I; Tveten, G M; Van de Walle, J; Warr, N; Wrzosek-Lipska, K; Zielinska, M; Bauer, C; Bruyneel, B; Butterworth, J; Fitzpatrick, C; Fransen, C; GernhäUser, R; Hess, H; Lutter, R; Marley, P; Reiter, P; Siebeck, B; Vermeulen, M; Wiens, A; De Witte, H

    2014-01-01

    A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N=60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.

  5. Onset of collectivity in 96,98Sr studied via Coulomb excitation

    Directory of Open Access Journals (Sweden)

    Clément E.

    2014-03-01

    Full Text Available A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N=60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.

  6. Coulomb stress changes and seismicity in central Taiwan due to the Nantou blind-thrust earthquakes in 2013

    Science.gov (United States)

    Liao, Boi-Yee; Huang, Huey-Chu

    2016-07-01

    Due to the two earthquakes, 27 March 2013 event (ML6.2, namely 0327 event) and 2 June 2013 event (ML6.5, namely 0602 event), occurring at the Nantou area of the central Taiwan, we investigate the relationship between the Coulomb stress changes and the seismicity in the paper. We first employed the refined homomorphic deconvolution method to invert the kinematic source processes of these two earthquakes from the teleseismic data recorded by Incorporated Research Institutions for Seismology (IRIS), and then calculated the Coulomb stress changes of these two events. The total durations of the rupture process for the 0327 and 0602 events were 12 s and 15 s, respectively. The epicenter of the 0602 event and the epicenters of the aftershocks (ML > 3) of the 0327 event were concentrated in a region with positive Coulomb stresses caused by the 0327 event. This indicates that the derived source process was available and coincided with physical properties in a manner that strongly suggests that the 0602 event was triggered by the 0327 event. According to the Coulomb stress changes caused by the 0602 event at a depth of 4 km and its vertical cross section, most of the aftershocks (ML > 3) of the 0602 event were located in a region with positive Coulomb stress changes greater than 0.1 bar. In addition, almost all the epicenters of the earthquakes (ML > 3) in central Taiwan between July 15, 2013, and January 27, 2015, were located in a region with positive Coulomb stress changes at a depth of 6 km contributed by the 0327 and 0602 events. These findings indicate that if the background stress in the central Taiwan is intense high, the Coulomb stress changes contributed by the two events may affect the seismicity of central Taiwan in this period of time, and that a region with extreme positive Coulomb stress changes may be the place in which potential earthquakes will occur in the future. Moreover, the proposed inversion method can derive the proper source model efficiently

  7. Coulomb interaction in atomic and nuclear physics: Inner-Shell excitation, Coulomb dissociation of nuclei, and nuclear polarizability in electronic atoms

    International Nuclear Information System (INIS)

    In three chapters different physical situations are described which have commonly the Coulomb interaction as driving force. The first two chapters study the Coulomb interactions in connection with the excitation of inner electron shells and the Coulomb excitation of nuclei in first order. In the third part on effect ofthe Coulomb interaction between electronic shell and nucleus is treated in second order (nuclear polarization), and its effect on the isotopic and isomeric shift is studied. (orig./HSI)

  8. Laser-assisted electron-ion scattering by the Coulomb-Glauber approximation

    International Nuclear Information System (INIS)

    In this paper, we extend the Coulomb-Glauber approximation to charged particles scattering processes in the presence of a laser field. With this method, laser-assisted electron scattering by hydrogen-like ions is studied. Numerical results of the elastic and 1s→2s, 1s→2p excitation scattering differential cross sections are obtained. Based on these results we discuss and compare with the Born approximation, the selection rules, the dressing effects and the use of the closure approximation in the calculation of the S-matrix. The cross section of the elastic scattering as a function of the charge number Z has also been shown. (author)

  9. Microscopic description of Coulomb and nuclear excitation of multiphonon states in $^{40}$Ca + $^{40}$Ca collisions

    OpenAIRE

    N. Andres; Catara, F.; Lanza, E. G.; Chomaz, Ph.; FALLOT M.; Scarpaci, J.A.

    2001-01-01

    We calculate the inelastic scattering cross sections to populate one- and two-phonon states in heavy ion collisions with both Coulomb and nuclear excitations. Starting from a microscopic approach based on RPA, we go beyond it in order to treat anharmonicities and non-linear terms in the exciting field. These anharmonicities and non-linearities are shown to have important effects on the cross sections both in the low energy part of the spectrum and in the energy region of the Double Giant Quad...

  10. Three-body Coulomb breakup of 11Li in the complex scaling method

    OpenAIRE

    Myo, T.; Aoyama, S.; Kato, K.; Ikeda, K.

    2003-01-01

    Coulomb breakup strengths of 11Li into a three-body 9Li+n+n system are studied in the complex scaling method. We decompose the transition strengths into the contributions from three-body resonances, two-body ``10Li+n'' and three-body ``9Li+n+n'' continuum states. In the calculated results, we cannot find the dipole resonances with a sharp decay width in 11Li. There is a low energy enhancement in the breakup strength, which is produced by both the two- and three-body continuum states. The enha...

  11. Two Dimensional Coulomb Potential of Confined Excitons in Quantum Well Structures

    Directory of Open Access Journals (Sweden)

    M. Solaimani

    2012-12-01

    Full Text Available In this study, we have investigated an exciton confined in a single quantum well. For the first time, we have compared the different methods of approximating the effective two dimensional Coulomb potentials which had been previously reported in the literatures. The effect of different previously introduced trial wave functions on the exciton binding energy is also investigated. In order to have a consistent and stable calculation we have tried to find the true region of variations for free parameters of these trial wave functions. Effects of the barrier thickness and doping fraction are also investigated.

  12. Exponential-trigonometric basis functions in the Coulomb four-body problem

    International Nuclear Information System (INIS)

    Basis functions of a new type--specifically, exponential-trigonometric functions depending on all six interparticle distances--have been proposed for the Coulomb four-body problem. A method has been developed for computing nine-dimensional integrals determining the matrix elements of the Hamiltonian for a four-body system and featuring these functions. The efficiency of the approach that relies on the proposed basis functions has been tested by calculating the e+e-e+e-, p+μ-p+μ-, μ+e-μ+e-, and p+e-p+e- molecules

  13. Coulomb excitation of neutron-rich $^{134-136}$Sn isotopes

    CERN Multimedia

    We propose to study excited states in the isotopes $^{134,136}$Sn by $\\gamma$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to investigate the evolution of quadrupole collectivity beyond the magic shell closure at N = 82 by the determination of B(E2) values and electric quadrupole moments $\\mathcal{Q}_2$. Recent shell-model calculations using realistic interactions predict possible enhanced collectivity in neutron-rich regions. Evidence for this could be obtained by this experiment. Furthermore, the currently unknown excitation energies of the 2$^+_{1}$ and 4$^+_{1}$ states in $^{136}$Sn will be measured for the first time.

  14. Distance dependence and salt sensitivity of pairwise, coulombic interactions in a protein

    OpenAIRE

    Lee, Kelly K; Fitch, Carolyn A.; García-Moreno E., Bertrand

    2002-01-01

    Histidine pKa values were measured in charge-reversal (K78E, K97E, K127E, and K97E/K127E) and charge-neutralization (E10A, E101A, and R35A) mutants of staphylococcal nuclease (SNase) by 1H-NMR spectroscopy. Energies of interaction between pairs of charges (ΔGij) were obtained from the shifts in pKa values relative to wild-type values. The data describe the distance dependence and salt sensitivity of pairwise coulombic interactions. Calculations with a continuum electrostatics method captured ...

