Amplitude Function of Asymptotic Correlations Along Charged Wall in Coulomb Fluids
NASA Astrophysics Data System (ADS)
Šamaj, Ladislav
2016-07-01
In classical semi-infinite Coulomb fluids, two-point correlation functions exhibit a slow inverse-power law decay along a uniformly charged wall. In this work, we concentrate on the corresponding amplitude function which depends on the distances of the two points from the wall. Recently Šamaj (J Stat Phys 161:227-249 2015), applying a technique of anticommuting variables to a 2D system of charged rectilinear wall with "counter-ions only", we derived a relation between the amplitude function and the density profile which holds for any temperature. In this paper, using the Möbius conformal transformation of particle coordinates in a disc, a new relation between the amplitude function and the density profile is found for that model. In all exactly solvable cases, the amplitude function factorizes itself in the two distances from the wall. Presupposing this factorization property at any temperature and using specific sum rules for semi-infinite geometries, a relation between the amplitude function of the charge-charge structure function and the charge profile is derived for many-component Coulomb fluids in any dimension.
NASA Astrophysics Data System (ADS)
Zhou, J. X.; Zhang, L.
2005-01-01
Incremental harmonic balance (IHB) formulations are derived for general multiple degrees of freedom (d.o.f.) non-linear autonomous systems. These formulations are developed for a concerned four-d.o.f. aircraft wheel shimmy system with combined Coulomb and velocity-squared damping. A multi-harmonic analysis is performed and amplitudes of limit cycles are predicted. Within a large range of parametric variations with respect to aircraft taxi velocity, the IHB method can, at a much cheaper cost, give results with high accuracy as compared with numerical results given by a parametric continuation method. In particular, the IHB method avoids the stiff problems emanating from numerical treatment of aircraft wheel shimmy system equations. The development is applicable to other vibration control systems that include commonly used dry friction devices or velocity-squared hydraulic dampers.
ERIC Educational Resources Information Center
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…
A Coulomb-Like Off-Shell T-Matrix with the Correct Coulomb Phase Shift
NASA Astrophysics Data System (ADS)
Oryu, Shinsho; Watanabe, Takashi; Hiratsuka, Yasuhisa; Togawa, Yoshio
2017-03-01
We confirm the reliability of the well-known Coulomb renormalization method (CRM). It is found that the CRM is only available for a very-long-range screened Coulomb potential (SCP). However, such an SCP calculation in momentum space is considerably difficult because of the cancelation of significant digits. In contrast to the CRM, we propose a new method by using an on-shell equivalent SCP and the rest term. The two-potential theory with r-space is introduced, which defines fully the off-shell Coulomb amplitude.
Hughto, J.; Schneider, A. S.; Horowitz, C. J.; Berry, D. K.
2011-07-15
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 {Gamma}=175 to Coulomb parameters up to {Gamma}=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.
Diffusion in Coulomb crystals.
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.
Positron scattering from hydrogen atom with screened Coulomb potentials
Ghoshal, Arijit; Nayek, Sujay; Kamali, M. Z. M.; Ratnavelu, K.
2014-03-05
Elastic positron-hydrogen collisions with screened Coulomb potentials have been investigated using a second-order distorted wave Born approximation in the momentum space. Two types of potentials have been considered, namely, static screened Coulomb potential and exponential cosine-screened Coulomb potential. Using a simple variationally determined hydrogenic wave function it has been possible to obtain the scattering amplitude in a closed form. A detailed study has been made on the differential and total cross sections in the energy range 20–300 eV.
Coulomb gauge ghost propagator and the Coulomb form factor
NASA Astrophysics Data System (ADS)
Quandt, M.; Burgio, G.; Chimchinda, S.; Reinhardt, H.
The ghost propagator and the Coulomb potential are evaluated in Coulomb gauge on the lattice, using an improved gauge fixing scheme which includes the residual symmetry. This setting has been shown to be essential in order to explain the scaling violations in the instantaneous gluon propagator. We find that both the ghost propagator and the Coulomb potential are insensitive to the Gribov problem or the details of the residual gauge fixing, even if the Coulomb potential is evaluated from the A0 -propagator instead of the Coulomb kernel. In particular, no signs of scaling violations could be found in either quantity, at least to well below the numerical accuracy where these violations were visible for the gluon propagator. The Coulomb potential from the A0 -propagator is shown to be in qualitative agreement with the (formally equivalent) expression evaluated from the Coulomb kernel.
Polonyi, J.
2008-06-15
The contribution of different modes of the Coulomb field to decoherence and to the dynamical breakdown of the time reversal invariance is calculated in the one-loop approximation for nonrelativistic electron gas. The dominant contribution was found to come from the usual collective modes in the plasma, namely, the zero-sound and the plasmon oscillations. The length scale of the quantum-classical transition is found to be close to the Thomas-Fermi screening length. It is argued that the extension of these modes to the whole Fock space yields optimal pointer states.
Coulomb Interactions in Hanbury Brown-Twiss Experiments with Electrons
ERIC Educational Resources Information Center
Shen, Kan
2009-01-01
This dissertation examines the effect of Coulomb interactions in Hanbury Brown-Twiss (HBT) type experiments with electrons. HBT experiments deal with intensity interference, which is related to the second-order correlation function of the particle field. This is an extension of the usual amplitude interference experiment, such as Young's…
A New Feature of the Screened Coulomb Potential in Momentum Space
NASA Astrophysics Data System (ADS)
Watanabe, Takashi; Hiratsuka, Yasuhisa; Oryu, Shinsho; Togawa, Yoshio
2017-03-01
A Coulomb equivalent screened Coulomb potential is proposed for solving the Schrödinger equation and/or the Calogero first order differential equation, where some critical range bands are obtained. Phase shifts for "any" two-charged particle system (from electron-electron to heavy ion-heavy ion) are reproduced by using the universal critical range bands and the appropriate Sommerfeld parameter over a very wide energy region. A Coulomb-like off-shell amplitude is introduced using two-potential theory without employing the usual Coulomb renormalization method.
Traceable Coulomb blockade thermometry
NASA Astrophysics Data System (ADS)
Hahtela, O.; Mykkänen, E.; Kemppinen, A.; Meschke, M.; Prunnila, M.; Gunnarsson, D.; Roschier, L.; Penttilä, J.; Pekola, J.
2017-02-01
We present a measurement and analysis scheme for determining traceable thermodynamic temperature at cryogenic temperatures using Coulomb blockade thermometry. The uncertainty of the electrical measurement is improved by utilizing two sampling digital voltmeters instead of the traditional lock-in technique. The remaining uncertainty is dominated by that of the numerical analysis of the measurement data. Two analysis methods are demonstrated: numerical fitting of the full conductance curve and measuring the height of the conductance dip. The complete uncertainty analysis shows that using either analysis method the relative combined standard uncertainty (k = 1) in determining the thermodynamic temperature in the temperature range from 20 mK to 200 mK is below 0.5%. In this temperature range, both analysis methods produced temperature estimates that deviated from 0.39% to 0.67% from the reference temperatures provided by a superconducting reference point device calibrated against the Provisional Low Temperature Scale of 2000.
Energies of Screened Coulomb Potentials.
ERIC Educational Resources Information Center
Lai, C. S.
1979-01-01
This article shows that, by applying the Hellman-Feynman theorem alone to screened Coulomb potentials, the first four coefficients in the energy series in powers of the perturbation parameter can be obtained from the unperturbed Coulomb system. (Author/HM)
Coulomb blockade and Coulomb staircase behavior observed at room temperature
NASA Astrophysics Data System (ADS)
Uky Vivitasari, Pipit; Azuma, Yasuo; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka
2017-02-01
A single-electron transistor (SET) consists of source, drain, Coulomb island, and gate to modulate the number of electrons and control the current. For practical applications, it is important to operate a SET at room temperature. One proposal towards the ability to operate at room temperature is to decrease Coulomb island size down to a few nanometres. We investigate a SET using Sn-porphyrin (Sn-por) protected gold nanoparticles (AuNPs) with 1.4 nm in core diameter as a Coulomb island. The fabrication method of nanogap electrodes uses the combination of a top-down technique by electron beam lithography (EBL) and a bottom-up process through electroless gold plating (ELGP) as our group have described before. The electrical measurement was conducted at room temperature (300 K). From current–voltage (I d–V d) characteristics, we obtained clear Coulomb blockade phenomena together with a Coulomb staircase due to a Sn-por protected gold NP as a Coulomb island. Experimental results of I d–V d characteristics agree with a theoretical curve based on using the orthodox model. Clear dI d/dV d peaks are observed in the Coulomb staircase at 9 K which suggest the electron transports through excited energy levels of Au NPs. These results are a big step for obtaining SETs that can operate at room temperature.
Radiative capture versus Coulomb dissociation.
Esbensen, H.; Physics
2006-01-01
Measurements of the Coulomb dissociation of {sup 8}B have been used to infer the rate of the inverse radiative proton capture on {sup 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.
Relativistic Aharonov-Bohm effect in the presence of planar Coulomb potentials
Khalilov, V.R.
2005-01-01
Exact analytic solutions are found to the Dirac equation in 2+1 dimensions for a combination of an Aharonov-Bohm potential and the Lorentz three-vector and scalar Coulomb potentials. By means of the solutions obtained the relativistic quantum Aharonov-Bohm effect is studied for the free (in the presence of a Lorentz three-vector Coulomb potential) and bound fermion states. We obtain the total scattering amplitude in a combination of the Aharonov-Bohm and Lorentz three-vector Coulomb potentials as a sum of two scattering amplitudes. This modifies the expression for the standard Aharonov-Bohm cross section due to the interference of these two amplitudes with each other. We discuss that the observable quantities can be the phases of electron wave functions or the energies of bound states.
Interpolating the Coulomb phase of little string theory
Lin, Ying -Hsuan; Shao, Shu -Heng; Wang, Yifan; ...
2015-12-03
We study up to 8-derivative terms in the Coulomb branch effective action of (1,1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity onmore » the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k=2,3,4,5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. As a result, we also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.« less
Interpolating the Coulomb phase of little string theory
Lin, Ying -Hsuan; Shao, Shu -Heng; Wang, Yifan; Yin, Xi
2015-12-03
We study up to 8-derivative terms in the Coulomb branch effective action of (1,1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity on the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k=2,3,4,5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. As a result, we also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.
Ordering in classical Coulombic systems.
Schiffer, J. P.
1998-01-22
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 {Lambda} (the dimensionless ratio of the average two-particle Coulomb energy to the kinetic energy per particle) is larger than {approximately}175. 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].
Coulomb path'' interference in low energy He sup + + He collisions
Swenson, J.K. ); Burgdoerfer, J. ); Meyer, F.W.; Havener, C.C.; Gregory, D.C.; Stolterfoht, N. )
1990-01-01
A new interference mechanism, analogous to classic'' double-slit electron scattering, has been identified in low energy ion-atom collisions. This Coulomb path'' interference results from the existence of two trajectories, indistinguishable with respect to laboratory energy and emission angle, along which ejected autoionizing electrons may be scattered by the attractive Coulomb potential of the slowly receding spectator ion. We present a simple semi-classical model for this effect in which we account for the path dependence of the amplitude of the ejected electron following decay of the autoionizing state. Calculated model lineshapes are found to be in excellent agreement with strong angular dependence of the interference structure observed in the He target 2s{sup 2} {sup 1}S autoionizing lineshape measured near 0{degree} following 10 keV He{sup +} + He collisions.
Renormalization group analysis of graphene with a supercritical Coulomb impurity
NASA Astrophysics Data System (ADS)
Nishida, Yusuke
2016-08-01
We develop a field-theoretic approach to massless Dirac fermions in a supercritical Coulomb potential. By introducing an Aharonov-Bohm solenoid at the potential center, the critical Coulomb charge can be made arbitrarily small for one partial-wave sector, where a perturbative renormalization group analysis becomes possible. We show that a scattering amplitude for reflection of particle at the potential center exhibits the renormalization group limit cycle, i.e., log-periodic revolutions as a function of the scattering energy, revealing the emergence of discrete scale invariance. This outcome is further incorporated in computing the induced charge and current densities, which turn out to have power-law tails with coefficients log-periodic with respect to the distance from the potential center. Our findings are consistent with the previous prediction obtained by directly solving the Dirac equation and can in principle be realized by graphene experiments with charged impurities.
Revival of the Phase-Amplitude Description of a Quantum-Mechanical Wave Function
NASA Astrophysics Data System (ADS)
Rawitscher, George
2017-01-01
The phase-amplitude description of a wave function is formulated by means of a new linear differential-integral equation, which is valid in the region of turning points. A numerical example for a Coulomb potential is presented.
Coincidence Proportional Counter
Manley, J H
1950-11-21
A coincidence proportional counter having a plurality of collecting electrodes so disposed as to measure the range or energy spectrum of an ionizing particle-emitting source such as an alpha source, is disclosed.
PREFACE: Strongly Coupled Coulomb Systems Strongly Coupled Coulomb Systems
NASA Astrophysics Data System (ADS)
Neilson, David; Senatore, Gaetano
2009-05-01
This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS), held from 29 July-2 August 2008 at the University of Camerino. Camerino is an ancient hill-top town located in the Apennine mountains of Italy, 200 kilometres northeast of Rome, with a university dating back to 1336. The Camerino conference was the 11th in a series which started in 1977: 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (hosted by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (hosted by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, New York, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) 2005: Moscow, Russia (hosted by Vladimir E Fortov and Vladimir Vorob'ev). The name of the series was changed in 1996 from Strongly Coupled Plasmas to Strongly Coupled Coulomb Systems to reflect a wider range of topics. 'Strongly Coupled Coulomb Systems' encompasses diverse many-body systems and physical conditions. The purpose of the conferences is to provide a regular international forum for the presentation and discussion of research achievements and ideas relating to a variety of plasma, liquid and condensed matter systems that are dominated by strong Coulomb interactions between their constituents. Each meeting has seen an evolution of topics and emphases that have followed new discoveries and new techniques. The field has continued to see new experimental tools and access to new strongly coupled conditions, most recently in the areas of warm matter, dusty plasmas
NASA Astrophysics Data System (ADS)
Xiong, Liyang; Shi, Wenjia; Tang, Chao
2016-08-01
Adaptation is a ubiquitous feature in biological sensory and signaling networks. It has been suggested that adaptive systems may follow certain simple design principles across diverse organisms, cells and pathways. One class of networks that can achieve adaptation utilizes an incoherent feedforward control, in which two parallel signaling branches exert opposite but proportional effects on the output at steady state. In this paper, we generalize this adaptation mechanism by establishing a steady-state proportionality relationship among a subset of nodes in a network. Adaptation can be achieved by using any two nodes in the sub-network to respectively regulate the output node positively and negatively. We focus on enzyme networks and first identify basic regulation motifs consisting of two and three nodes that can be used to build small networks with proportional relationships. Larger proportional networks can then be constructed modularly similar to LEGOs. Our method provides a general framework to construct and analyze a class of proportional and/or adaptation networks with arbitrary size, flexibility and versatile functional features.
Selecting Proportional Reasoning Tasks
ERIC Educational Resources Information Center
de la Cruz, Jessica A.
2013-01-01
With careful consideration given to task selection, students can construct their own solution strategies to solve complex proportional reasoning tasks while the teacher's instructional goals are still met. Several aspects of the tasks should be considered including their numerical structure, context, difficulty level, and the strategies they are…
Regularized friction and continuation: Comparison with Coulomb's law
NASA Astrophysics Data System (ADS)
Vigué, Pierre; Vergez, Christophe; Karkar, Sami; Cochelin, Bruno
2017-02-01
Periodic solutions of systems with friction are difficult to investigate because of the non-smooth nature of friction laws. This paper examines periodic solutions and most notably stick-slip, on a simple one-degree-of-freedom system (mass, spring, damper, and 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 constructed step by step, which gives a usable existence condition. With the regularized law, the Asymptotic Numerical Method and the Harmonic Balance Method provide bifurcation diagrams with respect to the belt speed or normal force, and for several values of the regularization parameter. Formulations from the Coulomb case give the means of a comparison between regularized solutions and a standard reference. With an appropriate definition, regularized stick-slip motion exists, its amplitude increases with respect to the belt speed and its pulsation decreases with respect to the normal force.
Coulomb-dominated low-energy deuteron stripping
Austern, N. )
1991-02-01
Analysis of a three-body model shows that Coulomb polarization of the deuteron has very little influence on the branching ratio {ital A}({ital d},{ital p})/{ital A}({ital d},{ital n}) for transfer reactions on target nucleus {ital A} at very low deuteron energies (the Oppenheimer-Phillips effect). We see that polarization effects in transfer reactions are not related to the long range of the Coulomb field, but are caused by the more intense fields near the target nucleus. However, even in that region the induced dipole moment is limited by the deuteron binding, and it is small for low {ital Z} targets. We see in addition that the transfer amplitudes tend to be {ital insensitive} to any polarization admixtures in the entrance channel. On the other hand, the branching ratio can be affected by the Coulomb barrier for the bound final-state wave function of the proton, especially for very weakly bound final states. Brief remarks about the relation of stripping theory to special properties of the {ital d}+{ital d} system are included.
Multiwire proportional chamber development
NASA Technical Reports Server (NTRS)
Doolittle, R. F.; Pollvogt, U.; Eskovitz, A. J.
1973-01-01
The development of large area multiwire proportional chambers, to be used as high resolution spatial detectors in cosmic ray experiments is described. A readout system was developed which uses a directly coupled, lumped element delay-line whose characteristics are independent of the MWPC design. A complete analysis of the delay-line and the readout electronic system shows that a spatial resolution of about 0.1 mm can be reached with the MWPC operating in the strictly proportional region. This was confirmed by measurements with a small MWPC and Fe-55 X-rays. A simplified analysis was carried out to estimate the theoretical limit of spatial resolution due to delta-rays, spread of the discharge along the anode wire, and inclined trajectories. To calculate the gas gain of MWPC's of different geometrical configurations a method was developed which is based on the knowledge of the first Townsend coefficient of the chamber gas.
PREFACE: Strongly Coupled Coulomb Systems
NASA Astrophysics Data System (ADS)
Fortov, Vladimir E.; Golden, Kenneth I.; Norman, Genri E.
2006-04-01
This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS) which was held during the week of 20 24 June 2005 in Moscow, Russia. The Moscow conference was the tenth in a series of conferences. The previous conferences were organized as follows. 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (organized by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (organized by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, NY, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) After 1995 the name of the series was changed from `Strongly Coupled Plasmas' to the present name in order to extend the topics of the conferences. The planned frequency for the future is once every three years. The purpose of these conferences is to provide an international forum for the presentation and discussion of research accomplishments and ideas relating to a variety of plasma liquid and condensed matter systems, dominated by strong Coulomb interactions between their constituents. Strongly coupled Coulomb systems encompass diverse many-body systems and physical conditions. Each meeting has seen an evolution of topics and emphasis as new discoveries and new methods appear. This year, sessions were organized for invited presentations and posters on dense plasmas and warm matter, astrophysics and dense hydrogen, non-neutral and ultracold plasmas, dusty plasmas, condensed matter 2D and layered charged-particle systems, Coulomb liquids, and statistical theory of SCCS. Within
Coulombic contribution and fat center vortex model
Rafibakhsh, Shahnoosh; Deldar, Sedigheh
2007-02-27
The fat (thick) center vortex model is one of the phenomenological models which is fairly successful to interpret the linear potential between static sources. However, the Coulombic part of the potential has not been investigated by the model yet. In an attempt to get the Coulombic contribution and to remove the concavity of the potentials, we are studying different vortex profiles and vortex sizes.
Coulomb-interaction-dependent effect of high-order sideband generation in an optomechanical system
NASA Astrophysics Data System (ADS)
Kong, Cui; Xiong, Hao; Wu, Ying
2017-03-01
High-order sideband generation in an optomechanical system coupled to a charged object is discussed, and the features of Coulomb-interaction-dependent effect are identified. We show that the Coulomb-interaction-dependent effect of high-order sideband generation exhibits essential difference between the case of weak control field and strong control field. In the weak control field case, the output spectra are in the perturbative regime and there is hardly any Coulomb-interaction-dependent effect in an optomechanical system coupling to an object with a small amount of charge. In the strong control field case, the output spectra are in the nonperturbative regime and robust Coulomb-interaction-dependent effect arises even if there are few charges. The amplitudes of specific sidebands are also discussed, and it is shown that Coulomb interaction plays an important role in achieving optomechanical control. Due to the extremely sensitive charge number, the Coulomb-interaction-dependent effect of high-order sideband generation is remarkable in many aspects and may be used to precision measurement of electrical charges beyond the linearized optomechanical interaction.
The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.
ERIC Educational Resources Information Center
Francisco, E.; And Others
1988-01-01
Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)
Proportional counter radiation camera
Borkowski, C.J.; Kopp, M.K.
1974-01-15
A gas-filled proportional counter camera that images photon emitting sources is described. A two-dimensional, positionsensitive proportional multiwire counter is provided as the detector. The counter consists of a high- voltage anode screen sandwiched between orthogonally disposed planar arrays of multiple parallel strung, resistively coupled cathode wires. Two terminals from each of the cathode arrays are connected to separate timing circuitry to obtain separate X and Y coordinate signal values from pulse shape measurements to define the position of an event within the counter arrays which may be recorded by various means for data display. The counter is further provided with a linear drift field which effectively enlarges the active gas volume of the counter and constrains the recoil electrons produced from ionizing radiation entering the counter to drift perpendicularly toward the planar detection arrays. A collimator is interposed between a subject to be imaged and the counter to transmit only the radiation from the subject which has a perpendicular trajectory with respect to the planar cathode arrays of the detector. (Official Gazette)
PULSE AMPLITUDE DISTRIBUTION RECORDER
Cowper, G.
1958-08-12
A device is described for automatica1ly recording pulse annplitude distribution received from a counter. The novelty of the device consists of the over-all arrangement of conventional circuit elements to provide an easy to read permanent record of the pulse amplitude distribution during a certain time period. In the device a pulse analyzer separates the pulses according to annplitude into several channels. A scaler in each channel counts the pulses and operates a pen marker positioned over a drivable recorder sheet. Since the scalers in each channel have the sanne capacity, the control circuitry permits counting of the incoming pulses until one scaler reaches capacity, whereupon the input is removed and an internal oscillator supplies the necessary pulses to fill up the other scalers. Movement of the chart sheet is initiated wben the first scaler reaches capacity to thereby give a series of marks at spacings proportional to the time required to fill the remaining scalers, and accessory equipment marks calibration points on the recorder sheet to facilitate direct reading of the number of external pulses supplied to each scaler.
The microstrip proportional counter
NASA Technical Reports Server (NTRS)
Ramsey, B. D.
1992-01-01
Microstrip detectors in which the usual discrete anode and cathode wires are replaced by conducting strips on an insulating or partially insulating substrate are fabricated using integrated circuit-type photolithographic techniques and hence offer very high spatial accuracy and uniformity, together with the capability of producing extremely fine electrode structures. Microstrip proportional counters have now been variously reported having an energy resolution of better than 11 percent FWHM at 5.9 keV. They have been fabricated with anode bars down to 2 microns and on a variety of substrate materials including thin films which can be molded to different shapes. This review will examine the development of the microstrip detector with emphasis on the qualities which make this detector particularly interesting for use in astronomy.
Gated strip proportional detector
Morris, Christopher L.; Idzorek, George C.; Atencio, Leroy G.
1987-01-01
A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10.sup.6. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.
Gated strip proportional detector
Morris, C.L.; Idzorek, G.C.; Atencio, L.G.
1985-02-19
A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10/sup 6/. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.
Numerical approach to Coulomb gauge QCD
Matevosyan, Hrayr H.; Szczepaniak, Adam P.; Bowman, Patrick O.
2008-07-01
We calculate the ghost two-point function in Coulomb gauge QCD with a simple model vacuum gluon wave function using Monte Carlo integration. This approach extends the previous analytic studies of the ghost propagator with this ansatz, where a ladder-rainbow expansion was unavoidable for calculating the path integral over gluon field configurations. The new approach allows us to study the possible critical behavior of the coupling constant, as well as the Coulomb potential derived from the ghost dressing function. We demonstrate that IR enhancement of the ghost correlator or Coulomb form factor fails to quantitatively reproduce confinement using Gaussian vacuum wave functional.
Pore fluid pressure, apparent friction, and Coulomb failure
Beeler, N.M.; Simpson, R.W.; Hickman, S.H.; Lockner, D.A.
2000-01-01
Many recent studies of stress-triggered seismicity rely on a fault failure model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ≤ μ′ ≤ 1. These studies may present a misleading view of fault strength and the role of pore fluid pressure in earthquake failure. The parameter μ′ is intended to incorporate the effects of both friction and pore pressure, but is a material constant only if changes in pore fluid pressure induced by changes in stress are proportional to the normal stress change across the potential failure plane. Although specific models of fault zones permit such a relation, neither is it known that fault zones within the Earth behave this way, nor is this behavior expected in all cases. In contrast, for an isotropic homogeneous poroelastic model the pore pressure changes are proportional to changes in mean stress, μ′ is not a material constant, and −∞ ≤ μ′ ≤ +∞. Analysis of the change in Coulomb failure stress for tectonically loaded reverse and strike-slip faults shows considerable differences between these two pore pressure models, suggesting that such models might be distinguished from one another using observations of triggered seismicity (e.g., aftershocks). We conclude that using the constant apparent friction model exclusively in studies of Coulomb failure stress is unwise and could lead to significant errors in estimated stress change and seismic hazard.
Low rank factorization of the Coulomb integrals for periodic coupled cluster theory
NASA Astrophysics Data System (ADS)
Hummel, Felix; Tsatsoulis, Theodoros; Grüneis, Andreas
2017-03-01
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 (N4) 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.
Crystallization in two-component Coulomb systems.
Bonitz, M; Filinov, V S; Fortov, V E; Levashov, P R; Fehske, H
2005-12-02
The analysis of Coulomb crystallization is extended from one-component to two-component plasmas. Critical parameters for the existence of Coulomb crystals are derived for both classical and quantum crystals. In the latter case, a critical mass ratio of the two charged components is found, which is of the order of 80. Thus, holes in semiconductors with sufficiently flat valence bands are predicted to spontaneously order into a regular lattice. Such hole crystals are intimately related to ion Coulomb crystals in white dwarf and neutron stars as well as to ion crystals produced in the laboratory. A unified phase diagram of two-component Coulomb crystals is presented and is verified by first-principles computer simulations.
Recent developments in Coulomb breakup calculations
Capel, P.
2008-05-12
The theory of reactions applied to Coulomb breakup of loosely-bound projectiles is reviewed. Both the Continuum Discretized Coupled Channel (CDCC) and time-dependent models are described. Recent results about sensitivity of breakup calculations to the projectile wave function are reviewed. Analyses of the extraction of radiative-capture cross section from Coulomb breakup measurements are presented. Current developments in breakup theory are also mentioned.
Off-shell Jost solutions for Coulomb and Coulomb-like interactions in all partial waves
Laha, U.; Bhoi, J.
2013-01-15
By exploiting the theory of ordinary differential equations, with judicious use of boundary conditions, interacting Green's functions and their integral transforms together with certain properties of higher transcendental functions, useful analytical expressions for the off-shell Jost solutions for motion in Coulomb and Coulomb-nuclear potentials are derived in maximal reduced form through different approaches to the problem in the representation space. The exact analytical expressions for the off-shell Jost solutions for Coulomb and Coulomb-like potentials are believed to be useful for the description of the charged particle scattering/reaction processes.
Amplitude- and rise-time-compensated filters
Nowlin, Charles H.
1984-01-01
An amplitude-compensated rise-time-compensated filter for a pulse time-of-occurrence (TOOC) measurement system is disclosed. The filter converts an input pulse, having the characteristics of random amplitudes and random, non-zero rise times, to a bipolar output pulse wherein the output pulse has a zero-crossing time that is independent of the rise time and amplitude of the input pulse. The filter differentiates the input pulse, along the linear leading edge of the input pulse, and subtracts therefrom a pulse fractionally proportional to the input pulse. The filter of the present invention can use discrete circuit components and avoids the use of delay lines.
Treatment of the two-body Coulomb problem as a short-range potential
NASA Astrophysics Data System (ADS)
Gasaneo, G.; Ancarani, L. U.
2009-12-01
The scattering wave function and the transition amplitude for the two-body Coulomb problem are written as power series of the Sommerfeld parameter. Making use of a mathematical study of the nth derivatives of Kummer function with respect to its first parameter, the series coefficients are expressed analytically in terms of multivariable hypergeometric functions. We establish the connection with the Born series based on the free particle Green’s function and show its applicability to long-range potentials. We also relate our analysis to recent works on the distorted-wave theory for the Coulomb problem. For the transition amplitude, the Born series is presented and compared to the series obtained from the exact well-known Rutherford result. Since the two series differ, care must be taken when extracting the relevant information about the scattering. Finally, implications for three-body problems are discussed.
Quantum mechanics on phase space and the Coulomb potential
NASA Astrophysics Data System (ADS)
Campos, P.; Martins, M. G. R.; Vianna, J. D. M.
2017-04-01
Symplectic quantum mechanics (SMQ) makes possible to derive the Wigner function without the use of the Liouville-von Neumann equation. In this formulation of the quantum theory the Galilei Lie algebra is constructed using the Weyl (or star) product with Q ˆ = q ⋆ = q +iħ/2∂p , P ˆ = p ⋆ = p -iħ/2∂q, and the Schrödinger equation is rewritten in phase space; in consequence physical applications involving the Coulomb potential present some specific difficulties. Within this context, in order to treat the Schrödinger equation in phase space, a procedure based on the Levi-Civita (or Bohlin) transformation is presented and applied to two-dimensional (2D) hydrogen atom. Amplitudes of probability in phase space and the correspondent Wigner quasi-distribution functions are derived and discussed.
Dynamic stresses, coulomb failure, and remote triggering: corrected
Hill, David P.
2012-01-01
Dynamic stresses associated with crustal surface waves with 15–30 s periods and peak amplitudes <1 MPa are capable of triggering seismicity at sites remote from the generating mainshock under appropriate conditions. Coulomb failure models based on a frictional strength threshold offer one explanation for instances of rapid‐onset triggered seismicity that develop during the surface‐wave peak dynamic stressing. Evaluation of the triggering potential of surface‐wave dynamic stresses acting on critically stressed faults using a Mohr’s circle representation together with the Coulomb failure criteria indicates that Love waves should have a higher triggering potential than Rayleigh waves for most fault orientations and wave incidence angles. That (1) the onset of triggered seismicity often appears to begin during the Rayleigh wave rather than the earlier arriving Love wave, and (2) Love‐wave amplitudes typically exceed those for Rayleigh waves suggests that the explanation for rapid‐onset dynamic triggering may not reside solely with a simple static‐threshold friction mode. The results also indicate that normal faults should be more susceptible to dynamic triggering by 20‐s Rayleigh‐wave stresses than thrust faults in the shallow seismogenic crust (<10 km) while the advantage tips in favor of reverse faults greater depths. This transition depth scales with wavelength and coincides roughly with the transition from retrograde‐to‐prograde particle motion. Locally elevated pore pressures may have a role in the observed prevalence of dynamic triggering in extensional regimes and geothermal/volcanic systems. The result is consistent with the apparent elevated susceptibility of extensional or transtensional tectonic regimes to remote triggering by Rayleigh‐wave dynamic stresses than compressional or transpressional regimes.
Visual Manipulatives for Proportional Reasoning.
ERIC Educational Resources Information Center
Moore, Joyce L.; Schwartz, Daniel L.
The use of a visual representation in learning about proportional relations was studied, examining students' understandings of the invariance of a multiplicative relation on both sides of a proportion equation and the invariance of the structural relations that exist in different semantic types of proportion problems. Subjects were 49 high-ability…
Coulomb wave functions in momentum space
Eremenko, V.; Upadhyay, N. J.; Thompson, I. J.; ...
2015-10-15
We present an algorithm to calculate non-relativistic partial-wave Coulomb functions in momentum space. The arguments are the Sommerfeld parameter η, the angular momentum l, the asymptotic momentum q and the 'running' momentum p, where both momenta are real. Since the partial-wave Coulomb functions exhibit singular behavior when p → q, different representations of the Legendre functions of the 2nd kind need to be implemented in computing the functions for the values of p close to the singularity and far away from it. The code for the momentum-space Coulomb wave functions is applicable for values of vertical bar eta vertical barmore » in the range of 10-1 to 10, and thus is particularly suited for momentum space calculations of nuclear reactions.« less
Coulomb wave functions in momentum space
Eremenko, V.; Upadhyay, N. J.; Thompson, I. J.; Elster, Ch.; Nunes, F. M.; Arbanas, G.; Escher, J. E.; Hlophe, L.
2015-10-15
We present an algorithm to calculate non-relativistic partial-wave Coulomb functions in momentum space. The arguments are the Sommerfeld parameter η, the angular momentum l, the asymptotic momentum q and the 'running' momentum p, where both momenta are real. Since the partial-wave Coulomb functions exhibit singular behavior when p → q, different representations of the Legendre functions of the 2nd kind need to be implemented in computing the functions for the values of p close to the singularity and far away from it. The code for the momentum-space Coulomb wave functions is applicable for values of vertical bar eta vertical bar in the range of 10^{-1} to 10, and thus is particularly suited for momentum space calculations of nuclear reactions.
Observation of ionic Coulomb blockade in nanopores
NASA Astrophysics Data System (ADS)
Feng, Jiandong; Liu, Ke; Graf, Michael; Dumcenco, Dumitru; Kis, Andras; di Ventra, Massimiliano; Radenovic, Aleksandra
2016-08-01
Emergent behaviour from electron-transport properties is routinely observed in systems with dimensions approaching the nanoscale. However, analogous mesoscopic behaviour resulting from ionic transport has so far not been observed, most probably because of bottlenecks in the controlled fabrication of subnanometre nanopores for use in nanofluidics. Here, we report measurements of ionic transport through a single subnanometre pore junction, and the observation of ionic Coulomb blockade: the ionic counterpart of the electronic Coulomb blockade observed for quantum dots. Our findings demonstrate that nanoscopic, atomically thin pores allow for the exploration of phenomena in ionic transport, and suggest that nanopores may also further our understanding of transport through biological ion channels.
Three-body Coulomb continuum problem
NASA Astrophysics Data System (ADS)
Berakdar, J.; Briggs, J. S.
1994-06-01
A symmetric representation of the three-body Coulomb continuum wave function as a product of three two-body Coulomb wave functions is modified to allow for three-body effects whereby the Sommerfeld parameter describing the strength of interaction of any two particles is affected by the presence of the third particle. This approach gives excellent agreement with near-threshold absolute (e,2e) ionization cross sections. In particular a recently observed deep minimum in noncoplanar geometry is reproduced for the first time.
Coulomb string tension, asymptotic string tension, and the gluon chain
Greensite, Jeff; Szczepaniak, Adam P.
2015-02-01
We compute, via numerical simulations, the non-perturbative Coulomb potential and position-space ghost propagator in 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.
Coulomb drag between helical Luttinger liquids
NASA Astrophysics Data System (ADS)
Kainaris, N.; Gornyi, I. V.; Levchenko, A.; Polyakov, D. G.
2017-01-01
We theoretically study Coulomb drag between two helical edges with broken spin-rotational symmetry, such as would occur in two capacitively coupled quantum spin Hall insulators. For the helical edges, Coulomb drag is particularly interesting because it specifically probes the inelastic interactions that break the conductance quantization for a single edge. Using the kinetic equation formalism, supplemented by bosonization, we find that the drag resistivity ρD exhibits a nonmonotonic dependence on the temperature T . In the limit of low T ,ρD vanishes with decreasing T as a power law if intraedge interactions are not too strong. This is in stark contrast to Coulomb drag in conventional quantum wires, where ρD diverges at T →0 irrespective of the strength of repulsive interactions. Another unusual property of Coulomb drag between the helical edges concerns higher T for which, unlike in the Luttinger liquid model, drag is mediated by plasmons. The special type of plasmon-mediated drag can be viewed as a distinguishing feature of the helical liquid—because it requires peculiar umklapp scattering only available in the presence of a Dirac point in the electron spectrum.
Electric-hexadecapole (24-pole) Coulomb integrals
NASA Astrophysics Data System (ADS)
Chidichimo, Marita C.; Stastna, Marek
1996-03-01
We obtain the quantal zero-energy-loss limit of the radial integrals arising in the nonrelativistic atomic excitation of electric-hexadecapole transitions. We compare these results to the classical limit and the WKB approximation. We show the different behavior of the Coulomb integrals in the WKB approximation in the cases of repulsive and attractive potentials as functions of the Sommerfeld number η.
Solution of Coulomb system in momentum space
Lin, D.-H.
2008-02-15
The solution of D-dimensional Coulomb system is solved in momentum space by path integral. From which the topological effect of a magnetic flux in the system is given. It is revealed that the flux effect represented by the two-dimensional field of Aharonov-Bohm covers any space-dimensions.
Coulomb Logarithm, Version 1.0
Singleton, Robert
2016-11-23
Clog is a library of charged particle stopping powers and related Coulomb logarithm processes in a plasma. The stopping power is a particularly useful quantity for plasma physics, as it measures the energy loss of per unit length of charged particle as it traverses a plasma. Clog's primary stopping power is the BPS (Brown-Preston-Singleton) theory.
Greenblatt, M.H.
1958-03-25
This patent pertains to pulse amplitude analyzers for sorting and counting a serles of pulses, and specifically discloses an analyzer which ls simple in construction and presents the puise height distribution visually on an oscilloscope screen. According to the invention, the pulses are applied to the vertical deflection plates of an oscilloscope and trigger the horizontal sweep. Each pulse starts at the same point on the screen and has a maximum amplitude substantially along the same vertical line. A mask is placed over the screen except for a slot running along the line where the maximum amplitudes of the pulses appear. After the slot has been scanned by a photocell in combination with a slotted rotating disk, the photocell signal is displayed on an auxiliary oscilloscope as vertical deflection along a horizontal time base to portray the pulse amplitude distribution.
Real topological string amplitudes
NASA Astrophysics Data System (ADS)
Narain, K. S.; Piazzalunga, N.; Tanzini, A.
2017-03-01
We discuss the physical superstring correlation functions in type I theory (or equivalently type II with orientifold) that compute real topological string amplitudes. We consider the correlator corresponding to holomorphic derivative of the real topological amplitude G_{χ } , at fixed worldsheet Euler characteristic χ. This corresponds in the low-energy effective action to N=2 Weyl multiplet, appropriately reduced to the orientifold invariant part, and raised to the power g' = -χ + 1. We show that the physical string correlator gives precisely the holomorphic derivative of topological amplitude. Finally, we apply this method to the standard closed oriented case as well, and prove a similar statement for the topological amplitude F_g.
Multiple Ways to Solve Proportions
ERIC Educational Resources Information Center
Ercole, Leslie K.; Frantz, Marny; Ashline, George
2011-01-01
When solving problems involving proportions, students may intuitively draw on strategies that connect to their understanding of fractions, decimals, and percents. These two statements--"Instruction in solving proportions should include methods that have a strong intuitive basis" and "Teachers should begin instruction with more intuitive…
Proportional Reasoning as Essential Numeracy
ERIC Educational Resources Information Center
Dole, Shelley; Hilton, Annette; Hilton, Geoff
2015-01-01
This paper reports an aspect of a large research and development project that aimed to promote middle years school teachers' understanding and awareness of the pervasiveness of proportional reasoning as integral to numeracy. Teacher survey data of proportional reasoning across the curriculum were mapped on to a rich model of numeracy. Results…
Cotunneling Drag Effect in Coulomb-Coupled Quantum Dots
NASA Astrophysics Data System (ADS)
Keller, A. J.; Lim, J. S.; Sánchez, David; López, Rosa; Amasha, S.; Katine, J. A.; Shtrikman, Hadas; Goldhaber-Gordon, D.
2016-08-01
In Coulomb drag, a current flowing in one conductor can induce a voltage across an adjacent conductor via the Coulomb interaction. The mechanisms yielding drag effects are not always understood, even though drag effects are sufficiently general to be seen in many low-dimensional systems. In this Letter, we observe Coulomb drag in a Coulomb-coupled double quantum dot and, through both experimental and theoretical arguments, identify cotunneling as essential to obtaining a correct qualitative understanding of the drag behavior.
Theoretical Investigation of a Proportional-Plus-Flicker Automatic Pilot
NASA Technical Reports Server (NTRS)
Seaberg, Ernest C.
1950-01-01
The proportional-plus-flicker automatic pilot operates by a nonlinear principle whereby a fast-acting flicker servomotor response is combined with a low-speed proportional servomotor response for the purpose of obtaining supersonic stability and control. Essentially, the autopilot maintains a zero reference about which the output is proportional to the input. However, a flicker response overrides this proportional response at a fixed angle of gimbal displacement on either side of the zero gyroscope reference. Therefore, in contrast to other high speed control systems, the design requirements are simplified because the two components of the proportional-flicker control system are easy to build separately and they can be combined in a relatively simple manner. By application of the proportional-flicker principle, satisfactory stability can be obtained by the proper adjustment of the variable factors in the autopilot mechanism; namely, the proportional gain, the amplitude of flicker control deflection, the autopilot time-lag factor (the time-lag between flicker and proportional operation), and the point in the range that the autopilot switches from a flicker to a proportional system. There is a possibility that these factors can be adjusted so that a more rapid response time (the time to reach steady state) is obtained with the non-linear proportional-flicker autopilot than with a purely linear proportional autopilot. For the main part of this analysis, the proportional part of the system is approximated by a zero-phase-lag proportional autopilot with the assumption that the control surface moves instantaneously at the point where the system switches from flicker to proportional. Good correlation is shown between the results obtained by this method and results obtained by using a close approximation of an actual autopilot transfer function for proportional autopilot operation.
Protostring scattering amplitudes
NASA Astrophysics Data System (ADS)
Thorn, Charles B.
2016-11-01
We calculate some tree-level scattering amplitudes for a generalization of the protostring, which is a novel string model implied by the simplest string bit models. These bit models produce a light-cone world sheet which supports s integer moded Grassmann fields. In the generalization we supplement this Grassmann world-sheet system with d =24 -s transverse coordinate world-sheet fields. The protostring corresponds to s =24 and the bosonic string to s =0 . The interaction vertex is a simple overlap with no operator insertions at the break/join point. Assuming that s is even we calculate the multistring scattering amplitudes by bosonizing the Grassmann fields, each pair equivalent to one compactified bosonic field, and applying Mandelstam's interacting string formalism to a system of s /2 compactified and d uncompactified bosonic world-sheet fields. We obtain all amplitudes for open strings with no oscillator excitations and for closed strings with no oscillator excitations and zero winding number. We then study in detail some simple special cases. Multistring processes with maximal helicity violation have much simpler amplitudes. We also specialize to general four-string amplitudes and discuss their high energy behavior. Most of these models are not covariant under the full Lorentz group O (d +1 ,1 ). The exceptions are the bosonic string whose Lorentz group is O (25 ,1 ) and the protostring whose Lorentz group is O (1 ,1 ). The models in between only enjoy an O (1 ,1 )×O (d ) spacetime symmetry.
Coulomb Bound States of Strongly Interacting Photons
NASA Astrophysics Data System (ADS)
Maghrebi, M. F.; Gullans, M. J.; Bienias, P.; Choi, S.; Martin, I.; Firstenberg, O.; Lukin, M. D.; Büchler, H. P.; Gorshkov, A. V.
2015-09-01
We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasibound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wave function resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.
Feynman rules for Coulomb gauge QCD
Andrasi, A.; Taylor, J.C.
2012-10-15
The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ-Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the sub-graph structure of ordinary Feynman graphs. The CL terms do not have a sub-graph structure. We show how to carry out renormalization in the presence of CL terms, by re-expressing these as 'pseudo-Feynman' integrals. We also explain how energy divergences cancel. - Highlights: Black-Right-Pointing-Pointer In Coulomb gauge QCD, we re-express Christ-Lee terms in the Hamiltonian as pseudo-Feynman integrals. Black-Right-Pointing-Pointer This gives a subgraph structure, and allows the ordinary renormalization process. Black-Right-Pointing-Pointer It also leads to cancellation of energy-divergences.
Coulomb edge effects in graphene nanoribbons
NASA Astrophysics Data System (ADS)
Jaskolski, W.; Ayuela, A.
2014-10-01
Coulomb effects in graphene nanoribbons with arbitrary edges are investigated with the use of a mean-field Hubbard model. It was recently shown that chiral ribbons with minimal edges, characterized by the translation vector (n,m), have a similar structure of bands localized around the Fermi energy as pure zigzag ribbons (n-m,0). Here we show that these flat bands in both ribbon cases differ in detail due to the perturbation induced by armchair edge nodes. For chiral ribbons the edge bands split at the zone boundary, where the corresponding bands of (n-m,0) zigzag ribbons are degenerate. Coulomb interactions enhance strongly this splitting and at the same time they bring spin into play. We modify each edge keeping global sublattice balance to find that spin degeneracy can be partially lifted. The breaking of spin-degeneracy depends on the asymmetry between the edges and in some cases leads to spin-polarized currents.
Coulomb crystallization of highly charged ions.
Schmöger, L; Versolato, O O; Schwarz, M; Kohnen, M; Windberger, A; Piest, B; Feuchtenbeiner, S; Pedregosa-Gutierrez, J; Leopold, T; Micke, P; Hansen, A K; Baumann, T M; Drewsen, M; Ullrich, J; Schmidt, P O; López-Urrutia, J R Crespo
2015-03-13
Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically (40)Ar(13+)) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be(+) ions. We also demonstrate cooling of a single Ar(13+) ion by a single Be(+) ion-the prerequisite for quantum logic spectroscopy with a potential 10(-19) accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.
Coulomb impurities in two-dimensional topological insulators
NASA Astrophysics Data System (ADS)
Zhu, Jia-Lin; Li, Guo; Yang, Ning
2017-03-01
Introducing a powerful method, we obtain the exact solutions for a Coulomb impurity in two-dimensional infinite and finite topological insulators. The level order and zero-energy degeneracy of the spectra are found to be quite different between topological trivial and nontrivial phases. For quantum dots of topological insulator, the variation of the edge and Coulomb states with dot size, Coulomb potential, and magnetic field are clearly shown. It is found that for small dots the edge states can be strongly coupled with the Coulomb states and for large dots the edge states are insensitive to the Coulomb fields but sensitive to the magnetic fields.
Coulomb interaction on spin-1 particles
NASA Astrophysics Data System (ADS)
Owen, D. A.; Barrett, R. C.
2003-11-01
Using the electro-weak theory, we find the lowest order perturbative correction to a spin-1 particle in an external Coulomb field. We show this leads to a correction of order (Zα)4 and is independent of the mass of the external field. Previous work with Duffin-Kemmer-Petiau (see Nedjadi and Barrett [J. Math. Phys. 35 (1994) 4517]) and the Proca equation has failed to produce this correction.
Generalized oscillator strength and Coulomb excitation
NASA Astrophysics Data System (ADS)
Chidichimo, Marita C.; Thorsley, Michael D.
2003-02-01
Coulomb interaction is characterized by two nondimensional fundamental quantities: the Sommerfeld parameter η and the adiabaticity parameter ξ=ηf-ηi. In this different approach, we choose these variables to describe the behavior of the generalized oscillator strength (GOS). The expression we obtain is valid for scattering of electrons, positrons, and nuclei by arbitrary targets. We present asymptotic expansions, in the quantal and semiclassical approximation, of the electric dipole GOS.
Thermoelectrics with Coulomb-coupled quantum dots
NASA Astrophysics Data System (ADS)
Thierschmann, Holger; Sánchez, Rafael; Sothmann, Björn; Buhmann, Hartmut; Molenkamp, Laurens W.
2016-12-01
In this article we review the thermoelectric properties of three terminal devices with Coulomb-coupled quantum dots (QDs) as observed in recent experiments [1,2]. The system we consider consists of two Coulomb-blockade QDs, one of which can exchange electrons with only a single reservoir (heat reservoir), while the other dot is tunnel coupled with two reservoirs at a lower temperature (conductor). The heat reservoir and the conductor interact only via the Coulomb coupling of the quantum dots. It has been found that two regimes have to be considered. In the first one, the heat flow between the two systems is small. In this regime, thermally driven occupation fluctuations of the hot QD modify the transport properties of the conductor system. This leads to an effect called thermal gating. Experiments have shown how this can be used to control charge flow in the conductor by means of temperature in a remote reservoir. We further substantiate the observations with model calculations, and implications for the realisation of an all-thermal transistor are discussed. In the second regime, the heat flow between the two systems is relevant. Here the system works as a nanoscale heat engine, as proposed recently (Sánchez and Büttiker [3]). We review the conceptual idea, its experimental realisation and the novel features arising in this new kind of thermoelectric device such as decoupling of heat and charge flow. xml:lang="fr"
Feng Bo
2007-11-20
In this talk, we will present recent progresses in perturbative calculations of scattering amplitudes at tree and one-loop levels. At tree level, we will discuss MHV-diagram method and on-shell recursion relation. At one-loop level, we will establish the framework of Unitarity cut method.
Reinforcing Saccadic Amplitude Variability
ERIC Educational Resources Information Center
Paeye, Celine; Madelain, Laurent
2011-01-01
Saccadic endpoint variability is often viewed as the outcome of neural noise occurring during sensorimotor processing. However, part of this variability might result from operant learning. We tested this hypothesis by reinforcing dispersions of saccadic amplitude distributions, while maintaining constant their medians. In a first experiment we…
Planar amplitude ammonia sensor
NASA Astrophysics Data System (ADS)
Karasinski, Pawel; Rogozinski, Roman
2004-09-01
The paper presents the results of investigation involving the influence of the change of launching conditions on the characteristics of amplitude ammonia sensors produced with the application of strip waveguides of different refractive profiles. Strip waveguides were produced using ion exchange technique, and the absorption sensitive films were produced using sol-gel technology.
Ultrafast dynamics of Coulomb correlated excitons in GaAs quantum wells
Mycek, M.A. |
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.
Bayesian Inference on Proportional Elections
Brunello, Gabriel Hideki Vatanabe; Nakano, Eduardo Yoshio
2015-01-01
Polls for majoritarian voting systems usually show estimates of the percentage of votes for each candidate. However, proportional vote systems do not necessarily guarantee the candidate with the most percentage of votes will be elected. Thus, traditional methods used in majoritarian elections cannot be applied on proportional elections. In this context, the purpose of this paper was to perform a Bayesian inference on proportional elections considering the Brazilian system of seats distribution. More specifically, a methodology to answer the probability that a given party will have representation on the chamber of deputies was developed. Inferences were made on a Bayesian scenario using the Monte Carlo simulation technique, and the developed methodology was applied on data from the Brazilian elections for Members of the Legislative Assembly and Federal Chamber of Deputies in 2010. A performance rate was also presented to evaluate the efficiency of the methodology. Calculations and simulations were carried out using the free R statistical software. PMID:25786259
Comparison of hard-cylinder and screened Coulomb interactions in the modeling of supercoiled DNAs.
