Sensitivity of electrospray molecular dynamics simulations to long-range Coulomb interaction models.

Science.gov (United States)

Mehta, Neil A; Levin, Deborah A

2018-03-01

Molecular dynamics (MD) electrospray simulations of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF_{4}) ion liquid were performed with the goal of evaluating the influence of long-range Coulomb models on ion emission characteristics. The direct Coulomb (DC), shifted force Coulomb sum (SFCS), and particle-particle particle-mesh (PPPM) long-range Coulomb models were considered in this work. The DC method with a sufficiently large cutoff radius was found to be the most accurate approach for modeling electrosprays, but, it is computationally expensive. The Coulomb potential energy modeled by the DC method in combination with the radial electric fields were found to be necessary to generate the Taylor cone. The differences observed between the SFCS and the DC in terms of predicting the total ion emission suggest that the former should not be used in MD electrospray simulations. Furthermore, the common assumption of domain periodicity was observed to be detrimental to the accuracy of the capillary-based electrospray simulations.

Using the Screened Coulomb Potential to Illustrate the Variational Method

Science.gov (United States)

Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

2012-01-01

The screened Coulomb potential, or Yukawa potential, is used to illustrate the application of the single and linear variational methods. The trial variational functions are expressed in terms of Slater-type functions, for which the integrals needed to carry out the variational calculations are easily evaluated in closed form. The variational…

An algorithm for computing screened Coulomb scattering in GEANT4

Energy Technology Data Exchange (ETDEWEB)

Mendenhall, Marcus H. [Vanderbilt University Free Electron Laser Center, P.O. Box 351816 Station B, Nashville, TN 37235-1816 (United States)]. E-mail: marcus.h.mendenhall@vanderbilt.edu; Weller, Robert A. [Department of Electrical Engineering and Computer Science, Vanderbilt University, P.O. Box 351821 Station B, Nashville, TN 37235-1821 (United States)]. E-mail: robert.a.weller@vanderbilt.edu

2005-01-01

An algorithm has been developed for the GEANT4 Monte-Carlo package for the efficient computation of screened Coulomb interatomic scattering. It explicitly integrates the classical equations of motion for scattering events, resulting in precise tracking of both the projectile and the recoil target nucleus. The algorithm permits the user to plug in an arbitrary screening function, such as Lens-Jensen screening, which is good for backscattering calculations, or Ziegler-Biersack-Littmark screening, which is good for nuclear straggling and implantation problems. This will allow many of the applications of the TRIM and SRIM codes to be extended into the much more general GEANT4 framework where nuclear and other effects can be included.

An algorithm for computing screened Coulomb scattering in GEANT4

International Nuclear Information System (INIS)

Mendenhall, Marcus H.; Weller, Robert A.

2005-01-01

An algorithm has been developed for the GEANT4 Monte-Carlo package for the efficient computation of screened Coulomb interatomic scattering. It explicitly integrates the classical equations of motion for scattering events, resulting in precise tracking of both the projectile and the recoil target nucleus. The algorithm permits the user to plug in an arbitrary screening function, such as Lens-Jensen screening, which is good for backscattering calculations, or Ziegler-Biersack-Littmark screening, which is good for nuclear straggling and implantation problems. This will allow many of the applications of the TRIM and SRIM codes to be extended into the much more general GEANT4 framework where nuclear and other effects can be included

Relativity, nuclear polarizability, and screening in sub-Coulomb elastic scattering

International Nuclear Information System (INIS)

Lynch, W.G.; Tsang, M.B.; Bhang, H.C.; Cramer, J.G.; Puigh, R.J.

Elastic scattering of p-shell nuclear projectiles from 208 Pb has been examined for deviations from Rutherford scattering. Four effects can be important: atomic screening, vacuum polarization, nuclear polarizability and a relativistic effect of dynamical origin. The presence of atomic screening, nuclear polarizability and the relativistic effect was observed thus constituting the first measurement of this relativistic effect using complex nuclei and the first measurement of this relativistic effect using complex nuclei and the first measurement of nuclear polarizability in an external Coulomb field

Coulomb breakup of 31Ne using finite range DWBA

International Nuclear Information System (INIS)

Shubhchintak; Chatterjee, R.

2013-01-01

Coulomb breakup of nuclei away from the valley of stability have been one of the most successful probes to unravel their structure. However, it is only recently that one is venturing into medium mass nuclei like 23 O and 31 Ne. This is a very new and exciting development which has expanded the field of light exotic nuclei to the deformed medium mass region. In this contribution, an extension of the previously proposed theory of Coulomb breakup within the post-form finite range distorted wave Born approximation to include deformation of the projectile is reported

Evaluation of the Coulomb logarithm using cutoff and screened Coulomb interaction potentials

International Nuclear Information System (INIS)

Ordonez, C.A.; Molina, M.I.

1994-01-01

The Coulomb logarithm is a fundamental plasma parameter which is commonly derived within the framework of the binary collision approximation. The conventional formula for the Coulomb logarithm, λ=ln Λ, takes into account a pure Coulomb interaction potential for binary collisions and is not accurate at small values (λ D in place of λ D (the Debye length) in the conventional formula for the Coulomb logarithm

Influence of long-range Coulomb interaction in velocity map imaging.

Science.gov (United States)

Barillot, T; Brédy, R; Celep, G; Cohen, S; Compagnon, I; Concina, B; Constant, E; Danakas, S; Kalaitzis, P; Karras, G; Lépine, F; Loriot, V; Marciniak, A; Predelus-Renois, G; Schindler, B; Bordas, C

2017-07-07

The standard velocity-map imaging (VMI) analysis relies on the simple approximation that the residual Coulomb field experienced by the photoelectron ejected from a neutral or ion system may be neglected. Under this almost universal approximation, the photoelectrons follow ballistic (parabolic) trajectories in the externally applied electric field, and the recorded image may be considered as a 2D projection of the initial photoelectron velocity distribution. There are, however, several circumstances where this approximation is not justified and the influence of long-range forces must absolutely be taken into account for the interpretation and analysis of the recorded images. The aim of this paper is to illustrate this influence by discussing two different situations involving isolated atoms or molecules where the analysis of experimental images cannot be performed without considering long-range Coulomb interactions. The first situation occurs when slow (meV) photoelectrons are photoionized from a neutral system and strongly interact with the attractive Coulomb potential of the residual ion. The result of this interaction is the formation of a more complex structure in the image, as well as the appearance of an intense glory at the center of the image. The second situation, observed also at low energy, occurs in the photodetachment from a multiply charged anion and it is characterized by the presence of a long-range repulsive potential. Then, while the standard VMI approximation is still valid, the very specific features exhibited by the recorded images can be explained only by taking into consideration tunnel detachment through the repulsive Coulomb barrier.

Pairing from dynamically screened Coulomb repulsion in bismuth

Science.gov (United States)

Ruhman, Jonathan; Lee, Patrick A.

2017-12-01

Recently, Prakash et al. have discovered bulk superconductivity in single crystals of bismuth, which is a semimetal with extremely low carrier density. At such low density, we argue that conventional electron-phonon coupling is too weak to be responsible for the binding of electrons into Cooper pairs. We study a dynamically screened Coulomb interaction with effective attraction generated on the scale of the collective plasma modes. We model the electronic states in bismuth to include three Dirac pockets with high velocity and one hole pocket with a significantly smaller velocity. We find a weak-coupling instability, which is greatly enhanced by the presence of the hole pocket. Therefore we argue that bismuth is the first material to exhibit superconductivity driven by retardation effects of Coulomb repulsion alone. By using realistic parameters for bismuth we find that the acoustic plasma mode does not play the central role in pairing. We also discuss a matrix element effect, resulting from the Dirac nature of the conduction band, which may affect Tc in the s -wave channel without breaking time-reversal symmetry.

Effect of long-range repulsive Coulomb interactions on packing structure of adhesive particles.

Science.gov (United States)

Chen, Sheng; Li, Shuiqing; Liu, Wenwei; Makse, Hernán A

2016-02-14

The packing of charged micron-sized particles is investigated using discrete element simulations based on adhesive contact dynamic model. The formation process and the final obtained structures of ballistic packings are studied to show the effect of interparticle Coulomb force. It is found that increasing the charge on particles causes a remarkable decrease of the packing volume fraction ϕ and the average coordination number 〈Z〉, indicating a looser and chainlike structure. Force-scaling analysis shows that the long-range Coulomb interaction changes packing structures through its influence on particle inertia before they are bonded into the force networks. Once contact networks are formed, the expansion effect caused by repulsive Coulomb forces are dominated by short-range adhesion. Based on abundant results from simulations, a dimensionless adhesion parameter Ad*, which combines the effects of the particle inertia, the short-range adhesion and the long-range Coulomb interaction, is proposed and successfully scales the packing results for micron-sized particles within the latest derived adhesive loose packing (ALP) regime. The structural properties of our packings follow well the recent theoretical prediction which is described by an ensemble approach based on a coarse-grained volume function, indicating some kind of universality in the low packing density regime of the phase diagram regardless of adhesion or particle charge. Based on the comprehensive consideration of the complicated inter-particle interactions, our findings provide insight into the roles of short-range adhesion and repulsive Coulomb force during packing formation and should be useful for further design of packings.

Modified Moliere's screening parameter and its impact on multiple coulomb scattering

International Nuclear Information System (INIS)

Striganov, Sergei

2015-01-01

The Moliere approximation of elastic Coulomb scattering cross-sections plays an important role in accurate description of multiple scattering, non-ionisation energy, DPA radiation damage etc. The cross-section depends only on a single parameter that describes the atomic screening. Moliere calculated the screening angle for the Tomas-Fermi distribution of electrons in atoms. In this paper, the screening parameter was recalculated using a more accurate atomic form-factor obtained from the self-consistent Dirac-Hartree-Fock-Slater computations. For relativistic particles, the new screening angle can differ from the Moliere approximation by up to 50%. At the same time, it is rather close to other independent calculations. At low energies, the new screening angle is different for positrons and electrons. The positron screening parameter is much larger than the electron one for heavy nuclei at energies of ∼Z keV. The impact of the screening angle on particle transport and calculated quantities is discussed. (authors)

Coulomb Logarithm in Nonideal and Degenerate Plasmas

Science.gov (United States)

Filippov, A. V.; Starostin, A. N.; Gryaznov, V. K.

2018-03-01

Various methods for determining the Coulomb logarithm in the kinetic theory of transport and various variants of the choice of the plasma screening constant, taking into account and disregarding the contribution of the ion component and the boundary value of the electron wavevector are considered. The correlation of ions is taken into account using the Ornstein-Zernike integral equation in the hypernetted-chain approximation. It is found that the effect of ion correlation in a nondegenerate plasma is weak, while in a degenerate plasma, this effect must be taken into account when screening is determined by the electron component alone. The calculated values of the electrical conductivity of a hydrogen plasma are compared with the values determined experimentally in the megabar pressure range. It is shown that the values of the Coulomb logarithm can indeed be smaller than unity. Special experiments are proposed for a more exact determination of the Coulomb logarithm in a magnetic field for extremely high pressures, for which electron scattering by ions prevails.

Finite-range Coulomb gas models of banded random matrices and quantum kicked rotors.

Science.gov (United States)

Pandey, Akhilesh; Kumar, Avanish; Puri, Sanjay

2017-11-01

Dyson demonstrated an equivalence between infinite-range Coulomb gas models and classical random matrix ensembles for the study of eigenvalue statistics. We introduce finite-range Coulomb gas (FRCG) models via a Brownian matrix process, and study them analytically and by Monte Carlo simulations. These models yield new universality classes, and provide a theoretical framework for the study of banded random matrices (BRMs) and quantum kicked rotors (QKRs). We demonstrate that, for a BRM of bandwidth b and a QKR of chaos parameter α, the appropriate FRCG model has the effective range d=b^{2}/N=α^{2}/N, for large N matrix dimensionality. As d increases, there is a transition from Poisson to classical random matrix statistics.

Bond alternation in the infinite polyene: effect of long range Coulomb interactions

International Nuclear Information System (INIS)

Mazumdar, S.; Campbell, D.K.

1985-01-01

We investigate the effects of long-range Coulomb interactions on bond and site dimerizations in a one-dimensional half-filled band. It is shown that the ground state broken symmetry is determined by two sharp inequalities involving the Coulomb parameters. Broken symmetry with periodicity 2k/sub F/ is guaranteed only if the first inequality (downward convexity of the intersite potential) is obeyed, while the second inequality gives the phase boundary between the bond-dimerized and site-dimerized phases. Application of these inequalities to the Pariser-Parr-Pople model for linear polyenes shows that the infinite polyene has enhanced bond alternation for both Ohno and Mataga-Nishimoto parametrizations of the intersite Coulomb terms. The possible role of distant neighbor interactions in photogeneration experiments is discussed. 26 refs., 3 figs

Electrostatic screening in classical Coulomb fluids: exponential or power-law decay or both? An investigation into the effect of dispersion interactions

International Nuclear Information System (INIS)

Kjellander, Roland

2006-01-01

It is shown that the nature of the non-electrostatic part of the pair interaction potential in classical Coulomb fluids can have a profound influence on the screening behaviour. Two cases are compared: (i) when the non-electrostatic part equals an arbitrary finite-ranged interaction and (ii) when a dispersion r -6 interaction potential is included. A formal analysis is done in exact statistical mechanics, including an investigation of the bridge function. It is found that the Coulombic r -1 and the dispersion r -6 potentials are coupled in a very intricate manner as regards the screening behaviour. The classical one-component plasma (OCP) is a particularly clear example due to its simplicity and is investigated in detail. When the dispersion r -6 potential is turned on, the screened electrostatic potential from a particle goes from a monotonic exponential decay, exp(-κr)/r, to a power-law decay, r -8 , for large r. The pair distribution function acquire, at the same time, an r -10 decay for large r instead of the exponential one. There still remains exponentially decaying contributions to both functions, but these contributions turn oscillatory when the r -6 interaction is switched on. When the Coulomb interaction is turned off but the dispersion r -6 pair potential is kept, the decay of the pair distribution function for large r goes over from the r -10 to an r -6 behaviour, which is the normal one for fluids of electroneutral particles with dispersion interactions. Differences and similarities compared to binary electrolytes are pointed out

Screened Coulomb interactions in metallic alloys. II. Screening beyond the single-site and atomic-sphere approximations

DEFF Research Database (Denmark)

Ruban, Andrei; Simak, S.I.; Korzhavyi, P.A.

2002-01-01

-electron potential and energy. In the case of a random alloy such interactions can be accounted for only by lifting the atomic-sphere and single-site approximations, in order to include the polarization due to local environment effects. Nevertheless, a simple parametrization of the screened Coulomb interactions...... for the ordinary single-site methods, including the generalized perturbation method, is still possible. We obtained such a parametrization for bulk and surface NiPt alloys, which allows one to obtain quantitatively accurate effective interactions in this system....

Fermi-edge singularity in one-dimensional electron systems with long-range Coulomb interactions

International Nuclear Information System (INIS)

Otani, H.; Ogawa, T.

1996-01-01

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, λ e and λ h , 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 (λ e h max[λ e ,λ h ]/v F . Corresponding optical spectrum near the Fermi edge (within an energy range of ℎv F /max[λ e ,λ h ]) 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., λ e →∞ and/or λ h →∞), 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

Coulomb systems seen as critical systems: Finite-size effects in two dimensions

International Nuclear Information System (INIS)

Jancovici, B.; Manificat, G.; Pisani, C.

1994-01-01

It is known that the free energy at criticality of a finite two-dimensional system of characteristic size L has in general a term which behaves like log L as L → ∞; the coefficient of this term is universal. There are solvable models of two-dimensional classical Coulomb systems which exhibit the same finite-size correction (except for its sign) although the particle correlations are short-ranged, i.e., noncritical. Actually, the electrical potential and electrical field correlations are critical at all temperatures (as long as the Coulomb system is a conductor), as a consequence of the perfect screening property of Coulomb systems. This is why Coulomb systems have to exhibit critical finite-size effects

Interplay between short-range correlated disorder and Coulomb interaction in nodal-line semimetals

Science.gov (United States)

Wang, Yuxuan; Nandkishore, Rahul M.

2017-09-01

In nodal-line semimetals, Coulomb interactions and short-range correlated disorder are both marginal perturbations to the clean noninteracting Hamiltonian. We analyze their interplay using a weak-coupling renormalization group approach. In the clean case, the Coulomb interaction has been found to be marginally irrelevant, leading to Fermi liquid behavior. We extend the analysis to incorporate the effects of disorder. The nodal line structure gives rise to kinematical constraints similar to that for a two-dimensional Fermi surface, which plays a crucial role in the one-loop renormalization of the disorder couplings. For a twofold degenerate nodal loop (Weyl loop), we show that disorder flows to strong coupling along a unique fixed trajectory in the space of symmetry inequivalent disorder couplings. Along this fixed trajectory, all symmetry inequivalent disorder strengths become equal. For a fourfold degenerate nodal loop (Dirac loop), disorder also flows to strong coupling, however, the strengths of symmetry inequivalent disorder couplings remain different. We show that feedback from disorder reverses the sign of the beta function for the Coulomb interaction, causing the Coulomb interaction to flow to strong coupling as well. However, the Coulomb interaction flows to strong coupling asymptotically more slowly than disorder. Extrapolating our results to strong coupling, we conjecture that at low energies nodal line semimetals should be described by a noninteracting nonlinear sigma model. We discuss the relation of our results with possible many-body localization at zero temperatures in such materials.

Influence of Coulomb screening on lateral lasing in VECSELs.

Science.gov (United States)

Wang, Chengao; Malloy, Kevin; Sheik-Bahae, Mansoor

2015-12-14

Parasitic lateral lasing in certain optically pumped semiconductor disc lasers drains the gain of the vertical mode and thus causes power scaling degradation and premature rollover in surface emitting operation. We have observed this effect in both multiple quantum wells (MQW) (GaInAs/GaAs) and double heterostructures (DHS) (GaInP/GaAs/GaInP) under pulsed excitation even when the gain chip lateral dimensions are much larger than the diameter of the pump laser. Lateral lasing occurs persistently between cleaved facets at a band-tail wavelength much longer than the peak of the gain. We show that the effect of bandgap renormalization due to Coulomb screening explains this phenomena. Exploiting the simple analytical plasma theory of bulk semiconductors (Banyai & Koch, 1986), we can account for such an effect in double heterostructures.

Thermal algebraic-decay charge liquid driven by competing short-range Coulomb repulsion

Science.gov (United States)

Kaneko, Ryui; Nonomura, Yoshihiko; Kohno, Masanori

2018-05-01

We explore the possibility of a Berezinskii-Kosterlitz-Thouless-like critical phase for the charge degrees of freedom in the intermediate-temperature regime between the charge-ordered and disordered phases in two-dimensional systems with competing short-range Coulomb repulsion. As the simplest example, we investigate the extended Hubbard model with on-site and nearest-neighbor Coulomb interactions on a triangular lattice at half filling in the atomic limit by using a classical Monte Carlo method, and find a critical phase, characterized by algebraic decay of the charge correlation function, belonging to the universality class of the two-dimensional XY model with a Z6 anisotropy. Based on the results, we discuss possible conditions for the critical phase in materials.

Long-range Coulomb interaction effects on the topological phase transitions between semimetals and insulators

Science.gov (United States)

Han, SangEun; Moon, Eun-Gook

2018-06-01

Topological states may be protected by a lattice symmetry in a class of topological semimetals. In three spatial dimensions, the Berry flux around gapless excitations in momentum space concretely defines a chirality, so a protecting symmetry may be referred to as a chiral symmetry. Prime examples include a Dirac semimetal (DSM) in a distorted spinel, BiZnSiO4, protected by a mirror symmetry, and a DSM in Na3Bi , protected by a rotational symmetry. In these states, topology and chiral symmetry are intrinsically tied. In this Rapid Communication, the characteristic interplay between a chiral symmetry order parameter and an instantaneous long-range Coulomb interaction is investigated with the standard renormalization group method. We show that a topological transition associated with chiral symmetry is stable under the presence of a Coulomb interaction and the electron velocity always becomes faster than the one of a chiral symmetry order parameter. Thus, the transition must not be relativistic, which implies that supersymmetry is intrinsically forbidden by the long-range Coulomb interaction. Asymptotically exact universal ratios of physical quantities such as the energy gap ratio are obtained, and connections with experiments and recent theoretical proposals are also discussed.

Scaling behaviour of Fisher and Shannon entropies for the exponential-cosine screened coulomb potential

Science.gov (United States)

Abdelmonem, M. S.; Abdel-Hady, Afaf; Nasser, I.

2017-07-01

The scaling laws are given for the entropies in the information theory, including the Shannon's entropy, its power, the Fisher's information and the Fisher-Shannon product, using the exponential-cosine screened Coulomb potential. The scaling laws are specified, in the r-space, as a function of |μ - μc, nℓ|, where μ is the screening parameter and μc, nℓ its critical value for the specific quantum numbers n and ℓ. Scaling laws for other physical quantities, such as energy eigenvalues, the moments, static polarisability, transition probabilities, etc. are also given. Some of these are reported for the first time. The outcome is compared with the available literatures' results.

Techniques for heavy-ion coupled-channels calculations. I. Long-range Coulomb coupling

International Nuclear Information System (INIS)

Rhoades-Brown, M.; Macfarlane, M.H.; Pieper, S.C.

1980-01-01

Direct-reaction calculations for heavy ions require special computational techniques that take advantage of the physical peculiarities of heavy-ion systems. This paper is the first of a series on quantum-mechanical coupled-channels calculations for heavy ions. It deals with the problems posed by the long range of the Coulomb coupling interaction. Our approach is to use the Alder-Pauli factorization whereby the channel wave functions are expressed as products of Coulomb functions and modulating amplitudes. The equations for the modulating amplitudes are used to integrate inwards from infinity to a nuclear matching radius ( approx. = 20 fm). To adequate accuracy, the equations for the amplitudes can be reduced to first order and solved in first Born approximation. The use of the Born approximation leads to rapid recursion relations for the solutions of the Alder-Pauli equations and hence to a great reduction in computational labor. The resulting coupled-channels Coulomb functions can then be matched in the usual way to solutions of the coupled radial equations in the interior region of r space. Numerical studies demonstrate the reliability of the various techniques introduced

Coulombic charge ice

Science.gov (United States)

McClarty, P. A.; O'Brien, A.; Pollmann, F.

2014-05-01

We consider a classical model of charges ±q on a pyrochlore lattice in the presence of long-range Coulomb interactions. This model first appeared in the early literature on charge order in magnetite [P. W. Anderson, Phys. Rev. 102, 1008 (1956), 10.1103/PhysRev.102.1008]. In the limit where the interactions become short ranged, the model has a ground state with an extensive entropy and dipolar charge-charge correlations. When long-range interactions are introduced, the exact degeneracy is broken. We study the thermodynamics of the model and show the presence of a correlated charge liquid within a temperature window in which the physics is well described as a liquid of screened charged defects. The structure factor in this phase, which has smeared pinch points at the reciprocal lattice points, may be used to detect charge ice experimentally. In addition, the model exhibits fractionally charged excitations ±q/2 which are shown to interact via a 1/r potential. At lower temperatures, the model exhibits a transition to a long-range ordered phase. We are able to treat the Coulombic charge ice model and the dipolar spin ice model on an equal footing by mapping both to a constrained charge model on the diamond lattice. We find that states of the two ice models are related by a staggering field which is reflected in the energetics of these two models. From this perspective, we can understand the origin of the spin ice and charge ice ground states as coming from a dipolar model on a diamond lattice. We study the properties of charge ice in an external electric field, finding that the correlated liquid is robust to the presence of a field in contrast to the case of spin ice in a magnetic field. Finally, we comment on the transport properties of Coulombic charge ice in the correlated liquid phase.

A study of the angular momentum dependence of the phase shift for finite range and Coulomb potentials

International Nuclear Information System (INIS)

Valluri, S.R.; Romo, W.J.

1989-01-01

The dependence of the phase shift δ l (k) on the angular momentum l is investigated. An analytic expression for the derivative of the phase shift with respect to angular momentum is derived for a class of potentials that includes complex and real potentials. The potentials behave like the finite range potential for small r and like a Coulomb potential for large r. Specific examples like the square well, the pure point charge Coulomb and a combination of a square well and the Coulomb potential are analytically treated. Possible applications are briefly indicated. (orig.)

Arbitrary l-wave solutions of the Schroedinger equation for the screen Coulomb potential

International Nuclear Information System (INIS)

Dong, Shishan; Sun, Guohua; Dong, Shihai

2013-01-01

Using improved approximate schemes for centrifugal term and the singular factor 1/r appearing in potential itself, we solve the Schroedinger equation with the screen Coulomb potential for arbitrary angular momentum state l. The bound state energy levels are obtained. A closed form of normalization constant of the wave functions is also found. The numerical results show that our results are in good agreement with those obtained by other methods. The key issue is how to treat two singular points in this quantum system. (author)

Exclusion of nuclear forces in heavy-ion Coulomb excitation and Coulomb fission experiments

International Nuclear Information System (INIS)

Neese, R.E.; Guidry, M.W.

1982-01-01

A simple prescription for estimating the energy at which nuclear forces begin to play a role in heavy-ion Coulomb excitation and Coulomb fission experiments is presented. The method differs from most commonly used recipes in accounting for projectile and target nucleus deformation effects. Using a single adjustable parameter the formula reproduces the energy for the onset of Coulomb-nuclear interference effects for a broad range of heavy-ion systems. It is suggested that most Coulomb fission experiments which have been done involve both Coulomb and nuclear excitation processes and should more properly be termed Coulomb-nuclear fission experiments

Coulomb Effects in Few-Body Reactions

Directory of Open Access Journals (Sweden)

Deltuva A.

2010-04-01

Full Text Available The method of screening and renormalization is used to include the Coulomb interaction between the charged particles in the momentum-space description of three- and four-body nuclear reactions. The necessity for the renormalization of the scattering amplitudes and the reliability of the method is demonstrated. The Coulomb effect on observables is discussed.

Tunable Mobility in Double-Gated MoTe2 Field-Effect Transistor: Effect of Coulomb Screening and Trap Sites.

Science.gov (United States)

Ji, Hyunjin; Joo, Min-Kyu; Yi, Hojoon; Choi, Homin; Gul, Hamza Zad; Ghimire, Mohan Kumar; Lim, Seong Chu

2017-08-30

There is a general consensus that the carrier mobility in a field-effect transistor (FET) made of semiconducting transition-metal dichalcogenides (s-TMDs) is severely degraded by the trapping/detrapping and Coulomb scattering of carriers by ionic charges in the gate oxides. Using a double-gated (DG) MoTe 2 FET, we modulated and enhanced the carrier mobility by adjusting the top- and bottom-gate biases. The relevant mechanism for mobility tuning in this device was explored using static DC and low-frequency (LF) noise characterizations. In the investigations, LF-noise analysis revealed that for a strong back-gate bias the Coulomb scattering of carriers by ionized traps in the gate dielectrics is strongly screened by accumulation charges. This significantly reduces the electrostatic scattering of channel carriers by the interface trap sites, resulting in increased mobility. The reduction of the number of effective trap sites also depends on the gate bias, implying that owing to the gate bias, the carriers are shifted inside the channel. Thus, the number of active trap sites decreases as the carriers are repelled from the interface by the gate bias. The gate-controlled Coulomb-scattering parameter and the trap-site density provide new handles for improving the carrier mobility in TMDs, in a fundamentally different way from dielectric screening observed in previous studies.

Pseudo-Coulomb potential in singlet superconductivity

International Nuclear Information System (INIS)

Daemen, L.L.; Overhauser, A.W.

1988-01-01

Reduction of the screened Coulomb potential parameter μ to μ/sup */ = μ/[1+μ ln(E/sub F//(h/2π)ω/sub D/)] is related to the pair correlation function at r = 0. This correlation function is calculated for both the simple Cooper-pair problem and standard Bardeen-Cooper-Schrieffer (BCS) theory by use of a two-square-well model (with λ and μ describing the attraction and repulsion). Results are compared with values obtained for a one-square-well model (having the suitable net attraction, e.g., λ-μ/sup */ in the BCS case). For the BCS case, the ''true'' pair correlation at r = 0 is reduced by a factor (μ/sup *//μ) 2 relative to the fictitious (one-square-well) value (even though Δ is the same for both models). The reduction factor is typically ≅(1/25. It follows that any short-range attractive contribution to superconducting pairing will suffer a reduction similar to that for the Coulomb repulsion

Accurate collision integrals for the attractive static screened Coulomb potential with application to electrical conductivity

International Nuclear Information System (INIS)

Macdonald, J.

1991-01-01

The results of accurate calculations of collision integrals for the attractive static screened Coulomb potential are presented. To obtain high accuracy with minimal computational cost, the integrals are evaluated by a quadrature method based on the Whittaker cardinal function. The collision integrals for the attractive potential are needed for calculation of the electrical conductivity of a dense fully or partially ionized plasma, and the results presented here are appropriate for the conditions in the nondegenerate envelopes of white dwarf stars. 25 refs

Coulomb-Sturmian separable expansion approach: Three-body Faddeev calculations for Coulomb-like interactions

International Nuclear Information System (INIS)

Papp, Z.; Plessas, W.

1996-01-01

We demonstrate the feasibility and efficiency of the Coulomb-Sturmian separable expansion method for generating accurate solutions of the Faddeev equations. Results obtained with this method are reported for several benchmark cases of bosonic and fermionic three-body systems. Correct bound-state results in agreement with the ones established in the literature are achieved for short-range interactions. We outline the formalism for the treatment of three-body Coulomb systems and present a bound-state calculation for a three-boson system interacting via Coulomb plus short-range forces. The corresponding result is in good agreement with the answer from a recent stochastic-variational-method calculation. copyright 1996 The American Physical Society

Planar density of vacuum charge induced by a supercritical Coulomb potential

Directory of Open Access Journals (Sweden)

V.R. Khalilov

2017-06-01

Full Text Available Analytical expressions for the planar density of an induced vacuum charge are 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 an external electromagnetic field. Induced vacuum charge density is calculated and analyzed in subcritical and supercritical Coulomb potentials for massless and massive fermions. We argue that the virtual and so-called real vacuum polarizations contribute in an induced vacuum charge in a supercritical Coulomb potential. The behavior of the polarization 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. The real vacuum polarization charge density that acquires the quantum electrodynamics vacuum in a supercritical Coulomb potential due to the real vacuum polarization is calculated. 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 supercritical Coulomb impurity.

Planar density of vacuum charge induced by a supercritical Coulomb potential

Energy Technology Data Exchange (ETDEWEB)

Khalilov, V.R., E-mail: khalilov@phys.msu.ru; Mamsurov, I.V.

2017-06-10

Analytical expressions for the planar density of an induced vacuum charge are 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 an external electromagnetic field. Induced vacuum charge density is calculated and analyzed in subcritical and supercritical Coulomb potentials for massless and massive fermions. We argue that the virtual and so-called real vacuum polarizations contribute in an induced vacuum charge in a supercritical Coulomb potential. The behavior of the polarization 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. The real vacuum polarization charge density that acquires the quantum electrodynamics vacuum in a supercritical Coulomb potential due to the real vacuum polarization is calculated. 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 supercritical Coulomb impurity.

Major difference in visible-light photocatalytic features between perfect and self-defective Ta3N5 materials: A screened coulomb hybrid dft investigation

KAUST Repository

Harb, Moussab; Cavallo, Luigi; Basset, Jean-Marie

2014-01-01

theory (DFT, including the perturbation theory DFPT) within the screened coulomb hybrid (HSE06) exchange-correlation formalism. Among the various explored self-defective structures, a strong stabilization is obtained for the configuration displaying a

Coulomb corrections in the low-energy scattering

International Nuclear Information System (INIS)

Mur, V.D.; Popov, V.S.

1985-01-01

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

Integral equation for Coulomb problem

International Nuclear Information System (INIS)

Sasakawa, T.

1986-01-01

For short range potentials an inhomogeneous (homogeneous) Lippmann-Schwinger integral equation of the Fredholm type yields the wave function of scattering (bound) state. For the Coulomb potential, this statement is no more valid. It has been felt difficult to express the Coulomb wave function in a form of an integral equation with the Coulomb potential as the perturbation. In the present paper, the author shows that an inhomogeneous integral equation of a Volterra type with the Coulomb potential as the perturbation can be constructed both for the scattering and the bound states. The equation yielding the binding energy is given in an integral form. The present treatment is easily extended to the coupled Coulomb problems

Dependence of Coulomb Sum Rule on the Short Range Correlation by Using Av18 Potential

Science.gov (United States)

Modarres, M.; Moeini, H.; Moshfegh, H. R.

The Coulomb sum rule (CSR) and structure factor are calculated for inelastic electron scattering from nuclear matter at zero and finite temperature in the nonrelativistic limit. The effect of short-range correlation (SRC) is presented by using lowest order constrained variational (LOCV) method and the Argonne Av18 and Δ-Reid soft-core potentials. The effects of different potentials as well as temperature are investigated. It is found that the nonrelativistic version of Bjorken scaling approximately sets in at the momentum transfer of about 1.1 to 1.2 GeV/c and the increase of temperature makes it to decrease. While different potentials do not significantly change CSR, the SRC improves the Coulomb sum rule and we get reasonably close results to both experimental data and others theoretical predictions.

A novel approach in Eliashberg theory of superconductivity with ab-initio static and dynamic Coulomb interaction applicable for real materials

Energy Technology Data Exchange (ETDEWEB)

Davydov, Arkadiy; Sanna, Antonio; Sharma, Sangeeta; Dewhurst, John Kay; Gross, E.K.U. [Max Planck Institute of Microstructure Physics, Halle (Saale) (Germany)

2016-07-01

In standard Eliashberg methods the Coulomb interaction is usually restricted to the use of a single phenomenological parameter μ{sup *} adjusted to give the right superconducting critical temperature (T{sub c}). In this work we present a parameter-free Eliashberg approach, in which we treat the screened Coulomb interaction within the random phase approximation (RPA) in its static and full dynamic limit. The full energy range of the Coulomb interaction is taken into account, which becomes computationally affordable with the introduction of a suitable isotropic approximation. We have tested the method on a set of conventional superconductors. We will discuss the reliability of the predicted T{sub c} both by using a static and a dynamic Coulomb interaction.

Complex-scaling of screened Coulomb potentials for resonance calculations utilizing the modified Bessel functions

Science.gov (United States)

Jiao, Li-Guang; Ho, Yew Kam

2014-05-01

The screened Coulomb potential (SCP) has been extensively used in atomic physics, nuclear physics, quantum chemistry and plasma physics. However, an accurate calculation for atomic resonances under SCP is still a challenging task for various methods. Within the complex-scaling computational scheme, we have developed a method utilizing the modified Bessel functions to calculate doubly-excited resonances in two-electron atomic systems with configuration interaction-type basis. To test the validity of our method, we have calculated S- and P-wave resonance states of the helium atom with various screening strengths, and have found good agreement with earlier calculations using different methods. Our present method can be applied to calculate high-lying resonances associated with high excitation thresholds of the He+ ion, and with high-angular-momentum states. The derivation and calculation details of our present investigation together with new results of high-angular-momentum states will be presented at the meeting. Supported by NSC of Taiwan.

Dissipative NEGF methodology to treat short range Coulomb interaction: Current through a 1D nanostructure.

Science.gov (United States)

Martinez, Antonio; Barker, John R; Di Prieto, Riccardo

2018-06-13

A methodology describing Coulomb blockade in the Non-equilibrium Green Function formalism is presented. We carried out ballistic and dissipative simulations through a 1D quantum dot using an Einstein phonon model. Inelastic phonons with different energies have been considered. The methodology incorporates the short-range Coulomb interaction between two electrons through the use of a two-particle Green's function. Unlike previous work, the quantum dot has spatial resolution i.e. it is not just parameterized by the energy level and coupling constants of the dot. Our method intends to describe the effect of electron localization while maintaining an open boundary or extended wave function. The formalism conserves the current through the nanostructure. A simple 1D model is used to explain the increase of mobility in semi-crystalline polymers as a function of the electron concentration. The mechanism suggested is based on the lifting of energy levels into the transmission window as a result of the local electron-electron repulsion inside a crystalline domain. The results are aligned with recent experimental findings. Finally, as a proof of concept, we present a simulation of a low temperature resonant structure showing the stability diagram in the Coulomb blockade regime. . © 2018 IOP Publishing Ltd.

Plasma screening effects on the energies of hydrogen atom

International Nuclear Information System (INIS)

Soylu, A.

2012-01-01

A more general exponential cosine screened Coulomb potential is used for the first time to investigate the screening effects on the hydrogen atom in plasmas. This potential is examined for four different cases that correspond to four different type potentials when the different parameters are used in the potential within the framework of the well-known asymptotic iteration method. By solving the corresponding the radial Schrödinger equation with the screened and exponential cosine screened Coulomb potentials and comparing the obtained energy eigenvalues with the results of other studies, the applicability of the method to this kind of plasma physics problem is shown. The energy values of more general exponential cosine screened Coulomb potential are presented for various parameters in the potential. One of the advantages of the present potential is that it exhibits stronger screening effect than that of the exponential cosine screened Coulomb potential and it is also reduced to screened Coulomb and exponential cosine screened Coulomb as well as Coulomb potentials for special values of parameters. The parameters in the potential would be useful to model screening effects which cause an increase or decrease in the energy values of hydrogen atom in both Debye and quantum plasmas and in this manner this potential would be useful for the investigations of the atomic structure and collisions in plasmas.

The effect of Coulomb interactions on the ac mobility of charges in quasi-one-dimensional systems. Example : Discotic liquid crystals

NARCIS (Netherlands)

Siebbeles, L.D.A.; Movaghar, B.

2000-01-01

Using Monte Carlo simulations we calculate the frequency dependence of the diffusive mobility of a group of carriers on a short one-dimensional chain. We allow the carriers to interact with each other through weakly screened long-range Coulomb potentials. We consider both doped systems with discrete

Coulomb-free and Coulomb-distorted recolliding quantum orbits in photoelectron holography

Science.gov (United States)

Maxwell, A. S.; Figueira de Morisson Faria, C.

2018-06-01

We perform a detailed analysis of the different types of orbits in the Coulomb quantum orbit strong-field approximation (CQSFA), ranging from direct to those undergoing hard collisions. We show that some of them exhibit clear counterparts in the standard formulations of the strong-field approximation for direct and rescattered above-threshold ionization, and show that the standard orbit classification commonly used in Coulomb-corrected models is over-simplified. We identify several types of rescattered orbits, such as those responsible for the low-energy structures reported in the literature, and determine the momentum regions in which they occur. We also find formerly overlooked interference patterns caused by backscattered Coulomb-corrected orbits and assess their effect on photoelectron angular distributions. These orbits improve the agreement of photoelectron angular distributions computed with the CQSFA with the outcome of ab initio methods for high energy phtotoelectrons perpendicular to the field polarization axis.

Accurate collision integrals for the attractive static screened Coulomb potential with application to electrical conductivity. [For white dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Macdonald, J. (Delaware, University, Newark (USA))

1991-05-01

The results of accurate calculations of collision integrals for the attractive static screened Coulomb potential are presented. To obtain high accuracy with minimal computational cost, the integrals are evaluated by a quadrature method based on the Whittaker cardinal function. The collision integrals for the attractive potential are needed for calculation of the electrical conductivity of a dense fully or partially ionized plasma, and the results presented here are appropriate for the conditions in the nondegenerate envelopes of white dwarf stars. 25 refs.

Computational assignment of redox states to Coulomb blockade diamonds.

Science.gov (United States)

Olsen, Stine T; Arcisauskaite, Vaida; Hansen, Thorsten; Kongsted, Jacob; Mikkelsen, Kurt V

2014-09-07

With the advent of molecular transistors, electrochemistry can now be studied at the single-molecule level. Experimentally, the redox chemistry of the molecule manifests itself as features in the observed Coulomb blockade diamonds. We present a simple theoretical method for explicit construction of the Coulomb blockade diamonds of a molecule. A combined quantum mechanical/molecular mechanical method is invoked to calculate redox energies and polarizabilities of the molecules, including the screening effect of the metal leads. This direct approach circumvents the need for explicit modelling of the gate electrode. From the calculated parameters the Coulomb blockade diamonds are constructed using simple theory. We offer a theoretical tool for assignment of Coulomb blockade diamonds to specific redox states in particular, and a study of chemical details in the diamonds in general. With the ongoing experimental developments in molecular transistor experiments, our tool could find use in molecular electronics, electrochemistry, and electrocatalysis.

Screened coulomb hybrid DFT investigation of band gap and optical absorption predictions of CuVO3, CuNbO3 and Cu 5Ta11O30 materials

KAUST Repository

Harb, Moussab; Masih, Dilshad; Takanabe, Kazuhiro

2014-01-01

with high accuracy using advanced first-principles quantum methods based on DFT (including the perturbation theory approach DFPT) within the screened coulomb hybrid HSE06 exchange-correlation formalism. The calculated density of states are found

Ginzburg criterion for ionic fluids: the effect of Coulomb interactions.

Science.gov (United States)

Patsahan, O

2013-08-01

The effect of the Coulomb interactions on the crossover between mean-field and Ising critical behavior in ionic fluids is studied using the Ginzburg criterion. We consider the charge-asymmetric primitive model supplemented by short-range attractive interactions in the vicinity of the gas-liquid critical point. The model without Coulomb interactions exhibiting typical Ising critical behavior is used to calibrate the Ginzburg temperature of the systems comprising electrostatic interactions. Using the collective variables method, we derive a microscopic-based effective Hamiltonian for the full model. We obtain explicit expressions for all the relevant Hamiltonian coefficients within the framework of the same approximation, i.e., the one-loop approximation. Then we consistently calculate the reduced Ginzburg temperature t(G) for both the purely Coulombic model (a restricted primitive model) and the purely nonionic model (a hard-sphere square-well model) as well as for the model parameters ranging between these two limiting cases. Contrary to the previous theoretical estimates, we obtain the reduced Ginzburg temperature for the purely Coulombic model to be about 20 times smaller than for the nonionic model. For the full model including both short-range and long-range interactions, we show that t(G) approaches the value found for the purely Coulombic model when the strength of the Coulomb interactions becomes sufficiently large. Our results suggest a key role of Coulomb interactions in the crossover behavior observed experimentally in ionic fluids as well as confirm the Ising-like criticality in the Coulomb-dominated ionic systems.

Dependence of conductivity on thickness within the variable-range hopping regime for Coulomb glasses

Directory of Open Access Journals (Sweden)

M. Caravaca

Full Text Available In this paper, we provide some computational evidence concerning the dependence of conductivity on the system thickness for Coulomb glasses. We also verify the Efros–Shklovskii law and deal with the calculation of its characteristic parameter as a function of the thickness. Our results strengthen the link between theoretical and experimental fields. Keywords: Coulomb glass, Conductivity, Density of states, Efros–Shklovskii law

Bound and resonant states in Coulomb-like potentials

International Nuclear Information System (INIS)

Papp, Z.

1985-12-01

The potential separable expansion method was generalized for calculating bound and resonant states in Coulomb-like potentials. The complete set of Coulomb-Sturmian functions was taken as the basis to expand the short-range potential. On this basis the matrix elements of the Coulomb-Green functions were given in closed form as functions of the (complex) energy. The feasibility of the method is demonstrated by a numerical example. (author)

Dressed ion theory of size-asymmetric electrolytes: effective ionic charges and the decay length of screened Coulomb potential and pair correlations.

Science.gov (United States)

Forsberg, Björn; Ulander, Johan; Kjellander, Roland

2005-02-08

The effects of ionic size asymmetry on long-range electrostatic interactions in electrolyte solutions are investigated within the primitive model. Using the formalism of dressed ion theory we analyze correlation functions from Monte Carlo simulations and the hypernetted chain approximation for size asymmetric 1:1 electrolytes. We obtain decay lengths of the screened Coulomb potential, effective charges of ions, and effective permittivity of the solution. It is found that the variation of these quantities with the degree of size asymmetry depends in a quite intricate manner on the interplay between the electrostatic coupling and excluded volume effects. In most cases the magnitude of the effective charge of the small ion species is larger than that of the large species; the difference increases with increasing size asymmetry. The effective charges of both species are larger (in absolute value) than the bare ionic charge, except for high asymmetry where the effective charge of the large ions can become smaller than the bare charge.

Coulomb drag in coherent mesoscopic systems

DEFF Research Database (Denmark)

Mortensen, 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 th......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 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...

Some studies in scatering by Coulomb modified nuclear potentials

International Nuclear Information System (INIS)

Laha, U.

1988-01-01

Recently, there has been a surge of interest in theoretical questions concerning the Coulomb nuclear problems with the main emphasis on their off-shell behaviour. Earlier approaches to the problem made use of a version of the two-potential formula as used by Bajzer. A slightly different point of view is presented here. An expression for the interacting Green's function for motion in the Coulomb plus Graz potential is constructed and used to obtain the half-off-shell T matrix in the ''maximal reduced form''. Similar results were also derived for the off-shell Jost functions. It is explicitly demonstrated that Coulomb and Coulomb-like potentials the half-off-shell T matrix can be expressed in terms of on-and off-shell Jost functions in the same way as one does for a purely short range interaction. In presenting the results for T matrix and other related quantities, the Coulomb effect is included rigorously. Results clearly delineate the branch point singularities originating from the long range nature of the Coulomb interaction and thus provide a better understanding of the off-shell two-body Coulomb-like T matrices. It is hoped that these results will form an adequate starting point for rigorous calculations on few-body systems with charges. (author). 16 refs

The eikonal phase of supersymmetric Coulomb partners

CERN Document Server

Lassaut, M; Lombard, R J

1998-01-01

We investigate the eikonal phase and its systematic corrections for the two supersymmetric Coulomb partners V sub 1 and V sub 2 derived by Amado. Apart from a constant shift of -pi for V sub 1 and -2 pi for V sub 2 , the eikonal phase decay to the eikonal phase of the Coulomb potential as 1/kb. For the potential V sub 2 , which is phase equivalent to the Coulomb potential, this result is only valid at b approx =0 and asymptotically; in the intermediate range, it constitutes a lower limit. (author)

Separable expansions for local potentials with Coulomb interactions

International Nuclear Information System (INIS)

Adhikari, S.K.

1976-01-01

If two particles are interacting via a short range potential and a repulsive Coulomb potential the t matrix can be written as a sum of the Coulomb and the ''nuclear'' t matrices. In order to solve the three-nucleon problem with Coulomb interactions usually we need a separable representation of this ''nuclear'' t matrix. A recently proposed method for finding a separable expansion for local potentials is here extended to find a rapidly convergent separable expansion, with analytic form factors, for the ''nuclear'' part of the t matrix of a local potential, in the presence of Coulomb interactions. The method is illustrated for a two-term Malfliet-Tjon potential. In each rank the ''nuclear'' phase shift is close to the corresponding phase shift when the Coulomb interaction is switched off

Unstable system with Coulomb interaction distorted near the origin

International Nuclear Information System (INIS)

Kerbikov, B.O.

1981-01-01

An unstable system with Coulomb interaction distorted at small distances is considered. The results are applicable to hadronic atoms analysis. A detailed investigation of the model which can be solved exactly is presented. This model contains the separable short-range potential with the Yamaguchi form factor. Closed expressions for the modified effective range function and the Coulomb-modified scattering length ase obtained [ru

Coulomb Distortion in the Inelastic Regime

Energy Technology Data Exchange (ETDEWEB)

Patricia Solvignon, Dave Gaskell, John Arrington

2009-09-01

The Coulomb distortion effects have been for a long time neglected in deep inelastic scattering for the good reason that the incident energies were very high. But for energies in the range of earlier data from SLAC or at JLab, the Coulomb distortion could have the potential consequence of affecting the A-dependence of the EMC effect and of the longitudinal to transverse virtual photon absorption cross section ratio $R(x,Q^2)$.

Coulomb states in atoms and solids

International Nuclear Information System (INIS)

Ortalano, D.M.