  15. Cold chemistry with electronically excited Ca+ Coulomb crystals

    International Nuclear Information System (INIS)

    Rate constants for chemical reactions of laser-cooled Ca+ ions and neutral polar molecules (CH3F, CH2F2, or CH3Cl) have been measured at low collision energies (coll>/kB=5-243 K). Low kinetic energy ensembles of 40Ca+ ions are prepared through Doppler laser cooling to form ''Coulomb crystals'' in which the ions form a latticelike arrangement in the trapping potential. The trapped ions react with translationally cold beams of polar molecules produced by a quadrupole guide velocity selector or with room-temperature gas admitted into the vacuum chamber. Imaging of the Ca+ ion fluorescence allows the progress of the reaction to be monitored. Product ions are sympathetically cooled into the crystal structure and are unambiguously identified through resonance-excitation mass spectrometry using just two trapped ions. Variations of the laser-cooling parameters are shown to result in different steady-state populations of the electronic states of 40Ca+ involved in the laser-cooling cycle, and these are modeled by solving the optical Bloch equations for the eight-level system. Systematic variation of the steady-state populations over a series of reaction experiments allows the extraction of bimolecular rate constants for reactions of the ground state (2S1/2) and the combined excited states (2D3/2 and 2P1/2) of 40Ca+. These results are analyzed in the context of capture theories and ab initio electronic structure calculations of the reaction profiles. In each case, suppression of the ground state rate constant is explained by the presence of a submerged or real barrier on the ground state potential surface. Rate constants for the excited states are generally found to be in line with capture theories.

  16. Cold chemistry with electronically excited Ca+ Coulomb crystals

    Science.gov (United States)

    Gingell, Alexander D.; Bell, Martin T.; Oldham, James M.; Softley, Timothy P.; Harvey, Jeremy N.

    2010-11-01

    Rate constants for chemical reactions of laser-cooled Ca+ ions and neutral polar molecules (CH3F, CH2F2, or CH3Cl) have been measured at low collision energies (⟨Ecoll⟩/kB=5-243 K). Low kinetic energy ensembles of C40a+ ions are prepared through Doppler laser cooling to form "Coulomb crystals" in which the ions form a latticelike arrangement in the trapping potential. The trapped ions react with translationally cold beams of polar molecules produced by a quadrupole guide velocity selector or with room-temperature gas admitted into the vacuum chamber. Imaging of the Ca+ ion fluorescence allows the progress of the reaction to be monitored. Product ions are sympathetically cooled into the crystal structure and are unambiguously identified through resonance-excitation mass spectrometry using just two trapped ions. Variations of the laser-cooling parameters are shown to result in different steady-state populations of the electronic states of C40a+ involved in the laser-cooling cycle, and these are modeled by solving the optical Bloch equations for the eight-level system. Systematic variation of the steady-state populations over a series of reaction experiments allows the extraction of bimolecular rate constants for reactions of the ground state (S21/2) and the combined excited states (D23/2 and P21/2) of C40a+. These results are analyzed in the context of capture theories and ab initio electronic structure calculations of the reaction profiles. In each case, suppression of the ground state rate constant is explained by the presence of a submerged or real barrier on the ground state potential surface. Rate constants for the excited states are generally found to be in line with capture theories.

  17. Cost-Effective Treatment of Scalar Relativistic Effects for Multireference Systems: A CASSCF Implementation Based on the Spin-free Dirac-Coulomb Hamiltonian.

    Science.gov (United States)

    Lipparini, Filippo; Gauss, Jürgen

    2016-09-13

    We present an implementation of the complete active space-self-consistent field (CASSCF) method specifically designed to be used in four-component scalar relativistic calculations based on the spin-free Dirac-Coulomb (SFDC) Hamiltonian. Our implementation takes full advantage of the properties of the SFDC Hamiltonian that allow us to use real algebra and to exploit point-group and spin symmetry to their full extent while including in a rigorous way scalar relativistic effects in the treatment. The SFDC-CASSCF treatment is more expensive than its non-relativistic counterpart only in the orbital optimization step, while exhibiting the same computational cost for the rate-determining full configuration interaction part. The numerical aspects are discussed, and the capabilities of the SFDC-CASSCF methodology are demonstrated through a pilot application. PMID:27464026

  18. Features of non-congruent phase transition in modified Coulomb model of the binary ionic mixture

    CERN Document Server

    Stroev, N E

    2016-01-01

    Non-congruent gas-liquid phase transition (NCPT) have been studied in modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a \\textit{uniformly compressible} ideal electronic background /BIM($\\sim$)/. The features of NCPT in improved version of the BIM($\\sim$) model for the same mixture on background of \\textit{non-ideal} electronic Fermi-gas and comparison it with the previous calculations are the subject of present study. Analytical fits for Coulomb corrections to EoS of electronic and ionic subsystems were used in present calculations within the Gibbs--Guggenheim conditions of non-congruent phase equilibrium.Parameters of critical point-line (CPL) were calculated on the entire range of proportions of mixed ions $0

  19. Coulomb excitation studies of shape coexistence in atomic nuclei

    Science.gov (United States)

    Görgen, Andreas; Korten, Wolfram

    2016-02-01

    Low-energy Coulomb excitation provides a well-understood means of exciting atomic nuclei and allows measuring electromagnetic moments that can be directly related to the nuclear shape. The availability of radioactive ion beams (RIBs) at energies near the Coulomb barrier has made it possible to study shape coexistence in a variety of short-lived exotic nuclei. This review presents a short overview of the methods related to multi-step Coulomb excitation experiments, followed by a discussion of several examples. The focus is on two mass regions where recent Coulomb excitation experiments have contributed to the quantitative understanding of shape coexistence: nuclei with mass A≈ 70 near the N = Z line and nuclei with A ≈ 100 near neutron number N = 60. Experimental results are summarized and their significance for understanding shape coexistence is discussed. Experimental observables such as quadrupole moments and electromagnetic transition strengths represent furthermore important benchmarks for advancing theoretical nuclear structure models. With several new RIB facilities planned and under construction, Coulomb excitation will remain to be an important tool to extend the studies of nuclear shapes toward more exotic systems, and to obtain a more comprehensive and quantitative understanding of shape coexistence.

  20. Coulomb versus physical string tension on the lattice

    Science.gov (United States)

    Burgio, Giuseppe; Quandt, Markus; Reinhardt, Hugo; Vogt, Hannes

    2015-08-01

    From continuum studies it is known that the Coulomb string tension σC gives an upper bound for the physical (Wilson) string tension σW [D. Zwanziger, Phys. Rev. Lett. 90, 102001 (2003)]. How does such a relationship translate to the lattice, however? In this paper we give evidence that on the lattice, while the two string tensions are related at zero temperature, they decouple at finite temperature. More precisely, we show that on the lattice the Coulomb gauge confinement scenario is always tied to the spatial string tension, which is known to survive the deconfinement phase transition and to cause screening effects in the quark-gluon plasma. Our analysis is based on the identification and elimination of center vortices, which allows us to control the physical string tension and study its effect on the Coulomb gauge observables. We also show how alternative definitions of the Coulomb potential may sense the deconfinement transition; however, a true static Coulomb gauge order parameter for the phase transition is still elusive on the lattice.

  1. The secondary supernova machine: Gravitational compression, stored Coulomb energy, and SNII displays

    Science.gov (United States)

    Clayton, Donald D.; Meyer, Bradley S.

    2016-04-01

    Radioactive power for several delayed optical displays of core-collapse supernovae is commonly described as having been provided by decays of 56Ni nuclei. This review analyses the provenance of that energy more deeply: the form in which that energy is stored; what mechanical work causes its storage; what conservation laws demand that it be stored; and why its release is fortuitously delayed for about 106 s into a greatly expanded supernova envelope. We call the unifying picture of those energy transfers the secondary supernova machine owing to its machine-like properties; namely, mechanical work forces storage of large increases of nuclear Coulomb energy, a positive energy component within new nuclei synthesized by the secondary machine. That positive-energy increase occurs despite the fusion decreasing negative total energy within nuclei. The excess of the Coulomb energy can later be radiated, accounting for the intense radioactivity in supernovae. Detailed familiarity with this machine is the focus of this review. The stored positive-energy component created by the machine will not be reduced until roughly 106 s later by radioactive emissions (EC and β +) owing to the slowness of weak decays. The delayed energy provided by the secondary supernova machine is a few × 1049 erg, much smaller than the one percent of the 1053 erg collapse that causes the prompt ejection of matter; however, that relatively small stored energy is vital for activation of the late displays. The conceptual basis of the secondary supernova machine provides a new framework for understanding the energy source for late SNII displays. We demonstrate the nuclear dynamics with nuclear network abundance calculations, with a model of sudden compression and reexpansion of the nuclear gas, and with nuclear energy decompositions of a nuclear-mass law. These tools identify excess Coulomb energy, a positive-energy component of the total negative nuclear energy, as the late activation energy. If the