Delrow, J J; Gebe, J A; Schurr, J M
1997-10-05
A 1000 base pair (bp) model supercoiled DNA is simulated using spherical screened Coulomb interactions between subunits on one hand and equivalent hard-cylinder interactions on the other. The amplitudes, or effective charges, of the spherical screened Coulomb electrostatic potentials are chosen so that the electrostatic potential surrounding the middle of a linear array of 2001 subunits (31.8 A diameter) closely matches the solution of the nonlinear Poisson-Boltzmann equation for a cylinder with 12 A radius and the full linear charge density of DNA at all distances beyond the 24 A hard-core diameter. This superposition of spherical screened Coulomb potentials is practically identical to the particular solution of the cylindrical linearized Poisson-Boltzmann equation that matches the solution of the nonlinear Poisson-Boltzmann equation at large distances. The interaction energy between subunits is reckoned from the effective charges according to the standard DLVO expression. The equivalent hard-cylinder diameter is chosen following Stigter's protocol for matching second virial coefficients, but for the full linear charge density of DNA. The electrostatic persistence length of the model with screened Coulomb interactions is extremely sensitive to the (arbitrarily) chosen subunit length at the higher salt concentrations. The persistence length of the hard-cylinder model is adjusted to match that of the screened Coulomb model for each ionic condition. Simulations for a superhelix density sigma = -0.05 using a spherical screened Coulomb interaction plus a 24 A hard-cylinder core (SCPHC) potential indicate that the radius of gyration of this 1000 bp DNA actually undergoes a slight increase as the NaCl concentration is raised from 0.01 to 1.0M. Thus, merely softening the potential from hard-cylinder to screened Coulomb form does not produce a large decrease in radius of gyration with increasing NaCl concentration for DNAs of this size. Radii of gyration, static structure
Weak boson production amplitude zeros; equalities of the helicity amplitudes
NASA Astrophysics Data System (ADS)
Mamedov, Fizuli
2002-08-01
We investigate the radiation amplitude zeros exhibited by many standard model amplitudes for triple weak gauge boson production processes. We show that WZγ production amplitudes have an especially rich structure in terms of zeros; these amplitudes have zeros originating from several different sources. It is also shown that the type-I current null zone is the special case of the equality of the specific helicity amplitudes.
Off-energy-shell p-p scattering at sub-Coulomb energies via the Trojan horse method
NASA Astrophysics Data System (ADS)
Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A.; Rapisarda, G. G.; Campajola, L.; Cherubini, S.; Crucillá, V.; Elekes, Z.; Fülöp, Z.; Gialanella, L.; Gulino, M.; Gyürky, G.; Kiss, G.; Cognata, M. La; Lamia, L.; Ordine, A.; Pizzone, R. G.; Romano, S.; Sergi, M. L.; Somorjai, E.
2008-12-01
Two-proton scattering at sub-Coulomb energies has been measured indirectly via the Trojan horse method applied to the p+d→p+p+n reaction to investigate off-energy shell effects for scattering processes. The three-body experiment was performed at 5 and 4.7 MeV corresponding to a p-p relative energy ranging from 80 to 670 keV. The free p-p cross section exhibits a deep minimum right within this relative energy region due to Coulomb plus nuclear destructive interference. No minimum occurs instead in the Trojan horse p-p cross section, which was extracted by employing a simple plane-wave impulse approximation. A detailed formalism was developed to build up the expression of the theoretical half-off-shell p-p cross section. Its behavior agrees with the Trojan horse data and in turn formally fits the n-n, n-p, and nuclear p-p cross sections given the fact that in its expression the Coulomb amplitude is negligible with respect to the nuclear one. These results confirm the Trojan horse suppression of the Coulomb amplitude for scattering due to the off-shell character of the process.
Syzygies probing scattering amplitudes
NASA Astrophysics Data System (ADS)
Chen, Gang; Liu, Junyu; Xie, Ruofei; Zhang, Hao; Zhou, Yehao
2016-09-01
We propose a new efficient algorithm to obtain the locally minimal generating set of the syzygies for an ideal, i.e. a generating set whose proper subsets cannot be generating sets. Syzygy is a concept widely used in the current study of scattering amplitudes. This new algorithm can deal with more syzygies effectively because a new generation of syzygies is obtained in each step and the irreducibility of this generation is also verified in the process. This efficient algorithm can also be applied in getting the syzygies for the modules. We also show a typical example to illustrate the potential application of this method in scattering amplitudes, especially the Integral-By-Part(IBP) relations of the characteristic two-loop diagrams in the Yang-Mills theory.
Erbert, G
2009-09-01
The Amplitude Modulator Chassis (AMC) is the final component in the MOR system and connects directly to the PAM input through a 100-meter fiber. The 48 AMCs temporally shape the 48 outputs of the MOR using an arbitrary waveform generator coupled to an amplitude modulator. The amplitude modulation element is a two stage, Lithium Niobate waveguide device, where the intensity of the light passing through the device is a function of the electrical drive applied. The first stage of the modulator is connected to a programmable high performance Arbitrary Waveform Generator (AWG) consisting of 140 impulse generators space 250 ps apart. An arbitrary waveform is generated by independently varying the amplitude of each impulse generator and then summing the impulses together. In addition to the AWG a short pulse generator is also connected to the first stage of the modulator to provide a sub 100-ps pulse used for timing experiments. The second stage of the modulator is connect to a square pulse generator used to further attenuate any pre or post pulse light passing through the first stage of the modulator. The fast rise and fall time of the square pulse generator is also used to produce fast rise and fall times of the AWG by clipping the AWG pulse. For maximum extinction, a pulse bias voltage is applied to each stage of the modulator. A pulse voltage is applied as opposed to a DC voltage to prevent charge buildup on the modulator. Each bias voltage is adjustable to provide a minimum of 50-dB extinction. The AMC is controlled through ICCS to generate the desired temporal pulse shape. This process involves a closed-loop control algorithm, which compares the desired temporal waveform to the produced optical pulse, and iterates the programming of the AWG until the two waveforms agree within an allowable tolerance.
Gray, G.W.; Jensen, A.S.
1957-10-22
A pulse-height analyzer system of improved design for sorting and counting a series of pulses, such as provided by a scintillation detector in nuclear radiation measurements, is described. The analyzer comprises a main transmission line, a cathode-ray tube for each section of the line with its deflection plates acting as the line capacitance; means to bias the respective cathode ray tubes so that the beam strikes a target only when a prearranged pulse amplitude is applied, with each tube progressively biased to respond to smaller amplitudes; pulse generating and counting means associated with each tube to respond when the beam is deflected; a control transmission line having the same time constant as the first line per section with pulse generating means for each tube for initiating a pulse on the second transmission line when a pulse triggers the tube of corresponding amplitude response, the former pulse acting to prevent successive tubes from responding to the pulse under test. This arrangement permits greater deflection sensitivity in the cathode ray tube and overcomes many of the disadvantages of prior art pulse-height analyzer circuits.
Amplitudes of Spiral Perturbations
NASA Astrophysics Data System (ADS)
Grosbol, P.; Patsis, P. A.
2014-03-01
It has proven very difficult to estimate the amplitudes of spiral perturbations in disk galaxies from observations due to the variation of mass-to-light ratio and extinction across spiral arms. Deep, near-infrared images of grand-design spiral galaxies obtained with HAWK-I/VLT were used to analyze the azimuthal amplitude and shape of arms, which, even in the K-band may, be significantly biased by the presence of young stellar populations. Several techniques were applied to evaluate the relative importance of young stars across the arms, such as surface brightness of the disk with light from clusters subtracted, number density of clusters detected, and texture of the disk. The modulation of the texture measurement, which correlates with the number density of faint clusters, yields amplitudes of the spiral perturbation in the range 0.1-0.2. This estimate gives a better estimate of the mass perturbation in the spiral arms, since it is dominated by old clusters.
Proportional Hazards Models of Graduation
ERIC Educational Resources Information Center
Chimka, Justin R.; Reed-Rhoads, Teri; Barker, Kash
2008-01-01
Survival analysis is a statistical tool used to describe the duration between events. Many processes in medical research, engineering, and economics can be described using survival analysis techniques. This research involves studying engineering college student graduation using Cox proportional hazards models. Among male students with American…
Saving Money Using Proportional Reasoning
ERIC Educational Resources Information Center
de la Cruz, Jessica A.; Garney, Sandra
2016-01-01
It is beneficial for students to discover intuitive strategies, as opposed to the teacher presenting strategies to them. Certain proportional reasoning tasks are more likely to elicit intuitive strategies than other tasks. The strategies that students are apt to use when approaching a task, as well as the likelihood of a student's success or…
Social Justice and Proportional Reasoning
ERIC Educational Resources Information Center
Simic-Muller, Ksenija
2015-01-01
Ratio and proportional reasoning tasks abound that have connections to real-world situations. Examples in this article demonstrate how textbook tasks can easily be transformed into authentic real-world problems that shed light on issues of equity and fairness, such as population growth and crime rates. A few ideas are presented on how teachers can…
Understanding Proportional Reasoning for Teaching
ERIC Educational Resources Information Center
Kastberg, Signe E.; D'Ambrosio, Beatriz; Lynch-Davis, Kathleen
2012-01-01
Proportional reasoning is an important cornerstone in children's mathematical development. This sort of reasoning has been shown to develop across the early years of schooling (ages 8 to 10) through the middle years (ages 11-14). In the early years, children tend to use additive reasoning to generate solutions to problems, while later comparisons…
Proportional Reasoning with a Pyramid
ERIC Educational Resources Information Center
Mamolo, Ami; Sinclair, Margaret; Whiteley, Walter J.
2011-01-01
Proportional reasoning pops up in math class in a variety of places, such as while making scaled drawings; finding equivalent fractions; converting units of measurement; comparing speeds, prices, and rates; and comparing lengths, areas, and volume. Students need to be exposed to a variety of representations to develop a sound understanding of this…
Dimension two condensates in the Gribov-Zwanziger theory in Coulomb gauge
NASA Astrophysics Data System (ADS)
Guimaraes, M. S.; Mintz, B. W.; Sorella, S. P.
2015-06-01
We investigate the dimension two condensate ⟨ϕ¯ia bϕia b-ω¯ia bωia b⟩ within the Gribov-Zwanziger approach to Euclidean Yang-Mills theories in the Coulomb gauge, in both 3 and 4 dimensions. An explicit calculation shows that, at the first order, the condensate ⟨ϕ¯i a bϕia b-ω¯i a bωia b⟩ is plagued by a nonintegrable IR divergence in 3 D , while in 4 D it exhibits a logarithmic UV divergence, being proportional to the Gribov parameter γ2. These results indicate that in 3D the transverse spatial Coulomb gluon two-point correlation function exhibits a scaling behavior, in agreement with Gribov's expression. In 4D, however, they suggest that, next to the scaling behavior, a decoupling solution might emerge too.
Turrell, A.E. Sherlock, M.; Rose, S.J.
2015-10-15
Large-angle Coulomb collisions allow for the exchange of a significant proportion of the energy of a particle in a single collision, but are not included in models of plasmas based on fluids, the Vlasov–Fokker–Planck equation, or currently available plasma Monte Carlo techniques. Their unique effects include the creation of fast ‘knock-on’ ions, which may be more likely to undergo certain reactions, and distortions to ion distribution functions relative to what is predicted by small-angle collision only theories. We present a computational method which uses Monte Carlo techniques to include the effects of large-angle Coulomb collisions in plasmas and which self-consistently evolves distribution functions according to the creation of knock-on ions of any generation. The method is used to demonstrate ion distribution function distortions in an inertial confinement fusion (ICF) relevant scenario of the slowing of fusion products.
NASA Astrophysics Data System (ADS)
Li, Zhongyu; Chen, Di; Wang, Jing; Shao, Lin
2014-04-01
Strong electronic stopping power of swift ions in a semiconducting or insulating substrate can lead to localized electron stripping. The subsequent repulsive interactions among charged target atoms can cause Coulomb explosion. Using molecular dynamics simulation, we simulate Coulomb explosion in silicon by introducing an ionization pulse lasting for different periods, and at different substrate temperatures. We find that the longer the pulse period, the larger the melting radius. The observation can be explained by a critical energy density model assuming that melting required thermal energy density is a constant value and the total thermal energy gained from Coulomb explosion is linearly proportional to the ionization period. Our studies also show that melting radius is larger at higher substrate temperatures. The temperature effect is explained due to a longer structural relaxation above the melting temperature at original ionization boundary due to lower heat dissipation rates. Furthermore, simulations show the formation of shock waves, created due to the compression from the melting core.
Particle Diffusion Due to Coulomb Scattering
V. Lebedev and S. Nagaitsev
2002-06-03
Conventionally, the multiple and single particle scattering in a storage ring are considered to be independent. Such an approach is simple and often yields sufficiently accurate results. Nevertheless, there is a class of problems where such an approach is not adequate and the single and multiple scattering need to be considered together. This can be achieved by solving an integro-differential equation for the particle distribution function, which correctly treats particle Coulomb scattering in the presence of betatron motion. A derivation of the equation is presented in the article. A numerical solution for one practical case is also considered.
Nanoplasmonic renormalization and enhancement of Coulomb interactions
NASA Astrophysics Data System (ADS)
Durach, Maxim; Rusina, Anastasia; Klimov, Victor I.; Stockman, Mark I.
2008-08-01
In this paper we propose a general and powerful theory of the plasmonic enhancement of the many-body phenomena resulting in a closed expression for the surface plasmon-dressed Coulomb interaction. We illustrate this theory by computing dressed interaction explicitly for an important example of metal-dielectric nanoshells which exhibits a rich resonant behavior in magnitude and phase. This interaction is used to describe the nanoplasmonic-enhanced FÂ¨orster resonant energy transfer (FRET) between nanocrystal quantum dots near a nanoshell.
Nanoplasmonic renormalization and enhancement of Coulomb interactions
NASA Astrophysics Data System (ADS)
Durach, M.; Rusina, A.; Klimov, V. I.; Stockman, M. I.
2008-10-01
In this paper, we propose a general and powerful theory of the plasmonic enhancement of the many-body phenomena resulting in a closed expression for the surface plasmon-dressed Coulomb interaction. We illustrate this theory by computing the dressed interaction explicitly for an important example of metal-dielectric nanoshells which exhibits a rich resonant behavior in magnitude and phase. This interaction is used to describe the nanoplasmonic-enhanced Förster resonant energy transfer (FRET) between nanocrystal quantum dots near a nanoshell.
Action principle for Coulomb collisions in plasmas
Hirvijoki, Eero
2016-09-14
In this study, an action principle for Coulomb collisions in plasmas is proposed. Although no natural Lagrangian exists for the Landau-Fokker-Planck equation, an Eulerian variational formulation is found considering the system of partial differential equations that couple the distribution function and the Rosenbluth-MacDonald-Judd potentials. Conservation laws are derived after generalizing the energy-momentum stress tensor for second order Lagrangians and, in the case of a test-particle population in a given plasma background, the action principle is shown to correspond to the Langevin equation for individual particles.
Temperature dependence of coulomb drag between finite-length quantum wires.
Peguiron, J; Bruder, C; Trauzettel, B
2007-08-24
We evaluate the Coulomb drag current in two finite-length Tomonaga-Luttinger-liquid wires coupled by an electrostatic backscattering interaction. The drag current in one wire shows oscillations as a function of the bias voltage applied to the other wire, reflecting interferences of the plasmon standing waves in the interacting wires. In agreement with this picture, the amplitude of the current oscillations is reduced with increasing temperature. This is a clear signature of non-Fermi-liquid physics because for coupled Fermi liquids the drag resistance is always expected to increase as the temperature is raised.
Manakov, N. L. Krylovetsky, A. A.; Marmo, S. I.
2015-11-15
Compact analytic expressions have been derived by a direct expansion in ħ → 0 for the nonrelativistic amplitude of Coulomb bremsstrahlung radiation (BR), the differential (in frequency and angles of the scattered electron) BR cross section, and the triply differential BR cross section that takes into account the bremsstrahlung photon direction and polarization and the scattered electron direction. They contain the classical limit and a quantum correction of the order of ħ at an arbitrary BR frequency ω. An explicit expression has been found for the quantum correction of the order of ħ to the classical BR spectrum.
New approach to folding with the Coulomb wave function
Blokhintsev, L. D.; Savin, D. A.; Kadyrov, A. S.; Mukhamedzhanov, A. M.
2015-05-15
Due to the long-range character of the Coulomb interaction theoretical description of low-energy nuclear reactions with charged particles still remains a formidable task. One way of dealing with the problem in an integral-equation approach is to employ a screened Coulomb potential. A general approach without screening requires folding of kernels of the integral equations with the Coulomb wave. A new method of folding a function with the Coulomb partial waves is presented. The partial-wave Coulomb function both in the configuration and momentum representations is written in the form of separable series. Each term of the series is represented as a product of a factor depending only on the Coulomb parameter and a function depending on the spatial variable in the configuration space and the momentum variable if the momentum representation is used. Using a trial function, the method is demonstrated to be efficient and reliable.
Improved Shell models for screened Coulomb balls
NASA Astrophysics Data System (ADS)
Bonitz, M.; Kaehlert, H.; Henning, C.; Baumgartner, H.; Filinov, A.
2006-10-01
Spherical Coulomb crystals in dusty plasmas [1] are well described by an isotropic Yukawa-type pair interaction and an external parabolic confinement as was shown by extensive molecular dynamics simulations [2]. A much simpler description is possible with analytical shell models which have been derived for Yukawas plasmas in [3,4]. Here we analyze improved Yukawa shell models which include correlations along the lines proposed for Coulomb crystals in [5]. The shell configurations are efficiently evaluated using a Monte Carlo procedure. [1] O. Arp, A. Piel and A. Melzer, Phys. Rev. Lett. 93, 165004 (2004). [2] M. Bonitz, D. Block, O. Arp, V. Golunychiy, H. Baumgartner, P. Ludwig, A. Piel and A. Filinov, Phys. Rev. Lett. 96, 075001 (2006). [3] H. Totsuji, C. Totsuji, T. Ogawa, and K. Tsuruta, Phys. Rev. E 71, 045401 (2005). [4] C. Henning, M. Bonitz, A. Piel, P. Ludwig, H. Baumgartner, V. Golubnichiy, and D. Block, submitted to Phys. Rev. E [5] W.D. Kraeft and M. Bonitz, J. Phys. Conf. Ser. 35, 94 (2006).
Thermodynamic properties of screened Coulomb balls
NASA Astrophysics Data System (ADS)
Bonitz, M.; Baumgartner, H.; Filinov, A.
2006-10-01
Complex plasmas in parabolic traps [1,2], especially Coulomb balls, can easily reach a strongly coupled state which is of great current interest in many fields, including trapped ions, ultracold plasmas and condensed matter. The advantage of the dust crystals is the direct experimental access to the individual particle positions, allowing for precision comparisons with theoretical models and numerical simulations. In this work the dependence of melting points of mesoscopic spherical crystals on the screening and particle number is analyzed. We present analytical results which are compared with simulation and experimental data [3,4,5]. It is shown that the influence of the screening on structural properties of these mesoscopic systems exhibts also a strong impact on the melting behavior. This analysis is based on Metropolis thermodynamic Monte Carlo simulations to obtain first principle thermodynamic properties of the strongly correlated Coulomb clusters. Finally, our results allow to propose a new non-invasive diagnostic to determine the dust temperature. [1] O. Arp, A. Piel and A. Melzer, Phys. Rev. Lett. 93, 165004 (2004).[2] P. Ludwig, S. Kosse and M. Bonitz, Phys. Rev. E 71, 046403 (2005).[3] M. Bonitz, D. Block, O. Arp, V. Golunychiy, H. Baumgartner, P. Ludwig, A. Piel and A. Filinov, Phys. Rev. Lett. 96, 075001 (2006). [4] O.S. Vaulina, S.A. Khrapak and G.E. Morfill, Phys. Rev. E 66, 016404 (2002). [5] J.P. Schiffer, Phys. Rev. Lett. 88, 205003 (2002)
Coulomb excitation of radioactive {sup 79}Pb
Lister, C.J.; Blumenthal, D.; Davids, C.N.
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.
[Invariants of the anthropometrical proportions].
Smolianinov, V V
2012-01-01
In this work a general interpretation of a modulor as scales of segments proportions of anthropometrical modules (extremities and a body) is made. The objects of this study were: 1) to reason the idea of the growth modulor; 2) using the modern empirical data, to prove the validity of a principle of linear similarity for anthropometrical segments; 3) to specify the system of invariants for constitutional anthropometrics.
Metacarpal proportions in Australopithecus africanus.
Green, David J; Gordon, Adam D
2008-05-01
Recent work has shown that, despite being craniodentally more derived, Australopithecus africanus had more apelike limb-size proportions than A. afarensis. Here, we test whether the A. africanus hand, as judged by metacarpal shaft and articular proportions, was similarly apelike. More specifically, did A. africanus have a short and narrow first metacarpal (MC1) relative to the other metacarpals? Proportions of both MC breadth and length were considered: the geometric mean (GM) of articular and midshaft measurements of MC1 breadth was compared to those of MC2-4, and MC1 length was compared to MC3 length individually and also to the GM of MC2 and 3 lengths. To compare the extant hominoid sample with an incomplete A. africanus fossil record (11 attributed metacarpals), a resampling procedure imposed sampling constraints on the comparative groups that produced composite intrahand ratios. Resampled ratios in the extant sample are not significantly different from actual ratios based on associated elements, demonstrating the methodological appropriateness of this technique. Australopithecus africanus metacarpals do not differ significantly from the great apes in the comparison of breadth ratios but are significantly greater than chimpanzees and orangutans in both measures of relative length. Conversely, A. africanus has a significantly smaller breadth ratio than modern humans, but does not significantly differ from this group in either measure of relative length. We conclude that the first metacarpals of A. africanus are more apelike in relative breadth while also being more humanlike in relative length, a finding consistent with previous work on A. afarensis hand proportions. This configuration would have likely promoted a high degree of manipulative dexterity, but the relatively slender, apelike first metacarpal suggests that A. africanus did not place the same mechanical demands on the thumb as more recent, stone-tool-producing hominins.
Effect of Coulomb interaction on multi-electronwave packet dynamics
Shiokawa, T.; Takada, Y.; Konabe, S.; Hatsugai, Y.; Muraguchi, M.; Endoh, T.; Shiraishi, K.
2013-12-04
We have investigated the effect of Coulomb interaction on electron transport in a one-dimensional nanoscale structure using a multi-electron wave packet approach. To study the time evolution, we numerically solve the time-dependent Hartree-Fock equation, finding that the electron wave packet dynamics strongly depends on the Coulomb interaction strength. When the Coulomb interaction is large, each electron wave packet moves separately in the presence of an electric field. With weak Coulomb interaction, however, the electron wave packets overlap, forming and moving as one collective wave packet.
The mystery of Coulomb friction in sediment transport
NASA Astrophysics Data System (ADS)
Pähtz, Thomas; Duran, Orencio
Nearly all analytical models of sediment transport in Newtonian fluid (e.g., air or water) are based on Bagnold's assumption of a constant Coulomb friction coefficient (particle-shear-pressure-ratio, μ) at the interface (zb) between sediment bed and transport layer. In fact, this assumption is the main reason why these models predict the sediment load (and subsequently the sediment transport rate) to be proportional to the excess shear stress (τ -τt), a scaling which has been confirmed in many wind-tunnel and flume experiments. Attempts to explain why μ (zb) is constant have usually been based on the sliding-friction analogy or rheology arguments. However, here we analytically derive μ (zs) √{ 3} - 1 , where zs is the location at which the production rate of particle fluctuation energy is maximal. Our derivation is based on the assumption that the rate of collisional transfer of horizontal into vertical kinetic energy is typically much larger than the rate of energy dissipation. Using state-of-the-art numerical simulations of sediment transport in Newtonian fluid, we validate all assumptions and approximation involved in our derivation. Interestingly, the location zs can significantly deviate from zb depending on the simulated conditions. We acknowledge support from grants National Natural Science Foundation of China (Nos. 1151101041 and 41376095) and Natural Science Foundation of Zhejiang Province (No. LR16E090001).
A molecular dynamics model for the Coulomb explosion
NASA Astrophysics Data System (ADS)
Smith, Roger; Ramasawmy, D.; Kenny, S. D.
2005-01-01
The impact of positively charged Arn+ ions, n = 1, 4, 8, incident normally on the (1 0 0) surface of NaCl is studied by Molecular Dynamics (MD) simulations for energies up to 1 keV. The model assumes fixed charges on the ions and the effect of projectile charge is investigated as a function of energy. It is shown that there is a significant enhancement in the sputtering yield at low impact energies due to the attachment of Cl ions to the impacting Ar, which is subsequently ejected from the lattice. The low energy Ar ions can also experience acceleration towards the NaCl crystal due to Coulombic attraction. At energies greater than a few hundred eV the Ar ions implant within the crystal which accommodates the extra charge from these ions. As a result the sputtering yield from the initial impact is reduced but as the dose increases, the yield rises as Na+ ions are preferentially ejected from the lattice. A large proportion of the ejected material is in the form of clusters.
Dust-Coulomb waves in dense dusty plasmas
NASA Astrophysics Data System (ADS)
Rao, N. N.
1999-12-01
Dusty plasmas can be considered as tenuous, dilute or dense when the dust fugacity parameter f≡4πnd0λD2R˜NDR/λD satisfies f≪1, ˜1, or ≫1, where nd0, λD and R denote, respectively, the dust number density, the plasma Debye length and the dust grain size (radius), and ND=nd0λD3 is the dust plasma parameter. Dense dusty plasmas are shown to support a new kind of ultra low-frequency electrostatic dust mode which may be called the "Dust-Coulomb Wave" (DCW). In contrast to the dust-acoustic wave (DAW) and the dust-lattice wave (DLW) which exist even for constant grain charge, DCWs are accompanied by dust charge as well as number density perturbations which are proportional to each other. For frequencies much smaller than the grain charging frequency, DCWs propagate as normal modes with the phase speed CDC≡qd0/√mdR , where qd0 (md) is the charge (mass) of the dust grains. In the long wavelength limit, the DCW phase speed is much smaller than that of DAW (CDA), and scales as ˜CDA/√f . Thus, for a given wave number, the frequency regime for the existence of DCW is much lower than the DAW regime. A comparison between the three types of dust-modes (DCWs, DAWs, and DLWs) has been carried out.
Coulomb crystallization in classical and quantum systems
NASA Astrophysics Data System (ADS)
Bonitz, Michael
2007-11-01
Coulomb crystallization occurs in one-component plasmas when the average interaction energy exceeds the kinetic energy by about two orders of magnitude. A simple road to reach such strong coupling consists in using external confinement potentials the strength of which controls the density. This has been succsessfully realized with ions in traps and storage rings and also in dusty plasma. Recently a three-dimensional spherical confinement could be created [1] which allows to produce spherical dust crystals containing concentric shells. I will give an overview on our recent results for these ``Yukawa balls'' and compare them to experiments. The shell structure of these systems can be very well explained by using an isotropic statically screened pair interaction. Further, the thermodynamic properties of these systems, such as the radial density distribution are discussed based on an analytical theory [3]. I then will discuss Coulomb crystallization in trapped quantum systems, such as mesoscopic electron and electron hole plasmas in coupled layers [4,5]. These systems show a very rich correlation behavior, including liquid and solid like states and bound states (excitons, biexcitons) and their crystals. On the other hand, also collective quantum and spin effects are observed, including Bose-Einstein condensation and superfluidity of bound electron-hole pairs [4]. Finally, I consider Coulomb crystallization in two-component neutral plasmas in three dimensions. I discuss the necessary conditions for crystals of heavy charges to exist in the presence of a light component which typically is in the Fermi gas or liquid state. It can be shown that their exists a critical ratio of the masses of the species of the order of 80 [5] which is confirmed by Quantum Monte Carlo simulations [6]. Familiar examples are crystals of nuclei in the core of White dwarf stars, but the results also suggest the existence of other crystals, including proton or α-particle crystals in dense matter
Elastic Coulomb breakup of 34Na
NASA Astrophysics Data System (ADS)
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
Continuous phase and amplitude holographic elements
NASA Technical Reports Server (NTRS)
Maker, Paul D. (Inventor); Muller, Richard E. (Inventor)
1995-01-01
A method for producing a phase hologram using e-beam lithography provides n-ary levels of phase and amplitude by first producing an amplitude hologram on a transparent substrate by e-beam exposure of a resist over a film of metal by exposing n is less than or equal to m x m spots of an array of spots for each pixel, where the spots are randomly selected in proportion to the amplitude assigned to each pixel, and then after developing and etching the metal film producing a phase hologram by e-beam lithography using a low contrast resist, such as PMMA, and n-ary levels of low doses less than approximately 200 micro-C/sq cm and preferably in the range of 20-200 micro-C/sq cm, and aggressive development using pure acetone for an empirically determined time (about 6 s) controlled to within 1/10 s to produce partial development of each pixel in proportion to the n-ary level of dose assigned to it.
Photodetectors for Scintillator Proportionality Measurement
Moses, William W.; Choong, Woon-Seng; Hull, Giulia; Payne, Steve; Cherepy, Nerine; Valentine, J.D.
2010-10-18
We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.
The ghost propagator in Coulomb gauge
NASA Astrophysics Data System (ADS)
Watson, P.; Reinhardt, H.
2011-05-01
We present results for a numerical study of the ghost propagator in Coulomb gauge whereby lattice results for the spatial gluon propagator are used as input to solving the ghost Dyson-Schwinger equation. We show that in order to solve completely, the ghost equation must be supplemented by a boundary condition (the value of the inverse ghost propagator dressing function at zero momentum) which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until `forced' to freeze out in the infrared to the value of the boundary condition. The boundary condition can be interpreted in terms of the Gribov gauge-fixing ambiguity; we also demonstrate that this is not connected to the renormalization. Further, the connection to the temporal gluon propagator and the infrared slavery picture of confinement is discussed.
The ghost propagator in Coulomb gauge
Watson, P.; Reinhardt, H.
2011-05-23
We present results for a numerical study of the ghost propagator in Coulomb gauge whereby lattice results for the spatial gluon propagator are used as input to solving the ghost Dyson-Schwinger equation. We show that in order to solve completely, the ghost equation must be supplemented by a boundary condition (the value of the inverse ghost propagator dressing function at zero momentum) which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until 'forced' to freeze out in the infrared to the value of the boundary condition. The boundary condition can be interpreted in terms of the Gribov gauge-fixing ambiguity; we also demonstrate that this is not connected to the renormalization. Further, the connection to the temporal gluon propagator and the infrared slavery picture of confinement is discussed.
Tabletop nucleosynthesis driven by cluster Coulomb explosion.
Last, Isidore; Jortner, Joshua
2006-10-27
Coulomb explosion of completely ionized (CH4)n, (NH3)n, and (H2O)n clusters will drive tabletop nuclear reactions of protons with 12C6+, 14N7+, and 16O8+ nuclei, extending the realm of nuclear reactions driven by ultraintense laser-heterocluster interaction. The realization for nucleosynthesis in exploding cluster beams requires complete electron stripping from the clusters (at laser intensities I(M) > or = 10(19) W cm(-2)), the utilization of nanodroplets of radius 300-700 A for vertical ionization, and the attainment of the highest energies for the nuclei (i.e., approximately 30 MeV for heavy nuclei and approximately 3 MeV for protons).
Ion Coulomb Crystals and Their Applications
NASA Astrophysics Data System (ADS)
Drewsen, Michael
The following text will give a brief introduction to the physics of the spatially ordered structures, so-called Coulomb crystals, that appear when confined ions are cooled to sufficiently low temperatures. It will as well briefly comment on the very diverse scientific applications of such crystals, which have emerged in the past two decades. While this document lacks figures and many specific references, it is the hope, not the text will stimulate the reader to dig deeper into one or more of the discussed subjects, and inspire her/him to think about new potential applications. A fully referenced journal article of essentially the same text can be found in Physica B 460, 105 (2015) [1].
Gauge Theories on the Coulomb Branch
NASA Astrophysics Data System (ADS)
Schwarz, John H.
We construct the world-volume action of a probe D3-brane in AdS5 × S5 with N units of flux. It has the field content, symmetries, and dualities of the U(1) factor of 𝒩 = 4 U(N + 1) super Yang-Mills theory, spontaneously broken to U(N) × U(1) by being on the Coulomb branch, with the massive fields integrated out. This motivates the conjecture that it is the exact effective action, called a highly effective action (HEA). We construct an SL(2, Z) multiplet of BPS soliton solutions of the D3-brane theory (the conjectured HEA) and show that they reproduce the electrically charged massive states that have been integrated out as well as magnetic monopoles and dyons. Their charges are uniformly spread on a spherical surface, called a soliton bubble, which is interpreted as a phase boundary.
Simulating Coulomb collisions in a magnetized plasma
Hinton, Fred L.
2008-04-15
The problem of simulating ion-ion Coulomb collisions in a plasma in a strong magnetic field is considered. No assumption is made about the ion distribution function except that it is independent of the gyrophase angle, consistent with the assumption that the ion gyrofrequency is much larger than the ion-ion collision frequency. A Langevin method is presented which time-advances the components of a particle's velocity parallel and perpendicular to the magnetic field, without following the rapidly changing gyrophase. Although the standard Monte Carlo procedure, which uses random sampling, can be used, it is also possible to use a deterministic sampling procedure, where the samples are determined by the points which would be used in a numerical quadrature formula for moments of the Fokker-Planck Green's function. This should reduce the sampling noise compared with the Monte Carlo collision method.
A coulombic hypothesis of mitochondrial oxidative phosphorylation.
Malpress, F H
1984-08-21
A coulombic hypothesis of mitochondrial oxidative phosphorylation is presented, founded upon the evidence for negative fixed charge formation during electron transport chain activity. The intermediary force is electrostatic (psi H) and not electrochemical (delta mu H). The electrochemical potential of the chemiosmotic hypothesis is identified as a "phantom" parameter which owes its delusive existence to the procedures by which it is measured. The connection between psi H and the conditional delta mu H values is examined; it entails the use of a variable conversion factor, f, where delta mu H (mV) = f psi H, and the concept of the "protonic status" of the diffuse double layer. A number of problems which beset the chemiosmotic view are reappraised in the light of the new interpretation, and find authentic solutions.
Relativistic Coulomb excitation of 88Kr
NASA Astrophysics Data System (ADS)
Moschner, K.; Blazhev, A.; Jolie, J.; Warr, N.; Boutachkov, P.; Bednarczyk, P.; Sieja, K.; Algora, A.; Ameil, F.; Bentley, M. A.; Brambilla, S.; Braun, N.; Camera, F.; Cederkäll, J.; Corsi, A.; Danchev, M.; DiJulio, D.; Fahlander, C.; Gerl, J.; Giaz, A.; Golubev, P.; Górska, M.; Grebosz, J.; Habermann, T.; Hackstein, M.; Hoischen, R.; Kojouharov, I.; Kurz, N.; Mǎrginean, N.; Merchán, E.; Möller, T.; Naqvi, F.; Nara Singh, B. S.; Nociforo, C.; Pietralla, N.; Pietri, S.; Podolyák, Zs.; Prochazka, A.; Reese, M.; Reiter, P.; Rudigier, M.; Rudolph, D.; Sava, T.; Schaffner, H.; Scruton, L.; Taprogge, J.; Thomas, T.; Weick, H.; Wendt, A.; Wieland, O.; Wollersheim, H.-J.
2016-11-01
To investigate the systematics of mixed-symmetry states in N =52 isotones, a relativistic Coulomb excitation experiment was performed during the PreSPEC campaign at the GSI Helmholtzzentrum für Schwerionenforschung to determine E 2 transition strengths to 2+ states of the radioactive nucleus 88Kr. Absolute transition rates could be measured towards the first and third 2+ states. For the latter a mixed-symmetry character is suggested on the basis of the indication for a strong M 1 transition to the fully symmetric 21+ state, extending the knowledge of the N =52 isotones below Z =40 . A comparison with the proton-neutron interacting boson model and shell-model predictions is made and supports the assignment.
Dynamical effects in the Coulomb expansion following nuclear fragmentation
Chung, K.C.; Donangelo, R.; Schechter, H.
1987-09-01
The effects of the Coulomb expansion on the fragment kinetic energy spectrum for a fragmentating hot nuclear system is investigated. In particular, /sup 12/C-fragment spectra are calculated and compared with those predicted by the uniform expansion approximation. The results indicate that the energy spectra of fragments are quite sensitive to the details of the Coulomb expansion treatment.
Known-to-Unknown Approach to Teach about Coulomb's Law
ERIC Educational Resources Information Center
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…
Proportional Reasoning: A Review of the Literature.
ERIC Educational Resources Information Center
Tourniaire, Francoise; Pulos, Steven
1985-01-01
The literature on proportional reasoning is reviewed. After methodology is discussed, strategies used to solve proportion problems, variables that influence performance, and training studies are each considered. (MNS)
Long-range interactions and the sign of natural amplitudes in two-electron systems
Giesbertz, Klaas J. H.; Leeuwen, Robert van
2013-09-14
In singlet two-electron systems, the natural occupation numbers of the one-particle reduced density matrix are given as squares of the natural amplitudes which are defined as the expansion coefficients of the two-electron wave function in a natural orbital basis. In this work, we relate the sign of the natural amplitudes to the nature of the two-body interaction. We show that long-range Coulomb-type interactions are responsible for the appearance of positive amplitudes and give both analytical and numerical examples that illustrate how the long-distance structure of the wave function affects these amplitudes. We further demonstrate that the amplitudes show an avoided crossing behavior as function of a parameter in the Hamiltonian and use this feature to show that these amplitudes never become zero, except for special interactions in which infinitely many of them can become zero simultaneously when changing the interaction strength. This mechanism of avoided crossings provides an alternative argument for the non-vanishing of the natural occupation numbers in Coulomb systems.
Coulomb gauge ghost Dyson-Schwinger equation
NASA Astrophysics Data System (ADS)
Watson, P.; Reinhardt, H.
2010-12-01
A numerical study of the ghost Dyson-Schwinger equation in Coulomb gauge is performed and solutions for the ghost propagator found. As input, lattice results for the spatial gluon propagator are used. It is shown that in order to solve completely, the equation must be supplemented by a nonperturbative boundary condition (the value of the inverse ghost propagator dressing function at zero momentum), which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until forced to freeze out in the infrared to the value of the boundary condition. The renormalization is shown to be largely independent of the boundary condition. The boundary condition and the pattern of the solutions can be interpreted in terms of the Gribov gauge-fixing ambiguity. The connection to the temporal gluon propagator and the infrared slavery picture of confinement is explored.
Coulomb glass in the random phase approximation
NASA Astrophysics Data System (ADS)
Basylko, S. A.; Onischouk, V. A.; Rosengren, A.
2002-01-01
A three-dimensional model of the electrons localized on randomly distributed donor sites of density n and with the acceptor charge uniformly smeared on these sites, -Ke on each, is considered in the random phase approximation (RPA). For the case K=1/2 the free energy, the density of the one-site energies (DOSE) ɛ, and the pair OSE correlators are found. In the high-temperature region (e2n1/3/T)<1 (T is the temperature) RPA energies and DOSE are in a good agreement with the corresponding data of Monte Carlo simulations. Thermodynamics of the model in this region is similar to the one of an electrolyte in the regime of Debye screening. In the vicinity of the Fermi level μ=0 the OSE correlations, depending on sgn(ɛ1.ɛ2) and with very slow decoupling law, have been found. The main result is that even in the temperature range where the energy of a Coulomb glass is determined by Debye screening effects, the correlations of the long-range nature between the OSE still exist.
Femtosecond Laser-Induced Coulomb Explosion Imaging
NASA Astrophysics Data System (ADS)
Karimi, Reza; Liu, Wing-Ki; Sanderson, Joseph
2016-07-01
We review recent progress in the field of Coulomb imaging using femtosecond laser pulses of variable length, referred to as Femtosecond Multiple Pulse Length Spectroscopy (FEMPULS). This method introduces a multi-dimensional approach to the study of the molecular dynamics of the multiply ionized triatomic molecules: CO2, OCS, and N2O. We describe the experimental setup used and the approaches needed to optimize the multi-particle detection, coincidence technique. The results show the degree of high resolution imaging which can be achieved with few cycle pulses, and how the onset of charge resonance enhanced ionization (CREI) can be observed as pulse length is increased. By coupling pulse length variation with Dalitz and Newton plotting techniques, stepwise processes can be identified for all three molecules, giving insight into the dynamics, particularly on the 3+ state, which has been revealed as the doorway state to CREI. Finally, in the case of OCS, pulse length variation is shown to have the potential as a control mechanism, as it modulates the ratio of stepwise to concerted processes.
Electron attraction mediated by Coulomb repulsion
NASA Astrophysics Data System (ADS)
Hamo, A.; Benyamini, A.; Shapir, I.; Khivrich, I.; Waissman, J.; Kaasbjerg, K.; Oreg, Y.; von Oppen, F.; Ilani, S.
2016-07-01
One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed ‘excitonic’, promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the ‘glue’ that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter.
Deep inelastic scattering near the Coulomb barrier
Gehring, J.; Back, B.; Chan, K.
1995-08-01
Deep inelastic scattering was recently observed in heavy ion reactions at incident energies near and below the Coulomb barrier. Traditional models of this process are based on frictional forces and are designed to predict the features of deep inelastic processes at energies above the barrier. They cannot be applied at energies below the barrier where the nuclear overlap is small and friction is negligible. The presence of deep inelastic scattering at these energies requires a different explanation. The first observation of deep inelastic scattering near the barrier was in the systems {sup 124,112}Sn + {sup 58,64}Ni by Wolfs et al. We previously extended these measurements to the system {sup 136}Xe + {sup 64}Ni and currently measured the system {sup 124}Xe + {sup 58}Ni. We obtained better statistics, better mass and energy resolution, and more complete angular coverage in the Xe + Ni measurements. The cross sections and angular distributions are similar in all of the Sn + Ni and Xe + Ni systems. The data are currently being analyzed and compared with new theoretical calculations. They will be part of the thesis of J. Gehring.
Multilevel Monte Carlo simulation of Coulomb collisions
Rosin, M.S.; Ricketson, L.F.; Dimits, A.M.; Caflisch, R.E.; Cohen, B.I.
2014-10-01
We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau–Fokker–Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ε, the computational cost of the method is O(ε{sup −2}) or O(ε{sup −2}(lnε){sup 2}), depending on the underlying discretization, Milstein or Euler–Maruyama respectively. This is to be contrasted with a cost of O(ε{sup −3}) for direct simulation Monte Carlo or binary collision methods. We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ε=10{sup −5}. We discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.
Correlation functions of Coulomb branch operators
NASA Astrophysics Data System (ADS)
Gerchkovitz, Efrat; Gomis, Jaume; Ishtiaque, Nafiz; Karasik, Avner; Komargodski, Zohar; Pufu, Silviu S.
2017-01-01
We consider the correlation functions of Coulomb branch operators in four-dimensional N = 2 Superconformal Field Theories (SCFTs) involving exactly one antichiral operator. These extremal correlators are the "minimal" non-holomorphic local observables in the theory. We show that they can be expressed in terms of certain determinants of derivatives of the four-sphere partition function of an appropriate deformation of the SCFT. This relation between the extremal correlators and the deformed four-sphere partition function is non-trivial due to the presence of conformal anomalies, which lead to operator mixing on the sphere. Evaluating the deformed four-sphere partition function using supersymmetric localization, we compute the extremal correlators explicitly in many interesting examples. Additionally, the representation of the extremal correlators mentioned above leads to a system of integrable differential equations. We compare our exact results with previous perturbative computations and with the four-dimensional tt ∗ equations. We also use our results to study some of the asymptotic properties of the perturbative series expansions we obtain in N = 2 SQCD.
Electron attraction mediated by Coulomb repulsion.
Hamo, A; Benyamini, A; Shapir, I; Khivrich, I; Waissman, J; Kaasbjerg, K; Oreg, Y; von Oppen, F; Ilani, S
2016-07-21
One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed 'excitonic', promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the 'glue' that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter.
Coulomb gauge model for hidden charm tetraquarks
NASA Astrophysics Data System (ADS)
Xie, W.; Mo, L. Q.; Wang, Ping; Cotanch, Stephen R.
2013-08-01
The spectrum of tetraquark states with hidden charm is studied within an effective Coulomb gauge Hamiltonian approach. Of the four independent color schemes, two are investigated, the (qcbar)1(cqbar)1 singlet-singlet (molecule) and the (qc)3(qbarcbar)3 triplet-triplet (diquark), for selected JPC states using a variational method. The predicted masses of triplet-triplet tetraquarks are roughly a GeV heavier than the singlet-singlet states. There is also an interesting flavor dependence with (qqbar)1 (ccbar1) states about half a GeV lighter than (qcbar)1(qbarc)1. The lightest 1++ and 1-- predictions are in agreement with the observed X (3872) and Y (4008) masses suggesting they are molecules with ωJ / ψ and ηhc, rather than D*Dbar* and DDbar, type structure, respectively. Similarly, the lightest isovector 1++ molecule, having a ρJ / ψ flavor composition, has mass near the recently observed charged Zc (3900) value. These flavor configurations are consistent with observed X, Y and Zc decays to ππJ / ψ.
Multilevel Monte Carlo simulation of Coulomb collisions
Rosin, M. S.; Ricketson, L. F.; Dimits, A. M.; ...
2014-05-29
We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau–Fokker–Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ε , the computational cost of the method is O(ε–2) or (ε–2(lnε)2), depending on the underlying discretization, Milstein or Euler–Maruyama respectively. This is to be contrasted with a cost of O(ε–3) for direct simulation Monte Carlo or binary collision methods.more » We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ε=10–5. Lastly, we discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.« less
Multilevel Monte Carlo simulation of Coulomb collisions
Rosin, M. S.; Ricketson, L. F.; Dimits, A. M.; Caflisch, R. E.; Cohen, B. I.
2014-05-29
We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau–Fokker–Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ε , the computational cost of the method is O(ε^{–2}) or (ε^{–2}(lnε)^{2}), depending on the underlying discretization, Milstein or Euler–Maruyama respectively. This is to be contrasted with a cost of O(ε^{–3}) for direct simulation Monte Carlo or binary collision methods. We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ε=10^{–5}. Lastly, we discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.
Verification of Coulomb order in a storage ring
Hasse, Rainer W.
1999-12-10
We verify theoretically that the anomalous longitudinal temperature reduction of strongly electron cooled heavy ions in the ESR at very low density is explained by the fact that there is no intrabeam scattering and that the particles by their Coulomb repulsion cannot pass each other any more. At the achievable momentum spreads Coulomb order is reached at particle distances of the order of centimeters. It is also shown that under the given experimental conditions in the proton NAP-M experiment of 1980 intrabeam heating counteracts Coulomb order.
Verification of Coulomb Order in a Storage Ring
Rainer W. Hasse
1999-12-31
We verify theoretically that the anomalous longitudinal temperature reduction of strongly electron cooled heavy ions in the ESR at very low density is explained by the fact that there is no intrabeam scattering and that the particles by their Coulomb repulsion cannot pass each other any more. At the achievable momentum spreads Coulomb order is reached at particle distances of the order of centimeters. It is also shown that under the given experimental conditions in the proton NAP-M experiment of 1980 intrabeam heating counteracts Coulomb order.
Classical Coulomb blockade of a silicon nanowire dot
NASA Astrophysics Data System (ADS)
Huang, Shaoyun; Fukata, Naoki; Shimizu, Maki; Yamaguchi, Tomohiro; Sekiguchi, Takashi; Ishibashi, Koji
2008-05-01
Single electron transistors (SETs) have been fabricated with an individual n-type single-crystal silicon nanowire (SiNW) that was grown by a catalytic chemical vapor deposition technique, and their transport properties have been measured in low temperatures. The SiNW-SET in the present work exhibited well pronounced Coulomb oscillations in a wide gate voltage range from -10to10V, featuring in uniform peak height, uniform full width at half maximum, and equidistant peak spacing. The charging energy turned out to be 64μeV. The temperature dependence of Coulomb oscillations revealed that the dot worked within the classical Coulomb blockade model.
Dynamic stresses, Coulomb failure, and remote triggering
Hill, D.P.
2008-01-01
Dynamic stresses associated with crustal surface waves with 15-30-sec periods and peak amplitudes 5 km). The latter is consistent with the observation that extensional or transtensional tectonic regimes are more susceptible to remote triggering by Rayleigh-wave dynamic stresses than compressional or transpressional regimes. Locally elevated pore pressures may have a role in the observed prevalence of dynamic triggering in extensional regimes and geothermal/volcanic systems.
Thermodynamic properties of the magnetized Coulomb crystal lattices
NASA Astrophysics Data System (ADS)
Kozhberov, A. A.
2016-08-01
It is thought that Coulomb crystals of ions with hexagonal close-packed lattice may form in the crust of strongly-magnetized neutron stars (magnetars). In this work we are trying to verify this prediction assuming that the direction of the magnetic field corresponds to the minimum of the zero-point energy. We also continue a detailed study of vibration modes and thermodynamic properties of magnetized Coulomb crystals in a wide range of temperatures and magnetic fields. It is demonstrated that the total Helmholtz free energy of the body-centered cubic Coulomb crystal is always lower than that of the Coulomb crystal with hexagonal close-packed or face-centered cubic lattice, which casts doubt on the hypothesis above.
Multifragmentation: Surface and Coulomb instabilities of sheets, bubbles, and donuts
Moretto, L.G.; Tso, Kin; Wozniak, G.J.
1993-08-01
Disks, bubbles, and donuts have been observed in dynamical calculations of heavy ion collisions. These shapes are subject to a variety of surface and Coulomb instabilities. These instabilities are identified and analyzed in terms of their relevance to multifragmentation.