1988-05-01

In this dissertation, an empirical quantum defect approach to describe the valence excitons of the rare gas solids is developed. These Coulomb states are of s-symmetry and form a hydrogen-like series which converges to the bottom of the lowest conduction band. A non-zero quantum defect is found for all of the excitons of neon, argon and xenon. For these systems, then, there exists, in addition to the screened Coulombic component, a non-Coulombic component to the total exciton binding energy. The Wannier formalism is, therefore, inappropriate for the excitons of Ne, Ar and Xe. From the sign of the quantum defect, the non-Coulombic potential is repulsive for Ne and Ar, attractive for Xe, and nearly zero for Kr. This is opposite to that for the Rydberg states of the corresponding rare gas atoms, where the non-Coulombic potential between the electron and the cation is attractive for all of the atoms. The excitons then, are not simply perturbed Rydberg states of the corresponding rare gas atoms (i.e., the excitons do not possess atomic parentage). Interatomic term value/band gap energy correlations and reduced term value/reduced band gap correlations were performed. These correlations were exploited to provide further evidence against both the Wannier formalism and the atomic parentage view point. From these correlations, it was also discovered that the non-Coulombic potential varies smoothly across the valence isoelectronic series of solids, and that it becomes more attractive (or less repulsive) in going from neon to xenon. In order to address the atomic parentage controversy, it was necessary to compare the excitons to the low-n Rydberg states of the rare gas atoms. A review of the quantum defect description of the atomic Rydberg states is, therefore, presented. Also, Rydberg term value/ionization energy correlations are discussed and compared with the analogous exciton correlations. 7 refs., 10 figs., 5 tabs

Infrared behavior of the Faddeev-Popov operator in Coulomb gauge QCD

International Nuclear Information System (INIS)

Nakagawa, Y.; Saito, T.; Toki, H.; Nakamura, A.

2007-01-01

We calculate the eigenvalue distribution of the Faddeev-Popov operator in Coulomb gauge QCD using quenched SU(3) lattice simulation. In the confinement phase, the density of the low-lying eigenvalues increases with lattice volume, and the confinement criterion is satisfied. Moreover, even in the deconfinement phase, the behavior of the FP eigenvalue density is qualitatively the same as in the confinement phase. This is consistent with the fact that the color-Coulomb potential is not screened in the deconfined phase

Coulomb excitation

International Nuclear Information System (INIS)

McGowan, F.K.; Stelson, P.H.

1974-01-01

The theory of Coulomb excitation and a brief review of pertinent treatments of the Coulomb excitation process that are useful for the analysis of experiments are given. Examples demonstrating the scope of nuclear structure information obtainable from gamma spectroscopy are presented. Direct Elambda excitation of 232 Th is discussed in terms of the one phonon octupole vibrational spectrum. B(MI) reduced transition probabilities resulting from Coulomb excitation of odd-A deformed nuclei with heavy ions are presented as a test of the rotational model. The use of gamma ray coincidence and particle-gamma coincidence as tools for investigating Coulomb excitation is discussed. (U.S.)

Coulomb Fourier transformation: A novel approach to three-body scattering with charged particles

International Nuclear Information System (INIS)

Alt, E.O.; Levin, S.B.; Yakovlev, S.L.

2004-01-01

A unitary transformation of the three-body Hamiltonian which describes a system of two charged and one neutral particles is constructed such that the Coulomb potential which acts between the charged particles is explicitly eliminated. The transformed Hamiltonian and, in particular, the transformed short-range pair interactions are worked out in detail. Thereby it is found that, after transformation, the short-range potentials acting between the neutral and either one of the charged particles become simply Fourier transformed but, in addition, multiplied by a function that represents the Coulombic three-body correlations originating from the action of the other charged particle on the considered pair. This function which is universal as it does not depend on any property of the short-range interaction is evaluated explicitly and its singularity structure is described in detail. In contrast, the short-range potential between the charged particles remains of two-body type but occurs now in the 'Coulomb representation'. Specific applications to Yukawa and Gaussian potentials are given. Since the Coulomb-Fourier-transformed Hamiltonian does no longer contain the Coulomb potential or any other effective interaction of long range, standard methods of short-range few-body scattering theory are applicable

Existence and consequences of Coulomb pairing of electrons in a solid

International Nuclear Information System (INIS)

Mahajan, S.M.; Thyagaraja, A.

1996-11-01

It is shown from first principles that, in the periodic potential of a crystalline solid, short-range (i.e., screened) binary Coulomb interactions can lead to a two-electron bound state. It is further suggested that these composite bosonic states (charge -2e, and typically spin zero) could mediate an effectively attractive interaction between pairs of conduction electrons close to the Fermi level. This necessarily short range attractive interaction, which is crucially dependent on the band structure of the solid, and is complementary to the phonon-mediated one, may provide a source for the existence and properties of short correlation-length electron pairs (analogous to but distinct from Cooper pairs) needed to understand high temperature superconductivity. Several distinctive and observable characteristics of the proposed pairing scheme are discussed

Coulomb interaction from the interplay between confinement and screening

International Nuclear Information System (INIS)

Gaete, P.; Guendelman, E.I.

2004-01-01

It has been noticed that confinement effects can be described by the addition of a √(-F μν a F aμν ) term in the Lagrangian density. We now study the combined effect of such 'confinement term' and that of a mass term. The surprising result is that the interplay between these two terms gives rise to a Coulomb interaction. Our picture has a certain correspondence with the quasiconfinement picture described by Giles, Jaffe and de Rujula for QCD with symmetry breaking

The Coulomb law and atomic levels in a superstrong B

Directory of Open Access Journals (Sweden)

Vysotsky M.I.

2014-04-01

Full Text Available The spectrum of atomic levels of hydrogen-like ions originating from the lowest Landau level in an external homogeneous superstrong magnetic field is obtained. The influence of the screening of the Coulomb potential on the values of critical nuclear charges is studied.

Core polarization and Coulomb displacement energies

International Nuclear Information System (INIS)

Shlomo, S.; Love, W.G.

1982-01-01

The contributions of core polarization terms (other than the Auerbach-Kahana-Weneser (AKW) effect) to Coulomb displacement energies of mirror nuclei near A = 16 and A = 40 are examined within the particle-vibration coupling model. The parameters of the model are determined using updated data on the locations and strengths of multipole core excitations. In the absence of relevant data an energy-weighted sum rule (EWSR) is exploited. Taking into account multipole excitations up to L = 5 and subtracting the contributions which are due to short-range correlations, significant contributions (1-3%) to ΔEsub(c) are found. These corrections arise from particle coupling to low-lying collective states (long-range correlations). The implications of these results on the Coulomb energy problem are discussed. (Auth.)

The Coulomb gap and low energy statistics for Coulomb glasses

International Nuclear Information System (INIS)

Glatz, Andreas; Vinokur, Valerii M; Bergli, Joakim; Kirkengen, Martin; Galperin, Yuri M

2008-01-01

We study the statistics of local energy minima in the configuration space of two-dimensional lattice Coulomb glasses with site disorder and the behavior of the Coulomb gap depending on the strength of random site energies. At intermediate disorder, i.e., when the typical strength of the disorder is of the same order as the nearest-neighbor Coulomb energy, the high energy tail of the distribution of the local minima is exponential. We furthermore analyze the structure of the local minima and show that most sites of the system have the same occupation numbers in all of these states. The density of states (DOS) shows a transition from the crystalline state at zero disorder (with a hard gap) to an intermediate, probably glassy state with a Coulomb gap. We analyze this Coulomb gap in some detail and show that the DOS deviates slightly from the traditional linear behavior in 2D. For finite systems these intermediate Coulomb gap states disappear for large disorder strengths and only a random localized state in which all electrons are in the minima of the random potential exists. Dedication: This paper is dedicated to Thomas Nattermann, our dearest friend, brilliant colleague, and outstanding teacher

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 voltage drop V-2 in another shell by the screened Coulomb interaction between the shells neglecting the intershell tunneling. We provide benchmark results for R-21 = V2/I-1 within the Fermi liquid theory using Boltzmann equations. The band structure gives rise to strongly chirality-dependent suppression...... effects for the Coulomb drag between different tubes due to selection rules combined with mismatching of wave vector and crystal angular momentum conservation near the Fermi level. This gives rise to orders of magnitude changes in R-21 and even the sign of R-21 can change depending on the chirality...

Competition between the inter-valley scattering and the intra-valley scattering on magnetoconductivity induced by screened Coulomb disorder in Weyl semimetals

Directory of Open Access Journals (Sweden)

Xuan-Ting Ji

2017-10-01

Full Text Available Recent experiments on Weyl semimetals reveal that charged impurities may play an important role. We use a screened Coulomb disorder to model the charged impurities, and study the magneto-transport in a two-node Weyl semimetal. It is found that when the external magnetic field is applied parallel to the electric field, the calculated longitudinal magnetoconductivity shows positive in the magnetic field, which is just the negative longitudinal magnetoresistivity (LMR observed in experiments. When the two fields are perpendicular to each other, the transverse magnetoconductivities are measured. It is found that the longitudinal (transverse magnetoconductivity is suppressed (enhanced sensitively with increasing the screening length. This feature makes it hardly to observe the negative LMR in Weyl semimetals experimentally owing to a small screening length. Our findings gain insight into further understanding on recently actively debated magneto-transport behaviors in Weyl semimetals. Furthermore we studied the relative weight of the inter-valley scattering and the intra-valley scattering. It shows that the former is as important as the latter and even dominates in the case of strong magnetic fields and small screening length. We emphasize that the discussions on inter-valley scattering is out of the realm of one-node model which has been studied.

Study of the nuclear-coulomb low-energy scattering parameters on the basis of the p-matrix approach

International Nuclear Information System (INIS)

Babenko, V.A.; Petrov, N.M.

1993-01-01

The P-matrix approach application to the description of two charged strongly interacting particles nuclear-Coulomb scattering parameters is considered. The nuclear-Coulomb scattering length and effective range explicit expressions in terms of the P-matrix parameters are found. The nuclear-Coulomb low-energy parameters expansions in powers of small parameter β ≡ R/a b , involving terms with big logarithms, are obtained. The nuclear-Coulomb scattering length and effective range for the square-well and the delta-shell short range potentials are found in an explicit form. (author). 21 refs

Coulomb interaction in multiple scattering theory

International Nuclear Information System (INIS)

Ray, L.; Hoffmann, G.W.; Thaler, R.M.

1980-01-01

The treatment of the Coulomb interaction in the multiple scattering theories of Kerman-McManus-Thaler and Watson is examined in detail. By neglecting virtual Coulomb excitations, the lowest order Coulomb term in the Watson optical potential is shown to be a convolution of the point Coulomb interaction with the distributed nuclear charge, while the equivalent Kerman-McManus-Thaler Coulomb potential is obtained from an averaged, single-particle Coulombic T matrix. The Kerman-McManus-Thaler Coulomb potential is expressed as the Watson Coulomb term plus additional Coulomb-nuclear and Coulomb-Coulomb cross terms, and the omission of the extra terms in usual Kerman-McManus-Thaler applications leads to negative infinite total reaction cross section predictions and incorrect pure Coulomb scattering limits. Approximations are presented which eliminate these anomalies. Using the two-potential formula, the full projectile-nucleus T matrix is separated into two terms, one resulting from the distributed nuclear charge and the other being a Coulomb distorted nuclear T matrix. It is shown that the error resulting from the omission of the Kerman-McManus-Thaler Coulomb terms is effectively removed when the pure Coulomb T matrix in Kerman-McManus-Thaler is replaced by the analogous quantity in the Watson approach. Using the various approximations, theoretical angular distributions are obtained for 800 MeV p+ 208 Pb elastic scattering and compared with experimental data

Coulomb interactions in charged fluids.

Science.gov (United States)

Vernizzi, Graziano; Guerrero-García, Guillermo Iván; de la Cruz, Monica Olvera

2011-07-01

The use of Ewald summation schemes for calculating long-range Coulomb interactions, originally applied to ionic crystalline solids, is a very common practice in molecular simulations of charged fluids at present. Such a choice imposes an artificial periodicity which is generally absent in the liquid state. In this paper we propose a simple analytical O(N(2)) method which is based on Gauss's law for computing exactly the Coulomb interaction between charged particles in a simulation box, when it is averaged over all possible orientations of a surrounding infinite lattice. This method mitigates the periodicity typical of crystalline systems and it is suitable for numerical studies of ionic liquids, charged molecular fluids, and colloidal systems with Monte Carlo and molecular dynamics simulations.

Coulomb collisions in the solar wind

Science.gov (United States)

Klein, L. W.; Ogilvie, K. W.; Burlaga, L. F.

1985-01-01

A major improvement of the present investigation over previous studies of the subject is related to the use of helium temperatures obtained from helium ion measurements uncontaminated by the high-velocity tail of the proton distribution. More observations, covering a large parameter range, were employed, and the effects of interspecies drift were taken into account. It is shown in a more definite way than has been done previously, that Coulomb collisions provide the most important mechanism bringing about equilibrium between helium and protons in the solar wind. Other mechanisms may play some part in restricted regions, but Coulomb collisions are dominant on the macroscale.

Dynamic screening in solar and stellar nuclear reactions

Energy Technology Data Exchange (ETDEWEB)

Daeppen, W. [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA (United States); Mussack, K. [Los Alamos National Laboratory, XTD-2, Los Alamos, NM (United States)

2012-02-15

In the hot, dense plasma of solar and stellar interiors, Coulomb potentials are screened, resulting in increased nuclear reaction rates. Although Salpeter's approximation for static screening is widely accepted and used in stellar modeling, the question of screening in nuclear reactions was revisited in the 1990s. In particular the issue of dynamic effects was raised by Shaviv and Shaviv, who applied the techniques of molecular dynamics to the conditions in the Sun's core in order to numerically determine the effect of screening. By directly calculating the motion of ions and electrons due to Coulomb interactions, the simulations are used to compute the effect of screening without the mean-field assumption inherent in Salpeter's approximation. In the last few years, the USC group has first reproduced Shaviv and Shaviv's numerical analysis of the screening energy, showing an effect of dynamic screening. When the consequence for the reaction-rate was computed, a rather surprising resulted, which is contrary to that from static screening theory. Our calculations showed that dynamic screening does not significantly change the reaction rate from that of the bare Coulomb potential. If this can be independently confirmed, then the effects of dynamic screening are highly relevant and should be included in stellar nuclear reaction rates (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Pressure dependence of effective Coulomb interaction parameters in BaFe2As2 by first-principle calculation

Science.gov (United States)

Aghajani, M.; Hadipour, H.; Akhavan, M.

2018-05-01

Pressure dependence of the onsite Coulomb interactions of the BaFe2As2 has been studied by employing the constrained random phase approximation within first-principle calculations. Analyzing total and projected density of states, a pseudogap is found for dxy band at the energy roughly 0.25 eV higher than the Fermi level. Also, by applying pressure the spectral weight of the dxy orbital vanishes while other orbitals remain metallic. The different screening channels, as discussed in four different models, affect significantly on the Hubbard U while the Hund J remains almost unchanged. The average onsite bare and partially and fully screened Coulomb interactions increase with different rates upon compression. These different rates can be explained by competition between the electronic screening and reduction of bond lengths.

A complex angular momentum theory of modified Coulomb scattering

International Nuclear Information System (INIS)

Thylwe, K.E.; Connor, J.N.L.

1985-01-01

The paper develops an exact complex angular momentum (CAM) theory of elastic scattering for a complex optical potential with a Coulombic tail. The present CAM theory avoids complications due to the long range nature of the Coulombic potential in a straightforward way. The Sommerfeld-Watson transformation together with a travelling wave (near-side far-side) decomposition, is used to obtain an exact representation for the scattering amplitude f(theta) in terms of a background integral fsub(B)(theta) and a series of subamplitudes fsup((+-))sub(n)(theta). New exact representations are derived for fsub(B)(theta) when the scattering matrix element S(lambda) possesses local symmetries of the type S(-lambda)=S(lambda)exp(+-2iπlambda) and S(-lambda)=S(lambda). The exact results obtained in this paper unify the CAM theory of scattering for Coulombic and short range potentials and are especially suitable for the introduction of semiclassical approximations. (author)

Coulomb effects in relativistic laser-assisted Mott scattering

International Nuclear Information System (INIS)

Ngoko Djiokap, J.M.; Kwato Njock, M.G.; Tetchou Nganso, H.M.

2004-09-01

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)

Fermi-edge transmission resonance in graphene driven by a single Coulomb impurity.

Science.gov (United States)

Karnatak, Paritosh; Goswami, Srijit; Kochat, Vidya; Pal, Atindra Nath; Ghosh, Arindam

2014-07-11

The interaction between the Fermi sea of conduction electrons and a nonadiabatic attractive impurity potential can lead to a power-law divergence in the tunneling probability of charge through the impurity. The resulting effect, known as the Fermi edge singularity (FES), constitutes one of the most fundamental many-body phenomena in quantum solid state physics. Here we report the first observation of FES for Dirac fermions in graphene driven by isolated Coulomb impurities in the conduction channel. In high-mobility graphene devices on hexagonal boron nitride substrates, the FES manifests in abrupt changes in conductance with a large magnitude ≈e(2)/h at resonance, indicating total many-body screening of a local Coulomb impurity with fluctuating charge occupancy. Furthermore, we exploit the extreme sensitivity of graphene to individual Coulomb impurities and demonstrate a new defect-spectroscopy tool to investigate strongly correlated phases in graphene in the quantum Hall regime.

Investigating Coulomb's Law.

Science.gov (United States)

Noll, Ellis; Koehlinger, Mervin; Kowalski, Ludwik; Swackhamer, Gregg

1998-01-01

Describes the use of a computer-linked camera to demonstrate Coulomb's law. Suggests a way of reducing the difficulties in presenting Coulomb's law by teaching the inverse square law of gravity and the inverse square law of electricity in the same unit. (AIM)

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

2010-06-28

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.

Diffusion in Coulomb crystals.

Science.gov (United States)

Hughto, J; Schneider, A S; Horowitz, C J; Berry, D K

2011-07-01

Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter Γ=175 to Coulomb parameters up to Γ=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous.

New type of cross section singularity in backward scattering: the Coulomb glory

International Nuclear Information System (INIS)

Demkov, Y.N.; Ostrovskii, V.N.; Tel'nov, D.A.

1984-01-01

For classical scattering by a central potential that exhibits Coulomb behavior (i.e., that is attractive) at small distances, the scattering angle theta tends to π as the orbital angular momentum L decreases. The differential cross section for scattering through angles close to π can be characterized by the power series expansion of the difference theta(L)--π in small L, only odd powers of L being present in this expansion. Expressions are found for the coefficients in the linear (c 1 ) and cubic (c 3 ): in L: terms. It is shown that, for a broad class of screened Coulomb potentials, the coefficient c 1 vanishes at some value of the collision energy E 0 . At the energy E = E 0 the classical cross section diverges in the case of backward scattering (the Coulomb glory); in wave mechanics the cross section possesses a maximum. The behavior of the cross section for energies close to E 0 is computed. The application of the theory to electron scattering by atoms, in which the Coulomb interaction at small distances is determined by the interaction with the nucleus (charge Z) and E 0 = 0.0103Z 4 /sup // 3 keV, is discussed

Enhanced Bulk-Edge Coulomb Coupling in Fractional Fabry-Perot Interferometers.

Science.gov (United States)

von Keyserlingk, C W; Simon, S H; Rosenow, Bernd

2015-09-18

Recent experiments use Fabry-Perot (FP) interferometry to claim that the ν=5/2 quantum Hall state exhibits non-Abelian topological order. We note that the experiments appear inconsistent with a model neglecting bulk-edge Coulomb coupling and Majorana tunneling, so we reexamine the theory of FP devices. Even a moderate Coulomb coupling may strongly affect some fractional plateaus, but very weakly affect others, allowing us to model the data over a wide range of plateaus. While experiments are consistent with the ν=5/2 state harboring Moore-Read topological order, they may have measured Coulomb effects rather than an "even-odd effect" due to non-Abelian braiding.

Hyperspherical Coulomb spheroidal basis in the Coulomb three-body problem

International Nuclear Information System (INIS)

Abramov, D. I.

2013-01-01

A hyperspherical Coulomb spheroidal (HSCS) representation is proposed for the Coulomb three-body problem. This is a new expansion in the set of well-known Coulomb spheroidal functions. The orthogonality of Coulomb spheroidal functions on a constant-hyperradius surface ρ = const rather than on a constant-internuclear-distance surface R = const, as in the traditional Born-Oppenheimer approach, is a distinguishing feature of the proposed approach. Owing to this, the HSCS representation proves to be consistent with the asymptotic conditions for the scattering problem at energies below the threshold for three-body breakup: only a finite number of radial functions do not vanish in the limit of ρ→∞, with the result that the formulation of the scattering problem becomes substantially simpler. In the proposed approach, the HSCS basis functions are considerably simpler than those in the well-known adiabatic hyperspherical representation, which is also consistent with the asymptotic conditions. Specifically, the HSCS basis functions are completely factorized. Therefore, there arise no problems associated with avoided crossings of adiabatic hyperspherical terms.

Transport cross sections based on a screened interaction potential: Comparison of classical and quantum-mechanical results

International Nuclear Information System (INIS)

Vincent, R.; Juaristi, J.I.; Nagy, I.

2005-01-01

Standard classical and quantum-mechanical methods are used to characterize the momentum-transfer cross section needed in energy-loss calculations and simulations for heavy, swift charges moving in an electron gas. By applying a well-known, finite-range screened Coulombic potential energy to model the two-body collision, the quantitative applicability range of the classical cross section is investigated as a function of charge (Z), screening length (R), and scattering relative velocity (v). The a posteriori condition (Z/R)/v 2 <1, as an upper bound for heavy charges, is deduced for this applicability range from the comparative study performed

Gauge orbits and the Coulomb potential

International Nuclear Information System (INIS)

Greensite, J.

2009-01-01

If the color Coulomb potential is confining, then the Coulomb field energy of an isolated color charge is infinite on an infinite lattice, even if the usual UV divergence is lattice regulated. A simple criterion for Coulomb confinement is that the expectation value of timelike link variables vanishes in the Coulomb gauge, but it is unclear how this criterion is related to the spectrum of the corresponding Faddeev-Popov operator, which can be used to formulate a quite different criterion for Coulomb confinement. The purpose of this article is to connect the two seemingly different Coulomb confinement criteria, and explain the geometrical basis of the connection.

Expansions for Coulomb wave functions

NARCIS (Netherlands)

Boersma, J.

1969-01-01

In this paper we derive a number of expansions for Whittaker functions, regular and irregular Coulomb wave functions. The main result consists of a new expansion for the irregular Coulomb wave functions of orders zero and one in terms of regular Coulomb wave functions. The latter expansions are

The screening of charged impurities in bilayer graphene

International Nuclear Information System (INIS)

Zhang Wenjing; Li, Lain-Jong

2010-01-01

Positively charged impurities were introduced into a bilayer graphene (BLG) transistor by n-doping with dimethylformamide. Subsequent exposure of the BLG device to moisture resulted in a positive shift of the Dirac point and an increase of hole mobility, suggesting that moisture could reduce the scattering strength of the existing charged impurities. In other words, moisture screened off the 'effective density' of charged impurities. At the early stage of moisture screening the scattering of hole carriers is dominated by long-range Coulomb scatter, but an alternative scattering mechanism should also be taken into consideration when the effective density of impurities is further lowered on moisture exposure.

Conservation laws, vertex corrections, and screening in Raman spectroscopy

Science.gov (United States)

Maiti, Saurabh; Chubukov, Andrey V.; Hirschfeld, P. J.

2017-07-01

We present a microscopic theory for the Raman response of a clean multiband superconductor, with emphasis on the effects of vertex corrections and long-range Coulomb interaction. The measured Raman intensity, R (Ω ) , is proportional to the imaginary part of the fully renormalized particle-hole correlator with Raman form factors γ (k ⃗) . In a BCS superconductor, a bare Raman bubble is nonzero for any γ (k ⃗) and diverges at Ω =2 Δmax , where Δmax is the largest gap along the Fermi surface. However, for γ (k ⃗) = constant, the full R (Ω ) is expected to vanish due to particle number conservation. It was sometimes stated that this vanishing is due to the singular screening by long-range Coulomb interaction. In our general approach, we show diagrammatically that this vanishing actually holds due to vertex corrections from the same short-range interaction that gives rise to superconductivity. We further argue that long-range Coulomb interaction does not affect the Raman signal for any γ (k ⃗) . We argue that vertex corrections eliminate the divergence at 2 Δmax . We also argue that vertex corrections give rise to sharp peaks in R (Ω ) at Ω <2 Δmin (the minimum gap along the Fermi surface), when Ω coincides with the frequency of one of the collective modes in a superconductor, e.g., Leggett and Bardasis-Schrieffer modes in the particle-particle channel, and an excitonic mode in the particle-hole channel.

Spectral sum for the color-Coulomb potential in SU(3) Coulomb gauge lattice Yang-Mills theory

International Nuclear Information System (INIS)

Nakagawa, Y.; Nakamura, A.; Saito, T.; Toki, H.

2010-01-01

We discuss the essential role of the low-lying eigenmodes of the Faddeev-Popov (FP) ghost operator on the confining color-Coulomb potential using SU(3) quenched lattice simulations in the Coulomb gauge. The color-Coulomb potential is expressed as a spectral sum of the FP ghost operator and has been explored by partially summing the FP eigenmodes. We take into account the Gribov copy effects that have a great impact on the FP eigenvalues and the color-Coulomb potential. We observe that the lowest eigenvalue vanishes in the thermodynamic limit much faster than that in the Landau gauge. The color-Coulomb potential at large distances is governed by the near-zero FP eigenmodes; in particular, the lowest one accounts for a substantial portion of the color-Coulomb string tension comparable to the Wilson string tension.

Coulomb potentials between spherical heavy ions

International Nuclear Information System (INIS)

Iwe, H.

1982-01-01

The Coulomb interaction between spherical nuclei having arbitrary radial nuclear charge distributions is calculated. All these realistic Coulomb potentials are given in terms of analytical expressions and are available for immediate application. So in no case a numerical computation of the Coulomb integral is required. The parameters of the charge distributions are taken from electron scattering analysis. The Coulomb self-energies of the charge distributions used are also calculated analytically in a closed form. For a number of nucleus-nucleus pairs, the Coulomb potentials derived from realistic charge distributions are compared with those normally used in various nucleus-nucleus optical model calculations. In this connection a detailed discussion of the problem how to choose consistently Coulomb parameters for different approximations is given. (orig.)

The Kosterlitz-thouless phase transition in two-dimensional hierarchical Coulomb gases

International Nuclear Information System (INIS)

Marchetti, D.H.U.; Perez, J.F.

1988-11-01

A hierarchical version of two-dimensional lattice Coulomb gases is investigated. For β>β c = 8Π there is a locally stable line of fixed points for the Renormalization Group ('block charges') transformations. For β>β - c (β c ≤β - c ≤3Π/2 β c ), these fixed points are globally stable. As a consequence, there is no screening of external charges for any activity if β > β - c . At β c a supercritical bifurcation takes place and the behavior of the model for β c as to show a weak form of screening, is investigated. (author) [pt

Phase diagram, correlation gap, and critical properties of the Coulomb glass

Science.gov (United States)

Palassini, Matteo; Goethe, Martin

2009-03-01

We investigate the lattice Coulomb glass model in three dimensions via extensive Monte Carlo simulations. 1. No evidence for an equilibrium glass phase is found down to very low temperatures, contrary to mean-field predictions, although the correlation length increases rapidly near T=0. 2. The single-particle density of states near the Coulomb gap satisfies the scaling law g(e,T)=T^λf(e/T) with λ 2.2. 3. A charge-ordered phase exists at low disorder. The phase transition from the fluid to the charge ordered phase is consistent with the Random Field Ising universality class, which shows that the interaction is effectively screened at moderate temperature. Results from nonequilibrium simulations will also be briefly discussed. Reference: M.Goethe and M.Palassini, arXiv:0810.1047

Exact method for the simulation of Coulombic systems by spherically truncated, pairwise r-1 summation

International Nuclear Information System (INIS)

Wolf, D.; Keblinski, P.; Phillpot, S.R.; Eggebrecht, J.

1999-01-01

Based on a recent result showing that the net Coulomb potential in condensed ionic systems is rather short ranged, an exact and physically transparent method permitting the evaluation of the Coulomb potential by direct summation over the r -1 Coulomb pair potential is presented. The key observation is that the problems encountered in determining the Coulomb energy by pairwise, spherically truncated r -1 summation are a direct consequence of the fact that the system summed over is practically never neutral. A simple method is developed that achieves charge neutralization wherever the r -1 pair potential is truncated. This enables the extraction of the Coulomb energy, forces, and stresses from a spherically truncated, usually charged environment in a manner that is independent of the grouping of the pair terms. The close connection of our approach with the Ewald method is demonstrated and exploited, providing an efficient method for the simulation of even highly disordered ionic systems by direct, pairwise r -1 summation with spherical truncation at rather short range, i.e., a method which fully exploits the short-ranged nature of the interactions in ionic systems. The method is validated by simulations of crystals, liquids, and interfacial systems, such as free surfaces and grain boundaries. copyright 1999 American Institute of Physics

Influence of Coulomb interaction of tunable shapes on the collective transport of ultradilute two-dimensional holes.

Science.gov (United States)

Huang, Jian; Pfeiffer, L N; West, K W

2014-01-24

In high quality updoped GaAs field-effect transistors, the two-dimensional charge carrier concentrations can be tuned to very low values similar to the density of electrons on helium surfaces. An important interaction effect, screening of the Coulomb interaction by the gate, rises as a result of the large charge spacing comparable to the distance between the channel and the gate. Based on the results of the temperature (T) dependence of the resistivity from measuring four different samples, a power-law characteristic is found for charge densities ≤2×10(9)  cm(-2). Moreover, the exponent exhibits a universal dependence on a single dimensionless parameter, the ratio between the mean carrier separation and the distance to the metallic gate that screens the Coulomb interaction. Thus, the electronic properties are tuned through varying the shape of the interaction potential.

Coulomb energy, vortices, and confinement

International Nuclear Information System (INIS)

Greensite, Jeff; Olejnik, Stefan

2003-01-01

We estimate the Coulomb energy of static quarks from a Monte Carlo calculation of the correlator of timelike link variables in the Coulomb gauge. We find, in agreement with Cucchieri and Zwanziger, that this energy grows linearly with distance at large quark separations. The corresponding string tension, however, is several times greater than the accepted asymptotic string tension, indicating that a state containing only static sources, with no constituent gluons, is not the lowest energy flux tube state. The Coulomb energy is also measured on thermalized lattices with center vortices removed by the de Forcrand-D'Elia procedure. We find that when vortices are removed, the Coulomb string tension vanishes

Coulomb Correlations Intertwined with Spin and Orbital Excitations in LaCoO_{3}.

Science.gov (United States)

Tomiyasu, K; Okamoto, J; Huang, H Y; Chen, Z Y; Sinaga, E P; Wu, W B; Chu, Y Y; Singh, A; Wang, R-P; de Groot, F M F; Chainani, A; Ishihara, S; Chen, C T; Huang, D J

2017-11-10

We carried out temperature-dependent (20-550 K) measurements of resonant inelastic x-ray scattering on LaCoO_{3} to investigate the evolution of its electronic structure across the spin-state crossover. In combination with charge-transfer multiplet calculations, we accurately quantified the renomalized crystal-field excitation energies and spin-state populations. We show that the screening of the effective on-site Coulomb interaction of 3d electrons is orbital selective and coupled to the spin-state crossover in LaCoO_{3}. The results establish that the gradual spin-state crossover is associated with a relative change of Coulomb energy versus bandwidth, leading to a Mott-type insulator-to-metal transition.

Unified approach to probing Coulomb effects in tunnel ionization for any ellipticity of laser light.

Science.gov (United States)

Landsman, A S; Hofmann, C; Pfeiffer, A N; Cirelli, C; Keller, U

2013-12-27

We present experimental data that show significant deviations from theoretical predictions for the location of the center of the electron momenta distribution at low values of ellipticity ε of laser light. We show that these deviations are caused by significant Coulomb focusing along the minor axis of polarization, something that is normally neglected in the analysis of electron dynamics, even in cases where the Coulomb correction is otherwise taken into account. By investigating ellipticity-resolved electron momenta distributions in the plane of polarization, we show that Coulomb focusing predominates at lower values of ellipticity of laser light, while Coulomb asymmetry becomes important at higher values, showing that these two complementary phenomena can be used to probe long-range Coulomb interaction at all polarizations of laser light. Our results suggest that both the breakdown of Coulomb focusing and the onset of Coulomb asymmetry are linked to the disappearance of Rydberg states with increasing ellipticity.

Coulomb correction calculations of pp Bremsstrahlung

International Nuclear Information System (INIS)

Katsogiannis, A.; Amos, K.; Jetter, M.; von Geramb, H.V.

1994-01-01

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

Asymptotic coulombic conditions in the electron capture process

International Nuclear Information System (INIS)

Corchs, S.E.; Maidagan, J.M.; Rivarola, R.D.

1990-01-01

Several first order perturbative approximations of the transition amplitude for electronic capture are studied. Different models in which the long range Coulomb potential is represented by different internuclear dependent phases, in the initial and final wave functions, are analysed and compared. (Author). 8 refs., 2 figs

Super-Coulombic atom-atom interactions in hyperbolic media

Science.gov (United States)

Cortes, Cristian L.; Jacob, Zubin

2017-01-01

Dipole-dipole interactions, which govern phenomena such as cooperative Lamb shifts, superradiant decay rates, Van der Waals forces and resonance energy transfer rates, are conventionally limited to the Coulombic near-field. Here we reveal a class of real-photon and virtual-photon long-range quantum electrodynamic interactions that have a singularity in media with hyperbolic dispersion. The singularity in the dipole-dipole coupling, referred to as a super-Coulombic interaction, is a result of an effective interaction distance that goes to zero in the ideal limit irrespective of the physical distance. We investigate the entire landscape of atom-atom interactions in hyperbolic media confirming the giant long-range enhancement. We also propose multiple experimental platforms to verify our predicted effect with phonon-polaritonic hexagonal boron nitride, plasmonic super-lattices and hyperbolic meta-surfaces as well. Our work paves the way for the control of cold atoms above hyperbolic meta-surfaces and the study of many-body physics with hyperbolic media.

Sine-Gordon mean field theory of a Coulomb gas

Energy Technology Data Exchange (ETDEWEB)

Diehl, Alexandre; Barbosa, Marcia C.; Levin, Yan

1997-12-31

Full text. The Coulomb gas provides a paradigm for the study of various models of critical phenomena. In particular, it is well known that the two dimensional (2 D). Coulomb gas can be directly used to study the superfluidity transition in {sup 4} He films, arrays of Josephson junctions, roughening transition, etc. Not withstanding its versatility, our full understanding of the most basic model of Coulomb gas, namely an ensemble of hard spheres carrying either positive or negative charges at their center, is still lacking. It is now well accepted that at low density the two dimensional plasma of equal number of positive and negative particles undergoes a Kosterlitz-Thouless (KT) metal insulator transition. This transition is of an infinite order and is characterized by a diverging Debye screening length. As the density of particles increases, the validity of the KT theory becomes questionable and the possibility of the KT transition being replaced by some kind of first order discontinuity has been speculated for a long time. In this work sine-Gordon field theory is used to investigate the phase diagram of a neutral Coulomb gas. A variational mean-field free energy is constructed and the corresponding phase diagrams in two and three dimensions are obtained. When analyzed in terms of chemical potential, the sine-Gordon theory predicts the phase diagram topologically identical to the Monte Carlo simulations and a recently developed Debye-Huckel-Bjerrum theory. In 2D, we find that the infinite-order Kosterlitz-Thouless line terminates in a tricritical point, after which the metal-insulator transition becomes first order. However, when the transformation from chemical potential to the density is made the whole insulating phase is mapped onto zero density. (author)

Coulomb blockade induced by magnetic field

International Nuclear Information System (INIS)

Kusmartsev, F.V.

1992-01-01

In this paper, the authors found that a Coulomb blockade can be induced by magnetic field. The authors illustrated this effect on the example of a ring consisting of two and many Josephson junctions. For the ring with two junctions we present an exact solution. The transition into Coulomb blockade state on a ring transforms into a linear array of Josephson junctions, although in latter case the effect of magnetic field disappears. In the state of Coulomb blockade the magnetization may be both diamagnetic and paramagnetic. The Coulomb blockade may also be removed by external magnetic field

Adventures in Coulomb Gauge

International Nuclear Information System (INIS)

Greensite, J.; Olejnik, S.

2003-01-01

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.

Azimuthal angle dependence of Coulomb and nuclear interactions between two deformed nuclei

International Nuclear Information System (INIS)

Ismail, M.; Ellithi, A. Y.; Botros, M. M.; Mellik, A. E.

2007-01-01

The azimuthal angle (φ) variation of the Coulomb and nuclear heavy ion (HI) potentials is studied in the framework of the double folding model, which is derived from realistic nuclear density distributions and a nucleon-nucleon (NN) interaction. The present calculation shows that the variation of HI potentials with the azimuthal angle depends strongly on the range of the NN forces. For the long-range Coulomb force, the maximum variation with φ is about 0.9%, and for HI potential derived from zero-range NN interaction the φ-variation can reach up to 90.0%. Our calculations are compared with the recent φ-dependence of the HI potential derived from proximity method. The present realistic φ-dependence calculations of the HI potential is completely different from the results of the proximity calculations

Reply to "Comment on 'Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit' ".

Science.gov (United States)

Gebremedhin, Daniel H; Weatherford, Charles A

2015-02-01

This is a response to the comment we received on our recent paper "Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit." In that paper, we introduced a computational algorithm that is appropriate for solving stiff initial value problems, and which we applied to the one-dimensional time-independent Schrödinger equation with a soft Coulomb potential. We solved for the eigenpairs using a shooting method and hence turned it into an initial value problem. In particular, we examined the behavior of the eigenpairs as the softening parameter approached zero (hard Coulomb limit). The commenters question the existence of the ground state of the hard Coulomb potential, which we inferred by extrapolation of the softening parameter to zero. A key distinction between the commenters' approach and ours is that they consider only the half-line while we considered the entire x axis. Based on mathematical considerations, the commenters consider only a vanishing solution function at the origin, and they question our conclusion that the ground state of the hard Coulomb potential exists. The ground state we inferred resembles a δ(x), and hence it cannot even be addressed based on their argument. For the excited states, there is agreement with the fact that the particle is always excluded from the origin. Our discussion with regard to the symmetry of the excited states is an extrapolation of the soft Coulomb case and is further explained herein.

Coulomb Blockade Plasmonic Switch.

Science.gov (United States)

Xiang, Dao; Wu, Jian; Gordon, Reuven

2017-04-12

Tunnel resistance can be modulated with bias via the Coulomb blockade effect, which gives a highly nonlinear response current. Here we investigate the optical response of a metal-insulator-nanoparticle-insulator-metal structure and show switching of a plasmonic gap from insulator to conductor via Coulomb blockade. By introducing a sufficiently large charging energy in the tunnelling gap, the Coulomb blockade allows for a conductor (tunneling) to insulator (capacitor) transition. The tunnelling electrons can be delocalized over the nanocapacitor again when a high energy penalty is added with bias. We demonstrate that this has a huge impact on the plasmonic resonance of a 0.51 nm tunneling gap with ∼70% change in normalized optical loss. Because this structure has a tiny capacitance, there is potential to harness the effect for high-speed switching.

Comment on "Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit".

Science.gov (United States)

Carrillo-Bernal, M A; Núñez-Yépez, H N; Salas-Brito, A L; Solis, Didier A

2015-02-01

In the referred paper, the authors use a numerical method for solving ordinary differential equations and a softened Coulomb potential -1/√[x(2)+β(2)] to study the one-dimensional Coulomb problem by approaching the parameter β to zero. We note that even though their numerical findings in the soft potential scenario are correct, their conclusions do not extend to the one-dimensional Coulomb problem (β=0). Their claims regarding the possible existence of an even ground state with energy -∞ with a Dirac-δ eigenfunction and of well-defined parity eigenfunctions in the one-dimensional hydrogen atom are questioned.

Nuclear and Non-Ionizing Energy-Loss for Coulomb Scattered Particles from Low Energy up to Relativistic Regime in Space Radiation Environment

CERN Document Server

Boschini, M.J.; Gervasi, M.; Giani, S.; Grandi, D.; Ivantchenko, V.; Pensotti, S.; Rancoita, P.G.; Tacconi, M.

2011-01-01

In the space environment, instruments onboard of spacecrafts can be affected by displacement damage due to radiation. The differential scattering cross section for screened nucleus--nucleus interactions - i.e., including the effects due to screened Coulomb nuclear fields -, nuclear stopping powers and non-ionization energy losses are treated from about 50\\,keV/nucleon up to relativistic energies.

Long-range analysis of density fitting in extended systems

Science.gov (United States)

Varga, Scarontefan

Density fitting scheme is analyzed for the Coulomb problem in extended systems from the correctness of long-range behavior point of view. We show that for the correct cancellation of divergent long-range Coulomb terms it is crucial for the density fitting scheme to reproduce the overlap matrix exactly. It is demonstrated that from all possible fitting metric choices the Coulomb metric is the only one which inherently preserves the overlap matrix for infinite systems with translational periodicity. Moreover, we show that by a small additional effort any non-Coulomb metric fit can be made overlap-preserving as well. The problem is analyzed for both ordinary and Poisson basis set choices.

Ultrafast dynamics of Coulomb correlated excitons in GaAs quantum wells

Energy Technology Data Exchange (ETDEWEB)

Mycek, M.A. [Univ. of California, Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley National Lab., CA (United States). Materials Sciences Div.

1995-12-01

The author measures the transient nonlinear optical response of room temperature excitons in gallium arsenide quantum wells via multi-wave mixing experiments. The dynamics of the resonantly excited excitons is directly reflected by the ultrafast decay of the induced nonlinear polarization, which radiates the detected multi-wave mixing signal. She characterizes this ultrafast coherent emission in both amplitude and phase, using time- and frequency-domain measurement techniques, to better understand the role of Coulomb correlation in these systems. To interpret the experimental results, the nonlinear optical response of a dense medium is calculated using a model including Coulomb interaction. She contributes three new elements to previous theoretical and experimental studies of these systems. First, surpassing traditional time-integrated measurements, she temporally resolves the amplitude of the ultrafast coherent emission. Second, in addition to measuring the third-order four-wave mixing signal, she also investigates the fifth-order six-wave mixing response. Third, she characterizes the ultrafast phase dynamics of the nonlinear emission using interferometric techniques with an unprecedented resolution of approximately 140 attoseconds. The author finds that effects arising from Coulomb correlation dominate the nonlinear optical response when the density of excitons falls below 3 {times} 10{sup 11} cm{sup {minus}2}, the saturation density. These signatures of Coulomb correlation are investigated for increasing excitation density to gradually screen the interactions and test the validity of the model for dense media. The results are found to be qualitatively consistent with both the predictions of the model and with numerical solutions to the semiconductor Bloch equations. Importantly, the results also indicate current experimental and theoretical limitations, which should be addressed in future research.

COULN, a program for evaluating negative energy Coulomb functions

International Nuclear Information System (INIS)

Noble, C.J.; Thompson, I.J.

1984-01-01

Program COULN calculates exponentially decaying Whittaker functions, Wsub(K,μ)(z) corresponding to negative energy Coulomb functions. The method employed is most appropriate for parameter ranges which commonly occur in atomic and molecular asymptotic scattering problems using a close-coupling approximation in the presence of closed channels. (orig.)

Hyperon excitation in nuclear coulomb field

International Nuclear Information System (INIS)

Vanyashin, A.V.; Nikitin, Yu.P.; Shan'gin, A.A.

1981-01-01

A possibility is studied to measure radiative decay partial widths from the 3/2 + decuplet hyperon resonances by means of the Coulomb excitation method of the octet hyperons. The expected contributions from the strong and electromagnetic interactions in the coherence range to the hyperon excitation cross sections on heavy nuclei and on the 4 He nucleus are estimated. The particle angular distributions in the reactions Σ-+A→Σ-(1385)+A and Λ+A→Σ 0 (1385)+A are analysed in order to determine the energy range where the background conditions are the most favorable to extract the electromagnetic mechanism of the hyperon excitation [ru

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)

Hoffmann, B.

1984-07-01

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) [de

Nuclear sizes and the Coulomb Displacement Energy

International Nuclear Information System (INIS)

Van der Werf, S.Y.

1997-01-01

Data on Coulomb Displacement Energies in the mass range A = 40 - 240 are analyzed in the deformed Liquid Drop model and in the independent particle model. Reduced half-widths of Woods-Saxon mean-field potential of the resulting neutron-excess distributions are deduced. It is argued that the Nolen-Schiffer anomaly may be lifted by allowing for a slight binding-energy dependence of the mean-field potential geometry. (author)

Plasma screening effects on the energies of hydrogen atom under the influence of velocity-dependent potential

International Nuclear Information System (INIS)

Bahar, M. K.

2014-01-01

In order to examine the plasma screening and velocity-dependent potential effects on the hydrogen atom, the Schrödinger equation including a more general exponential cosine screened Coulomb and velocity-dependent potential is solved numerically in the framework asymptotic iteration method. The more general exponential cosine screened Coulomb potential is used to model Debye and quantum plasma for the specific values of the parameters in its structure. However, in order to examine effects of velocity-dependent potential on energy values of hydrogen atom in Debye and quantum plasma, the isotropic form factor of velocity-dependent potential is given as harmonic oscillator type, ρ(r)=ρ o r 2 . Then, the energies of s and p states are calculated numerically without any approximation. In order to investigate thoroughly plasma screening effects and contribution of velocity-dependent potential on energy values of hydrogen atom, the corresponding calculations are carried out by using different values of parameters of more general exponential cosine screened Coulomb potential and isotropic dependence, results of which are discussed

Role of the Coulomb interaction in the low-frequency density of states of DNA double helices

International Nuclear Information System (INIS)

Garcia, A.E.; Krumhansl, J.A.

1988-01-01

The complete vibrational frequency spectrum of several DNA double-helical oligomers is calculated using established pair potentials. Various cutoff values are used for the range of the Coulomb interactions. At very low frequency the integrated density of states shows a noninteger exponent with values ranging from 0.75 to 1.55, depending on the cutoff value for the Coulomb interactions. We conclude that the cumulative densities of states in those molecules depend more on competing interactions than on various proposed universal laws

Coulomb interaction in the supermultiplet basis

International Nuclear Information System (INIS)

Ruzha, Ya.Kh.; Guseva, T.V.; Tamberg, Yu.Ya.; Vanagas, V.V.

1989-01-01

An approximate expression for the matrix elements of the Coulomb interaction operator in the supermultiplet basis has been derived with the account for the orbitally-nonsymmetric terms. From the general expression a simplified formula for the Coulomb interaction energy has been proposed. On the basis of the expression obtained the contribution of the Coulomb interaction to the framework of a strongly restricted dynamic model in the light (4≤A≤40) and heavy (158≤A≤196) nuclei region has been studied. 19 refs.; 4 tabs

Stability of Dirac Liquids with Strong Coulomb Interaction.

Science.gov (United States)

Tupitsyn, Igor S; Prokof'ev, Nikolay V

2017-01-13

We develop and apply the diagrammatic Monte Carlo technique to address the problem of the stability of the Dirac liquid state (in a graphene-type system) against the strong long-range part of the Coulomb interaction. So far, all attempts to deal with this problem in the field-theoretical framework were limited either to perturbative or random phase approximation and functional renormalization group treatments, with diametrically opposite conclusions. Our calculations aim at the approximation-free solution with controlled accuracy by computing vertex corrections from higher-order skeleton diagrams and establishing the renormalization group flow of the effective Coulomb coupling constant. We unambiguously show that with increasing the system size L (up to ln(L)∼40), the coupling constant always flows towards zero; i.e., the two-dimensional Dirac liquid is an asymptotically free T=0 state with divergent Fermi velocity.