  2. Semiclassical wave functions and semiclassical dynamics for the Kepler/Coulomb problem

    International Nuclear Information System (INIS)

    We investigate the semiclassical Kepler/Coulomb problem using the classical constants of the motion in the framework of Nelson’s stochastic mechanics. This is done by considering the eigenvalue relations for a family of coherent states (known as the atomic elliptic states) whose wave functions are concentrated on the elliptical orbit corresponding to the associated classical problem. We show that these eigenvalue relations lead to identities for the semiclassical energy, angular momentum and Hamilton–Lenz–Runge vectors in the elliptical case. These identities are then extended to include the cases of circular, parabolic and hyperbolic motions. We show that in all cases the semiclassical wave function is determined by our identities and so our identities can be seen as defining a semiclassical Kepler/Coulomb problem. The results are interpreted in terms of two dynamical systems: one a complex valued solution to the classical mechanics for a Coulomb potential and the other the drift field for a semiclassical Nelson diffusion. (paper)

  3. Optimal load resistance of a randomly excited nonlinear electromagnetic energy harvester with Coulomb friction

    International Nuclear Information System (INIS)

    A nonlinear electromagnetic energy harvester directly powering a load resistance is considered in this manuscript. The nonlinearity includes the cubic stiffness and the unavoidable Coulomb friction, and the base excitation is confined to Gaussian white noise. Directly starting from the coupled equations, a novel procedure to evaluate the random responses and the mean output power is developed through the generalized harmonic transformation and the equivalent non-linearization technique. The dependence of the optimal ratio of the load resistance to the internal resistance and the associated optimal mean output power on the internal resistance of the coil is established. The principle of impedance matching is correct only when the internal resistance is infinity, and the optimal mean output power approaches an upper limit as the internal resistance is close to zero. The influence of the Coulomb friction on the optimal resistance ratio and the optimal mean output power is also investigated. It is proved that the Coulomb friction almost does not change the optimal resistance ratio although it prominently reduces the optimal mean output power. (paper)

  4. Coulomb crystal mass spectrometry in a digital ion trap

    CERN Document Server

    Deb, Nabanita; Smith, Alexander D; Keller, Matthias; Rennick, Christopher J; Heazlewood, Brianna R; Softley, Timothy P

    2015-01-01

    We present a mass spectrometric technique for identifying the masses and relative abundances of Coulomb-crystallized ions held in a linear Paul trap. A digital radiofrequency waveform is employed to generate the trapping potential, as this can be cleanly switched off, and static dipolar fields subsequently applied to the trap electrodes for ion ejection. Excellent detection efficiency is demonstrated for Ca+ and CaF+ ions from bi-component Ca+/CaF+ Coulomb crystals prepared by reaction of Ca+ with CH3F. A quantitative linear relationship is observed between ion number and the corresponding integrated TOF peak, independent of the ionic species. The technique is applicable to a diverse range of multi-component Coulomb crystals - demonstrated here for Ca+/NH3+/NH4+ and Ca+/CaOH+/CaOD+ crystals - and will facilitate the measurement of ion-molecule reaction rates and branching ratios in complicated reaction systems.

  5. Long-range Coulomb interaction in nodal-ring semimetals

    Science.gov (United States)

    Huh, Yejin; Moon, Eun-Gook; Kim, Yong Baek

    2016-01-01

    Recently there have been several proposals of materials predicted to be nodal-ring semimetals, where zero energy excitations are characterized by a nodal ring in the momentum space. This class of materials falls between the Dirac-like semimetals and the more conventional Fermi-surface systems. As a step towards understanding this unconventional system, we explore the effects of the long-range Coulomb interaction. Due to the vanishing density of states at the Fermi level, Coulomb interaction is only partially screened and remains long-ranged. Through renormalization group and large-Nf computations, we have identified a nontrivial interacting fixed point. The screened Coulomb interaction at the interacting fixed point is an irrelevant perturbation, allowing controlled perturbative evaluations of physical properties of quasiparticles. We discuss unique experimental consequences of such quasiparticles: acoustic wave propagation, anisotropic dc conductivity, and renormalized phonon dispersion as well as energy dependence of quasiparticle lifetime.

  6. Adiabatic and non-adiabatic processes in strong Coulomb fields

    International Nuclear Information System (INIS)

    Adiabatic and non-adiabatic behaviour of relativistic electrons in external Coulomb fields of time-dependent strength is studied within the framework of a model for the description of a shell electron's behaviour during a heavy-ion collision. A classification scheme for types of non-adiabatic behaviour is suggested; its relevance for the analysis of pair production processes in strong Coulomb fields is discussed (K-Shell Ionization). An ansatz for the vacuum polarization potential is introduced and employed to demonstrate the special role of vacuum polarization for adiabatic and non-adiabatic behaviour in very strong Coulomb fields (Zα > 1). The implications of the underlaying specific features of the vacuum polarization charge density in very strong fields for pair production mechanisms are considered. (orig.)

  7. Imaging quantum Hall Coulomb islands inside a quantum ring

    Science.gov (United States)

    Martins, Frederico; Hackens, Benoit; Faniel, Sebastien; Bayot, Vincent; Pala, Marco; Sellier, Hermann; Huant, Serge; Desplanque, Ludovic; Wallart, Xavier

    2011-03-01

    In the quantum Hall regime near integer filling factors, electrons are transmitted through edge states confined at the borders of the device. In mesoscopic samples, however, edge states may be sufficiently close to allow electrons to tunnel, or to be transmitted through localized states (``Coulomb islands''). Here, we use the biased tip of a low temperature scanning gate microscope to alter tunneling through quantum Hall Coulomb islands localized inside a quantum ring patterned in an InGaAs/InAlAs heterostructure. Simultaneously, we map the quantum ring resistance and observe different sets of concentric resistance fringes, due to charging/discharging of each Coulomb island. Tuning the magnetic field and the tip voltage, we reveal the rich and complex behaviour of these fringes.

  8. Bound state energy of a Coulomb impurity in gapped bilayer graphene: "Hydrogen atom with a Mexican hat"

    OpenAIRE

    Skinner, Brian; Shklovskii, B. I.; Voloshin, M. B.

    2013-01-01

    Application of a perpendicular electric field induces a band gap in bilayer graphene, and it also creates a "Mexican hat" structure in the dispersion relation. This structure has unusual implications for the hydrogen-like bound state of an electron to a Coulomb impurity. We calculate the ground state energy of this hydrogen-like state as a function of the applied interlayer voltage and the effective fine structure constant. Unlike in the normal hydrogen atom, the resulting wavefunction has ma...

  9. Coulomb excitation $^{74}$Zn-$^{80}$Zn (N=50): probing the validity of shell-model descriptions around $^{78}$Ni

    CERN Multimedia

    A study of the evolution of the nuclear structure along the zinc isotopic chain close to the doubly magic nucleus $^{78}$Ni is proposed to probe recent shell-model calculations in this area of the nuclear chart. Excitation energies and connecting B(E2) values will be measured through multiple Coulomb excitation experiment with laser ionized purified beams of $^{74-80}$Zn from HIE ISOLDE. The current proposal request 30 shifts.

  10. Observation of ionic Coulomb blockade in nanopores.

    Science.gov (United States)

    Feng, Jiandong; Liu, Ke; Graf, Michael; Dumcenco, Dumitru; Kis, Andras; Di Ventra, Massimiliano; Radenovic, Aleksandra

    2016-08-01

    Emergent behaviour from electron-transport properties is routinely observed in systems with dimensions approaching the nanoscale. However, analogous mesoscopic behaviour resulting from ionic transport has so far not been observed, most probably because of bottlenecks in the controlled fabrication of subnanometre nanopores for use in nanofluidics. Here, we report measurements of ionic transport through a single subnanometre pore junction, and the observation of ionic Coulomb blockade: the ionic counterpart of the electronic Coulomb blockade observed for quantum dots. Our findings demonstrate that nanoscopic, atomically thin pores allow for the exploration of phenomena in ionic transport, and suggest that nanopores may also further our understanding of transport through biological ion channels. PMID:27019385

  11. Lyapunov spectra of Coulombic and gravitational periodic systems

    CERN Document Server

    Kumar, Pankaj

    2016-01-01

    We compute Lyapunov spectra for Coulombic and gravitational versions of the one-dimensional systems of parallel sheets with periodic boundary conditions. Exact time evolution of tangent-space vectors are derived and are utilized toward computing Lypaunov characteristic exponents using an event-driven algorithm. The results indicate that the energy dependence of the largest Lyapunov exponent emulates that of Kolmogorov-entropy density for each system at different degrees of freedom. Our approach forms an effective and approximation-free tool toward studying the dynamical properties exhibited by the Coulombic and gravitational systems and finds applications in investigating indications of thermodynamic transitions in large versions of the spatially periodic systems.