Coulomb excitation of radioactive nuclear beams in inverse kinematics
Zamfir, N.V. |||; Barton, C.J.; Brenner, D.S.; Casten, R.F. |; Gill, R.L.; Zilges, A. |
1996-12-31
Techniques for the measurement of B (E2:0{sub 1}{sup +} {r_arrow} 2{sub 1}{sup +}) values by Coulomb excitation of Radioactive Nuclear Beams in inverse kinematics are described. Using a thin, low Z target, the Coulomb excited beam nuclei will decay in flight downstream of the target. For long lifetimes (nanosecond range) these nuclei decay centimeters downstream of the target and for shorter lifetimes (picoseconds or less) they decay near the target. Corresponding to these two lifetime regimes two methods have been developed to measure {gamma} rays from the Coulomb excited nuclei: the lifetime method in which the lifetime of the excited state is deduced from the decay curve and the integral method in which the B(E2) value is extracted from the measured total Coulomb excitation cross section.
Constants of motion in deformed oscillator and Coulomb systems
NASA Astrophysics Data System (ADS)
Hakobyan, Tigran; Nersessian, Armen; Shmavonyan, Hovhannes
2017-03-01
In this note we propose a unified description for the constants of motion for superintegrable deformations of the oscillator and Coulomb systems on N-dimensional Euclidean space, sphere and hyperboloid.
Aftershock triggering by complete Coulomb stress changes
Kilb, Debi; Gomberg, J.; Bodin, P.
2002-01-01
We examine the correlation between seismicity rate change following the 1992, M7.3, Landers, California, earthquake and characteristics of the complete Coulomb failure stress (CFS) changes (??CFS(t)) that this earthquake generated. At close distances the time-varying "dynamic" portion of the stress change depends on how the rupture develops temporally and spatially and arises from radiated seismic waves and from permanent coseismic fault displacement. The permanent "static" portion (??CFS) depends only on the final coseismic displacement. ??CFS diminishes much more rapidly with distance than the transient, dynamic stress changes. A common interpretation of the strong correlation between ??CFS and aftershocks is that load changes can advance or delay failure. Stress changes may also promote failure by physically altering properties of the fault or its environs. Because it is transient, ??CFS(t) can alter the failure rate only by the latter means. We calculate both ??CFS and the maximum positive value of ??CFS(t) (peak ??CFS(t)) using a reflectivity program. Input parameters are constrained by modeling Landers displacement seismograms. We quantify the correlation between maps of seismicity rate changes and maps of modeled ??CFS and peak ??CFS(t) and find agreement for both models. However, rupture directivity, which does not affect ??CFS, creates larger peak ??CFS(t) values northwest of the main shock. This asymmetry is also observed in seismicity rate changes but not in ??CFS. This result implies that dynamic stress changes are as effective as static stress changes in triggering aftershocks and may trigger earthquakes long after the waves have passed.
Uniform derivation of Coulomb collisional transport thanks to Debye shielding
NASA Astrophysics Data System (ADS)
Escande, Dominique; Elskens, Yves; Doveil, Fabrice
2016-10-01
The effective potential acting on particles in plasmas being essentially the Debye-shielded Coulomb potential, the particles collisional transport in thermal equilibrium is calculated for all impact parameters b, with a convergent expression reducing to Rutherford scattering for small b, in agreement with both usual expressions holding for large b and small b. No cutoff at the Debye length scale is needed, and the Coulomb logarithm is only slightly modified.
A New Hybrid STEP/Coulomb model for Aftershock Forecasting
NASA Astrophysics Data System (ADS)
Steacy, S.; Jimenez, A.; Gerstenberger, M.
2014-12-01
Aftershock forecasting models tend to fall into two classes - purely statistical approaches based on clustering, b-value, and the Omori-Utsu law; and Coulomb rate-state models which relate the forecast increase in rate to the magnitude of the Coulomb stress change. Recently, hybrid models combining physical and statistical forecasts have begun to be developed, for example by Bach and Hainzl (2012) and Steacy et al. (2013). The latter approach combined Coulomb stress patterns with the STEP (short-term earthquake probability) model by redistributing expected rate from areas with decreased stress to regions where the stress had increased. The chosen 'Coulomb Redistribution Parameter' (CRP) was 0.93, based on California earthquakes, which meant that 93% of the total rate was expected to occur where the stress had increased. The model was tested against the Canterbury sequence and the main result was that the new model performed at least as well as, and often better than, STEP when tested against retrospective data but that STEP was generally better in pseudo-prospective tests that involved data actually available within the first 10 days of each event of interest. The authors suggested that the major reason for this discrepancy was uncertainty in the slip models and, particularly, in the geometries of the faults involved in each complex major event. Here we develop a variant of the STEP/Coulomb model in which the CRP varies based on the percentage of aftershocks that occur in the positively stressed areas during the forecast learning period. We find that this variant significantly outperforms both STEP and the previous hybrid model in almost all cases, even when the input Coulomb model is quite poor. Our results suggest that this approach might be more useful than Coulomb rate-state when the underlying slip model is not well constrained due to the dependence of that method on the magnitude of the Coulomb stress change.
CHY formula and MHV amplitudes
NASA Astrophysics Data System (ADS)
Du, Yi-Jian; Teng, Fei; Wu, Yong-Shi
2016-05-01
In this paper, we study the relation between the Cachazo-He-Yuan (CHY) formula and the maximal-helicity-violating (MHV) amplitudes of Yang-Mills and gravity in four dimensions. We prove that only one special rational solution of the scattering equations found by Weinzierl supports the MHV amplitudes. Namely, localized at this solution, the integrated CHY formula produces the Parke-Taylor formula for MHV Yang-Mills amplitudes as well as the Hodges formula for MHV gravitational amplitudes, with an arbitrary number of external gluons/gravitons. This is achieved by developing techniques, in a manifestly Möbius covariant formalism, to explicitly compute relevant reduced Pfaffians/determinants. We observe and prove two interesting properties (or identities), which facilitate the computations. We also check that all the other ( n - 3)! - 1 solutions to the scattering equations do not support the MHV amplitudes, and prove analytically that this is indeed true for the other special rational solution proposed by Weinzierl, that actually supports the anti-MHV amplitudes. Our results reveal a mysterious feature of the CHY formalism that in Yang-Mills and gravity theory, solutions of scattering equations, involving only external momenta, somehow know about the configuration of external polarizations of the scattering amplitudes.
Cognitive and Metacognitive Aspects of Proportional Reasoning
ERIC Educational Resources Information Center
Modestou, Modestina; Gagatsis, Athanasios
2010-01-01
In this study we attempt to propose a new model of proportional reasoning based both on bibliographical and research data. This is impelled with the help of three written tests involving analogical, proportional, and non-proportional situations that were administered to pupils from grade 7 to 9. The results suggest the existence of a…
Body proportions in children with Kabuki syndrome.
Penders, Bas; Schott, Nina; Gerver, Willem-Jan M; Stumpel, Constance T R M
2016-03-01
Facial characteristics, short stature, and skeletal anomalies have been described for the clinical diagnosis of Kabuki Syndrome (KS) in children. However, no studies have investigated body proportions in KS. Knowledge of body proportions in KS may contribute to better insight into the growth pattern and characterization of this genetic disorder. Therefore we compared body proportions of children with KS to normally proportioned controls to investigate if atypical body proportions are part of this genetic disorder. This study was designed and conducted within the setting of the Maastricht University Medical Centre (MUMC+), the official Dutch expert center for Kabuki syndrome. We conducted a cross-sectional study in 32 children (11 children with KS and 21 controls). Body proportions were determined by means of photogrammetric anthropometry, measurements based on digital photography. Body proportions, quantified as body ratios, differ significantly in children with KS from normally proportioned children. Children with KS have larger heads and longer arms proportional to their trunks and have been found to have longer upper arms proportional to their tibia length and feet. Based on deviations in body proportions it was shown possible to discern children with KS from normally proportioned controls.
NASA Astrophysics Data System (ADS)
Lam, C. S.; Yao, York-Peng
2016-06-01
The Cachazo-He-Yuan (CHY) formula for on-shell scattering amplitudes is extended off-shell. The off-shell amplitudes (amputated Green's functions) are Möbius invariant, and have the same momentum poles as the on-shell amplitudes. The working principles which drive the modifications to the scattering equations are mainly Möbius covariance and energy momentum conservation in off-shell kinematics. The same technique is also used to obtain off-shell massive scalars. A simple off-shell extension of the CHY gauge formula which is Möbius invariant is proposed, but its true nature awaits further study.
Coulomb excitation of states in 238U
NASA Astrophysics Data System (ADS)
McGowan, F. K.; Milner, W. T.
1994-05-01
Twenty-two states in 238U have been observed with 18 MeV 4He ions on a thick target. Eight 2 + states between 966 and 1782 keV and three 3 - states are populated by direct E2 and E3, respectively. The remaining states are either weakly excited by multiple Coulomb excitation and /or populated by the γ-ray decay of the directly excited states. Spin assignments are based on γ-ray angular distributions. Reduced transition probabilities have been deduced from the γ-ray yields. The B(E2) values for excitation of the 2 + states range from 0.10 to 3.0 W.u. (281 W.u. for the first 2 + state). For the 3 states, the B(E3, 0 → 3 -) values are 7.1, 7.8, and 24.2 W.u. Several of the 2 + states have decay branches to the one-phonon states with B(E2) values between 27 and 56 W.u. which are an order of magnitude larger than the B(E2) values between the one- and zero-phonon states. This disagrees with our present understanding of collectivity in nuclei if these 2 + states are considered to be collective two-phonon excitations. However, the excitation energies of these 2 + states with respect to the one-phonon states are only 1.3 to 1.6. The B(E1) values for 17 transitions between the positive- and negative-parity states range between 10 -3 and 10 -7 W.u. The B(E1) branching ratios for many of these transitions have large deviations from the Alaga-rule predictions. These deviations can be understood by the strong Coriolis coupling between the states of the one-phonon octupole quadruplet in deformed nuclei. The general features of the experimental results for the B(E3) values are reproduced by the microscopic calculations of Neergård and Vogel when the Coriolis coupling between the states of the octupole quadruplet is included.
Coulomb excitation of states in 232Th
NASA Astrophysics Data System (ADS)
McGowan, F. K.; Milner, W. T.
1993-09-01
Twenty-five states in 232Th have been observed with 18 MeV 4He ions on a thick target. Eleven 2 + states between 774 and 1554 keV and three 3 - states are populated by direct E2 and E3, respectively. The remaining states are either weakly excited by multiple Coulomb excitation and/or populated by the decay of the directly excited states. Spin assignments are based on γ-ray angular distributions. Reduced transition probabilities have been deduced from the γ-ray yields. The B(E2) values for excitation of the 2 + states range from 0.024 to 3.5 W.u. (222 W.u. for the first 2 + state). For the 3 - states, the B(E3,0 → 3 -) values are 1.7, 11, and 24 W.u. A possible two-phonon state at 1554 keV, which is nearly harmonic, decays to four members of the one-phonon states, to the ground-state band, and to the K = 0 - octupole band. The B(E2) value for excitation of this state is 0.66 ± 0.05 W.u. and the B(E1) values for decay of this state are (2 and 6)×10 -4 W.u. The B(E2) values between two- and one-phonon vibrational states range between 16 and 53 W.u. which are an order of magnitude larger than the B(E2) values between the one- and zero-phonon states. This disagrees with our present understanding of collectivity in nuclei if this 2 + state is considered to be a collective two-phonon excitation. The 2 + states at 1477 and 1387 keV, which are also nearly harmonic, are possible candidates with two-phonon structure. The agreement between the experimental results and the microscopic calculations by Neergård and Vogel of the B(E3,0 → 3) for the 3 - members of the one-phonon octupole quadruplet is satisfactory when the Coriolis coupling between the states with K and K ± 1 is included. The B(E1) branching ratios for transitions from the 3 - and 1 - states to the ground-state band have large deviations from the Alaga-rule predictions. These deviations can be understood by the strong Coriolis coupling between the states of the octupole quadruplet in deformed nuclei.
Structural stiffness and Coulomb damping in compliant foil journal bearings: Parametric studies
NASA Astrophysics Data System (ADS)
Ku, C.-P. Roger; Heshmat, Hooshang
1994-07-01
This paper presents the results of the second part of the investigation on structural stiffness and Coulomb damping in compliant foil journal bearings. In the first part, a theoretical model was developed to calculate equivalent viscous damping coefficients and structural stiffness of a bump foil strip in a journal bearing or damper. A computer program was also developed to compute the eccentricity and attitude angle of the journal static equilibrium position as well as the deflections, displacements, reacting forces, and equivalent friction coefficient of each bump on the strip. This model and program enabled further parametric studies to be conducted in the second part of the investigation, the results of which are the subject of this paper. The design parameters studied were static eccentricity (bearing load), pad angle (load angle), sliding friction coefficients, and perturbation amplitude (dynamic load). In addition, more effective methods of achieving both Coulomb damping and optimum structural stiffness were examined. The results of the studies showed that stiffness and damping coefficients were highly nonlinear and anisotropic, that their values depended on the sums of the sliding friction coefficients between contact surfaces, and that they were greatly affected by the pad angle.
Coulomb-blockade peak spacing statistics of graphene quantum dots on SiO2
NASA Astrophysics Data System (ADS)
Herrmann, O.; Gould, C.; Molenkamp, L. W.
2016-10-01
Extrinsic disorder strongly affects the performance of graphene-based quantum dots. The standard SiO2 substrate is generally considered to be one major factor besides edge-induced disorder. In this report we present the fabrication of lithographically defined quantum dots on SiO2 with short and narrow constrictions and different central island sizes. Low temperature transport measurements display distinct Coulomb-blockade peaks with amplitudes exceeding what is commonly observed experimentally. The analysis of the normalized Coulomb-blockade peak spacing shows a size dependence, which has not previously been observed for devices on SiO2. Furthermore, a quantitative comparison of the peak spacing distribution to the literature shows that one of the two devices compares favorably to a similar sized dot placed on hexagonal boron nitride, which is known to reduce the substrate disorder. Our findings suggest that the other sources of extrinsic disorder, such as lithography residues, may play an important role for the performance of large graphene quantum dots.
Amplitude sorting of oscillatory burst signals by sampling
Davis, Thomas J.
1977-01-01
A method and apparatus for amplitude sorting of oscillatory burst signals is described in which the burst signal is detected to produce a burst envelope signal and an intermediate or midportion of such envelope signal is sampled to provide a sample pulse output. The height of the sample pulse is proportional to the amplitude of the envelope signal and to the maximum burst signal amplitude. The sample pulses are fed to a pulse height analyzer for sorting. The present invention is used in an acoustic emission testing system to convert the amplitude of the acoustic emission burst signals into sample pulse heights which are measured by a pulse height analyzer for sorting the pulses in groups according to their height in order to identify the material anomalies in the test material which emit the acoustic signals.
Stable and Critical Noncohesive Coulomb Wedges: Exact Elastic Solutions
NASA Astrophysics Data System (ADS)
Wang, K.; Hu, Y.
2004-12-01
The theory of critically tapered Coulomb wedge has been successfully applied to model active fold-and-thrust belts or submarine accretionary prisms. Brittle mountain building is episodic in nature, controlled by changes in basal friction, erosion and sedimentation, and hydrogeology. Sediment accretion may be modulated by great subduction earthquakes. Between deformation episodes and/or during transition between compressional and extensional tectonics, the Coulomb wedges are stable (i.e., supercritical), to which the critical taper theory does not apply. In this work, we provide an exact elastic solution for stable wedges based on Airy stress functions. The stress equilibrium equation and definition of basal friction and basal and internal pore fluid pressure ratios are exactly the same as those used for Dahlen's [1984] exact solution for critical noncohesive Coulomb wedges, but internal friction μ becomes irrelevant. Given elastic - perfectly Coulomb-plastic rheology, for stresses in a wedge on the verge of Coulomb failure there must co-exist a critical taper solution involving μ and a unique equivalent elastic solution not involving μ . Our elastic solution precisely reduces to Dahlen's critical taper solution for critical conditions. For stable conditions, normal stress perpendicular to the surface slope σ z and shear stress τ xz are identical with those in a critical taper, but the slope-parallel normal stress is different. The elastic solution is also generally applicable to purely elastic wedges and useful for modeling geodetic observations. A stable noncohesive Coulomb wedge differs from a general elastic wedge in that its upper and lower surfaces stay at zero curvature during loading. Dahlen, F.A. (1984), Noncohesive critical Coulomb wedges: An exact solution, JGR, 89, 10,125-10,133.
Small amplitude quasibreathers and oscillons
Fodor, Gyula; Lukacs, Arpad; Forgacs, Peter; Horvath, Zalan
2008-07-15
Quasibreathers (QB) are time-periodic solutions with weak spatial localization introduced in G. Fodor et al. in [Phys. Rev. D 74, 124003 (2006)]. QB's provide a simple description of oscillons (very long-living spatially localized time dependent solutions). The small amplitude limit of QB's is worked out in a large class of scalar theories with a general self-interaction potential, in D spatial dimensions. It is shown that the problem of small amplitude QB's is reduced to a universal elliptic partial differential equation. It is also found that there is the critical dimension, D{sub crit}=4, above which no small amplitude QB's exist. The QB's obtained this way are shown to provide very good initial data for oscillons. Thus these QB's provide the solution of the complicated, nonlinear time dependent problem of small amplitude oscillons in scalar theories.
Tempo and amplitude in growth.
Hermanussen, Michael
2011-01-01
Growth is defined as an increase of size over time with time usually defined as physical time. Yet, the rigid metric of physical time is not directly relevant to the internal dynamics of growth. Growth is linked to maturation. Children and adolescents differ in the tempo at which they mature. One calendar year differs in its meaning in a fast maturing, and in a slow maturing child. The slow child needs more calendar years for completing the same stage of maturity. Many characteristics in the human growth curve are tempo characteristics. Tempo - being fast or slow maturing - has to be carefully separated from amplitude - being tall or short. Several characteristic phenomena such as catch-up growth after periods of illness and starvation are largely tempo phenomena, and do usually not affect the amplitude component of growth. Applying Functional Data Analysis and Principal Component Analysis, the two main sources of height variance: tempo and amplitude can statistically be separate and quantified. Tempo appears to be more sensitive than amplitude to nutrition, health and environmental stress. An appropriate analysis of growth requires disentangling its two major components: amplitude and tempo. The assessment of the developmental tempo thus is an integral part of assessing child and adolescent growth. Though an Internet portal is currently available to process small amounts of height data (www.willi-will-wachsen.com) for separately determining amplitude and tempo in growth, there is urgent need of better and practical solutions for analyzing individual growth.
Solving the three-body Coulomb breakup problem using exterior complex scaling
McCurdy, C.W.; Baertschy, M.; Rescigno, T.N.
2004-05-17
Electron-impact ionization of the hydrogen atom is the prototypical three-body Coulomb breakup problem in quantum mechanics. The combination of subtle correlation effects and the difficult boundary conditions required to describe two electrons in the continuum have made this one of the outstanding challenges of atomic physics. A complete solution of this problem in the form of a ''reduction to computation'' of all aspects of the physics is given by the application of exterior complex scaling, a modern variant of the mathematical tool of analytic continuation of the electronic coordinates into the complex plane that was used historically to establish the formal analytic properties of the scattering matrix. This review first discusses the essential difficulties of the three-body Coulomb breakup problem in quantum mechanics. It then describes the formal basis of exterior complex scaling of electronic coordinates as well as the details of its numerical implementation using a variety of methods including finite difference, finite elements, discrete variable representations, and B-splines. Given these numerical implementations of exterior complex scaling, the scattering wave function can be generated with arbitrary accuracy on any finite volume in the space of electronic coordinates, but there remains the fundamental problem of extracting the breakup amplitudes from it. Methods are described for evaluating these amplitudes. The question of the volume-dependent overall phase that appears in the formal theory of ionization is resolved. A summary is presented of accurate results that have been obtained for the case of electron-impact ionization of hydrogen as well as a discussion of applications to the double photoionization of helium.
TOPICAL REVIEW: Solving the three-body Coulomb breakup problem using exterior complex scaling
NASA Astrophysics Data System (ADS)
McCurdy, C. W.; Baertschy, M.; Rescigno, T. N.
2004-09-01
Electron-impact ionization of the hydrogen atom is the prototypical three-body Coulomb breakup problem in quantum mechanics. The combination of subtle correlation effects and the difficult boundary conditions required to describe two electrons in the continuum have made this one of the outstanding challenges of atomic physics. A complete solution of this problem in the form of a 'reduction to computation' of all aspects of the physics is given by the application of exterior complex scaling, a modern variant of the mathematical tool of analytic continuation of the electronic coordinates into the complex plane that was used historically to establish the formal analytic properties of the scattering matrix. This review first discusses the essential difficulties of the three-body Coulomb breakup problem in quantum mechanics. It then describes the formal basis of exterior complex scaling of electronic coordinates as well as the details of its numerical implementation using a variety of methods including finite difference, finite elements, discrete variable representations and B-splines. Given these numerical implementations of exterior complex scaling, the scattering wavefunction can be generated with arbitrary accuracy on any finite volume in the space of electronic coordinates, but there remains the fundamental problem of extracting the breakup amplitudes from it. Methods are described for evaluating these amplitudes. The question of the volume-dependent overall phase that appears in the formal theory of ionization is resolved. A summary is presented of accurate results that have been obtained for the case of electron-impact ionization of hydrogen as well as a discussion of applications to the double photoionization of helium.
Coulomb and nuclear effects in breakup and reaction cross sections
NASA Astrophysics Data System (ADS)
Descouvemont, P.; Canto, L. F.; Hussein, M. S.
2017-01-01
We use a three-body continuum discretized coupled channel (CDCC) model to investigate Coulomb and nuclear effects in breakup and reaction cross sections. The breakup of the projectile is simulated by a finite number of square integrable wave functions. First we show that the scattering matrices can be split in a nuclear term and in a Coulomb term. This decomposition is based on the Lippmann-Schwinger equation and requires the scattering wave functions. We present two different methods to separate both effects. Then, we apply this separation to breakup and reaction cross sections of 7Li+208Pb . For breakup, we investigate various aspects, such as the role of the α +t continuum, the angular-momentum distribution, and the balance between Coulomb and nuclear effects. We show that there is a large ambiguity in defining the Coulomb and nuclear breakup cross sections, since both techniques, although providing the same total breakup cross sections, strongly differ for the individual components. We suggest a third method which could be efficiently used to address convergence problems at large angular momentum. For reaction cross sections, interference effects are smaller, and the nuclear contribution is dominant above the Coulomb barrier. We also draw attention to different definitions of the reaction cross section which exist in the literature and which may induce small, but significant, differences in the numerical values.
Nonstationary multistate Coulomb and multistate exponential models for nonadiabatic transitions
Ostrovsky, V. N.
2003-07-01
The nonstationary Schroedinger equation is considered in a finite basis of states. The model Hamiltonian matrix corresponds to a single diabatic potential curve with a Coulombic {approx}1/t time dependence. An arbitrary number of other diabatic potential curves are flat, i.e., time independent and have arbitrary energies. Related states are coupled by constant interactions with the Coulomb state. The resulting nonstationary Schroedinger equation is solved by the method of contour integral. Probabilities of transitions to any other state are obtained as t{yields}{infinity} in a simple analytical form for the case when the Coulomb state is populated initially (at instant of time t{yields}+0). The formulas apply both to the cases when a horizontal diabatic potential curve is crossed by the Coulomb one and to a noncrossing situation. In the limit of weak coupling, the transition probabilities are interpreted in terms of a sequence of pairwise Landau-Zener-type transitions. Mapping of the Coulomb model onto an exactly solvable exponential multistate model is established. For the special two-state case, the well-known Nikitin model is recovered.
Three-body Coulomb bound states
NASA Astrophysics Data System (ADS)
Bhatia, A. K.; Drachman, Richard J.
1987-05-01
The binding energies of three-particle systems containing two electrons and one positive particle of mass M are reexamined in an attempt to understand the approximate proportionality of the 1Se ground-state binding energies of the reduced masses, as pointed out by Botero and Green (1986). The contribution to the energy of the mass-polarization term is evaluated. No fundamental principle is involved, since the mass polarization merely decreases somewhat as the mass of the positive particle is reduced below the proton mass. In the case of the excited 3Pe state, this reduction is not sufficient to allow binding when M approaches the electron mass. Some properties of the recently observed negative muonium ion (e/-/ mu/+/ e/-/) are also computed.
Three-body Coulomb bound states
NASA Technical Reports Server (NTRS)
Bhatia, A. K.; Drachman, Richard J.
1987-01-01
The binding energies of three-particle systems containing two electrons and one positive particle of mass M are reexamined in an attempt to understand the approximate proportionality of the 1Se ground-state binding energies of the reduced masses, as pointed out by Botero and Green (1986). The contribution to the energy of the mass-polarization term is evaluated. No fundamental principle is involved, since the mass polarization merely decreases somewhat as the mass of the positive particle is reduced below the proton mass. In the case of the excited 3Pe state, this reduction is not sufficient to allow binding when M approaches the electron mass. Some properties of the recently observed negative muonium ion (e/-/ mu/+/ e/-/) are also computed.
Features of non-congruent phase transition in modified Coulomb model of the binary ionic mixture
NASA Astrophysics Data System (ADS)
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 < 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.
Thermodynamic functions of the hcp Coulomb crystal lattice
NASA Astrophysics Data System (ADS)
Kozhberov, A. A.; Baiko, D. A.
2015-10-01
One-component Coulomb crystals of ions with hexagonal close-packed (hcp) lattice likely form in the crust of strongly-magnetized neutron stars (magnetars). In this work we present a detailed study of vibration modes and thermodynamic properties of such crystals in a wide range of temperatures at zero magnetic field. In contrast to typically considered lattices, the phonon spectrum of the system exhibits a peculiar crossing of the acoustic modes near the Brillouin zone center in certain directions of the wavevector. It is demonstrated that in the field-free regime the Helmholtz free energy of the hcp Coulomb crystal is always higher than those of the Coulomb crystals with body-centered cubic and face-centered cubic lattices. The results of our numerical calculations are fitted by simple analytic expressions.
Coulomb matrix elements in multi-orbital Hubbard models
NASA Astrophysics Data System (ADS)
Bünemann, Jörg; Gebhard, Florian
2017-04-01
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.
Coulomb explosion of the hot spot of micropinches
NASA Astrophysics Data System (ADS)
Oreshkin, V. I.; Oreshkin, E. V.
2017-01-01
It has been shown that the generation of hard X-ray radiation, electron beam, and high energy ions that have been detected in experiments on compressing pinches can be related to the Coulomb explosion of a micropinch hot spot, which is formed due to the outflow of the material. In the outflow process, the plasma temperature in the hot spot increases and conditions appear for the transition of electrons to the regime of continuous acceleration. The exit of runaway electrons from the hot spot region leads to the creation of a positive bulk charge, then to a Coulomb explosion. Conditions under which electrons pass to the continuous acceleration regime have been determined and estimates of the ion kinetic energy upon a Coulomb explosion have been obtained.
Gribov horizon and Gribov copies effect in lattice Coulomb gauge
NASA Astrophysics Data System (ADS)
Burgio, Giuseppe; Quandt, Markus; Reinhardt, Hugo; Vogt, Hannes
2017-01-01
Following a recent proposal by Cooper and Zwanziger, we investigate via S U (2 ) lattice simulations the effect on the Coulomb gauge propagators and on the Gribov-Zwanziger confinement mechanism of selecting the Gribov copy with the smallest nontrivial eigenvalue of the Faddeev-Popov operator, i.e., the one closest to the Gribov horizon. Although such choice of gauge drives the ghost propagator towards the prediction of continuum calculations, we find that it actually overshoots the goal. With increasing computer time, we observe that Gribov copies with arbitrarily small eigenvalues can be found. For such a method to work, one would therefore need further restrictions on the gauge condition to isolate the physically relevant copies, since, for example, the Coulomb potential VC defined through the Faddeev-Popov operator becomes otherwise physically meaningless. Interestingly, the Coulomb potential alternatively defined through temporal link correlators is only marginally affected by the smallness of the eigenvalues.
Coulomb branch Hilbert series and Hall-Littlewood polynomials
NASA Astrophysics Data System (ADS)
Cremonesi, Stefano; Hanany, Amihay; Mekareeya, Noppadol; Zaffaroni, Alberto
2014-09-01
There has been a recent progress in understanding the chiral ring of 3d = 4 superconformal gauge theories by explicitly constructing an exact generating function (Hilbert series) counting BPS operators on the Coulomb branch. In this paper we introduce Coulomb branch Hilbert series in the presence of background magnetic charges for flavor symmetries, which are useful for computing the Hilbert series of more general theories through gluing techniques. We find a simple formula of the Hilbert series with background magnetic charges for T ρ ( G) theories in terms of Hall-Littlewood polynomials. Here G is a classical group and ρ is a certain partition related to the dual group of G. The Hilbert series for vanishing background magnetic charges show that Coulomb branches of T ρ ( G) theories are complete intersections. We also demonstrate that mirror symmetry maps background magnetic charges to baryonic charges.
Computing Maximally Supersymmetric Scattering Amplitudes
NASA Astrophysics Data System (ADS)
Stankowicz, James Michael, Jr.
This dissertation reviews work in computing N = 4 super-Yang--Mills (sYM) and N = 8 maximally supersymmetric gravity (mSUGRA) scattering amplitudes in D = 4 spacetime dimensions in novel ways. After a brief introduction and overview in Ch. 1, the various techniques used to construct amplitudes in the remainder of the dissertation are discussed in Ch. 2. This includes several new concepts such as d log and pure integrand bases, as well as how to construct the amplitude using exactly one kinematic point where it vanishes. Also included in this chapter is an outline of the Mathematica package on shell diagrams and numerics.m (osdn) that was developed for the computations herein. The rest of the dissertation is devoted to explicit examples. In Ch. 3, the starting point is tree-level sYM amplitudes that have integral representations with residues that obey amplitude relations. These residues are shown to have corresponding residue numerators that allow a double copy prescription that results in mSUGRA residues. In Ch. 4, the two-loop four-point sYM amplitude is constructed in several ways, showcasing many of the techniques of Ch. 2; this includes an example of how to use osdn. The two-loop five-point amplitude is also presented in a pure integrand representation with comments on how it was constructed from one homogeneous cut of the amplitude. On-going work on the two-loop n-point amplitude is presented at the end of Ch. 4. In Ch. 5, the three-loop four-point amplitude is presented in the d log representation and in the pure integrand representation. In Ch. 6, there are several examples of four- through seven-loop planar diagrams that illustrate how considerations of the singularity structure of the amplitude underpin dual-conformal invariance. Taken with the previous examples, this is additional evidence that the structure known to exist in the planar sector extends to the full theory. At the end of this chapter is a proof that all mSUGRA amplitudes have a pole at
Tree-augmented Cox proportional hazards models.
Su, Xiaogang; Tsai, Chih-Ling
2005-07-01
We study a hybrid model that combines Cox proportional hazards regression with tree-structured modeling. The main idea is to use step functions, provided by a tree structure, to 'augment' Cox (1972) proportional hazards models. The proposed model not only provides a natural assessment of the adequacy of the Cox proportional hazards model but also improves its model fitting without loss of interpretability. Both simulations and an empirical example are provided to illustrate the use of the proposed method.
Lorentzian proper vertex amplitude: Asymptotics
NASA Astrophysics Data System (ADS)
Engle, Jonathan; Vilensky, Ilya; Zipfel, Antonia
2016-09-01
In previous work, the Lorentzian proper vertex amplitude for a spin-foam model of quantum gravity was derived. In the present work, the asymptotics of this amplitude are studied in the semiclassical limit. The starting point of the analysis is an expression for the amplitude as an action integral with action differing from that in the Engle-Pereira-Rovelli-Livine (EPRL) case by an extra "projector" term. This extra term scales linearly with spins only in the asymptotic limit, and is discontinuous on a (lower dimensional) submanifold of the integration domain in the sense that its value at each such point depends on the direction of approach. New tools are introduced to generalize stationary phase methods to this case. For the case of boundary data which can be glued to a nondegenerate Lorentzian 4-simplex, the asymptotic limit of the amplitude is shown to equal the single Feynman term, showing that the extra term in the asymptotics of the EPRL amplitude has been eliminated.
Effect of Coulombic friction on spatial displacement statistics.
Menzel, Andreas M; Goldenfeld, Nigel
2011-07-01
The phenomenon of Coulombic friction enters the stochastic description of dry friction between two solids and the statistic characterization of vibrating granular media. Here we analyze the corresponding Fokker-Planck equation including both velocity and spatial components, exhibiting a formal connection to a quantum mechanical harmonic oscillator in the presence of a delta potential. Numerical solutions for the resulting spatial displacement statistics show a crossover from exponential to Gaussian displacement statistics. We identify a transient intermediate regime that exhibits multiscaling properties arising from the contribution of Coulombic friction. The possible role of these effects during observations in diffusion experiments is briefly discussed.
Separable wave equation for three Coulomb interacting particles
NASA Astrophysics Data System (ADS)
Colavecchia, F. D.; Gasaneo, G.; Garibotti, C. R.
1998-02-01
We consider a separable approximation to the Schrödinger equation for the three-body Coulomb problem and found its exact solution above the ionization threshold. This wave function accounts for different possible asymptotic behaviors and reduces to the well-known product of three two-body Coulomb waves (C3) for scattering conditions. The momenta and position-dependent modifications recently proposed for the Sommerfeld parameters, as an improvement to the C3 model, are analyzed. We show how these changes can be included in our model as a suitable physically based variations in the separable approximation for the wave equation.
On rate-state and Coulomb failure models
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
Convergence of Feynman integrals in Coulomb gauge QCD
Andraši, A.; Taylor, J.C.
2014-12-15
At 2-loop order, Feynman integrals in the Coulomb gauge are divergent over the internal energy variables. Nevertheless, it is known how to calculate the effective action, provided that the external gluon fields are all transverse. We show that, for the two-gluon Greens function as an example, the method can be extended to include longitudinal external fields. The longitudinal Greens functions appear in the BRST identities. As an intermediate step, we use a flow gauge, which interpolates between the Feynman and Coulomb gauges.
Higher-order dynamical effects in Coulomb dissociation
Esbensen, H.; Bertsch, G.F.; Bertulani, C.A.
1995-08-01
Coulomb dissociation is a technique commonly used to extract the dipole response of nuclei far from stability. This technique is applicable if the dissociation is dominated by dipole transitions and if first-order perturbation theory is valid. In order to assess the significance of higher-order processes we solve numerically the time evolution of the wave function for a two-body breakup in the Coulomb field from a high Z target. We applied this method to the breakup reactions: {sup 11}Be {yields} {sup 10}Be + n and {sup 11}Li {yields} +2n. The latter is treated as a two-body breakup, using a di-neutron model.
Running Coulomb potential and Lamb shift in QCD
Hoang, Andre H.; Manohar, Aneesh V.; Stewart, Iain W.
2001-07-01
The QCD {beta} function and the anomalous dimensions for the Coulomb potential and the static potential first differ at three loop order. We evaluate the three loop ultrasoft anomalous dimension for the Coulomb potential and give the complete three loop running. Using this result, we calculate the leading logarithmic Lamb shift for a heavy-quark{endash}antiquark bound state, which includes all contributions to the binding energies of the form m{alpha}{sub s}{sup 4}({alpha}{sub s}ln{alpha}{sub s}){sup k}, k{ge}0.
Factorization of chiral string amplitudes
NASA Astrophysics Data System (ADS)
Huang, Yu-tin; Siegel, Warren; Yuan, Ellis Ye
2016-09-01
We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory. We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes. The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor. This cancels all but a finite number of states: as found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory. However, we now find for the other cases that additional fields, formerly thought to be auxiliary, describe new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic). The tachyon is always a ghost, but can be avoided in the heterotic case.
Coulomb effect and threshold effect in electronic stopping power for slow protons
Semrad, D.
1986-03-01
We show how the electronic stopping power for slow protons is influenced by the deceleration and deflection of the projectile in the field of the target nucleus (Coulomb effect) and by the fact that in insulators a finite energy is also required for excitation of the outermost electrons (threshold effect). Estimates are derived from the Fermi-Teller description of the stopping process, from a modified local-density approximation, and from measured inner-shell ionization cross sections. It is found that the introduction of an energy threshold reduces at low energies the stopping cross section by a large factor and hence leads to an appreciable deviation from v/sub 1/ proportionality.
CCSSM Challenge: Graphing Ratio and Proportion
ERIC Educational Resources Information Center
Kastberg, Signe E.; D'Ambrosio, Beatriz S.; Lynch-Davis, Kathleen; Mintos, Alexia; Krawczyk, Kathryn
2013-01-01
A renewed emphasis was placed on ratio and proportional reasoning in the middle grades in the Common Core State Standards for Mathematics (CCSSM). The expectation for students includes the ability to not only compute and then compare and interpret the results of computations in context but also interpret ratios and proportions as they are…
Prospective Elementary School Teachers' Proportional Reasoning
ERIC Educational Resources Information Center
Valverde, Gabriela; Castro, Encarnación
2012-01-01
We present the findings of a study on prospective elementary teachers' proportional reasoning. After describing some of the teachers' performance in solving multiplicative structure problems that involve ratios and relations of direct proportionality between quantities, we were able to establish classifications of their answers according to…
Examining Prospective Teachers' Understanding of Proportional Reasoning
ERIC Educational Resources Information Center
Kitchen, Richard; DePree, Julie
2004-01-01
In this article, the authors describe their efforts to assess prospective K-8 teachers' knowledge of proportional reasoning. Based upon their analysis of prospective K-8 teachers' work on a mathematics performance task, they discuss the implications for preparing prospective teachers to teach proportional reasoning to their students. In general,…
Working Memory Mechanism in Proportional Quantifier Verification
ERIC Educational Resources Information Center
Zajenkowski, Marcin; Szymanik, Jakub; Garraffa, Maria
2014-01-01
The paper explores the cognitive mechanisms involved in the verification of sentences with proportional quantifiers (e.g. "More than half of the dots are blue"). The first study shows that the verification of proportional sentences is more demanding than the verification of sentences such as: "There are seven blue and eight yellow…
NASA Astrophysics Data System (ADS)
Jiang, Xiao-Song; He, Guo-Qiu; Liu, Bing; Zhu, Zheng-Yu; Zhang, Wei-Hua
2011-08-01
With the increasing use of Al-Si-Mg alloys in the automotive industry, the fatigue performance of Al-Si-Mg alloy has become a major concern with regard to their reliability. The fatigue characteristics and microcosmic mechanism of an Al-Si-Mg alloy under multiaxial proportional loadings were investigated in this research. As low cycle fatigue life and material strengthening behavior are closely related, the effect of equivalent strain amplitude on the multiaxial fatigue properties was analyzed. Fatigue tests were conducted to determine the influence of equivalent strain amplitude on the multiaxial proportional fatigue properties. The fatigue life exhibits a stable behavior under multiaxial proportional loadings. The dislocation structures of the Al-Si-Mg alloy were observed by transmission electron microscopy (TEM). The dislocation structure evolution of the Al-Si-Mg alloy under multiaxial proportional loadings during low cycle fatigue develops step by step by increasing fatigue cycles. Simultaneously, the dislocation structure changes with the change in equivalent strain amplitude under multiaxial proportional loadings. The experimental evidence indicates that the multiaxial fatigue behavior and life are strongly dependent on the microstructure of the material, which is caused by multiaxial proportional loadings.
Toward complete pion nucleon amplitudes
Mathieu, Vincent; Danilkin, Igor V.; Fernández-Ramírez, Cesar; ...
2015-10-05
We compare the low-energy partial wave analyses πN scattering with a high-energy data via finite energy sum rules. We also construct a new set of amplitudes by matching the imaginary part from the low-energy analysis with the high-energy, Regge parametrization and then reconstruct the real parts using dispersion relations.
Large amplitude drop shape oscillations
NASA Technical Reports Server (NTRS)
Trinh, E. H.; Wang, T. G.
1982-01-01
An experimental study of large amplitude drop shape oscillation was conducted in immiscible liquids systems and with levitated free liquid drops in air. In liquid-liquid systems the results indicate the existence of familiar characteristics of nonlinear phenomena. The resonance frequency of the fundamental quadrupole mode of stationary, low viscosity Silicone oil drops acoustically levitated in water falls to noticeably low values as the amplitude of oscillation is increased. A typical, experimentally determined relative frequency decrease of a 0.5 cubic centimeters drop would be about 10% when the maximum deformed shape is characterized by a major to minor axial ratio of 1.9. On the other hand, no change in the fundamental mode frequency could be detected for 1 mm drops levitated in air. The experimental data for the decay constant of the quadrupole mode of drops immersed in a liquid host indicate a slight increase for larger oscillation amplitudes. A qualitative investigation of the internal fluid flows for such drops revealed the existence of steady internal circulation within drops oscillating in the fundamental and higher modes. The flow field configuration in the outer host liquid is also significantly altered when the drop oscillation amplitude becomes large.
Isotope shifts and coulomb displacement energies in calcium isotopes
NASA Astrophysics Data System (ADS)
Caurier, E.; Poves, A.; Zuker, A.
1980-10-01
Isotope shifts, neutron-proton radii differences and Coulomb displacement energies are calculated for calcium isotopes A = 41 to 48. A simple parametrization of the core polarization terms of the effective force in the framework of the Isospin Projected Hartree-Fock (IPHF) method leads to good agreement between theory and experiment.
Using the Screened Coulomb Potential to Illustrate the Variational Method
ERIC Educational Resources Information Center
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…
Coulomb repulsion and the electron beam directed energy weapon
NASA Astrophysics Data System (ADS)
Retsky, Michael W.
2004-09-01
Mutual repulsion of discrete charged particles or Coulomb repulsion is widely considered to be an ultimate hard limit in charged particle optics. It prevents the ability to finely focus high current beams into small spots at large distances from defining apertures. A classic example is the 1970s era "Star Wars" study of an electron beam directed energy weapon as an orbiting antiballistic missile device. After much analysis, it was considered physically impossible to focus a 1000-amp 1-GeV beam into a 1-cm diameter spot 1000-km from the beam generator. The main reason was that a 1-cm diameter beam would spread to 5-m diameter at 1000-km due to Coulomb repulsion. Since this could not be overcome, the idea was abandoned. But is this true? What if the rays were reversed? That is, start with a 5-m beam converging slightly with the same nonuniform angular and energy distribution as the electrons from the original problem were spreading at 1000-km distance. Could Coulomb repulsion be overcome? Looking at the terms in computational studies, some are reversible while others are not. Based on estimates, the nonreversible terms should be small - of the order of 0.1 mm. If this is true, it is possible to design a practical electron beam directed weapon not limited by Coulomb repulsion.
Limits to Electron Beam Emittance from Stochastic Coulomb Interactions
Coleman-Smith, Christopher; Padmore, Howard A.; Wan, Weishi
2008-08-22
Dense electron beams can now be generated on an ultrafast timescale using laser driven photo-cathodes and these are used for a range of applications from ultrafast electron defraction to free electron lasers. Here we determine a lower bound to the emittance of an electron beam limited by fundamental stochastic Coulomb interactions.
Exchange Coulomb interaction in nanotubes: Dispersion of Langmuir waves
Andreev, P. A. Ivanov, A. Yu.
2015-07-15
The microscopic derivation of the Coulomb exchange interaction for electrons located on the nanotubes is presented. The derivation is based on the many-particle quantum hydrodynamic method. We demonstrate the effect of curvature of the nanocylinders on the force of exchange interaction. We calculate corresponding dispersion dependencies for electron oscillations on the nanotubes.
Coulomb gauge approach for charmonium meson and hybrid radiative transitions
Gou, Peng; Yepez-Martínez, Tochtli; Szczepaniak, Adam P.
2015-01-22
We consider the lowest order interaction of the Foldy-Wouthuysen QED and QCD Hamiltonian in the Coulomb gauge approach, to describe radiative transitions between conventional and hybrids charmonium mesons. The results are compared to potential quark models and lattices calculations.
Accurate Coulomb blockade thermometry up to 60 kelvin.
Meschke, M; Kemppinen, A; Pekola, J P
2016-03-28
We demonstrate experimentally a precise realization of Coulomb blockade thermometry working at temperatures up to 60 K. Advances in nano-fabrication methods using electron beam lithography allow us to fabricate uniform arrays of sufficiently small tunnel junctions to guarantee an overall temperature reading precision of about 1%.
Existence of the thermodynamic limit for disordered quantum Coulomb systems
NASA Astrophysics Data System (ADS)
Blanc, Xavier; Lewin, Mathieu
2012-09-01
Following a recent method introduced by Hainzl, Solovej, and Lewin, we prove the existence of the thermodynamic limit for a system made of quantum electrons, and classical nuclei whose positions and charges are randomly perturbed in an ergodic fashion. All the particles interact through Coulomb forces.
Finiteness of the Coulomb gauge QCD perturbative effective action
Andraši, A.; Taylor, J.C.
2015-05-15
At 2-loop order in the Coulomb gauge, individual Feynman graphs contributing to the effective action have energy divergences. It is proved that these cancel in suitable combinations of graphs. This has previously been shown only for transverse external fields. The calculation results in a generalization of the Christ–Lee term which was inserted into the Hamiltonian.
Application of Designer Polynomials to the Soft-Coulomb Potential
NASA Astrophysics Data System (ADS)
Weatherford, Charles; Wynn, Albert, III; Red, Eddie; Mathis, Clausell
2004-05-01
In a recent article [C.A. Weatherford, E. Red, A. Wynn III, International Journal of Quantum Chemistry 90, 1289-1294 (2002)], an algorithm was described whereby a synthetic weighted polynomial basis may be constructed which is adapted (designed) to a particular potential. It was applied therein to the Schroedinger equation with a coulomb potential in one dimension (-1/|x| ). A weighted polynomial basis with weight function w(x)=exp(-a|x|) was employed. It was observed that this potential had no even parity solutions - only odd parity solutions. The question arises as to the relationship of the solutions (eigenfunctions and eigenvalues) for this hard coulomb potential to the solutions for the soft coulomb potential (-1/ √x^2+b^2^1/2 ). In particular, since the soft coulomb potential is clearly expected to possess both even and odd parity solutions, how do these solutions behave as b->0 and thus what happens to the even solutions. This problem is deceptively difficult none of the standard basis sets produce a variational minimum as a function of 'a' for nonzero 'b'. This is apparently why this problem has never been done before. A new orthonormal basis was designed with weight function w(x)=exp(-a√x^2+b^2) which did produce a variational minimum for variable a and arbitrary fixed 'b'. The present paper describes these solutions and clearly indicates how they behave as b->0 .
Hamiltonian flow in Coulomb gauge Yang-Mills theory
Leder, Markus; Reinhardt, Hugo; Pawlowski, Jan M.; Weber, Axel
2011-01-15
We derive a new functional renormalization group equation for Hamiltonian Yang-Mills theory in Coulomb gauge. The flow equations for the static gluon and ghost propagators are solved under the assumption of ghost dominance within different diagrammatic approximations. The results are compared to those obtained in the variational approach and the reliability of the approximations is discussed.
Reassessing manual proportions in Australopithecus afarensis.
Rolian, Campbell; Gordon, Adam D
2013-11-01
Previous analyses of hand morphology in Australopithecus afarensis have concluded that this taxon had modern human-like manual proportions, with relatively long thumbs and short fingers. These conclusions are based on the A.L.333 composite fossil assemblage from Hadar, Ethiopia, and are premised on the ability to assign phalanges to a single individual, and to the correct side and digit. Neither assignment is secure, however, given the taphonomy and sample composition at A.L.333. We use a resampling approach that includes the entire assemblage of complete hand elements at Hadar, and takes into account uncertainties in identifying phalanges by individual, side and digit number. This approach provides the most conservative estimates of manual proportions in Au. afarensis. We resampled hand long bone lengths in Au. afarensis and extant hominoids, and obtained confidence limits for distributions of manual proportions in the latter. Results confirm that intrinsic manual proportions in Au. afarensis are dissimilar to Pan and Pongo. However, manual proportions in Au. afarensis often fall at the upper end of the distribution in Gorilla, and very lower end in Homo, corresponding to disproportionately short thumbs and long medial digits in Homo. This suggests that manual proportions in Au. afarensis, particularly metacarpal proportions, were not as derived towards Homo as previously described, but rather are intermediate between gorillas and humans. Functionally, these results suggest Au. afarensis could not produce precision grips with the same efficiency as modern humans, which may in part account for the absence of lithic technology in this fossil taxon.
Non-Sticking Oscillation Formulae for Coulomb Friction Under Harmonic Loading
NASA Astrophysics Data System (ADS)
HONG, H.-K.; LIU, C.-S.
2001-07-01
In this paper, a new estimate for periodic non-sticking (i.e., zero stop per cycle) solutions is presented for the steady state responses of the Coulomb friction oscillator subjected to harmonic loading. Compared with the Den Hartog (1931 Transactions of the American Society of Mechanical Engineers53, 107-115 [1]) estimate, the new estimate leads to the same formulae for the maximum displacement and its time lag, but only the new estimate offers the closed-form formulae for the maximum velocity and its time lag. More importantly, a simple formula is derived for estimating the minimum driving force amplitude needed to prevent an oscillating object from sticking to the friction surface on which it slides. The validity of the assumptions made for the new estimate and the accuracy of the formulae developed are confirmed by comparing with the exact solutions (Hong and Liu 2000 Journal of Sound and Vibration229, 1171-1192 [2]). It is also found that there exists the best driving force amplitude for maximum dissipation efficiency.
Proportion of recovered waterfowl bands reported
Geis, A.D.; Atwood, E.L.
1961-01-01
Data from the annual mail survey of waterfowl hunters in the United States were used to estimate the total numbers of banded waterfowl that were shot. These estimates were compared with Banding Office records to estimate the proportion of recovered bands that was reported. On the average, about two banded birds were recovered for each one reported. The proportion reported was higher for some areas and for some species than for others. The proportion reported was higher when more of the reports came through employees of conservation agencies.
Using Resampling to Compare Two Proportions
ERIC Educational Resources Information Center
Stephenson, W. Robert; Froelich, Amy G.; Duckworth, William M.
2010-01-01
This article shows that when applying resampling methods to the problem of comparing two proportions, students can discover that whether you resample with or without replacement can make a big difference.
Proportionality, just war theory and weapons innovation.
Forge, John
2009-03-01
Just wars are supposed to be proportional responses to aggression: the costs of war must not greatly exceed the benefits. This proportionality principle raises a corresponding 'interpretation problem': what are the costs and benefits of war, how are they to be determined, and a 'measurement problem': how are costs and benefits to be balanced? And it raises a problem about scope: how far into the future do the states of affairs to be measured stretch? It is argued here that weapons innovation always introduces costs, and that these costs cannot be determined in advance of going to war. Three examples, the atomic bomb, the AK-47 and the ancient Greek catapult, are given as examples. It is therefore argued that the proportionality principle is inapplicable prospectively. Some replies to the argument are discussed and rejected. Some more general defences of the proportionality principle are considered and also rejected. Finally, the significance of the argument for Just War Theory as a whole is discussed.