A simplified fixed-point perturbation theory and its application to the coulomb + short-range potential

International Nuclear Information System (INIS)

Znojil, M.

1986-01-01

The radial Schroedinger equation and its bound-state solutions for the interaction V(r)=Vsub(coulomb)+Vsub(Pade), where Vsub(Pade)(r)=(b+cr)/(1+drsup(2)) are considered. In order to construct exactly the Feshbach effective Hamiltonian Hsup(eff), the fixed-point-substraction technique is employed and its simplification is proposed. The first two terms in the resulting asymptotic expansions of PSIsub(n) and Hsup(eff) are calculated and interpreted as a new type of perturbation theory

Trinucleon asymptotic normalization constants including Coulomb effects

International Nuclear Information System (INIS)

Friar, J.L.; Gibson, B.F.; Lehman, D.R.; Payne, G.L.

1982-01-01

Exact theoretical expressions for calculating the trinucleon S- and D-wave asymptotic normalization constants, with and without Coulomb effects, are presented. Coordinate-space Faddeev-type equations are used to generate the trinucleon wave functions, and integral relations for the asymptotic norms are derived within this framework. The definition of the asymptotic norms in the presence of the Coulomb interaction is emphasized. Numerical calculations are carried out for the s-wave NN interaction models of Malfliet and Tjon and the tensor force model of Reid. Comparison with previously published results is made. The first estimate of Coulomb effects for the D-wave asymptotic norm is given. All theoretical values are carefully compared with experiment and suggestions are made for improving the experimental situation. We find that Coulomb effects increase the 3 He S-wave asymptotic norm by less than 1% relative to that of 3 H, that Coulomb effects decrease the 3 He D-wave asymptotic norm by approximately 8% relative to that of 3 H, and that the distorted-wave Born approximation D-state parameter, D 2 , is only 1% smaller in magnitude for 3 He than for 3 H due to compensating Coulomb effects

Coulomb-Driven Relativistic Electron Beam Compression.

Science.gov (United States)

Lu, Chao; Jiang, Tao; Liu, Shengguang; Wang, Rui; Zhao, Lingrong; Zhu, Pengfei; Xiang, Dao; Zhang, Jie

2018-01-26

Coulomb interaction between charged particles is a well-known phenomenon in many areas of research. In general, the Coulomb repulsion force broadens the pulse width of an electron bunch and limits the temporal resolution of many scientific facilities such as ultrafast electron diffraction and x-ray free-electron lasers. Here we demonstrate a scheme that actually makes use of the Coulomb force to compress a relativistic electron beam. Furthermore, we show that the Coulomb-driven bunch compression process does not introduce additional timing jitter, which is in sharp contrast to the conventional radio-frequency buncher technique. Our work not only leads to enhanced temporal resolution in electron-beam-based ultrafast instruments that may provide new opportunities in probing material systems far from equilibrium, but also opens a promising direction for advanced beam manipulation through self-field interactions.

Coulomb-Driven Relativistic Electron Beam Compression

Science.gov (United States)

Lu, Chao; Jiang, Tao; Liu, Shengguang; Wang, Rui; Zhao, Lingrong; Zhu, Pengfei; Xiang, Dao; Zhang, Jie

2018-01-01

Coulomb interaction between charged particles is a well-known phenomenon in many areas of research. In general, the Coulomb repulsion force broadens the pulse width of an electron bunch and limits the temporal resolution of many scientific facilities such as ultrafast electron diffraction and x-ray free-electron lasers. Here we demonstrate a scheme that actually makes use of the Coulomb force to compress a relativistic electron beam. Furthermore, we show that the Coulomb-driven bunch compression process does not introduce additional timing jitter, which is in sharp contrast to the conventional radio-frequency buncher technique. Our work not only leads to enhanced temporal resolution in electron-beam-based ultrafast instruments that may provide new opportunities in probing material systems far from equilibrium, but also opens a promising direction for advanced beam manipulation through self-field interactions.

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...... means such as perturbation theory or random matrix theory. The physics of Coulomb drag in the mesoscopic regime is very different from Coulomb drag between extended electron systems. In the mesoscopic regime we in general find fluctuations of the drag comparable to the mean value. Examples are vanishing...

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...... means such as perturbation theory or random matrix theory. The physics of Coulomb drag in the mesoscopic regime is very different from Coulomb drag between extended electron systems. In the mesoscopic regime we in general find fluctuations of the drag comparable to the mean value. Examples are vanishing...

Coulomb branches with complex singularities

Science.gov (United States)

Argyres, Philip C.; Martone, Mario

2018-06-01

We construct 4d superconformal field theories (SCFTs) whose Coulomb branches have singular complex structures. This implies, in particular, that their Coulomb branch coordinate rings are not freely generated. Our construction also gives examples of distinct SCFTs which have identical moduli space (Coulomb, Higgs, and mixed branch) geometries. These SCFTs thus provide an interesting arena in which to test the relationship between moduli space geometries and conformal field theory data. We construct these SCFTs by gauging certain discrete global symmetries of N = 4 superYang-Mills (sYM) theories. In the simplest cases, these discrete symmetries are outer automorphisms of the sYM gauge group, and so these theories have lagrangian descriptions as N = 4 sYM theories with disconnected gauge groups.

Asymptotic freedom in the axial and Coulomb gauges

International Nuclear Information System (INIS)

Frenkel, J.; Taylor, J.C.

1976-01-01

The sources of the negative contribution to the charge renormalization factor gsup(B)/g-1 in Yang-Mills theories are investigated in the axial and Coulomb gauges. In the axial gauge, a Kaellen dispersion relation exists but the spectral function is not positive definite because of the prescription that is used to integrate the singular polarization vectors. In the Coulomb gauge, the negative contributions are (to the lowest order) isolated in the Coulomb self-energy corrections to the Coulomb field. (Auth.)

Phases and amplitudes for a modified repulsive Coulomb field

International Nuclear Information System (INIS)

Chidichimo, M.C.; Davison, T.S.

1990-01-01

The asymptotic form of the radial wave function for positive-energy states is calculated for the case of a repulsive Coulomb field. The cases of a pure Coulomb potential and a modified Coulomb potential are considered. Second-order analytic solutions for the amplitudes and phases are obtained when the modifications to the pure Coulombic potential take the form αr -2 +βr -3 +γr -4 , using the Jeffreys or WKB method. For the case of a pure Coulomb field, numerical results obtained from this method were compared with ''exact'' numerical results that were obtained using the analytic properties of the Coulomb wave functions. Tables are presented to show the conditions under which the method is accurate

Intersite Coulomb interaction and Heisenberg exchange

NARCIS (Netherlands)

Eder, R; van den Brink, J.; Sawatzky, G.A

1996-01-01

Based on exact diagonalization results for small clusters we discuss the effect of intersite Coulomb repulsion in Mott-Hubbard or charge transfers insulators. Whereas the exchange constant J for direct exchange is enhanced by intersite Coulomb interaction, that for superexchange is suppressed. The

Poisson equation in the Kohn-Sham Coulomb problem

OpenAIRE

Manby, F. R.; Knowles, Peter James

2001-01-01

We apply the Poisson equation to the quantum mechanical Coulomb problem for many-particle systems. By introducing a suitable basis set, the two-electron Coulomb integrals become simple overlaps. This offers the possibility of very rapid linear-scaling treatment of the Coulomb contribution to Kohn-Sham theory.

8B + 208Pb Elastic Scattering at Coulomb Barrier Energies

Science.gov (United States)

La Commara, M.; Mazzocco, M.; Boiano, A.; Boiano, C.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Strano, E.; Torresi, D.; Yamaguchi, H.; Kahl, D.; Di Meo, P.; Grebosz, J.; Imai, N.; Hirayama, Y.; Ishiyama, H.; Iwasa, N.; Jeong, S. C.; Jia, H. M.; Kim, Y. H.; Kimura, S.; Kubono, S.; Lin, C. J.; Miyatake, H.; Mukai, M.; Nakao, T.; Nicoletto, M.; Sakaguchi, Y.; Sánchez-Benítez, A. M.; Soramel, F.; Teranishi, T.; Wakabayashi, Y.; Watanabe, Y. X.; Yang, L.; Yang, Y. Y.

2018-02-01

The scattering process of weakly-bound nuclei at Coulomb barrier energies provides deep insights on the reaction dynamics induced by exotic nuclei. Within this framework, we measured for the first time the scattering process of the short-lived Radioactive Ion Beam (RIB) 8B (Sp = 0.1375 MeV) from a 208Pb target at 50 MeV beam energy. The 8B RIB was produced by means of the in-flight facility CRIB (RIKEN, Japan) with an average intensity on target of 10 kHz and a purity about 25%. Elastically scattering ions were detected in the angular range θc.m. = 10°-160° by means of the detector array EXPADES. A preliminary optical model analysis indicates a total reaction cross section of about 1 b, a value, once reduced, 2-3 times larger than those obtained for the reactions induced by the stable weakly-bound projectiles 6,7Li on a 208Pb target in the energy range around the Coulomb barrier.

Coulomb effects in particle distributions inclusive

International Nuclear Information System (INIS)

Erazmus, B.; Martin, L.; Pluta, J.; Stavinky, A.

1997-01-01

Single pion distributions from central 158 A.GeV/c Pb + Pb collisions measured by the NA44 experiment show the effect of Coulomb interaction with the net charge produced during the reaction. Coulomb effects are analyzed with the help of the microscopic model RQMD and a model including the Coulomb interaction. Different sets of kinematical characteristics of the net charge have been used to reproduce the experimental data and a strong sensitivity to the charge value has been found. This study has evidenced the non-negligible influence of a Coulomb charge, present in the region of the central rapidity in heavy ion collisions on the inclusive distributions of the produced particles. A more thorough analysis of the data obtained from the experiment NA44 is now under way to take into account the hyperon decay that can modify the fraction of different particles, particularly at low transverse momenta

Coulomb string tension, asymptotic string tension, and the gluon chain

OpenAIRE

Greensite, Jeff; Szczepaniak, Adam P.

2014-01-01

We compute, via numerical simulations, the non-perturbative Coulomb potential of pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

Structure and Spectrum of Dust Coulomb Clusters

International Nuclear Information System (INIS)

Cheung, F.M.H.; Ford, C.; Barkby, S.; Samarian, A.A.; Vladimirov, S.V.

2005-01-01

In our study, the dynamics of Coulomb cluster systems were simulated for different number of particles. The spectra of energy states of dust Coulomb clusters corresponding to various packing sequences were obtained. The broadening of the spectrum due to inter-ring twist was discovered. It was found that the inter-ring twist will lead to a change in the energy spectrum of Coulomb cluster. This change was accompanied by a distortion of stable shells such that particles are able to compensate for any additional Coulomb energy (owing to the inter-ring twist) by further reducing their radial distance as much as possible. The overall effect is a change in the shape of the outer-shell from circular to elliptical

Tur\\'an type inequalities for regular Coulomb wave functions

OpenAIRE

Baricz, Árpád

2015-01-01

Tur\\'an, Mitrinovi\\'c-Adamovi\\'c and Wilker type inequalities are deduced for regular Coulomb wave functions. The proofs are based on a Mittag-Leffler expansion for the regular Coulomb wave function, which may be of independent interest. Moreover, some complete monotonicity results concerning the Coulomb zeta functions and some interlacing properties of the zeros of Coulomb wave functions are given.

Nucleon-nucleon correlations and the Coulomb Displacement Energy

International Nuclear Information System (INIS)

Van Neck, D.; Waroquier, M.; Heyde, K.

1997-01-01

Coulomb Displacement Energies (CDE) are accurately known for a wide range of nuclear masses. Assuming isospin independence in the nuclear Hamiltonian, the CDE can in first instance be interpreted as the Coulomb interaction energy between the density of the excess neutrons and the proton charge density in the parent nucleus. However, when using reasonable mean-field models for the proton and neutron density one underestimates the CDE by about 8% on average. This discrepancy is known as the Nolen-Schiffer anomaly, and various explanations have been put forward in the past. In this work the role of nucleon-nucleon correlations are re-examined. Calculations for the pair density functions in various nuclei are presented. Preliminary results suggest that the modifications to the mean-field pair density functions cause an enhancement of the CDE in the order of 4%, which is rather A-independent. (author)

Experiments on Coulomb ionization by charged particles

International Nuclear Information System (INIS)

Andersen, J.U.; Laegsgaard, E.; Lund, M.

1978-01-01

Inner-shell ionization by light projectiles, i.e., in very asymmetric collisions, is often denoted 'Coulomb ionization' because it is caused by the Coulomb interaction between the electron and the projectile. Although with little justification, the term is also used to distinquish such processes, in which the projectile Coulomb field is a small perturbation, from ionization in more violent, nearly symmetric ion-atom collisions. A discussion of Coulomb ionization of atomic K shells is given, with emphasis on experimental methods and results. The discussion is not intended as a review of the field but rather as a progress report on the anthor's work on the subject. A more detailed account was recently presented at the ICPEAC meeting in Paris. (Auth.)

Long-range terms in atomic collisions

International Nuclear Information System (INIS)

McGuire, J.H.; Weaver, O.L.

1986-01-01

Various separations, or ''gauge choices,'' are possible for the decomposition of the total Hamiltonian into electronic and internuclear terms. We show that, for one particular choice, all long-range Coulomb terms are associated with the internuclear motion. The potential then associated with electronic transitions is non-Coulombic. Some practical consequences of this gauge choice are discussed

Coulomb Blockade of Tunnel-Coupled Quantum Dots

National Research Council Canada - National Science Library

Golden, John

1997-01-01

.... Though classical charging models can explain the Coulomb blockade of an isolated dot, they must be modified to explain the Coulomb blockade of dots coupled through the quantum mechanical tunneling of electrons...

Theory of Coulomb drag for massless Dirac fermions

International Nuclear Information System (INIS)

Carrega, M; Principi, A; Polini, M; Tudorovskiy, T; Katsnelson, M I

2012-01-01

Coulomb drag between two unhybridized graphene sheets separated by a dielectric spacer has recently attracted considerable theoretical interest. We first review, for the sake of completeness, the main analytical results which have been obtained by other authors. We then illustrate pedagogically the minimal theory of Coulomb drag between two spatially separated two-dimensional systems of massless Dirac fermions which are both away from the charge-neutrality point. This relies on second-order perturbation theory in the screened interlayer interaction and on Boltzmann-transport theory. In this theoretical framework and in the low-temperature limit, we demonstrate that, to leading (i.e. quadratic) order in temperature, the drag transresistivity is completely insensitive to the precise intralayer momentum-relaxation mechanism (i.e. to the functional dependence of the transport scattering time on energy). We also provide analytical results for the low-temperature drag transresistivity for both cases of ‘thick’ and ‘thin’ spacers and for arbitrary values of the dielectric constants of the media surrounding the two Dirac-fermion layers. Finally, we present numerical results for the low-temperature drag transresistivity for the case when one of the media surrounding the Dirac-fermion layers has a frequency-dependent dielectric constant. We conclude by suggesting an experiment that can potentially allow for the observation of departures from the canonical quadratic-in-temperature behavior of the transresistivity. (paper)

A realistic solvable model for the Coulomb dissociation of neutron halo nuclei

International Nuclear Information System (INIS)

Baur, G.; Hencken, K.; Trautmann, D.

2003-01-01

As a model of a neutron halo nucleus we consider a neutron bound to an inert core by a zero range force. We study the breakup of this simple nucleus in the Coulomb field of a target nucleus. In the post-form DWBA (or, in our simple model CWBA (''Coulomb wave born approximation'')) an analytic solution for the T-matrix is known. We study limiting cases of this T-matrix. As it should be, we recover the Born approximation for weak Coulomb fields (i.e., for the relevant Coulomb parameters much smaller than 1). For strong Coulomb fields, high beam energies, and scattering to the forward region we find a result which is very similar to the Born result. It is only modified by a relative phase (close to 0) between the two terms and a prefactor (close to 1). A similar situation exists for bremsstrahlung emission. This formula can be related to the first order semiclassical treatment of the electromagnetic dissociation. Since our CWBA model contains the electromagnetic interaction between the core and the target nucleus to all orders, this means that higher order effects (including postacceleration effects) are small in the case of high beam energies and forward scattering. Our model also predicts a scaling behavior of the differential cross section, that is, different systems (with different binding energies, beam energies and scattering angles) show the same dependence on two variables x and y. (orig.)

Probing Minicharged Particles with Tests of Coulomb's Law

International Nuclear Information System (INIS)

Jaeckel, Joerg

2009-01-01

Minicharged particles arise in many extensions of the standard model. Their contribution to the vacuum polarization modifies Coulomb's law via the Uehling potential. In this Letter, we argue that tests for electromagnetic fifth forces can therefore be a sensitive probe of minicharged particles. In the low mass range < or approx. μeV existing constraints from Cavendish type experiments provide the best model-independent bounds on minicharged particles.

Radiative capture versus Coulomb dissociation

International Nuclear Information System (INIS)

Esbensen, H.; Physics

2006-01-01

Measurements of the Coulomb dissociation of 8 B have been used to infer the rate of the inverse radiative proton capture on 7 Be. The analysis is usually based on the assumptions that the two processes are related by detailed balance and described by E1 transitions. However, there are corrections to this relation. The Coulomb form factors for the two processes, for example, are not identical. There are also E2 transitions and higher-order effects in the Coulomb dissociation, and the nuclear induced breakup cannot always be ignored. While adding first-order E2 transitions enhances the decay energy spectrum, the other mechanisms cause a suppression at low relative energies. The net result may accidentally be close to the conventional first-order E1 calculation, but there are differences which cannot be ignored if accuracies of 10% or better are needed

Radiative Capture versus Coulomb Dissociation

International Nuclear Information System (INIS)

Esbensen, Henning

2006-01-01

Measurements of the Coulomb dissociation of 8B have been used to infer the rate of the inverse radiative proton capture on 7Be. The analysis is usually based on the assumptions that the two processes are related by detailed balance and described by E1 transitions. However, there are corrections to this relation. The Coulomb form factors for the two processes, for example, are not identical. There are also E2 transitions and higher-order effects in the Coulomb dissociation, and the nuclear induced breakup cannot always be ignored. While adding first-order E2 transitions enhances the decay energy spectrum, the other mechanisms cause a suppression at low relative energies. The net result may accidentally be close to the conventional first-order E1 calculation, but there are differences which cannot be ignored if accuracies of 10% or better are needed

Heat Coulomb blockade of one ballistic channel

Science.gov (United States)

Sivre, E.; Anthore, A.; Parmentier, F. D.; Cavanna, A.; Gennser, U.; Ouerghi, A.; Jin, Y.; Pierre, F.

2018-02-01

Quantum mechanics and Coulomb interaction dictate the behaviour of small circuits. The thermal implications cover fundamental topics from quantum control of heat to quantum thermodynamics, with prospects of novel thermal machines and an ineluctably growing influence on nanocircuit engineering. Experimentally, the rare observations thus far include the universal thermal conductance quantum and heat interferometry. However, evidence for many-body thermal effects paving the way to markedly different heat and electrical behaviours in quantum circuits remains wanting. Here we report on the observation of the Coulomb blockade of electronic heat flow from a small metallic circuit node, beyond the widespread Wiedemann-Franz law paradigm. We demonstrate this thermal many-body phenomenon for perfect (ballistic) conduction channels to the node, where it amounts to the universal suppression of precisely one quantum of conductance for the transport of heat, but none for electricity. The inter-channel correlations that give rise to such selective heat current reduction emerge from local charge conservation, in the floating node over the full thermal frequency range (laws for thermal transport in nanocircuits.

Screened Coulomb balls-structural properties and melting behaviour

International Nuclear Information System (INIS)

Golubnychiy, V; Baumgartner, H; Bonitz, M; Filinov, A; Fehske, H

2006-01-01

Classical molecular dynamics and Monte Carlo simulations are used to investigate three-dimensional spherical charged particle clusters which were experimentally observed in dusty plasmas (Arp et al 2004 Phys. Rev. Lett. 93 165005). The shell configuration and geometry of the ground state is found to change with the screening parameter. The melting temperature of small clusters exhibits a non-monotonic dependence on the total number of particles

Coulomb systems distorted at short distances in atomic and nuclear physics

International Nuclear Information System (INIS)

Popov, V.S.

1987-01-01

In systems bound by the Coulomb interaction distorted at short distances there may appear, under certain conditions, a rearrangment of atomic spectrum (or the Zel'dovich effect). Specific features of this effect are discussed for states with an arbitrary angular momentum l (both with and without the absorption). The equation is studied which connects nuclear level shifts with the low-energy scattering parameters a l , r l . The conditions have been found under which the rearrangement of spectrum is replaced by oscillations of atomic levels. The Coulomb renormalization of scattering lengths and that of effective ranges is discussed. Some manifestations of the Zel'dovich effect in the physics of hadronic atoms and mesomolecules are considered

Electron capture by alpha particles from helium atoms in a Coulomb-Born distorted-wave approximation

International Nuclear Information System (INIS)

Ghanbari-Adivi, E; Ghavaminia, H

2012-01-01

A three-body Coulomb-Born continuum distorted-wave approximation is applied to calculate the differential and total cross sections for single-electron exchange in the collision of fast alpha particles with helium atoms in their ground states. The applied first-order distorted wave theory satisfies correct Coulomb boundary conditions. Both post and prior forms of the transition amplitude are calculated. The nuclear-screening effect of the passive electron on the differential and total cross sections is investigated. The results are compared with those of other theories and with the available experimental data. For differential cross sections, the comparisons show a reasonable agreement with empirical measurements at higher impact energies. The agreement between experimental data and the present calculations for total cross sections with the average of the post and prior forms of the transition amplitude is reasonable at all the specified energies.

Role amplification of the coulomb interaction in nuclear reactions

Energy Technology Data Exchange (ETDEWEB)

Kumar, Ashok; Soni, S K; Pancholi, S K; Gupta, S L [AN SSSR, Moscow. Radiotekhnicheskij Inst.

1976-10-01

The genarally adopted estimate of coulomb interaction in nuclear reactions based on the comparison of relative energies of real particles participating in the reaction with the coulomb barrier has been shown to provide wrong presentation of the role of coulomb interaction in the reaction mechanism. The relative energy of particles participating in virtual processes forming the reaction mechanism and its relation to the coulomb barrier turn out to be tens of per cent less than for the particles in an inlet channel. This is the main reason of increasing the role of coulomb interaction in the reaction mechanism. This increase is particularly significant for nuclei with large charges, in particular, in heavy ion reaction.

Collisional scattering for binary Coulomb interactions that are cut off at a distance different than the Debye length

International Nuclear Information System (INIS)

Correa, J.R.; Chang Yongbin; Ordonez, C.A.

2005-01-01

Collisional scattering is considered within a system of charged particles experiencing binary Coulomb interactions when the scale length for the range of each interaction is not isotropic and is not necessarily equal to the Debye length. For example, one or more dimensions of the system could be smaller than the Debye length. The effect is assessed by evaluating integrals over the impact cross section. Cutoffs on both the impact parameter and the Coulomb interaction potential are employed, and no assumption is made regarding the value of the Coulomb logarithm. Two expressions are found that have a dependence on the cutoff lengths, with one of the expressions being associated with the Coulomb logarithm. Collisional scattering within an electrostatic ion trap is considered by way of example

Selfconsistent theory of Coulomb mixing in nuclei

International Nuclear Information System (INIS)

Pyatov, N.I.

1978-01-01

The theory of isobaric states is considered according to the Coulomb mixing in nuclei. For a given form of the isovestor potential the separable residual interactions are constructed by means of the isotopic invariance principle. The strength parameter of the force is found from a selfconsistency condition. The charge dependent force is represented by the Coulomb effective potential. The theory of the isobaric states is developed using the random phase approximation. The Coulomb mixing effects in the ground and isobaric 0 + states of even-mass nuclei are investigated

Coulomb Damping

Science.gov (United States)

Fay, Temple H.

2012-01-01

Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…

Eikonal representation of N-body Coulomb scattering amplitudes

International Nuclear Information System (INIS)

Fried, H.M.; Kang, K.; McKellar, B.H.J.

1983-01-01

A new technique for the construction of N-body Coulomb scattering amplitudes is proposed, suggested by the simplest case of N = 2: Calculate the scattering amplitude in eikonal approximation, discard the infinite phase factors which appear upon taking the limit of a Coulomb potential, and treat the remainder as an amplitude whose absolute value squared produces the exact, Coulomb differential cross section. The method easily generalizes to the N-body Coulomb problem for elastic scattering, and for inelastic rearrangement scattering of Coulomb bound states. We give explicit results for N = 3 and 4; in the N = 3 case we extract amplitudes for the processes (12)+3->1+2+3 (breakup), (12)+3->1+(23) (rearrangement), and (12)+3→(12)'+3 (inelastic scattering) as residues at the appropriate poles in the free-free amplitude. The method produces scattering amplitudes f/sub N/ given in terms of explicit quadratures over (N-2) 2 distinct integrands

The Coulomb potential in quantum mechanics and related topics

International Nuclear Information System (INIS)

Haeringen, H. van.

1978-01-01

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.)

On rate-state and Coulomb failure models

Science.gov (United States)

Gomberg, J.; Beeler, N.; Blanpied, M.

2000-01-01

We examine the predictions of Coulomb failure stress and rate-state frictional models. We study the change in failure time (clock advance) Δt due to stress step perturbations (i.e., coseismic static stress increases) added to "background" stressing at a constant rate (i.e., tectonic loading) at time t0. The predictability of Δt implies a predictable change in seismicity rate r(t)/r0, testable using earthquake catalogs, where r0 is the constant rate resulting from tectonic stressing. Models of r(t)/r0, consistent with general properties of aftershock sequences, must predict an Omori law seismicity decay rate, a sequence duration that is less than a few percent of the mainshock cycle time and a return directly to the background rate. A Coulomb model requires that a fault remains locked during loading, that failure occur instantaneously, and that Δt is independent of t0. These characteristics imply an instantaneous infinite seismicity rate increase of zero duration. Numerical calculations of r(t)/r0 for different state evolution laws show that aftershocks occur on faults extremely close to failure at the mainshock origin time, that these faults must be "Coulomb-like," and that the slip evolution law can be precluded. Real aftershock population characteristics also may constrain rate-state constitutive parameters; a may be lower than laboratory values, the stiffness may be high, and/or normal stress may be lower than lithostatic. We also compare Coulomb and rate-state models theoretically. Rate-state model fault behavior becomes more Coulomb-like as constitutive parameter a decreases relative to parameter b. This is because the slip initially decelerates, representing an initial healing of fault contacts. The deceleration is more pronounced for smaller a, more closely simulating a locked fault. Even when the rate-state Δt has Coulomb characteristics, its magnitude may differ by some constant dependent on b. In this case, a rate-state model behaves like a modified

Static and dynamic properties of two-dimensional Coulomb clusters.

Science.gov (United States)

Ash, Biswarup; Chakrabarti, J; Ghosal, Amit

2017-10-01

We study the temperature dependence of static and dynamic responses of Coulomb interacting particles in two-dimensional confinements across the crossover from solid- to liquid-like behaviors. While static correlations that investigate the translational and bond orientational order in the confinements show the footprints of hexatic-like phase at low temperatures, dynamics of the particles slow down considerably in this phase, reminiscent of a supercooled liquid. Using density correlations, we probe long-lived heterogeneities arising from the interplay of the irregularity in the confinement and long-range Coulomb interactions. The relaxation at multiple time scales show stretched-exponential decay of spatial correlations in irregular traps. Temperature dependence of characteristic time scales, depicting the structural relaxation of the system, show striking similarities with those observed for the glassy systems, indicating that some of the key signatures of supercooled liquids emerge in confinements with lower spatial symmetries.

Phase behaviour of charged colloidal sphere dispersions with added polymer chains

International Nuclear Information System (INIS)

Fortini, Andrea; Dijkstra, Marjolein; Tuinier, Remco

2005-01-01

We study the stability of mixtures of highly screened repulsive charged spheres and non-adsorbing ideal polymer chains in a common solvent using free volume theory. The effective interaction between charged colloids in an aqueous salt solution is described by a screened Coulomb pair potential, which supplements the pure hard-sphere interaction. The ideal polymer chains are treated as spheres that are excluded from the colloids by a hard-core interaction, whereas the interaction between two ideal chains is set to zero. In addition, we investigate the phase behaviour of charged colloid-polymer mixtures in computer simulations, using the two-body (Asakura-Oosawa pair potential) approximation to the effective one-component Hamiltonian of the charged colloids. Both our results obtained from simulations and from free volume theory show similar trends. We find that the screened Coulomb repulsion counteracts the effect of the effective polymer-mediated attraction. For mixtures of small polymers and relatively large charged colloidal spheres, the fluid-crystal transition shifts to significantly larger polymer concentrations with increasing range of the screened Coulomb repulsion. For relatively large polymers, the effect of the screened Coulomb repulsion is weaker. The resulting fluid-fluid binodal is only slightly shifted towards larger polymer concentrations upon increasing the range of the screened Coulomb repulsion. In conclusion, our results show that the miscibility of dispersions containing charged colloids and neutral non-adsorbing polymers increases upon increasing the range of the screened Coulomb repulsion, or upon lowering the salt concentration, especially when the polymers are small compared to the colloids

Electron-atom spin asymmetry and two-electron photodetachment - Addenda to the Coulomb-dipole threshold law

Science.gov (United States)

Temkin, A.

1984-01-01

Temkin (1982) has derived the ionization threshold law based on a Coulomb-dipole theory of the ionization process. The present investigation is concerned with a reexamination of several aspects of the Coulomb-dipole threshold law. Attention is given to the energy scale of the logarithmic denominator, the spin-asymmetry parameter, and an estimate of alpha and the energy range of validity of the threshold law, taking into account the result of the two-electron photodetachment experiment conducted by Donahue et al. (1984).

Intergrain Coupling in Dusty-Plasma Coulomb Crystals

International Nuclear Information System (INIS)

Mohideen, U.; Smith, M.A.; Rahman, H.U.; Rosenberg, M.; Mendis, D.A.

1998-01-01

We have studied the lattice structure of dusty-plasma Coulomb crystals formed in rectangular conductive grooves as a function of plasma temperature and density. The crystal appears to be made of mutually repulsive columns of grains confined by the walls of the groove. The columns are oriented along the direction of the electrode sheath electric field. A simple phenomenological model wherein the intergrain spacing results from an attractive electric-field-induced dipole-dipole force balanced by a repulsive monopole Coulomb force is consistent with observed features of the Coulomb crystal. copyright 1998 The American Physical Society

Approximate Coulomb effects in the three-body scattering problem

International Nuclear Information System (INIS)

Haftel, M.I.; Zankel, H.

1981-01-01

From the momentum space Faddeev equations we derive approximate expressions which describe the Coulomb-nuclear interference in the three-body elastic scattering, rearrangement, and breakup problems and apply the formalism to p-d elastic scattering. The approximations treat the Coulomb interference as mainly a two-body effect, but we allow for the charge distribution of the deuteron in the p-d calculations. Real and imaginary parts of the Coulomb correction to the elastic scattering phase shifts are described in terms of on-shell quantities only. In the case of pure Coulomb breakup we recover the distorted-wave Born approximation result. Comparing the derived approximation with the full Faddeev p-d elastic scattering calculation, which includes the Coulomb force, we obtain good qualitative agreement in S and P waves, but disagreement in repulsive higher partial waves. The on-shell approximation investigated is found to be superior to other current approximations. The calculated differential cross sections at 10 MeV raise the question of whether there is a significant Coulomb-nuclear interference at backward angles

Coulomb explosion of “hot spot”

Energy Technology Data Exchange (ETDEWEB)

Oreshkin, V. I., E-mail: oreshkin@ovpe.hcei.tsc.ru [Institute of High Current Electrons, SB, RAS, Tomsk (Russian Federation); Tomsk Polytechnic University, Tomsk (Russian Federation); Oreshkin, E. V. [P. N. Lebedev Physical Institute, RAS, Moscow (Russian Federation); Chaikovsky, S. A. [Institute of High Current Electrons, SB, RAS, Tomsk (Russian Federation); P. N. Lebedev Physical Institute, RAS, Moscow (Russian Federation); Institute of Electrophysics, UD, RAS, Ekaterinburg (Russian Federation); Artyomov, A. P. [Institute of High Current Electrons, SB, RAS, Tomsk (Russian Federation)

2016-09-15

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 the estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.

Coulomb explosion of “hot spot”

International Nuclear Information System (INIS)

Oreshkin, V. I.; Oreshkin, E. V.; 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 the estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.

Scattering and stopping of swift diatomic molecules under Coulomb explosion

International Nuclear Information System (INIS)

Sigmund, P.

1992-01-01

The scattering and stopping of the fragments of a fast diatomic molecule under Coulomb explosion has been analysed theoretically. The central assumption in the scheme is the dominance of Coulomb explosion, while electronic stopping (including wake forces) and elastic scattering are treated as perturbations. Charge exchange has been neglected. Coulomb images of penetration phenomena are heavily distorted. For small penetrated layer thicknesses, images appear contracted in the direction of the molecular axis, and expanded perpendicular to it. This distortion is described quantitatively by a linear transformation. General expressions have been derived for the effect of continuous and stochastic forces on the distribution of fragment velocities from Coulomb explosion (the ''ring pattern''). Moreover, relations have been found that allow to scale velocity distributions valid in the absence of Coulomb explosion into distributions allowing for Coulomb explosion. Applications concern the shift in ring pattern due to electronic stopping, the lateral broadening due to multiple scattering, and the effect of zero-point motion on the Coulomb image of a molecule. (orig.)

Scattering and stopping of swift diatomic molecules under Coulomb explosion

International Nuclear Information System (INIS)

Sigmund, P.

1991-01-01

The scattering and stopping of the fragments of a fast diatomic molecule under Coulomb explosion has been analyzed theoretically. The central assumption in the scheme is the dominance of Coulomb explosion, while electronic stopping (including wake forces) and elastic scattering are treated as perturbations. Charge exchange has been neglected. Coulomb images of penetration phenomena are heavily distorted. For small penetrated layer thicknesses, images appear contracted in the direction of the molecular axis, and expanded perpendicular to it. This distortion is described quantitatively by a linear transformation. General expressions have been derived for the effect of continuous and stochastic forces on the distribution of fragment velocities from Coulomb explosion (the ''ring pattern''). Moreover, relations have been found that allow to scale velocity distributions valid in the absence of Coulomb explosion into distributions allowing for Coulomb explosion. Applications concern the shift in ring pattern due to electronic stopping, the lateral broadening due to multiple scattering and the effect of zero-point motion on the Coulomb image of a molecule. 14 refs., 5 figs

Subcycle dynamics of Coulomb asymmetry in strong elliptical laser fields.

Science.gov (United States)

Li, Min; Liu, Yunquan; Liu, Hong; Ning, Qicheng; Fu, Libin; Liu, Jie; Deng, Yongkai; Wu, Chengyin; Peng, Liang-You; Peng, Liangyou; Gong, Qihuang

2013-07-12

We measure photoelectron angular distributions of noble gases in intense elliptically polarized laser fields, which indicate strong structure-dependent Coulomb asymmetry. Using a dedicated semiclassical model, we have disentangled the contribution of direct ionization and multiple forward scattering on Coulomb asymmetry in elliptical laser fields. Our theory quantifies the roles of the ionic potential and initial transverse momentum on Coulomb asymmetry, proving that the small lobes of asymmetry are induced by direct ionization and the strong asymmetry is induced by multiple forward scattering in the ionic potential. Both processes are distorted by the Coulomb force acting on the electrons after tunneling. Lowering the ionization potential, the relative contribution of direct ionization on Coulomb asymmetry substantially decreases and Coulomb focusing on multiple rescattering is more important. We do not observe evident initial longitudinal momentum spread at the tunnel exit according to our simulation.

Charge independence and charge symmetry breaking interactions and the Coulomb energy anomaly in isobaric analog states

International Nuclear Information System (INIS)

Suzuki, Toshio; Sagawa, H.; Giai, N. van.

1992-01-01

Effects of CIB (charge independence breaking) and CSB (charge symmetry breaking) interactions on the Coulomb displacement energies of isobaric analog states are investigated for 48 Ca, 90 Zr and 208 Pb. Mass number dependence of the Coulomb energy anomalies is well explained when CIB and CSB interactions are used which reproduce the differences of the scattering lengths as well as those of the effective ranges of low energy nucleon-nucleon scattering. (author) 17 refs., 3 figs., 3 tabs

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 (cotunneling......) processes as well as energy-dependent lead couplings, and identify a mesoscopic Coulomb drag mechanism driven by nonlocal multi-electron 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...... on Coulomb drag in CQD systems....

Coulomb gap triptych in a periodic array of metal nanocrystals.

Science.gov (United States)

Chen, Tianran; Skinner, Brian; Shklovskii, B I

2012-09-21

The Coulomb gap in the single-particle density of states (DOS) is a universal consequence of electron-electron interaction in disordered systems with localized electron states. Here we show that in arrays of monodisperse metallic nanocrystals, there is not one but three identical adjacent Coulomb gaps, which together form a structure that we call a "Coulomb gap triptych." We calculate the DOS and the conductivity in two- and three-dimensional arrays using a computer simulation. Unlike in the conventional Coulomb glass models, in nanocrystal arrays the DOS has a fixed width in the limit of large disorder. The Coulomb gap triptych can be studied via tunneling experiments.

Coulomb excitation of 189Os

International Nuclear Information System (INIS)

Brandao, S.B.

1987-01-01

The level structure of 189 Os has been studied by Coulomb excitation using 35 Cl, 28 Si, 16 O beams. GOSIA, a code written to analyze multiple Coulomb excitation, was used to obtain the reduced probabilities of transition B(E2). The results for interband and intraband turned out possible the classification of the states following Nilsson levels. Gamma-rays originating from deexcitation of 216.7 and 219.4 keV have been separated and the reduced probability of transition has been measured. (A.C.A.S.) [pt

Detection method of elastic scattering in the Coulomb interference region: scintillation target

International Nuclear Information System (INIS)

Azaiez, Hamza.

1981-01-01

Measurement of polarization in (p-p) elastic scattering in the Coulomb interference region is considered as a valid method for calibrating high energy polarized proton beams. Possibility of using a scintillation target to detect low energy recoil protons in this /t/ region has been studied by using a 4 GeV/c π - beam from CERN PS. The results obtained with a steack of thin plastic scintillators, each 1 mm thick, showed the feasibility of detecting recoil protons in a /t/ range as low a 5.10 -3 (GeV/c) 2 . This method thus confirmed experimentally can be used also to measure, using a polarized beam, polarization in Coulomb interference region [fr

Examining the role of Coulomb static stress transfer in injection-induced seismicity: a generic modeling approach

Science.gov (United States)

Brown, M. R. M.; Ge, S.

2017-12-01

Increased pore pressure decreasing the effective stress on a critically stressed fault has been the accepted mechanism for injection-induced seismicity. This, however, is an over simplified approach that does not take into account the coupled hydro-mechanical effects. In addition, this approach leaves out a possible key stressor in the system, the earthquakes. Earthquakes are known to interact with each other by Coulomb static stress transfer, the process of permanent stress change caused by movement on a fault. In areas of induced seismicity, many small to moderate earthquakes can occur adding to the stress in the system via Coulomb static stress transfer. Here we ask: Is the Coulomb static stress transfer from the earthquakes as important as the pore pressure increase or stress changes caused by coupled hydro-mechanical processes? Is there a point where the Coulomb static stress transfer from the earthquakes becomes the controlling process for inducing future earthquakes? How does the effect of many small earthquakes compare to a few larger events in terms of Coulomb static stress transfer? In this study, we use hydrologic and coupled hydro-mechanical models and USGS Coulomb 3 to assess the importance of induced earthquakes in terms of the stress change in the system. Realistic scenarios of wastewater injection and earthquake magnitude-frequency distributions are used to develop generic models. Model variables and data are varied to evaluate the range of possible outcomes. Preliminary results show that the stress change associated with injection is of the same order of magnitude as the cumulative Coulomb static stress change of a series of small (1

Measurements of electric charge and screening length of microparticles in a plasma sheath

International Nuclear Information System (INIS)

Nakamura, Y.; Ishihara, O.

2009-01-01

An experiment is described in which microparticles are levitated within a rf sheath above a conducting plate in argon plasma. The microparticles forming a two-dimensional crystal structure are considered to possess Debye screening Coulomb potential φ(r)=(Q/4πε 0 r)exp(-r/λ), where Q is the electric charge, r is distance, and λ is the screening length. When the crystal structure is slanted with an angle θ, a particle experiences a force Mg sin θ, where M is the mass of the particle and g is acceleration due to gravity, which must be equal to the Debye screened Coulomb force from other particles. By changing θ, relations for λ(Q) are measured. The screening length λ and Q are determined uniquely from the crossing points of several relations. The electric charge Q is also estimated from a floating potential measured with a probe. The measured λ is nearly equal to an ion Debye length.

Relativistic Coulomb excitation

International Nuclear Information System (INIS)

Winther, A.; Alder, K.

1979-01-01

Coulomb excitation of both target and projectile in relativistic heavy ion collisions is evaluated including the lowest order correction for the deviation from a straight line trajectory. Explicit results for differential and total cross sections are given in the form of tables and figures. (Auth.)

Gravity duals for the Coulomb branch of marginally deformed N=4 Yang-Mills

CERN Document Server

Hernández, R; Zoakos, D; Hernandez, Rafael; Sfetsos, Konstadinos; Zoakos, Dimitrios

2006-01-01

Supergravity backgrounds dual to a class of exactly marginal deformations of N supersymmetric Yang-Mills can be constructed through an SL(2,R) sequence of T-dualities and coordinate shifts. We apply this transformation to multicenter solutions and derive supergravity backgrounds describing the Coulomb branch of N=1 theories at strong 't Hooft coupling as marginal deformations of N=4 Yang-Mills. For concreteness we concentrate to cases with an SO(4)xSO(2) symmetry preserved by continuous distributions of D3-branes on a disc and on a three-dimensional spherical shell. We compute the expectation value of the Wilson loop operator and confirm the Coulombic behaviour of the heavy quark-antiquark potential in the conformal case. When the vev is turned on we find situations where a complete screening of the potential arises, as well as a confining regime where a linear or a logarithmic potential prevails depending on the ratio of the quark-antiquark separation to the typical vev scale. The spectra of massless excitat...

Coulomb dissociation of N-20,N-21

NARCIS (Netherlands)

Roeder, 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.; 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; Gernhaeuser, Roman; Goebel, Kathrin; Kalantar-Nayestanaki, Nasser; Najafi, Mohammad Ali; Rigollet, Catherine; Stoica, V.; Streicher, Branislav; Van de Walle, J.

2016-01-01

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-20,N-21 are reported. Relativistic N-20,N-21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a

Ordering in classical Coulombic systems

International Nuclear Information System (INIS)

Schiffer, J. P.

1998-01-01

The author discusses the properties of classical Coulombic matter at low temperatures. It has been well known for some time [1,2] that infinite Coulombic matter will crystallize in body-centered cubic form when the quantity Λ (the dimensionless ratio of the average two-particle Coulomb energy to the kinetic energy per particle) is larger than approximately175. But the systems of such particles that have been produced in the laboratory in ion traps, or ion beams, are finite with surfaces defined by the boundary conditions that have to be satisfied. This results in ion clouds with sharply defined curved surfaces, and interior structures that show up as a set of concentric layers that are parallel to the outer surface. The ordering does not appear to be cubic, but the charges on each shell exhibit a ''hexatic'' pattern of equilateral triangles that is the characteristic of liquid crystals. The curvature of the surfaces prevents the structures on successive shells from interlocking in any simple fashion. This class of structures was first found in simulations [3] and later in experiments [4

Generalized coherent states for the Coulomb problem in one dimension

International Nuclear Information System (INIS)

Nouri, S.

2002-01-01

A set of generalized coherent states for the one-dimensional Coulomb problem in coordinate representation is constructed. At first, we obtain a mapping for proper transformation of the one-dimensional Coulomb problem into a nonrotating four-dimensional isotropic harmonic oscillator in the hyperspherical space, and the generalized coherent states for the one-dimensional Coulomb problem is then obtained in exact closed form. This exactly soluble model can provide an adequate means for a quantum coherency description of the Coulomb problem in one dimension, sample for coherent aspects of the exciton model in one-dimension example in high-temperature superconductivity, semiconductors, and polymers. Also, it can be useful for investigating the coherent scattering of the Coulomb particles in one dimension

Screening effects in plasma with charged Bose condensate

International Nuclear Information System (INIS)

Dolgov, Alexander D.; Lepidi, Angela; Piccinelli, Gabriella

2009-01-01

The screening of a Coulomb field of test charge in plasma with a Bose condensate of an electrically charged scalar field is considered. It is found that the screened potential contains several different terms: one decreases as a power of distance (in contrast to the usual exponential Debye screening), and some others oscillate with an exponentially decreasing envelope. A similar phenomenon exists for fermions (Friedel oscillations), but fermionic and bosonic systems have quite different features. Several limiting cases and values of the parameters are considered and the resulting potentials are presented.

Coulomb repulsion in short polypeptides.

Science.gov (United States)

Norouzy, Amir; Assaf, Khaleel I; Zhang, Shuai; Jacob, Maik H; Nau, Werner M

2015-01-08

Coulomb repulsion between like-charged side chains is presently viewed as a major force that impacts the biological activity of intrinsically disordered polypeptides (IDPs) by determining their spatial dimensions. We investigated short synthetic models of IDPs, purely composed of ionizable amino acid residues and therefore expected to display an extreme structural and dynamic response to pH variation. Two synergistic, custom-made, time-resolved fluorescence methods were applied in tandem to study the structure and dynamics of the acidic and basic hexapeptides Asp6, Glu6, Arg6, Lys6, and His6 between pH 1 and 12. (i) End-to-end distances were obtained from the short-distance Förster resonance energy transfer (sdFRET) from N-terminal 5-fluoro-l-tryptophan (FTrp) to C-terminal Dbo. (ii) End-to-end collision rates were obtained for the same peptides from the collision-induced fluorescence quenching (CIFQ) of Dbo by FTrp. Unexpectedly, the very high increase of charge density at elevated pH had no dynamical or conformational consequence in the anionic chains, neither in the absence nor in the presence of salt, in conflict with the common view and in partial conflict with accompanying molecular dynamics simulations. In contrast, the cationic peptides responded to ionization but with surprising patterns that mirrored the rich individual characteristics of each side chain type. The contrasting results had to be interpreted, by considering salt screening experiments, N-terminal acetylation, and simulations, in terms of an interplay of local dielectric constant and peptide-length dependent side chain charge-charge repulsion, side chain functional group solvation, N-terminal and side chain charge-charge repulsion, and side chain-side chain as well as side chain-backbone interactions. The common picture that emerged is that Coulomb repulsion between water-solvated side chains is efficiently quenched in short peptides as long as side chains are not in direct contact with each

On the theory for Coulomb break-up of deuterons by atomic nuclei at low energy

International Nuclear Information System (INIS)

Grantsev, V.I.; Evlanov, M.V.

1982-01-01

The influence of a finite range of nuclear forces between nucleons in the deuteron on angular and energy distributions for products of deuteron disintegration by the Coulomb field of nucleus is investigated. This effect leads to the difference of differential cross sections of Coulomb deuteron disintegration from differential cross sections obtained in the framework of the approximation of the zero-radius interaction. Angular and energy dependences of differential cross sections of deuteron disintegration with the energy of 13.6 MeV on the 208 Pb nucleus are given [ru

Two-center Coulomb problem with Calogero interaction

Energy Technology Data Exchange (ETDEWEB)

Hakobyan, T., E-mail: tigran.hakobyan@ysu.am; Nersessian, A., E-mail: arnerses@ysu.am [Armenia Tomsk Polytechnic University, Yerevan State University (Russian Federation)

2017-03-15

We show that the Calogero-type perturbation preserves the integrability and partial separation of variables for the Stark–Coulomb and two-center Coulomb problems, and present the explicit expressions of their constants of motion. We reveal that this perturbation preserves the spectra of initial systems, but leads to the change of degree of degeneracy.