  12. Coulomb explosion in aromatic molecules and their deuterated derivatives

    Science.gov (United States)

    Tzallas, P.; Kosmidis, C.; Graham, P.; Ledingham, K. W. D.; McCanny, T.; Hankin, S. M.; Singhal, R. P.; Taday, P. F.; Langley, A. J.

    2000-12-01

    Coulomb explosion within some aromatic molecules (furan, pyrrole, pyridine and pyrazine) and their deuterated derivatives induced by strong fs laser fields (˜ 4×10 16 W/cm2) is studied at λ=790 nm by means of time-of-flight (TOF) mass spectrometry. It is found that in hydrogenated molecules the Coulomb explosion process begins at internuclear distances about twice larger than the equilibrium distance ( Re), while the expansion of the molecular skeleton in the deuterated derivatives is smaller. Based on the estimated kinetic energy values of the fragment ions, the charge distribution in the transient molecular species is also discussed.

  13. Vibrational motions in rotating nuclei studied by Coulomb excitations

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Yoshifumi R. [Kyushu Univ., Fukuoka (Japan). Dept. of Physics

    1998-03-01

    As is well-known Coulomb excitation is an excellent tool to study the nuclear collective motions. Especially the vibrational excitations in rotating nuclei, which are rather difficult to access by usual heavy-ion fusion reactions, can be investigated in detail. Combined with the famous 8{pi}-Spectrometer, which was one of the best {gamma}-ray detector and had discovered some of superdeformed bands, such Coulomb excitation experiments had been carried out at Chalk River laboratory just before it`s shutdown of physics division. In this meeting some of the experimental data are presented and compared with the results of theoretical investigations. (author)

  14. Nonlinear conductivity of two-dimensional Coulomb glasses

    OpenAIRE

    Caravaca, M.; Somoza, A. M.; Ortuño, M.

    2011-01-01

    We have studied the nonlinear conductivity of two-dimensional Coulomb glasses. We have used a Monte Carlo algorithm to simulate the dynamic of the system under an applied electric field $E$. We found that in the nonlinear regime the site occupancy in the Coulomb gap follows a Fermi-Dirac distribution with an effective temperature $T_{\\rm eff}$, higher than the phonon bath temperature $T$. The value of the effective temperature is compatible with that obtained for slow modes from the generaliz...

  15. Geometrically-frustrated pseudogap phase of Coulomb liquids

    International Nuclear Information System (INIS)

    We study a class of models with long-range repulsive interactions of the generalized Coulomb form V(r)∼1/rα. We show that decreasing the interaction exponent in the regime αc in any dimension d≥2, reflecting the strong geometric frustration produced by long-range interactions. A nearly frozen Coulomb liquid then survives in a broad pseudogap phase found at T>Tc, which is characterized by an unusual temperature dependence of all quantities. In contrast, the leading critical behavior very close to the charge-ordering temperature remains identical as in models with short-range interactions.

  16. Coulomb Blockade in an Ultrathin Ti Nanowire at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    CAIQiyu; YANGTao; CAIBingchu; YINYou; JIANGJianfei

    2003-01-01

    A scanning tunneling microscope operated in ambient air was employed to fabricate a~ 30nm-wide and ~ 700nm-long Ti nanowire connecting the source and drain electrodes on a 3nm-thick Ti film. The ultraflne but nonuniform Ti nanowire was well defined between two ox-idized lines. The gate electrode was capacitively coupled to the nanowire by a ~150nm-wide oxidized line. The electrical properties measured at room temperature of the Ti nanowire showed Coulomb blockade in highly nonlinear Ids-Vds characteristics and Coulomb oscillation in Ids - Vgs characteristics.

  17. CoulombExpress: Automated near-realtime forecasts of earthquake-induced stress transfer and expected seismicity rate changes (Invited)

    Science.gov (United States)

    Toda, S.; Enescu, B.; Stein, R. S.

    2009-12-01

    A principal tenet of the Coulomb hypothesis is that stress increases promote, and decreases inhibit, fault failure. In support of such a simple hypothesis, a growing number of studies have found that seismicity rates climb where the stress increases and fall where the stress drops. However, they are all evaluated retrospectively, which may permit unintentionial bias to enter into data interpretation. Further, retrospective tests do not contribute to earthquake disaster mitigation. In particular, the probability rate for triggered seismicity is highest immediately after a mainshock, as suggested by rate/state friction. Thus, to make the stress-based earthquake forecasting rapidly available and to permit objective prospective testing, we have developed CoulombExpress, an automatic stress calculation system, which uses near real-time information, such as earthquake magnitude, location, depth, and its rapid moment tensor solution. Two versions of CoulombExpress, “CoulombExpress Global” and “CoulombExpress Regional” are in progress. 1) CoulombExpress Global: The system quickly computes the Coulomb stress change caused by an M≥6 around the globe. It automatically accesses the USGS National Earthquake Information Center parameters. In order of time, the system uses the NEIC W-phase, central, and body-wave moment tensor solutions, when available, to make the two-nodal-plane source fault models using the empirical scaling relations of Wells and Coppersmith [1994]. The stress changes are resolved on receiver faults parallel to the sources and also on both nodal planes of the nearby 1967-2005 Global CMT earthquakes, as stand-in's for active faults. The color-coded displays allow the viewer to grasp where and by how much the off-fault aftershocks might become active. Keeping long-term records of our results in an official archive will allow evaluators to examine rigorously the forecasting skills of our model. 2) CoulombExpress Regional: This is a forecasting system

  18. Extraordinary waves in two dimensional electron gas with separate spin evolution and Coulomb exchange interaction

    CERN Document Server

    Andreev, Pavel A

    2016-01-01

    Hydrodynamics analysis of waves in two-dimensional degenerate electron gas with the account of separate spin evolution is presented. The transverse electric field is included along with the longitudinal electric field. The Coulomb exchange interaction is included in the analysis. In contrast with the three-dimensional plasma-like mediums the contribution of the transverse electric field is small. We show the decrease of frequency of both the extraordinary (Langmuir) wave and the spin-electron acoustic wave due to the exchange interaction. Moreover, spin-electron acoustic wave has negative dispersion at the relatively large spin-polarization. Corresponding dispersion dependencies are presented and analyzed.

  19. Structure of low-lying states in 140Sm studied by Coulomb excitation

    Science.gov (United States)

    Klintefjord, M.; Hadyńska-KlÈ©k, K.; Görgen, A.; Bauer, C.; Bello Garrote, F. L.; Bönig, S.; Bounthong, B.; Damyanova, A.; Delaroche, J.-P.; Fedosseev, V.; Fink, D. A.; Giacoppo, F.; Girod, M.; Hoff, P.; Imai, N.; Korten, W.; Larsen, A.-C.; Libert, J.; Lutter, R.; Marsh, B. A.; Molkanov, P. L.; Naïdja, H.; Napiorkowski, P.; Nowacki, F.; Pakarinen, J.; Rapisarda, E.; Reiter, P.; Renstrøm, T.; Rothe, S.; Seliverstov, M. D.; Siebeck, B.; Siem, S.; Srebrny, J.; Stora, T.; Thöle, P.; Tornyi, T. G.; Tveten, G. M.; Van Duppen, P.; Vermeulen, M. J.; Voulot, D.; Warr, N.; Wenander, F.; De Witte, H.; Zielińska, M.