Proportion estimation using prior cluster purities
NASA Technical Reports Server (NTRS)
Terrell, G. R. (Principal Investigator)
1980-01-01
The prior distribution of CLASSY component purities is studied, and this information incorporated into maximum likelihood crop proportion estimators. The method is tested on Transition Year spring small grain segments.
Compact Collision Kernels for Hard Sphere and Coulomb Cross Sections; Fokker-Planck Coefficients
Chang Yongbin; Shizgal, Bernie D.
2008-12-31
A compact collision kernel is derived for both hard sphere and Coulomb cross sections. The difference between hard sphere interaction and Coulomb interaction is characterized by a parameter {eta}. With this compact collision kernel, the calculation of Fokker-Planck coefficients can be done for both the Coulomb and hard sphere interactions. The results for arbitrary order Fokker-Planck coefficients are greatly simplified. An alternate form for the Coulomb logarithm is derived with concern to the temperature relaxation in a binary plasma.
Pulse amplitude modulated chlorophyll fluorometer
Greenbaum, Elias; Wu, Jie
2015-12-29
Chlorophyll fluorometry may be used for detecting toxins in a sample because of changes in micro algae. A portable lab on a chip ("LOAC") based chlorophyll fluorometer may be used for toxin detection and environmental monitoring. In particular, the system may include a microfluidic pulse amplitude modulated ("PAM") chlorophyll fluorometer. The LOAC PAM chlorophyll fluorometer may analyze microalgae and cyanobacteria that grow naturally in source drinking water.
Genus dependence of superstring amplitudes
Davis, Simon
2006-11-15
The problem of the consistency of the finiteness of the supermoduli space integral in the limit of vanishing super-fixed point distance and the genus-dependence of the integral over the super-Schottky coordinates in the fundamental region containing a neighborhood of |K{sub n}|=0 is resolved. Given a choice of the categories of isometric circles representing the integration region, the exponential form of bounds for superstring amplitudes is derived.
Phase variation of hadronic amplitudes
Dedonder, J.-P.; Gibbs, W. R.; Nuseirat, Mutazz
2008-04-15
The phase variation with angle of hadronic amplitudes is studied with a view to understanding the underlying physical quantities that control it and how well it can be determined in free space. We find that unitarity forces a moderately accurate determination of the phase in standard amplitude analyses but that the nucleon-nucleon analyses done to date do not give the phase variation needed to achieve a good representation of the data in multiple scattering calculations. Models are examined that suggest its behavior near forward angles is related to the radii of the real and absorptive parts of the interaction. The dependence of this phase on model parameters is such that if these radii are modified in the nuclear medium (in combination with the change due to the shift in energy of the effective amplitude in the medium) then the larger magnitudes of the phase needed to fit the data might be attainable but only for negative values of the phase variation parameter.
Blocage de Coulomb dans une boite quantique laterale contenant un faible nombre d'electrons
NASA Astrophysics Data System (ADS)
Gould, Charles
Dans ce travail on utilise une nouvelle geometrie pour augmenter le controle sur le nombre d'electrons contenus dans une boite quantique laterale, et ainsi atteindre un regime de petit nombre d'electrons. Ces echantillons permettent une etude du blocage de Coulomb quand les electrons sont injectes a partir d'un gaz electronique a deux dimensions (2DEG). Les mesures a faible champ magnetique demontrent la grande flexibilite des echantillons et montrent que l'on peut faire varier le nombre d'electrons dans une boite quantique a partir de plus de 40 electrons jusqu'a un seul electron, ce qui est assez courant dans les boites quantiques verticales, mais ce qui n'avait jamais ete reussi dans une boite quantique laterale. Nos resultats montrent egalement que dans les boites quantiques laterales il est possible de determiner le spin du niveau qui participe au transport a l'aide du phenomene de blocage de spin. De plus, dans certaines circonstances il est meme possible de determiner le spin total de la boite quantique, ce qui peut avoir des applications pratiques dans des domaines tels l'informatique quantique. Les mesures dans le regime de renversement de spin a un champ magnetique plus eleve montrent l'importance des correlations electrons---electrons dans ces boites quantiques, qui menent a des depolarisations et a des structures de spins qui ont un effet sur le transport. En particulier, ces correlations menent a l'existence de niveaux excites de basse energie qui causent une dependance anormale de l'amplitude des pics de blocage de Coulomb en fonction de la temperature. Nos experiences demontrent egalement la possibilite d'utiliser ces boites quantiques comme sondes pour etudier les proprietes du bord d'un 2DEG. Une voie de recherche a etre exploree.
Crisis in Amplitude Control Hides in Multistability
NASA Astrophysics Data System (ADS)
Li, Chunbiao; Sprott, Julien Clinton; Xing, Hongyan
2016-12-01
A crisis of amplitude control can occur when a system is multistable. This paper proposes a new chaotic system with a line of equilibria to demonstrate the threat to amplitude control from multistability. The new symmetric system has two coefficients for amplitude control, one of which is a partial amplitude controller, while the other is a total amplitude controller that simultaneously controls the frequency. The amplitude parameter rescales the basins of attraction and triggers a state switch among different states resulting in a failure of amplitude control to the desired state.
Amplitude effects on the dynamic performance of hydrostatic gas thrust bearings
NASA Technical Reports Server (NTRS)
Stiffler, A. K.; Tapia, R. R.
1979-01-01
A strip gas film bearing with inherently compensated inlets is analyzed to determine the effect of disturbance amplitude on its dynamic performance. The governing Reynolds' equation is solved using finite-difference techniques. The time dependent load capacity is represented by a Fourier series up to and including the third harmonics. For the range of amplitudes investigated the linear stiffness was independent of the amplitude, and the linear damping was inversely proportional to (1 - epsilon-squared) to the 1.5 power where epsilon is the amplitude relative to the film thickness.
Calculation of multi-loop superstring amplitudes
NASA Astrophysics Data System (ADS)
Danilov, G. S.
2016-12-01
The multi-loop interaction amplitudes in the closed, oriented superstring theory are obtained by the integration of local amplitudes. The local amplitude is represented by a sum over the spinning string local amplitudes. The spinning string local amplitudes are given explicitly through super-Schottky group parameters and through interaction vertex coordinates on the (1| 1) complex, non-split supermanifold. The obtained amplitudes are free from divergences. They are consistent with the world-sheet spinning string symmetries. The vacuum amplitude vanishes along with 1-, 2- and 3-point amplitudes of massless states. The vanishing of the above-mentioned amplitude occurs after the integration of the corresponding local amplitude has been performed over the super-Schottky group limiting points and over interaction vertex coordinate, except for those (3| 2) variables which are fixed due to SL(2)-symmetry.
Testing departure from Hardy-Weinberg proportions.
Wang, Jian; Shete, Sanjay
2012-01-01
The Hardy-Weinberg principle, one of the most important principles in population genetics, was originally developed for the study of allele frequency changes in a population over generations. It is now, however, widely used in studies of human diseases to detect inbreeding, populations stratification, and genotyping errors. For assessment of deviation from the Hardy-Weinberg proportions in data, the most popular approaches include the asymptotic Pearson's chi-square goodness-of-fit test and the exact test. The Pearson's chi-square goodness-of-fit test is simple and straightforward, but it is very sensitive to small sample size or rare allele frequency. The exact test of Hardy-Weinberg proportions is preferable in these situations. The exact test can be performed through complete enumeration of heterozygote genotypes or on the basis of the Markov chain Monte Carlo procedure. In this chapter, we describe the Hardy-Weinberg principle and the commonly used Hardy-Weinberg proportions tests and their applications, and we demonstrate how the chi-square test and exact test of Hardy-Weinberg proportions can be performed step-by-step using the popular software programs SAS, R, and PLINK, which have been widely used in genetic association studies, along with numerical examples. We also discuss recent approaches for testing Hardy-Weinberg proportions in case-control study designs that are better than traditional approaches for testing Hardy-Weinberg proportions in controls only. Finally, we note that deviation from the Hardy-Weinberg proportions in affected individuals can provide evidence for an association between genetic variants and diseases.
Culham, Doreen E.; Shkel, Irina A.; Record, M. Thomas; Wood, Janet M.
2016-01-01
Osmosensing transporters mediate osmolyte accumulation to forestall cellular dehydration as the extracellular osmolality increases. ProP is a bacterial osmolyte-H+ symporter, a major facilitator superfamily member, and a paradigm for osmosensing. ProP activity is a sigmoid function of the osmolality. It is determined by the osmolality, not the magnitude or direction of the osmotic shift, in cells and salt-loaded proteoliposomes. The activation threshold varies directly with the proportion of anionic phospholipid in cells and proteoliposomes. The osmosensory mechanism was probed by varying the salt composition and concentration outside and inside proteoliposomes. Data analysis was based on the hypothesis that the fraction of maximal transporter activity at a particular luminal salt concentration reflects the proportion of ProP molecules in an active conformation. ProP attained the same activity at the same osmolality when diverse, membrane-impermeant salts were added to the external medium. Contributions of Coulombic and/or Hofmeister salt effects to ProP activation were examined by varying the luminal salt cation (K+ and Na+) and anion (chloride, phosphate, and sulfate) composition and then systematically increasing the luminal salt concentration by increasing the external osmolality. ProP activity increased with the sixth power of the univalent cation concentration, independent of the type of anion. This indicates that salt activation of ProP is a Coulombic, cation effect resulting from salt cation accumulation and not site-specific cation binding. Possible origins of this Coulombic effect include folding or assembly of anionic cytoplasmic ProP domains, an increase in local membrane surface charge density, and/or the juxtaposition of anionic protein and membrane surfaces during activation. PMID:26871755
Culham, Doreen E; Shkel, Irina A; Record, M Thomas; Wood, Janet M
2016-03-08
Osmosensing transporters mediate osmolyte accumulation to forestall cellular dehydration as the extracellular osmolality increases. ProP is a bacterial osmolyte-H(+) symporter, a major facilitator superfamily member, and a paradigm for osmosensing. ProP activity is a sigmoid function of the osmolality. It is determined by the osmolality, not the magnitude or direction of the osmotic shift, in cells and salt-loaded proteoliposomes. The activation threshold varies directly with the proportion of anionic phospholipid in cells and proteoliposomes. The osmosensory mechanism was probed by varying the salt composition and concentration outside and inside proteoliposomes. Data analysis was based on the hypothesis that the fraction of maximal transporter activity at a particular luminal salt concentration reflects the proportion of ProP molecules in an active conformation. ProP attained the same activity at the same osmolality when diverse, membrane-impermeant salts were added to the external medium. Contributions of Coulombic and/or Hofmeister salt effects to ProP activation were examined by varying the luminal salt cation (K(+) and Na(+)) and anion (chloride, phosphate, and sulfate) composition and then systematically increasing the luminal salt concentration by increasing the external osmolality. ProP activity increased with the sixth power of the univalent cation concentration, independent of the type of anion. This indicates that salt activation of ProP is a Coulombic, cation effect resulting from salt cation accumulation and not site-specific cation binding. Possible origins of this Coulombic effect include folding or assembly of anionic cytoplasmic ProP domains, an increase in local membrane surface charge density, and/or the juxtaposition of anionic protein and membrane surfaces during activation.
The Effects of Static Coulomb Stress Change on Southern California Earthquake Forecasting
NASA Astrophysics Data System (ADS)
Strader, Anne Elizabeth
I investigate how inclusion of static Coulomb stress changes, caused by tectonic loading and previous seismicity, contributes to the effectiveness and reliability of prospective earthquake forecasts. Several studies have shown that positive static Coulomb stress changes are associated with increased seismicity, relative to stress shadows. However, it is difficult to avoid bias when the learning and testing intervals are chosen retrospectively. I hypothesize that earthquake forecasts based on static Coulomb stress fields may improve upon existing earthquake forecasts based on historical seismicity. Within southern California, I have confirmed the aforementioned relationship between earthquake location and Coulomb stress change, but found no identifiable triggering threshold based on static Coulomb stress history at individual earthquake locations. I have also converted static Coulomb stress changes into spatially-varying earthquake rates by optimizing an index function and calculating probabilities of cells containing at least one earthquake based on Coulomb stress ranges. Inclusion of Coulomb stress effects gives an improvement in earthquake forecasts that is significant with 95% confidence, compared to smoothed seismicity null forecasts. Because of large uncertainties in Coulomb stress calculations near faults (and aftershock distributions), I combine static Coulomb stress and smoothed seismicity into a hybrid earthquake forecast. Evaluating such forecasts against those in which only Coulomb stress or smoothed seismicity determines earthquake rates indicates that Coulomb stress is more effective in the far field, whereas statistical seismology outperforms Coulomb stress near faults. Additionally, I test effects of receiver plane orientation, stress type (normal and shear components), and declustering receiver earthquakes. While static Coulomb stress shows significant potential in a prospective earthquake forecast, simplifying assumptions compromise its
Progress in studying scintillator proportionality: Phenomenological model
Bizarri, Gregory; Cherepy, Nerine; Choong, Woon-Seng; Hull, Giulia; Moses, William; Payne, Sephen; Singh, Jai; Valentine, John; Vasilev, Andrey; Williams, Richard
2009-04-30
We present a model to describe the origin of non-proportional dependence of scintillator light yield on the energy of an ionizing particle. The non-proportionality is discussed in terms of energy relaxation channels and their linear and non-linear dependences on the deposited energy. In this approach, the scintillation response is described as a function of the deposited energy deposition and the kinetic rates of each relaxation channel. This mathematical framework allows both a qualitative interpretation and a quantitative fitting representation of scintillation non-proportionality response as function of kinetic rates. This method was successfully applied to thallium doped sodium iodide measured with SLYNCI, a new facility using the Compton coincidence technique. Finally, attention is given to the physical meaning of the dominant relaxation channels, and to the potential causes responsible for the scintillation non-proportionality. We find that thallium doped sodium iodide behaves as if non-proportionality is due to competition between radiative recombinations and non-radiative Auger processes.
Conductance of a proximitized nanowire in the Coulomb blockade regime
NASA Astrophysics Data System (ADS)
van Heck, B.; Lutchyn, R. M.; Glazman, L. I.
2016-06-01
We identify the leading processes of electron transport across finite-length segments of proximitized nanowires and build a quantitative theory of their two-terminal conductance. In the presence of spin-orbit interaction, a nanowire can be tuned across the topological transition point by an applied magnetic field. Due to a finite segment length, electron transport is controlled by the Coulomb blockade. Upon increasing of the field, the shape and magnitude of the Coulomb blockade peaks in the linear conductance are defined, respectively, by Andreev reflection, single-electron tunneling, and resonant tunneling through the Majorana modes emerging after the topological transition. Our theory provides the framework for the analysis of experiments with proximitized nanowires [such as reported in S. M. Albrecht et al., Nature (London) 531, 206 (2016), 10.1038/nature17162] and identifies the signatures of the topological transition in the two-terminal conductance.
Coulomb and electron-phonon interactions in metals
NASA Astrophysics Data System (ADS)
Tupitsyn, Igor S.; Mishchenko, Andrey S.; Nagaosa, Naoto; Prokof'ev, Nikolay
2016-10-01
An accurate and consistent theory of phonons in metals requires that all long-range Coulomb interactions between charged particles (electrons and ions) be treated on equal footing. So far, all attempts to deal with this nonperturbative system were relying on uncontrolled approximations in the absence of small parameters. In this paper, we develop the diagrammatic Monte Carlo approach for a two-component Coulomb system that obtains the solution to this fundamental problem in an approximation-free way by computing vertex corrections from higher-order skeleton graphs. The feasibility of the method is demonstrated by calculating the spectrum of longitudinal acoustic phonons in a simple cubic lattice, determining their sound velocity, and obtaining the phonon spectral densities by analytic continuation of the Matsubara-Green's functions. Final results are checked against the lowest-order fully self-consistent G W approximation in both adiabatic and nonadiabatic regimes.
Electronic cooling via interlayer Coulomb coupling in multilayer epitaxial graphene.
Mihnev, Momchil T; Tolsma, John R; Divin, Charles J; Sun, Dong; Asgari, Reza; Polini, Marco; Berger, Claire; de Heer, Walt A; MacDonald, Allan H; Norris, Theodore B
2015-09-24
In van der Waals bonded or rotationally disordered multilayer stacks of two-dimensional (2D) materials, the electronic states remain tightly confined within individual 2D layers. As a result, electron-phonon interactions occur primarily within layers and interlayer electrical conductivities are low. In addition, strong covalent in-plane intralayer bonding combined with weak van der Waals interlayer bonding results in weak phonon-mediated thermal coupling between the layers. We demonstrate here, however, that Coulomb interactions between electrons in different layers of multilayer epitaxial graphene provide an important mechanism for interlayer thermal transport, even though all electronic states are strongly confined within individual 2D layers. This effect is manifested in the relaxation dynamics of hot carriers in ultrafast time-resolved terahertz spectroscopy. We develop a theory of interlayer Coulomb coupling containing no free parameters that accounts for the experimentally observed trends in hot-carrier dynamics as temperature and the number of layers is varied.
Coulomb effects in low-energy nuclear fragmentation
NASA Technical Reports Server (NTRS)
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.
Proton focusing driven by laser triggered Coulomb explosion
NASA Astrophysics Data System (ADS)
Wang, W. Q.; Yin, Y.; Zou, D. B.; Yu, T. P.; Ge, Z. Y.; Xu, H.; Zhuo, H. B.; Shao, F. Q.
2017-03-01
A mechanism of the acceleration and focusing of quasi-monoenergetic proton beams from a thin arched carbon-hydrogen target irradiated by a relativistic-intensity laser pulse is investigated by multi-dimensional particle-in-cell (PIC) simulations. As an intense linearly polarized laser pulse impinges on the thin target, a considerable number of electrons are evacuated, leading to Coulomb explosion in the excess positive charges left behind. Accompanying with the acceleration, the protons are focused ballistically in the Coulomb field, which is mainly contributed by the carbon ions. It is demonstrated that a quasi-monoenergetic proton bunch with the energy-density as high as 1017 J/m3 is produced by using a laser pulse with the intensity of 1021 W/cm2. An analytical model is proposed to predict the proton energy and the focal position, which is fairly consistent with PIC simulations.
Role of the Permanent Dipole Moment in Coulomb Explosion
NASA Astrophysics Data System (ADS)
Zhang, Cai-Ping; Miao, Xiang-Yang
2013-10-01
By numerically solving the non-Born—Oppenheimer time-dependent Schrödinger equation in a few-cycle chirped laser field (5-fs, 800-nm), the effect of the permanent dipole moment on the Coulomb explosion is studied by the kinetic-energy-release spectra with the “virtual detector" method. The results indicate that with the effect of the permanent dipole moment, different multiphoton processes for heteronuclear and homonuclear diatomic molecular ions may take place when the wave packets transit from the ground state (1sσg) to the first excited state (2pσu), and then move along the excited potential curve, and finally charge-resonant enhanced ionization occurs at critical internuclear distance. As a result, despite the similar ionization probabilities for these two systems at higher vibrational level with larger chirp parameter β, the structure of the Coulomb explosion spectrum for the former is prominently different from that for the latter.
Elastic scattering of Beryllium isotopes near the Coulomb barrier
Di Pietro, A.; Figuera, P.; Amorini, F.; Fisichella, M.; Lattuada, M.; Musumarra, A.; Pellegriti, M. G.; Randisi, G.; Rizzo, F.; Santonocito, D.; Scalia, G.; Scuderi, V.; Strano, E.; Torresi, D.; Papa, M.; Acosta, L.; Martel, I.; Perez-Bernal, F.; Borge, M. J. G.; Tengblad, O.
2011-10-28
In this contribution, results of experiments performed with the three Beryllium isotopes {sup 9,10,11}Be on a medium mass {sup 64}Zn target, at a center of mass energy of {approx_equal}1.4 the Coulomb barrier, will be discussed. Elastic scattering angular distributions have been measured for the {sup 9,10}Be reactions. In the {sup 11}Be case the quasielastic scattering angular distribution was obtained. In the halo nucleus case, the angular distribution exhibit a non-Fresnel-type pattern with a strong damping of the Coulomb-nuclear interference peak. Moreover, it is found that the total reaction cross-section for the halo nucleus induced collision is more than double the ones extracted in the collisions induced by the non-halo Beryllium isotopes. A large contribution to the total-reaction cross-section in the {sup 11}Be case could be attributed to transfer and/or break-up events.
Coulomb artifacts and bottomonium hyperfine splitting in lattice NRQCD
NASA Astrophysics Data System (ADS)
Liu, T.; Penin, A. A.; Rayyan, A.
2017-02-01
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 "na¨ıve" 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 [1, 2]. 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 Y(1 S) - M ηb (1 S) = 52.9 ± 5.5 MeV [1].
Structural phase transitions and topological defects in ion Coulomb crystals
Partner, Heather L.; Nigmatullin, Ramil; Burgermeister, Tobias; Keller, Jonas; Pyka, Karsten; Plenio, Martin B.; Retzker, Alex; Zurek, Wojciech Hubert; del Campo, Adolfo; Mehlstaubler, Tanja E.
2014-11-19
We use laser-cooled ion Coulomb crystals in the well-controlled environment of a harmonic radiofrequency ion trap to investigate phase transitions and defect formation. Topological defects in ion Coulomb crystals (kinks) have been recently proposed for studies of nonlinear physics with solitons and as carriers of quantum information. Defects form when a symmetry breaking phase transition is crossed non-adiabatically. For a second order phase transition, the Kibble-Zurek mechanism predicts that the formation of these defects follows a power law scaling in the rate of the transition. We demonstrate a scaling of defect density and describe kink dynamics and stability. We further discuss the implementation of mass defects and electric fields as first steps toward controlled kink preparation and manipulation.
Orbital ice: An exact Coulomb phase on the diamond lattice
Chern Giawei; Wu Congjun
2011-12-15
We demonstrate the existence of an orbital Coulomb phase as the exact ground state of a p-orbital exchange Hamiltonian on the diamond lattice. The Coulomb phase is an emergent state characterized by algebraic dipolar correlations and a gauge structure resulting from local constraints (ice rules) of the underlying lattice models. For most ice models on the pyrochlore lattice, these local constraints are a direct consequence of minimizing the energy of each individual tetrahedron. On the contrary, the orbital ice rules are emergent phenomena resulting from the quantum orbital dynamics. We show that the orbital ice model exhibits an emergent geometrical frustration by mapping the degenerate quantum orbital ground states to the spin-ice states obeying the 2-in-2-out constraints on the pyrochlore lattice. We also discuss possible realization of the orbital ice model in optical lattices with p-band fermionic cold atoms.
Coulomb chronometry to probe the decay mechanism of hot nuclei
NASA Astrophysics Data System (ADS)
Gruyer, D.; Frankland, J. D.; Bonnet, E.; Chbihi, A.; Ademard, G.; Boisjoli, M.; Borderie, B.; Bougault, R.; Galichet, E.; Gauthier, J.; Guinet, D.; Lautesse, P.; Le Neindre, N.; Legouée, E.; Lombardo, I.; Lopez, O.; Manduci, L.; Marini, P.; Mazurek, K.; Nadtochy, P. N.; Pârlog, M.; Rivet, M. F.; Roy, R.; Rosato, E.; Spadaccini, G.; Verde, G.; Vient, E.; Vigilante, M.; Wieleczko, J. P.; Indra Collaboration
2015-12-01
In 129Xe+natSn central collisions from 8 to 25 MeV/nucleon, the three-fragment exit channel occurs with a significant cross section. We show that these fragments arise from two successive binary splittings of a heavy composite system. The sequence of fragment production is determined. Strong Coulomb proximity effects are observed in the three-fragment final state. A comparison with Coulomb trajectory calculations shows that the time scale between the consecutive breakups decreases with increasing bombarding energy, becoming quasisimultaneous above excitation energy E*=4.0 ±0.5 MeV /nucleon . This transition from sequential to simultaneous breakup was interpreted as the signature of the onset of multifragmentation for the three-fragment exit channel in this system.
Electronic cooling via interlayer Coulomb coupling in multilayer epitaxial graphene
Mihnev, Momchil T.; Tolsma, John R.; Divin, Charles J.; Sun, Dong; Asgari, Reza; Polini, Marco; Berger, Claire; de Heer, Walt A.; MacDonald, Allan H.; Norris, Theodore B.
2015-01-01
In van der Waals bonded or rotationally disordered multilayer stacks of two-dimensional (2D) materials, the electronic states remain tightly confined within individual 2D layers. As a result, electron–phonon interactions occur primarily within layers and interlayer electrical conductivities are low. In addition, strong covalent in-plane intralayer bonding combined with weak van der Waals interlayer bonding results in weak phonon-mediated thermal coupling between the layers. We demonstrate here, however, that Coulomb interactions between electrons in different layers of multilayer epitaxial graphene provide an important mechanism for interlayer thermal transport, even though all electronic states are strongly confined within individual 2D layers. This effect is manifested in the relaxation dynamics of hot carriers in ultrafast time-resolved terahertz spectroscopy. We develop a theory of interlayer Coulomb coupling containing no free parameters that accounts for the experimentally observed trends in hot-carrier dynamics as temperature and the number of layers is varied. PMID:26399955
Glassy Dynamics in Geometrically Frustrated Coulomb Liquids without Disorder
NASA Astrophysics Data System (ADS)
Mahmoudian, Samiyeh; Rademaker, Louk; Ralko, Arnaud; Fratini, Simone; Dobrosavljević, Vladimir
2015-07-01
We show that introducing long-range Coulomb interactions immediately lifts the massive ground state degeneracy induced by geometric frustration for electrons on quarter-filled triangular lattices in the classical limit. Important consequences include the stabilization of a stripe-ordered crystalline (global) ground state, but also the emergence of very many low-lying metastable states with amorphous "stripe-glass" spatial structures. Melting of the stripe order thus leads to a frustrated Coulomb liquid at intermediate temperatures, showing remarkably slow (viscous) dynamics, with very long relaxation times growing in Arrhenius fashion upon cooling, as typical of strong glass formers. On shorter time scales, the system falls out of equilibrium and displays the aging phenomena characteristic of supercooled liquids above the glass transition. Our results show remarkable similarity with the recent observations of charge-glass behavior in ultraclean triangular organic materials of the θ -(BEDT -TTF )2 family.
Is the ground state of Yang-Mills theory Coulombic?
Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D.; Lutz, W.
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.
Stability of Dirac Liquids with Strong Coulomb Interaction
NASA Astrophysics Data System (ADS)
Tupitsyn, Igor S.; Prokof'ev, Nikolay V.
2017-01-01
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.
Coulomb excitation of C{sub 60} molecules
Esbensen, H.; Berry, H.G.; Cheng, S.
1995-08-01
The ionization and dissociation of C{sub 60} molecules in the Coulomb field from fast, highly-charged xenon ions was measured recently at ATLAS. The Coulomb excitation was modeled as a coherent excitation of the giant plasmon resonance. Guided by photo-absorption measurements, single-plasmon excitations were identified with the production of single-charged C{sub 60}{sup +} molecular ions. The calculated cross sections do indeed reproduce the beam energy-dependence of the measured C{sub 60}{sup +} yield. The calculations show that single-plasmon excitations are responsible for about half of the total reaction cross section. The other half, i.e., multiplasmon excitations, leads to multiple ionization and dissociation of the molecule.
A Coulomb collision algorithm for weighted particle simulations
NASA Technical Reports Server (NTRS)
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.
Coulomb branch Hilbert series and three dimensional Sicilian theories
NASA Astrophysics Data System (ADS)
Cremonesi, Stefano; Hanany, Amihay; Mekareeya, Noppadol; Zaffaroni, Alberto
2014-09-01
We evaluate the Coulomb branch Hilbert series of mirrors of three dimensional Sicilian theories, which arise from compactifying the 6 d (2 , 0) theory with symmetry G on a circle times a Riemann surface with punctures. We obtain our result by gluing together the Hilbert series for building blocks T ρ ( G), where ρ is a certain partition related to the dual group of G, which we evaluated in a previous paper. The result is expressed in terms of a class of symmetric functions, the Hall-Littlewood polynomials. As expected from mirror symmetry, our results agree at genus zero with the superconformal index prediction for the Higgs branch Hilbert series of the Sicilian theories and extend it to higher genus. In the A 1 case at genus zero, we also evaluate the Coulomb branch Hilbert series of the Sicilian theory itself, showing that it only depends on the number of external legs.
Low-energy Coulomb excitation of Sr,9896 beams
NASA Astrophysics Data System (ADS)
Clément, E.; Zielińska, M.; Péru, S.; Goutte, H.; Hilaire, S.; Görgen, A.; Korten, W.; Doherty, D. T.; Bastin, B.; Bauer, C.; Blazhev, A.; Bree, N.; Bruyneel, B.; Butler, P. A.; Butterworth, J.; Cederkäll, J.; Delahaye, P.; Dijon, A.; Ekström, A.; Fitzpatrick, C.; Fransen, C.; Georgiev, G.; Gernhäuser, R.; Hess, H.; Iwanicki, J.; Jenkins, D. G.; Larsen, A. C.; Ljungvall, J.; Lutter, R.; Marley, P.; Moschner, K.; Napiorkowski, P. J.; Pakarinen, J.; Petts, A.; Reiter, P.; Renstrøm, T.; Seidlitz, M.; Siebeck, B.; Siem, S.; Sotty, C.; Srebrny, J.; Stefanescu, I.; Tveten, G. M.; Van de Walle, J.; Vermeulen, M.; Voulot, D.; Warr, N.; Wenander, F.; Wiens, A.; De Witte, H.; Wrzosek-Lipska, K.
2016-11-01
The structure of neutron-rich Sr,9896 nuclei was investigated by low-energy safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN, with the MINIBALL spectrometer. A rich set of transitional and diagonal E 2 matrix elements, including those for non-yrast structures, has been extracted from the differential Coulomb-excitation cross sections. The results support the scenario of a shape transition at N =60 , giving rise to the coexistence of a highly deformed prolate and a spherical configuration in 98Sr, and are compared to predictions from several theoretical calculations. The experimental data suggest a significant contribution of the triaxal degree of freedom in the ground state of both isotopes. In addition, experimental information on low-lying states in 98Rb has been obtained.
Quantum solution for the one-dimensional Coulomb problem
Nunez-Yepez, H. N.; Salas-Brito, A. L.; Solis, Didier A.
2011-06-15
The one-dimensional hydrogen atom has been a much studied system with a wide range of applications. Since the pioneering work of Loudon [R. Loudon, Am. J. Phys. 27, 649 (1959).], a number of different features related to the nature of the eigenfunctions have been found. However, many of the claims made throughout the years in this regard are not correct--such as the existence of only odd eigenstates or of an infinite binding-energy ground state. We explicitly show that the one-dimensional hydrogen atom does not admit a ground state of infinite binding energy and that the one-dimensional Coulomb potential is not its own supersymmetric partner. Furthermore, we argue that at the root of many such false claims lies the omission of a superselection rule that effectively separates the right side from the left side of the singularity of the Coulomb potential.
Coulomb excitations for a short linear chain of metallic shells
Zhemchuzhna, Liubov; Gumbs, Godfrey; Iurov, Andrii; Huang, Danhong; Gao, Bo
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.
Stability characterizations of fixtured rigid bodies with Coulomb friction
PANG,J.S.; TRINKLE,JEFFREY C.
2000-02-15
This paper formally introduces several stability characterizations of fixtured three-dimensional rigid bodies initially at rest and in unilateral contact with Coulomb friction. These characterizations, weak stability and strong stability, arise naturally from the dynamic model of the system, formulated as a complementarity problem. Using the tools of complementarity theory, these characterizations are studied in detail to understand their properties and to develop techniques to identify the stability classifications of general systems subjected to known external loads.
Coulomb-Gauge Gluon Propagator and the Gribov Formula
Burgio, G.; Quandt, M.; Reinhardt, H.
2009-01-23
We analyze the lattice SU(2) Yang-Mills theory in the Coulomb gauge. We show that the static gluon propagator is multiplicative renormalizable and takes the simple form D(|p-vector|){sup -1}={radical}(|p-vector|{sup 2}+M{sup 4}/|p-vector|{sup 2}), proposed by Gribov through heuristic arguments many years ago. We find M=0.88(1) GeV{approx_equal}2{radical}({sigma})
On the Nonlocality of the Coulomb Gauge External Field Problem
NASA Astrophysics Data System (ADS)
Hraskó, Péter
The apparent nonlocality of the Coulomb gauge external field problem in electrodynamics is illustrated with an example in which nonlocality is especially striking. Explanation of this apparent nonlocal behaviour based on a purely local picture is given. A gauge invariant decomposition of the Lorentz-force into two terms with clear physical meanings is pointed out. Based on this decomposition derivation of the Aharonov-Bohm effect in terms of field strengths alone is given.
On the nonlocality of the Coulomb gauge external field problem
NASA Astrophysics Data System (ADS)
Hraskó, Péter
2016-10-01
The apparent nonlocality of the Coulomb gauge external field problem in electrodynamics is illustrated with an example in which nonlocality is especially striking. Explanation of this apparent nonlocal behaviour based on a purely local picture is given. A gauge invariant decomposition of the Lorentz-force into two terms with clear physical meanings is pointed out. Based on this decomposition derivation of the Aharonov-Bohm effect in terms of field strengths alone is given.
Coulomb crystallization of sympathetically cooled highly charged ions
NASA Astrophysics Data System (ADS)
Crespo López-Urrutia, José R.
2015-05-01
Wave functions of inner-shell electrons significantly overlap with the nucleus, whereby enormously magnified relativistic, quantum electrodynamic (QED) and nuclear size effects emerge. In highly charged ions (HCI), the relative reduction of electronic correlations contributions improves the visibility of these effects. This well known facts have driven research efforts with HCI, yet the typically high temperatures at which these can be prepared in the laboratory constitutes a serious hindrance for application of laser spectroscopic methods. The solution for this, cooling HCI down to crystallization has remained an elusive target for more than two decades. By applying laser cooling to an ensemble of Be+ ions, we build Coulomb crystals that we use for stopping the motion of HCI and for cooling them. HCI, in this case Ar13+ ions are extracted from an electron beam ion trap with an energy spread of a few 100's of eV, due to the ion temperature within the trap. Carefully timed electric pulses in a potential-gradient decelerate and bunch the HCI. We achieve Coulomb crystallization of these HCI by re-trapping them in a cryogenic linear radiofrequency trap where they are sympathetically cooled through Coulomb interaction with the directly laser-cooled ensemble. Furthermore, we also demonstrate cooling of a single Ar13+ ion by a single Be+ ion, prerequisite for quantum logic spectroscopy with potentially 10-19 relative accuracy. The strongly suppressed thermal motion of the embedded HCI offers novel possibilities for investigation of questions related to the time variation of fundamental constants, parity non-conservation effects, Lorentz invariance and quantum electrodynamics. Achieving a seven orders-of-magnitude decrease in HCI temperature, from the starting point at MK values in the ion source down to the mK range within the Coulomb crystal eliminates the major obstacle for HCI investigation with high precision laser spectroscopy and quantum computation schemes.
Can Coulomb repulsion for charged particle beams be overcome?
NASA Astrophysics Data System (ADS)
Retsky, Michael W.
2004-01-01
Mutual repulsion of discrete charged particles or Coulomb repulsion is widely considered to be an ultimate hard limit in charged particle optics. It prevents the ability to finely focus high current beams into a small spots at large distances from the defining apertures. A classic example is the 1970s era "Star Wars" study of an electron beam directed energy weapon as an orbiting antiballistic missile device. After much analysis, it was considered physically impossible to focus a 1000-amp 1-GeV beam into a 1-cm diameter spot 1000-km from the beam generator. The main reason was that a 1-cm diameter beam would spread to 5-m diameter at 1000-km due to Coulomb repulsion. Since this could not be overcome, the idea was abandoned. But is this true? What if the rays were reversed? That is, start with a 5-m beam converging slightly with the same nonuniform angular and energy distribution as the electrons from the original problem were spreading at 1000-km distance. Could Coulomb repulsion be overcome? Looking at the terms in computational studies, some are reversible while others are not. Since the nonreversible terms should be small, it might be possible to construct an electron beam directed energy weapon.
Coulomb crystal mass spectrometry in a digital ion trap
NASA Astrophysics Data System (ADS)
Deb, Nabanita; Pollum, Laura L.; Smith, Alexander D.; Keller, Matthias; Rennick, Christopher J.; Heazlewood, Brianna R.; Softley, Timothy P.
2015-03-01
We present a mass spectrometric technique for identifying the masses and relative abundances of Coulomb-crystallized ions held in a linear Paul trap. A digital radio-frequency wave form is employed to generate the trapping potential, as this can be cleanly switched off, and static dipolar fields are subsequently applied to the trap electrodes for ion ejection. Close to 100% detection efficiency is demonstrated for Ca+ and CaF+ ions from bicomponent Ca+-CaF+ Coulomb crystals prepared by the reaction of Ca+ with CH3F . A quantitative linear relationship is observed between ion number and the corresponding integrated time-of-flight (TOF) peak, independent of the ionic species. The technique is applicable to a diverse range of multicomponent Coulomb crystals—demonstrated here for Ca+-NH 3+ -NH 4+ and Ca+-CaOH +-CaOD + crystals—and will facilitate the measurement of ion-molecule reaction rates and branching ratios in complicated reaction systems.
Implosive Interatomic Coulombic decay in the simplest molecular anion
NASA Astrophysics Data System (ADS)
Greene, Chris H.; Perez-Rios, Jesus; Slipchenko, Lyudmila
2016-05-01
Interatomic Coulombic decay (ICD) has been extensively studied in different systems: from diatomic systems such as He2 up to more complex chemical systems with interest in biochemistry. Independently of the size and complexity of the system, the ICD process proposed involves the emission of an electron through exchange of a virtual photon. The present theoretical study investigates the ICD process in the helium hydride anion, which involves two final product states that can be produced through a Coulomb implosion following high energy ejection of a He 1s electron accompanied by excitation to He+(n = 2) . One of the subsequent decay channels is associated with the usual emission of a single electron, to produce a stable molecule: HeH+, which can compete with the usual dissociated final state of the system. The second channel involves the emission of two electrons, leading to the usual Coulomb explosion of the final product ions He+(1 s) + H + . In addition, the process of formation of the helium hydride anion is analyzed in terms of the existing technology of ionic molecular beams and buffer gas cooling techniques. This work is supported by the National Science Foundation under Grant PHY-1306905.
Quasi-exactly solvable relativistic soft-core Coulomb models
Agboola, Davids Zhang, Yao-Zhong
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.
Electron interactions in graphene through an effective Coulomb potential
NASA Astrophysics Data System (ADS)
Rodrigues, Joao N. B.; Adam, Shaffique
A recent numerical work [H.-K. Tang et al, PRL 115, 186602 (2015)] considering graphene's π-electrons interacting through an effective Coulomb potential that is finite at short-distances, stressed the importance of the sp2 -electrons in determining the semimetal to Mott insulator phase transition in graphene. Some years ago, I. F. Herbut [PRL 97, 146401 (2006)] studied such a transition by mapping graphene's π-electrons into a Gross-Neveu model. From a different perspective, D. T. Son [PRB 75, 235423 (2007)] put the emphasis on the long-range interactions by modelling graphene as Dirac fermions interacting through a bare Coulomb potential. Here we build on these works and explore the phase diagram of Dirac fermions interacting through an effective Coulomb-like potential screened at short-distances. The interaction potential used allows for analytic results that controllably switch between the two perspectives above. This work was supported by the Singapore National Research Foundation (NRF-NRFF2012-01 and CA2DM medium-sized centre program) and by the Singapore Ministry of Education and Yale-NUS College (R-607-265-01312).
Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule.
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.
Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule
NASA Astrophysics Data System (ADS)
Cloët, Ian C.; Bentz, Wolfgang; Thomas, Anthony W.
2016-01-01
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.
Dynamical Coulomb blockade of tunnel junctions driven by alternating voltages
NASA Astrophysics Data System (ADS)
Grabert, Hermann
2015-12-01
The theory of the dynamical Coulomb blockade is extended to tunneling elements driven by a time-dependent voltage. It is shown that, for standard setups where an external voltage is applied to a tunnel junction via an impedance, time-dependent driving entails an excitation of the modes of the electromagnetic environment by the applied voltage. Previous approaches for ac driven circuits need to be extended to account for the driven bath modes. A unitary transformation involving also the variables of the electromagnetic environment is introduced which allows us to split off the time dependence from the Hamiltonian in the absence of tunneling. This greatly simplifies perturbation-theoretical calculations based on treating the tunneling Hamiltonian as a perturbation. In particular, the average current flowing in the leads of the tunnel junction is studied. Explicit results are given for the case of an applied voltage with a constant dc part and a sinusoidal ac part. The connection with standard dynamical Coulomb blockade theory for constant applied voltage is established. It is shown that an alternating voltage source reveals significant additional effects caused by the electromagnetic environment. The hallmark of the dynamical Coulomb blockade in ac driven devices is a suppression of higher harmonics of the current by the electromagnetic environment. The theory presented basically applies to all tunneling devices driven by alternating voltages.
Ionization in an intense field considering Coulomb correction
NASA Astrophysics Data System (ADS)
Li, Jian; Huo, Yi-Ning; Tang, Zeng-Hua; Ma, Feng-Cai
2017-01-01
We derive a simple ionization rate formula for the ground state of a hydrogen atom in the velocity gauge under the conditions: ω \\ll 1 a.u. (a.u. is short for atomic unit) and γ \\ll 1 (ω is the laser frequency and γ is the Keldysh parameter). Comparisons are made among the different versions of the Keldysh–Faisal–Reiss (KFR) theory. The numerical study shows that with considering the quasi-classical (WKB) Coulomb correction in the final state of the ionized electron, the photoionization rate is enhanced compared with without considering the Coulomb correction, and the Reiss theory with the WKB Coulomb correction gives the correct result in the tunneling regime. Our concise formula of the ionization rate may provide an insight into the ionization mechanism for the ground state of a hydrogen atom. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274149 and 11304185) and the Program of Shenyang Key Laboratory of Optoelectronic Materials and Technology, China (Grant No. F12-254-1-00).
Instabilities of Coulomb phases and quark confinement in QCD
Asorey, Manuel; Santagata, Alessandro
2009-01-01
The Gribov picture to quark confinement is based on the Coulomb phase instability due to the very large values that the effective α{sub s} coupling constant can reach in the infrared regime. The Gribov instability is driven by a vacuum decay into light quarks beyond a critical value of the coupling constant α{sub s}3π(1-√(2/3))/4 (for SU(3) gauge group). From first principles it has been shown the existence of an instability of the Coulomb phase in pure gauge theories for α≥√(2), much beyond the Gribov critical value. In this paper we analyze the effect of dynamical quarks in the instability of the Coulomb phase. We find a critical value of the coupling α=√(3) where a quark-antiquark pair creation mechanism leads to vacuum instability. However, the new critical value turns out to be larger than the pure gauge critical value α=√(2), unlike it is expected in the standard Gribov scenario. The result is analytically derived from first principles and provides further consistency to the picture where quark confinement is mainly driven by gluonic fluctuation instabilities.
Boron-10 Lined Proportional Counter Wall Effects
Siciliano, Edward R.; Kouzes, Richard T.
2012-05-01
The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube based system in the configuration of a coincidence counter. This report provides information about how variations in proportional counter radius and gas pressure in a typical coincident counter design might affect the observed signal from boron-lined tubes. A discussion comparing tubes to parallel plate counters is also included.
The simplest model for non-congruent fluid-fluid phase transition in Coulomb system
NASA Astrophysics Data System (ADS)
Stroev, N. E.; Iosilevskiy, I. L.
2015-11-01
The simplest model for non-congruent phase transition of gas-liquid type was developed in frames of modified model with no associations of a binary ionic mixture (BIM) on a homogeneous compressible ideal background (or non-ideal) electron gas /BIM(˜)/. The analytical approximation for equation of state equation of state of Potekhin and Chabrier of fully ionized electron-ionic plasma was used for description of the ion-ion correlations (Coulomb non-ideality) in combination with “linear mixture” (LM) approximation. Phase equilibrium for the charged species was calculated according to the Gibbs-Guggenheim conditions. The presently considered BIM(˜) model allows to calculate full set of parameters for phase boundaries of non-congruent variant of phase equilibrium and to study all features for this non-congruent phase transition realization in Coulomb system in comparison with the simpler (standard) forced-congruent evaporation mode. In particular, in BIM(˜) there were reproduced two-dimensional remarkable (“banana-like”) structure of two-phase region P — T diagram and the characteristic non-monotonic shape of caloric phase enthalpy-temperature diagram, similar to the non-congruent evaporation of reactive plasma products in high-temperature heating with the uranium-oxygen system. The parameters of critical points (CP) line were calculated on the entire range of proportions of ions 0 < X < 1, including two reference values, when CP coincides with a point of extreme temperature and extreme pressure, XT and Xp. Finally, it is clearly demonstrated the low-temperature property of non-congruent gas-liquid transition — “distillation”, which is weak in chemically reactive plasmas.
Quasidistribution amplitude of heavy quarkonia
NASA Astrophysics Data System (ADS)
Jia, Yu; Xiong, Xiaonu
2016-11-01
The recently proposed quasidistributions point out a promising direction for lattice QCD to investigate the light-cone correlators, such as parton distribution functions and distribution amplitudes (DAs), directly in the x space. Owing to its excessive simplicity, heavy quarkonium can serve as an ideal theoretical laboratory to ascertain certain features of quasi-DAs. In the framework of nonrelativistic QCD factorization, we compute the order-αs correction to both light-cone distribution amplitudes (LCDAs) and quasi-DAs associated with the lowest-lying quarkonia, with the transverse-momentum UV cutoff interpreted as the renormalization scale. We confirm analytically that the quasi-DA of a quarkonium does reduce to the respective LCDA in the infinite-momentum limit. We also observe that, provided that the momentum of a charmonium reaches about 2-3 times its mass, the quasi-DAs already converge to the LCDAs to a decent level. These results might provide some useful guidance for the future lattice study of quasidistributions.
Canine Conjectures: Using Data for Proportional Reasoning
ERIC Educational Resources Information Center
Westenskow, Arla; Moyer-Packenham, Patricia S.
2011-01-01
No person, place, or thing can capture the attention of a class of sixth graders like "man's best friend." To prompt students' interest in a series of lessons on proportional relationships, the authors brought in a unique teaching aid--a dog. A family dog was used to supply the measurements for scatter plots and variables so that students could…
Tukey-Like Pairwise Comparisons among Proportions.
ERIC Educational Resources Information Center
Williams, Richard H.
1992-01-01
A QuickBASIC microcomputer program for conducting Tukey-like pairwise comparisons on "k" independent sample proportions is described. The program can accommodate applications involving equal or unequal sample sizes. Studentized range values are computed and displayed on a computer monitor, each of which represents a simple comparison…
Kitchen Gardens: Contexts for Developing Proportional Reasoning
ERIC Educational Resources Information Center
Hilton, Annette; Hilton, Geoff; Dole, Shelley; Goos, Merrilyn; O'Brien, Mia
2013-01-01
It is great to see how the sharing of ideas sparks new ideas. In 2011 Lyon and Bragg wrote an "Australian Primary Mathematics Classroom" (APMC) article on the mathematics of kitchen gardens. In this article the authors show how the kitchen garden may be used as a starting point for proportional reasoning. The authors highlight different…
Using Artwork to Explore Proportional Reasoning
ERIC Educational Resources Information Center
Bush, Sarah B.; Karp, Karen S.; Nadler, Jennifer; Gibbons, Katie
2016-01-01
Having an answer to "When are we ever going to use this in real life?" is important to middle school mathematics teachers. The activity described in this article awakened sixth graders' understanding of how artists use mathematics. By exploring ratio and proportionality in different paintings, students realized the use of proportional…
Research on fluidics, valves, and proportional amplifiers
NASA Technical Reports Server (NTRS)
1974-01-01
Research and development being conducted at the Systems and Controls Laboratory is reviewed. Static characteristics (supply, input, transfer, output, and noise characteristics) of laminar proportional amplifiers were investigated. Other topics discussed include velocity profiles for laminar fluidic jets, speed control systems employing a jet pipe valve, and power amplification with a vortex valve.
Golden Proportions for the Generalized Tribonacci Numbers
ERIC Educational Resources Information Center
Shah, Devbhadra V.; Mehta, Darshana A.
2009-01-01
It is known that the ratios of consecutive terms of Fibonacci and Tribonacci sequences converge to the fixed ratio. In this article, we consider the generalized form of Tribonacci numbers and derive the "golden proportion" for the whole family of this generalized sequence. (Contains 2 tables.)
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.
Large amplitude relativistic plasma waves
Coffey, Timothy
2010-05-15
Relativistic, longitudinal plasma oscillations are studied for the case of a simple water bag distribution of electrons having cylindrical symmetry in momentum space with the axis of the cylinder parallel to the velocity of wave propagation. The plasma is required to obey the relativistic Vlasov-Poisson equations, and solutions are sought in the wave frame. An exact solution for the plasma density as a function of the electrostatic field is derived. The maximum electric field is presented in terms of an integral over the known density. It is shown that when the perpendicular momentum is neglected, the maximum electric field approaches infinity as the wave phase velocity approaches the speed of light. It is also shown that for any nonzero perpendicular momentum, the maximum electric field will remain finite as the wave phase velocity approaches the speed of light. The relationship to previously published solutions is discussed as is some recent controversy regarding the proper modeling of large amplitude relativistic plasma waves.
Constructing Amplitudes from Their Soft Limits
Boucher-Veronneau, Camille; Larkoski, Andrew J.; /SLAC
2011-12-09
The existence of universal soft limits for gauge-theory and gravity amplitudes has been known for a long time. The properties of the soft limits have been exploited in numerous ways; in particular for relating an n-point amplitude to an (n-1)-point amplitude by removing a soft particle. Recently, a procedure called inverse soft was developed by which 'soft' particles can be systematically added to an amplitude to construct a higher-point amplitude for generic kinematics. We review this procedure and relate it to Britto-Cachazo-Feng-Witten recursion. We show that all tree-level amplitudes in gauge theory and gravity up through seven points can be constructed in this way, as well as certain classes of NMHV gauge-theory amplitudes with any number of external legs. This provides us with a systematic procedure for constructing amplitudes solely from their soft limits.