On Coulomb disintegration of relativistic nuclei and hypernuclei

International Nuclear Information System (INIS)

Lyuboshits, V.L.

1989-01-01

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-Λ 3 H into a deuteron and Λ-particle. 12 refs

Empirical Coulomb matrix elements and the mass of 22Al

International Nuclear Information System (INIS)

Whitehead, R.R.; Watt, A.; Kelvin, D.; Rutherford, H.J.

1976-01-01

An attempt has been made to obtain a set of Coulomb matrix elements which fit the known Coulomb energy shifts in the nuclei of mass 18 to 22. The interaction obtained fits the data well with only a few exceptions, one of these being the Coulomb shift of the notorious third 0 + state in 18 Ne. These Coulomb matrix elements are used together with the Chung-Wildenthal interaction to obtain a new prediction for the mass excess of 22 Al. The results indicate that 22 Al should be bound against proton emission. (Auth.)

Coulomb Dissociation as a Tool of Nuclear Astrophysics

International Nuclear Information System (INIS)

Utsunomiya, H.

2000-01-01

My talk will begin with an introduction of the Coulomb dissociation method, proceed to discussions on Coulomb breakup of 7 Li with respect to the big-bang nucleosynthesis and end with the revision of astrophysical S-factors. The methodology based on the virtual photon source will be introduced in view of experimental techniques. The discussion will include the quantum tunnelling effect in non-resonant breakup, the lifetime of continuum states, and Coulomb distortion of relevant cross sections. Roles of multi-step processes and different multipolarities will also be discussed on the basis of solving a time-dependent Schroedinger equation. My talk will present quantitative results. The theoretical framework of the Coulomb dissociation method and a broad scope of its applications are given by G. Baur. Applications to radioactive nuclei which have quickly become vogue are discussed in the related lecture of J. Kiener. (author)

Revision of FMM-Yukawa: An adaptive fast multipole method for screened Coulomb interactions

Science.gov (United States)

Zhang, Bo; Huang, Jingfang; Pitsianis, Nikos P.; Sun, Xiaobai

2010-12-01

FMM-YUKAWA is a mathematical software package primarily for rapid evaluation of the screened Coulomb interactions of N particles in three dimensional space. Since its release, we have revised and re-organized the data structure, software architecture, and user interface, for the purpose of enabling more flexible, broader and easier use of the package. The package and its documentation are available at http://www.fastmultipole.org/, along with a few other closely related mathematical software packages. New version program summaryProgram title: FMM-Yukawa Catalogue identifier: AEEQ_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEQ_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPL 2.0 No. of lines in distributed program, including test data, etc.: 78 704 No. of bytes in distributed program, including test data, etc.: 854 265 Distribution format: tar.gz Programming language: FORTRAN 77, FORTRAN 90, and C. Requires gcc and gfortran version 4.4.3 or later Computer: All Operating system: Any Classification: 4.8, 4.12 Catalogue identifier of previous version: AEEQ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 180 (2009) 2331 Does the new version supersede the previous version?: Yes Nature of problem: To evaluate the screened Coulomb potential and force field of N charged particles, and to evaluate a convolution type integral where the Green's function is the fundamental solution of the modified Helmholtz equation. Solution method: The new version of fast multipole method (FMM) that diagonalizes the multipole-to-local translation operator is applied with the tree structure adaptive to sample particle locations. Reasons for new version: To handle much larger particle ensembles, to enable the iterative use of the subroutines in a solver, and to remove potential contention in assignments for parallelization. Summary of revisions: The software package FMM-Yukawa has been

Coulomb sum rules in the relativistic Fermi gas model

International Nuclear Information System (INIS)

Do Dang, G.; L'Huillier, M.; Nguyen Giai, Van.

1986-11-01

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 40 Ca data to obtain the experimental Coulomb sum rule as a function of momentum transfer

The exact solution of a four-body Coulomb problem

Science.gov (United States)

Ray, Hasi

2018-03-01

The elastic collision between two H-like atoms utilizing an ab initio static-exchange model (SEM) in the center of mass (CM) frame considering the system as a four-body Coulomb problem where all the Coulomb interaction terms in the direct and exchange channels are treated exactly, is studied thoroughly. A coupled-channel methodology in momentum space is used to solve Lippman-Schwinger equation following the integral approach. The new SEM code [Ray, Pramana 83, 907 (2014)] in which the Born-Oppenheimer (BO) scattering amplitude acts as input to derive the SEM amplitude using partial wave analysis, is utilized to study the s-, p-, d-wave elastic phase shifts and the corresponding partial cross sections. An augmented-Born approximation is used to include the contribution of higher partial waves more accurately to determine the total/integrated elastic cross sections. The effective range theory is used to determine the scattering lengths and effective ranges in the s-wave elastic scattering. The systems studied are Ps-Ps, Ps-Mu, Ps-H, Ps-D, Ps-T, Mu-Mu, Mu-H, Mu-D, Mu-T, H-H, H-D, H-T, D-D, D-T, T-T. The SEM includes the non-adiabatic short-range effects due to exchange. The MSEM code [Ray, Pramana 83, 907 (2014)] is used to study the effect of the long-range van der Waals interaction due to induced dipole polarizabilities of the atoms in H(1s)-H(1s) elastic collision. The dependence of scattering length on the reduced mass of the system and the dependence of scattering length on the strength of long-range van der Waals interaction that varies with the minimum interatomic distance are observed. Contribution to the Topical Issue "Low Energy Positron and Electron Interactions", edited by James Sullivan, Ron White, Michael Bromley, Ilya Fabrikant, and David Cassidy.

Coulomb displacement energies in nuclei: a new approach

International Nuclear Information System (INIS)

Auerbach, N.; Tel Aviv Univ.; Bernard, V.; Nguyen, V.G.

1978-04-01

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 48 Ca, 88 Sr and 208 Pb have been calculated using Skyrme interactions SIII and SIV. A good agreement with experiment is obtained

Coulomb interaction rules timescales in potassium ion channel tunneling

Science.gov (United States)

De March, N.; Prado, S. D.; Brunnet, L. G.

2018-06-01

Assuming the selectivity filter of KcsA potassium ion channel may exhibit quantum coherence, we extend a previous model by Vaziri and Plenio (2010 New J. Phys. 12 085001) to take into account Coulomb repulsion between potassium ions. We show that typical ion transit timescales are determined by this interaction, which imposes optimal input/output parameter ranges. Also, as observed in other examples of quantum tunneling in biological systems, the addition of moderate noise helps coherent ion transport.

Coulomb Friction Damper

Science.gov (United States)

Appleberry, W. T.

1983-01-01

Standard hydraulic shock absorber modified to form coulomb (linear friction) damper. Device damps very small velocities and is well suited for use with large masses mounted on soft springs. Damping force is easily adjusted for different loads. Dampers are more reliable than fluid dampers and also more economical to build and to maintain.

Renormalizable Non-Covariant Gauges and Coulomb Gauge Limit

CERN Document Server

Baulieu, L

1999-01-01

To study ``physical'' gauges such as the Coulomb, light-cone, axial or temporal gauge, we consider ``interpolating'' gauges which interpolate linearly between a covariant gauge, such as the Feynman or Landau gauge, and a physical gauge. Lorentz breaking by the gauge-fixing term of interpolating gauges is controlled by extending the BRST method to include not only the local gauge group, but also the global Lorentz group. We enumerate the possible divergences of interpolating gauges, and show that they are renormalizable, and we show that the expectation value of physical observables is the same as in a covariant gauge. In the second part of the article we study the Coulomb-gauge as the singular limit of the Landau-Coulomb interpolating gauge. We find that unrenormalized and renormalized correlation functions are finite in this limit. We also find that there are finite two-loop diagrams of ``unphysical'' particles that are not present in formal canonical quantization in the Coulomb gauge. We verify that in the ...

Observation of a Coulomb flux tube

Science.gov (United States)

Greensite, Jeff; Chung, Kristian

2018-03-01

In Coulomb gauge there is a longitudinal color electric field associated with a static quark-antiquark pair. We have measured the spatial distribution of this field, and find that it falls off exponentially with transverse distance from a line joining the two quarks. In other words there is a Coulomb flux tube, with a width that is somewhat smaller than that of the minimal energy flux tube associated with the asymptotic string tension. A confinement criterion for gauge theories with matter fields is also proposed.

Dimensional regularization and renormalization of Coulomb gauge quantum electrodynamics

International Nuclear Information System (INIS)

Heckathorn, D.

1979-01-01

Quantum electrodynamics is renormalized in the Coulomb gauge with covariant counter terms and without momentum-dependent wave-function renormalization constants. It is shown how to dimensionally regularize non-covariant integrals occurring in this guage, and prove that the 'minimal' subtraction prescription excludes non-covariant counter terms. Motivated by the need for a renormalized Coulomb gauge formalism in certain practical calculations, the author introduces a convenient prescription with physical parameters. The renormalization group equations for the Coulomb gauge are derived. (Auth.)

Coulomb corrections for interferometry analysis of expanding hadron systems

Energy Technology Data Exchange (ETDEWEB)

Sinyukov, Yu.M.; Lednicky, R.; Pluta, J.; Erazmus, B. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees; Akkelin, S.V. [ITP, Kiev (Ukraine)

1997-09-01

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 {pi}{sup +}{pi}{sup +} and K{sup +}K{sup +} correlation functions the analytical calculations of the Coulomb correction are compared with the exact numerical results. (author). 20 refs.

Heat flux dropouts in the solar wind and Coulomb scattering effects

International Nuclear Information System (INIS)

Fitzenreiter, R.J.; Ogilvie, K.W.

1992-01-01

Measurements of solar wind electrons at ISEE 3 located 0.01 AU upstream from the Earth indicate periods of time when the flux of antisunward suprathermal electrons decreases suddenly, leaving the velocity distribution nearly isotropic and causing the solar wind heat flux to drop. These heat flux dropouts (HFDs) are usually found in regions of increased plasma density and decreased electron temperature, and they are associated with sector boundaries. It has been suggested that HFDs may be due either to disconnection from the Sun of the magnetic flux tube in which they are found, or to enhanced Coulomb scattering of halo electrons in transit from the Sun to the Earth. Using the vector electron spectrometer on ISEE 1, the authors have found eight intervals of greatly reduced heat flux which appear to be associated with HFDs at ISEE 3. Five of the eight events were delayed by an appropriate convection time and had approximately the same duration as the corresponding ISEE 3 event. Velocity distributions during HFDs at ISEE 1 show that the depletion of halo electrons traveling away from the Sun is most pronounced in the 100-eV range, while there is essentially no depletion in the 1-keV range, and that in four cases the magnitude of the halo depletion and its upper velocity limit both depend on the density increase in the HFD. These results are shown to be in agreement with the υ -3 dependence of the Coulomb collision frequency. Thus the authors conclude that Coulomb scattering effects play a substantial role in at least some heat flux dropout events

Coulomb Mediated Hybridization of Excitons in Coupled Quantum Dots.

Science.gov (United States)

Ardelt, P-L; Gawarecki, K; Müller, K; Waeber, A M; Bechtold, A; Oberhofer, K; Daniels, J M; Klotz, F; Bichler, M; Kuhn, T; Krenner, H J; Machnikowski, P; Finley, J J

2016-02-19

We report Coulomb mediated hybridization of excitonic states in optically active InGaAs quantum dot molecules. By probing the optical response of an individual quantum dot molecule as a function of the static electric field applied along the molecular axis, we observe unexpected avoided level crossings that do not arise from the dominant single-particle tunnel coupling. We identify a new few-particle coupling mechanism stemming from Coulomb interactions between different neutral exciton states. Such Coulomb resonances hybridize the exciton wave function over four different electron and hole single-particle orbitals. Comparisons of experimental observations with microscopic eight-band k·p calculations taking into account a realistic quantum dot geometry show good agreement and reveal that the Coulomb resonances arise from broken symmetry in the artificial semiconductor molecule.

Coulomb matrix elements in multi-orbital Hubbard models.

Science.gov (United States)

Bünemann, Jörg; Gebhard, Florian

2017-04-26

Coulomb matrix elements are needed in all studies in solid-state theory that are based on Hubbard-type multi-orbital models. Due to symmetries, the matrix elements are not independent. We determine a set of independent Coulomb parameters for a d-shell and an f-shell and all point groups with up to 16 elements (O h , O, T d , T h , D 6h , and D 4h ). Furthermore, we express all other matrix elements as a function of the independent Coulomb parameters. Apart from the solution of the general point-group problem we investigate in detail the spherical approximation and first-order corrections to the spherical approximation.

Cavity QED experiments with ion Coulomb crystals

DEFF Research Database (Denmark)

Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan

2009-01-01

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....

Perturbative ambiguities in Coulomb gauge QCD

International Nuclear Information System (INIS)

Doust, P.

1987-01-01

The naive Coulomb gauge Feynman rules in non-abelian gauge theory give rise to ambiguous integrals, in addition to the usual ultraviolet divergences. Generalizing the work of Cheng and Tsai, these ambiguities are resolved to all orders in perturbation theory, by defining a gauge that interpolates smoothly between the Feynman gauge and the Coulomb gauge. The extra terms V 1 +V 2 of Christ and Lee are identified with certain two-loop ambiguous terms. However, there still seem to be unsolved problems connected with renormalisation. copyright 1987 Academic Press, Inc

Coulomb dissociation of N 20,21

OpenAIRE

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

2016-01-01

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 N20,21 are reported. Relativistic N20,21 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 N19(n,γ)N20 and N20(n,γ)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,γ)N20 rate is...

Coulomb singularity effects in tunnelling spectroscopy of individual impurities

OpenAIRE

Arseyev, P. I.; Maslova, N. S.; Panov, V. I.; Savinov, S. V.

2002-01-01

Non-equilibrium Coulomb effects in resonant tunnelling processes through deep impurity states are analyzed. It is shown that Coulomb vertex corrections to the tunnelling transfer amplitude lead to a power-law singularity in current- voltage characteristics

Review of stopping power and Coulomb explosion for molecular ion in plasmas

Directory of Open Access Journals (Sweden)

Guiqiu Wang

2018-03-01

Full Text Available We summarize our theoretical studies for stopping power of energetic heavy ion, diatomic molecular ions and small clusters penetrating through plasmas. As a relevant research field for the heavy ion inertial confinement fusion (HICF, we lay the emphasis on the dynamic polarization and correlation effects of the constituent ion within the molecular ion and cluster for stopping power in order to disclose the role of the vicinage effect on the Coulomb explosion and energy deposition of molecules and clusters in plasma. On the other hand, as a promising scheme for ICF, both a strong laser field and an intense ion beam are used to irradiate a plasma target. So the influence of a strong laser field on stopping power is significant. We discussed a large range of laser and plasma parameters on the coulomb explosion and stopping power for correlated-ion cluster and C60 cluster. Furthermore, in order to indicate the effects of different cluster types and sizes on the stopping power, a comparison is made for hydrogen and carbon clusters. In addition, the deflection of molecular axis for diatomic molecules during the Coulomb explosion is also given for the cases both in the presence of a laser field and laser free. Finally, a future experimental scheme is put forward to measure molecular ion stopping power in plasmas in Xi'an Jiaotong University of China. Keywords: Molecules, Stopping power, Coulomb explosion, Vicinage effect, Laser, PACS Codes: 34.50.Bw, 52.40.Mj, 61.85.+p, 34.50.Dy

The Coulomb Branch of 3d N= 4 Theories

Science.gov (United States)

Bullimore, Mathew; Dimofte, Tudor; Gaiotto, Davide

2017-09-01

We propose a construction for the quantum-corrected Coulomb branch of a general 3d gauge theory with N=4 supersymmetry, in terms of local coordinates associated with an abelianized theory. In a fixed complex structure, the holomorphic functions on the Coulomb branch are given by expectation values of chiral monopole operators. We construct the chiral ring of such operators, using equivariant integration over BPS moduli spaces. We also quantize the chiral ring, which corresponds to placing the 3d theory in a 2d Omega background. Then, by unifying all complex structures in a twistor space, we encode the full hyperkähler metric on the Coulomb branch. We verify our proposals in a multitude of examples, including SQCD and linear quiver gauge theories, whose Coulomb branches have alternative descriptions as solutions to Bogomolnyi and/or Nahm equations.

Critical opalescence in the pure Coulomb system

Energy Technology Data Exchange (ETDEWEB)

Bobrov, V.B., E-mail: vic5907@mail.r [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaia St., 13, Bd. 2. Moscow 125412 (Russian Federation); Trigger, S.A., E-mail: satron@mail.r [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaia St., 13, Bd. 2. Moscow 125412 (Russian Federation); Institut fuer Physik, Humboldt-Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany)

2011-04-18

Highlights: The review of the critical opalescence problem is presented. Light scattering in a two-component electron-nuclear system is studied. The exact relations between the structure factors and compressibility are found. The obtained relations are valid for strong interaction for the Coulomb systems. The experimental verification of these relations is possible for various elements. - Abstract: Based on the dielectric formalism and quantum field theory methods, the phenomenon of critical opalescence is explained for light scattering in pure matter as a two-component electron-nuclear system with Coulomb interaction. A similar phenomenon is shown to occur in the case of neutron scattering in pure substances as well. The obtained results are valid for quantum case and arbitrary strong Coulomb interaction. Thus, the relations between structure factors derived for the electron-nuclear system are the exact result of the quantum statistical mechanics.

Coulomb energy of uniformly charged spheroidal shell systems.

Science.gov (United States)

Jadhao, Vikram; Yao, Zhenwei; Thomas, Creighton K; de la Cruz, Monica Olvera

2015-03-01

We provide exact expressions for the electrostatic energy of uniformly charged prolate and oblate spheroidal shells. We find that uniformly charged prolate spheroids of eccentricity greater than 0.9 have lower Coulomb energy than a sphere of the same area. For the volume-constrained case, we find that a sphere has the highest Coulomb energy among all spheroidal shells. Further, we derive the change in the Coulomb energy of a uniformly charged shell due to small, area-conserving perturbations on the spherical shape. Our perturbation calculations show that buckling-type deformations on a sphere can lower the Coulomb energy. Finally, we consider the possibility of counterion condensation on the spheroidal shell surface. We employ a Manning-Oosawa two-state model approximation to evaluate the renormalized charge and analyze the behavior of the equilibrium free energy as a function of the shell's aspect ratio for both area-constrained and volume-constrained cases. Counterion condensation is seen to favor the formation of spheroidal structures over a sphere of equal area for high values of shell volume fractions.

Regularization of the Coulomb scattering problem

International Nuclear Information System (INIS)

Baryshevskii, V.G.; Feranchuk, I.D.; Kats, P.B.

2004-01-01

The exact solution of the Schroedinger equation for the Coulomb potential is used within the scope of both stationary and time-dependent scattering theories in order to find the parameters which determine the regularization of the Rutherford cross section when the scattering angle tends to zero but the distance r from the center remains finite. The angular distribution of the particles scattered in the Coulomb field is studied on rather a large but finite distance r from the center. It is shown that the standard asymptotic representation of the wave functions is inapplicable in the case when small scattering angles are considered. The unitary property of the scattering matrix is analyzed and the 'optical' theorem for this case is discussed. The total and transport cross sections for scattering the particle by the Coulomb center proved to be finite values and are calculated in the analytical form. It is shown that the effects under consideration can be important for the observed characteristics of the transport processes in semiconductors which are determined by the electron and hole scattering by the field of charged impurity centers

Characterization of ion Coulomb crystals in a linear Paul trap

International Nuclear Information System (INIS)

Okada, K.; Takayanagi, T.; Wada, M.; Ohtani, S.; Schuessler, H. A.

2010-01-01

We describe a simple and fast method for simulating observed images of ion Coulomb crystals. In doing so, cold elastic collisions between Coulomb crystals and virtual very light atoms are implemented in a molecular dynamics (MD) simulation code. Such an approach reproduces the observed images of Coulomb crystals by obtaining density plots of the statistics of existence of each ion. The simple method has the advantage of short computing time in comparison with previous calculation methods. As a demonstration of the simulation, the formation of a planar Coulomb crystal with a small number of ions has been investigated in detail in a linear ion trap both experimentally and by simulation. However, also large Coulomb crystals including up to 1400 ions have been photographed and simulated to extract the secular temperature and the number of ions. For medium-sized crystals, a comparison between experiments and calculations has been performed. Moreover, an MD simulation of the sympathetic cooling of small molecular ions was performed in order to test the possibility of extracting the temperature and the number of refrigerated molecular ions from crystal images of laser-cooled ions. Such information is basic to studying ultracold ion-molecule reactions using ion Coulomb crystals including sympathetically cooled molecular ions.

Proton optical potential and scattering matrix for tin nuclei at sub-coulomb energies

International Nuclear Information System (INIS)

Guzhovskij, B.Ya.; Dzyuba, B.M.

1981-01-01

A unified set of parameters of the proton optical potential (OP) for the n nuclei is searched for in the below-Coulomb-barrier energy range. The set must describe well the experimental data on the pn-reaction total cross sections and on the angular distributions of elastically scattered protons at E [ru

Coulomb effects in deuteron stripping reactions as a three-body problem

International Nuclear Information System (INIS)

Osman, A.

1981-08-01

Deuteron stripping nuclear reactions are reconsidered as a three-body problem. The Coulomb effects between the proton and the target nucleus are investigated. The mathematical formalism introduces three-body integral equations which can be exactly calculated for such simple models. These coupled integral equations suitably include the Coulomb effects due to replusive or attractive Coulomb potential. Numerical calculations of the differential cross-sections of the reactions 28 Si(d,p) 29 Si and 40 Ca(d,p) 41 Ca are carried out showing the importance of the Coulomb effects. The angular distributions of these reactions are theoretically calculated and fitted to the experimental data. From this fitting, reasonable spectroscopic factors are obtained. Inclusion of Coulomb force in the three-body model are found to improve the results by a percentage of about 6.826%. (author)

Effects of ion and electron screening on thermonuclear reaction rates

International Nuclear Information System (INIS)

Brady, L.R. Jr.

1977-01-01

The effects of screening by ions and electrons on thermonuclear reaction rates in stellar plasmas are considered. The enhancement of the reaction rate ranges from negligible to extremely large (on the order of 10 26 or greater). In order to calculate these effects, the potential about a given reacting nucleus is determined. First, Boltzmann-Vlasov and Poisson-Boltzmann equations are solved to yield a Yukawa potential. A suitable approximation to this potential is integrated in the action integral to give the barrier penetration. The screened reaction rate is then found by the saddle-point method. In developing a general formalism to calculate the screened reaction rate and the screening factor, effects due to the finite size of the nucleus are considered and found to be negligible. An expression for the screening factor for resonant reaction rates is also derived. A different and relatively simple approach, based on work of Stewart and Pyatt (1966), is used to find the barrier penetration from the action integral in two approximations: a modified Coulomb potential and a constant-shift potential. Screening factors are calculated for carbon burning at T 6 = 100 and T 6 = 400 for a wide range of densities and also for several examples in late stellar evolution. These screening factors are, for the most part, greater than those given by most others by a few percent at low density to 4 or more orders of magnitude at T 6 = 100 and rho = 10 10 g/cm 3 . Near the edge of the crystalline lattice region, however, they are significantly lower than those of some others. The increase in reaction rates for carbon burning indicates that carbon ignition may occur at lower densities than previously thought and may affect the density at which a supernova shock may occur

3D Oscillator and Coulomb Systems reduced from Kahler spaces

OpenAIRE

Nersessian, Armen; Yeranyan, Armen

2003-01-01

We define the oscillator and Coulomb systems on four-dimensional spaces with U(2)-invariant Kahler metric and perform their Hamiltonian reduction to the three-dimensional oscillator and Coulomb systems specified by the presence of Dirac monopoles. We find the Kahler spaces with conic singularity, where the oscillator and Coulomb systems on three-dimensional sphere and two-sheet hyperboloid are originated. Then we construct the superintegrable oscillator system on three-dimensional sphere and ...

Correlated Coulomb Drag in Capacitively Coupled Quantum-Dot Structures.

Science.gov (United States)

Kaasbjerg, Kristen; Jauho, Antti-Pekka

2016-05-13

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.

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

Monotonicity of energy eigenvalues for Coulomb systems

International Nuclear Information System (INIS)

Englisch, R.

1983-01-01

Generalising results by earlier workers for a large class of Hamiltonians (among others, Hamiltonians of Coulomb systems) which can be written in the form H(α) = H 0 + αH' the present works shows that their eigenvalues decrease with increasing α. This result is applied to Coulomb systems in which the distances between the infinitely heavy particles are varying and also is used to obtain a completion and simplification of proof for the stability of the biexciton. (author)

Critical opalescence in the pure Coulomb system

International Nuclear Information System (INIS)

Bobrov, V.B.; Trigger, S.A.

2011-01-01

Highlights: → The review of the critical opalescence problem is presented. → Light scattering in a two-component electron-nuclear system is studied. → The exact relations between the structure factors and compressibility are found. → The obtained relations are valid for strong interaction for the Coulomb systems. → The experimental verification of these relations is possible for various elements. - Abstract: Based on the dielectric formalism and quantum field theory methods, the phenomenon of critical opalescence is explained for light scattering in pure matter as a two-component electron-nuclear system with Coulomb interaction. A similar phenomenon is shown to occur in the case of neutron scattering in pure substances as well. The obtained results are valid for quantum case and arbitrary strong Coulomb interaction. Thus, the relations between structure factors derived for the electron-nuclear system are the exact result of the quantum statistical mechanics.

Understanding Coulomb Scattering Mechanism in Monolayer MoS2 Channel in the Presence of h-BN Buffer Layer.

Science.gov (United States)

Joo, Min-Kyu; Moon, Byoung Hee; Ji, Hyunjin; Han, Gang Hee; Kim, Hyun; Lee, Gwanmu; Lim, Seong Chu; Suh, Dongseok; Lee, Young Hee

2017-02-08

As the thickness becomes thinner, the importance of Coulomb scattering in two-dimensional layered materials increases because of the close proximity between channel and interfacial layer and the reduced screening effects. The Coulomb scattering in the channel is usually obscured mainly by the Schottky barrier at the contact in the noise measurements. Here, we report low-temperature (T) noise measurements to understand the Coulomb scattering mechanism in the MoS 2 channel in the presence of h-BN buffer layer on the silicon dioxide (SiO 2 ) insulating layer. One essential measure in the noise analysis is the Coulomb scattering parameter (α SC ) which is different for channel materials and electron excess doping concentrations. This was extracted exclusively from a 4-probe method by eliminating the Schottky contact effect. We found that the presence of h-BN on SiO 2 provides the suppression of α SC twice, the reduction of interfacial traps density by 100 times, and the lowered Schottky barrier noise by 50 times compared to those on SiO 2 at T = 25 K. These improvements enable us to successfully identify the main noise source in the channel, which is the trapping-detrapping process at gate dielectrics rather than the charged impurities localized at the channel, as confirmed by fitting the noise features to the carrier number and correlated mobility fluctuation model. Further, the reduction in contact noise at low temperature in our system is attributed to inhomogeneous distributed Schottky barrier height distribution in the metal-MoS 2 contact region.

4-center STO interelectron repulsion integrals with Coulomb Sturmians

DEFF Research Database (Denmark)

Avery, James Emil; Avery, John Scales

2018-01-01

Abstract We present a method for evaluating 4-center electron repulsion integrals (ERI) for Slater-type orbitals by way of expansions in terms of Coulomb Sturmians. The ERIs can then be evaluated using our previously published methods for rapid evaluation of Coulomb Sturmians through hyperspherical...

Asymptotic three-particle approach to the Coulomb breakup process {sup 6}Li + {sup 208}Pb → {sup 208}Pb + α + d

Energy Technology Data Exchange (ETDEWEB)

Igamov, S. B., E-mail: igamov@inp.uz [Uzbek Academy of Sciences, Institute of Nuclear Physics (Uzbekistan)

2017-03-15

On the basis of the distorted-wave method, experimental data on the triple-differential cross section for the Coulomb breakup reaction {sup 208}Pb({sup 6}Li, αd){sup 208}Pb are analyzed by employing a correct expression for the final-state {sup 208}Pb–α–d three-particle Coulomb wave function. It is shown that the effect of final-state three-particle Coulomb dynamics can be used to assess the kinematical condition of clean Coulomb breakup processes. New values of the astrophysical S factor for the direct-radiative-capture reaction d(α, γ){sup 6}Li at ultralow energies in the range of 70 ≤ E{sub dα} ≤ 600 keV were extracted from experimental data. The value of S(0) = 1.60 ± 0.17 MeV nb was obtained.

Controllability of the Coulomb charging energy in close-packed nanoparticle arrays.

Science.gov (United States)

Duan, Chao; Wang, Ying; Sun, Jinling; Guan, Changrong; Grunder, Sergio; Mayor, Marcel; Peng, Lianmao; Liao, Jianhui

2013-11-07

We studied the electronic transport properties of metal nanoparticle arrays, particularly focused on the Coulomb charging energy. By comparison, we confirmed that it is more reasonable to estimate the Coulomb charging energy using the activation energy from the temperature-dependent zero-voltage conductance. Based on this, we systematically and comprehensively investigated the parameters that could be used to tune the Coulomb charging energy in nanoparticle arrays. We found that four parameters, including the particle core size, the inter-particle distance, the nearest neighboring number, and the dielectric constant of ligand molecules, could significantly tune the Coulomb charging energy.

Metal nanoparticle film-based room temperature Coulomb transistor.

Science.gov (United States)

Willing, Svenja; Lehmann, Hauke; Volkmann, Mirjam; Klinke, Christian

2017-07-01

Single-electron transistors would represent an approach to developing less power-consuming microelectronic devices if room temperature operation and industry-compatible fabrication were possible. We present a concept based on stripes of small, self-assembled, colloidal, metal nanoparticles on a back-gate device architecture, which leads to well-defined and well-controllable transistor characteristics. This Coulomb transistor has three main advantages. By using the scalable Langmuir-Blodgett method, we combine high-quality chemically synthesized metal nanoparticles with standard lithography techniques. The resulting transistors show on/off ratios above 90%, reliable and sinusoidal Coulomb oscillations, and room temperature operation. Furthermore, this concept allows for versatile tuning of the device properties such as Coulomb energy gap and threshold voltage, as well as period, position, and strength of the oscillations.

Known-to-Unknown Approach to Teach about Coulomb's Law

Science.gov (United States)

Thamburaj, P. K.

2007-01-01

Analogies from life experiences help students understand various relationships presented in an introductory chemistry course. Coulomb's law is a complex relationship encountered in introductory general chemistry. A proper understanding of the relationships between the quantities involved in Coulomb's law is necessary in order for students to…

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...

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 eval......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...

Physics of the Non-Abelian Coulomb Phase

DEFF Research Database (Denmark)

Ryttov, Thomas A.; Shrock, Robert

2018-01-01

are applied to obtain further estimates of $\\gamma_{\\bar\\psi\\psi,IR}$ and $\\beta'_{IR}$ for several SU($N_c$) groups and representations $R$, and comparisons are made with lattice measurements. We apply our results to obtain new estimates of the extent of the respective non-Abelian Coulomb phases in several....... It is shown that an expansion of $\\gamma_{\\bar\\psi\\psi,IR}$ to $O(\\Delta_f^4)$ is quite accurate throughout the entire non-Abelian Coulomb phase of this supersymmetric theory....

Higher-order dynamical effects in Coulomb dissociation

International Nuclear Information System (INIS)

Esbensen, H.

1994-06-01

We study the effect of higher-order processes in Coulomb dissociation of 11 Li by numerically solving the three-dimensional time-dependent Schroedinger equation for the relative motion of a di-neutron and the 9 Li core. Comparisons are made to first-order perturbation theory and to measurements. The calculated Coulomb reacceleration effects improve the agreement with experiment, but some discrepancy remains. The effects are much smaller in the dissociation of 11 Be, and they decrease with increasing beam energy. (orig.)

Coulomb corrections to scattering length and effective radius

International Nuclear Information System (INIS)

Mur, V.D.; Kudryavtsev, A.E.; Popov, V.S.

1983-01-01

The problem considered is extraction of the ''purely nuclear'' scattering length asub(s) (corresponding to the strong potential Vsub(s) at the Coulomb interaction switched off) from the Coulomb-nuclear scattering length asub(cs), which is an object of experimental measurement. The difference between asub(s) and asub(cs) is especially large if the potential Vsub(s) has a level (real or virtual) with an energy close to zero. For this case formulae are obtained relating the scattering lengths asub(s) and asub(cs), as well as the effective radii rsub(s) and rsub(cs). The results are extended to states with arbitrary angular momenta l. It is shown that the Coulomb correction is especially large for the coefficient with ksup(2l) in the expansion of the effective radius; in this case the correction contains a large logarithm ln(asub(B)/rsub(0)). The Coulomb renormalization of other terms in the effective radius espansion is of order (rsub(0)/asub(B)), where r 0 is the nuclear force radius, asub(B) is the Bohr radius. The obtained formulae are tried on a number of model potentials Vsub(s), used in nuclear physics

Recharging of a screened ion on the molecular ion

International Nuclear Information System (INIS)

Karbovanets, M.I.; Lazur, V.Yu.; Yudin, G.L.; Gosudarstvennyj Komitet po Ispol'zovaniyu Atomnoj Ehnergii SSSR, Obninsk. Fiziko-Ehnergeticheskij Inst.)

1987-01-01

Charge exchange of a screened ion on a molecular ion is studied in the Oppenheimer-Brinkman-Cramers approximation. To calculate ion exchange probabilities and cross sections summed over the final degenerated electron states method of Green functions analogous to that applied earlier in the direct Coulomb excitation theory and atomic ionization is developed

Fast Electron Repulsion Integrals for Molecular Coulomb Sturmians

DEFF Research Database (Denmark)

Avery, James Emil

2013-01-01

A new method is presented for calculating interelectron repulsion integrals for molecular Coulomb Sturmian basis sets. This makes use of an expansion of densities in terms of 2k-Sturmians, and the interelectron repulsion integrals are then calculated by a method based on the theory of hyperspheri......A new method is presented for calculating interelectron repulsion integrals for molecular Coulomb Sturmian basis sets. This makes use of an expansion of densities in terms of 2k-Sturmians, and the interelectron repulsion integrals are then calculated by a method based on the theory...... of 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...

Metal nanoparticle film–based room temperature Coulomb transistor

Science.gov (United States)

Willing, Svenja; Lehmann, Hauke; Volkmann, Mirjam; Klinke, Christian

2017-01-01

Single-electron transistors would represent an approach to developing less power–consuming microelectronic devices if room temperature operation and industry-compatible fabrication were possible. We present a concept based on stripes of small, self-assembled, colloidal, metal nanoparticles on a back-gate device architecture, which leads to well-defined and well-controllable transistor characteristics. This Coulomb transistor has three main advantages. By using the scalable Langmuir-Blodgett method, we combine high-quality chemically synthesized metal nanoparticles with standard lithography techniques. The resulting transistors show on/off ratios above 90%, reliable and sinusoidal Coulomb oscillations, and room temperature operation. Furthermore, this concept allows for versatile tuning of the device properties such as Coulomb energy gap and threshold voltage, as well as period, position, and strength of the oscillations. PMID:28740864

A proposal for Coulomb assisted laser cooling of piezoelectric semiconductors

Energy Technology Data Exchange (ETDEWEB)

Nia, Iman Hassani; Mohseni, Hooman, E-mail: hmohseni@ece.northwestern.edu [Bio-Inspired Sensors and Optoelectronics Laboratory (BISOL), Department of Electrical Engineering, Northwestern University, Evanston, Illinois 60208 (United States)

2014-07-28

Anti-Stokes laser cooling of semiconductors as a compact and vibration-free method is very attractive. While it has achieved significant milestones, increasing its efficiency is highly desirable. The main limitation is the lack of the pristine material quality with high luminescence efficiency. Here, we theoretically demonstrate that the Coulomb interaction among electrons and holes in piezoelectric heterostructures could lead to coherent damping of acoustic phonons; rendering a significantly higher efficiency that leads to the possibility of cooling a broad range of semiconductors.

Critical opalescence in the pure Coulomb system

Science.gov (United States)

Bobrov, V. B.; Trigger, S. A.

2011-04-01

Based on the dielectric formalism and quantum field theory methods, the phenomenon of critical opalescence is explained for light scattering in pure matter as a two-component electron-nuclear system with Coulomb interaction. A similar phenomenon is shown to occur in the case of neutron scattering in pure substances as well. The obtained results are valid for quantum case and arbitrary strong Coulomb interaction. Thus, the relations between structure factors derived for the electron-nuclear system are the exact result of the quantum statistical mechanics.

Exact solution of the N-dimensional generalized Dirac-Coulomb equation

International Nuclear Information System (INIS)

Tutik, R.S.

1992-01-01

An exact solution to the bound state problem for the N-dimensional generalized Dirac-Coulomb equation, whose potential contains both the Lorentz-vector and Lorentz-scalar terms of the Coulomb form, is obtained. 24 refs. (author)

Coulomb dissociation of 8B at 254 MeV/u

International Nuclear Information System (INIS)

Surowka, G.; Iwasa, N.; Boue, F.

1999-01-01

As an alternative method to determine the cross section of 7 Be (p, γ) 8 B, the Coulomb dissociation reaction 8 B → 7 Be + p at E inc = 254 MeV/u was measured. Our preliminary results show the dominant role of the dipole excitation in the Coulomb break-up process. The extracted astrophysical S 17 factor is consistent with the lower-value results both of the direct-capture studies, and the RIKEN Coulomb-dissociation experiment at ∼ 50 MeV/u. (author)

Coulomb Problem for Z > Zcr in Doped Graphene

Science.gov (United States)

Kuleshov, V. M.; Mur, V. D.; Fedotov, A. M.; Lozovik, Yu. E.

2017-12-01

The dynamics of charge carriers in doped graphene, i.e., graphene with a gap in the energy spectrum depending on the substrate, in the presence of a Coulomb impurity with charge Z is considered within the effective two-dimensional Dirac equation. The wave functions of carriers with conserved angular momentum J = M + 1/2 are determined for a Coulomb potential modified at small distances. This case, just as any two-dimensional physical system, admits both integer and half-integer quantization of the orbital angular momentum in plane, M = 0, ±1, ±2, …. For J = 0, ±1/2, ±1, critical values of the effective charge Z cr( J, n) are calculated for which a level with angular momentum J and radial quantum numbers n = 0 and n = 1 reaches the upper boundary of the valence band. For Z function of charge Z for the lowest values of orbital angular momentum M, the level with J = 0 being the first to descend to the band edge. For Z > Z cr ( J, n = 0), scattering phases are calculated as a function of hole energy for several values of supercriticality, as well as the positions ɛ0 and widths γ of quasistationary states as a function of supercriticality. The values of ɛ0* and width γ* are pointed out for which quasidiscrete levels may show up as Breit-Wigner resonances in the scattering of holes by a supercritical impurity. Since the phases are real, the partial scattering matrix is unitary, so that the radial Dirac equation is consistent even for Z > Z cr. In this single-particle approximation, there is no spontaneous creation of electron-hole pairs, and the impurity charge cannot be screened by this mechanism.

The use of polybenzimidazole membranes in vanadium redox flow batteries leading to increased coulombic efficiency and cycling performance

International Nuclear Information System (INIS)

Zhou, X.L.; Zhao, T.S.; An, L.; Wei, L.; Zhang, C.

2015-01-01

An issue with conventional vanadium redox flow batteries (VRFB) with Nafion membranes is the crossover of vanadium ions, resulting in low coulombic efficiency and rapid decay in capacity. In this work, a VRFB with a polybenzimidazole (PBI) membrane is tested and compared with the Nafion system. Results show that the PBI-based VRFB exhibits a substantially higher coulombic efficiency of up to 99% at current densities ranging from 20 mA cm −2 to 80 mA cm −2 . More importantly, it is demonstrated that the PBI-based VRFB has a capacity decay rate of as low as 0.3% per cycle, which is four times lower than that of the Nafion system (1.3% per cycle). The improved coulombic efficiency and cycling performance are attributed to the low crossover of vanadium ions through the PBI membrane

The generalized parabolic Coulomb wavefunction in spherical coordinates

Energy Technology Data Exchange (ETDEWEB)

Gasaneo, G. [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Departamento de Fisica, Universidad del Sur, Buenos Aires (Argentina); Colavecchia, F.D.; Garibotti, C.R. [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Centro Atomico Bariloche, Rio Negro (Argentina); Otranto, S. [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Departamento de Fisica, Universidad del Sur, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, Centro Atomico Bariloche, Rio Negro (Argentina)

2001-10-19

In this work we present a detailed study of the recently introduced {delta}{sub m,n} basis for three Coulomb particles. We show that the scattering and generalized Coulomb problems as well as a {phi}{sub 2} approach can be viewed as particular cases of this basis. We derive a partial wave expansion for {delta}{sub m,n} functions and analyse the reduction to some of the precedent cases. (author)

Coulomb excitation of radioactive 20, 21Na

Science.gov (United States)

Schumaker, M. A.; Cline, D.; Hackman, G.; Pearson, C.; Svensson, C. E.; Wu, C. Y.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Buchmann, L.; Churchman, R.; Cifarelli, F.; Cooper, R. J.; Cross, D. S.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Drake, T. E.; Finlay, P.; Gallant, A. T.; Garrett, P. E.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Lisetskiy, A. F.; Leach, K. G.; Lee, G.; Maharaj, R.; Martin, J.-P.; Moisan, F.; Morton, A. C.; Mythili, S.; Nelson, L.; Newman, O.; Nolan, P. J.; Orce, J. N.; Padilla-Rodal, E.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Roy, R.; Ruiz, C.; Sarazin, F.; Scraggs, D. P.; Waddington, J. C.; Wan, J. M.; Whitbeck, A.; Williams, S. J.; Wong, J.

2009-12-01

The low-energy structures of the radioactive nuclei 20, 21Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ˜ 5×106 ions/s were accelerated to 1.7MeV/A and Coulomb excited in a 0.5mg/cm^2 natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for γ -ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For 21Na , Coulomb excitation from the 3/2+ ground state to the first excited 5/2+ state was observed, while for 20Na , Coulomb excitation was observed from the 2+ ground state to the first excited 3+ and 4+ states. For both beams, B ( λ L) values were determined using the 2+ rightarrow 0+ de-excitation in 48Ti as a reference. The resulting B( E2) ↓ value for 21Na is 137±9 e^2fm^4, while the resulting B( λ L) ↓ values for 20Na are 55±6 e^2fm^4 for the 3+ rightarrow 2+ , 35.7±5.7 e^2 fm^4 for the 4+ rightarrow 2+ , and 0.154±0.030 μ_ N^2 for the 4+ rightarrow 3+ transitions. This analysis significantly improves the measurement of the 21Na B( E2) value, and provides the first experimental determination of B( λ L) values for the proton dripline nucleus 20Na .-1

Coulomb-gas scaling, superfluid films, and the XY model

International Nuclear Information System (INIS)

Minnhagen, P.; Nylen, M.

1985-01-01

Coulomb-gas-scaling ideas are invoked as a link between the superfluid density of two-dimensional 4 He films and the XY model; the Coulomb-gas-scaling function epsilon(X) is extracted from experiments and is compared with Monte Carlo simulations of the XY model. The agreement is found to be excellent

On the Emergence of the Coulomb Forces in Quantum Electrodynamics

Directory of Open Access Journals (Sweden)

Jan Naudts

2017-01-01

Full Text Available A simple transformation of field variables eliminates Coulomb forces from the theory of quantum electrodynamics. This suggests that Coulomb forces may be an emergent phenomenon rather than being fundamental. This possibility is investigated in the context of reducible quantum electrodynamics. It is shown that states exist which bind free photon and free electron fields. The binding energy peaks in the long-wavelength limit. This makes it plausible that Coulomb forces result from the interaction of the electron/positron field with long-wavelength transversely polarized photons.

Critical behavior in graphene with Coulomb interactions.

Science.gov (United States)

Wang, Jianhui; Fertig, H A; Murthy, Ganpathy

2010-05-07

We demonstrate that, in the presence of Coulomb interactions, electrons in graphene behave like a critical system, supporting power law correlations with interaction-dependent exponents. An asymptotic analysis shows that the origin of this behavior lies in particle-hole scattering, for which the Coulomb interaction induces anomalously close approaches. With increasing interaction strength the relevant power law changes from real to complex, leading to an unusual instability characterized by a complex-valued susceptibility in the thermodynamic limit. Measurable quantities, as well as the connection to classical two-dimensional systems, are discussed.

Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

International Nuclear Information System (INIS)

Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

2015-01-01

Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials

Coulomb fission and transfer fission at heavy ion collisions

International Nuclear Information System (INIS)

Himmele, G.

1981-01-01

In the present thesis the first direct evidence of nuclear fission after inelastic scattering of heavy ions (sup(183,184)W, 152 Sm → 238 U; 184 W → 232 Th; 184 W, 232 Th → 248 Cm) is reported. Experiments which were performed at the UNILAC of the Gesellschaft fuer Schwerionenforschung in Darmstadt show the observed heavy ion induced fission possesses significant properties of the Coulomb fission. The observed dependence of the fission probability for inelastic scattering on the projectile charge proves that the nuclear fission is mediated by the electromagnetic interaction between heavy ions. This result suggests moreover a multiple Coulomb-excitation preceding the fission. Model calculations give a first indication, that the Coulomb fission proceeds mainly from the higher β phonons. In the irradiation with 184 W the fission probability of 232 Th is for all incident energies about 40% smaller that at 238 U. The target dependence of the Coulomb fission however doesn't allow, to give quantitative statements about the position and B(E2)-values of higher lying β phonons. (orig./HSI) [de

Break up of light ions in the nuclear and Coulomb field of nuclei

International Nuclear Information System (INIS)

Srivastava, D.K.

1985-12-01

The break up of light ion projectiles in the nuclear and Coulomb field of nuclei is considered. Current theoretical concepts for describing break up processes and their theoretical features are discussed. An alternative method, based on a prior-interaction DWBA, is introduced for the calculation of the direct elastic break up cross sections. This method reveals the role of the internal momentum distribution of the break up fragments and includes corresponding 'finite range' effects. The Coulomb break up of 6 Li is studied on the basis of a quasi-sequential break up approach (following Rybicki and Austern) and results are obtained for very low relative energies of the emerging α-particles and deuteron fragments. The astrophysical interest in these cross sections is noted. A view on further extensions of the break up theory is given. (orig.) [de

About the role of 2D screening in high temperature superconductivity

International Nuclear Information System (INIS)

Vazquez-Ponce, Y.; Oliva Aguero, D.; Cabo Montes de Oca, D.

2005-09-01

The 2D screening is investigated in a simple single band square tight-binding model which qualitatively resembles the known electronic structure in high temperature superconductors. The Coulomb kernel for the two particle Bethe-Salpeter equation in the single loop (RPA) approximation for the polarization can be evaluated in a strong tight binding limit. The results indicate an intense screening of the Coulomb repulsion between the particles, which becomes stronger and anisotropic when the Fermi level approaches half filling (or equivalently, when the Fermi surface turns to be near the Van Hove singularities) and rapidly decreases away from it. The effect is also more pronounced for quasi-momenta regions near the corners of the Brillouin cell, which corresponds to dual spatial distances of the order of a few unit cells. Therefore, a possible mechanism is identified which could explain the existence of extremely small Cooper pairs in these materials, as bounded anisotropic composite particles joined by residual superexchange or phonon interactions. (author)

The Coulomb gas representation of critical RSOS models on the sphere and the torus

International Nuclear Information System (INIS)

Foda, O.; Nienhuis, B.

1989-01-01

We derive the Coulomb gas formulation of the c<1 discrete unitary series, on the sphere and the torus, starting from the corresponding regime-III RSOS models on a square lattice with appropriate topology. We clarify the origin of the background charge, the screening charges, and the choice of operator representations in a correlation function. In the scaling limit, we obtain a bosonic action coupled to the background curvature in addition to topological terms that vanish on the Riemann sphere. Its Virasoro algebra has the central charge expected on the basis of comparing conformal dimensions. As an application, we derive general expressions for the correlation functions on the torus. (orig.)