    2016-05-01

    The electromagnetic structure of 140Sm was studied in a low-energy Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE facility at CERN. The 2+ and 4+ states of the ground-state band and a second 2+ state were populated by multistep excitation. The analysis of the differential Coulomb excitation cross sections yielded reduced transition probabilities between all observed states and the spectroscopic quadrupole moment for the 21+ state. The experimental results are compared to large-scale shell model calculations and beyond-mean-field calculations based on the Gogny D1S interaction with a five-dimensional collective Hamiltonian formalism. Simpler geometric and algebraic models are also employed to interpret the experimental data. The results indicate that 140Sm shows considerable γ softness, but in contrast to earlier speculation no signs of shape coexistence at low excitation energy. This work sheds more light on the onset of deformation and collectivity in this mass region.

  20. The structure of low-lying states in ${}^{140}$Sm studied by Coulomb excitation

    CERN Document Server

    Klintefjord, M; Görgen, A; Bauer, C; Garrote, F L Bello; Bönig, S; Bounthong, B; Damyanova, A; Delaroche, J-P; Fedosseev, V; Fink, D A; Giacoppo, F; Girod, M; Hoff, P; Imai, N; Korten, W; Larsen, A C; Libert, J; Lutter, R; Marsh, B A; Molkanov, P L; Naïdja, H; Napiorkowski, P; Nowacki, F; Pakarinen, J; Rapisarda, E; Reiter, P; Renstrøm, T; Rothe, S; Seliverstov, M D; Siebeck, B; Siem, S; Srebrny, J; Stora, T; Thöle, P; Tornyi, T G; Tveten, G M; Van Duppen, P; Vermeulen, M J; Voulot, D; Warr, N; Wenander, F; De Witte, H; Zielińska, M

    2016-01-01

    The electromagnetic structure of $^{140}$Sm was studied in a low-energy Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE facility at CERN. The $2^+$ and $4^+$ states of the ground-state band and a second $2^+$ state were populated by multi-step excitation. The analysis of the differential Coulomb excitation cross sections yielded reduced transition probabilities between all observed states and the spectroscopic quadrupole moment for the $2_1^+$ state. The experimental results are compared to large-scale shell model calculations and beyond-mean-field calculations based on the Gogny D1S interaction with a five-dimensional collective Hamiltonian formalism. Simpler geometric and algebraic models are also employed to interpret the experimental data. The results indicate that $^{140}$Sm shows considerable $\\gamma$ softness, but in contrast to earlier speculation no signs of shape coexistence at low excitation energy. This work sheds more light on the onset of deformation and collectivit...

  1. The simplest model for non-congruent fluid-fluid phase transition in Coulomb system

    CERN Document Server

    Stroev, Nikita

    2015-01-01

    The simplest model for non-congruent phase transition of gas-liquid type was developed in frames of modified model with no associations of a binary ionic mixture (BIM) on a homogeneous compressible ideal background (or non-ideal) electron gas /BIM($\\sim$)/. The analytical approximation for equation of state equation of state of Potekhin and Chabrier of fully ionized electron-ionic plasma was used for description of the ion-ion correlations (Coulomb non-ideality) in combination with ``linear mixture'' (LM) approximation. Phase equilibrium for the charged species was calculated according to the Gibbs-Guggenheim conditions. The presently considered BIM($\\sim$) model allows to calculate full set of parameters for phase boundaries of non-congruent variant of phase equilibrium and to study all features for this non-congruent phase transition realization in Coulomb system in comparison with the simpler (standard) forced-congruent evaporation mode. In particular, in BIM($\\sim$) there were reproduced two-dimensional r...

  2. Dynamics of He2++H ionization with exponential cosine-screened Coulomb potential

    International Nuclear Information System (INIS)

    Dynamics of He2++H ionization in dense quantum plasmas (DQPs) has been studied by the classical trajectory Monte Carlo method. The interactions between charged particles have been described by the exponential cosine-screened Coulomb potential. It is found that ionization cross sections in plasma environments are obviously larger than those in plasma-free environments due to the screening effects. Cross sections for H+ also have been calculated for comparison. For H+, cross sections increase with the increase of screening effects. However, for He2+, cross sections begin to decrease in strong screening effects at intermediate energies. Furthermore, He2+ impact ionization cross sections in weakly coupled plasmas (WCPs) also have been calculated. The interactions have been described by the static screened Coulomb potential. It is found that when screening effects are weak, cross sections in DQPs and WCPs are approximately the same. As screening effects increase, cross sections in DQPs become larger than those in WCPs at high energies. However, when screening effects are strong enough, cross sections in DQPs become smaller than those in WCPs at low and intermediate energies. (paper)

  3. Coulomb excitation of neutron-rich odd-$A$ Cd isotopes

    CERN Multimedia

    Reiter, P; Kruecken, R; Gernhaeuser, R A; Kroell, T; Leske, J; Marginean, N M

    We propose to study excited states in the odd-${A}$ isotopes $^{123,125,127}$Cd by ${\\gamma}$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to determine the B(E2) values connecting excited states with the ground state as well as the long-lived (11/2$^{-}$) isomer. The proposed study profits from the unique capability of ISOLDE to produce beams containing Cd in the ground state or in the isomeric state. Our recent results on the neutron-rich even-A Cd nuclei appear to show that these nuclei may possess some collectivity beyond that calculated by modern shell-model predictions. Beyond-mean-field calculations also predict these nuclei to be weakly deformed. These facets are surprising considering their proximity to the doubly magic $^{132}$Sn. Coulomb-excitation studies of odd-${A}$ Cd isotopes may give a unique insight into the deformation-driving roles played by different orbits in this region. Such studies of the onset of collectivity become especially important in light of recent...

  4. Superconformal models and the supersymmetric coulomb gas

    International Nuclear Information System (INIS)

    The obtention of the supersymmetric 19-vertex model from an inhomogeneous 6-vertex model, is discussed. The 19-vertex model is considered the underlying theory and applied to calculate the partition function of the torus. A similar scheme to that for the critical models obtention, concerning the restriction procedure at special points of the gaussian line (of the 6-vertex model) is used. The critical line, in the supersymmetric model, is described by a free superfield and related to the XY model. The ''fused'' lattice models are outlined. It is shown that the results can be generalized to the models obtained by SU(2) coset construction

  5. Fast Electron Repulsion Integrals for Molecular Coulomb Sturmians

    DEFF Research Database (Denmark)

    Avery, James Emil

    hyperspherical harmonics. A rudimentary software library has been implemented and preliminary benchmarks indicate very good performance: On average 40 ns, or approximately 80 clock cycles, per electron repulsion integral. This makes molecular Coulomb Sturmians competitive with Gaussian type orbitals in terms of...

  6. Chaos in a coulombic muffin-tin potential

    International Nuclear Information System (INIS)

    We study the two-dimensional classical scattering dynamics by a Muffin-Tin potential with 3 Coulomb singularities. A complete symbolic dynamics for the periodic orbits is derivd. The classical trajectories are shown to be hyperbolic everywhere in phase space and to carry no conjugate points. (orig.)

  7. Coulomb displacement energies between analog levels for 44 < = A < = 239

    International Nuclear Information System (INIS)

    Experimental Coulomb displacement energie ΔEsub(C) between isobaric analog levels are tabulated for 44 <- A <- 239, extending recent work in which similar data were presented for 3 <- A <- 45. An overall parametrization in anti-Z/A sup(1/3) and uniform radius parameters rsub(o) are given

  8. Analytic structure of many-body Coulombic wave functions

    DEFF Research Database (Denmark)

    Fournais, Søren; Hoffmann-Ostenhof, Maria; Hoffmann-Ostenhof, Thomas; Sørensen, Thomas Østergaard

    2009-01-01

    We investigate the analytic structure of solutions of non-relativistic Schrödinger equations describing Coulombic many-particle systems. We prove the following: Let ψ(x) with denote an N-electron wavefunction of such a system with one nucleus fixed at the origin. Then in a neighbourhood of a...

  9. Limits to Electron Beam Emittance from Stochastic Coulomb Interactions

    International Nuclear Information System (INIS)

    Dense electron beams can now be generated on an ultrafast timescale using laser driven photo-cathodes and these are used for a range of applications from ultrafast electron defraction to free electron lasers. Here we determine a lower bound to the emittance of an electron beam limited by fundamental stochastic Coulomb interactions.

  10. Existence of the thermodynamic limit for disordered quantum Coulomb systems

    CERN Document Server

    Blanc, Xavier

    2012-01-01

    Following a recent method introduced by C. Hainzl, J.P. Solovej and the second author of this article, we prove the existence of the thermodynamic limit for a system made of quantum electrons, and classical nuclei whose positions and charges are randomly perturbed in an ergodic fashion. All the particles interact through Coulomb forces.

