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Sample records for ring current decay

  1. Ring current proton decay by charge exchange

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Hoffman, R. A.; Fritz, T.

    1975-01-01

    Explorer 45 measurements during the recovery phase of a moderate magnetic storm have confirmed that the charge exchange decay mechanism can account for the decay of the storm-time proton ring current. Data from the moderate magnetic storm of 24 February 1972 was selected for study since a symmetrical ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, the equatorially mirroring protons in the energy range 5 to 30 keV decayed throughout the L-value range of 3.5 to 5.0 at the charge exchange decay rate calculated by Liemohn. After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange can entirely account for the storm-time proton ring current decay, and that this mechanism must be considered in all studies involving the loss of proton ring current particles.

  2. Ring current proton decay by charge exchange

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Hoffman, R. A.; Fritz, T. A.

    1976-01-01

    Explorer 45 (S3-A) measurements were made during the recovery phase of the moderate magnetic storm of February 24, 1972, in which a symmetric ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, which is a consequence of the dissipation of the asymmetric ring current, the equatorially mirroring protons in the energy range 5-30 keV decayed throughout the L value range of 3.5-5.0 at the charge exchange decay rate calculated by Liemohn (1961). After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange is more than sufficient as a particle loss mechanism for the storm time proton ring current decay.

  3. Three-dimensional ring current decay model

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Moore, Thomas E.; Kozyra, Janet U.; Ho, George C.; Hamilton, Douglas C.

    1995-01-01

    This work is an extension of a previous ring current decay model. In the previous work, a two-dimensional kinetic model was constructed to study the temporal variations of the equatorially mirroring ring current ions, considering charge exchange and Coulomb drag losses along drift paths in a magnetic dipole field. In this work, particles with arbitrary pitch angle are considered. By bounce averaging the kinetic equation of the phase space density, information along magnetic field lines can be inferred from the equator. The three-dimensional model is used to simulate the recovery phase of a model great magnetic storm, similar to that which occurred in early February 1986. The initial distribution of ring current ions (at the minimum Dst) is extrapolated to all local times from AMPTE/CCE spacecraft observations on the dawnside and duskside of the inner magnetosphere spanning the L value range L = 2.25 to 6.75. Observations by AMPTE/CCE of ring current distributions over subsequent orbits during the storm recovery phase are compared to model outputs. In general, the calculated ion fluxes are consistent with observations, except for H(+) fluxes at tens of keV, which are always overestimated. A newly invented visualization idea, designated as a chromogram, is used to display the spatial and energy dependence of the ring current ion differential flux. Important features of storm time ring current, such as day-night asymmetry during injection and drift hole on the dayside at low energies (less than 10 keV), are manifested in the chromogram representation. The pitch angle distribution is well fit by the function, J(sub o)(1 + Ay(sup n)), where y is sine of the equatorial pitch angle. The evolution of the index n is a combined effect of charge exchange loss and particle drift. At low energies (less than 30 keV), both drift dispersion and charge exchange are important in determining n.

  4. The impact of exospheric neutral dynamics on ring current decay

    NASA Astrophysics Data System (ADS)

    Ilie, R.; Liemohn, M. W.; Skoug, R. M.; Funsten, H. O.; Gruntman, M.; Bailey, J. J.; Toth, G.

    2015-12-01

    The geocorona plays an important role in the energy budget of the Earth's inner magnetosphere since charge exchange of energetic ions with exospheric neutrals makes the exosphere act as an energy sink for ring current particles. Long-term ring current decay following a magnetic storm is mainly due to these electron transfer reactions, leading to the formation energetic neutral atoms (ENAs) that leave the ring current system on ballistic trajectories. The number of ENAs emitted from a given region of space depends on several factors, such as the energy and species of the energetic ion population in that region and the density of the neutral gas with which the ions undergo charge exchange. However, the density and structure of the exosphere are strongly dependent on changes in atmospheric temperature and density as well as charge exchange with the ions of plasmaspheric origin, which depletes the geocorona (by having a neutral removed from the system). Moreover, the radiation pressure exerted by solar far-ultraviolet photons pushes the geocoronal hydrogen away from the Earth in an anti-sunward direction to form a tail of neutral hydrogen. TWINS ENA images provide a direct measurement of these ENA losses and therefore insight into the dynamics of the ring current decay through interactions with the geocorona. We assess the influence of geocoronal neutrals on ring current formation and decay by analysis of the predicted ENA emissions using 6 different geocoronal models and simulations from the HEIDI ring current model during storm time. Comparison with TWINS ENA images shows that the location of the peak ENA enhancements is highly dependent on the distribution of geocoronal hydrogen density. We show that the neutral dynamics has a strong influence on the time evolution of the ring current populations as well as on the formation of energetic neutral atoms.

  5. A three-dimensional ring current decay model

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Moore, Thomas E.; Kozyra, Janet U.; Ho, George C.; Hamilton, Douglas C.

    1994-01-01

    This work is an extension of a previous ring current decay model. In the previous work, a two-dimensional kinetic model was constructed to study the temporal variations of the equatorially mirroring ring current ions, considering charge exchange and Coulomb drag losses along drift paths in a magnetic dipole field. In this work, particles with arbitrary pitch angle are considered. By bounce averaging the kinetic equation of the phase space density, information along magnetic field lines can be inferred from the equator. The three-dimensional model is used to simulate the recovery phase of a model great magnetic storm, similar to that which occurred in early February 1986. The initial distribution of ring current ions (at the minimum Dst) is extrapolated to all local times from AMPTE/CCE spacecraft observations on the dawn and dusk sides of the inner magnetosphere spanning the L value range L = 2.25 to 6.75. Observations by AMPTE/CCE of ring current distributions over subsequent orbits during the storm recovery phase are compared to model outputs. In general, the calculated ion fluxes are consistent with observations, except for H+ fluxes at tens of keV, which are always over-estimated. A newly-invented visualization idea, designated as a chromogram, is used to display the spatial and energy dependence of the ring current ion differential flux. Important features of storm-time ring current, such as day-night asymmetry during injection and drift hole on the dayside at low energies (less than 10 keV), are manifested in the chromogram representation. The pitch angle distribution is well fit by the function, j(sub o)(1+Ay(exp n)), where y is sine of the equatorial pitch angle. The evolution of the index n is a combined effect of charge exchange loss and particle drift. At low energies (less than 30 keV), both drift dispersion and charge exchange are important in determining n.

  6. Characteristic Time of the Magnetospheric Ring Current Decay FROM EXPIREMENT AND THEORY

    NASA Astrophysics Data System (ADS)

    Biktash(Sizova), L. Z.; Korotova, G. I.

    2006-12-01

    The magnetospheric ring current particles are the most dynamic part of the Earth's radiation belts especially during geomagnetic storms. The processes of the magnetospheric ring current decay are studied as a function of the solar wind electric field. It is shown that the ring current dissipation rate is different during the main and recovery phase of geomagnetic storms. The characteristic time of the ring current decay in the main phase is independent of storm intensity and equals 4 hours. The characteristic time of the ring current decay in a recovery phase increases with storm intensity. We examine the ring current ion lifetimes for the possible mechanisms of its decay. Coulomb scattering, charge exchange and plasma instability mechanisms are used for estimation of lifetime of electrons, protons, helium, and oxygen ions. The values of the characteristic lifetime of ring current dissipation obtained from experiment and theory are compared. It is shown that during main and recovery phase of magnetic storm the different mechanisms can play main role in dissipation of the ring current. Very short characteristic decay time during main phase of geomagnetic storms is associated with plasma instabilities. The available ion composition data of the ring current make possible to assume that the ring current decay is accounted for by ion composition variations with changing the intensity (and hence position) of the ring current and/or by a rise of energetic ion fraction on low L-shells.

  7. Inference of the ring current ion composition by means of charge exchange decay

    SciTech Connect

    Smith, P.H.; Bewtra, N.K.; Hoffman, R.A.

    1981-05-01

    The analysis of data from the Explorer 45 (S/sup 3/-A) electrostatic analyzer in the energy range 5--30 keV has provided some new results of the ring current ion composition. It has been well established that the storm time ring current has a decay time of several days, during which the particle fluxes decrease nearly monotonically. In the past, ring current studies have assumed or stated that hydrogen was the dominant ion in the earth's ring current. By analyzing the measured ion fluxes during the several day storm recovery period and assuming that beside hydrogen other ions were present and that the decays were exponential in nature, we were able to establish three separate lifetimes for the ions. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H/sup +/, O/sup +/, and He/sup +/ in the energy and L value of the data. This inference technique thus establishes the presence of measureable and appreciable quantities of oxygen and helium ions as well as protons in the storm time ring current; we also find indicatons that He/sup + +/ may also be present under these same conditions. The existence of additional ions is not rules out by this technique.

  8. Inference of the ring current ion composition by means of charge exchange decay

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Hoffman, R. A.; Bewtra, N. K.

    1981-01-01

    The analysis of data from the Explorer 45 (S3-A) electrostatic analyzer in the energy range 5-30 keV has provided some new results on the ring current ion composition. It has been well established that the storm time ring current has a decay time of several days, during which the particle fluxes decrease nearly monotonically. By analyzing the measured ion fluxes during the several day storm recovery period and assuming that beside hydrogen other ions were present and that the decays were exponential in nature, three separate lifetimes for the ions were established. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H(+), O(+) and He(+) in the energy and L value range of the data.

  9. Charge Exchange Contribution to the Decay of the Ring Current, Measured by Energetic Neutral Atoms (ENAs)

    NASA Technical Reports Server (NTRS)

    Jorgensen, A. M.; Henderson, M. G.; Roelof, E. C.; Reeves, G. D.; Spence, H. E.

    2001-01-01

    In this paper we calculate the contribution of charge exchange to the decay of the ring current. Past works have suggested that charge exchange of ring current protons is primarily responsible for the decay of the ring current during the late recovery phase, but there is still much debate about the fast decay of the early recovery phase. We use energetic neutral atom (ENA) measurements from Polar to calculate the total ENA energy escape. To get the total ENA escape we apply a forward modeling technique, and to estimate the total ring current energy escape we use the Dessler-Parker-Sckopke relationship. We find that during the late recovery phase of the March 10, 1998 storm ENAs with energies greater than 17.5 keV can account for 75% of the estimated energy loss from the ring current. During the fast recovery the measured ENAs can only account for a small portion of the total energy loss. We also find that the lifetime of the trapped ions is significantly shorter during the fast recovery phase than during the late recovery phase, suggesting that different processes are operating during the two phases.

  10. Charge Exchange Contribution to the Decay of the Ring Current, Measured by Energetic Neutral Atoms (ENAs)

    NASA Technical Reports Server (NTRS)

    Jorgensen, A. M.; Henderson, M. G.; Roelof, E. C.; Reeves, G. D.; Spence, H. E.

    2001-01-01

    In this paper we calculate the contribution of charge exchange to the decay of the ring current. Past works have suggested that charge exchange of ring current protons is primarily responsible for the decay of the ring current during the late recovery phase, but there is still much debate about the fast decay of the early recovery phase. We use energetic neutral atom (ENA) measurements from Polar to calculate the total ENA energy escape. To get the total ENA escape we apply a forward modeling technique, and to estimate the total ring current energy escape we use the Dessler-Parker-Sckopke relationship. We find that during the late recovery phase of the March 10, 1998 storm ENAs with energies greater than 17.5 keV can account for 75% of the estimated energy loss from the ring current. During the fast recovery the measured ENAs can only account for a small portion of the total energy loss. We also find that the lifetime of the trapped ions is significantly shorter during the fast recovery phase than during the late recovery phase, suggesting that different processes are operating during the two phases.

  11. Ring Current Decay During Northward Turnings of The Interplanetary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Monreal MacMahon, R.; Llop, C.; Miranda, R.

    The ring current formation and energization is thought to be the main consequence of geomagnetic storms and its strength is characterized by the Dst index which evolu- tion satisfies a simple and well-known differential equation introduced by Burton et al. (1975). Since then, several attempts and approaches have been done to study the evolution of the ring current whether introducing discrete values or continuous func- tions for the decay time involved. In this work, we study the character of the recovery phase of magnetic storms in response to well defined northward turnings of the inter- planetary magnetic field using our functional form of the decay time of ring current particles introduced previously.

  12. Inference of the ring current ion composition by means of charge exchange decay

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Bewtra, N. K.; Hoffman, R. A.

    1978-01-01

    The analysis of the measured ion fluxes during the several day storm recovery period and the assumption that beside hydrogen other ions were present and that the decays were exponential in nature, it was possible to establish three separate lifetimes for the ions. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H(+), O(+), and He(+) in the energy and L-value range of the data. This inference technique, thus, establishes the presence of measurable and appreciable quantities of oxygen and helium ions as well as protons in the storm-time ring current. Indications that He(+) may also be present under these same conditions were found.

  13. Quantum decay of the persistent current in a Josephson junction ring

    NASA Astrophysics Data System (ADS)

    Garanin, D. A.; Chudnovsky, E. M.

    2016-03-01

    We study the persistent current in a ring consisting of N ≫1 Josephson junctions threaded by the magnetic flux. When the dynamics of the ring is dominated by the capacitances of the superconducting islands the system is equivalent to the x y spin system in 1 +1 dimensions at the effective temperature T*=√{2 J U } , with J being the Josephson energy of the junction and U being the charging energy of the superconducting island. The numerical problem is challenging due to the absence of thermodynamic limit and slow dynamics of the Kosterlitz-Thouless transition. It is investigated on lattices containing up to ×106 sites. At T*≪J the quantum phase slips are frozen. The low-T* dependence of the persistent current computed numerically agrees quantitatively with the analytical formula provided by the spin-wave approximation. The high-T* behavior depends strongly on the magnetic flux and on the number of superconducting islands N . We present a detailed numerical study of the unbinding of vortex-antivortex pairs responsible for the phase slips, the superconductor-insulator transition, and evolution of the persistent current in a finite-size system.

  14. The inconsistency between proton charge exchange and the observed ring current decay

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.; Evans, D. S.

    1976-01-01

    The equatorial pitch-angle distributions of ring-current ions observed during a storm recovery phase at L values between 3 and 4 are compared with the pitch-angle distributions predicted by proton charge exchange with neutral hydrogen. Large disagreements are found, and three alternative explanations are explored. (1) A strong proton source acts to mask the effects of charge exchange. It is believed that the required strong continual source with a unique pitch-angle and energy dependence is unrealistic at these low L values. (2) Presently accepted neutral hydrogen density models have densities well over an order of magnitude too large for a storm recovery phase. No evidence is known to support the required large errors in the densities. (3) The ring current at particle energies not exceeding 50 keV was dominated by some ion species other than protons during the storm recovery phase. Such ions must have much longer lifetimes for charge exchange with hydrogen than do protons. This alternative is strongly favored, with He(+) being an attractive candidate.

  15. Ring currents in azulene

    NASA Astrophysics Data System (ADS)

    Paxton, A. T.; Todorov, T. N.; Elena, A. M.

    2009-11-01

    We propose a self consistent polarisable ion tight binding theory for the study of push-pull processes in aromatic molecules. We find that the method quantitatively reproduces ab initio calculations of dipole moments and polarisability. We apply the scheme in a simulation which solves the time dependent Schrödinger equation to follow the relaxation of azulene from the second excited to the ground states. We observe rather spectacular oscillating ring currents which we explain in terms of interference between the HOMO and LUMO states.

  16. The impact of geocoronal density on ring current development

    NASA Astrophysics Data System (ADS)

    Ilie, R.; Skoug, R. M.; Funsten, H. O.; Liemohn, M. W.; Bailey, J. J.; Gruntman, M.

    2013-07-01

    Long-term ring current decay following a magnetic storm is mainly due to charge exchange collisions of ring current ions with geocoronal neutral atoms forming energetic neutral atoms (ENAs) that leave the ring current system. Therefore, the density distribution of these cold and tenuous neutral hydrogen atoms plays a key role in the ring current recovery. TWINS ENA images provide a direct measurement of these ENA losses and therefore insight into the dynamics of the ring current decay through interactions with the geocorona. To assess the influence of geocoronal neutrals on ring current decay, we compare the predicted ENA emission using five different geocoronal models and the HEIDI ring current model to simulate the July 22, 2009 storm. We show that for high energy H+ (≥100 keV), all geocoronal models predict similar decay rates of the ring current ions. However, for low energy ions (≤100 keV), the decay rate varies significantly depending on the geocoronal density model. Comparison with TWINS ENA images shows that the location of the peak ENA enhancements is highly dependent on the distribution of geocoronal hydrogen density. The ring current topology depends greatly on the hydrogen model used, therefore knowing the H-distribution is very important in understanding how the ring current recovers following a magnetic storm.

  17. Ring current and radiation belts

    NASA Technical Reports Server (NTRS)

    Williams, D. J.

    1987-01-01

    Studies performed during 1983-1986 on the ring current, the injection boundary model, and the radiation belts are discussed. The results of these studies yielded the first observations on the composition and charge state of the ring current throughout the ring-current energy range, and strong observational support for an injection-boundary model accounting for the origins of radiation-belt particles, the ring current, and substorm particles observed at R less than about 7 earth radii. In addition, the results have demonstrated that the detection of energetic neutral atoms generated by charge-exchange interactions between the ring current and the hydrogen geocorona can provide global images of the earth's ring current and its spatial and temporal evolution.

  18. Statistical ring current of Saturn

    NASA Astrophysics Data System (ADS)

    Carbary, J. F.; Achilleos, N.; Arridge, C. S.

    2012-06-01

    The statistical ring current of Saturn has been determined from the curl of the median magnetic field derived from over 5 years of observations of the Cassini magnetometer. The main issue addressed here is the calculation of the statistical ring current of Saturn by directly computing, for the first time, the symmetrical part of the ring current J from the Maxwell equation ∇ × B = μ0J from assembling the perturbation magnetic field B from 2004 through 2010. This study validates previous studies, based on fewer data and not using ∇ × B, and shows that the ring current flows eastward (in the +ϕ or corotation direction) and extends from ˜3 RS to at least ˜20 RS (1 RS = 60,268 km), which is the vicinity of the dayside magnetopause; that the ring current has a peak strength of ˜75 pA/m2 at ˜9.5 RS; and that the ring current has a half-width of ˜1.5 RS. Two outcomes of this study are that the ring current bends northward, as suggested by the “bowl” model of Saturn's plasma sheet, and that the total ring current is 9.2 ± 1.0 MA. In the context of future endeavors, the statistical ring current presented here can be used for calculations of the magnetic field of Saturn for particle drifts, field line mapping, and J × B force.

  19. Paratropic ring currents in cubane

    NASA Astrophysics Data System (ADS)

    Havenith, Remco W. A.; Fowler, Patrick W.; Steiner, Erich

    2003-04-01

    Visualisation, at the ab initio CTOCD-DZ/RHF/6-31G ** level, of current density induced in the cubane molecule, C 8H 8, by a magnetic field along a fourfold axis shows a pair of strong face-localised paratropic ring currents in this saturated system that account for the strong deshielding effects at both face and cube centres predicted in previous calculations.

  20. Tilt stability of rotating current rings with passive conductors

    SciTech Connect

    Zweibel, E.G.; Pomphrey, N.

    1984-12-01

    We study the combined effects of rotation and resistive passive conductors on the stability of a rigid current in an external magnetic field. We present numerical and approximate analytical solutions to the equations of motion, which show that the ring is always tilt unstable on the resistive decay timescale of the conductors, although rotation and eddy currents may stabilize it over short times. Possible applications of our model include spheromaks which rotate or which are encircled by energetic particle rings.

  1. Radiation issues in a radioactive ion decay ring.

    PubMed

    Magistris, M; Silari, M

    2005-01-01

    In a beta-beam facility, a pure beam of electron neutrinos, or their antiparticles, are produced by the decay of fully stripped radioactive ions (6He and 18Ne) circulating in a storage ring. Since the beam is not extracted from the ring, all the particles will eventually be lost somewhere in the machine and thus activate the accelerator components and the surrounding concrete and rock. In particular, as nuclei change their charge in beta-decay, a large part of the particles will be lost in the arcs of the decay ring and mainly irradiate the magnets. The density of inelastic interactions of hadrons in the magnets, concrete and rock and the track-length distribution of secondary hadrons were calculated by means of the FLUKA Monte Carlo code. These values were used to estimate the induced radioactivity in the facility, the dose rates expected in the decay ring and the consequences for the environment.

  2. Oscillating pendulum decay by emission of vortex rings

    NASA Astrophysics Data System (ADS)

    Bolster, Diogo; Hershberger, Robert E.; Donnelly, Russell J.

    2010-04-01

    We have studied oscillation of a pendulum in water using spherical bobs. By measuring the loss in potential energy, we estimate the drag coefficient on the sphere and compare to data from liquid-helium experiments. The drag coefficients compare very favorably illustrating the true scaling behavior of this phenomenon. We also studied the decay of amplitude of the pendulum over time. As observed previously, at small amplitudes, the drag on the bob is given by the linear Stokes drag and the decay is exponential. For larger amplitudes, the pendulum bob sheds vortex rings as it reverses direction. The momentum imparted to these vortex rings results in an additional discrete drag on the bob. We present experiments and a theoretical estimate of this vortex-ring-induced drag. We analytically derive an estimate for a critical amplitude beyond which vortex ring shedding will occur as well as an estimate of the radius of the ring as a function of amplitude.

  3. Current double beta decay experiments

    NASA Astrophysics Data System (ADS)

    Giuliani, A.

    2005-01-01

    After an introduction about double beta decay and the deep connections between the lepton-violating channel and the neutrino properties, the most sensitive experimental approaches to the search for this rare nuclear transition are described. An overview of the experiments presently running is then given, with particular emphasis on the adopted techniques and their possible extrapolation to next-generation, higher-sensitivity experiments. The present situation about the experimental determination of the Majorana neutrino mass is presented and discussed.

  4. A dynamic, rotating ring current around Saturn.

    PubMed

    Krimigis, S M; Sergis, N; Mitchell, D G; Hamilton, D C; Krupp, N

    2007-12-13

    The concept of an electrical current encircling the Earth at high altitudes was first proposed in 1917 to explain the depression of the horizontal component of the Earth's magnetic field during geomagnetic storms. In situ measurements of the extent and composition of this current were made some 50 years later and an image was obtained in 2001 (ref. 6). Ring currents of a different nature were observed at Jupiter and their presence inferred at Saturn. Here we report images of the ring current at Saturn, together with a day-night pressure asymmetry and tilt of the planet's plasma sheet, based on measurements using the magnetospheric imaging instrument (MIMI) on board Cassini. The ring current can be highly variable with strong longitudinal asymmetries that corotate nearly rigidly with the planet. This contrasts with the Earth's ring current, where there is no rotational modulation and initial asymmetries are organized by local time effects.

  5. Plasmasphere Modeling with Ring Current Heating

    NASA Technical Reports Server (NTRS)

    Guiter, S. M.; Fok, M.-C.; Moore, T. E.

    1995-01-01

    Coulomb collisions between ring current ions and the thermal plasma in the plasmasphere will heat the plasmaspheric electrons and ions. During a storm such heating would lead to significant changes in the temperature and density of the thermal plasma. This was modeled using a time- dependent, one-stream hydrodynamic model for plasmaspheric flows, in which the model flux tube is connected to the ionosphere. The model simultaneously solves the coupled continuity, momentum, and energy equations of a two-ion (H(+) and O(+) quasineutral, currentless plasma. Heating rates due to collisions with ring current ions were calculated along the field line using a kinetic ring current model. First, diurnally reproducible results were found assuming only photoelectron heating of the thermal electrons. Then results were found with heating of the H(+) ions by the ring current during the recovery phase of a magnetic storm.

  6. Ring currents and magnetic properties of pyracylene

    NASA Astrophysics Data System (ADS)

    Fowler, P. W.; Zanasi, R.; Cadioli, B.; Steiner, E.

    1996-03-01

    A distributed-origin coupled Hartree-Fock method is used to compute the current density induced in the pyracylene (cyclopent[fg]acenaphthylene) molecule by an external magnetic field, and hence to plot the π ring currents and obtain ab initio values of the total magnetisability, 13C and 1H nuclear magnetic shieldings. The calculated map shows paramagnetic ring currents over the pentagons and diamagnetic circulation around the central naphthalenoid unit of pyracylene, and accounts semi-quantitatively for the measured difference in chemical shift between protons attached to the pentagons and hexagons of this molecule.

  7. Persistent currents in mesoscopic Fibonacci rings

    SciTech Connect

    Jin, G.J.; Wang, Z.D.; Hu, A.; Jiang, S.S.

    1997-04-01

    In the framework of a tight-binding model, we study energy spectra and persistent currents in mesoscopic Fibonacci rings threaded by a magnetic flux. It is found that the flux-dependent electron eigenenergies E({Phi}) in mesoscopic Fibonacci rings still form ``bands`` with respect to the flux {Phi}, but there is a scaling relation between the total ``bandwidth`` and the Fibonacci number. When the strength of the one-dimensional quasiperiodic potential increases, the persistent current decreases rapidly. Interestingly, for a generalized mixing model of mesoscopic Fibonacci rings, free-electron-like persistent current may appear if the number of electrons of the system takes a specific value. {copyright} {ital 1997} {ital The American Physical Society}

  8. Persistence of the ring current, 1958--1984

    SciTech Connect

    Wrenn, G.L. )

    1989-08-01

    Statistical evidence for a solar cycle modulation in storm-time ring current particle lifetimes is presented. Linear regression of Dst with respect to a{sub p}({tau}), and an optimization of {tau} to maximize correlation, gives characteristic persistence times for each year through 2.5 solar cycles. These average persistences vary between less than 10 h at solar maximum (1962, 1975) to greater than 16 h at solar maximum (1970, 1981). The analysis is biased toward the later stages of recovery when the rate of decay has reduced, but the result is not a function of mean current strength or frequency of large storms. Increased abundance of O{sup +} is postulated as the most probable explanation of longer particle lifetimes at solar maximum, this strongly supports the proposition that a large fraction of the ring current is of ionospheric origin, and underlines the importance of dynamic coupling between the ionosphere and magnetosphere during disturbed periods.

  9. Ring Current Development During Storm Main Phase

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Moore, Thomas E.; Greenspan, Marian E.

    1996-01-01

    The development of the ring current ions in the inner magnetosphere during the main phase of a magnetic storm is studied. The temporal and spatial evolution of the ion phase space densities in a dipole field are calculated using a three dimensional ring current model, considering charge exchange and Coulomb losses along drift paths. The simulation starts with a quiet time distribution. The model is tested by comparing calculated ion fluxes with Active Magnetospheric Particle Tracer Explorers/CCE measurement during the storm main phase on May 2, 1986. Most of the calculated omnidirectional fluxes are in good agreement with the data except on the dayside inner edge (L less than 2.5) of the ring current, where the ion fluxes are underestimated. The model also reproduces the measured pitch angle distributions of ions with energies below 10 keV. At higher energy, an additional diffusion in pitch angle is necessary in order to fit the data. The role of the induced electric field on the ring current dynamics is also examined by simulating a series of substorm activities represented by stretching and collapsing the magnetic field lines. In response to the impulsively changing fields, the calculated ion energy content fluctuates about a mean value that grows steadily with the enhanced quiescent field.

  10. High-current ion-ring accelerator

    SciTech Connect

    Sudan, R.N. )

    1993-03-15

    An accelerator concept is outlined which enables 10[sup 15] to 10[sup 18] ions in the form of a charge neutralized ion ring to be accelerated to GeV energies. A repetition rate of 10 Hz will deliver an average current in the range of 0.1 A.

  11. Recent Simulation Results on Ring Current Dynamics Using the Comprehensive Ring Current Model

    NASA Technical Reports Server (NTRS)

    Zheng, Yihua; Zaharia, Sorin G.; Lui, Anthony T. Y.; Fok, Mei-Ching

    2010-01-01

    Plasma sheet conditions and electromagnetic field configurations are both crucial in determining ring current evolution and connection to the ionosphere. In this presentation, we investigate how different conditions of plasma sheet distribution affect ring current properties. Results include comparative studies in 1) varying the radial distance of the plasma sheet boundary; 2) varying local time distribution of the source population; 3) varying the source spectra. Our results show that a source located farther away leads to a stronger ring current than a source that is closer to the Earth. Local time distribution of the source plays an important role in determining both the radial and azimuthal (local time) location of the ring current peak pressure. We found that post-midnight source locations generally lead to a stronger ring current. This finding is in agreement with Lavraud et al.. However, our results do not exhibit any simple dependence of the local time distribution of the peak ring current (within the lower energy range) on the local time distribution of the source, as suggested by Lavraud et al. [2008]. In addition, we will show how different specifications of the magnetic field in the simulation domain affect ring current dynamics in reference to the 20 November 2007 storm, which include initial results on coupling the CRCM with a three-dimensional (3-D) plasma force balance code to achieve self-consistency in the magnetic field.

  12. Recent Simulation Results on Ring Current Dynamics Using the Comprehensive Ring Current Model

    NASA Technical Reports Server (NTRS)

    Zheng, Yihua; Zaharia, Sorin G.; Lui, Anthony T. Y.; Fok, Mei-Ching

    2010-01-01

    Plasma sheet conditions and electromagnetic field configurations are both crucial in determining ring current evolution and connection to the ionosphere. In this presentation, we investigate how different conditions of plasma sheet distribution affect ring current properties. Results include comparative studies in 1) varying the radial distance of the plasma sheet boundary; 2) varying local time distribution of the source population; 3) varying the source spectra. Our results show that a source located farther away leads to a stronger ring current than a source that is closer to the Earth. Local time distribution of the source plays an important role in determining both the radial and azimuthal (local time) location of the ring current peak pressure. We found that post-midnight source locations generally lead to a stronger ring current. This finding is in agreement with Lavraud et al.. However, our results do not exhibit any simple dependence of the local time distribution of the peak ring current (within the lower energy range) on the local time distribution of the source, as suggested by Lavraud et al. [2008]. In addition, we will show how different specifications of the magnetic field in the simulation domain affect ring current dynamics in reference to the 20 November 2007 storm, which include initial results on coupling the CRCM with a three-dimensional (3-D) plasma force balance code to achieve self-consistency in the magnetic field.

  13. Ring current electron dynamics during geomagnetic storms based on the Van Allen Probes measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Baker, D. N.; Claudepierre, S. G.; Fennell, J. F.; Blake, J. B.; Larsen, B. A.; Skoug, R. M.; Funsten, H. O.; Friedel, R. H. W.; Reeves, G. D.; Spence, H. E.; Mitchell, D. G.; Lanzerotti, L. J.

    2016-04-01

    Based on comprehensive measurements from Helium, Oxygen, Proton, and Electron Mass Spectrometer Ion Spectrometer, Relativistic Electron-Proton Telescope, and Radiation Belt Storm Probes Ion Composition Experiment instruments on the Van Allen Probes, comparative studies of ring current electrons and ions are performed and the role of energetic electrons in the ring current dynamics is investigated. The deep injections of tens to hundreds of keV electrons and tens of keV protons into the inner magnetosphere occur frequently; after the injections the electrons decay slowly in the inner belt but protons in the low L region decay very fast. Intriguing similarities between lower energy protons and higher-energy electrons are also found. The evolution of ring current electron and ion energy densities and energy content are examined in detail during two geomagnetic storms, one moderate and one intense. The results show that the contribution of ring current electrons to the ring current energy content is much smaller than that of ring current ions (up to ~12% for the moderate storm and ~7% for the intense storm), and <35 keV electrons dominate the ring current electron energy content at the storm main phases. Though the electron energy content is usually much smaller than that of ions, the enhancement of ring current electron energy content during the moderate storm can get to ~30% of that of ring current ions, indicating a more dynamic feature of ring current electrons and important role of electrons in the ring current buildup. The ring current electron energy density is also shown to be higher at midnight and dawn while lower at noon and dusk.

  14. Radiation Belt and Ring Current Forecasting Model

    NASA Astrophysics Data System (ADS)

    Fok, M.; Khazanov, G. V.

    2001-12-01

    A model has been developed to predict the radiation belt and ring current environment. The core of this forecasting model is a kinetic model, which solves the convection-diffusion equation of particle distributions at 10 keV to MeV energy range. This forecasting model is solely driven by the solar wind and IMF conditions. We will present the model logic, and the model validation by comparing measured particle fluxes during several magnetic storms with model calculations. In addition, we will estimate the radiation dose collected during these active periods. Finally, future development of this forecasting model will be discussed.

  15. Cleft contribution to ring current formation

    SciTech Connect

    Delcourt, D.C. ); Sauvaud, J.A. ); Moore, T.E. )

    1990-12-01

    The storm time transport of ionospheric plasma from the cleft fountain to the plasma sheet and ring current is investigated by means of three-dimensional trajectory codes. Using observations to define the source location and flow rate. The authors trace test particles during a taillike to dipolelike reconfiguration of the geomagnetic field. Emphasis is placed on the behavior of heavy ions of low charge state (O{sup +}). As a result of their long periods of gyration, these ions are highly sensitive to rapid field variations and possible display transient nonadiabatic motions. It is demonstrated that O{sup +} which have originated in the high-latitude ionosphere but which find themselves in the vicinity of the equator at substorm onset can experience considerable erergization (from several keV up to several hundred keV) and pitch angle increase leading to trapping, as an effect of the induced electric field. These effects accompany a rapid earthward transport from midtail ({approximately}10-15 R{sub E}) to geosynchronous altitudes. The average particle energy and density involved suggest a substantial contribution of the cleft O{sup +} fountain to the ring current during substorms.

  16. Magnetic Field Observations of Partial Ring Current during Storm Recovery Phase

    NASA Technical Reports Server (NTRS)

    Le, Guan; Russell, C. T.; Slavin, J. A.; Lucek, E. A.

    2007-01-01

    We present results of an extensive survey of the magnetic field observations in the inner magnetosphere using 30 years of magnetospheric magnetic field data from Polar, Cluster, ISEE, and AMPTE/CCE missions. The purpose of this study is to understand the magnetic field evolution during the recovery phase of geomagnetic storms, and its implication to the ring current recovery and loss mechanisms of ring current particles. Our previous work on global ring current distribution [Le et al., 2004] has shown that a significant partial ring current is always present at all Dst levels (regardless of storm phases) even for quiet time ring current. The total current carried by the partial ring current is much stronger than (during stormtime) or at least comparable to (during quiet time) the symmetric ring current. It is now commonly believed that a strong partial ring current is formed during the storm main phase due to the enhanced earthward convection of energetic ions from nightside plasma sheet. But the presence of a strong partial ring current throughout the recovery phase remains controversial. The magnetic field generated by the ring current inflates the inner magnetosphere and causes magnetic field depressions in the equatorial magnetosphere. During the storm recovery phase, we find that the distribution of the equatorial magnetic field depression exhibits similar local time dependence as the ring current distribution obtained from the combined dataset in the earlier study. It shows that a strong partial ring current is a permanent feature throughout the recovery phase. In the early recovery phase, the partial ring current peaks near the dusk terminator as indicated by the peak of the magnetic field depression. As the recovery phase progresses, the partial ring current decays most quickly near the dusk and results in a dusk-to-midnight moving of the peak of the partial ring current. Thus the loss mechanisms work most effectively near the dusk. The magnetic field

  17. The Role of the Ring Current in Inner Magnetosphere Cross-Energy Coupling

    NASA Astrophysics Data System (ADS)

    Jordanova, V.

    2014-12-01

    The ring current plays an important role in the processes of energy transport through the inner magnetosphere into the subauroral ionosphere, and as a source of particle precipitation into the atmospheric regions located equatorward of the auroral zone. A large fraction of the solar wind energy transferred into the magnetosphere during geomagnetic storms is consumed by the buildup of the storm-time ring current. As the ring current decays during the storm recovery phase, its energy is released into the atmosphere, ionosphere, and plasmasphere causing effects such as subauroral electron temperature enhancements, detached proton arcs, and energetic neutral atom (ENA) fluxes. Ring current pressure gradients drive the Region-2 field-aligned currents that further modify the overall convection pattern and can have significant feedback on ring current dynamics. In addition, the storm-time ring current development affects radiation belt dynamics in various ways: a) it depresses the background magnetic field on the nightside, which affects the subsequent transport of radiation belt electrons, b) its electron component represents a highly variable, asymmetric, low-energy seed population of the radiation belts, and c) the unstable ring current ion and electron populations generate electromagnetic ion cyclotron (EMIC), magnetosonic, and chorus waves (with different intensities and spatial distributions) that scatter radiation belt particles. Results from recent ring current modeling studies using self-consistently calculated electric and magnetic fields that illustrate these coupling processes are presented and discussed.

  18. Investigation of ring current/storm dynamics

    SciTech Connect

    Collin, H.L.; Cladis, J.B.; Quinn, J.M.

    1991-08-31

    This study outlines the achievements of the first year of work on data acquired by the Lockheed Ion Mass Spectrometer (IMS-LO), one of the space radiation group of instruments on the Combined Release and Radiation Effects Satellite (CRRES). The purpose of IMS-LO is to study the low energy (110eV-35 keV) ion component of the ring current plasma. The primary data processing is proceeding rapidly, as is the construction of databases of validated low energy ion data. A number of events have been selected for special study and one of these has been analysed in detail. A tentative identification has been made of a new mechanism which causes loss of ions.

  19. Latitudinal dependence of nonlinear interaction between electromagnetic ion cyclotron wave and terrestrial ring current ions

    SciTech Connect

    Su, Zhenpeng Zhu, Hui; Zheng, Huinan; Xiao, Fuliang; Zhang, Min; Liu, Y. C.-M.; Shen, Chao; Wang, Yuming; Wang, Shui

    2014-05-15

    Electromagnetic ion cyclotron (EMIC) waves can lead to the rapid decay (on a timescale of hours) of the terrestrial ring current. Such decay process is usually investigated in the framework of quasi-linear theory. Here, both theoretical analysis and test-particle simulation are performed to understand the nonlinear interaction between ring current ions and EMIC waves. In particular, the dependence of the nonlinear wave-particle interaction processes on the ion initial latitude is investigated in detail. These nonlinear processes are classified into the phase trapping and phase bunching, and the phase bunching is further divided into the channel and cluster effects. Compared to the prediction of the quasi-linear theory, the ring current decay rate can be reduced by the phase trapping, increased by the channel effect phase bunching, but non-deterministically influenced by the cluster effect phase bunching. The ion initial latitude changes the occurrence of the phase trapping, modulates the transport direction and strength of the cluster effect phase bunching, and only slightly affects the channel effect phase bunching. The current results suggest that the latitudinal dependence of these nonlinear processes should be considered in the evaluation of the ring current decay induced by EMIC waves.

  20. Sources and Losses of Ring Current Ions

    NASA Technical Reports Server (NTRS)

    Chen, Sheng-Hsien; Fok, Mei-Ching H.; Angeloupoulos, Vassilis

    2010-01-01

    During geomagnetic quiet times, in-situ measurements of ring current energetic ions (few to few tens of keVs) from THEMIS spacecraft often exhibit multiple ion populations at discrete energies that extend from the inner magnetosphere to the magnetopause at dayside or plasma sheet at nightside. During geomagnetic storm times, the levels of fluxes as well as the mean energies of these ions elevated dramatically and the more smooth distributions in energies and distances during quiet times are disrupted into clusters of ion populations with more confined spatial extends. This reveals local plasma heating processes that might have come into play. Several processes have been proposed. Magnetotail dipolarization, sudden enhancement of field-aligned current, local current disruptions, and plasma waves are possible mechanisms to heat the ions locally as well as strong convections of energetic ions directly from the magnetotail due to reconnections. We will examine two geomagnetic storms on October 11, 2008 and July 22, 2009 to reveal possible heating mechanisms. We will analyze in-situ plasma and magnetic field measurements from THEMIS, GOES, and DMSP for the events to study the ion pitch angle distributions and magnetic field perturbations in the auroral ionosphere and inner magnetosphere where the plasma heating processes occur.

  1. Magnetic-field decay of three interlocked flux rings with zero linking number.

    PubMed

    Del Sordo, Fabio; Candelaresi, Simon; Brandenburg, Axel

    2010-03-01

    The resistive decay of chains of three interlocked magnetic flux rings is considered. Depending on the relative orientation of the magnetic field in the three rings, the late-time decay can be either fast or slow. Thus, the qualitative degree of tangledness is less important than the actual value of the linking number or, equivalently, the net magnetic helicity. Our results do not suggest that invariants of higher order than that of the magnetic helicity need to be considered to characterize the decay of the field.

  2. The magnetospheric disturbance ring current as a source for probing the deep earth electrical conductivity

    USGS Publications Warehouse

    Campbell, W.H.

    1990-01-01

    Two current rings have been observed in the equatorial plane of the earth at times of high geomagnetic activity. An eastward current exists between about 2 and 3.5 earth radii (Re) distant, and a larger, more variable companion current exists between about 4 and 9 Re. These current regions are loaded during geomagnetic substorms. They decay, almost exponentially, after the cessation of the particle influx that attends the solar wind disturbance. This review focuses upon characteristics needed for intelligent use of the ring current as a source for induction probing of the earth's mantle. Considerable difficulties are found with the assumption that Dst is a ring-current index. ?? 1990 Birkha??user Verlag.

  3. Aromatic and antiaromatic ring currents in a molecular nanoring

    NASA Astrophysics Data System (ADS)

    Peeks, Martin D.; Claridge, Timothy D. W.; Anderson, Harry L.

    2016-12-01

    Aromatic and antiaromatic molecules—which have delocalized circuits of [4n + 2] or [4n] electrons, respectively—exhibit ring currents around their perimeters. The direction of the ring current in an aromatic molecule is such as to generate a magnetic field that opposes the external field inside the ring (a ‘diatropic’ current), while the ring current in an antiaromatic molecule flows in the reverse direction (‘paratropic’). Similar persistent currents occur in metal or semiconductor rings, when the phase coherence of the electronic wavefunction is preserved around the ring. Persistent currents in non-molecular rings switch direction as a function of the magnetic flux passing through the ring, so that they can be changed from diatropic (‘aromatic’) to paratropic (‘antiaromatic’) simply by changing the external magnetic field. As in molecular systems, the direction of the persistent current also depends on the number of electrons. The relationship between ring currents in molecular and non-molecular rings is poorly understood, partly because they are studied in different size regimes: the largest aromatic molecules have diameters of about one nanometre, whereas persistent currents are observed in microfabricated rings with diameters of 20-1,000 nanometres. Understanding the connection between aromaticity and quantum-coherence effects in mesoscopic rings provides a motivation for investigating ring currents in molecules of an intermediate size. Here we show, using nuclear magnetic resonance spectroscopy and density functional theory, that a six-porphyrin nanoring template complex, with a diameter of 2.4 nanometres, is antiaromatic in its 4+ oxidation state (80 π electrons) and aromatic in its 6+ oxidation state (78 π electrons). The antiaromatic state has a huge paramagnetic susceptibility, despite having no unpaired electrons. This work demonstrates that a global ring current can be promoted in a macrocycle by adjusting its oxidation state

  4. Evolution of the ring current during two geomagnetic storms

    SciTech Connect

    Lui, A.T.Y.; McEntire, R.W.; Krimigis, S.M.

    1987-07-01

    The progressive developments in the radial profiles of the particle pressure, plasma beta, and electric currents of the storm time ring current are investigated with data from the medium energy particle analyzer on the AMPTE Charged Particle Explorer spacecraft. Measurements of ions from 25 keV to 1 MeV, which carry 70--85% of the energy density of the entire ring current population, are used in this work. Two geomagnetic storms in September of 1984 are selected and four traversals of the equatorial ring current region during the course of each storm are studied. It is shown that enhancements in the particle pressure occur initially in the outer region and reach the inner region in the late phase of the storm. Structures suggestive of multiple particle injections are seen in the pressure profile. The leading and trailing edges of the particle injection structures are associated, respectively, with the depressions and enhancements of the westward current densities of the ring current. Plasma beta occasionally increases to values of the order of 1 in some regions of the ring current from prestorm values of the order of 0.1 or less. It is also found that the location of the maximum ring current particle pressure can be several earth radii from where the most intense westward ring current flows. This is a consequence of the dominance of pressure gradient current over the current associated with the magnetic field line curvature and particle anisotropy. copyright American Geophysical Union 1987

  5. Transport currents measured in ring samples: test of superconducting weld

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Claus, H.; Chen, L.; Paulikas, A. P.; Veal, B. W.; Olsson, B.; Koshelev, A.; Hull, J.; Crabtree, G. W.

    2001-02-01

    The critical current densities in bulk melt-textured YBa 2Cu 3O x and across superconducting “weld” joints are measured using scanning Hall probe measurements of the trapped magnetic field in ring samples. With this method, critical current densities are obtained without the use of electrical contacts. Large persistent currents are induced in ring samples at 77 K, after cooling in a 3 kG field. These currents can be determined from the magnetic field they produce. At 77 K a supercurrent exceeding 2000 A (about 10 4 A/cm 2) was induced in a 2 cm diameter ring; this current produces a magnetic field exceeding 1.5 kG in the bore of the ring. We demonstrate that when a ring is cut, and the cut is repaired by a superconducting weld, the weld joint can transmit the same high supercurrent as the bulk.

  6. Space Weather Effects Produced by the Ring Current Particles

    NASA Astrophysics Data System (ADS)

    Ganushkina, Natalia; Jaynes, Allison; Liemohn, Michael

    2017-10-01

    One of the definitions of space weather describes it as the time-varying space environment that may be hazardous to technological systems in space and/or on the ground and/or endanger human health or life. The ring current has its contributions to space weather effects, both in terms of particles, ions and electrons, which constitute it, and magnetic and electric fields produced and modified by it at the ground and in space. We address the main aspects of the space weather effects from the ring current starting with brief review of ring current discovery and physical processes and the Dst-index and predictions of the ring current and storm occurrence based on it. Special attention is paid to the effects on satellites produced by the ring current electrons. The ring current is responsible for several processes in the other inner magnetosphere populations, such as the plasmasphere and radiation belts which is also described. Finally, we discuss the ring current influence on the ionosphere and the generation of geomagnetically induced currents (GIC).

  7. The Ring Current Response to Solar and Interplanetary Storm Drivers

    NASA Astrophysics Data System (ADS)

    Mouikis, C.; Kistler, L. M.; Bingham, S.; Kronberg, E. A.; Gkioulidou, M.; Huang, C. L.; Farrugia, C. J.

    2014-12-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), corotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure, in turn, change the global magnetic field, controlling the transport of the radiation belts. To quantitatively determine the field changes during a storm throughout the magnetosphere, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. Because the measured ring current energy spectra depend not only on local processes, but also on the history of the ions along their entire drift path, measurements of ring current energy spectra at two or more locations can be used to strongly constrain the time dependent magnetic and electric fields. In this study we use data predominantly from the Cluster and the Van Allen Probes, covering more than a full solar cycle (from 2001 to 2014). For the period 2001-2012, the Cluster CODIF and RAPID measurements of the inner magnetosphere are the primary data set used to monitor the storm time ring current variability. After 2012, the Cluster data set complements the data from the Van Allen Probes HOPE and RBSPICE instruments, providing additional measurements from different MLT and L shells. Selected storms from this periods, allow us to study the ring current dynamics and pressure changes, as a function of L shell, magnetic local time, and the type of interplanetary disturbances.

  8. Motion and decay of vortex rings submerged in a rotational flow

    NASA Technical Reports Server (NTRS)

    Ishii, K.; Liu, C. H.

    1987-01-01

    The interaction between vortex rings of finite strength and an axisymmetric rotational background flow is studied by a singular perturbation method, because it is difficult to use a finite-difference method to analyze the viscous decay in the small core of a vortex ring. The analysis is carried out by combining a composite solution of a vortex ring and an unsteady Euler solution for the background rotational flow. Using the method of averaging, a numerical scheme is developed to obtain an Euler solution in which the grid and time-step sizes depend solely on the length and velocity scales of the background flow. Numerical results are presented to illustrate the interaction between the trajectories and decay rates of the vortex rings and the background rotational flow.

  9. Multistep Dst development and ring current composition changes during the 4-6 June 1991 magnetic storm

    NASA Astrophysics Data System (ADS)

    Kozyra, J. U.; Liemohn, M. W.; Clauer, C. R.; Ridley, A. J.; Thomsen, M. F.; Borovsky, J. E.; Roeder, J. L.; Jordanova, V. K.; Gonzalez, W. D.

    2002-08-01

    The 4-6 June 1991 magnetic storm, which occurred during solar maximum conditions, is analyzed to investigate two observed features of magnetic storms that are not completely understood: (1) the mass-dependent decay of the ring current during the early recovery phase and (2) the role of preconditioning in multistep ring current development. A kinetic ring current drift-loss model, driven by dynamic fluxes at the nightside outer boundary, was used to simulate this storm interval. A strong partial ring current developed and persisted throughout the main and early recovery phases. The majority of ions in the partial ring current make one pass through the inner magnetosphere on open drift paths before encountering the dayside magnetopause. The ring current exhibited a three-phase decay in this storm. A short interval of charge-exchange loss constituted the first phase of the decay followed by a classical two-phase decay characterized by an abrupt transition between two very different decay timescales. The short interval dominated by charge-exchange loss occurred because an abrupt northward turning of the interplanetary magnetic field (IMF) trapped ring current ions on closed trajectories, and turned-off sources and ``flow-out'' losses. If this had been the end of the solar wind disturbance, decay timescales would have gradually lengthened as charge exchange preferentially removed the short-lived species; a distinctive two-phase decay would not have resulted. However, the IMF turned weakly southward, drift paths became open, and a standard two-phase decay ensued as the IMF rotated slowly northward again. As has been shown before, a two-phase decay is produced as open drift paths are converted to closed in a weakening convection electric field, driving a transition from the fast flow-out losses associated with the partial ring current to the slower charge-exchange losses associated with the trapped ring current. The open drift path geometry during the main phase and

  10. Perimeter ring currents in benzenoids from Pauling bond orders.

    PubMed

    Fowler, Patrick W; Myrvold, Wendy; Jenkinson, Daniel; Bird, William H

    2016-04-28

    It is shown that the ring currents in perimeter hexagonal rings of Kekulean benzenoids, as estimated within the Randić conjugated-circuit model, can be calculated directly without tedious pairwise comparison of Kekulé structures or Kekulé counting for cycle-deleted subgraphs. Required are only the Pauling bond orders of perimeter bonds and the number of Kekulé structures of the benzenoid, both readily available from the adjacency matrix of the carbon skeleton. This approach provides easy calculation of complete current maps for benzenoids in which every face has at least one bond on the perimeter (as in the example of cata-condensed benzenoids), and allows qualitative evaluation of the main ring-current contributions to (1)H chemical shifts in general benzenoids. A combined Randić-Pauling model for correlation of ring current and bond length through bond order is derived and shown to be consistent with resilience of current under bond alternation.

  11. Dawn-dusk asymmetries in the magnetopause and ring current.

    NASA Astrophysics Data System (ADS)

    Haaland, S.

    2014-12-01

    Motion of charged particles in the Earth's magnetosphere sets up a system of currents. Current continuity requires that these currents are closed, either locally or via other current systems. We have investigated whether magnetopause surface currents can contribute to ring current closure. Using 10 years of measurements from the Cluster constellation of spacecraft, we calculated the magnetopause current density for a large number of flank magnetopause traversals. For each event, we also consulted sectorial ring current indices, derived from SuperMAG - a large constellation of ground based magnetometer stations. SuperMAG results show a significant and persistent dawn-dusk asymmetry in ground magnetic perturbations which indicates a more intense ring current on the dusk side. The asymmetries become more pronounced during disturbed magnetospheric conditions, indicating an increased divergence of the current and closure through other current systems. A similar response to geomagnetic activity is also observed at the magnetopause. Duskside magnetopause current densities are generally higher than their dawnside counterparts, and the magnetopause asymmetry becomes more pronounced during disturbed conditions. Although the two current systems are related to different processes - gradient drift of energetic plasma sheet particles for the ring current and a surface current due to differential motion of ions and electrons inside the magnetopause interface for the magnetopause current - the results demonstrate a mutual relation between the two current systems.

  12. Large transient fault current test of an electrical roll ring

    NASA Technical Reports Server (NTRS)

    Yenni, Edward J.; Birchenough, Arthur G.

    1992-01-01

    The space station uses precision rotary gimbals to provide for sun tracking of its photoelectric arrays. Electrical power, command signals and data are transferred across the gimbals by roll rings. Roll rings have been shown to be capable of highly efficient electrical transmission and long life, through tests conducted at the NASA Lewis Research Center and Honeywell's Satellite and Space Systems Division in Phoenix, AZ. Large potential fault currents inherent to the power system's DC distribution architecture, have brought about the need to evaluate the effects of large transient fault currents on roll rings. A test recently conducted at Lewis subjected a roll ring to a simulated worst case space station electrical fault. The system model used to obtain the fault profile is described, along with details of the reduced order circuit that was used to simulate the fault. Test results comparing roll ring performance before and after the fault are also presented.

  13. Perspective of the study on the ring current - past, present and future

    NASA Astrophysics Data System (ADS)

    Ebihara, Y.

    2016-12-01

    The study of the ring current has a long history going back to the early 20th century. The ring current was predicted by Carl Stoermer to explain the equatorward movement of the auroral zone during magnetic storms. In 1917, Adolf Schmidt introduced the concept of the ring current to explain the global decrease of the geomagnetic field. Since then, number of studies have been accomplished in the context of the growth and recovery of magnetic storms. Observations have shown that protons and oxygen ions with energies 1 - 100 keV significantly increase during the storm main phase, which are most likely the major contributor to the storm-time ring current. When the loss of the ions dominates the injection of them, the storm recovery phase takes place. Immediate problems are the origin, transport and loss of the ions. All these relevant processes are essential to understand the growth and decay of the ring current. Derived problems, for example, include the entry of solar wind plasma into the magnetosphere, the outflow of ionospheric ions, generation of the convection electric field, influence of substorm-associated electric field, and pitch angle scattering of ions. Recalling that the ring current is the diamagnetic current, we shall consider the force balance and stress carefully. Generation of field-aligned currents is one of the consequences, which might redistribute the state of the inner magnetosphere including the plasmasphere, the ring current and the radiation belts. The ring current may also have a large influence on the geomagnetically induced current (GIC) on the ground at mid- and low-latitudes. The magnetic storms can be easily identified by looking at magnetograms, but the processes behind the magnetic storms cannot be easily understood because the processes depend on each other. From this sense, we shall pay much attention to the detailed function of each process as well as its role on the overall system. Dealing with the ring current as a complex system

  14. Global Magnetospheric Evolution Effected by Sudden Ring Current Injection

    NASA Astrophysics Data System (ADS)

    Park, Geunseok; No, Jincheol; Kim, Kap-Sung; Choe, Gwangson; Lee, Junggi

    2016-04-01

    The dynamical evolution of the Earth's magnetosphere loaded with a transiently enhanced ring current is investigated by global magnetohydrodynamic simulations. Two cases with different values of the primitive ring current are considered. In one case, the initial ring current is strong enough to create a magnetic island in the magnetosphere. The magnetic island readily reconnects with the earth-connected ambient field and is destroyed as the system approaches a steady equilibrium. In the other case, the initial ring current is not so strong, and the initial magnetic field configuration bears no magnetic island, but features a wake of bent field lines, which is smoothed out through the relaxing evolution of the magnetosphere. The relaxation time of the magnetosphere is found to be about five to six minutes, over which the ring current is reduced to about a quarter of its initial value. Before reaching a quasi-steady state, the magnetosphere is found to undergo an overshooting expansion and a subsequent contraction. Fast and slow magnetosonic waves are identified to play an important role in the relaxation toward equilibrium. Our study suggests that a sudden injection of the ring current can generate an appreciable global pulsation of the magnetosphere.

  15. Rheology of Rings: Current Status and Future Challenges

    NASA Astrophysics Data System (ADS)

    McKenna, Gregory

    Understanding the dynamics of circular or ring-like polymers has been a subject of investigation since the 1980s and is one which remains an area that is not fully understood. Part of the reason for this is the difficulty of making synthetic rings of sufficient size to establish the nature of the entanglement dynamics, if entanglements even exist in these materials. Furthermore, there is now strong evidence that small amounts of linear impurities can impact the dynamics. Hence, one of the major challenges to our understanding of ring dynamics is to make large molecular weight rings of sufficient purity that the dynamics of the rings themselves can be determined. In the present work the current state of understanding of the dynamics of rings is outlined and current work from our group of collaborators to make extremely large circular polymers using Echeverria Coli as a route to make pure rings (circular DNA) in sufficient quantity and size to determine the dynamics of these materials will be shown. First results of ring dynamics in dilute solution are presented and new results on concentrated and entangled solutions will be discussed. Remaining challenges will be elucidated. Partially supported by the John R. Bradford Endowment and the Paul Whitfield Horn Professorship at Texas Tech University.

  16. Current loop decay in Rutherford-type cables

    SciTech Connect

    Akhmetov, A.A.; Devred, A.; Schermer, R.I.; Mints, R.G.

    1993-05-01

    Recent measurements of superconducting panicle accelerator magnets made of multistrand Rutherford-type cable have shown that the magnetic field and its main harmonics oscillate along the magnet axis with a wavelength nearly equal to the cable transposition. It was also observed that, at low transport current, the periodic magnetic pitch length. It was also observed that, at low transport current, the periodic magnetic field patterns can persist without any significant decay for more than 12 hours. The coincidence of the wavelength of the magnetic field oscillations with the cable transposition pitch suggests that slowly decaying current loops exist in the cable even at zero transport current. These loops consist of currents flowing along the cable through one set of strands and returning through another set of strands. In this paper, we consider the process of current loop decay in a Rutherford-type cable.

  17. Relativistic persistent currents in ideal Aharonov-Bohm rings

    NASA Astrophysics Data System (ADS)

    Cotăescu, Ion I.; Băltăţeanu, Doru-Marcel; Cotăescu, Ion

    2016-11-01

    The exact solutions of the complete Dirac equation for fermions moving in ideal Aharonov-Bohm rings are used for deriving the exact expressions of the relativistic partial currents. It is shown that as in the nonrelativistic case, these currents can be related to the derivative of the fermion energy with respect to the flux parameter. A specific relativistic effect is the saturation of the partial currents for high values of the total angular momentum. Based on this property, the total relativistic persistent current at T = 0 is evaluated giving its analytical expression and showing how this depends on the ring parameters.

  18. Spatial and temporal evolution of strom ring current

    NASA Astrophysics Data System (ADS)

    Shen, Chao; Rong, Zhaojin; Liu, Zhenxing; Zeng, Gang; Li, Xinlin; Ji, Yong; Yang, Yanyan

    Magnetic storms are the strongest activities in the magnetosphere. The main characteristics of the magnetic storms are the ring current containing huge kinetic and magnetic energies and strong current and leading to the significant depression of the geomagnetic field on the ground. Based on the continuous magnetic field measurements of the multiple ground observatories, the structure of the geomagnetic field disturbance and its temporal variations have been investigated, so as to deduce the evolution of the storm ring current. Assuming the geomagnetic field disturbance around Earth is linear in space, the gradient of the corrected H component is obtained from the multiple ground observations. It is found that, the maximum difference of the corrected H component around the Earth surface, as calculated by the gradient of the corrected H component multiplied by the Earth diameter, well represents the asymmetric index Asy-H, but is actually more sensitive to the substorm activities than the Asy-H index. The anti-direction of the gradient of the corrected H component may be regarded as pointing to the position of the maximum partial ring current. It is shown that, for the ordinary storms (Dst>-200nT) (which may be caused by CIRs, long lasting fast solar wind flows, or prolonged south IMF, etc), the maximum partial ring current is located around the duskside during the main phase and the earlier stage of the recovery phase. At the later stage of the recovery phase, the position of the maximum partial ring current keeps rotating eastward, indicating the energetic electrons may play a significant role and the main ring current carriers may be the electrons at this stage. For the severe storms (Dst<-200nT), the position of the maximum partial ring current is not so regular, and there is the evidence that the injected electrons may contribute significantly to the ring current during the main phase of supper storms. Based on physical considerations, this investigation also

  19. Modeling the near-Earth interaction between ring current ions and exospheric neutrals: escape through energetic neutral atoms (ENAs)

    NASA Astrophysics Data System (ADS)

    LLera, K.; Goldstein, J.; McComas, D. J.; Valek, P. W.

    2016-12-01

    The two major loss processes for ring current decay are precipitation and energetic neutral atoms (ENAs). Since the exospheric neutral density increases with decreasing altitudes, precipitating ring current ions (reaching down to 200 - 800 km in altitude) also produce low-altitude ENA signatures that can be stronger than the ring current emission at equatorial distances ( 2 - 9 Re). The higher density results in multiple collisions between the ring current ions and exospheric oxygen. The affect on hydrogen ions is the focus of this study. Since the H particle sustains energy loss ( 36 eV) at each neutralizing or re-ionizing interaction, the escaped ENAs do not directly reflect the ring current properties. We model the energy loss due to multiple charge exchange and electron stripping interactions of 1 - 100 keV precipitating ring current ions undergo before emerging as low-altitude ENAs. The H particle is either an ion or an ENA throughout the simulation. Their lifetime is analytically determined by the length of one mean free path. We track the ion state with Lorentz motion while the ENA travels ballistically across the geomagnetic field. Our simulations show the energy loss is greater than 20% for hydrogen ring current ions below 30 keV (60 keV for the simulations that wander equatorward). This is the first quantification of the energy loss associated with the creation of low-altitude ENAs. Our model (currently constrained in the meridional plane) has revealed characteristics on how precipitation is affected by the near-Earth neutral exosphere. This ion-neutral interaction removes particles from the loss cone but promotes loss through ENA generation. These findings should be implemented in models predicting the ring current decay and used as an analysis tool to reconstruct the ring current population from observed low-altitude ENAs.

  20. Numerical Simulations of the Ring Current During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Chen, M. W.; Lemon, C.; Guild, T. B.; Schulz, M.; Roeder, J. L.; Lui, A.; Keesee, A. M.; Goldstein, J.; Le, G.; Rodriguez, J. V.

    2012-12-01

    Recent progress in ring current modeling has shown the importance of a self-consistent treatment of particle transport along with magnetic and electric fields in the inner magnetosphere. The ring current intensity and spatial distribution are significantly affected by variations in the plasma sheet (the major source to the ring current), the cross polar cap potential, and compressions and expansions of the magnetosphere. We simulate the ion and electron ring current and plasma sheet by using the magnetically and electrically self-consistent Rice Convection Model-Equilibrium [Lemon et al., JGR, 2004] with a time-varying magnetopause driven by upstream solar wind and interplanetary magnetic (IMF) conditions and with time-varying plasma sheet distributions as boundary conditions. Examples of detailed comparisons of simulated storm events with in-situ magnetic intensities (e. g., GOES, Polar/MPA, or THEMIS) and proton flux spectra (e. g., LANL/MPA and SOPA, Polar/CAMMICE, or THEMIS) and energetic neutral atom (ENA) fluxes (e. g., TWINS) will be shown. We will also present comparisons of observed electron flux spectra with simulations based on a few simple electron loss models. These data-model comparisons test the ability of our model to characterize the ring current environment and the storm-time inner magnetospheric magnetic field.

  1. North Brazil Current Ring Collisions With the Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Fratantoni, D. M.; Richardson, P. L.

    2002-12-01

    The earth's largest ocean rings are spawned near 8°N in the western tropical Atlantic from the equator-crossing North Brazil Current (NBC). NBC rings, which can exceed 450 km in diameter and 2000 m in vertical extent, translate northwestward parallel to the South American coastline until they collide with the Lesser Antilles in the southeastern Caribbean Sea. The rings entrain filaments of nutrient- and sediment-rich Amazon and Orinoco River discharge, impact the distribution of icthyoplankton, and pose a physical threat to expanding offshore oil and gas exploration. The six rings generated annually are also responsible for up to one-third of the equatorial-to-subtropical mass and heat transport associated with the Atlantic meridional overturning circulation, a fundamental component of the earth climate system. Recent RAFOS float and surface drifter trajectories illustrate the translation and structural evolution of several NBC rings and enable the determination of the downstream fate of South Atlantic water trapped within the ring core. These results indicate that NBC rings do not enter the Caribbean Sea intact as simulated by numerical ocean models but are instead sheared apart through topographic interaction along the eastern flank of the Lesser Antilles.

  2. The Role of Ring Current on Slot Region Penetration

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Elkington, Scot

    2006-01-01

    During magnetic quiet times, the inner belt, slot region and the outer belt are well defined regions. However, during some major storms, outer belt particles penetrate inward and significantly fill the slot region. In some extreme events, the outer belt particles travel through the slot and create a new belt in the inner region that persists from months to years. In this paper, we examine the role of the ring current on this radiation belt penetration into the slot region. The storm-time intensification of the ring current produces strong magnetic depression in the inner magnetosphere. This perturbation and its fluctuation enhance the radial transport and diffusion of the outer radiation belt particles. We perform kinetic and test-particle calculations to quantitatively assess the effects of the ring current field on filling of the slot region. Simulation results during major storms will be presented and discussed.