ERIC Educational Resources Information Center
Lobato, Joanne; Ellis, Amy; Zbiek, Rose Mary
2010-01-01
How do you refute the erroneous claim that all ratios are fractions? This book goes beyond a simple introduction to ratios, proportions, and proportional reasoning. It will help broaden and deepen your mathematical understanding of one of the most challenging topics for students--and teachers--to grasp. It will help you engage your students,…
Proportional reasoning competence among different student populations
NASA Astrophysics Data System (ADS)
Wong, King
2012-10-01
A collaborative project between Western Washington University, Rutgers University, and New Mexico State University seeks to understand student's competence level on proportional reasoning. We have been collecting and analyzing data from introductory physics and science education courses using a set of assessment tasks. We utilize the notion of constructs to categorize student thinking according to repetitive patterns. Results suggest that, when students confront ratio and proportion problems, they often experience a gap between the mechanics of the mathematical operations and the conscious understanding of what they are doing. In this poster we will share results of our findings from different courses, institutions, and student populations. Supported by NSF grants DUE-1045227, DUE-1045231, DUE-1045250..
Gamma heating measurements with proportional counters
Chiu, H.; Bennett, E.F.; Micklich, B.J.
1990-05-01
A new data acquisition technique (the Continuously-varied Bias- voltage Acquisition mode) has been developed and tested for the low-flux broad-energy regime characteristic of existing fusion blanket mock-ups. This method of analysis allows for the acquisition of data spanning several orders of magnitude in energy with a single proportional counter. Utilizing this method, the gamma energy deposition in a mixed neutron and gamma field was measured. 7 refs., 5 figs.
Evaluation of Facial Beauty Using Anthropometric Proportions
Milutinovic, Jovana
2014-01-01
The improvement of a patient's facial appearance is one of the main goals of contemporary orthodontic treatment. The aim of this investigation was to evaluate the difference in facial proportions between attractive and anonymous females in order to establish objective facial features which are widely considered as beautiful. The study included two groups: first group consisted of 83 Caucasian female subjects between 22 and 28 years of age who were selected from the population of students at the University of Belgrade, and the second group included 24 attractive celebrity Caucasian females. The en face facial photographs were taken in natural head position (NHP). Numerous parameters were recorded on these photographs, in order to establish facial symmetry and correlation with the ideal set of proportions. This study showed significant difference between anonymous and attractive females. Attractive females showed smaller face in general and uniformity of the facial thirds and fifths, and most of the facial parameters meet the criteria of the ideal proportions. PMID:24701166
NASA CONNECT: Proportionality: Modeling the Future
NASA Technical Reports Server (NTRS)
2000-01-01
'Proportionality: Modeling the Future' is the sixth of seven programs in the 1999-2000 NASA CONNECT series. Produced by NASA Langley Research Center's Office of Education, NASA CONNECT is an award-winning series of instructional programs designed to enhance the teaching of math, science and technology concepts in grades 5-8. NASA CONNECT establishes the 'connection' between the mathematics, science, and technology concepts taught in the classroom and NASA research. Each program in the series supports the national mathematics, science, and technology standards; includes a resource-rich teacher guide; and uses a classroom experiment and web-based activity to complement and enhance the math, science, and technology concepts presented in the program. NASA CONNECT is FREE and the programs in the series are in the public domain. Visit our web site and register. http://connect.larc.nasa.gov 'Proportionality: Modeling the Future', students will examine how patterns, measurement, ratios, and proportions are used in the research, development, and production of airplanes.
The Effect of Speed of Processing Training on Microsaccade Amplitude
Layfield, Stephen; Burge, Wesley; Mitchell, William; Ross, Lesley; Denning, Christine; Amthor, Frank; Visscher, Kristina
2014-01-01
Older adults experience cognitive deficits that can lead to driving errors and a loss of mobility. Fortunately, some of these deficits can be ameliorated with targeted interventions which improve the speed and accuracy of simultaneous attention to a central and a peripheral stimulus called Speed of Processing training. To date, the mechanisms behind this effective training are unknown. We hypothesized that one potential mechanism underlying this training is a change in distribution of eye movements of different amplitudes. Microsaccades are small amplitude eye movements made when fixating on a stimulus, and are thought to counteract the “visual fading” that occurs when static stimuli are presented. Due to retinal anatomy, larger microsaccadic eye movements are needed to move a peripheral stimulus between receptive fields and counteract visual fading. Alternatively, larger microsaccades may decrease performance due to neural suppression. Because larger microsaccades could aid or hinder peripheral vision, we examine the distribution of microsaccades during stimulus presentation. Our results indicate that there is no statistically significant change in the proportion of large amplitude microsaccades during a Useful Field of View-like task after training in a small sample of older adults. Speed of Processing training does not appear to result in changes in microsaccade amplitude, suggesting that the mechanism underlying Speed of Processing training is unlikely to rely on microsaccades. PMID:25248099
NASA Astrophysics Data System (ADS)
Salas, L. D.; Arce, J. C.
2017-02-01
For the S states of two-electron atoms, we introduce an exact and unique factorization of the internal eigenfunction in terms of a marginal amplitude, which depends functionally on the electron-nucleus distances r1 and r2, and a conditional amplitude, which depends functionally on the interelectronic distance r12 and parametrically on r1 and r2. Applying the variational principle, we derive pseudoeigenvalue equations for these two amplitudes, which cast the internal Schrödinger equation in a form akin to the Born-Oppenheimer separation of nuclear and electronic degrees of freedom in molecules. The marginal equation involves an effective radial Hamiltonian, which contains a nonadiabatic potential energy surface that takes into account all interparticle correlations in an averaged way, and whose unique eigenvalue is the internal energy. At each point (r1,r2) , such surface is, in turn, the unique eigenvalue in the conditional equation. Employing the ground state of He as prototype, we show that the nonadiabatic potential energy surface affords a molecularlike interpretation of the structure of the atom, and aids in the analysis of energetic and spatial aspects of the Coulomb correlation, in particular correlation-induced symmetry breaking and quantum phase transition.
Coulomb Drag and Magnetotransport in Graphene Double Layers
NASA Astrophysics Data System (ADS)
Tutuc, Emanuel
2013-03-01
Graphene double layers, a set of two closely spaced graphene monolayers seperated by an ultra-thin dielectric, represent an interesting electron system to explore correlated electron states. We discuss the fabrication of such samples using a layer-by-layer transfer approach, the electron transport in individual layers at zero and in a high magnetic field, and Coulomb drag measurements. Coulomb drag, probed by flowing a drive current in one layer, and measuring the voltage drop in the opposite layer provides a direct measurement of the electron-electron scattering between the two layers, and can be used to probe the electron system ground state. Coulomb drag in graphene, measured as a function of both layer densities and temperature reveals two distinct regimes: (i) diffusive drag at elevated temperatures, above 50 K, and (ii) mesoscopic fluctuations-dominated drag at low temperatures. A second topic discussed here is a technique that allows a direct measurement of the Fermi energy in an electron system with an accuracy independent of the sample size, using a graphene double layer heterostructure. The underlying principle of the technique is that an interlayer bias applied to bring the top layer to the charge neutrality point is equal to the Fermi energy of the bottom layer, which in effect renders the top graphene layer a resistively detected Kelvin probe. We illustrate this method by measuring the Fermi velocity, Landau level spacing, and Landau level broadening in monolayer graphene. Work done in collaboration with S. Kim, I. Jo, J. Nah, D. Dillen, K. Lee, B. Fallahazad, Z. Yao, and S. K. Banerjee. We thank ONR, NRI, and NSF for support.
CESR feedback system using a constant amplitude pulser
Codner, G.; Billing, M.; Meller, R.; Patten, R.; Rogers, J.; Sikora, J.; Sloand, M.; Strohman, C.
1998-12-10
Particle beam feedback system using constant-amplitude, 1000 V, 12 ns pulses has been built to provide longitudinal and horizontal feedback for stabilizing 14 ns spaced bunches for use in CESR (Cornell Electron Storage Ring). The pulse rate is modulated to obtain proportional amplitude control and the pulse arrival time is modulated to obtain both positive and negative kicks. The average repetition rate is limited by pulser power dissipation, but the instantaneous rate may be increased to full duty cycle for short periods of time to handle transients. The pulser drives a 50-ohm stripline kicker so the equivalent peak power at 1000 V is 10 kW. The characteristics of the pulser and its modulator will be described along with the system's operation.
Becedas, Jonathan; Trapero, Juan Ramón; Feliu, Vicente; Sira-Ramirez, Hebertt
2009-06-01
In this paper, we propose a fast online closed-loop identification method combined with an output-feedback controller of the generalized proportional integral (GPI) type for the control of an uncertain flexible robotic arm with unknown mass at the tip, including a Coulomb friction term in the motor dynamics. A fast nonasymptotic algebraic identification method developed in continuous time is used to identify the unknown system parameter and update the designed certainty equivalence GPI controller. In order to verify this method, several informative simulations and experiments are shown.
High power laser coupling to carbon nano-tubes and ion Coulomb explosion
K, Magesh Kumar K; Tripathi, V. K.
2013-09-15
Linear and non linear interaction of laser with an array of carbon nanotubes is investigated. The ac conductivity of nanotubes, due to uneven response of free electrons in them to axial and transverse fields, is a tensor. The propagation constant for p-polarization shows resonance at a specific frequency that varies with the direction of laser propagation. It also shows surface plasmon resonance at ω=ω{sub p}/√(2), where ω{sub p} is the plasma frequency of free electrons inside a nanotube, assumed to be uniform plasma cylinder. The attenuation constant is also resonantly enhanced around these frequencies. At large laser amplitude, the nanotubes behave as thin plasma rods. As the electrons get heated, the nanotubes undergo hydrodynamic expansion. At an instant when plasma frequency reaches ω{sub p}=√(2)ω, the electron temperature rises rapidly and then saturates. For a Gaussian laser beam, the heating rate is maximum on the laser axis and falls off with the distance r from the axis. When the excursion of the electrons Δ is comparable or larger than the radius of the nanotube r{sub c}, the nanotubes undergo ion Coulomb explosion. The distribution function of ions turns out to be a monotonically decreasing function of energy.
Theory and simulation of ion Coulomb crystal formation in a Penning trap
NASA Astrophysics Data System (ADS)
Asprusten, Martin; Worthington, Simon; Thompson, Richard C.
2014-01-01
Ion Coulomb crystals (ICCs) are formed by laser-cooled ions in both radio-frequency and Penning traps. In radio-frequency traps, the crystals are generally stationary. In Penning traps, ICCs always rotate. The frequency of rotation is often set by an applied rotating wall drive that forces the crystal to rotate at the same frequency as the drive. In the absence of any applied rotating or oscillating fields, ICCs in a Penning trap can be in stable equilibrium with a range of rotation frequencies. The density and shape of the crystal adjust with the rotation frequency to ensure that equilibrium is reached. Here, we show that the parameters of the radial laser-cooling beam determine the rotation frequency of a small crystal in a Penning trap when no driving fields are present. We demonstrate, using an approximate theoretical treatment and realistic simulations, that the crystal rotation frequency is independent of the number of ions and the trap parameters, so long as the crystal radius remains smaller than the cooling laser beam waist. As the rotation frequency increases, the crystal eventually becomes a linear string, at which point it is no longer able to adjust its density. Instead, a small amplitude vibration in the zigzag mode of oscillation manifests itself as a rotation of the crystal at a fixed frequency that depends only on the applied trap potential.
Coulomb breakup of 22C in a four-body model
NASA Astrophysics Data System (ADS)
Pinilla, E. C.; Descouvemont, P.
2016-08-01
Breakup cross sections are determined for the Borromean nucleus 22C by using a four-body eikonal model, including Coulomb corrections. Bound and continuum states are constructed within a 20C+n +n three-body model in hyperspherical coordinates. We compute continuum states with the correct asymptotic behavior through the R -matrix method. For the n +n potential, we use the Minnesota interaction. As there is no precise experimental information on 21C, we define different parameter sets for the 20C+n potentials. These parameter sets provide different scattering lengths, and resonance energies of an expected 3 /2+ excited state. Then we analyze the 22C ground-state energy and rms radius, as well as E 1 strength distributions and breakup cross sections. The E 1 strength distribution presents an enhancement at low energies. Its amplitude is associated with the low binding energy, rather than with a three-body resonance. We show that the shape of the cross section at low energies is sensitive to the ground-state properties. In addition, we suggest the existence of a low-energy 2+ resonance, which should be observable in breakup experiments.
Coulomb excitation of levels in 143Nd and 145Nd
NASA Astrophysics Data System (ADS)
Drǎgulescu, E.; Ivaşcu, M.; Mihu, R.; Popescu, D.; Semenescu, G.; Paar, V.; Vretenar, D.
1984-04-01
The low-lying states of 143Nd and 154Nd have been studied by means of Coulomb excitation with 16O and α-particles. Angular distribution measurements were carried out for some transitions in 145Nd with 11.2 MeV α-particles. Level energy decay schemes and B(E2)↑ values were measured for two states in 143Nd and for six states in 145Nd. Some spin assignments have been established for the 145Nd nucleus. 143Nd and 145Nd have been theoretically described by coupling one and three particles, respectively, to quadrupole vibrations, and rather good agreement with experiment was achieved.
Heavy quarks, gluons and the confinement potential in Coulomb gauge
Popovici, Carina; Watson, Peter; Reinhardt, Hugo
2011-05-23
We consider the heavy quark limit of Coulomb gauge QCD, with the truncation of the Yang-Mills sector to include only (dressed) two-point functions. We find that the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is nonperturbatively exact and moreover, we provide a direct connection between the temporal gluon propagator and the quark confinement potential. Further, we show that only bound states of color singlet quark-antiquark (meson) and quark-quark (SU(2) baryon) pairs are physically allowed.
Photodetachment of hydrogen negative ions with screened Coulomb interaction
Zhang, Song Bin; Chen, Xiang Jun; Wang, Jian Guo; Janev, R. K.; Qu, Yi Zhi
2010-06-15
The effects of Coulomb interaction screening on photodetachment cross sections of hydrogen negative ions below the n =2 excitation threshold is investigated by using the R-matrix method with pseudostates. The contributions of Feshbach and shape resonances to H{sup -} photodetachment cross section are presented when screening length (D) varies from D = {infinity} to D = 4.6 a.u. It is found that the interaction screening has dramatic effects on the photodetachment cross sections of hydrogen negative ions in the photoelectron energy region around the n = 2 excitation threshold by strongly affecting the evolution of near-threshold resonances.
A nonlinear Bloch model for Coulomb interaction in quantum dots
Bidegaray-Fesquet, Brigitte Keita, Kole
2014-02-15
In this paper, we first derive a Coulomb Hamiltonian for electron–electron interaction in quantum dots in the Heisenberg picture. Then we use this Hamiltonian to enhance a Bloch model, which happens to be nonlinear in the density matrix. The coupling with Maxwell equations in case of interaction with an electromagnetic field is also considered from the Cauchy problem point of view. The study is completed by numerical results and a discussion about the advisability of neglecting intra-band coherences, as is done in part of the literature.
Coulombic wall slip of concentrated soft-particle suspensions
NASA Astrophysics Data System (ADS)
Adams, Michael; Liu, Wei; Zhang, Zhibing; Fryer, Peter
2013-06-01
The coefficients of friction of concentrated soft-particle suspensions (tomato paste and a microgel suspension) were measured as a function of the slip velocity for a number of substrates. The data are interpreted using a micro-elastohydrodynamic model that is consistent with significant bulk frictional dissipation and an increase in the number of particle-wall contacts with increasing normal stress. The origin of the Coulombic slip, which has not been observed previously for pastes, is ascribed to the sensitivity of the lubricating film thickness.
Proton radiography, nuclear cross sections and multiple Coulomb scattering
Sjue, Sky K.
2015-11-04
The principles behind proton radiography including multiple Coulomb scattering are discussed for a purely imaginary square well nucleus in the eikonal approximation. It is found that a very crude model can reproduce the angular dependence of the cross sections measured at 24 GeV/c. The largest differences are ~3% for the 4.56 mrad data, and ~4% for the 6.68 mrad data. The prospect of understanding how to model deterministically high-energy proton radiography over a very large range of energies is promising, but it should be tested more thoroughly.
Momentum correlation in the three-body Coulomb continuum problem
NASA Astrophysics Data System (ADS)
Zhang, Suimeng
2000-09-01
Following the work of Berakdar (1996 Phys. Rev. A 53 2316), momentum correlation in the three-body Coulomb continuum problem is considered by the introduction of effective Sommerfeld parameters for both the symmetric and the asymmetric geometry. The triple differential cross sections for electron impact ionization of atomic helium at incident energies of 50 eV in the asymmetric geometry are calculated. Results of this approach are compared with the absolute measurements, the results of the BBK model without modification, the convergent close-coupling calculations and the results of our earlier model.
Nonlocal and nonlinear electrostatics of a dipolar Coulomb fluid.
Sahin, Buyukdagli; Ralf, Blossey
2014-07-16
We study a model Coulomb fluid consisting of dipolar solvent molecules of finite extent which generalizes the point-like dipolar Poisson-Boltzmann model (DPB) previously introduced by Coalson and Duncan (1996 J. Phys. Chem. 100 2612) and Abrashkin et al (2007 Phys. Rev. Lett. 99 077801). We formulate a nonlocal Poisson-Boltzmann equation (NLPB) and study both linear and nonlinear dielectric response in this model for the case of a single plane geometry. Our results shed light on the relevance of nonlocal versus nonlinear effects in continuum models of material electrostatics.
Triaxiality near the 110Ru ground state from Coulomb excitation
NASA Astrophysics Data System (ADS)
Doherty, D. T.; Allmond, J. M.; Janssens, R. V. F.; Korten, W.; Zhu, S.; Zielińska, M.; Radford, D. C.; Ayangeakaa, A. D.; Bucher, B.; Batchelder, J. C.; Beausang, C. W.; Campbell, C.; Carpenter, M. P.; Cline, D.; Crawford, H. L.; David, H. M.; Delaroche, J. P.; Dickerson, C.; Fallon, P.; Galindo-Uribarri, A.; Kondev, F. G.; Harker, J. L.; Hayes, A. B.; Hendricks, M.; Humby, P.; Girod, M.; Gross, C. J.; Klintefjord, M.; Kolos, K.; Lane, G. J.; Lauritsen, T.; Libert, J.; Macchiavelli, A. O.; Napiorkowski, P. J.; Padilla-Rodal, E.; Pardo, R. C.; Reviol, W.; Sarantites, D. G.; Savard, G.; Seweryniak, D.; Srebrny, J.; Varner, R.; Vondrasek, R.; Wiens, A.; Wilson, E.; Wood, J. L.; Wu, C. Y.
2017-03-01
A multi-step Coulomb excitation measurement with the GRETINA and CHICO2 detector arrays was carried out with a 430-MeV beam of the neutron-rich 110Ru (t1/2 = 12 s) isotope produced at the CARIBU facility. This represents the first successful measurement following the post-acceleration of an unstable isotope of a refractory element. The reduced transition probabilities obtained for levels near the ground state provide strong evidence for a triaxial shape; a conclusion confirmed by comparisons with the results of beyond-mean-field and triaxial rotor model calculations.
The distinguishable cluster approach from a screened Coulomb formalism.
Kats, Daniel
2016-01-28
The distinguishable cluster doubles equations have been derived starting from an effective screened Coulomb formalism and a particle-hole symmetric formulation of the Fock matrix. A perturbative triples correction to the distinguishable cluster with singles and doubles (DCSD) has been introduced employing the screened integrals. It is shown that the resulting DCSD(T) method is more accurate than DCSD for reaction energies and is less sensitive to the static correlation than coupled cluster with singles and doubles with a perturbative triples correction.
Mean Field Evolution of Fermions with Coulomb Interaction
NASA Astrophysics Data System (ADS)
Porta, Marcello; Rademacher, Simone; Saffirio, Chiara; Schlein, Benjamin
2017-03-01
We study the many body Schrödinger evolution of weakly coupled fermions interacting through a Coulomb potential. We are interested in a joint mean field and semiclassical scaling, that emerges naturally for initially confined particles. For initial data describing approximate Slater determinants, we prove convergence of the many-body evolution towards Hartree-Fock dynamics. Our result holds under a condition on the solution of the Hartree-Fock equation, that we can only show in a very special situation (translation invariant data, whose Hartree-Fock evolution is trivial), but that we expect to hold more generally.
Quantum confinement and Coulomb blockade in isolated nanodiamond crystallites
NASA Astrophysics Data System (ADS)
Bolker, Asaf; Saguy, Cecile; Tordjman, Moshe; Kalish, Rafi
2013-07-01
We present direct experimental evidence of quantum confinement effects in single isolated nanodiamonds by scanning tunneling spectroscopy. For grains smaller than 4.5 nm, the band gap was found to increase with decreasing nanodiamond size and a well-defined, evenly spaced, 12-peak structure was observed on the conduction band side of the conductance curves. We attribute these peaks to the Coulomb blockade effect, reflecting the 12-fold degeneracy of the first electron-energy level in the confined nanodiamond. The present results shed light on the size dependence of the electronic properties of single nanodiamonds and are of major importance for future nanodiamond-based applications.
Analytical approach to quasiperiodic beam Coulomb field modeling
NASA Astrophysics Data System (ADS)
Rubtsova, I. D.
2016-09-01
The paper is devoted to modeling of space charge field of quasiperiodic axial- symmetric beam. Particle beam is simulated by charged disks. Two analytical Coulomb field expressions are presented, namely, Fourier-Bessel series and trigonometric polynomial. Both expressions permit the integral representation. It provides the possibility of integro-differential beam dynamics description. Consequently, when beam dynamics optimization problem is considered, it is possible to derive the analytical formula for quality functional gradient and to apply directed optimization methods. In addition, the paper presents the method of testing of space charge simulation code.
Ice limit of Coulomb gauge Yang-Mills theory
Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D.
2008-10-01
In this paper we describe gauge invariant multiquark states generalizing the path integral framework developed by Parrinello, Jona-Lasinio, and Zwanziger to amend the Faddeev-Popov approach. This allows us to produce states such that, in a limit which we call the ice limit, fermions are dressed with glue exclusively from the fundamental modular region associated with Coulomb gauge. The limit can be taken analytically without difficulties, avoiding the Gribov problem. This is illustrated by an unambiguous construction of gauge invariant mesonic states for which we simulate the static quark-antiquark potential.
"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications
NASA Technical Reports Server (NTRS)
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
A solvable model for localized adsorption in a Coulomb system
Rosinberg, M.L.; Blum, L.; Lebowitz, J.L.
1986-07-01
A model for an interface with localized adsorption is presented, in which the surface has a distribution of sticky adhesive sites in contact with a Coulomb fluid. Contrary to the current literature on the electrical double layer the surface charge is in dynamic equilibrium with the bulk fluid. The sum rules obeyed by the one- and two-body correlation functions are investigated. Explicit results are obtained for a solvable model, the two-dimensional one-component plasma at reduced temperature 2. The effect of the granularity of the adsorbed charge on the adsorption isotherm is discussed.
Dynamic screening of the three-body coulomb interactions
NASA Astrophysics Data System (ADS)
Zhang-jin, Chen
1998-03-01
The BBK approach is modified by the introduction of effective Sommerfeld parameters for both symmetric and asymmetric geometries, according to the fact that the strength of any particular two-body Coulomb interaction is affected by the presence of the third particle. The triple differential cross sections for electron impact ionization of atomic helium at incident energies of 40 and 50 eV in asymmetric geometry are calculated. Results of this approach are found to be in good agreement with the absolute measurements and the only existing theoretical results of the convergent close-coupling method.
NASA Astrophysics Data System (ADS)
Brogi, Bharat Bhushan; Chand, Shyam; Ahluwalia, P. K.
2015-06-01
Theoretical study of the Coulomb blockade effect on transport properties (Transmission Probability and I-V characteristics) for varied configuration of coupled quantum dot system has been studied by using Non Equilibrium Green Function(NEGF) formalism and Equation of Motion(EOM) method in the presence of magnetic flux. The self consistent approach and intra-dot Coulomb interaction is being taken into account. As the key parameters of the coupled quantum dot system such as dot-lead coupling, inter-dot tunneling and magnetic flux threading through the system can be tuned, the effect of asymmetry parameter and magnetic flux on this tuning is being explored in Coulomb blockade regime. The presence of the Coulomb blockade due to on-dot Coulomb interaction decreases the width of transmission peak at energy level ɛ + U and by adjusting the magnetic flux the swapping effect in the Fano peaks in asymmetric and symmetric parallel configuration sustains despite strong Coulomb blockade effect.
Proportional wire calorimeter for magnet pole tips
Kraus, D; Ludlam, T; Renardy, J; Willis, W; Zurfluh, E
1980-01-01
A total absorption calorimeter is designed to have magnetic properties comparable to those of ordinary steel, and thus can be incorporated into the poles of a spectrometer magnet without compromising the field quality. A test device has been built which consists of an iron structure penetrated by a finegrain pattern of holes, each acting as a proportional tube such that 90% of the volume is occupied by iron. Measurements of the energy and space resolution of this device in a high energy beam will be presented.
Neutron spectrometry with He-3 proportional counters
Manolopoulou, M.; Fragopoulou, M.; Stoulos, S.; Vagena, E.; Westmeier, W.; Zamani, M.
2011-07-01
Helium filled proportional counters are widely used in the field of neutron detection and spectrometry. In this work the response of a commercially available He-3 counter is studied experimentally and calculated with Monte Carlo for the neutron energy range from 230 keV up to about 7 MeV. The calculated response of the system is used to determine neutron yield energy distribution emitted from an extended {sup nat}U/Pb assembly irradiated with 1.6 GeV deuterons. The results are in acceptable agreement with the calculated neutron distribution with DCM-DEM code. (authors)
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
NASA Astrophysics Data System (ADS)
Przybytek, Michal; Helgaker, Trygve
2013-08-01
We analyze the accuracy of the Coulomb energy calculated using the Gaussian-and-finite-element-Coulomb (GFC) method. In this approach, the electrostatic potential associated with the molecular electronic density is obtained by solving the Poisson equation and then used to calculate matrix elements of the Coulomb operator. The molecular electrostatic potential is expanded in a mixed Gaussian-finite-element (GF) basis set consisting of Gaussian functions of s symmetry centered on the nuclei (with exponents obtained from a full optimization of the atomic potentials generated by the atomic densities from symmetry-averaged restricted open-shell Hartree-Fock theory) and shape functions defined on uniform finite elements. The quality of the GF basis is controlled by means of a small set of parameters; for a given width of the finite elements d, the highest accuracy is achieved at smallest computational cost when tricubic (n = 3) elements are used in combination with two (γH = 2) and eight (γ1st = 8) Gaussians on hydrogen and first-row atoms, respectively, with exponents greater than a given threshold (α _min^G=0.5). The error in the calculated Coulomb energy divided by the number of atoms in the system depends on the system type but is independent of the system size or the orbital basis set, vanishing approximately like d4 with decreasing d. If the boundary conditions for the Poisson equation are calculated in an approximate way, the GFC method may lose its variational character when the finite elements are too small; with larger elements, it is less sensitive to inaccuracies in the boundary values. As it is possible to obtain accurate boundary conditions in linear time, the overall scaling of the GFC method for large systems is governed by another computational step—namely, the generation of the three-center overlap integrals with three Gaussian orbitals. The most unfavorable (nearly quadratic) scaling is observed for compact, truly three-dimensional systems
Coulomb-corrected molecular orbital tomography of nitrogen
NASA Astrophysics Data System (ADS)
Zhai, Chunyang; He, Lixin; Lan, Pengfei; Zhu, Xiaosong; Li, Yang; Wang, Feng; Shi, Wenjing; Zhang, Qingbin; Lu, Peixiang
2016-03-01
High-order harmonic generation (HHG) from aligned molecules has provided a promising way to probe the molecular orbital with an Ångström resolution. This method, usually called molecular orbital tomography (MOT) replies on a simple assumption of the plane-wave approximation (PW), which has long been questioned due to that PW approximation is known to be valid in the keV energy region. However, the photon energy is usually no more than 100 eV in HHG. In this work, we experimentally reconstruct the highest occupied molecular orbital (HOMO) of nitrogen (N2) by using a Coulomb-corrected MOT (CCMOT) method. In our scheme, the molecular continuum states are described by a Coulomb wave function instead of the PW approximation. With CCMOT, the reconstructed orbital is demonstrated to agree well with the theoretical prediction and retain the main features of the HOMO of N2. Compared to the PW approximation method, the CCMOT shows a significant improvement in eliminating the artificial structures caused by PW approximation.
Exact linearized Coulomb collision operator in the moment expansion
Ji, Jeong-Young; Held, Eric D.
2006-10-15
In the moment expansion, the Rosenbluth potentials, the linearized Coulomb collision operators, and the moments of the collision operators are analytically calculated for any moment. The explicit calculation of Rosenbluth potentials converts the integro-differential form of the Coulomb collision operator into a differential operator, which enables one to express the collision operator in a simple closed form for any arbitrary mass and temperature ratios. In addition, it is shown that gyrophase averaging the collision operator acting on arbitrary distribution functions is the same as the collision operator acting on the corresponding gyrophase averaged distribution functions. The moments of the collision operator are linear combinations of the fluid moments with collision coefficients parametrized by mass and temperature ratios. Useful forms involving the small mass-ratio approximation are easily found since the collision operators and their moments are expressed in terms of the mass ratio. As an application, the general moment equations are explicitly written and the higher order heat flux equation is derived.
Coulomb interaction effects on the Majorana states in quantum wires.
Manolescu, A; Marinescu, D C; Stanescu, T D
2014-04-30
The stability of the Majorana modes in the presence of a repulsive interaction is studied in the standard semiconductor wire-metallic superconductor configuration. The effects of short-range Coulomb interaction, which is incorporated using a purely repulsive δ-function to model the strong screening effect due to the presence of the superconductor, are determined within a Hartree-Fock approximation of the effective Bogoliubov-De Gennes Hamiltonian that describes the low-energy physics of the wire. Through a numerical diagonalization procedure we obtain interaction corrections to the single particle eigenstates and calculate the extended topological phase diagram in terms of the chemical potential and the Zeeman energy. We find that, for a fixed Zeeman energy, the interaction shifts the phase boundaries to a higher chemical potential, whereas for a fixed chemical potential this shift can occur either at lower or higher Zeeman energies. These effects can be interpreted as a renormalization of the g-factor due to the interaction. The minimum Zeeman energy needed to realize Majorana fermions decreases with the increasing strength of the Coulomb repulsion. Furthermore, we find that in wires with multi-band occupancy this effect can be enhanced by increasing the chemical potential, i.e. by occupying higher energy bands.
Super-Coulombic atom-atom interactions in hyperbolic media.
Cortes, Cristian L; Jacob, Zubin
2017-01-25
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.
Interatomic Coulombic decay cascades in multiply excited neon clusters
Nagaya, K.; Iablonskyi, D.; Golubev, N. V.; Matsunami, K.; Fukuzawa, H.; Motomura, K.; Nishiyama, T.; Sakai, T.; Tachibana, T.; Mondal, S.; Wada, S.; Prince, K. C.; Callegari, C.; Miron, C.; Saito, N.; Yabashi, M.; Demekhin, Ph. V.; Cederbaum, L. S.; Kuleff, A. I.; Yao, M.; Ueda, K.
2016-01-01
In high-intensity laser light, matter can be ionized by direct multiphoton absorption even at photon energies below the ionization threshold. However on tuning the laser to the lowest resonant transition, the system becomes multiply excited, and more efficient, indirect ionization pathways become operative. These mechanisms are known as interatomic Coulombic decay (ICD), where one of the species de-excites to its ground state, transferring its energy to ionize another excited species. Here we show that on tuning to a higher resonant transition, a previously unknown type of interatomic Coulombic decay, intra-Rydberg ICD occurs. In it, de-excitation of an atom to a close-lying Rydberg state leads to electron emission from another neighbouring Rydberg atom. Moreover, systems multiply excited to higher Rydberg states will decay by a cascade of such processes, producing even more ions. The intra-Rydberg ICD and cascades are expected to be ubiquitous in weakly-bound systems exposed to high-intensity resonant radiation. PMID:27917867
Interatomic Coulombic decay cascades in multiply excited neon clusters
NASA Astrophysics Data System (ADS)
Nagaya, K.; Iablonskyi, D.; Golubev, N. V.; Matsunami, K.; Fukuzawa, H.; Motomura, K.; Nishiyama, T.; Sakai, T.; Tachibana, T.; Mondal, S.; Wada, S.; Prince, K. C.; Callegari, C.; Miron, C.; Saito, N.; Yabashi, M.; Demekhin, Ph. V.; Cederbaum, L. S.; Kuleff, A. I.; Yao, M.; Ueda, K.
2016-12-01
In high-intensity laser light, matter can be ionized by direct multiphoton absorption even at photon energies below the ionization threshold. However on tuning the laser to the lowest resonant transition, the system becomes multiply excited, and more efficient, indirect ionization pathways become operative. These mechanisms are known as interatomic Coulombic decay (ICD), where one of the species de-excites to its ground state, transferring its energy to ionize another excited species. Here we show that on tuning to a higher resonant transition, a previously unknown type of interatomic Coulombic decay, intra-Rydberg ICD occurs. In it, de-excitation of an atom to a close-lying Rydberg state leads to electron emission from another neighbouring Rydberg atom. Moreover, systems multiply excited to higher Rydberg states will decay by a cascade of such processes, producing even more ions. The intra-Rydberg ICD and cascades are expected to be ubiquitous in weakly-bound systems exposed to high-intensity resonant radiation.
Laser-Driven Recollisions under the Coulomb Barrier
NASA Astrophysics Data System (ADS)
Keil, Th.; Popruzhenko, S. V.; Bauer, D.
2016-12-01
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.
Enhancement of the Coulomb collision rate by individual particle wakes
NASA Astrophysics Data System (ADS)
Baalrud, Scott; Scheiner, Brett
2013-09-01
Charged particles moving in a plasma leave a trailing wake in their electric potential profile associated with the response function of the medium. For superthermal particles, these wakes can cause significant departures from the oft-assumed screened Coulomb potential profile. The wakes extend the interaction length scale beyond the Debye screening length for collisions between fast test particles and field particles in their wake. This can increase the Coulomb collision rate for velocities beyond the thermal speed. To demonstrate this effect, we consider the relaxation rate due to electron-electron collisions of an electron distribution function with initially depleted tails, as is common near boundary sheaths or double layers. This problem is related to Langmuir's paradox. We compare the standard Landau (Fokker-Planck) collision operator, which does not account for wakes, with the Lenard-Balescu collision operator, which includes wake effects through the linear dielectric response function. For this distribution, the linear dielectric is described by the incomplete plasma dispersion function. We compare the collision operators directly as well as the relaxation rate determined from a hybrid kinetic-fluid model. S. D. Baalrud, Phys. Plasmas 20, 012118 (2013).
Revision of the Coulomb logarithm in the ideal plasma
Mulser, P. Alber, G.; Murakami, M.
2014-04-15
The standard picture of the Coulomb logarithm in the ideal plasma is controversial, the arguments for the lower cut off need revision. The two cases of far subthermal and of far superthermal electron drift motions are accessible to a rigorous analytical treatment. We show that the lower cut off b{sub min} is a function of symmetry and shape of the shielding cloud, it is not universal. In the subthermal case, shielding is spherical and b{sub min} is to be identified with the de Broglie wavelength; at superthermal drift the shielding cloud exhibits cylindrical (axial) symmetry and b{sub min} is the classical parameter of perpendicular deflection. In both situations, the cut offs are determined by the electron-ion encounters at large collision parameters. This is in net contrast to the governing standard interpretation that attributes b{sub min} to the Coulomb singularity at vanishing collision parameters b and, consequently, assigns it universal validity. The origin of the contradictions in the traditional picture is analyzed.
Super-Coulombic atom–atom interactions in hyperbolic media
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. PMID:28120826
Super-Coulombic atom-atom interactions in hyperbolic media
NASA Astrophysics Data System (ADS)
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.
Slave rotor approach to dynamically screened Coulomb interactions in solids
NASA Astrophysics Data System (ADS)
Krivenko, I. S.; Biermann, S.
2015-04-01
Recent studies of dynamical screening of the electronic Coulomb interactions in solids have revived interest in lattice models of correlated fermions coupled to bosonic degrees of freedom (Hubbard-Holstein-type models). We propose a new dynamical mean-field-based approach to dynamically screened Coulomb interactions. In the effective Anderson-Holstein model, a transformation to slave rotors [S. Florens and A. Georges, Phys. Rev. B 66, 165111 (2002), 10.1103/PhysRevB.66.165111] is performed to decouple the dynamical part of the interaction. This transformation allows for a systematic derivation and analysis of recently introduced approximate schemes for the solution of dynamical impurity problems, in particular, the Bose factor ansatz within the dynamic atomic limit approximation (DALA) with and without Lang-Firsov correction. More importantly still, it suggests an optimized choice for a Bose factor in the sense of the variational principle of Feynman and Peierls. We demonstrate the accuracy of our scheme and present a comparison to calculations within the DALA.
Coulomb-corrected molecular orbital tomography of nitrogen.
Zhai, Chunyang; He, Lixin; Lan, Pengfei; Zhu, Xiaosong; Li, Yang; Wang, Feng; Shi, Wenjing; Zhang, Qingbin; Lu, Peixiang
2016-03-22
High-order harmonic generation (HHG) from aligned molecules has provided a promising way to probe the molecular orbital with an Ångström resolution. This method, usually called molecular orbital tomography (MOT) replies on a simple assumption of the plane-wave approximation (PW), which has long been questioned due to that PW approximation is known to be valid in the keV energy region. However, the photon energy is usually no more than 100 eV in HHG. In this work, we experimentally reconstruct the highest occupied molecular orbital (HOMO) of nitrogen (N2) by using a Coulomb-corrected MOT (CCMOT) method. In our scheme, the molecular continuum states are described by a Coulomb wave function instead of the PW approximation. With CCMOT, the reconstructed orbital is demonstrated to agree well with the theoretical prediction and retain the main features of the HOMO of N2. Compared to the PW approximation method, the CCMOT shows a significant improvement in eliminating the artificial structures caused by PW approximation.
Exact linearized Coulomb collision operator in the moment expansion
Ji, Jeong -Young; Held, Eric D.
2006-10-05
In the moment expansion, the Rosenbluth potentials, the linearized Coulomb collision operators, and the moments of the collision operators are analytically calculated for any moment. The explicit calculation of Rosenbluth potentials converts the integro-differential form of the Coulomb collision operator into a differential operator, which enables one to express the collision operator in a simple closed form for any arbitrary mass and temperature ratios. In addition, it is shown that gyrophase averaging the collision operator acting on arbitrary distribution functions is the same as the collision operator acting on the corresponding gyrophase averaged distribution functions. The moments of the collisionmore » operator are linear combinations of the fluid moments with collision coefficients parametrized by mass and temperature ratios. Furthermore, useful forms involving the small mass-ratio approximation are easily found since the collision operators and their moments are expressed in terms of the mass ratio. As an application, the general moment equations are explicitly written and the higher order heat flux equation is derived.« less
Absence of exponential clustering in quantum Coulomb fluids
NASA Astrophysics Data System (ADS)
Alastuey, A.; Martin, Ph. A.
1989-12-01
We show that the quantum corrections to the classical correlations of a Coulomb fluid do not decay exponentially fast for all values of the thermodynamical parameters. Specifically, the ħ4 term in the Wigner-Kirkwood expansion of the equilibrium charge-charge correlations of the quantum one-component plasma is found to decay like ||r||-10. More generally, using functional integration, we present a diagrammatic representation of the ħ expansion of the correlations in a multicomponent fluid with a locally regularized Coulomb potential and Maxwell-Boltzmann statistics. The ħ2n terms are found to decay algebraically for all n>=2. Furthermore, an analysis of the hierarchy equations for the correlations provides upper bounds that are compatible with the findings of the perturbative expansion. Except for the monopole, all higher-order multipole sum rules do not hold, in general, in the quantum system. This violation of the multipole sum rules as well as the related algebraic tails are due to the intrinsic quantum fluctuations that prevent a perfect organization of the screening clouds. This phenomenon is illustrated in a simpler model where the large-distance correlations between two quantum particles embedded in a classical plasma can be exactly computed.
Influence of the Coulomb Force on Spray Cooling
NASA Astrophysics Data System (ADS)
Kuhlman, John M.; Kreitzer, Paul J.; Mehra, Deepak; Gray, Donald D.; Yerkes, Kirk L.
2007-01-01
Effects of the Coulomb electrical body force on heat transfer performance of an instrumented spray cooling experiment are reported. Heat transfer performance is documented for a range of spray volume flow rates and heater power levels using the dielectric liquids, FC-72 and HFE-7000, sprayed onto a Thick Film Resistor (TFR) heater; along with flow visualization results using a transparent Indium-Tin Oxide (ITO) heater. Two Coulomb force electrode geometries show modest but consistent improvements in heat transfer (order of 5-15%), but only at heat fluxes where boiling of the liquid film occurs. Flow visualization shows a highly contorted liquid film forming on the heater surface. These flow visualization results are used to aid in the estimation of characteristic time scales governing the effects of surface tension, gravity, heating of the liquid film, and vaporization of the film. For the present dense liquid sprays, it is concluded that none of these time scales are as short as the average time between droplet impacts into a heater surface area equal to the estimated size of the thin, crater-like liquid films formed by a previous droplet impact.
Room temperature Coulomb blockade mediated field emission via self-assembled gold nanoparticles
NASA Astrophysics Data System (ADS)
Wang, Fei; Fang, Jingyue; Chang, Shengli; Qin, Shiqiao; Zhang, Xueao; Xu, Hui
2017-02-01
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.
"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications
NASA Technical Reports Server (NTRS)
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
Energy Proportionality for Disk Storage Using Replication
Kim, Jinoh; Rotem, Doron
2010-09-09
Energy saving has become a crucial concern in datacenters as several reports predict that the anticipated energy costs over a three year period will exceed hardware acquisition. In particular, saving energy for storage is of major importance as storage devices (and cooling them off) may contribute over 25 percent of the total energy consumed in a datacenter. Recent work introduced the concept of energy proportionality and argued that it is a more relevant metric than just energy saving as it takes into account the tradeoff between energy consumption and performance. In this paper, we present a novel approach, called FREP (Fractional Replication for Energy Proportionality), for energy management in large datacenters. FREP includes areplication strategy and basic functions to enable flexible energy management. Specifically, our method provides performance guarantees by adaptively controlling the power states of a group of disks based on observed and predicted workloads. Our experiments, using a set of real and synthetic traces, show that FREP dramatically reduces energy requirements with a minimal response time penalty.
Kalman-predictive-proportional-integral-derivative (KPPID)
Fluerasu, A.; Sutton, M.
2004-12-17
With third generation synchrotron X-ray sources, it is possible to acquire detailed structural information about the system under study with time resolution orders of magnitude faster than was possible a few years ago. These advances have generated many new challenges for changing and controlling the state of the system on very short time scales, in a uniform and controlled manner. For our particular X-ray experiments on crystallization or order-disorder phase transitions in metallic alloys, we need to change the sample temperature by hundreds of degrees as fast as possible while avoiding over or under shooting. To achieve this, we designed and implemented a computer-controlled temperature tracking system which combines standard Proportional-Integral-Derivative (PID) feedback, thermal modeling and finite difference thermal calculations (feedforward), and Kalman filtering of the temperature readings in order to reduce the noise. The resulting Kalman-Predictive-Proportional-Integral-Derivative (KPPID) algorithm allows us to obtain accurate control, to minimize the response time and to avoid over/under shooting, even in systems with inherently noisy temperature readings and time delays. The KPPID temperature controller was successfully implemented at the Advanced Photon Source at Argonne National Laboratories and was used to perform coherent and time-resolved X-ray diffraction experiments.
Viking-Age Sails: Form and Proportion
NASA Astrophysics Data System (ADS)
Bischoff, Vibeke
2017-01-01
Archaeological ship-finds have shed much light on the design and construction of vessels from the Viking Age. However, the exact proportions of their sails remain unknown due to the lack of fully preserved sails, or other definite indicators of their proportions. Key Viking-Age ship-finds from Scandinavia—the Oseberg Ship, the Gokstad Ship and Skuldelev 3—have all revealed traces of rigging. In all three finds, the keelson—with the mast position—is preserved, together with fastenings for the sheets and the tack, indicating the breadth of the sail. The sail area can then be estimated based on practical experience of how large a sail the specific ship can carry, in conjunction with hull form and displacement. This article presents reconstructions of the form and dimensions of rigging and sail based on the archaeological finds, evidence from iconographic and written sources, and ethnographic parallels with traditional Nordic boats. When these sources are analysed, not only do the similarities become apparent, but so too does the relative disparity between the archaeological record and the other sources. Preferential selection in terms of which source is given the greatest merit is therefore required, as it is not possible to afford them all equal value.
ProPortal: A Database for Prochlorococcus
Huang, Katherine [Chisholm lab, MIT
Prochlorococcus is a marine cyanobacterium that numerically dominates the mid-latitude oceans, and is the smallest known oxygenic phototroph. All isolates described thus far can be assigned to either a tightly clustered high-light (HL) adapted clade, or a more divergent low-light (LL) adapted group. They are closely related to, but distinct from, marine Synechococcus. The genomes of 12 strains have been sequenced and they range in size from 1.6 to 2.6 Mbp. They represent diverse lineages, spanning the rRNA diversity (97 to 99.93% similarity) of cultured representatives of this group. Our analyses of these genomes inform our understanding of how adaptation occurs in the oceans along gradients of light, nutrients, and other environmental factors, providing essential context for interpreting rapidly expanding metagenomic datasets. [Copied from http://proportal.mit.edu/project/prochlorococcus/] ProPortal allows users to browse and search genome date for not only Prochlorococcus, but Cyanophage and Synechococcus. Microarray data, environmental cell concentration data, and metagenome information are also available.
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 I< or =10(17) W cm(-2)), and the attainment of cluster vertical ionization (CVI) (at I=10(17) W cm(-2) for cluster radius R(0)< or =31 A). Nuclear kinematic effects on heterocluster Coulomb explosion are governed by the kinematic parameter eta=q(C)m(A)/q(A)m(C) for (CA(4))(n) clusters (A=H,D), where q(j) and m(j) (j=A,C) are the ionic charges 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)< or
Time-lapse nanoscopy of friction in the non-Amontons and non-Coulomb regime.
Ishida, Tadashi; Sato, Takaaki; Ishikawa, Takahiro; Oguma, Masatsugu; Itamura, Noriaki; Goda, Keisuke; Sasaki, Naruo; Fujita, Hiroyuki
2015-03-11
Originally discovered by Leonard da Vinci in the 15th century, the force of friction is directly proportional to the applied load (known as Amontons' first law of friction). Furthermore, kinetic friction is independent of the sliding speed (known as Coulomb's law of friction). These empirical laws break down at high normal pressure (due to plastic deformation) and low sliding speed (in the transition regime between static friction and kinetic friction). An important example of this phenomenon is friction between the asperities of tectonic plates on the Earth. Despite its significance, little is known about the detailed mechanism of friction in this regime due to the lack of experimental methods. Here we demonstrate in situ time-lapse nanoscopy of friction between asperities sliding at ultralow speed (∼0.01 nm/s) under high normal pressure (∼GPa). This is made possible by compressing and rubbing a pair of nanometer-scale crystalline silicon anvils with electrostatic microactuators and monitoring its dynamical evolution with a transmission electron microscope. Our analysis of the time-lapse movie indicates that superplastic behavior is induced by decrystallization, plastic deformation, and atomic diffusion at the asperity-asperity interface. The results hold great promise for a better understanding of quasi-static friction under high pressure for geoscience, materials science, and nanotechnology.
Discontinuities of multi-Regge amplitudes
NASA Astrophysics Data System (ADS)
Fadin, V. S.
2015-04-01
In the BFKL approach, discontinuities of multiple production amplitudes in invariant masses of produced particles are discussed. It turns out that they are in evident contradiction with the BDS ansatz for n-gluon amplitudes in the planar N = 4 SYM at n ≥ 6. An explicit expression for the NLO discontinuity of the two-to-four amplitude in the invariant mass of two produced gluons is is presented.
Minimal Basis for Gauge Theory Amplitudes
Bjerrum-Bohr, N. E. J.; Damgaard, Poul H.; Vanhove, Pierre
2009-10-16
Identities based on monodromy for integrations in string theory are used to derive relations between different color-ordered tree-level amplitudes in both bosonic and supersymmetric string theory. These relations imply that the color-ordered tree-level n-point gauge theory amplitudes can be expanded in a minimal basis of (n-3)exclamation amplitudes. This result holds for any choice of polarizations of the external states and in any number of dimensions.
Gravity and Yang-Mills amplitude relations
Bjerrum-Bohr, N. E. J.; Damgaard, Poul H.; Soendergaard, Thomas; FengBo
2010-11-15
Using only general features of the S matrix and quantum field theory, we prove by induction the Kawai-Lewellen-Tye relations that link products of gauge theory amplitudes to gravity amplitudes at tree level. As a bonus of our analysis, we provide a novel and more symmetric form of these relations. We also establish an infinite tower of new identities between amplitudes in gauge theories.
TRIAC/SCR proportional control circuit
Hughes, Wallace J.
1999-01-01
A power controller device which uses a voltage-to-frequency converter in conjunction with a zero crossing detector to linearly and proportionally control AC power being supplied to a load. The output of the voltage-to frequency converter controls the "reset" input of a R-S flip flop, while an "0" crossing detector controls the "set" input. The output of the flip flop triggers a monostable multivibrator controlling the SCR or TRIAC firing circuit connected to the load. Logic gates prevent the direct triggering of the multivibrator in the rare instance where the "reset" and "set" inputs of the flip flop are in coincidence. The control circuit can be supplemented with a control loop, providing compensation for line voltage variations.
TRIAC/SCR proportional control circuit
Hughes, W.J.
1999-04-06
A power controller device is disclosed which uses a voltage-to-frequency converter in conjunction with a zero crossing detector to linearly and proportionally control AC power being supplied to a load. The output of the voltage-to frequency converter controls the ``reset`` input of a R-S flip flop, while an ``0`` crossing detector controls the ``set`` input. The output of the flip flop triggers a monostable multivibrator controlling the SCR or TRIAC firing circuit connected to the load. Logic gates prevent the direct triggering of the multivibrator in the rare instance where the ``reset`` and ``set`` inputs of the flip flop are in coincidence. The control circuit can be supplemented with a control loop, providing compensation for line voltage variations. 9 figs.
A proportional temperature controller with automatic shutoff
NASA Astrophysics Data System (ADS)
Lucich, G. M.; Holland, P. W.