The Coulomb gas representation of critical RSOS models on the sphere and the torus

Energy Technology Data Exchange (ETDEWEB)

Foda, O. (Rijksuniversiteit Utrecht (Netherlands). Inst. voor Theoretische Fysica); Nienhuis, B. (Rijksuniversiteit Leiden (Netherlands). Inst. Lorentz voor Theoretische Natuurkunde)

1989-10-02

We derive the Coulomb gas formulation of the c<1 discrete unitary series, on the sphere and the torus, starting from the corresponding regime-III RSOS models on a square lattice with appropriate topology. We clarify the origin of the background charge, the screening charges, and the choice of operator representations in a correlation function. In the scaling limit, we obtain a bosonic action coupled to the background curvature in addition to topological terms that vanish on the Riemann sphere. Its Virasoro algebra has the central charge expected on the basis of comparing conformal dimensions. As an application, we derive general expressions for the correlation functions on the torus. (orig.).

Dynamic plasma screening effects on atomic collisions in dense plasmas

International Nuclear Information System (INIS)

Young-Dae Jung

1999-01-01

Dynamic plasma screening effects are investigated on electron-ion collisional excitation and Coulomb Bremsstrahlung processes in dense plasmas. The electron-ion interaction potential is considered by introduction of the plasma dielectric function. The straight-ling trajectory method is applied to the path of the projectile electron. The transition probability including the dynamic plasma screening effect is found to be always greater than that including the static plasma screening effects. It is found that the differential Bremsstrahlung radiation cross section including the dynamic plasma screening effect is also greater than that including the static plasma screening effect. When the projectile velocity is smaller than the electron thermal velocity, the dynamic polarization screening effect becomes the static plasma screening effect. However, when the projectile velocity is greater than the electron thermal velocity, the interaction potential is almost unshielded

Rigorous study of the mean field approximation of Debye and Hueckel for Coulomb systems

International Nuclear Information System (INIS)

Kennedy, T.G.

1984-01-01

The statistical mechanics of a classical charge symmetric Coulomb system is studied in three dimensions in the limit that the plasma parameter (the inverse temperature divided by the Debye length) goes to zero. To make the system stable, a short range interaction, e.g., hard cores is included. This short range interaction is allowed to go to zero as the plasma parameter goes to zero. Debye and Hueckel used a mean field approximation to give a nonrigorous study of Coulomb systems in his limit. For a system with no external charge distribution, it is shown that the pressure, density, and correlation functions are asymptotic to their Debye-Hueckel approximations. These approximations consist of the ideal gas term plus a term of one lower order in the plasma parameter. The main tools are the Sine-Gordon transformation, the Mayer expansion, and some new correlation inequalities. The sine-Gordon transformation and the Mayer expansion are used to express the observables as functional integrals with respect to a Gaussian measure. The correlation inequalities help control these functional integrals

Formation of Coulomb crystal in presence of attractive overlapping Debye sphere potential

International Nuclear Information System (INIS)

Baruah, Swati; Das, Nilakshi

2011-01-01

The role of attractive overlapping Debye sphere (ODS) potential on dust crystal formation has been investigated by using molecular dynamics code. A comparative study on plasma crystal formation has been made between Yukawa and coupled Yukawa-ODS potential by calculating pair-correlation function, for different values of Coulomb coupling parameter Γ and screening parameter κ. From our study, it is seen that the attractive ODS potential becomes dominant beyond a critical radius than that of the Yukawa potential. This leads to the fact that the effect due to combined Yukawa-ODS potential depends more sensitively on κ. From the comparison of the results for Yukawa and ODS potential with experimental results, it is observed that a close agreement is obtained for attractive ODS potential.

Coulomb explosion of large penetrating molecular clusters

International Nuclear Information System (INIS)

Wegner, H.E.; Thieberger, P.

1981-01-01

The main purpose of these Coulomb explosion measurements is to determine what kind of structure these and other complex molecules may have and also to determine what other special phenomena may come into play as these complex molecules pass through matter. Although the first preliminary measurements involving the Coulomb explosion of these molecules was reported at this workshop last year, the results are briefly summarized before going on to the more recent measurements obtained with a completely new kind of detector system. This new image intensifier detector system, coupled with a microcomputer, has proven to be a valuable tool in the study of the Coulomb explosion of complex molecules that penetrate matter. In the future, with some additional improvements in the system, and much better statistics for most of the molecules studied to date, it is expected that much new information will be gained about the structure of many kinds of complex molecular ions including the special effects that may be encountered when these fast molecular ions penetrate matter

Narrow resonances and short-range interactions

International Nuclear Information System (INIS)

Gelman, Boris A.

2009-01-01

Narrow resonances in systems with short-range interactions are discussed in an effective field theory (EFT) framework. An effective Lagrangian is formulated in the form of a combined expansion in powers of a momentum Q 0 | 0 --a resonance peak energy. At leading order in the combined expansion, a two-body scattering amplitude is the sum of a smooth background term of order Q 0 and a Breit-Wigner term of order Q 2 (δε) -1 which becomes dominant for δε 3 . Such an EFT is applicable to systems in which short-distance dynamics generates a low-lying quasistationary state. The EFT is generalized to describe a narrow low-lying resonance in a system of charged particles. It is shown that in the case of Coulomb repulsion, a two-body scattering amplitude at leading order in a combined expansion is the sum of a Coulomb-modified background term and a Breit-Wigner amplitude with parameters renormalized by Coulomb interactions.

Testing the Predictive Power of Coulomb Stress on Aftershock Sequences

Science.gov (United States)

Woessner, J.; Lombardi, A.; Werner, M. J.; Marzocchi, W.

2009-12-01

Empirical and statistical models of clustered seismicity are usually strongly stochastic and perceived to be uninformative in their forecasts, since only marginal distributions are used, such as the Omori-Utsu and Gutenberg-Richter laws. In contrast, so-called physics-based aftershock models, based on seismic rate changes calculated from Coulomb stress changes and rate-and-state friction, make more specific predictions: anisotropic stress shadows and multiplicative rate changes. We test the predictive power of models based on Coulomb stress changes against statistical models, including the popular Short Term Earthquake Probabilities and Epidemic-Type Aftershock Sequences models: We score and compare retrospective forecasts on the aftershock sequences of the 1992 Landers, USA, the 1997 Colfiorito, Italy, and the 2008 Selfoss, Iceland, earthquakes. To quantify predictability, we use likelihood-based metrics that test the consistency of the forecasts with the data, including modified and existing tests used in prospective forecast experiments within the Collaboratory for the Study of Earthquake Predictability (CSEP). Our results indicate that a statistical model performs best. Moreover, two Coulomb model classes seem unable to compete: Models based on deterministic Coulomb stress changes calculated from a given fault-slip model, and those based on fixed receiver faults. One model of Coulomb stress changes does perform well and sometimes outperforms the statistical models, but its predictive information is diluted, because of uncertainties included in the fault-slip model. Our results suggest that models based on Coulomb stress changes need to incorporate stochastic features that represent model and data uncertainty.

Density of states of two-dimensional systems with long-range logarithmic interactions

Energy Technology Data Exchange (ETDEWEB)

Somoza, Andrés M.; Ortuño, Miguel; Baturina, Tatyana I.; Vinokur, Valerii M.

2015-08-03

We investigate a single-particle density of states (DOS) in strongly disordered two- dimensional high dielectric permittivity systems with logarithmic Coulomb interaction between particles. We derive self-consistent DOS at zero temperature and show that it is appreciably suppressed as compared to the DOS expected from the Efros-Shklovskii approach.We carry out zero- and finite-temperature Monte Carlo numerical studies of the DOS and find the perfect agreement between the numerical and analytical results at zero temperature, observing, in particular, a hardening of the Coulomb gap with the increasing electrostatic screening length. At finite temperatures, we reveal a striking scaling of the DOS as a function of energy normalized to the temperature of the system.

Room-temperature Coulomb staircase in semiconducting InP nanowires modulated with light illumination.

Science.gov (United States)

Yamada, Toshishige; Yamada, Hidenori; Lohn, Andrew J; Kobayashi, Nobuhiko P

2011-02-04

Detailed electron transport analysis is performed for an ensemble of conical indium phosphide nanowires bridging two hydrogenated n(+)-silicon electrodes. The current-voltage (I-V) characteristics exhibit a Coulomb staircase in the dark with a period of ∼ 1 V at room temperature. The staircase is found to disappear under light illumination. This observation can be explained by assuming the presence of a tiny Coulomb island, and its existence is possible due to the large surface depletion region created within contributing nanowires. Electrons tunnel in and out of the Coulomb island, resulting in the Coulomb staircase I-V. Applying light illumination raises the electron quasi-Fermi level and the tunneling barriers are buried, causing the Coulomb staircase to disappear.

The singularity structure of scale-invariant rank-2 Coulomb branches

Science.gov (United States)

Argyres, Philip C.; Long, Cody; Martone, Mario

2018-05-01

We compute the spectrum of scaling dimensions of Coulomb branch operators in 4d rank-2 N=2 superconformal field theories. Only a finite rational set of scaling dimensions is allowed. It is determined by using information about the global topology of the locus of metric singularities on the Coulomb branch, the special Kähler geometry near those singularities, and electric-magnetic duality monodromies along orbits of the U(1) R symmetry. A set of novel topological and geometric results are developed which promise to be useful for the study and classification of Coulomb branch geometries at all ranks.

Study of the elastic scattering of {sup 6}He on {sup 208}Pb at energies around the Coulomb barrier

Energy Technology Data Exchange (ETDEWEB)

Sanchez-Benitez, A.M. [Departamento de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain); Centre de Recherches du Cyclotron, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Escrig, D. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Alvarez, M.A.G.; Andres, M.V. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, E-41080 Sevilla (Spain); Angulo, C. [Centre de Recherches du Cyclotron, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Borge, M.J.G. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Cabrera, J. [Centre de Recherches du Cyclotron, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Cherubini, S. [INFN Laboratori Nazionali del Sud, I-95123 Catania (Italy); Demaret, P. [Centre de Recherches du Cyclotron, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Espino, J.M. [Dept. de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, E-41080 Sevilla (Spain); Figuera, P. [INFN Laboratori Nazionali del Sud, I-95123 Catania (Italy); Freer, M. [School of Physics and Astronomy, University of Birmingham, B15 2TT Birmingham (United Kingdom); Garcia-Ramos, J.E. [Departamento de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain); Gomez-Camacho, J. [Dept. de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, E-41080 Sevilla (Spain); Gulino, M. [INFN Laboratori Nazionali del Sud, I-95123 Catania (Italy); Kakuee, O.R. [Van der Graaff Laboratory, Nuclear Research Centre, AEOI, PO Box 14155-1339, Tehran (Iran, Islamic Republic of); Martel, I. [Dept. de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain)], E-mail: imartel@uhu.es; Metelko, C. [School of Physics and Astronomy, University of Birmingham, B15 2TT Birmingham (United Kingdom); Moro, A.M. [Dept. de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, E-41080 Sevilla (Spain)] (and others)

2008-04-15

The elastic scattering of {sup 6}He on {sup 208}Pb 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.

Grain dynamics and inter-grain coupling in dusty plasma Coulomb crystals

International Nuclear Information System (INIS)

Rahman, H.U.; Mohideen, U.; Smith, M.A.; Rosenberg, M.; Mendis, D.A.

2001-01-01

We review our results on the lattice structure and the lattice dynamics of dusty plasma Coulomb crystals formed in rectangular conductive grooves. The basic structure appears to be made of mutually repulsive columns of grains confined by the walls of the groove. The columns are oriented along the direction of the electrode sheath electric field. Inter-grain coupling as a function of plasma temperature and density were investigated by measurement of these parameters. A simple phenomenological model wherein the inter-grain spacing along the column results from an attractive electric field induced dipole-dipole force balanced by a repulsive monopole Coulomb force is consistent with observed features of the Coulomb crystal. In addition, here we present some preliminary measurements of the vibration and rotation dynamics of the individual grains in the Coulomb crystal. The thermal energy of the dust grain thus calculated is much less than the inter-grain Coulomb potential energy as required for the formation of stable structures. Also the observed rotational frequency is consistent with the assumption of thermal equilibrium between the dust grains and the neutral gas. (orig.)

Dynamical ion transfer between coupled Coulomb crystals in a double-well potential.

Science.gov (United States)

Klumpp, Andrea; Zampetaki, Alexandra; Schmelcher, Peter

2017-09-01

We investigate the nonequilibrium dynamics of coupled Coulomb crystals of different sizes trapped in a double well potential. The dynamics is induced by an instantaneous quench of the potential barrier separating the two crystals. Due to the intra- and intercrystal Coulomb interactions and the asymmetric population of the potential wells, we observe a complex reordering of ions within the two crystals as well as ion transfer processes from one well to the other. The study and analysis of the latter processes constitutes the main focus of this work. In particular, we examine the dependence of the observed ion transfers on the quench amplitude performing an analysis for different crystalline configurations ranging from one-dimensional ion chains via two-dimensional zigzag chains and ring structures to three-dimensional spherical structures. Such an analysis provides us with the means to extract the general principles governing the ion transfer dynamics and we gain some insight on the structural disorder caused by the quench of the barrier height.

A comparison of Coulomb and pseudo-Coulomb friction implementations: Application to the table contact phase of gymnastics vaulting.

Science.gov (United States)

Jackson, M I; Hiley, M J; Yeadon, M R

2011-10-13

In the table contact phase of gymnastics vaulting both dynamic and static friction act. The purpose of this study was to develop a method of simulating Coulomb friction that incorporated both dynamic and static phases and to compare the results with those obtained using a pseudo-Coulomb implementation of friction when applied to the table contact phase of gymnastics vaulting. Kinematic data were obtained from an elite level gymnast performing handspring straight somersault vaults using a Vicon optoelectronic motion capture system. An angle-driven computer model of vaulting that simulated the interaction between a seven segment gymnast and a single segment vaulting table during the table contact phase of the vault was developed. Both dynamic and static friction were incorporated within the model by switching between two implementations of the tangential frictional force. Two vaulting trials were used to determine the model parameters using a genetic algorithm to match simulations to recorded performances. A third independent trial was used to evaluate the model and close agreement was found between the simulation and the recorded performance with an overall difference of 13.5%. The two-state simulation model was found to be capable of replicating performance at take-off and also of replicating key contact phase features such as the normal and tangential motion of the hands. The results of the two-state model were compared to those using a pseudo-Coulomb friction implementation within the simulation model. The two-state model achieved similar overall results to those of the pseudo-Coulomb model but obtained solutions more rapidly. Copyright © 2011 Elsevier Ltd. All rights reserved.

Coulomb Sturmians as a basis for molecular calculations

DEFF Research Database (Denmark)

Avery, John Scales; Avery, James Emil

2012-01-01

mathematical difficulty of evaluating interelectron repulsion integrals when exponential-type orbitals (ETOs) are used. In this paper we show that when many-centre Coulomb Sturmian ETOs are used as a basis, the most important integrals can be evaluated rapidly and accurately by means of the theory...... of hyperspherical harmonics. For the remaining many-centre integrals, Coulomb Sturmians are shown to have advantages over other ETOs. Pilot calculations are performed on N-electron molecules using the Generalized Sturmian Method....

Regularized friction and continuation: Comparison with Coulomb's law

OpenAIRE

Vigué, Pierre; Vergez, Christophe; Karkar, Sami; Cochelin, Bruno

2016-01-01

International audience; Periodic solutions of systems with friction are difficult to investigate because of the irregular nature of friction laws. This paper examines periodic solutions and most notably stick-slip, on a simple one-degre-of-freedom system (mass, spring, damper, belt), with Coulomb's friction law, and with a regularized friction law (i.e. the friction coefficient becomes a function of relative speed, with a stiffness parameter). With Coulomb's law, the stick-slip solution is co...

Coulomb interference and bending slope in hadron-hadron scattering

International Nuclear Information System (INIS)

Pereira, Flavio I.; Ferreira, Erasmo

1994-01-01

With the purpose of testing the results of QCD calculations on the structure of the forward elastic scattering cross-section, we analyse the coulombic-nuclear interference occurring at small values of the momentum transfer. We emphasize the influence of the hadronic structures on the determination of the Coulomb phase and consequently on the t-dependence of the strong interaction slope parameter. (author)

Electron and nuclear dynamics of molecular clusters in ultraintense laser fields. IV. Coulomb explosion of molecular heteroclusters.

Science.gov (United States)

Last, Isidore; Jortner, Joshua

2004-11-01

In this paper we present a theoretical and computational study of the temporal dynamics and energetics of Coulomb explosion of (CD4)(n) and (CH4)(n) (n=55-4213) molecular heteroclusters in ultraintense (I=10(16)-10(19) W cm(-2)) laser fields, addressing the manifestation of electron dynamics, together with nuclear energetic and kinematic effects on the heterocluster Coulomb instability. The manifestations of the coupling between electron and nuclear dynamics were explored by molecular dynamics simulations for these heteroclusters coupled to Gaussian laser fields (pulse width tau=25 fs), elucidating outer ionization dynamics, nanoplasma screening effects (being significant for Icharges and masses. Nonuniform heterocluster Coulomb explosion (eta >1) manifests an overrun effect of the light ions relative to the heavy ions, exhibiting the expansion of two spatially separated subclusters, with the light ions forming the outer subcluster at the outer edge of the spatial distribution. Important features of the energetics of heterocluster Coulomb explosion originate from energetic triggering effects of the driving of the light ions by the heavy ions (C(4+) for I=10(17)-10(18) W cm(-2) and C(6+) for I=10(19) W cm(-2)), as well as for kinematic effects. Based on the CVI assumption, scaling laws for the cluster size (radius R(0)) dependence of the energetics of uniform Coulomb explosion of heteroclusters (eta=1) were derived, with the size dependence of the average (E(j,av)) and maximal (E(j,M)) ion energies being E(j,av)=aR(0) (2) and E(j,M)=(5a/3)R(0) (2), as well as for the ion energy distributions P(E(j)) proportional to E(j) (1/2); E(j)1) result in an isotope effect, predicting the enhancement (by 9%-11%) of E(H,av) for Coulomb explosion of (C(4+)H(4) (+))(eta) (eta=3) relative to E(D,av) for Coulomb explosion of (C(4+)D(4) (+))(eta) (eta=1.5), with the isotope effect being determined by the ratio of the kinematic parameters for the pair of Coulomb exploding clusters

Frictional Magneto-Coulomb Drag in Graphene Double-Layer Heterostructures.

Science.gov (United States)

Liu, Xiaomeng; Wang, Lei; Fong, Kin Chung; Gao, Yuanda; Maher, Patrick; Watanabe, Kenji; Taniguchi, Takashi; Hone, James; Dean, Cory; Kim, Philip

2017-08-04

Coulomb interaction between two closely spaced parallel layers of conductors can generate the frictional drag effect by interlayer Coulomb scattering. Employing graphene double layers separated by few-layer hexagonal boron nitride, we investigate density tunable magneto- and Hall drag under strong magnetic fields. The observed large magnetodrag and Hall-drag signals can be related with Laudau level filling status of the drive and drag layers. We find that the sign and magnitude of the drag resistivity tensor can be quantitatively correlated to the variation of magnetoresistivity tensors in the drive and drag layers, confirming a theoretical formula for magnetodrag in the quantum Hall regime. The observed weak temperature dependence and ∼B^{2} dependence of the magnetodrag are qualitatively explained by Coulomb scattering phase-space argument.

Two-dimensional QCD in the Coulomb gauge

International Nuclear Information System (INIS)

Kalashnikova, Yu.S.; Nefed'ev, A.V.

2002-01-01

Various aspects of the 't Hooft model for two-dimensional QCD in the limit of infinite number of colours in the Coulomb gauge are discussed. The properties of mesonic excitations are studied, with special emphasis on the pion. Attention is paid to the dual role of the pion. which, while a genuine qq-bar state, is a Goldstone boson of two-dimensional QCD as well. In particular, the validity of the soft-pion theorems is demonstrated. It is shown that the Coulomb gauge is the most suitable choice for the study of hadronic observables involving pions [ru

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.

A set-valued force law for spatial Coulomb-Contensou friction

NARCIS (Netherlands)

Leine, R.I.; Glocker, C.

2003-01-01

The aim of this paper is to develop a set-valued contact law for combined spatial Coulomb-Contensou friction, taking into account a normal friction torque (drilling friction) and spin. The set-valued Coulomb-Contensou friction law is derived from a non-smooth velocity pseudo potential. A

Sub-Coulomb heavy ion neutron transfer reactions and neutron orbit sizes

International Nuclear Information System (INIS)

Phillips, W.R.

1976-01-01

Direct transfer reactions below the Coulomb barrier offer the best means of determining neutron densities near the nuclear surface. This paper describes how heavy ion sub-Coulomb transfer can be used to determine the rms radii of neutron orbits in certain nuclei. The theoretical background is outlined and problems associated with the comparison of experiment and theory are discussed. Experiments performed to calibrate sub-Coulomb heavy ion transfer reactions are presented, and some comments are made on the relative roles of light and heavy ion reactions. Preliminary values for the rms radii of neutron orbits and neutron excesses extracted from recent experiments are given, and some remarks are made concerning the implications of these results for the triton wave function and for the Coulomb energy difference anomaly. (author)

11Li Breakup on 208 at energies around the Coulomb barrier.

Science.gov (United States)

Fernández-García, J P; Cubero, M; Rodríguez-Gallardo, M; Acosta, L; Alcorta, M; Alvarez, M A G; Borge, M J G; Buchmann, L; Diget, C A; Falou, H A; Fulton, B R; Fynbo, H O U; Galaviz, D; Gómez-Camacho, J; Kanungo, R; Lay, J A; Madurga, M; Martel, I; Moro, A M; Mukha, I; Nilsson, T; Sánchez-Benítez, A M; Shotter, A; Tengblad, O; Walden, P

2013-04-05

The inclusive breakup for the (11)Li + (208)Pb reaction at energies around the Coulomb barrier has been measured for the first time. A sizable yield of (9)Li following the (11)Li dissociation has been observed, even at energies well below the Coulomb barrier. Using the first-order semiclassical perturbation theory of Coulomb excitation it is shown that the breakup probability data measured at small angles can be used to extract effective breakup energy as well as the slope of B(E1) distribution close to the threshold. Four-body continuum-discretized coupled-channels calculations, including both nuclear and Coulomb couplings between the target and projectile to all orders, reproduce the measured inclusive breakup cross sections and support the presence of a dipole resonance in the (11)Li continuum at low excitation energy.

Mirror symmetry and Coulomb effects in light N ≅ Z nuclei

International Nuclear Information System (INIS)

Bentley, M.A.; Williams, S.J.; Joss, D.T.

2002-01-01

Some latest results from gamma-ray spectroscopic studies of high spin states of isobaric multiplets are presented. An experimental programme is underway to examine exited states of isobaric multiplets of total isospin T 1/2 and T = 1 and the comparison of energies of excited states can be interpreted in terms of Coulomb effects. Through a systematic study of these Coulomb effects, and through examination of the calculated Coulomb energies from full pf-shell model calculations, it is now becoming clear that measurement of Coulomb energies can yield very detailed information on the evolution of nuclear structure phenomena as a function of energy and angular momentum. In this contribution, latest results of studies of isobaric analogue states at high spin in the A = 50, 51 and 53 systems are presented. (author)

Dynamic polarization by coulomb excitation in the closed formalism for heavy ion scattering

International Nuclear Information System (INIS)

Frahn, W.E.; Hill, T.F.

1978-01-01

We present a closed-form treatment of the effects of dynamic polarization by Coulomb excitation on the elastic scattering of deformed heavy ions. We assume that this interaction can be represented by an absorptive polarization potential. The relatively long range of this potential entails a relatively slow variation of the associated reflection function in l-space. This feature leads to a simple generalization of the closed formula derived previously for the elastic scattering amplitude of spherical heavy nuclei. We use both the polarization potential of Love et al. and the recent improved potential of Baltz et al. to derive explicit expressions for the associated reflection functions in a Coulomb-distorted eikonal approximation. As an example we analyze the elastic scattering of 90-MeV 18 O ions by 184 W and show that both results give a quantitative description of the data. (orig.) [de

Coulomb-Fourier representation approach to three-body scattering with charged particles

International Nuclear Information System (INIS)

Alt, E.O.; Levin, S.B.; Yakovlev, S.L.

2004-01-01

We present a novel approach for calculating charged-composite particle scattering. It consists in eliminating by means of a suitably chosen representation that part of the interaction which is of longest range and, hence, gives rise to all the troublesome features which plague charged particle scattering theories. In this paper only the simplest case is considered, namely that of two charged and one neutral particles which interact via pairwise strong potentials, and a repulsive Coulomb potential between the charged particles

Three-dimensional oscillator and Coulomb systems reduced from Kaehler spaces

International Nuclear Information System (INIS)

Nersessian, Armen; Yeranyan, Armen

2004-01-01

We define the oscillator and Coulomb systems on four-dimensional spaces with U(2)-invariant Kaehler metric and perform their Hamiltonian reduction to the three-dimensional oscillator and Coulomb systems specified by the presence of Dirac monopoles. We find the Kaehler spaces with conic singularity, where the oscillator and Coulomb systems on three-dimensional sphere and two-sheet hyperboloid originate. Then we construct the superintegrable oscillator system on three-dimensional sphere and hyperboloid, coupled to a monopole, and find their four-dimensional origins. In the latter case the metric of configuration space is a non-Kaehler one. Finally, we extend these results to the family of Kaehler spaces with conic singularities

Engineering drag currents in Coulomb coupled quantum dots

Science.gov (United States)

Lim, Jong Soo; Sánchez, David; López, Rosa

2018-02-01

The Coulomb drag phenomenon in a Coulomb-coupled double quantum dot system is revisited with a simple model that highlights the importance of simultaneous tunneling of electrons. Previously, cotunneling effects on the drag current in mesoscopic setups have been reported both theoretically and experimentally. However, in both cases the sequential tunneling contribution to the drag current was always present unless the drag level position were too far away from resonance. Here, we consider the case of very large Coulomb interaction between the dots, whereby the drag current needs to be assisted by cotunneling events. As a consequence, a quantum coherent drag effect takes place. Further, we demonstrate that by properly engineering the tunneling probabilities using band tailoring it is possible to control the sign of the drag and drive currents, allowing them to flow in parallel or antiparallel directions. We also show that the drag current can be manipulated by varying the drag gate potential and is thus governed by electron- or hole-like transport.

Room temperature Coulomb blockade mediated field emission via self-assembled gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wang, Fei [College of Physics and Electronics, Central South University, Changsha, Hunan 410073 (China); College of Science, National University of Defense Technology, Changsha, Hunan 410073 (China); Fang, Jingyue, E-mail: fjynudt@aliyun.com [College of Science, National University of Defense Technology, Changsha, Hunan 410073 (China); Chang, Shengli; Qin, Shiqiao; Zhang, Xueao [College of Science, National University of Defense Technology, Changsha, Hunan 410073 (China); Xu, Hui, E-mail: cmpxhg@csu.edu.cn [College of Physics and Electronics, Central South University, Changsha, Hunan 410073 (China)

2017-02-05

Coulomb blockade mediated field-emission current was observed in single-electron tunneling devices based on self-assembled gold nanoparticles at 300 K. According to Raichev's theoretical model, by fixing a proper geometric distribution of source, island and drain, the transfer characteristics can be well explained through a combination of Coulomb blockade and field emission. Coulomb blockade and field emission alternately happen in our self-assembled devices. The Coulomb island size derived from the experimental data is in good agreement with the average size of the gold nanoparticles used in the device. The integrated tunneling can be adjusted via a gate electrode. - Highlights: • The phenomenon of single-electron field emission in a transistor setting using self-assembled gold nanoparticles was investigated. • The transfer characteristics can be well explained by the model that is a combination of Coulomb blockage and field emission. • This transport mechanism is novel and may be used in many applications in field emission devices.

The three-point function in split dimensional regularization in the Coulomb gauge

CERN Document Server

Leibbrandt, G

1998-01-01

We use a gauge-invariant regularization procedure, called ``split dimensional regularization'', to evaluate the quark self-energy $\\Sigma (p)$ and quark-quark-gluon vertex function $\\Lambda_\\mu (p^\\prime,p)$ in the Coulomb gauge, $\\vec{\\bigtriangledown}\\cdot\\vec{A}^a = 0$. The technique of split dimensional regularization was designed to regulate Coulomb-gauge Feynman integrals in non-Abelian theories. The technique which is based on two complex regulating parameters, $\\omega$ and $\\sigma$, is shown to generate a well-defined set of Coulomb-gauge integrals. A major component of this project deals with the evaluation of four-propagator and five-propagator Coulomb integrals, some of which are nonlocal. It is further argued that the standard one-loop BRST identity relating $\\Sigma$ and $\\Lambda_\\mu$, should by rights be replaced by a more general BRST identity which contains two additional contributions from ghost vertex diagrams. Despite the appearance of nonlocal Coulomb integrals, both $\\Sigma$ and $\\Lambda_\\...

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.)

Investigations of direct and sequential Coulomb break-up of light ions

International Nuclear Information System (INIS)

Srivastava, D.K.; Basu, D.N.; Rebel, H.

1988-07-01

Coulomb dissociation of 6 Li in the field of 208 Pb at different energies via resonance and continuum levels is discussed in detail. Relations are given which can be used to directly relate the Coulomb break-up cross section to the astrophysical S-factor. Predictions for energy dependence and angular-distributions are given. The direct Coulomb break-up of 6 Li is found to be of the same order of magnitude as the sequential break-up at higher projectile energies. The effect to eleastic scattering can be accounted for by introducing a dynamic polarization potential. Predictions are given for the direct Coulomb dissociation of 26 MeV/nucleon 7 Li and 16 O incident on 208 Pb through dipole transitions to the continuum, and for 20 Ne via quadrupole transitions in similar experimental situations. (orig.) [de

Derivation of magnetic Coulomb's law for thin, semi-infinite solenoids

OpenAIRE

Kitano, Masao

2006-01-01

It is shown that the magnetic force between thin, semi-infinite solenoids obeys a Coulomb-type law, which corresponds to that for magnetic monopoles placed at the end points of each solenoid. We derive the magnetic Coulomb law from the basic principles of electromagnetism, namely from the Maxwell equations and the Lorentz force.

Inter-grain coupling and grain charge in dusty plasma Coulomb crystals

International Nuclear Information System (INIS)

Smith, M. A.; Goodrich, J.; Mohideen, U.; Rahman, H. U.; Rosenberg, M.; Mendis, D. A.

1998-01-01

We have studied the lattice structure and grain charge of dusty plasma Coulomb crystals formed in rectangular conductive grooves as a function of plasma temperature and density. The crystal appears to be made of mutually repulsive columns of grains confined by the walls of the groove. The columns are oriented along the direction of the electrode sheath electric field. A simple phenomenological model wherein the inter-grain spacing results from an attractive electric field induced dipole-dipole force balanced by a repulsive monopole Coulomb force is consistent with observed features of the Coulomb crystal

One-Step Direct Return Method For Mohr-Coulomb Plasticity

DEFF Research Database (Denmark)

Clausen, Johan; Damkilde, Lars; Andersen, Lars

2004-01-01

A new return method for the Mohr-Coulomb yield criteria is presented. The idea is to transform the problem into the principal direction and thereby achieve very simple formulas for calculating the elastic return stresses.......A new return method for the Mohr-Coulomb yield criteria is presented. The idea is to transform the problem into the principal direction and thereby achieve very simple formulas for calculating the elastic return stresses....

Soft Coulomb gap and asymmetric scaling towards metal-insulator quantum criticality in multilayer MoS2.

Science.gov (United States)

Moon, Byoung Hee; Bae, Jung Jun; Joo, Min-Kyu; Choi, Homin; Han, Gang Hee; Lim, Hanjo; Lee, Young Hee

2018-05-24

Quantum localization-delocalization of carriers are well described by either carrier-carrier interaction or disorder. When both effects come into play, however, a comprehensive understanding is not well established mainly due to complexity and sparse experimental data. Recently developed two-dimensional layered materials are ideal in describing such mesoscopic critical phenomena as they have both strong interactions and disorder. The transport in the insulating phase is well described by the soft Coulomb gap picture, which demonstrates the contribution of both interactions and disorder. Using this picture, we demonstrate the critical power law behavior of the localization length, supporting quantum criticality. We observe asymmetric critical exponents around the metal-insulator transition through temperature scaling analysis, which originates from poor screening in insulating regime and conversely strong screening in metallic regime due to free carriers. The effect of asymmetric scaling behavior is weakened in monolayer MoS 2 due to a dominating disorder.

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

2013-08-07

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 (γ(H) = 2) and eight (γ(1st) = 8) Gaussians on hydrogen and first-row atoms, respectively, with exponents greater than a given threshold (αmin (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 d(4) 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

Hybrid and Constrained Resolution-of-Identity Techniques for Coulomb Integrals.

Science.gov (United States)

Duchemin, Ivan; Li, Jing; Blase, Xavier

2017-03-14

The introduction of auxiliary bases to approximate molecular orbital products has paved the way to significant savings in the evaluation of four-center two-electron Coulomb integrals. We present a generalized dual space strategy that sheds a new light on variants over the standard density and Coulomb-fitting schemes, including the possibility of introducing minimization constraints. We improve in particular the charge- or multipole-preserving strategies introduced respectively by Baerends and Van Alsenoy that we compare to a simple scheme where the Coulomb metric is used for lowest angular momentum auxiliary orbitals only. We explore the merits of these approaches on the basis of extensive Hartree-Fock and MP2 calculations over a standard set of medium size molecules.

Calculation of proton-deuteron phase parameters including the Coulomb force

International Nuclear Information System (INIS)

Alt, E.O.; Sandhas, W.; Ziegelmann, H.

1985-04-01

A previously proposed exact method for including the Coulomb force in three-body collisions is applied to proton-deuteron scattering. We present phase shifts for angular momenta up to L=9, from elastic threshold to 50 MeV proton laboratory energy. Separable rank-one potentials are taken for the nuclear interactions. A charge-independent and a charge-symmetric choise, while leading to different neutron-deuteron and proton-deuteron phase parameters, nevertheless yields practically the same Coulomb corrections. We, moreover, investigate the question of P-wave resonances.A critical comparison of our results with those obtained in a co-ordinate space formalism is performed. Furthermore, proposals for an approximate inclusion of the Coulomb potential are tested, and found unsatisfactory. (orig.)

Electron impact excitation of positive ions calculated in the Coulomb-Born approximation

International Nuclear Information System (INIS)

Nakazaki, Shinobu; Hashino, Tasuke

1979-08-01

Theoretical results on the electron impact excitation of positive ions are surveyed through the end of 1978. As a guide to the available data, a list of references is made. The list shows ion species, transitions, energy range and methods of calculation for the respective data. Based on the literature survey, the validity of the Coulomb-Born approximation is investigated. Comparisons with the results of the close-coupling and the distorted-wave methods are briefly summarized. (author)

Coulomb Final State Interactions for Gaussian Wave Packets

CERN Document Server

Wiedemann, Urs Achim; Heinz, Ulrich W

1999-01-01

Two-particle like-sign and unlike-sign correlations including Coulomb final state interactions are calculated for Gaussian wave packets emitted from a Gaussian source. We show that the width of the wave packets can be fully absorbed into the spatial and momentum space widths of an effective emission function for plane wave states, and that Coulomb final state interaction effects are sensitive only to the latter, but not to the wave packet width itself. Results from analytical and numerical calculations are compared with recently published work by other authors.

Screened coulomb hybrid DFT investigation of band gap and optical absorption predictions of CuVO3, CuNbO3 and Cu 5Ta11O30 materials

KAUST Repository

Harb, Moussab

2014-01-01

We present a joint theoretical and experimental investigation of the optoelectronic properties of CuVO3, CuNbO3 and Cu 5Ta11O30 materials for potential photocatalytic and solar cell applications. In addition to the experimental results obtained by powder X-ray diffraction and UV-Vis spectroscopy of the materials synthesized under flowing N2 gas at atmospheric pressure via solid-state reactions, the electronic structure and the UV-Vis optical absorption coefficient of these compounds are predicted with high accuracy using advanced first-principles quantum methods based on DFT (including the perturbation theory approach DFPT) within the screened coulomb hybrid HSE06 exchange-correlation formalism. The calculated density of states are found to be in agreement with the UV-Vis diffuse reflectance spectra, predicting a small indirect band gap of 1.4 eV for CuVO3, a direct band gap of 2.6 eV for CuNbO3, and an indirect (direct) band gap of 2.1 (2.6) eV for Cu5Ta 11O30. It is confirmed that the Cu(i)-based multi-metal oxides possess a strong contribution of filled Cu(i) states in the valence band and of empty d0 metal states in the conduction band. Interestingly, CuVO3 with its predicted small indirect band gap of 1.4 eV shows the highest absorption coefficient in the visible range with a broad absorption edge extending to 886 nm. This novel result offers a great opportunity for this material to be an excellent candidate for solar cell applications. © the Partner Organisations 2014.

Three-body Coulomb systems using generalized angular-momentum S states

Science.gov (United States)

Whitten, R. C.; Sims, J. S.

1974-01-01

An expansion of the three-body Coulomb potential in generalized angular-momentum eigenfunctions developed earlier by one of the authors is used to compute energy eigenvalues and eigenfunctions of bound S states of three-body Coulomb systems. The results for He, H(-), e(-)e(+)e(-), and pmu(-)p are compared with the results of other computational approaches.

Effects of Coulomb screening and disorder on artificial graphene based on nanopatterned semiconductor

OpenAIRE

Tkachenko, O. A.; Tkachenko, V. A.; Terekhov, I. S.; Sushkov, O. P.

2014-01-01

A residual disorder in the gate system is the main problem on the way to create artificial graphene based on two-dimensional electron gas. The disorder can be significantly screened/reduced due to the many-body effects. To analyse the screening/disorder problem we consider AlGaAs/GaAs/AlGaAs heterostructure with two metallic gates. We demonstrate that the design least susceptible to the disorder corresponds to the weak coupling regime (opposite to tight binding) which is realised via system o...

The three-point function in split dimensional regularization in the Coulomb gauge

International Nuclear Information System (INIS)

Leibbrandt, G.

1998-01-01

We use a gauge-invariant regularization procedure, called split dimensional regularization, to evaluate the quark self-energy Σ(p) and quark-quark-gluon vertex function Λ μ (p',p) in the Coulomb gauge, ∇-vector.A - vectora=0. The technique of split dimensional regularization was designed to regulate Coulomb-gauge Feynman integrals in non-Abelian theories. The technique which is based on two complex regulating parameters, ω and σ, is shown to generate a well-defined set of Coulomb-gauge integrals. A major component of this project deals with the evaluation of four-propagator and five-propagator Coulomb integrals, some of which are non-local. It is further argued that the standard one-loop BRST identity relating Σ and Λ μ , should by rights be replaced by a more general BRST identity which contains two additional contributions from ghost vertex diagrams. Despite the appearance of non-local Coulomb integrals, both Σ and Λ μ are local functions which satisfy the appropriate BRST identity. Application of split dimensional regularization to two-loop energy integrals is briefly discussed. (orig.)

Coulomb stress analysis of the 21 February 2008 Mw= 6.0 Wells, Nevada, earthquake

Science.gov (United States)

Sevilgen, Volkan

2011-01-01

Static Coulomb stress changes imparted by the February 21, 2008 Wells, Nevada earthquake are calculated, using an 8 x 6 km rectangular patch with a uniform slip as a source fault. Stress changes are resolved on nearby active faults using their rake, dip, and strike direction, assuming a fault friction of 0.4. The largest Coulomb stress increase (0.2 bars) imparted to surrounding major active faults from the Wells earthquake occurs on the Clover Hill fault, which may be the southern continuation of the ruptured fault. A 0.1 bar Coulomb stress increase is calculated on the western Snake Mountains fault. Coulomb stress decreases of 0.5 bars are calculated for the northern parts of the Independence and Ruby Mountains faults. The Coulomb stress change is calculated on relocated aftershocks assuming that they have the same strike, dip, and rake, as the source fault. Under this assumption, 75% of the aftershocks received a Coulomb stress increase.

Coulomb oscillations in three-layer graphene nanostructures

International Nuclear Information System (INIS)

Guettinger, J; Stampfer, C; Molitor, F; Graf, D; Ihn, T; Ensslin, K

2008-01-01

We present transport measurements on a tunable three-layer graphene single electron transistor (SET). The device consists of an etched three-layer graphene flake with two narrow constrictions separating the island from source and drain contacts. Three lateral graphene gates are used to electrostatically tune the device. An individual three-layer graphene constriction has been investigated separately showing a transport gap near the charge neutrality point. The graphene tunneling barriers show a strongly nonmonotonic coupling as a function of gate voltage indicating the presence of localized states in the constrictions. We show Coulomb oscillations and Coulomb diamond measurements proving the functionality of the graphene SET. A charging energy of ∼0.6 meV is extracted.

On Coulomb and Viscosity damped single-degree-of-freedom vibrating systems

DEFF Research Database (Denmark)

Jakobsen, J.; Sivebæk, Ion Marius

2016-01-01

influence. The amount of analyses of friction damped system is comparatively more limited. The periodic square wave is a frequently occurring type of friction in this type of analyses. This periodic square wave is often named Coulomb friction. It can be resolved in an infinite series of harmonic components...... with frequencies 1, 3, 5, … times the basic frequency of the square wave and with respective amplitudes: (4/π)∗(1, 1/3, 1/5... )∗Fμ(ωt). Fμ(ωt): the square wave amplitude. The governing equation for the sequence of a free vibration with Coulomb friction damping is nonlinear, but is linear within each ½ period....... A complete solution can therefore be made up compounding solutions from ½ periods by inserting end conditions from one ½ period as initial conditions for the following ½ period. – Only spring and Coulomb forces act together. As a Coulomb force is conceivable as an infinite series of harmonic components...

Investigation of effective impact parameters in electron-ion temperature relaxation via Particle-Particle Coulombic molecular dynamics

Science.gov (United States)

Zhao, Yinjian

2017-09-01

Aiming at a high simulation accuracy, a Particle-Particle (PP) Coulombic molecular dynamics model is implemented to study the electron-ion temperature relaxation. In this model, the Coulomb's law is directly applied in a bounded system with two cutoffs at both short and long length scales. By increasing the range between the two cutoffs, it is found that the relaxation rate deviates from the BPS theory and approaches the LS theory and the GMS theory. Also, the effective minimum and maximum impact parameters (bmin* and bmax*) are obtained. For the simulated plasma condition, bmin* is about 6.352 times smaller than the Landau length (bC), and bmax* is about 2 times larger than the Debye length (λD), where bC and λD are used in the LS theory. Surprisingly, the effective relaxation time obtained from the PP model is very close to the LS theory and the GMS theory, even though the effective Coulomb logarithm is two times greater than the one used in the LS theory. Besides, this work shows that the PP model (commonly known as computationally expensive) is becoming practicable via GPU parallel computing techniques.

11Li Breakup on 208Pb at Energies Around the Coulomb Barrier

DEFF Research Database (Denmark)

Fernández-García, J.P.; Cubero, M.; Rodríguez-Gallardo, M.

2013-01-01

The inclusive breakup for the 11Li+208Pb reaction at energies around the Coulomb barrier has been measured for the first time. A sizable yield of 9Li following the 11Li dissociation has been observed, even at energies well below the Coulomb barrier. Using the first-order semiclassical perturbation...... theory of Coulomb excitation it is shown that the breakup probability data measured at small angles can be used to extract effective breakup energy as well as the slope of B(E1) distribution close to the threshold. Four-body continuum-discretized coupled-channels calculations, including both nuclear...... and Coulomb couplings between the target and projectile to all orders, reproduce the measured inclusive breakup cross sections and support the presence of a dipole resonance in the 11Li continuum at low excitation energy....

Cold transfer between deformed, Coulomb excited nuclei

International Nuclear Information System (INIS)

Bauer, H.

1998-01-01

The scattering system 162 Dy → 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 γ-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 162 Dy has been analyzed. The gross properties of the measured population probabilities could be interpreted in a simple band mixing model. (orig.)

Fusion and quasi-elastic processes near the Coulomb barrier

International Nuclear Information System (INIS)

Abriola, D.

1987-01-01

An overview of the fusion phenomenon below Coulomb barrier is presented. The current theoretical descriptions, emphasizing the relations with direct reactions are discussed. The definition and systematic behaviour of the fusion enhancement below the Coulomb barrier are also presented. The role of coupling to surface degrees of freedom, namely permanent deformations of nuclei, inelastic and transfer channels is shown. The importance of studies describing simultaneously quase-elastic processes and fusion are also shown. (M.C.K.) [pt

Optically induced structural phase transitions in ion Coulomb crystals

DEFF Research Database (Denmark)

Horak, Peter; Dantan, Aurelien Romain; Drewsen, Michael

2012-01-01

We investigate numerically the structural dynamics of ion Coulomb crystals confined in a three-dimensional harmonic trap when influenced by an additional one-dimensional optically induced periodical potential. We demonstrate that transitions between thermally excited crystal structures, such as b......We investigate numerically the structural dynamics of ion Coulomb crystals confined in a three-dimensional harmonic trap when influenced by an additional one-dimensional optically induced periodical potential. We demonstrate that transitions between thermally excited crystal structures...

Electron transport in the presence of a Coulomb field

International Nuclear Information System (INIS)

Burgdoerfer, J.; Gibbons, J.

1990-01-01

We analyze the modifications of the transport behavior of electrons in dense media due to the presence of a strong Coulomb field generated by an ion moving initially in close phase-space correlation with the electrons. These modifications play a profound role in convoy electron emission in ion-solid collisions. The transport behavior is studied within the framework of a classical phase-space master equation. The nonseparable master equation is solved numerically using test-particle discretization and Monte Carlo sampling. In the limit of vanishing Coulomb forces the master equation becomes separable and can be reduced to standard one-dimensional kinetic equations for free-electron transport that can be solved exactly. The comparison to free-electron transport is used to gauge both the reliability of test-particle discretization and the significance of Coulomb distortion of the distribution functions. Applications to convoy-electron emission are discussed

Nonthermal and screening effects on photoionizations in Lorentzian plasmas

International Nuclear Information System (INIS)

Shin, Dong-Soo; Jung, Young-Dae

2009-01-01

The nonthermal and plasma screening effects on the x-ray photoionization process are investigated in astrophysical Lorentzian plasmas. The screened atomic wave function and energy eigenvalue of the target ion in Lorentzian plasmas are obtained by the Rayleigh-Ritz variational method. The x-ray retardation and screened Coulomb corrections are considered to obtain a photoionization cross section as a function of the spectral index and plasma parameters. It is shown that the nonthermal character of the Lorentzian plasma suppresses the photoionization cross section. Hence, the photoionization cross sections in nonthermal plasmas are found to be always smaller than those in thermal plasmas. It is also shown that the plasma screening effect is more significant for small spectral indices. In addition, the nonthermal effect on the photoionization cross section is found to be decreased with an increase in the Debye length.

Coulomb interactions between cytoplasmic electric fields and phosphorylated messenger proteins optimize information flow in cells.