  3. Ring Current Ion Coupling with Electromagnetic Ion Cyclotron Waves

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.

    2002-01-01

    A new ring current global model has been developed for the first time that couples the system of two kinetic equations: one equation describes the ring current (RC) ion dynamic, and another equation describes wave evolution of electromagnetic ion cyclotron waves (EMIC). The coupled model is able to simulate, for the first time self-consistently calculated RC ion kinetic and evolution of EMIC waves that propagate along geomagnetic field lines and reflect from the ionosphere. Ionospheric properties affect the reflection index through the integral Pedersen and Hall coductivities. The structure and dynamics of the ring current proton precipitating flux regions, intensities of EMIC, global RC energy balance, and some other parameters will be studied in detail for the selected geomagnetic storms. The space whether aspects of RC modelling and comparison with the data will also be discussed.

  4. Ring Current Ion Coupling with Electromagnetic Ion Cyclotron Waves

    NASA Technical Reports Server (NTRS)

    Khazanov. G. V.; Gamayunov, K. V.; Jordanova, V. K.; Six, N. Frank (Technical Monitor)

    2002-01-01

    A new ring current global model has been developed that couples the system of two kinetic equations: one equation describes the ring current (RC) ion dynamic, and another equation describes wave evolution of electromagnetic ion cyclotron waves (EMIC). The coupled model is able to simulate, for the first time self-consistently calculated RC ion kinetic and evolution of EMIC waves that propagate along geomagnetic field lines and reflect from the ionosphere. Ionospheric properties affect the reflection index through the integral Pedersen and Hall conductivities. The structure and dynamics of the ring current proton precipitating flux regions, intensities of EMIC global RC energy balance, and some other parameters will be studied in detail for the selected geomagnetic storms.

  5. The Role of Ring Current on Slot Region Penetration

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Elkington, Scot

    2006-01-01

    During magnetic quiet times, the inner belt, slot region and the outer belt are well defined regions. However, during some major storms, outer belt particles penetrate inward and significantly fill the slot region. In some extreme events, the outer belt particles travel through the slot and create a new belt in the inner region that persists from months to years. In this paper, we examine the role of the ring current on this radiation belt penetration into the slot region. The storm-time intensification of the ring current produces strong magnetic depression in the inner magnetosphere. This perturbation and its fluctuation enhance the radial transport and diffusion of the outer radiation belt particles. We perform kinetic and test-particle calculations to quantitatively assess the effects of the ring current field on filling of the slot region. Simulation results during major storms will be presented and discussed.

  6. Ring Current Modeling in a Realistic Magnetic Field Configuration

    NASA Technical Reports Server (NTRS)

    Fok, M.-C.; Moore, T. E.

    1997-01-01

    A 3-dimensional kinetic model has been developed to study the dynamics of the storm time ring current in a dipole magnetic field. In this paper, the ring current model is extended to include a realistic, time-varying magnetic field model. The magnetic field is expressed as the cross product of the gradients of two Euler potentials and the bounce-averaged particle drifts are calculated in the Euler potential coordinates. A dipolarization event is modeled by collapsing a tail-like magnetosphere to a dipole-like configuration. Our model is able to simulate the sudden enhancements in the ring current ion fluxes and the corresponding ionospheric precipitation during the substorm expansion.

  7. Study of Ring Current Dynamics During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Jordanova, Vania K.

    2000-01-01

    This research program considered modeling the dynamical evolution of the ring current during several geomagnetic storms. The first year (6/01/1997-5/31/1998) of this successful collaborative research between the University of New Hampshire (UNH) and the University of California Los Angeles (UCLA) was supported by NASA grant NAG5-4680. The second and third years (6/01/1998-5/31/2000) were funded at UNH under NASA grant NAG5-7368. Research work at UNH concentrated on further development of a kinetic model to treat all of the important physical processes that affect the ring current ion population during storm conditions. This model was applied to simulate ring current development during several International Solar-Terrestrial Physics (ISTP) events, and the results were directly compared to satellite observations. A brief description of our major accomplishments and a list of the publications and presentations resulting from this effort are given.

  8. Empirical Model of the Pressure in the Earth's Ring Current

    NASA Astrophysics Data System (ADS)

    Sotirelis, T.; Gkioulidou, M.; Ukhorskiy, A. Y.; MacDonald, E.

    2014-12-01

    Plasma in the inner magnetosphere produces the Earth's ring current through its pressure. Changes in the plasma pressure dramatically effects the ring current, and the magnetic field which guides particle motion. Here, the pressure in the inner magnetosphere is empirically modeled using Van Allen Probes observations by the RBSPICE and ECT-HOPE instruments. The radial and local-time dependence of both the parallel and perpendicular components of plasma pressure are assessed and the contributions of Helium and Oxygen are measured. Correlation studies are used to further understand the causal roles played by various drivers. Simultaneous observations from the two Van Allen Probes permit an understanding of global versus local variations.

  9. The Consequences of Saturn’s Rotating Asymmetric Ring Current

    NASA Astrophysics Data System (ADS)

    Southwood, D. J.; Kivelson, M. G.

    2009-12-01

    The plasma and field behavior in the dipolar region of the Saturnian magnetosphere is described, based primarily on interpretation of the magnetic field behavior measured by the Cassini spacecraft. Previous authors, such as Provan and Khurana, have pointed out that the regular pulses in field strength at around 10.8 hrs period detected in this region imply the existence not only of a symmetric ring current but also of a partial ring current. Once spacecraft motion in local time has been allowed for, one finds a close to sinusoidal variation with azimuth and time of the magnetic signal. Hence the partial ring current appears to quasi-rigidly rotate about the planetary axis at the same 10.8 hr period as the pulsing of the Saturn kilometric radiation. We point out that, independent of whether the excess current is due to asymmetry in flux tube population or in plasma beta (pressure normalized to field pressure), such a current gives rise to a rotating circulation system. The compressional field pattern is consistent with an m = 1 pattern of circulation. The fairly uniform inner magnetosphere cam magnetic signature predicted on the basis of inner magnetosphere transverse field components in our past work is modified in a systematic way by the partial ring current effects. The circulation due to the partial ring current has its own set of distributed field aligned currents (FACs). The rotating transverse perturbation field components are twisted by the FACs so that the radial field is reduced at low L-shells and increased at larger L. Overall the cam field is depressed at low L and enhanced as one approaches the boundary of the cam region at L = 10-12. In practice the system must also respond to some local time effects. Loss of plasma is easier on the night-side and flanks than on the day-side and so a day-night asymmetry is imposed tending to increase the perturbation field amplitudes by night. The FACs driven by the asymmetric ring current should be broadly

  10. Modeling the Inner Magnetosphere: Radiation Belts, Ring Current, and Composition

    NASA Technical Reports Server (NTRS)

    Glocer, Alex

    2011-01-01

    The space environment is a complex system defined by regions of differing length scales, characteristic energies, and physical processes. It is often difficult, or impossible, to treat all aspects of the space environment relative to a particular problem with a single model. In our studies, we utilize several models working in tandem to examine this highly interconnected system. The methodology and results will be presented for three focused topics: 1) Rapid radiation belt electron enhancements, 2) Ring current study of Energetic Neutral Atoms (ENAs), Dst, and plasma composition, and 3) Examination of the outflow of ionospheric ions. In the first study, we use a coupled MHD magnetosphere - kinetic radiation belt model to explain recent Akebono/RDM observations of greater than 2.5 MeV radiation belt electron enhancements occurring on timescales of less than a few hours. In the second study, we present initial results of a ring current study using a newly coupled kinetic ring current model with an MHD magnetosphere model. Results of a dst study for four geomagnetic events are shown. Moreover, direct comparison with TWINS ENA images are used to infer the role that composition plays in the ring current. In the final study, we directly model the transport of plasma from the ionosphere to the magnetosphere. We especially focus on the role of photoelectrons and and wave-particle interactions. The modeling methodology for each of these studies will be detailed along with the results.

  11. Stormtime transport of ring current and radiation belt ions

    NASA Technical Reports Server (NTRS)

    Chen, Margaret W.; Schulz, Michael; Lyons, Larry R.; Gorney, David J.

    1993-01-01

    A dynamical guiding-center simulation model is used to study the stormtime ion transport which leads to the formation of the ring current and diffusion in the radiation belts. Representative ions guiding-center motion in response to model storm-associated impulses in the convection electric field is traced for a range of ion mu values. The present numerical results are compared with previously formulated limiting idealization of particle transport in order to assess the limits of validity of these approximations. For ions having drift periods that exceed the duration of the main phase of the storm, their inward transport to form the stormtime ring current is appropriately described as direct convective access. For ions having drift periods comparable to the duration of the main phase of the storm, there is a transition between direct convective access and transport that resembles radial diffusion. Lower-energy ring-current ions at L of about 3 are freshly injected there from open adiabatic trajectories, whereas the higher-energy ring-current population consists of a mixture of freshly injected and previously trapped ions.

  12. Computational analysis of the near-Earth magnetospheric current system during two-phase decay storms

    NASA Astrophysics Data System (ADS)

    Liemohn, M. W.; Kozyra, J. U.; Clauer, C. R.; Ridley, A. J.

    2001-12-01

    Several two-phase decay magnetic storms are examined using a kinetic transport model to find the spatial and temporal distribution of the perpendicular and field-aligned currents in the inner magnetosphere. The global morphology of these currents in the calculational domain (inside of geosynchronous orbit) is discussed as a function of storm epoch, obtaining good comparison between the numerically derived features and observed values of stormtime currents in this region. The model results are also consistent with quiet time plasma observations showing an increasing pressure in to L=3 or 4, including a pressure maximum near midnight for the generation of region 2 Birkeland currents in the proper direction. A detailed analysis of the characteristic features of these currents is also presented and discussed. It is found that most of the ring current (>90%) during the main phase and early recovery phase is partial rather than symmetric, closing mostly (up to 90%) through field-aligned currents into the ionosphere. Conversely, the quiet time ring current is largely (>60%) symmetric, with most of the asymmetry produced by minor injections of near-Earth plasma sheet material. In general, the peak asymmetric current (which occurs during the main phase) is 2-3 times larger than the peak symmetric current (which occurs during the recovery phase) for any particular two-phase decay event. This is the case for all of the events studied, regardless of storm size, solar wind parameters, or solar cycle. The maximum azimuthal current (integrated over a local time slice) reaches 5 to 20 MA, compared with <2 MA of symmetric current at quiet times.

  13. Persistent currents in coherently coupled Bose-Einstein condensates in a ring trap

    NASA Astrophysics Data System (ADS)

    Abad, Marta

    2016-03-01

    We study the stability of persistent currents in a coherently coupled quasi-two-dimensional Bose-Einstein condensate confined in a ring trap at T =0 . By numerically solving Gross-Pitaevskii equations and by analyzing the excitation spectrum obtained from diagonalization of the Bogoliubov-de Gennes matrix, we describe the mechanisms responsible for the decay of the persistent currents depending on the values of the interaction coupling constants and the Rabi frequency. When the unpolarized system decays due to an energetic instability in the density channel, the spectrum may develop a rotonlike minimum, which gives rise to the finite wavelength excitation necessary for vortex nucleation at the inner surface. When decay in the unpolarized system is driven by spin-density excitations, the finite wavelength naturally arises from the existence of a gap in the excitation spectrum. In the polarized phase of the coherently coupled condensate, there is a hybridization of the excitation modes that leads to complex decay dynamics. In particular, close to the phase transition, a state of broken rotational symmetry is found to be stationary and stable.

  14. The Saturnian Ring Current: The Role of Suprathermal Pressure.

    NASA Astrophysics Data System (ADS)

    Sergis, N.; Krimigis, S. M.; Mitchell, D. G.; Roelof, E. C.; Hamilton, D. C.; Krupp, N.

    2007-12-01

    On July 1, 2007, Cassini completed three full years orbiting Saturn. The Magnetospheric Imaging Instrument (MIMI) onboard the spacecraft, performs comprehensive measurements of the energetic ion population within the magnetosphere of the planet. Observations of energetic ion directional intensities, energy spectra and ion composition are provided by the Charge Energy Mass Spectrometer (CHEMS) over the range 3 to 220 keV/e and by the Low Energy Magnetospheric Measurements System (LEMMS) that measures ions in the range 0.024 to 18 MeV. Using the suprathermal particle pressure (Ppart) distribution over the Saturnian magnetosphere, calculated from the (E>3keV) energetic ion fluxes obtained during the three years of Cassini orbits, we address the driving mechanism of the equatorial azimuthal current system in the Saturnian magnetosphere. We report estimates of the equatorial azimuthal ring current intensity (Jphi) resulting from the radial pressure gradient and compare the inertial (centrifugal) stress to suprathermal particle pressures and their relative significance on the ring current formation and dynamics. Preliminary results indicate that the suprathermal pressure (Ppart), is systematically larger compared to the ram pressure of the corotational flow (ρ V2), by approximately one order of magnitude (i.e. 5× 10- 10dyne/cm2 vs. 6× 10-11dyne/cm2 for r=10RS), throughout the ring current region. Furthermore, outside r=11RS the centrifugal stress (ρ Ømega 2r), appears to be substantially smaller compared to the radial gradient of the suprathermal pressure (dPpart/dr), suggesting that the outer part of the azimuthal ring current is driven principally by suprathermal rather than inertial forces.

  15. Survey of Digital Feedback Systems in High Current Storage Rings

    SciTech Connect

    Teytelman, Dmitry

    2003-06-06

    In the last decade demand for brightness in synchrotron light sources and luminosity in circular colliders led to construction of multiple high current storage rings. Many of these new machines require feedback systems to achieve design stored beam currents. In the same time frame the rapid advances in the technology of digital signal processing allowed the implementation of these complex feedback systems. In this paper I concentrate on three applications of feedback to storage rings: orbit control in light sources, coupled-bunch instability control, and low-level RF control. Each of these applications is challenging in areas of processing bandwidth, algorithm complexity, and control of time-varying beam and system dynamics. I will review existing implementations as well as comment on promising future directions.

  16. Particle simulation of ion heating in the ring current

    NASA Technical Reports Server (NTRS)

    Qian, S.; Hudson, M. K.; Roth, I.

    1990-01-01

    Heating of heavy ions has been observed in the equatorial magnetosphere in GEOS 1 and 2 and ATS 6 data due to ion cyclotron waves generated by anisotropic hot ring current ions. A one-dimensional hybrid-Darwin code has been developed to study ion heating in the ring current. Here, a strong instability and heating of thermal ions is investigated in a plasma with a los cone distribution of hot ions. The linear growth rate calculation and particle simulations are conducted for cases with different loss cones and relative ion densities. The linear instability of the waves, the quasi-linear heating of cold ions and dependence on the thermal H(+)/He(+) density ratio are analyzed, as well as nonlinear parallel heating of thermal ions. Effects of thermal oxygen and hot oxygen are also studied.

  17. Protons as the prime contributors to storm time ring current

    NASA Technical Reports Server (NTRS)

    Berko, F. W.; Cahill, L. J., Jr.; Fritz, T. A.

    1975-01-01

    Following a large sudden commencement on June 17, 1972, a large magnetic storm evolved, with a well-developed main phase and recovery phase. Explorer 45 (S3-A), with its apogee near 16 hours local time in June, measured the equatorial particle populations and magnetic field throughout this period. By use of data obtained during the symmetric recovery phase it is shown that through a series of self-consistent calculations, the measured protons, with energies from 1 to 872 keV, can account for almost all of the observed ring current magnetic effects within the limits of experimental uncertainties. This enables us to set an upper limit to the heavy ion contribution to the storm time ring current of a few percent of the proton contribution.

  18. Los Alamos high-current proton storage ring

    NASA Astrophysics Data System (ADS)

    Lawrence, G. P.; Hardekopf, R. A.; Jason, A. J.; Clout, P. N.; Sawyer, G. A.

    1985-05-01

    The Proton Storage Ring (PSR), whose installation was recently completed at Los Alamos, is a fast-cycling high-current accumulator designed to produce intense 800 MeV proton pulses for driving a spallation neutron source. The ring converts long beam pulses from the LAMPF linear accelerator into short bunches well matched to requirements of a high-resolution neutron-scattering materials science program. The initial performance goal for this program is to provide 100-(MU)A average current at the neutron production target within a 12-Hz pulse rate. Operation at 20 (MU)A is scheduled for September 1985, with full intensity within the next year. The storage ring was originally designed to function in a second mode in which six 1-ns bunches are accumulated and separately extracted every LAMPF macropulse. Implementation of this mode, which would serve a fast-neutron nuclear-physics program, was deferred in favor of initial concentration on the neutron-scattering program. The PSR design and status is summarized. Unique machine features include high peak current, two-step charge-stripping injection, a low-impedance buncher amplifier to counter beam-loading, and a high-repetition-rate strip-line extraction kicker.

  19. Beam Aborts in PEP-II Rings and Lingering Drift Chamber Currents

    SciTech Connect

    Meshkat, N.

    2004-09-03

    The BABAR detector at SLAC was designed to study CP-violation in B-meson decays from electron-positron collisions in the PEP-II electron-positron storage rings. Background radiation in the High Energy Ring (HER) and Low Energy Ring (LER) of PEP-II has the potential to damage the sensitive equipment in the BABAR detector. As a result, the beams in the HER and LER can be aborted to prevent such damage. In the span of a few microseconds, the HER and LER currents drop from, for example, 1450 micro Amps and 2300 micro Amps, respectively, to zero. At this time the voltage in the Drift Chamber is rapidly ramped down from a potential of 1930 V to a safe potential of 800 V, thus we would expect the currents in the Drift Chamber to quickly go to zero once the beams are aborted. However, we observe an average 15 second delay in the measured time it takes for all current in the Drift Chamber to fall below 1 micro Amp. This delay has been hypothesized as an instrumentation issue and not as a physical phenomenon. The specific sources of this error are still not completely known, but analysis suggests that it results from the interplay of the CAEN High Voltage supplies and the EPICS system and/or limitations within those systems.

  20. Dst is not a pure ring-current index

    NASA Astrophysics Data System (ADS)

    Campbell, Wallace H.

    The Equatorial Dst Ring-Current Index, Dst, distributed internationally by the World Data Center C2 for Geomagnetism (Faculty of Science, Kyoto University) is widely used in geophysics as an indicator of geomagnetic storm behavior. At the recent Chapman Conference on Magnetic Storms held at the Jet Propulsion Laboratory in Pasadena, Calif., from February 11 to 16, 1996, three of the conference summary speakers formally announced that the Dst index should not be considered to be a simple representation of the ring current of a storm because other sources significantly contribute to that index formulation. This assertion went unchallenged by those in attendance. Such understanding represents a major change from the traditional belief that the index is a direct result of the geomagnetic storm-time growth and recovery of a Saturnlike ring of particles encircling the Earth. This old model is indeed beautiful, but inherently wrong and inadequate for the many uses to which Dst has been assigned over the years. The paragraphs below describe some of the backgrou nd for this new viewpoint and suggest how the characteristic storm shape may arise.

  1. Modelling of the ring current in Saturn's magnetosphere

    NASA Astrophysics Data System (ADS)

    Giampieri, G.; Dougherty, M.

    2004-02-01

    . The existence of a ring current inside Saturn's magnetosphere was first suggested by smith80 and ness81,ness82, in order to explain various features in the magnetic field observations from the Pioneer 11 and Voyager 1 and 2 spacecraft. connerney83 formalized the equatorial current model, based on previous modelling work of Jupiter's current sheet and estimated its parameters from the two Voyager data sets. Here, we investigate the model further, by reconsidering the data from the two Voyager spacecraft, as well as including the Pioneer 11 flyby data set. First, we obtain, in closed form, an analytic expression for the magnetic field produced by the ring current. We then fit the model to the external field, that is the difference between the observed field and the internal magnetic field, considering all the available data. In general, through our global fit we obtain more accurate parameters, compared to previous models. We point out differences between the model's parameters for the three flybys, and also investigate possible deviations from the axial and planar symmetries assumed in the model. We conclude that an accurate modelling of the Saturnian disk current will require taking into account both of the temporal variations related to the condition of the magnetosphere, as well as non-axisymmetric contributions due to local time effects.

  2. ENA Observations from the IMAGE Mission: Global Evolution and Validation of the Ring Current Ion Distribution and Future Outlook

    NASA Astrophysics Data System (ADS)

    Brandt, P. C.; Hsieh, S. Y. W.; Demajistre, R.; Sitnov, M. I.; Stephens, G. K.; Gkioulidou, M.

    2016-12-01

    Energetic Neutral Atom (ENA) imaging is the only technique that can capture the instantaneous state of the ring current ion distribution, which can vary globally on <10 min timescales. Therefore, it is also enables the only method to validate global ring current physics models. However, this requires a detailed understanding for how ENAs are produced from the ring current and inversion techniques that are thoroughly validated against in-situ measurements. To date, several missions have carried out ENA imaging of the ring current including POLAR, Astrid-1, Double Star, TWINS and IMAGE. Because of their path-finding successes, a future science-mission concept, MEDICI, has been defined in the Heliophysics Decadal Survey. In this presentation we provide an overview of the global storm-time ring current ion evolution in the 10-200 keV range for several storms during the 2000-2005 era using ENA observations from the IMAGE mission obtained by the HENA Camera. A constrained linear inversion technique has proven to be one of the more effective and convenient techniques to retrieve the spatial and pitch-angle distributions (PAD) of the ring current. We briefly describe the technique and focus on how to ensure that the unique and best solution has been found by using both simulations using synthetic data and validations against the simultaneous in-situ measurements from the Cluster mission for several geomagnetic storms. Results of the global evolution of the ring current is summarized in terms of build-up and decay, and symmetrization timescales, degree of spatial asymmetry, temporal variability due to injections and spatial variability of PADs. We present comparisons with empirical ring current distributions retrieved from the global magnetic field model TS07d and Van Allen Probes in-situ measurements for similar driving conditions. Lastly, we discuss the lessons learned and implications for the second-generation of imaging missions such as MEDICI.

  3. Persistent Currents in Bosonic Mixtures in the Ring Geometry

    NASA Astrophysics Data System (ADS)

    Anoshkin, Konstantin

    The present thesis is devoted to an analysis of the possibility of Bose condensates supporting persistent currents in the ring geometry. Our analysis is based on an approach developed by F. Bloch [1]which focuses on the ground state energy of the condensate as a function of its angular momentum L. According to this approach, persistent currents are stable if the energy exhibits a local minimum at some non-zero angular momentum. We have used this approach for a single-species gas within a mean-field approximation to show that persistent currents are stable at integral multiples of Nh, where N is the number of atoms in the system, provided a certain interaction parameter exceeds some critical value. These results are extended to a binary mixture of bosonic atoms and we show that the system is still capable of supporting persistent currents under certain conditions. Some of our conclusions contradict those appearing in the earlier literature.

  4. Ring current activity during the early Bz<0 phase of the January 1997 magnetic cloud

    NASA Astrophysics Data System (ADS)

    Jordanova, V. K.; Torbert, R. B.; Thorne, R. M.; Collin, H. L.; Roeder, J. L.; Foster, J. C.

    1999-11-01

    The passage at Earth of the January 10-11, 1997, magnetic cloud induced a storm of moderate geomagnetic activity with Dst index reaching minimum values of about -83 nT. We study ring current formation during the early Bz negative phase of this magnetic cloud, using energetic particle data from three instruments on the Polar spacecraft and geosynchronous plasma data from the LANL spacecraft. We use our kinetic drift-loss model to simulate the evolution of ring current H+, He+, and O+ ion distributions and associated aeronomical effects during this period. The results from two Volland-Stern type magnetospheric electric field model formulations are compared: (1) Kp-dependent and (2) interplanetary magnetic field (IMF) dependent. We demonstrate that while both electric field models reproduce well the main trends of ring current formation and decay during the storm, the IMF-dependent model reproduces the rapidity of the main storm growth phase and its strength better. Comparing model results during the main phase of the storm with HYDRA, TIMAS, and CAMMICE data we find that the model reproduces very well the ring current distributions near dawn. The formation of the nose event, i.e., the rise of the 10-30 keV energy particles near dusk due to abruptly increased convection is, however, overestimated by the model. We compute plasmaspheric heating through Coulomb collisions as the storm evolves and find that maximum heating occurs initially on the nightside near L~3.5 and subsequently moves earthward to L~2.75, in agreement with Millstone Hill radar observations of midlatitude electron temperature enhancement on January 10. However, the magnitude of the energy transferred to plasmaspheric electrons through Coulomb collisions appears to be not sufficient to yield the observed elevated electron temperature at ~0830 UT, suggesting that additional energy sources should be considered during this event.

  5. Search for flavor-changing-neutral-current d meson decays.

    PubMed

    Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Ancu, L S; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Arnoud, Y; Arov, M; Arthaud, M; Askew, A; Asman, B; Assis Jesus, A C S; Atramentov, O; Autermann, C; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Banerjee, P; Barberis, E; Barfuss, A-F; Bargassa, P; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Berntzon, L; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Biscarat, C; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Borissov, G; Bos, K; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Buehler, M; Buescher, V; Burdin, S; Burke, S; Burnett, T H; Buszello, C P; Butler, J M; Calfayan, P; Calvet, S; Cammin, J; Caron, S; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chan, K; Chandra, A; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Christoudias, T; Cihangir, S; Claes, D; Clément, B; Coadou, Y; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Crépé-Renaudin, S; Cutts, D; Cwiok, M; da Motta, H; Das, A; Davies, G; De, K; de Jong, S J; de Jong, P; De La Cruz-Burelo, E; De Oliveira Martins, C; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Ford, M; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; Garcia, C; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Gelé, D; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Gollub, N; Gómez, B; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, J; Guo, F; Gutierrez, P; Gutierrez, G; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Hanagaki, K; Hansson, P; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Hong, S J; Hooper, R; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jesik, R; Johns, K; Johnson, C; Johnson, M; Jonckheere, A; Jonsson, P; Juste, A; Käfer, D; Kahn, S; Kajfasz, E; Kalinin, A M; Kalk, J R; Kalk, J M; Kappler, S; Karmanov, D; Kasper, J; Kasper, P; Katsanos, I; Kau, D; Kaur, R; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y M; Khatidze, D; Kim, H; Kim, T J; Kirby, M H; Kirsch, M; Klima, B; Kohli, J M; Konrath, J-P; Kopal, M; Korablev, V M; Kozelov, A V; Krop, D; Kryemadhi, A; Kuhl, T; Kumar, A; Kunori, S; Kupco, A; Kurca, T; Kvita, J; Lacroix, F; Lam, D; Lammers, S; Landsberg, G; Lazoflores, J; Lebrun, P; Lee, W M; Leflat, A; Lehner, F; Lellouch, J; Leveque, J; Lewis, P; Li, J; Li, Q Z; Li, L; Lietti, S M; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobo, L; Lobodenko, A; Lokajicek, M; Lounis, A; Love, P; Lubatti, H J; Lyon, A L; Maciel, A K A; Mackin, D; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Makovec, N; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; Martin, B; McCarthy, R; Melnitchouk, A; Mendes, A; Mendoza, L; Mercadante, P G; Merkin, M; Merritt, K W; Meyer, J; Meyer, A; Michaut, M; Millet, T; Mitrevski, J; Molina, J; Mommsen, R K; Mondal, N K; Moore, R W; Moulik, T; Muanza, G S; Mulders, M; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Nomerotski, A; Novaes, S F; Nunnemann, T; O'Dell, V; O'Neil, D C; Obrant, G; Ochando, C; Onoprienko, D; Oshima, N; Osta, J; Otec, R; Otero Y Garzón, G J; Owen, M; Padley, P; Pangilinan, M; Parashar, N; Park, S-J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Penning, B; Peters, K; Peters, Y; Pétroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M-E; Polozov, P; Pompos, A; Pope, B G; Popov, A V; Potter, C; Prado da Silva, W L; Prosper, H B; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rakitine, A; Rangel, M S; Ranjan, K; Ratoff, P N; Renkel, P; Reucroft, S; Rich, P; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rodrigues, R F; Royon, C; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A; Savage, G; Sawyer, L; Scanlon, T; Schaile, D; Schamberger, R D; Scheglov, Y; Schellman, H; Schieferdecker, P; Schliephake, T; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sekaric, J; Sengupta, S; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shivpuri, R K; Shpakov, D; Siccardi, V; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Snow, J; Snow, G R; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Souza, M; Spurlock, B; Stark, J; Steele, J; Stolin, V; Stone, A; Stoyanova, D A; Strandberg, J; Strandberg, S; Strang, M A; Strauss, M; Strauss, E; Ströhmer, R; Strom, D; Stutte, L; Sumowidagdo, S; Svoisky, P; Sznajder, A; Talby, M; Tamburello, P; Tanasijczuk, A; Taylor, W; Telford, P; Temple, J; Tiller, B; Tissandier, F; Titov, M; Tokmenin, V V; Toole, T; Torchiani, I; Trefzger, T; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, S; Uvarov, L; Uzunyan, S; Vachon, B; van den Berg, P J; van Eijk, B; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Villeneuve-Seguier, F; Vint, P; Vokac, P; Von Toerne, E; Voutilainen, M; Vreeswijk, M; Wagner, R; Wahl, H D; Wang, L; Wang, M H L S; Warchol, J; Watts, G; Wayne, M; Weber, M; Weber, G; Wenger, A; Wermes, N; Wetstein, M; White, A; Wicke, D; Wilson, G W; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Yacoob, S; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yip, K; Yoo, H D; Youn, S W; Yu, J; Zatserklyaniy, A; Zeitnitz, C; Zhang, D; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zivkovic, L; Zutshi, V; Zverev, E G

    2008-03-14

    We study the flavor-changing-neutral-current process c-->u micro(+) micro(-) using 1.3 fb(-1) of pp[over ] collisions at square root s = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We see clear indications of the charged-current mediated D(s)(+) and D(+)-->phipi(+) --> micro(+)micro(-)pi(+) final states with significance greater than 4 standard deviations above background for the D(+) state. We search for the continuum neutral-current decay of D(+)-->pi(+) micro(+) micro(-) in the dimuon invariant mass spectrum away from the phi resonance. We see no evidence of signal above background and set a limit of B(D(+) --> pi(+) micro(+) micro(-))<3.9 x 10(-6) at the 90% C.L. This limit places the most stringent constraint on new phenomena in the c--> u micro(+) micro(-) transition.

  6. Search for right-handed currents in muon decay

    SciTech Connect

    Jodidio, A.E.

    1986-01-01

    Limits are reported on charged right-handed currents, based on precise measurement of the endpoint e/sup +/ spectrum in ..mu../sup +/ decay. Highly polarized ..mu../sup +/ from the TRIUMF ''surface'' muon beam were stopped in high purity metal foils and liquid He targets selected to minimize depolarization effects. Decay e/sup +/ emitted within 160 mrad of the beam direction were momentum-analyzed to 0.15%. Muons were stopped within either a spin-processing transverse field (70-G or 110-G) or a spin-holding longitudinal field (0.3-T or 1.1-T). Data collected with the spin-precessing field were used for the momentum calibration of the spectrometer. The spin-held data were used to measure the relative e/sup +/ rate at the endpoint. An extrapolation was made to extract the endpoint rate opposite to the ..mu../sup +/ spin. In terms of the standard muon decay parameters this rate is given by (1-xi P/sub ..mu../delta/rho) where P/sub ..mu../ is muon polarization. The result for xi P/sub ..mu../delta was consistent with the V-A prediction of 1. It is quoted as a 90% confidence lower limit xi P/sub ..mu../delta/rho > 0.9975 since we are unable to correct for all possible sources of muon depolarization. For the model with manifest left-right symmetry and massless neutrinos the result implies 90% confidence limits m(W/sub 2/) > 432 GeV/c/sup 2/ and -0.050 < xi < 0.035, where W/sub 2/ is the predominantly right-handed boson and xi is the left-right mixing angle. With the assumption of no left-right mixing an equivalent 90% confidence upper limit of 0.025 is obtained on the absolute value of the ratio of a possible V+A amplitude to the dominant V-A amplitude in muon and pion decays. Limits are also deduced on the nu/sub ..mu..L/ mass and helicity in ..pi../sup +/ decay, non-(V-A) couplings in helicity projection form, the mass scale of composite leptons, and the branching ratio for ..-->.. e+f where f (familon) is the neutral massless Nambu-Goldstone boson associated with

  7. Predicting EMIC wave properties from ring current plasma conditions

    NASA Astrophysics Data System (ADS)

    Cowee, M.; Fu, X.; Jordanova, V.

    2015-12-01

    Recently, sophisticated computer models have shown that accurate, dynamic modelling of the energetic electrons in the radiation belt requires global and real-time plasma and wave conditions. Data provided by in-situ spacecraft measurement are too sparse to supply enough inputs for continuous global modeling of the radiation belt. Here we present a model to predict amplitude, peak frequency and spectral width of the electromagnetic ion cyclotron (EMIC) wave from the anisotropic ring current ion distributions, which are the source of the wave. The model is derived from hybrid simulations in a large initial parameter space for plasmas consisting of electrons, protons, and helium ions. Key parameters include the ratio of plasma frequency to ion gyrofrequency, the density, temperature and anisotropy of hot ions, and the cold-ion composition. The results show that amplitude, peak frequency and spectral width of EMIC waves can be related to linear properties of the anisotropy-driven instability, e.g. growth rate and plasma beta, through simple analytic formulas. Combined with a dynamic ring current model, this model can provide global EMIC wave information needed for radiation-belt modeling.

  8. Short-Term Forecasting of Radiation Belt and Ring Current

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching

    2007-01-01

    A computer program implements a mathematical model of the radiation-belt and ring-current plasmas resulting from interactions between the solar wind and the Earth s magnetic field, for the purpose of predicting fluxes of energetic electrons (10 keV to 5 MeV) and protons (10 keV to 1 MeV), which are hazardous to humans and spacecraft. Given solar-wind and interplanetary-magnetic-field data as inputs, the program solves the convection-diffusion equations of plasma distribution functions in the range of 2 to 10 Earth radii. Phenomena represented in the model include particle drifts resulting from the gradient and curvature of the magnetic field; electric fields associated with the rotation of the Earth, convection, and temporal variation of the magnetic field; and losses along particle-drift paths. The model can readily accommodate new magnetic- and electric-field submodels and new information regarding physical processes that drive the radiation-belt and ring-current plasmas. Despite the complexity of the model, the program can be run in real time on ordinary computers. At present, the program can calculate present electron and proton fluxes; after further development, it should be able to predict the fluxes 24 hours in advance

  9. Operational advances in ring current modeling using RAM-SCB

    SciTech Connect

    Welling, Daniel T; Jordanova, Vania K; Zaharia, Sorin G; Morley, Steven K

    2010-12-03

    The Ring current Atmosphere interaction Model with Self-Consistently calculated 3D Magnetic field (RAM-SCB) combines a kinetic model of the ring current with a force-balanced model of the magnetospheric magnetic field to create an inner magnetospheric model that is magnetically self consistent. RAM-SCB produces a wealth of outputs that are valuable to space weather applications. For example, the anisotropic particle distribution of the KeV-energy population calculated by the code is key for predicting surface charging on spacecraft. Furthermore, radiation belt codes stand to benefit substantially from RAM-SCB calculated magnetic field values and plasma wave growth rates - both important for determining the evolution of relativistic electron populations. RAM-SCB is undergoing development to bring these benefits to the space weather community. Data-model validation efforts are underway to assess the performance of the system. 'Virtual Satellite' capability has been added to yield satellite-specific particle distribution and magnetic field output. The code's outer boundary is being expanded to 10 Earth Radii to encompass previously neglected geosynchronous orbits and allow the code to be driven completely by either empirical or first-principles based inputs. These advances are culminating towards a new, real-time version of the code, rtRAM-SCB, that can monitor the inner magnetosphere conditions on both a global and spacecraft-specific level. This paper summarizes these new features as well as the benefits they provide the space weather community.

  10. Radial transport of storm time ring current ions

    SciTech Connect

    Lui, A.T.Y. )

    1993-01-01

    Radial transport of energetic ions for the development of the main phase of geomagnetic storms is investigated with data from the medium energy particle analyzer (MEPA) on the Charge Composition Explorer (CCE) spacecraft, which monitored protons (E[sub p] > 56 keV), helium ions (E[sub He] > 72 keV), and the carbon-nitrogen-oxygen group, which is mostly dominated by oxygen ions (E[sub O] > 137 keV). From a study of four geomagnetic storms, we show that the flux increase of these ions in the inner ring current region (L [approx lt] 5) can be accounted for by an inward displacement of the ring current population by [approximately]0.5 to 3.5 R[sub E]. There is a general trend that a larger inward displacement occurs at higher L shells than at lower ones. These results are in agreement with previous findings. The radially injected population consists of the prestorm population modified by substorm injections which occur on a much shorter rime scale than that of a storm main phase. It is also found that the inward displacement is relatively independent of ion mass and energy, suggesting that the radial transport of these energetic ions is effected primarily by convective motion from a large electric field or by diffusion resulting from magnetic field fluctuations. 27 refs., 5 figs.

  11. Modeling Earth's Ring Current Using The CIMI Model

    NASA Astrophysics Data System (ADS)

    Craven, J. D., II; Perez, J. D.; Buzulukova, N.; Fok, M. C. H.

    2015-12-01

    Earth's ring current is a result of the injection of charged particles trapped in the magnetosphere from solar storms. The enhancement of the ring current particles produces magnetic depressions and disturbances to the Earth's magnetic field known as geomagnetic storms, which have been modeled using the comprehensive inner magnetosphere-ionosphere (CIMI) model. The purpose of this model is to identify and understand the physical processes that control the dynamics of the geomagnetic storms. The basic procedure was to use the CIMI model for the simulation of 15 storms since 2009. Some of the storms were run multiple times, but with varying parameters relating to the dynamics of the Earth's magnetic field, particle fluxes, and boundary conditions of the inner-magnetosphere. Results and images were placed in the TWINS online catalog page for further analysis and discussion. Particular areas of interest were extreme storm events. A majority of storms simulated had average DST values of -100 nT; these extreme storms exceeded DST values of -200 nT. The continued use of the CIMI model will increase knowledge of the interactions and processes of the inner-magnetosphere as well as lead to a better understanding of extreme solar storm events for the future advancement of space weather physics.

  12. Geomagnetic storms, the Dst ring-current myth and lognormal distributions

    USGS Publications Warehouse

    Campbell, W.H.

    1996-01-01

    The definition of geomagnetic storms dates back to the turn of the century when researchers recognized the unique shape of the H-component field change upon averaging storms recorded at low latitude observatories. A generally accepted modeling of the storm field sources as a magnetospheric ring current was settled about 30 years ago at the start of space exploration and the discovery of the Van Allen belt of particles encircling the Earth. The Dst global 'ring-current' index of geomagnetic disturbances, formulated in that period, is still taken to be the definitive representation for geomagnetic storms. Dst indices, or data from many world observatories processed in a fashion paralleling the index, are used widely by researchers relying on the assumption of such a magnetospheric current-ring depiction. Recent in situ measurements by satellites passing through the ring-current region and computations with disturbed magnetosphere models show that the Dst storm is not solely a main-phase to decay-phase, growth to disintegration, of a massive current encircling the Earth. Although a ring current certainly exists during a storm, there are many other field contributions at the middle-and low-latitude observatories that are summed to show the 'storm' characteristic behavior in Dst at these observatories. One characteristic of the storm field form at middle and low latitudes is that Dst exhibits a lognormal distribution shape when plotted as the hourly value amplitude in each time range. Such distributions, common in nature, arise when there are many contributors to a measurement or when the measurement is a result of a connected series of statistical processes. The amplitude-time displays of Dst are thought to occur because the many time-series processes that are added to form Dst all have their own characteristic distribution in time. By transforming the Dst time display into the equivalent normal distribution, it is shown that a storm recovery can be predicted with

  13. Heavy Flavor Decays of the Z0 and a Search for Flavor Changing Neutral Currents

    SciTech Connect

    Walston, S

    2004-06-22

    Presented here are the results of a direct search for flavor changing neutral currents via the rare process Z{sup 0} {yields} bs and a measurement of R{sub bs} = {Lambda}(Z{sup 0} {yields} bs)/{Lambda}(Z{sup 0} {yields} hadrons). Because the decays Z{sup 0} {yields} b{bar b} and Z{sup 0} {yields} c{bar c} contribute significant backgrounds to Z{sup 0} {yields} bs, simultaneous measurements of R{sub b} = {Lambda}(Z{sup 0} {yields} b{bar b})/{Lambda}(Z{sup 0} {yields} hadrons) and R{sub c} = {Lambda}(Z{sup 0} {yields} c{bar c})/{Lambda}(Z{sup 0} {yields} hadrons) were also made. The standard double tag technique was extended and self calibrating tags were used for s, c, and b quarks. These measurements were made possible by the unique capabilities of the SLAC Large Detector (SLD) at the Stanford Linear Accelerator Center (SLAC): The b and c tags relied upon the SLD's VXD3 307 megapixel CCD vertex detector for topological and kinematic reconstruction of the B and D decay vertices; the s tag identified K{sup {+-}} mesons using the particle identification capabilities of SLD's Cherenkov Ring Imaging Detector (CRID), and K{sub S}{sup 0} mesons and {Lambda} hadrons by kinematic reconstruction of their decay vertices in SLD's 5120 channel central drift chamber (CDC) particle tracking system.

  14. Observation of magnetic fluctuations and rapid density decay of magnetospheric plasma in Ring Trap 1

    SciTech Connect

    Saitoh, H.; Yoshida, Z.; Morikawa, J.; Yano, Y.; Mikami, H.; Kasaoka, N.; Sakamoto, W.

    2012-06-15

    The Ring Trap 1 device, a magnetospheric configuration generated by a levitated dipole field magnet, has created high-{beta} (local {beta} {approx} 70%) plasma by using electron cyclotron resonance heating (ECH). When a large population of energetic electrons is generated at low neutral gas pressure operation, high frequency magnetic fluctuations are observed. When the fluctuations are strongly excited, rapid loss of plasma was simultaneously observed especially in a quiet decay phase after the ECH microwave power is turned off. Although the plasma is confined in a strongly inhomogeneous dipole field configuration, the frequency spectra of the fluctuations have sharp frequency peaks, implying spatially localized sources of the fluctuations. The fluctuations are stabilized by decreasing the hot electron component below approximately 40%, realizing stable high-{beta} confinement.

  15. THE POTENTIAL FOR NEUTRINO PHYSICS AT MUON COLLIDERS AND DEDICATED HIGH CURRENT MUON STORAGE RINGS

    SciTech Connect

    BIGI,I.; BOLTON,T.; FORMAGGIO,J.; HARRIS,D.; MORFIN,J.; SPENTZOURIS,P.; YU,J.; KAYSER,B.; KING,B.J.; MCFARLAND,K.; PETROV,A.; SCHELLMAN,H.; VELASCO,M.; SHROCK,R.

    2000-05-11

    Conceptual design studies are underway for both muon colliders and high-current non-colliding muon storage rings that have the potential to become the first true neutrino factories. Muon decays in long straight sections of the storage rings would produce uniquely intense and precisely characterized two-component neutrino beams--muon neutrinos plus electron antineutrinos from negative muon decays and electron neutrinos plus muon antineutrinos from positive muons. This article presents a long-term overview of the prospects for these facilities to greatly extend the capabilities for accelerator-based neutrino physics studies for both high rate and long baseline neutrino experiments. As the first major physics topic, recent experimental results involving neutrino oscillations have motivated a vigorous design effort towards dedicated neutrino factories that would store muon beams of energies 50 GeV or below. These facilities hold the promise of neutrino oscillation experiments with baselines up to intercontinental distances and utilizing well understood beams that contain, for the first time, a substantial component of multi-GeV electron-flavored neutrinos. In deference to the active and fast-moving nature of neutrino oscillation studies, the discussion of long baseline physics at neutrino factories has been limited to a concise general overview of the relevant theory, detector technologies, beam properties, experimental goals and potential physics capabilities. The remainder of the article is devoted to the complementary high rate neutrino experiments that would study neutrino-nucleon and neutrino-electron scattering and would be performed at high performance detectors placed as close as is practical to the neutrino production straight section of muon storage rings in order to exploit beams with transverse dimensions as small as a few tens of centimeters.

  16. Low altitude observations of ENA from the ring current and from the proton oval

    NASA Astrophysics Data System (ADS)

    Søraas, Finn; Sørbø, Marita

    2013-07-01

    Observations of Energetic Neutral Atoms (ENAs) emitted from the proton aurora and from the equatorial ring current at tens to a few hundred of keV during the Halloween 2003 storm are presented. From the proton oval a large number of ENAs are spread over the polar cap making a contribution to the ion outflow. From the Ring Current (RC) ENAs are spread in all directions. The Storm Time Equatorial Belt (STEB) consists of ENAs observed around the geomagnetic equator at low L-values. Their source is RC protons existing at larger L-values. The number of observed ENAs is directly dependent on the amount of ions (protons) present in the RC along the line of sight. Thus the time variations of the STEB enable us to monitor the behavior of the RC. Based on observations of the STEB at six different local times we discuss the RC injection region, the drift of RC-particles through the evening/afternoon sector into the morning sector and the RC decay time during the storm recovery phase. The MLT variation of the STEB gives information about the symmetry and asymmetry of the RC with no interference from other current systems. The revealed RC-symmetry and asymmetry complement magnetic ground observations.

  17. Stormtime transport of ring current and radiation belt ions

    NASA Technical Reports Server (NTRS)

    Chen, Margaret W.; Schulz, Michael; Lyons, L. R.; Gorney, David J.

    1993-01-01

    This is an investigation of stormtime particle transport that leads to formation of the ring current. Our method is to trace the guiding-center motion of representative ions (having selected first adiabatic invariants mu) in response to model substorm-associated impulses in the convection electric field. We compare our simulation results qualitatively with existing analytically tractable idealizations of particle transport (direct convective access and radial diffusion) in order to assess the limits of validity of these approximations. For mu approximately less than 10 MeV/G (E approximately less than 10 keV at L equivalent to 3) the ion drift period on the final (ring-current) drift shell of interest (L equivalent to 3) exceeds the duration of the main phase of our model storm, and we find that the transport of ions to this drift shell is appropriately idealized as direct convective access, typically from open drift paths. Ion transport to a final closed drift path from an open (plasma-sheet) drift trajectory is possible for those portions of that drift path that lie outside the mean stormtime separatrix between closed and open drift trajectories, For mu approximately 10-25 MeV/G (110 keV approximately less than E approximately less than 280 keV at L equivalent to 3) the drift period at L equivalent to 3 is comparable to the postulated 3-hr duration of the storm, and the mode of transport is transitional between direct convective access and transport that resembles radial diffusion. (This particle population is transitional between the ring current and radiation belt). For mu approximately greater than 25 MeV/G (radiation-belt ions having E approximately greater than 280 keV at L equivalent to 3) the ion drift period is considerably shorter than the main phase of a typical storm, and ions gain access to the ring-current region essentially via radial diffusion. By computing the mean and mean-square cumulative changes in 1/L among (in this case) 12 representative

  18. Phase space variations of near equatorially mirroring ring current ions

    SciTech Connect

    Williams, D.J.

    1981-01-01

    We present Isee 1 observations of near equatorially mirroring ring current ions before and after the magnetic storm of November 25-26, 1977. The data are presented as phase space densities, f(s/sup 2//cm/sup 6/), versus the first adiabatic invariant, m(MeV/G), for the L range approx.2.7-8 R/sub E/. The m range covered varies from approx.50-1000 MeV/G at L = 8 to approx.1-100 MeV/G at L = 2.7. The prestorm phase space densities show an intensity peak at a m value which varies with L as m/sub peak/approx.38 MeV/G for 5< or approx. =L< or approx. =8 and m/sub peak/approx.10e/sup( 0.7L/-3) for 2.7< or approx. =L< or approx. =5. Phase space densities remain nearly constant throughout the storm for m values greater that m/sub peak/ and are enhanced for m values less than m/sub peak/. Thus high-energy ions respond adiabatically to the magnetic field changes caused by the low-energy ion enhancements. This result agrees with earlier Explorer 45 results (Lyons and Williams, 1976). The Isee 1 data are compared directly with the Explorer 45 data and are found to agree very well. The time difference of approx.6 years and local time separation of approx.12 hours between the two data sets lead to the conclusion that the ring current ion behavior presented here is a characteristic feature of geomagnetic storms.

  19. Interhemispheric currents in the ring current region as seen by the Cluster spacecraft

    NASA Astrophysics Data System (ADS)

    Tenfjord, P.; Ostgaard, N.; Haaland, S.; Laundal, K.; Reistad, J. P.

    2013-12-01

    The existence of interhemispheric currents has been predicted by several authors, but their extent in the ring current has to our knowledge never been studied systematically by using in-situ measurements. These currents have been suggested to be associated with observed asymmetries of the aurora. We perform a statistical study of current density and direction during ring current crossings using the Cluster spacecraft. We analyse the extent of the interhemispheric field aligned currents for a wide range of solar wind conditions. Direct estimations of equatorial current direction and density are achieved through the curlometer technique. The curlometer technique is based on Ampere's law and requires magnetic field measurements from all four spacecrafts. The use of this method requires careful study of factors that limit the accuracy, such as tetrahedron shape and configuration. This significantly limits our dataset, but is a necessity for accurate current calculations. Our goal is to statistically investigate the occurrence of interhemispheric currents, and determine if there are parameters or magnetospheric states on which the current magnitude and directions depend upon.

  20. High Intracellular Chloride Slows the Decay of Glycinergic Currents

    PubMed Central

    Pitt, Samantha J.; Sivilotti, Lucia G.; Beato, Marco

    2009-01-01

    The time course of currents mediated by native and recombinant glycine receptors was examined with a combination of rapid agonist applications to outside-out patches and single-channel recording. The deactivation time constant of currents evoked by brief, saturating pulses of glycine is profoundly affected by the chloride concentration on the intracellular side of the cell membrane. Deactivation was threefold slower when intracellular chloride was increased from a low level (10 mm), similar to that observed in living mature neurons, to 131 mm (“symmetrical” chloride, often used in pipette internal solutions). Single-channel analysis revealed that high chloride has its greatest effect on the channel closing rate, slowing it by a factor of 2 compared with the value we estimated in the cell-attached mode (in which the channels are at physiological intracellular chloride concentrations). The same effect of chloride was observed when glycinergic evoked synaptic currents were recorded from juvenile rat spinal motoneurons in vitro, because the decay time constant was reduced from ∼7ms to ∼3 ms when cells were dialyzed with 10 mm chloride intracellular recording solution. Our results indicate that the time course of glycinergic synaptic inhibition in intact neurons is much faster than is estimated by measurements in symmetrical chloride and can be modulated by changes in intracellular chloride concentration in the range that can occur in physiological or pathological conditions. PMID:18987182

  1. The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Baker, D. N.; Fennell, J. F.; Blake, J. B.; Larsen, B. A.; Skoug, R. M.; Funsten, H. O.; Friedel, R. H. W.; Reeves, G. D.; Spence, H. E.; Mitchell, D. G.; Lanzerotti, L. J.; Rodriguez, J. V.

    2015-09-01

    Enabled by the comprehensive measurements from the Magnetic Electron Ion Spectrometer (MagEIS), Helium Oxygen Proton Electron mass spectrometer (HOPE), and Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher-energy protons. During the storm main phase, ions with energies <50 keV contribute more significantly to the ring current than those with higher energies; while the higher-energy protons dominate during the recovery phase and quiet times. The enhancements of higher-energy proton fluxes as well as energy content generally occur later than those of lower energy protons, which could be due to the inward radial diffusion. For the 29 March 2013 storm we investigated in detail that the contribution from O+ is ~25% of the ring current energy content during the main phase and the majority of that comes from <50 keV O+. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions. Using the Dessler-Parker-Sckopke relation, the contributions of ring current particles to the magnetic field depression during this geomagnetic storm are also calculated. The results show that the measured ring current ions contribute about half of the Dst depression.

  2. Ring current dynamics in moderate and strong storms: Comparative analysis of TWINS and IMAGE/HENA data with the Comprehensive Ring Current Model

    NASA Astrophysics Data System (ADS)

    Buzulukova, N.; Fok, M.-C.; Goldstein, J.; Valek, P.; McComas, D. J.; Brandt, P. C.

    2010-12-01

    We present a comparative study of ring current dynamics during strong and moderate storms. The ring current during the strong storm is studied with IMAGE/HENA data near the solar cycle maximum in 2000. The ring current during the moderate storm is studied using energetic neutral atom (ENA) data from the Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS) mission during the solar minimum in 2008. For both storms, the local time distributions of ENA emissions show signatures of postmidnight enhancement (PME) during the main phases. To model the ring current and ENA emissions, we use the Comprehensive Ring Current Model (CRCM). CRCM results show that the main-phase ring current pressure peaks in the premidnight-dusk sector, while the most intense CRCM-simulated ENA emissions show PME signatures. We analyze two factors to explain this difference: the dependence of charge-exchange cross section on energy and pitch angle distributions of ring current. We find that the IMF By effect (twisting of the convection pattern due to By) is not needed to form the PME. Additionally, the PME is more pronounced for the strong storm, although relative shielding and hence electric field skewing is well developed for both events.

  3. Ring Current Dynamics in Moderate and Strong Storms: Comparative Analysis of TWINS and IMAGE/HENA Data with the Comprehensive Ring Current Model

    NASA Technical Reports Server (NTRS)

    Buzulukova, N.; Fok, M.-C.; Goldstein, J.; Valek, P.; McComas, D. J.; Brandt, P. C.

    2010-01-01

    We present a comparative study of ring current dynamics during strong and moderate storms. The ring current during the strong storm is studied with IMAGE/HENA data near the solar cycle maximum in 2000. The ring current during the moderate storm is studied using energetic neutral atom (ENA) data from the Two Wide-Angle Imaging Neutral- Atom Spectrometers (TWINS) mission during the solar minimum in 2008. For both storms, the local time distributions of ENA emissions show signatures of postmidnight enhancement (PME) during the main phases. To model the ring current and ENA emissions, we use the Comprehensive Ring Current Model (CRCM). CRCM results show that the main-phase ring current pressure peaks in the premidnight-dusk sector, while the most intense CRCM-simulated ENA emissions show PME signatures. We analyze two factors to explain this difference: the dependence of charge-exchange cross section on energy and pitch angle distributions of ring current. We find that the IMF By effect (twisting of the convection pattern due to By) is not needed to form the PME. Additionally, the PME is more pronounced for the strong storm, although relative shielding and hence electric field skewing is well developed for both events.

  4. Ring Current Dynamics in Moderate and Strong Storms: Comparative Analysis of TWINS and IMAGE/HENA Data with the Comprehensive Ring Current Model

    NASA Technical Reports Server (NTRS)

    Buzulukova, N.; Fok, M.-C.; Goldstein, J.; Valek, P.; McComas, D. J.; Brandt, P. C.

    2010-01-01

    We present a comparative study of ring current dynamics during strong and moderate storms. The ring current during the strong storm is studied with IMAGE/HENA data near the solar cycle maximum in 2000. The ring current during the moderate storm is studied using energetic neutral atom (ENA) data from the Two Wide-Angle Imaging Neutral- Atom Spectrometers (TWINS) mission during the solar minimum in 2008. For both storms, the local time distributions of ENA emissions show signatures of postmidnight enhancement (PME) during the main phases. To model the ring current and ENA emissions, we use the Comprehensive Ring Current Model (CRCM). CRCM results show that the main-phase ring current pressure peaks in the premidnight-dusk sector, while the most intense CRCM-simulated ENA emissions show PME signatures. We analyze two factors to explain this difference: the dependence of charge-exchange cross section on energy and pitch angle distributions of ring current. We find that the IMF By effect (twisting of the convection pattern due to By) is not needed to form the PME. Additionally, the PME is more pronounced for the strong storm, although relative shielding and hence electric field skewing is well developed for both events.

  5. Current Research on Wood Decay in the USDA Forest Service

    Treesearch

    Harold H. Burdsall Jr.

    1991-01-01

    The Forest Service's research on decay fungi and decay caused by fungi is done mainly in two research work units at the Forest Products Laboratory. One unit, the Center for Forest Mycology Research, performs biosystematic research on root-rot and products-rot fungi in the genera Armillaria, Phellinus, and Phlebia and maintains the culture collection supporting...

  6. Current and future searches for neutrinoless double beta decay

    NASA Astrophysics Data System (ADS)

    Dolinski, Michelle J.

    2016-09-01

    With the discovery of neutrino oscillations and neutrino mass, it has become a pressing question whether neutrinos have distinct antiparticle states. The most practical experimental approach to answering this question is the search for neutrinoless double beta decay, a version of a rare nuclear process that would violate lepton number conservation. The observation of neutrinoless double beta decay would prove that neutrinos are their own antiparticles. Neutrinoless double beta decay experiments deploy large source masses consisting of a select few (usually enriched) isotopes of interest. Detectors must achieve extremely low levels of radioactive background to detect this rare decay. I will report on recent searches for neutrinoless double beta decay and discuss the technical challenges that the next generation of experiments will overcome.

  7. The Magnetic and Shielding Effects of Ring Current on Radiation Belt Dynamics

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching

    2012-01-01

    The ring current plays many key roles in controlling magnetospheric dynamics. A well-known example is the magnetic depression produced by the ring current, which alters the drift paths of radiation belt electrons and may cause significant electron flux dropout. Little attention is paid to the ring current shielding effect on radiation belt dynamics. A recent simulation study that combines the Comprehensive Ring Current Model (CRCM) with the Radiation Belt Environment (RBE) model has revealed that the ring current-associated shielding field directly and/or indirectly weakens the relativistic electron flux increase during magnetic storms. In this talk, we will discuss how ring current magnetic field and electric shielding moderate the radiation belt enhancement.

  8. Search for flavor-changing-neutral-current D meson decays

    SciTech Connect

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Aguilo, E.; Ahn, S.H.; Ahsan, M.; Alexeev, G.D.; Alkhazov, G.; /Buenos Aires U. /Rio de Janeiro, CBPF /Rio de Janeiro State U. /Sao Paulo, IFT /Alberta U. /Simon Fraser U. /York U., Canada /McGill U. /Hefei, CUST /Andes U., Bogota /Charles U.

    2007-08-01

    We study the flavor-changing-neutral-current process c {yields} u{mu}{sup +}{mu}{sup -} using 1.3 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We see clear indications of the D{sup +}{sub s} and D{sup +} {yields} {phi}{pi}{sup +} {yields} {mu}{sup +}{mu}{sup -}{pi}{sup +} final states with significance greater than four standard deviations above background for the D{sup +} state. We search for the continuum decay of D{sup +} {yields} {pi}{sup +}{mu}{sup +}{mu}{sup -} in the dimuon invariant mass spectrum away from the {phi} resonance. We see no evidence of signal above background and set a limit of B(D{sup +} {yields} {pi}{sup +}{mu}{sup +}{mu}{sup -}) < 3.9 x 10{sup -6} at the 90% CL. This limit places the most stringent constraint on new phenomena in the c {yields} u{mu}{sup +}{mu}{sup -} transition.

  9. Large- and Small-Scale Ring Current Electrodynamic Coupling

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.

    2003-01-01

    In this talk we will address the two primary issues of ring current (RC) electrodynamic coupling: 1. RC self-consistent magnetosphere-ionosphere coupling that includes calculation of the magnetospheric electric field (large scale electrodynamic coupling); and 2. RC self-consistent coupling with electromagnetic ion cyclotron (EMIC) waves (small scale electrodynamic coupling). Our study will be based on two RC models that we have recently developed in our group. The first model by Khazanov et al. [2002] couples the system of two kinetic equations: one equation which describes the RC ion dynamics and another equation which describes the energy density evolution of EMIC waves. The second model by Khazanov et al. [2003] deals with large scale electrodynamic coupling processes and provides a self-consistent simulation of RC ions and the magnetospheric electric field. There is presently no model that addresses both of these issues simultaneously in a self-consistent calculation. However, the need exists for such a model, because these two processes directly influence each other, with the mesoscale coupling changing the drift paths of the thermal and energetic particle populations in the inner magnetosphere, thereby changing the wave interactions, and the microscale coupling altering the pitch angle distributions and ionospheric conductivities (through increased precipitation), thus changing the field-aligned currents and electric potential structure. The initial thrust of the work will be the development of a combined kinetic model of micro- and meso-scale RC electrodynamic coupling processes and to examine their interactions with each other on a global scale.

  10. Ring Current Influence on Ionospheric Morpology using HEIDI/GITM

    NASA Astrophysics Data System (ADS)

    Perlongo, N. J.; Ridley, A. J.

    2015-12-01

    A longstanding challenge for ionosphere-thermosphere models has been the inclusion of accurate and self-consistent electrodynamic inputs in the auroral zone. Phenomenon such as penetration electric fields (PEFs), storm enhanced densities (SEDs), and sub-auroral polarization streams (SAPS) are inextricably linked to the coupled magnetosphere-ionosphere-thermosphere system. To address this, the global ionosphere-thermosphere model (GITM) has been coupled to the hot electron ion drift integrator (HEIDI) model of the inner magnetosphere and ring current. However, since the electrodynamic system is strongly dependent on the ionospheric conductance, HEIDI was first updated to include a self-consistent auroral model. HEIDI now calculates the total energy flux and average energy in the auroral zone by calculating the flux of electrons in the loss cone at each time-step. These are used with the Robinson formula to derive the Hall and Pedersen conductances as well as in the potential solver, along with the field-aligned currents, to generate an electric potential pattern which is subsequently used to advect the particles in HEIDI. The resulting aurora and potentials are then used to drive GITM in a one-way coupling. HEIDI and GITM were run for multiple storms using this configuration, and a number of phenomena were investigated, such as PEFs, SEDs and SAPS, as well as their influence on the thermospheric temperature, density and wind structure. Simulations of real storms were compared to incoherent scatter radar, GPS TEC, and satellite data to understand the differences between the old and new model results.

  11. Graphene plasmonics for tuning photon decay rate near metallic split-ring resonator in a multilayered substrate.

    PubMed

    Chen, Yongpin P; Sha, Wei E I; Jiang, Lijun; Hu, Jun

    2015-02-09

    Study of photon decay rate is essential to various optical devices, where graphene is an emerging building block due to its electrical tunability. In this paper, we study photon decay rate of a quantum emitter near a metallic split-ring resonator, which is embedded in a multilayered substrate incorporating a graphene layer. Analyzing photon decay rate in such a complex multilayered system is not only computationally challenging but also highly important to experimentally realizable devices. First, the dispersion relation of graphene plasmonics supported at a dieletric/graphene/dielectric structure is investigated systematically. Meanwhile, the dispersion relation of metallic plasmonics supported at a dielectric/metal structure is studied comparatively. According to our investigation, graphene offers several flexible tuning routes for manipulating photon decay rate, including tunable chemical potential and the emitter's position and polarization. Next, considering plasmonic waves in a graphene sheet occur in the infrared regime, we carefully design a metallic split ring resonating around the same frequency range. Consequently, this design enables a mutual interaction between graphene plasmonics and metallic plasmonics. The boundary element method with a multilayered medium Green's function is adopted in the numerical simulation. Blue-shifted and splitting resonance peaks are theoretically observed, which suggests a strong mode coupling. Moreover, the mode coupling has a switch on-off feature via electrostatically doping the graphene sheet. This work is helpful to dynamically manipulate photon decay rate in complex optical devices.

  12. Effects of ring current ions on the ULF waves in the inner magnetosphere based on a 5-D drift kinetic ring current model

    NASA Astrophysics Data System (ADS)

    Seki, K.; Amano, T.; Saito, S.; Kamiya, K.; Miyoshi, Y.; Keika, K.; Matsumoto, Y.

    2016-12-01

    Terrestrial inner magnetosphere is the region where different plasma regimes over a wide range of energy such as the plasmasphere, ring current, and radiation belt coexist. Among them, the ring current carries most of plasma pressure and is thus responsible for deformation of the magnetic field. Since the deformation changes drift paths of charged particles including the ring current ions, it is important to describe this coupling between the ring current and electric/magnetic fields self-consistently. It is known that short-timescale phenomena such as ULF waves and substorm related ion injections from the plasma sheet play important roles in the inner magnetospheric dynamics during magnetic storms. While ULF waves contribute to the radial transport of relativistic electrons to form the radiation belt, the ion injections contribute to excitation of storm-time Pc5 ULF waves as well as to plasma supply to the ring current from the magnetotail. Aiming at a self-consistent description of the coupling between ring current ions and electric/magnetic fields, we have developed a global ring current model (GEMSIS-RC model). The model is a self-consistent and kinetic numerical simulation code solving the five-dimensional collisionless drift-kinetic equation for the ring-current ions coupled with Maxwell equations. Without assuming a force-balanced equilibrium, the GEMSIS-RC model allows the force-imbalance to exist, which generates induced electric field through the polarization current. In this study, we applied the GEMSIS-RC model for simulation of ULF waves in the inner magnetosphere with a focus on the short-timescale phenomena described above. Comparison between runs with/without ring current ions show that the existence of hot ring current ions can deform and amplify the original sinusoidal waveforms. The deformation causes the energy cascade to higher frequency range (Pc4 and Pc3 ranges). The cascade is more pronounced in high plasma beta cases. It is also shown that

  13. Ring current and electron delocalisation in an all-metal cluster, Al 42-

    NASA Astrophysics Data System (ADS)

    Fowler, P. W.; Havenith, R. W. A.; Steiner, E.