1980-08-01
A sensitive, proportional temperature controller useful in the temperature range from 40 to 400 C with an accuracy of plus or minus 0.1 C is described. It is potentially useful for regulating temperatures in air chambers, liquid baths, furnaces and reaction vessels and for other applications. This instrument was developed to control the duration and temperature of the heating cycle of a charcoal filled adsorber that is part of a special helium analyzer. The controller was made from commercially available parts and can be easily modified to provide continuous temperature control. The circuit is solid state and employs no electromechanical devices. Over a 2 year period of use as a component of the special helium analyzer, this temperature controller performed successfully and required no maintenance.
Microstrip proportional counter development at MSFC
NASA Technical Reports Server (NTRS)
Fulton, M. A.; Kolodziejczak, J. J.; Ramsey, B. D.
1992-01-01
Microstrip detectors are an exciting new development in proportional counter design fabricated using integrated circuit-type photolithography techniques; they therefore offer very high spatial accuracy and uniformity. A development program is underway at NASA-Marshall to produce large-area microstrips for use in an X-ray detector balloon flight program and to investigate the general performance limits of these new devices. Microstrips tested so far have been fabricated both in-house using standard photolithographic techniques and by an outside contractor using electron beam technology. Various substrate materials have been tested along with different electrode configurations. The distributions of pickup on subdivided cathodes on both top and bottom surfaces of the microstrips are also being investigated for use as two-dimensional imaging detectors. Data from these tests in the development of a large-area device will be presented.
Boron-10 Lined Proportional Counter Model Validation
Lintereur, Azaree T.; Siciliano, Edward R.; Kouzes, Richard T.
2012-06-30
The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project “Coincidence Counting With Boron-Based Alternative Neutron Detection Technology” at Pacific Northwest National Laboratory (PNNL) for the development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube-based alternative system in the configuration of a coincidence counter. This report discusses the validation studies performed to establish the degree of accuracy of the computer modeling methods current used to simulate the response of boron-lined tubes. This is the precursor to developing models for the uranium neutron coincidence collar under Task 2 of this project.
Scaling and universality in proportional elections.
Fortunato, Santo; Castellano, Claudio
2007-09-28
A most debated topic of the last years is whether simple statistical physics models can explain collective features of social dynamics. A necessary step in this line of endeavor is to find regularities in data referring to large-scale social phenomena, such as scaling and universality. We show that, in proportional elections, the distribution of the number of votes received by candidates is a universal scaling function, identical in different countries and years. This finding reveals the existence in the voting process of a general microscopic dynamics that does not depend on the historical, political, and/or economical context where voters operate. A simple dynamical model for the behavior of voters, similar to a branching process, reproduces the universal distribution.
Lindesay, James V
2002-03-12
Starting from a unitary, Lorentz invariant two-particle scattering amplitude, we show how to use an identification and replacement process to construct a unique, unitary particle-antiparticle amplitude. This process differs from conventional on-shell Mandelstam s,t,u crossing in that the input and constructed amplitudes can be off-diagonal and off-energy shell. Further, amplitudes are constructed using the invariant parameters which are appropriate to use as driving terms in the multi-particle, multichannel nonperturbative, cluster decomposable, relativistic scattering equations of the Faddeev-type integral equations recently presented by Alfred, Kwizera, Lindesay and Noyes. It is therefore anticipated that when so employed, the resulting multi-channel solutions will also be unitary. The process preserves the usual particle-antiparticle symmetries. To illustrate this process, we construct a J=0 scattering length model chosen for simplicity. We also exhibit a class of physical models which contain a finite quantum mass parameter and are Lorentz invariant. These are constructed to reduce in the appropriate limits, and with the proper choice of value and sign of the interaction parameter, to the asymptotic solution of the nonrelativistic Coulomb problem, including the forward scattering singularity , the essential singularity in the phase, and the Bohr bound-state spectrum.
DVCS amplitude with kinematical twist-3 terms
Radyushkin, A.V.; Weiss, C.
2000-08-01
The authors compute the amplitude of deeply virtual Compton scattering (DVCS) using the calculus of QCD string operators in coordinate representation. To restore the electromagnetic gauge invariance (transversality) of the twist-2 amplitude they include the operators of twist-3 which appear as total derivatives of twist-2 operators. The results are equivalent to a Wandzura-Wilczek approximation for twist-3 skewed parton distributions. They find that this approximation gives a finite result for the amplitude of a longitudinally polarized virtual photon, while the amplitude for transverse polarization is divergent, i.e., factorization breaks down in this term.
Interatomic Coulombic decay widths of helium trimer: Ab initio calculations
Kolorenč, Přemysl; Sisourat, Nicolas
2015-12-14
We report on an extensive study of interatomic Coulombic decay (ICD) widths in helium trimer computed using a fully ab initio method based on the Fano theory of resonances. Algebraic diagrammatic construction for one-particle Green’s function is utilized for the solution of the many-electron problem. An advanced and universal approach to partitioning of the configuration space into discrete states and continuum subspaces is described and employed. Total decay widths are presented for all ICD-active states of the trimer characterized by one-site ionization and additional excitation of an electron into the second shell. Selected partial decay widths are analyzed in detail, showing how three-body effects can qualitatively change the character of certain relaxation transitions. Previously unreported type of three-electron decay processes is identified in one class of the metastable states.
Coulomb-stable triply charged diatomic: HeY3+
NASA Astrophysics Data System (ADS)
Wesendrup, Ralf; Pernpointner, Markus; Schwerdtfeger, Peter
1999-11-01
Accurate relativistic coupled-cluster calculations show that the triply charged species HeY3+ is a stable molecule and represents the lightest diatomic trication that does not undergo a Coulomb fragmentation into charged fragments. The diatomic potential-energy curve is approximated by an extended Morse potential, and vibrational-rotational constants for HeY3+ are predicted (Re=224.3 pm, D0=0.394 eV, ωe=437 cm-1, ωexe=15.8 cm-1, Be=0.877 cm-1). It is further shown that the He-Y3+ bond can basically be described as a charge-induced dipole interaction.
Strong nuclear couplings as a source of Coulomb rainbow suppression
Keeley, N.; Alamanos, N.; Rusek, K.
2010-09-15
A recent measurement of the {sup 11}Be+{sup 64}Zn quasielastic scattering angular distribution exhibits a non-Fresnel-type pattern, in contrast to {sup 6}He+{sup 64}Zn elastic scattering but similar to that for the elastic scattering of {sup 6}He from heavy targets. We show by means of continuum discretized coupled-channels (CDCC) calculations that this unusual behavior of {sup 11}Be is caused by the much greater importance of nuclear coupling to the continuum in {sup 11}Be compared to {sup 6}He, where Coulomb dipole coupling is mainly responsible for the non-Fresnel-like shape, when present. We also show that the dynamic polarization potentials derived from the CDCC calculations seem to follow a universal form as a function of radius.
Coulomb gauge confinement in the heavy quark limit
Popovici, C.; Watson, P.; Reinhardt, H.
2010-05-15
The relationship between the nonperturbative Green's functions of Yang-Mills theory and the confinement potential is investigated. By rewriting the generating functional of quantum chromodynamics in terms of a heavy quark mass expansion in Coulomb gauge, restricting to leading order in this expansion and considering only the two-point functions of the Yang-Mills sector, the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is shown to be exact in this case and an analytic, nonperturbative solution is presented. It is found that there is a direct connection between the string tension and the temporal gluon propagator. Further, it is shown that for the 4-point quark correlation functions, only confined bound states of color-singlet quark-antiquark (meson) and quark-quark (baryon) pairs exist.
Slow Interatomic Coulombic Decay of Multiply Excited Neon Clusters
NASA Astrophysics Data System (ADS)
Iablonskyi, D.; Nagaya, K.; Fukuzawa, H.; Motomura, K.; Kumagai, Y.; Mondal, S.; Tachibana, T.; Takanashi, T.; Nishiyama, T.; Matsunami, K.; Johnsson, P.; Piseri, P.; Sansone, G.; Dubrouil, A.; Reduzzi, M.; Carpeggiani, P.; Vozzi, C.; Devetta, M.; Negro, M.; Calegari, F.; Trabattoni, A.; Castrovilli, M. C.; Faccialà, D.; Ovcharenko, Y.; Möller, T.; Mudrich, M.; Stienkemeier, F.; Coreno, M.; Alagia, M.; Schütte, B.; Berrah, N.; Kuleff, A. I.; Jabbari, G.; Callegari, C.; Plekan, O.; Finetti, P.; Spezzani, C.; Ferrari, E.; Allaria, E.; Penco, G.; Serpico, C.; De Ninno, G.; Nikolov, I.; Diviacco, B.; Di Mitri, S.; Giannessi, L.; Prince, K. C.; Ueda, K.
2016-12-01
Ne clusters (˜5000 atoms ) were resonantly excited (2 p →3 s ) by intense free electron laser (FEL) radiation at FERMI. Such multiply excited clusters can decay nonradiatively via energy exchange between at least two neighboring excited atoms. Benefiting from the precise tunability and narrow bandwidth of seeded FEL radiation, specific sites of the Ne clusters were probed. We found that the relaxation of cluster surface atoms proceeds via a sequence of interatomic or intermolecular Coulombic decay (ICD) processes while ICD of bulk atoms is additionally affected by the surrounding excited medium via inelastic electron scattering. For both cases, cluster excitations relax to atomic states prior to ICD, showing that this kind of ICD is rather slow (picosecond range). Controlling the average number of excitations per cluster via the FEL intensity allows a coarse tuning of the ICD rate.
Gribov pendulum in the Coulomb gauge on curved spaces
NASA Astrophysics Data System (ADS)
Canfora, Fabrizio; Giacomini, Alex; Oliva, Julio
2011-11-01
In this paper the generalization of the Gribov pendulum equation in the Coulomb gauge for curved space-times is analyzed on static spherically symmetric backgrounds. A rigorous argument for the existence and uniqueness of solution is provided in the asymptotically AdS case. The analysis of the strong and weak boundary conditions is equivalent to analyzing an effective one-dimensional Schrödinger equation. Necessary conditions in order for spherically symmetric backgrounds to admit solutions of the Gribov pendulum equation representing copies of the vacuum satisfying the strong boundary conditions are given. It is shown that asymptotically flat backgrounds do not support solutions of the Gribov pendulum equation of this type, while on asymptotically AdS backgrounds such ambiguities can appear. Some physical consequences are discussed.
Finsler-type modification of the Coulomb law
NASA Astrophysics Data System (ADS)
Itin, Yakov; Lämmerzahl, Claus; Perlick, Volker
2014-12-01
Finsler geometry is a natural generalization of pseudo-Riemannian geometry. It can be motivated e.g. by a modified version of the Ehlers-Pirani-Schild axiomatic approach to space-time theory. Also, some scenarios of quantum gravity suggest a modified dispersion relation which could be phrased in terms of Finsler geometry. On a Finslerian space-time, the universality of free fall is still satisfied but local Lorentz invariance is violated in a way not covered by standard Lorentz invariance violation schemes. In this paper we consider a Finslerian modification of Maxwell's equations. The corrections to the Coulomb potential and to the hydrogen energy levels are computed. We find that the Finsler metric corrections yield a splitting of the energy levels. Experimental data provide bounds for the Finsler parameters.
Coulomb-blockade and Pauli-blockade magnetometry
NASA Astrophysics Data System (ADS)
Széchenyi, Gábor; Pályi, András
2017-01-01
Scanning-probe magnetometry is a valuable experimental tool to investigate magnetic phenomena at the micro- and nanoscale. We theoretically analyze the possibility of measuring magnetic fields via the electrical current flowing through quantum dots. We characterize the shot-noise-limited magnetic-field sensitivity of two devices: a single dot in the Coulomb blockade regime, and a double dot in the Pauli blockade regime. Constructing such magnetometers using carbon nanotube quantum dots would benefit from the large, strongly anisotropic and controllable g tensors, the low abundance of nuclear spins, and the small detection volume allowing for nanoscale spatial resolution; we estimate that a sensitivity below 1 μ T/√{Hz} can be achieved with this material. As quantum dots have already proven to be useful as scanning-probe electrometers, our proposal highlights their potential as hybrid sensors having in situ switching capability between electrical and magnetic sensing.
Classical Kepler-Coulomb problem on SO(2, 2) hyperboloid
Petrosyan, D. Pogosyan, G. S.
2013-10-15
In the present work, the problem of the motion of the classical particle in the Kepler-Coulomb field in three-dimensional hyperbolic space H{sub 2}{sup 2}: z{sub 2}{sup 0} + z{sub 2}{sup 1} - z{sub 2}{sup 2} - z{sub 2}{sup 3} = R{sup 2} is solved in the framework of Hamilton-Jacobi equation. The requirements for the existence of bounded motion of particle are formulated. The equation of the trajectory of particle is obtained, and it is shown that all the finite trajectories are closed. It is also demonstrated that under the certain values (zero or negative) of the separation constant A the fall of the particle onto the center takes place.
Ultra-high-ohmic microstripline resistors for Coulomb blockade devices
NASA Astrophysics Data System (ADS)
Lotkhov, Sergey V.
2013-06-01
In this paper, we report on the fabrication and low-temperature characterization of ultra-high-ohmic microstripline resistors made of a thin film of weakly oxidized titanium. Nearly linear voltage-current characteristics were measured at temperatures down to T ˜ 20 mK for films with sheet resistivities as high as ˜7 kΩ, i.e. about an order of magnitude higher than our previous findings for weakly oxidized Cr. Our analysis indicates that such an improvement can help to create an advantageous high-impedance environment for different Coulomb blockade devices. Further properties of the Ti film addressed in this work show the promise of low-noise behavior of the resistors when applied in different realizations of the quantum standard of current.
Ultra-high-ohmic microstripline resistors for Coulomb blockade devices.
Lotkhov, Sergey V
2013-06-14
In this paper, we report on the fabrication and low-temperature characterization of ultra-high-ohmic microstripline resistors made of a thin film of weakly oxidized titanium. Nearly linear voltage-current characteristics were measured at temperatures down to T ~ 20 mK for films with sheet resistivities as high as ~7 kΩ, i.e. about an order of magnitude higher than our previous findings for weakly oxidized Cr. Our analysis indicates that such an improvement can help to create an advantageous high-impedance environment for different Coulomb blockade devices. Further properties of the Ti film addressed in this work show the promise of low-noise behavior of the resistors when applied in different realizations of the quantum standard of current.
Relativistic Aharonov{endash}Bohm{endash}Coulomb problem
Hagen, C.R.; Park, D.K.
1996-10-01
The ((2+1)-dimensional) Aharonov{endash}Bohm effect is analyzed for a spin-1/2 particle in the case that a 1/{ital r} potential is present. Scalar and vector couplings are each considered. It is found that the approach in which the flux tube is given a finite radius that is taken to zero only after a matching of boundary conditions does not give physically meaningful results. Specifically, the operations of taking the limit of zero flux tube radius and the Galilean limit do not commute. Thus there appears to be no satisfactory solution of the relativistic Aharonov{endash}Bohm{endash}Coulomb problem using the finite radius flux tube method. Copyright {copyright} 1996 Academic Press, Inc.
Configurational and energy landscape in one-dimensional Coulomb systems
NASA Astrophysics Data System (ADS)
Varela, Lucas; Téllez, Gabriel; Trizac, Emmanuel
2017-02-01
We study a one-dimensional Coulomb system, where two charged colloids are neutralized by a collection of point counterions, with global neutrality. With temperature being given, two situations are addressed: Either the colloids are kept at fixed positions (canonical ensemble) or the force acting on the colloids is fixed (isobaric-isothermal ensemble). The corresponding partition functions are worked out exactly, in view of determining which arrangement of counterions is optimal. How many counterions should be in the confined segment between the colloids? For the remaining ions outside, is there a left-right symmetry breakdown? We evidence a cascade of transitions as system size is varied in the canonical treatment or as pressure is increased in the isobaric formulation.
Coulomb Excitation of the N = 50 nucleus 80Zn
NASA Astrophysics Data System (ADS)
van de Walle, J.; Aksouh, F.; Ames, F.; Behrens, T.; Bildstein, V.; Blazhev, A.; Cederkäll, J.; Clément, E.; Cocolios, T. E.; Davinson, T.; Delahaye, P.; Eberth, J.; Ekström, A.; Fedorov, D. V.; Fedosseev, V. N.; Fraile, L. M.; Franchoo, S.; Gernhauser, R.; Georgiev, G.; Habs, D.; Heyde, K.; Huber, G.; Huyse, M.; Ibrahim, F.; Ivanov, O.; Iwanicki, J.; Jolie, J.; Kester, O.; Köster, U.; Kröll, T.; Krücken, R.; Lauer, M.; Lisetskiy, A. F.; Lutter, R.; Marsh, B. A.; Mayet, P.; Niedermaier, O.; Nilsson, T.; Pantea, M.; Perru, O.; Raabe, R.; Reiter, P.; Sawicka, M.; Scheit, H.; Schrieder, G.; Schwalm, D.; Seliverstov, M. D.; Sieber, T.; Sletten, G.; Smirnova, N.; Stanoiu, M.; Stefanescu, I.; Thomas, J.-C.; Valiente-Dobón, J. J.; van Duppen, P.; Verney, D.; Voulot, D.; Warr, N.; Weisshaar, D.; Wenander, F.; Wolf, B. H.; Zielińska, M.
2008-05-01
Neutron rich Zinc isotopes, including the N = 50 nucleus 80Zn, were produced and post-accelerated at the Radioactive Ion Beam (RIB) facility REX-ISOLDE (CERN). Low-energy Coulomb excitation was induced on these isotopes after post-acceleration, yielding B(E2) strengths to the first excited 2+ states. For the first time, an excited state in 80Zn was observed and the 21+ state in 78Zn was established. The measured B(E2,21+-->01+) values are compared to two sets of large scale shell model calculations. Both calculations reproduce the observed B(E2) systematics for the full Zinc isotopic chain. The results for N = 50 isotones indicate a good N = 50 shell closure and a strong Z = 28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni.
Configurational and energy landscape in one-dimensional Coulomb systems.
Varela, Lucas; Téllez, Gabriel; Trizac, Emmanuel
2017-02-01
We study a one-dimensional Coulomb system, where two charged colloids are neutralized by a collection of point counterions, with global neutrality. With temperature being given, two situations are addressed: Either the colloids are kept at fixed positions (canonical ensemble) or the force acting on the colloids is fixed (isobaric-isothermal ensemble). The corresponding partition functions are worked out exactly, in view of determining which arrangement of counterions is optimal. How many counterions should be in the confined segment between the colloids? For the remaining ions outside, is there a left-right symmetry breakdown? We evidence a cascade of transitions as system size is varied in the canonical treatment or as pressure is increased in the isobaric formulation.
Anomalous Coulomb drag in bilayer graphene double layers
NASA Astrophysics Data System (ADS)
Liu, Xiaomeng; Taniguchi, Takashi; Watanabe, Kenji; Kim, Philip
Bilayer graphene double-layer structure consists of two layers of bilayer graphene separated by atomically thin hexagonal boron nitride (hBN). With a perfect Fermi surface nesting and strong electron-electron interaction (ECoulomb > Ekinetic), such systems offer exciting platforms to study interaction driven phenomena, such as Coulomb drag and exciton condensation. We fabricate ultra-clean encapsulated bilayer graphene double layers with dry pick-up method. Room temperature drag measurement on our devices shows the sign of drag agree with the typical Fermi liquid behavior. However, at lower temperatures, the sign of drag reversed, indicating a new drag mechanism emerges and dominates. We measure this with different geometry, temperature, bias and gating to investigate the origin of such effect and discuss the implication of the drag sign changes.
Quantum Coulomb systems: some exact results in the atomic limit
NASA Astrophysics Data System (ADS)
Ballenegger, V.; Martin, Ph. A.
2002-04-01
We review a number of exact results concerning the recombined electron-proton gas. The recombination problem can be formulated in precise terms in the atomic limit. In this limit one lets the density and the temperature tend to zero in a coupled way so that the resulting energy-entropy balance favors the formation of certain chemical species. This enables to develop a clear understanding of the dielectric versus conducting behavior in the system. In particular, we give a first principle derivation of the dielectric constant of the dilute atomic gas without presupposing the existence of atoms. The analysis relies on the path integral representation of the Coulomb gas together with Mayer diagrammatic techniques.
Three-body Coulomb systems using generalized angular-momentum S states
NASA Technical Reports Server (NTRS)
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.
First-principles calculations of shear moduli for Monte Carlo-simulated Coulomb solids
NASA Technical Reports Server (NTRS)
Ogata, Shuji; Ichimaru, Setsuo
1990-01-01
The paper presents a first-principles study of the shear modulus tensor for perfect and imperfect Coulomb solids. Allowance is made for the effects of thermal fluctuations for temperatures up to the melting conditions. The present theory treats the cases of the long-range Coulomb interaction, where volume fluctuations should be avoided in the Ewald sums.
Exact tests for Hardy-Weinberg proportions.
Engels, William R
2009-12-01
Exact conditional tests are often required to evaluate statistically whether a sample of diploids comes from a population with Hardy-Weinberg proportions or to confirm the accuracy of genotype assignments. This requirement is especially common when the sample includes multiple alleles and sparse data, thus rendering asymptotic methods, such as the common chi(2)-test, unreliable. Such an exact test can be performed using the likelihood ratio as its test statistic rather than the more commonly used probability test. Conceptual advantages in using the likelihood ratio are discussed. A substantially improved algorithm is described to permit the performance of a full-enumeration exact test on sample sizes that are too large for previous methods. An improved Monte Carlo algorithm is also proposed for samples that preclude full enumeration. These algorithms are about two orders of magnitude faster than those currently in use. Finally, methods are derived to compute the number of possible samples with a given set of allele counts, a useful quantity for evaluating the feasibility of the full enumeration procedure. Software implementing these methods, ExactoHW, is provided.
Proportional mortality of 50 years and above
Swaroop, S.; Uemura, K.
1957-01-01
In 1954 the United Nations Committee of Experts on International Definition and Measurement of Standards and Levels of Living suggested that for the measurement of levels of living quantifiable or potentially quantifiable components should be considered separately. An attempt is made in the present paper to evolve a single, comprehensive numerical indicator to quantify the component “health, including demographic conditions”. The use of an objective statistical technique as a guide in the selection of such an indicator is suggested. From the application of this technique, it is concluded that the percentage of deaths at the ages 50 years and over to total deaths (proportional mortality) affords a fairly suitable yardstick by which broad inter-country comparisons may be made. This indicator has the advantages of simplicity of calculation, comprehensiveness, availability of data, possibility of international comparability despite the varying quality of basic statistical information, sensitivity for the purpose of inter-country comparisons, and validity for studying levels and trends. PMID:13500159
Coulomb-corrected eikonal description of the breakup of halo nuclei
Capel, P.; Baye, D.
2008-11-15
The eikonal description of breakup reactions diverges because of the Coulomb interaction between the projectile and the target. This divergence is due to the adiabatic, or sudden, approximation usually made, which is incompatible with the infinite range of the Coulomb interaction. A correction for this divergence is analyzed by comparison with the dynamical eikonal approximation, which is derived without the adiabatic approximation. The correction consists in replacing the first-order term of the eikonal Coulomb phase by the first-order of the perturbation theory. This allows taking into account both nuclear and Coulomb interactions on the same footing within the computationally efficient eikonal model. Excellent results are found for the dissociation of {sup 11}Be on lead at 69 MeV/nucleon. This Coulomb-corrected eikonal approximation provides a competitive alternative to more elaborate reaction models for investigating breakup of three-body projectiles at intermediate and high energies.
Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials
Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan
2015-07-14
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.
Magnetospheric chorus - Amplitude and growth rate
NASA Technical Reports Server (NTRS)
Burtis, W. J.; Helliwell, R. A.
1975-01-01
A new study of the amplitude of magnetospheric chorus with 1966-1967 data from the Stanford University/Stanford Research Institute VLF receivers on Ogo 1 and Ogo 3 has confirmed the band-limited character of magnetospheric chorus in general and the double-banding of near-equatorial chorus. Chorus amplitude tended to be inversely correlated with frequency, implying lower intensities at lower L values. Individual chorus emissions often showed a characteristic amplitude variation, with rise times of 10 to 300 ms, a short duration at peak amplitude, and decay times of 100 to 3000 msec. Growth was often approximately exponential, with rates from 200 to nearly 2000 dB/sec. Rate of change of frequency was found in many cases to be independent of emission amplitude, in agreement with the cyclotron feedback theory of chorus (Helliwell, 1967, 1970).
Amplitude image processing by diffractive optics.
Cagigal, Manuel P; Valle, Pedro J; Canales, V F
2016-02-22
In contrast to the standard digital image processing, which operates over the detected image intensity, we propose to perform amplitude image processing. Amplitude processing, like low pass or high pass filtering, is carried out using diffractive optics elements (DOE) since it allows to operate over the field complex amplitude before it has been detected. We show the procedure for designing the DOE that corresponds to each operation. Furthermore, we accomplish an analysis of amplitude image processing performances. In particular, a DOE Laplacian filter is applied to simulated astronomical images for detecting two stars one Airy ring apart. We also check by numerical simulations that the use of a Laplacian amplitude filter produces less noisy images than the standard digital image processing.
Thermal cracking and amplitude dependent attenuation
Johnston, D.H.; Toksoez, M.N.
1980-02-10
The role of crack and grain boundary contacts in determining seismic wave attenuation in rock is investigated by examining Q as a function of thermal cycling (cracking) and wave strain amplitude. Q values are obtained using a longitudinal resonant bar technique in the 10- to 20-kHz range for maximum strain amplitudes varying from roughly 10/sup -8/ to 10/sup -5/. The samples studied include the Berea and Navajo sandstones, Plexiglas, Westerly granite, Solenhofen limestone, and Frederick diabase, the latter two relatively crack free in their virgin state. Measurements were made at room temperature and pressure in air. Q values for both sandstones are constant at low strains (<10/sup -6/) but decrease rapidly with amplitude at higher strains. There is no hysteresis of Q with amplitude. Q values for Plexiglas show no indication of amplitude dependent behavior. The granite, limestone, and diabase are thermally cycled at both fast and slow heating rates in order to induce cracking. Samples slowly cycled at 400/sup 0/C show a marked increase in Q that cannot be entirely explained by outgassing of volatiles. Cycling may also widen thin cracks and grain boundaries, reducing contact areas. Samples heated beyond 400/sup 0/C, or rapidly heated, result in generally decreasing Q values. The amplitude dependence of Q is found to be coupled to the effects of thermal cycling. For rock slowly cycled 400)C or less, the transition from low-amplitude contant Q to high-amplitude variable Q behavior decreases to lower amplitudes as a function of maximum temperature. Above 400/sup 0/C, and possibly in th rapidly heated samples also, the transition moves to higher amplitudes.
The Effects of Static Coulomb Stress Change on Southern California Earthquake Forecasts
NASA Astrophysics Data System (ADS)
Strader, A. E.; Jackson, D. D.
2013-12-01
In previous studies, we confirmed an association between static Coulomb stress change and earthquake location in southern California, when resolving stress tensors onto uniformly oriented northwest right-lateral strike-slip planes (Deng & Sykes, 1997). Using an optimized index function to convert static Coulomb stress change into normalized seismicity rates, we found that the Coulomb stress-based forecasts were not significantly more effective indicators of future earthquake locations than forecasts based on smoothed seismicity (Hiemer et al., 2011). These results were likely due to Coulomb stress uncertainties, particularly near stress singularities at the ends of fault sections where many earthquakes occurred. We evaluate hybrid Coulomb stress/smoothed seismicity earthquake forecasts against those with earthquake rates derived from only one component, within a southern California study area (32°N-37°N latitude, 122°W-114°W longitude). Using a weighted linear combination of earthquake rates derived from static Coulomb stress change and smoothed seismicity, we mitigate the effects of stress uncertainty through increasing the influence of Coulomb stress on earthquake rates with increasing distance from faults. We also evaluate time-dependent Coulomb stress earthquake forecasts based on rate-and-state friction (Toda & Enescu, 2011 and Dieterich, 1996) against a Poissonian null hypothesis, from the 10/16/1999 Hector Mine earthquake to the 4/4/2010 El Mayor Cucapah earthquake. From numerical integration, we establish a normalized seismicity rate for each day, during the target time interval, from Coulomb stress evolution and the times since all preceding source earthquakes. During each day we assume seismicity follows a Poissonian process, with expected rates defined as the rate-and-state seismicity rates. By pseudo-prospectively testing these spatial and spatiotemporal earthquake forecasts, we ascertain the role of static and quasi-static Coulomb stress change in
Radionuclide fourier amplitude analysis to predict post-aneurysmectomy ejection fraction
McCarthy, D.M.; Kleaveland, J.P.; Makler, P.T. Jr.; Alavi, A.
1984-01-01
Post-operative LV ejection fraction (EF) is an important determinant of outcome following aneurysmectomy but is difficult to predict noninvasively. First harmonic Fourier analysis of radionuclide angiography (RNA) in patients with aneurysms gives characteristic phase and amplitude images which delineate contractile and dyskinetic regions. Since pixel amplitude is proportional to stroke counts, the summed amplitude values from the contractile region (CR) and the aneurysm should reflect regional stroke volumes. A predicted post-operative LVEF may be determined from the pre-operative global LVEF and the proportion of the total amplitude located in the CR. The authors studied 19 patients undergoing LV aneurysmectomy with pre- and post-operative RNA. Three patients were excluded for technical reasons, leaving 16 patients for analysis. There were 13 males, and the mean age was 56.8 yrs (range 45-78). All patients had a history of anterior myocardial infarction and were undergoing surgery for recurrent sustained ventricular tachycardia. The global LVEF increased from 0.25 +- .13 (sd) pre-operatively to 0.38+-.11 following surgery (p<.001). The predicted post-operative LVEF (from amplitude analysis of the pre-operative RNA) averaged 0.35 +- .13 and correlated significantly with the actual post-operative LVEf (r=0.87, SEE=.06, p<.01). The results suggest that the LVEF following aneurysmectomy can be predicted from Fourier amplitude analysis of the pre-operative RNA.
Elastic Scattering of Low Energy Pions by Nuclei and the In-Medium Isovector πN Amplitude
NASA Astrophysics Data System (ADS)
Friedman, E.; Bauer, M.; Breitschopf, J.; Clement, H.; Denz, H.; Doroshkevich, E.; Erhardt, A.; Hofman, G. J.; Kritchman, S.; Meier, R.; Wagner, G. J.; Yaari, G.
2006-07-01
Measurements of elastic scattering of 21.5 MeV π± by Si, Ca, Ni and Zr were made using a single arm magnetic spectrometer and absolute calibration was made by parallel measurements of Coulomb scattering of muons. Optical model fits to the data reveal the `anomalous' s-wave repulsion known from pionic atoms. Introducing a chiral-motivated density dependence of the isovector scattering amplitude, and considering the energy dependence of the free πN interaction greatly improve fits to the data and remove the `anomaly'.
Phase and amplitude errors in FM radars
NASA Astrophysics Data System (ADS)
Griffiths, Hugh D.
The constraints on phase and amplitude errors are determined for various types of FM radar by calculating the range sidelobe levels on the point target response due to the phase and amplitude modulation of the target echo. It is shown that under certain circumstances the constraints on phase linearity appropriate for conventional pulse compression radars are unnecessarily stringent, and quite large phase errors can be tolerated provided the relative delay of the local oscillator with respect to the target echo is small compared with the periodicity of the phase error characteristic. The constraints on amplitude flatness, however, are severe under almost all circumstances.
A link representation for gravity amplitudes
NASA Astrophysics Data System (ADS)
He, Song
2013-10-01
We derive a link representation for all tree amplitudes in supergravity, from a recent conjecture by Cachazo and Skinner. The new formula explicitly writes amplitudes as contour integrals over constrained link variables, with an integrand naturally expressed in terms of determinants, or equivalently tree diagrams. Important symmetries of the amplitude, such as supersymmetry, parity and (partial) permutation invariance, are kept manifest in the formulation. We also comment on rewriting the formula in a GL( k)-invariant manner, which may serve as a starting point for the generalization to possible Grassmannian contour integrals.
Interatomic and intermolecular Coulombic decay: the coming of age story
NASA Astrophysics Data System (ADS)
Jahnke, T.
2015-04-01
In pioneering work by Cederbaum et al an excitation mechanism was proposed that occurs only in loosely bound matter (Cederbaum et al 1997 Phys. Rev. Lett. 79 4778): it turned out, that (in particular) in cases where a local Auger decay is energetically forbidden, an excited atom or molecule is able to decay in a scheme which was termed ‘interatomic Coulombic decay’ (or ‘intermolecular Coulombic decay’) (ICD). As ICD occurs, the excitation energy is released by transferring it to an atomic or molecular neighbor of the initially excited particle. As a consequence the neighboring atom or molecule is ionized as it receives the energy. A few years later the existence of ICD was confirmed experimentally (Marburger et al 2003 Phys. Rev. Lett. 90 203401; Jahnke et al 2004 Phys. Rev. Lett. 93 163401; Öhrwall et al 2004 Phys. Rev. Lett. 93 173401) by different techniques. Since this time it has been found that ICD is not (as initially suspected) an exotic feature of van der Waals or hydrogen bonded systems, but that ICD is a very general and common feature occurring after a manifold of excitation schemes and in numerous weakly bound systems, as revealed by more than 200 publications. It was even demonstrated, that ICD can become more efficient than a local Auger decay in some system. This review will concentrate on recent experimental investigations on ICD. It will briefly introduce the phenomenon and give a short summary of the ‘early years’ of ICD (a detailed view on this episode of investigations can be found in the review article by U Hergenhahn with the same title (Hergenhahn 2011 J. Electron Spectrosc. Relat. Phenom. 184 78)). More recent articles will be presented that investigate the relevance of ICD in biological systems and possible radiation damage of such systems due to ICD. The occurrence of ICD and ICD-like processes after different excitation schemes and in different systems is covered in the middle section: in that context the helium dimer (He2
NASA Astrophysics Data System (ADS)
Cocco, M.; Hainzl, S.; Woessner, J.; Enescu, B.; Catalli, F.; Lombardi, A.
2009-12-01
It is nowadays well established that both Coulomb stress perturbations and the rate- and state-dependent frictional response of fault populations are needed to model the spatial and temporal evolution of seismicity. This represents the most popular physics-based approach to forecast the rate of earthquake production and its performances have to be verified with respect to alternative statistical methods. Despite the numerous applications of Coulomb stress interactions, a rigorous validation of the forecasting capabilities is still missing. In this work, we use the Dieterich (1994) physics-based approach to simulate the spatio-temporal evolution of seismicity caused by stress changes applied to an infinite population of nucleating patches modelled through a rate- and state-dependent friction law. According to this model, seismicity rate changes depend on the amplitude of stress perturbation, the physical constitutive properties of faults (represented by the parameter Aσ), the stressing rate and the background seismicity rate of the study area. In order to apply this model in a predictive manner, we need to understand the variability of input physical model parameters and their correlations. We first discuss the impact of uncertainties in model parameters and, in particular, in computed coseismic stress perturbations on the seismicity rate changes forecasted through the frictional model. We aim to understand how the variability of Coulomb stress changes affects the correlation between predicted and observed changes in the rate of earthquake production. We use the aftershock activity following the 1992 M 7.3 Landers (California) earthquake as one of our case studies. We analyze the variability of stress changes resulting from the use of different published slip distributions. We find that the standard deviation of the uncertainty is of the same size as the absolute stress change and that their ratio, the coefficient of variation (CV), is approximately constant in
Amplitude dynamics favors synchronization in complex networks
Gambuzza, Lucia Valentina; Gómez-Gardeñes, Jesus; Frasca, Mattia
2016-01-01
In this paper we study phase synchronization in random complex networks of coupled periodic oscillators. In particular, we show that, when amplitude dynamics is not negligible, phase synchronization may be enhanced. To illustrate this, we compare the behavior of heterogeneous units with both amplitude and phase dynamics and pure (Kuramoto) phase oscillators. We find that in small network motifs the behavior crucially depends on the topology and on the node frequency distribution. Surprisingly, the microscopic structures for which the amplitude dynamics improves synchronization are those that are statistically more abundant in random complex networks. Thus, amplitude dynamics leads to a general lowering of the synchronization threshold in arbitrary random topologies. Finally, we show that this synchronization enhancement is generic of oscillators close to Hopf bifurcations. To this aim we consider coupled FitzHugh-Nagumo units modeling neuron dynamics. PMID:27108847
Large Amplitude Oscillations of a Double Pendulum
NASA Astrophysics Data System (ADS)
Gerres, Jeffrey M.; Jacobs, Robert M.; Kasun, Sara F.; Bacon, Margaret E.; Nagolu, Chakravarthi M.; Owens, Erin L.; Siehl, Kevin F.; Thomsen, Marshall; Troyer, Jon S.
2008-03-01
The nature of the normal modes of oscillation in the small angle regime of a double pendulum is well established. However, for large amplitude oscillations, a closed form solution of the differential equations of motion does not exist. Using Lagrange formalism, we explore both the in-phase and out-of-phase normal modes of oscillation of a double pendulum as a function of the mass ratio of the two bobs and their initial angular positions. We conduct the analysis using MatLab, where we initially verify our code in the known small amplitude limit. Among our results we find that certain symmetries between the in-phase and out-of-phase normal modes that exist in the small amplitude limit are no longer present at large amplitudes.
Amplitude dynamics favors synchronization in complex networks
NASA Astrophysics Data System (ADS)
Gambuzza, Lucia Valentina; Gómez-Gardeñes, Jesus; Frasca, Mattia
2016-04-01
In this paper we study phase synchronization in random complex networks of coupled periodic oscillators. In particular, we show that, when amplitude dynamics is not negligible, phase synchronization may be enhanced. To illustrate this, we compare the behavior of heterogeneous units with both amplitude and phase dynamics and pure (Kuramoto) phase oscillators. We find that in small network motifs the behavior crucially depends on the topology and on the node frequency distribution. Surprisingly, the microscopic structures for which the amplitude dynamics improves synchronization are those that are statistically more abundant in random complex networks. Thus, amplitude dynamics leads to a general lowering of the synchronization threshold in arbitrary random topologies. Finally, we show that this synchronization enhancement is generic of oscillators close to Hopf bifurcations. To this aim we consider coupled FitzHugh-Nagumo units modeling neuron dynamics.
Maximal Values of the Auger Amplitudes and Propensity Rules for their Quantum Numbers
NASA Astrophysics Data System (ADS)
Kyiene, A.; Karazija, R.
2004-01-01
The maximal values of the Auger amplitudes corresponding to transitions of the type n1l14l1 + 1 n2l2N → n1l14l1 + 2n2l2N - 2ɛlj are investigated. It is shown that the maximal values of amplitudes vary within a relatively narrow interval and rather smoothly with N. Though the amplitude has a complicated expression for the considered transitions the quantum numbers of its maximal values obey rather general and strict propensity rules. They are also established for the quantum numbers of the initial and final states. It is shown that these rules are mainly determined by the two-electron fractional parentage coefficients. The existence of such rules indicates the additional properties of the interconfiguration matrix elements of the Coulomb interaction operator. The experimental data for the Auger spectra of atoms with closed shells confirm the validity of these rules for the determination of the most intensive line in the spectrum.
Feynman amplitudes and limits of heights
NASA Astrophysics Data System (ADS)
Amini, O.; Bloch, S. J.; Burgos Gil, J. I.; Fresán, J.
2016-10-01
We investigate from a mathematical perspective how Feynman amplitudes appear in the low-energy limit of string amplitudes. In this paper, we prove the convergence of the integrands. We derive this from results describing the asymptotic behaviour of the height pairing between degree-zero divisors, as a family of curves degenerates. These are obtained by means of the nilpotent orbit theorem in Hodge theory.
Amplitude Metrics for Cellular Circadian Bioluminescence Reporters
St. John, Peter C.; Taylor, Stephanie R.; Abel, John H.; Doyle, Francis J.
2014-01-01
Bioluminescence rhythms from cellular reporters have become the most common method used to quantify oscillations in circadian gene expression. These experimental systems can reveal phase and amplitude change resulting from circadian disturbances, and can be used in conjunction with mathematical models to lend further insight into the mechanistic basis of clock amplitude regulation. However, bioluminescence experiments track the mean output from thousands of noisy, uncoupled oscillators, obscuring the direct effect of a given stimulus on the genetic regulatory network. In many cases, it is unclear whether changes in amplitude are due to individual changes in gene expression level or to a change in coherence of the population. Although such systems can be modeled using explicit stochastic simulations, these models are computationally cumbersome and limit analytical insight into the mechanisms of amplitude change. We therefore develop theoretical and computational tools to approximate the mean expression level in large populations of noninteracting oscillators, and further define computationally efficient amplitude response calculations to describe phase-dependent amplitude change. At the single-cell level, a mechanistic nonlinear ordinary differential equation model is used to calculate the transient response of each cell to a perturbation, whereas population-level dynamics are captured by coupling this detailed model to a phase density function. Our analysis reveals that amplitude changes mediated at either the individual-cell or the population level can be distinguished in tissue-level bioluminescence data without the need for single-cell measurements. We demonstrate the effectiveness of the method by modeling experimental bioluminescence profiles of light-sensitive fibroblasts, reconciling the conclusions of two seemingly contradictory studies. This modeling framework allows a direct comparison between in vitro bioluminescence experiments and in silico ordinary
Bootstrapping One-Loop QCD Amplitudes
Berger, Carola F.; /SLAC
2006-09-08
We review the recently developed bootstrap method for the computation of high-multiplicity QCD amplitudes at one loop. We illustrate the general algorithm step by step with a six-point example. The method combines (generalized) unitarity with on-shell recursion relations to determine the not cut-constructible, rational terms of these amplitudes. Our bootstrap approach works for arbitrary configurations of gluon helicities and arbitrary numbers of external legs.
Amplitude metrics for cellular circadian bioluminescence reporters.
St John, Peter C; Taylor, Stephanie R; Abel, John H; Doyle, Francis J
2014-12-02
Bioluminescence rhythms from cellular reporters have become the most common method used to quantify oscillations in circadian gene expression. These experimental systems can reveal phase and amplitude change resulting from circadian disturbances, and can be used in conjunction with mathematical models to lend further insight into the mechanistic basis of clock amplitude regulation. However, bioluminescence experiments track the mean output from thousands of noisy, uncoupled oscillators, obscuring the direct effect of a given stimulus on the genetic regulatory network. In many cases, it is unclear whether changes in amplitude are due to individual changes in gene expression level or to a change in coherence of the population. Although such systems can be modeled using explicit stochastic simulations, these models are computationally cumbersome and limit analytical insight into the mechanisms of amplitude change. We therefore develop theoretical and computational tools to approximate the mean expression level in large populations of noninteracting oscillators, and further define computationally efficient amplitude response calculations to describe phase-dependent amplitude change. At the single-cell level, a mechanistic nonlinear ordinary differential equation model is used to calculate the transient response of each cell to a perturbation, whereas population-level dynamics are captured by coupling this detailed model to a phase density function. Our analysis reveals that amplitude changes mediated at either the individual-cell or the population level can be distinguished in tissue-level bioluminescence data without the need for single-cell measurements. We demonstrate the effectiveness of the method by modeling experimental bioluminescence profiles of light-sensitive fibroblasts, reconciling the conclusions of two seemingly contradictory studies. This modeling framework allows a direct comparison between in vitro bioluminescence experiments and in silico ordinary
Quartic Amplitudes for Minkowski Higher Spin
NASA Astrophysics Data System (ADS)
Bengtsson, Anders K. H.
The old problem of finding general quartic interaction terms between fields of higher helicities on the light-front is discussed from the point of view of calculating the corresponding amplitudes directly from the cubic vertices using BCFW recursion. Amplitude based no-go results that has appeared in the literature are reviewed and discussed and it is pointed out how they may perhaps be circumvented.
Effects of Coulomb quadrupole excitation in heavy-ion reactions
NASA Astrophysics Data System (ADS)
Cheoun, Myung-Ki; Choi, K. S.; Kim, K. S.; Kim, T. H.; So, W. Y.
2016-09-01
For 12C + 184W, 18O + 184W, and 20Ne + 208Pb systems, we investigate the suppression of the ratios P E = σ el/ σ RU by using the Coulomb quadrupole excitation (CQE) potentials. In order to explain the effect of the CQE potentials, we first use a well-known Love's CQE potential, and reproduce the experimental P E data well by using this potential. We also introduce a simple CQE potential written as W CQE( r) = - W P / r n , which is much simpler than the conventional Love's potential, to investigate the suppression of the P E ratios. Using this potential, we perform a χ2 analysis to find the adjustable parameter n, then, we find that the best fit parameters n ≈ 5 is close to the lowest order term, 1/ r 5. Consequently, we find that using the simple CQE potential explains the experimental P E data and that the ratio P E depends on the n values sensitively.
Le probleme quantique bicomplexe du potentiel de Coulomb
NASA Astrophysics Data System (ADS)
Mathieu, Jeremie
In this master's thesis, is gathered a great part of my work on bicomplex quantum mechanics. Bicomplex numbers are the second order multicomplex generalization of complex numbers. Equipped with the standard addition and multiplication, they form an algebraic structure called a commutative ring with unity and are one of many known generalizations of the real number system. It has been almost eighty years since it's been proposed to use an algebra of a superior dimension than the one of complex numbers to construct the mathematical formalism of quantum mechanics. However it's only been since less than a decade ago that the idea of using the bicomplex numbers to do so has been seriously considered. In that sense, the complete resolution of the quantum harmonic oscillator in a bicomplex Hilbert space was the first major achievement of this ambitious project. This thesis, by article style, is a continuation of this work of generalization. It presents, by an axiomatic approach, the complete differential solution of the bicomplex quantum Coulomb potential problem and half of its algebraic solution.
Coulomb drag and tunneling studies in quantum Hall bilayers
NASA Astrophysics Data System (ADS)
Nandi, Debaleena
The bilayer quantum Hall state at total filling factor νT=1, where the total electron density matches the degeneracy of the lowest Landau level, is a prominent example of Bose-Einstein condensation of excitons. A macroscopically ordered state is realized where an electron in one layer is tightly bound to a "hole" in the other layer. If exciton transport were the only bulk transportmechanism, a current driven in one layer would spontaneously generate a current of equal magnitude and opposite sign in the other layer. The Corbino Coulomb drag measurements presented in this thesis demonstrate precisely this phenomenon. Excitonic superfluidity has been long sought in the νT=1 state. The tunneling between the two electron gas layers exihibit a dc Josephson-like effect. A simple model of an over-damped voltage biased Josephson junction is in reasonable agreement with the observed tunneling I -- V. At small tunneling biases, it exhibits a tunneling "supercurrent". The dissipation is carefully studied in this tunneling "supercurrent" and found to remain small but finite.
Three-body quantum Coulomb problem: Analytic continuation
NASA Astrophysics Data System (ADS)
Turbiner, A. V.; Lopez Vieyra, J. C.; Olivares Pilón, H.
2016-08-01
The second (unphysical) critical charge in the three-body quantum Coulomb system of a nucleus of positive charge Z and mass mp, and two electrons, predicted by Stillinger has been calculated to be equal to ZB∞ = 0.904854 and ZBmp = 0.905138 for infinite and finite (proton) mass mp, respectively. It is shown that in both cases, the ground state energy E(Z) (analytically continued beyond the first critical charge Zc, for which the ionization energy vanishes, to ReZ
Synchrotron and Coulomb Boiler in Cygnus X-1
Malzac, Julien; Belmont, Renaud
2009-05-11
We use a new code to simulate the radiation and kinetic processes in the X-ray emitting region around accreting black holes and constrain the magnetic field and temperature of the hot protons in the corona of Cygnus X-1. In the hard state we find a magnetic field below equipartition with radiation, suggesting that the corona is not powered through magnetic field dissipation (as assumed in most accretion disc corona models). On the other hand, our results also point toward proton temperatures that are substantially lower than typical temperatures of the ADAF models. Finally, we show that in both spectral states Comptonising plasma could be powered essentially through power-law acceleration of non-thermal electrons, which are then partly thermalised by the synchrotron and Coulomb boiler. This suggests that, contrary to current beliefs, the corona of the HSS and that of the LHS could be of very similar nature. The differences between the LHS and HSS coronal spectra would then be predominantly caused by the strong disc soft cooling emission which is present in the HSS and absent in the LHS.
The EBIS/T as a Coulomb target for ions
NASA Astrophysics Data System (ADS)
Becker, Reinard; Kester, Oliver
2004-01-01
A partially neutralised electron beam can be considered as a well defined target of ions. Trapped in the electrostatic 3D-trap of the electron beam in an EBIS, they will—for low loss rates—acquire an energy distribution according to Boltzmanns law. The resulting spatial distribution then is well defined, once the ion temperature and the amount of ions are known. Both are related to each other by a monotone dependence, hence determination of either the ion temperature or the number of ions will give the second quantity. Such a Coulomb target provides friction to the radial movement of newly injected ions, hence can be used to facilitate the trapping of low charged injected ions (external ion source, charge breeder) or of cooling of highly charged ions (created by deceleration). Due to the well known properties of such a target, it also may be used for collision studies between trapped ions and either a beam of atoms or of additionally injected ions.
Superallowed fermi beta decay and Coulomb mixing in nuclei
Hardy, J. C.; Towner, I. S.
1999-09-02
Superallowed 0{sup +}{yields}0{sup +} nuclear beta decay provides a direct measure of the weak vector coupling constant, G{sub v}. We survey current world data on the nine accurately determined transitions of this type, which range from the decay of {sup 10}C to that of {sup 54}Co, and demonstrate that the results confirm conservation of the weak vector current (CVC) but differ at the 98% confidence level from the unitarity condition for the Cabibbo-Kobayashi-Maskawa (CKM) matrix. We examine the reliability of the small calculated corrections that have been applied to the data, and conclude that there are no evident defects although the Coulomb correction, {delta}{sub C}, depends sensitively on nuclear structure and thus needs to be constrained independently. The potential importance of a result in disagreement with unitarity, clearly indicates the need for further work to confirm or deny the discrepancy. We examine the options and recommend priorities for new experiments and improved calculations. Some of the required experiments depend upon the availability of intense radioactive beams. Others are possible with existing facilities. (c) 1999 American Institute of Physics.