Directory of Open Access Journals (Sweden)

Robert A Gatenby

2010-08-01

Full Text Available Normal cell function requires timely and accurate transmission of information from receptors on the cell membrane (CM to the nucleus. Movement of messenger proteins in the cytoplasm is thought to be dependent on random walk. However, Brownian motion will disperse messenger proteins throughout the cytosol resulting in slow and highly variable transit times. We propose that a critical component of information transfer is an intracellular electric field generated by distribution of charge on the nuclear membrane (NM. While the latter has been demonstrated experimentally for decades, the role of the consequent electric field has been assumed to be minimal due to a Debye length of about 1 nanometer that results from screening by intracellular Cl- and K+. We propose inclusion of these inorganic ions in the Debye-Huckel equation is incorrect because nuclear pores allow transit through the membrane at a rate far faster than the time to thermodynamic equilibrium. In our model, only the charged, mobile messenger proteins contribute to the Debye length.Using this revised model and published data, we estimate the NM possesses a Debye-Huckel length of a few microns and find this is consistent with recent measurement using intracellular nano-voltmeters. We demonstrate the field will accelerate isolated messenger proteins toward the nucleus through Coulomb interactions with negative charges added by phosphorylation. We calculate transit times as short as 0.01 sec. When large numbers of phosphorylated messenger proteins are generated by increasing concentrations of extracellular ligands, we demonstrate they generate a self-screening environment that regionally attenuates the cytoplasmic field, slowing movement but permitting greater cross talk among pathways. Preliminary experimental results with phosphorylated RAF are consistent with model predictions.This work demonstrates that previously unrecognized Coulomb interactions between phosphorylated messenger

Role of Coulomb repulsion in multilayer cuprate superconductor

International Nuclear Information System (INIS)

Singh Chauhan, Ekta; Singh, Vipul; Masih, Piyush

2012-01-01

Although BCS theory completely neglects coulomb repulsion; Anderson and Morel showed very early that it plays a central role in superconductivity. Since all high T c superconductors are based on the structure of closely spaced square planner CuO 2 layers and role of interlayer interaction plays important role in enhancement of T c . Therefore the work has been dealt with 'Role of Coulomb repulsion in Multilayer Cuprate Superconductors'. An expression for transition temperature T c is obtained by using simple integration technique and is numerically solved. It has found that T c decreases with electronic repulsion. (author)

The effect of charged quantum dots on the mobility of a two-dimensional electron gas: How important is the Coulomb scattering?

International Nuclear Information System (INIS)

Kurzmann, A.; Beckel, A.; Lorke, A.; Geller, M.; Ludwig, A.; Wieck, A. D.

2015-01-01

We have investigated the influence of a layer of charged self-assembled quantum dots (QDs) on the mobility of a nearby two-dimensional electron gas (2DEG). Time-resolved transconductance spectroscopy was used to separate the two contributions of the change in mobility, which are: (i) The electrons in the QDs act as Coulomb scatterers for the electrons in the 2DEG. (ii) The screening ability and, hence, the mobility of the 2DEG decreases when the charge carrier density is reduced by the charged QDs, i.e., the mobility itself depends on the charge carrier concentration. Surprisingly, we find a negligible influence of the Coulomb scattering on the mobility for a 2DEG, separated by a 30 nm tunneling barrier to the layer of QDs. This means that the mobility change is completely caused by depletion, i.e., reduction of the charge carrier density in the 2DEG, which indirectly influences the mobility

Calculation of the Coulomb nuclear energy for the 1fsub(7/2) shell

International Nuclear Information System (INIS)

Kaminski, V.A.; Shpikovski, S.

1980-01-01

Calculated was the Coulomb energy for nuclei with half-filled 1fsub(7/2) shell i.e. for configurations, where quasiparticle basis can serve as a total basis for precise calculations. Presented are calculation results of vector and tensor components of the Coulomb energy for Ca-Se-Ti-V isobaric pairs, as well as experimental and theoretical values for the Coulomb displacements. To estimate the Coulomb energies used were wave functions of a Hamiltonian taking account of pair and quadrupole interactions. There is good agreement with experimental data. Quasiparticle consideration is useful for calculating matrix elements of half-filled shells and for the cases of such an isospin value, where the technique of genealogical coefficients becomes extremely cumbersome

Finite size and Coulomb corrections: from nuclei to nuclear liquid vapor phase diagram

International Nuclear Information System (INIS)

Moretto, L.G.; Elliott, J.B.; Phair, L.

2003-01-01

In this paper we consider the problem of obtaining the infinite symmetric uncharged nuclear matter phase diagram from a thermal nuclear reaction. In the first part we shall consider the Coulomb interaction which, because of its long range makes the definition of phases problematic. This Coulomb effect seems truly devastating since it does not allow one to define nuclear phase transitions much above A ∼ 30. However there may be a solution to this difficulty. If we consider the emission of particles with a sizable charge, we notice that a large Coulomb barrier Bc is present. For T << Bc these channels may be considered effectively closed. Consequently the unbound channels may not play a role on a suitably short time scale. Then a phase transition may still be definable in an approximate way. In the second part of the article we shall deal with the finite size problem by means of a new method, the complement method, which shall permit a straightforward extrapolation to the infinite system. The complement approach consists of evaluating the change in free energy occurring when a particle or cluster is moved from one (finite) phase to another. In the case of a liquid drop in equilibrium with its vapor, this is done by extracting a vapor particle of any given size from the drop and evaluating the energy and entropy changes associated with both the vapor particle and the residual liquid drop (complement)

Lee-Nauenberg theorem and Coulomb scattering

Energy Technology Data Exchange (ETDEWEB)

Fleming, H; Frenkel, J [Sao Paulo Univ. (Brazil). Instituto de Fisica

1975-08-01

Lee-Nauenberg analysis is extended to the case of Coulomb scattering, where the diagonal elements of the Hamiltonian interaction are singular functions. It is shown, using a simple argument, that the leading infrared singularities in the cross-section are mutually canceled out.

Towards a First-Principles Determination of Effective Coulomb Interactions in Correlated Electron Materials: Role of Intershell Interactions.

Science.gov (United States)

Seth, Priyanka; Hansmann, Philipp; van Roekeghem, Ambroise; Vaugier, Loig; Biermann, Silke

2017-08-04

The determination of the effective Coulomb interactions to be used in low-energy Hamiltonians for materials with strong electronic correlations remains one of the bottlenecks for parameter-free electronic structure calculations. We propose and benchmark a scheme for determining the effective local Coulomb interactions for charge-transfer oxides and related compounds. Intershell interactions between electrons in the correlated shell and ligand orbitals are taken into account in an effective manner, leading to a reduction of the effective local interactions on the correlated shell. Our scheme resolves inconsistencies in the determination of effective interactions as obtained by standard methods for a wide range of materials, and allows for a conceptual understanding of the relation of cluster model and dynamical mean field-based electronic structure calculations.

The screening length of interatomic potential in atomic collisions

International Nuclear Information System (INIS)

Yamamura, Y.; Takeuchi, W.; Kawamura, T.

1998-03-01

In computer studies on the interaction of charged particle with solids, many authors treat the nuclear collision by the Thomas-Fermi screened Coulomb potential. For better agreement with experiment, the screening length is modified sometimes. We investigate the theoretical background for the correction factor of the screening length in the interatomic potential which can be deduced from two steps. The first step is to select the correction factor of an isolated atom so as to match the average radius of the Thomas-Fermi electron distribution with that of the Hartree-Fock electron distribution, where we use the Clementi and Roetti's table. The second step is to determine the correction factor of the screening length of the interatomic potential by using a combination rule. The correction factors obtained for the screening length are in good agreement with those determined by the computer analysis of the Impact Collision Ion Scattering Spectroscopy (ICISS) data. (author)

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.

Interaction of charged 3D soliton with Coulomb center

International Nuclear Information System (INIS)

Rybakov, Yu.P.

1996-03-01

The Einstein - de Broglie particle-soliton concept is applied to simulate stationary states of an electron in a hydrogen atom. According to this concept, the electron is described by the localized regular solutions to some nonlinear equations. In the framework of Synge model for interacting scalar and electromagnetic fields a system of integral equations has been obtained, which describes the interaction between charged 3D soliton and Coulomb center. The asymptotic expressions for physical fields, describing soliton moving around the fixed Coulomb center, have been obtained with the help of integral equations. It is shown that the electron-soliton center travels along some stationary orbit around the Coulomb center. The electromagnetic radiation is absent as the Poynting vector has non-wave asymptote O(r -3 ) after averaging over angles, i.e. the existence of spherical surface corresponding to null Poynting vector stream, has been proved. Vector lines for Poynting vector are constructed in asymptotical area. (author). 22 refs, 2 figs

Dynamical Symmetries of Two-Dimensional Dirac Equation with Screened Coulomb and Isotropic Harmonic Oscillator Potentials

International Nuclear Information System (INIS)

Wang Qing; Hou Yu-Long; Jing Jian; Long Zheng-Wen

2014-01-01

In this paper, we study symmetrical properties of two-dimensional (2D) screened Dirac Hydrogen atom and isotropic harmonic oscillator with scalar and vector potentials of equal magnitude (SVPEM). We find that it is possible for both cases to preserve so(3) and su(2) dynamical symmetries provided certain conditions are satisfied. Interestingly, the conditions for preserving these dynamical symmetries are exactly the same as non-relativistic screened Hydrogen atom and screened isotropic oscillator preserving their dynamical symmetries. Some intuitive explanations are proposed. (general)

Theoretical studies of finite size effects and screening effects caused by a STM tip in Luettinger liquids

International Nuclear Information System (INIS)

Guigou, Marine

2009-01-01

This thesis takes place in the field of condensed matter. More precisely, we focus on the finite size effects and the screening effects caused by a STM tip in a quantum wire. For that, we use, first, the Luettinger liquid theory, which allows to describe strongly correlated systems and secondly, the Keldysh formalism, which is necessary to treat the out-of-equilibrium systems. For these studies, we consider, the currant, the noise and the conductance. The noise presents a non-Poissonian behaviour, when finite size effects appear. Through the photo-assisted transport, it is shown that those effects hide the effects of the Coulomb interactions. Considering the proximity between the STM tip, used as a probe or as an injector, and a quantum wire, screening effects appear. We can conclude that they play a similar role to those of Coulomb interactions. (author) [fr

Coulomb pair-creation

International Nuclear Information System (INIS)

Hrasko, P.; Foeldy, L.; Toth, A.

1986-07-01

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)

The statistical mechanics of the classical two-dimensional Coulomb gas is exactly solved

International Nuclear Information System (INIS)

Samaj, L

2003-01-01

The model under consideration is a classical 2D Coulomb gas of pointlike positive and negative unit charges, interacting via a logarithmic potential. In the whole stability range of temperatures, the equilibrium statistical mechanics of this fluid model is exactly solvable via an equivalence with the integrable 2D sine-Gordon field theory. The exact solution includes the bulk thermodynamics, special cases of the surface thermodynamics and the large-distance asymptotic behaviour of the two-body correlation functions

Hybrid and Constrained Resolution-of-Identity Techniques for Coulomb Integrals

OpenAIRE

Duchemin , Ivan; Li , Jing; Blase , Xavier

2017-01-01

International audience; The introduction of auxiliary bases to approximate molecular orbital products has paved the way to significant savings in the evaluation of four-center two-electron Coulomb integrals. We present a generalized dual space strategy that sheds a new light on variants over the standard density and Coulomb-fitting schemes, including the possibility of introducing minimization constraints. We improve in particular the charge- or multipole-preserving strategies introduced resp...

A uniform semi-classical approach to the Coulomb fission problem

International Nuclear Information System (INIS)

Levit, S.; Smilansky, U.

1978-01-01

A semi-classical theory based on the path integral formalism is applied to the description of Coulomb fission. Complex classical trajectories are used to compute the classically forbidden transitions from the target's ground state to fission. In a simple model the energy spectrum and angular distributions of the fragments are calculated for the Coulomb fission in the Xe + U collision. Theoretical predictions are made which may be checked experimentally. (author)

Representation of the Coulomb Matrix Elements by Means of Appell Hypergeometric Function F 2

Science.gov (United States)

Bentalha, Zine el abidine

2018-06-01

Exact analytical representation for the Coulomb matrix elements by means of Appell's double series F 2 is derived. The finite sum obtained for the Appell function F 2 allows us to evaluate explicitly the matrix elements of the two-body Coulomb interaction in the lowest Landau level. An application requiring the matrix elements of Coulomb potential in quantum Hall effect regime is presented.

Study of breakup mechanism of a loosely bound projectile in a region of Coulomb-breakup dominance

Directory of Open Access Journals (Sweden)

Uesaka T.

2010-04-01

Full Text Available A kinematically complete measurement of the deuteron elastic break reaction has been carried out at Ed = 140 MeV on 12C, 40Ca, 90Zr, and 208Pb targets in a wide angular range of θp , θn = 0° –8° for a detailed study of the reaction mechanism of loosely bound projectiles in kinematical regions of Coulomb-breakup dominance. A finite-range calculation of the post-form distorted-wave Born approximation is presented.

Plasmons in Dimensionally Mismatched Coulomb Coupled Graphene Systems.

Science.gov (United States)

Badalyan, S M; Shylau, A A; Jauho, A P

2017-09-22

We calculate the plasmon dispersion relation for Coulomb coupled metallic armchair graphene nanoribbons and doped monolayer graphene. The crossing of the plasmon curves, which occurs for uncoupled 1D and 2D systems, is split by the interlayer Coulomb coupling into a lower and an upper plasmon branch. The upper branch exhibits an unusual behavior with end points at finite q. Accordingly, the structure factor shows either a single or a double peak behavior, depending on the plasmon wavelength. The new plasmon structure is relevant to recent experiments, its properties can be controlled by varying the system parameters and be used in plasmonic applications.

Two-craft Coulomb formation study about circular orbits and libration points

Science.gov (United States)

Inampudi, Ravi Kishore

This dissertation investigates the dynamics and control of a two-craft Coulomb formation in circular orbits and at libration points; it addresses relative equilibria, stability and optimal reconfigurations of such formations. The relative equilibria of a two-craft tether formation connected by line-of-sight elastic forces moving in circular orbits and at libration points are investigated. In circular Earth orbits and Earth-Moon libration points, the radial, along-track, and orbit normal great circle equilibria conditions are found. An example of modeling the tether force using Coulomb force is discussed. Furthermore, the non-great-circle equilibria conditions for a two-spacecraft tether structure in circular Earth orbit and at collinear libration points are developed. Then the linearized dynamics and stability analysis of a 2-craft Coulomb formation at Earth-Moon libration points are studied. For orbit-radial equilibrium, Coulomb forces control the relative distance between the two satellites. The gravity gradient torques on the formation due to the two planets help stabilize the formation. Similar analysis is performed for along-track and orbit-normal relative equilibrium configurations. Where necessary, the craft use a hybrid thrusting-electrostatic actuation system. The two-craft dynamics at the libration points provide a general framework with circular Earth orbit dynamics forming a special case. In the presence of differential solar drag perturbations, a Lyapunov feedback controller is designed to stabilize a radial equilibrium, two-craft Coulomb formation at collinear libration points. The second part of the thesis investigates optimal reconfigurations of two-craft Coulomb formations in circular Earth orbits by applying nonlinear optimal control techniques. The objective of these reconfigurations is to maneuver the two-craft formation between two charged equilibria configurations. The reconfiguration of spacecraft is posed as an optimization problem using the

Isospin effect of coulomb interaction on momentum dissipation in intermediate energy heavy ion collisions

International Nuclear Information System (INIS)

Liu Jianye; Guo Wenjun; Li Xiguo; Xing Yongzhong

2004-01-01

The authors investigate the isospin effect of Coulomb interaction on the momentum dissipation or nuclear stopping in the intermediate energy heavy ion collisions by using the isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces obviously the reductions of the momentum dissipation. The authors also find that the variation amplitude of momentum dissipation induced by the Coulomb interaction depends sensitively on the form and strength of symmetry potential. However, the isospin effect of Coulomb interaction on the momentum dissipation is less than that induced by the in-medium nucleon-nucleon cross section. In this case, Coulomb interaction does not changes obviously the isospin effect of momentum dissipation induced by the in-medium two-body collision. In particular, the Coulomb interaction is preferable for standing up the isospin effect of in-medium nucleon-nucleon cross section on the momentum dissipation and reducing the isospin effect of symmetry potential on it, which is important for obtaining the feature about the sensitive dependence of momentum dissipation on the in-medium nucleon-nucleon cross section and weakly on the symmetry potential. (author)

Chiral-symmetry restoration at finite densities in Coulomb-gauge QCD

International Nuclear Information System (INIS)

Kocic, A.

1986-01-01

Using the Schwinger-Dyson equation in the Hartree-Fock approximation, we show that, within a potential model motivated by the QCD Hamiltonian in the Coulomb gauge, chiral symmetry is restored at finite densities. Two cases are studied: a delta-function potential and a linear confining potential. For the former case the phase diagram is obtained analytically, whereas for the latter case numerical techniques are used. The values of physical quantities calculated for the linear confining model are consistently smaller than the experimental ones indicating that a potential with additional short-range attraction is needed to describe the quark interaction in the high-density regime

Coulomb's Electrical Measurements. Experiment No. 14.

Science.gov (United States)

Devons, Samuel

Presented is information related to the life and work of Charles Coulomb as well as detailed notes of his measurements of the distribution of electricity on conductors. The two methods that he used (the large torsion balance, and the timing of "force" oscillations) are described. (SA)

Investigation of uncertainty components in Coulomb blockade thermometry

International Nuclear Information System (INIS)

Hahtela, O. M.; Heinonen, M.; Manninen, A.; Meschke, M.; Savin, A.; Pekola, J. P.; Gunnarsson, D.; Prunnila, M.; Penttilä, J. S.; Roschier, L.

2013-01-01

Coulomb blockade thermometry (CBT) has proven to be a feasible method for primary thermometry in every day laboratory use at cryogenic temperatures from ca. 10 mK to a few tens of kelvins. The operation of CBT is based on single electron charging effects in normal metal tunnel junctions. In this paper, we discuss the typical error sources and uncertainty components that limit the present absolute accuracy of the CBT measurements to the level of about 1 % in the optimum temperature range. Identifying the influence of different uncertainty sources is a good starting point for improving the measurement accuracy to the level that would allow the CBT to be more widely used in high-precision low temperature metrological applications and for realizing thermodynamic temperature in accordance to the upcoming new definition of kelvin

Investigation of uncertainty components in Coulomb blockade thermometry

Energy Technology Data Exchange (ETDEWEB)

Hahtela, O. M.; Heinonen, M.; Manninen, A. [MIKES Centre for Metrology and Accreditation, Tekniikantie 1, 02150 Espoo (Finland); Meschke, M.; Savin, A.; Pekola, J. P. [Low Temperature Laboratory, Aalto University, Tietotie 3, 02150 Espoo (Finland); Gunnarsson, D.; Prunnila, M. [VTT Technical Research Centre of Finland, Tietotie 3, 02150 Espoo (Finland); Penttilä, J. S.; Roschier, L. [Aivon Oy, Tietotie 3, 02150 Espoo (Finland)

2013-09-11

Coulomb blockade thermometry (CBT) has proven to be a feasible method for primary thermometry in every day laboratory use at cryogenic temperatures from ca. 10 mK to a few tens of kelvins. The operation of CBT is based on single electron charging effects in normal metal tunnel junctions. In this paper, we discuss the typical error sources and uncertainty components that limit the present absolute accuracy of the CBT measurements to the level of about 1 % in the optimum temperature range. Identifying the influence of different uncertainty sources is a good starting point for improving the measurement accuracy to the level that would allow the CBT to be more widely used in high-precision low temperature metrological applications and for realizing thermodynamic temperature in accordance to the upcoming new definition of kelvin.

The Coulomb break-up of 9Be

International Nuclear Information System (INIS)

Macdonald, E.W.; Shotter, A.C.; Branford, D.; Rahighi, J.; Davinson, T.; Davis, N.J.

1992-01-01

Kinematically complete data is presented on the break-up reaction 120 Sn( 9 Be, 8 Be g.s +n) 120 Sn g.s. at E beam =90 MeV for several scattering angles inside the grazing angle. These data are compared with the predictions of a Coulomb break-up model. It is shown that the data can be understood in terms of the Coulomb model provided some account is taken of the interactions of the break-up fragments with the target. Analysis of the 9 Be break-up data, using radio-isotope measurements of the 9 Be(γ, n) cross-section, indicates that for this photo-disintegration reaction there is probably a significant direct component to the threshold cross-section, in addition to a threshold resonance at 1.69 MeV. (orig.)

Unsafe Coulomb excitation of $^{240-244}Pu$

CERN Document Server

Wiedenhöver, I; Hackman, L; Ahmad, I; Greene, J P; Amro, H; Carpenter, M P; Nisius, D T; Reiter, P; Lauritsen, T; Lister, C J; Khoo, T L; Siem, S; Cizewski, J A; Seweryniak, D; Uusitalo, J; Macchiavelli, A O; Chowdhury, P; Seabury, E H; Cline, D; Wu, C Y

1999-01-01

The high spin states of /sup 240/Pu and /sup 244/Pu have been investigated with GAMMASPHERE at ATLAS, using Coulomb excitation with a /sup 208/Pb beam at energies above the Coulomb barrier. Data on a transfer channel leading to /sup 242/Pu were obtained as well. In the case of /sup 244/Pu, the yrast band was extended to 34h(cross), revealing the completed pi i/sub 13/2/ alignment, a "first" for actinide nuclei. The yrast sequence of /sup 242/Pu was also extended to higher spin and a similar backbend was delineated. In contrast, while the ground state band of /sup 240/Pu was measured up to the highest rotational frequencies ever reported in the actinide region (~300 keV), no sign of particle alignment was observed. (11 refs).

Effective quantum theories with short- and long-range forces

International Nuclear Information System (INIS)

Koenig, Sebastian

2013-01-01

At low energies, nonrelativistic quantum systems are essentially governed by their wave functions at large distances. For this reason, it is possible to describe a wide range of phenomena with short- or even finite-range interactions. In this thesis, we discuss several topics in connection with such an effective description and consider, in particular, modifications introduced by the presence of additional long-range potentials. In the first part we derive general results for the mass (binding energy) shift of bound states with angular momentum L ≥ 1 in a periodic cubic box in two and three spatial dimensions. Our results have applications to lattice simulations of hadronic molecules, halo nuclei, and Feshbach molecules. The sign of the mass shift can be related to the symmetry properties of the state under consideration. We verify our analytical results with explicit numerical calculations. Moreover, we discuss the case of twisted boundary conditions that arise when one considers moving bound states in finite boxes. The corresponding finite-volume shifts in the binding energies play an important role in the study of composite-particle scattering on the lattice, where they give rise to topological correction factors. While the above results are derived under the assumption of a pure finite-range interaction - and are still true up to exponentially small correction in the short-range case - in the second part we consider primarily systems of charged particles, where the Coulomb force determines the long-range part of the potential. In quantum systems with short-range interactions, causality imposes nontrivial constraints on low-energy scattering parameters. We investigate these causality constraints for systems where a long-range Coulomb potential is present in addition to a short-range interaction. The main result is an upper bound for the Coulomb-modified effective range parameter. We discuss the implications of this bound to the effective feld theory (EFT) for

Quasi-stationary states and fermion pair creation from a vacuum in supercritical Coulomb field

Science.gov (United States)

Khalilov, V. R.

2017-12-01

Creation of charged fermion pair from a vacuum in so-called supercritical Coulomb potential is examined for the case when fermions can move only in the same (one) plane. In which case, quantum dynamics of charged massive or massless fermions can be described by the two-dimensional Dirac Hamiltonians with an usual (-a/r) Coulomb potential. These Hamiltonians are singular and require the additional definition in order for them to be treated as self-adjoint quantum-mechanical operators. We construct the self-adjoint two-dimensional Dirac Hamiltonians with a Coulomb potential and determine the quantum-mechanical states for such Hamiltonians in the corresponding Hilbert spaces of square-integrable functions. We determine the scattering amplitude in which the self-adjoint extension parameter is incorporated and then obtain equations implicitly defining possible discrete energy spectra of the self-adjoint Dirac Hamiltonians with a Coulomb potential. It is shown that this quantum system becomes unstable in the presence of a supercritical Coulomb potential which manifests in the appearance of quasi-stationary states in the lower (negative) energy continuum. The energy spectrum of those states is quasi-discrete, consists of broadened levels with widths related to the inverse lifetimes of the quasi-stationary states as well as the probability of creation of charged fermion pair by a supercritical Coulomb field. Explicit analytical expressions for the creation probabilities of charged (massive or massless) fermion pair are obtained in a supercritical Coulomb field.

Scattering at low energies by potentials containing power-law corrections to the Coulomb interaction

International Nuclear Information System (INIS)

Kuitsinskii, A.A.

1986-01-01

The low-energy asymptotic behavior is found for the phase shifts and scattering amplitudes in the case of central potentials which decrease at infinity as n/r+ar /sup -a/,a 1. In problems of atomic and nuclear physics one is generally interested in collisions of clusters consisting of several charged particles. The effective interaction potential of such clusters contains long-range power law corrections to the Coulomb interaction that is presented

Scattering amplitudes on the Coulomb branch of N=4 super Yang-Mills

International Nuclear Information System (INIS)

Henn, J.M.

2010-01-01

We discuss planar scattering amplitudes on the Coulomb branch of N=4 super Yang-Mills. The vacuum expectation values on the Coulomb branch can be used to regulate infrared divergences. We argue that this has a number of conceptual as well as practical advantages over dimensional regularisation.

Coulomb disintegration as an information source for relevant processes in nuclear astrophysics

International Nuclear Information System (INIS)

Bertulani, C.A.

1989-01-01

The possibility of obtaining the photodisintegration cross section using the equivalent-photon number method first deduced and employed for the Coulomb disintegration processes has been suggested. This is very interesting because there exist radioactive capture processes, related to the photodisintegration through time reversal, that are relevant in astrophysics. In this paper, the recent results of the Karlsruhe and the Texas A and M groups on the Coulomb disintegration of 6 Li and 7 Li and the problems of the method are discussed. The ideas developed in a previous paper (Nucl. Phys. A458 (1986) 188) are confirmed qualitatively. To understand the process quantitatively it is necessary to use a quantum treatment that would imply the introduction of Coulomb excitation effects of higher orders. The Coulomb disintegration of exotic secondary beams is also studied. It is particularly interesting the question about what kind of nuclear structure information, as binding energies of momentum distributions, may be obtained. (Author) [es

Simplistic Coulomb Forces in Molecular Dynamics

DEFF Research Database (Denmark)

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

2012-01-01

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...

Monotonicity and concavity in Coulomb systems

International Nuclear Information System (INIS)

Englisch, R.; Englisch, H.; Karl-Marx-Universitaet, Leipzig

1986-01-01

The eigenvalues of H(α) = H 0 + αH * , where H * is an arbitrary Coulomb potential, decrease with increasing α ≥ 0. Linear and parabolic bounds for the ground state energy are presented. These bounds are applied to the biexciton and the exciton at a neutral donor. (orig.)

Measurements on the extended range of the wake

International Nuclear Information System (INIS)

Kumbartzki, G.J.; Kroesing, G; Neuburger, H.

1981-01-01

The Coulomb explosion of H 2 + -ions at 28 MeV is used to probe the wake over a range of about 400 A in Al. Preliminary results give food agreement with the wavelength prediction of the simple plasma oscillation wake model. (author)

Resistive transition for two-dimensional superconductors: Comparison between experiments and Coulomb-gas-model predictions

International Nuclear Information System (INIS)

Minnhagen, P.

1983-01-01

The Coulomb-gas model of vortex fluctuations leads to scaling relations for the resistive transition which can be directly tested by experiments. By analyzing published resistance data, it is shown that there is experimental evidence for the Coulomb-gas scaling relation in the absence of a perpendicular magnetic field. It is also shown that there exists some suggestive support for the Coulomb-gas predictions in the presence of a magnetic field

Effect of the moment-of-inertia variation on Coulomb-nuclear interference in heavy ion scattering

International Nuclear Information System (INIS)

Bolotin, Yu.L.; Gonchar, V.Yu.; Inopin, E.V.; Chekanov, N.A.

1987-01-01

Effect of moment-of-inertia (MI) variation on probabilities of the Coulomb excitation of nucleus rotational states (RS) is investigated. The calculation is performed in the generalized quasiclassical approximation. Cillisions with an aimed parameter equal to 0 and recording of scattered ion at angles close to 180 deg were considered. Effect of MI dependence on angular momentum (AM) on the RS Coulomb excitation probability in the 86 Kr+ 238 U process at 400 MeV 86 Kr has been studied. For small AMs (I < 10), when the MI variation can be neglected, the Coulomb-nuclear interference leads to a marked shift of RS excitation probability maxima. However, with increasing transferred AM the convergence of probabilities conditioned with mutual compensation of phases shift related to the MI variation and Coulomb-nucleus interference, is noted. It is also noted that correct parameters of deformed nuclei extracted from experiments on the Coulomb excitation of high-spin states can be obtained only during simultaneous accountancy of both the Coulomb-nuclear interference and the MI variation of excited nuclei

Effective Kratzer and Coulomb potentials as limit cases of a multiparameter exponential-type potential

Energy Technology Data Exchange (ETDEWEB)

García-Ravelo, J., E-mail: g.ravelo@hotmail.com [Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Edificio 9, Unidad Profesional Adolfo López Mateos, México D.F., 07738 (Mexico); Menéndez, A.; García-Martínez, J. [Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Edificio 9, Unidad Profesional Adolfo López Mateos, México D.F., 07738 (Mexico); Schulze-Halberg, A. [Department of Mathematics and Actuarial Science and Department of Physics, Indiana University Northwest, 3400 Broadway, Gary, IN 46408 (United States)

2014-06-13

We show that the effective Kratzer and Coulomb potentials can be obtained by taking particular limits of a multiparameter exponential potential that was studied recently. Moreover, we demonstrate that the bound state solutions of the exponential potential reduce correctly to their well-known counterparts associated with the Kratzer and Coulomb potentials. As a byproduct, we obtain a new limit relation for the hypergeometric function. - Highlights: • Kratzer and Coulomb potentials are limit cases of an exponential-type potential. • From exact s-waves, approximate solutions for l-waves are obtained. • l-waves of the potential tend to the solutions of the Kratzer and Coulomb potentials. • A non-evident identity between hypergeometric functions is demonstrated.

Effective Kratzer and Coulomb potentials as limit cases of a multiparameter exponential-type potential

International Nuclear Information System (INIS)

García-Ravelo, J.; Menéndez, A.; García-Martínez, J.; Schulze-Halberg, A.

2014-01-01

We show that the effective Kratzer and Coulomb potentials can be obtained by taking particular limits of a multiparameter exponential potential that was studied recently. Moreover, we demonstrate that the bound state solutions of the exponential potential reduce correctly to their well-known counterparts associated with the Kratzer and Coulomb potentials. As a byproduct, we obtain a new limit relation for the hypergeometric function. - Highlights: • Kratzer and Coulomb potentials are limit cases of an exponential-type potential. • From exact s-waves, approximate solutions for l-waves are obtained. • l-waves of the potential tend to the solutions of the Kratzer and Coulomb potentials. • A non-evident identity between hypergeometric functions is demonstrated

Effect of Coulomb stress on the Gutenberg-Richter law

Science.gov (United States)

Navas-Portella, V.; Corral, A.; Jimenez, A.

2017-12-01

Coulomb stress theory has been used for years in seismology to understand how earthquakes trigger each other. Whenever an earthquake occurs, the stress field changes in its neighbourhood, with places with positive values brought closer to failure, whereas negative values distance away that location from failure. Earthquake models that relate rate changes and Coulomb stress after a main event, such as the rate-and-state model, assume negative and positive stress values affect rate changes according to the same functional form. As a first order approximation, under uniform background seismicity before the main event, different values of the b-exponent in the Gutenberg-Richter law would indicate different behaviour for positive and negative stress. In this work, we study the Gutenberg-Richter law in the aftershock sequence of the Landers earthquake (California, 1992, MW=7.3). By using a statistically based fitting method, we discuss whether the sign of Coulomb stresses and the distance to the fault have a significant effect on the value of the b-exponent.

Coulomb Coupling Between Quantum Dots and Waveguides

National Research Council Canada - National Science Library

Porod, Wolfgang

2000-01-01

.... We considered both III-V and Si-based semiconductor systems. In later years, the AASERT award supported work on QCA realizations in Coulomb-blockade metal-dot systems, which were successful in demonstrating the basic QCA switching operation...

Coulomb effect in the tri nucleon system in an optical potential model

International Nuclear Information System (INIS)

Adhikari, S.K.; Delfino, A.; Maryland Univ., College Park, MD

1993-02-01

A Saxon-Woods type nucleon-deuteron optical potential in suggested and applied numerically to the study of the static Coulomb effect in the low-energy tri nucleon system. In particular, the observed correlations between the static Coulomb energy of 3 He and the triton binding energy, and that between the neutron-deuteron and the proton-deuteron scattering lengths are simulated with this optical potential. In view of this study and a previous one employing two other effective potentials its is unlikely that a a study of the usual static Coulomb effect in the tri nucleon system will reveal new and meaningful physics. (author). 12 refs, 2 figs

Electron stereodynamics in coulomb explosion of molecules by slow highly charged ions

International Nuclear Information System (INIS)

Ichimura, Atsushi; Ohyama-Yamaguchi, Tomoko

2008-01-01

The three-center Coulombic over-the-barrier model is developed for Coulomb explosion of a homonuclear diatomic molecule in collisions with a slow (∼10 eV/amu) highly charged ion. A conventional two-step picture of multiple electron transfer followed by Coulomb explosion is far from appropriate because the molecule sets out to dissociate before the incident ion approaches the closest distance. We treat the formation of a quasi-molecule and its decay into the three moving atomic ions. Charge-asymmetric population between fragment ions observed in a triple-coincidence measurement is suggested to reflect the bond elongation during a collision. Collisions of Kr 8+ + N 2 are analyzed. (author)

Coulomb Impurity Problem of Graphene in Strong Coupling Regime in Magnetic Fields.

Science.gov (United States)

Kim, S C; Yang, S-R Eric

2015-10-01

We investigate the Coulomb impurity problem of graphene in strong coupling limit in the presence of magnetic fields. When the strength of the Coulomb potential is sufficiently strong the electron of the lowest energy boundstate of the n = 0 Landau level may fall to the center of the potential. To prevent this spurious effect the Coulomb potential must be regularized. The scaling function for the inverse probability density of this state at the center of the impurity potential is computed in the strong coupling regime. The dependence of the computed scaling function on the regularization parameter changes significantly as the strong coupling regime is approached.

Coulomb ionization of inner shells by heavy charged particles

International Nuclear Information System (INIS)

Lapicki, G.

1975-01-01

The theory of inner-shell Coulomb ionization by heavy charged particles, of atomic number small compared to the target atomic number, is developed through the extension of work by Brandt and his coworkers for K shells to L shells. In slow collisions relative to the characteristic times of the inner shell electrons, the quantum-mechanical predictions in the plane-wave Born approximation (PWBA) can exceed experimental cross sections by orders of magnitude. The effects of the perturbation of the atom by and the Coulomb deflection of the particle during collisions are included in the theory. The perturbed atomic states amount to a binding of the inner-shell electrons to the moving particle in slow collisions, and to a polarization of the inner shells by the particle passing at large impact parameters during nonadiabatic collisions. These effects, not contained in the PWBA, are treated in the framework of the perturbed stationary state (PSS) theory for slow collisions and in terms of the harmonic oscillator model of Ashley, Brandt, and Ritchie for stopping powers in fast collisions. The effect of the Coulomb deflection of the particle in the field of the target nucleus on the cross sections is incorporated in the semiclassical approximation of Bang and Hansteen. Except for the lightest target atoms, the contribution of electron capture by the particles to inner-shell ionizations is shown to be negligible. The theory as developed earlier for the K shell, and here for L shells, agrees well with the vast body of experimental data on inner-shell Coulomb ionization by heavy charged particles

Extended Kepler–Coulomb quantum superintegrable systems in three dimensions

International Nuclear Information System (INIS)

Kalnins, E G; Kress, J M; Miller, W Jr

2013-01-01

The quantum Kepler–Coulomb system in three dimensions is well known to be second order superintegrable, with a symmetry algebra that closes polynomially under commutators. This polynomial closure is also typical for second order superintegrable systems in 2D and for second order systems in 3D with nondegenerate (four-parameter) potentials. However, the degenerate three-parameter potential for the 3D Kepler–Coulomb system (also second order superintegrable) is an exception, as its symmetry algebra does not close polynomially. The 3D four-parameter potential for the extended Kepler–Coulomb system is not even second order superintegrable, but Verrier and Evans (2008 J. Math. Phys. 49 022902) showed it was fourth order superintegrable, and Tanoudis and Daskaloyannis (2011 arXiv:11020397v1) showed that, if a second fourth order symmetry is added to the generators, the symmetry algebra closes polynomially. Here, based on the Tremblay, Turbiner and Winternitz construction, we consider an infinite class of quantum extended Kepler–Coulomb three- and four-parameter systems indexed by a pair of rational numbers (k 1 , k 2 ) and reducing to the usual systems when k 1 = k 2 = 1. We show these systems to be superintegrable of arbitrarily high order and determine the structure of their symmetry algebras. We demonstrate that the symmetry algebras close algebraically; only for systems admitting extra discrete symmetries is polynomial closure achieved. Underlying the structure theory is the existence of raising and lowering operators, not themselves symmetry operators or even defined independent of basis, that can be employed to construct the symmetry operators and their structure relations. (paper)

Quasi-exactly solvable relativistic soft-core Coulomb models

Energy Technology Data Exchange (ETDEWEB)

Agboola, Davids, E-mail: davagboola@gmail.com; Zhang, Yao-Zhong, E-mail: yzz@maths.uq.edu.au

2012-09-15

By considering a unified treatment, we present quasi exact polynomial solutions to both the Klein-Gordon and Dirac equations with the family of soft-core Coulomb potentials V{sub q}(r)=-Z/(r{sup q}+{beta}{sup q}){sup 1/q}, Z>0, {beta}>0, q{>=}1. We consider cases q=1 and q=2 and show that both cases are reducible to the same basic ordinary differential equation. A systematic and closed form solution to the basic equation is obtained using the Bethe ansatz method. For each case, the expressions for the energies and the allowed parameters are obtained analytically and the wavefunctions are derived in terms of the roots of a set of Bethe ansatz equations. - Highlights: Black-Right-Pointing-Pointer The relativistic bound-state solutions of the soft-core Coulomb models. Black-Right-Pointing-Pointer Quasi-exact treatments of the Dirac and Klein-Gordon equations for the soft-core Coulomb models. Black-Right-Pointing-Pointer Solutions obtained in terms of the roots to the Bethe ansatz equations. Black-Right-Pointing-Pointer The hidden Lie algebraic structure discussed for the models. Black-Right-Pointing-Pointer Results useful in describing mesonic atoms and interaction of intense laser fields with atom.

Gold Nanoparticles on Functionalized Silicon Substrate under Coulomb Blockade Regime: An Experimental and Theoretical Investigation.

Science.gov (United States)

Pluchery, Olivier; Caillard, Louis; Dollfus, Philippe; Chabal, Yves J

2018-01-18

Single charge electronics offer a way for disruptive technology in nanoelectronics. Coulomb blockade is a realistic way for controlling the electric current through a device with the accuracy of one electron. In such devices the current exhibits a step-like increase upon bias which reflects the discrete nature of the fundamental charge. We have assembled a double tunnel junction on an oxide-free silicon substrate that exhibits Coulomb staircase characteristics using gold nanoparticles (AuNPs) as Coulomb islands. The first tunnel junction is an insulating layer made of a grafted organic monolayer (GOM) developed for this purpose. The GOM also serves for attaching AuNPs covalently. The second tunnel junction is made by the tip of an STM. We show that this device exhibits reproducible Coulomb blockade I-V curves at 40 K in vacuum. We also show that depending on the doping of the silicon substrate, the whole Coulomb staircase can be adjusted. We have developed a simulation approach based on the orthodox theory that was completed by calculating the bias dependent tunnel barriers and by including an accurate calculation of the band bending. This model accounts for the experimental data and the doping dependence of Coulomb oscillations. This study opens new perspectives toward designing new kind of single electron transistors (SET) based on this dependence of the Coulomb staircase with the charge carrier concentration.

Effects of Coulomb repulsion in the inner-shell ionization cross-section by protons, deuterons and alpha-particles

International Nuclear Information System (INIS)

Magno, C.; Milazzo, M.; Pizzi, C.; Porro, F.; Rota, A.; Riccobono, G.

1979-01-01

A critical survey has been made of the currently accepted BEA theory for inner-shell atomic-ionization processes. This review has led to the introduction of an effective ion energy which accounts for the slowing-down of the ion in the nuclear Coulomb field. The effect of the ion deflection, also due to the nuclear Coulomb field, is analyzed. Relativistic effects in the collision of ions with K-shell electrons have been taken into account. A tentative qualitative explanation for the experimentally observed nonexistence of a threshold energy for ionization is given in the framework of the BEA theory. Ionization cross-sections for Rb, Sr, Zr, Cd, In, Sb, W by protons in the energy range from 500 keV to 3 MeV have been measured. Also measurements of ionization cross-sections by deuterons in the energy range from 800 keV to 2.6 MeV on Rb, Sr, Zr, Cd, Sb and by He ions in the energy range from 1.4 MeV to 2.8 MeV on Cd and Sb have been performed. Results are compared with those of other authors and in the context of the corrections introduced in the BEA theory. (author)

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)

Charge-carrier dynamics and Coulomb effects in semiconductor tetrapods

International Nuclear Information System (INIS)

Mauser, Christian

2011-01-01

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

Generalized Coulomb gauge without Gribov ambiguity

Energy Technology Data Exchange (ETDEWEB)

Fachin, S.; Parrinello, C. (New York Univ., NY (United States). Physics Dept.)

1992-05-01

We discuss a global gauge-fixing prescription that is free of the Gribov problem, preserves reflection positivity and contains as a limiting case the (maximal) Coulomb gauge. In such a formalism it is very easy to check that only color singlet states propagate in Euclidean time, for any value of [beta]. (orig.).

Interatomic Coulombic decay in helium nanodroplets

DEFF Research Database (Denmark)

Shcherbinin, Mykola; Laforge, Aaron; Sharma, Vandana

2017-01-01

, or in the droplet interior. ICD at the surface gives rise to energetic He+ ions as previously observed for free He dimers. ICD deeper inside leads to the ejection of slow He+ ions due to Coulomb explosion delayed by elastic collisions with neighboring He atoms, and to the formation of Hek+ complexes....

Trace of a water droplet exerted by coulomb force. 2

International Nuclear Information System (INIS)

Sugita, Hideaki; Murakami, Takuro; Nakazawa, Takeshi; Nakasako, Makoto; Yoshimura, Takuma; Osarakawa, Toshihiro

2002-01-01

The movement of water droplets in the air-water separator is based on the principle of the electrostatic precipitator with positive and negative poles. The mechanism of separation is that the water droplets charged negative ions or electrons by corona discharge are collected on the positive pole by Coulomb force operating between the both poles. This paper describes the theoretical analyses that how the movement of a water droplet is affected by Coulomb force in the air-water separator. (author)

The Singularity Structure of Scale-Invariant Rank-2 Coulomb Branches

OpenAIRE

Argyres, Philip C.; Long, Cody; Martone, Mario

2018-01-01

We compute the spectrum of scaling dimensions of Coulomb branch operators in 4d rank-2 $\\mathcal{N}{=}2$ superconformal field theories. Only a finite rational set of scaling dimensions is allowed. It is determined by using information about the global topology of the locus of metric singularities on the Coulomb branch, the special K\\"ahler geometry near those singularities, and electric-magnetic duality monodromies along orbits of the $\\rm\\, U(1)_R$ symmetry. A set of novel topological and ge...

Proton-/sup 90/Zr interaction at sub-Coulomb proton energies

International Nuclear Information System (INIS)

Laird, C.E.; Flynn, D.; Hershberger, R.L.; Gabbard, F.

1987-01-01

The proton-/sup 90/Zr interaction at sub-Coulomb energies has been investigated in the context of the Lane model, with isospin coupling included, and with alternate decay modes represented with the Hauser-Feshbach model. Scattering and reaction cross sections were accurately measured in order to obtain enough information to constrain the real and absorptive parts of the proton potential. Differential elastic scattering excitation functions were measured at back angles of 135 0 and 165 0 from 2 to 7 MeV, with cross section accuracies of 3%. The energy range was sufficient to go from a region where the backscattering was predominantly Coulomb, enabling additional checks on the cross section accuracies, to a region where the gross structure of the cross sections deviated significantly from Rutherford scattering. Radiative capture cross sections were measured from 1.9 to 5.7 MeV proton energies. The capture cross sections were obtained by summing the measured cross sections for the first two primary gamma rays in addition to some 34 other transitions which terminated on the ground and first excited state. The total inelastic scattering cross section to all /sup 90/Zr excited states (except the first excited state which has been previously measured) was measured at several energies between 3.9 and 5.7 MeV by observing the radiative decay of the residual, excited /sup 90/Zr nuclei. The analysis yielded several model parameters suggestive of large nuclear structure effects. The depth of the absorptive potential was found to vary as W/sub D/ = 2.73+0.70 E/sub p/ in the 2 to 7 MeV proton energy range studied. A real diffuseness of 0.54 fm, significantly smaller than that obtained in neighboring nuclei, was obtained

No evidence of reduced collectivity in Coulomb-excited Sn isotopes

Science.gov (United States)

Kumar, R.; Saxena, M.; Doornenbal, P.; Jhingan, A.; Banerjee, A.; Bhowmik, R. K.; Dutt, S.; Garg, R.; Joshi, C.; Mishra, V.; Napiorkowski, P. J.; Prajapati, S.; Söderström, P.-A.; Kumar, N.; Wollersheim, H.-J.

2017-11-01

In a series of Coulomb excitation experiments the first excited 2+ states in semimagic Sn 112 ,116 ,118 ,120 ,122 ,124 isotopes were excited using a 58Ni beam at safe Coulomb energy. The B (E 2 ; 0+→2+) values were determined with high precision (˜3 %) relative to 58Ni projectile excitation. These results disagree with previously reported B (E 2 ↑) values [A. Jungclaus et al., Phys. Lett. B 695, 110 (2011)., 10.1016/j.physletb.2010.11.012] extracted from Doppler-shift attenuation lifetime measurements, whereas the reported mass dependence of B (E 2 ↑) values is very similar to a recent Coulomb excitation study [J. M. Allmond et al., Phys. Rev. C 92, 041303(R) (2015), 10.1103/PhysRevC.92.041303]. The stable Sn isotopes, key nuclei in nuclear structure, show no evidence of reduced collectivity and we, thus, reconfirm the nonsymmetric behavior of reduced transition probabilities with respect to the midshell A =116 .

Verification of the Rigidity of the Coulomb Field in Motion

Science.gov (United States)

Blinov, S. V.; Bulyzhenkov, I. É.

2018-06-01

Laplace, analyzing the stability of the Solar System, was the first to calculate that the velocity of the motion of force fields can significantly exceed the velocity of light waves. In electrodynamics, the Coulomb field should rigidly accompany its source for instantaneous force action in distant regions. Such rigid motion was recently inferred from experiments at the Frascati Beam Test Facility with short beams of relativistic electrons. The comments of the authors on their observations are at odds with the comments of theoreticians on retarded potentials, which motivates a detailed study of the positions of both sides. Predictions of measurements, based on the Lienard-Wiechert potentials, are used to propose an unambiguous scheme for testing the rigidity of the Coulomb field. Realization of the proposed experimental scheme could independently refute or support the assertions of the Italian physicists regarding the rigid motion of Coulomb fields and likewise the nondual field approach to macroscopic reality.

Coulomb excitation of neutron-deficient polonium isotopes studied at ISOLDE

CERN Document Server

Neven, Michiel

The polonium isotopes represent an interesting region of the nuclear chart having only two protons outside the Z = 82 closed shell. These isotopes have already been extensively studied theoretically and experimentally. The heavier isotopes (A > 200) seem to follow a "regular seniority-type regime" while for the lighter isotopes (A < 200) a more collective behavior is observed. Many questions remain regarding the transition between these two regimes and the configuration mixing between quantum states. Experiments in the lighter polonium isotopes point to the presence of shape coexistence, however the phenomenon is not fully understood. A Coulomb excitation study of the polonium isotopes whereby the dynamic properties are investigated can provide helpful insights in understanding the shape coexistence phenomena. In this thesis $^{202}$Po was studied via Coulomb excitation. The $^{202}$Po isotope was part of an experimental campaign in which the $^{196,198,200,206}$Po isotopes were studied as well via Coulomb...

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.