    2002-06-01

    Localised-orbital analysis of the current density induced by a perpendicular magnetic field in square-planar Al 42- demonstrates the intrinsic non-localisability of the σ electrons of this metallic cluster and confirms their dominant role in its diamagnetic ring current. Though delocalised, the π electrons do not give rise to a significant ring current.

  14. Pseudo-π currents: rapid and accurate visualisation of ring currents in conjugated hydrocarbons

    NASA Astrophysics Data System (ADS)

    Fowler, P. W.; Steiner, E.

    2002-10-01

    An inexpensive method for accurate simulation of π contributions to ring currents is proposed. A conjugated carbon framework is formally replaced by a set of hydrogen atoms bearing single 1s (STO-3G) orbitals. Calculation, with the ipsocentric CTOCD-DZ method, of the in-plane σ current density induced by a perpendicular magnetic field then gives a close numerical match to the out-of-plane π current density of the original carbon system at a height of 1 bohr. This 'pseudo-π' method depends on the one-to-one correspondence in symmetry between σ and π orbitals and is capable of reproducing the general pattern of π current, its specific features and its orbital decomposition for polycyclic hydrocarbon systems.

  15. Ring Current-Electromagnetic Ion Cyclotron Waves Coupling

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.

    2005-01-01

    The effect of Electromagnetic Ion Cyclotron (EMIC) waves, generated by ion temperature anisotropy in Earth s ring current (RC), is the best known example of wave- particle interaction in the magnetosphere. Also, there is much controversy over the importance of EMIC waves on RC depletion. Under certain conditions, relativistic electrons, with energies 21 MeV, can be removed from the outer radiation belt (RB) by EMIC wave scattering during a magnetic storm. That is why the calculation of EMIC waves must be a very critical part of the space weather studies. The new RC model that we have developed and present for the first time has several new features that we have combine together in a one single model: (a) several lower frequency cold plasma wave modes are taken into account; (b) wave tracing of these wave has been incorporated in the energy EMIC wave equation; (c) no assumptions regarding wave shape spectra have been made; (d) no assumptions regarding the shape of particle distribution have been made to calculate the growth rate; (e) pitch-angle, energy, and mix diffusions are taken into account together for the first time; (f) the exact loss-cone RC analytical solution has been found and coupled with bounce-averaged numerical solution of kinetic equation; (g) the EMIC waves saturation due to their modulation instability and LHW generation are included as an additional factor that contributes to this process; and (h) the hot ions were included in the real part of dielectric permittivity tensor. We compare our theoretical results with the different EMIC waves models as well as RC experimental data.

  16. Ring Current-Electromagnetic Ion Cyclotron Waves Coupling

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.

    2005-01-01

    The effect of Electromagnetic Ion Cyclotron (EMIC) waves, generated by ion temperature anisotropy in Earth s ring current (RC), is the best known example of wave- particle interaction in the magnetosphere. Also, there is much controversy over the importance of EMIC waves on RC depletion. Under certain conditions, relativistic electrons, with energies 21 MeV, can be removed from the outer radiation belt (RB) by EMIC wave scattering during a magnetic storm. That is why the calculation of EMIC waves must be a very critical part of the space weather studies. The new RC model that we have developed and present for the first time has several new features that we have combine together in a one single model: (a) several lower frequency cold plasma wave modes are taken into account; (b) wave tracing of these wave has been incorporated in the energy EMIC wave equation; (c) no assumptions regarding wave shape spectra have been made; (d) no assumptions regarding the shape of particle distribution have been made to calculate the growth rate; (e) pitch-angle, energy, and mix diffusions are taken into account together for the first time; (f) the exact loss-cone RC analytical solution has been found and coupled with bounce-averaged numerical solution of kinetic equation; (g) the EMIC waves saturation due to their modulation instability and LHW generation are included as an additional factor that contributes to this process; and (h) the hot ions were included in the real part of dielectric permittivity tensor. We compare our theoretical results with the different EMIC waves models as well as RC experimental data.

  17. Transfer matrix approach to the persistent current in quantum rings: Application to hybrid normal-superconducting rings

    NASA Astrophysics Data System (ADS)

    Nava, Andrea; Giuliano, Rosa; Campagnano, Gabriele; Giuliano, Domenico

    2016-11-01

    Using the properties of the transfer matrix of one-dimensional quantum mechanical systems, we derive an exact formula for the persistent current across a quantum mechanical ring pierced by a magnetic flux Φ as a single integral of a known function of the system's parameters. Our approach provides exact results at zero temperature, which can be readily extended to a finite temperature T . We apply our technique to exactly compute the persistent current through p -wave and s -wave superconducting-normal hybrid rings, deriving full plots of the current as a function of the applied flux at various system's scales. Doing so, we recover at once a number of effects such as the crossover in the current periodicity on increasing the size of the ring and the signature of the topological phase transition in the p -wave case. In the limit of a large ring size, resorting to a systematic expansion in inverse powers of the ring length, we derive exact analytic closed-form formulas, applicable to a number of cases of physical interest.

  18. Antiaromatic character of 16 π electron octaethylporphyrins: magnetically induced ring currents from DFT-GIMIC calculations.

    PubMed

    Fliegl, Heike; Pichierri, Fabio; Sundholm, Dage

    2015-03-19

    The magnetically induced current density susceptibility, also called current density, has been calculated for a recently synthesized octaethylporphyrin (OEP) zinc(II) dication with formally 16 π electrons. Numerical integration of the current density passing selected chemical bonds yields the current pathway around the porphyrinoid ring and the strength of the ring current. The current strengths show that the OEP-Zn(II) dication is strongly antiaromatic, as also concluded experimentally. The calculation of the ring current pathway shows that all 24 π electrons participate in the transport of the ring current because the current splits into inner and outer branches of practically equal strengths at the four pyrrolic rings. The corresponding neutral octaethylporphyrinoid without Zn and inner hydrogens is found to be antiaromatic, sustaining a paratropic ring current along the inner pathway with 16 π electrons. The neutral OEP-Zn(II) molecule with formally 18 π electrons is found to be almost as aromatic as free-base porphyrin. However, also in this case, all 26 π electrons contribute to the ring current, as for free-base porphyrin. A comparison of calculated and measured (1)H NMR chemical shifts is presented. The current strength susceptibility under experimental conditions has been estimated by assuming a linear relation between experimental shielding constants and calculated current strengths.

  19. Measurements of the persistent current decay and snapback effect in Tevatron dipole magnets

    SciTech Connect

    Velev, G.V.; Bauer, P.; DiMarco, J.; Hanft, R.; Lamm, M.; Schlabach, P.; Sylvester, C.; Tartaglia, M.; Tompkins, J.C.; /Fermilab

    2006-08-01

    A systematic study of the persistent current decay and snapback effect in the fields of Tevatron accelerator dipoles was performed at the Fermilab Magnet Test Facility (MTF). The decay and snapback were measured under a range of conditions including variations of the current ramp parameters and magnet operational history. The study has mostly focused on the dynamic behavior of the normal sextupole component. In addition, the paper presents the persistent current effects observed in the other allowed field harmonics as well. The results provide new information about the previously observed ''excess'' decay during the first several seconds of the sextupole decay during injection and the correlation between the snapback amplitude and its duration.

  20. Ring discharge on the backsurface of a composite skin with ohmic anisotropy in response to frontal high current injection

    NASA Astrophysics Data System (ADS)

    Lee, T. S.; Robb, J. D.

    The ring discharge hazard to a carbon-reinforced-composites fuel tank skin under lightning strike conditions is investigated. A model of anisotropy in electric conductivity is adopted whereby longitudinal conductivity and transverse conductivity are considered separately. It is concluded that the current flow pattern contains a stagnation-dominated near-field region and a geometry-dominated far-field decaying region. While this pattern is unaltered by anisotropy in conductivity, the accompanying nonliner electrical field pattern is greatly distorted. It is noted that conclusions applicable to the ignition hazard which were derived from the model of a uniform scalar conductivity for the skin still remain intact.

  1. A Statistical Study of the Global Structure of the Ring Current

    NASA Technical Reports Server (NTRS)

    Jorgensen, A. M.; Spence, H. E.; Hughes, W. J.; Singer, H. J.

    1997-01-01

    In this paper we derive the average configuration of the ring current as a function of the state of the magnetosphere as indicated by the Dst index. We sort magnetic field data from the Combined Release and Radiation Effects Satellite (CRRES) by spatial location and by the Dst index in order to produce magnetic field maps. From these maps we calculate local current systems by taking the curl of the magnetic field. NN7e find both the westward (outer) and the eastward (inner) components of the ring current. We find that the ring current intensity varies linearly with D.St as expected, and that the ring current is asymmetric for all Dst values. The azimuthal peak of the ring current is located in the afternoon sector for quiet conditions, and near midnight for disturbed conditions. The ring current also moves closer to the Earth during disturbed conditions. We are able to recreate the Dst index by integrating the magnetic perturbations caused by the ring current. We find that we needed to apply a 20 nT offset to Dst, and assume a perfectly conducting Earth to obtain an optimal agreement between the computed and the observed Dst. We interpret the 20 nT offset as the magnetic field generated by the quiet time ring current used as baseline in computing Dst.

  2. Nuclear cascades in Saturn's rings - Cosmic ray albedo neutron decay and origins of trapped protons in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.

    1983-05-01

    The nearly equatorial trajectory of the Pioneer 11 spacecraft through Saturn's high energy proton radiation belts and under the main A-B-C rings provided a unique opportunity to study the radial dependence of the greater than 30 MeV proton intensities in the belts in terms of models for secondary nucleon production by cosmic ray interactions in the rings, in situ proton injection in the radiation belts by neutron beta decay, magnetospheric diffusion, and absorption by planetary rings and satellites. Maximum trapped proton intensities measured by Pioneer 11 in the radiation belts are compared with calculated intensities and found consistent with trapping times of roughly 40 years and a radial diffusion coefficient of about 10 to the -15th L to the 9th Rs squared/s. Differential energy spectra proportional to E to the -2 estimated from integral measurements of trapped photons with E greater than 100 MeV are consistent with the beta decay model, but an inferred turndown of the spectra toward lower energies and reported integral proton anisotropies of a specified form both indicate the need for more realistic calculations of the neutron source from the rings and the radiation belt loss processes.

  3. Nuclear cascades in Saturn's rings - Cosmic ray albedo neutron decay and origins of trapped protons in the inner magnetosphere

    NASA Technical Reports Server (NTRS)

    Cooper, J. F.

    1983-01-01

    The nearly equatorial trajectory of the Pioneer 11 spacecraft through Saturn's high energy proton radiation belts and under the main A-B-C rings provided a unique opportunity to study the radial dependence of the greater than 30 MeV proton intensities in the belts in terms of models for secondary nucleon production by cosmic ray interactions in the rings, in situ proton injection in the radiation belts by neutron beta decay, magnetospheric diffusion, and absorption by planetary rings and satellites. Maximum trapped proton intensities measured by Pioneer 11 in the radiation belts are compared with calculated intensities and found consistent with trapping times of roughly 40 years and a radial diffusion coefficient of about 10 to the -15th L to the 9th R sub s squared/s. Differential energy spectra proportional to E to the -2 estimated from integral measurements of trapped photons with E greater than 100 MeV are consistent with the beta decay model, but an inferred turndown of the spectra toward lower energies and reported integral proton anisotropies of a specified form both indicate the need for more realistic calculations of the neutron source from the rings and the radiation belt loss processes.

  4. Particle pressure and current density in the magnetosphere of Saturn: Origin of the Saturnian ring current

    NASA Astrophysics Data System (ADS)

    Sergis, N.; Krimigis, S. M.; Roelof, E. C.; Mitchell, D. G.; Rymer, A. M.; Arridge, C. S.; Krupp, N.; Thomsen, M. F.; Hamilton, D. C.; McAndrews, H. J.; Coates, A. J.; Wilson, R. J.; Dougherty, M. K.; Young, D. T.

    2009-12-01

    We report initial results on the distribution of the thermal plasma, energetic particle and magnetic field pressure in the equatorial magnetosphere, as measured by the Magnetospheric Imaging Instrument (MIMI), Cassini Plasma Spectrometer (CAPS) and the flux gate magnetometer (MAG) onboard the Cassini spacecraft, currently orbiting Saturn. Data were obtained during 11 passes from September 2005 to May 2006, when the spacecraft was particularly close (±1 Rs) to the nominal magnetic equator in the range 6 to 15 RS. The radial gradient of the total pressure is compared to the inertial body force in order to determine their relative contribution to the Saturnian ring current, and an average radial profile of the azimuthal current intensity is presented. The results can be summarized as follows: (1) The suprathermal (> 3 keV) pressure contribution to the total particle pressure becomes significant outside 8-9 Rs, exceeding 50% for r between 12 and 15 Rs. (2) The plasma beta (particle pressure/magnetic pressure) remains above 1 outside 8 RS, reaching ~3 to ~10 between 11 and 14 Rs. (3) The comparison between the inertial body force and the radial pressure gradient shows that both terms are close at 9-10 Rs, with the pressure gradient becoming dominant outside of 11 Rs. (4) The azimuthal ring current intensity develops a maximum region between approximately 8 and 12 Rs, reaching values of 100-150 pA/m^2. Outside this region, it drops with radial distance faster than the 1/r dependence that a disk current model would suggest.

  5. Global Ring Current Ion Distributions Obtained by IMAGE/HENA DURING STORMS AND SUBSTORMS

    NASA Astrophysics Data System (ADS)

    Brandt, P. C.; Ganushkina, N.; Zheng, Y.; Fok, M.; Mitchell, D. G.; Demajistre, R.; Roelof, E. C.

    2005-05-01

    Global Energetic Neutral Atom (ENA) images of the Hydrogen and Oxygen ring current in the 10-200 keV range have been obtained by IMAGE/HENA for five years. Approximately 40 storms have been succesfully imaged. Over the years a constrained linear inversion technique has been developed that can retrieve the equatorial ring current ion distributions from the ENA images. It uses the Tsyganenko [2003] magnetic field model and assumes pitch-angle distributions based on in-situ data. We investigate the general morphology of the ring current during storm times with special attention to the question of how much the storm-time substorm injections contribute to the ring current pressure. We discuss and compare observations with ring current models.

  6. Quantum periodicity in the critical current of superconducting rings with asymmetric link-up of current leads

    NASA Astrophysics Data System (ADS)

    Burlakov, A. A.; Chernykh, A. V.; Gurtovoi, V. L.; Ilin, A. I.; Mikhailov, G. M.; Nikulov, A. V.; Tulin, V. A.

    2017-08-01

    We use superconducting rings with asymmetric link-up of current leads for experimental investigation of winding number change at magnetic field corresponding to the half of the flux quantum inside the ring. According to the conventional theory, the critical current of such rings should change by jump due to this change. Experimental data obtained at measurements of aluminum rings agree with theoretical prediction in magnetic flux region close to integer numbers of the flux quantum and disagree in the region close to the half of the one, where a smooth change is observed instead of the jump. First measurements of tantalum ring give a hope for the jump. Investigation of this problem may have both fundamental and practical importance.

  7. Current status of decay heat measurements, evaluations, and needs

    SciTech Connect

    Dickens, J.K.

    1986-07-01

    Over a decade ago serious concern over possible consequences of a loss-of-coolant accident in a commercial light-water reactor prompted support of several experiments designed specifically to measure the latent energy of beta-ray and gamma-ray emanations from fission products for thermal reactors. This latent energy was termed Decay Heat. At about the same time the American Nuclear Society convened a working group to develop a standard for use in computing decay heat in real reactor environs primarily for regulatory requirements. This working group combined the new experimental results and best evaluated data into a standard which was approved by the ANS and by the ANSI. The primary work since then has been: (a) on improvements to computational efforts and (b) experimental measurements for fast reactors. In addition, the need for decay-heat data has been extended well beyond the time regime of a loss-of-coolant accident; new concerns involve, for example, away-from-reactor shipments and storage. The efficacy of the ANS standard for these longer time regimes has been a subject of study with generally positive results. However, a specific problem, namely, the consequences of fission-product neutron capture, remains contentious. Satisfactory resolution of this problem merits a high priority. 31 refs., 4 figs., 1 tab.

  8. Current status of decay heat measurements, evaluations, and needs

    SciTech Connect

    Dickens, J.K.

    1986-01-01

    Over a decade ago serious concern over possible consequences of a loss-of-coolant accident in a commercial light-water reactor prompted support of several experiments designed specifically to measure the latent energy of beta-ray and gamma-ray emanations from fission products for thermal reactors. This latent energy was termed Decay Heat. At about the same time the American Nuclear Society convened a working group to develop a standard for use in computing decay heat in real reactor environs primarily for regulatory requirements. This working group combined the new experimental results and best evaluated data into a standard which was approved by the ANS and by the ANSI. The primary work since then has been (a) on improvements to computational efforts and (b) experimental measurements for fast reactors. In addition, the need for decay-heat data has been extended well beyond the time regime of a loss-of-coolant accident; new concerns involve, for example, away-from-reactor shipments and storage. The efficacy of the ANS standard for these longer time regimes has been a subject of study with generally positive results. However, a specific problem, namely, the consequences of fission-product neutron capture, remains contentious. Satisfactory resolution of this problem merits a high priority. 31 refs.

  9. Comparison study of ring current simulations with and without bubble injections

    NASA Astrophysics Data System (ADS)

    Yang, Jian; Toffoletto, Frank R.; Wolf, Richard A.

    2016-01-01

    For many years, stand-alone ring current models have been successfully producing storm time ring current enhancements without specifying explicit localized transient injections along their outer boundaries. However, both observations and simulations have suggested that the frequent burst flows or bubble injections can contribute substantially to the storm time ring current energy. In this paper, we investigate the difference in the spatial and temporal development of the ring current distribution with and without bubble injections using the Rice Convection Model-Equilibrium. The comparison study indicates that the simulation with bubble effects smoothed out along geosynchronous orbit can predict approximately the same large-scale ring current pressure distribution and electric potential pattern as the simulation with bubble effects included. Our results suggest that the increase of the hot plasma population along geosynchronous orbit can be envisaged as an integrated effect of bubble injections from the near-Earth plasma sheet. However, the observed fluctuations in the plasma population and electric field can only be captured when the mesoscale injections are included in the simulation. We also confirmed again that adiabatic convection of fully populated flux tubes cannot inject the ring current from the middle plasma sheet. The paper provides a justification for using stand-alone ring current models in the inner magnetosphere to simulate magnetic storms, without explicit consideration of bubbles and magnetic buoyancy effects inside geosynchronous orbit.

  10. Self-Consistent Ring Current/Electromagnetic Ion Cyclotron Waves Modeling

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.

    2006-01-01

    The self-consistent treatment of the RC ion dynamics and EMIC waves, which are thought to exert important influences on the ion dynamical evolution, is an important missing element in our understanding of the storm-and recovery-time ring current evolution. For example, the EMlC waves cause the RC decay on a time scale of about one hour or less during the main phase of storms. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Under certain conditions, relativistic electrons, with energies 21 MeV, can be removed from the outer radiation belt by EMIC wave scattering during a magnetic storm. That is why the modeling of EMIC waves is critical and timely issue in magnetospheric physics. This study will generalize the self-consistent theoretical description of RC ions and EMIC waves that has been developed by Khazanov et al. [2002, 2003] and include the heavy ions and propagation effects of EMIC waves in the global dynamic of self-consistent RC - EMIC waves coupling. The results of our newly developed model that will be presented at the meeting, focusing mainly on the dynamic of EMIC waves and comparison of these results with the previous global RC modeling studies devoted to EMIC waves formation. We also discuss RC ion precipitations and wave induced thermal electron fluxes into the ionosphere.

  11. Interplay Between Ionospheric Outflow and the Ring Current During Magnetospheric Storms

    NASA Astrophysics Data System (ADS)

    Welling, D. T.; Jordanova, V. K.; Zaharia, S. G.

    2011-12-01

    It is now well established that ionospheric outflow is an important source of plasma, especially heavy ions, for the terrestrial magnetosphere. During active magnetospheric conditions, outflow is enhanced as additional energy is supplied to the magnetosphere-ionosphere system. Much of the outflowing plasma traverses through the plasma sheet to populate and energize the ring current. As the ring current builds up, it can feed back to the ionosphere alter outflow dynamics. For example, region 2 Field-Aligned Currents (FACs) driven by ring current pressure gradients change electron precipitation patterns and the ionospheric potential pattern, which alters joule and topside heating, horizontal transport and centrifugal acceleration, and other outflow mechanics. This two-way dependence between the ring current and the ionosphere creates a highly non-linear system that is not well understood. This work uses first-principles based numerical modeling to examine the relationship between the ring current and ionospheric outflow. Four models are used: the well known BATS-R-US magnetohydrodynamic (MHD) model, a height integrated ionospheric electrodynamics solver, the Polar Wind Outflow Model (PWOM), and the Ring current Atmosphere interactions Model with Self Consistent Magnetic field (RAM-SCB). All four models are coupled through the Space Weather Modeling Framework (SWMF). A magnetospheric storm is first simulated with RAM-SCB in one way coupled mode so that the ring current is fed by the other codes but cannot feed back into the whole system. The storm is then re-simulated with RAM-SCB in two-way coupled mode so that feedback between the ring current and the ionospheric outflow model is properly included. This simulation is compared against the baseline simulation to assess the importance of this feedback and identify key processes. Outflow fluxes for H+, O+, and He+ are examined to understand how outflow is changed when the ring current can feed back into the ionosphere

  12. The two-way relationship between ionospheric outflow and the ring current

    NASA Astrophysics Data System (ADS)

    Welling, D. T.; Jordanova, V. K.; Glocer, A.; Toth, G.; Liemohn, M. W.; Weimer, D. R.

    2015-06-01

    It is now well established that the ionosphere, because it acts as a significant source of plasma, plays a critical role in ring current dynamics. However, because the ring current deposits energy into the ionosphere, the inverse may also be true: the ring current can play a critical role in the dynamics of ionospheric outflow. This study uses a set of coupled, first-principles-based numerical models to test the dependence of ionospheric outflow on ring current-driven region 2 field-aligned currents (FACs). A moderate magnetospheric storm event is modeled with the Space Weather Modeling Framework using a global MHD code (Block Adaptive Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), a polar wind model (Polar Wind Outflow Model), and a bounce-averaged kinetic ring current model (ring current atmosphere interaction model with self-consistent magnetic field, RAM-SCB). Initially, each code is two-way coupled to all others except for RAM-SCB, which receives inputs from the other models but is not allowed to feed back pressure into the MHD model. The simulation is repeated with pressure coupling activated, which drives strong pressure gradients and region 2 FACs in BATS-R-US. It is found that the region 2 FACs increase heavy ion outflow by up to 6 times over the noncoupled results. The additional outflow further energizes the ring current, establishing an ionosphere-magnetosphere mass feedback loop. This study further demonstrates that ionospheric outflow is not merely a plasma source for the magnetosphere but an integral part in the nonlinear ionosphere-magnetosphere-ring current system.

  13. The two-way relationship between ionospheric outflow and the ring current

    DOE PAGES

    Welling, Daniel T.; Jordanova, Vania Koleva; Glocer, Alex; ...

    2015-06-01

    It is now well established that the ionosphere, because it acts as a significant source of plasma, plays a critical role in ring current dynamics. However, because the ring current deposits energy into the ionosphere, the inverse may also be true: the ring current can play a critical role in the dynamics of ionospheric outflow. This study uses a set of coupled, first-principles-based numerical models to test the dependence of ionospheric outflow on ring current-driven region 2 field-aligned currents (FACs). A moderate magnetospheric storm event is modeled with the Space Weather Modeling Framework using a global MHD code (Block Adaptivemore » Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), a polar wind model (Polar Wind Outflow Model), and a bounce-averaged kinetic ring current model (ring current atmosphere interaction model with self-consistent magnetic field, RAM-SCB). Initially, each code is two-way coupled to all others except for RAM-SCB, which receives inputs from the other models but is not allowed to feed back pressure into the MHD model. The simulation is repeated with pressure coupling activated, which drives strong pressure gradients and region 2 FACs in BATS-R-US. It is found that the region 2 FACs increase heavy ion outflow by up to 6 times over the non-coupled results. The additional outflow further energizes the ring current, establishing an ionosphere-magnetosphere mass feedback loop. This study further demonstrates that ionospheric outflow is not merely a plasma source for the magnetosphere but an integral part in the nonlinear ionosphere-magnetosphere-ring current system.« less

  14. The two-way relationship between ionospheric outflow and the ring current

    SciTech Connect

    Welling, Daniel T.; Jordanova, Vania Koleva; Glocer, Alex; Toth, Gabor; Liemohn, Michael W.; Weimer, Dan R.

    2015-06-01

    It is now well established that the ionosphere, because it acts as a significant source of plasma, plays a critical role in ring current dynamics. However, because the ring current deposits energy into the ionosphere, the inverse may also be true: the ring current can play a critical role in the dynamics of ionospheric outflow. This study uses a set of coupled, first-principles-based numerical models to test the dependence of ionospheric outflow on ring current-driven region 2 field-aligned currents (FACs). A moderate magnetospheric storm event is modeled with the Space Weather Modeling Framework using a global MHD code (Block Adaptive Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), a polar wind model (Polar Wind Outflow Model), and a bounce-averaged kinetic ring current model (ring current atmosphere interaction model with self-consistent magnetic field, RAM-SCB). Initially, each code is two-way coupled to all others except for RAM-SCB, which receives inputs from the other models but is not allowed to feed back pressure into the MHD model. The simulation is repeated with pressure coupling activated, which drives strong pressure gradients and region 2 FACs in BATS-R-US. It is found that the region 2 FACs increase heavy ion outflow by up to 6 times over the non-coupled results. The additional outflow further energizes the ring current, establishing an ionosphere-magnetosphere mass feedback loop. This study further demonstrates that ionospheric outflow is not merely a plasma source for the magnetosphere but an integral part in the nonlinear ionosphere-magnetosphere-ring current system.

  15. The circular current in a conducting mesoscopic ring with coupled quantum dot

    NASA Astrophysics Data System (ADS)

    Bo, Zhou

    2016-11-01

    In this paper, we investigate the circular current in the metallic ring coupled with two QDs connected with two ferromagnetic leads with the in-plane electric field ξ which is perpendicular to the wire applied to the ring by using the non-equilibrium Green's function technique. We find that in this systems the circular current in the ring can be tuned by the voltages between left and right electrodes, the temperature, the spin polarization, and the energy of the QDs and the electric field ɛ. With these parameters varied, the values and direction of the circular current can be controlled, so we can control the values and the directions of the magnetic field produced at the ring center. In addition, there also has the function of spin filter in the P and has the function of suppression of the circular current for large 𝒫 of the AP. So this structure has potential applications in designing spin-based quantum devices.

  16. Ring current development during the great geomagnetic storm of February 1986

    NASA Technical Reports Server (NTRS)

    Hamilton, D. C.; Gloeckler, G.; Ipavich, F. M.; Wilken, B.; Stuedemann, W.

    1988-01-01

    The variations of the ring current energy density and composition during the great magnetic storm of February 1986 were investigated using particle measurements obtained by the charge-energy-mass instrument on the AMPTE Charge Composition Explorer spacecraft. The ring current composition of this storm, which had a complicated main phase and a minimum Dst of -312 nT on February 9, was followed for five days from the prestorm quiet time to the early recovery phase. Results suggested that the very rapid initial Dst recovery (tau of about 9.3 hrs) in this storm resulted largely from the rapid loss of 75- to 100-keV O(+) via charge exchange in the inner portion of the ring current. It is proposed that a major O(+) + N(+) ring current component generally exists near the maximum phase of great storms.

  17. Coulomb collisions of ring current particles: Indirect source of heat for the ionosphere

    NASA Technical Reports Server (NTRS)

    Cole, K. D.

    1975-01-01

    The additional energy requirements of the topside ionosphere during a magnetic storm are less than one quarter of the ring current energy. This energy is supplied largely by Coulomb collisions of ring current protons of energy less than about 20 keV with background thermal electrons which conduct the heat to the ionosphere. Past criticisms are discussed of this mechanism for the supply of energy to the SAR-arc and neighboring regions of the ionosphere.

  18. Protons as the prime contributors to the storm time ring current. [measured from Explorer 45

    NASA Technical Reports Server (NTRS)

    Berko, F. W.; Cahill, L. J., Jr.; Fritz, T. A.

    1974-01-01

    Following a large magnetic storm (17 June 1972), Explorer 45 measured the equatorial particle populations and magnetic field. Using data obtained during the symmetic recovery phase, it is shown that through a series of self-consistent calculations, the measured protons with energies from 1 to 872 keV, can account for the observed ring current magnetic effects within experimental uncertainities. This enables an upper limit to be set for the heavy ion contribution to the storm time ring current.

  19. The rings of Saturn: State of current knowledge and some suggestions for future studies

    NASA Technical Reports Server (NTRS)

    Cuzzi, J. N.

    1978-01-01

    The state of our current knowledge of the properties of the ring system as a whole, and of the particles individually, is assessed. Attention is primarily devoted to recent results and possibilities for exploration of the ring system by a Saturn orbiter. In particular, the infrared and microwave properties of the ring system are discussed. The behavior of the ring brightness is not well understood in the critical transition spectral region from approximately 100 micrometers to approximately 1 cm. Also, the dynamical behavior of the ring system is discussed. Recent theoretical studies show that ongoing dynamical effects continually affect the ring structure in azimuth (possibly producing the A ring brightness asymmetry) and in the vertical direction. Orbital spacecraft-based studies of the rings will offer several unique advantages and impact important cosmogonical questions. Bistatic radar studies and millimeter-wavelength spectrometer/radiometry will give particle sizes and composition limits needed to resolve the question of the density of the rings, and provide important boundary conditions on the state of Saturn's protoplanetary nebula near the time of planetary formation.

  20. Global Evolution of the Earth's Magnetosphere in Response to a Sudden Ring Current Injection

    NASA Astrophysics Data System (ADS)

    No, Jincheol; Choe, Gwangson; Park, Geunseok

    2014-05-01

    The dynamical evolution of the Earth's magnetosphere loaded with a transiently enhanced ring current is investigated by global magnetohydrodynamic simulations. Two cases with different values of the primitive ring current are considered. In one case, the initial ring current is strong enough to create a magnetic island in the magnetosphere. The magnetic island readily reconnects with the earth-connected ambient field and is destroyed as the system approaches a steady equilibrium. In the other case, the initial ring current is not so strong, and the initial magnetic field configuration bears no magnetic island, but features a wake of bent field lines, which is smoothed out through the relaxing evolution of the magnetosphere. The relaxation time of the magnetosphere is found to be about five to six minutes, over which the ring current is reduced to about a quarter of its initial value. Before reaching a steady state, the magnetosphere is found to undergo an overshooting expansion and a subsequent contraction. Fast and slow magnetosonic waves are identified to play an important role in the relaxation toward equilibrium. Our study suggests that a sudden injection of the ring current can generate an appreciable global pulsation of the magnetosphere.

  1. Transient electric current through an Aharonov-Bohm ring after switching of a two-level system

    NASA Astrophysics Data System (ADS)

    Tatara, Gen

    2002-05-01

    The response of the electronic current through an Aharonov-Bohm ring after a two-level-system is switched on is calculated perturbatively by use of a nonequilibrium Green function. In the ballistic case the amplitude of the Aharonov-Bohm oscillation is shown to decay to a new equilibrium value due to scattering into other electronic states. The relaxation of the Altshuler-Aronov-Spivak oscillation in the diffusive case, due to the dephasing effect, is also calculated. The time scale of the relaxation is determined by characteristic relaxation times of the system and the splitting of a two-level-system. The oscillation phase is not affected. Experimental studies of current response would give us direct information about characteristic times of mesoscopic systems.

  2. Sensitivity to electronvolt-scale sterile neutrinos at a 3.8-GeV/c muon decay ring

    SciTech Connect

    Tunnell, Christopher D.

    2013-03-01

    The liquid-scintillator neutrino-detector (LSND) and mini booster neutrino experiment (MiniBooNE) experiments claim to observe the oscillation $\\bar{v}$μ → $\\bar{v}$e, which can only be explained by additional neutrinos and is a claim that must be further tested. This thesis proposes a new accelerator and experiment called neutrinos from stored muons ( STORM) to refute or confirm the oscillation these claims by studying the CPT-equivalent channel ve → vμ . A 3.8-GeV/c muon decay ring is proposed with neutrino detectors placed 20 m and 2000 m from the decay ring. The detector technology would be a magnetized iron sampling calorimeter, where the magnetic field is induced by a superconducting transmission line. In a frequentist study, the sensitivity of this experiment after 5 years would be >10σ . The range of the thesis discussion starts with the proton front-end design and ends with neutrino parameter estimation. After describing the phenomenology of sterile neutrinos, the facility and detector performance work is presented. Finally, the systematics are explained before the sensitivity and parameter-estimation works are explained

  3. The effect of the electron temperature and current density profiles on the plasma current decay in JT-60U disruptions

    NASA Astrophysics Data System (ADS)

    Shibata, Y.; Isayama, A.; Miyamoto, S.; Kawakami, S.; Watanabe, K. Y.; Matsunaga, G.; Kawano, Y.; Lukash, V. E.; Khayrutdinov, R. R.; the JT-60 Team

    2014-04-01

    The plasma current decay during the initial phase of the current quench in JT-60U disruption has been calculated by a disruption simulation code (DINA) using the measured electron temperature Te profile. In the case of fast plasma current decay, Te has a peaked profile immediately after a thermal quench and the Te profile does not change significantly during the initial phase of the current quench. On the other hand, in the case of a slow plasma current decay, the Te profile is broader immediately after the thermal quench, and the Te profile shrinks. The results of the DINA simulation show that the plasma internal inductance Li increases during the initial phase of the current quench, whereas the plasma external inductance Le does not change over time. If the plasma is represented by a simple electrical circuit, the time derivative of Li functions as a resistance on the plasma current decay. It was confirmed that the increase in Li is caused by current diffusion toward the core plasma due to the decrease in Te in the intermediate and edge regions.

  4. Quantum rings in magnetic fields and spin current generation.

    PubMed

    Cini, Michele; Bellucci, Stefano

    2014-04-09

    We propose three different mechanisms for pumping spin-polarized currents in a ballistic circuit using a time-dependent magnetic field acting on an asymmetrically connected quantum ring at half filling. The first mechanism works thanks to a rotating magnetic field and produces an alternating current with a partial spin polarization. The second mechanism works by rotating the ring in a constant field; like the former case, it produces an alternating charge current, but the spin current is dc. Both methods do not require a spin-orbit interaction to achieve the polarized current, but the rotating ring could be used to measure the spin-orbit interaction in the ring using characteristic oscillations. On the other hand, the last mechanism that we propose depends on the spin-orbit interaction in an essential way, and requires a time-dependent magnetic field in the plane of the ring. This arrangement can be designed to pump a purely spin current. The absence of a charge current is demonstrated analytically. Moreover, a simple formula for the current is derived and compared with the numerical results.

  5. Concentric rings of polystyrene and titanium dioxide nanoparticles patterned by alternating current signal guided coffee ring effect

    NASA Astrophysics Data System (ADS)

    Mu, Jinhua; Lin, Peng; Xia, Qiangfei

    2014-06-01

    The authors studied the surface deposition of nanoparticles by introducing an alternating current (AC) signal into the millimeter-sized nanoparticle droplet. For both polystyrene (PS) in deionized (DI) water and titanium dioxide (TiO2) in toluene, the nanoparticles self-assembled into regular concentric rings over a larger area on the substrate during the droplet drying process. The patterned area decreased, and the inter-ring spacing increased with higher AC frequencies for the TiO2/toluene system, while those for the PS/DI water system only changed slightly. The frequency dependent pattern formation was interpreted by the interaction between different factors such as capillary flow and the AC signal introduced dielectrophoresis force.

  6. Cyclical reconnection in Saturn's magnetotail and the maintenance of ring current region asymmetry

    NASA Astrophysics Data System (ADS)

    Khurana, Krishan; Dougherty, Michele; Russell, Christopher; Paranicas, Chris; Brandt, Pontus

    2010-05-01

    Field, plasma and energetic particle observations from Saturn's magnetosphere provide evidence of a rotating partial ring current located between the radial distance of 8 and 13 Rs. Khurana et al. (2009) showed that the rotating partial ring current has several profound effects on the structure of the magnetosphere. In the outer magnetosphere, the partial ring current imposes a sinusoidal variation of the magnetic field in the lobe region. The resulting asymmetric distribution of magnetic flux in Saturn's magnetosphere leads to an asymmetric lift of the magnetosphere by the solar wind which tilts the planet's current sheet even when the internal field is completely axisymmetric. The current sheet tilt generates out-of-phase periodicities in which the particle fluxes and the magnetic field strength are anti-correlated. In this presentation, we explore ideas on how the ring current region anomalies can be generated and maintained in the magnetosphere. In particular, we focus on a model of self-generation of energetic particles' azimuthal asymmetry from periodic reconnection induced particle injections and bursty-bulk flows launched into inner magnetosphere from the neutral line. Finally we discuss why the magnetosphere favors the azimuthal m = 1 mode over m = 0 (uniform ring current) and other higher order and non-integral modes. We show that for a given integrated energy density of particles , this mode produces the most stretched configuration in the reconnection region and thus the strongest feedback reaction from the magnetotail.

  7. Localized persistent spin currents in defect-free quasiperiodic rings with Aharonov-Casher effect

    NASA Astrophysics Data System (ADS)

    Qiu, R. Z.; Chen, C. H.; Cheng, Y. H.; Hsueh, W. J.

    2015-06-01

    We propose strongly localized persistent spin current in one-dimensional defect-free quasiperiodic Thue-Morse rings with Aharonov-Casher effect. The results show that the characteristics of these localized persistent currents depend not only on the radius filling factor, but also on the strength of the spin-orbit interaction. The maximum persistent spin currents in systems always appear in the ring near the middle position of the system array whether or not the Thue-Morse rings array is symmetrical. The magnitude of the persistent currents is proportional to the sharpness of the resonance peak, which is dependent on the bandwidth of the allowed band in the band structure. The maximum persistent spin currents also increase exponentially as the generation order of the system increases.

  8. The "anthracene problem": closed-form conjugated-circuit models of ring currents in linear polyacenes.

    PubMed

    Fowler, Patrick W; Myrvold, Wendy

    2011-11-17

    Conjugated-circuit models for induced π ring currents differ in the types of circuit that they include and the weights attached to them. Choice of circuits for general π systems can be expressed compactly in terms of matchings of the circuit-deleted molecular graph. Variants of the conjugated-circuit model for induced π currents are shown to have simple closed-form solutions for linear polyacenes. Despite differing assumptions about the effect of cycle area, all the models predict the most intense perimeter current in the central rings, in general agreement with ab initio current-density maps. All tend to overestimate the rate of increase with N of the central ring current for the [N]polyacene, in comparison with molecular-orbital treatments using ipsocentric ab initio, pseudo-π, and Hückel-London approaches.

  9. Current-induced SQUID behavior of superconducting Nb nano-rings.

    PubMed

    Sharon, Omri J; Shaulov, Avner; Berger, Jorge; Sharoni, Amos; Yeshurun, Yosef

    2016-06-20

    The critical temperature in a superconducting ring changes periodically with the magnetic flux threading it, giving rise to the well-known Little-Parks magnetoresistance oscillations. Periodic changes of the critical current in a superconducting quantum interference device (SQUID), consisting of two Josephson junctions in a ring, lead to a different type of magnetoresistance oscillations utilized in detecting extremely small changes in magnetic fields. Here we demonstrate current-induced switching between Little-Parks and SQUID magnetoresistance oscillations in a superconducting nano-ring without Josephson junctions. Our measurements in Nb nano-rings show that as the bias current increases, the parabolic Little-Parks magnetoresistance oscillations become sinusoidal and eventually transform into oscillations typical of a SQUID. We associate this phenomenon with the flux-induced non-uniformity of the order parameter along a superconducting nano-ring, arising from the superconducting leads ('arms') attached to it. Current enhanced phase slip rates at the points with minimal order parameter create effective Josephson junctions in the ring, switching it into a SQUID.

  10. Current-induced SQUID behavior of superconducting Nb nano-rings

    NASA Astrophysics Data System (ADS)

    Sharon, Omri J.; Shaulov, Avner; Berger, Jorge; Sharoni, Amos; Yeshurun, Yosef

    2016-06-01

    The critical temperature in a superconducting ring changes periodically with the magnetic flux threading it, giving rise to the well-known Little-Parks magnetoresistance oscillations. Periodic changes of the critical current in a superconducting quantum interference device (SQUID), consisting of two Josephson junctions in a ring, lead to a different type of magnetoresistance oscillations utilized in detecting extremely small changes in magnetic fields. Here we demonstrate current-induced switching between Little-Parks and SQUID magnetoresistance oscillations in a superconducting nano-ring without Josephson junctions. Our measurements in Nb nano-rings show that as the bias current increases, the parabolic Little-Parks magnetoresistance oscillations become sinusoidal and eventually transform into oscillations typical of a SQUID. We associate this phenomenon with the flux-induced non-uniformity of the order parameter along a superconducting nano-ring, arising from the superconducting leads (‘arms’) attached to it. Current enhanced phase slip rates at the points with minimal order parameter create effective Josephson junctions in the ring, switching it into a SQUID.

  11. Current-induced SQUID behavior of superconducting Nb nano-rings

    PubMed Central

    Sharon, Omri J.; Shaulov, Avner; Berger, Jorge; Sharoni, Amos; Yeshurun, Yosef

    2016-01-01

    The critical temperature in a superconducting ring changes periodically with the magnetic flux threading it, giving rise to the well-known Little-Parks magnetoresistance oscillations. Periodic changes of the critical current in a superconducting quantum interference device (SQUID), consisting of two Josephson junctions in a ring, lead to a different type of magnetoresistance oscillations utilized in detecting extremely small changes in magnetic fields. Here we demonstrate current-induced switching between Little-Parks and SQUID magnetoresistance oscillations in a superconducting nano-ring without Josephson junctions. Our measurements in Nb nano-rings show that as the bias current increases, the parabolic Little-Parks magnetoresistance oscillations become sinusoidal and eventually transform into oscillations typical of a SQUID. We associate this phenomenon with the flux-induced non-uniformity of the order parameter along a superconducting nano-ring, arising from the superconducting leads (‘arms’) attached to it. Current enhanced phase slip rates at the points with minimal order parameter create effective Josephson junctions in the ring, switching it into a SQUID. PMID:27321733

  12. Lepton Universality, |V(Us)| and Search for Second Class Current in Tau Decays

    SciTech Connect

    Banerjee, Swagato; /Victoria U.

    2011-11-10

    Several hundred million {tau} decays have been studied with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. Recent results on Charged Current Lepton Universality and two independent measurements of |V{sub us}| using {tau}{sup -} {yields} e{sup -}{bar {nu}}{sub e}{nu}{sub {tau}}, {mu}{sup -}{bar {nu}}{sub {mu}}{nu}{sub {tau}}, {pi}{sup -}{nu}{sub {tau}}, K{sup -} {nu}{sub {tau}} and K{sub S}{sup 0}{pi}{sup -} {nu}{sub {tau}} decays, and a search for Second Class Current in {tau}{sup -} {yields} {pi}{sup -} {omega}{nu}{sub {tau}} decays are presented, where the charge conjugate decay modes are also implied.

  13. Aromatic interactions in model peptide β-hairpins: ring current effects on proton chemical shifts.

    PubMed

    Rajagopal, Appavu; Aravinda, Subrayashastry; Raghothama, Srinivasarao; Shamala, Narayanaswamy; Balaram, Padmanabhan

    2012-01-01

    Crystal structures of eight peptide β-hairpins in the sequence Boc-Leu-Phe-Val-Xxx-Yyy-Leu-Phe-Val-OMe revealed that the Phe(2) and Phe(7) aromatic rings are in close spacial proximity, with the centroid-centroid distance (R(cen)) of 4.4-5.4 Å between the two phenyl rings. Proton NMR spectra in chloroform and methanol solution reveal a significant upfield shift of the Phe(7) C(δ,δ') H(2) protons (6.65-7.04 ppm). Specific assignments of the aromatic protons have been carried out in the peptide Boc-Leu-Phe-Val-(D)Pro-(L)Pro-Leu-Phe-Val-OMe (6). The anticipated ring current shifts have been estimated from the aromatic ring geometrics observed in crystals for all eight peptides. Only one of the C(δ,δ') H proton lies in the shielding zone with rapid ring flipping, resulting in averaging between the two extreme chemical shifts. An approximate estimate of the population of conformations, which resemble crystal state orientation, may be obtained. Key nuclear Overhauser effects (NOEs) between facing Phe side chains provide support for close similarity between the solid state and solution conformation. Temperature dependence of aromatic ring proton chemical shift and line widths for peptide 6 (Boc-Leu-Phe-Val-(D)Pro-(L)Pro-Leu-Phe-Val-OMe) and the control peptide Boc-Leu-Val-Val-(D)Pro-Gly-Leu-Phe-Val-OMe establish an enhanced barrier to ring flipping when the two Phe rings are in proximity. Modeling studies suggest that small, conformational adjustment about C(α)-C(β) (χ(1) ) and C(β)-C(γ) (χ(2) ) bonds of both the Phe residues may be required in order to permit unhindered, uncorrelated flipping of both the Phe rings. The maintenance of the specific aromatic ring orientation in organic solvents provides evidence for significant stabilizing interaction. Copyright © 2012 Wiley Periodicals, Inc.

  14. Electronic delocalization and persistent currents in nonsymmetric-dimer mesoscopic rings threaded by magnetic flux

    NASA Astrophysics Data System (ADS)

    Hu, X. F.; Peng, Z. H.; Peng, R. W.; Liu, Y. M.; Qiu, F.; Huang, X. Q.; Hu, A.; Jiang, S. S.

    2004-06-01

    We investigate electronic delocalization and magnetic-flux-induced persistent current in the mesoscopic ring, which is constructed according to the nonsymmetric-dimer (NSD) model. The flux-dependent energy spectra, electronic wavefunctions, and persistent currents are theoretically obtained. It is demonstrated that due to the localization-delocalization transition of electrons, the electronic state in the NSD ring can be localized, extended, and the intermediate case between extended states and localized ones. The persistent current (PC) approaches the behavior of free electrons if the Fermi level is around the near-resonant energy. Otherwise, the PC is depressed dramatically. This conclusion could be generalized to other correlated-disordered systems.

  15. Impact of Ring Current Ions on Electromagnetic Ion Cyclotron Wave Dispersion Relation

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.

    2007-01-01

    Effect of the ring current ions in the real part of electromagnetic ion Cyclotron wave dispersion relation is studied on global scale. Recent Cluster observations by Engebretson et al. showed that although the temperature anisotropy of is energetic (> 10 keV) ring current protons was high during the entire 22 November 2003 perigee pass, electromagnetic ion cyclotron waves were observed only in conjunction with intensification of the ion fluxes below 1 keV by over an order of magnitude. To study the effect of the ring current ions on the wave dispersive properties and the corresponding global wave redistribution, we use a self-consistent model of interacting ring current and electromagnetic ion cyclotron waves, and simulate the May 1998 storm. The main findings of our simulation can be summarized as follows: First, the plasma density enhancement in the night MLT sector during the main and recovery storm phases is mostly caused by injection of suprathermal plasma sheet H + (approximately < 1 keV), which dominate the thermal plasma density. Second, during the recovery storm phases, the ring current modification of the wave dispersion relation leads to a qualitative change of the wave patterns in the postmidnight-dawn sector for L > 4.75. This "new" wave activity is well organized by outward edges of dense suprathermal ring current spots, and the waves are not observed if the ring current ions are not included in the real part of dispersion relation. Third, the most intense wave-induced ring current precipitation is located in the night MLT sector and caused by modification of the wave dispersion relation. The strongest precipitating fluxes of about 8 X 10(exp 6)/ (cm(exp 2) - s X st) are found near L=5.75, MLT=2 during the early recovery phase on 4 May. Finally, the nightside precipitation is more intense than the dayside fluxes, even if there are less intense waves, because the convection field moves ring current ions into the loss cone on the nightside, but drives

  16. The plasmasheet H+ and O+ contribution on the storm time ring current

    NASA Astrophysics Data System (ADS)

    Mouikis, C.; Bingham, S.; Kistler, L. M.; Spence, H. E.; Gkioulidou, M.; Claudepierre, S. G.; Farrugia, C. J.

    2015-12-01

    The source population of the storm time ring current is the night side plasma sheet. We use Van Allen Probes and Cluster observations to determine the contribution of the convecting plasma sheet H+ and O+ particles in the storm time development of the ring current. Using the Volland-Stern model with a dipole magnetic field together with the identification of the observed energy cutoffs in the particle spectra, we specify the pressure contributed by H+ and O+ populations that are on open drift paths vs. the pressure contributed by the trapped populations, for different local times. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L~2 and their pressure compares to the local magnetic field pressure as deep as L~3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current.

  17. An alternative analysis of low- and high-altitude observations of ring current ions during a storm recovery phase

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.

    1977-01-01

    Explorer 45 equatorial observations of ring current ions during a storm recovery phase have shown pitch angle distributions and decay rates inconsistent with proton charge exchange with neutral hydrogen. This inconsistency has led to the suggestion that recovery phase ring current ions at L less than or equal to 4 and energies not greater than 50 keV are dominated by He(+) rather than protons. The absence of He(+) on flux tubes from which H(+) and O(+) were precipitating in ion mass spectrometer measurements made during the same period by the low-altitude polar-orbiting satellite 1971-089A led Sharp et al. to suggest a source of H(+) and O(+) to L = 3 during this period. An alternative explanation, in which the magnetic field lines labeled L = 3 at the earth's surface near local midnight were mapped to about 3.7 earth radii in the equatorial plane during the storm recovery phase and during the period of enhanced activity, is proposed. If the proposed explanation is correct, the observations of Sharp et al. are not incompatible with the conclusion that the recovery phase ions at less than 50 keV were dominated by He(+) for L not greater than 3.7.

  18. An alternative analysis of low- and high-altitude observations of ring current ions during a storm recovery phase

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.

    1977-01-01

    Explorer 45 equatorial observations of ring current ions during a storm recovery phase have shown pitch angle distributions and decay rates inconsistent with proton charge exchange with neutral hydrogen. This inconsistency has led to the suggestion that recovery phase ring current ions at L less than or equal to 4 and energies not greater than 50 keV are dominated by He(+) rather than protons. The absence of He(+) on flux tubes from which H(+) and O(+) were precipitating in ion mass spectrometer measurements made during the same period by the low-altitude polar-orbiting satellite 1971-089A led Sharp et al. to suggest a source of H(+) and O(+) to L = 3 during this period. An alternative explanation, in which the magnetic field lines labeled L = 3 at the earth's surface near local midnight were mapped to about 3.7 earth radii in the equatorial plane during the storm recovery phase and during the period of enhanced activity, is proposed. If the proposed explanation is correct, the observations of Sharp et al. are not incompatible with the conclusion that the recovery phase ions at less than 50 keV were dominated by He(+) for L not greater than 3.7.

  19. A model for local current decay in a superconducting LR chain

    SciTech Connect

    Garavaglia, T.; Kauffmann, K.

    1991-04-01

    Solutions are given for the decay of the local current in both a finite and an infinite superconducting circuit consisting of a linear array of loops each containing in series an inductance L and in parallel a resistance R. Numerical results obtained from these solutions are given, and the results for local current decay for both cases are compared The properties of polynomials associated with the finite chain solution and two generating functions along with the method of solution of the diffusion type equation associated with the infinite chain model are discussed in the appendices. These solutions are used to obtain insight into the nature of the time decay of the currents in the loops resulting from crossings of the strands forming the superconducting cable of the SSC dipole magnets.

  20. Ultra-sensitive silicon photonic current sensor using a ring resonator

    NASA Astrophysics Data System (ADS)

    Wei, Bing; Zhao, Changyun; Wang, Gencheng; Dai, Tingge; Wang, Yuehai; Yang, Jianyi; Li, Yubo

    2016-08-01

    We proposed and experimentally investigated a compact and ultra-sensitive integrated photonic current sensor based on a silicon ring resonator in this paper. The current flowing through the integrated resistive TiN heater produces the Joule’s heat and changes the temperature, which results in the change of refractive index and physical dimensions of the ring. An optical spectrum analyzer is used to monitor the resonant wavelength shift of the ring. The experiment results show that the sensor achieves an ultra-high sensitivity of 6.8 × 104 nm A-2 and good linearity between real-time current and wavelength shift in the test range of 0-10 mA.

  1. Predicting electromagnetic ion cyclotron wave amplitude from unstable ring current plasma conditions

    NASA Astrophysics Data System (ADS)

    Fu, Xiangrong; Cowee, Misa M.; Jordanova, Vania K.; Gary, S. Peter; Reeves, Geoffrey D.; Winske, Dan

    2016-11-01

    Electromagnetic ion cyclotron (EMIC) waves in the Earth's inner magnetosphere are enhanced fluctuations driven unstable by ring current ion temperature anisotropy. EMIC waves can resonate with relativistic electrons and play an important role in precipitation of MeV radiation belt electrons. In this paper, we investigate the excitation and saturation of EMIC instability in a homogeneous plasma using both linear theory and nonlinear hybrid simulations. We have explored a four-dimensional parameter space, carried out a large number of simulations, and derived a scaling formula that relates the saturation EMIC wave amplitude to initial plasma conditions. Such scaling can be used in conjunction with ring current models like ring current-atmosphere interactions model with self-consistent magnetic field to provide global dynamic EMIC wave maps that will be more accurate inputs for radiation belt modeling than statistical models.

  2. Ring currents in six-membered heterocycles: the diazaborinines (CH)2B2N2

    NASA Astrophysics Data System (ADS)

    Cernusak, I.; Fowler, P. W.; Steiner, E.

    Six of the eleven possible cyclic isomers (CH)2B2N2 are found, by geometric optimization at a correlated level of theory, to have planar closed-shell ground states. Current density maps calculated with distributed-origin coupled Hartree-Fock theory wavefunctions show that all six of these have delocalized pi-electron systems supporting diamagnetic ring currents. In comparison with benzene at the same level of theory, the isomer with lowest energy, 1,3,2,4 diazadiborinine, has a 5% greater centre of ring shielding, but 20-25% smaller mean magnetizability, mean polarizability and polarizability anisotropy.

  3. Wave-particle interaction at the plasmasphere-ring current interface

    NASA Technical Reports Server (NTRS)

    Roth, Ilan; Hudson, Mary K.

    1992-01-01

    During the plasmasphere filling process following geomagnetic storms, an outward density decrease of the cold plasma at L = 3-4 is typically observed. When this structure overlaps with the sharp inner edge of the ring current, wave activity is detected at linearly stable phase velocities. The excitation of these waves around the lower hybrid frequency and their effects on the heating of thermal ions is analyzed. It is found that lower hybrid drift waves are most effective at heating lower mass ions, e.g. plasmaspheric H(+), versus He(+), which may be heated more effectively by electromagnetic ion cyclotron waves driven unstable by the ring current loss cone.

  4. The effect of the magnetic field stretching on the development of the ring current

    NASA Astrophysics Data System (ADS)

    Ilie, R.; Toth, G.; Liemohn, M. W.; Skoug, R. M.

    2010-12-01

    While the dipolar solution for the geomagnetic field during quiet times represents a reasonable assumption, during storm activity this assumption becomes invalid. Theoretical and numerical modifications to an inner magnetosphere - Hot Electron Ion Drift Integrator (HEIDI)- model are implemented, in order to accommodate for a non-dipolar arbitrary magnetic field. HEIDI solves the time dependent, gyration and bounced averaged kinetic equation for the phase space density of one or more ring current species. In this study the effect of the magnetic field stretching on the build-up of the ring current is examined for both real and idealized input conditions.

  5. Induced fermionic charge and current densities in two-dimensional rings

    NASA Astrophysics Data System (ADS)

    Bellucci, S.; Saharian, A. A.; Grigoryan, A. Kh.

    2016-11-01

    For a massive quantum fermionic field, we investigate the vacuum expectation values (VEVs) of the charge and current densities induced by an external magnetic flux in a two-dimensional circular ring. Both the irreducible representations of the Clifford algebra are considered. On the ring edges the bag (infinite mass) boundary conditions are imposed for the field operator. This leads to the Casimir type effect on the vacuum characteristics. The radial current vanishes. The charge and the azimuthal current are decomposed into the boundary-free and boundary-induced contributions. Both these contributions are odd periodic functions of the magnetic flux with the period equal to the flux quantum. An important feature that distinguishes the VEVs of the charge and current densities from the VEV of the energy density is their finiteness on the ring edges. The current density is equal to the charge density for the outer edge and has the opposite sign on the inner edge. The VEVs are peaked near the inner edge and, as functions of the field mass, exhibit quite different features for two inequivalent representations of the Clifford algebra. We show that, unlike the VEVs in the boundary-free geometry, the vacuum charge and the current in the ring are continuous functions of the magnetic flux and vanish for half-odd integer values of the flux in units of the flux quantum. Combining the results for two irreducible representations, we also investigate the induced charge and current in parity and time-reversal symmetric models. The corresponding results are applied to graphene rings with the electronic subsystem described in terms of the effective Dirac theory with the energy gap. If the energy gaps for two valleys of the graphene hexagonal lattice are the same, the charge densities corresponding to the separate valleys cancel each other, whereas the azimuthal current is doubled.

  6. Ring-current aromaticity in triplet states of 4 n π electron monocycles

    NASA Astrophysics Data System (ADS)

    Fowler, P. W.; Steiner, E.; Jenneskens, L. W.

    2003-04-01

    The ipsocentric approach to orbital contributions to current density predicts that a triplet state of a 4 n π-electron Hückel monocycle should be aromatic, in the sense of supporting a diatropic ring current, and that this current should be carried by just four of the π electrons (three for n=1). The magnetic criterion of aromaticity is thus in agreement with Baird's classic energy-based prediction of aromatic stabilisation for these species.

  7. An Analytical Model of Wave-Induced Longshore Current Based on Power Law Wave Height Decay.

    DTIC Science & Technology

    1988-01-01

    34I ANALYtTICAL MODEL OF NAVE-INDUCED LON6SHORE CURRENT BASED ON PONE* LAW.. (U) COASTAL ENG INEERING RESEAKNH CENTER VICKSBURG NS J N SMITH ET AL...j . - .L .V . : ; * AN ANALYTICAL MODEL OF WAVE-INDUCED ~ z * LONGSHORE CURRENT BASED ON POWER LAW * - WAVE HEIGHT DECAY by Jane McKee...I_ I IF 31592 11. TITLE (Include Security Classfication) • An Analytical Model of Wave-Induced Longshore Current Based on Power Law . Wave

  8. Noise-Assisted Currents in a Cylinder-Like Set of Mesoscopic Rings

    NASA Astrophysics Data System (ADS)

    Dajka, J.; Kostur, M.; Luczka, J.; Szopa, M.; Zipper, E.

    2003-07-01

    We study magnetic fluxes and currents in a set of mesoscopic rings which form a cylinder. We investigate the noiseless system as well as the influence of equilibrium and non-equilibrium fluctuations on the properties of selfsustaining currents. Thermal equilibrium Nyquist noise does not destroy selfsustaining currents up to temperatures of the same order as the critical temperature for selfsustaining currents. For temperatures below the critical temperature, randomness in the distribution of parity of the coherent electrons can lead to disappearing of selfsustaining currents and inducing new metastable states. For temperatures above the critical temperature, it causes a creation of new metastable states with non-zero currents.

  9. Influence of plasma opacity on current decay after disruptions in tokamaks

    NASA Astrophysics Data System (ADS)

    Lukash, V. E.; Mineev, A. B.; Morozov, D. Kh.

    2007-11-01

    Current decays after disruptions as well as after noble gas injections in tokamaks are examined. As is shown, the cooled plasmas at the stage of current decay are partially opaque for radiation in lines giving the main impact into total thermal losses. The thermal balance is supposed to be determined by Ohmic heating and radiative losses. A zero-dimensional model for radiation losses and temperature distribution over minor radius is used. Plasma current evolution is simulated with DIMRUN and DINA codes. Impurity distribution over ionization states is calculated from the time-dependent set of differential equations. The opacity effects are found to be most important for simulation of JET disruption experiments with beryllium- and carbon-seeded plasmas. The decay times calculated are in good agreement with the experimental values. Current decays in beryllium-, carbon-, argon- and neon-seeded plasmas for ITER parameters are simulated. The temperatures after thermal quench are shown to be significantly higher in comparison with the model of transparent plasmas. Opacity effects are found to be most important for Be- and C-seeded plasmas. Runaway electron currents are damped significantly if opacity effects are taken into account in any case examined.

  10. Self-consistent model of magnetospheric ring current and propagating electromagnetic ion cyclotron waves: 2. Wave-induced ring current precipitation and thermal electron heating

    NASA Astrophysics Data System (ADS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.; Liemohn, M. W.

    2007-04-01

    This paper continues presentation and discussion of the results from our new global self-consistent theoretical model of interacting ring current ions and propagating electromagnetic ion cyclotron waves (Khazanov et al., 2006) currently developing in NASA Marshall Space Flight Center. To study the effects of electromagnetic ion cyclotron wave propagation and refraction on the wave induced ring current precipitation and heating of the thermal plasmaspheric electrons, we simulate the May 1998 storm. The main findings after the simulation can be summarized as follows. First, the wave induced ring current precipitation exhibits quite a lot of fine structure and is highly organized by location of the plasmapause gradient. The strongest fluxes of about 4 × 106 (cm2 s sr)-1 are observed during the main and early recovery phases of the storm. The very interesting and probably more important finding is that in a number of cases the most intense precipitating fluxes are not connected to the most intense waves in simple manner. The characteristics of the wave power spectral density distribution over the wave normal angle are extremely crucial for the effectiveness of the ring current ion scattering. Second, comparison of the global proton precipitating patterns with the results from RAM (Kozyra et al., 1997a) reveals that although we observe a qualitative agreement between the localizations of the wave induced precipitations in the models, there is no quantitative agreement between the magnitudes of the fluxes. The quantitative differences are mainly due to a qualitative difference between the characteristics of the wave power spectral density distributions over the wave normal angle in RAM and in our model. Third, the heat fluxes to plasmaspheric electrons caused by Landau resonate energy absorption from electromagnetic ion cyclotron waves are observed in the postnoon-premidnight MLT sector and can reach the magnitude of 1011 eV/(cm2 s). The Coulomb energy degradation of

  11. Spin polarized current from multiply-coupled rings with Zeeman-split quantum dots

    SciTech Connect

    Hedin, Eric R.; Joe, Yong S.

    2014-03-21

    We investigate transmission resonances and conductance properties of multiple, serially connected, direct-contact nanoscale rings using the tight-binding model. Quantum dots (QDs) are embedded in the two arms of each ring, and Zeeman-splitting of the QD energy levels is incorporated into the system Hamiltonian. Transmission bands develop as the number of rings in series increases, with a band-gap which is sensitive to the degree of Zeeman splitting and the initial settings of the QD site energy values. The current vs. voltage characteristics of the system can be modulated between Ohmic and semiconducting as a function of the Zeeman splitting. In addition, spin-polarized current results for selected ranges of the Fermi energy.

  12. Controllable persistent spin-polarized charge current in a Rashba ring

    NASA Astrophysics Data System (ADS)

    Liang, Feng; Gao, Benling; Zhang, Jun; Gu, Yu

    2017-08-01

    We theoretically predict the appearance of a persistent charge current in a Rashba ring with a normal and a ferromagnetic lead under no external bias. This charge current is the result of the breaking of the time inversion symmetry in the original persistent pure spin current induced by the Rashba spin-orbit coupling (RSOC) in the ring due to the existence of the ferromagnetic lead. With the Keldysh Green’s function technique, we find that not only the magnitude and sign but also the spin polarization of the generated charge current is determined by the system parameters such as the magnetization direction of the ferromagnetic lead, the tunneling coefficient, the strength of the RSOC and the exchange energy of the ferromagnetic lead, which are all tunable in experiments, that is, a controllable persistent spin-polarized charge current can be obtained in such a device.

  13. Self-consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 2. Wave Induced Ring Current Precipitation and Thermal Electron Heating

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.; Liemohn, M. W.