  11. Strong impact of protonation and deprotonation on intermolecular Coulombic decay

    International Nuclear Information System (INIS)

    Intermolecular Coulombic decay (ICD) is an ultrafast relaxation mechanism of a highly excited system embedded in a chemical environment. Our theoretical investigation of ammonia clusters shows that the ICD efficiency can be regulated by protonation or deprotonation. It is suggested that by varying ICD rate through changing the environmental pH value a control over the relaxation dynamics can be achieved.

  12. Plasmon-mediated Coulomb drag between graphene waveguides

    DEFF Research Database (Denmark)

    Shylau, Artsem A.; Jauho, Antti-Pekka

    2014-01-01

    We analyze theoretically charge transport in Coulomb coupled graphene waveguides (GWGs). The GWGs are defined using antidot lattices, and the lateral geometry bypasses many technological challenges of earlier designs. The drag resistivity ρD, which is a measure of the many-particle interactions...

  13. Limits to Electron Beam Emittance from Stochastic Coulomb Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Coleman-Smith, Christopher; Padmore, Howard A.; Wan, Weishi

    2008-08-22

    Dense electron beams can now be generated on an ultrafast timescale using laser driven photo-cathodes and these are used for a range of applications from ultrafast electron defraction to free electron lasers. Here we determine a lower bound to the emittance of an electron beam limited by fundamental stochastic Coulomb interactions.

  14. Coulomb potential from a particle in uniform ultrarelativistic motion

    OpenAIRE

    Baltz, A. J.

    1995-01-01

    The Coulomb potential produced by an ultrarelativistic particle (such as a heavy ion) in uniform motion is shown in the appropriate gauge to factorize into a longitudinal Dirac delta function of (z - t) times the simple two dimensional potential solution in the transverse direction. This form makes manifest the source of the energy independence of the interaction.

  15. Solutions of the two-body Salpeter equation under the Coulomb and exponential potential for any l state with Laplace approach

    International Nuclear Information System (INIS)

    In this paper we have solved the two-body spinless-Salpeter (SS) equation under the Coulomb and exponential type potentials. We have applied an approximation for the centrifugal term in our calculations. The energy eigenvalues and the corresponding eigenfunctions are reported by using the Laplace transform approach for any n, l states. (authors)

  16. On two variants of solving the eigenvalue problem for a system of second-order differential equations in the method of many-dimensional angular coulomb functions

    International Nuclear Information System (INIS)

    Consideration is being given to application of two numerical methods for solving eigenvalue problem a system of usual differential equations, ocurring in multi-electron theory of atom when using the method of many-dimensional angular Coulomb functions, Galerkin method, and the method of Sturm function expansion. Results of numerical calculations, illustrating the convergence of both methods are presented

  17. Green's Function Monte Carlo calculations of light nuclei

    International Nuclear Information System (INIS)

    Recently, Green's Function Monte Carlo methods have been developed which enable one to perform exact calculations for the ground states of three and four body nuclei. These methods allow the alpha particle to be used as a testing ground for a variety of two- and three-nucleon interaction models, both in terms of their ground state energies and a variety of other ground state expectation values. We present a brief review of GFMC methods as applied to light nuclei, including recent improvements of the algorithm and a discussion of the prospects for the inclusion of momentum-dependent terms. We then discuss results for the ground state energy, one- and two-body density distributions, D-state probability, coulomb sum rule, and momentum distributions. The GFMC results are compared to experimental results and to variational Monte Carlo calculations. 27 refs., 5 figs., 1 tab

  18. A Note on AdS/SYM Correspondence on the Coulomb Branch

    OpenAIRE

    Wu, Yi-Yen

    1998-01-01

    We study Maldacena's conjecture and the AdS/SYM correspondence on the Coulomb branch. Several interesting aspects of this conjectured AdS/SYM correspondence on the Coulomb branch are pointed out and clarified.

  19. On the Coulomb gauge quark propagator

    International Nuclear Information System (INIS)

    Full text: A solution of the quark Dyson-Schwinger equation including transverse gluons is presented. The corresponding retardation effects in the quark propagator are discussed. Especially, their effects on confinement properties and dynamical mass generation are described. (author)

  20. Fermi-edge singularity in one-dimensional electron systems with long-range Coulomb interactions

    International Nuclear Information System (INIS)

    Effects of long-range Coulomb interactions on the Fermi-edge singularity in optical spectra are investigated theoretically for one-dimensional spin-1/2 fermion systems with the use of the Tomonaga-Luttinger bosonization technique. Low-energy excitation spectrum near the Fermi level shows that dispersion of the charge-density fluctuation remains gapless but is nonlinear when the electron-electron (e-e) Coulomb interaction is of the x-1 type (i.e., an infinite force range). Temporal behavior of the current-current correlation function is calculated analytically for arbitrary force ranges, λe and λh, of the e-e and the electron-hole (e-h) Coulomb interactions. (i) When both the e-e and the e-h interactions have large but finite force ranges (λehmax[λe,λh]/vF. Corresponding optical spectrum near the Fermi edge (within an energy range of ℎvF/max[λe,λh]) exhibits the power-law divergence or the power-law convergence, which is an ordinary Fermi-edge singularity. (ii) When either the e-e or the e-h interaction is of the x-1 type (i.e., λe→∞ and/or λh→∞), an exponent of the correlation function is dependent on time to lead the faster decay than that of any power laws. Then the optical spectra show no power law dependence and always converge (become zero) at the Fermi edge, which is in striking contrast to the ordinary power-law singularity

  1. Obtaining Empirical Validation of Shape-Coexistence in the Mass 70 Region: Coulomb Excitation of a Radioactive Beam of $^{70}$Se

    CERN Multimedia

    Andreoiu, C; Paul, E S; Czosnyka, T; Hammond, N

    2002-01-01

    We propose to study the Coulomb excitation of a radioactive beam of $^{70}$Se at 2.2 MeV/u obtained from the REX-ISOLDE facility in order to determine the sign of the quadrupole moment and, hence, the sign of the quadrupole deformation. Calculations suggest a 33~\\% sensitivity in Coulomb excitation yield for a nickel target depending on whether the nuclear shape is oblate or prolate. Such a determination would provide compelling evidence for the presence of oblate shapes in the vicinity of N=Z=34.

  2. Effects of alternating coulomb and resonance interactions in correlated one-dimensional diatomic systems

    International Nuclear Information System (INIS)

    The diatomic-chain model of mixed-stack molecular crystal is studied accounting for the electron correlation and lattice relaxation. Energetics, Peierls distorsion and charge transfer are calculated by the use of optimized-germinal technique. The realistic case of Hubbard electron repulsion on donors stronger than on acceptors is considered, it is shown that taking into account this difference improves the predictions of dimerization properties. The limiting case of correlated donor-acceptor dimers that interact only through Coulomb field is considered analytically; it is found that interdimer hopping is essential for adequate predictions of characteristics of neutral-to-ionic phase transition. Calculations of broken-symmetry states of the correlated chain show that metastable solitons with excitation energy close to transfer integral are possible near the phase transition point

  3. Coulomb time delays in high harmonic generation

    CERN Document Server

    Smirnova, Olga

    2016-01-01

    Measuring the time it takes to remove an electron from an atom or molecule during photoionization using newly developed attosecond spectroscopies has been a focus of many recent experiments. However, the outcome of such measurement depends on measurement protocols and specific observables available in each particular experiment. One of such protocols relies on high harmonic generation. First, we derive rigorous and general expressions for ionization and recombination times in high harmonic generation experiments. We show that these times are different from, but related to ionization times measured in photo-electron spectroscopy, i.e. using attosecond streak camera, RABBITT and atto-clock methods. Second, we use the Analytical R-Matrix theory (ARM) to calculate these times and compare them with experimental values.