Singularities of elastic scattering amplitude by long-range potentials

International Nuclear Information System (INIS)

Kvitsinsky, A.A.; Komarov, I.V.; Merkuriev, S.P.

1982-01-01

The angular peculiarities and the zero energy singularities of the elastic scattering amplitude by a long-range potential are described. The singularities of the elastic (2 → 2) scattering amplitude for a system of three Coulomb particles are considered [ru

High-throughput screening of filamentous fungi using nanoliter-range droplet-based microfluidics

Science.gov (United States)

Beneyton, Thomas; Wijaya, I. Putu Mahendra; Postros, Prexilia; Najah, Majdi; Leblond, Pascal; Couvent, Angélique; Mayot, Estelle; Griffiths, Andrew D.; Drevelle, Antoine

2016-06-01

Filamentous fungi are an extremely important source of industrial enzymes because of their capacity to secrete large quantities of proteins. Currently, functional screening of fungi is associated with low throughput and high costs, which severely limits the discovery of novel enzymatic activities and better production strains. Here, we describe a nanoliter-range droplet-based microfluidic system specially adapted for the high-throughput sceening (HTS) of large filamentous fungi libraries for secreted enzyme activities. The platform allowed (i) compartmentalization of single spores in ~10 nl droplets, (ii) germination and mycelium growth and (iii) high-throughput sorting of fungi based on enzymatic activity. A 104 clone UV-mutated library of Aspergillus niger was screened based on α-amylase activity in just 90 minutes. Active clones were enriched 196-fold after a single round of microfluidic HTS. The platform is a powerful tool for the development of new production strains with low cost, space and time footprint and should bring enormous benefit for improving the viability of biotechnological processes.

Structures and Dynamics of Two-Dimensional Dust Lattices with and without Coulomb Molecules in Plasmas

International Nuclear Information System (INIS)

Huang Feng; Wang Xue-Jin; Liu Yan-Hong; Ye Mao-Fu; Wang Long

2010-01-01

Structures and dynamics of two-dimensional dust lattices with and without Coulomb molecules in plasmas are investigated. The experimental results show that the lattices have the crystal-like hexagonal structures, i.e. most particles have six nearest-neighboring particles. However, the lattice points can be occupied by the individual particles or by a pair of particles called Coulomb molecules. The pair correlation function is used to compare the structures between the lattices with or without the Coulomb molecules. In the experiments, the Coulomb molecules can also decompose and recombine with another individual particle to form a new molecule. (physics of gases, plasmas, and electric discharges)

Coulomb excitation of {sup 8}Li

Energy Technology Data Exchange (ETDEWEB)

Assuncao, Marlete; Britos, Tatiane Nassar [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil). Dept. de Ciencias Exatas e da Terra; Descouvemont, Pierre [Universite Libre de Bruxelles (ULB), Brussels (Belgium). Physique Nucleaire Theorique et Physique Mathematique; Lepine-Szily, Alinka; Lichtenthaler Filho, Rubens; Barioni, Adriana; Silva, Diego Medeiros da; Pereira, Dirceu; Mendes Junior, Djalma Rosa; Pires, Kelly Cristina Cezaretto; Gasques, Leandro Romero; Morais, Maria Carmen; Added, Nemitala; Neto Faria, Pedro; Rec, Rafael [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica. Dept. de Fisica Nuclear

2012-07-01

Full text: This work shows the Coulomb Excitation of {sup 8}Li on targets that have effectively behavior of Rutherford in angles and energies of interest for determining the value of the B(E2) electromagnetic transition. Theoretical aspects involved in this type of measure, known as COULEX [1], and some results in the literature [2-3] will be presented. Some problems with the targets and measurement system while performing an experiment on Coulomb Excitation of {sup 8}Li will be discussed: the energy resolution, background, possible contributions of the primary beam and also the excited states of the target near the region of elastic and inelastic peaks. They will be illustrated by measurements of the Coulomb Excitation of {sup 8}Li on targets of {sup 197}Au and {sup 208}Pb using the system RIBRAS(Brazilian Radioactive Ion Beam). In this case, the {sup 8}Li beam(T{sub 1/2} = 838 ms)is produced by {sup 9}Be({sup 7}Li;{sup 8} Li){sup 8}Be reaction from RIBRAS system which is installed at Instituto de Fisica of the Universidade de Sao Paulo. The primary {sup 7L}i beam is provided by Pelletron Accelerator. [1] K. Alder and A. Winther, Electromagnetic Excitation, North-Holland, New York, 1975; [2] P. Descouvemont and D. Baye, Phys. Letts. B 292, 235-238, 1992; [3] J. A. Brown, F. D. Becchetti, J. W. Jaenecke, K, Ashktorab, and D. A. Roberts, J. J. Kolata, R. J. Smith, and K. Lamkin, R. E. Warner, Phys. Rev. Letts., 66, 19, 1991; [4] R. J. Smith, J. J Kolata, K. Lamkin and A. Morsard, F. D. Becchetti, J. A. Brown, W. Z. Liu, J. W. Jaenecke, and D. A. Roberts, R. E. Warner, Phys. Rev. C, 43, 5, 1991. (author)

Coulomb dissociation of {sup 8}B at 254 A MeV

Energy Technology Data Exchange (ETDEWEB)

Suemmerer, K; Boue, F; Baumann, T; Geissel, H; Hellstroem, M; Koczon, P; Schwab, E; Schwab, W; Senger, P; Surowiecz, A [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); Iwasa, N; Ozawa, A [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); [RIKEN Institute of Physical and Chemical Research, Saitama (Japan); Surowka, G [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); [Jagiellonian Univ., Krakow (Poland). Inst. of Physics; Blank, B; Czajkowski, S; Marchand, C; Pravikoff, M S [Centre d` Etudes Nucleaires de Bordeaux-Gradignan, 33 (France); Foerster, A; Lauer, F; Oeschler, H; Speer, J; Sturm, C; Uhlig, F; Wagner, A [Technische Univ. Darmstadt (Germany); Gai, M [Connecticut Univ., Storrs, CT (United States). Dept. of Physics; Grosse, E [Inst. fuer Kern- und Hadronenphysik, Forschungszentrum Rossendorf, Dresden (Germany); Kohlmeyer, B [Philipps Univ., Marburg (Germany). Fachbereich Physik; Kulessa, R; Walus, W [Jagiellonian Univ., Krakow (Poland). Inst. of Physics; Motobayashi, T [Rikkyo Univ., Tokyo (Japan). Dept. of Physics; Teranishi, T [RIKEN Institute of Physical and Chemical Research, Saitama (Japan)

1998-06-01

As an alternative method for determining the astrophysical S-factor for the {sup 7}Be(p,{gamma}){sup 8}B reaction we have measured the Coulomb dissociation of {sup 8}B at 254 A MeV. From our preliminary results, we obtain good agreement with both the accepted direct-reaction measurements and the low-energy Coulomb dissociation study of Iwasa et al. performed at about 50 A MeV. (orig.)

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

International Nuclear Information System (INIS)

Giai, Nguyen Van; Liang, Haozhao; 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 work, we show that the Coulomb exchange effects can be easily included with 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

Coulomb sums for 7Li nucleus at 3-momentum transfers q=1,250...1,625 fm-1

International Nuclear Information System (INIS)

Buki, A.Yu.; Shevchenko, N.G.; Timchenko, I.S.

2009-01-01

The experimental response functions of 7 Li nucleus at effective 3-momentum transfers q = 1.250; 1.375; 1.500 and 1.625 fm -1 are presented. The longitudinal response functions were used to evaluate the Coulomb sum values. The Coulomb sums for 6 Li obtained by us earlier were applied to analyze these data. The Coulomb sums of lithium isotopes were compared with the well-known Coulomb sums values of the other nuclei

Slow Noncollinear Coulomb Scattering in the Vicinity of the Dirac Point in Graphene.

Science.gov (United States)

König-Otto, J C; Mittendorff, M; Winzer, T; Kadi, F; Malic, E; Knorr, A; Berger, C; de Heer, W A; Pashkin, A; Schneider, H; Helm, M; Winnerl, S

2016-08-19

The Coulomb scattering dynamics in graphene in energetic proximity to the Dirac point is investigated by polarization resolved pump-probe spectroscopy and microscopic theory. Collinear Coulomb scattering rapidly thermalizes the carrier distribution in k directions pointing radially away from the Dirac point. Our study reveals, however, that, in almost intrinsic graphene, full thermalization in all directions relying on noncollinear scattering is much slower. For low photon energies, carrier-optical-phonon processes are strongly suppressed and Coulomb mediated noncollinear scattering is remarkably slow, namely on a ps time scale. This effect is very promising for infrared and THz devices based on hot carrier effects.

Questions of quark confinement and ambiguities in Coulomb gauge of Yang-Mills fields

International Nuclear Information System (INIS)

Abarbanel, H.D.I.; Bartels, J.

1978-01-01

The ambiguities considered by Gribov in the formulation of Coulomb gauge in non-Abelian gauge theories are discussed and the division of gauge field space into a sector with a unique transverse gauge, a sector with a two-fold ambiguity in transverse gauge, etc. is reviewed. The authors argue in a semi-classical fashion that transitions between these sectors readily occur and discuss the connection with ideas of quark confinement in Coulomb gauge. Because of these transitions it appears that the functional integral formulation of Coulomb gauge will be rather more complicated than expected in the past. (Auth.)

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...

Exact inclusion of the Coulomb field in the photobeta decay of a nucleus and problem of bypassed elements

International Nuclear Information System (INIS)

Kopytin, I.V.; Karelin, K.N.; Nekipelov, A.A.

2004-01-01

The probability of the endothermic β - decay of nuclei that is stimulated by an electromagnetic field of Planck frequency spectrum (photobeta decay) is calculated, the effect of the Coulomb field on a relativistic electron and a virtual relativistic positron being exactly taken into account in this calculation. It is shown that the inclusion of Coulomb effects is of paramount importance and that the results of the calculations may differ by an order of magnitude from those that were obtained previously in the plane-wave approximation, depending on the energy range being considered. A model for the synthesis of bypassed elements in the interior of massive stars is proposed on the basis of the mechanism of the photobeta decay of stable elements that originate from s and r processes

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)

Effect of increasing disorder on domains of the 2d Coulomb glass.

Science.gov (United States)

Bhandari, Preeti; Malik, Vikas

2017-12-06

We have studied a two dimensional lattice model of Coulomb glass for a wide range of disorders at [Formula: see text]. The system was first annealed using Monte Carlo simulation. Further minimization of the total energy of the system was done using an algorithm developed by Baranovskii et al, followed by cluster flipping to obtain the pseudo-ground states. We have shown that the energy required to create a domain of linear size L in d dimensions is proportional to [Formula: see text]. Using Imry-Ma arguments given for random field Ising model, one gets critical dimension [Formula: see text] for Coulomb glass. The investigation of domains in the transition region shows a discontinuity in staggered magnetization which is an indication of a first-order type transition from charge-ordered phase to disordered phase. The structure and nature of random field fluctuations of the second largest domain in Coulomb glass are inconsistent with the assumptions of Imry and Ma, as was also reported for random field Ising model. The study of domains showed that in the transition region there were mostly two large domains, and that as disorder was increased the two large domains remained, but a large number of small domains also opened up. We have also studied the properties of the second largest domain as a function of disorder. We furthermore analysed the effect of disorder on the density of states, and showed a transition from hard gap at low disorders to a soft gap at higher disorders. At [Formula: see text], we have analysed the soft gap in detail, and found that the density of states deviates slightly ([Formula: see text]) from the linear behaviour in two dimensions. Analysis of local minima show that the pseudo-ground states have similar structure.

Hamiltonian approach to 1 + 1 dimensional Yang-Mills theory in Coulomb gauge

International Nuclear Information System (INIS)

Reinhardt, H.; Schleifenbaum, W.

2009-01-01

We study the Hamiltonian approach to 1 + 1 dimensional Yang-Mills theory in Coulomb gauge, considering both the pure Coulomb gauge and the gauge where in addition the remaining constant gauge field is restricted to the Cartan algebra. We evaluate the corresponding Faddeev-Popov determinants, resolve Gauss' law and derive the Hamiltonians, which differ in both gauges due to additional zero modes of the Faddeev-Popov kernel in the pure Coulomb gauge. By Gauss' law the zero modes of the Faddeev-Popov kernel constrain the physical wave functionals to zero colour charge states. We solve the Schroedinger equation in the pure Coulomb gauge and determine the vacuum wave functional. The gluon and ghost propagators and the static colour Coulomb potential are calculated in the first Gribov region as well as in the fundamental modular region, and Gribov copy effects are studied. We explicitly demonstrate that the Dyson-Schwinger equations do not specify the Gribov region while the propagators and vertices do depend on the Gribov region chosen. In this sense, the Dyson-Schwinger equations alone do not provide the full non-abelian quantum gauge theory, but subsidiary conditions must be required. Implications of Gribov copy effects for lattice calculations of the infrared behaviour of gauge-fixed propagators are discussed. We compute the ghost-gluon vertex and provide a sensible truncation of Dyson-Schwinger equations. Approximations of the variational approach to the 3 + 1 dimensional theory are checked by comparison to the 1 + 1 dimensional case

Investigation of scattering processes in quantum few-body systems involving long-range interaction by the complex-rotation method

International Nuclear Information System (INIS)

Volkov, M. V.; Elander, N.; Yakovlev, S. L.; Yarevsky, E. A.

2013-01-01

The complex-rotation method adapted to solving the multichannel scattering problem in the two-body system where the interaction potential contains the long-range Coulomb components is described. The scattering problem is reformulated as the problem of solving a nonhomogeneous Schrödinger equation in which the nonhomogeneous term involves a Coulomb potential cut off at large distances. The incident wave appearing in the nonhomogeneous term is a solution of the Schrödinger equation with longrange Coulomb interaction. This formulation is free from approximations associated with a direct cutoff of Coulomb interaction at large distances. The efficiency of this formalism is demonstrated by considering the example of solving scattering problems in the α-α and p-p systems.

Coulomb corrections for interferometry analysis of expanding hadron systems

Energy Technology Data Exchange (ETDEWEB)

Sinyukov, Yu.M. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees]|[Institute for Theoretical Physics of National Acad. Sci., Kiev (Ukraine); Lednicky, R. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees]|[Institute of Physics, Prague (Czech Republic); Akkelin, S.V. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Teoreticheskoj Fiziki; Pluta, J. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees]|[Warsaw Univ. (Poland). Inst. of Physics; Erazmus, B. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees

1998-10-01

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 volumes predicted in the realistic evolution scenarios taking into account the collective flows. A simple modification of the standard zero-distance correction (so called Gamow or Coulomb factor) has been proposed for such a kind of systems. For {pi}{sup +}{pi}{sup +} and K{sup +}K{sup +} correlation functions this approximate analytical approach is compared with the exact numerical results and a good agreement is found for typical conditions at SPS, RHIC and even LHC energies. (author) 21 refs.

Negative differential resistance in nanoscale transport in the Coulomb blockade regime

International Nuclear Information System (INIS)

Parida, Prakash; Lakshmi, S; Pati, Swapan K

2009-01-01

Motivated by recent experiments, we have studied the transport behavior of coupled quantum dot systems in the Coulomb blockade regime using the master (rate) equation approach. We explore how electron-electron interactions in a donor-acceptor system, resembling weakly coupled quantum dots with varying charging energy, can modify the system's response to an external bias, taking it from normal Coulomb blockade behavior to negative differential resistance (NDR) in the current-voltage characteristics.

KLEIN: Coulomb functions for real lambda and positive energy to high accuracy

International Nuclear Information System (INIS)

Barnett, A.R.

1981-01-01

KLEIN computes relativistic Schroedinger (Klein-Gordon) equation solutions, i.e. Coulomb functions for real lambda > - 1, Fsub(lambda)(eta,x), Gsub(lambda)(eta,x), F'sub(lambda)(eta,x) and G'sub(lambda)(eta,x) for real kappa > 0 and real eta, - 10 4 4 . Hence it is also suitable for Bessel and spherical Bessel functions. Accuracies are in the range 10 -14 -10 -16 in oscillating region, and approx. equal to 10 -30 on an extended precision compiler. The program is suitable for generating Klein-Gordon wavefunctions for matching in pion and kaon physics. (orig.)

Coulomb blockade threshold in finite one-dimensional arrays of small tunnel junctions

International Nuclear Information System (INIS)

Lien, Nguyen V.; Dat, Nguyen T.; Nam, Nguyen H.

2001-11-01

The current-voltage characteristics of one-dimensional tunnel junction arrays are simulated using the semiclassical and full capacitance matrix description. The threshold voltage V th of the Coulomb blockade (CB) is evaluated and analyzed in detail as a function of the gate capacitance C 0 , the array length N, the temperature, and the degree of disorder. The disordered effect is found to be essential, while the long range interaction included in the full capacitance matrix calculations, when decreasing V th , weakly affects the qualitative behaviour of the CB for the V th (C 0 ) - and the V th (N)-dependences. (author)

The role played by the Coulombic traction for an interface crack in dissimilar piezoelectric materials

International Nuclear Information System (INIS)

Li Qun; Chen Yiheng

2008-01-01

The role played by the Coulombic traction for an interface crack in dissimilar piezoelectric materials is clarified. Based on the extended Stroh theory, the Coulombic traction, usually neglected in piezoelectric fracture, is imposed on the interface crack surfaces. It is found that the low-capacitance medium (air or vacuum) inside the crack gap yields some large Coulombic traction as compared to the applied mechanical loading whether the remanent polarization of piezoelectric material is considered or not. Thus, previous investigations based on the traction-free condition underestimate the role of the Coulombic traction and in turn may yield unexpected errors for the effective stress intensity factor (SIF) and energy release rate (ERR) at the crack tip. (technical note)

Coulomb fission in dielectric dication clusters: experiment and theory on steps that may underpin the electrospray mechanism.

Science.gov (United States)

Chen, Xiaojing; Bichoutskaia, Elena; Stace, Anthony J

2013-05-16

A series of five molecular dication clusters, (H2O)n(2+), (NH3)n(2+), (CH3CN)n(2+), (C5H5N)n(2+), and (C6H6)n(2+), have been studied for the purpose of identifying patterns of behavior close to the Rayleigh instability limit where the clusters might be expected to exhibit Coulomb fission. Experiments show that the instability limit for each dication covers a range of sizes and that on a time scale of 10(-4) s ions close to the limit can undergo either Coulomb fission or neutral evaporation. The observed fission pathways exhibit considerable asymmetry in the sizes of the charged fragments, and are associated with kinetic (ejection) energies of ~0.9 eV. Coulomb fission has been modeled using a theory recently formulated to describe how charged particles of dielectric materials interact with one another (Bichoutskaia et al. J. Chem. Phys. 2010, 133, 024105). The calculated electrostatic interaction energy between separating fragments accounts for the observed asymmetric fragmentation and for the magnitudes of the measured ejection energies. The close match between theory and experiment suggests that a significant fraction of excess charge resides on the surfaces of the fragment ions. The experiments provided support for a fundamental step in the electrospray ionization (ESI) mechanism, namely the ejection from droplets of small solvated charge carriers. At the same time, the theory shows how water and acetonitrile may behave slightly differently as ESI solvents. However, the theory also reveals deficiencies in the point-charge image-charge model that has previously been used to quantify Coulomb fission in the electrospray process.

A Coulomb collision algorithm for weighted particle simulations

Science.gov (United States)

Miller, Ronald H.; Combi, Michael R.

1994-01-01

A binary Coulomb collision algorithm is developed for weighted particle simulations employing Monte Carlo techniques. Charged particles within a given spatial grid cell are pair-wise scattered, explicitly conserving momentum and implicitly conserving energy. A similar algorithm developed by Takizuka and Abe (1977) conserves momentum and energy provided the particles are unweighted (each particle representing equal fractions of the total particle density). If applied as is to simulations incorporating weighted particles, the plasma temperatures equilibrate to an incorrect temperature, as compared to theory. Using the appropriate pairing statistics, a Coulomb collision algorithm is developed for weighted particles. The algorithm conserves energy and momentum and produces the appropriate relaxation time scales as compared to theoretical predictions. Such an algorithm is necessary for future work studying self-consistent multi-species kinetic transport.

Generalized second-order Coulomb phase shift functions

International Nuclear Information System (INIS)

Rosendorff, S.

1982-01-01

Some specific properties and the evaluation of the generalized second-order Coulomb phase shift functions (two-dimensional integrals of four spherical cylinder functions) are discussed. The dependence on the three momenta k 1 ,k-bar,k 2 , corresponding to the final, intermediate, and initial states is illustrated

Chaos in a coulombic muffin-tin potential

International Nuclear Information System (INIS)

Brandis, S.

1994-04-01

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.)

Coulomb scatter of diamagnetic dust particles in a cusp magnetic trap under microgravity conditions

Energy Technology Data Exchange (ETDEWEB)

Myasnikov, M. I., E-mail: miasnikovmi@mail.ru; D’yachkov, L. G.; Petrov, O. F.; Vasiliev, M. M., E-mail: mixxy@mail.ru; Fortov, V. E. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Savin, S. F.; Serova, E. O. [Korolev Rocket and Space Corporation Energia, ul. Lenina 4A (Russian Federation)

2017-02-15

The effect of a dc electric field on strongly nonideal Coulomb systems consisting of a large number (~10{sup 4}) of charged diamagnetic dust particles in a cusp magnetic trap are carried out aboard the Russian segment of the International Space Station (ISS) within the Coulomb Crystal experiment. Graphite particles of 100–400 μm in size are used in the experiments. Coulomb scatter of a dust cluster and the formation of threadlike chains of dust particles are observed experimentally. The processes observed are simulated by the molecular dynamics (MD) method.

Impact of electron-electron Coulomb interaction on the high harmonic generation process in graphene

Science.gov (United States)

Avetissian, H. K.; Mkrtchian, G. F.

2018-03-01

Generation of high harmonics in a monolayer graphene initiated by a strong coherent radiation field, taking into account electron-electron Coulomb interaction, is investigated. A microscopic theory describing the nonlinear optical response of graphene is developed. The Coulomb interaction of electrons is treated in the scope of dynamic Hartree-Fock approximation. The closed set of integrodifferential equations for the single-particle density matrix of a graphene quantum structure is solved numerically. The obtained solutions show the significance of many-body Coulomb interaction on the high harmonic generation process in graphene.

Laser-Driven Recollisions under the Coulomb Barrier.

Science.gov (United States)

Keil, Th; Popruzhenko, S V; Bauer, D

2016-12-09

Photoelectron spectra obtained from the ab initio solution of the time-dependent Schrödinger equation can be in striking disagreement with predictions by the strong-field approximation (SFA), not only at low energy but also around twice the ponderomotive energy where the transition from the direct to the rescattered electrons is expected. In fact, the relative enhancement of the ionization probability compared to the SFA in this regime can be several orders of magnitude. We show for which laser and target parameters such an enhancement occurs and for which the SFA prediction is qualitatively good. The enhancement is analyzed in terms of the Coulomb-corrected action along analytic quantum orbits in the complex-time plane, taking soft recollisions under the Coulomb barrier into account. These recollisions in complex time and space prevent a separation into sub-barrier motion up to the "tunnel exit" and subsequent classical dynamics. Instead, the entire quantum path up to the detector determines the ionization probability.

Analytical evaluation of integrals over Coulomb wave functions

International Nuclear Information System (INIS)

Nesbet, R.K.

1988-01-01

Indefinite integrals of products of Coulomb wave functions over the interval (r, ∞) can be evaluated by conversion to continued fractions. Examples are given of normalization and dipole transition integrals required in photoionization calculations. (orig.)

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.

Heavy ion collisions at energies near the Coulomb barrier 1990

International Nuclear Information System (INIS)

Nagarajan, M.A.

1991-01-01

During recent years, detailed experimental and theoretical investigations have been carried out on heavy ion collisions at energies close to the Coulomb barrier. These studies have provided direct evidence of strong couplings between the various reaction channels available at energies near the top of the Coulomb barrier. This field of research has remained the focus of interest and with improved experimental techniques, new detailed high resolution data have been obtained. The workshop on ''Heavy Ion Collisions at Energies Close to the Coulomb Barrier'' was organized with the aim of reviewing the current understanding of the collision dynamics and to discuss future directions in this area of research. The topics discussed at the workshop were broadly classified under the titles: quasielastic reactions; fusion of heavy ions; and shape and spin dependence in heavy ion collisions. The last of these topics was included to review new data obtained with polarized heavy ions and their theoretical interpretations. This volume contains the invited and contributed talks as well as a few short presentations during panel discussions. (author)

Prospects for coherently driven nuclear radiation by Coulomb excitation

International Nuclear Information System (INIS)

Karamyan, S.A.; Carroll, J.J.

2006-01-01

Possible experiments are discussed in which the Coulomb excitation of nuclear isomers would be followed by sequential energy release. The possibility of the coherent Coulomb excitation of nuclei ensconced in a crystal by channeled relativistic heavy projectiles is considered. The phase shift between neighbor-nuclei excitations can be identical to the photon phase shift for emission in forward direction. Thus, the elementary string of atoms can radiate coherently with emission of characteristic nuclear γ rays and the intensity of the radiation could be increased due to the summation of amplitudes. The Moessbauer conditions should be important for this new type of collective radiation that could be promising in the context of the γ-lasing problem

Is the ground state of Yang-Mills theory Coulombic?

Science.gov (United States)

Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; Lutz, W.; McMullan, D.

2008-08-01

We study trial states modelling the heavy quark-antiquark ground state in SU(2) Yang-Mills theory. A state describing the flux tube between quarks as a thin string of glue is found to be a poor description of the continuum ground state; the infinitesimal thickness of the string leads to UV artifacts which suppress the overlap with the ground state. Contrastingly, a state which surrounds the quarks with non-Abelian Coulomb fields is found to have a good overlap with the ground state for all charge separations. In fact, the overlap increases as the lattice regulator is removed. This opens up the possibility that the Coulomb state is the true ground state in the continuum limit.

Coulomb excitations for a short linear chain of metallic shells

Energy Technology Data Exchange (ETDEWEB)

Zhemchuzhna, Liubov, E-mail: lzhemchuzhna@unm.edu [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Gumbs, Godfrey [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Donostia International Physics Center (DIPC), P de Manuel Lardizabal, 4, 20018 San Sebastian, Basque Country (Spain); Iurov, Andrii [Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Huang, Danhong [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Gao, Bo [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States)

2015-03-15

A self-consistent-field theory is given for the electronic collective modes of a chain containing a finite number, N, of Coulomb-coupled spherical two-dimensional electron gases arranged with their centers along a straight line, for simulating electromagnetic response of a narrow-ribbon of metallic shells. The separation between nearest-neighbor shells is arbitrary and because of the quantization of the electron energy levels due to their confinement to the spherical surface, all angular momenta L of the Coulomb excitations, as well as their projections M on the quantization axis, are coupled. However, for incoming light with a given polarization, only one angular momentum quantum number is usually required. Therefore, the electromagnetic response of the narrow-ribbon of metallic shells is expected to be controlled externally by selecting different polarizations for incident light. We show that, when N = 3, the next-nearest-neighbor Coulomb coupling is larger than its value if they are located at opposite ends of a right-angle triangle forming the triad. Additionally, the frequencies of the plasma excitations are found to depend on the orientation of the line joining them with respect to the axis of quantization since the magnetic field generated from the induced oscillating electric dipole moment on one sphere can couple to the induced magnetic dipole moment on another. Although the transverse inter-shell electromagnetic coupling can be modeled by an effective dynamic medium, the longitudinal inter-shell Coulomb coupling, on the other hand, can still significantly modify the electromagnetic property of this effective medium between shells.

Influence of the Coulomb interaction on the exchange coupling in granular magnets.

Science.gov (United States)

Udalov, O G; Beloborodov, I S

2017-04-20

We develop a theory of the exchange interaction between ferromagnetic (FM) metallic grains embedded into insulating matrix by taking into account the Coulomb blockade effects. For bulk ferromagnets separated by the insulating layer the exchange interaction strongly depends on the height and thickness of the tunneling barrier created by the insulator. We show that for FM grains embedded into insulating matrix the exchange coupling additionally depends on the dielectric properties of this matrix due to the Coulomb blockade effects. In particular, the FM coupling decreases with decreasing the dielectric permittivity of insulating matrix. We find that the change in the exchange interaction due to the Coulomb blockade effects can be a few tens of percent. Also, we study dependence of the intergrain exchange interaction on the grain size and other parameters of the system.

Impact of density-dependent symmetry energy and Coulomb ...

Indian Academy of Sciences (India)

2014-03-07

Mar 7, 2014 ... The IMF production increases with the stiffness of symmetry energy. .... to clusterization using minimum spanning tree MST(M) method .... To understand the direct role of Coulomb interactions, we display in figure 4 the mean.

Coulomb displacement energies of the T=1, J=0 states of A=42 nuclei

International Nuclear Information System (INIS)

Sato, H.

1978-01-01

Coulomb displacement energies of the T=1, J=0 + and 6 1 + states of A=42 nuclei are analyzed with previously known charge dependent forces and effects, and with the available Hartree-Fock single-particle wave functions. From the study of the Coulomb displacement energies of the 6 1 + states it is found that the present knowledge on the charge dependence, including a phenomenological charge symmetry breaking force previously introduced so as to help explain the Nolen-Schiffer anomaly, gives a sufficient and consistent explanation for both single-particle and two-particle systems. From the study of the 0 + states, it is found that the Coulomb displacement energies of the second 0 2 + states can be explained with a compensation between the smaller Coulomb energies of the second lowest two-particle state and larger ones of the deformed 4p-2h state. (Auth.)

Coulomb excitation of the proton-dripline nucleus Na20

Science.gov (United States)

Schumaker, M. A.; Cline, D.; Hackman, G.; Pearson, C. J.; Svensson, C. E.; Wu, C. Y.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Buchmann, L.; Churchman, R.; Cifarelli, F.; Cooper, R. J.; Cross, D. S.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Drake, T. E.; Finlay, P.; Gallant, A. T.; Garrett, P. E.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Lisetskiy, A. F.; Leach, K. G.; Lee, G.; Maharaj, R.; Martin, J.-P.; Moisan, F.; Morton, A. C.; Mythili, S.; Nelson, L.; Newman, O.; Nolan, P. J.; Orce, J. N.; Padilla-Rodal, E.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Roy, R.; Ruiz, C.; Sarazin, F.; Scraggs, D. P.; Waddington, J. C.; Wan, J. M.; Whitbeck, A.; Williams, S. J.; Wong, J.

2009-10-01

The low-energy structure of the proton dripline nucleus Na20 has been studied using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. A 1.7-MeV/nucleon Na20 beam of ~5×106 ions/s was Coulomb excited by a 0.5-mg/cm2natTi target. Scattered beam and target particles were detected by the BAMBINO segmented Si detector while γ rays were detected by two TIGRESS HPGe clover detectors set perpendicular to the beam axis. Coulomb excitation from the 2+ ground state to the first excited 3+ and 4+ states was observed, and B(λL) values were determined using the 2+→0+ de-excitation in Ti48 as a reference. The resulting B(λL)↓ values are B(E2;3+→2+)=55±6e2fm4 (17.0±1.9 W.u.), B(E2;4+→2+)=35.7±5.7e2fm4 (11.1±1.8 W.u.), and B(M1;4+→3+)=0.154±0.030μN2 (0.086±0.017 W.u.). These measurements provide the first experimental determination of B(λL) values for this proton dripline nucleus of astrophysical interest.

Study on scalable Coulombic degradation for estimating the lifetime of organic light-emitting devices

International Nuclear Information System (INIS)

Zhang Wenwen; Hou Xun; Wu Zhaoxin; Liang Shixiong; Jiao Bo; Zhang Xinwen; Wang Dawei; Chen Zhijian; Gong Qihuang

2011-01-01

The luminance decays of organic light-emitting diodes (OLEDs) are investigated with initial luminance of 1000 to 20 000 cd m -2 through a scalable Coulombic degradation and a stretched exponential decay. We found that the estimated lifetime by scalable Coulombic degradation deviates from the experimental results when the OLEDs work with high initial luminance. By measuring the temperature of the device during degradation, we found that the higher device temperatures will lead to instabilities of organic materials in devices, which is expected to result in the difference between the experimental results and estimation using the scalable Coulombic degradation.

Coulomb-nuclear interference measurements of hexadecapole deformations in 168Yb and 178,180Hf

International Nuclear Information System (INIS)

Nettles, W.G.; Mississippi Coll., Clinton; Ramayya, A.V.; Hamilton, J.H.

1988-01-01

Coulomb-nuclear interference studies of 168 Yb and 178,180 Hf have been carried out with alpha particles from the Pittsburgh tandem. From coupled channel fits to the data at 18 MeV for 168 Yb and 19.5 MeV for 178,180 Hf, β 4 c values of -0.030(20), -0.166(18), and -0.180(6) were obtained, respectively. These data agree with the positive M 04 value from sub-Coulomb studies of 168 Yb but with the large negative M 04 values from sub-Coulomb studies of 178,180 Hf. (author)

Use of the Coulomb excitation by light and heavy ions for quantitative analysis

International Nuclear Information System (INIS)

Craciun, L.; Racolta, P. M.; Tripadus, V.; Dragulescu, E.; Serbanut, C.

2001-01-01

nuclei; b) Coulomb excitation for incident energies below the Coulomb barrier; here the excitations of the nucleus by the interaction of its Coulomb field with that of the bombarding nucleus is a purely electromagnetic process. In the first stage of this project, the theoretical considerations and their consequences for analytical possibilities will be considered. The overwhelming majority of the excitations in the Coulomb excitation are the electric quadrupole transitions (E2). All particularities of this type of transitions will be evaluated. A dedicated beam line with the target chamber and spectrometric setups has been realized and experimented, in order to compete with European standards. The experimental thick-target yields and detection limits for 20 elements in many matrices will be analyzed. Coulomb excitation by different charged particles, like p, 9 Be, 11 B, 14 N, 35 Cl will be investigated. - A special attention will be allocated for CE by heavy ions ( 35 Cl, 55 MeV). For this quantitative analysis, because of the energy range, the used formulae from the Bethe equation for stopping power cannot be applied and then we propose a new methodology after the actual programs; - To test the validity of our approximation, some standard samples from the 'Bureau Communautaire de Reference' in Brussels will be used. The heavy-ion beams will be produced at the IFIN-HH Tandem, 8 MV on terminal. (authors)

Features of non-congruent phase transition in modified Coulomb model of the binary ionic mixture

International Nuclear Information System (INIS)

Stroev, N E; Iosilevskiy, I L

2016-01-01

Non-congruent gas-liquid phase transition (NCPT) have been studied previously in modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a uniformly compressible ideal electronic background /BIM(∼)/. The features of NCPT in improved version of the BIM(∼) model for the same mixture on background of non-ideal electronic Fermi-gas and comparison it with the previous calculations are the subject of present study. Analytical fits for Coulomb corrections to equation of state 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 were calculated on the entire range of proportions of mixed ions 0 < X < 1. Strong “distillation” effect was found for NCPT in the present BIM(∼) model. Just similar distillation was obtained in the variant of NCPT in dense nuslear matter. The absence of azeotropic compositions was revealed in studied variants of BIM(∼) in contrast to an explicit existence of the azeotropic compositions for the NCPT in chemically reacting plasmas and in astrophysical applications. (paper)

Features of non-congruent phase transition in modified Coulomb model of the binary ionic mixture

Science.gov (United States)

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

2016-11-01

Non-congruent gas-liquid phase transition (NCPT) have been studied previously in modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a uniformly compressible ideal electronic background /BIM(∼)/. The features of NCPT in improved version of the BIM(∼) model for the same mixture on background of non-ideal electronic Fermi-gas and comparison it with the previous calculations are the subject of present study. Analytical fits for Coulomb corrections to equation of state 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 were calculated on the entire range of proportions of mixed ions 0 distillation” effect was found for NCPT in the present BIM(∼) model. Just similar distillation was obtained in the variant of NCPT in dense nuslear matter. The absence of azeotropic compositions was revealed in studied variants of BIM(∼) in contrast to an explicit existence of the azeotropic compositions for the NCPT in chemically reacting plasmas and in astrophysical applications.

Quasineutral Limit of the Schrödinger-Poisson System in Coulomb Gauge

OpenAIRE

Lin, Chi-Kun; Wong, Yau-Shu; Wu, Kung-Chien

2012-01-01

The zero Debye length asymptotic of the Schrödinger-Poisson system in Coulomb gauge for ill-prepared initial data is studied. We prove that when the scaled Debye length λ → 0, the current density defined by the solution of the Schrödinger-Poisson system in the Coulomb gauge converges to the solution of the rotating incompressible Euler equation plus a fast singular oscillating gradient vector field.

On analytical solutions to the problem of the Coulomb and confining potentials

International Nuclear Information System (INIS)

Dineykhan, M.; Nazmitdinov, R.G.

1997-01-01

The oscillator representation method is presented and applied to calculate the energy spectrum of the superposition of the Coulomb and the power-law potentials, the Coulomb and the Yukawa potentials. The method provides an efficient way to obtain analytical results for arbitrary set of parameters of the considered potentials. The energies of ground and excited states of a quantum system are in good agreement with the exact results

Simulation of Coulomb interaction effects in electron sources

International Nuclear Information System (INIS)

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

2011-01-01

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.

Coulomb excitation of atoms by fast multicharged ions

International Nuclear Information System (INIS)

Yudin, G.L.

1980-01-01

Investigated is coulomb eXcitation of discrete levels of a hydrogen-like atom by a fast multicharged ion. Obtained are dependences of probabilities of channels 1S→nS and 1S→nP on the sight parameter in the zero order of sudden excitation theory. 1S-2S transition is considered in detail. Carried out are calculations for excitation of the hydrogen atom by the wholy bare carbon atom. It is shown, that at low values of excitation pr.ocess parameter eta excitation probability is a monotonously decreasing function of the impact parameter. With the growth of eta the situation is changed, and at low impact parameters the probability of 1S-2S transition is decreased. At high impact parameters approximation of sudden excitations is unacceptable, here lagging of coulomb interaction is essential

Coulomb displacement energies in relativistic and non-relativistic self-consistent models

International Nuclear Information System (INIS)

Marcos, S.; Savushkin, L.N.; Giai, N. van.

1992-03-01

Coulomb displacement energies in mirror nuclei are comparatively analyzed in Dirac-Hartree and Skyrme-Hartree-Fock models. Using a non-linear effective Lagrangian fitted on ground state properties of finite nuclei, it is found that the predictions of relativistic models are lower than those of Hartree-Fock calculations with Skyrme force. The main sources of reduction are the kinetic energy and the Coulomb-nuclear interference potential. The discrepancy with the data is larger than in the Skyrme-Hartree-Fock case. (author) 24 refs., 3 tabs

Scaling laws governing the multiple scattering of diatomic molecules under Coulomb explosion

International Nuclear Information System (INIS)

Sigmund, P.

1992-01-01

The trajectories of fast molecules during and after penetration through foils are governed by Coulomb explosion and distorted by multiple scattering and other penetration phenomena. A scattering event may cause the energy available for Coulomb explosion to increase or decrease, and angular momentum may be transferred to the molecule. Because of continuing Coulomb explosion inside and outside the target foil, the transmission pattern recorded at a detector far away from the target is not just a linear superposition of Coulomb explosion and multiple scattering. The velocity distribution of an initially monochromatic and well-collimated, but randomly oriented, beam of molecular ions is governed by a generalization of the standard Bothe-Landau integral that governs the multiple scattering of atomic ions. Emphasis has been laid on the distribution in relative velocity and, in particular, relative energy. The statistical distributions governing the longitudinal motion (i.e., the relative motion along the molecular axis) and the rotational motion can be scaled into standard multiple-scattering distributions of atomic ions. The two scaling laws are very different. For thin target foils, the significance of rotational energy transfer is enhanced by an order of magnitude compared to switched-off Coulomb explosion. A distribution for the total relative energy (i.e., longitudinal plus rotational motion) has also been found, but its scaling behavior is more complex. Explicit examples given for all three distributions refer to power-law scattering. As a first approximation, scattering events undergone by the two atoms in the molecule were assumed uncorrelated. A separate section has been devoted to an estimate of the effect of impact-parameter correlation on the multiple scattering of penetrating molecules

Intensity dependent absorption bleaching of high subband excitons in GaAs/AlGaAs multiple quantum wells

CERN Document Server

Shin, S H; Lee, E H; Chae, K M; Park, S H; Kim, U

1998-01-01

We have investigated the influence of carrier generation on the absorption bleaching of the n=2 and n=3 excitons in GaAs/AlGaAs multiple quantum wells (MQWs). With the excitation near the resonance of the n=1 exciton absorption, the long range coulomb screening and collision broadening had significant effects on the exciton bleaching. At low excitation intensity, the absorption bleaching of the n=2 exciton in 75 A-thick MQWs and that of the n=3 exciton in 150 A-thick MQWs were due to linewidth broadening by the collision broadening effect only. At high excitation intensity, however, the reduction of oscillator strength due to the long range coulomb screening contributed dominantly to absorption bleaching.

The influence of the s-d(f) Coulomb interaction on the transition element compound superconductive critical temperature

International Nuclear Information System (INIS)

Kravtsov, V.E.; Mal'shukov, A.G.

1978-01-01

The influence of s-d Coulomb interaction on the superconductive critical temperature Tsub(c) of transition element compounds and their dilute alloys was investigated in the frame of Anderson model. Coulomb interaction of electrons with opposite spins on the same atom was considered in a ladder approximation valid when hybridization is sufficiently small while s-d Coulomb interaction has led to the 'parquet' summation. It is shown that s-d Coulomb interaction results in the decrease of Tsub(c) and hence the electron mechanism of superconductivity seems to be non-effective in systems under consideration. (author)

Imaging of Coulomb-Driven Quantum Hall Edge States

KAUST Repository

Lai, Keji; Kundhikanjana, Worasom; Kelly, Michael A.; Shen, Zhi-Xun; Shabani, Javad; Shayegan, Mansour

2011-01-01

The edges of a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime are divided into alternating metallic and insulating strips, with their widths determined by the energy gaps of the QHE states and the electrostatic Coulomb

Coulomb drag in multiwall armchair carbon nanotubes

DEFF Research Database (Denmark)

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

2004-01-01

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...

Single-photon Coulomb explosion of methanol using broad bandwidth ultrafast EUV pulses.

Science.gov (United States)

Luzon, Itamar; Jagtap, Krishna; Livshits, Ester; Lioubashevski, Oleg; Baer, Roi; Strasser, Daniel

2017-05-31

Single-photon Coulomb explosion of methanol is instigated using the broad bandwidth pulse achieved through high-order harmonics generation. Using 3D coincidence fragment imaging of one molecule at a time, the kinetic energy release (KER) and angular distributions of the products are measured in different Coulomb explosion (CE) channels. Two-body CE channels breaking either the C-O or the C-H bonds are described as well as a proton migration channel forming H 2 O + , which is shown to exhibit higher KER. The results are compared to intense-field Coulomb explosion measurements in the literature. The interpretation of broad bandwidth single-photon CE data is discussed and supported by ab initio calculations of the predominant C-O bond breaking CE channel. We discuss the importance of these findings for achieving time resolved imaging of ultrafast dynamics.

Electric and Magnetic Coulomb Potentials in the Deuteron

Directory of Open Access Journals (Sweden)

Bernard Schaeffer

2013-09-01

Full Text Available After one century of nuclear physics, the underlying fun- damental laws of nuclear physics are still missing. Bohr had found a formula for the H atom and another for the H2 molecule but no equivalent formula exists for the deuteron 2H. The only known Coulomb interaction in a nucleus by the mainstream nuclear physics is the long range repulsion between protons, forgetting that the neutron contains elec- tric charges with no net charge. The neutron is attracted by the proton in a way discovered two millenaries ago by the Greeks. This attraction is equilibrated by the repulsion between the opposite magnetic moments of the proton and of the neutron in the deuteron. The bare application of ge- ometry together with electric and magnetic Coulomb’s in- teractions accounts for the binding energy of the deuteron, without fitting, with only 4 per cent discrepancy, proving the electromagnetic nature of the nuclear energy.

Short-range second order screened exchange correction to RPA correlation energies

Science.gov (United States)

Beuerle, Matthias; Ochsenfeld, Christian

2017-11-01

Direct random phase approximation (RPA) correlation energies have become increasingly popular as a post-Kohn-Sham correction, due to significant improvements over DFT calculations for properties such as long-range dispersion effects, which are problematic in conventional density functional theory. On the other hand, RPA still has various weaknesses, such as unsatisfactory results for non-isogyric processes. This can in parts be attributed to the self-correlation present in RPA correlation energies, leading to significant self-interaction errors. Therefore a variety of schemes have been devised to include exchange in the calculation of RPA correlation energies in order to correct this shortcoming. One of the most popular RPA plus exchange schemes is the second order screened exchange (SOSEX) correction. RPA + SOSEX delivers more accurate absolute correlation energies and also improves upon RPA for non-isogyric processes. On the other hand, RPA + SOSEX barrier heights are worse than those obtained from plain RPA calculations. To combine the benefits of RPA correlation energies and the SOSEX correction, we introduce a short-range RPA + SOSEX correction. Proof of concept calculations and benchmarks showing the advantages of our method are presented.

Surface effects on ionic Coulomb blockade in nanometer-size pores.

Science.gov (United States)

Tanaka, Hiroya; Iizuka, Hideo; Pershin, Yuriy V; Ventra, Massimiliano Di

2018-01-12

Ionic Coulomb blockade in nanopores is a phenomenon that shares some similarities but also differences with its electronic counterpart. Here, we investigate this phenomenon extensively using all-atom molecular dynamics of ionic transport through nanopores of about one nanometer in diameter and up to several nanometers in length. Our goal is to better understand the role of atomic roughness and structure of the pore walls in the ionic Coulomb blockade. Our numerical results reveal the following general trends. First, the nanopore selectivity changes with its diameter, and the nanopore position in the membrane influences the current strength. Second, the ionic transport through the nanopore takes place in a hopping-like fashion over a set of discretized states caused by local electric fields due to membrane atoms. In some cases, this creates a slow-varying 'crystal-like' structure of ions inside the nanopore. Third, while at a given voltage, the resistance of the nanopore depends on its length, the slope of this dependence appears to be independent of the molarity of ions. An effective kinetic model that captures the ionic Coulomb blockade behavior observed in MD simulations is formulated.

Surface effects on ionic Coulomb blockade in nanometer-size pores

Science.gov (United States)

Tanaka, Hiroya; Iizuka, Hideo; Pershin, Yuriy V.; Di Ventra, Massimiliano

2018-01-01

Ionic Coulomb blockade in nanopores is a phenomenon that shares some similarities but also differences with its electronic counterpart. Here, we investigate this phenomenon extensively using all-atom molecular dynamics of ionic transport through nanopores of about one nanometer in diameter and up to several nanometers in length. Our goal is to better understand the role of atomic roughness and structure of the pore walls in the ionic Coulomb blockade. Our numerical results reveal the following general trends. First, the nanopore selectivity changes with its diameter, and the nanopore position in the membrane influences the current strength. Second, the ionic transport through the nanopore takes place in a hopping-like fashion over a set of discretized states caused by local electric fields due to membrane atoms. In some cases, this creates a slow-varying ‘crystal-like’ structure of ions inside the nanopore. Third, while at a given voltage, the resistance of the nanopore depends on its length, the slope of this dependence appears to be independent of the molarity of ions. An effective kinetic model that captures the ionic Coulomb blockade behavior observed in MD simulations is formulated.

Coulomb repulsion in (TMTSF)2X and (TMTTF)2X

DEFF Research Database (Denmark)

Mortensen, Kell; Engler, E. M.

1985-01-01

On the basis of studies of transport properties of (TMTSF)2 X, (TMTTF)2X and their binary alloys the authors discuss the role of on-site Coulomb repulsion relative to the transfer integrals. In TMTTF-salts U/ta are believed to be large, resulting in a Hubbard gap, whereas U/ta in TMTSF-salts are ......On the basis of studies of transport properties of (TMTSF)2 X, (TMTTF)2X and their binary alloys the authors discuss the role of on-site Coulomb repulsion relative to the transfer integrals. In TMTTF-salts U/ta are believed to be large, resulting in a Hubbard gap, whereas U/ta in TMTSF...