    2007-01-01

    This paper continues presentation and discussion of the results from our new global self-consistent theoretical model of interacting ring current ions and propagating electromagnetic ion cyclotron waves [Khazanov et al., 2006]. To study the effects of electromagnetic ion cyclotron wave propagation and refraction on the wave induced ring current precipitation and heating of the thermal plasmaspheric electrons, we simulate the May 1998 storm. The main findings after a simulation can be summarized as follows. Firstly, the wave induced ring current precipitation exhibits quite a lot of fine structure, and is highly organized by location of the plasmapause gradient. The strongest fluxes of about 4 x 10(exp 6) (cm(raised dot) s(raised dot) sr(raised dot) (sup -1)) are observed during the maill and early recovery phases of the storm. The very interesting and probably more important finding is that in a number of cases the most intense precipitating fluxes are not connected to the most intense waves in simple manner. The characteristics of the wave power spectral density distribution over the wave normal angle are extremely crucial for the effectiveness of the ring current ion scattering. Secondly, comparison of the global proton precipitating patterns with the results from RAM [Kozyra et al., 1997a] reveals that although we observe a qualitative agreement between the localizations of the wave induced precipitations in the models, there is no quantitative agreement between the magnitudes of the fluxes. The quantitative differences are mainly due to a qualitative difference between the characteristics of the wave power spectral density distributions over the wave normal angle in RAM and in our model. Thirdly, the heat fluxes to plasmaspheric electrons caused by Landau resonate energy absorption from electromagnetic ion cyclotron waves are observed in the postnoon-premidnight MLT sector, and can reach the magnitude of 10(exp 11) eV/(cm(sup 2)(raised dot)s). The Coulomb

  14. Role of ULF Waves in Radiation Belt and Ring Current Dynamics

    NASA Astrophysics Data System (ADS)

    Mann, I. R.; Murphy, K. R.; Rae, I. J.; Ozeke, L.; Milling, D. K.

    2013-12-01

    Ultra-low frequency (ULF) waves in the Pc4-5 band can be excited in the magnetosphere by the solar wind. Much recent work has shown how ULF wave power is strongly correlated with solar wind speed. However, little attention has been paid the dynamics of ULF wave power penetration onto low L-shells in the inner magnetosphere. We use more than a solar cycle of ULF wave data, derived from ground-based magnetometer networks, to examine this ULF wave power penetration and its dependence on solar wind and geomagnetic activity indices. In time domain data, we show very clearly that dayside ULF wave power, spanning more than 4 orders of magnitude, follows solar wind speed variations throughout the whole solar cycle - during periods of sporadic solar maximum ICMEs, during declining phase fast solar wind streams, and at solar minimum, alike. We also show that time domain ULF wave power increases during magnetic storms activations, and significantly demonstrate that a deeper ULF wave power penetration into the inner magnetosphere occurs during larger negative excursions in Dst. We discuss potential explanations for this low-L ULF wave power penetration, including the role of plasma mass density (such as during plasmaspheric erosion), or ring current ion instabilities during near-Earth ring current penetration. Interestingly, we also show that both ULF wave power and SAMPEX MeV electron flux show a remarkable similarity in their penetration to low-L, which suggests that ULF wave power penetration may be important for understanding and explaining radiation belt dynamics. Moreover, the correlation of ULF wave power with Dst, which peaks at one day lag, suggests the ULF waves might also be important for the inward transport of ions into the ring current. Current ring current models, which exclude long period ULF wave transport, under-estimate the ring current during fast solar wind streams which is consistent with a potential role for ULF waves in ring current energisation. The

  15. Possible deviations from (V-A) charged currents: precise measurement of muon decay parameters

    SciTech Connect

    Strovink, M.

    1981-02-01

    This short review examines the experimental limits on possible deviations from (V-A) charged weak currents, as would occur at some mass scale, for example, in manifestly left-right-symmetric electro-weak theories. Both present and anticipated limits are considered, emphasizing muon-decay experiments but including other experimental input where convenient.

  16. Unconventional ring currents in an `all-metal aromatic', Al 42-

    NASA Astrophysics Data System (ADS)

    Fowler, P. W.; Havenith, R. W. A.; Steiner, E.

    2001-07-01

    The square planar anion Al 42- supports an unconventional diamagnetic ring current which originates in the σ system, has negligible contribution from the two-electron π system, and survives in pyramidal bimetallic clusters MAl 4- (M=Li, Na, Cu).

  17. Concurrent operational modes and enhanced current sensitivity in heterostructure of magnetoelectric ring and piezoelectric transformer

    NASA Astrophysics Data System (ADS)

    Zhang, Shengyao; Ming Leung, Chung; Kuang, Wei; Wing Or, Siu; Ho, S. L.

    2013-05-01

    A heterostructure possessing two concurrent operational modes: current sensing (CS) mode and current transduction (CT) mode and an enhanced current sensitivity associated with the CT mode is proposed by combining a magnetoelectric ring (MER) with a piezoelectric transformer (PET). The MER is a ring-shaped magnetoelectric laminate having an axially polarized Pb(Zr, Ti)O3 (PZT) piezoelectric ceramic ring sandwiched between two circumferentially magnetized, inter-magnetically biased Tb0.3Dy0.7Fe1.92 (Terfenol-D) short-fiber/NdFeB magnet/epoxy three-phase magnetostrictive composite rings, while the PET is a Rosen-type PZT piezoelectric ceramic transformer. The current sensitivity (SI) and magnetoelectric voltage coefficient (αV) of the heterostructure in the two operational modes are evaluated theoretically and experimentally. The CS mode provides a large SI of ˜10 mV/A over a flat frequency range of 10 Hz-40 kHz with a high resonance SI of 157 mV/A at 62 kHz. The CT mode gives a 6.4-times enhancement in resonance SI, reaching 1000 mV/A at 62 kHz, as a result of the amplified vortex magnetoelectric effect caused by the vortex magnetoelectric effect in the MER, the matching of the resonance frequencies between the MER and the PET, and the resonance voltage step-up effect in the PET.

  18. Instability of ring current protons beyond the plasmapause during injection events.

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.; White, R.; Fredricks, R. W.

    1972-01-01

    The stability of ring current protons with an injection spectrum modeled by a loss cone distribution function is examined for typical ring current parameters. It is found that a quasi-electrostatic ion loss cone mode can be excited with frequencies just below and growth rates of the order of 0.01 times the ion plasma frequency. The instability is strongest in the moderate beta about equal to 1, low-density region just outside the plasmapause; for the beta much greater than 1 auroral regions and the high-density plasmasphere the mode is nearly stable. For the same ring current parameters the electromagnetic ion cyclotron wave is almost nonconvectively unstable, with growth rates of the order of 0.1 times the ion cyclotron frequency. The combination of the two unstable modes results in a large quasi-linear diffusion coefficient throughout most of the proton velocity space. Unless it is maintained by rapid inward convection, the ring current injection anisotropy will be reduced by diffusion toward the loss cone on time scales short in comparison to the minimum precipitation lifetime.

  19. Position of the Ring Current Peak During ICME- and CIR-Driven Storms

    NASA Astrophysics Data System (ADS)

    Jahn, J.; Elliott, H. A.; Perez, J. D.; Pulkkinen, T. I.; Samara, M.; Barrows, S.

    2006-12-01

    Under appropriate solar wind driving during the main phase of a storm, the peak of the ring current (as deduced from ENA observations) can move past midnight towards early morning magnetic local times. Several mechanisms explaining this dawnward shift have been proposed, including the deformation of the convection electric field due to the shielding electric field, and the local time dependence of the plasma sheet density. We present a study of all Dst storms during the IMAGE mission (2000-2005) for which below 80 keV hydrogen ENA remote sensing ring current data are available. We expand previous investigations in several areas. In addition to all ICME-driven events we also include all CIR-driven storms. The relevant (and sufficient) solar wind driving may occur in either event type. We discuss the coupling between solar wind and magnetosphere in more detail, also considering the magnetospheric state prior to storm main phase. This will better represent the role of the plasma sheet in the control of the storm time ring current peak position. Furthermore, we include a comparison of ENA-based results with ground-based magnetometer observations of the ring current morphology for a select number of cases. This provides ground truth for studies previously based on remote- sensing ENA observations alone.

  20. The electronic structure of inorganic benzenes: valence bond and ring-current descriptions.

    PubMed

    Engelberts, Jeroen J; Havenith, Remco W A; van Lenthe, Joop H; Jenneskens, Leonardus W; Fowler, Patrick W

    2005-07-25

    Valence bond (VB) theory and ring-current maps have been used to study the electronic structure of inorganic benzene analogues X(6)H(6) (X = C (1), Si (2)), X(6) (X = N (3), P (4)), X(3)Y(3)H(6) (X,Y = B,N (5), B,P (6), Al,N (7), Al,P (8)), and B(3)Y(3)H(3) (Y = O (9), S (10)). It is shown that the homonuclear compounds possess benzene-like character, with resonance between two Kekulé-like structures and induced diatropic ring currents. Heteronuclear compounds typically show localization of the lone pairs on the electronegative atoms; Kekulé-like structures do not contribute. Of the heteronuclear compounds, only B(3)P(3)H(6) (6) has some benzene-like features with a significant contribution of two Kekulé-like structures to its VB wave function, an appreciable resonance energy, and a discernible diatropic ring current in planar geometry. However, relaxation of 6 to the optimal nonplanar chair conformation is accompanied by the onset of localization of the ring current.

  1. On the contribution of plasma sheet bubbles to the storm time ring current

    NASA Astrophysics Data System (ADS)

    Yang, Jian; Toffoletto, Frank R.; Wolf, Richard A.; Sazykin, Stanislav

    2015-09-01

    Particle injections occur frequently inside 10 Re during geomagnetic storms. They are commonly associated with bursty bulk flows or plasma sheet bubbles transported from the tail to the inner magnetosphere. Although observations and theoretical arguments have suggested that they may have an important role in storm time dynamics, this assertion has not been addressed quantitatively. In this paper, we investigate which process is dominant for the storm time ring current buildup: large-scale enhanced convection or localized bubble injections. We use the Rice Convection Model-Equilibrium (RCM-E) to model a series of idealized storm main phases. The boundary conditions at 14-15 Re on the nightside are adjusted to randomly inject bubbles to a degree roughly consistent with observed statistical properties. A test particle tracing technique is then used to identify the source of the ring current plasma. We find that the contribution of plasma sheet bubbles to the ring current energy increases from ~20% for weak storms to ~50% for moderate storms and levels off at ~61% for intense storms, while the contribution of trapped particles decreases from ~60% for weak storms to ~30% for moderate and ~21% for intense storms. The contribution of nonbubble plasma sheet flux tubes remains ~20% on average regardless of the storm intensity. Consistent with previous RCM and RCM-E simulations, our results show that the mechanisms for plasma sheet bubbles enhancing the ring current energy are (1) the deep penetration of bubbles and (2) the bulk plasma pushed ahead of bubbles. Both the bubbles and the plasma pushed ahead typically contain larger distribution functions than those in the inner magnetosphere at quiet times. An integrated effect of those individual bubble injections is the gradual enhancement of the storm time ring current. We also make two predictions testable against observations. First, fluctuations over a time scale of 5-20 min in the plasma distributions and electric field

  2. Persistent current and zero-energy Majorana modes in a p -wave disordered superconducting ring

    NASA Astrophysics Data System (ADS)

    Nava, Andrea; Giuliano, Rosa; Campagnano, Gabriele; Giuliano, Domenico

    2017-04-01

    We discuss the emergence of zero-energy Majorana modes in a disordered finite-length p -wave one-dimensional superconducting ring, pierced by a magnetic flux Φ tuned at an appropriate value Φ =Φ* . In the absence of fermion parity conservation, we evidence the emergence of the Majorana modes by looking at the discontinuities in the persistent current I [Φ ] at Φ =Φ* . By monitoring the discontinuities in I [Φ ] , we map out the region in parameter space characterized by the emergence of Majorana modes in the disordered ring.

  3. Search for hadronic b-->u decays

    NASA Astrophysics Data System (ADS)

    Albrecht, H.; Gläser, R.; Harder, G.; Krüger, A.; Nilsson, A. W.; Nippe, A.; Oest, T.; Reidenbach, M.; Schäfer, M.; Schmidt-Parzefall, W.; Schröder, H.; Schulz, H. D.; Sefkow, F.; Wurth, R.; Appuhn, R. D.; Drescher, A.; Hast, C.; Herrera, G.; Kolanoski, H.; Lange, A.; Lindner, A.; Mankel, R.; Scheck, H.; Schweda, G.; Spaan, B.; Walther, A.; Wegener, D.; Paulini, M.; Reim, K.; Volland, U.; Wegener, H.; Funk, W.; Stiewe, J.; Werner, S.; Ball, S.; Gabriel, J. C.; Geyer, C.; Hölscher, A.; Hofmann, W.; Holzer, B.; Khan, S.; Spengler, J.; Charlesworth, C. E. K.; Edwards, K. W.; Frisken, W. R.; Kapitza, H.; Krieger, P.; Kutschke, R.; Macfarlene, D. B.; McLean, K. W.; Orr, R. S.; Parsons, J. A.; Patel, P. M.; Prentice, J. D.; Seidel, S. C.; Swain, J. D.; Tsipolitis, G.; Tzamariudaki, K.; Yoon, T.-S.; Ruf, T.; Schael, S.; Schubert, K. R.; Strahl, K.; Waldi, R.; Weseler, S.; Boštjančič, B.; Kernel, G.; Križan, P.; Križnič, E.; Cronström, H. I.; Jönsson, L.; Babaev, A.; Danilo, M.; Fominykh, B.; Golutvin, A.; Gorelov, I.; Lubimov, V.; Rostovtsev, A.; Semenov, A.; Semenov, S.; Shevchenko, V.; Soloshenko, V.; Tchistilin, V.; Tichomirov, I.; Zaitsev, Yu.; Childers, R.; Darden, C. W.; Argus Collaboration

    1990-05-01

    Using the ARGUS detector at the e +e - storage ring DORIS II at DESY, we searched for b→u transitions in exclusive hadronic B meson decays. A systematic analysis of B decays into pions has been performed for decay modes with 2-7 pions in the final state. In none of the decays a positive signal was observed. The upper limits obtained on various branching ratios are consistent with the current model predictions.

  4. Current observations with a decaying cosmological constant allow for chaotic cyclic cosmology

    NASA Astrophysics Data System (ADS)

    Ellis, George F. R.; Platts, Emma; Sloan, David; Weltman, Amanda

    2016-04-01

    We use the phase plane analysis technique of Madsen and Ellis [1] to consider a universe with a true cosmological constant as well as a cosmological "constant" that is decaying. Time symmetric dynamics for the inflationary era allows eternally bouncing models to occur. Allowing for scalar field dynamic evolution, we find that if dark energy decays in the future, chaotic cyclic universes exist provided the spatial curvature is positive. This is particularly interesting in light of current observations which do not yet rule out either closed universes or possible evolution of the cosmological constant. We present only a proof of principle, with no definite claim on the physical mechanism required for the present dark energy to decay.

  5. Current observations with a decaying cosmological constant allow for chaotic cyclic cosmology

    SciTech Connect

    Ellis, George F.R.; Platts, Emma; Weltman, Amanda; Sloan, David E-mail: pltemm002@myuct.ac.za E-mail: amanda.weltman@uct.ac.za

    2016-04-01

    We use the phase plane analysis technique of Madsen and Ellis [1] to consider a universe with a true cosmological constant as well as a cosmological 'constant' that is decaying. Time symmetric dynamics for the inflationary era allows eternally bouncing models to occur. Allowing for scalar field dynamic evolution, we find that if dark energy decays in the future, chaotic cyclic universes exist provided the spatial curvature is positive. This is particularly interesting in light of current observations which do not yet rule out either closed universes or possible evolution of the cosmological constant. We present only a proof of principle, with no definite claim on the physical mechanism required for the present dark energy to decay.

  6. Effect of Ring Current Ions on Electromagnetic Ion Cyclotron Wave Dispersion Relation

    NASA Technical Reports Server (NTRS)

    Gamayunov, K. V.; Khazanov, G. V.

    2006-01-01

    Electromagnetic ion cyclotron (EMIC) waves are widely observed in the inner and outer magnetosphere, at geostationary orbit, at high latitudes along the plasmapause, and at the ionospheric altitudes. Interaction of the Ring Current (RC) ions and EMIC waves causes ion scattering into the loss cone and leads to decay of the RC, especially during the main phase of storms when the RC decay times of about one hour or less are observed. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Induced scattering of these waves by the plasmaspheric thermal ions leads to ion temperature enhancement, and forms a so-called hot zone near the plasmapause where the temperature of core plasma ions can reach tens of thousands of degrees. Relativistic electrons in the outer radiation belt also interact well with the EMIC waves, and during the main and/or recovery phases of the storms these electrons can easily be scattered into the loss cone over a time scale from several hours to a day. The plasma density distribution in the magnetosphere and the ion content play a critical role in EMIC wave generation and propagation, but the wave dispersion relation in the known RC-EMIC wave interaction models is assumed to be determined by the thermal plasma distribution only. In these models, the modification of the EMIC wave dispersion relation caused by the RC ions is not taken into account, and the RC ions are only treated as a source of free energy in order to generate EMIC waves. At the same time, the RC ions can dominate the thermal magnetospheric content in the night MLT sector at great L shells during the main and/or recovery storm phase. In this study, using our self-consistent RC-EMIC wave model [Khazanov et al., 2006], we simulate the May 1998 storm in order to quantify the global EMIC wave redistribution caused by

  7. Are Ring Current Ions Lost in Electromagnetic Ion Cyclotron Wave Dispersion Relation?

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.

    2006-01-01

    Electromagnetic ion cyclotron (EMIC) waves are widely observed in the inner and outer magnetosphere, at geostationary orbit, at high latitudes along the plasmapause, and at the ionospheric altitudes. Interaction of the Ring Current (RC) ions and EMIC waves causes ion scattering into the loss cone and leads to decay of the RC, especially during the main phase of storms when the RC decay times of about one hour or less are observed. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Induced scattering of these waves by the plasmaspheric thermal ions leads to ion temperature enhancement, and forms a so-called hot zone near the plasmapause where the temperature of core plasma ions can reach tens of thousands of degrees. Relativistic electrons in the outer radiation belt also interact well with the EMIC waves, and during the main and/or recovery phases of the storms these electrons can easily be scattered into the loss cone over a time scale from several hours to a day. The plasma density distribution in the magnetosphere and the ion content play a critical role in EMIC wave generation and propagation, but the wave dispersion relation in the known RC-EMIC wave interaction models is assumed to be determined by the thermal plasma distribution only. In these models, the modification of the EMIC wave dispersion relation caused by the RC ions is not taken into account, and the RC ions are only treated as a source of free energy in order to generate EMIC waves. At the same time, the RC ions can dominate the thermal magnetospheric content in the night MLT sector at great L shells during the main and/or recovery storm phase. In this study, using our self-consistent RC-EMIC wave model [Khazanov et al., 2006], we simulate the May 1998 storm in order to quantify the global EMIC wave redistribution caused by

  8. Are Ring Current Ions Lost in Electromagnetic Ion Cyclotron Wave Dispersion Relation?

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.

    2006-01-01

    Electromagnetic ion cyclotron (EMIC) waves are widely observed in the inner and outer magnetosphere, at geostationary orbit, at high latitudes along the plasmapause, and at the ionospheric altitudes. Interaction of the Ring Current (RC) ions and EMIC waves causes ion scattering into the loss cone and leads to decay of the RC, especially during the main phase of storms when the RC decay times of about one hour or less are observed. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Induced scattering of these waves by the plasmaspheric thermal ions leads to ion temperature enhancement, and forms a so-called hot zone near the plasmapause where the temperature of core plasma ions can reach tens of thousands of degrees. Relativistic electrons in the outer radiation belt also interact well with the EMIC waves, and during the main and/or recovery phases of the storms these electrons can easily be scattered into the loss cone over a time scale from several hours to a day. The plasma density distribution in the magnetosphere and the ion content play a critical role in EMIC wave generation and propagation, but the wave dispersion relation in the known RC-EMIC wave interaction models is assumed to be determined by the thermal plasma distribution only. In these models, the modification of the EMIC wave dispersion relation caused by the RC ions is not taken into account, and the RC ions are only treated as a source of free energy in order to generate EMIC waves. At the same time, the RC ions can dominate the thermal magnetospheric content in the night MLT sector at great L shells during the main and/or recovery storm phase. In this study, using our self-consistent RC-EMIC wave model [Khazanov et al., 2006], we simulate the May 1998 storm in order to quantify the global EMIC wave redistribution caused by

  9. Effect of Ring Current Ions on Electromagnetic Ion Cyclotron Wave Dispersion Relation

    NASA Technical Reports Server (NTRS)

    Gamayunov, K. V.; Khazanov, G. V.

    2006-01-01

    Electromagnetic ion cyclotron (EMIC) waves are widely observed in the inner and outer magnetosphere, at geostationary orbit, at high latitudes along the plasmapause, and at the ionospheric altitudes. Interaction of the Ring Current (RC) ions and EMIC waves causes ion scattering into the loss cone and leads to decay of the RC, especially during the main phase of storms when the RC decay times of about one hour or less are observed. The oblique EMIC waves damp due to Landau resonance with the thermal plasmaspheric electrons, and subsequent transport of the dissipating wave energy into the ionosphere below causes an ionosphere temperature enhancement. Induced scattering of these waves by the plasmaspheric thermal ions leads to ion temperature enhancement, and forms a so-called hot zone near the plasmapause where the temperature of core plasma ions can reach tens of thousands of degrees. Relativistic electrons in the outer radiation belt also interact well with the EMIC waves, and during the main and/or recovery phases of the storms these electrons can easily be scattered into the loss cone over a time scale from several hours to a day. The plasma density distribution in the magnetosphere and the ion content play a critical role in EMIC wave generation and propagation, but the wave dispersion relation in the known RC-EMIC wave interaction models is assumed to be determined by the thermal plasma distribution only. In these models, the modification of the EMIC wave dispersion relation caused by the RC ions is not taken into account, and the RC ions are only treated as a source of free energy in order to generate EMIC waves. At the same time, the RC ions can dominate the thermal magnetospheric content in the night MLT sector at great L shells during the main and/or recovery storm phase. In this study, using our self-consistent RC-EMIC wave model [Khazanov et al., 2006], we simulate the May 1998 storm in order to quantify the global EMIC wave redistribution caused by

  10. Aharonov-Casher oscillations of spin current through a multichannel mesoscopic ring

    NASA Astrophysics Data System (ADS)

    Shlyapin, V. V.; Mal'Shukov, A. G.

    2010-09-01

    The Aharonov-Casher (AC) oscillations of spin current through a two-dimensional ballistic ring in the presence of Rashba spin-orbit interaction and external magnetic field has been calculated using the semiclassical path-integral method. For classically chaotic trajectories the Fokker-Planck equation determining dynamics of the particle spin polarization has been derived. On the basis of this equation an analytic expression for the spin conductance has been obtained taking into account a finite width of the ring arms carrying large number of conducting channels. It was shown that the finite width results in a broadening and damping of spin-current AC oscillations. We found that an external magnetic field leads to appearance of new nondiagonal components of the spin conductance, allowing thus by applying a rather weak magnetic field to change a direction of the transmitted spin-current polarization.

  11. Highly Efficient Spin-Current Operation in a Cu Nano-Ring.

    PubMed

    Murphy, Benedict A; Vick, Andrew J; Samiepour, Marjan; Hirohata, Atsufumi

    2016-11-21

    An all-metal lateral spin-valve structure has been fabricated with a medial Copper nano-ring to split the diffusive spin-current path. We have demonstrated significant modulation of the non-local signal by the application of a magnetic field gradient across the nano-ring, which is up to 30% more efficient than the conventional Hanle configuration at room temperature. This was achieved by passing a dc current through a current-carrying bar to provide a locally induced Ampère field. We have shown that in this manner a lateral spin-valve gains an additional functionality in the form of three-terminal gate operation for future spintronic logic.

  12. Energy transfer, orbital angular momentum, and discrete current in a double-ring fiber array

    SciTech Connect

    Alexeyev, C. N.; Volyar, A. V.; Yavorsky, M. A.

    2011-12-15

    We study energy transfer and orbital angular momentum of supermodes in a double-ring array of evanescently coupled monomode optical fibers. The structure of supermodes and the spectra of their propagation constants are obtained. The geometrical parameters of the array, at which the energy is mostly confined within the layers, are determined. The developed method for finding the supermodes of concentric arrays is generalized for the case of multiring arrays. The orbital angular momentum carried by a supermode of a double-ring array is calculated. The discrete lattice current is introduced. It is shown that the sum of discrete currents over the array is a conserved quantity. The connection of the total discrete current with orbital angular momentum of discrete optical vortices is made.

  13. Highly Efficient Spin-Current Operation in a Cu Nano-Ring

    PubMed Central

    Murphy, Benedict A.; Vick, Andrew J.; Samiepour, Marjan; Hirohata, Atsufumi

    2016-01-01

    An all-metal lateral spin-valve structure has been fabricated with a medial Copper nano-ring to split the diffusive spin-current path. We have demonstrated significant modulation of the non-local signal by the application of a magnetic field gradient across the nano-ring, which is up to 30% more efficient than the conventional Hanle configuration at room temperature. This was achieved by passing a dc current through a current-carrying bar to provide a locally induced Ampère field. We have shown that in this manner a lateral spin-valve gains an additional functionality in the form of three-terminal gate operation for future spintronic logic. PMID:27869213

  14. Writing with ring currents: selectively hydrogenated polycyclic aromatics as finite models of graphene and graphane.

    PubMed

    Fowler, Patrick W; Gibson, Christopher M; Bean, David E

    2014-03-08

    Alternating partial hydrogenation of the interior region of a polycyclic aromatic hydrocarbon gives a finite model system representing systems on the pathway from graphene to the graphane modification of the graphene sheet. Calculations at the DFT and coupled Hartree-Fock levels confirm that sp(2) cycles of bare carbon centres isolated by selective hydrogenation retain the essentially planar geometry and electron delocalization of the annulene that they mimic. Delocalization is diagnosed by the presence of ring currents, as detected by ipsocentric calculation and visualization of the current density induced in the π system by a perpendicular external magnetic field. These induced 'ring' currents have essentially the same sense, strength and orbital origin as in the free hydrocarbon. Subjected to the important experimental proviso of the need for atomic-scale control of hydrogenation, this finding predicts the possibility of writing single, multiple and concentric diatropic and/or paratropic ring currents on the graphene/graphane sheet. The implication is that pathways for free flow of ballistic current can be modelled in the same way.

  15. Simulations of phase space distributions of storm time proton ring current

    NASA Technical Reports Server (NTRS)

    Chen, Margaret W.; Lyons, Larry R.; Schulz, Michael

    1994-01-01

    We use results of guiding-center simulations of ion transport to map phase space densities of the stormtime proton ring current. We model a storm as a sequence of substorm-associated enhancements in the convection electric field. Our pre-storm phase space distribution is an analytical solution to a steady-state transport model in which quiet-time radial diffusion balances charge exchange. This pre-storm phase space spectra at L approximately 2 to 4 reproduce many of the features found in observed quiet-time spectra. Using results from simulations of ion transport during model storms having main phases of 3, 6, and 12 hr, we map phase space distributions from the pre-storm distribution in accordance with Liouville's theorem. We find stormtime enhancements in the phase space densities at energies E approximately 30-160 keV for L approximately 2.5 to 4. These enhancements agree well with the observed stormtime ring current. For storms with shorter main phases (approximately 3 hr), the enhancements are caused mainly by the trapping of ions injected from open night side trajectories, and diffusive transport of higher-energy (greater than or approximately 160 keV) ions contributes little to the stormtime ring current. However, the stormtime ring current is augmented also by the diffusive transport of higher-energy ions (E greater than or approximately 160 keV) durinng stroms having longer main phases (greater than or approximately 6 hr). In order to account for the increase in Dst associated with the formation of the stormtime ring current, we estimate the enhancement in particle-energy content that results from stormtime ion transport in the equatorial magnetosphere. We find that transport alone cannot account for the entire increase in absolute value of Dst typical of a major storm. However, we can account for the entire increase in absolute value of Dst by realistically increasing the stormtime outer boundary value of the phase space density relative to the quiet

  16. Simulations of phase space distributions of storm time proton ring current

    NASA Technical Reports Server (NTRS)

    Chen, Margaret W.; Lyons, Larry R.; Schulz, Michael

    1994-01-01

    We use results of guiding-center simulations of ion transport to map phase space densities of the stormtime proton ring current. We model a storm as a sequence of substorm-associated enhancements in the convection electric field. Our pre-storm phase space distribution is an analytical solution to a steady-state transport model in which quiet-time radial diffusion balances charge exchange. This pre-storm phase space spectra at L approximately 2 to 4 reproduce many of the features found in observed quiet-time spectra. Using results from simulations of ion transport during model storms having main phases of 3, 6, and 12 hr, we map phase space distributions from the pre-storm distribution in accordance with Liouville's theorem. We find stormtime enhancements in the phase space densities at energies E approximately 30-160 keV for L approximately 2.5 to 4. These enhancements agree well with the observed stormtime ring current. For storms with shorter main phases (approximately 3 hr), the enhancements are caused mainly by the trapping of ions injected from open night side trajectories, and diffusive transport of higher-energy (greater than or approximately 160 keV) ions contributes little to the stormtime ring current. However, the stormtime ring current is augmented also by the diffusive transport of higher-energy ions (E greater than or approximately 160 keV) durinng stroms having longer main phases (greater than or approximately 6 hr). In order to account for the increase in Dst associated with the formation of the stormtime ring current, we estimate the enhancement in particle-energy content that results from stormtime ion transport in the equatorial magnetosphere. We find that transport alone cannot account for the entire increase in absolute value of Dst typical of a major storm. However, we can account for the entire increase in absolute value of Dst by realistically increasing the stormtime outer boundary value of the phase space density relative to the quiet

  17. Analysis of the magnetically induced current density of molecules consisting of annelated aromatic and antiaromatic hydrocarbon rings.

    PubMed

    Sundholm, Dage; Berger, Raphael J F; Fliegl, Heike

    2016-06-21

    Magnetically induced current susceptibilities and current pathways have been calculated for molecules consisting of two pentalene groups annelated with a benzene (1) or naphthalene (2) moiety. Current strength susceptibilities have been obtained by numerically integrating separately the diatropic and paratropic contributions to the current flow passing planes through chosen bonds of the molecules. The current density calculations provide novel and unambiguous current pathways for the unusual molecules with annelated aromatic and antiaromatic hydrocarbon moieties. The calculations show that the benzene and naphthalene moieties annelated with two pentalene units as in molecules 1 and 2, respectively, are unexpectedly antiaromatic sustaining only a local paratropic ring current around the ring, whereas a weak diatropic current flows around the C-H moiety of the benzene ring. For 1 and 2, the individual five-membered rings of the pentalenes are antiaromatic and a slightly weaker semilocal paratropic current flows around the two pentalene rings. Molecules 1 and 2 do not sustain any net global ring current. The naphthalene moiety of the molecule consisting of a naphthalene annelated with two pentalene units (3) does not sustain any strong ring current that is typical for naphthalene. Instead, half of the diatropic current passing the naphthalene moiety forms a zig-zag pattern along the C-C bonds of the naphthalene moiety that are not shared with the pentalene moieties and one third of the current continues around the whole molecule partially cancelling the very strong paratropic semilocal ring current of the pentalenes. For molecule 3, the pentalene moieties and the individual five-membered rings of the pentalenes are more antiaromatic than for 1 and 2. The calculated current patterns elucidate why the compounds with formally [4n + 2] π-electrons have unusual aromatic properties violating the Hückel π-electron count rule. The current density calculations also provide

  18. State-of-Art Empirical Modeling of Ring Current Plasma Pressure

    NASA Astrophysics Data System (ADS)

    Yue, C.; Ma, Q.; Wang, C. P.; Bortnik, J.; Thorne, R. M.

    2015-12-01

    The plasma pressure in the inner magnetosphere plays a key role in plasma dynamics by changing magnetic field configurations and generating the ring current. In this study, we present our preliminary results of empirically constructing 2D equatorial ring current pressure and pressure anisotropy spatial distributions controlled by Dst based on measurements from two particle instruments (HOPE and RBSPICE) onboard Van Allen Probes. We first obtain the equatorial plasma perpendicular and parallel pressures for different species including H+, He+, O+ and e- from 20 eV to ~1 MeV, and investigate their relative contributions to the total plasma pressure and pressure anisotropy. We then establish empirical equatorial pressure models within ~ 6 RE using a state-of-art machine learning technique, Support Vector Regression Machine (SVRM). The pressure models predict equatorial perpendicular and parallel plasma thermal pressures (for each species and for total pressures) and pressure anisotropy at any given r, MLT, Bz/Br (equivalent Z distance), and Dst within applicable ranges. We are currently validating our model predictions and investigating how the ring current pressure distributions and the associated pressure gradients vary with Dst index.

  19. Control of Josephson current by Aharonov-Casher phase in a Rashba ring

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Borunda, M. F.; Liu, Xiong-Jun; Sinova, Jairo

    2009-11-01

    We study the interference effect induced by the Aharonov-Casher phase on the Josephson current through a semiconducting ring attached to superconducting leads. Using a one-dimensional model that incorporates spin-orbit coupling in the semiconducting ring, we calculate the Andreev levels analytically and numerically, and predict oscillations of the Josephson current due to the AC phase. This result is valid from the point-contact limit to the long channel-length case, as defined by the ratio of the junction length and the BCS healing length. We show in the long channel-length limit that the impurity scattering has no effect on the oscillation of the Josephson current, in contrast to the case of conductivity oscillations in a spin-orbit-coupled ring system attached to normal leads where impurity scattering reduces the amplitude of oscillations. Our results suggest a scheme to measure the AC phase with, in principle, higher sensitivity. In addition, this effect allows for control of the Josephson current through the gate-voltage-tuned AC phase.

  20. The Evolution of Ring Current Energy Density and Energy Content during Geomagnetic Storms Based on Van Allen Probes Measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Baker, D. N.; Claudepierre, S. G.; Fennell, J. F.; Blake, J. B.; Larsen, B.; Skoug, R. M.; Funsten, H. O.; Freidel, R. H. W.; Reeves, G. D.; Spence, H. E.; Mitchell, D. G.; Lanzerotti, L. J.; Rodriguez, J. V.

    2015-12-01

    Enabled by the comprehensive measurements from the MagEIS, HOPE, and RBSPICE instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of particles with different energies and species to the ring current energy density and their dependence on the geomagnetic storms and storm phases are quantified. During the main phases of moderate storms (with minimum Dst between -50 nT and -100 nT), ions of energies < 50 keV and electrons of energies of <35 keV contribute more significantly to the ring current energy than those of higher energies. During the recovery phase and quiet times higher energy protons dominate the ring current energy content. For the March 29, 2013 moderate storm, the contribution from O+ is ~25% of the ring current energy content during the main phase, and the majority of that comes from < 50 keV O+. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions and low energy O+ plays an important role in ring current dynamics. The contribution of electrons to the ring current energy content is up to ~7% during this moderate storm and the magnetic local time dependence of electron energy density is also investigated. However, the ring current energy partitions for different species and energy ranges are very different during the great storm of 17 March 2015 (with minimum Dst<-210 nT).

  1. The storm time ring current dynamics and response to CMEs and CIRs using Van Allen Probes observations and CIMI simulations

    NASA Astrophysics Data System (ADS)

    Mouikis, Christopher; Bingham, Samuel; Kistler, Lynn; Spence, Harlan; Gkioulidou, Matina

    2017-04-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), and co-rotating interaction regions (CIR's). Using Van Allen Probes observations, we develop an empirical ring current model of the ring current pressure, the pressure anisotropy and the current density development during the storm phases for both types of storm drivers and for all MLTs inside L 6. Delineating the differences in the ring current development between these two drivers will aid our understanding of the ring current dynamics. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L 2 and their pressure compares to the local magnetic field pressure as deep as L 3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current. However, the largest difference between the CME and CIR ring current responses during the storm main and early recovery phases is caused by how the 15 - 60 keV O+ responds to these drivers. This empirical model is compared to the results of CIMI simulations of a CMEs and a CIRs where the model input is comprised of the superposed epoch solar wind conditions of the storms that comprise the empirical model. Different inner magnetosphere boundary conditions are tested in order to match the empirical model results. Comparing the model and simulation results improves our understanding of the ring current dynamics as part of the highly coupled inner magnetosphere system. In addition, within the framework of this empirical model, the prediction of the EMIC wave generation linear theory is tested using the observed plasma parameters and comparing with the observations of

  2. Study of Interactions Between ULF Waves and Ring Current Heavy (He+ and O+) Ions

    NASA Astrophysics Data System (ADS)

    Kim, H.; Lanzerotti, L. J.; Gerrard, A. J.; Manweiler, J. W.; Soto-chavez, A. R.; Cohen, R. J.; Bortnik, J.; Kim, E. H.; Johnson, J.

    2015-12-01

    We report the spatiotemporal structure of interactions between ULF waves and ring current heavy (He+ and O+) ions using a suite of Van Allen Probes instruments. It is well known that although heavy ions constitute only a fraction of magnetospheric particles in most conditions (especially during quiet times), their role in wave generation and propagation is significant. The relative contribution of each heavy ion species to ULF wave generation and propagation still needs to be further investigated to understand ring current heavy ion dynamics. We present data from the ion composition (Radiation Belt Storm Probes Ion Composition Experiment; RBSPICE) and field (Electric and Magnetic Field Instrument Suite and Integrated Science; EMFISIS) instruments onboard Van Allen Probes to examine ULF wave activity in the presence of heavy ions and the scattering of heavy ions. Ground-based data near spacecraft conjunction sites are also used to investigate wave propagation associated with wave-particle interactions.

  3. Reversing the persistent current of particles in a driven optical ring lattice

    NASA Astrophysics Data System (ADS)

    Morales-Molina, L.; Arévalo, E.

    2015-10-01

    We study the dynamics of persistent bosonic currents in closed-loop atom circuits in the form of ring lattices and under the action of time periodic driving. The closed-loop atom circuits are described by a Bose-Hubbard model in the presence of a Peierls phase and with periodic boundary conditions. We find that the motion of matter waves can be controlled with the help of an external driving only applied in one site of the ring lattice. For tuned values of the interaction strength between particles, we show that there exists a frequency range of the external driving where not only suppression but also reversion of the persistent bosonic currents is achieved. Applications of our results are discussed.

  4. Analytic Aharonov-Bohm ringsCurrents readout from Zeeman spectrum

    NASA Astrophysics Data System (ADS)

    Xiao, Mufei; Reyes-Serrato, Armando

    2016-06-01

    This paper reports the work on the development and analysis of a model for quantum rings in which persistent currents are induced by Aharonov-Bohm (AB) or other similar effects. The model is based on a centric and annual potential profile. The time-independent Schrödinger equation including an external magnetic field and an AB flux is analytically solved. The outputs, namely energy dispersion and wavefunctions, are analyzed in detail. It is shown that the rotation quantum number m is limited to small numbers, especially in weak confinement, and a conceptual proposal is put forward for acquiring the flux and eventually estimating the persistent currents in a Zeeman spectroscopy. The wavefunctions and electron distributions are numerically studied and compared to one-dimensional (1D) quantum well. It is predicated that the model and its solutions, eigen energy structure and analytic wavefunctions, would be a powerful tool for studying various electric and optical properties of quantum rings.

  5. Electrostatic instability of ring current protons beyond the plasmapause during injection events

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.; Fredricks, R. W.; White, R.

    1972-01-01

    The stability of ring current protons with an injection spectrum modeled by an m = 2 mirror distribution function was examined for typical ring current parameters. It was found that the high frequency loss cone mode can be excited at wave numbers K lambda sub Di about = to 0.1 to 0.5, at frequencies omega about = to (0.2 to 0.6) omega sub pi and with growth rates up to gamma/omega about = to 0.03. These waves interact with the main body of the proton distribution and propagate nearly perpendicular to the local magnetic field. Cold particle partial densities tend to reduce the growth rate so that the waves are quenched at or near to the plasmapause boundary. Wave e-folding lengths are comparable to 0.1 R sub e, compared to the value of about 4 R sub e found for ion cyclotron waves at the same plasma conditions.

  6. Variation of the ion composition in the ring current during magnetic storms: Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Luo, Hao; Du, Aimin; Ge, Yasong; Cao, Xin; Zhang, Ying; Wang, Yuan

    2015-04-01

    It has been reported that the energy density of the oxygen ions in the ring current region will show more enhancements than protons during magnetic storms. Knowing how the ion composition changes during a magnetic storm is important for understanding the dynamic processes in the inner magnetosphere. By using ion flux data from HOPE and RBSPICE instruments on board the Van Allen probes, we study the energy density variation of both protons and oxygen ions during fifteen strong magnetic storms (minimum Dst < -80 nT) happened during year 2013 to 2014. Results provide important details about the ion composition at different storm stages and different magnetic local times. Results also give important indications about the ion acceleration in the inner magnetosphere and the source of the ring current ions during the magnetic storms.

  7. The role of ring current O(+) in the formation of stable auroral red arcs

    NASA Technical Reports Server (NTRS)

    Kozyra, J. U.; Shelley, E. G.; Comfort, R. H.; Brace, L. H.; Cravens, T. E.

    1987-01-01

    Observations of thermal and energetic ion populations by the Dynamics Explorer 1 satellite in the magnetospheric energy source region as well as nearly simultaneous Langmuir probe measurements of enhanced electron temperatures by Dynamics Explorer 2 within the stable auroral red (SAR) arc at F region heights are used to examine the role of heavy ions in the formation of SAR arcs. It is found that sufficient energy is transferred to the electron gas at high altitudes via Coulomb collisions between the observed ring current ions and thermal electrons to support the enhanced F region electron temperatures measured on these field lines. The latitudinal variation in the electron heating rates calculated using observed ion populations is consistent with the observed variation in electron temperature across the SAR arc. In all cases, ring current O(+) is the major source of energy for the SAR arcs.

  8. Modes of response of the ring current and radiation belts to interplanetary drivers

    NASA Astrophysics Data System (ADS)

    Vassiliadis, D.; Shao, X.; Liemohn, M. W.; Tornquist, M.; Koepke, M. E.

    2012-12-01

    It is often mentioned that the dynamic regimes of magnetic storms are difficult to categorize, with each storm being a distinct response to solar wind driving of the magnetosphere. We report on the ring current response to interplanetary drivers and compare with the known modes of response of the energetic electron flux. The Hot Electron and Ion Drift Integrator (HEIDI) model is used to reproduce 20 storms driven by high-speed streams (HSS) and 20 storms driven by interplanetary coronal mass ejections (ICMEs). Observations of energetic electrons at 2 MeV during those storms are available from the SAMPEX and POLAR missions. While the ring current is driven by slowly-varying convective electric fields in the tail, the energetic electrons of the radiation belts respond to faster drivers such as impulses and waves. We use principal component analysis and filter techniques to compare the ion phase-space density and energetic electron flux dynamics. We find that the modes of response (P0, P1, and V1) of the electron flux are related to spatial and temporal modes of the ring current. The V1 mode corresponds to the intensification of the ring current during the main phase, and the P0 and P1 peak fluxes correspond to ion dynamic effects below and above the plasmapause respectively. The mechanisms present in HEIDI are ion energization (via wave-particle interaction) and loss (via wave-particle interactions, charge exchange, and Coulomb collisions). Finally the ICME-driven storms have spatiotemporal features related to all three electron-flux peaks while most HSS-driven storms display only two modes (P1 and V1) above the plasmapause.

  9. Impact of Near-Earth Plasma Sheet Dynamics on the Ring Current Composition

    NASA Astrophysics Data System (ADS)

    Kistler, L. M.; Mouikis, C.; Menz, A.; Spence, H. E.; Mitchell, D. G.; Gkioulidou, M.; Lanzerotti, L. J.; Skoug, R. M.; Larsen, B.; Claudepierre, S. G.; Fennell, J. F.; Blake, J. B.

    2014-12-01

    How the dynamics in the near-earth plasma sheet affects the heavy ion content, and therefore the ion pressure, of the ring current in Earth's magnetosphere is an outstanding question. Substorms accelerate plasma in the near-earth region and drive outflow from the aurora, and both these processes can preferentially enhance the population of heavy ions in this region. These heavy ions are then driven into the inner magnetosphere during storms. Thus understanding how the composition of the ring current changes requires simultaneous observations in the near-earth plasma sheet and in the inner magnetosphere. We use data from the CODIF instrument on Cluster and HOPE, RBSPICE, and MagEIS instruments on the Van Allen Probes to study the acceleration and transport of ions from the plasma sheet into the ring current. During the main phase of a geomagnetic storm on Aug 4-6, 2013, the Cluster spacecraft were moving inbound in the midnight central plasma sheet, while the apogees of the two Van Allen Probes were located on the duskside. The Cluster spacecraft measure the composition and spectral changes in the plasma sheet, while the Van Allen Probes measure the ions that reach the inner magnetosphere. A strong increase in 1-40 keV O+ was observed at the Cluster location during the storm main phase, and the Van Allen Probes observed both H+ and O+ being driven deep into the inner magnetosphere. By comparing the variations in phase space density (PSD) vs. magnetic moment at the Cluster and the Van Allen Probes locations, we examine how the composition changes non-adiabatically in the near-earth plasma sheet, and how those changes are propagated into the inner magnetosphere, populating the hto ion ring current.

  10. Effect of flavor-changing neutral currents in the leptonic asymmetry in Bd decays

    NASA Astrophysics Data System (ADS)

    Branco, G. C.; Parada, P. A.; Morozumi, T.; Rebelo, M. N.

    1993-06-01

    We evaluate the charge asymmetry in equal sign dileptons arising from the decay of a Bd0-Bd0 pair, in the presence of Z-mediated flavor-changing neutral currents. We compare our predictions with those of the standard model and the superweak model. Work supported by the Deprtment of Energy, contract DEAC03-76SF00515 and by a fellowship from OTAN (NATO).

  11. Inner Magnetosphere Modeling at the CCMC: Ring Current, Radiation Belt and Magnetic Field Mapping

    NASA Astrophysics Data System (ADS)

    Rastaetter, L.; Mendoza, A. M.; Chulaki, A.; Kuznetsova, M. M.; Zheng, Y.

    2013-12-01

    Modeling of the inner magnetosphere has entered center stage with the launch of the Van Allen Probes (RBSP) in 2012. The Community Coordinated Modeling Center (CCMC) has drastically improved its offerings of inner magnetosphere models that cover energetic particles in the Earth's ring current and radiation belts. Models added to the CCMC include the stand-alone Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model by M.C. Fok, the Rice Convection Model (RCM) by R. Wolf and S. Sazykin and numerous versions of the Tsyganenko magnetic field model (T89, T96, T01quiet, TS05). These models join the LANL* model by Y. Yu hat was offered for instant run earlier in the year. In addition to these stand-alone models, the Comprehensive Ring Current Model (CRCM) by M.C. Fok and N. Buzulukova joined as a component of the Space Weather Modeling Framework (SWMF) in the magnetosphere model run-on-request category. We present modeling results of the ring current and radiation belt models and demonstrate tracking of satellites such as RBSP. Calculations using the magnetic field models include mappings to the magnetic equator or to minimum-B positions and the determination of foot points in the ionosphere.

  12. Energetic neutral atom image of a storm-time ring current

    NASA Technical Reports Server (NTRS)

    Roelof, Edmond C.

    1987-01-01

    Energetic neutral atom (ENA) images of a storm-time ring current produced from direct measurements and model simulations are presented and analyzed. An ENA image of the storm-time ring current was obtained with the Medium Energy Particles Instrument (MEPI) mounted on ISEE 1 on September 29, 1978, and a zero-order model of the ring current ion was employed to simulate the ENA image. The simulated instrument response is compared with actual ENA measurements. It is observed that the spatial distribution of singly charged ions detected from the ENA images displays equatorial midnight/noon asymmetry in differential ion intensity with a midnight/noon ratio of greater than or equal to 20:1; peak ion fluxs, H(+) and O(+), in the midnight sector are greater than 10 to the 6th/(sq cm s sr keV); and ENA fluxes from the brighter areas of the image exceed greater than 1000/(sq cm s sr keV). It is noted that the ENA image from MEPI data correlates with the morphology of the simulated response of MEPI calculated from the model.

  13. Ion transport and loss in the earth's quiet ring current. I - Data and standard model

    NASA Technical Reports Server (NTRS)

    Sheldon, R. B.; Hamilton, D. C.

    1993-01-01

    A study of the transport and loss of ions in the earth's quiet time ring current, in which the standard radial diffusion model developed for the high-energy radiation belt particles is compared with the measurements of the lower-energy ring current ions, is presented. The data set provides ionic composition information in an energy range that includes the bulk of the ring current energy density, 1-300 keV/e. Protons are found to dominate the quiet time energy density at all altitudes, peaking near L of about 4 at 60 keV/cu cm, with much smaller contributions from O(+) (1-10 percent), He(+) (1-5 percent), and He(2+) (less than 1 percent). A minimization procedure is used to fit the amplitudes of the standard electric radial diffusion coefficient, yielding 5.8 x 10 exp -11 R(E-squared)/s. Fluctuation ionospheric electric fields are suggested as the source of the additional diffusion detected.

  14. Improved Treatment of Wave-Particle Interaction in a Ring-Current Model

    NASA Astrophysics Data System (ADS)

    Jeffery, C. A.; Delzanno, G. L.; Jordanova, V.; Yu, Y.

    2016-12-01

    Simulation of radiation belt electron dynamics during geomagnetic storms requires detailed temporal knowledge of global wave distributions. However, in-situ observations of waves are confined to a limited range of L-shell and magnetic local times, while global climatologies of wave amplitudes, constructed from the statistics of many years of observations, may not well represent any given event. In principle, ring current simulations that predict anisotropic electron distributions via a kinetic model contain knowledge of the unstable wave-particle interactions that generate Chorus waves. The details of these instabilities is, however, unresolved at the spatial (tenths of L-shells) and temporal (tenths of minutes) scales of a typical large-scale ring current code. We present a preliminary attempt to couple in a more self-consistent way inner magnetospheric micro- and macro-scale interactions via the selective spatial coupling of a kinetic ring current model (RAM) with a very high resolution Particle-In-Cell (PIC) code. In our approach, anisotropic electron distributions predicted by RAM at a few select locations are used to seed the PIC code which, in turn, predicts the resulting Chorus wave distributions that are fed back into RAM.

  15. Experimental and theoretical investigations into the paratropic ring current of a porphyrin sheet.

    PubMed

    Nakamura, Yasuyuki; Aratani, Naoki; Osuka, Atsuhiro

    2007-07-02

    Anomalous induced magnetic effects were observed in a directly fused square-planar porphyrin sheet 1, in that the protons above the center of the tetraporphyrin core were characteristically shifted downfield in the 1H NMR spectrum. These observations suggest a rare paratropic ring-current effect around the planar cyclooctatetraene (COT) core of 1. To examine the spatial distribution of the induced magnetic effect, face-to-face dimeric complexes of porphyrin sheet 1 with bipyridyl-type guest molecules (G1-G3) were prepared, which provided complexation-induced shifts (CISs) of the guest molecules as a neat experimental guide to the distance dependence of the induced magnetic effects in 1. Nucleus-independent chemical shift (NICS) values of 1 were calculated by varying the distance of the probe from the plane of 1. Whereas a simple bell-type profile was estimated for the complex (1)2-(G1)4, the distance profiles of the CIS became increasingly flat for (1)2-(G2)4 and (1)2-(G3)4. Finally, we investigated the paratropic ring-current effect just above the COT core of the complex 1-(G4)2, which agrees well with the theoretically estimated distance-dependent induced magnetic effect. Consequently, both experimental and theoretical studies on the complexes of porphyrin sheets with guest molecules revealed for the first time a unique distance dependence of the paratropic ring current.

  16. Analysis of the contributions of ring current and electric field effects to the chemical shifts of RNA bases.

    PubMed

    Sahakyan, Aleksandr B; Vendruscolo, Michele

    2013-02-21

    Ring current and electric field effects can considerably influence NMR chemical shifts in biomolecules. Understanding such effects is particularly important for the development of accurate mappings between chemical shifts and the structures of nucleic acids. In this work, we first analyzed the Pople and the Haigh-Mallion models in terms of their ability to describe nitrogen base conjugated ring effects. We then created a database (DiBaseRNA) of three-dimensional arrangements of RNA base pairs from X-ray structures, calculated the corresponding chemical shifts via a hybrid density functional theory approach and used the results to parametrize the ring current and electric field effects in RNA bases. Next, we studied the coupling of the electric field and ring current effects for different inter-ring arrangements found in RNA bases using linear model fitting, with joint electric field and ring current, as well as only electric field and only ring current approximations. Taken together, our results provide a characterization of the interdependence of ring current and electric field geometric factors, which is shown to be especially important for the chemical shifts of non-hydrogen atoms in RNA bases.

  17. Universal cumulants of the current in diffusive systems on a ring

    NASA Astrophysics Data System (ADS)

    Appert-Rolland, C.; Derrida, B.; Lecomte, V.; van Wijland, F.

    2008-08-01

    We calculate exactly the first cumulants of the integrated current and of the activity (which is the total number of changes of configurations) of the symmetric simple exclusion process on a ring with periodic boundary conditions. Our results indicate that for large system sizes the large deviation functions of the current and of the activity take a universal scaling form, with the same scaling function for both quantities. This scaling function can be understood either by an analysis of Bethe ansatz equations or in terms of a theory based on fluctuating hydrodynamics or on the macroscopic fluctuation theory of Bertini, De Sole, Gabrielli, Jona-Lasinio, and Landim.

  18. Universal cumulants of the current in diffusive systems on a ring.

    PubMed

    Appert-Rolland, C; Derrida, B; Lecomte, V; van Wijland, F

    2008-08-01

    We calculate exactly the first cumulants of the integrated current and of the activity (which is the total number of changes of configurations) of the symmetric simple exclusion process on a ring with periodic boundary conditions. Our results indicate that for large system sizes the large deviation functions of the current and of the activity take a universal scaling form, with the same scaling function for both quantities. This scaling function can be understood either by an analysis of Bethe ansatz equations or in terms of a theory based on fluctuating hydrodynamics or on the macroscopic fluctuation theory of Bertini, De Sole, Gabrielli, Jona-Lasinio, and Landim.

  19. Method of determination of the mass composition of ring current ions

    NASA Technical Reports Server (NTRS)

    Temnyy, V. V.; Gott, Y. V.; Usikov, Y. I.

    1980-01-01

    A method for individual registration of protons, and helium and oxygen ions, with energies E for a charge on the order of 100 kev/q in the ring currents of the Earth's magnetosphere was examined. The method is based on the various specific losses in energy by these ions in matter. The ion current, selected according to E/q, is passed through a solid target, after which identification of the masses is carried out, based on the energy losses in the possibly to reliably divide the flows of protons, and helium and oxygen ions.

  20. Procaine alters fast excitatory postsynaptic current decay in amphibian sympathetic ganglia.

    PubMed Central

    Connor, E. A.; Parsons, R. L.

    1983-01-01

    1--The effects of procaine (25-200 microM) on the fast excitatory postsynaptic currents (e.p.s.cs) of bullfrog sympathetic ganglion B cells were studied with a two-microelectrode voltage clamp system. 2--Procaine decreased peak e.p.s.c. size with no measurable decrease in quantal content. 3--The peak e.p.s.c.-voltage relationship was linear in control cells, but showed a marked nonlinearity in cells treated with procaine so that peak e.p.s.c. size decreased progressively at hyperpolarized values of membrane potential. The e.p.s.c. reversal potential was not altered in procaine. 4--Although the e.p.s.c. decay time course was well described by a single exponential in control cells, the decay phase often became complex in the presence of procaine. The decay phase consisted of two components in the presence of procaine which became more obvious with increasing concentration and membrane hyperpolarization. 5--In control cells, the e.p.s.c. time constant of decay increased with membrane hyperpolarization. In the presence of procaine, the first time constant of decay, tauf, increased with hyperpolarization up to -40mV, but then decreased with hyperpolarization between -40 and -100mV. 6--We conclude that procaine has two sites of action at postganglionic sympathetic neurones: (1) it reduces the number of activatable receptor-channel complexes and (2) procaine blocks open synaptic channels. Blockade of open channels became more important with hyperpolarization. PMID:6600952

  1. Writing with ring currents: selectively hydrogenated polycyclic aromatics as finite models of graphene and graphane

    PubMed Central

    Fowler, Patrick W.; Gibson, Christopher M.; Bean, David E.

    2014-01-01

    Alternating partial hydrogenation of the interior region of a polycyclic aromatic hydrocarbon gives a finite model system representing systems on the pathway from graphene to the graphane modification of the graphene sheet. Calculations at the DFT and coupled Hartree–Fock levels confirm that sp2 cycles of bare carbon centres isolated by selective hydrogenation retain the essentially planar geometry and electron delocalization of the annulene that they mimic. Delocalization is diagnosed by the presence of ring currents, as detected by ipsocentric calculation and visualization of the current density induced in the π system by a perpendicular external magnetic field. These induced ‘ring’ currents have essentially the same sense, strength and orbital origin as in the free hydrocarbon. Subjected to the important experimental proviso of the need for atomic-scale control of hydrogenation, this finding predicts the possibility of writing single, multiple and concentric diatropic and/or paratropic ring currents on the graphene/graphane sheet. The implication is that pathways for free flow of ballistic current can be modelled in the same way. PMID:24611026

  2. Coordinated Coverage of the Ring Current, Cusp and Adjacent FACs with Cluster and Swarm

    NASA Astrophysics Data System (ADS)

    Xiong, C.; Dunlop, M. W.; Bogdanova, Y.; Yang, J.; Yang, Y.; Shen, C.; Luhr, H.; Olsen, N.; Zhang, Q. H.; Ritter, P.; Kauristie, K.; Masson, A.; Haagmans, R.

    2014-12-01

    We explore the capability of Swarm-Cluster coordination for probing the behavior of the ring current (RC), field aligned currents (FAC) and cusp currents at medium and low orbits. The RC and connecting R2 FACs influence the geomagnetic field at low Earth orbit (LEO) and are sampled in situ by the four Cluster spacecraft every perigee pass. Coordination of the configuration of the three Swarm spacecraft with the constellation of the four Cluster spacecraft has been planned through joint operations; providing a set of distributed, multi-point measurements covering this region. A particularly close coordination of all spacecraft has been achieved during the start of the Swarm operations. We show preliminary study of the morphology and influence of the ring current from the in-situ RC and associated FACs determined directly from the 4-spacecraft Cluster perigee observations. We report here preliminary results of joint science targets, including coordinated cusp encounters; the comparative significance of the connecting R2 FACs, and the use and application of new analysis techniques derived from the calculation of curl B and magnetic gradients to compare estimates of the current distributions. For context, we will report on the coordination of Champ and Cluster data to interpret and resolve the R1 and R2 FACs using Champ derived models of the associated auroral boundaries.

  3. Search for a Fourth Generation Charge -1/3 Quark via Flavor Changing Neutral Current Decay

    NASA Astrophysics Data System (ADS)

    Abachi, S.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adam, I.; Adams, D. L.; Adams, M.; Ahn, S.; Aihara, H.; Alves, G. A.; Amidi, E.; Amos, N.; Anderson, E. W.; Astur, R.; Baarmand, M. M.; Baden, A.; Balamurali, V.; Balderston, J.; Baldin, B.; Banerjee, S.; Bantly, J.; Bartlett, J. F.; Bazizi, K.; Belyaev, A.; Beri, S. B.; Bertram, I.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Biswas, N.; Blazey, G.; Blessing, S.; Bloom, P.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Borders, J.; Boswell, C.; Brandt, A.; Brock, R.; Bross, A.; Buchholz, D.; Burtovoi, V. S.; Butler, J. M.; Carvalho, W.; Casey, D.; Castilla-Valdez, H.; Chakraborty, D.; Chang, S.-M.; Chekulaev, S. V.; Chen, L.-P.; Chen, W.; Choi, S.; Chopra, S.; Choudhary, B. C.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cobau, W. G.; Cochran, J.; Cooper, W. E.; Cretsinger, C.; Cullen-Vidal, D.; Cummings, M. A.; Cutts, D.; Dahl, O. I.; de, K.; del Signore, K.; Demarteau, M.; Denisov, D.; Denisov, S. P.; Diehl, H. T.; Diesburg, M.; di Loreto, G.; Draper, P.; Drinkard, J.; Ducros, Y.; Dudko, L. V.; Dugad, S. R.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Evdokimov, V. N.; Fahland, T.; Fatyga, M.; Fatyga, M. K.; Featherly, J.; Feher, S.; Fein, D.; Ferbel, T.; Finocchiaro, G.; Fisk, H. E.; Fisyak, Y.; Flattum, E.; Forden, G. E.; Fortner, M.; Frame, K. C.; Fuess, S.; Gallas, E.; Galyaev, A. N.; Gartung, P.; Geld, T. L.; Genik, R. J., II; Genser, K.; Gerber, C. E.; Gibbard, B.; Glenn, S.; Gobbi, B.; Goforth, M.; Goldschmidt, A.; Gómez, B.; Gomez, G.; Goncharov, P. I.; González Solís, J. L.; Gordon, H.; Goss, L. T.; Goussiou, A.; Graf, N.; Grannis, P. D.; Green, D. R.; Green, J.; Greenlee, H.; Grim, G.; Grossman, N.; Grudberg, P.; Grünendahl, S.; Guglielmo, G.; Guida, J. A.; Guida, J. M.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, P.; Gutnikov, Y. E.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hahn, K. S.; Hall, R. E.; Hansen, S.; Hauptman, J. M.; Hedin, D.; Heinson, A. P.; Heintz, U.; Hernández-Montoya, R.; Heuring, T.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoftun, J. S.; Hsieh, F.; Hu, Ting; Hu, Tong; Huehn, T.; Ito, A. S.; James, E.; Jaques, J.; Jerger, S. A.; Jesik, R.; Jiang, J. Z.-Y.; Joffe-Minor, T.; Johns, K.; Johnson, M.; Jonckheere, A.; Jones, M.; Jöstlein, H.; Jun, S. Y.; Jung, C. K.; Kahn, S.; Kalbfleisch, G.; Kang, J. S.; Kehoe, R.; Kelly, M. L.; Kim, C. L.; Kim, S. K.; Klatchko, A.; Klima, B.; Klopfenstein, C.; Klyukhin, V. I.; Kochetkov, V. I.; Kohli, J. M.; Koltick, D.; Kostritskiy, A. V.; Kotcher, J.; Kotwal, A. V.; Kourlas, J.; Kozelov, A. V.; Kozlovski, E. A.; Krane, J.; Krishnaswamy, M. R.; Krzywdzinski, S.; Kunori, S.; Lami, S.; Lan, H.; Lander, R.; Landry, F.; Landsberg, G.; Lauer, B.; Leflat, A.; Li, H.; Li, J.; Li-Demarteau, Q. Z.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Liu, Q.; Liu, Y. C.; Lobkowicz, F.; Loken, S. C.; Lökös, S.; Lueking, L.; Lyon, A. L.; Maciel, A. K.; Madaras, R. J.; Madden, R.; Magaña-Mendoza, L.; Mani, S.; Mao, H. S.; Markeloff, R.; Markosky, L.; Marshall, T.; Martin, M. I.; May, B.; Mayorov, A. A.; McCarthy, R.; McDonald, J.; McKibben, T.; McKinley, J.; McMahon, T.; Melanson, H. L.; Merkin, M.; Merritt, K. W.; Miettinen, H.; Mincer, A.; de Miranda, J. M.; Mishra, C. S.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Mooney, P.; da Motta, H.; Murphy, C.; Nang, F.; Narain, M.; Narasimham, V. S.; Narayanan, A.; Neal, H. A.; Negret, J. P.; Nemethy, P.; Nes̆iĆ, D.; Nicola, M.; Norman, D.; Oesch, L.; Oguri, V.; Oltman, E.; Oshima, N.; Owen, D.; Padley, P.; Pang, M.; Para, A.; Park, Y. M.; Partridge, R.; Parua, N.; Paterno, M.; Perkins, J.; Peters, M.; Piekarz, H.; Pischalnikov, Y.; Podstavkov, V. M.; Pope, B. G.; Prosper, H. B.; Protopopescu, S.; Pus̆eljić, D.; Qian, J.; Quintas, P. Z.; Raja, R.; Rajagopalan, S.; Ramirez, O.; Rapidis, P. A.; Rasmussen, L.; Reucroft, S.; Rijssenbeek, M.; Rockwell, T.; Roe, N. A.; Rubinov, P.; Ruchti, R.; Rutherfoord, J.; Sánchez-Hernández, A.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Sculli, J.; Shabalina, E.; Shaffer, C.; Shankar, H. C.; Shivpuri, R. K.; Shupe, M.; Singh, H.; Singh, J. B.; Singh, P.; Sirotenko, V.; Smart, W.; Smith, A.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snow, J.; Snyder, S.; Solomon, J.; Sood, P. M.; Sosebee, M.; Sotnikova, N.; Souza, M.; Spadafora, A. L.; Stephens, R. W.; Stevenson, M. L.; Stewart, D.; Stoianova, D. A.; Stoker, D.; Strauss, M.; Streets, K.; Strovink, M.; Sznajder, A.; Tamburello, P.; Tarazi, J.; Tartaglia, M.; Thomas, T. L.; Thompson, J.; Trippe, T. G.; Tuts, P. M.; Varelas, N.; Varnes, E. W.; Vititoe, D.; Volkov, A. A.; Vorobiev, A. P.; Wahl, H. D.; Wang, G.; Warchol, J.; Watts, G.; Wayne, M.; Weerts, H.; White, A.; White, J. T.; Wightman, J. A.; Willis, S.; Wimpenny, S. J.; Wirjawan, J. V.; Womersley, J.; Won, E.; Wood, D. R.; Xu, H.; Yamada, R.; Yamin, P.; Yanagisawa, C.; Yang, J.; Yasuda, T.; Yepes, P.; Yoshikawa, C.; Youssef, S.; Yu, J.; Yu, Y.; Zhu, Q.; Zhu, Z. H.; Zieminska, D.; Zieminski, A.; Zverev, E. G.; Zylberstejn, A.