  4. Dynamic polarization potential for heavy-ion scattering induced by multiple Coulomb excitation

    International Nuclear Information System (INIS)

    In heavy-ion reactions the strong electromagnetic interactions lead to Coulomb excitation effects which are superimposed on the nuclear and static-Coulomb forces. In elastic scattering these effects can be accounted for by a long-range dynamic 'Coulomb polarization potential'. For rather heavy ions, multiple Coulomb excitation becomes important. Here the authors report on a polarization potential which takes such multiple processes into account (at least in the semi-classical approximation). (orig./AH)

  5. Coulomb correction to the parameters of the Landau-Pomeranchuk-Migdal effect theory

    International Nuclear Information System (INIS)

    Using the Coulomb correction to the screening angular parameter of the Moliere multiple scattering theory, we obtained analytically and numerically the Coulomb corrections to the quantities of the Migdal LPM-effect theory. We showed that the Coulomb correction to the spectral bremsstrahlung rate allows completely eliminating the discrepancy between the predictions of the LPM effect theory and its measurements

  6. On the role of deformed Coulomb potential in fusion using energy density formalism

    Indian Academy of Sciences (India)

    Lavneet Kaur; Raj Kumari

    2015-10-01

    Using the Skyrme energy density formalism, the effect of deformed Coulomb potential on fusion barriers and fusion cross-sections is studied. Our detailed study reveals that the fusion barriers as well as fusion probabilities depend on the shape deformation (due to deformed Coulomb potential) of the colliding nuclei. However, this dependence due to deformed Coulomb potential is found to be very weak.

  7. Space-Pseudo-Time Method: Application to the One-Dimensional Coulomb Potential and Density Funtional Theory

    Science.gov (United States)

    Weatherford, Charles; Gebremedhin, Daniel

    2016-03-01

    A new and efficient way of evolving a solution to an ordinary differential equation is presented. A finite element method is used where we expand in a convenient local basis set of functions that enforce both function and first derivative continuity across the boundaries of each element. We also implement an adaptive step size choice for each element that is based on a Taylor series expansion. The method is applied to solve for the eigenpairs of the one-dimensional soft-coulomb potential and the hard-coulomb limit is studied. The method is then used to calculate a numerical solution of the Kohn-Sham differential equation within the local density approximation is presented and is applied to the helium atom. Supported by the National Nuclear Security Agency, the Nuclear Regulatory Commission, and the Defense Threat Reduction Agency.

  8. Study of the 17Ne Coulomb dissociation process and its role for the rp process of nucleosynthesis

    International Nuclear Information System (INIS)

    The study of 17Ne Coulomb dissociation process gives us a possibility to study the time-reversed reaction 15O(2p,γ)17Ne, with the detailed balance theorem. This reaction could serve as a bypass of 15O waiting point during the rp process, and move the initial CNO material towards heavier nuclei. The two-proton capture can proceed sequentially or directly from the three-body continuum. And the reaction rate can be enhanced by a few orders of magnitude by taking the three-body continuum into account. The Coulomb dissociation method is the one way to experimentally determine the three-body radiative capture cross section, which is needed to verify theoretical calculations, and which was not experimentally determined yet. The experiment has been performed at the LAND/R3B setup at GSI.

  9. Andreev reflection through a ferromagnet-quantum dot-superconductor system with intradot Coulomb correlations

    Directory of Open Access Journals (Sweden)

    Rudziński Wojciech

    2013-01-01

    Full Text Available Spin-dependent tunneling through a quantum dot coupled to one ferromagnetic and one superconducting electrodes is studied in the Andreev reflection (AR regime. Electrical conductance is calculated within the nonequilibrium Green function technique. Effects due to a competition between the Coulomb correlations on the dot and intradot spin-flip processes are considered in the linear transport regime and for different coupling strengths between the dot and the external electrodes. It is shown that when a coherent spin rotation is present on the dot, Coulomb interactions may lead to a significant enhancement of the AR tunneling current and even to the perfect AR transmission. Origin of occurrence of a variety of the multipeak structure of the linear conductance is also discussed.

  10. Coulomb excitation of exotic nuclei at REX-ISOLDE with MINIBALL

    International Nuclear Information System (INIS)

    In this contribution nuclear structure studies with post-accelerated radioactive ion beams from the REX-ISOLDE facility at CERN are presented. The method employed is γ-ray spectroscopy with the MINIBALL array following 'safe' Coulomb excitation. The highly efficient MINIBALL array consists of 8 triple clusters of six-fold segmented HPGe detectors. Recent results concerning the investigation of nuclear shapes are presented and discussed. These results include studies on deformation in 94,96Kr nuclei, on quadrupole collectivity around 132Sn, on shape coexistence in neutron-deficient Hg, Po and Rn isotopes, and on octupole states in 122Rn and 224Ra nuclei

  11. Nonperturbative study of the four-point heavy quark Green's functions in Coulomb gauge

    CERN Document Server

    Popovici, Carina; Reinhardt, Hugo

    2011-01-01

    The heavy quark sector of Coulomb gauge QCD is investigated, by making a heavy quark mass expansion of the QCD action and restricting to the leading order. With the truncation of the Yang-Mills sector to include only dressed two-point functions, we study the Dyson-Schwinger equations for the four-point quark Green's functions (proper and amputated). In this limit, we provide an exact solution for the four-point quark Green's functions and show that the corresponding poles relate to the bound state energy of the heavy quark system. Moreover, a natural separation between the physical and unphysical poles in the Green's functions emerges.

  12. Coherence-Like States of Two Coulomb-Correlated Ions Confined in a Paul Trap

    Institute of Scientific and Technical Information of China (English)

    LI Hui; HAI Wen-Hua; CHEN Wen-Qin; XU Jun

    2007-01-01

    We report the n×n'coherence-like state solutions in the cases of n,n'=1,2,…for the system including two Coulomb-correlated ions confined in a one-dimensional Paul trap with a time-dependent harmonic potential.One of the n'exact solutions of the centre-of-mass motion describes a generalized coherent state.For a small driving strength the n approximate solutions of relative motion are constructed,which describe the coherent oscillations of the two ions around the classical equilibrium position.

  13. Exchange and correlation effects on the plasmon dispersions and the Coulomb drag in low-density electron bilayers

    OpenAIRE

    Badalyan, S. M.; Kim, C. S.; Vignale, G.; Senatore, G.

    2005-01-01

    We investigate the effect of exchange and correlation (xc) on the plasmon spectrum and the Coulomb drag between spatially separated low-density two-dimensional electron layers. We adopt a new approach, which employs dynamic xc kernels in the calculation of the bi-layer plasmon spectra and of the plasmon-mediated drag, and static many-body local field factors in the calculation of the particle-hole contribution to the drag. The spectrum of bi-layer plasmons and the drag resistivity are calcula...

  14. Coulomb versus nuclear break-up of sup 1 sup 1 Be halo nucleus in a nonperturbative framework

    CERN Document Server

    Fallot, M; Lacroix, D; Chomaz, P; Margueron, J

    2002-01-01

    The sup 1 sup 1 Be break-up is calculated at 41 MeV per nucleon incident energy on different targets using a nonperturbative time-dependent quantum calculation. The evolution of the neutron halo wave function shows an emission of neutron at large angles for grazing impact parameters and at forward angles for large impact parameters. The neutron angular distribution is deduced for the different targets and compared to experimental data. We emphasize the diversity of diffraction mechanisms, in particular we discuss the interplay of the nuclear effects such as the towing mode and the Coulomb break-up. A good agreement is found with experimental data.

  15. Coulomb excitation of a 242Am isomeric target: E2 and E3 strengths, rotational alignment, and collective enhancement

    International Nuclear Information System (INIS)

    A 98% pure 242mAm (K=5-, t1/2=141 years) isomeric target was Coulomb excited with a 170.5-MeV 40Ar beam. The selectivity of Coulomb excitation, coupled with the sensitivity of Gammasphere plus CHICO, was sufficient to identify 46 new states up to spin 18(ℎ/2π) in at least four rotational bands; 11 of these new states lie in the isomer band, 13 in a previously unknown yrast Kπ=6- rotational band, and 13 in a band tentatively identified as the predicted yrast Kπ=5+ band. The rotational bands based on the Kπ=5- isomer and the 6- bandhead were populated by Coulomb excitation with unexpectedly equal cross sections. The γ-ray yields are reproduced by Coulomb excitation calculations using a two-particle plus rotor model (PRM), implying nearly complete ΔK=1 mixing of the two almost-degenerate rotational bands, but recovering the Alaga rule for the unperturbed states. The degeneracy of the 5- and 6- bands allows for precise determination of the mixing interaction strength V, which approaches the strong-mixing limit; this agrees with the 50% attenuation of the Coriolis matrix element assumed in the model calculations. The fractional admixture of the IKπ=66- state in the nominal 65- isomer band state is measured within the PRM as 45.6-1.1+0.3%. The E2 and M1 strengths coupling the 5- and 6- bands are enhanced significantly by the mixing, while E1 and E2 couplings to other low-K bands are not measurably enhanced. The yields of the 5+ band are reproduced by an E3 strength of ≅15 W.u., competitive with the interband E2 strength. Alignments of the identified two-particle Nilsson states in 242Am are compared with the single-particle alignments in 241Am.