Coulomb Force Correction to the Decay b→ccs in the Threshold(Particles and Fields)

OpenAIRE

Kouhei, HASEGAWA; Department of Physics, University of Alberta

2007-01-01

We study the physical origins of the O(α_s) and O(α^2_s) corrections to the c-s current in the decay b→ccs in the threshold region δ=(M_b-2m_c)/2M_b ≪1. We obtain the corrections which are produced by the Coulomb force between the anti-charm and strange quarks. The Coulomb corrections C_Fπ^2 at O(α_s) and -C^2_Fπ^2ln δ at O(α^2_s) account for 300% and 120% of the corresponding terms in the Abelian-type perturbative corrections respectively. The differences between the Coulomb and perturbative...

The Yang-Mills vacuum wave functional in Coulomb gauge

International Nuclear Information System (INIS)

Campagnari, Davide R.

2011-01-01

Yang-Mills theories are the building blocks of today's Standard Model of elementary particle physics. Besides methods based on a discretization of space-time (lattice gauge theory), also analytic methods are feasible, either in the Lagrangian or in the Hamiltonian formulation of the theory. This thesis focuses on the Hamiltonian approach to Yang-Mills theories in Coulomb gauge. The thesis is presented in cumulative form. After an introduction into the general formulation of Yang-Mills theories, the Hamilton operator in Coulomb gauge is derived. Chap. 1 deals with the heat-kernel expansion of the Faddeev-Popov determinant. In Chapters 2 and 3, the high-energy behaviour of the theory is investigated. To this purpose, perturbative methods are applied, and the results are compared with the ones stemming from functional methods in Coulomb and Landau gauge. Chap. 4 is devoted to the variational approach. Variational ansatzes going beyond the Gaussian form for the vacuum wave functional are considered and treated using Dyson-Schwinger techniques. Equations for the higher-order variational kernels are derived and their effects are estimated. Chap. 5 presents an application of the previously obtained propagators, namely the evaluation of the topological susceptibility, which is related to the mass of the η meson. Finally, a short overview of the perturbative treatment of dynamical fermion fields is presented.

Electronic and Structural Properties of ABO3: Role of the B-O Coulomb Repulsions for Ferroelectricity.

Science.gov (United States)

Miura, Kaoru; Azuma, Masaki; Funakubo, Hiroshi

2011-01-17

We have investigated the role of the Ti-O Coulomb repulsions in the appearance of the ferroelectric state in BaTiO3 as well as the role of the Zn-O Coulomb repulsions in BiZn0.5Ti0.5O3, using a first-principles calculation with optimized structures. In tetragonal BaTiO3, it is found that the Coulomb repulsions between Ti 3s and 3p states and O 2s and 2p states have an important role for the appearance of Ti ion displacement. In BiZn0.5Ti0.5O3, on the other hand, the stronger Zn-O Coulomb repulsions, which are due to the 3s, 3p, and 3d (d10) states of the Zn ion, have more important role than the Ti-O Coulomb repulsions for the appearance of the tetragonal structure. Our suggestion is consistent with the other ferroelectric perovskite oxides ABO3 in the appearance of tetragonal structures as well as rhombohedral structures.

Low rank factorization of the Coulomb integrals for periodic coupled cluster theory.

Science.gov (United States)

Hummel, Felix; Tsatsoulis, Theodoros; Grüneis, Andreas

2017-03-28

We study a tensor hypercontraction decomposition of the Coulomb integrals of periodic systems where the integrals are factorized into a contraction of six matrices of which only two are distinct. We find that the Coulomb integrals can be well approximated in this form already with small matrices compared to the number of real space grid points. The cost of computing the matrices scales as O(N 4 ) using a regularized form of the alternating least squares algorithm. The studied factorization of the Coulomb integrals can be exploited to reduce the scaling of the computational cost of expensive tensor contractions appearing in the amplitude equations of coupled cluster methods with respect to system size. We apply the developed methodologies to calculate the adsorption energy of a single water molecule on a hexagonal boron nitride monolayer in a plane wave basis set and periodic boundary conditions.

Resolutions of the Coulomb operator: VIII. Parallel implementation using the modern programming language X10.

Science.gov (United States)

Limpanuparb, Taweetham; Milthorpe, Josh; Rendell, Alistair P

2014-10-30

Use of the modern parallel programming language X10 for computing long-range Coulomb and exchange interactions is presented. By using X10, a partitioned global address space language with support for task parallelism and the explicit representation of data locality, the resolution of the Ewald operator can be parallelized in a straightforward manner including use of both intranode and internode parallelism. We evaluate four different schemes for dynamic load balancing of integral calculation using X10's work stealing runtime, and report performance results for long-range HF energy calculation of large molecule/high quality basis running on up to 1024 cores of a high performance cluster machine. Copyright © 2014 Wiley Periodicals, Inc.

Yangian Y(sl(2)) in Coulomb problem

International Nuclear Information System (INIS)

Zhang Shengli

1998-01-01

In this paper, the Yangian Y(sl(2)) is shown existing in the system that a particle moves in Coulomb field. The generators of Y(sl(2)) are constructed in terms of the angular momentum operators and so-called Yangian Runge-Lenz vector. The selection rule and matrix element of Y(sl(2)) generators are calculated. (orig.)

Semiclassical treatment of nuclear effects in Coulomb excitation

Energy Technology Data Exchange (ETDEWEB)

Canto, L F; Donangelo, R [Universidade Federal do Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Rasmussen, J O; Ring, P; Stoyer, M A [Lawrence Berkeley Lab., CA (USA). Nuclear Science Div.

1990-09-27

We introduce the effects of the nuclear potential in the semiclassical Alder-Winther-de Boer method, both in the coupling matrix elements and as corrections to the Rutherford orbit. We compare our results to those of pure Coulomb excitation and to coupled-channel calculations. (orig.).

Effect of the neutral charge fraction in the Coulomb explosion of H2+ ions through aluminum foils

International Nuclear Information System (INIS)

Denton, Cristian D.; Abril, Isabel; Barriga-Carrasco, Manuel D.; Garcia-Molina, Rafael; Lantschner, Gerardo H.; Eckardt, Juan C.; Arista, Netor R.

2002-01-01

The Coulomb explosion of the proton fragments dissociated from H 2 + molecules moving through thin aluminum foils has been studied by means of their energy spectra, measured in the forward direction, and by computer simulations. The covered energy range goes from 25 to 100 keV/u. Estimations of the neutral charge fraction of the fragments inside the foil have been obtained by comparison of the experimental energy spectra with the computer simulations

Numerical solver of the time-dependent Schroedinger equation with Coulomb singularities

International Nuclear Information System (INIS)

Gordon, Ariel; Jirauschek, Christian; Kaertner, Franz X.

2006-01-01

This paper addresses a very fundamental and important problem in the numerical analysis of atomic and molecular systems: How to discretize Hamiltonians with divergent potential terms, such as Coulomb singularities. At the point of a Coulomb singularity, the wave function cannot be described by a Taylor series expansion, which results in problems when standard discretization schemes are used. We propose using the known asymptotic form of the wave function near the singularity instead of the (nonexistent) Taylor series. This principle, namely discretization by asymptotic behavior correspondence (ABC), is employed in this paper for obtaining grid-discretizations for the Coulomb potential in Cartesian, cylindrical and spherical coordinate systems. We show that computations with the ABC discretization are faster and more precise than with a naive discretization by orders of magnitude. The ABC discretization is well suited for the standard numerical time propagators, such as the Crank-Nicholson, Peaceman-Rachford, and leapfrog schemes. We use the latter, since it is faster and has the same order of accuracy. The leapfrog scheme is generalized to allow absorbing potentials at the grid boundaries

Electromagnetic excitation with very heavy ions at and above the Coulomb barrier

International Nuclear Information System (INIS)

Wollersheim, H.J.

1988-08-01

The present report is part of a systematic study of the electromagnetic properties of strongly deformed and shape transitional nuclei carried out at GSI. The high efficiency particle-gamma detector system is described to perform multiple Coulomb excitation experiments with very heavy projectiles. Some results obtained for the shape transitional nucleus 196 Pt will be presented to exemplify the importance of having access to both the level energies and the E2-transition matrix elements when discussing the possible structure of these states. The second part of this paper is devoted to transfer reactions between very heavy nuclei. In contrast to light projectiles heavy ions offer the possibility to study new phenomena which originate in the much larger Coulomb contribution to the total interaction. In particular, heavy deformed nuclei will be Coulomb excited by the strong electromagnetic field to high spin states already at the time when they start interacting through the nuclear forces. The particle transfer therefore takes place mainly between excited collective states and thus should give information about the interplay between single-particle degrees of freedom, pair correlations and collective excitations. In this paper results of experiments will be reported in which nuclei from the rare earth and the actinide region have been bombarded by 206,208 Pb projectiles at incident energies near the Coulomb barrier. (orig./HSI)

A conceivable lattice structure of the Coulomb law

International Nuclear Information System (INIS)

Papp, E.; Santilli, R.M.

1983-01-01

A few heuristic remarks on recent extensions of the Coulomb law via effective potentials and other means, which appear to admit a lattice structure in time and space whose spacing are given by the characteristic period of the elctron and its Compton wave-length, respectively, are presented

Multiple Coulomb excitation effects in heavy ion compound and fusion cross sections

International Nuclear Information System (INIS)

Carlson, B.V.; Hussein, M.S.

1981-11-01

A simple model for the average S-matrix that describes heavy ion direct processes in the presence of absorption due to compound nucleus formation is developed. The fluctuation cross section and the fusion cross section are then calculated for deformed heavy ion systems where multiple Coulomb excitation is important. A simple expression for the fusion cross section valid for above-barrier energies is then obtained. The formula clearly displays the modification, due to Coulomb excitation, in the usual geometrical expression. (Author) [pt

Influences of temperature on asymmetric quantum dot qubit in Coulombic impunity potential

Science.gov (United States)

Chen, Y.-J.; Song, H.-T.; Xiao, J.-L.

2018-05-01

Using the variational method of the Pekar-type, we study the influences of the temperature on the asymmetric quantum dot (QD) qubit in the Coulombic impunity potential. Then we derive the numerical results and formulate the derivative relationships of the electron probability density and the electron oscillation period in the superposition state of the ground state and the first-excited state with the electron-phonon coupling constant, the Coulombic impurity potential, the transverse and longitudinal confinement strengths at different temperatures, respectively.

Coulomb excitation of rotational states in the 162Dy nucleus in the framework of the generalized semiclassical approximation

International Nuclear Information System (INIS)

Bolotin, Yu.L.; Gonchar, V.Yu.; Chekanov, N.A.

1985-01-01

Coulomb excitation of rotational states induced in heavyion collisions is treated in the framework of the generalized semiclassical approximation. The Hamiltonian of the system under consideration involves not only Coulomb forces (monopole, quadrupole, and hexadecapole) but as well a real nuclear potential in the form of the deformed Woods-Saxon potential. Strong dependence of the excitation probability on the interference between the Coulomb and nuclear interactions is shown. Calculations are carried out for the reaction 40 Ar+ 162 Dy at E=148.6 MeV. The calculated Coulomb excitation probabilities agree satisfactory with the corresponding experimental values

Coulomb double helical structure

Science.gov (United States)

Kamimura, Tetsuo; Ishihara, Osamu

2012-01-01

Structures of Coulomb clusters formed by dust particles in a plasma are studied by numerical simulation. Our study reveals the presence of various types of self-organized structures of a cluster confined in a prolate spheroidal electrostatic potential. The stable configurations depend on a prolateness parameter for the confining potential as well as on the number of dust particles in a cluster. One-dimensional string, two-dimensional zigzag structure and three-dimensional double helical structure are found as a result of the transition controlled by the prolateness parameter. The formation of stable double helical structures resulted from the transition associated with the instability of angular perturbations on double strings. Analytical perturbation study supports the findings of numerical simulations.

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

International Nuclear Information System (INIS)

Han Yiwen; Hong Yun; Bao Zhiqing

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. (general)

Vacuum structure of the SU(3) gauge field theory in the Coulomb gauge

International Nuclear Information System (INIS)

Yee, J.H.; Viswanathan, K.S.

1978-01-01

The SU(3) gauge field is studied in the Coulomb gauge. The Gribov ambiguities arising in the Coulomb gauge are analysed. Restricting to a class of spherically symmetric vacua it is shown that there exist non-trivial vacua characterized by a topological number eta=0, +-1/2, and +-2. This must be contrasted with the spherically symmetric SU(2) vacua which are characterized by eta=0, +-1/2. (Auth.)

Ground-state configuration of neutron-rich Aluminum isotopes through Coulomb Breakup

Directory of Open Access Journals (Sweden)

Chakraborty S.

2014-03-01

Full Text Available Neutron-rich 34,35Al isotopes have been studied through Coulomb excitation using LAND-FRS setup at GSI, Darmstadt. The method of invariant mass analysis has been used to reconstruct the excitation energy of the nucleus prior to decay. Comparison of experimental CD cross-section with direct breakup model calculation with neutron in p3/2 orbital favours 34Al(g.s⊗νp3/2 as ground state configuration of 35Al. But ground state configuration of 34Al is complicated as evident from γ-ray spectra of 33Al after Coulomb breakup of 34Al.

Microscopic theory of the Coulomb based exchange coupling in magnetic tunnel junctions.

Science.gov (United States)

Udalov, O G; Beloborodov, I S

2017-05-04

We study interlayer exchange coupling based on the many-body Coulomb interaction between conduction electrons in magnetic tunnel junction. This mechanism complements the known interaction between magnetic layers based on virtual electron hopping (or spin currents). We find that these two mechanisms have different behavior on system parameters. The Coulomb based coupling may exceed the hopping based exchange. We show that the Coulomb based exchange interaction, in contrast to the hopping based coupling, depends strongly on the dielectric constant of the insulating layer. The dependence of the interlayer exchange interaction on the dielectric properties of the insulating layer in magnetic tunnel junction is similar to magneto-electric effect where electric and magnetic degrees of freedom are coupled. We calculate the interlayer coupling as a function of temperature and electric field for magnetic tunnel junction with ferroelectric layer and show that the exchange interaction between magnetic leads has a sharp decrease in the vicinity of the ferroelectric phase transition and varies strongly with external electric field.

Localizing gauge fields on a topological Abelian string and the Coulomb law

International Nuclear Information System (INIS)

Torrealba S, Rafael S.

2010-01-01

The confinement of electromagnetic field is studied in axial symmetrical, warped, six-dimensional brane world, using a recently proposed topological Abelian string-vortex solution as background. It was found, that the massless gauge field fluctuations follow four-dimensional Maxwell equations in the Lorenz gauge. The massless zero mode is localized when the thickness of the string vortex is less than 5β/4πe 2 v 2 and there are no other localized massless modes. There is also an infinite of nonlocalized massive Fourier modes, that follow four-dimensional Proca equations with a continuous spectrum. To compute the corrections to the Coulomb potential, a radial cutoff was introduced, in order to achieve a discrete mass spectrum. As a main result, a (R o /βR 2 ) correction was found for the four-dimensional effective Coulomb law; the result is in correspondence with the observed behavior of the Coulomb potential at today's measurable distances.

JANUS - A setup for low-energy Coulomb excitation at ReA3

Science.gov (United States)

Lunderberg, E.; Belarge, J.; Bender, P. C.; Bucher, B.; Cline, D.; Elman, B.; Gade, A.; Liddick, S. N.; Longfellow, B.; Prokop, C.; Weisshaar, D.; Wu, C. Y.

2018-03-01

A new experimental setup for low-energy Coulomb excitation experiments was constructed in a collaboration between the National Superconducting Cyclotron Laboratory (NSCL), Lawrence Livermore National Laboratory (LLNL), and the University of Rochester and was commissioned at the general purpose beam line of NSCL's ReA3 reaccelerator facility. The so-called JANUS setup combines γ-ray detection with the Segmented Ge Array (SeGA) and scattered particle detection using a pair of segmented double-sided Si detectors (Bambino 2). The low-energy Coulomb excitation program that JANUS enables will complement intermediate-energy Coulomb excitation studies that have long been performed at NSCL by providing access to observables that quantify collectivity beyond the first excited state, including the sign and magnitude of excited-state quadrupole moments. In this work, the setup and its performance will be described based on the commissioning run that used stable 78Kr impinging onto a 1.09 mg/cm2208Pb target at a beam energy of 3.9 MeV/u.

Shape coexistence in the neutron-deficient mercury isotopes studied through Coulomb excitation

CERN Document Server

Bree, Nick

This thesis describes the analysis and results of a series of Coulomb-excitation experiments on even-even neutron-deficient mercury isotopes aimed at obtaining a more detailed description of shape coexistence. Two experimental campaigns have been undertaken in the Summer of 2007 and 2008. Pure beams of 182,184,186,188Hg were produced and accelerated at the REX-ISOLDE radioactive-beam facility, located at CERN (Geneva, Switzerland). The beams were guided to collide with a stable target to induce Coulomb excitation. The scattered particles were registered by a double-sided silicon strip detector, and the emitted gamma rays by the MINIBALL gamma-ray spectrometer. The motivation to study these mercury isotopes, focused around shape coexistence in atomic nuclei, is addressed in chapter 1, as well as an overview of the knowledge in this region of the nuclear chart. A theoretical description of Coulomb excitation is presented in the second chapter, while the third chapter describes the setup employed for the experim...

Coulomb excitations of low lying levels in 127I and 197Au

International Nuclear Information System (INIS)

Singh, K.P.; Tayal, D.C.; Hans, H.S.

1988-01-01

The low-lying levels of 127 I and 197 Au were Coulomb excited with 3.54 to 4.2 MeV protons. The reduced quadrupole transition probabilities of the 203, 374.9, 418, 618.4, 628.7, 651.1 and 745.5 keV states of 127 I, and the 268.8, 278.9, 502, and 547.5 keV states of 197 Au was measured from Coulomb excitation by observing the de-excitation gamma rays with a high resolution Ge(Li) detector. The low-energy protons were used for the first time to Coulomb-excite the two levels at 618.4 and 651.1 keV of 127 I and one level at 502 keV of 197 Au. The present experimental results are found in agreement with the existing experimental data except the B(E2) value of the level at 268.8 keV of 197 Au. (author). 4 figs., 4 tabs., 32 refs

Observations of static Coulomb stress triggering of the November 2011 M5.7 Oklahoma earthquake sequence

Science.gov (United States)

Sumy, Danielle F.; Cochran, Elizabeth S.; Keranen, Katie M.; Wei, Maya; Abers, Geoffrey A.

2014-01-01

In November 2011, a M5.0 earthquake occurred less than a day before a M5.7 earthquake near Prague, Oklahoma, which may have promoted failure of the mainshock and thousands of aftershocks along the Wilzetta fault, including a M5.0 aftershock. The M5.0 foreshock occurred in close proximity to active fluid injection wells; fluid injection can cause a buildup of pore fluid pressure, decrease the fault strength, and may induce earthquakes. Keranen et al. [2013] links the M5.0 foreshock with fluid injection, but the relationship between the foreshock and successive events has not been investigated. Here we examine the role of coseismic Coulomb stress transfer on earthquakes that follow the M5.0 foreshock, including the M5.7 mainshock. We resolve the static Coulomb stress change onto the focal mechanism nodal plane that is most consistent with the rupture geometry of the three M ≥ 5.0 earthquakes, as well as specified receiver fault planes that reflect the regional stress orientation. We find that Coulomb stress is increased, e.g., fault failure is promoted, on the nodal planes of ~60% of the events that have focal mechanism solutions, and more specifically, that the M5.0 foreshock promoted failure on the rupture plane of the M5.7 mainshock. We test our results over a range of effective coefficient of friction values. Hence, we argue that the M5.0 foreshock, induced by fluid injection, potentially triggered a cascading failure of earthquakes along the complex Wilzetta fault system.

Approximative analytic eigenvalues for orbital excitations in the case of a coulomb potential plus linear and quadratic radial terms

International Nuclear Information System (INIS)

Rekab, S.; Zenine, N.

2006-01-01

We consider the three dimensional non relativistic eigenvalue problem in the case of a Coulomb potential plus linear and quadratic radial terms. In the framework of the Rayleigh-Schrodinger Perturbation Theory, using a specific choice of the unperturbed Hamiltonian, we obtain approximate analytic expressions for the eigenvalues of orbital excitations. The implications and the range of validity of the obtained analytic expression are discussed

Signatures of Coulomb fission: a theoretical study

International Nuclear Information System (INIS)

Oberacker, V.; Kruse, H.; Pinkston, W.T.; Greiner, W.

1979-01-01

Evidence for Coulomb fission (CF) is noted first. Then the Hamiltonian is set down and explained, and an expression for the CF probability of CF is obtained. Results are summarized. Figures show the CF probability of 238 U as a function of projectile charge number and the excitation functions for CF of 238 U by 184 W and 136 Xe. 3 figures

How to calculate the Coulomb scattering amplitude

International Nuclear Information System (INIS)

Grosse, H.; Narnhofer, H.; Thirring, W.

1974-01-01

The derivation of scattering amplitudes for Coulomb scattering is discussed. A derivation of the S-matrix elements for a dense set of states in momentum space is given in the framework of time dependent scattering theory. The convergence of the S-matrix is studied. A purely algebraic derivation of the S-matrix elements and phase shifts is also presented. (HFdV)

Coulomb correlations in electron and positron impact ionization of hydrogen at intermediate and higher energies

International Nuclear Information System (INIS)

Jetzke, S.; Faisal, F.H.M.

1992-01-01

Investigating the relation between the asymptotic condition and the dynamic Coulomb correlation for single and multiple ionization we discuss a complete set of spatially separable N-electrons final-state wavefunctions, satisfying multiple ionization boundary conditions. We apply these results to electron and positron impact ionization of atomic hydrogen in the energy range 54.4 and 250 eV on the basis of a parameter-free model formulated within the scope of the multiple scattering approach. A comparison between our results and available experimental data and alternative theoretical calculations are made and discussed. (Author)

Total source charge and charge screening in Yang-Mills theories

International Nuclear Information System (INIS)

Campbell, W.B.; Norton, R.E.

1991-01-01

New gauge-invariant definitions for the total charge on a static Yang-Mills source are suggested which we argue are better suited for determining when true color screening has occurred. In particular, these new definitions imply that the Abelian Coulomb solution for a simple ''electric'' dipole source made up of two opposite point charges has zero total source charge and therefore no color screening. With the definition of total source charge previously suggested by other authors, such a source would have a total source charge of 2q and therefore a screening charge in the field of -2q, where q is the magnitude of the charge of either point charge. Our definitions for more general solutions are not unique because of the path dependence of the parallel transport of charges. Suggestions for removing this ambiguity are offered, but it is not known if a unique, physically meaningful definition of total source charge in fact exists

Major difference in visible-light photocatalytic features between perfect and self-defective Ta3N5 materials: A screened coulomb hybrid dft investigation

KAUST Repository

Harb, Moussab

2014-09-11

Relevant properties to visible-light overall water splitting reactions of perfect and self-defective bulk Ta3N5 semiconductor photocatalysts are investigated using accurate first-principles quantum calculations on the basis of density functional theory (DFT, including the perturbation theory DFPT) within the screened coulomb hybrid (HSE06) exchange-correlation formalism. Among the various explored self-defective structures, a strong stabilization is obtained for the configuration displaying a direct interaction between the created N- and Ta-vacancies. In the lowest-energy structure, each of the three created Ta-vacancies and the five created N-vacancies is found to be in aggregated disposition, leading to the formation of cages into the lattice. Although the calculated structural, electronic, and optical properties of the two materials are found to be very similar and in good agreement with available experimental works, their photocatalytic features for visible-light overall water splitting reactions show completely different behaviors. On the basis of calculated band edge positions relative to water redox potentials, the perfect Ta3N5 (calculated band gap of 2.2 eV) is predicted by HSE06 to be a good candidate only for H+ reduction while the self-defective Ta3N5 (calculated band gap of 2.0 eV) reveals suitable band positions for both water oxidation and H+ reduction similar to the experimental data reported on Ta3N5 powders. Its ability to reduce H+ is predicted to be lower than the perfect one. However, the strongly localized electronic characters of the valence band (VB) and conduction band (CB) edge states of the self-defective material only on the N 2p and Ta 5d orbitals surrounding the aggregated N- and Ta-vacancies are expected to strongly limit the probability of photogenerated carrier mobility through its crystal structure.

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.

Coulomb-explosion technique for determining geometrical structures of molecular ions

International Nuclear Information System (INIS)

Gemmell, D.S.

1981-01-01

Traditional experimental techniques (e.g. studies on photon absorption or emission) for determining the sterochemical structures of neutral molecules are extremeley difficult to apply to molecular ions because of problems in obtaining a sufficient spatial density of the ions to be studied. Recent high-resolution measurements on the energy and angle distributions of the fragments produced when fast (MeV) molecular-ion beams from an electrostatic accelerator dissociate (Coulomb explode) in thin foils and in gases, offer promising possibilities for deducing the sterochemical structures of the molecular ions constituting the incident beams. Bond lengths have been determined in this way for several diatomic projectiles (H 2+ , HeH + , CH + , NH + , OH + , N 2+ , O 2+ , etc.) with an accuracy of approx. 0.01 A. H 3+ has been demonstrated (for the first time) to be equilateral triangular and the interproton distance measured. Measurements on single fragments from CO 2+ , N 2 O + , C 3 H 3+ , and CH/sub n/ + have revealed the gross structures of the projectiles. An apparatus has recently been constructed at Argonne to permit precise measurements on fragments in coincidence. The apparatus has been tested on a known structure (OH 2+ ). The O-H bond length was found to be 1.0 +- 0.04 A and the H-O-H bond angle was measured as 110 --- 2 0 . These values are in excellent agreement with those found in optical experiments (0.999 A and 110.5 0 ). This Coulomb explosion technique can be expected to be refined in accuracy and to be extended to a wide range of molecular ions whose structures are inaccessible by other means

Semiclassical treatment of inelastic collisions between electrons and highly ionized atoms

International Nuclear Information System (INIS)

Frasier, S.M.

1984-01-01

The thesis is concerned with the calculation of excitation cross sections of ions by electron impact at intermediate energies in the limit of Z >> N/sub b/, where Z is the atomic number and N/sub b/ is the number of bound electrons. A semiclassical procedure is developed for calculating total cross sections using analytic bound states and averaged free electron wave functions derived in the second eikonal approximation. The analytic bound states are derived assuming a screened Coulomb potential and using orbital energies obtained from Hartree-Fock calculations. The functional form of the bound states reduces naturally to the hydrogen atom functions in the limit Z → infinity. The free electron functions used are semiclassical solutions to the free electron Schroedinger equation with a screened Coulomb potential. An exact solution is obtained in the second eikonal approximation, including all classical path contributions. This solution is averaged to extract the focusing and acceleration effects resulting from the long range Coulomb potential of the ion. The results are presented in the form of Born-like cross section formulae and demonstrate the appropriate correction of the Born cross section which arises from the acceleration and focusing of the free electrons by the long range Coulomb potential. Comparison is made with the Coulomb-Born results; the results agree to within 10% in most cases

An entropic form for NLFP with coulombic-like potential

International Nuclear Information System (INIS)

Grassi, A.

2012-01-01

Here it is proposed a new entropy form for which it is possible to obtain a stationary solution of the Non-Linear Fokker–Planck equation (NLFP) with coulombic-like potentials. The general properties of this new entropy form are shown and the results are compared with those obtained by other entropy forms. Finally, the behavior of the stationary solution in presence of two point charges is also shown. -- Highlights: ► In this Letter we have proposed a new form of entropy. ► Starting from this new entropy form a Non-Linear Fokker–Planck equation has been derived. ► The stationary solution of the Non-Linear Fokker–Planck equation is obtained by using an external coulombic-like potential. ► A comparison with other forms of entropies has been proposed in the case of a single or two point charges.

Quantum effects on the coulomb logarithm for energetic ions during the initial thermalization phase

CERN Document Server

Deng Bai Quan; Deng Mei Gen; Peng Li Lin

2002-01-01

The authors have discussed the quantum mechanical effects for the energetic charged particles produced in D-He sup 3 fusion reactions. Authors' results show that it is better to use the proper Coulomb logarithm at the high-energy end in describing the thermalization process, because the quantum mechanical effects on the Coulomb logarithm are not negligible, based on an assumption of binary collision

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.

Unsafe Coulomb excitation of 240-244Pu

International Nuclear Information System (INIS)

Ahmad, I.; Amro, H.; Carpenter, M. P.; Chowdhury, P.; Cizewski, J.; Cline, D.; Greene, J. P.; Hackman, G.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Macchiavelli, A. O.; Nisius, D. T.; Reiter, P.; Seabury, E. H.; Seweryniak, D.; Siem, S.; Uusitalo, J.; Wiedenhoever, I.; Wu, C. Y.

1999-01-01

The high spin states of 240 Pu and 244 Pu have been investigated with GAMMASPHERE at ATLAS, using Coulomb excitation with a 208 Pb beam at energies above the Coulomb barrier. Data on a transfer channel leading to 242 Pu were obtained as well. In the case of 244 Pu, the yrast band was extended to 34h b ar revealing the completed πi 13/2 alignment, a ''first'' for actinide nuclei. The yrast sequence of 242 Pu was also extended to higher spin and a similar backbend was delineated. In contrast, while the ground state band of 240 Pu was measured up to the highest rotational frequencies ever reported in the actinide region (approximately300 keV), no sign of particle alignment was observed. In this case, several observable such as the large B(E1)/B(E2) branching ratios in the negative parity band, and the vanishing energy staggering between the negative and positive parity bands suggest that the strength of octupole correlations increases with rotational frequency. These stronger correlations may well be responsible for delaying or suppressing the πi 13/2 particle alignment

Temperature dependence of Coulomb oscillations in a few-layer two-dimensional WS2 quantum dot.

Science.gov (United States)

Song, Xiang-Xiang; Zhang, Zhuo-Zhi; You, Jie; Liu, Di; Li, Hai-Ou; Cao, Gang; Xiao, Ming; Guo, Guo-Ping

2015-11-05

Standard semiconductor fabrication techniques are used to fabricate a quantum dot (QD) made of WS2, where Coulomb oscillations were found. The full-width-at-half-maximum of the Coulomb peaks increases linearly with temperature while the height of the peaks remains almost independent of temperature, which is consistent with standard semiconductor QD theory. Unlike graphene etched QDs, where Coulomb peaks belonging to the same QD can have different temperature dependences, these results indicate the absence of the disordered confining potential. This difference in the potential-forming mechanism between graphene etched QDs and WS2 QDs may be the reason for the larger potential fluctuation found in graphene QDs.

B-13,B-14(n,gamma) via Coulomb Dissociation for Nucleosynthesis towards the r-Process

NARCIS (Netherlands)

Altstadt, S. G.; Adachi, T.; Aksyutina, Y.; Alcantara, J.; Alvarez-Pol, H.; Ashwood, N.; Atar, L.; Aumann, T.; Avdeichikov, V.; Barr, M.; Beceiro, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Boretzky, K.; Borge, M. J. G.; Burgunder, G.; Caamano, M.; Caesar, C.; Casarejos, E.; Catford, W.; Cederkall, J.; Chakraborty, S.; Chartier, M.; Chulkov, L.; Cortina-Gil, D.; Pramanik, U. Datta; Fernandez, P. Diaz; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estrade, A.; Farinon, F.; Fraile, L. M.; Freer, M.; Freudenberger, M.; Fynbo, H. O. U.; Galaviz, D.; Geissel, H.; Gernhaeuser, R.; Goebel, K.; Golubev, P.; Gonzalez Diaz, D.; Kalantar-Nayestanaki, N.; Najafi, M. A.; Rigollet, C.; Stoica, V.; Streicher, B.; Van de Walle, J.

Radioactive beams of B-14,B-15 produced by fragmentation of a primary Ar-40 beam were directed onto a Pb target to investigate the neutron breakup within the Coulomb field. The experiment was performed at the LAND/(RB)-B-3 setup. Preliminary results for the Coulomb dissociation cross sections as

Analytic structure of many-body Coulombic wave functions

DEFF Research Database (Denmark)

Fournais, Søren; Hoffmann-Ostenhof, Maria; Hoffmann-Ostenhof, Thomas

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 coal...

Influence of screening effect on hydrogen passivation of hole silicon

International Nuclear Information System (INIS)

Aleksandrov, O.V.

2002-01-01

The simulation of hole silicon passivation during hydrogen diffusion with account of hydrogen-acceptor pairs formation, internal electrical field and screening effect has been carried out. Screening by free carriers of hydrogen and acceptor ions results in shortening their interaction radii and slacking the concentration dependence of hydrogen diffusivity at high level of silicon doping. The consistency of simulated and experimental profiles of holes and hydrogen-acceptor pairs is reached in a broad band of doping levels from 4 x 10 14 to 1.2 x 10 20 cm -3 at the pair binding energy of 0.70-0.79 eV while the radius of the Coulomb interaction of hydrogen and boron ions is equal to 35 A under low doping and decrease with increasing doping level [ru

Convergence problems of Coulomb and multipole sums in crystals

International Nuclear Information System (INIS)

Kholopov, Evgenii V

2004-01-01

Different ways of calculating Coulomb and dipole sums over crystal lattices are analyzed comparatively. It is shown that the currently alleged disagreement between various approaches originates in ignoring the requirement for the self-consistency of surface conditions, which are of fundamental importance due to the long-range nature of the bulk interactions that these sums describe. This is especially true of surfaces arising when direct sums for infinite translation-invariant structures are truncated. The charge conditions for actual surfaces being self-consistently adjusted to the bulk state are formally the same as those on the truncation surface, consistent with the concept of the thermodynamic limit for the bulk-state absolute equilibrium and with the fact that the surface energy contribution in this case is, naturally, statistically small compared to the bulk contribution. Two-point multipole expansions are briefly discussed, and the problems associated with the boundary of their convergence circle are pointed out. (reviews of topical problems)

13,14B(n, γ) via Coulomb Dissociation for Nucleosynthesis towards the r-Process

International Nuclear Information System (INIS)

Altstadt, S.G.; Adachi, T.; Aksyutina, Y.; Alcantara, J.; Alvarez-Pol, H.; Ashwood, N.; Atar, L.; Aumann, T.; Avdeichikov, V.; Barr, M.; Beceiro, S.; Bemmerer, D.

2014-01-01

Radioactive beams of 14,15 B produced by fragmentation of a primary 40 Ar beam were directed onto a Pb target to investigate the neutron breakup within the Coulomb field. The experiment was performed at the LAND/R 3 B setup. Preliminary results for the Coulomb dissociation cross sections as well as for the astrophysically interesting inverse reactions, 13,14 B(n,γ), are presented

Fermi Surface of Sr_{2}RuO_{4}: Spin-Orbit and Anisotropic Coulomb Interaction Effects.

Science.gov (United States)

Zhang, Guoren; Gorelov, Evgeny; Sarvestani, Esmaeel; Pavarini, Eva

2016-03-11

The topology of the Fermi surface of Sr_{2}RuO_{4} is well described by local-density approximation calculations with spin-orbit interaction, but the relative size of its different sheets is not. By accounting for many-body effects via dynamical mean-field theory, we show that the standard isotropic Coulomb interaction alone worsens or does not correct this discrepancy. In order to reproduce experiments, it is essential to account for the Coulomb anisotropy. The latter is small but has strong effects; it competes with the Coulomb-enhanced spin-orbit coupling and the isotropic Coulomb term in determining the Fermi surface shape. Its effects are likely sizable in other correlated multiorbital systems. In addition, we find that the low-energy self-energy matrix-responsible for the reshaping of the Fermi surface-sizably differs from the static Hartree-Fock limit. Finally, we find a strong spin-orbital entanglement; this supports the view that the conventional description of Cooper pairs via factorized spin and orbital part might not apply to Sr_{2}RuO_{4}.

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.

Coulomb and Nuclear Breakup at Low Energies: Scaling Laws

Directory of Open Access Journals (Sweden)

Hussein M. S.

2013-12-01

Full Text Available We report on a recent work on the low-energy behavior of the breakup cross section in so far as it has important role in the fusion of weakly bound and halo nuclei at near-barrier energies. We assess the way the nuclear component of this cross section scales with the target mass. In complete accord with previous finding at higher energies we verify that the low energy behavior of the breakup cross section for a given projectile and relative center of mass energy with respect to the Coulomb barrier height scales as the cubic root of the mass number of the target. Surprisingly we find that the Coulomb component of the breakup cross section at these low energies also obeys scaling, but with a linear dependence on the target charge. Our findings are important when planning for experiments involving these exotic nuclei.

Coulomb artifacts and bottomonium hyperfine splitting in lattice NRQCD

Energy Technology Data Exchange (ETDEWEB)

Liu, T. [Department of Physics, University of Alberta,11455 Saskatchewan Drive, Edmonton, Alberta T6G 2J1 (Canada); Penin, A.A. [Department of Physics, University of Alberta,11455 Saskatchewan Drive, Edmonton, Alberta T6G 2J1 (Canada); Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology,Wolfgang-Gaede-Strasse 1, 76128 Karlsruhe (Germany); Rayyan, A. [Department of Physics, University of Alberta,11455 Saskatchewan Drive, Edmonton, Alberta T6G 2J1 (Canada)

2017-02-16

We study the role of the lattice artifacts associated with the Coulomb binding effects in the analysis of the heavy quarkonium within lattice NRQCD. We find that a “naïve” perturbative matching generates spurious linear Coulomb artifacts, which result in a large systematic error in the lattice predictions for the heavy quarkonium spectrum. This effect is responsible, in particular, for the discrepancy between the recent determinations of the bottomonium hyperfine splitting in the radiatively improved lattice NRQCD (DOI: 10.1103/PhysRevD.92.054502; Arxiv:1309.5797). We show that the correct matching procedure which provides full control over discretization errors is based on the asymptotic expansion of the lattice theory about the continuum limit, which gives M{sub Υ(1S)}−M{sub η{sub b(1S)}}=52.9±5.5 MeV (DOI: 10.1103/PhysRevD.92.054502).

"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications

Science.gov (United States)

Marshall, J. R.

1999-01-01

The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this

"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications

Science.gov (United States)

Marshall, J. R.

1999-09-01

The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this

A unitarized meson model including color Coulomb interaction

International Nuclear Information System (INIS)

Metzger, Kees.

1990-01-01

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

SUSY shape-invariant Hamiltonians for the generalized dirac-coulomb problem

International Nuclear Information System (INIS)

Rodrigues, R. de Lima; Vaidya, Arvind Narayan

2007-02-01

A spin 1/2 relativistic particle described by a general potential in terms of the sum of the Coulomb potential with a Lorentz scalar potential is investigated via supersymmetry in quantum mechanics. (author)

On Coulomb collisions in bi-Maxwellian plasmas

Czech Academy of Sciences Publication Activity Database

Hellinger, Petr; Trávníček, Pavel M.

2009-01-01

Roč. 16, č. 5 (2009), 054501/1-054501/4 ISSN 1070-664X R&D Projects: GA AV ČR IAA300420702 Institutional research plan: CEZ:AV0Z30420517; CEZ:AV0Z10030501 Keywords : Coulomb collisions * transport coefficients * bi-Maxwellian distribution function Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.475, year: 2009 http://link.aip.org/link/?PHPAEN/16/054501/1

Coulomb replica-exchange method: handling electrostatic attractive and repulsive forces for biomolecules.

Science.gov (United States)

Itoh, Satoru G; Okumura, Hisashi

2013-03-30

We propose a new type of the Hamiltonian replica-exchange method (REM) for molecular dynamics (MD) and Monte Carlo simulations, which we refer to as the Coulomb REM (CREM). In this method, electrostatic charge parameters in the Coulomb interactions are exchanged among replicas while temperatures are exchanged in the usual REM. By varying the atom charges, the CREM overcomes free-energy barriers and realizes more efficient sampling in the conformational space than the REM. Furthermore, this method requires only a smaller number of replicas because only the atom charges of solute molecules are used as exchanged parameters. We performed Coulomb replica-exchange MD simulations of an alanine dipeptide in explicit water solvent and compared the results with those of the conventional canonical, replica exchange, and van der Waals REMs. Two force fields of AMBER parm99 and AMBER parm99SB were used. As a result, the CREM sampled all local-minimum free-energy states more frequently than the other methods for both force fields. Moreover, the Coulomb, van der Waals, and usual REMs were applied to a fragment of an amyloid-β peptide (Aβ) in explicit water solvent to compare the sampling efficiency of these methods for a larger system. The CREM sampled structures of the Aβ fragment more efficiently than the other methods. We obtained β-helix, α-helix, 3(10)-helix, β-hairpin, and β-sheet structures as stable structures and deduced pathways of conformational transitions among these structures from a free-energy landscape. Copyright © 2012 Wiley Periodicals, Inc.

Structure Theory for Extended Kepler-Coulomb 3D Classical Superintegrable Systems

Directory of Open Access Journals (Sweden)

Ernie G. Kalnins

2012-06-01

Full Text Available The classical Kepler-Coulomb system in 3 dimensions is well known to be 2nd order superintegrable, with a symmetry algebra that closes polynomially under Poisson brackets. This polynomial closure is typical for 2nd order superintegrable systems in 2D and for 2nd order systems in 3D with nondegenerate (4-parameter potentials. However the degenerate 3-parameter potential for the 3D extended Kepler-Coulomb system (also 2nd order superintegrable is an exception, as its quadratic symmetry algebra doesn't close polynomially. The 3D 4-parameter potential for the extended Kepler-Coulomb system is not even 2nd order superintegrable. However, Verrier and Evans (2008 showed it was 4th order superintegrable, and Tanoudis and Daskaloyannis (2011 showed that in the quantum case, if a second 4th order symmetry is added to the generators, the double commutators in the symmetry algebra close polynomially. Here, based on the Tremblay, Turbiner and Winternitz construction, we consider an infinite class of classical extended Kepler-Coulomb 3- and 4-parameter systems indexed by a pair of rational numbers (k_1,k_2 and reducing to the usual systems when k_1=k_2=1. We show these systems to be superintegrable of arbitrarily high order and work out explicitly the structure of the symmetry algebras determined by the 5 basis generators we have constructed. We demonstrate that the symmetry algebras close rationally; only for systems admitting extra discrete symmetries is polynomial closure achieved. Underlying the structure theory is the existence of raising and lowering constants of the motion, not themselves polynomials in the momenta, that can be employed to construct the polynomial symmetries and their structure relations.

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.

An infinite family of superintegrable deformations of the Coulomb potential

International Nuclear Information System (INIS)

Post, Sarah; Winternitz, Pavel

2010-01-01

We introduce a new family of Hamiltonians with a deformed Kepler-Coulomb potential dependent on an indexing parameter k. We show that this family is superintegrable for all rational k and compute the classical trajectories and quantum wavefunctions. We show that this system is related, via coupling constant metamorphosis, to a family of superintegrable deformations of the harmonic oscillator given by Tremblay, Turbiner and Winternitz. In doing so, we prove that all Hamiltonians with an oscillator term are related by coupling constant metamorphosis to systems with a Kepler-Coulomb term, both on Euclidean space. We also look at the effect of the transformation on the integrals of the motion, the classical trajectories and the wavefunctions, and give the transformed integrals explicitly for the classical system. (fast track communication)

An infinite family of superintegrable deformations of the Coulomb potential

Energy Technology Data Exchange (ETDEWEB)

Post, Sarah [Centre de recherches mathematiques, CP 6128 succ. Centre-Ville, Montreal, QC H3C 3J7 (Canada); Winternitz, Pavel, E-mail: post@CRM.UMontreal.C, E-mail: wintern@CRM.UMontreal.C [Centre de recherches mathematiques and Departement de mathematiques et de statistique, CP 6128 succ. Centre-Ville, Montreal, QC H3C 3J7 (Canada)

2010-06-04

We introduce a new family of Hamiltonians with a deformed Kepler-Coulomb potential dependent on an indexing parameter k. We show that this family is superintegrable for all rational k and compute the classical trajectories and quantum wavefunctions. We show that this system is related, via coupling constant metamorphosis, to a family of superintegrable deformations of the harmonic oscillator given by Tremblay, Turbiner and Winternitz. In doing so, we prove that all Hamiltonians with an oscillator term are related by coupling constant metamorphosis to systems with a Kepler-Coulomb term, both on Euclidean space. We also look at the effect of the transformation on the integrals of the motion, the classical trajectories and the wavefunctions, and give the transformed integrals explicitly for the classical system. (fast track communication)

Letting students discover the power, and the limits, of simple models: Coulomb's law

Science.gov (United States)

Bohacek, Peter; Vonk, Matthew; Dill, Joseph; Boehm, Emma

2017-09-01

The inverse-square law pops up all over. It's a simplified model of reality that describes light, sound, gravity, and static electricity. But when it's brought up in class, students are often just handed the equations. They rarely have an opportunity to discover Coulomb's law or Newton's law of gravitation for themselves. It's not hard to understand why. A quantitative demonstration of Coulomb's law can be difficult. The forces are smaller than many force sensors can measure and static electricity tends to be finicky. In addition, off-the-shelf units are expensive or difficult to use. As a result, many instructors skip this lab in favor of qualitative demonstrations or simulations. Adolf Cortel sought to remedy this by designing a straightforward experiment for measuring Coulomb's law using charged metalized-glass spheres (Christmas ornaments) and an electronic balance. Building on Cortel's design, we've made a series of video-based experiments that students can use to discover the relationships that underlie electric force.

Maximal superintegrability of the generalized Kepler-Coulomb system on N-dimensional curved spaces

International Nuclear Information System (INIS)

Ballesteros, Angel; Herranz, Francisco J

2009-01-01

The superposition of the Kepler-Coulomb potential on the 3D Euclidean space with three centrifugal terms has recently been shown to be maximally superintegrable (Verrier and Evans 2008 J. Math. Phys. 49 022902) by finding an additional (hidden) integral of motion which is quartic in the momenta. In this paper, we present the generalization of this result to the N-dimensional spherical, hyperbolic and Euclidean spaces by making use of a unified symmetry approach that makes use of the curvature parameter. The resulting Hamiltonian, formed by the (curved) Kepler-Coulomb potential together with N centrifugal terms, is shown to be endowed with 2N - 1 functionally independent integrals of the motion: one of them is quartic and the remaining ones are quadratic. The transition from the proper Kepler-Coulomb potential, with its associated quadratic Laplace-Runge-Lenz N-vector, to the generalized system is fully described. The role of spherical, nonlinear (cubic) and coalgebra symmetries in all these systems is highlighted

Hamiltonian approach to QCD in Coulomb gauge at zero and finite temperature

Directory of Open Access Journals (Sweden)

Reinhardt H.

2017-01-01

Full Text Available I report on recent results obtained within the Hamiltonian approach to QCD in Coulomb gauge. By relating the Gribov confinement scenario to the center vortex picture of confinement it is shown that the Coulomb string tension is tied to the spatial string tension. For the quark sector a vacuum wave functional is used which results in variational equations which are free of ultraviolet divergences. The variational approach is extended to finite temperatures by compactifying a spatial dimension. For the chiral and deconfinement phase transition pseudo-critical temperatures of 170MeV and 198 MeV, respectively, are obtained.

Simulations of Coulomb systems confined by polarizable surfaces using periodic Green functions.

Science.gov (United States)

Dos Santos, Alexandre P; Girotto, Matheus; Levin, Yan

2017-11-14

We present an efficient approach for simulating Coulomb systems confined by planar polarizable surfaces. The method is based on the solution of the Poisson equation using periodic Green functions. It is shown that the electrostatic energy arising from the surface polarization can be decoupled from the energy due to the direct Coulomb interaction between the ions. This allows us to combine an efficient Ewald summation method, or any other fast method for summing over the replicas, with the polarization contribution calculated using Green function techniques. We apply the method to calculate density profiles of ions confined between the charged dielectric and metal surfaces.