    1997-05-01

    We report on a search for pair production of a fourth generation charge -1/3 quark ( b') in pp¯ collisions at s = 1.8 TeV by the DØ experiment at the Fermilab Tevatron using an integrated luminosity of 93 pb-1. Both b' quarks are assumed to decay via flavor changing neutral currents (FCNC). The search uses the signatures γ+3 jets +μ-tag and 2γ+2 jets. We see no significant excess of events over the expected background. We place an upper limit on the production cross section times branching fraction that is well below theoretical expectations for a b' decaying exclusively via FCNC for b' masses up to mZ+mb.

  4. Ring Current Pressure Estimation withRAM-SCB using Data Assimilation and VanAllen Probe Flux Data

    NASA Astrophysics Data System (ADS)

    Godinez, H. C.; Yu, Y.; Henderson, M. G.; Larsen, B.; Jordanova, V.

    2015-12-01

    Capturing and subsequently modeling the influence of tail plasma injections on the inner magnetosphere is particularly important for understanding the formation and evolution of Earth's ring current. In this study, the ring current distribution is estimated with the Ring Current-Atmosphere Interactions Model with Self-Consistent Magnetic field (RAM-SCB) using, for the first time, data assimilation techniques and particle flux data from the Van Allen Probes. The state of the ring current within the RAM-SCB is corrected via an ensemble based data assimilation technique by using proton flux from one of the Van Allen Probes, to capture the enhancement of ring current following an isolated substorm event on July 18 2013. The results show significant improvement in the estimation of the ring current particle distributions in the RAM-SCB model, leading to better agreement with observations. This newly implemented data assimilation technique in the global modeling of the ring current thus provides a promising tool to better characterize the effect of substorm injections in the near-Earth regions. The work is part of the Space Hazards Induced near Earth by Large, Dynamic Storms (SHIELDS) project in Los Alamos National Laboratory.

  5. Ring current pressure estimation with RAM-SCB using data assimilation and Van Allen Probe flux data

    NASA Astrophysics Data System (ADS)

    Godinez, H. C.; Yu, Y.; Lawrence, E.; Henderson, M. G.; Larsen, B.; Jordanova, V. K.

    2016-12-01

    Capturing and subsequently modeling the influence of tail plasma injections on the inner magnetosphere is important for understanding the formation and evolution of the ring current. In this study, the ring current distribution is estimated with the Ring Current-Atmosphere Interactions Model with Self-Consistent Magnetic field (RAM-SCB) using, for the first time, data assimilation techniques and particle flux data from the Van Allen Probes. The state of the ring current within the RAM-SCB model is corrected via an ensemble based data assimilation technique by using proton flux from one of the Van Allen Probes, to capture the enhancement of the ring current following an isolated substorm event on 18 July 2013. The results show significant improvement in the estimation of the ring current particle distributions in the RAM-SCB model, leading to better agreement with observations. This newly implemented data assimilation technique in the global modeling of the ring current thus provides a promising tool to improve the characterization of particle distribution in the near-Earth regions.

  6. Lower Current Large Deviations for Zero-Range Processes on a Ring

    NASA Astrophysics Data System (ADS)

    Chleboun, Paul; Grosskinsky, Stefan; Pizzoferrato, Andrea

    2017-04-01

    We study lower large deviations for the current of totally asymmetric zero-range processes on a ring with concave current-density relation. We use an approach by Jensen and Varadhan which has previously been applied to exclusion processes, to realize current fluctuations by travelling wave density profiles corresponding to non-entropic weak solutions of the hyperbolic scaling limit of the process. We further establish a dynamic transition, where large deviations of the current below a certain value are no longer typically attained by non-entropic weak solutions, but by condensed profiles, where a non-zero fraction of all the particles accumulates on a single fixed lattice site. This leads to a general characterization of the rate function, which is illustrated by providing detailed results for four generic examples of jump rates, including constant rates, decreasing rates, unbounded sublinear rates and asymptotically linear rates. Our results on the dynamic transition are supported by numerical simulations using a cloning algorithm.

  7. A novel approach for generating giant electronic persistent currents in symmetric defect mesoscopic-ring networks

    NASA Astrophysics Data System (ADS)

    Hu, Xubo; Yang, Xiangbo; Deng, Dongmei

    2017-04-01

    According to optical analogy of electrons' behavior in mesoscopic systems, we change optical symmetric defect waveguide networks being able to create strong photonic localizations into electronic symmetric defect mesoscopic-ring networks (SDMRNs) being capable of generating giant electronic persistent currents. These simple SDMRNs can produce giant electronic persistent currents in the absence of magnetic field, stub, and impurity. We give out the sufficient condition for generating maximum electronic persistent current |Jp|max in SDMRNs and obtain the formula of |Jp|max. It is found that |Jp|max is proportional to the inverse square of the breaking degree of defect, Δd. Our results may deepen one's knowledge on the correlation between photonic and electronic networks and may be useful for the designing of microcircuits with large electric current.

  8. Lower Current Large Deviations for Zero-Range Processes on a Ring

    NASA Astrophysics Data System (ADS)

    Chleboun, Paul; Grosskinsky, Stefan; Pizzoferrato, Andrea

    2017-02-01

    We study lower large deviations for the current of totally asymmetric zero-range processes on a ring with concave current-density relation. We use an approach by Jensen and Varadhan which has previously been applied to exclusion processes, to realize current fluctuations by travelling wave density profiles corresponding to non-entropic weak solutions of the hyperbolic scaling limit of the process. We further establish a dynamic transition, where large deviations of the current below a certain value are no longer typically attained by non-entropic weak solutions, but by condensed profiles, where a non-zero fraction of all the particles accumulates on a single fixed lattice site. This leads to a general characterization of the rate function, which is illustrated by providing detailed results for four generic examples of jump rates, including constant rates, decreasing rates, unbounded sublinear rates and asymptotically linear rates. Our results on the dynamic transition are supported by numerical simulations using a cloning algorithm.

  9. Interaction of ring current and radiation belt protons with ducted plasmaspheric hiss. 1: Diffusion coefficients and timescales

    NASA Technical Reports Server (NTRS)

    Kozyra, J. U.; Rasmussen, C. E.; Miller, R. H.; Lyons, L. R.

    1994-01-01

    Protons that are convected into the inner magnetosphere in response to enhanced magnetic activity can resonate with ducted plasmaspheric hiss in the outer plasmasphere via an anomalous Doppler-shifted cyclotron resonance. Plasmaspheric hiss is a right-hand-polarized electromagnetic emission that is observed to fill the plasmasphere on a routine basis. When plasmaspheric hiss is confined within field-aligned ducts or guided along density gradients, wave normal angles remain largely below 45 deg. This allows resonant interactions with ions at typical ring current and radiation belt energies to take place. Such field-aligned ducts have been observed both within the plasmasphere and in regions outside of the plasmasphere. Wave intensities are estimated using statistical information from studies of detached plasma regions. Diffusion coefficients are presented for a range of L shells and proton energies for a fixed wave distribution. Harmonic resonances in the range N = +/-100 are considered in order to include interactions between hiss at 100 Hz to 2 kHz frequencies, and protons in the energy range between approximately 10 keV and 1000 keV. Diffusion timescales are estimated to be of the order of tens of days and comparable to or shorter than lifetimes for Coulomb decay and charge exchange losses over most of the energy and spatial ranges of interest.

  10. Radial and local time structure of the Saturnian ring current, revealed by Cassini

    NASA Astrophysics Data System (ADS)

    Sergis, N.; Jackman, C. M.; Thomsen, M. F.; Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Dougherty, M. K.; Krupp, N.; Wilson, R. J.

    2017-02-01

    We analyze particle and magnetic field data obtained between July 2004 and December 2013 in the equatorial magnetosphere of Saturn, by the Cassini spacecraft. The radial and local time distribution of the total (thermal and suprathermal) particle pressure and total plasma beta (ratio of particle to magnetic pressure) over radial distances from 5 to 16 Saturn radii (RS = 60,258 km) is presented. The average azimuthal current density Jϕ and its separate components (inertial, pressure gradient, and anisotropy) are computed as a function of radial distance and local time and presented as equatorial maps. We explore the relative contribution of different physical mechanisms that drive the ring current at Saturn. Results show that (a) the particle pressure is controlled by thermal plasma inside of 8 RS and by the hot ions beyond 12 RS, exhibiting strong local time asymmetry with higher pressures measured at the dusk and night sectors; (b) the plasma beta increases with radial distance and remains >1 beyond 8-10 RS for all local times; (c) the ring current is asymmetric in local time and forms a maximum region between 7 and 13 RS, with values up to 100-115 pA/m2; and (d) the ring current is inertial everywhere inside of 7 RS, exhibits a mixed nature between 7 and 11 RS and is pressure gradient driven beyond 11 RS, with the exception of the noon sector where the mixed nature persists. In the dawn sector, it appears strongly pressure gradient driven for a wider range of radial distance, consistent with fast return flow of hot, tenuous magnetospheric plasma following tail reconnection.

  11. A possible mechanism for enhanced persistent current sextupole decay in SSC dipoles

    SciTech Connect

    Stiening, R.

    1991-01-01

    It has recently been discovered that the HEAR superconducting dipoles have a periodic pattern in their fields as measured along the axis of the dipole. This effect has more recently been observed in the prototype SSC 5 cm dipole. The wavelength of the periods observed in both dipoles is equal to the transposition pitch length of the Rutherford cable. A plausible explanation for the periodic pattern is the existence of a transport current trapped within the cable. That is, a current which runs through one strand from the solder joint at the one end of the cable to the solder joint at the other end, and which returns back by way of another strand. The average current in the strands, which is the current from the power supply, is unaffected by the presence of currents trapped within the cable. The size of the observed field oscillation suggests that the trapped currents might be as large as 100 amps. There is evidence that the trapped currents are time dependent. This is reasonable since the I-V characteristics of the various resistive elements in the cable are all different so the equilibrium distribution of current in the strands should depend on the excitation level of the magnet. It is the purpose of this note to point out that the time dependence of trapped currents is a powerful mechanism for causing the time decay of persistent current'' multipoles.

  12. Statistics of large currents in the Kipnis-Marchioro-Presutti model in a ring geometry

    NASA Astrophysics Data System (ADS)

    Zarfaty, Lior; Meerson, Baruch

    2016-03-01

    We use the macroscopic fluctuation theory to determine the statistics of large currents in the Kipnis-Marchioro-Presutti (KMP) model in a ring geometry. About 10 years ago this simple setting was instrumental in identifying a breakdown of the additivity principle in a class of lattice gases at currents exceeding a critical value. Building on earlier work, we assume that, for supercritical currents, the optimal density profile, conditioned on the given current, has the form of a traveling wave (TW). For the KMP model we find this TW analytically, in terms of elliptic functions, for any supercritical current I. Using this TW solution, we evaluate, up to a pre-exponential factor, the probability distribution P(I). We obtain simple asymptotics of the TW and of P(I) for currents close to the critical current, and for currents much larger than the critical current. In the latter case we show that -\\ln P(I)˜ I\\ln I , whereas the optimal density profile acquires a soliton-like shape. Our analytic results are in a very good agreement with Monte-Carlo simulations and numerical solutions of Hurtado and Garrido (2011).

  13. Limit on Tensor Currents from Li 8 β Decay

    NASA Astrophysics Data System (ADS)

    Sternberg, M. G.; Segel, R.; Scielzo, N. D.; Savard, G.; Clark, J. A.; Bertone, P. F.; Buchinger, F.; Burkey, M.; Caldwell, S.; Chaudhuri, A.; Crawford, J. E.; Deibel, C. M.; Greene, J.; Gulick, S.; Lascar, D.; Levand, A. F.; Li, G.; Pérez Galván, A.; Sharma, K. S.; Van Schelt, J.; Yee, R. M.; Zabransky, B. J.

    2015-10-01

    In the standard model, the weak interaction is formulated with a purely vector-axial-vector (V -A ) structure. Without restriction on the chirality of the neutrino, the most general limits on tensor currents from nuclear β decay are dominated by a single measurement of the β -ν ¯ correlation in He 6 β decay dating back over a half century. In the present work, the β -ν ¯ -α correlation in the β decay of Li 8 and subsequent α -particle breakup of the Be8 * daughter was measured. The results are consistent with a purely V -A interaction and in the case of couplings to right-handed neutrinos (CT=-CT' ) limits the tensor fraction to |CT/CA|2<0.011 (95.5% C.L.). The measurement confirms the He 6 result using a different nuclear system and employing modern ion-trapping techniques subject to different systematic uncertainties.

  14. New analysis of 14O β decay: Branching ratios and conserved vector current consistency

    NASA Astrophysics Data System (ADS)

    Towner, I. S.; Hardy, J. C.

    2005-11-01

    The ground-state Gamow-Teller transition in the decay of 14O is strongly hindered and the electron spectrum shape deviates markedly from the allowed shape. A reanalysis of the only available data on this spectrum changes the branching ratio assigned to this transition by seven standard deviations: Our new result is (0.54±0.02)%. The Kurie plot data from two earlier publications are also examined, and a revision to their published branching ratios is recommended. The required nuclear matrix elements are calculated with the shell model, and, for the first time, consistency is obtained between the M1 matrix element deduced from the analog γ transition in 14N and that deduced from the slope in the shape-correction function in the β transition, a requirement of the conserved-vector current hypothesis. This consistency is obtained, however, only if renormalized rather than free-nucleon operators are used in the shell-model calculations. In the mirror decay of 14C, a similar situation occurs. Consistency among the 14C lifetime, the slope of the shape-correction function, and the M1 matrix element from γ decay can be achieved only with renormalized operators in the shell-model calculation.

  15. Decay of a superfluid current of ultracold atoms in a toroidal trap

    NASA Astrophysics Data System (ADS)

    Mathey, Amy C.; Clark, Charles W.; Mathey, L.

    2014-08-01

    Using a numerical implementation of the truncated Wigner approximation, we simulate the experiment reported by Ramanathan et al. in Phys. Rev. Lett. 106, 130401 (2011), 10.1103/PhysRevLett.106.130401, in which a Bose-Einstein condensate is created in a toroidal trap and set into rotation via a phase imprinting technique. A potential barrier is then placed in the trap to study the decay of the superflow. We find that the current decays via thermally activated phase slips, which can also be visualized as vortices crossing the barrier region in the radial direction. Adopting the notion of critical velocity used in the experiment, we determine it to be lower than the local speed of sound at the barrier, in contradiction to the predictions of the zero-temperature Gross-Pitaevskii equation. We map out the superfluid decay rate and critical velocity as a function of temperature and observe a strong dependence. Thermal fluctuations offer a partial explanation of the experimentally observed reduction of the critical velocity from the phonon velocity.

  16. Search for the flavor-changing neutral current decay K sup + yields. pi. sup +. nu. nu

    SciTech Connect

    Ito, M.M. . Joseph Henry Labs.)

    1990-01-01

    The observation that flavor-changing neutral currents (FCNC) in weak decays are highly suppressed was first explained by Glashow, Iliopoulos and Maiani in 1970, and their idea has since become a cornerstone of the Standard Model. They proposed a model of the weak interaction that included a then new fourth quark and which, in a natural way, allowed the existence of a neutral vector boson without inducing FCNC's at tree level. Thus the couplings of the neutral intermediary{hor ellipsis}cause no embarrassment.'' In higher order through, decays like K {yields} {pi}l{bar l} can proceed. Measurements of such processes provide a detailed test of the Standard Model since definite predictions for their rates can be calculated. Conversely, if no contradictions are found and the standard model is assumed to describe the physics, measurements limit the allowed values of the parameters of the model. As is often the case in studying processes that are highly suppressed and heretofore unseen, improvements in the sensitivity of experiments allow the possibility for the discovery of new physics that exhibits a similar experimental signature. This paper describes experiment 787 at Brookhaven which is expected to address some of these issues. The status and future of the experiment will be described here. The main goal of E787 is to measure the rate of K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}} at the standard model level. In addition, the experiment has sensitivity to other FCNC decays of the charged kaon, in particular the decays K{sup +} {yields} {pi}{sup +}{mu}{sup +}{mu}{sup {minus}} and K{sup +} {yields} {pi}{sup +}{gamma}{gamma}.

  17. High-Current Effects in The PEP-II Storage Rings

    SciTech Connect

    Wienands, U.; Sullivan, M.K.; Akre, R.; Cheng, W.; Colocho, W.; DeBarger, S.; Decker, F.-J.; Ecklund, S.; Fisher, A.; Kharakh, D.; Krasnykh, A.; Novokhatski, A.; /SLAC

    2009-06-19

    High beam currents in PEP-II have been a challenge for vacuum system and ring components. For the {approx} 1 cm long bunches peak currents exceed 100 A and modest impedance can give rise to voltage spikes and discharges. During the last two runs, difficulties arose from rf seals at the 'flex flanges' in the HER. High temperatures were seen and the seals turned out to be severely damaged by discharges. In the LER, the horizontal stripline kickers of the bunch-by-bunch feedback system experiences breakdown at high bunch current-Macor pins installed for mechanical stability turned out to be a weak spot causing discharges. Finally, in the HER an experiment to shorten the ion-clearing gap in the beam revealed signs of ion-induced instability indicating that the HER has been operating quite close to the stability limit. The effects shown here are relevant to future high-intensity electron and positron rings like SuperB and PEP-X.

  18. Hysteresis of Current in Noninteracting Atomic Fermi Gases in Optical Ring Potentials

    NASA Astrophysics Data System (ADS)

    Metcalf, Mekena; Chien, Chih-Chun; Lai, Chen-Yen

    Hysteresis is a ubiquitous phenomenon, which can be found in magnets, superfluids, and other many-body systems. Although interactions are present in most systems exhibiting hysteresis, here we show the current of a non-interacting Fermi gas in an optical ring potential produces hysteresis behavior when driven by a time-dependent artificial gauge field and subject to dissipation. Fermions in a ring potential threaded with flux can exhibit a persistent current when the system is in thermal equilibrium, but cold-atoms are clean and dissipation for reaching thermal equilibrium may be introduced by an external, thermal bath. We use the standard relaxation approximation to model the dynamics of cold-atoms driven periodically by an artificial gauge field. A competition of the driven time and the relaxation time leads to hysteresis of the mass current, and work done on the system, as a function of the relaxation time, exhibits similar behavior as Kramers transition rate in chemical reaction and one-dimensional thermal transport.

  19. Predicting EMIC wave properties from ring current conditions observed by Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Jordanova, V.; Fu, X.; Cowee, M.; Gary, S. P.; Winske, D.; Reeves, G. D.

    2016-12-01

    Recently, we have developed a model to predict amplitude and spectrum of the electromagnetic ion cyclotron (EMIC) wave from the anisotropic ring current ion distributions. The model is derived from linear theory and nonlinear hybrid simulations in a large parameter space for homogeneous plasmas consisting of electrons, protons, and helium ions. In this study we apply our model to selected EMIC events observed by Van Allen Probes satellites. Using the plasma conditions measured by the HOPE instrument, we predict EMIC properties and compare them to wave measurements by the EMFISIS instrument. Detailed analysis of these events will be shown.

  20. A bounce-averaged kinetic model of the ring current ion population

    NASA Technical Reports Server (NTRS)

    Jordanova, V. K.; Kozyra, J. U.; Khazanov, G. V.; Nagy, A. F.; Rasmussen, C. E.; Fok, M.-C.

    1994-01-01

    A bounced-averaged ring current kinetic model for arbitrary pitch angle, including losses due to charge exchange and Coulomb collisions along ion drift paths, is developed and solved numerically. Results from simplifield model runs, intended to illustrate the effects of adiabatic drifts and collisional losses on the proton population, are presented. The processes of: (1) particle acceleration under the conditions of time-independent magnetospheric electric fields; (2) a predominant loss of particles with small pitch angles due to charge exchange; and (3) a buildup of a low-energy population caused by the Coulomb drag energy degradation, are discussed.

  1. Reprint of : Semiclassical theory of persistent current fluctuations in ballistic chaotic rings

    NASA Astrophysics Data System (ADS)

    Brouwer, Piet W.; Danon, Jeroen

    2016-08-01

    The persistent current in a mesoscopic ring has a Gaussian distribution with small non-Gaussian corrections. Here we report a semiclassical calculation of the leading non-Gaussian correction, which is described by the three-point correlation function. The semiclassical approach is applicable to systems in which the electron dynamics is ballistic and chaotic, and includes the dependence on the Ehrenfest time. At small but finite Ehrenfest times, the non-Gaussian fluctuations are enhanced with respect to the limit of zero Ehrenfest time.

  2. Transport of Energetic Ions in the Ring Current During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Kistler, Lynn M.; Kaufmann, Richard

    2001-01-01

    In the final year (plus no-cost extentions) of this grant, we have: Used the particle tracing code to perform a systematic study of the expected energy spectra over the full range of local times in the ring current using a variety of electric and magnetic field models. Shown that the Weimer electric field is superior to the Volland-Stern electric field in reproducing the observed energy spectra on the AMPTE CCE spacecraft. Redone our analysis of the pitch angle spectra of energetic ions during storms in the magnetosphere, using a larger data set, and a more reliable classification technique.

  3. Exploring storm time ring current formation and response on the energy input

    NASA Astrophysics Data System (ADS)

    Ilie, Raluca

    While extensive research has been made over the last decades regarding the storm-time dynamics, there are still unanswered questions regarding the ring current formation and plasmasphere evolution, specifically about the ring current response on the energy input. Large-scale data analysis and global magnetospheric simulations provide complementary alternatives for exploring highly complex coupling of the solar wind-ionosphere-magnetosphere system. Superposed Epoch analysis of intense storms data suggests that a distinct time stamp is needed in order to resolve certain solar wind features. However, when it conies to hot proton at geosynchronous orbit, the choice of reference time primarily matters to accurately describe the size of peaks, while the presence and time evolution is unaltered by it. Examination of the role the transient spikes in the solar wind parameters play in the development of magnetic storms, reveals that changes in the energy input produce a nonlinear response of the inner magnetosphere. While initial increases in the energy input enhance the magnetospheric response, as the power transferred to the system is increased, the growth of the ring current is stalled and a saturation limits sets in. A threshold in the energy input is necessary for the ring current to develop, while the short time scale fluctuations in the solar wind parameters did not have a significant contribution. This implies the existence of an internal feedback mechanism as the magnetosphere acts as a low-pass filter of the IMF, limiting the energy flow in the magnetosphere. Further, the main characteristic in determining IMF Bz fluctuation periodicity transfer of solar wind mass and energy to the inner magnetosphere, is the peak signal to noise ratio in the power spectrum of the input parameter, suggesting that a ratio of 10 is needed in order to trigger a similar periodicity in the magnetosphere response. Theoretical and numerical modifications to an inner magnetosphere model

  4. Longitudinal Single-Bunch Instability in the ILC Damping Rings: Estimate of Current Threshold

    SciTech Connect

    Venturini, Marco; Venturini, Marco

    2008-06-25

    Characterization of single-bunch instabilities in the International Linear Collider (ILC) damping rings (DRs) has been indicated as a high-priority activity toward completion of an engineering design. In this paper we report on a first estimate ofthe current thresholds for the instability using numerical and analytical models of the wake potentials associated with the various machine components. The numerical models were derived (upon appropriate scaling) from designs of the correspondingcomponents installed in existing machines. The current thresholds for instabilities were determined by numerical solution of the Vlasov equation for the longitudinal dynamics. For the DR baseline lattice as of Feb. 2007 we find the critical current forinstability to be safely above the design specifications leaving room for further optimization of the choice of the momentum compaction.

  5. Bohm-Aharonov and Kondo effects on tunneling currents in a mesoscopic ring

    SciTech Connect

    Davidovich, M.A.; Anda, E.V.; Chiappe, G.

    1997-03-01

    We present an analysis of the Kondo effect on the Bohm-Aharonov oscillations of the tunneling currents in a mesoscopic ring with a quantum dot inserted in one of its arms. The system is described by an Anderson-impurity tight-binding Hamiltonian where the electron-electron interaction is restricted to the dot. The currents are obtained using nonequilibrium Green functions calculated through a cumulant diagrammatic expansion in the chain approximation. It is shown that at low temperature, even with the system out of resonance, the Kondo peak provides a channel for the electron to tunnel through the dot, giving rise to the Bohm-Aharonov oscillations of the current. At high temperature these oscillations are important only if the dot level is aligned to the Fermi level, when the resonance condition is satisfied. {copyright} {ital 1997} {ital The American Physical Society}

  6. Terahertz emission from two-plasmon-decay induced transient currents in laser-solid interactions

    SciTech Connect

    Liao, G.-Q.; Li, C.; Li, Y.-T. E-mail: zmsheng@sjtu.edu.cn; Wang, W.-M.; Mondal, S.; Hafez, H. A.; Fareed, M. A.; Ozaki, T.; Sheng, Z.-M. E-mail: zmsheng@sjtu.edu.cn; Zhang, J.

    2016-01-15

    We have studied the generation of terahertz (THz) radiation via the interaction of intense femtosecond laser pulses with solid targets at a small incidence angle. It is found that preplasma with a moderate density gradient can enhance the emission. We also observe saturation of the THz output with the driving laser energy. We find that THz emission is closely related to the 3/2 harmonics of the driving laser. Particle-in-cell simulations indicate that under the present experimental conditions, the THz emission could be attributed to the transient currents at the plasma-vacuum interface, mainly formed by the two-plasmon-decay instability.

  7. A Self-Consistent Model of the Interacting Ring Current Ions and Electromagnetic ICWs. Initial Results: Waves and Precipitation Fluxes

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Jordanova, V. K.; Krivorutsky, E. N.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Initial results from the new developed model of the interacting ring current ions and ion cyclotron waves are presented. The model described by the system of two bound kinetic equations: one equation describes the ring current ion dynamics, and another one gives wave evolution. Such system gives a self-consistent description of the ring current ions and ion cyclotron waves in a quasilinear approach. Calculating ion-wave relationships, on a global scale under non steady-state conditions during May 2-5, 1998 storm, we presented the data at three time cuts around initial, main, and late recovery phases of May 4, 1998 storm phase. The structure and dynamics of the ring current proton precipitating flux regions and the wave active ones are discussed in detail.

  8. Effects of a high-density plasma sheet on ring current development during the November 2-6, 1993, magnetic storm

    NASA Astrophysics Data System (ADS)

    Kozyra, J. U.; Jordanova, V. K.; Borovsky, J. E.; Thomsen, M. F.; Knipp, D. J.; Evans, D. S.; McComas, D. J.; Cayton, T. E.

    1998-11-01

    parameter [Akasofu, 1981] overestimates the ring current energy input compared to the drift-loss model by almost an order of magnitude during the main phase. However, the integrated energy input from ɛ, over the 4 day interval of the storm, is in very good agreement with the total energy input inferred from observations. On the other hand, F more closely approximates the magnitude of the ring current energy input alone as calculated in the drift-loss model. An energy budget is constructed for the storm that shows energy inputs from the solar wind and energy dissipation due to ring current buildup and decay, auroral electron precipitation, Joule heating, ion precipitation, and energy storage in the magnetotail in reasonable balance. The ring current energy input accounts for only 15% of the total dissipated energy in this storm interval. A more complete energy budget that extends to November 11, 1993, was compiled by Knipp et al. [this issue].

  9. Effects of superthermal ring current ion tails on the electromagnetic ion cyclotron instability in multi-ion magnetospheric plasmas

    NASA Astrophysics Data System (ADS)

    Mace, R. L.; Sydora, R. D.; Silin, I.

    2011-05-01

    An important plasma source for the storm-enhanced ring current is the plasma sheet. Ion species in the near-Earth plasma sheet have been observed to have power law tails on their velocity distributions, which can be well fitted with kappa distributions under a variety of geomagnetic conditions. Motivated by these ideas, we investigate the electromagnetic ion cyclotron (EMIC) instability driven by hot ring current ions having velocity distributions that exhibit thermal anisotropy and power law tails of varying degrees of hardness (smallness of power index) for parameters consistent with the inner magnetosphere. With few exceptions, the presence of hard power law tails on the velocity distributions of the ring current ion species is observed to significantly enhance instability growth rates relative to a bi-Maxwellian ring current model. For a ring current composed of only hot protons, all EMIC branches are unstable, with the helium branch exhibiting the fastest growth rate for the thermal anisotropies considered. The addition of equal number densities of helium and oxygen ions to the ring current plasma has a dramatic stabilizing effect on the proton and helium branches. In this case it is frequently only the oxygen branch of the EMIC wave dispersion relation which is unstable. The detailed balance between cyclotron damping produced by one species and growth produced by another elevates the importance of the velocity distribution spectral index so that it can serve as a “switch” to turn on instability of certain branches.

  10. Observations of the ring current composition at L less than 4

    NASA Astrophysics Data System (ADS)

    Lundin, R.; Lyons, L. R.; Pisarenko, N.

    1980-06-01

    Observations showing that the low energy (less than 17 keV) portion of the ring current at L less than 4 is composed mainly of O(+) and He(+) ions during quiet times and the recovery of magnetic storms are presented. The data were obtained from the ion composition experiment on board the Prognoz-7 satellite during several passes through the ring current region. For L less than 3.5, the relative abundance of H(+) was only a few percent of the ion energy density in the energy range of 0.2-17 keV. Although O(+) normally dominates for L less than 4, the relative contribution of He(+) increases with decreasing L, and in one case became more abundant than O(+) for L less than 3. One example of a storm injection shows dominance by O(+) ions (82%) with H(+) only giving a minor contribution (15%) to the density. These observations are consistent with inferences based on charge exchange, H(+) being most rapidly lost and He(+) being the most stable.

  11. Absence of Suppression in the Persistent Current by Delocalization in Random-dimer Mesoscopic Rings

    NASA Astrophysics Data System (ADS)

    Liu, Y. M.; Peng, R. W.; Huang, X. Q.; Wang, Mu; Hu, A.; Jiang, S. S.

    2003-02-01

    We study the persistent current (PC) in one-dimensional (1D) magnetic-flux threaded mesoscopic rings, which is constructed according to the random-dimer (RD) model. It is found that the PC varies significantly when the Fermi energy is changed in the system. The PC can approach the behaviour of free electrons regardless of the disorder if there is the extended electronic state at the Fermi level; while the PC can be depressed dramatically if the highest-occupied electronic state is localized or in the intermediate case between the extended state and localized one. This property provides a possible explanation to the anomalously large PC observed in some experiments. Furthermore, it is demonstrated that the electronic delocalization leads to unsuppressed persistent currents and \\sqrt{N} unscattered states exist around the resonant energy in the RD model from the viewpoint of the PC. The possibility to use 1D random-dimer mesoscopic rings as quantum-switch devices is also discussed.

  12. Investigation of 1H NMR chemical shifts of organic dye with hydrogen bonds and ring currents.

    PubMed

    Park, Sung Soo; Won, Yong Sun; Lee, Woojin; Kim, Jae Hong

    2011-04-07

    The (1)H NMR chemical shifts were theoretically computed for the organic dyes 2-(2,6-dimethyl-4H-pyran-4-ylidene)-malononitrile (1), cyano-(2,6-dimethyl-4H-pyran-4-ylidene)-acetic acid methyl ester (2), 2-(2,6-bis(4-(dimethylamino)styryl)-4H-pyran-4-ylidene)-malononitrile (3), and methyl 2-(2,6-bis(4-(dimethylamino)styryl)-4H-pyran-4-ylidene)-2-cyanoacetate (4) at the GIAO/B3LYP/6-311++G(d,p)//B3LYP/6-311++G(d,p) level of theory. Moreover, the intramolecular rotational barriers of the molecules were calculated to evaluate the internal flexibility with respect to the torsional degrees of freedom, and the nuclear-independent chemical shifts (NICS) were employed to analyze the ring currents. The difference was explained in terms of intramolecular hydrogen bonds and ring currents of the molecules. The (1)H NMR spectra were reproduced by experiments for the comparison with computationally constructed data. Our results suggest a good guideline in interpreting (1)H NMR chemical shifts using computational methods and furthermore a reliable perspective for designing molecular structures.

  13. Interactions between magnetosonic waves and ring current protons: Gyroaveraged test particle simulations

    NASA Astrophysics Data System (ADS)

    Fu, Song; Ni, Binbin; Li, Jinxing; Zhou, Chen; Gu, Xudong; Huang, Shiyong; Zhang, Hui; Ge, Yasong; Cao, Xing

    2016-09-01

    Gyroaveraged test particle simulations are implemented to quantitatively investigate interactions between linearly polarized magnetosonic waves (i.e., equatorial noises) and ring current protons inside and outside the plasmasphere at L = 4.5. For magnetosonic waves at the frequency of 33.3 Hz (fw/fcp = 6.4 at the magnetic equator, for L = 4.5), it is found that wave-particle interactions at the resonance order corresponding to the lowest resonant proton energy (i.e., N = 6) are dominant. The interactions at other resonance orders make much less contribution. Near the equatorial loss cone at L = 4.5, magnetosonic waves produce strongest proton pitch angle diffusion at 20 keV inside the plasmasphere and at 100 keV outside the plasmasphere, respectively, reaching a rate above 10-6 s-1. The corresponding energy diffusion dominates over pitch angle diffusion at high pitch angles; therefore, magnetosonic waves are likely to accelerate protons at a few keV inside the plasmasphere and at 10 keV outside the plasmasphere. Due to the emission equatorial confinement, the effect of transit time scattering also occurs for interactions of magnetosonic waves with ring current protons and tends to be increasingly important outside the plasmasphere, which is consistent with previous studies on interactions of magnetosonic waves with radiation belt electrons.

  14. Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Thorne, Richard M.; Horne, Richard B.

    1994-01-01

    Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.

  15. A double-cusp type electrostatic analyzer for high-cadence ring current ion measurements

    NASA Astrophysics Data System (ADS)

    Ogasawara, K.; Allegrini, F.; Burch, J. L.; Desai, M. I.; Ebert, R. W.; Goldstein, J.; John, J. M.; Livi, S. A.; McComas, D. J.

    2015-12-01

    Detailed observations of a variety of ion species at a sufficiently high temporal resolution are essential to understanding the loss and acceleration processes of ring current ions. For example, CRESS/MICS observations indicated that the energy density of suprathermal O+ exceeds that of H+ in large magnetic storms (Daglis et al., 1997), while the H+ energy density dominates under quiet conditions. However, the primary ion loss processes during the storm recovery phase are still incompletely understood. The mechanisms to accelerate upflowing ions, regularly observed with energies of a few keV at ~1000 km altitude, up to the 100s-keV range in the geospace are also not fully understood. Our novel electrostatic analyzer (ESA) employs a toroidal double-shell structure to cover the entire ring current ion range of ~3-250 keV/Q with high temporal resolution (<1 minute with a necessary counting statistics for the quiet time), while saving significant resources in mass and size. In this presentation, we discuss the operation principle and the proof of concept study of the ESA in terms of numerical calculations and ion beam calibration activities. This presentation comprehensively covers the expected sensor performance important for the in-flight capabilities, such as sensor parameters (G-factor, K-factor, and energy resolution), cross-shell contaminations, and UV background counts.

  16. A correlative comparison of the ring current and auroral electrojets using geomagnetic indices

    SciTech Connect

    Cade, W.B. III; Sojka, J.J.; Zhu, L.

    1995-01-01

    From a study of the 21 largest geomagnetic storms during solar cycle 21, a strong correlation is established between the ring current index Dst and the time-weighted accumulation of the 1-hour auroral electrojet indices, AE and AL. The time-weighted accumulation corresponds to convolution of the auroral electrojet indices with an exponential weighting function with an e-folding time of 9.4 hours. The weighted indices AE{sub w} and AL{sub w} have correlation coefficients against Dst ranging between 0.8 and 0.95 for 20 of the 21 storms. Correlation over the entire solar cycle 21 database is also strong but not as strong for an individual storm. A set of simple Dst prediction functions provide a first approximation of the inferred dependence, but the specific functional relationship of Dst(AE{sub w}) or Dst(AL{sub w}) varies from one storm to the next in a systematic way. This variation reveals a missing parametric dependence in the transfer function. However, these results indicate that auroral electroject indices are potentially useful for predicting storm time enhancements of ring current intensity with a few hours lead time. 20 refs., 9 figs., 2 tabs.

  17. Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Thorne, Richard M.; Horne, Richard B.

    1994-01-01

    Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.

  18. Ring current Atmosphere interactions Model with Self-Consistent Magnetic field

    SciTech Connect

    Jordanova, Vania; Jeffery, Christopher; Welling, Daniel

    2016-09-09

    The Ring current Atmosphere interactions Model with Self-Consistent magnetic field (B) is a unique code that combines a kinetic model of ring current plasma with a three dimensional force-balanced model of the terrestrial magnetic field. The kinetic portion, RAM, solves the kinetic equation to yield the bounce-averaged distribution function as a function of azimuth, radial distance, energy and pitch angle for three ion species (H+, He+, and O+) and, optionally, electrons. The domain is a circle in the Solar-Magnetic (SM) equatorial plane with a radial span of 2 to 6.5 RE. It has an energy range of approximately 100 eV to 500 KeV. The 3-D force balanced magnetic field model, SCB, balances the JxB force with the divergence of the general pressure tensor to calculate the magnetic field configuration within its domain. The domain ranges from near the Earth’s surface, where the field is assumed dipolar, to the shell created by field lines passing through the SM equatorial plane at a radial distance of 6.5 RE. The two codes work in tandem, with RAM providing anisotropic pressure to SCB and SCB returning the self-consistent magnetic field through which RAM plasma is advected.

  19. A simple model for counter-rotating ring currents in [ n]circulenes

    NASA Astrophysics Data System (ADS)

    Acocella, A.; Havenith, R. W. A.; Steiner, E.; Fowler, P. W.; Jenneskens, L. W.

    2002-09-01

    Ab initio current density maps for [7]circulene computed using the ipsocentric CTOCD-DZ/6-31G**//RHF/6-31G** method show that in both planar [ 3a (D 7h)] and non-planar, saddle-shaped [ 3b (C 2)] geometries this molecule sustains similar counter-rotating rim (diatropic) and hub (strongly paratropic) currents. A survey of the orbital contributions to the current density reveals that 3 like corannulene ( 1) is a 4d + 4p system with just eight magnetically active and 20 magnetically inactive π electrons. The graph-theoretical Hückel-London model describes the ring-current patterns of [ n]circulenes in terms of a coupling strength (the ratio of radial and tangential resonance integrals) that charts the variation from the decoupled con-rotating currents of the [ n]annulene-within-an-[ m]annulene model to the fully coupled counter-rotating currents of the real [ n]circulene.

  20. Current evolution and plasma density space distribution in the reflex discharge with ring cathodes

    NASA Astrophysics Data System (ADS)

    Samokhin, A. A.; Liziakin, G. D.; Gavrikov, A. V.; Usmanov, R. A.; Smirnov, V. P.

    2016-11-01

    In this paper the numerical model of direct current gas discharge in drift-diffusion approximation is considered. For two-component plasma the processes of the gas discharge development in the reflex geometry with ring cathodes at a helium pressure of 35 mTorr are studied. We investigate the influence of: (a) the boundary conditions on the dielectric, (b) the electron temperature and (c) the coefficient of the secondary ion-electron emission on the I-U curve of the discharge. In a magnetic field of 50 Gauss the impact of the discharge voltage U = 300-700 V on the evolutionary process of the discharge is examined. The effect of diffusion on maintaining steady state discharge is researched. The parameters of the existence of a high-current (tens of μA) and low voltage (tens of mA) discharge modes are defined.

  1. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 2; Waves, Precipitating Ring Current Ions, and Thermal Electron Heating

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.

    2006-01-01

    This paper is dedicated to further presentations and discussions of the results from our new global self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves [Khazanov et al., 2006; here referred to as Paper 1]. In order to adequately take into account the wave propagation and refraction in a multi-ion plasmasphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation [for details see Paper 1]. To demonstrate the effects of the EMIC wave propagation and refraction on the RC proton precipitations and heating of the thermal plasmaspheric electrons we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. Firstly, the wave induced precipitations have a quite fine structure, and are highly organized by location of the plasmapause gradient. The strongest fluxes of about 4 (raised dot) 10(exp 6) [(cm (raised dot) s (raised dot) sr)(sup -l)] are observed during the main and early recovery phases of the storm. The very interesting and probably more important finding is that in a number of cases the most intense precipitating fluxes are not simply connected to the most intense EMIC waves. The character of the EMIC wave power spectral density distribution over the equatorial wave normal angle is an extremely crucial for the effectiveness of the RC ion scattering. Secondly, comparison of the global proton precipitating patterns with the results from other ring current model [Kozyra et al., 1997] reveals that although we observe a qualitative agreement between localizations of the wave induced fluxes in the models, there is no quantitative agreement between the magnitudes of these fluxes. These differences are mainly due to a qualitative difference between the characters of the EMIC wave power spectral density distributions over the equatorial wave normal angle. Finally, the two energy sources to the

  2. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 2; Waves, Precipitating Ring Current Ions, and Thermal Electron Heating

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.

    2006-01-01

    This paper is dedicated to further presentations and discussions of the results from our new global self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves [Khazanov et al., 2006; here referred to as Paper 1]. In order to adequately take into account the wave propagation and refraction in a multi-ion plasmasphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation [for details see Paper 1]. To demonstrate the effects of the EMIC wave propagation and refraction on the RC proton precipitations and heating of the thermal plasmaspheric electrons we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. Firstly, the wave induced precipitations have a quite fine structure, and are highly organized by location of the plasmapause gradient. The strongest fluxes of about 4 (raised dot) 10(exp 6) [(cm (raised dot) s (raised dot) sr)(sup -l)] are observed during the main and early recovery phases of the storm. The very interesting and probably more important finding is that in a number of cases the most intense precipitating fluxes are not simply connected to the most intense EMIC waves. The character of the EMIC wave power spectral density distribution over the equatorial wave normal angle is an extremely crucial for the effectiveness of the RC ion scattering. Secondly, comparison of the global proton precipitating patterns with the results from other ring current model [Kozyra et al., 1997] reveals that although we observe a qualitative agreement between localizations of the wave induced fluxes in the models, there is no quantitative agreement between the magnitudes of these fluxes. These differences are mainly due to a qualitative difference between the characters of the EMIC wave power spectral density distributions over the equatorial wave normal angle. Finally, the two energy sources to the

  3. Electron-phonon interaction effect on persistent current in a one-dimensional quantum ring by using a simple model

    NASA Astrophysics Data System (ADS)

    Omidi, Mahboubeh; Faizabadi, Edris

    2015-09-01

    We use a simple model to study the electron-phonon interaction influences on persistent current in a one-dimensional quantum ring enclosed by a magnetic flux. With increasing the temperature, persistent current amplitude is reduced, especially in a quantum ring with two ions per primitive cell (diatomic ring) because of the participation of optical phonons. Furthermore, the periodicity of the Aharonov-Bohm oscillations changes to Φ0 / 2 (Φ0 is magnetic flux quantum). In a diatomic ring, by increasing the difference between left and right nearest-neighbor hopping integrals at zero temperature, persistent current variations show a transition from metallic to insulator against distinctive behavior at nonzero temperature.

  4. Dynamical MI-Coupling of the Ring Current and Plasmasphere and its Impacts on the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Brandt, P. C.; Keika, K.; Hsieh, S.-Y.; Talaat, E.

    2012-04-01

    The plasma pressure and its gradients drive the dominating current system of the inner magnetosphere, which is commonly referred to as the ring current, or partial ring current. Protons, He+ and O+ are heated and transported from the magnetotail in to the inner magnetosphere, leading to an enhanced plasma pressure in the energy range of about 10-300 keV. At the same time, the magnetospheric currents close through the ionosphere, resulting in a modification of ionospheric flows, fields and conductance that have macroscopic influences on magnetospheric dynamics. In this presentation we discuss how the ring current, plasma sphere and ionosphere evolve together during storms and substorms. First, we review the most recent ideas on how ions are heated and transported in to the ring current and show how it evolves and drive the 3D electrical current system of the inner magnetosphere. Second, to illustrate the dramatic and large-scale consequences of MI-coupling, we will use the so-called sub-auroral polarization stream (SAPS) phenomenon. During the course of a partial ring current enhancement, the flow and conductance of the ionospheric trough evolve together in way that can only be explained by considering all systems simultaneously. We will use multiple in-situ and global measurements from SuperDARN, DMSP, IMAGE, Cluster, and more to highlight the unsolved mysteries in MI-coupling represented in the SAPS region. Third, we will present and compare observations of the inner magnetospheres of Saturn and Jupiter.

  5. Searching for Tensor Currents in the Weak Interaction Using 8Li β Decay

    NASA Astrophysics Data System (ADS)

    Burkey, M. T.; Savard, G.; Segel, R. E.; Clark, J. A.; Scielzo, N. D.; Gallant, A. T.; Kolos, K.; Padgett, S. W.; Wang, B. S.; Hirsh, T.; Heckmaier, E.; Marley, S. T.; Morgan, G.; Orford, R.; Sharma, K. S.

    2017-01-01

    The weak interaction is framed in the Standard Model with a pure vector-axial vector structure. A high-precision measurement of the β - ν correlation coefficient (aβν) could reveal contributions from tensor or scalar currents and give insight into new physics. We utilize stopped 8Li in the Beta decay Paul Trap (BPT) at Argonne National Lab to measure aβν. The BPT is surrounded on 4 sides with double-sided silicon strip detectors backed by plastic scintillator detectors, which allow the kinematics of the 8Li decay products to be over-constrained. A previous measurement done by our collaboration resulted in the first improvement in over 50 years to the tensor limit of aβν in a nuclear setting and was recently published in PRL. We have since upgraded our system and obtained over ten times our previous statistics. Our goal is to achieve a limit of aβν with an uncertainty of 0.001. Analysis is ongoing. We acknowledge NSERC, Canada, App. No. 216974, the U.S. DOE Contract No. DE-AC02-06CH11357 [ANL] and DE-AC52-07NA27344 [LLNL], NSF Grant No. 1144082 and the ANL ATLAS facility

  6. Energy dynamics and current sheet structure in fluid and kinetic simulations of decaying magnetohydrodynamic turbulence

    SciTech Connect

    Makwana, K. D. Cattaneo, F.; Zhdankin, V.; Li, H.; Daughton, W.

    2015-04-15

    Simulations of decaying magnetohydrodynamic (MHD) turbulence are performed with a fluid and a kinetic code. The initial condition is an ensemble of long-wavelength, counter-propagating, shear-Alfvén waves, which interact and rapidly generate strong MHD turbulence. The total energy is conserved and the rate of turbulent energy decay is very similar in both codes, although the fluid code has numerical dissipation, whereas the kinetic code has kinetic dissipation. The inertial range power spectrum index is similar in both the codes. The fluid code shows a perpendicular wavenumber spectral slope of k{sub ⊥}{sup −1.3}. The kinetic code shows a spectral slope of k{sub ⊥}{sup −1.5} for smaller simulation domain, and k{sub ⊥}{sup −1.3} for larger domain. We estimate that collisionless damping mechanisms in the kinetic code can account for the dissipation of the observed nonlinear energy cascade. Current sheets are geometrically characterized. Their lengths and widths are in good agreement between the two codes. The length scales linearly with the driving scale of the turbulence. In the fluid code, their thickness is determined by the grid resolution as there is no explicit diffusivity. In the kinetic code, their thickness is very close to the skin-depth, irrespective of the grid resolution. This work shows that kinetic codes can reproduce the MHD inertial range dynamics at large scales, while at the same time capturing important kinetic physics at small scales.

  7. Updated Search for the Flavor-Changing Neutral-Current Decay $D^0 \\to \\mu^+ \\mu^-$

    SciTech Connect

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR

    2010-08-01

    We report on a search for the flavor-changing neutral-current decay D{sup 0} {yields} {mu}{sup +}{mu}{sup -} in p{bar p} collisions at {radical}s = 1.96TeV using 360 pb{sup -1} of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. A displaced vertex trigger selects long-lived D{sup 0} candidates in the {mu}{sup +}{mu}{sup -}, {pi}{sup +}{pi}{sup -}, and K{sup -}{pi}{sup +} decay modes. We use the Cabibbo-favored D{sup 0} {yields} K{sup -}{pi}{sup +} channel to optimize the selection criteria in an unbiased manner, and the kinematically similar D{sup 0} {yields} {pi}{sup +}{pi}{sup -} channel for normalization. We set an upper limit on the branching fraction {Beta}(D{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 2.1 x 10{sup -7} (3.0 x 10{sup -7}) at the 90% (95%) confidence level.

  8. Persistent current and Drude weight of one-dimensional interacting fermions on imperfect ring from current lattice density functional theory

    NASA Astrophysics Data System (ADS)

    Akande, Akinlolu; Sanvito, Stefano

    2016-11-01

    We perform a numerical study of interacting one-dimensional Hubbard rings with a single impurity potential and pierced by a magnetic flux. Our calculations are carried out at the level of current lattice density functional theory (CLDFT) for the Hubbard model and compared to known results obtained in the thermodynamical limit from the Bethe ansatz. In particular, we investigate the effects of disorder and Coulomb interaction on the persistent current (PC) and the Drude weight. It is found that CLDFT is able to accurately describe qualitative and quantitative features of these ground state properties in the presence of disorder and electronic interaction. When the impurity potential is switched off, the CLDFT approach describes well the velocity of the Luttinger liquid excitations as a function of both interaction strength and electron filling. Then, when the impurity scattering potential is finite, we find the PC to vanish as {{L}-{{α\\text{B}}-1}} for large L and independent on the strength of the scattering potential, in good agreement with Luttinger liquid theory.

  9. Effect of resistivity profile on current decay time of initial phase of current quench in neon-gas-puff inducing disruptions of JT-60U

    SciTech Connect

    Kawakami, S.; Ohno, N.; Shibata, Y.; Isayama, A.; Kawano, Y.; Watanabe, K. Y.; Takizuka, T.; Okamoto, M.

    2013-11-15

    According to an early work [Y. Shibata et al., Nucl. Fusion 50, 025015 (2010)] on the behavior of the plasma current decay in the JT-60U disruptive discharges caused by the radiative collapse with a massive neon-gas-puff, the increase of the internal inductance mainly determined the current decay time of plasma current during the initial phase of current quench. To investigate what determines the increase of the internal inductance, we focus attention on the relationship between the electron temperature (or the resistivity) profile and the time evolution of the current density profile and carry out numerical calculations. As a result, we find the reason of the increase of the internal inductance: The current density profile at the start of the current quench is broader than an expected current density profile in the steady state, which is determined by the temperature (or resistivity) profile. The current density profile evolves into peaked one and the internal inductance is increasing.

  10. A new current regulator for the APS storage ring correction magnet bipolar switching mode converters.

    SciTech Connect

    Wang, J.; Accelerator Systems Division

    2004-01-01

    The correction magnets in the Advanced Photon Source's storage ring are powered by PWM-controlled bipolar switching-mode converters. These converters are designed to operate at up to {+-}150 A. The original control circuit used a polarity detection circuit with a hysteresis to determine which IGBT was needed to regulate the current with a given polarity. Only the required IGBT was switched with PWM pulses while others were held on or off continuously. The overall IGBT switching losses were minimized by the design. The shortcoming of the design was that the converter's output was unstable near zero current because of the hysteresis. To improve the stability, a new current regulator using a different PWM method has been developed to eliminate the requirement of the polarity detection. With the new design, converters can operate smoothly in the full range of {+-}150 A. The new design also meets tighter specs in terms of the ripple current and dynamic response. This paper describes the design of the new regulator and the test results.

  11. Effects of pressure anisotropy on magnetospheric magnetohydrodynamics equilibrium of an internal ring current system

    SciTech Connect

    Furukawa, M.

    2014-01-15

    Effects of pressure anisotropy on magnetospheric magnetohydrodynamics equilibrium are studied analytically and numerically, where the plasma is confined by only poloidal magnetic field generated by an internal ring current. The plasma current due to finite pressure can be divided into two components; one remains at isotropic pressure and the other arises from pressure anisotropy. When p{sub ⊥}, the pressure perpendicular to the magnetic field, is larger than p{sub ∥}, the pressure parallel to the magnetic field, those two components of plasma current tend to cancel each other to reduce the total amount of plasma current. Equilibrium beta limit is also examined, where the beta is a ratio of the plasma pressure to the magnetic pressure. The equilibrium beta limit decreases as the pressure anisotropy becomes strong. The beta value is strictly limited by ellipticity of the equilibrium equation when p{sub ∥}>p{sub ⊥}. On the other hand, when p{sub ⊥}>p{sub ∥}, although the tendency of the beta limit agrees with the ellipticity condition of the equilibrium equation, equilibria with a hyperbolic region can be obtained by iterative procedure with practically reasonable convergence criteria.

  12. The effect of ring current electron scattering rates on magnetosphere-ionosphere coupling

    NASA Astrophysics Data System (ADS)

    Perlongo, N. J.; Ridley, A. J.; Liemohn, M. W.; Katus, R. M.

    2017-04-01

    This simulation study investigated the electrodynamic impact of varying descriptions of the diffuse aurora on the magnetosphere-ionosphere (M-I) system. Pitch angle diffusion caused by waves in the inner magnetosphere is the primary source term for the diffuse aurora, especially during storm time. The magnetic local time (MLT) and storm-dependent electrodynamic impacts of the diffuse aurora were analyzed using a comparison between a new self-consistent version of the Hot Electron Ion Drift Integrator with varying electron scattering rates and real geomagnetic storm events. The results were compared with Dst and hemispheric power indices, as well as auroral electron flux and cross-track plasma velocity observations. It was found that changing the maximum lifetime of electrons in the ring current by 2-6 h can alter electric fields in the nightside ionosphere by up to 26%. The lifetime also strongly influenced the location of the aurora, but the model generally produced aurora equatorward of observations.

  13. The effect of ring current electron scattering rates on M-I coupling

    NASA Astrophysics Data System (ADS)

    Perlongo, N. J.; Ridley, A. J.; Liemohn, M. W.; Katus, R. M.

    2016-12-01

    This simulation study investigates the electrodynamic impact of varying descriptions of the diffuse aurora on the magnetosphere-ionosphere (M-I) system. Pitch angle diffusion caused by waves in the inner magnetosphere is the primary source term for the diffuse aurora, especially during storm time. A number of empirical models have been developed to define the subsequent scattering rate of ring current electrons. This study investigates the magnetic local time (MLT) and storm dependent electrodynamic impacts of the diffuse aurora using a comparison between a self-consistent version of the hot electron ion drift integrator (HEIDI) with varying electron scattering rates and real geomagnetic storm events. The results are compared with multiple data sets including, but not limited to, Dst and hemispheric power indices, auroral electron flux, and electric field observations. Large differences in the systems response are shown between scattering rate descriptions.

  14. An unusual SAR arc observed during ring current development, 4 August 1972. [Stable Auroral Red

    NASA Technical Reports Server (NTRS)

    Shepherd, G. G.; Brace, L. H.; Burrows, J. R.; Hoffman, J. H.; Klumpar, D. M.; James, H. G.; Whitteker, J. H.; Nagy, A. F.; Stathopoulos, E.

    1980-01-01

    An unusual SAR arc observed during the growth phase of the ring current is described. Proton precipitation was observed, with electron temperature enhancements throughout the region, and an F-region trough present at the equatorward boundary; a high flux of low energy at the SAR arc location and a 'slot' in the ambient electron density are characteristic of this event. Comparisons are made with S3-A spacecraft observations made in the equatorial region at the same time and with Isis-II observations of a more normal SAR arc; the kinetic Alfven process described by Hasegawa and Mima (1978) appears to account for the acceleration of these low energy electrons, although an auroral-type acceleration process cannot be excluded.

  15. Energy content of stormtime ring current from phase space mapping simulations

    NASA Technical Reports Server (NTRS)

    Chen, Margaret W.; Schulz, Michael; Lyons, Larry R.

    1993-01-01

    We perform a phase space mapping study to estimate the enhancement in energy content that results from stormtime particle transport in the equatorial magnetosphere. Our pre-storm phase space distribution is based on a steady-state transport model. Using results from guiding-center simulations of ion transport during model storms having main phases of 3 hr, 6 hr, and 12 hr, we map phase space distributions of ring current protons from the pre-storm distribution in accordance with Liouville's theorem. We find that transport can account for the entire ten to twenty-fold increase in magnetospheric particle energy content typical of a major storm if a realistic stormtime enhancement of the phase space density f is imposed at the nightside tail plasma sheet (represented by an enhancement of f at the neutral line in our model).

  16. Quantifying the Contribution of keV-Energy Electrons to the Ring Current

    NASA Astrophysics Data System (ADS)

    Liemohn, Michael

    2010-05-01

    The Hot Electron and Ion Drift Integrator (HEIDI) inner magnetospheric drift physics model has recently been modified to include keV-energy electron scattering rates by VLF chorus and hiss waves, thus allowing for the calculation of the electron phase space distribution in the inner magnetosphere. Comparisons of calculated electron fluxes are made with low-Earth orbit electron precipitation data and dayside electron measurements to validate the scattering implementation procedure. Changes to the original scattering rate coefficients are made to take into account geomagnetic activity and plasmapause location. The electron ring current intensities and spatio-temporal evolution are compared against simulation results for the hot ion species. While the electron total energy content is typically 10 times smaller than the ion total energy content in the inner magnetosphere, it can be significantly higher than this during the main phase of magnetic storms.

  17. Ring currents in the porphyrins: pi shielding, delocalisation pathways and the central cation.

    PubMed

    Steiner, Erich; Soncini, Alessandro; Fowler, Patrick W

    2005-11-21

    It is shown that the ipsocentric orbital-based model explains how the charge of the central cation drives the delocalisation pathway in metalloporphyrins. A positive charge +Ze at the centre of the porphin ring gives rise to a two-way radial transfer of charge within the pi structure of the porphin macrocycle. This manifests itself in a change of pathway of the global pi current, as Z increases from Z = 0, from an inner- through a bifurcated- to an outer-pathway. Changes of pathway can be interpreted in terms of a specific pi shielding effect whereby electrons in high-lying pi orbitals are screened from the central charge by the electrons in lower-lying orbitals of the same symmetry. These changes in pi structure are essentially independent of accompanying changes in the sigma structure.

  18. Fits combining hyperon semileptonic decays, magnetic moments, and the conserved-vector-current hypothesis

    SciTech Connect

    Bohm, A.; Kielanowski, P.

    1983-06-01

    We have performed a test of the conserved-vector-current hypothesis (CVC) by determining the baryon charges and magnetic moments from the hyperon semileptonic data. Then CVC was applied in order to make a joint fit of all baryon semileptonic decay data and baryon magnetic moments for the spectrum-generating-group (SG) model as well as for the conventional (Cabibbo and magnetic moments in nuclear magnetons) model. The SG model gives a very good fit with chi/sup 2//n/sub D/ = 25/20/sup triangle-open//sub 21% C.L. whereas the conventional model gives a fit with chi/sup 2//n/sub D/approx. =244/20.

  19. Ion Temperatures in Earth's Inner Magnetosphere: Ring Current Dynamics, Transient Effects, and Data-Model Comparisons

    NASA Astrophysics Data System (ADS)

    Elfritz, Justin G.

    Earth's magnetosphere is an inherently complex, strongly nonlinear system with intrinsic coupling between internal and external drivers. In general, magnetospheric systems can be understood as a balance between multiple regions which all exhibit unique plasma properties. The feedback processes between each region depend on geomagnetic activity levels and the preceding states of the solar wind and the respective magnetospheric regions. Of particular interest is understanding how ion temperatures evolve during geomagnetically active periods, and also understanding the space weather impacts of hot ion populations injected during such periods. Dynamic, spatiotemporally resolved ion temperature boundary conditions have been implemented into the Comprehensive Ring Current Model (CRCM); the temperatures are based on 2-D equatorial maps derived from remotely imaged energetic neutral atom (ENA) measurements. The high-speed-stream-driven event on 22 July 2009 and the coronal mass ejection-driven event on 30-31 October 2013 are simulated and compared against identical simulations using a statistically derived boundary condition model. This new method for establishing boundary conditions allows users to include event-specific observations associated with a dynamic plasma sheet. It is found that spatial and energy distributions in the storm-time ring current exhibit sensitive dependence on boundary conditions during these events. The coupling of boundary conditions to the time history of the convection electric field strength is found to play an important role in throttling the influence of the boundary plasma on the inner magnetosphere. Storm-time dusk-dawn asymmetries consistent with observational data are reproduced well when CRCM is provided with the event-specific boundary condition model. The dependence of average, global magnetospheric ion temperatures derived from ENA maps is also investigated as a function of various combinations of solar wind parameters, IMF

  20. Comparisons of Simulated and Observed Stormtime Magnetic Intensities and Ion Plasma Parameters in the Ring Current

    NASA Astrophysics Data System (ADS)

    Chen, M. W.; Guild, T. B.; Lemon, C.; Roeder, J. L.; Le, G.; Schulz, M.

    2009-12-01

    Recent progress in ring current and plasma sheet modeling has shown the importance of a self-consistent treatment of particle transport and magnetic and electric fields in the inner magnetosphere. Models with and without self-consistency can lead to significantly different magnitudes and spatial distributions of plasma pressure and magnetic intensity during disturbed times. In this study we compare simulated and observed stormtime magnetic intensities (GOES and Polar/MFE) and ion densities (LANL/MPA and Polar/CAMMICE) to test how well self-consistent simulations can simultaneously reproduce these quantities. We simulate the ring current and plasma sheet for conditions corresponding to the 11 August 2000 storm using the self-consistent Rice Convection Model-Equilibrium (RCM-E) [Lemon et al., JGR, 2004] with a constant magnetopause location. Using the empirical IMF-dependent model of Tsyganenko and Mukai [JGR, 2003], we specify the plasma sheet pressure and density at 10 RE as the plasma boundary location in the RCM-E. The simulated ion densities at different magnetic local times agree fairly well with those from the re-analysis model of LANL/MPA densities of O’Brien and Lemon [Space Weather, 2007]. We compare the simulated magnetic intensity with the magnetic intensity measured by magnetometers on the GOES satellites at geosynchronous altitude (6.6 RE) and on the Polar satellite. Agreement between the simulated and observed magnetic intensities tends to agree better on the nightside than on the dayside in the inner magnetosphere. In particular, the model cannot account for observed drops in the dayside magnetic intensity during decreases in the solar wind pressure. We will modify the RCM-E to include a time-varying magnetopause location to simulate compressions and expansions associated with variations in the solar wind pressure. We investigate whether this will lead to improved agreement between the simulated and model magnetic intensities.

  1. Improvement of current limitation in the storage ring NIJI-IV

    SciTech Connect

    Yokoyama, M.; Kawai, M.; Hamada, S.

    1995-12-31

    The storage ring NIJI-IV dedicated to free-electron lasers was completed in December 1990. Lasing at 595-352 nm by using the NIJI-IV was accomplished by April 1994. The NIJI-IV has 16 rf-buckets. The electron bunch contributed to FEL gain of the NIJI-IV is only one of 16. In order to get the redundant bunch, make beam quality better, and make the FEL operation easier, a single bunch injection (SBI) system by using a short pulse beam from an electron gun was prepared. The quality of the beam accelerated and bunched by a buncher section has already been investigated. It was convinced that the accelerated short pulse beam satisfies the performance required on the SBI of the NIJI-IV. At present, the operation of the SBI system is being tested. Storage efficiency (the ratio of storage current to injection current) and limitation of storage current by using the SBI system will be reported in this conference. We expect lasing at below 352nm by the SBI.