Coulomb Excitation of Radioactive Mo-Ru Isotopes
NASA Astrophysics Data System (ADS)
Allmond, J. M.; Gretina-Chico2 Collaboration
2016-09-01
The study of shapes in atomic nuclei has been a major focus of nuclear structure ever since the observation of large electric quadrupole moments in the first half of the 20th century. A leading challenge has been to experimentally establish regions of oblate deformation, which are very limited, and triaxial deformation. The neutron-rich Mo-Ru region is expected to exhibit triaxial deformation in the low-lying states, mediated by a relatively rare instance of prolate-to-oblate shape evolution. A survey of equipment, techniques, and preliminary results from recent Coulomb-excitation and beta-decay experiments in the neutron-rich Mo-Ru region will be presented. These experiments were conducted at the CARIBU-ANL facility using GRETINA-CHICO2. An emphasis will be placed on unique opportunities with 3-MeV/u beams. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics.
The onset of coulomb explosions in polyatomic molecules
Smith; Ledingham; Singhal; McCanny; Graham; Kilic; Tzallas; Kosmidis; Langley; Taday
1999-01-01
With the development of high intensity femtosecond lasers, the ionisation and dissociation dynamics of molecules has become an area of considerable interest. Using the technique of femtosecond laser mass spectrometry (FLMS), the molecules carbon disulphide, pyrimidine, toluene, cyclohexanone and benzaldehyde are studied with pulse widths of 50 fs in the near infrared (IR) wavelength region (790 nm). Results are presented and contrasted for laser beam intensities around 10(15) and 10(16) W cm(-2). For the lower intensities, the mass spectra yield dominant singly charged parent ions. Additionally, the appearance of doubly charged parent ions is evident for carbon disulphide, toluene and benzaldehyde with envelopes of doubly charged satellite species existing in these local regions. Carbon disulphide also reveals a small triply charged component. Such atomic-like features are thought to be a strong fingerprint of FLMS at these intensities. However, upon increasing the laser intensity to approximately 10(16) W cm(-2), parent ion dominance decreases and the appearance of multiply charged atomic species occurs, particularly carbon. This phenomenon has been attributed to Coulomb explosions in which the fast absorption of many photons may produce transient highly ionised parent species which can subsequently blow apart. Copyright 1999 John Wiley & Sons, Ltd.
Dark Coulomb binding of heavy neutrinos of fourth family
NASA Astrophysics Data System (ADS)
Belotsky, K. M.; Esipova, E. A.; Khlopov, M. Yu.; Laletin, M. N.
2015-11-01
Direct dark matter searches put severe constraints on the weakly interacting massive particles (WIMPs). These constraints cause serious troubles for the model of stable neutrino of fourth generation with mass around 50GeV. Though the calculations of primordial abundance of these particles make them in the charge symmetric case a sparse subdominant component of the modern dark matter, their presence in the universe would exceed the current upper limits by several orders of the magnitude. However, if quarks and leptons of fourth generation possess their own Coulomb-like y-interaction, recombination of pairs of heavy neutrinos and antineutrinos and their annihilation in the “neutrinium” atoms can play important role in their cosmological evolution, reducing their modern abundance far below the experimental upper limits. The model of stable fourth generation assumes that the dominant part of dark matter is explained by excessive Ū antiquarks, forming (ŪŪŪ)-- charged clusters, bound with primordial helium in nuclear-interacting O-helium (OHe) dark atoms. The y charge conservation implies generation of the same excess of fourth generation neutrinos, potentially dangerous WIMP component of this scenario. We show that due to y-interaction recombination of fourth neutrinos with OHe hides these WIMPs from direct WIMP searches, leaving the negligible fraction of free neutrinos, what makes their existence compatible with the experimental constraints.
A new graphene composite with a high coulombic efficiency
NASA Astrophysics Data System (ADS)
Protich, Z.; Wong, P.; Santhanam, K. S. V.
2016-11-01
Zinc-graphene composite has been electrolytically produced for the first time using a graphene quantum dot (GQD) electrode. The electrochemical reduction of zinc ion at a GQD electrode is shifted to a lesser negative potential with the complimentary anodic peak due to the oxidation of the composite shifted towards a positive potential as compared to zinc ion reduction in the GQD bath. The coulombic efficiency of the composite represents a gain of nearly 10% over the conventional Zn/Zn2+ in the energy storage systems. In galvanostatic electrolysis, the deposition of zinc-graphene composite is carried out under neutral and acidic conditions. The X-ray diffraction of the electrolytically prepared composite shows distinct features of 2 theta reflection at 8° due to (001) plane of graphene, in addition to the characteristic reflections at 38.9°,43.2°, 54.3°, 70.1° and 90° arising from Zn at (002), (100), (101), (102) and (110). A large scale preparation of the zinc-graphene composite has been achieved at a zinc plate as the working electrode in the GQD bath. The composite is stable up to 250 °C. Scanning electron microscopic (SEM) and energy dispersion X-ray analysis (EDAX) shows a string like structure with peaks for carbon and zinc in EDAX.
Twistor-strings and gravity tree amplitudes
NASA Astrophysics Data System (ADS)
Adamo, Tim; Mason, Lionel
2013-04-01
Recently we discussed how Einstein supergravity tree amplitudes might be obtained from the original Witten and Berkovits twistor-string theory when external conformal gravitons are restricted to be Einstein gravitons. Here we obtain a more systematic understanding of the relationship between conformal and Einstein gravity amplitudes in that twistor-string theory. We show that although it does not in general yield Einstein amplitudes, we can nevertheless obtain some partial twistor-string interpretation of the remarkable formulae recently been found by Hodges and generalized to all tree amplitudes by Cachazo and Skinner. The Hodges matrix and its higher degree generalizations encode the world sheet correlators of the twistor string. These matrices control both Einstein amplitudes and those of the conformal gravity arising from the Witten and Berkovits twistor-string. Amplitudes in the latter case arise from products of the diagonal elements of the generalized Hodges matrices and reduced determinants give the former. The reduced determinants arise if the contractions in the worldsheet correlator are restricted to form connected trees at MHV. The (generalized) Hodges matrices arise as weighted Laplacian matrices for the graph of possible contractions in the correlators and the reduced determinants of these weighted Laplacian matrices give the sum of the connected tree contributions by an extension of the matrix-tree theorem.
Liquid-gas phase transitions in a multicomponent nuclear system with Coulomb and surface effects
Lee, S. J.; Mekjian, A. Z.
2001-04-01
The liquid-gas phase transition is studied in a multicomponent nuclear system using a local Skyrme interaction with Coulomb and surface effects. Some features are qualitatively the same as the results of Mu''ller and Serot where a relativistic mean field was used without Coulomb and surface effects. Surface tension brings the coexistence binodal surface to lower pressure. The Coulomb interaction makes the binodal surface smaller and causes another pair of binodal points at low pressure and large proton fraction with fewer protons in the liquid phase and more protons in the gas phase.
Coulomb impurity effects on the zero-Landau level splitting of graphene on polar substrates
NASA Astrophysics Data System (ADS)
Xiao, Yao; Li, Wei-Ping; Li, Zhi-Qing; Wang, Zi-Wu
2017-04-01
We theoretically investigate the effects of the Coulomb impurity on the zero-Landau level splitting of graphene on different polar substrates basing on the Fröhlich polaron model, in which the polaron is formed due to the carriers-surface optical phonon coupling. We discuss the influence of Coulomb impurity on the zero-Landau level splitting in the case of weak and strong coupling limits. We find that the splitting energy can be varied in a large scale due to the Coulomb impurity, which provides the possible theoretical explanation for the experimental measurements regarding the energy gap opened and zero-Landau level splitting in Landau quantized graphene.
Large ion Coulomb crystals: A near-ideal medium for coupling optical cavity modes to matter
Dantan, A.; Albert, M.; Marler, J. P.; Herskind, P. F.; Drewsen, M.
2009-10-15
We present an investigation of the coherent coupling of various transverse field modes of an optical cavity to ion Coulomb crystals. The obtained experimental results, which include the demonstration of identical collective coupling rates for different transverse modes of a cavity field to ions in the same large Coulomb crystal, are in excellent agreement with theoretical predictions. The results furthermore suggest that Coulomb crystals in the future may serve as near-ideal media for high-fidelity multimode quantum information processing and communication purposes, including the generation and storage of single-photon qubits encoded in different transverse modes.
Analytical expressions for partial wave two-body Coulomb transition matrices at ground-state energy
NASA Astrophysics Data System (ADS)
Kharchenko, V. F.
2016-11-01
Leaning upon the Fock method of the stereographic projection of the three-dimensional momentum space onto the four-dimensional unit sphere the possibility of the analytical solving of the Lippmann-Schwinger integral equation for the partial wave two-body Coulomb transition matrix at the ground bound state energy has been studied. In this case new expressions for the partial p-, d- and f-wave two-body Coulomb transition matrices have been obtained in the simple analytical form. The developed approach can also be extended to determine analytically the partial wave Coulomb transition matrices at the energies of excited bound states.
Coulomb-nuclear interference in 56 MeV deuteron breakup at extreme forward angle
NASA Astrophysics Data System (ADS)
Samanta, C.; Kanungo, Rituparna; Mukherjee, Sanjukta; Basu, D. N.
1995-02-01
Recently measured 12C(d,pn) 12C breakup data show a dip in the energy integrated cross section below a momentum transfer ∼ 117 MeV/ c. We analyse these data by the prior form distorted-wave Born approximation theory. Although the double humped structure of the θp = θn = 0° data exhibit the dominance of Coulomb-breakup, the pronounced asymmetry of the energy sharing data cannot be explained through Coulomb breakup only. A closer agreement to the data is obtained through Coulomb-nuclear interference and an unusual optical potential of longer range in the exit channel.
The Phase-Amplitude (PhA) representation of a wave function
NASA Astrophysics Data System (ADS)
Rawitscher, George
2017-01-01
The PhA representation of an oscillatory wave function is ψ(r) = y sin(ϕ) , where y(r) is the amplitude and ϕ(r) the phase. Since these quantities depend on distance r slowly and generally monotonically, they can be calculated numerically out to large distances with a relatively small number of mesh-points. A linear equation for y2 exists that has been overlooked in the past. The advantage of this equation is that it avoids the non-linearity difficulties encountered with the equation for y given In 1930 W. E. Milne. This equation will be shown and a solution method will be described, that uses expansions into Laguerre polynomials. A numerical example for the Coulomb potential will be presented, including the region of turning points.
Amplitude Modulations of Acoustic Communication Signals
NASA Astrophysics Data System (ADS)
Turesson, Hjalmar K.
2011-12-01
In human speech, amplitude modulations at 3 -- 8 Hz are important for discrimination and detection. Two different neurophysiological theories have been proposed to explain this effect. The first theory proposes that, as a consequence of neocortical synaptic dynamics, signals that are amplitude modulated at 3 -- 8 Hz are propagated better than un-modulated signals, or signals modulated above 8 Hz. This suggests that neural activity elicited by vocalizations modulated at 3 -- 8 Hz is optimally transmitted, and the vocalizations better discriminated and detected. The second theory proposes that 3 -- 8 Hz amplitude modulations interact with spontaneous neocortical oscillations. Specifically, vocalizations modulated at 3 -- 8 Hz entrain local populations of neurons, which in turn, modulate the amplitude of high frequency gamma oscillations. This suggests that vocalizations modulated at 3 -- 8 Hz should induce stronger cross-frequency coupling. Similar to human speech, we found that macaque monkey vocalizations also are amplitude modulated between 3 and 8 Hz. Humans and macaque monkeys share similarities in vocal production, implying that the auditory systems subserving perception of acoustic communication signals also share similarities. Based on the similarities between human speech and macaque monkey vocalizations, we addressed how amplitude modulated vocalizations are processed in the auditory cortex of macaque monkeys, and what behavioral relevance modulations may have. Recording single neuron activity, as well as, the activity of local populations of neurons allowed us to test both of the neurophysiological theories presented above. We found that single neuron responses to vocalizations amplitude modulated at 3 -- 8 Hz resulted in better stimulus discrimination than vocalizations lacking 3 -- 8 Hz modulations, and that the effect most likely was mediated by synaptic dynamics. In contrast, we failed to find support for the oscillation-based model proposing a
Mathematically modelling proportions of Japanese populations by industry
NASA Astrophysics Data System (ADS)
Hirata, Yoshito
2016-10-01
I propose a mathematical model for temporal changes of proportions for industrial sectors. I prove that the model keeps the proportions for the primary, the secondary, and the tertiary sectors between 0 and 100% and preserves their total as 100%. The model fits the Japanese historical data between 1950 and 2005 for the population proportions by industry very well. The model also predicts that the proportion for the secondary industry becomes negligible and becomes less than 1% at least around 2080.
Elastic scattering of low energy pions by nuclei and the in-medium isovector πN amplitude
NASA Astrophysics Data System (ADS)
Friedman, E.; Bauer, M.; Breitschopf, J.; Clement, H.; Denz, H.; Doroshkevich, E.; Erhardt, A.; Hofman, G. J.; Kritchman, S.; Meier, R.; Wagner, G. J.; Yaari, G.
2005-09-01
Measurements of elastic scattering of 21.5 MeV π± by Si, Ca, Ni, and Zr were made by using a single-arm magnetic spectrometer. Absolute calibration was made by parallel measurements of Coulomb scattering of muons. Parameters of a pion-nucleus optical potential were obtained from fits to all eight angular distributions put together. The anomalous s-wave repulsion known from pionic atoms is clearly observed and could be removed by introducing a chiral-motivated density dependence of the isovector scattering amplitude, which also greatly improved the fits to the data. The empirical energy dependence of the isoscalar amplitude also improves the fits to the data but, contrary to what is found with pionic atoms, on its own is incapable of removing the anomaly.
Proportion in Middle-School Mathematics: It's Everywhere
ERIC Educational Resources Information Center
Shield, Mal; Dole, Shelley
2008-01-01
Proportional thinking is the mathematical basis of a wide range of topics in the middle-school mathematics curriculum. While the concept is obvious in the traditionally-named ratio and proportion sections, proportional thinking is also the key to such diverse topics as rate, gradient of a linear function, similarity, trigonometry and percentage,…
Spatial Proportional Reasoning Is Associated with Formal Knowledge about Fractions
ERIC Educational Resources Information Center
Möhring, Wenke; Newcombe, Nora S.; Levine, Susan C.; Frick, Andrea
2016-01-01
Proportional reasoning involves thinking about parts and wholes (i.e., about fractional quantities). Yet, research on proportional reasoning and fraction learning has proceeded separately. This study assessed proportional reasoning and formal fraction knowledge in 8- to 10-year-olds. Participants (N = 52) saw combinations of cherry juice and water…
Evaluation of facial divine proportion in North Indian Population
Khan, Naseem Ahmad; Nagar, Amit; Tandon, Pradeep; Singh, Gulshan Kumar; Singh, Alka
2016-01-01
Objective: To evaluate the facial divine proportion and its relationship with facial attractiveness in North Indian population. Materials and Methods: For evaluation of various facial proportions, standardized frontal facial photographs of total 300 subjects between 18 and 30 years of age were obtained. Black and white copies of these photographs were presented in front of an evaluation jury for assigning scores of facial attractiveness and finally 130 attractive subjects were selected. These subjects were divided into two groups, Group I (attractive females n = 65) and Group II (attractive males n = 65) and they were further analyzed for various parameters of facial proportions. Unpaired Student's t-test was used to compare both groups. Results: Group I showed that five of seven vertical facial proportions were close to divine proportion (1.618) whereas only two vertical proportions in Group II were close to it. Transverse facial proportions in both groups deviated more from divine proportion (1.618) and were closer to silver proportion (1.414). Conclusions: Most of the facial proportions of attractive females in the North-Indian population were close to the divine proportion. Thus, facial divine proportion could be an important factor in the perception of facial attractiveness of North-Indian attractive females. PMID:27630502
Solution of two-body relativistic bound state equations with confining plus Coulomb interactions
NASA Technical Reports Server (NTRS)
Maung, Khin Maung; Kahana, David E.; Norbury, John W.
1992-01-01
Studies of meson spectroscopy have often employed a nonrelativistic Coulomb plus Linear Confining potential in position space. However, because the quarks in mesons move at an appreciable fraction of the speed of light, it is necessary to use a relativistic treatment of the bound state problem. Such a treatment is most easily carried out in momentum space. However, the position space Linear and Coulomb potentials lead to singular kernels in momentum space. Using a subtraction procedure we show how to remove these singularities exactly and thereby solve the Schroedinger equation in momentum space for all partial waves. Furthermore, we generalize the Linear and Coulomb potentials to relativistic kernels in four dimensional momentum space. Again we use a subtraction procedure to remove the relativistic singularities exactly for all partial waves. This enables us to solve three dimensional reductions of the Bethe-Salpeter equation. We solve six such equations for Coulomb plus Confining interactions for all partial waves.
Last, Isidore; Levy, Yaakov; Jortner, Joshua
2002-07-09
We address the stability of multicharged finite systems driven by Coulomb forces beyond the Rayleigh instability limit. Our exploration of the nuclear dynamics of heavily charged Morse clusters enabled us to vary the range of the pair potential and of the fissibility parameter, which results in distinct fragmentation patterns and in the angular distributions of the fragments. The Rayleigh instability limit separates between nearly binary (or tertiary) spatially unisotropic fission and spatially isotropic Coulomb explosion into a large number of small, ionic fragments. Implications are addressed for a broad spectrum of dynamics in chemical physics, radiation physics of ultracold gases, and biophysics, involving the fission of clusters and droplets, the realization of Coulomb explosion of molecular clusters, the isotropic expansion of optical molasses, and the Coulomb instability of "isolated" proteins.
Liu Jianye; Guo Wenjun; Gao Yuanyi; Xing Yongzhong; Li Xiguo
2004-09-01
We investigate separately the isospin effects of Coulomb interaction and symmetry potential on the dissipation and fragmentation in the intermediate energy heavy ion collisions by using isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces the reductions of both isospin fractionation ratio and nuclear stopping (momentum dissipation). However, the Coulomb interaction not only does not change obviously the strong isospin effect of the symmetry potential on the isospin fractionation ratio but also does not change obviously that of in-medium two-body collision on the nuclear stopping. On the contrary, the symmetry potential induces the enhancement of the isospin fractionation ratio but it is insensitive to the nuclear stopping. Finally, the competition between the Coulomb interaction and symmetry potential induces the reductions of both isospin fractionation ratio and nuclear stopping for two forms of symmetry potentials in this paper.
NASA Astrophysics Data System (ADS)
Hakobyan, Tigran; Nersessian, Armen; Shmavonyan, Hovhannes
2017-01-01
We propose a unified description for the constants of motion for superintegrable deformations of the oscillator and Coulomb systems on N -dimensional Euclidean space, sphere, and hyperboloid. We also consider the duality between these generalized systems and present some examples.
Capri, M.A.L. . E-mail: marcio@dft.if.uerj.br; Sobreiro, R.F. . E-mail: sobreiro@uerj.br; Sorella, S.P. . E-mail: sorella@uerj.br; Thibes, R. . E-mail: thibes@dft.if.uerj.br
2007-08-15
A detailed discussion of the renormalization properties of a class of gauges which interpolates among the Landau, Coulomb and maximal Abelian gauges is provided in the framework of the algebraic renormalization in Euclidean Yang-Mills theories in four dimensions.
Cold chemistry with electronically excited Ca{sup +} Coulomb crystals
Gingell, Alexander D.; Bell, Martin T.; Oldham, James M.; Softley, Timothy P.; Harvey, Jeremy N.
2010-11-21
Rate constants for chemical reactions of laser-cooled Ca{sup +} ions and neutral polar molecules (CH{sub 3}F, CH{sub 2}F{sub 2}, or CH{sub 3}Cl) have been measured at low collision energies (
A mechanical connector design for high-current, high-coulomb pulsed power systems
Susoeff, A.R.; Hawke, R.S.; Leighton, K.S.
1992-02-25
A technique to make reliable high-current, high-coulomb electrical contact was developed for transmitting power into railguns. The method uses spring loaded removable connectors that are installed independently from the launcher. The simple rod-type design and absence of fastener holes allow maximum utilization of material mechanical properties. Repeated experiments with 9.5-mm diameter connectors demonstrated reliable pulsed charge transfer of 200 coulombs at currents of over 400kA. 20 refs.
Violation of detailed balance for charge-transfer statistics in Coulomb-blockade systems
NASA Astrophysics Data System (ADS)
Stegmann, Philipp; König, Jürgen
2017-03-01
We discuss the possibility to generate in Coulomb-blockade systems steady states that violate detailed balance. This includes both voltage biased and non-biased scenarios. The violation of detailed balance yields that the charge-transfer statistics for electrons tunneling into an island experiencing strong Coulomb interaction is different from the statistics for tunneling out. This can be experimentally tested by time-resolved measurement of the island's charge state. We demonstrate this claim for two model systems.
Solutions to the 1d Klein Gordon equation with cut-off Coulomb potentials
NASA Astrophysics Data System (ADS)
Hall, Richard L.
2007-12-01
In a recent paper by Barton [G. Barton, J. Phys. A: Math. Gen. 40 (2007) 1011], the 1-dimensional Klein Gordon equation was solved analytically for the non-singular Coulomb-like potential V(|x|)=-α/(|x|+a). In the present Letter, these results are completely confirmed by a numerical formulation that also allows a solution for an alternative cut-off Coulomb potential V(|x|)=-α/|x|, |x|>a, and otherwise V(|x|)=-α/a.
Ion Coulomb crystals: from quantum technology to chemistry close to the absolute zero point
NASA Astrophysics Data System (ADS)
Dulieu, O.; Willitsch, S.
2017-03-01
Ion Coulomb crystals are ordered structures of atomic or molecular ions stored in ion traps at temperatures close to the absolute zero point. These unusual "crystals" form the basis of extremely accurate clocks, provide an environment for precise studies of chemical reactions and enable advanced implementations of the technology for a quantum computer. In this article, we discuss the techniques for generating atomic and molecular Coulomb crystals and highlight some of their applications.
Three-Body Wave Functions in the Continuum: Application to the Repulsive Coulomb Case
NASA Astrophysics Data System (ADS)
Garrido, E.; Kievsky, A.; Viviani, M.
2017-03-01
In this work we describe a method that permits to obtain full three-body continuum wave functions regardless the short- or long-range character of the two-body potentials involved. Within this method all the possible incoming channels are automatically taken into account. When applied to systems where only the repulsive Coulomb interaction enters the method provides the corresponding regular three-body Coulomb functions, from which their irregular partners can be obtained.
Perturbed Coulomb potentials in the Klein-Gordon equation via the asymptotic iteration method
Barakat, T.
2009-03-15
The asymptotic iteration method is used to construct the exact energy eigenvalues for a Lorentz vector or a Lorentz scalar, and an equally mixed Lorentz vector and Lorentz scalar Coulombic potentials. Highly accurate and rapidly converging ground-state energies for Lorentz vector Coulomb with a Lorentz vector or a Lorentz scalar linear potential, V(r)=-{lambda}{sub 1}/r+krandV(r)=-{lambda}{sub 1}/randW(r)=kr, respectively, are obtained.
As-built design specification for proportion estimate software subsystem
NASA Technical Reports Server (NTRS)
Obrien, S. (Principal Investigator)
1980-01-01
The Proportion Estimate Processor evaluates four estimation techniques in order to get an improved estimate of the proportion of a scene that is planted in a selected crop. The four techniques to be evaluated were provided by the techniques development section and are: (1) random sampling; (2) proportional allocation, relative count estimate; (3) proportional allocation, Bayesian estimate; and (4) sequential Bayesian allocation. The user is given two options for computation of the estimated mean square error. These are referred to as the cluster calculation option and the segment calculation option. The software for the Proportion Estimate Processor is operational on the IBM 3031 computer.
Strong-field ionization via a high-order Coulomb-corrected strong-field approximation
NASA Astrophysics Data System (ADS)
Klaiber, Michael; Daněk, Jiří; Yakaboylu, Enderalp; Hatsagortsyan, Karen Z.; Keitel, Christoph H.
2017-02-01
Signatures of the Coulomb corrections in the photoelectron momentum distribution during laser-induced ionization of atoms or ions in tunneling and multiphoton regimes are investigated analytically in the case of a one-dimensional problem. A high-order Coulomb-corrected strong-field approximation is applied, where the exact continuum state in the S matrix is approximated by the eikonal Coulomb-Volkov state including the second-order corrections to the eikonal. Although without high-order corrections our theory coincides with the known analytical R -matrix (ARM) theory, we propose a simplified procedure for the matrix element derivation. Rather than matching the eikonal Coulomb-Volkov wave function with the bound state as in the ARM theory to remove the Coulomb singularity, we calculate the matrix element via the saddle-point integration method by time as well as by coordinate, and in this way avoiding the Coulomb singularity. The momentum shift in the photoelectron momentum distribution with respect to the ARM theory due to high-order corrections is analyzed for tunneling and multiphoton regimes. The relation of the quantum corrections to the tunneling delay time is discussed.
Comparing Mohr Coulomb and Drucker Prager function in three dimensional analysis on rock
NASA Astrophysics Data System (ADS)
Okay Aksoy, C.; Safak, Suleyman
2010-05-01
Rapid development is happening in the solution of engineering problems in recent years. The most important of all, develops in the area of computer software with no doubt. There are many programs that are finite element, finite different boundary element based. Some of these programmes use the Mohr-Coulomb failure criterion for the purpose of mining problems. This function is not very suitable in the solution of three dimension elasto-plastic problems. Mohr-Coulomb and Drucker-Prager functions are defined in a very similar manner. However, Mohr-Coulomb elastic-plastic model does not represent hardening behavior exhibited by most geologic materials and no yield under stress. On the other hand, Drucker-Prager plasticity model is an approximation of the Mohr-Coulomb failure criterion. Both, Mohr-Coulumb and Drucker-Prager fonctions have been analyzed with Gauss Elimination Method and Newton-Raphson Method, respectively and clearer results can be obtained by adopting the Drucker-Prager function to the Mohr-Coulomb function. Keywords: Drucker-Prager, Mohr-Coulomb, Rock Mechanics.
Coulomb-tail effect of electron-electron interaction on nonsequential double ionization
NASA Astrophysics Data System (ADS)
Zhou, Yueming; Huang, Cheng; Lu, Peixiang
2011-08-01
With the classical ensemble model, we investigate the manifestations of the Coulomb tail of electron-electron interaction in nonsequential double ionization by comparing the results from the short-range electron-electron interaction with those from the Coulombic electron-electron interaction. At the intensity below the recollision threshold, the two-electron momentum distributions in the direction parallel to the laser polarization show an anticorrelated behavior for the Coulombic electron-electron interaction while a correlated behavior for the short-range interaction, which indicates the responsibility of the Coulomb tail of the electron-electron interaction for the experimentally observed anticorrelated emission [Y. Liu, S. Tschuch, A. Rudenko, M. Durr, M. Siegel, U. Morgner, R. Moshammer, and J. Ullrich, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.101.053001 101, 053001 (2008)]. In the transverse direction, for the Coulombic electron-electron interaction, the two electrons exhibit no effect of repulsion at an intensity below the recollision threshold while a strong repulsion effect at an intensity above the threshold, which becomes weaker as the laser intensity further increases. Back analysis shows that the role of the Coulomb tail of electron-electron interaction leads asymmetric energy sharing (AES) to be prevalent at recollision. This AES results in the two electrons leaving the ion at different times or with different initial momenta, which is responsible for the anticorrelated behavior in the parallel direction and the intensity-dependent repulsion effect in the transverse direction.
Coulomb-tail effect of electron-electron interaction on nonsequential double ionization
Zhou Yueming; Huang Cheng; Lu Peixiang
2011-08-15
With the classical ensemble model, we investigate the manifestations of the Coulomb tail of electron-electron interaction in nonsequential double ionization by comparing the results from the short-range electron-electron interaction with those from the Coulombic electron-electron interaction. At the intensity below the recollision threshold, the two-electron momentum distributions in the direction parallel to the laser polarization show an anticorrelated behavior for the Coulombic electron-electron interaction while a correlated behavior for the short-range interaction, which indicates the responsibility of the Coulomb tail of the electron-electron interaction for the experimentally observed anticorrelated emission [Y. Liu, S. Tschuch, A. Rudenko, M. Durr, M. Siegel, U. Morgner, R. Moshammer, and J. Ullrich, Phys. Rev. Lett. 101, 053001 (2008)]. In the transverse direction, for the Coulombic electron-electron interaction, the two electrons exhibit no effect of repulsion at an intensity below the recollision threshold while a strong repulsion effect at an intensity above the threshold, which becomes weaker as the laser intensity further increases. Back analysis shows that the role of the Coulomb tail of electron-electron interaction leads asymmetric energy sharing (AES) to be prevalent at recollision. This AES results in the two electrons leaving the ion at different times or with different initial momenta, which is responsible for the anticorrelated behavior in the parallel direction and the intensity-dependent repulsion effect in the transverse direction.
The effect of Coulomb interactions on thermoelectric properties of quantum dots
NASA Astrophysics Data System (ADS)
Zimbovskaya, Natalya; Kuzmin, Valery
2014-03-01
Thermoelectric effects in a quantum dot coupled to the source and drain charge reservoirs are explored using a nonequilibrium Green's functions formalism beyond the Hartree-Fock approxomation. We concentrate on theoretical analysis of the influence of Coulomb interactions on thermopower and the figure of merit ZT . Obtained results show that Coulomb interactions between charge carriers on the dot significantly contribute to its thermoelectric properties. In the present work, we trace the transition from the Coulomb blockade regime to Kondo regime in the thermoelectric properties of the quantum dot which occurs when we gradually strengthen the coupling of the dot to the charge reservoirs. We show that within the Coulomb blockade regime (when the coupling of the dot to the leads is weak compared to the characteristic strength of the charge carriers interactions) thermoelectric characteristics of the dot display distinct features caused by Coulomb interactions. These features indicate possibilities of enhancement of thermoelectric efficiency of the considered systems. Within the Kondo regime, when the couplings of the dot to the leads became stronger, the influence of Coulomb interactions declines bringing a decrease in the the thermoelectric efficiency.
Periodic amplitude variations in Jovian continuum radiation
NASA Technical Reports Server (NTRS)
Kurth, W. S.; Gurnett, D. A.; Scarf, F. L.
1986-01-01
An analysis of periodic variations in the amplitude of continuum radiation near 3 kHz trapped in the Jovian magnetosphere shows structure with periods near both five and ten hours. Contrary to a plausible initial idea, the continuum amplitudes are not organized by position of the observer relative to the dense plasma sheet. Instead, there seem to be preferred orientations of system III longitude with respect to the direction to the sun which account for the peaks. This implies a clock-like modulation of the continuum radiation intensity as opposed to a searchlight effect. The importance of the dipole longitude-solar wind alignment to the amplitude of the continuum radiation implies the source region of the radiation is near the magnetopause and may indirectly tie the generation of the radio waves to the clocklike modulation of energetic electron fluxes from Jupiter.
Cut-constructible part of QCD amplitudes
Britto, Ruth; Feng Bo; Mastrolia, Pierpaolo
2006-05-15
Unitarity cuts are widely used in analytic computation of loop amplitudes in gauge theories such as QCD. We expand upon the technique introduced in hep-ph/0503132 to carry out any finite unitarity cut integral. This technique naturally separates the contributions of bubble, triangle and box integrals in one-loop amplitudes and is not constrained to any particular helicity configurations. Loop momentum integration is reduced to a sequence of algebraic operations. We discuss the extraction of the residues at higher-order poles. Additionally, we offer concise algebraic formulas for expressing coefficients of three-mass triangle integrals. As an application, we compute all remaining coefficients of bubble and triangle integrals for nonsupersymmetric six-gluon amplitudes.
Analytic representations of Yang-Mills amplitudes
NASA Astrophysics Data System (ADS)
Bjerrum-Bohr, N. E. J.; Bourjaily, Jacob L.; Damgaard, Poul H.; Feng, Bo
2016-12-01
Scattering amplitudes in Yang-Mills theory can be represented in the formalism of Cachazo, He and Yuan (CHY) as integrals over an auxiliary projective space-fully localized on the support of the scattering equations. Because solving the scattering equations is difficult and summing over the solutions algebraically complex, a method of directly integrating the terms that appear in this representation has long been sought. We solve this important open problem by first rewriting the terms in a manifestly Möbius-invariant form and then using monodromy relations (inspired by analogy to string theory) to decompose terms into those for which combinatorial rules of integration are known. The result is the foundations of a systematic procedure to obtain analytic, covariant forms of Yang-Mills tree-amplitudes for any number of external legs and in any number of dimensions. As examples, we provide compact analytic expressions for amplitudes involving up to six gluons of arbitrary helicities.
A description of seismic amplitude techniques
NASA Astrophysics Data System (ADS)
Shadlow, James
2014-02-01
The acquisition of seismic data is a non-invasive technique used for determining the sub surface geology. Changes in lithology and fluid fill affect the seismic wavelet. Analysing seismic data for direct hydrocarbon indicators (DHIs), such as full stack amplitude anomalies, or amplitude variation with offset (AVO), can help a seismic interpreter relate the geophysical response to real geology and, more importantly, to distinguish the presence of hydrocarbons. Inversion is another commonly used technique that attempts to tie the seismic data back to the geology. Much has been written about these techniques, and attempting to gain an understanding on the theory and application of them by reading through various journals can be quite daunting. The purpose of this paper is to briefly outline DHI analysis, including full stack amplitude anomalies, AVO and inversion and show the relationship between all three. The equations presented have been included for completeness, but the reader can pass over the mathematical detail.
ERIC Educational Resources Information Center
De Bock, Dirk; Van Dooren, Wim; Verschaffel, Lieven
2015-01-01
We investigated students' understanding of proportional, inverse proportional, and affine functions and the way this understanding is affected by various external representations. In a first study, we focus on students' ability to model textual descriptions of situations with different kinds of representations of proportional, inverse…
Estimating sighting proportions of American alligator nests during helicopter survey
Rice, Kenneth G.; Percival, H. Franklin; Woodward, Allan R.
2000-01-01
Proportions of American alligator (Alligator mississippiensis) nests sighted during aerial survey in Florida were estimated based upon multiple surveys by different observers. We compared sighting proportions across habitats, nesting seasons, and observer experience levels. The mean sighting proportion across all habitats and years was 0.736 (SE=0.024). Survey counts corrected by the mean sighting proportion reliably predicted total nest counts (7?2=0.933). Sighting proportions did not differ by habitat type (P=0.668) or year P=0.328). Experienced observers detected a greater proportion of nests (P<0.0001) than did either less experienced or inexperienced observers. Reliable estimates of nest abundance can be derived from aerial counts of alligator nests when corrected by the appropriate sighting proportion.
Modified π π amplitude with σ pole
NASA Astrophysics Data System (ADS)
Bydžovský, P.; Kamiński, R.; Nazari, V.
2014-12-01
A set of well-known once subtracted dispersion relations with imposed crossing symmetry condition is used to modify unitary multichannel S (π π , K K ¯, and η η ) and P (π π , ρ 2 π , and ρ σ ) wave amplitudes mostly below 1 GeV. Before the modifications, these amplitudes significantly did not satisfy the crossing symmetry condition and did not describe the π π threshold region. Moreover, the pole of the S wave amplitude related with the f0(500 ) meson (former f0(600 ) or σ ) had much smaller imaginary part and bigger real one in comparison with those in the newest Particle Data Group Tables. Here, these amplitudes are supplemented by near threshold expansion polynomials and refitted to the experimental data in the effective two pion mass from the threshold to 1.8 GeV and to the dispersion relations up to 1.1 GeV. In result the self consistent, i.e., unitary and fulfilling the crossing symmetry condition, S and P wave amplitudes are formed and the σ pole becomes much narrower and lighter. To eliminate doubts about the uniqueness of the so obtained sigma pole position short and purely mathematical proof of the uniqueness of the results is also presented. This analysis is addressed to a wide group of physicists and aims at providing a very effective and easy method of modification of, many presently used, π π amplitudes with a heavy and broad σ meson without changing of their original mathematical structure.
Singularity structure of maximally supersymmetric scattering amplitudes.
Arkani-Hamed, Nima; Bourjaily, Jacob L; Cachazo, Freddy; Trnka, Jaroslav
2014-12-31
We present evidence that loop amplitudes in maximally supersymmetric (N=4) Yang-Mills theory (SYM) beyond the planar limit share some of the remarkable structures of the planar theory. In particular, we show that through two loops, the four-particle amplitude in full N=4 SYM has only logarithmic singularities and is free of any poles at infinity--properties closely related to uniform transcendentality and the UV finiteness of the theory. We also briefly comment on implications for maximal (N=8) supergravity theory (SUGRA).
Topographic quantitative EEG amplitude in recovered alcoholics.
Pollock, V E; Schneider, L S; Zemansky, M F; Gleason, R P; Pawluczyk, S
1992-05-01
Topographic measures of electroencephalographic (EEG) amplitude were used to compare recovered alcoholics (n = 14) with sex- and age-matched control subjects. Delta, alpha, and beta activity did not distinguish the groups, but regional differences in theta distribution did. Recovered alcoholics showed more uniform distributions of theta amplitudes in bilateral anterior and posterior regions compared with controls. Because a minimum of 5 years had elapsed since the recovered alcoholic subjects fulfilled DSM-III-R criteria for alcohol abuse or dependence, it is unlikely these EEG theta differences reflect the effects of withdrawal.
Dual amplitude pulse generator for radiation detectors
Hoggan, Jerry M.; Kynaston, Ronnie L.; Johnson, Larry O.
2001-01-01
A pulsing circuit for producing an output signal having a high amplitude pulse and a low amplitude pulse may comprise a current source for providing a high current signal and a low current signal. A gate circuit connected to the current source includes a trigger signal input that is responsive to a first trigger signal and a second trigger signal. The first trigger signal causes the gate circuit to connect the high current signal to a pulse output terminal whereas the second trigger signal causes the gate circuit to connect the low current signal to the pulse output terminal.
Amplitude Models for Discrimination and Yield Estimation
Phillips, William Scott
2016-09-01
This seminar presentation describes amplitude models and yield estimations that look at the data in order to inform legislation. The following points were brought forth in the summary: global models that will predict three-component amplitudes (R-T-Z) were produced; Q models match regional geology; corrected source spectra can be used for discrimination and yield estimation; three-component data increase coverage and reduce scatter in source spectral estimates; three-component efforts must include distance-dependent effects; a community effort on instrument calibration is needed.
Amplitude for N-gluon superstring scattering.
Stieberger, Stephan; Taylor, Tomasz R
2006-11-24
We consider scattering processes involving N gluonic massless states of open superstrings with a certain Regge slope alpha'. At the semiclassical level, the string world-sheet sweeps a disk and N gluons are created or annihilated at the boundary. We present exact expressions for the corresponding amplitudes, valid to all orders in alpha', for the so-called maximally helicity violating configurations, with N = 4, 5 and N = 6. We also obtain the leading O(alpha '2) string corrections to the zero-slope N-gluon Yang-Mills amplitudes.
Amplitude for N-Gluon Superstring Scattering
Stieberger, Stephan; Taylor, Tomasz R.
2006-11-24
We consider scattering processes involving N gluonic massless states of open superstrings with a certain Regge slope {alpha}{sup '}. At the semiclassical level, the string world-sheet sweeps a disk and N gluons are created or annihilated at the boundary. We present exact expressions for the corresponding amplitudes, valid to all orders in {alpha}{sup '}, for the so-called maximally helicity violating configurations, with N=4, 5 and N=6. We also obtain the leading O({alpha}{sup '2}) string corrections to the zero-slope N-gluon Yang-Mills amplitudes.
Coherent quantum states from classical oscillator amplitudes
NASA Astrophysics Data System (ADS)
Briggs, John S.; Eisfeld, Alexander
2012-05-01
In the first days of quantum mechanics Dirac pointed out an analogy between the time-dependent coefficients of an expansion of the Schrödinger equation and the classical position and momentum variables solving Hamilton's equations. Here it is shown that the analogy can be made an equivalence in that, in principle, systems of classical oscillators can be constructed whose position and momenta variables form time-dependent amplitudes which are identical to the complex quantum amplitudes of the coupled wave function of an N-level quantum system with real coupling matrix elements. Hence classical motion can reproduce quantum coherence.
Nonlinear (super)symmetries and amplitudes
NASA Astrophysics Data System (ADS)
Kallosh, Renata
2017-03-01
There is an increasing interest in nonlinear supersymmetries in cosmological model building. Independently, elegant expressions for the all-tree amplitudes in models with nonlinear symmetries, like D3 brane Dirac-Born-Infeld-Volkov-Akulov theory, were recently discovered. Using the generalized background field method we show how, in general, nonlinear symmetries of the action, bosonic and fermionic, constrain amplitudes beyond soft limits. The same identities control, for example, bosonic E 7(7) scalar sector symmetries as well as the fermionic goldstino symmetries.
Calculation of energy levels, {ital E}1 transition amplitudes, and parity violation in francium
Dzuba, V.A.; Flambaum, V.V.; Sushkov, O.P.
1995-05-01
Many-body perturbation theory in the screened Coulomb interaction was used to calculate energy levels, {ital E}1 trransition amplitudes, and the parity-nonconserving (PNC) {ital E}1 amplitude of the 7{ital s}-8{ital s} transition in francium. The method takes into account the core-polarization effect, the second-order correlations, and the three dominating sequences of higher-order correlation diagrams: screening of the electron-electron interaction, particle-hole interaction, and the iterations of the self-energy operator. The result for the PNC amplitude for {sup 223}Fr is {ital E}1(7{ital s}-8{ital s})=(1.59{plus_minus}{similar_to}1%){times}10{sup {minus}10}{ital iea}{sub {ital B}}({minus}{ital Q}{sub {ital W}}/{ital N}), where {ital Q}{sub {ital W}} is the weak charge of the nucleus, {ital N}=136 is the number of neutrons, {ital e}={vert_bar}{ital e}{vert_bar} is the elementary charge, and {ital a}{sub {ital B}} is the Bohr radius. Our prediction for the position of the 8{ital s} energy level of Fr, which has not been measured yet, is 13 110 cm{sup {minus}1} below the limit of the continuous spectrum. The accuracy of the calculations was controlled by comparison with available experimental data and analogous calculations for cesium. It is estimated to be {similar_to}0.1% for the energy levels and {similar_to}1% for the transition amplitudes.
Particle Distribution Modification by Low Amplitude Modes
White, R. B.; Gorelenkov, N.; Heidbrink, W. W.; Van Zeeland, M. A.
2009-08-28
Modification of a high energy particle distribution by a spectrum of low amplitude modes is investigated using a guiding center code. Only through resonance are modes effective in modifying the distribution. Diagnostics are used to illustrate the mode-particle interaction and to find which effects are relevant in producing significant resonance, including kinetic Poincare plots and plots showing those orbits with time averaged mode-particle energy transfer. Effects of pitch angle scattering and drag are studied, as well as plasma rotation and time dependence of the equilibrium and mode frequencies. A specific example of changes observed in a DIII-D deuterium beam distribution in the presence of low amplitude experimentally validated Toroidal Alfven (TAE) eigenmodes and Reversed Shear Alfven (RSAE) eigenmodes is examined in detail. Comparison with experimental data shows that multiple low amplitude modes can account for significant modification of high energy beam particle distributions. It is found that there is a stochastic threshold for beam profile modification, and that the experimental amplitudes are only slightly above this threshold.
The CMU Baryon Amplitude Analysis Program
NASA Astrophysics Data System (ADS)
Bellis, Matt
2007-05-01
The PWA group at Carnegie Mellon University has developed a comprehensive approach and analysis package for the purpose of extracting the amplitudes for photoproduced baryon resonances. The end goal is to identify any missing resonances that are predicted by the constituent quark model, but not definitively observed in experiments. The data comes from the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab.
Audio steganography by amplitude or phase modification
NASA Astrophysics Data System (ADS)
Gopalan, Kaliappan; Wenndt, Stanley J.; Adams, Scott F.; Haddad, Darren M.
2003-06-01
This paper presents the results of embedding short covert message utterances on a host, or cover, utterance by modifying the phase or amplitude of perceptually masked or significant regions of the host. In the first method, the absolute phase at selected, perceptually masked frequency indices was changed to fixed, covert data-dependent values. Embedded bits were retrieved at the receiver from the phase at the selected frequency indices. Tests on embedding a GSM-coded covert utterance on clean and noisy host utterances showed no noticeable difference in the stego compared to the hosts in speech quality or spectrogram. A bit error rate of 2 out of 2800 was observed for a clean host utterance while no error occurred for a noisy host. In the second method, the absolute phase of 10 or fewer perceptually significant points in the host was set in accordance with covert data. This resulted in a stego with successful data retrieval and a slightly noticeable degradation in speech quality. Modifying the amplitude of perceptually significant points caused perceptible differences in the stego even with small changes of amplitude made at five points per frame. Finally, the stego obtained by altering the amplitude at perceptually masked points showed barely noticeable differences and excellent data recovery.
Travel-Time and Amplitude Sensitivity Kernels
2011-09-01
amplitude sensitivity kernels shown in the lower panels concentrate about the corresponding eigenrays . Each 3D kernel exhibits a broad negative...in 2 and 3 dimensions have similar 11 shapes to corresponding travel-time sensitivity kernels (TSKs), centered about the respective eigenrays
Amplitude Frequency Response Measurement: A Simple Technique
ERIC Educational Resources Information Center
Satish, L.; Vora, S. C.
2010-01-01
A simple method is described to combine a modern function generator and a digital oscilloscope to configure a setup that can directly measure the amplitude frequency response of a system. This is achieved by synchronously triggering both instruments, with the function generator operated in the "Linear-Sweep" frequency mode, while the oscilloscope…
Connected formulas for amplitudes in standard model
NASA Astrophysics Data System (ADS)
He, Song; Zhang, Yong
2017-03-01
Witten's twistor string theory has led to new representations of S-matrix in massless QFT as a single object, including Cachazo-He-Yuan formulas in general and connected formulas in four dimensions. As a first step towards more realistic processes of the standard model, we extend the construction to QCD tree amplitudes with massless quarks and those with a Higgs boson. For both cases, we find connected formulas in four dimensions for all multiplicities which are very similar to the one for Yang-Mills amplitudes. The formula for quark-gluon color-ordered amplitudes differs from the pure-gluon case only by a Jacobian factor that depends on flavors and orderings of the quarks. In the formula for Higgs plus multi-parton amplitudes, the massive Higgs boson is effectively described by two additional massless legs which do not appear in the Parke-Taylor factor. The latter also represents the first twistor-string/connected formula for form factors.
BOLD Responses to Stimuli: Dependence on Frequency, Stimulus form, Amplitude, and Repetition Rate.
NASA Astrophysics Data System (ADS)
Robinson, Peter; Drysdale, Peter; van der Merwe, Helena; Kyriakou, Elizabeth; Rigozzi, Michelle; Germanoska, Biljana; Rennie, Christopher
2006-03-01
A quantitative theory is developed for the relationship between stimulus and the resulting Blood Oxygen Level Dependent (BOLD) functional MRI signal in the brain. The relationship of stimuli to neuronal activity during evoked responses is inferred from recent physiology-based modeling of evoked response potentials (ERPs). A hemodynamic model is then used to calculate the BOLD response to neuronal activity. The predicted response is analyzed vs. form, frequency, and amplitude of stimulus. The BOLD frequency response is very nearly linear in the parameter ranges of interest, with the form of a low-pass filter with a weak resonance at 0.07 Hz. For short stimuli, the response is closely proportional to the time-integrated stimulus-evoked activity, rather than the peak amplitude, as often assumed. There can thus be widely differing proportionalities between BOLD and peak activity, a likely reason for the weak expected correlation between ERPs and BOLD.
ABJM amplitudes and the positive orthogonal Grassmannian
NASA Astrophysics Data System (ADS)
Huang, Yu-tin; Wen, CongKao
2014-02-01
A remarkable connection between perturbative scattering amplitudes of four dimensional planar SYM, and the stratification of the positive Grassmannian, was revealed in the seminal work of Arkani-Hamed et al. Similar extension for three-dimensional ABJM theory was proposed. Here we establish a direct connection between planar scattering amplitudes of ABJM theory, and singularities thereof, to the stratification of the positive orthogonal Grassmannian. In particular, scattering processes are constructed through on-shell diagrams, which are simply iterative gluing of the fundamental four-point amplitude. Each diagram is then equivalent to the merging of fundamental OG2 orthogonal Grassmannian to form a larger OG k , where 2 k is the number of external particles. The invariant information that is encoded in each diagram is precisely this stratification. This information can be easily read off via permutation paths of the on-shell diagram, which also can be used to derive a canonical representation of OG k that manifests the vanishing of consecutive minors as the singularity of all on-shell diagrams. Quite remarkably, for the BCFW recursion representation of the tree-level amplitudes, the on-shell diagram manifests the presence of all physical factorization poles, as well as the cancellation of the spurious poles. After analytically continuing the orthogonal Grassmannian to split signature, we reveal that each on-shell diagram in fact resides in the positive cell of the orthogonal Grassmannian, where all minors are positive. In this language, the amplitudes of ABJM theory is simply an integral of a product of d log forms, over the positive orthogonal Grassmannian.
NASA Astrophysics Data System (ADS)
Strader, A. E.; Jackson, D. D.