  16. Sources, potentials and fields in Lorenz and Coulomb gauge: Cancellation of instantaneous interactions for moving point charges

    International Nuclear Information System (INIS)

    We investigate the coupling of the electromagnetic sources (charge and current densities) to the scalar and vector potentials in classical electrodynamics, using Green function techniques. As is well known, the scalar potential shows an action-at-a-distance behavior in Coulomb gauge. The conundrum generated by the instantaneous interaction has intrigued physicists for a long time. Starting from the differential equations that couple the sources to the potentials, we here show in a concise derivation, using the retarded Green function, how the instantaneous interaction cancels in the calculation of the electric field. The time derivative of a specific additional term in the vector potential, present only in Coulomb gauge, yields a supplementary contribution to the electric field which cancels the gradient of the instantaneous Coulomb gauge scalar potential, as required by gauge invariance. This completely eliminates the contribution of the instantaneous interaction from the electric field. It turns out that a careful formulation of the retarded Green function, inspired by field theory, is required in order to correctly treat boundary terms in partial integrations. Finally, compact integral representations are derived for the Liénard–Wiechert potentials (scalar and vector) in Coulomb gauge which manifestly contain two compensating action-at-a-distance terms. - Highlights: ► We investigate action-at-a-distance effects in electrodynamics in detail. ► We calculate the instantaneous interactions for scalar and vector potentials. ► The cancellation mechanism involves the retarded Green function. ► The mechanism is confirmed on the example of moving point charges. ► The Green function has to be treated with care for nontrivial boundary terms.

  17. Comment on "Structure effects in the $^{15}$N(n,$\\gamma$)$^{16}$N radiative capture reaction from the Coulomb dissociation of $^{16}$N"

    CERN Document Server

    Mohr, Peter

    2016-01-01

    In their recent study Neelam, Shubhchintak, and Chatterjee have claimed that "it would certainly be useful to perform a Coulomb dissociation experiment to find the low energy capture cross section for the reaction" $^{15}$N(n,$\\gamma$)$^{16}$N. However, it is obvious that a Coulomb dissociation experiment cannot constrain this capture cross section because the dominating branchings of the capture reaction lead to excited states in $^{16}$N which do not contribute in a Coulomb dissociation experiment. An estimate of the total $^{15}$N(n,$\\gamma$)$^{16}$N cross section from Coulomb dissociation of $^{16}$N requires a precise knowledge of the $\\gamma$-ray branchings in the capture reaction. Surprisingly, the calculation of Neelam, Shubhchintak, and Chatterjee predicts a strongly energy-dependent ground state branching of the order of 0.05\\% to 0.6\\% at energies between 100 and 500 keV which is almost 2 orders of magnitude below calculations in the direct capture model. Additionally, this calculation of Neelam, S...

  18. Charge-carrier dynamics and Coulomb effects in semiconductor tetrapods

    International Nuclear Information System (INIS)

    In this thesis the Coulomb interaction and its influence on localization effects and dynamics of charge carriers in semiconductor nanocrystals were studied. In the studied nanostructures it deals with colloidal tetrapod heterostructures, which consist of a cadmium selenide (CdSe) core and four tetraedrical grown cadmium sulfide (CdS) respectively cadmium telluride (CdTe) legs, which exhibit a type-I respectively type-II band transition. The dynamics and interactions were studied by means of photoluminescence (PL) and absorption measurements both on the ensemble and on single nanoparticles, as well as time-resolved PL and transient absorption spectroscopy. Additionally theoretical simulations of the wave-function distributions were performed, which are based on the effective-mass approximation. The special band structure of the CdSe/CdS tetrapods offers a unique possibility to study the Coulomb interaction. The flat conduction band in these heterostructures makes the electron via the Coulomb interaction sensitive to the localization position of the hole within the structure. The valence band has instead a potential maximum in the CdSe, which leads to a directed localization of the hole and the photoluminescence of the core. Polarization-resolved measurements showed hereby an anisotropy of the photoluminescence, which could be explained by means of simulations of the wave-function distribution with an asymmetry at the branching point. Charge-carrier localization occur mainly both in longer structures and in trap states in the CdS leg and can be demonstrated in form of a dual emission from a nanocrystal. The charge-carrier dynamics of electron and hole in tetrapods is indeed coupled by the Coulomb interaction, however it cannot be completely described in an exciton picture. The coupled dynamics and the Coulomb interaction were studied concerning a possible influence of the geometry in CdSe/CdS nanorods and compared with those of the tetrapods. The interactions of the

  19. Coulomb Excitation of 68,70Cu First Use of Postaccelerated Isomeric Beams

    CERN Document Server

    Stefanescu, I

    2007-01-01

    We report on the first low-energy Coulomb excitation measurements with radioactive Iπ=6- beams of odd-odd nuclei 68,70Cu. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2.83  MeV/nucleon. γ rays were detected with the MINIBALL spectrometer. The 6- beam was used to study the multiplet of states (3-, 4-, 5-, 6-) arising from the π2p3/2ν1g9/2 configuration. The 4- state of the multiplet was populated via Coulomb excitation and the B(E2;6-→4-) value was determined in both nuclei. The results obtained illustrate the fragile stability of the Z=28 shell and N=40 subshell closures. A comparison with large-scale shell-model calculations using the 56Ni core shows the importance of the proton excitations across the Z=28 shell gap to the understanding of the nuclear structure in the neutron-rich nuclei with N≈40.

  20. Low-energy Coulomb excitation of neutron-rich zinc isotopes

    CERN Document Server

    Van de Walle, J; Behrens, T; Bildstein, V; Blazhev, A; Cederkäll, J; Clément, E; Cocolios, T E; Davinson, T; Delahaye, P; Eberth, J; Ekström, A; Fedorov, D V; Fedosseev, V; Fraile, L M; Franchoo, S; Gernhäuser, R; Georgiev, G; Habs, D; Heyde, K; Huber, G; Huyse, M; Ibrahim, F; Ivanov, O; Iwanicki, J; Jolie, J; Kester, O; Köster, U; Kröll, T; Krücken, R; Lauer, M; Lisetskiy, A F; Lutter, R; Marsh, B A; Mayet, P; Niedermaier, O; Pantea, M; Raabe, R; Reiter, P; Sawicka, M; Scheit, H; Schrieder, G; Schwalm, D; Seliverstov, M D; Sieber, T; Sletten, G; Smirnova, N; Stanoiu, M; Stefanescu, I; Thomas, J C; Valiente-Dobón, J J; Van Duppen, P; Verney, D; Voulot, D; Warr, N; Weisshaar, D; Wenander, F; Wolf, B H; Zielinska, M

    2009-01-01

    At the radioactive ion beam facility REX-ISOLDE, neutron-rich zinc isotopes were investigated using low-energy Coulomb excitation. These experiments have resulted in B(E2,20) values in 74-80Zn, B(E2,42) values in 74,76Zn and the determination of the energy of the first excited 2 states in 78,80Zn. The zinc isotopes were produced by high-energy proton- (A=74,76,80) and neutron- (A=78) induced fission of 238U, combined with selective laser ionization and mass separation. The isobaric beam was postaccelerated by the REX linear accelerator and Coulomb excitation was induced on a thin secondary target, which was surrounded by the MINIBALL germanium detector array. In this work, it is shown how the selective laser ionization can be used to deal with the considerable isobaric beam contamination and how a reliable normalization of the experiment can be achieved. The results for zinc isotopes and the N=50 isotones are compared to collective model predictions and state-of-the-art large-scale shell-model calculations, i...