  2. Current status of superallowed 0+ ->0+ nuclear β decay and the value of Vud

    NASA Astrophysics Data System (ADS)

    Hardy, J. C.; Towner, I. S.; Bencomo, M.; Iacob, V. E.; Park, H. I.; Chen, L.; Eronen, T.; Horvat, V.; Nica, N.

    2016-09-01

    Currently, the results from superallowed 0+ ->0+ nuclear β decays provide the most precise value for Vud, the up-down element of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix. According to the most recent critical survey of world data, the ft values for 14 of these superallowed transitions have been established to a precision of order 0.1% or better. These results, which cover a wide range of parent nuclei from 10C to 74Rb, constitute a very robust data set. After radiative and isospin-symmetry-breaking corrections have been applied, the resulting corrected Ft values are all consistent with one another, demonstrating agreement with conservation of the vector current (CVC). With CVC upheld, the Ft -value results can then be averaged to obtain a value for GV, the vector coupling constant, and for Vud. Since the last survey closed, new measurements have appeared, which do not significantly change the conclusions in but do reflect constructively on isospin symmetry breaking and on possible scalar currents. Up-to-date outcomes will be presented.

  3. Relative importance of ring and tail currents to Dst under extremely disturbed conditions

    NASA Astrophysics Data System (ADS)

    Kalegaev, V. V.; Makarenkov, E. V.

    2008-02-01

    Relative ring current (RC) and tail current (TC) contributions to Dst were investigated on the basis of the statistical study of 70 magnetic storms of different intensities. Special attention was paid to the extremely disturbed conditions during magnetic storms in October-November 2003. Variations of the magnetic field produced by magnetospheric currents on the Earth's surface were calculated using paraboloid model of the magnetosphere A2000 [Alexeev, I.I., Belenkaya, E.S., Kalegaev, V.V., Feldstein, Y.I., Grafe, A., 1996. Journal of Geophysical Research 101,7737; Alexeev, I.I., Kalegaev, V.V., Belenkaya, E.S., Bobrovnikov, S.Yu., Feldstein, Ya.I., Gromova, L.I., 2001. Journal of Geophysical Research 106, 25683], taking into account the effect of terrestrial induced currents. For each magnetic storm we calculated Dst and contributions produced by large-scale magnetospheric current systems. The relative RC and TC contributions for each event at the storm maximum were examined in relationship to the peak pressure-corrected Dst value. Analysis of Dst sources confirms the conclusions of Kalegaev and Ganushkina [2005. In: Pulkkinen, T., Tsyganenko, N.A., Friedel, R.H.W. (Eds.), Physics and Modeling of the Inner Magnetosphere, AGU Geophysical Monograph 155. AGU, Washington, DC, p. 293] and Kalegaev and Makarenkov [2006. Geomagnetism and Aeronomy 46, 570] about saturation of the TC effect under extremely disturbed conditions. The RC becomes the dominant Dst source during severe magnetic storms, but during moderate storms its contribution to Dst is comparable with TC's contribution. The RC injection amplitude increases with the growth of magnetospheric disturbance level.

  4. Stability of vortex rotation around a mesoscopic square superconducting ring under radially injected current and an external magnetic field.

    PubMed

    Xue, Cun; He, An; Li, Chun; Zhou, Youhe

    2017-04-05

    We present the stability of vortex rotation around a mesoscopic square superconducting ring under radially injected currents and external magnetic fields based on time-dependent Ginzburg-Landau equations. We demonstrate that the vortex rotation around a square ring can lead to voltage oscillations as the vortices periodically pass by the corners. The amplitude of the time evolution of the voltage oscillations as a function of external current is studied at different magnetic fields, and the effect of thermal noise on the voltage oscillations is discussed. The rotation frequency depends linearly on external current at lower magnetic fields, whereas it is a nonlinear function of external current at higher magnetic fields. The stable vortex rotation appears in a certain range of injected currents under magnetic fields, but it is unstable at high injected currents. It is found that such a transition from stability to instability can lead to an abrupt jump in current-voltage characteristics.

  5. The angular electronic band structure and free particle model of aromatic molecules: High-frequency photon-induced ring current

    NASA Astrophysics Data System (ADS)

    Öncan, Mehmet; Koç, Fatih; Şahin, Mehmet; Köksal, Koray

    2017-05-01

    This work introduces an analysis of the relationship of first-principles calculations based on DFT method with the results of free particle model for ring-shaped aromatic molecules. However, the main aim of the study is to reveal the angular electronic band structure of the ring-shaped molecules. As in the case of spherical molecules such as fullerene, it is possible to observe a parabolic dispersion of electronic states with the variation of angular quantum number in the planar ring-shaped molecules. This work also discusses the transition probabilities between the occupied and virtual states by analyzing the angular electronic band structure and the possibility of ring currents in the case of spin angular momentum (SAM) or orbital angular momentum (OAM) carrying light. Current study focuses on the benzene molecule to obtain its angular electronic band structure. The obtained electronic band structure can be considered as a useful tool to see the transition probabilities between the electronic states and possible contribution of the states to the ring currents. The photoinduced current due to the transfer of SAM into the benzene molecule has been investigated by using analytical calculations within the frame of time-dependent perturbation theory.

  6. τ-→η(')π-ντγ decays as background in the search for second class currents

    NASA Astrophysics Data System (ADS)

    Guevara, A.; López-Castro, G.; Roig, P.

    2017-03-01

    Observation of τ-→η(')π-ντ decays at Belle-II would indicate either a manifestation of isospin symmetry breaking or genuine second class current (SCC) effects. The corresponding radiative τ-→η(')π-ντγ decay channels are not suppressed by G -parity considerations and may represent a serious background in searches of SCCs in the former. We compute the observables associated to these radiative decays using resonance chiral Lagrangians and conclude that vetoing photons with Eγ>100 MeV should get rid of this background in the Belle-II environment while searching for the τ-→η π-ντ channel. Similar considerations hold inconclusive for decays involving the η', given the theory's uncertainties in the prediction of the τ-→η'π-ντ branching ratio. Still, additional kinematics-based cuts should be able to suppress this background in the η' case to a negligible level.

  7. The role of ring current particle injections: Global simulations and Van Allen Probes observations during 17 March 2013 storm

    NASA Astrophysics Data System (ADS)

    Yu, Yiqun; Jordanova, Vania; Welling, Dan; Larsen, Brian; Claudepierre, Seth G.; Kletzing, Craig

    2014-02-01

    We simulate substorm injections observed by the Van Allen Probes during the 17 March 2013 storm using a self-consistent coupling between the ring current model RAM-SCB and the global MHD model BATS-R-US. This is a significant advancement compared to previous studies that used artificially imposed electromagnetic field pulses to mimic substorm dipolarization and associated inductive electric field. Several substorm dipolarizations and injections are reproduced in the MHD model, in agreement with the timing of shape changes in the AE/AL index. The associated inductive electric field transports plasma sheet plasma to geostationary altitudes, providing the boundary plasma source to the ring current model. It is found that impulsive plasma sheet injections, together with a large-scale convection electric field, are necessary to develop a strong ring current. Comparisons with Van Allen Probes observations show that our model reasonably well captures dispersed electron injections and the global Dst index.

  8. Energy dynamics and current sheet structure in fluid and kinetic simulations of decaying magnetohydrodynamic turbulence

    SciTech Connect

    Makwana, K. D.; Zhdankin, V.; Li, H.; Daughton, W.; Cattaneo, F.

    2015-04-10

    We performed simulations of decaying magnetohydrodynamic (MHD) turbulence with a fluid and a kinetic code. The initial condition is an ensemble of long-wavelength, counter-propagating, shear-Alfvén waves, which interact and rapidly generate strong MHD turbulence. The total energy is conserved and the rate of turbulent energy decay is very similar in both codes, although the fluid code has numerical dissipation, whereas the kinetic code has kinetic dissipation. The inertial range power spectrum index is similar in both the codes. The fluid code shows a perpendicular wavenumber spectral slope of k-1.3⊥k⊥-1.3. The kinetic code shows a spectral slope of k-1.5⊥k⊥-1.5 for smaller simulation domain, and k-1.3⊥k⊥-1.3 for larger domain. We then estimate that collisionless damping mechanisms in the kinetic code can account for the dissipation of the observed nonlinear energy cascade. Current sheets are geometrically characterized. Their lengths and widths are in good agreement between the two codes. The length scales linearly with the driving scale of the turbulence. In the fluid code, their thickness is determined by the grid resolution as there is no explicit diffusivity. In the kinetic code, their thickness is very close to the skin-depth, irrespective of the grid resolution. Finally, this work shows that kinetic codes can reproduce the MHD inertial range dynamics at large scales, while at the same time capturing important kinetic physics at small scales.

  9. Energy dynamics and current sheet structure in fluid and kinetic simulations of decaying magnetohydrodynamic turbulence

    DOE PAGES

    Makwana, K. D.; Zhdankin, V.; Li, H.; ...

    2015-04-10

    We performed simulations of decaying magnetohydrodynamic (MHD) turbulence with a fluid and a kinetic code. The initial condition is an ensemble of long-wavelength, counter-propagating, shear-Alfvén waves, which interact and rapidly generate strong MHD turbulence. The total energy is conserved and the rate of turbulent energy decay is very similar in both codes, although the fluid code has numerical dissipation, whereas the kinetic code has kinetic dissipation. The inertial range power spectrum index is similar in both the codes. The fluid code shows a perpendicular wavenumber spectral slope of k-1.3⊥k⊥-1.3. The kinetic code shows a spectral slope of k-1.5⊥k⊥-1.5 for smallermore » simulation domain, and k-1.3⊥k⊥-1.3 for larger domain. We then estimate that collisionless damping mechanisms in the kinetic code can account for the dissipation of the observed nonlinear energy cascade. Current sheets are geometrically characterized. Their lengths and widths are in good agreement between the two codes. The length scales linearly with the driving scale of the turbulence. In the fluid code, their thickness is determined by the grid resolution as there is no explicit diffusivity. In the kinetic code, their thickness is very close to the skin-depth, irrespective of the grid resolution. Finally, this work shows that kinetic codes can reproduce the MHD inertial range dynamics at large scales, while at the same time capturing important kinetic physics at small scales.« less

  10. Particle pressure, inertial force and ring current density in the magnetosphere of Saturn

    NASA Astrophysics Data System (ADS)

    Sergis, Nick; Krimigis, Stamatios; Arridge, Christopher; Roelof, Edmond; Rymer, Abigail; Mitchell, Donald; Thomsen, Michelle; Kivelson, Margaret; Ramer, Kate; Hamilton, Douglas; Krupp, Norbert; Dougherty, Michele; Coates, Andrew; Young, David

    2010-05-01

    We present the most recent radial profiles for the thermal plasma, energetic particle and magnetic field pressures in the equatorial magnetosphere of Saturn, as measured by the MIMI, CAPS and MAG instruments of Cassini, currently orbiting Saturn. Data were obtained between September 2005 and May 2006, when the spacecraft was particularly close (±0.5 RS) to the nominal magnetic equator in the range 6 to 15 RS. The radial gradient of the total pressure is compared to the inertial body force and an average radial profile of the azimuthal current intensity is presented. The results show that: (1) The suprathermal (keV) pressure contribution to the total particle pressure becomes significant outside 8-9 RS, exceeding 50% for r>12 RS. (2) The plasma beta remains above 1 outside 8 RS, reaching ~3 to ~10 between 11 and 14 RS. (3) The inertial body force and the radial pressure gradient are similar at 9-10 RS, with the pressure gradient prevailing beyond 11 RS. (4) The ring current develops a maximum between ~8 and 12 RS, reaching values of 100-150 pA/m2, and is primarily inertial inside of 8.5 RS but increasingly pressure gradient-driven in its maximum region and beyond. Farther away, it drops with radial distance much faster than the 1/r rate that several disk current models assume. The distribution of various plasma and energetic particle parameters in SLS phase is also examined in connection with the observed periodicity in the radial and azimuthal components of the magnetic field.

  11. Intergrain and intragrain currents in bulk melt-grown YBa2Cu3O7-δ rings

    NASA Astrophysics Data System (ADS)

    Surzhenko, A. B.; Zeisberger, M.; Habisreuther, T.; Gawalek, W.; Uspenskaya, L. S.

    2003-08-01

    A simple contactless method suitable for discerning between the intergrain (circular) current, which flows in the thin superconducting ring, and the intragrain current, which does not cross the weakest link, has been proposed. At first, we show that the intergrain current may directly be estimated from the magnetic flux density B(±z0) measured by the Hall sensor positioned in the special points ±z0 above or below the ring center. The experimental and numerical techniques to determine the value z0 are discussed. Being very promising for the characterization of a current flowing across the joints in welded YBaCuO rings (its dependences on the temperature and external magnetic field as well as the time dissipation), the approach has been applied to study the corresponding properties of the intragrain and intergrain currents flowing across the a-twisted grain boundaries which are frequent in bulk melt-textured (MT) YBaCuO samples. We present experimental data related to the flux penetration inside a bore of MT YBaCuO rings both in the nonmagnetized, virgin state, and during the field reversal. The shielding properties and their dependence on external magnetic fields are also studied. Besides, we consider flux creep effects and their influence on the current redistribution during a dwell.

  12. Stability of vortex rotation around a mesoscopic square superconducting ring under radially injected current and an external magnetic field

    NASA Astrophysics Data System (ADS)

    Xue, Cun; He, An; Li, Chun; Zhou, Youhe

    2017-04-01

    We present the stability of vortex rotation around a mesoscopic square superconducting ring under radially injected currents and external magnetic fields based on time-dependent Ginzburg–Landau equations. We demonstrate that the vortex rotation around a square ring can lead to voltage oscillations as the vortices periodically pass by the corners. The amplitude of the time evolution of the voltage oscillations as a function of external current is studied at different magnetic fields, and the effect of thermal noise on the voltage oscillations is discussed. The rotation frequency depends linearly on external current at lower magnetic fields, whereas it is a nonlinear function of external current at higher magnetic fields. The stable vortex rotation appears in a certain range of injected currents under magnetic fields, but it is unstable at high injected currents. It is found that such a transition from stability to instability can lead to an abrupt jump in current–voltage characteristics.

  13. Stormtime ring current and radiation belt ion transport: Simulations and interpretations

    NASA Technical Reports Server (NTRS)

    Lyons, Larry R.; Gorney, David J.; Chen, Margaret W.; Schulz, Michael

    1995-01-01

    We use a dynamical guiding-center model to investigate the stormtime transport of ring current and radiation-belt ions. We trace the motion of representative ions' guiding centers in response to model substorm-associated impulses in the convection electric field for a range of ion energies. Our simple magnetospheric model allows us to compare our numerical results quantitatively with analytical descriptions of particle transport, (e.g., with the quasilinear theory of radial diffusion). We find that 10-145-keV ions gain access to L approximately 3, where they can form the stormtime ring current, mainly from outside the (trapping) region in which particles execute closed drift paths. Conversely, the transport of higher-energy ions (approximately greater than 145 keV at L approximately 3) turns out to resemble radial diffusion. The quasilinear diffusion coefficient calculated for our model storm does not vary smoothly with particle energy, since our impulses occur at specific (although randomly determined) times. Despite the spectral irregularity, quasilinear theory provides a surprisingly accurate description of the transport process for approximately greater than 145-keV ions, even for the case of an individual storm. For 4 different realizations of our model storm, the geometric mean discrepancies between diffusion coefficients D(sup sim, sub LL) obtained from the simulations and the quasilinear diffusion coefficient D(sup ql, sub LL) amount to factors of 2.3, 2.3, 1.5, and 3.0, respectively. We have found that these discrepancies between D(sup sim, sub LL) and D(sup ql, sub LL) can be reduced slightly by invoking drift-resonance broadening to smooth out the sharp minima and maxima in D(sup ql, sub LL). The mean of the remaining discrepancies between D(sup sim, sub LL) and D(sup ql, sub LL) for the 4 different storms then amount to factors of 1.9, 2.1, 1.5, and 2.7, respectively. We find even better agreement when we reduce the impulse amplitudes systematically in

  14. Cluster Observations of Channels of Enhanced Convection Velocity in the Ring Current Region

    NASA Astrophysics Data System (ADS)

    Puhl-Quinn, P. A.; Foerster, M.; Labelle, J.; Linder, J.; Matsui, H.; Treumann, R.

    2003-12-01

    For decades, spacecraft-borne instruments have detected enhanced convection features in the duskside and premidnight subauroral region, variously known as polarization jet [Galperin et al., 1973] or subauroral ion drifts (SAID) [Spiro et al., 1979]. We report Cluster observations of this phenomenon, detected with the electron drift instrument (EDI) which uses a novel particle-detection method to measure electric fields in the plane perpendicular to the magnetic field. We have identified enhanced convection velocity striations within the dusk-side ring current region. Such striations with durations 1-5 minutes were observed in AMPTE/IRM data [LaBelle et al., 1988] and also may be the source of fine features observed recently in ground-based radar observations of SAID [Erickson et al., 2002]. Cluster, due to its more polar orbit, finds them on time scales of tens of minutes implying that the channels are extended along magnetic flux tubes. A survey of Cluster/EDI data from February, 2001 until July, 2003 was performed, using data from 14 to 24 hours local time, from 60-69 degrees invariant latitude, and for Kp > 4. Enhanced electric fields were defined as those in the anti-corotation direction (westward) with amplitude exceeding twice the corotation speed. The data show a tendency for the enhanced electric fields to occur at lower latitudes in premidnight/midnight local time than on the duskside, consistent with previous observations. Many previous observations report widths as narrow as 0.1 degrees for SAID events, and for example the 1-5 minute crossing times at IRM imply striation widths on the order of 1000-2000 km. The variable separations of the Cluster spacecraft over the multi-year data set provides a unique opportunity to improve the determination of this width. In this paper, we elaborate about statistical properties, theoretical implications, and association with the SAPS (sub-auroral polarization streams) and SAID phenomena. Erickson, P.J., et al

  15. Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials.

    PubMed

    Liu, Chao; Schauff, Joseph; Lee, Seokhyeong; Cho, Jeong-Hyun

    2017-03-23

    Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR is not affected by environmental characteristics such as the temperature and pressure surrounding the resonator. Electromagnetic radiation in THz frequencies is biocompatible, which is a critical condition especially for the application of the biomolecular sensing. However, the quality factor (Q-factor) and frequency responses of traditional thin-film based split ring resonator (SRR) MMs are very low, which limits their sensitivities and selectivity as sensors. In this work, novel nanopillar-based SRR MMs, utilizing displacement current, are designed to enhance the Q-factor up to 450, which is around 45 times higher than that of traditional thin-film-based MMs. In addition to the enhanced Q-factor, the nanopillar-based MMs induce a larger frequency shifts (17 times compared to the shift obtained by the traditional thin-film based MMs). Because of the significantly enhanced Q-factors and frequency shifts as well as the property of biocompatible radiation, the THz nanopillar-based SRR are ideal MMs for the development of biomolecular sensors with high sensitivity and selectivity without inducing damage or distortion to biomaterials. A novel fabrication process has been demonstrated to build the nanopillar-based SRRs for displacement current mediated THz MMs. A two-step gold (Au) electroplating process and an atomic layer deposition (ALD) process are used to create sub-10 nm scale gaps between Au nanopillars. Since the ALD process is a conformal coating process, a uniform aluminum oxide (Al2O3) layer with nanometer-scale thickness can be achieved. By sequentially electroplating another Au thin film to fill the spaces between Al2O3 and Au, a close-packed Au-Al2O3-Au structure with nano-scale Al2O3 gaps can be fabricated. The size of the nano-gaps can be well defined by precisely controlling the deposition cycles of the

  16. Spectral and polarization characteristics of the nonspherically decaying radiation generated by polarization currents with superluminally rotating distribution patterns.

    PubMed

    Ardavan, Houshang; Ardavan, Arzhang; Singleton, John

    2004-05-01

    We present a theoretical study of the emission from a superluminal polarization current whose distribution pattern rotates (with an angular frequency omega) and oscillates (with a frequency Omega) at the same time and that comprises both poloidal and toroidal components. This type of polarization current is found in recent practical machines designed to investigate superluminal emission. We find that the superluminal motion of the distribution pattern of the emitting current generates localized electromagnetic waves that do not decay spherically, i.e., that do not have an intensity diminishing as RP(-2) with the distance RP from their source. The nonspherical decay of the focused wave packets that are emitted by the polarization currents does not contravene conservation of energy: The constructive interference of the constituent waves of such propagating caustics takes place within different solid angles on spheres of different radii (RP) centered on the source. For a polarization current whose longitudinal distribution (over an azimuthal interval of length 2pi) consists of m cycles of a sinusoidal wave train, the nonspherically decaying part of the emitted radiation contains the frequencies Omega +/- momega; i.e., it contains only the frequencies involved in the creation and implementation of the source. This is in contrast to recent studies of the spherically decaying emission, which was shown to contain much higher frequencies. The polarization of the emitted radiation is found to be linear for most configurations of the source.

  17. Magnetic field structure of Saturn's dayside magnetosphere and its mapping to the ionosphere: Results from ring current modeling

    NASA Astrophysics Data System (ADS)

    Bunce, E. J.; Arridge, C. S.; Cowley, S. W. H.; Dougherty, M. K.

    2008-02-01

    Ring current modeling in Saturn's magnetosphere using Pioneer-11, Voyager, and Cassini data has shown that the size and strength of the current system grows with the extension of the magnetosphere, governed by the solar wind dynamic pressure. Here we show that the consequent middle magnetosphere field is quasi-dipolar in form when the magnetosphere is strongly compressed, but extends into a magnetodisc when it is strongly expanded. We also show that the region occupied by the modeled ring current corresponds to an essentially fixed shell of field lines that expands and contracts with the size of the system, thus mapping to an almost fixed co-latitude range in Saturn's ionosphere, between ~14° and ~20° in the northern hemisphere, and ~16° and ~22° in the southern hemisphere. The median dayside UV auroral oval is found to map from near the poleward edge of the modeled ring current toward the boundary of open field lines at smaller co-latitudes. In the equatorial plane this corresponds to a layer ~2-5 Saturn radius wide (depending on magnetosphere size), extending from near the outer edge of the ring current to the vicinity of the magnetopause.

  18. Search for flavor changing neutral currents in top quark decays in pp collisions at 7 TeV

    NASA Astrophysics Data System (ADS)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Aguilo, E.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hammer, J.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knünz, V.; Krammer, M.; Liko, D.; Mikulec, I.; Pernicka, M.; Rahbaran, B.; Rohringer, C.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Taurok, A.; Wagner, P.; Waltenberger, W.; Walzel, G.; Widl, E.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Bansal, S.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Luyckx, S.; Mucibello, L.; Ochesanu, S.; Roland, B.; Rougny, R.; Selvaggi, M.; Staykova, Z.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Gonzalez Suarez, R.; Kalogeropoulos, A.; Maes, M.; Olbrechts, A.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Clerbaux, B.; De Lentdecker, G.; Dero, V.; Gay, A. P. R.; Hreus, T.; Léonard, A.; Marage, P. E.; Reis, T.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Adler, V.; Beernaert, K.; Cimmino, A.; Costantini, S.; Garcia, G.; Grunewald, M.; Klein, B.; Lellouch, J.; Marinov, A.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Verwilligen, P.; Walsh, S.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Bruno, G.; Castello, R.; Ceard, L.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Lemaitre, V.; Liao, J.; Militaru, O.; Nuttens, C.; Pagano, D.; Pin, A.; Piotrzkowski, K.; Schul, N.; Vizan Garcia, J. M.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Alves, G. A.; Correa Martins Junior, M.; De Jesus Damiao, D.; Martins, T.; Pol, M. E.; Souza, M. H. G.; Aldá Júnior, W. L.; Carvalho, W.; Custódio, A.; Da Costa, E. M.; De Oliveira Martins, C.; Fonseca De Souza, S.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Oguri, V.; Prado Da Silva, W. L.; Santoro, A.; Soares Jorge, L.; Sznajder, A.; Bernardes, C. A.; Dias, F. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Lagana, C.; Marinho, F.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Genchev, V.; Iaydjiev, P.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Tcholakov, V.; Trayanov, R.; Vutova, M.; Dimitrov, A.; Hadjiiska, R.; Kozhuharov, V.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Jiang, C. H.; Liang, D.; Liang, S.; Meng, X.; Tao, J.; Wang, J.; Wang, X.; Wang, Z.; Xiao, H.; Xu, M.; Zang, J.; Zhang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Guo, S.; Guo, Y.; Li, W.; Liu, S.; Mao, Y.; Qian, S. J.; Teng, H.; Wang, D.; Zhang, L.; Zhu, B.; Zou, W.; Avila, C.; Gomez, J. P.; Gomez Moreno, B.; Osorio Oliveros, A. F.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Plestina, R.; Polic, D.; Puljak, I.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Duric, S.; Kadija, K.; Luetic, J.; Morovic, S.; Attikis, A.; Galanti, M.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Finger, M.; Finger, M.; Assran, Y.; Elgammal, S.; Ellithi Kamel, A.; Khalil, S.; Mahmoud, M. A.; Radi, A.; Kadastik, M.; Müntel, M.; Raidal, M.; Rebane, L.; Tiko, A.; Eerola, P.; Fedi, G.; Voutilainen, M.; Härkönen, J.; Heikkinen, A.; Karimäki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Ungaro, D.; Wendland, L.; Banzuzi, K.; Karjalainen, A.; Korpela, A.; Tuuva, T.; Besancon, M.; Choudhury, S.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Millischer, L.; Nayak, A.; Rander, J.; Rosowsky, A.; Shreyber, I.; Titov, M.; Baffioni, S.; Beaudette, F.; Benhabib, L.; Bianchini, L.; Bluj, M.; Broutin, C.; Busson, P.; Charlot, C.; Daci, N.; Dahms, T.; Dobrzynski, L.; Granier de Cassagnac, R.; Haguenauer, M.; Miné, P.; Mironov, C.; Nguyen, M.; Ochando, C.; Paganini, P.; Sabes, D.; Salerno, R.; Sirois, Y.; Veelken, C.; Zabi, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bodin, D.; Brom, J.-M.; Cardaci, M.; Chabert, E. C.; Collard, C.; Conte, E.; Drouhin, F.; Ferro, C.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Juillot, P.; Le Bihan, A.-C.; Van Hove, P.; Fassi, F.; Mercier, D.; Beauceron, S.; Beaupere, N.; Bondu, O.; Boudoul, G.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Kurca, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Sordini, V.; Tosi, S.; Tschudi, Y.; Verdier, P.; Viret, S.; Tsamalaidze, Z.; Anagnostou, G.; Beranek, S.; Edelhoff, M.; Feld, L.; Heracleous, N.; Hindrichs, O.; Jussen, R.; Klein, K.; Merz, J.; Ostapchuk, A.; Perieanu, A.; Raupach, F.; Sammet, J.; Schael, S.

    2013-01-01

    The results of a search for flavor changing neutral currents in top quark decays t → Zq in events with a topology compatible with the decay chain ttbar → Wb + Zq → ℓνb + ℓℓq are presented. The search is performed with a data sample corresponding to an integrated luminosity of 5.0fb-1 of proton-proton collisions at a center-of-mass energy of 7 TeV, collected with the CMS detector at the LHC. The observed number of events agrees with the standard model prediction and no evidence for flavor changing neutral currents in top quark decays is found. A t → Zq branching fraction greater than 0.21% is excluded at the 95% confidence level.

  19. Collision of a loop current anticyclonic ring against the continental shelf slope of the western Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Vidal, VíCtor M. V.; Vidal, Francisco V.; PéRez-Molero, José M.

    1992-02-01

    A Loop Current anticyclonic ring ˜330 km in diameter and extending to a depth of >1500 m was observed to collide in January of 1984 against the continental shelf slope of the western Gulf of Mexico between 21.5° and 23°N. The collision occurred precisely at the time we conducted our Argos 84-1 hydrographic cruise in the western gulf (26°00' to 19°20'N) aboard the R/V Justo Sierra. The Caribbean Subtropical Underwater (SUW) was used as a tracer to identify the Loop Current anticyclonic ring within the western gulf. The collision was identified from temperature and salinity distributions and from the dynamic topography distribution relative to 500 m. The ring's collision zone was identified by the presence of a horizontal baroclinic flow divergence, to the east of Tamiahua, that divides the surface circulation into northward and southward baroclinic currents parallel to the western gulf's continental shelf break, with speeds of 85 and 32 cm s-1, respectively. Horizontal divergence and vertical convergence (ring asymmetries) resulted at the focus of the anticyclonic ring's collision and originated the alongshore self advection and northward translation of the colliding anticyclone. Upon colliding the anticyclonic ring shed approximately one third of its volume (˜2 × 104 km3), mass, and transferred angular momentum to the south flanking water mass, thus generating a cyclonic ring to the south of the collision zone. The observed alongshelf southward current results from mass conservation and volume continuity requirements associated with the anticyclonic ring's volume shedding and most probably constitutes the colliding ring's potential vorticity conservation mechanism. The weakening of the anticyclonic ring's relative vorticity due to the collision is most likely made up by gain of vorticity from lateral shear in the northward and southward current jets parallel to the continental shelf break. The core of both the anticyclonic and cyclonic rings had typical SUW

  20. Understanding the Dynamics of the Coupled Ring Current Radiation Belt System Using 4D VERB Simulations

    NASA Astrophysics Data System (ADS)

    Shprits, Y.; Kellerman, A. C.; Drozdov, A.; Orlova, K.; Spasojevic, M.

    2014-12-01

    Predicting and understanding the non-linear response of different electron populations in the inner magnetosphere, including ring current and higher energy radiation belts, has been a grand challenge since the beginning of the space age. During this past decade, there have been a number of long-term simulations that used lower energy boundary condition observations around geosynchronous orbit. In this study, we set up observations at around 15 RE and study how the combined convective-diffusive transport can result in the acceleration of keV to relativistic and ultra-relativistic energies. We show that while lower energy radial transport is dominated by the convection, higher energy transport is dominated by the diffusive radial transport. MLT dependent diffusion confidents allow us to study how difference in wave properties at different MLT can influence the dynamics of the particles. Inclusion of adiabatic changes also allows us to study the radial transport that results from pitch-angle scattering and adiabatic changes. We also show that there exists an intermediate range of energies for electrons for which both processes work simultaneously. We show the comparison of the 4D VERB simulations with the Van Allen Probes measurements.

  1. Comparative investigation of the energetic ion spectra comprising the magnetospheric ring currents of the solar system.

    PubMed

    Mauk, B H

    2014-12-01

    Investigated here are factors that control the intensities and shapes of energetic ion spectra that make up the ring current populations of the strongly magnetized planets of the solar system, specifically those of Earth, Jupiter, Saturn, Uranus, and Neptune. Following a previous and similar comparative investigation of radiation belt electrons, we here turn our attention to ions. Specifically, we examine the possible role of the differential ion Kennel-Petschek limit, as moderated by Electromagnetic Ion Cyclotron (EMIC) waves, as a standard for comparing the most intense ion spectra within the strongly magnetized planetary magnetospheres. In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate. Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV. We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process. The ion spectra of Saturn, Uranus, and Neptune reside far below their respective limits and are likely limited by interactions with gas and dust (Saturn) and by the absence of robust ion acceleration processes (Uranus and Neptune). Suggestions are provided for further testing the efficacy of the differential Kennel-Petschek limit for ions using the Van Allen Probes.

  2. Understanding the Dynamical Evolution of the Earth Radiation Belt and Ring Current Coupled System

    NASA Astrophysics Data System (ADS)

    Shprits, Yuri; Usanova, Maria; Kellerman, Adam; Drozdov, Alexander

    2016-07-01

    Modeling and understanding the ring current and radiation belt-coupled system has been a grand challenge since the beginning of the space age. In this study we show long-term simulations with a 3D Versatile Electron Radiation Belt (VERB) code of modeling the radiation belts with boundary conditions derived from observations around geosynchronous orbit. Simulations can reproduce long term variations of the electron radiation belt fluxes and show the importance of local acceleration, radial diffusion, loss to the atmosphere and loss to the magnetopause. We also present 4D VERB simulations that include convective transport, radial diffusion, pitch angle scattering and local acceleration. VERB simulations show that the lower energy inward transport is dominated by the convection and higher energy transport is dominated by the diffusive radial transport. We also show that at energies of 100s of keV, a number of processes work simultaneously, including convective transport, radial diffusion, local acceleration, loss to the loss cone and loss to the magnetopause. The results of the simulation of the March 2013 storm are compared with Van Allen Probes observations.

  3. Extreme Ring Current Proton Spectra Measured by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Summers, D.; Shi, R.; Manweiler, J. W.; Mitchell, D. G.; Lanzerotti, L. J.

    2016-12-01

    We analyze proton spectra measured by the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) on board the Van Allen Probes over the energy range 50 - 600 keV for L-shells , 3 < L < 6 . Three magnetic storm periods are considered,namely,March 17 - 20, 2013; February 18 - 22, 2014; and March 17 - 20, 2015. We consider the most intense proton spectra over these storm periods. Recent progress has been achieved in modeling the limitation of energetic ring current ion spectra resulting from the action of pitch-angle scattering by electromagnetic ion cyclotron (EMIC)waves. According to this theory,the limiting (extreme) spectrum is achieved when the EMIC waves acquire a certain gain over a given convective length scale for all frequencies over which wave growth occurs. The limiting spectrum is determined by numerically solving a standard integral equation. By comparing the observed extreme proton spectra with the corresponding numerical limiting spectra ,we find plausible evidence that the extreme spectra are controlled by EMIC wave scattering. Further work is required to compare measured extreme particle spectra with the theoretical limiting solutions over a wider range of events and varying geomagnetic conditions.

  4. VLF-emissions from ring current electrons. An interpretation of the band of missing emissions

    NASA Technical Reports Server (NTRS)

    Maeda, K.; Smith, P. H.; Anderson, R. R.

    1976-01-01

    VLF-emissions associated with the enhancement of ring current electrons during magnetic storms and substorms which were detected by the equatorially orbiting S-A satellite (Explorer 45) are described. The emissions observed near the geomagnetic equator consist of essentially two frequency regimes, i.e., one above the electron gyrofrequency, f sub H at the equator and the other below f sub H. This is indicated as a part of the wide-band data obtained during the main phase of the December 17, 1971 magnetic storm. The upper figure is the ac-magnetic field data measured by the search-coil magnetometer with the upper cutoff of 3kHz and the lower figure is the ac-electric field data obtained by the electric field sensor with the upper cutoff of 10kHz. These figures show the time sequence of the observed emissions along the inbound orbit (No. 101) of the satellite as f sub H changes approximately from 3 kHz at 20 UT to 6 kHz at 21 UT. The emissions above f sub H are electrostatic mode, which peak near the frequencies of (n + 1/2) f sub H where n is positive integer, and sometimes emissions up to n = 10 are observed. The emissions below f sub H are whistler mode, which have a conspicuous gap along exactly half electron gyrofrequency, f sub H/2.

  5. The Nonlinear Coupling of Electromagnetic Ion Cyclotron and Lower Hybrid Waves in the Ring Current Region

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.

    2004-01-01

    The excitation of lower hybrid waves (LHWs) is a widely discussed mechanism of interaction between plasma species in space, and is one of the unresolved questions of magnetospheric multi-ion plasmas. In this paper we present the morphology, dynamics, and level of LHW activity generated by electromagnetic ion cyclotron (EMIC) waves during the May 2-7, 1998 storm period on the global scale. The LHWs were calculated based on a newly developed self-consistent model (Khazanov et. al., 2002, 2003) that couples the system of two kinetic equations: one equation describes the ring current (RC) ion dynamic, and another equation describes the evolution of EMIC waves. It is found that the LHWs are excited by helium ions due to their mass dependent drift in the electric field of EMIC waves. The level of LHW activity is calculated assuming that the induced scattering process is the main saturation mechanism for these waves. The calculated LHWs electric fields are consistent with the observational data.

  6. SAR Arcs We Have Seen: Variability of Ring Current - Ionosphere Interactions

    NASA Astrophysics Data System (ADS)

    Baumgardner, J. L.; Wroten, J.; Mendillo, M.

    2015-12-01

    Starting in 1987, an all-sky airglow imaging system has operated from a site at the Millstone Hill/Haystack Observatory in Westford, MA. During the ~2½ solar cycles from 1987 to 2014, the most prominent storm-time optical feature observed from a sub-auroral site is a stable auroral red (SAR) arc. The standard use of a SAR arc's position is to locate the ionospheric footprint of the narrow plasmapause-ring current interaction region where heat conduction from the inner magnetosphere excites emission within the F-layer trough. When mapped from an emission altitude of 400 km to the geomagnetic equatorial plane, SAR arcs from Millstone Hill give the location of the plasmapause at radial distances between 2 to 4.5 earth radii. A total of 377 SAR arcs have been observed during the 27 years of imaging at Millstone Hill. A significant number of their morphologies departed from the stability in space and time implied by its name. We have classified these into five categories: longevity, multiplicity, zonal structure, latitudinal inhomogeneity, and tilt with respect to geomagnetic coordinates. In each case, the implications for the inner magnetosphere sources that drive SAR arcs are explored. Collectively, the variable nature of SAR arcs is documented systematically for the first time—an aspect of solar-terrestrial physics not yet addressed in either magnetosphere or ionosphere modeling studies.

  7. Ring Current Electrons in HEIDI and Their Relative Total Energy Content

    NASA Astrophysics Data System (ADS)

    Liemohn, M. W.

    2009-12-01

    The Hot Electron and Ion Drift Integrator (HEIDI) inner magnetospheric drift physics model has always had the capability of solving for the phase space density of keV-energy electrons. This aspect of the code, however, has not been utilized, largely because the results would have been totally unrealistic without the additional inclusion of VLF-chorus-induced pitch-angle scattering. Using the scattering rates of Chen et al. [JGR, 2005] for chorus wave interactions with keV electrons, new electron-only pitch-angle diffusion coefficients have been incorporated into HEIDI, allowing for an accurate solution of plasma sheet electron injection, transport, and loss. Initial results of electron transport calculations within HEIDI are presented and discussed. Of particular interest is the spatial configuration of the electron pressure within the inner magnetosphere and the total energy content of the electrons relative to the hot ions of the ring current. A set of idealized input scenarios are presented as well as a few real-event scenarios. Without the Chen et al. coefficients, the electron total energy content is nearly as large as the ion total energy content. With these losses, the ion energy content is five to ten times larger than the electron energy content.

  8. Superposed Epoch Analysis of Ring Current Geoeffectiveness Related to Solar Wind and Plasma Sheet Drivers

    NASA Technical Reports Server (NTRS)

    Liemohm, M. W.; Kozyra, J. U.; Thomsen, M. F.; Borovsky, J. E.; Gahurthakurta, Madulika (Technical Monitor)

    2004-01-01

    The goal of that proposal was to examine the relationship between solar wind drivers and ring current dynamics through data analysis and numerical simulations. The data analysis study was a statistical examination (via superposed epoch analyses) of a solar cycle's worth of storm data. Solar wind data, geophysical indices, and geosynchronous plasma data were collected for every time period with Dst< -50 nT from 1989 through 2002, and the storm list now exceeds 400 entries. This work was first conducted by a summer undergraduate student, Mr. John Vann (University of Kansas), with funding from the NSF Research Experience for Undergraduates program. It was then continued by a University of Michigan graduate student, Mr. Jichun Zhang. Mr. Zhang is now in his fourth year at U-M and is progressing very well toward a PhD in space science. His dissertation will be based on his data analysis and modeling efforts using this geomagnetic storm database. The results of the data analysis study have been the focus of several conference presentations, and the first manuscript has just been published. Two additional papers are presently being prepared, one on average (superposed) solar wind features for various storm subsets (e.g., intense storms at solar maximum), and another on geosynchronous plasma features for these same storm subsets. The latter result was highlighted by the TR&T program director in his presentation at the COSPAR meeting this summer.

  9. The ion energy spectra in the ring current during the geomagnetic storm of February 1986

    NASA Technical Reports Server (NTRS)

    Kistler, L. M.; Hamilton, D. C.; Ipavich, F. M.; Gloeckler, G.

    1989-01-01

    The largest geomagnetic storm in several decades occurred in February 1986, with a minimum Dst of -312 nT. In this experiment, the CHEM instrument on the AMPTE/CCE spacecraft has been used to study the development of this storm in more detail. By comparing measurements of phase space density (f) vs magnetic moment (mu) for four ion species H(+), O(+), He (+), and He(++) during consecutive passes through the ring current region, a distinction can be made between flux increases that require the injection of a new population and those that are consistent with the adiabatic acceleration of a pre-existing population. It is shown that the smaller flux observed during the outbound pass compared to the preceding inbound pass at the time of minimum Dst is due to the difference in local times of the two measurements. This local time difference is consistent with a greatly enhanced convection electric field, which brings a new population from the magnetotail to the post-noon, but not to pre-noon local time sector.

  10. A broad-band VLF-burst associated with ring-current electrons. [geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Maeda, K.

    1982-01-01

    Frequency band broadening takes place just outside of the nighttime plasmasphere, where the density of cold plasma is known to be very low during the later phase of a geomagnetic storm. Instead of the gradual broadening of several hours duration, a burst type broadening of VLF emission lasting less than ten minutes was observed by Explorer 45 in a similar location. The magnetic field component of this emission is very weak and the frequency spreads below the local half electron cyclotron frequency. Corresponding enhancement of the anisotropic ring current electrons is also very sudden and limited below the order of 10 keV without significant velocity dispersion, in contrast to the gradual broadening events. The cause of this type of emission band spreading can be attributed to the generation of the quasielectrostatic whistler mode emission of short wavelength by hot bimaxwellian electrons surging into the domain of relatively low density magnetized cold plasma. The lack of energy dispersion in the enhanced electrons indicates that the inner edge of the plasma sheet, the source of these hot electrons, is not far from the location of this event.

  11. Penetration of Solar Wind Driven ULF Waves into the Earth's Inner Magnetosphere: Role in Radiation Belt and Ring Current Dynamics

    NASA Astrophysics Data System (ADS)

    Mann, Ian; Murphy, Kyle; Rae, Jonathan; Ozeke, Louis; Milling, David

    2013-04-01

    Ultra-low frequency (ULF) waves in the Pc4-5 band can be excited in the magnetosphere by the solar wind. Much recent work has shown how ULF wave power is strongly correlated with solar wind speed. However, little attention has been paid the dynamics of ULF wave power penetration onto low L-shells in the inner magnetosphere. We use more than a solar cycle of ULF wave data, derived from ground-based magnetometer networks, to examine this ULF wave power penetration and its dependence on solar wind and geomagnetic activity indices. In time domain data, we show very clearly that dayside ULF wave power, spanning more than 4 orders of magnitude, follows solar wind speed variations throughout the whole solar cycle - during periods of sporadic solar maximum ICMEs, during declining phase fast solar wind streams, and at solar minimum, alike. We also show that time domain ULF wave power increases during magnetic storms activations, and significantly demonstrate that a deeper ULF wave power penetration into the inner magnetosphere occurs during larger negative excursions in Dst. We discuss potential explanations for this low-L ULF wave power penetration, including the role of plasma mass density (such as during plasmaspheric erosion), or ring current ion instabilities during near-Earth ring current penetration. Interestingly, we also show that both ULF wave power and SAMPEX MeV electron flux show a remarkable similarity in their penetration to low-L, which suggests that ULF wave power penetration may be important for understanding and explaining radiation belt dynamics. Moreover, the correlation of ULF wave power with Dst, which peaks at one day lag, suggests the ULF waves might also be important for the inward transport of ions into the ring current. Current ring current models, which exclude long period ULF wave transport, under-estimate the ring current during fast solar wind streams which is consistent with a potential role for ULF waves in ring current energisation. The

  12. Self-Consistent Model of Magnetospheric Ring Current and Electromagnetic Ion Cyclotron Waves: The 2-7 May 1998 Storm

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Jordanova, V. K.

    2003-01-01

    A complete description of a self-consistent model of magnetospheric ring current interacting with electromagnetic ion cyclotron waves is presented. The model is based on the system of two kinetic equations; one equation describes the ring current ion dynamics, and another equation describes the wave evolution. The effects on ring current ions interacting with electromagnetic ion cyclotron waves and back on waves are considered self-consistently by solving both equations on a global magnetospheric scale under nonsteady state conditions. The developed model is employed to simulate the entire 2-7 May 1998 storm period. First, the trapped number fluxes of the ring current protons are calculated and presented along with comparison with the data measured by the three- dimensional hot plasma instrument Polar/HYDRA. Incorporating in the model the wave-particle interaction leads to much better agreement between the experimental data and the model results. Second, examining of the wave (MLT, L shell) distributions produced by the model during the storm progress reveals an essential intensification of the wave emission about 2 days after the main phase of the storm. This result is well consistent with the earlier ground-based observations. Finally, the theoretical shapes and the occurrence rates of the wave power spectral densities are studied. It is found that about 2 days after the storm s main phase on 4 May, mainly non-Gaussian shapes of power spectral densities are produced.

  13. Modeling of Ring Current Energy Content and Magnetic Field During Storms: How Much Do the Results Depend on Model Choice?

    NASA Astrophysics Data System (ADS)

    Ganushkina, N. Y.; Liemohn, M. W.

    2009-12-01

    We use the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM) to trace particles from the plasma sheet to the inner magnetosphere regions and to study the ring current formation during storm times. The IMPTAM model follows drift of ions and electrons with arbitrary pitch angles in time-dependent magnetic and electric fields, assuming that 1st and 2nd adiabatic invariants are conserved. For two storms, one moderate on November 6-7, 1997 and one intense on October 21-23, 1999, we analyze the evolution of model ring current energy content and magnetic field depression produced by the modeled ring current at the Earth. We trace particles in several combinations of electric and magnetic field models such as dipole, Tsyganenko T89, Tsyganenko T96, Tsyganenko and Sitnov TS04 models for magnetic field and Volland-Stern, Boyle et al., and Weimer models for electric field. We also apply 4 different types of boundary distribution in the plasma sheet at different locations. We make model-to-model and model-to-Dst-observed comparisons. The questions to be answered are How much do the results of the storm-time ring current modeling depend on the choice of models and How accurate are the conclusions made from the modeling output?

  14. Self-Consistent Model of Magnetospheric Ring Current and Electromagnetic Ion Cyclotron Waves: The 2-7 May 1998 Storm

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Jordanova, V. K.

    2003-01-01

    A complete description of a self-consistent model of magnetospheric ring current interacting with electromagnetic ion cyclotron waves is presented. The model is based on the system of two kinetic equations; one equation describes the ring current ion dynamics, and another equation describes the wave evolution. The effects on ring current ions interacting with electromagnetic ion cyclotron waves and back on waves are considered self-consistently by solving both equations on a global magnetospheric scale under nonsteady state conditions. The developed model is employed to simulate the entire 2-7 May 1998 storm period. First, the trapped number fluxes of the ring current protons are calculated and presented along with comparison with the data measured by the three- dimensional hot plasma instrument Polar/HYDRA. Incorporating in the model the wave-particle interaction leads to much better agreement between the experimental data and the model results. Second, examining of the wave (MLT, L shell) distributions produced by the model during the storm progress reveals an essential intensification of the wave emission about 2 days after the main phase of the storm. This result is well consistent with the earlier ground-based observations. Finally, the theoretical shapes and the occurrence rates of the wave power spectral densities are studied. It is found that about 2 days after the storm s main phase on 4 May, mainly non-Gaussian shapes of power spectral densities are produced.

  15. Global modes in Saturn’s main rings. Theoretical background and current issues

    NASA Astrophysics Data System (ADS)

    Longaretti, Pierre-Yves

    2017-06-01

    The dynamics of dense ring systems may conveniently be divided into two main topics: local structures, mostly driven be local, incoherent instabilities (most prominently, self-gravitational wakes and local viscous overstabilities) and global structures, involving in particular non-axisymmetric features over the whole extent in azimuth. The latter include density and bending waves, global narrow ring modes and edge modes; these structures can be globally viscously overstable.All global modes have a common dynamical origin and can be described in a unified dynamical framework, which will be reviewed in the first part of the talk. In particular, all planar narrow ring modes and edge modes can be described as trapped density waves and theoretically investigated as a nonlinear eigenvalue problem.The second part of the talk will focus on salient problems, some of which were discovered and characterized during the Cassini mission. These include, e.g., the numerous edge modes observed at gap edges and narrow ring edges, the peculiar structure of the B ring edge and the alternating series of gaps and rings populating the Cassini division. The possible dynamical origin of these structures will be reviewed; if available at the time of the conference, new numerical simulations investigating the dynamics of the B ring edge will be presented.

  16. Odd-Even Effect of the Persistent Current in a Quantum Dot Ring with Embedded Majorana Bound States

    NASA Astrophysics Data System (ADS)

    Gong, Wei-Jiang; Zhao, Ying; Gao, Zhen; Yi, Guangyu; Zhang, Xin

    2015-02-01

    We investigate the persistent current in one mesoscopic ring formed by the couplings between the end dots of a quantum dot chain and one Majorana bound states (MBS). It is found that the persistent-current properties are dependent on the dot-number parity of the chain. When the dot number is odd, the persistent current emerges with its oscillation by tuning the magnetic flux in the ring. However, if the dot number is even, the persistent current will always be zero regardless of the presence of Majorana zero mode. By transforming the system Hamiltonian into the Majorana representation, all the results are analyzed in detail. We believe that these results provide new information for understanding the MBS-assisted electron motion property in the mesoscopic system.

  17. Charge and current neutralization in the formation of ion rings in a background plasma

    SciTech Connect

    Oliver, B.V.; Ryutov, D.D.; Sudan, R.N. )

    1994-10-01

    For typical field-reversed ion ring experiments, an intense ion beam is injected across a plasma-filled magnetic cusp and propagated into a solenoidal field downstream. The characteristic time [tau] satisfies 2[pi]/[Omega][sub [ital e

  18. Search for flavor-changing neutral current and Lepton-flavor violating decays of D0-->l+l-.

    PubMed

    Aubert, B; Barate, R; Boutigny, D; Couderc, F; Gaillard, J-M; Hicheur, A; Karyotakis, Y; Lees, J P; Tisserand, V; Zghiche, A; Palano, A; Pompili, A; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Borgland, A W; Breon, A B; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Day, C T; Gill, M S; Gritsan, A V; Groysman, Y; Jacobsen, R G; Kadel, R W; Kadyk, J; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lynch, G; Mir, L M; Oddone, P J; Orimoto, T J; Pripstein, M; Roe, N A; Ronan, M T; Shelkov, V G; Wenzel, W A; Barrett, M; Ford, K E; Harrison, T J; Hart, A J; Hawkes, C M; Morgan, S E; Watson, A T; Fritsch, M; Goetzen, K; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Steinke, M; Boyd, J T; Chevalier, N; Cottingham, W N; Kelly, M P; Latham, T E; Wilson, F F; Cuhadar-Donszelmann, T; Hearty, C; Knecht, N S; Mattison, T S; McKenna, J A; Thiessen, D; Khan, A; Kyberd, P; Teodorescu, L; Blinov, A E; Blinov, V E; Druzhinin, V P; Golubev, V B; Ivanchenko, V N; Kravchenko, E A; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Yushkov, A N; Best, D; Bruinsma, M; Chao, M; Eschrich, I; Kirkby, D; Lankford, A J; Mandelkern, M; Mommsen, R K; Roethel, W; Stoker, D P; Buchanan, C; Hartfiel, B L; Foulkes, S D; Gary, J W; Shen, B C; Wang, K; del Re, D; Hadavand, H K; Hill, E J; MacFarlane, D B; Paar, H P; Rahatlou, Sh; Sharma, V; Berryhill, J W; Campagnari, C; Dahmes, B; Long, O; Lu, A; Mazur, M A; Richman, J D; Verkerke, W; Beck, T W; Eisner, A M; Heusch, C A; Kroseberg, J; Lockman, W S; Nesom, G; Schalk, T; Schumm, B A; Seiden, A; Spradlin, P; Williams, D C; Wilson, M G; Albert, J; Chen, E; Dubois-Felsmann, G P; Dvoretskii, A; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Ryd, A; Samuel, A; Yang, S; Jayatilleke, S; Mancinelli, G; Meadows, B T; Sokoloff, M D; Abe, T; Blanc, F; Bloom, P; Chen, S; Ford, W T; Nauenberg, U; Olivas, A; Rankin, P; Smith, J G; Zhang, J; Zhang, L; Chen, A; Harton, J L; Soffer, A; Toki, W H; Wilson, R J; Zeng, Q; Altenburg, D; Brandt, T; Brose, J; Dickopp, M; Feltresi, E; Hauke, A; Lacker, H M; Müller-Pfefferkorn, R; Nogowski, R; Otto, S; Petzold, A; Schubert, J; Schubert, K R; Schwierz, R; Spaan, B; Sundermann, J E; Bernard, D; Bonneaud, G R; Brochard, F; Grenier, P; Schrenk, S; Thiebaux, Ch; Vasileiadis, G; Verderi, M; Bard, D J; Clark, P J; Lavin, D; Muheim, F; Playfer, S; Xie, Y; Andreotti, M; Azzolini, V; Bettoni, D; Bozzi, C; Calabrese, R; Cibinetto, G; Luppi, E; Negrini, M; Piemontese, L; Sarti, A; Treadwell, E; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Patteri, P; Peruzzi, I M; Piccolo, M; Zallo, A; Buzzo, A; Capra, R; Contri, R; Crosetti, G; Lo Vetere, M; Macri, M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Bailey, S; Brandenburg, G; Chaisanguanthum, K S; Morii, M; Won, E; Dubitzky, R S; Langenegger, U; Bhimji, W; Bowerman, D A; Dauncey, P D; Egede, U; Gaillard, J R; Morton, G W; Nash, J A; Nikolich, M B; Taylor, G P; Charles, M J; Grenier, G J; Mallik, U; Cochran, J; Crawley, H B; Lamsa, J; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Yi, J; Biasini, M; Covarelli, R; Pioppi, M; Davier, M; Giroux, X; Grosdidier, G; Höcker, A; Laplace, S; Le Diberder, F; Lepeltier, V; Lutz, A M; Petersen, T C; Plaszczynski, S; Schune, M H; Tantot, L; Wormser, G; Cheng, C H; Lange, D J; Simani, M C; Wright, D M; Bevan, A J; Chavez, C A; Coleman, J P; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; Hutchcroft, D E; Parry, R J; Payne, D J; Sloane, R J; Touramanis, C; Back, J J; Cormack, C M; Harrison, P F; Di Lodovico, F; Mohanty, G B; Brown, C L; Cowan, G; Flack, R L; Flaecher, H U; Green, M G; Jackson, P S; McMahon, T R; Ricciardi, S; Salvatore, F; Winter, M A; Brown, D; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Hart, P A; Hodgkinson, M C; Lafferty, G D; Lyon, A J; Williams, J C; Chen, C; Farbin, A; Hulsbergen, W D; Jawahery, A; Kovalskyi, D; Lae, C K; Lillard, V; Roberts, D A; Blaylock, G; Dallapiccola, C; Flood, K T; Hertzbach, S S; Kofler, R; Koptchev, V B; Moore, T B; Saremi, S; Staengle, H; Willocq, S; Cowan, R; Sciolla, G; Sekula, S J; Taylor, F; Yamamoto, R K; Mangeol, D J J; Patel, P M; Robertson, S H; Lazzaro, A; Lombardo, V; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Taras, P; Nicholson, H; Cavallo, N; Fabozzi, F; Gatto, C; Lista, L; Monorchio, D; Paolucci, P; Piccolo, D; Sciacca, C; Baak, M; Bulten, H; Raven, G; Snoek, H L; Wilden, L; Jessop, C P; Losecco, J M; Allmendinger, T; Gan, K K; Honscheid, K; Hufnagel, D; Kagan, H; Kass, R; Pulliam, T; Rahimi, A M; Ter-Antonyan, R; Wong, Q K; Brau, J; Frey, R; Igonkina, O; Potter, C T; Sinev, N B; Strom, D; Torrence, E; Colecchia, F; Dorigo, A; Galeazzi, F; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Tiozzo, G; Voci, C; Benayoun, M; Briand, H; Chauveau, J; David, P; de la Vaissière, Ch; Del Buono, L; Hamon, O; John, M J J; Leruste, Ph; Malcles, J; Ocariz, J; Pivk, M; Roos, L; T'jampens, S; Therin, G; Manfredi, P F; Re, V; Behera, P K; Gladney, L; Guo, Q H; Panetta, J; Angelini, C; Batignani, G; Bettarini, S; Bondioli, M; Bucci, F; Calderini, G; Carpinelli, M; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Martinez-Vidal, F; Morganti, M; Neri, N; Paoloni, E; Rama, M; Rizzo, G; Sandrelli, F; Walsh, J; Haire, M; Judd, D; Paick, K; Wagoner, D E; Danielson, N; Elmer, P; Lau, Y P; Lu, C; Miftakov, V; Olsen, J; Smith, A J S; Telnov, A V; Bellini, F; Cavoto, G; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Li Gioi, L; Mazzoni, M A; Morganti, S; Pierini, M; Piredda, G; Safai Tehrani, F; Voena, C; Christ, S; Wagner, G; Waldi, R; Adye, T; De Groot, N; Franek, B; Geddes, N I; Gopal, G P; Olaiya, E O; Aleksan, R; Emery, S; Gaidot, A; Ganzhur, S F; Giraud, P-F; Hamel de Monchenault, G; Kozanecki, W; Legendre, M; London, G W; Mayer, B; Schott, G; Vasseur, G; Yèche, Ch; Zito, M; Purohit, M V; Weidemann, A W; Wilson, J R; Yumiceva, F X; Aston, D; Bartoldus, R; Berger, N; Boyarski, A M; Buchmueller, O L; Claus, R; Convery, M R; Cristinziani, M; De Nardo, G; Dong, D; Dorfan, J; Dujmic, D; Dunwoodie, W; Elsen, E E; Fan, S; Field, R C; Glanzman, T; Gowdy, S J; Hadig, T; Halyo, V; Hast, C; Hryn'ova, T; Innes, W R; Kelsey, M H; Kim, P; Kocian, M L; Leith, D W G S; Libby, J; Luitz, S; Luth, V; Lynch, H L; Marsiske, H; Messner, R; Muller, D R; O'Grady, C P; Ozcan, V E; Perazzo, A; Perl, M; Petrak, S; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Simi, G; Snyder, A; Soha, A; Stelzer, J; Su, D; Sullivan, M K; Va'vra, J; Wagner, S R; Weaver, M; Weinstein, A J R; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Young, C C; Burchat, P R; Edwards, A J; Meyer, T I; Petersen, B A; Roat, C; Ahmed, S; Alam, M S; Ernst, J A; Saeed, M A; Saleem, M; Wappler, F R; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Kim, H; Ritchie, J L; Satpathy, A; Schwitters, R F; Izen, J M; Kitayama, I; Lou, X C; Ye, S; Bianchi, F; Bona, M; Gallo, F; Gamba, D; Bosisio, L; Cartaro, C; Cossutti, F; Della Ricca, G; Dittongo, S; Grancagnolo, S; Lanceri, L; Poropat, P; Vitale, L; Vuagnin, G; Panvini, R S; Banerjee, Sw; Brown, C M; Fortin, D; Jackson, P D; Kowalewski, R; Roney, J M; Sobie, R J; Band, H R; Cheng, B; Dasu, S; Datta, M; Eichenbaum, A M; Graham, M; Hollar, J J; Johnson, J R; Kutter, P E; Li, H; Liu, R; Mihalyi, A; Mohapatra, A K; Pan, Y; Prepost, R; Tan, P; von Wimmersperg-Toeller, J H; Wu, J; Wu, S L; Yu, Z; Greene, M G; Neal, H

    2004-11-05

    We report on a search for the flavor-changing neutral current decays D0-->e(+)e(-) and D0-->mu(+)mu(-), and the lepton-flavor violating decay D0-->e(+/-)mu(-/+). The measurement is based on 122 fb(-1) of data collected by the BABAR detector at the SLAC PEP-II asymmetric e(+)e(-) collider. No evidence is found for any of the decays. The upper limits on the branching fractions, at the 90% confidence level, are 1.2x10(-6) for D0-->e(+)e(-), 1.3x10(-6) for D0-->mu(+)mu(-), and 8.1x10(-7) for D0-->e(+/-)mu(-/+).

  19. Effect of Precipitating Electrons on Ring Current Energy Content, Ionospheric Conductance, and Thermospheric Properties

    NASA Astrophysics Data System (ADS)

    Chen, M.; Lemon, C. L.; Walterscheid, R. L.; Yoo, B.; Hecht, J. H.; Shprits, Y.; Orlova, K.; Schulz, M.; Evans, J. S.

    2014-12-01

    We investigate how scattering of electrons by waves in the plasma sheet and plasmasphere affects precipitating energy flux distributions during magnetic storms, how the precipitating electrons modify the ionospheric Hall and Pederson conductivity and electric potential, how these processes feedback on magnetospheric particle transport and redistribute the ring current, and how the ionization and energy deposition of precipitating electrons affects thermospheric winds and temperature. Our main approach is to couple simulation models: (1) the magnetically and electrically self-consistent Rice Convection Model - Equilibrium (RCM-E) of the inner magnetosphere, (2) the B3c transport model for electron-proton-hydrogen atom aurora in the ionosphere, and (3) the Thermosphere-Ionsphere-Electrodynamics General Circulation Model (TIEGCM) of the ionosphere and thermosphere. Realistic descriptions of electron pitch-angle diffusion by whistler chorus in the plasma sheet/magnetotail and hiss in the plasmasphere are included in the RCM-E. We use parameterized rates of electron pitch-angle scattering with whistler chorus of Orlova and Shprits [JGR, 2014] that depend on equatorial radial distance, magnetic activity (Kp), and magnetic local time. To study how the precipitating electron energy flux distributions affect ionospheric conductivity and ionospheric electric potential patterns, we have performed a one-way coupling of the RCM-E and ionospheric B3c model. The simulated precipitating electron flux distributions are used to specify the energy flux and particle heating due to precipitating auroral electrons for TIEGCM simulations of the neutral atmosphere. We simulate a storm event and compare simulated quantities with in situ observations.

  20. Comparative investigation of the energetic ion spectra comprising the magnetospheric ring currents of the solar system

    PubMed Central

    Mauk, B H

    2014-01-01

    Investigated here are factors that control the intensities and shapes of energetic ion spectra that make up the ring current populations of the strongly magnetized planets of the solar system, specifically those of Earth, Jupiter, Saturn, Uranus, and Neptune. Following a previous and similar comparative investigation of radiation belt electrons, we here turn our attention to ions. Specifically, we examine the possible role of the differential ion Kennel-Petschek limit, as moderated by Electromagnetic Ion Cyclotron (EMIC) waves, as a standard for comparing the most intense ion spectra within the strongly magnetized planetary magnetospheres. In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate. Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV. We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process. The ion spectra of Saturn, Uranus, and Neptune reside far below their respective limits and are likely limited by interactions with gas and dust (Saturn) and by the absence of robust ion acceleration processes (Uranus and Neptune). Suggestions are provided for further testing the efficacy of the differential Kennel-Petschek limit for ions using the Van Allen Probes. PMID:26167438

  1. Loop Current Ring Shedding: the Formation of Cyclones and the Effect of Topography.

    NASA Astrophysics Data System (ADS)

    Cherubin, L. M.; Morel, Y.; Chassignet, E. P.

    2005-05-01

    The formation of cyclones in the vicinity of the LC ring during the shedding process is analyzed in terms of vortex instability. Using a high resolution ECMWF-daily wind forced MICOM simulation, we show that cyclones are the products of a mixed barotropic-baroclinic vortex instability, which grows around the rim of the LC ring while it is attached to the LC. Cyclones contributes to the separation of the ring from the LC as they grow between them. The QG instability of the LC-like type `R` vortex shows that a mode 4 baroclinic instability is intensified in the deep layers of the ring while barotropic instability is surface intensified. The nonlinear state shows that a LC-like vortex is indeed a pentapole on an f-plane. On the β-plane, the northern cyclone is separated from the anticyclone by the β-effect and both drift westward. When the topography of the GOM is taken into account, namely the Campeche Bank, the southward slope north of the LC and the Florida shelf east of the LC, several effects are observed: (1) the northern corner of the Campeche Bank erodes the LC ring and its cyclones, and interacts with the vortex most unstable mode; (2) the northern southward slope scatters the northern cyclone while the anticyclone remain coherent and propagate to the west; (3) realistic westward propagation speeds are obtained in the presence of the northern Campeche shelf, which acts as a mirror effect on the LC ring as opposed to the Florida shelf, which tends to block the ring.

  2. Canonical orbital contributions to the magnetic fields induced by global and local diatropic and paratropic ring currents.