2011-12-01
Deng & Sykes (1997) found a strong correlation between receiver earthquake location and positive increase in Coulomb stress (ΔCFF). Assuming a coefficient of friction of 0.6, and resolving stresses onto assumed fault planes with uniform orientation parallel to average Pacific-North American plate motion, they found that only 15% of receiver earthquakes occur in "stress shadows" where the Coulomb stress change should impede faulting. We extended their study by adding two source earthquakes (Hector Mine, 1999 and El Mayor-Cucupah, 2010), and calculating the stress changes at the locations of 134 receiver earthquakes with magnitude 4.4 and greater after 1999. We examined shear stress, normal stress, and Coulomb stress, resolving stresses onto four different hypothetical fault planes: smoothed seismicity-based planes, a weighted average of nearby fault-plane orientations, and the two nodal planes of weighed average moment tensors of nearby earthquakes. We also computed shear, normal, and Coulomb stress histories oriented according to the four choices of fault orientation, and tested the effect of total stress change on receiver earthquake magnitude. Our chi square test results indicate that, with 95% confidence, receiver earthquakes do not tend to avoid stress shadows, and that the choice of plane onto which stress is resolved does not affect the result. On average, 39% of earthquakes occur at the time of maximum stress at the event location, with no significant variation depending on the choice of rupture plane or type of stress change. We found no correlation between earthquake magnitude and total stress change at the events' locations. These results suggest that instantaneous cumulative Coulomb stress, as we and Deng & Sykes modeled it, does not strongly control the locations of future earthquakes. The lack of correlation between Coulomb stress change and magnitude suggests that modeled Coulomb stress change does not control the size of earthquakes once they
Direct evidence for a Coulombic phase in monopole-suppressed SU(2) lattice gauge theory
NASA Astrophysics Data System (ADS)
Grady, Michael
2013-11-01
Further evidence is presented for the existence of a non-confining phase at weak coupling in SU(2) lattice gauge theory. Using Monte Carlo simulations with the standard Wilson action, gauge-invariant SO(3)-Z2 monopoles, which are strong-coupling lattice artifacts, have been seen to undergo a percolation transition exactly at the phase transition previously seen using Coulomb gauge methods, with an infinite lattice critical point near β=3.2. The theory with both Z2 vortices and monopoles and SO(3)-Z2 monopoles eliminated is simulated in the strong-coupling (β=0) limit on lattices up to 604. Here, as in the high-β phase of the Wilson-action theory, finite size scaling shows it spontaneously breaks the remnant symmetry left over after Coulomb gauge fixing. Such a symmetry breaking precludes the potential from having a linear term. The monopole restriction appears to prevent the transition to a confining phase at any β. Direct measurement of the instantaneous Coulomb potential shows a Coulombic form with moderately running coupling possibly approaching an infrared fixed point of α˜1.4. The Coulomb potential is measured to 50 lattice spacings and 2 fm. A short-distance fit to the 2-loop perturbative potential is used to set the scale. High precision at such long distances is made possible through the use of open boundary conditions, which was previously found to cut random and systematic errors of the Coulomb gauge fixing procedure dramatically. The Coulomb potential agrees with the gauge-invariant interquark potential measured with smeared Wilson loops on periodic lattices as far as the latter can be practically measured with similar statistics data.
Comparison of COULOMB-2, NASCAP-2k and SPIS codes for geostationary spacecrafts charging
NASA Astrophysics Data System (ADS)
Novikov, Lev; Makletsov, Andrei; Sinolits, Vadim
In developing of international standards for spacecraft charging, it is necessary to compare results of spacecraft charging modeling obtained with various models. In the paper, electrical potentials for spacecraft 3D models were calculated with COULOMB-2, NASCAP-2k [1] and SPIS [2] software, and the comparison of obtained values was performed. To compare COULOMB-2 and NASCAP-2k codes we used a 3D geometrical model of a spacecraft given in [1]. Parameters of spacecraft surface materials were taken from [1], too. For COULOMB-2 and SPIS cross validation, we carried out calculations with SPIS code through SPENVIS web-interface and with COULOMB-2 software for a spacecraft geometrical model given in SPIS test examples [2]. In both cases, we calculated distributions of electric potentials on the spacecraft surface and visualized the obtained distributions with color code. Pictures of the surface potentials distribution calculated with COULOMB-2 and SPIS software are in good qualitative agreement. Absolute values of surface potentials calculated with these codes for different plasma conditions, are close enough. Pictures of the surface potentials distribution calculated for the spacecraft model [1] with COULOMB-2 software completely correspond to actual understanding of physical mechanisms of differential spacecraft surface charging. In this case, we compared only calculated values of the surface potential for the same space plasma conditions because the potential distributions on the spacecraft surface are absent in [1]. For all the plasma conditions considered, COULOMB-2 model gives higher absolute values of negative potential, than NASCAP-2k model. Differences in these values reach 2-3 kV. The possible explanations of the divergences indicated above are distinctions in calculation procedures of primary plasma currents and secondary emission currents. References 1. Ferguson D.С., Wimberly S.C. 51st AIAA Aerospace Science Meeting 2013 (AIAA 2013-0810). 2. http://dev.spis.org/projects/spine/home/spis
A spectral Phase-Amplitude method for propagating a wave function to large distances
NASA Astrophysics Data System (ADS)
Rawitscher, George
2015-06-01
The phase and amplitude (Ph-A) of a wave function vary slowly with distance, in contrast to the wave function that can be highly oscillatory. Hence the Ph-A representation of a wave function requires far fewer computational mesh points than the wave function itself. In 1930 Milne presented an equation for the phase and the amplitude functions (which is different from the one developed by Calogero), and in 1962 Seaton and Peach solved these equations iteratively. The objective of the present study is to implement Seaton and Peach's iteration procedure with a spectral Chebyshev expansion method, and at the same time present a non-iterative analytic solution to an approximate version of the iterative equations. The iterations converge rapidly for the case of attractive potentials. Two numerical examples are given: (1) for a potential that decreases with distance as 1 /r3, and (2) a Coulomb potential ∝ 1 / r. In both cases the whole radial range of [0-2000] requires only between 25 and 100 mesh points and the corresponding accuracy is between 10-3 and 10-6. The 0th iteration (which is the WKB approximation) gives an accuracy of 10-2. This spectral method permits one to calculate a wave function out to large distances reliably and economically.
NASA Astrophysics Data System (ADS)
Paulo, Álvaro San; García, Ricardo
2001-11-01
Amplitude-modulation (tapping mode) atomic force microscopy is a technique for high resolution imaging of a wide variety of surfaces in air and liquid environments. Here by using the virial theorem and energy conservation principles we have derived analytical relationships between the oscillation amplitude, phase shift, and average tip-surface forces. We find that the average value of the interaction force and oscillation and the average power dissipated by the tip-surface interaction are the quantities that control the amplitude reduction. The agreement obtained between analytical and numerical results supports the analytical method.
NASA Astrophysics Data System (ADS)
Kong, Biao; Wang, Enyuan; Li, Zenghua; Wang, Xiaoran; Niu, Yue; Kong, Xiangguo
2017-01-01
Thermally treated sandstone deformation and fracture produced abundant acoustic emission (AE) signals. The AE signals waveform contained plentiful precursor information of sandstone deformation and fracture behavior. In this paper, uniaxial compression tests of sandstone after different temperature treatments were conducted, the frequency-amplitude characteristics of AE signals were studied, and the main frequency distribution at different stress level was analyzed. The AE signals frequency-amplitude characteristics had great difference after different high temperature treatment. Significant differences existed of the main frequency distribution of AE signals during thermal treated sandstone deformation and fracture. The main frequency band of the largest waveforms proportion was not unchanged after different high temperature treatments. High temperature caused thermal damage to the sandstone, and sandstone deformation and fracture was obvious than the room temperature. The number of AE signals was larger than the room temperature during the initial loading stage. The low frequency AE signals had bigger proportion when the stress was 0.1, and the maximum value of the low frequency amplitude was larger than high frequency signals. With the increase of stress, the low and high frequency AE signals were gradually increase, which indicated that different scales ruptures were broken in sandstone. After high temperature treatment, the number of high frequency AE signals was significantly bigger than the low frequency AE signals during the latter loading stage, this indicates that the small scale rupture rate of recurrence and frequency were more than large scale rupture. The AE ratio reached the maximum during the sandstone instability failure period, and large scale rupture was dominated in the failure process. AE amplitude increase as the loading increases, the deformation and fracture of sandstone was increased gradually. By comparison, the value of the low frequency
NASA Astrophysics Data System (ADS)
Anoukou, K.; Pastor, F.; Dufrenoy, P.; Kondo, D.
2016-06-01
The present two-part study aims at investigating the specific effects of Mohr-Coulomb matrix on the strength of ductile porous materials by using a kinematic limit analysis approach. While in the Part II, static and kinematic bounds are numerically derived and used for validation purpose, the present Part I focuses on the theoretical formulation of a macroscopic strength criterion for porous Mohr-Coulomb materials. To this end, we consider a hollow sphere model with a rigid perfectly plastic Mohr-Coulomb matrix, subjected to axisymmetric uniform strain rate boundary conditions. Taking advantage of an appropriate family of three-parameter trial velocity fields accounting for the specific plastic deformation mechanisms of the Mohr-Coulomb matrix, we then provide a solution of the constrained minimization problem required for the determination of the macroscopic dissipation function. The macroscopic strength criterion is then obtained by means of the Lagrangian method combined with Karush-Kuhn-Tucker conditions. After a careful analysis and discussion of the plastic admissibility condition associated to the Mohr-Coulomb criterion, the above procedure leads to a parametric closed-form expression of the macroscopic strength criterion. The latter explicitly shows a dependence on the three stress invariants. In the special case of a friction angle equal to zero, the established criterion reduced to recently available results for porous Tresca materials. Finally, both effects of matrix friction angle and porosity are briefly illustrated and, for completeness, the macroscopic plastic flow rule and the voids evolution law are fully furnished.
Positive and Negative Coulomb Drag in a 1D Quantum Circuit
NASA Astrophysics Data System (ADS)
Laroche, Dominique; Gervais, Guillaume; Lilly, Mike; Reno, John
2012-02-01
We report Coulomb drag measurements between tunable vertically-coupled quantum wires. The wires are fabricated in a GaAs/AlGaAs double quantum well heterostructure with a 15 nm barrier separating the quantum wells. The Coulomb drag signal is mapped out versus the number of subbands occupied in each wire, and regions of both positive and negative drag are observed (D. Laroche et. al. Nature Nanotechnology, doi:10.1038/nnano.2011.182). The observation of negative Coulomb drag at a high one-dimensional electronic density is not predicted by the usual momentum-transfer model for Coulomb drag and shows that the existing picture of the drag effect in one-dimension is incomplete. In order to clarify the origin of this negative signal, temperature dependencies of the Coulomb drag are presented both in the positive and in the negative drag regimes. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
Observations of Coulomb explosion in doubly charged atomic and molecular clusters
NASA Astrophysics Data System (ADS)
Gotts, N. G.; Lethbridge, P. G.; Stace, A. J.
1992-01-01
Coulomb explosion has been promoted in a range of doubly charged atomic and molecular clusters. In these new experiments, mass selected clusters of Ar2+n, (CO2)2+n, (H2O)2+n, (H2O)nH2+2, (CH3CN)nH2+2, and (C6H6)2+n have been subjected to collisional activation with a background gas. For species close to the Coulomb cutoff, each collision removes sufficient atoms or molecules (approximately six) as to render the clusters unstable. As a result, charge separation occurs and part (≂30%) of the Coulomb repulsion energy is released in the form of center of mass kinetic energy in the fragments. The remaining Coulomb energy appears as internal excitation in the fragments and subsequently leads to extensive evaporation. It is shown that the latter process is continuing even 10-6 s after Coulomb explosion. All the molecular systems studied show evidence of asymmetric charge separation, with some singly charged fragments containing up to 65% of the initial cluster mass. A detailed quantitative analysis of the results is made difficult by the very broad range of fragment ion sizes.
Three-Body Coulomb Functions in the Hyperspherical Adiabatic Expansion Method
NASA Astrophysics Data System (ADS)
Garrido, E.; Kievsky, A.; Viviani, M.
2016-12-01
In this work we describe a numerical method devised to compute continuum three-body wave functions. The method is implemented using the hyperspherical adiabatic expansion for the three-body wave function imposing a box boundary condition. The continuum energy spectrum results discretized and, for specific quantum number values, all the possible incoming and outgoing channels are simultaneously computed. For a given energy, the hyperradial continuum functions form a matrix whose ij-term refers to specific incoming and outgoing channels. When applied to three-body systems interacting only through the Coulomb potential, this method provides the adiabatic representation of the regular three-body Coulomb wave function. The computation of the irregular Coulomb wave function representation is also discussed. These regular and irregular Coulomb functions can be used to extract the S-matrix for those reactions where, together with some short-range potential, the Coulomb interaction is also present. The method is illustrated in the case of the 3→ 3 process of three alpha particles.
Constructing QCD one-loop amplitudes
Forde, Darren; /SLAC /UCLA
2008-02-22
In the context of constructing one-loop amplitudes using a unitarity bootstrap approach we discuss a general systematic procedure for obtaining the coefficients of the scalar bubble and triangle integral functions of one-loop amplitudes. Coefficients are extracted after examining the behavior of the cut integrand as the unconstrained parameters of a specifically chosen parameterization of the cut loop momentum approach infinity. Measurements of new physics at the forthcoming experimental program at CERN's Large Hadron Collider (LHC) will require a precise understanding of processes at next-to-leading order (NLO). This places increased demands for the computation of new one-loop amplitudes. This in turn has spurred recent developments towards improved calculational techniques. Direct calculations using Feynman diagrams are in general inefficient. Developments of more efficient techniques have usually centered around unitarity techniques [1], where tree amplitudes are effectively 'glued' together to form loops. The most straightforward application of this method, in which the cut loop momentum is in D = 4, allows for the computation of 'cut-constructible' terms only, i.e. (poly)logarithmic containing terms and any related constants. QCD amplitudes contain, in addition to such terms, rational pieces which cannot be derived using such cuts. These 'missing' rational parts can be extracted using cut loop momenta in D = 4-2 {var_epsilon}. The greater difficulty of such calculations has restricted the application of this approach, although recent developments [3, 4] have provided new promise for this technique. Recently the application of on-shell recursion relations [5] to obtaining the 'missing' rational parts of one-loop processes [6] has provided an alternative very promising solution to this problem. In combination with unitarity methods an 'on-shell bootstrap' approach provides an efficient technique for computing complete one-loop QCD amplitudes [7]. Additionally
Amplitudes of MHD Waves in Sunspots
NASA Astrophysics Data System (ADS)
Norton, Aimee Ann; Cally, Paul; Baldner, Charles; Kleint, Lucia; Tarbell, Theodore D.; De Pontieu, Bart; Scherrer, Philip H.; Rajaguru, Paul
2016-05-01
The conversion of p-modes into MHD waves by strong magnetic fields occurs mainly in the sub-photospheric layers. The photospheric signatures of MHD waves are weak due to low amplitudes at the beta=1 equipartion level where mode-conversion occurs. We report on small amplitude oscillations observed in the photosphere with Hinode SOT/SP in which we analyze time series for sunspots ARs 12186 (11.10.2014) and 12434 (17.10.2015). No significant magnetic field oscillations are recovered in the umbra or penumbra in the ME inversion. However, periodicities in the inclination angle are found at the umbral/penumbral boundary with 5 minute periods. Upward propagating waves are indicated in the intensity signals correlated between HMI and AIA at different heights. We compare SP results with the oscillations observed in HMI data. Simultaneous IRIS data shows transition region brightening above the umbral core.
Multilayered models for electromagnetic reflection amplitudes
NASA Technical Reports Server (NTRS)
Linlor, W. I.
1976-01-01
The remote sensing of snowpack characteristics with surface installations or with an airborne system could have important applications in water resource management and flood prediction. To derive some insight into such applications, the electromagnetic response of multilayer snow models is analyzed. Normally incident plane waves are assumed at frequencies ranging from 10 to the 6th power to 10 to the 10th power Hz, and amplitude reflection coefficients are calculated for models having various snow-layer combinations, including ice sheets. Layers are defined by a thickness, permittivity, and conductivity; the electrical parameters are constant or prescribed functions of frequency. To illustrate the effect of various layering combinations, results are given in the form of curves of amplitude reflection coefficients, versus frequency for a variety of models. Under simplifying assumptions, the snow thickness and effective dielectric constant can be estimated from the reflection coefficient variations as a function of frequency.
34 CFR Appendix to Part 81 - Illustrations of Proportionality
Code of Federal Regulations, 2013 CFR
2013-07-01
... 34 Education 1 2013-07-01 2013-07-01 false Illustrations of Proportionality Appendix to Part 81 Education Office of the Secretary, Department of Education GENERAL EDUCATION PROVISIONS ACT-ENFORCEMENT Pt. 81, App. Appendix to Part 81—Illustrations of Proportionality (1) Ineligible beneficiaries. A...
34 CFR Appendix to Part 81 - Illustrations of Proportionality
Code of Federal Regulations, 2012 CFR
2012-07-01
... 34 Education 1 2012-07-01 2012-07-01 false Illustrations of Proportionality Appendix to Part 81 Education Office of the Secretary, Department of Education GENERAL EDUCATION PROVISIONS ACT-ENFORCEMENT Pt. 81, App. Appendix to Part 81—Illustrations of Proportionality (1) Ineligible beneficiaries. A...
34 CFR Appendix to Part 81 - Illustrations of Proportionality
Code of Federal Regulations, 2014 CFR
2014-07-01
... 34 Education 1 2014-07-01 2014-07-01 false Illustrations of Proportionality Appendix to Part 81 Education Office of the Secretary, Department of Education GENERAL EDUCATION PROVISIONS ACT-ENFORCEMENT Pt. 81, App. Appendix to Part 81—Illustrations of Proportionality (1) Ineligible beneficiaries. A...
Longitudinal Enrollment Dynamics and Changes in Ethnic Proportionality.
ERIC Educational Resources Information Center
Greaves, Fred
The Federal Racial/Ethnic Surveys of the Salinas Union High School District were examined to identify changes in ethnic proportions within a particular class from its entry in the 9th grade until the 12th grade. The 9th, 10th, 11th, and 12th grade proportional distributions are reported by school (Alisal High School, North Salinas High School, and…
The Failings of the Law of Definite Proportions
ERIC Educational Resources Information Center
Suchow, Lawrence
1975-01-01
Indicates that the concept of definite proportions or constant composition should be introduced with qualification. Presents arguments against the Law of Definite Proportions and cites examples in the areas of solid solutions, compounds of the transition and inner transition elements, and in some compounds of the representative elements. (GS)
The Fibonacci Sequence: Proportional Semantic Bases of Children's Aesthetic Preferences.
ERIC Educational Resources Information Center
Neperud, Ronald W.; Serlin, Ronald C.
1984-01-01
Only at the third- and seventh-grade levels did proportional preferences for Fibonacci figures differ significantly from preferences for other kinds of proportional spatial divisions. Semantic patterns were similar among third and fifth graders, with a change occurring between fifth and seventh grades in keeping with the development of formal…
Understanding Proportional Reasoning in Pre-Service Teachers
ERIC Educational Resources Information Center
Johnson, Kim H.
2013-01-01
The purpose of this study is to examine the proportional reasoning of pre-service teachers at the beginning of their teacher preparation program using the developmental shifts described by Lobato and Ellis (2010). They cast changes in proportional reasoning as transitions or "shifts" in students' thinking and these shifts can serve as…
Large Amplitude Oscillatory Shear near Jamming
NASA Astrophysics Data System (ADS)
Tighe, Brian; Dagois-Bohy, Simon; Somfai, Ellak; van Hecke, Martin
2014-11-01
Jammed solids such as foams and emulsions can be driven with oscillatory shear at finite strain amplitude and frequency. On a macro scale, this induces nonlinearities such as strain softening and shear thinning. On the micro scale one observes the onset of irreversibility, caging, and long-time diffusion. Using simulations of soft viscous spheres, we systematically vary the distance to the jamming transition. We correlate crossovers in the microscopic and macroscopic response, and construct scaling arguments to explain their relationships.
Amplitude calibration experiment for SIR-B
NASA Technical Reports Server (NTRS)
Held, D. N.; Ulaby, F. T.
1984-01-01
The objectives, approach, and expected results of the amplitude calibration experiment for the Shuttle Imaging Radar-B (SIR-B) are outlined. Specific objectives include: (1) the determination of the repeatability (stability) of the SIR-B; (2) the absolute and relative calibration of the system; and (3) the ground truth verification of the calibration accuracy using measurements made by a ground spectrometer and an airborne synthetic aperture radar.
Photon Counting Chirped Amplitude Modulation Ladar
2008-03-01
22202-4302. Respondents should be aware that notwithstanding any other provision of law , no person shall be subject to any penalty for failing to...135 S. Taylor Ave., Room 103, Louisville, CO 80027-3025 14. ABSTRACT This work developed a method using Geiger -mode avalanche photodiode (GM-APD...architecture are discussed. 15. SUBJECT TERMS laser radar, ladar, avalanche photo-detectors, Geiger mode detectors, chirped amplitude modulation
Chiral extrapolation of SU(3) amplitudes
Ecker, Gerhard
2011-05-23
Approximations of chiral SU(3) amplitudes at NNLO are proposed to facilitate the extrapolation of lattice data to the physical meson masses. Inclusion of NNLO terms is essential for investigating convergence properties of chiral SU(3) and for determining low-energy constants in a controllable fashion. The approximations are tested with recent lattice data for the ratio of decay constants F{sub K}/F{sub {pi}}.
Understanding the amplitudes of noise correlation measurements
Tsai, Victor C.
2011-01-01
Cross correlation of ambient seismic noise is known to result in time series from which station-station travel-time measurements can be made. Part of the reason that these cross-correlation travel-time measurements are reliable is that there exists a theoretical framework that quantifies how these travel times depend on the features of the ambient noise. However, corresponding theoretical results do not currently exist to describe how the amplitudes of the cross correlation depend on such features. For example, currently it is not possible to take a given distribution of noise sources and calculate the cross correlation amplitudes one would expect from such a distribution. Here, we provide a ray-theoretical framework for calculating cross correlations. This framework differs from previous work in that it explicitly accounts for attenuation as well as the spatial distribution of sources and therefore can address the issue of quantifying amplitudes in noise correlation measurements. After introducing the general framework, we apply it to two specific problems. First, we show that we can quantify the amplitudes of coherency measurements, and find that the decay of coherency with station-station spacing depends crucially on the distribution of noise sources. We suggest that researchers interested in performing attenuation measurements from noise coherency should first determine how the dominant sources of noise are distributed. Second, we show that we can quantify the signal-to-noise ratio of noise correlations more precisely than previous work, and that these signal-to-noise ratios can be estimated for given situations prior to the deployment of seismometers. It is expected that there are applications of the theoretical framework beyond the two specific cases considered, but these applications await future work.
Zeroing in on Supersymmetric Radiation Amplitude Zeros
Hewett, JoAnne L.; Ismail, Ahmed; Rizzo, Thomas G.; /SLAC
2012-02-15
Radiation amplitude zeros have long been used to test the Standard Model. Here, we consider the supersymmetric radiation amplitude zero in chargino-neutralino associated production, which can be observed at the luminosity upgraded LHC. Such an amplitude zero only occurs if the neutralino has a large wino fraction and hence this observable can be used to determine the neutralino eigenstate content. We find that this observable can be measured by comparing the p{sub T} spectrum of the softest lepton in the trilepton {tilde {chi}}{sub 1}{sup {+-}} {tilde {chi}}{sub 2}{sup 0} decay channel to that of a control process such as {tilde {chi}}{sub 1}{sup +} {tilde {chi}}{sub 1}{sup -} or {tilde {chi}}{sub 2}{sup 0} {tilde {chi}}{sub 2}{sup 0}. We test this technique on a previously generated model sample of the 19 dimensional parameter space of the phenomenological MSSM, and find that it is effective in determining the wino content of the neutralino.
[Amplitude modulation in sound signals by mammals].
Nikol'skiĭ, A A
2012-01-01
Periodic variations in amplitude of a signal, or amplitude modulation (AM), affect the structure of communicative messages spectrum. Within the spectrum of AM-signals, side frequencies are formed both above and below the carrier frequency that is subjected to modulation. In case of harmonic signal structure they are presented near fundamental frequency as well as near harmonics. Thus, AM may by viewed as a relatively simple mechanism for controlling the spectrum of messages transmitted by mammals. Examples of AM affecting the spectrum structure of functionally different sound signals are discussed as applied to representatives of four orders of mammals: rodents (Reodentia), duplicidentates (Lagomorpha), pinnipeds (Pinnipedia), and paridigitates (Artiodactia). For the first time, the classification of AM in animals' sound signals is given. Five forms of AM are picked out in sound signals by mammals: absence of AM, continuous AM, fragmented, heterogeneous, and multilevel one. AM presence/absence is related neither with belonging to any specific order nor with some particular function of a signal. Similar forms of AM can occur in different orders of mammals in parallel. On the contrary, different forms of AM can be detected in signals meant for similar functions. The assumption is made about AM-signals facilitating information encoding and jamprotection of messages transmitted by mammals. Preliminry analysis indicates that hard-driving amplitude modulation is incompatible with hard-driving frequency modulation.
NASA Astrophysics Data System (ADS)
Zhang, G. L.; Pan, M.
2016-10-01
The Coulomb barrier heights are calculated by using the proximity potential with a new universal function in comparison with the results of proximity potentials Prox77, AW95, Bass73, BW91, CW76, DP and Ng80. It is found that the new results of Coulomb barrier heights are better than those of most proximity potentials. Then this proximity potential with the new universal function was used to calculate the Coulomb barrier positions and heights from light fusion systems to heavy fusion systems. The parametrized formulas are obtained for Coulomb barrier height and position, and can reproduce most of calculated barrier heights and positions within the accuracy of ± 1%.
Long-Range Coulomb Effect in Intense Laser-Driven Photoelectron Dynamics
Quan, Wei; Hao, XiaoLei; Chen, YongJu; Yu, ShaoGang; Xu, SongPo; Wang, YanLan; Sun, RenPing; Lai, XuanYang; Wu, ChengYin; Gong, QiHuang; He, XianTu; Liu, XiaoJun; Chen, Jing
2016-01-01
In strong field atomic physics community, long-range Coulomb interaction has for a long time been overlooked and its significant role in intense laser-driven photoelectron dynamics eluded experimental observations. Here we report an experimental investigation of the effect of long-range Coulomb potential on the dynamics of near-zero-momentum photoelectrons produced in photo-ionization process of noble gas atoms in intense midinfrared laser pulses. By exploring the dependence of photoelectron distributions near zero momentum on laser intensity and wavelength, we unambiguously demonstrate that the long-range tail of the Coulomb potential (i.e., up to several hundreds atomic units) plays an important role in determining the photoelectron dynamics after the pulse ends. PMID:27256904
NASA Astrophysics Data System (ADS)
Yudin, G. L.; Patchkovskii, S.; Corkum, P. B.; Bandrauk, A. D.
2007-03-01
We develop a description of laser-assisted x-ray photoionization based on a sudden approximation approach. By splitting the system evolution into three time stages we find necessary and sufficient conditions for spatial and temporal separation of Coulomb and Volkov continuum solutions. Using the separable Coulomb-Volkov wavefunction we present an analytical non-relativistic quantum theory of attosecond photoionization. It applies for arbitrary x-ray parameters, with both Coulomb continuum and laser field treated non-perturbatively. The theory provides a firm basis for characterizing photoelectron phase and atomic and molecular wavefunctions, by extracting them from experimental data. Using the molecular hydrogen ion as a test case, we display a variety of photoelectron interference sources in energy- and angular-resolved spectra for different pulse durations, chirps and delay times between x-ray pulse replicas.
Measurement of the 92,93,94,100Mo(γ,n) reactions by Coulomb Dissociation
NASA Astrophysics Data System (ADS)
Göbel, K.; Adrich, P.; Altstadt, S.; Alvarez-Pol, H.; Aksouh, F.; Aumann, T.; Babilon, M.; Behr, K.-H.; Benlliure, J.; Berg, T.; Böhmer, M.; Boretzky, K.; Brünle, A.; Beyer, R.; Casarejos, E.; Chartier, M.; Cortina-Gil, D.; Chatillon, A.; Datta Pramanik, U.; Deveaux, L.; Elvers, M.; Elze, T. W.; Emling, H.; Erhard, M.; Ershova; Fernandez-Dominguez, B.; Geissel, H.; Górska, M.; Heftrich, T.; Heil, M.; Hellstroem, M.; Ickert, G.; Johansson, H.; Junghans, A. R.; Käppeler, F.; Kiselev, O.; Klimkiewicz, A.; Kratz, J. V.; Kulessa, R.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lindenberg, K.; Litvinov, Y. A.; Maierbeck, P.; Movsesyan, A.; Müller, S.; Nilsson, T.; Nociforo, C.; Paar, N.; Palit, R.; Paschalis, S.; Plag, R.; Prokopowicz, W.; Reifarth, R.; Rossi, D. M.; Schnorrenberger, L.; Simon, H.; Sonnabend, K.; Sümmerer, K.; Surówka, G.; Vretenar, D.; Wagner, A.; Walter, S.; Waluś, W.; Wamers, F.; Weick, H.; Weigand, M.; Winckler, N.; Winkler, M.; Zilges, A.
2016-01-01
The Coulomb Dissociation (CD) cross sections of the stable isotopes 92,94,100Mo and of the unstable isotope 93Mo were measured at the LAND/R3B setup at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. Experimental data on these isotopes may help to explain the problem of the underproduction of 92,94Mo and 96,98Ru in the models of p-process nucleosynthesis. The CD cross sections obtained for the stable Mo isotopes are in good agreement with experiments performed with real photons, thus validating the method of Coulomb Dissociation. The result for the reaction 93Mo(γ,n) is especially important since the corresponding cross section has not been measured before. A preliminary integral Coulomb Dissociation cross section of the 94Mo(γ,n) reaction is presented. Further analysis will complete the experimental database for the (γ,n) production chain of the p-isotopes of molybdenum.
Velizhanin, Kirill A; Piryatinski, Andrei
2011-05-12
Employing the interband exciton scattering model, we have derived a closed set of equations determining the 2D double-quantum coherence signal sensitive to the interband Coulomb interactions (i.e., many-body Coulomb interactions leading to the couplings between exciton and biexciton bands) in semiconductor nanostructures such as nanocrystals, quantum wires, wells, and carbon nanotubes. Our general analysis of 2D double-quantum coherence resonances has demonstrated that the interband Coulomb interactions lead to new cross-peaks whose appearance can be interpreted as a result of exciton and biexciton state mixing. The presence of the strongly coupled resonant states and weakly coupled background of off-resonant states can significantly simplify cross-peak analysis by eliminating the congested background spectrum. Our simulations of the 2D double-quantum coherence signal in PbSe NCs have validated this approach.
On the Klein–Gordon oscillator subject to a Coulomb-type potential
Bakke, K. Furtado, C.
2015-04-15
By introducing the scalar potential as modification in the mass term of the Klein–Gordon equation, the influence of a Coulomb-type potential on the Klein–Gordon oscillator is investigated. Relativistic bound states solutions are achieved to both attractive and repulsive Coulomb-type potentials and the arising of a quantum effect characterized by the dependence of angular frequency of the Klein–Gordon oscillator on the quantum numbers of the system is shown. - Highlights: • Interaction between the Klein–Gordon oscillator and a modified mass term. • Relativistic bound states for both attractive and repulsive Coulomb-type potentials. • Dependence of the Klein–Gordon oscillator frequency on the quantum numbers. • Relativistic analogue of a position-dependent mass system.
Structural relaxation and aging scaling in the Coulomb and Bose glass models
NASA Astrophysics Data System (ADS)
Assi, Hiba; Chaturvedi, Harshwardhan; Pleimling, Michel; Täuber, Uwe Claus
2016-11-01
We employ Monte Carlo simulations to study the relaxation properties of the two-dimensional Coulomb glass in disordered semiconductors and the three-dimensional Bose glass in type-II superconductors in the presence of extended linear defects. We investigate the effects of adding non-zero random on-site energies from different distributions on the properties of the correlation-induced Coulomb gap in the density of states (DOS) and on the non-equilibrium aging kinetics highlighted by the density autocorrelation functions. We also probe the sensitivity of the system's equilibrium and non-equilibrium relaxation properties to instantaneous changes in the density of charge carriers in the Coulomb glass or flux lines in the Bose glass.
Coulomb Excitation of 78,80Se and the radioactive 84Se (N = 50) isotopes
NASA Astrophysics Data System (ADS)
Galindo-Uribarri, A.; Padilla-Rodal, E.; Garcia-Ruiz, R. F.; Allmond, J. M.; Batchelder, J. C.; Beene, J. R.; Lagergren, K. B.; Mueller, P. E.; Radford, D. C.; Stracener, D. W.; Urrego-Blanco, J. P.; Varner, R. L.; Yu, C.-H.
2011-10-01
Coulomb excitation is a purely electromagnetic excitation process of nuclear states due to the Coulomb field of two colliding nuclei. It is a very precise tool to measure excitation probabilities and provide insight on the collectivity of nuclear excitations and in particular on nuclear shapes. We have measured the B(E2) value of various nuclei in the mass A ~ 80 region using particle-gamma coincidences with the HyBall and Clarion arrays at HRIBF. The Coulomb excitation of various projectile-target combinations (ASe on 12C, 24Mg, 27Al and 50Ti) allow the use of consistency cross checks and the systematic study of isotopic and isotonic chains using both stable and radioactive nuclei under almost identical experimental conditions.We present new results for 78Se, 80Se and the radioactive nucleus 84Se (N = 50). Research sponsored by the Office of Nuclear Physics, U.S. Department of Energy and CONACyT Grant 103366.
Coulomb explosion induced by intense ultrashort laser pulses in two-dimensional clusters
Mijoule, Vincent; Lewis, Laurent J.; Meunier, Michel
2006-03-15
The phenomenon of Coulomb explosion is studied through qualitative numerical simulations of clusters irradiated with intense ultrashort laser pulses. We introduce a semiquantum approach which allows us to model two different types of materials--akin to rare gases and dielectrics--and which is appropriate for both low- and high-energy domains, i.e., the thermodynamic regime and the Coulomb explosion regime. Through a detailed study of clusters submitted to laser pulses of various intensities, we demonstrate that Coulomb explosion is the process responsible for cluster explosion under femtosecond laser pulses. We examine the differences in the dynamics of explosion of rare-gas clusters as a function of the wavelength of the incident laser radiation. For dielectric clusters, our simulations reveal a fragmented explosion mechanism; the influence of the size of the cluster is also studied.
Influence of the Coulomb interaction on the exchange coupling in granular magnets
NASA Astrophysics Data System (ADS)
Udalov, O. G.; Beloborodov, I. S.
2017-04-01
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.
Doping Induced Electronic Phase Separation and Coulomb Bubbles in Layered Superconductors
NASA Astrophysics Data System (ADS)
Saarela, M.; Kusmartsev, F. V.
2010-12-01
We study properties of charge fluids with random impurities or heavy polarons using a microscopic Hamiltonian with the full many-body Coulomb interaction. At zero temperature and high enough density the bosonic fluid is superconducting, but when density decreases the Coulomb interaction will be strongly over-screened and impurities or polarons begin to trap charge carriers forming bound quasiparticle like clusters, which we call Coulomb bubbles or clumps. These bubbles are embedded inside the superconductor and form nuclei of a new insulating state. The growth of a bubble is terminated by the Coulomb force. The fluid contains two groups of charge carriers associated with free and localized states. The insulating state arises via a percolation of the insulating islands of bubbles, which cluster and prevent the flow of the electrical supercurrent through the system. Our results are applicable to HTSC. There the Coulomb fluids discussed in the paper correspond to mobile holes located on Cu sites and heavy polarons or charged impurities located on Oxygen sites. As a result of our calculations the following two-componet picture of two competing orders in cuprates arise. The mobile and localized states are competing with each other and their balance is controlled by doping. At high doping a large Fermi surface is open. There the density of real charge carriers is significantly larger than the density of the doped ones. When doping decreases more and more carriers are localized as Coulomb clumps which are creating around heavy polarons localized on Oxygen sites and forming a regular lattice. The picture is consistent with the Gorkov and Teitelbaum (GT) analysis 1,2 of the transport, Hall effect data and the ARPES spectra as well as with nanoscale superstructures observed in Scanning Tunneling Microscope(STM) experiments [3-8]. The scenario of the clump formation may be also applicable to pnictides, where two types of clumps may arise even at very high temperatures.
Doping Induced Electronic Phase Separation and Coulomb Bubbles in Layered Superconductors
NASA Astrophysics Data System (ADS)
Saarela, M.; Kusmartsev, F. V.
We study properties of charge fluids with random impurities or heavy polarons using a microscopic Hamiltonian with the full many-body Coulomb interaction. At zero temperature and high enough density the bosonic fluid is superconducting, but when density decreases the Coulomb interaction will be strongly over-screened and impurities or polarons begin to trap charge carriers forming bound quasiparticle like clusters, which we call Coulomb bubbles or clumps. These bubbles are embedded inside the superconductor and form nuclei of a new insulating state. The growth of a bubble is terminated by the Coulomb force. The fluid contains two groups of charge carriers associated with free and localized states. The insulating state arises via a percolation of the insulating islands of bubbles, which cluster and prevent the flow of the electrical supercurrent through the system. Our results are applicable to HTSC. There the Coulomb fluids discussed in the paper correspond to mobile holes located on Cu sites and heavy polarons or charged impurities located on Oxygen sites. As a result of our calculations the following two-componet picture of two competing orders in cuprates arise. The mobile and localized states are competing with each other and their balance is controlled by doping. At high doping a large Fermi surface is open. There the density of real charge carriers is significantly larger than the density of the doped ones. When doping decreases more and more carriers are localized as Coulomb clumps which are creating around heavy polarons localized on Oxygen sites and forming a regular lattice. The picture is consistent with the Gorkov and Teitelbaum (GT) analysis 1,2 of the transport, Hall effect data and the ARPES spectra as well as with nanoscale superstructures observed in Scanning Tunneling Microscope(STM) experiments [3-8]. The scenario of the clump formation may be also applicable to pnictides, where two types of clumps may arise even at very high temperatures.
Development of proportional reasoning: where young children go wrong.
Boyer, Ty W; Levine, Susan C; Huttenlocher, Janellen
2008-09-01
Previous studies have found that children have difficulty solving proportional reasoning problems involving discrete units until 10 to 12 years of age, but can solve parallel problems involving continuous quantities by 6 years of age. The present studies examine where children go wrong in processing proportions that involve discrete quantities. A computerized proportional equivalence choice task was administered to kindergartners through 4th-graders in Study 1, and to 1st- and 3rd-graders in Study 2. Both studies involved 4 between-subjects conditions that were formed by pairing continuous and discrete target proportions with continuous and discrete choice alternatives. In Study 1, target and choice alternatives were presented simultaneously; in Study 2, target and choice alternatives were presented sequentially. In both studies, children performed significantly worse when both the target and choice alternatives were represented with discrete quantities than when either or both of the proportions involved continuous quantities. Taken together, these findings indicate that children go astray on proportional reasoning problems involving discrete units only when a numerical match is possible, suggesting that their difficulty is due to an overextension of numerical equivalence concepts to proportional equivalence problems.
Development of Proportional Reasoning: Where Young Children Go Wrong
Boyer, Ty W.; Levine, Susan C.; Huttenlocher, Janellen
2008-01-01
Previous studies have found that children have difficulty solving proportional reasoning problems involving discrete units until 10- to 12-years of age, but can solve parallel problems involving continuous quantities by 6-years of age. The present studies examine where children go wrong in processing proportions that involve discrete quantities. A computerized proportional equivalence choice task was administered to kindergartners through fourth-graders in Study 1, and to first- and third-graders in Study 2. Both studies involved four between-subjects conditions that were formed by pairing continuous and discrete target proportions with continuous and discrete choice alternatives. In Study 1, target and choice alternatives were presented simultaneously and in Study 2 target and choice alternatives were presented sequentially. In both studies, children performed significantly worse when both the target and choice alternatives were represented with discrete quantities than when either or both of the proportions involved continuous quantities. Taken together, these findings indicate that children go astray on proportional reasoning problems involving discrete units only when a numerical match is possible, suggesting that their difficulty is due to an overextension of numerical equivalence concepts to proportional equivalence problems. PMID:18793078
One-dimensional Coulomb-like problem in general case of deformed space with minimal length
NASA Astrophysics Data System (ADS)
Samar, M. I.; Tkachuk, V. M.
2016-08-01
In general case of deformed Heisenberg algebra leading to the minimal length, we present a definition of the inverse of position operator which is linear and two-sided. Our proposal is based on the functional analysis of the position operator. Using this definition, 1D Coulomb-like problem is studied. We find exactly the energy spectrum and the eigenfunctions for the 1D Coulomb-like potential in deformed space with arbitrary function of deformation. We analyze the energy spectrum for different partial cases of deformation function and find that the correction caused by the deformation highly depends on the type of the deformation function.
Coulomb Energy Differences in T = 1 Mirror Rotational Bands in 50Fe and 50Cr
NASA Astrophysics Data System (ADS)
Lenzi, S. M.; Mărginean, N.; Napoli, D. R.; Ur, C. A.; Zuker, A. P.; de Angelis, G.; Algora, A.; Axiotis, M.; Bazzacco, D.; Belcari, N.; Bentley, M. A.; Bizzeti, P. G.; Bizzeti-Sona, A.; Brandolini, F.; von Brentano, P.; Bucurescu, D.; Cameron, J. A.; Chandler, C.; de Poli, M.; Dewald, A.; Eberth, H.; Farnea, E.; Gadea, A.; Garces-Narro, J.; Gelletly, W.; Grawe, H.; Isocrate, R.; Joss, D. T.; Kalfas, C. A.; Klug, T.; Lampman, T.; Lunardi, S.; Martínez, T.; Martínez-Pinedo, G.; Menegazzo, R.; Nyberg, J.; Podolyak, Zs.; Poves, A.; Ribas, R. V.; Rossi Alvarez, C.; Rubio, B.; Sánchez-Solano, J.; Spolaore, P.; Steinhardt, T.; Thelen, O.; Tonev, D.; Vitturi, A.; von Oertzen, W.; Weiszflog, M.
2001-09-01
Gamma rays from the N = Z-2 nucleus 50Fe have been observed, establishing the rotational ground state band up to the state Jπ = 11+ at 6.994 MeV excitation energy. The experimental Coulomb energy differences, obtained by comparison with the isobaric analog states in its mirror 50Cr, confirm the qualitative interpretation of the backbending patterns in terms of successive alignments of proton and neutron pairs. A quantitative agreement with experiment has been achieved by exact shell model calculations, incorporating the differences in radii along the yrast bands, and properly renormalizing the Coulomb matrix elements in the pf model space.
Aplesnin, S. S.; Piskunova, N. I.
2011-01-15
The electronic spectrum of a trimer with a variable number of electrons has been calculated in the Hubbard model by exact diagonalization. The dependences of the chemical potential shift, magnetic moment, and energy level splitting near the chemical potential on the magnetic field, Coulomb interaction between the electrons located at the vertices of the triangle, trimer deformation, and three-center interaction have been established. The removal of magnetic degeneracy in the trimer when the intersite Coulomb and three-center interactions are taken into account and the formation of a singlet pair of electrons under trimer deformation have been detected.
If Coulomb's law were not inverse square: The charge distribution inside a solid conducting sphere
NASA Astrophysics Data System (ADS)
Spencer, Ross L.
1990-04-01
The distribution of charge between concentric conducting shells has been at the heart of the most sensitive tests of the exponent in Coulomb's law since the days of Henry Cavendish. But it appears that no one has ever answered the question of how an excess of charge would distribute itself throughout the interior of a solid conductor if Coulomb's law were other than inverse square. Spherically symmetric solutions to this problem have been found under the assumption that the potential of a point charge varies either as e-kr/r or as 1/rn.
Gulminelli, F; Chomaz, Ph; Raduta, Al H; Raduta, Ad R
2003-11-14
The liquid-gas phase transition is analyzed from the topologic properties of the event distribution in the observables space. A multicanonical formalism allows one to directly relate the standard phase transition with neutral particles to the case where the nonsaturating Coulomb interaction is present, and to interpret the Coulomb effect as a deformation of the probability distributions and a rotation of the order parameter. This formalism is applied to a statistical multifragmentation model and consequences for the nuclear multifragmentation phase transitions are drawn.
Elastic scattering of {sup 9}Li on {sup 208}Pb at energies around the Coulomb barrier
Cubero, M.; Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Lay, J. A.; Moro, A. M.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Alcorta, M.; Borge, M. J. G.; Tengblad, O.; Buchmann, L.; Shotter, A.; Walden, P.; Diget, D. G.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gomez-Camacho, J.; Mukha, I.
2011-10-28
We have studied the dynamical effects of the halo structure of {sup 11}Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated {sup 11}Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. {sup 9}Li on {sup 208}Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.
Optimum forward scattering zone for intermediate-energy Coulomb excitation experiments
NASA Astrophysics Data System (ADS)
Kumar, Rajiv; Singh, Pardeep; Kharab, Rajesh
2015-08-01
Here we present a comparative study of various schemes commonly used for the determination of the safe minimum value of the impact parameter, which decides the maximum value of forward laboratory scattering angle, in intermediate-energy Coulomb excitation experiments. We have found that these are special cases of the recently proposed parameterization scheme in Kumar Rajiv et al., Phys. Rev. C, 81 (2010) 037602. The scheme may be used to demarcate the absorption-free as well as no-flux loss zone for intermediate-energy Coulomb excitation experiments.
Ablikim, Utuq; Bomme, Cédric; Xiong, Hui; Savelyev, Evgeny; Obaid, Razib; Kaderiya, Balram; Augustin, Sven; Schnorr, Kirsten; Dumitriu, Ileana; Osipov, Timur; Bilodeau, René; Kilcoyne, David; Kumarappan, Vinod; Rudenko, Artem; Berrah, Nora; Rolles, Daniel
2016-01-01
An experimental route to identify and separate geometric isomers by means of coincident Coulomb explosion imaging is presented, allowing isomer-resolved photoionization studies on isomerically mixed samples. We demonstrate the technique on cis/trans 1,2-dibromoethene (C2H2Br2). The momentum correlation between the bromine ions in a three-body fragmentation process induced by bromine 3d inner-shell photoionization is used to identify the cis and trans structures of the isomers. The experimentally determined momentum correlations and the isomer-resolved fragment-ion kinetic energies are matched closely by a classical Coulomb explosion model. PMID:27910943
(AASERT-93) Field-Effect-Controlled, Coulomb-BlocKage Single-Electron Transistor in Silicon.
2007-11-02
imludCigdibei m , f lei reviewingI Ifistrctflnfl iiv thing~ rIUrmg Ol a m"su’e. gi~wr~ng LrIs fl Ifanil fbe data needed, and c~fO atingbl aw~d...AASERT-93) Field-Effect-Controlled, Coulomb -Blockage Single-Electron Transistor in Silicon .61103D 1-. AUTHO-R(S) 3484/TS Professor Dimitri.Antoniadis...limits of X-ray nanolithography for real devices was found. Novel I coulomb -blockade devices have been fabricated using this modified process
Scattering of Halo Nuclei at Energies below and around the Coulomb Barrier
NASA Astrophysics Data System (ADS)
Borge, M. J. G.; Cubero, M.; Fernández-García, J. P.; Moro, A. M.; Pesudo, V.; Acosta, L.; Alcorta, M.; Alvarez, M. A. G.; Bender, P.; Buchmann, L.; Diget, C. A.; Di Pietro, A.; Escrig, D.; Falou, H. A.; Figuera, P. P.; Fulton, B. R.; Fynbo, H. O. U.; Galaviz, D.; Garnsworthy, A.; Gómez-Camacho, J.; Hackman, G.; Kanungo, R.; Lay, J. A.; Madurga, M.; Martel, I.; Mukha, I.; Nilsson, T.; Rodríguez-Gallardo, M.; Rusek, K.; Sánchez-Benítez, A. M.; Rajabali, M.; Sarazin, F.; Shotter, A.; Tengblad, O.; Unsworth, C.; Walden, P.
The loosely bound structure of halo nuclei is predicted to affect the collisions with heavy targets at energies around the Coulomb barrier. We report here on the results on a series of experiments done at different facilities to study the behaviour of the scattering of the archetype of the halo nuclei: 6He, 11Li, and 11Be on heavy targets at energies below and around the Coulomb barrier. The results are interpreted in the framework of Continuum-Discretized Coupled-Channel calculations (CDCC). The departure from Rutherford scattering is larger than expected. In first approximation the effect certainly scales with the loosely bound character of the projectile.
Computational Analysis of Intermolecular Coulombic Decay Effects in DNA nucleotide Photoionization
NASA Astrophysics Data System (ADS)
Vargas, E. L.; Robertson, J.; Andrianarijaona, V. M.
2016-03-01
Intermolecular Coulombic Decay (ICD) is the process of how electrons return to their original state after excitation and how this affects their immediate environment. In a previous research presentationwe had considered the hypothetical applications of Intermolecular Coulombic Decay on the adhesiveness of coding proteins within DNA molecules. This presentation is a continuation of the previous in that the results of our DFT-based computational calculations of the ionization potentials of nucleotides and their excitation energies will be presented, as well as how they influence their surroundings. Author would like to acknowledge the PUC Student Senate for financial assistance.
A shortcut through the Coulomb gas method for spectral linear statistics on random matrices
NASA Astrophysics Data System (ADS)
Deelan Cunden, Fabio; Facchi, Paolo; Vivo, Pierpaolo
2016-04-01
In the last decade, spectral linear statistics on large dimensional random matrices have attracted significant attention. Within the physics community, a privileged role has been played by invariant matrix ensembles for which a two-dimensional Coulomb gas analogy is available. We present a critical revision of the Coulomb gas method in random matrix theory (RMT) borrowing language and tools from large deviations theory. This allows us to formalize an equivalent, but more effective and quicker route toward RMT free energy calculations. Moreover, we argue that this more modern viewpoint is likely to shed further light on the interesting issues of weak phase transitions and evaporation phenomena recently observed in RMT.
NASA Astrophysics Data System (ADS)
Ablikim, Utuq; Bomme, Cédric; Xiong, Hui; Savelyev, Evgeny; Obaid, Razib; Kaderiya, Balram; Augustin, Sven; Schnorr, Kirsten; Dumitriu, Ileana; Osipov, Timur; Bilodeau, René; Kilcoyne, David; Kumarappan, Vinod; Rudenko, Artem; Berrah, Nora; Rolles, Daniel
2016-12-01
An experimental route to identify and separate geometric isomers by means of coincident Coulomb explosion imaging is presented, allowing isomer-resolved photoionization studies on isomerically mixed samples. We demonstrate the technique on cis/trans 1,2-dibromoethene (C2H2Br2). The momentum correlation between the bromine ions in a three-body fragmentation process induced by bromine 3d inner-shell photoionization is used to identify the cis and trans structures of the isomers. The experimentally determined momentum correlations and the isomer-resolved fragment-ion kinetic energies are matched closely by a classical Coulomb explosion model.
Hamiltonian Approach to Yang-Mills Theory in Coulomb Gauge--Revisited
Reinhardt, Hugo; Campagnari, Davide R.; Leder, Markus; Burgio, Giuseppe; Quandt, Markus; Pawlowski, Jan M.; Weber, Axel
2011-05-24
I briefly review results obtained within the variational Hamiltonian approach to Yang-Mills theory in Coulomb gauge and confront them with recent lattice data. The variational approach is extended to non-Gaussian wave functionals including three- and four-gluon kernels in the exponential of the vacuum wave functional and used to calculate the three-gluon vertex. A new functional renormalization group flow equation for Hamiltonian Yang-Mills theory in Coulomb gauge is solved for the gluon and ghost propagator under the assumption of ghost dominance. The results are compared to those obtained in the variational approach.