    PubMed

    Charistos, Nickolas D; Papadopoulos, Anastasios G; Nikopoulos, Thomas A; Muñoz-Castro, Alvaro; Sigalas, Michael P

    2017-11-15

    The induced magnetic field (IMF) of naphthalene, biphenyl, biphenylene, benzocyclobutadiene, and pentalene is dissected to contributions from the total π system, canonical π-molecular orbitals (CMO), and HOMO→π* excitations, to evaluate and interpret relative global and local diatropicity and paratropicity. Maps of the IMF of the total π system reveal its relative strength and topology that corresponds to global and local diatropic and paratropic ring currents. The total π magnetic response is determined by this of canonical HOMOs and particularly by paratropic contributions of rotational excitations from HOMOs to unoccupied π* orbitals. Low energy excitations and similar nodal structure of HOMO and π* induce strong paratropic fields that dominate on antiaromatic rings. High energy excitations and different nodal structures lead to weak paratropic contributions of canonical HOMOs, which are overwhelmed by diatropic response of lower energy canonical orbitals in aromatic rings. CMO-IMF analysis is found in agreement with ring current analysis. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  3. Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  4. Global Simulations of the March 17, 2013 Storm: Importance of Boundary Conditions in Reproducing Ring Current Observations

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Jordanova, V.; Larsen, B.; Claudepierre, S. G.; Welling, D. T.; Skoug, R. M.; Kletzing, C.

    2013-12-01

    As modeling capabilities become increasingly available for the study of inner magnetospheric dynamics, the models' boundary conditions remain a crucial controlling factor in reproducing observations. In this study, we use the kinetic Ring current-Atmosphere Interaction Model (RAM) two-way coupled with the global MHD model BATS-R-US to study the evolution of the ring current and its feedback to the ionospheric electrodynamics during the March 17, 2013 storm. The MHD code solves fluid quantities and provides the inner magnetosphere code with plasma sheet plasma, which is the primary source for the development of the ring current. In this study, we examine the effect of different boundary conditions in specifying the plasma sheet plasma source on reproducing observations of the inner magnetospheric/subauroral region, such as in-situ observations (e.g., flux, magnetic fields, and electric fields) from Van Allen Probes (RBSP), field-aligned currents from AMPERE, and global convection maps from SuperDARN. These different boundary settings include a Maxwellian distribution assumption with MHD single-fluid temperature and density, a Kappa distribution assumption with MHD single-fluid temperature and density, and a bi-Maxwellian distribution with anisotropic pressures passed from the MHD code. Results indicate that a Kappa distribution at the boundary of RAM leads to a better ring current flux prediction than that with a Maxwellian distribution assumption, as well as a more realistic spatial distribution of ion anisotropy, which is important in driving electromagnetic ion cyclotron waves. The anisotropic pressure coupling between the kinetic code and the MHD code with a bi-Maxwellian function significantly improves the agreement with observations, especially the Dst index prediction.

  5. Modeling of the Convection and Interaction of Ring Current, Plasmaspheric and Plasma Sheet Plasmas in the Inner Magnetosphere

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Chen, Sheng-Hsien; Buzulukova, Natalia; Glocer, Alex

    2010-01-01

    Distinctive sources of ions reside in the plasmasphere, plasmasheet, and ring current regions at discrete energies constitute the major plasma populations in the inner/middle magnetosphere. They contribute to the electrodynamics of the ionosphere-magnetosphere system as important carriers of the global current system, in triggering; geomagnetic storm and substorms, as well as critical components of plasma instabilities such as reconnection and Kelvin-Helmholtz instability at the magnetospheric boundaries. Our preliminary analysis of in-situ measurements shoves the complexity of the plasmas pitch angle distributions at particularly the cold and warm plasmas, vary dramatically at different local times and radial distances from the Earth in response to changes in solar wind condition and Dst index. Using an MHD-ring current coupled code, we model the convection and interaction of cold, warm and energetic ions of plasmaspheric, plasmasheet, and ring current origins in the inner magnetosphere. We compare our simulation results with in-situ and remotely sensed measurements from recent instrumentation on Geotail, Cluster, THEMIS, and TWINS spacecraft.

  6. Aharonov-Bohm conductance through a single-channel quantum ring: persistent-current blockade and zero-mode dephasing.

    PubMed

    Dmitriev, A P; Gornyi, I V; Kachorovskii, V Yu; Polyakov, D G

    2010-07-16

    We study the effect of electron-electron interaction on transport through a tunnel-coupled single-channel ring. We find that the conductance as a function of magnetic flux shows a series of interaction-induced resonances that survive thermal averaging. The period of the series is given by the interaction strength α. The physics behind this behavior is the blocking of the tunneling current by the circular current. The main mechanism of dephasing is due to circular-current fluctuations. The dephasing rate is proportional to the tunneling rate and does not depend on α.

  7. Coherent π-electron dynamics of (P)-2,2'-biphenol induced by ultrashort linearly polarized UV pulses: angular momentum and ring current.

    PubMed

    Mineo, H; Lin, S H; Fujimura, Y

    2013-02-21

    The results of a theoretical investigation of coherent π-electron dynamics for nonplanar (P)-2,2'-biphenol induced by ultrashort linearly polarized UV pulses are presented. Expressions for the time-dependent coherent angular momentum and ring current are derived by using the density matrix method. The time dependence of these coherences is determined by the off-diagonal density matrix element, which can be obtained by solving the coupled equations of motion of the electronic-state density matrix. Dephasing effects on coherent angular momentum and ring current are taken into account within the Markov approximation. The magnitudes of the electronic angular momentum and current are expressed as the sum of expectation values of the corresponding operators in the two phenol rings (L and R rings). Here, L (R) denotes the phenol ring in the left (right)-hand side of (P)-2,2'-biphenol. We define the bond current between the nearest neighbor carbon atoms Ci and Cj as an electric current through a half plane perpendicular to the Ci-Cj bond. The bond current can be expressed in terms of the inter-atomic bond current. The inter-atomic bond current (bond current) depends on the position of the half plane on the bond and has the maximum value at the center. The coherent ring current in each ring is defined by averaging over the bond currents. Since (P)-2,2'-biphenol is nonplanar, the resultant angular momentum is not one-dimensional. Simulations of the time-dependent coherent angular momentum and ring current of (P)-2,2'-biphenol excited by ultrashort linearly polarized UV pulses are carried out using the molecular parameters obtained by the time-dependent density functional theory (TD-DFT) method. Oscillatory behaviors in the time-dependent angular momentum (ring current), which can be called angular momentum (ring current) quantum beats, are classified by the symmetry of the coherent state, symmetric or antisymmetric. The bond current of the bridge bond linking the L and R

  8. Coherent π-electron dynamics of (P)-2,2'-biphenol induced by ultrashort linearly polarized UV pulses: Angular momentum and ring current

    NASA Astrophysics Data System (ADS)

    Mineo, H.; Lin, S. H.; Fujimura, Y.

    2013-02-01

    The results of a theoretical investigation of coherent π-electron dynamics for nonplanar (P)-2,2'-biphenol induced by ultrashort linearly polarized UV pulses are presented. Expressions for the time-dependent coherent angular momentum and ring current are derived by using the density matrix method. The time dependence of these coherences is determined by the off-diagonal density matrix element, which can be obtained by solving the coupled equations of motion of the electronic-state density matrix. Dephasing effects on coherent angular momentum and ring current are taken into account within the Markov approximation. The magnitudes of the electronic angular momentum and current are expressed as the sum of expectation values of the corresponding operators in the two phenol rings (L and R rings). Here, L (R) denotes the phenol ring in the left (right)-hand side of (P)-2,2'-biphenol. We define the bond current between the nearest neighbor carbon atoms Ci and Cj as an electric current through a half plane perpendicular to the Ci-Cj bond. The bond current can be expressed in terms of the inter-atomic bond current. The inter-atomic bond current (bond current) depends on the position of the half plane on the bond and has the maximum value at the center. The coherent ring current in each ring is defined by averaging over the bond currents. Since (P)-2,2'-biphenol is nonplanar, the resultant angular momentum is not one-dimensional. Simulations of the time-dependent coherent angular momentum and ring current of (P)-2,2'-biphenol excited by ultrashort linearly polarized UV pulses are carried out using the molecular parameters obtained by the time-dependent density functional theory (TD-DFT) method. Oscillatory behaviors in the time-dependent angular momentum (ring current), which can be called angular momentum (ring current) quantum beats, are classified by the symmetry of the coherent state, symmetric or antisymmetric. The bond current of the bridge bond linking the L and R

  9. A Long-term Ring Current Measure Created by Using the VMO MANGO Service Package

    NASA Astrophysics Data System (ADS)

    Bargatze, L. F.; King, T. A.

    2008-12-01

    A set of computational routines called MANGO (Magnetogram Analysis for the Network of Geomagnetic Observatories) is utilized to calculate a new measure of magnetic storm activity for the years 1932 to the near present. The MANGO routines are part of an effort to enhance data services available to users of the Heliophysics VxOs, specifically for the Virtual Magnetospheric Observatory (VMO). The community can utilize MANGO to derive value-added data products and images suitable for publication via the VMO web site. MANGO routines will be demonstrated through their application to study magnetic storms, a field of research that began in 1828 when von Humboldt launched an investigation of observations taken simultaneously from magnetic field stations spread around the Earth. The defining signature of magnetic storms is a worldwide decrease of the horizontal component of the magnetic field caused by fluctuations in the strength of the ring current. In the 1940's, Bartel pushed for deriving an index to measure the strength of magnetic storms. Progress intensified during the International Geophysical Year leading to the definition of the Dst index. The definitive Dst index is calculated at WDC-C2 for Geomagnetism in Kyoto by using a derivation scheme certified by Division V of IAGA. The Dst index time series spans the years 1957 to present with a cadence equal to 1-hr. The new data set we will present is a magnetic storm measure that is similar to the Dst index though it is calculated by using MANGO and a method that differs slightly from the official scheme. The MANGO data service package is based on a set of IDL routines that decompose ground magnetic field observations to isolate secular, diurnal, and disturbance variations of the magnetic field station-by-station. Each MANGO subroutine has been written in modular fashion to allow "plug and play"- style flexibility and each has been designed to account for failure modes and noisy data so that the programs will run to

  10. Measurements of the persistent current decay and snapback effect in Nb3Sn Fermilab-built accelerator prototype magnets

    SciTech Connect

    Velev, G.V.; Chlachidze, G.; DiMarco, J.; Kashikhin, V.V.; /Fermilab

    2012-05-01

    In recent years, Fermilab has been performing an intensive R an D program on Nb{sub 3}Sn accelerator magnets. This program has included dipole and quadrupole magnets for different programs and projects, including LARP and VLHC. A systematic study of the persistent current decay and snapback effect in the fields of these magnets was executed at the Fermilab Magnet Test Facility. The decay and snapback were measured under a range of conditions including variations of the current ramp parameters and flattop and injection plateau durations. This study has mostly focused on the dynamic behavior of the normal sextupole and dodecapole components in dipole and quadrupole magnets respectively. The paper summarizes the recent measurements and presents a comparison with previously measured NbTi magnets.

  11. Persistent currents from the decay of quantum turbulence: signatures of an inverse energy cascade in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Anderson, Brian P.; Neely, Tyler W.; Carlo Samson, E.; Wright, Ewan M.; Rooney, Sam J.; Bradley, Ashton S.; Davis, Matthew J.; Law, Kody J. H.; Carretero-Gonzalez, Ricardo; Kevrekidis, Panayotis G.

    2011-05-01

    We report the formation of persistent currents from the decay of turbulence in Bose- Einstein condensates (BECs). In our experiments, a BEC is pierced with a blue-detuned laser beam. By moving the trap center relative to the beam's position, vortices are stirred into the BEC, creating a quantum turbulent state. At finite temperatures, the turbulent state can decay to a persistent current about the blue-detuned laser beam that can last for up to 50 seconds; winding numbers up to 8 have been observed. Our experimental observations correspond well with numerical simulations of the non-equilibrium dynamics and calculations of vortex pinning by a laser beam. We interpret our results as evidence for an inverse energy cascade in dilute-gas BECs. This work is supported by the US National Science Foundation, the Army Research Office, and the New Zealand Foundation for Research, Science, and Technology.

  12. The effect of guard ring on leakage current and spectroscopic performance of TlBr planar detectors

    NASA Astrophysics Data System (ADS)

    Kargar, Alireza; Kim, Hadong; Cirignano, Leonard; Shah, Kanai

    2014-09-01

    Four thallium bromide planar detectors were fabricated from materials grown at RMD Inc. The TlBr samples were prepared to investigate the effect of guard ring on device gamma-ray spectroscopy performance, and to investigate the leakage current through surface and bulk. The devices' active area in planar configuration were 4.4 × 4.4 × 1.0 mm3. In this report, the detector fabrication process is described and the resulting energy spectra are discussed. It is shown that the guard ring improves device spectroscopic performance by shielding the sensing electrode from the surface leakage current, and by making the electric filed more uniform in the active region of the device.

  13. Generation of geometrical phases and persistent spin currents in 1-dimensional rings by Lorentz-violating terms

    NASA Astrophysics Data System (ADS)

    Casana, R.; Ferreira, M. M.; Mouchrek-Santos, V. E.; Silva, Edilberto O.

    2015-06-01

    We have demonstrated that Lorentz-violating terms stemming from the fermion sector of the SME are able to generate geometrical phases on the wave function of electrons confined in 1-dimensional rings, as well as persistent spin currents, in the total absence of electromagnetic fields. We have explicitly evaluated the eigenenergies and eigenspinors of the electrons modified by the Lorentz-violating terms, using them to calculate the dynamic and the Aharonov-Anandan phases in the sequel. The total phase presents a pattern very similar to the Aharonov-Casher phase accumulated by electrons in rings under the action of the Rashba interaction. Finally, the persistent spin current were carried out and used to impose upper bounds on the Lorentz-violating parameters.

  14. Discovery of energetic molecular ions (NO/sup +/ and O/sub 2//sup +/) in the storm time ring current

    SciTech Connect

    Klecker, B.; Moebius, E.; Hovestadt, D.; Scholer, M.; Gloeckler, G.; Ipavich, F.M.

    1986-07-01

    A few hours after the onset of a large geomagnetic storm on September 4, 1984, energetic molecular ions in the mass range 28--32, predminantly NO/sup +/ and O/sub 2//sup +/, have been discovered in the outer ring current at L--7. The data have been obtained with the time-of-flight spectrometer SULEICA on the AMPTE/IRM spacecraft. We find at 160 keV/e a mean abundance ratio of the molecular ions relative to O/sup +/ ions of 0.031 +- 0.004. During quiet times no molecular ions are observed, the 1 sigma upper limit of the ratio derived by averaging over several quiet periods is 0.003. The observations demonstrate the injection of ionospheric plasma into the storm time ring current and the subsequent acceleration to energies of several hundred keV on a time scale of a few hours after the onset of the magnetic storm.

  15. Middle-Latitude Ionospheric Irregularities and Their Relationships with the Ring Current and Auroral Oval Expansion during Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Pi, X.; Mannucci, A. J.; Zhang, Y.

    2016-12-01

    To study ionospheric irregularities, global maps of ionospheric irregularities and scintillation (GMIIS) have been generated at the Jet Propulsion Laboratory. Each GMIIS visualizes a snapshot of global measurements of the rate of TEC index (ROTI) in a 5-minute interval, and the measurements are derived from GPS observations collected from thousands of GNSS stations. In our analysis GMIIS are used to investigate occurrence and evolution of irregularity and scintillation activities in different regions, particularly under disturbed space weather conditions. A number of middle-latitude ionospheric irregularity events are captured using GMIIS that show the irregularities can expand down to sub-auroral and middle latitudes (well below 50 degree dip latitude) during certain geomagnetic storms. The affected middle-latitude region can be a major part of the U.S. continent. Such events are remarkably different from the well-established global picture in which ionospheric irregularities and scintillation predominately occur at low and high latitudes. It is also discovered that all major events examined so far are associated with significant ring current enhancement, and the GMIIS pictures are consistent with DMSP auroral images that show auroral oval expansion. The relationships between the activities of irregularities, ring current, and auroral oval expansion indicate that the ring current expansion into the plasmasphere is likely responsible for the middle-latitude irregularity phenomenon. Under this condition the plasma convection and charged particle precipitation driven by the magnetospheric processes penetrates into middle latitudes, and their variations can cause ionospheric irregularities as seen in GPS data. In this presentation we will show major events of middle-latitude irregularities and their relationships with the ring current and auroral activities. The responsible mechanisms will be discussed. The presentation will add the middle-latitude ionospheric

  16. Self-Consistent Model of Magnetospheric Ring Current and Electromagnetic Ion Cyclotron Waves: The May 2-7, 1998, Storm

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Jordanova, V. K.

    2003-01-01

    Complete description of a self-consistent model for magnetospheric ring current interacting with electromagnetic ion cyclotron waves is presented. The model is based on the system of two kinetic equations; one equation describes the ring current ion dynamics, and another equation describes the wave evolution. The effects on ring current ions interacting with electromagnetic ion cyclotron waves, and back on waves, are considered self-consistently by solving both equations on a global magnetospheric scale under non steady-state conditions. In the paper by Khazanov et al. [2002] this self-consistent model has only been shortly outlined, and discussions of many the model related details have been omitted. For example, in present study for the first time a new algorithm for numerical finding of the resonant numbers for quasilinear wave-particle interaction is described, or it is demonstrated that in order to describe quasilinear interaction in a multi-ion thermal plasma correctly, both e and He(+) modes of electromagnetic ion cyclotron waves should be employed. The developed model is used to simulate the entire May 2-7, 1998 storm period. Trapped number fluxes of the ring current protons are calculated and presented along with their comparison with the data measured by the 3D hot plasma instrument Polar/HYDRA. Examining of the wave (MLT, L shell) distributions produced during the storm progress reveals an essential intensification of the wave emissions in about two days after main phase of storm. This result is well consistent with the earlier ground-based observations. Also the theoretical shapes and the occurrence rates for power spectral densities of electromagnetic ion cyclotron waves are studied. It is found that in about 2 days after the storm main phase on May 4, mainly non Gaussian shapes of power spectral densities are produced.

  17. Two current experimental problems in heavy lepton physics: tau decay modes and close mass pairs

    SciTech Connect

    Perl, M.L.

    1987-08-01

    This paper investigates tau lepton decay modes and close-mass lepton pairs. The major part of the paper discusses branching functions from experimental and theoretical viewpoints. Finally, the lack of experimental signatures of close-mass lepton pairs are reviewed. 15 refs., 2 figs., 11 tabs. (JDH)

  18. A short review of our current understanding of the development of ring faults during collapse caldera formation

    NASA Astrophysics Data System (ADS)

    Geyer, Adelina; Marti, Joan

    2014-09-01

    The term collapse caldera refers to those volcanic depressions resulting from the sinking of the chamber roof due to the rapid withdrawal of magma during the course of an eruption. During the last three decades, collapse caldera dynamics has been the focus of attention of numerous, theoretical, numerical and experimental studies. Nonetheless, even if there is a tendency to go for a general and comprehensive caldera dynamics model, some key aspects remain unclear, controversial or completely unsolved. This is the case of ring fault nucleation points and propagation and dip direction. Since direct information on calderas’ deeper structure comes mainly from partially eroded calderas or few witnessed collapses, ring faults layout at depth remains still uncertain. This has generated a strong debate over the detailed internal fault and fracture configuration of a caldera collapse and, in more detail, how ring faults initiate and propagate. We offer here a very short description of the main results obtained by those analogue and theoretical/mathematical models applied to the study of collapse caldera formation. We place special attention on those observations related to the nucleation and propagation of the collapse-controlling ring faults. This summary is relevant to understand the current state-of-the-art of this topic and it should be taken under consideration in future works dealing with collapse caldera dynamics.

  19. Seven Years (2004-2011) of Cassini Measurements Reveal Strong Local Time Asymmetry of the Saturnian Ring Current

    NASA Astrophysics Data System (ADS)

    Sergis, N.; Krimigis, S.; Thomsen, M.; Roelof, E.; Mitchell, D.; Hamilton, D.; Krupp, N.; Dougherty, M.; Crary, F.

    2012-04-01

    The Saturnian ring current, initially inferred from magnetic field and particle measurements after the Voyager 1 and 2 flybys, has been studied in substantial detail via in-situ and remote measurements since the July 2004 Cassini orbit insertion. The ring current of Saturn, located between 7 and 15 RS and primarily composed of O+ ions, is characterized by increased suprathermal (> 3 keV) particle pressure with high (> 1) plasma β values and intense dynamic behavior, as revealed by the analysis of combined particle data from the Cassini Magnetospheric Imaging Instrument (MIMI) and the Cassini Plasma Spectrometer instrument (CAPS), and magnetic field measurements from the Cassini magnetometer (MAG). Among the most important findings so far is that the azimuthal ring current flows primarily to balance inertial centrifugal forces inside ~8 RS, but increasingly it is driven by the non-thermal pressure gradient beyond its maximum region (8-12 RS, 100-150 pA/m2) and certainly it dominates farther out. Beyond ~ 10RS, the non-thermal pressure decreases with radial distance faster than the previously assumed 1/r rate and results in a magnetic perturbation of 10-15 nT. In this work we present the most complete (2004-2011) and up-to-date results, focusing on the local time asymmetry of the ring current properties (e.g. particle pressure, current density), and the relative contribution of different components to the radial force balance. The comprehensive spatial and local time coverage provided by the Cassini orbits has revealed that the suprathermal pressure and its corresponding pressure gradient is higher by a factor of 3 to 8 on the night side, in agreement with the observed distribution of energetic particle injections and energetic neutral atom (ENA) emissions. In addition to in-situ measurements, ENA images from the Ion and Neutral Camera (INCA) of Cassini, offer a unique overview of large parts of the Saturnian magnetosphere, depicting the rotation and dynamics of the

  20. Particle pressure, inertial force, and ring current density profiles in the magnetosphere of Saturn, based on Cassini measurements

    NASA Astrophysics Data System (ADS)

    Sergis, N.; Krimigis, S. M.; Roelof, E. C.; Arridge, C. S.; Rymer, A. M.; Mitchell, D. G.; Hamilton, D. C.; Krupp, N.; Thomsen, M. F.; Dougherty, M. K.; Coates, A. J.; Young, D. T.

    2010-01-01

    We report initial results on the particle pressure distribution and its contribution to ring current density in the equatorial magnetosphere of Saturn, as measured by the Magnetospheric Imaging Instrument (MIMI) and the Cassini Plasma Spectrometer (CAPS) onboard the Cassini spacecraft. Data were obtained from September 2005 to May 2006, within ±0.5 RS from the nominal magnetic equator in the range 6 to 15 RS. The analysis of particle and magnetic field measurements, the latter provided by the Cassini magnetometer (MAG), allows the calculation of average radial profiles for various pressure components in Saturn's magnetosphere. The radial gradient of the total particle pressure is compared to the inertial body force to determine their relative contribution to the Saturnian ring current, and an average radial profile of the azimuthal current intensity is deduced. The results show that: (1) Thermal pressure dominates from 6 to 9 RS, while thermal and suprathermal pressures are comparable outside 9 RS with the latter becoming larger outside 12 RS. (2) The plasma β (particle/magnetic pressure) remains ≥1 outside 8 RS, maximizing (˜3 to ˜10) between 11 and 14 RS. (3) The inertial body force and the pressure gradient are similar at 9-10 RS, but the gradient becomes larger ≥11 RS. (4) The azimuthal ring current intensity develops a maximum between approximately 8 and 12 RS, reaching values of 100-150 pA/m2. Outside this region, it drops with radial distance faster than the 1/r rate assumed by typical disk current models even though the total current is not much different to the model results.

  1. Synapse-specific contribution of the variation of transmitter concentration to the decay of inhibitory postsynaptic currents.

    PubMed Central

    Nusser, Z; Naylor, D; Mody, I

    2001-01-01

    Synaptic transmission is characterized by a remarkable trial-to-trial variability in the postsynaptic response, influencing the way in which information is processed in neuronal networks. This variability may originate from the probabilistic nature of quantal transmitter release, from the stochastic behavior of the receptors, or from the fluctuation of the transmitter concentration in the cleft. We combined nonstationary noise analysis and modeling techniques to estimate the contribution of transmitter fluctuation to miniature inhibitory postsynaptic current (mIPSC) variability. A substantial variability (approximately 30%) in mIPSC decay was found in all cell types studied (neocortical layer2/3 pyramidal cells, granule cells of the olfactory bulb, and interneurons of the cerebellar molecular layer). This large variability was not solely the consequence of the expression of multiple types of GABA(A) receptors, as a similar mIPSC decay variability was observed in cerebellar interneurons that express only a single type (alpha(1)beta(2)gamma(2)) of GABA(A) receptor. At large synapses on these cells, all variance in mIPSC decay could be accounted for by the stochastic behavior of approximately 36 pS channels, consistent with the conductance of alpha(1)beta(2)gamma(2) GABA(A) receptors at physiological temperatures. In contrast, at small synapses, a significant amount of variability in the synaptic cleft GABA transient had to be present to account for the additional variance in IPSC decay over that produced by stochastic channel openings. Thus, our results suggest a synapse-specific contribution of the variation of the spatiotemporal profile of GABA to the decay of IPSCs. PMID:11222289

  2. Signatures of the Dirac electron in the flux dependence of total persistent currents in isolated Aharonov-Bohm rings.

    PubMed

    Cotaescu, I I; Papp, E

    2007-06-20

    This paper deals with the total persistent current at T = 0 produced by the exact energy solution of the Dirac electron moving on isolated 1D Aharonov-Bohm rings. Leading contributions concerning the non-relativistic limit are written down for large values of the electron number. Usual non-relativistic currents get reproduced, but now in terms of a reversed parity of the electron number. Such an 'anomaly' is able to serve as a signature of the Dirac electron referred to above.

  3. (1) H NMR Spectra. Part 28: Proton chemical shifts and couplings in three-membered rings. A ring current model for cyclopropane and a novel dihedral angle dependence for (3) J(HH) couplings involving the epoxy proton.

    PubMed

    Abraham, Raymond J; Leonard, Paul; Tormena, Cláudio F

    2012-04-01

    The (1) H chemical shifts of selected three-membered ring compounds in CDCl(3) solvent were obtained. This allowed the determination of the substituent chemical shifts of the substituents in the three-membered rings and the long-range effect of these rings on the distant protons. The substituent chemical shifts of common substituents in the cyclopropane ring differ considerably from the same substituents in acyclic fragments and in cyclohexane and were modelled in terms of a three-bond (γ)-effect. For long-range protons (more than three bonds removed), the substituent effects of the cyclopropane ring were analysed in terms of the cyclopropane magnetic anisotropy and steric effect. The cyclopropane magnetic anisotropy (ring current) shift was modelled by (a) a single equivalent dipole perpendicular to and at the centre of the cyclopropane ring and (b) by three identical equivalent dipoles perpendicular to the ring placed at each carbon atom. Model (b) gave a more accurate description of the (1) H chemical shifts and was the selected model. After parameterization, the overall root mean square error for the dataset of 289 entries was 0.068 ppm. The anisotropic effects are significant for the cyclopropane protons (ca 1 ppm) but decrease rapidly with distance. The heterocyclic rings of oxirane, thiirane and aziridine do not possess a ring current. (3) J(HH) couplings of the epoxy ring proton with side-chain protons were obtained and shown to be dependent on both the H-C-C-H and H-C-C-O orientations. Both density functional theory calculations and a simple Karplus-type equation gave general agreement with the observed couplings (root mean square error 0.5 Hz over a 10-Hz range).

  4. Quantum dynamics of bosons in a two-ring ladder: Dynamical algebra, vortexlike excitations, and currents

    NASA Astrophysics Data System (ADS)

    Richaud, Andrea; Penna, Vittorio

    2017-07-01

    We study the quantum dynamics of the Bose-Hubbard model on a ladder formed by two rings coupled by the tunneling effect. By implementing the Bogoliubov approximation scheme, we prove that, despite the presence of the inter-ring coupling term, the Hamiltonian decouples in many independent sub-Hamiltonians Ĥk associated with momentum-mode pairs ±k . Each sub-Hamiltonian Ĥk is then shown to be part of a specific dynamical algebra. The properties of the latter allow us to perform the diagonalization process, to find the energy spectrum and the conserved quantities of the model, and to derive the time evolution of important physical observables. We then apply this solution scheme to the simplest possible closed ladder, the double trimer. After observing that the excitations of the system are weakly populated vortices, we explore the corresponding dynamics by varying the initial conditions and the model parameters. Finally, we show that the inter-ring tunneling determines a spectral collapse when approaching the border of the dynamical-stability region.

  5. Field and plasma periodicities in Saturn's equatorial middle magnetosphere: Links between the asymmetric ring current and plasma circulation

    NASA Astrophysics Data System (ADS)

    Kivelson, Margaret; Southwood, David

    Superimposed on the predominantly dipolar field of Saturn's middle magnetosphere (here taken as between 5 and 10 RS) are perturbations of a few nT amplitude that vary with the SKR periodicity. Andrews and coworkers (2008) have determined that averages of the perturbations of the radial and azimuthal field components vary roughly sinusoidally and in quadrature, with the radial component leading. Thus these two components of the magnetic perturbations can be represented as an approximately uniform field rotating in the sense of Saturn's rotation (Espinosa et al., 2003). This perturbation field is referred to by Southwood and Kivelson (2007) as the cam field. Andrews et al. (2008) show that perturbation of the theta component, (theta is colatitude) is also nearly sinusoidal and in-phase with the radial perturbations. It follows that near the equator variations of the field magnitude are also in phase with the radial perturbations. Provan et al. (2009) and Khurana et al. (2009) have attributed the periodicity of the field magnitude to an asymmetric ring current. Saturn's asymmetric ring current is not fixed in local time,as it is at Earth, but rotates quasi-rigidly at the SKR period. A distributed, rotating field-aligned current (FAC) system must develop between regions with an excess of or a dearth of azimuthal current but, because those FACs spread over a large spatial region, the associated current density will be smaller than the current density of the more localized cam current system. Thus, it is the electrons associated with the latter currents that are likely to drive the periodically modulated SKR signals. The ring current of the middle magnetosphere is dominated by inertial currents carried by the thermal plasma (Sergis et al., 2010), but the variation of azimuthal current may arise either from density variations or variations of plasma beta. In either case, the current pattern must drive a circulation of the plasma in the middle magnetosphere. [A circulating

  6. A Search for the Flavor-Changing Neutral Current Top Quark Decay with the CMS Experiment at LHC

    NASA Astrophysics Data System (ADS)

    Won, Steven

    The result of a search for flavor-changing neutral currents (FCNC) in top quark decays is presented. The search is performed in a data sample corresponding to a total integrated luminosity of 5.0 fb-1 of pp collisions at a center-of-mass energy of 7 TeV, collected by the CMS experiment at the LHC in 2011. The observed number of events agrees with the standard model prediction, and no evidence of t→Zq decay is found. A limit on the branching fraction Br(t→Zq) ≤ 0.28% is set at the 95% confidence level (CL). This result is the world's best limit to date.

  7. Bounding the B{sub s{yields}{gamma}{gamma}} decay from Higgs mediated flavor changing neutral current transitions

    SciTech Connect

    Aranda, J. I.; Ramirez-Zavaleta, F.; Tututi, E. S.; Toscano, J. J.

    2010-09-01

    The Higgs-mediated flavor violating bottom-strange quarks transitions induced at the one-loop level by a nondiagonal Hbs coupling are studied within the context of an effective Yukawa sector that comprises SU{sub L}(2)xU{sub Y}(1)-invariant operators of up to dimension six. The most recent experimental result on B{yields}X{sub s{gamma}} with hard photons is employed to constrain the Hbs vertex, which is used to estimate the branching ratio for the B{sub s{yields}{gamma}{gamma}} decay. It is found that the B{sub s{yields}{gamma}{gamma}} decay can reach a branching ratio of the order of 4x10{sup -8}, which is 2 orders of magnitude smaller than the current experimental limit.

  8. Operating experience with high beam currents and transient beam loading in the SLC damping rings

    SciTech Connect

    Minty, M.G.; Akre, R.; Krejcik, P.; Siemann, R.H.

    1995-06-01

    During the 1994 SLC run the nominal operating intensity in the damping rings was raised from 3.5 {times} 10{sup 10} to greater than 4 {times} 10{sup 10} particles per bunch (ppb). Stricter regulation of rf system parameters was required to maintain stability of the rf system and particle beam. Improvements were made in the feedback loops which control the cavity amplitude and loading angles. Compensation for beam loading was also required to prevent klystron saturation during repetition rate changes. To minimize the effects of transient loading on the rf system, the gain of the direct rf feedback loop and the loading angles were optimized.

  9. Control of coupled-bunch instabilities in high current storage rings

    SciTech Connect

    Lambertson, G.

    1991-04-01

    Intense particle beams may be subject to coupled-bunch instabilities that would grow at rates greater than the bunch oscillation frequencies. The suppression of the growth requires both reduction of the driving impedances and active feedback of bunch motions. The shunt impedances of higher-order cavity resonances can be reduced by passive dampers and the beam impedance within the band of the fundamental resonance can be reduced by rf feedback around the cavity and power amplifier. The feedback of bunch motions composed of numerous coupled-bunch modes requires broad-band systems for which the amplifiers are costly. Examples proposed for electron storage rings are presented. 10 refs, 5 figs.

  10. Global Storm-Time Evolution of the Ring Current and the Magnetic Field from Image and TS07D

    NASA Astrophysics Data System (ADS)

    Brandt, P. C.; Sitnov, M. I.; Hsieh, S. Y. W.; Demajistre, R.; Stephens, G. K.

    2015-12-01

    The global storm-evolution of the structure of the inner magnetosphere is believed to be dictated by the dynamic force balance between energetic particles and electrical currents. In this presentation we address how the global evolution of energetic particle spectra and species affect the global field-structure of the inner magnetosphere across storm phases and different storms. We compare the global storm evolution of energetic protons (27-198 keV) and O+ (74-300 keV), obtained from the High-Energy Neutral Atom (HENA) Camera on board IMAGE, to the statistically obtained magnetic field and electrical current distributions from the TS07d model. The energetic particle distributions are obtained from a constrained linear inversion of the HENA images, validated by in-situ measurements from Cluster and optimized through simulations using the HENA response function. We discuss in particular the local-time asymmetry of the main phase ring current and associated energetic particle pressure and its dependence on solar wind parameters, and the evolution to a symmetric recovery-phase ring current.

  11. Relationship between the growth of the ring current and the interplanetary quantity. [solar wind energy-magnetospheric coupling parameter correlation with substorm AE index

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1979-01-01

    Akasofu (1979) has reported that the interplanetary parameter epsilon correlates reasonably well with the magnetospheric substorm index AE; in the first approximation, epsilon represents the solar wind coupled to the magnetosphere. The correlation between the interplanetary parameter, the auroral electrojet index and the ring current index is examined for three magnetic storms. It is shown that when the interplanetary parameter exceeds the amount that can be dissipated by the ionosphere in terms of the Joule heat production, the excess energy is absorbed by the ring current belt, producing an abnormal growth of the ring current index.

  12. Positron neutrino correlations in 32Ar and 33Ar decays: Probes of scalar weak currents and nuclear isospin mixing

    NASA Astrophysics Data System (ADS)

    García, A.; Adelberger, E. G.; Ortiz, C.; Swanson, H. E.; Beck, M.; Tengblad, O.; Borge, M. J. G.; Martel, I.; Bichsel, H.

    2000-12-01

    The positron neutrino correlation in the 0+→0+ β-decay of 32Ar was measured at ISOLDE by analyzing the effect of lepton recoil on the shape of the narrow proton group following the super-allowed decay. Our result is consistent with the standard model prediction;for vanishing Fierz interference we find a=0.9989±0.0052±0.0039. Our result leads to improved constraints on scalar weak interactions. The positron neutrino correlation in 33Ar decay was measured in the same experiment;for vanishing Fierz interference we find a=0.944±0.002±0.003. The 32Ar and 33Ar correlations, in combination with precision measurements of the half-lives, super-allowed branching ratios and beta endpoint energies, will determine the isospin impurities of the super-allowed transitions. These will provide useful tests of isospin-violation corrections used in deducing |Vud| which currently indicates non-unitarity of the KM matrix.

  13. The Current Status of Precision Superallowed Fermi β-Decay Measurements at TRIUMF-ISAC

    NASA Astrophysics Data System (ADS)

    Leach, K. G.

    2011-06-01

    Recent experimental work at the TRIUMF-ISAC radioactive ion-beam facility in Vancouver Canada, has produced several new results related to precise experimental tests of fundamental symmetries. The nature of these programs range from campaigns using existing setups, to the development of new apparati to further the experimental reach. One of the primary goals has been the investigation of superallowed Fermi β-decay, and its relation to Standard Model tests of CVC and CKM unitarity The extraction of experimental β-decay ft values requires the measurement of three quantities: the half-life, the superallowed branching ratio, and the parent-daughter mass difference. TRIUMF-ISAC has the ability to measure each of these values with very high precision, using a gas-proportional-counter, the 8π γ-ray spectrometer, and TITAN, respectively. This report focuses on the recent experimental progress of the superallowed program, as well as highlighting some results from the successful halo-nucleus mass-measurement program at TITAN.

  14. The Current Status of Precision Superallowed Fermi {beta}-Decay Measurements at TRIUMF-ISAC

    SciTech Connect

    Leach, K. G.

    2011-06-28

    Recent experimental work at the TRIUMF-ISAC radioactive ion-beam facility in Vancouver Canada, has produced several new results related to precise experimental tests of fundamental symmetries. The nature of these programs range from campaigns using existing setups, to the development of new apparats to further the experimental reach. One of the primary goals has been the investigation of superallowed Fermi {beta}-decay, and its relation to Standard Model tests of CVC and CKM unitarity The extraction of experimental {beta}-decay ft values requires the measurement of three quantities: the half-life, the superallowed branching ratio, and the parent-daughter mass difference. TRIUMF-ISAC has the ability to measure each of these values with very high precision, using a gas-proportional-counter, the 8{pi}{gamma}-ray spectrometer, and TITAN, respectively. This report focuses on the recent experimental progress of the superallowed program, as well as highlighting some results from the successful halo-nucleus mass-measurement program at TITAN.

  15. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves: Waves in Multi-Ion Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2006-01-01

    The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves (Khazanov et al., 2003) is presented In order to adequately take into account wave propagation and refraction in a multi-ion magnetosphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate the spatial, temporal, and spectral evolution of the ring current and of electromagnetic ion cyclotron waves To demonstrate the effects of EMIC wave propagation and refraction on the wave energy distribution and evolution, we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, owing to the density gradient at the plasmapause, the net wave refraction is suppressed, and He+-mode grows preferably at the plasmapause. This result is in total agreement with previous ray tracing studies and is very clearly found in presented B field spectrograms. Second, comparison of global wave distributions with the results from another ring current model (Kozyra et al., 1997) reveals that this new model provides more intense and more highly plasmapause-organized wave distributions during the May 1998 storm period Finally, it is found that He(+)-mode energy distributions are not Gaussian distributions and most important that wave energy can occupy not only the region of generation, i.e., the region of small wave normal angles, but all wave normal angles, including those to near 90 . The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping and subsequent downward heat transport and excitation of stable auroral red arcs.

  16. Warm Oxygen Enhancements in the Inner Magnetosphere and Their Relation to Geomagnetic Activity, Plasmasphere, and Ring Current.

    NASA Astrophysics Data System (ADS)

    Jahn, J. M.; Skoug, R. M.; Gkioulidou, M.; Bonnell, J. W.; Larsen, B.; Reeves, G. D.; Spence, H. E.

    2014-12-01

    Ionospheric oxygen plays an important role in the dynamics of Earth's magnetosphere. During geomagnetic storms, oxygen transported into the tail can experience significant energization and become a major contributor to the storm-time ring current. At very low energies, a dense cold oxygen torus straddles the outer plasmasphere, frequently with O+/H+ ratios approaching unity. With the Radiation Belt Storm Probes we now also observe a third oxygen population in this region. In this paper we discuss the nature of "warm" (10's eV to few keV, i.e., between plasmasphere and ring current ion energies) oxygen density enhancements over the course of the Van Allen Probes mission. We find that the composition of this warm thermal plasma is very dynamic throughout the inner magnetosphere. The warm oxygen density is highly responsive to changes in geomagnetic activity, varying by more than two orders of magnitude between quiet times and moderate storms. This variation at times is a greater than the variation of the corresponding proton density. The O+/H+ warm plasma density ration will frequently exceed unity, usually during the recovery phase of storms. The region of enhanced warm oxygen density reaches from the plasmasphere boundary out to at least geosynchronous orbit (the largest L-shells covered by the Van Allen Probes). It can be observed at all local times. Barring other geomagnetic activity, warm oxygen density enhancements disappear typically within 5 days of their first detection, which is consistent with drift times through the inner magnetosphere along open drift paths. We are putting these characteristics in context of the composition, location, and evolution of the plasmasphere and the ring current.

  17. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 1; Waves in Multi Ion Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gumayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2006-01-01

    The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves [Khazanov et al., 2003] is presented. In order to adequately take into account the wave propagation and refraction in a multi-ion plasmasphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate spatial, temporal, and spectral evolutions of the ring current and electromagnetic ion cyclotron waves. To demonstrate the effects of EMIC wave propagation and refraction on the EMIC wave energy distributions and evolution we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, due to the density gradient at the plasmapause, the net wave refraction is suppressed, and He(+)-mode grows preferably at plasmapause. This result is in a total agreement with the previous ray tracing studies, and very clear observed in presented B-field spectrograms. Second, comparison the global wave distributions with the results from other ring current model [Kozyra et al., 1997] reveals that our model provides more intense and higher plasmapause organized distributions during the May, 1998 storm period. Finally, the found He(+)-mode energy distributions are not Gaussian distributions, and most important that wave energy can occupy not only the region of generation, i. e. the region of small wave normal angles, but the entire wave normal angle region and even only the region near 90 degrees. The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping, and subsequent downward heat transport and excitation of stable auroral red arcs.

  18. Evolution of low altitude and ring current ENA emissions from moderate magnetospheric storms: Continuous and simultaneous TWINS observations

    NASA Astrophysics Data System (ADS)

    Valek, P. W.; Brandt, P. C.; Fok, M. H.; Goldstein, J.; McComas, D. J.; Perez, J. D.; Roelof, E. C.; Skoug, R. M.

    2010-12-01

    The TWINS mission measures energetic neutral atoms (ENAs) using sensors mounted on two separate spacecraft. Because the two spacecraft's orbital planes and phases are significantly offset, the pair provides a nearly optimal combination of continuous magnetospheric observations from at least one of the TWINS platforms with several hours of simultaneous, dual-platform viewing over each orbit. Two types of ENA signals are observed during storms, corresponding to two fundamental magnetospheric ion processes. The first signal is the high-altitude ring current emission (RCE) due to a parent population of trapped ions in the inner magnetosphere, undergoing charge exchange with the extended neutral hydrogen exosphere. The second is the low altitude emission (LAE) signal that results from precipitating ions which undergo charge exchange with the oxygen exosphere at a few hundred km altitude. Valek et al. (2010) investigated the temporal evolution of the moderate storm of 22 July 2009 and showed the LAE began earlier and was the brightest emission seen during the main phase, while later, during the recovery, the LAE was only as bright as the bulk ring current emissions. Using this same methodology applied to a larger number of storms, we determine the general relative temporal evolution of the RCE and LAE as seen by TWINS. Valek, P., P. C. Brandt, N. Buzulukova, M.-C. Fok, J. Goldstein, D.J. McComas, J. D. Perez, E. C. Roelof, and R. Skoug (2010), Evolution of low altitude and ring current ENA emissions from a moderate magnetospheric storm: Continuous and simultaneous TWINS observations,J. Geophys. Res., doi:10.1029/2010JA015429, in press.

  19. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves: Waves in Multi-Ion Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2006-01-01

    The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves (Khazanov et al., 2003) is presented In order to adequately take into account wave propagation and refraction in a multi-ion magnetosphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate the spatial, temporal, and spectral evolution of the ring current and of electromagnetic ion cyclotron waves To demonstrate the effects of EMIC wave propagation and refraction on the wave energy distribution and evolution, we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, owing to the density gradient at the plasmapause, the net wave refraction is suppressed, and He+-mode grows preferably at the plasmapause. This result is in total agreement with previous ray tracing studies and is very clearly found in presented B field spectrograms. Second, comparison of global wave distributions with the results from another ring current model (Kozyra et al., 1997) reveals that this new model provides more intense and more highly plasmapause-organized wave distributions during the May 1998 storm period Finally, it is found that He(+)-mode energy distributions are not Gaussian distributions and most important that wave energy can occupy not only the region of generation, i.e., the region of small wave normal angles, but all wave normal angles, including those to near 90 . The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping and subsequent downward heat transport and excitation of stable auroral red arcs.

  20. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 1; Waves in Multi Ion Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gumayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

    2006-01-01

    The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves [Khazanov et al., 2003] is presented. In order to adequately take into account the wave propagation and refraction in a multi-ion plasmasphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate spatial, temporal, and spectral evolutions of the ring current and electromagnetic ion cyclotron waves. To demonstrate the effects of EMIC wave propagation and refraction on the EMIC wave energy distributions and evolution we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, due to the density gradient at the plasmapause, the net wave refraction is suppressed, and He(+)-mode grows preferably at plasmapause. This result is in a total agreement with the previous ray tracing studies, and very clear observed in presented B-field spectrograms. Second, comparison the global wave distributions with the results from other ring current model [Kozyra et al., 1997] reveals that our model provides more intense and higher plasmapause organized distributions during the May, 1998 storm period. Finally, the found He(+)-mode energy distributions are not Gaussian distributions, and most important that wave energy can occupy not only the region of generation, i. e. the region of small wave normal angles, but the entire wave normal angle region and even only the region near 90 degrees. The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping, and subsequent downward heat transport and excitation of stable auroral red arcs.

  1. Testing the necessity of transient spikes in the drivers for creating a storm-time ring current

    NASA Astrophysics Data System (ADS)

    Liemohn, M. W.; Ilie, R.; Ridley, A. J.; Kozyra, J. U.; Thomsen, M. F.; Borovsky, J. E.

    2007-12-01

    The role of transient spikes in upstream solar wind parameters and near-Earth plasma sheet parameters is investigated through a series of numerical simulations. During magnetic storms, the near-Earth plasma sheet density (as observed at geosynchronous altitude) is often enhanced relative to its normal, quiescent level. In addition to a baseline increase of the density of up to a few per cubic centimeter lasting several hours, there are usually short-lived (a few to tens of minutes) increases on top of this (up to double the baseline). In addition, the solar wind parameters also often have numerous short-lived spikes and fluctuations within it. The question then arises of the relative contribution of these transient spikes in the drivers to the storm-time ring current intensity. To address this issue, a series of simulations are conducted using the Hot Electron and Ion Drift Integrator (HEIDI) model (formerly the Michigan version of RAM). Various running averages of the upstream solar wind conditions and geosynchronous orbit nightside boundary conditions are used to drive HEIDI. It is found that the spikes are simply adding a linear contribution to the ring current intensity over the baseline (averaged) input levels, and that any nonlinear influences occur beyond the HEIDI simulation domain (i.e., at high latitudes or in the tail). That is, the spikes do not last long enough to develop nonlinear influences on the ring current's total energy content. The HEIDI results are compared against global magnetospheric modeling results using averaged input parameters into the Space Weather Modeling Framework (SWMF), which show a nonlinear response to transient spikes.

  2. Analytical study of the energy rate balance equation for the magnetospheric storm-ring current

    NASA Astrophysics Data System (ADS)

    Clúa de Gonzalez, A. L.; Gonzalez, W. D.

    1998-11-01

    We present some results of the analytical integration of the energy rate balance equation, assuming that the input energy rate is proportional to the azimuthal interplanetary electric field, Ey, and can be described by simple rectangular or triangular functions, as approximations to the frequently observed shapes of Ey, especially during the passage of magnetic clouds. The input function is also parametrized by a reconnection-transfer efficiency factor (which is assumed to vary between 0.1 and 1). Our aim is to solve the balance equation and derive values for the decay parameter compatible with the observed Dst peak values. To facilitate the analytical integration we assume a constant value for through the main phase of the storm. The model is tested for two isolated and well-monitored intense storms. For these storms the analytical results are compared to those obtained by the numerical integration of the balance equation, based on the interplanetary data collected by the ISEE-3 satellite, with the values parametrized close to those obtained by the analytical study. From the best fit between this numerical integration and the observed Dst the most appropriate values of are then determined. Although we specifically focus on the main phase of the storms, this numerical integration has been also extended to the recovery phase by an independent adjust. The results of the best fit for the recovery phase show that the values of may differ drastically from those corresponding to the main phase. The values of the decay parameter for the main phase of each event, m, are found to be very sensitive to the adopted efficiency factor, , decreasing as this factor increases. For the recovery phase, which is characterized by very low values of the power input, the response function becomes almost independent of the value of and the resulting values for the decay time parameter, r, do not vary greatly as varies

  3. Self-Consistent Ring Current Modeling with Propagating Electromagnetic Ion Cyclotron Waves in the Presence of Heavy Ions

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.

    2006-01-01

    The self-consistent treatment of the RC ion dynamics and EMIC waves, which are thought to exert important influences on the ion dynamical evolution, is an important missing element in our understanding of the storm-and recovery-time ring current evolution. Under certain conditions, relativistic electrons, with energies 21 MeV, can be removed from the outer radiation belt by EMIC wave scattering during a magnetic storm. That is why the modeling of EMIC waves is critical and timely issue in magnetospheric physics. To describe the RC evolution itself this study uses the ring current-atmosphere interaction model (RAM). RAM solves the gyration and bounce-averaged Boltzmann-Landau equation inside of geosynchronous orbit. Originally developed at the University of Michigan, there are now several branches of this model currently in use as describe by Liemohn namely those at NASA Goddard Space Flight Center This study will generalize the self-consistent theoretical description of RC ions and EMIC waves that has been developed by Khazanov and include the heavy ions and propagation effects of EMIC waves in the global dynamic of self-consistent RC - EMIC waves coupling. The results of our newly developed model that will be presented at GEM meeting, focusing mainly on the dynamic of EMIC waves and comparison of these results with the previous global RC modeling studies devoted to EMIC waves formation. We also discuss RC ion precipitations and wave induced thermal electron fluxes into the ionosphere.

  4. Geomagnetic cutoff rigidities of cosmic rays in a model of the bounded magnetosphere with the ring current

    NASA Astrophysics Data System (ADS)

    Kichigin, G. N.; Sdobnov, V. E.

    2017-03-01

    The cosmic ray geomagnetic cutoff rigidities are obtained by analytical calculations within an axisymmetric model of bounded magnetosphere, the magnetic field of which is created by the dipole field of the Earth and by two spheres located beyond the Earth with the currents that flow along the parallels and have a value proportional to the cosine of latitude. The inner sphere models the ring current flowing in the westerly direction; the outer sphere simulates the currents over the magnetopause, which flow in the easterly direction. The analytical results of calculations of variations in the geomagnetic cutoff rigidity for different levels of geomagnetic disturbances are given. The results are compared with the results of analytical calculations within the model of unbounded magnetosphere (when the outer sphere is absent).

  5. Ring currents and poloidal magnetic fields in nuclear regions of galaxies

    NASA Astrophysics Data System (ADS)

    Lesch, H.; Crusius, A.; Schlickeiser, R.; Wielebinski, R.

    1989-06-01

    The origin of observed strong poloidal magnetic fields R(z) in the central regions of galaxies which have gaseous rings is discussed. In the context of galactic disk dynamo models only weak poloidal fields but strong toroidal fields result. The strength of the poloidal fields is tied to the central activity and apply known and tested ideas rigorously. A battery process on galactic scales is discussed which ensures the existence of a large-scale magnetic field in the inner galactic region. The frozen-in field may be amplified by v x B compression and turbulent stretching; the resulting field is poloidal. The central activity provides a flow field which can produce B(z) equal to or greater than B(phi).

  6. A Self-Consistent Model of the Interacting Ring Current Ions and Electromagnetic Ion Cyclotron Waves, Initial Results: Waves and Precipitating Fluxes

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Jordanova, V. K.; Krivorutsky, E. N.

    2002-01-01

    Initial results from a newly developed model of the interacting ring current ions and ion cyclotron waves are presented. The model is based on the system of two kinetic equations: one equation describes the ring current ion dynamics, and another equation describes wave evolution. The system gives a self-consistent description of the ring current ions and ion cyclotron waves in a quasilinear approach. These equations for the ion phase space distribution function and for the wave power spectral density were solved on aglobal magnetospheric scale undernonsteady state conditions during the 2-5 May 1998 storm. The structure and dynamics of the ring current proton precipitating flux regions and the ion cyclotron wave-active zones during extreme geomagnetic disturbances on 4 May 1998 are presented and discussed in detail.

  7. PIC simulations of wave-particle interactions with an initial electron velocity distribution from a kinetic ring current model

    DOE PAGES

    Yu, Yiqun; Delzanno, Gian Luca; Jordanova, Vania Koleva; ...

    2017-07-15

    Whistler wave-particle interactions play an important role in the Earth inner magnetospheric dynamics and have been the subject of numerous investigations. By running a global kinetic ring current model (RAM-SCB) in a storm event occurred on Oct 23–24 2002, we obtain the ring current electron distribution at a selected location at MLT of 9 and L of 6 where the electron distribution is composed of a warm population in the form of a partial ring in the velocity space (with energy around 15 keV) in addition to a cool population with a Maxwellian-like distribution. The warm population is likely frommore » the injected plasma sheet electrons during substorm injections that supply fresh source to the inner magnetosphere. These electron distributions are then used as input in an implicit particle-in-cell code (iPIC3D) to study whistler-wave generation and the subsequent wave-particle interactions. Here, we find that whistler waves are excited and propagate in the quasi-parallel direction along the background magnetic field. Several different wave modes are instantaneously generated with different growth rates and frequencies. The wave mode at the maximum growth rate has a frequency around 0.62ωce, which corresponds to a parallel resonant energy of 2.5 keV. Linear theory analysis of wave growth is in excellent agreement with the simulation results. These waves grow initially due to the injected warm electrons and are later damped due to cyclotron absorption by electrons whose energy is close to the resonant energy and can effectively attenuate waves. The warm electron population overall experiences net energy loss and anisotropy drop while moving along the diffusion surfaces towards regions of lower phase space density, while the cool electron population undergoes heating when the waves grow, suggesting the cross-population interactions.« less

  8. Visualizing the fully three-dimensional plasmaspheric and ring current distribution from global EUV and ENA imaging

    NASA Astrophysics Data System (ADS)

    Zimmerman, M. I.; Hsieh, S. W.; Brandt, P. C.; Vandegriff, J. D.; Stephens, G. K.; Toigo, A. D.; Keika, K.; Kusterer, M. B.; Demajistre, R.

    2013-12-01

    Extreme Ultra Violet (EUV) and Energetic neutral atom (ENA) imaging are powerful remote sensing tools utilized on, for example the IMAGE and TWINS missions, that provides global three-dimensional information about the structure, dynamics, and composition of Earth's plasmaspheric He+ and ring current ion distributions. Numerical retrieval techniques provide 3D distributions of quantities such as pressure and ion flux from ring current ENA images and the He+ distribution from EUV plasmasphere images. The tool includes an intuitive interface wnabling the user to select from a variety of prepared datasets, display and manipulate nested pressure isocontours, depict coincident spacecraft tracks and compare in-situ data with global distributions derived from images, and animate the pressure evolution of a magnetospheric storm. Therefore the tool is valuable for the validation and intercomparison between global and in-situ data and is broadly applicable to other derived global datasets and modeling results. Screenshot of the visualization tool including 3D isocontours of pressure inferred from IMAGE/HENA inversion data (left panel) and the equatorial inverted image intensity (right panel).

  9. Storm time dynamics of ring current protons: Implications for the long-term energy budget in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Gkioulidou, Matina; Ukhorskiy, A. Y.; Mitchell, D. G.; Lanzerotti, L. J.

    2016-05-01

    Our investigation of the long-term ring current proton pressure evolution in Earth's inner magnetosphere based on Van Allen Probes data shows drastically different behavior of the low- and high- energy components of the ring current proton population with respect to the SYM-H index variation. We found that while the low-energy component of the protons (<80 keV) is strongly governed by convective timescales and is very well correlated with the absolute value of SYM-H index, the high-energy component (>100 keV) varies on much longer timescales and shows either no correlation or anticorrelation with the absolute value of SYM-H index. Our study also shows that the contributions of the low- and high- energy protons to the inner magnetosphere energy content are comparable. Thus, our results conclusively demonstrate that proton dynamics, and as a result the energy budget in the inner magnetosphere, do not vary strictly on storm time timescales as those are defined by the SYM-H index.

  10. Observed geomagnetic induction effect on Dst-related magnetic observations under different disturbance intensities of the magnetospheric ring current

    NASA Astrophysics Data System (ADS)

    Xu, Dan; Chen, Huaran; Gao, Mengtan

    2015-01-01

    Based on the spherical harmonic expansion of geomagnetic disturbance observed on the mid-latitude surface of the Earth, external and internal field separation is conducted in which the external component is magnetic disturbance caused by the magnetospheric ring current and the internal component is that raised by the correspondingly induced currents within the Earth. The objectives are to evaluate the influences of the induced internal field on the surface magnetic observations and to reveal the response performance of internal geomagnetic induction under different strengths of magnetospheric ring current fluctuations for better understanding of the disturbance storm time ( Dst) index variations. The results show that the ratio of the internal component to surface observation does not remain constant in storm time. During the main phase of the storm, the ratio variation follows the pattern of logarithmic growth with storm evolution up to the top value at the Dst-minimum; then, the ratio slowly decreases in the long recovery phase. Multiple small logarithmic growths are superimposed on the traces of internal ratios, corresponding to temporary ring current intensification during the storm main phase and amplifying the effect of this intensification on surface magnetic observations. With the intensification of magnetospheric storms from the level of (-200 nT, - 100 nT) to (-300 nT, - 200 nT) and (-500 nT, - 300 nT) classified with the Dst-minimum, the top value of the ratio averaged for each storm group in the superposed epoch analysis method increases from the value of 0.295 ± 0.014 to 0.300 ± 0.016 and 0.308 ± 0.015, respectively. It is demonstrated that the geomagnetic induction exceeds the linear relation with the intensification of the external field, which is physically reasonable and coincident with the Faraday's law of induction. Due to the effects of high induction of the oceans and lateral heterogeneity of electric conductivity distribution in the upper

  11. Analysis and design of a high-current, high-voltage accurate power supply for the APS storage ring

    SciTech Connect

    Fathizadeh, M.

    1993-08-01

    There are 81 dipole magnets contained in the storage ring at the Advanced Photon Source (APS). These magnets are connected in series and are energized by only one 12-phase power supply. The eighty-first magnet is located in a temperature-controlled room with an NMR probe to monitor the magnetic field in the magnet and provide a reference signal for correction of the field drift due to aging of the components. The current in the magnets will be held at 497 A. The required current stability of the power supply is {plus_minus}30 ppM, the current reproducibility is {plus_minus}50 ppM, and the current ripple is {plus_minus}400 ppM. The voltage required to maintain such a current in the magnets is about 1700 V. Different schemes for regulating current in the magnets are studied. Pspice software is used to simulate the behavior and the design of such a power supply under different conditions. The pros and cons of each scheme will be given and the proper power and regulating scheme will be selected.

  12. Angular dependence of direct current decay in a closed YBCO double-pancake coil under external AC magnetic field and reduction by magnetic shielding

    NASA Astrophysics Data System (ADS)

    Geng, J.; Zhang, H.; Li, C.; Zhang, X.; Shen, B.; Coombs, T. A.

    2017-03-01

    High T c superconducting (HTS) coils are ideal candidates in the use of high field magnets. HTS coils carrying a direct current, however, suffer a non-negligible loss when they are exposed to an external AC magnetic field. Although this phenomenon is well known, no study concerning AC magnetic field angular dependence of direct current decay has ever been shown. In this work, we experimentally investigate the direct current decay characteristics in a closed double pancake coil made of a YBCO coated conductor under external AC field. AC field of different angles with respect to the coil plane is applied. Results show that the current decay rate presents a strong angular dependence. The fastest decay occurs when the field is parallel to the coil plane, in which case the surface of the tape in the outermost layer experiences most flux variation. To reduce the decay rate, we propose wrapping superconducting tapes around the outermost layer of the coil to shield external AC field. This method significantly reduces direct current decay rate under parallel field, without affecting the perpendicular self-field of the coil.

  13. Subauroral polarization stream on the outer boundary of the ring current during an energetic ion injection event

    NASA Astrophysics Data System (ADS)

    Yuan, Zhigang; Qiao, Zheng; Li, Haimeng; Huang, Shiyong; Wang, Dedong; Yu, Xiongdong; Yu, Tao

    2017-04-01

    Subauroral polarization stream (SAPS) electric field can play an important role in the coupling between the inner magnetosphere and ionosphere; however, the production mechanism of SAPS has not been yet solved. During an energetic ion injection event on 26 March 2004, at latitudes lower than the equatorward boundaries of precipitating plasma sheet electrons and ions, the Defense Meteorological Satellite Program (DMSP) F13 satellite simultaneously observed a strong SAPS with the peak velocity of 1294 m/s and downward flowing field-aligned currents (FACs). Conjugate observations of DMSP F13 and NOAA 15 satellites have shown that FACs flowing into the ionosphere just lie in the outer boundary of the ring current (RC). The downward flowing FACs were observed in a region of positive latitudinal gradients of the ion energy density, implying that the downward flowing FACs are more likely linked to the azimuthal gradient than the radial gradient of the RC ion pressure. Our result demonstrates that RC ion pressure gradients on the outer boundary of the RC in the evening sector during energetic ion injection events can lead to downward flowing FACs so as to cause strong SAPS in condition of low ionospheric conductivities.Plain Language SummaryThis paper provides a good case that the SAPS and FAC occurred in the outer boundary of the <span class="hlt">ring</span> <span class="hlt">current</span> during an energetic ion injection event. Our result demonstrates that RC ion pressure gradients on the outer boundary of the RC in the evening sector during energetic ion injection events can lead to downward flowing FACs so as to cause strong SAPS in condition of low ionospheric conductivities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23612860','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23612860"><span>π-Electron <span class="hlt">ring-currents</span> and bond-<span class="hlt">currents</span> in [10,5]-Coronene and related structures conforming to the 'Annulene-Within-an-Annulene' model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dickens, T K; Mallion, R B</p> <p>2013-06-07</p> <p>A series of hypothetical conjugated structures is defined; the series is called the p-Coronenes and the first four members of it are shown to respect the 'Annulene-Within-an-Annulene' (AWA) model when tested by means of Hückel-London-Pople-McWeeny (HLPM) π-electron <span class="hlt">ring-current</span> and bond-<span class="hlt">current</span> calculations. The first member of this series, 5-Coronene, is also a member of the regular [r,s]-Coronene series, where it is known as [10,5]-Coronene. It is shown that, as p is varied (with p always odd, and with p > 3) through the values 5, 7, 9, 11, etc., the resulting structures alternate between a '[4n + 2]-Annulene-Within-a-[4m]-Annulene' (if (p- 1) is divisible by 4) and a '[4n]-Annulene-Within-a-[4m + 2]-Annulene' (if (p- 1) is not divisible by 4). It is therefore claimed that the p-Coronenes constitute an ideal series for testing the AWA model. It is also remarked that each member of the p-Coronene series has only four Kekulé structures, and that the 'spokes' or 'transverse' bonds connecting the central [p(p- 3)]-membered <span class="hlt">ring</span> to the outer [p(p- 1)]-membered periphery always have a Pauling bond-order of zero, ensuring that the outer and inner <span class="hlt">rings</span> are 'decoupled'; such bonds also bear zero bond-<span class="hlt">current</span>, by symmetry. It is argued that the former property of these transverse bonds, rather than the latter, determines that the p-Coronenes obey the AWA rule-which is in fact an exception, rather than a 'rule'per se. The paper concludes by explicitly stating our philosophy that a conceptually simple model depending on no subjective (or any other) parameters whatsoever can give intuitive chemical insight for certain systems equal to that available from far-more complex methods such as ab initio calculations-what Coulson once famously called 'primitive patterns of understanding'.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22181723','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22181723"><span>Observation of the baryonic flavor-changing neutral <span class="hlt">current</span> <span class="hlt">decay</span> Λb(0)→Λμ+μ-.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Aaltonen, T; González, B Alvarez; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Apresyan, A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bauer, G; Bedeschi, F; Beecher, D; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Bland, K R; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Brisuda, A; Bromberg, C; Brucken, E; Bucciantonio, M; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Cabrera, S; Calancha, C; Camarda, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Crescioli, F; Almenar, C Cuenca; Cuevas, J; Culbertson, R; Dagenhart, D; d'Ascenzo, N; Datta, M; de Barbaro, P; De Cecco, S; De Lorenzo, G; Dell'Orso, M; Deluca, C; Demortier, L; Deng, J; Deninno, M; Devoto, F; d'Errico, M; Di Canto, A; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Dorigo, T; Ebina, K; Elagin, A; Eppig, A; Erbacher, R; Errede, D; Errede, S; Ershaidat, N; Eusebi, R; Fang, H C; Farrington, S; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, S R; Halkiadakis, E; Hamaguchi, A; Han, J Y; Happacher, F; Hara, K; Hare, D; Hare, M; Harr, R F; Hatakeyama, K; Hays, C; Heck, M; Heinrich, J; Herndon, M; Hewamanage, S; Hidas, D; Hocker, A; Hopkins, W; Horn, D; Hou, S; Hughes, R E; Hurwitz, M; Husemann, U; Hussain, N; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jha, M K; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Ketchum, W; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, H W; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Klimenko, S; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Krumnack, N; Kruse, M; Krutelyov, V; Kuhr, T; Kurata, M; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, E; Lee, H S; Lee, J S; Lee, S W; Leo, S; Leone, S; Lewis, J D; Lin, C-J; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, Q; Liu, T; Lockwitz, S; Lockyer, N S; Loginov, A; Lucchesi, D; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maeshima, K; Makhoul, K; Maksimovic, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Martínez, M; Martínez-Ballarín, R; Mastrandrea, P; Mathis, M; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzione, A; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Mondragon, M N; Moon, C S; Moore, R; Morello, M J; Morlock, J; Fernandez, P Movilla; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Griso, S Pagan; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Potamianos, K; Poukhov, O; Prokoshin, F; Pronko, A; Ptohos, F; Pueschel, E; Punzi, G; Pursley, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Renton, P; Rescigno, M; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Safonov, A; Sakumoto, W K; Santi, L; Sartori, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, A; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Sfyrla, A; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shiraishi, S; Shochet, M; Shreyber, I; Simonenko, A; Sinervo, P; Sissakian, A; Sliwa, K; Smith, J R; Snider, F D; Soha, A; Somalwar, S; Sorin, V; Squillacioti, P; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Strycker, G L; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thome, J; Thompson, G A; Thomson, E; Ttito-Guzmán, P; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Vidal, M; Vila, I; Vilar, R; Vogel, M; Volpi, G; Wagner, P; Wagner, R L; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wenzel, H; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Wilbur, S; Wick, F; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamaoka, J; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanetti, A; Zeng, Y; Zucchelli, S</p> <p>2011-11-11</p> <p>We report the first observation of the baryonic flavor-changing neutral <span class="hlt">current</span> <span class="hlt">decay</span> Λ(b)(0)→Λμ(+)μ(-) with 24 signal events and a statistical significance of 5.8 Gaussian standard deviations. This measurement uses a pp collisions data sample corresponding to 6.8 fb(-1) at √s = 1.96 TeV collected by the CDF II detector at the Tevatron collider. The total and differential branching ratios for Λ(b)(0)→Λμ(+)μ(-) are measured. We find B(Λ(b)(0)→Λμ(+)μ(-))=[1.73 ± 0.42(stat) ± (syst)] × 10(-6). We also report the first measurement of the differential branching ratio of B(s)(0)→ϕμ(+)μ(-), using 49 signal events. In addition, we report branching ratios for B(+)→K(+)μ(+)μ(-), B(0)→K(0)μ(+)μ(-), and B→K(*)(892)μ(+)μ(-) <span class="hlt">decays</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1022793-observation-baryonic-flavor-changing-neutral-current-decay-b0','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1022793-observation-baryonic-flavor-changing-neutral-current-decay-b0"><span>Observation of the Baryonic Flavor-Changing Neutral <span class="hlt">Current</span> <span class="hlt">Decay</span> Λb0 → Λµ+µ-</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Aaltonen, T.</p> <p>2011-11-08</p> <p>The authors report the first observation of the baryonic flavor-changing neutral <span class="hlt">current</span> <span class="hlt">decay</span> Λb0 → Λµ+µ- with 24 signal events and a statistical significance of 5.8 Gaussian standard deviations. This measurement uses a pp¯ collisions data sample corresponding to 6.8 fb-1 at √s = 1.96 TeV collected by the CDF II detector at the Tevatron collider. The total and differential branching ratios for Λb0 → Λµ+µ- are measured. They find Β(Λb0 → Λµ+µ-) = [1.73 ± 0.42(stat) ± 0.55(syst)] x 10-6. They also report the first measurement of the differential branching ratio of Bs0→φµ+µ- using 49 signal events. In addition,more » they report branching ratios for B+→K+µ+µ-, B0→K0µ+µ- and Β→ K*(892)µ+µ- <span class="hlt">decays</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22043888','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22043888"><span>Effect of Z Prime -mediated flavor-changing neutral <span class="hlt">current</span> on B {yields} {pi}{pi} <span class="hlt">decays</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sahoo, S.; Das, C. K.; Maharana, L.</p> <p>2011-07-15</p> <p>We study the effect of Z Prime -mediated flavor-changing neutral <span class="hlt">current</span> on the B {yields} {pi}{pi} <span class="hlt">decays</span>. The branching ratios of these <span class="hlt">decays</span> can be enhanced remarkably in the nonuniversal Z Prime model. Our estimated branching ratios B(B{sup 0} {yields} {pi}{sup 0}{pi}{sup 0}) are enhanced significantly from their standard model (SM) value. For g Prime /g = 1, the branching ratios B(B{sup 0} {yields} {pi}{sup 0}{pi}{sup 0}) are very close to the recently observed experimental values and for higher values of g Prime /g branching ratios are more. Our calculated branching ratios B(B{sup 0} {yields} {pi}{sup +}{pi}{sup -}) and B(B{sup +} {yields} {pi}{sup +}{pi}{sup 0}) are also enhanced from the SM value as well as the recently observed experimental values. These enhancements of branching ratios from their SM value give the possibility of new physics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995JGR...10021911K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995JGR...10021911K"><span>Interaction of <span class="hlt">ring</span> <span class="hlt">current</span> and radiation belt protons with ducted plasmaspheric hiss. 2. Time evolution of the distribution function</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kozyra, J. U.; Rasmussen, C. E.; Miller, R. H.; Villalon, E.</p> <p>1995-11-01</p> <p>The evolution of the bounce-averaged <span class="hlt">ring</span> <span class="hlt">current</span>/radiation belt proton distribution is simulated during resonant interactions with ducted plasmaspheric hiss. The plasmaspheric hiss is assumed to be generated by <span class="hlt">ring</span> <span class="hlt">current</span> electrons and to be damped by the energetic protons. Thus energy is transferred between energetic electrons and protons using the plasmaspheric hiss as a mediary. The problem is not solved self-consistently. During the simulation period, interactions with <span class="hlt">ring</span> <span class="hlt">current</span> electrons (not represented in the model) are assumed to maintain the wave amplitudes in the presence of damping by the energetic protons, allowing the wave spectrum to be held fixed. Diffusion coefficients in pitch angle, cross pitch angle/energy, and energy were previously calculated by Kozyra et al. (1994) and are adopted for the present study. The simulation treats the energy range, E>=80 keV, within which the wave diffusion operates on a shorter timescale than other proton loss processes (i.e., Coulomb drag and charge exchange). These other loss processes are not included in the simulation. An interesting result of the simulation is that energy diffusion maximizes at moderate pitch angles near the edge of the atmospheric loss cone. Over the simulation period, diffusion in energy creates an order of magnitude enhancement in the bounce-averaged proton distribution function at moderate pitch angles. The loss cone is nearly empty because scattering of particles at small pitch angles is weak. The bounce-averaged flux distribution, mapped to ionospheric heights, results in elevated locally mirroring proton fluxes. OGO 5 observed order of magnitude enhancements in locally mirroring energetic protons at altitudes between 350 and 1300 km and invariant latitudes between 50° and 60° (Lundblad and Soraas, 1978). The proton distributions were highly anisotropic in pitch angle with nearly empty loss cones. The similarity between the observed distributions and those resulting from this</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24836238','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24836238"><span>Search for flavor-changing neutral <span class="hlt">currents</span> in top-quark <span class="hlt">decays</span> t → Zq in pp collisions at sqrt[s] = 8 TeV.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chatrchyan, S; Khachatryan, V; Sirunyan, A M; Tumasyan, A; Adam, W; Bergauer, T; Dragicevic, M; Erö, J; Fabjan, C; Friedl, M; Frühwirth, R; Ghete, V M; Hartl, C; Hörmann, N; Hrubec, J; Jeitler, M; Kiesenhofer, W; Knünz, V; Krammer, M; Krätschmer, I; Liko, D; Mikulec, I; Rabady, D; Rahbaran, B; Rohringer, H; Schöfbeck, R; Strauss, J; Taurok, A; Treberer-Treberspurg, W; Waltenberger, W; Wulz, C-E; Mossolov, V; Shumeiko, N; Suarez Gonzalez, J; Alderweireldt, S; 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Sung, K; Velasco, M; Won, S; Berry, D; Brinkerhoff, A; Chan, K M; Drozdetskiy, A; Hildreth, M; Jessop, C; Karmgard, D J; Kolb, J; Lannon, K; Luo, W; Lynch, S; Marinelli, N; Morse, D M; Pearson, T; Planer, M; Ruchti, R; Slaunwhite, J; Valls, N; Wayne, M; Wolf, M; Antonelli, L; Bylsma, B; Durkin, L S; Flowers, S; Hill, C; Hughes, R; Kotov, K; Ling, T Y; Puigh, D; Rodenburg, M; Smith, G; Vuosalo, C; Winer, B L; Wolfe, H; Wulsin, H W; Berry, E; Elmer, P; Halyo, V; Hebda, P; Hegeman, J; Hunt, A; Jindal, P; Koay, S A; Lujan, P; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Quan, X; Raval, A; Saka, H; Stickland, D; Tully, C; Werner, J S; Zenz, S C; Zuranski, A; Brownson, E; Lopez, A; Mendez, H; Ramirez Vargas, J E; Alagoz, E; Benedetti, D; Bolla, G; Bortoletto, D; De Mattia, M; Everett, A; Hu, Z; Jones, M; Jung, K; Kress, M; Leonardo, N; Lopes Pegna, D; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Radburn-Smith, B C; Shipsey, I; Silvers, D; Svyatkovskiy, A; Wang, F; Xie, W; Xu, L; Yoo, H D; Zablocki, J; Zheng, Y; Parashar, N; Adair, A; Akgun, B; Ecklund, K M; Geurts, F J M; Li, W; Michlin, B; Padley, B P; Redjimi, R; Roberts, J; Zabel, J; Betchart, B; Bodek, A; Covarelli, R; de Barbaro, P; Demina, R; Eshaq, Y; Ferbel, T; Garcia-Bellido, A; Goldenzweig, P; Han, J; Harel, A; Miner, D C; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Ciesielski, R; Demortier, L; Goulianos, K; Lungu, G; Malik, S; Mesropian, C; Arora, S; Barker, A; Chou, J P; Contreras-Campana, C; Contreras-Campana, E; Duggan, D; Ferencek, D; Gershtein, Y; Gray, R; Halkiadakis, E; Hidas, D; Lath, A; Panwalkar, S; Park, M; Patel, R; Rekovic, V; Robles, J; Salur, S; Schnetzer, S; Seitz, C; Somalwar, S; Stone, R; Thomas, S; Thomassen, P; Walker, M; Rose, K; Spanier, S; Yang, Z C; York, A; Bouhali, O; Eusebi, R; Flanagan, W; Gilmore, J; Kamon, T; Khotilovich, V; Krutelyov, V; Montalvo, R; Osipenkov, I; Pakhotin, Y; Perloff, A; Roe, J; Safonov, A; Sakuma, T; Suarez, I; Tatarinov, A; Toback, D; Akchurin, N; Cowden, C; Damgov, J; Dragoiu, C; Dudero, P R; Kovitanggoon, K; Kunori, S; Lee, S W; Libeiro, T; Volobouev, I; Appelt, E; Delannoy, A G; Greene, S; Gurrola, A; Johns, W; Maguire, C; Mao, Y; Melo, A; Sharma, M; Sheldon, P; Snook, B; Tuo, S; Velkovska, J; Arenton, M W; Boutle, S; Cox, B; Francis, B; Goodell, J; Hirosky, R; Ledovskoy, A; Lin, C; Neu, C; Wood, J; Gollapinni, S; Harr, R; Karchin, P E; Kottachchi Kankanamge Don, C; Lamichhane, P; Sakharov, A; Belknap, D A; Borrello, L; Carlsmith, D; Cepeda, M; Dasu, S; Duric, S; Friis, E; Grothe, M; Hall-Wilton, R; Herndon, M; Hervé, A; Klabbers, P; Klukas, J; Lanaro, A; Loveless, R; Mohapatra, A; Ojalvo, I; Perry, T; Pierro, G A; Polese, G; Ross, I; Sarangi, T; Savin, A; Smith, W H</p> <p>2014-05-02</p> <p>A search for flavor-changing neutral <span class="hlt">currents</span> in top-quark <span class="hlt">decays</span> t → Zq is performed in events produced from the <span class="hlt">decay</span> chain tt → Zq+Wb, where both vector bosons <span class="hlt">decay</span> leptonically, producing a final state with three leptons (electrons or muons). A data set collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7 fb(-1) of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus, no evidence for flavor-changing neutral <span class="hlt">currents</span> in top-quark <span class="hlt">decays</span> is found. A combination with a previous search at 7 TeV excludes a t → Zq branching fraction greater than 0.05% at the 95% confidence level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110013511&hterms=Magnetosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DMagnetosphere','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110013511&hterms=Magnetosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DMagnetosphere"><span>Dynamics of <span class="hlt">Ring</span> <span class="hlt">Current</span> and Electric Fields in the Inner Magnetosphere During Disturbed Periods: CRCM-BATS-R-US Coupled Model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Buzulukova, N.; Fok, M.-C.; Pulkkinen, A.; Kuznetsova, M.; Moore, T. E.; Glocer, A.; Brandt, P. C.; Toth, G.; Rastaetter, L.</p> <p>2010-01-01</p> <p>We present simulation results from a one-way coupled global MHD model (Block-Adaptive-Tree Solar-Wind Roe-Type Upwind Scheme, BATS-R-US) and kinetic <span class="hlt">ring</span> <span class="hlt">current</span> models (Comprehensive <span class="hlt">Ring</span> <span class="hlt">Current</span> Model, CRCM, and Fok <span class="hlt">Ring</span> <span class="hlt">Current</span>, FokRC). The BATS-R-US provides the CRCM/FokRC with magnetic field information and plasma density/temperature at the polar CRCM/FokRC boundary. The CRCM uses an electric potential from the BATS-R-US ionospheric solver at the polar CRCM boundary in order to calculate the electric field pattern consistent with the CRCM pressure distribution. The FokRC electric field potential is taken from BATS-R-US ionospheric solver everywhere in the modeled region, and the effect of Region II <span class="hlt">currents</span> is neglected. We show that for an idealized case with southward-northward-southward Bz IMF turning, CRCM-BATS-R-US reproduces well known features of inner magnetosphere electrodynamics: strong/weak convection under the southward/northward Bz; electric field shielding/overshielding/penetration effects; an injection during the substorm development; Subauroral Ion Drift or Polarization Jet (SAID/PJ) signature in the dusk sector. Furthermore, we find for the idealized case that SAID/PJ forms during the substorm growth phase, and that substorm injection has its own structure of field-aligned <span class="hlt">currents</span> which resembles a substorm <span class="hlt">current</span> wedge. For an actual event (12 August 2000 storm), we calculate ENA emissions and compare with Imager for Magnetopause-to-Aurora Global Exploration/High Energy Neutral Atom data. The CRCM-BATS-R-US reproduces both the global morphology of <span class="hlt">ring</span> <span class="hlt">current</span> and the fine structure of <span class="hlt">ring</span> <span class="hlt">current</span> injection. The FokRC-BATS-R-US shows the effect of a realistic description of Region II <span class="hlt">currents</span> in <span class="hlt">ring</span> <span class="hlt">current</span>-MHD coupled models.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110013511&hterms=electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Delectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110013511&hterms=electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Delectric%2Bcurrent"><span>Dynamics of <span class="hlt">Ring</span> <span class="hlt">Current</span> and Electric Fields in the Inner Magnetosphere During Disturbed Periods: CRCM-BATS-R-US Coupled Model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Buzulukova, N.; Fok, M.-C.; Pulkkinen, A.; Kuznetsova, M.; Moore, T. E.; Glocer, A.; Brandt, P. C.; Toth, G.; Rastaetter, L.</p> <p>2010-01-01</p> <p>We present simulation results from a one-way coupled global MHD model (Block-Adaptive-Tree Solar-Wind Roe-Type Upwind Scheme, BATS-R-US) and kinetic <span class="hlt">ring</span> <span class="hlt">current</span> models (Comprehensive <span class="hlt">Ring</span> <span class="hlt">Current</span> Model, CRCM, and Fok <span class="hlt">Ring</span> <span class="hlt">Current</span>, FokRC). The BATS-R-US provides the CRCM/FokRC with magnetic field information and plasma density/temperature at the polar CRCM/FokRC boundary. The CRCM uses an electric potential from the BATS-R-US ionospheric solver at the polar CRCM boundary in order to calculate the electric field pattern consistent with the CRCM pressure distribution. The FokRC electric field potential is taken from BATS-R-US ionospheric solver everywhere in the modeled region, and the effect of Region II <span class="hlt">currents</span> is neglected. We show that for an idealized case with southward-northward-southward Bz IMF turning, CRCM-BATS-R-US reproduces well known features of inner magnetosphere electrodynamics: strong/weak convection under the southward/northward Bz; electric field shielding/overshielding/penetration effects; an injection during the substorm development; Subauroral Ion Drift or Polarization Jet (SAID/PJ) signature in the dusk sector. Furthermore, we find for the idealized case that SAID/PJ forms during the substorm growth phase, and that substorm injection has its own structure of field-aligned <span class="hlt">currents</span> which resembles a substorm <span class="hlt">current</span> wedge. For an actual event (12 August 2000 storm), we calculate ENA emissions and compare with Imager for Magnetopause-to-Aurora Global Exploration/High Energy Neutral Atom data. The CRCM-BATS-R-US reproduces both the global morphology of <span class="hlt">ring</span> <span class="hlt">current</span> and the fine structure of <span class="hlt">ring</span> <span class="hlt">current</span> injection. The FokRC-BATS-R-US shows the effect of a realistic description of Region II <span class="hlt">currents</span> in <span class="hlt">ring</span> <span class="hlt">current</span>-MHD coupled models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20662282','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20662282"><span>Two interacting charged particles in an Aharonov-Bohm <span class="hlt">ring</span>: Bound state transitions, symmetry breaking, persistent <span class="hlt">currents</span>, and Berry's phase</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moulopoulos, Konstantinos; Constantinou, Martha</p> <p>2004-12-15</p> <p>By using a Green's function procedure we determine exactly the energy spectrum and the associated eigenstates of a system of two oppositely charged particles interacting through a contact potential and moving in a one-dimensional <span class="hlt">ring</span> threaded by a magnetic flux. Critical interactions for the appearance of bound states are analytically determined and are viewed as limiting cases of many-body results from the area of interaction-induced metal-insulator transitions in charged quantal mixtures. Analytical expressions on one-body probability and charge <span class="hlt">current</span> densities for this overall neutral system are derived and their single-valuedness leads to the possibility of states with broken symmetry, with possible experimental signatures in exciton spectra. Persistent <span class="hlt">currents</span> are analytically determined and their properties investigated from the point of view of an interacting mesoscopic system. A cyclic adiabatic process on the interaction potential is also identified, with the associated Berry's phase directly linked to the electric (persistent) <span class="hlt">currents</span>, the probability <span class="hlt">currents</span> having no contribution for a neutral system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.4393X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.4393X"><span>Relativistic electron's butterfly pitch angle distribution modulated by localized background magnetic field perturbation driven by hot <span class="hlt">ring</span> <span class="hlt">current</span> ions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Ying; Chen, Lunjin; Xie, Lun; Fu, Suiyan; Xia, Zhiyang; Pu, Zuyin</p> <p>2017-05-01</p> <p>Dayside modulated relativistic electron's butterfly pitch angle distributions (PADs) from ˜200 keV to 2.6 MeV were observed by Van Allen Probe B at L = 5.3 on 15 November 2013. They were associated with localized magnetic dip driven by hot <span class="hlt">ring</span> <span class="hlt">current</span> ion (60-100 keV proton and 60-200 keV helium and oxygen) injections. We reproduce the electron's butterfly PADs at satellite's location using test particle simulation. The simulation results illustrate that a negative radial flux gradient contributes primarily to the formation of the modulated electron's butterfly PADs through inward transport due to the inductive electric field, while deceleration due to the inductive electric field and pitch angle change also makes in part contribution. We suggest that localized magnetic field perturbation, which is a frequent phenomenon in the magnetosphere during magnetic disturbances, is of great importance for creating electron's butterfly PADs in the Earth's radiation belts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.4334X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.4334X"><span>Relativistic electron's butterfly pitch angle distribution modulated by localized background magnetic field perturbation driven by hot <span class="hlt">ring</span> <span class="hlt">current</span> ions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Ying; Chen, Lunjin; Xie, Lun; Fu, Suiyan; Pu, Zuyin</p> <p>2017-04-01</p> <p>Dayside modulated relativistic electron's butterfly pitch angle distributions (PADs) from 200 keV to 2.6 MeV was observed by Van Allen Probe-B at L = 5.3 on November 15, 2013. They were associated with localized magnetic dip driven by hot <span class="hlt">ring</span> <span class="hlt">current</span> ion (60-100 keV protons and 60-200 keV oxygen) injections. We reproduce the electron's butterfly PADs at satellite's location using test particle simulation. The simulation results illustrate that negative radial flux gradient contributes primarily to the formation of the modulated electron's butterfly PADs through inward transport due to the inductive electric field, while deceleration due to the inductive electric field and pitch angle change make in part contribution. We suggest that localized magnetic field perturbation, which is a frequent phenomenon in the magnetosphere during magnetic disturbances, is of great importance for creating electron's butterfly PADs in the Earth's radiation belts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM11A2132S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM11A2132S"><span>High beta plasma observations in Earth's <span class="hlt">Ring</span> <span class="hlt">Current</span>: Waves and particle oscillations, and drift-mirror instability.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Soto-chavez, A. R.; Lanzerotti, L. J.; Cohen, R. J.; Gerrard, A. J.; Manweiler, J. W.; Kim, H.</p> <p>2016-12-01</p> <p>We report on high beta ( > 1) plasma observations made by the RBSPICE instruments onboard the Van Allen Probes spacecraft. The data presented covers almost two years of continuous measurements (March 9, 2013 to December 31, 2014). This coverage provides an unprecedented opportunity to identify and characterize high-beta plasma occurrences in the inner magnetosphere and their characteristics. It is known that high-beta events involve complex plasma physics dynamics. These events can also have global effects on Earth's magnetosphere. Here we show that on July 6, 2013 (one of many high-beta events) a Pc5 (˜ 2.5 min period) wave was locally generated in the magnetosphere through the drift-mirror instability. We describe the wave characteristics and its effects on particle modulations, specifically <span class="hlt">ring</span> <span class="hlt">current</span> ions (˜ 50-500 keV).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090017831','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090017831"><span>Self-Consistent Model of Magnetospheric Electric Field, <span class="hlt">Ring</span> <span class="hlt">Current</span>, Plasmasphere, and Electromagnetic Ion Cyclotron Waves: Initial Results</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gamayunov, K. V.; Khazanov, G. V.; Liemohn, M. W.; Fok, M.-C.; Ridley, A. J.</p> <p>2009-01-01</p> <p>Further development of our self-consistent model of interacting <span class="hlt">ring</span> <span class="hlt">current</span> (RC) ions and electromagnetic ion cyclotron (EMIC) waves is presented. This model incorporates large scale magnetosphere-ionosphere coupling and treats self-consistently not only EMIC waves and RC ions, but also the magnetospheric electric field, RC, and plasmasphere. Initial simulations indicate that the region beyond geostationary orbit should be included in the simulation of the magnetosphere-ionosphere coupling. Additionally, a self-consistent description, based on first principles, of the ionospheric conductance is required. These initial simulations further show that in order to model the EMIC wave distribution and wave spectral properties accurately, the plasmasphere should also be simulated self-consistently, since its fine structure requires as much care as that of the RC. Finally, an effect of the finite time needed to reestablish a new potential pattern throughout the ionosphere and to communicate between the ionosphere and the equatorial magnetosphere cannot be ignored.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhyS...84b5701S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhyS...84b5701S"><span>Statistical interpretation of transient <span class="hlt">current</span> power-law <span class="hlt">decay</span> in colloidal quantum dot arrays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sibatov, R. T.</p> <p>2011-08-01</p> <p>A new statistical model of the charge transport in colloidal quantum dot arrays is proposed. It takes into account Coulomb blockade forbidding multiple occupancy of nanocrystals and the influence of energetic disorder of interdot space. The model explains power-law <span class="hlt">current</span> transients and the presence of the memory effect. The fractional differential analogue of the Ohm law is found phenomenologically for nanocrystal arrays. The model combines ideas that were considered as conflicting by other authors: the Scher-Montroll idea about the power-law distribution of waiting times in localized states for disordered semiconductors is applied taking into account Coulomb blockade; Novikov's condition about the asymptotic power-law distribution of time intervals between successful <span class="hlt">current</span> pulses in conduction channels is fulfilled; and the carrier injection blocking predicted by Ginger and Greenham (2000 J. Appl. Phys. 87 1361) takes place.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991PhLB..262..148A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991PhLB..262..148A"><span>Search for b-->sX+X- in exclusive <span class="hlt">decays</span> of B mesons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Albrecht, H.; Gläser, R.; Harder, G.; Krüger, A.; Nippe, A.; Oest, T.; Reidenbach, M.; Schäfer, M.; Schmidt-Parzefall, W.; Schröder, H.; Schulz, H. D.; Sefkow, F.; Wurth, R.; Appuhn, R. D.; Drescher, A.; Hast, C.; Herrera, G.; Kolanoski, H.; Lange, A.; Linder, A.; Mankel, R.; Scheck, H.; Schweda, G.; Spaan, B.; Walther, A.; Wegener, D.; Paulini, M.; Reim, K.; Volland, U.; Wegener, H.; Funk, W.; Stiewe, J.; Werner, S.; Ball, S.; Gabriel, J. C.; Geyer, C.; Hölscher, A.; Hofmann, W.; Holzer, B.; Khan, S.; Spengler, J.; Charlesworth, C. E. K.; Edwards, K. W.; Frisken, W. R.; Kapitza, H.; Krieger, P.; Kutschke, R.; Macfarlane, D. B.; McLean, K. W.; Orr, R. S.; Parsons, J. A.; Patel, P. M.; Prentice, J. D.; Seidel, S. C.; Swain, J. D.; Tsipolitis, G.; Yoon, T.-S.; Davis, R.; Ruf, T.; Schael, S.; Schubert, K. R.; Strahl, K.; Waldi, R.; Weseler, S.; Boštjančič, B.; Kernel, G.; Križan, P.; Križnič, E.; Pleško, M.; Cronström, H. I.; Jönsson, L.; Nilsson, A. W.; Babaev, A.; Danilov, M.; Fominykh, B.; Golutvin, A.; Gorelov, I.; Lubimov, V.; Rostovtsev, A.; Semenov, A.; Semenov, S.; Shevchenko, V.; Soloshenko, V.; Tchistilin, V.; Tichomirov, I.; Zaitsev, Yu.; Childers, R.; Darden, C. W.</p> <p>1991-06-01</p> <p>Using the ARGUS detector at the e+e- storage <span class="hlt">ring</span> DORIS II at DESY, penguin <span class="hlt">decays</span> of B mesons involving b-->sX+X- have been searched for, where X is one of e, μ, π, or K. No evidence for these <span class="hlt">decays</span> was found and upoer limits are quoted. These numbers represent important constraints of flavour-changing neutral <span class="hlt">currents</span> in B meson <span class="hlt">decays</span> and probe the heavy-quark and Higgs sectors of the standard model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011CPL...517...98D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011CPL...517...98D"><span>Topological <span class="hlt">ring-current</span> assessment of the 'annulene-within-an-annulene' model in [ N]-circulenes and some structures related to kekulene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dickens, Timothy K.; Mallion, Roger B.</p> <p>2011-11-01</p> <p>Hückel-London-Pople-McWeeny (HLPM) 'topological' <span class="hlt">ring-currents</span> calculated for certain [ N]-circulenes are in accord with (a) the previous generalised predictions based on the London approach and (b) the ab-initio ipso-centric π-electron <span class="hlt">current</span>-density maps that this series of conjugated structures does not conform to the 'annulene-within-an-annulene' (AWA) model. These considerations are extended beyond the [ N]-circulenes to a series of structures formally related to kekulene. One such system studied, anti-kekulene, with a [4 n]-perimeter ( n = 6) and [4 n]-central <span class="hlt">ring</span> ( n = 3), exhibits paramagnetic topological bond-<span class="hlt">currents</span> in its periphery, and a mixture of both paramagnetic and diamagnetic bond-<span class="hlt">currents</span> in its central (overall, paramagnetic) <span class="hlt">ring</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21104760','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21104760"><span>Difference between ²JC2H3 and ²JC3H2 spin-spin couplings in heterocyclic five- and six-membered <span class="hlt">rings</span> as a probe for studying σ-<span class="hlt">ring</span> <span class="hlt">currents</span>: a quantum chemical analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Contreras, Rubén H; dos Santos, Francisco P; Ducati, Lucas C; Tormena, Cláudio F</p> <p>2010-12-01</p> <p>Adequate analyses of canonical molecular orbitals (CMOs) can provide rather detailed information on the importance of different σ-Fermi contact (FC) coupling pathways (FC term transmitted through the σ-skeleton). Knowledge of the spatial distribution of CMOs is obtained by expanding them in terms of natural bond orbitals (NBOs). Their relative importance for transmitting the σ-FC contribution to a given spin-spin coupling constants (SSCCs) is estimated by resorting to the expression of the FC term given by the polarisation propagator formalism. In this way, it is possible to classify the effects affecting such couplings in two different ways: delocalisation interactions taking place in the neighbourhood of the coupling nuclei and 'round the <span class="hlt">ring</span>' effects. The latter, associated with σ-<span class="hlt">ring</span> <span class="hlt">currents</span>, are observed to yield significant differences between the FC terms of (2)J(C2H3) and (2)J(C3H2) SSCCs which, consequently, are taken as probes to gauge the differences in σ-<span class="hlt">ring</span> <span class="hlt">currents</span> for the five-membered <span class="hlt">rings</span> (furan, thiophene, selenophene and pyrrol) and also for the six-membered <span class="hlt">rings</span> (benzene, pyridine, protonated pyridine and N-oxide pyridine) used in the present study. Copyright © 2010 John Wiley & Sons, Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EPJB...87..113A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EPJB...87..113A"><span>Effects of geometry and linearly polarized cavity photons on charge and spin <span class="hlt">currents</span> in a quantum <span class="hlt">ring</span> with spin-orbit interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arnold, Thorsten; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar</p> <p>2014-05-01</p> <p>We calculate the persistent charge and spin polarization <span class="hlt">current</span> inside a finite-width quantum <span class="hlt">ring</span> of realistic geometry as a function of the strength of the Rashba or Dresselhaus spin-orbit interaction. The time evolution in the transient regime of the two-dimensional (2D) quantum <span class="hlt">ring</span> connected to electrically biased semi-infinite leads is governed by a time-convolutionless non-Markovian generalized master equation. The electrons are correlated via Coulomb interaction. In addition, the <span class="hlt">ring</span> is embedded in a photon cavity with a single mode of linearly polarized photon field, which is polarized either perpendicular or parallel to the charge transport direction. To analyze carefully the physical effects, we compare to the analytical results of the toy model of a one-dimensional (1D) <span class="hlt">ring</span> of non-interacting electrons with spin-orbit coupling. We find a pronounced charge <span class="hlt">current</span> dip associated with many-electron level crossings at the Aharonov-Casher phase ΔΦ = π, which can be disguised by linearly polarized light. Qualitative agreement is found for the spin polarization <span class="hlt">currents</span> of the 1D and 2D <span class="hlt">ring</span>. Quantitatively, however, the spin polarization <span class="hlt">currents</span> are weaker in the more realistic 2D <span class="hlt">ring</span>, especially for weak spin-orbit interaction, but can be considerably enhanced with the aid of a linearly polarized electromagnetic field. Specific spin polarization <span class="hlt">current</span> symmetries relating the Dresselhaus spin-orbit interaction case to the Rashba one are found to hold for the 2D <span class="hlt">ring</span>, which is embedded in the photon cavity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA10094.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA10094.html"><span>Saturn <span class="hlt">Ring</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2007-12-12</p> <p>Like Earth, Saturn has an invisible <span class="hlt">ring</span> of energetic ions trapped in its magnetic field. This feature is known as a "<span class="hlt">ring</span> <span class="hlt">current</span>." This <span class="hlt">ring</span> <span class="hlt">current</span> has been imaged with a special camera on Cassini sensitive to energetic neutral atoms. This is a false color map of the intensity of the energetic neutral atoms emitted from the <span class="hlt">ring</span> <span class="hlt">current</span> through a processed called charged exchange. In this process a trapped energetic ion steals and electron from cold gas atoms and becomes neutral and escapes the magnetic field. The Cassini Magnetospheric Imaging Instrument's ion and neutral camera records the intensity of the escaping particles, which provides a map of the <span class="hlt">ring</span> <span class="hlt">current</span>. In this image, the colors represent the intensity of the neutral emission, which is a reflection of the trapped ions. This "<span class="hlt">ring</span>" is much farther from Saturn (roughly five times farther) than Saturn's famous icy <span class="hlt">rings</span>. Red in the image represents the higher intensity of the particles, while blue is less intense. Saturn's <span class="hlt">ring</span> <span class="hlt">current</span> had not been mapped before on a global scale, only "snippets" or areas were mapped previously but not in this detail. This instrument allows scientists to produce movies (see PIA10083) that show how this <span class="hlt">ring</span> changes over time. These movies reveal a dynamic system, which is usually not as uniform as depicted in this image. The <span class="hlt">ring</span> <span class="hlt">current</span> is doughnut shaped but in some instances it appears as if someone took a bite out of it. This image was obtained on March 19, 2007, at a latitude of about 54.5 degrees and radial distance 1.5 million kilometres (920,000 miles). Saturn is at the center, and the dotted circles represent the orbits of the moon's Rhea and Titan. The Z axis points parallel to Saturn's spin axis, the X axis points roughly sunward in the sun-spin axis plane, and the Y axis completes the system, pointing roughly toward dusk. The ion and neutral camera's field of view is marked by the white line and accounts for the cut-off of the image on the left. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22408008','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22408008"><span>Repetitive formation and <span class="hlt">decay</span> of <span class="hlt">current</span> sheets in magnetic loops: An origin of diverse magnetic structures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kumar, Dinesh; Bhattacharyya, R.; Smolarkiewicz, P. K.</p> <p>2015-01-15</p> <p>In this work, evolution of an incompressible, thermally homogeneous, infinitely conducting, viscous magnetofluid is numerically explored as the fluid undergoes repeated events of magnetic reconnection. The initial magnetic field is constructed by a superposition of two linear force-free fields and has similar morphology as the magnetic loops observed in the solar corona. The results are presented for computations with three distinct sets of footpoint geometries. To onset reconnection, we rely on numerical model magnetic diffusivity, in the spirit of implicit large eddy simulation. It is generally expected that in a high Lundquist number fluid, repeated magnetic reconnections are ubiquitous and hence can lead to a host of magnetic structures with considerable observational importance. In particular, the simulations presented here illustrate formations of magnetic islands, rotating magnetic helices and rising flux ropes—depending on the initial footpoint geometry but through the common process of repeated magnetic reconnections. Further, we observe the development of extended <span class="hlt">current</span> sheets in two case studies, where the footpoint reconnections generate favorable dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850045555&hterms=role+phytoplankton+nutrient+production&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drole%2Bphytoplankton%2Bnutrient%2Bproduction.','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850045555&hterms=role+phytoplankton+nutrient+production&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drole%2Bphytoplankton%2Bnutrient%2Bproduction."><span>Rotary motions and convection as a means of regulating primary production in warm core <span class="hlt">rings</span>. [of ocean <span class="hlt">currents</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yentsch, C. S.; Phinney, D. A.</p> <p>1985-01-01</p> <p>The term '<span class="hlt">ring</span>' is generally used in the case of a subdivision of ocean eddies. in the present investigation, it denotes mesoscale features which are spawned by the Gulf Stream. This investigation is concerned with the mechanism involved in the regulation of the growth of phytoplankton by the physical oceanographic features of <span class="hlt">rings</span>. Gulf Stream <span class="hlt">rings</span> were first observed by Parker (1971) and Fuglister (1972) as a result of extensive temperature measurements from ships in the Gulf Stream. Attention is given to changes in density boundaries associated with the rotation of <span class="hlt">rings</span>, a synthetic model of a newly formed warm core <span class="hlt">ring</span>, convection-stabilization, the role of light, the influence of convective overturn in adding nutrients to surface waters of warm core <span class="hlt">rings</span>, and two major areas which require study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvE..94f2304S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvE..94f2304S"><span><span class="hlt">Ring</span> correlations in random networks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sadjadi, Mahdi; Thorpe, M. F.</p> <p>2016-12-01</p> <p>We examine the correlations between <span class="hlt">rings</span> in random network glasses in two dimensions as a function of their separation. Initially, we use the topological separation (measured by the number of intervening <span class="hlt">rings</span>), but this leads to pseudo-long-range correlations due to a lack of topological charge neutrality in the shells surrounding a central <span class="hlt">ring</span>. This effect is associated with the noncircular nature of the shells. It is, therefore, necessary to use the geometrical distance between <span class="hlt">ring</span> centers. Hence we find a generalization of the Aboav-Weaire law out to larger distances, with the correlations between <span class="hlt">rings</span> <span class="hlt">decaying</span> away when two <span class="hlt">rings</span> are more than about three <span class="hlt">rings</span> apart.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002CPL...355..471S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002CPL...355..471S"><span>Structure, <span class="hlt">ring</span> <span class="hlt">currents</span> and magnetic properties of 12b,12d,12f-triaza-12c,12e,12g-tribora-coronene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Steiner, E.; Fowler, P. W.; Viglione, R. G.; Zanasi, R.</p> <p>2002-04-01</p> <p>The title molecule (TTC), formally derived by replacing the inner C 6 <span class="hlt">ring</span> of coronene with (BN) 3, is predicted at MP2/6-31G * and B3LYP/6-31G * levels to have a planar D 3h equilibrium structure. Coupled Hartree-Fock calculations on TTC with the distributed-gauge continuous transformation of <span class="hlt">current</span> density-diamagnetic zero (CTOCD-DZ) method predict a strongly diatropic coronene-like perimeter <span class="hlt">ring</span> <span class="hlt">current</span>, but with localized inner borazine-like diatropic circulations replacing the central paramagnetic circulation of coronene. On magnetic criteria, therefore, TTC is predicted to be at least as aromatic as coronene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014plri.book.....E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014plri.book.....E"><span>Planetary <span class="hlt">Rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Esposito, Larry</p> <p>2014-03-01</p> <p>Preface: a personal view of planetary <span class="hlt">rings</span>; 1. Introduction: the allure of the <span class="hlt">ringed</span> planets; 2. Studies of planetary <span class="hlt">rings</span> 1610-2013; 3. Diversity of planetary <span class="hlt">rings</span>; 4. Individual <span class="hlt">ring</span> particles and their collisions; 5. Large-scale <span class="hlt">ring</span> evolution; 6. Moons confine and sculpt <span class="hlt">rings</span>; 7. Explaining <span class="hlt">ring</span> phenomena; 8. N-body simulations; 9. Stochastic models; 10. Age and evolution of <span class="hlt">rings</span>; 11. Saturn's mysterious F <span class="hlt">ring</span>; 12. Uranus' <span class="hlt">rings</span> and moons; 13. Neptune's partial <span class="hlt">rings</span>; 14. Jupiter's <span class="hlt">ring</span>-moon system after Galileo and New Horizons; 15. <span class="hlt">Ring</span> photometry; 16. Dusty <span class="hlt">rings</span>; 17. Concluding remarks; Afterword; Glossary; References; Index.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006cosp...36.2187M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006cosp...36.2187M"><span>About distribution of energy, transported in the magnetosphere during superstorm on November 20, 2003, between the ionosphere and <span class="hlt">ring</span> <span class="hlt">current</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mishin, V.; Karavaev, Y.; Sapronova, L.; Kuzminykh, Y.</p> <p></p> <p>The values of the power consumed in the ionosphere Q i and DR-<span class="hlt">current</span> Q DR also the ratio alpha Q DR Q i during different regimes of the superstorm on Nov 20 2003 were calculated by using the new method without applying of the known DPS equation The values of the Perreault-Akasofu s Poynting flux varepsilon 10 -7 V sw B 2 sin 4 theta 2 L 0 2 have been used in calculations of Q DR and the parameter of the same sense varepsilon prime Psi 1 2 V sw mu 0 S where Psi 1 -- the open tail magnetic flux S -- the area of the tail cross-section pierced by Psi 1 Having the values of varepsilon varepsilon prime respectively the underestimated and overestimated values of the total power Q of the superstorm on Nov 20 2003 were found They were used to calculate Q DR 0 5 Q-Q i and alpha The values alpha were changed during the superstorm from alpha 1 to alpha sim 3 - 10 as distinct from the results that are known from the literature Two maximums of alpha coincided with the substorm onsets at 0314 and 0351 UT Some other maximums were found for the interval 1112-1210 UT of the driven regime of the disturbance when a saturation of the ionospheric electric field was observed We interpreted this saturation as the result of the observed fragmentation of the cross-tail <span class="hlt">current</span> in the substorm <span class="hlt">current</span> wedge SCW Thus all the above-mentioned maximums of alpha likely are linked with an amplification of the <span class="hlt">ring</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26831831','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26831831"><span>Persistent <span class="hlt">current</span> in a correlated quantum <span class="hlt">ring</span> with electron-phonon interaction in the presence of Rashba interaction and Aharonov-Bohm flux.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Monisha, P J; Sankar, I V; Sil, Shreekantha; Chatterjee, Ashok</p> <p>2016-02-01</p> <p>Persistent <span class="hlt">current</span> in a correlated quantum <span class="hlt">ring</span> threaded by an Aharonov-Bohm flux is studied in the presence of electron-phonon interactions and Rashba spin-orbit coupling. The quantum <span class="hlt">ring</span> is modeled by the Holstein-Hubbard-Rashba Hamiltonian and the energy is calculated by performing the conventional Lang-Firsov transformation followed by the diagonalization of the effective Hamiltonian within a mean-field approximation. The effects of Aharonov-Bohm flux, temperature, spin-orbit and electron-phonon interactions on the persistent <span class="hlt">current</span> are investigated. It is shown that the electron-phonon interactions reduce the persistent <span class="hlt">current</span>, while the Rashba coupling enhances it. It is also shown that temperature smoothens the persistent <span class="hlt">current</span> curve. The effect of chemical potential on the persistent <span class="hlt">current</span> is also studied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4735522','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4735522"><span>Persistent <span class="hlt">current</span> in a correlated quantum <span class="hlt">ring</span> with electron-phonon interaction in the presence of Rashba interaction and Aharonov-Bohm flux</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Monisha, P. J.; Sankar, I. V.; Sil, Shreekantha; Chatterjee, Ashok</p> <p>2016-01-01</p> <p>Persistent <span class="hlt">current</span> in a correlated quantum <span class="hlt">ring</span> threaded by an Aharonov-Bohm flux is studied in the presence of electron-phonon interactions and Rashba spin-orbit coupling. The quantum <span class="hlt">ring</span> is modeled by the Holstein-Hubbard-Rashba Hamiltonian and the energy is calculated by performing the conventional Lang-Firsov transformation followed by the diagonalization of the effective Hamiltonian within a mean-field approximation. The effects of Aharonov-Bohm flux, temperature, spin-orbit and electron-phonon interactions on the persistent <span class="hlt">current</span> are investigated. It is shown that the electron-phonon interactions reduce the persistent <span class="hlt">current</span>, while the Rashba coupling enhances it. It is also shown that temperature smoothens the persistent <span class="hlt">current</span> curve. The effect of chemical potential on the persistent <span class="hlt">current</span> is also studied. PMID:26831831</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6019597','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6019597"><span>Transport of ions in presence of induced electric field and electrostatic turbulence - source of ions injected into <span class="hlt">ring</span> <span class="hlt">current</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cladis, J.B.; Francis, W.E.</p> <p>1985-01-01</p> <p>The transport of ions from the polar ionosphere to the inner magnetosphere during stormtime conditions has been computed using a Monte Carlo diffusion code. The effect of the electrostatic turbulence assumed to be present during the substorm expansion phase was simulated by a process that accelerated the ions stochastically perpendicular to the magnetic field with a diffusion coefficient proportional to the energization rate of the ions by the induced electric field. This diffusion process was continued as the ions were convected from the plasma sheet boundary layer to the double-spiral injection boundary. Inward of the injection boundary, the ions were convected adiabatically. By using as input an O(+) flux of 2.8 x 10 to the 8th per sq cm per s (w greater than 10 eV) and an H(+) flux of 5.5 x 10 to the 8th per sq cm per s (w greater than 0.63 eV), the computed distribution functions of the ions in the <span class="hlt">ring</span> <span class="hlt">current</span> were found to be in good agreement, over a wide range in L (4 to 8), with measurements made with the ISEE-1 satellite during a storm. This O(+) flux and a large part of the H(+) flux are consistent with the DE satellite measurements of the polar ionospheric outflow during disturbed times. 19 references.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070002805&hterms=waves+electromagnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dwaves%2Belectromagnetic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070002805&hterms=waves+electromagnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dwaves%2Belectromagnetic"><span>Self-Consistent <span class="hlt">Ring</span> <span class="hlt">Current</span> Modeling with Propagating Electromagnetic Ion Cyclotron Waves in the Presence of Heavy Ions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.; Liemohn, M. W.</p> <p>2006-01-01</p> <p>The self-consistent treatment of the RC ion dynamics and EMlC waves, which are thought to exert important influences on the ion dynamical evolution, is an important missing element in our understanding of the storm-and recovery-time <span class="hlt">ring</span> <span class="hlt">current</span> evolution. Under certain conditions, relativistic electrons, with energies greater than or equal to 1 MeV, can be removed from the outer radiation belt by EMlC wave scattering during a magnetic storm (Summers and Thorne, 2003; Albert, 2003). That is why the modeling of EMlC waves is critical and timely issue in magnetospheric physics. This study will generalize the self-consistent theoretical description of RC ions and EMlC waves that has been developed by Khazanov et al. [2002, 2003] and include the heavy ions and propagation effects of EMlC waves in the global dynamic of self-consistent RC - EMlC waves coupling. The results of our newly developed model that will be presented at Huntsville 2006 meeting, focusing mainly on the dynamic of EMlC waves and comparison of these results with the previous global RC modeling studies devoted to EMlC waves formation. We also discuss RC ion precipitations and wave induced thermal electron fluxes into the ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850059830&hterms=electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Delectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850059830&hterms=electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Delectric%2Bcurrent"><span>Transport of ions in presence of induced electric field and electrostatic turbulence - Source of ions injected into <span class="hlt">ring</span> <span class="hlt">current</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cladis, J. B.; Francis, W. E.</p> <p>1985-01-01</p> <p>The transport of ions from the polar ionosphere to the inner magnetosphere during stormtime conditions has been computed using a Monte Carlo diffusion code. The effect of the electrostatic turbulence assumed to be present during the substorm expansion phase was simulated by a process that accelerated the ions stochastically perpendicular to the magnetic field with a diffusion coefficient proportional to the energization rate of the ions by the induced electric field. This diffusion process was continued as the ions were convected from the plasma sheet boundary layer to the double-spiral injection boundary. Inward of the injection boundary, the ions were convected adiabatically. By using as input an O(+) flux of 2.8 x 10 to the 8th per sq cm per s (w greater than 10 eV) and an H(+) flux of 5.5 x 10 to the 8th per sq cm per s (w greater than 0.63 eV), the computed distribution functions of the ions in the <span class="hlt">ring</span> <span class="hlt">current</span> were found to be in good agreement, over a wide range in L (4 to 8), with measurements made with the ISEE-1 satellite during a storm. This O(+) flux and a large part of the H(+) flux are consistent with the DE satellite measurements of the polar ionospheric outflow during disturbed times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850059830&hterms=electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Delectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850059830&hterms=electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Delectric%2Bcurrent"><span>Transport of ions in presence of induced electric field and electrostatic turbulence - Source of ions injected into <span class="hlt">ring</span> <span class="hlt">current</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cladis, J. B.; Francis, W. E.</p> <p>1985-01-01</p> <p>The transport of ions from the polar ionosphere to the inner magnetosphere during stormtime conditions has been computed using a Monte Carlo diffusion code. The effect of the electrostatic turbulence assumed to be present during the substorm expansion phase was simulated by a process that accelerated the ions stochastically perpendicular to the magnetic field with a diffusion coefficient proportional to the energization rate of the ions by the induced electric field. This diffusion process was continued as the ions were convected from the plasma sheet boundary layer to the double-spiral injection boundary. Inward of the injection boundary, the ions were convected adiabatically. By using as input an O(+) flux of 2.8 x 10 to the 8th per sq cm per s (w greater than 10 eV) and an H(+) flux of 5.5 x 10 to the 8th per sq cm per s (w greater than 0.63 eV), the computed distribution functions of the ions in the <span class="hlt">ring</span> <span class="hlt">current</span> were found to be in good agreement, over a wide range in L (4 to 8), with measurements made with the ISEE-1 satellite during a storm. This O(+) flux and a large part of the H(+) flux are consistent with the DE satellite measurements of the polar ionospheric outflow during disturbed times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5438687','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5438687"><span><span class="hlt">Current</span> status of the E(1420)/. iota. (1440) and future prospects of the g sub T <span class="hlt">decaying</span> into. phi. phi</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chung, S.U.</p> <p>1991-12-01</p> <p>A survey is given of the <span class="hlt">current</span> status of the f{sub 1}(1420)/E and the {eta}(1440)/{iota} in the channels of K {bar K}{pi} and {eta}{pi}{pi}. There is now strong evidence that the {eta}(1440)/{iota} is split into two J{sup PC} = o{sup {minus}+} states in the 1.4--1.5 GeV range with the lower-mass state coupling mostly to a{sub 0}(980){pi} whereas the upper-mass state couples mainly to K*(890){bar K}. Both of them cannot be quarkonia. It appears very likely that the f{sub 1}(1420)/E is an S-wave K*(890){bar K} molecule with a strong overlap with the a{sub 0}(980)/{delta}. It is thought that one or more of the J{sup PC} = 1{sup ++} f{sub 2}(2010)/g{sub r}, F{sub 2}(2300)/g{sub T}{prime} and f{sub 2}(2340)/g{sub f}{double prime} states <span class="hlt">decaying</span> into {phi}{phi} may be the tensor glueball. The future prospects at BNL and elsewhere for further experimental work on these on other exotic states coupling to {phi}{phi} are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH51D2613S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH51D2613S"><span>Parametric <span class="hlt">decay</span> of <span class="hlt">current</span>-driven Langmuir oscillations and wave packet formation in plateau plasmas: Relevance to type III bursts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sauer, K.; Malaspina, D.; Pulupa, M.</p> <p>2016-12-01</p> <p>Instead of starting with an unstable electron beam, our focus is directed on the nonlinear response of Langmuir oscillations which are driven after beam stabilization by the still persisting <span class="hlt">current</span> of the (stable) two-electron plasma. The velocity distribution function of the second population forms a plateau with weak damping over a more or less extended wave number range k. As shown by PIC simulations, this so-called plateau plasma drives primarily Langmuir oscillations at the plasma frequency ωe with k=0 over long times without remarkable change of the distribution function. The Langmuir oscillations, however, act as pump wave for parametric <span class="hlt">decay</span> by which an electron-acoustic wave slightly below ωe and a counter-streaming ion-acoustic wave are generated. Both high-frequency waves have nearly the same amplitude which is simply given by the product of plateau density and velocity. Beating of these two wave types leads to pronounced Langmuir amplitude modulation, in good agreement with solar wind and foreshock WIND observations where waveforms and electron distribution functions have simultaneously been analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987PhRvD..35.3423S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987PhRvD..35.3423S"><span>Remarks concerning the O(Zα2) corrections to Fermi <span class="hlt">decays</span>, conserved-vector-<span class="hlt">current</span> predictions, and universality</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sirlin, A.</p> <p>1987-06-01</p> <p>Finite-nuclear-size contributions to the O(Zα2) corrections to Fermi <span class="hlt">decays</span> are studied for realistic nuclear-charge distributions. In conjunction with the results of Koslowsky et al. and recent papers by the author and Zucchini and by Jaus and Rasche, these refinements lead to an average value scrFt=3070.6+/-1.6 s for the accurately measured superallowed Fermi transitions. Correspondingly, Vud=0.9744+/-0.0010 and Vud 2+Vus 2+Vub 2=0.9979+/-0.0021 in good agreement with the three-generation standard model at the level of its quantum corrections. The agreement with conserved-vector-<span class="hlt">current</span> predictions is very good, with each of the eight transitions differing from the average by <1σ. The consequences of using two other calculations of the nuclear mismatch correction δc, Wilkinson's microscopic analysis and the recent results of Ormand and Brown, are briefly discussed. A useful upper bound on scrFt, independent of the δc calculation, is given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27301603','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27301603"><span>Vascular <span class="hlt">rings</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Backer, Carl L; Mongé, Michael C; Popescu, Andrada R; Eltayeb, Osama M; Rastatter, Jeffrey C; Rigsby, Cynthia K</p> <p>2016-06-01</p> <p>The term vascular <span class="hlt">ring</span> refers to congenital vascular anomalies of the aortic arch system that compress the esophagus and trachea, causing symptoms related to those two structures. The most common vascular <span class="hlt">rings</span> are double aortic arch and right aortic arch with left ligamentum. Pulmonary artery sling is rare and these patients need to be carefully evaluated for frequently associated tracheal stenosis. Another cause of tracheal compression occurring only in infants is the innominate artery compression syndrome. In the <span class="hlt">current</span> era, the diagnosis of a vascular <span class="hlt">ring</span> is best established by CT imaging that can accurately delineate the anatomy of the vascular <span class="hlt">ring</span> and associated tracheal pathology. For patients with a right aortic arch there recently has been an increased recognition of a structure called a Kommerell diverticulum which may require resection and transfer of the left subclavian artery to the left carotid artery. A very rare vascular <span class="hlt">ring</span> is the circumflex aorta that is now treated with the aortic uncrossing operation. Patients with vascular <span class="hlt">rings</span> should all have an echocardiogram because of the incidence of associated congenital heart disease. We also recommend bronchoscopy to assess for additional tracheal pathology and provide an assessment of the degree of tracheomalacia and bronchomalacia. The outcomes of surgical intervention are excellent and most patients have complete resolution of symptoms over a period of time. Copyright © 2016 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/28324','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/28324"><span>A Model for Estimating <span class="hlt">Current</span> and Future Timber Volume Loss from Stem <span class="hlt">Decay</span> Caused by Heterobasidion annosum and Other Fungi in Stands of True Fir</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Gregory M. Filip</p> <p>1989-01-01</p> <p>In 1979, an equation was developed to estimate the percentage of <span class="hlt">current</span> and future timber volume loss due to stem <span class="hlt">decay</span> caused by Heterobasidion annosum and other fungi in advance regeneration stands of grand and white fir in eastern Oregon and Washington. Methods for using and testing the equation are presented. Extensive testing in 1988 showed the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16..323S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16..323S"><span>Evolution of the Storm Magnetic Field Disturbance on Earth's Surface and the Associated <span class="hlt">Ring</span> <span class="hlt">Current</span> as Deduced from Multiple Ground Observatories</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shen, Chao; Zeng, Gang; Li, Xinlin; Rong, Zhaojin</p> <p>2014-05-01</p> <p>Based on the continuous magnetic field measurements of the multiple ground observatories, the structure of the geomagnetic field disturbance and its temporal variations have been investigated, so as to deduce the evolution of the storm <span class="hlt">ring</span> <span class="hlt">current</span>. Assuming the geomagnetic field disturbance around Earth is linear in space, the gradient of the corrected H component is obtained from the multiple ground observations. It is found that, the maximum difference of the corrected H component around the Earth surface, as calculated by the gradient of the corrected H component multiplied by the Earth diameter, well represents the asymmetric index Asy-H, but is actually more sensitive to the substorm activities than the Asy-H index. The anti-direction of the gradient of the corrected H component may be regarded as pointing to the position of the maximum partial <span class="hlt">ring</span> <span class="hlt">current</span>. It is shown that, for the ordinary storms (Dst>-200nT) (which may be caused by CIRs, long lasting fast solar wind flows, or prolonged south IMF, etc), the maximum partial <span class="hlt">ring</span> <span class="hlt">current</span> is located around the duskside during the main phase and the earlier stage of the recovery phase. At the later stage of the recovery phase, the position of the maximum partial <span class="hlt">ring</span> <span class="hlt">current</span> keeps rotating eastward, indicating the energetic electrons may play a significant role and the main <span class="hlt">ring</span> <span class="hlt">current</span> carriers may be the electrons at this stage. For the severe storms (Dst<-200nT), the position of the maximum partial <span class="hlt">ring</span> <span class="hlt">current</span> is not so regular, and there is the evidence that the injected electrons may contribute significantly to the <span class="hlt">ring</span> <span class="hlt">current</span> during the main phase of supper storms. Based on physical considerations, this investigation also provides new definitions to the symmetric index Sym-H and asymmetric index Asy-H. It is made possible that, the symmetric index Sym-H and asymmetric index Asy-H may be deduced from the measurements of the geomagnetic observatories located at local but not global area on Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM14A..02G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM14A..02G"><span>Storm time dynamics of <span class="hlt">ring</span> <span class="hlt">current</span> protons and the implications for the long-term energy budget in the inner magnetosphere: Van Allen Probes observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gkioulidou, M.; Ukhorskiy, A. Y.; Mitchell, D. G.; Lanzerotti, L. J.</p> <p>2016-12-01</p> <p>The <span class="hlt">ring</span> <span class="hlt">current</span> plays a key role in the global electrodynamics of the magnetosphere. Pressure gradients associated with <span class="hlt">ring</span> <span class="hlt">current</span> particles can shield the near-Earth region from solar wind induced electric fields. Also, the distortion of the Earth's magnetic field in the inner magnetosphere due to the <span class="hlt">ring</span> <span class="hlt">current</span> formation, affects the transport and loss of particles contributing both to <span class="hlt">ring</span> <span class="hlt">current</span> and radiation belts. Therefore, understanding the long-term evolution of the <span class="hlt">ring</span> <span class="hlt">current</span> energy content is essential. The Van Allen Probes provide continuous monitoring of the region inside geosynchronous orbit, with unprecedented high-energy resolution and wide-energy-range measurements of proton intensities, thus allowing us to revisit the proton dynamics inside geosynchronous orbit in the context of the long-term variability of the energy budget in the inner magnetosphere. We present here a quantitative assessment of the energy budget in the inner magnetosphere, its variations, and the dominant energy contributors during storm time and non-storm time periods. Our investigation of the long-term <span class="hlt">ring</span> <span class="hlt">current</span> proton pressure evolution in Earth's inner magnetosphere shows drastically different behavior of the low- and high- energy components of the <span class="hlt">ring</span> <span class="hlt">current</span> proton population with respect to the SYM-H index variation, an index that has traditionally been used to define geomagnetic storm intervals. We found that while the low-energy component of the protons (<80 keV) is strongly governed by convective timescales and is very well correlated with the absolute value of SYM-H index, the high-energy component (>100 keV) varies on much longer timescales and shows either no correlation or anti-correlation with the absolute value of SYM-H index. Our study also shows that the contributions of the low- and high- energy protons to the inner magnetosphere energy content are comparable. Thus, our results conclusively demonstrate that proton dynamics, and as a result the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1361408','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1361408"><span>Deterministic phase slips in mesoscopic superconducting <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Petković, Ivana; Lollo, A.; Glazman, L. I.; Harris, J. G. E.</p> <p>2016-11-24</p> <p>The properties of one-dimensional superconductors are strongly influenced by topological fluctuations of the order parameter, known as phase slips, which cause the <span class="hlt">decay</span> of persistent <span class="hlt">current</span> in superconducting <span class="hlt">rings</span> and the appearance of resistance in superconducting wires. Despite extensive work, quantitative studies of phase slips have been limited by uncertainty regarding the order parameter’s free-energy landscape. Here we show detailed agreement between measurements of the persistent <span class="hlt">current</span> in isolated flux-biased <span class="hlt">rings</span> and Ginzburg–Landau theory over a wide range of temperature, magnetic field and <span class="hlt">ring</span> size; this agreement provides a quantitative picture of the free-energy landscape. Furthermore, we also demonstrate that phase slips occur deterministically as the barrier separating two competing order parameter configurations vanishes. These results will enable studies of quantum and thermal phase slips in a well-characterized system and will provide access to outstanding questions regarding the nature of one-dimensional superconductivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatCo...713551P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatCo...713551P"><span>Deterministic phase slips in mesoscopic superconducting <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petković, I.; Lollo, A.; Glazman, L. I.; Harris, J. G. E.</p> <p>2016-11-01</p> <p>The properties of one-dimensional superconductors are strongly influenced by topological fluctuations of the order parameter, known as phase slips, which cause the <span class="hlt">decay</span> of persistent <span class="hlt">current</span> in superconducting <span class="hlt">rings</span> and the appearance of resistance in superconducting wires. Despite extensive work, quantitative studies of phase slips have been limited by uncertainty regarding the order parameter's free-energy landscape. Here we show detailed agreement between measurements of the persistent <span class="hlt">current</span> in isolated flux-biased <span class="hlt">rings</span> and Ginzburg-Landau theory over a wide range of temperature, magnetic field and <span class="hlt">ring</span> size; this agreement provides a quantitative picture of the free-energy landscape. We also demonstrate that phase slips occur deterministically as the barrier separating two competing order parameter configurations vanishes. These results will enable studies of quantum and thermal phase slips in a well-characterized system and will provide access to outstanding questions regarding the nature of one-dimensional superconductivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5123074','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5123074"><span>Deterministic phase slips in mesoscopic superconducting <span class="hlt">rings</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Petković, I.; Lollo, A.; Glazman, L. I.; Harris, J. G. E.</p> <p>2016-01-01</p> <p>The properties of one-dimensional superconductors are strongly influenced by topological fluctuations of the order parameter, known as phase slips, which cause the <span class="hlt">decay</span> of persistent <span class="hlt">current</span> in superconducting <span class="hlt">rings</span> and the appearance of resistance in superconducting wires. Despite extensive work, quantitative studies of phase slips have been limited by uncertainty regarding the order parameter's free-energy landscape. Here we show detailed agreement between measurements of the persistent <span class="hlt">current</span> in isolated flux-biased <span class="hlt">rings</span> and Ginzburg–Landau theory over a wide range of temperature, magnetic field and <span class="hlt">ring</span> size; this agreement provides a quantitative picture of the free-energy landscape. We also demonstrate that phase slips occur deterministically as the barrier separating two competing order parameter configurations vanishes. These results will enable studies of quantum and thermal phase slips in a well-characterized system and will provide access to outstanding questions regarding the nature of one-dimensional superconductivity. PMID:27882924</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011plri.book.....E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011plri.book.....E"><span>Planetary <span class="hlt">Rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Esposito, Larry W.</p> <p>2011-07-01</p> <p>Preface; 1. Introduction: the allure of <span class="hlt">ringed</span> planets; 2. Studies of planetary <span class="hlt">rings</span> 1610-2004; 3. Diversity of planetary <span class="hlt">rings</span>; 4. Individual <span class="hlt">ring</span> particles and their collisions; 5. Large-scale <span class="hlt">ring</span> evolution; 6. Moons confine and sculpt <span class="hlt">rings</span>; 7. Explaining <span class="hlt">ring</span> phenomena; 8. N-Body simulations; 9. Stochastic models; 10. Age and evolution of <span class="hlt">rings</span>; 11. Saturn's mysterious F <span class="hlt">ring</span>; 12. Neptune's partial <span class="hlt">rings</span>; 13. Jupiter's <span class="hlt">ring</span>-moon system after Galileo; 14. <span class="hlt">Ring</span> photometry; 15. Dusty <span class="hlt">rings</span>; 16. Cassini observations; 17. Summary: the big questions; Glossary; References; Index.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016sros.confE.144F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016sros.confE.144F"><span>The circumstellar <span class="hlt">ring</span> of SN 1987A</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fransson, Claes; Migotto, Katia; Larsson, Josefin; Pesce, Dominic; Challis, Peter; Chevalier, Roger A.; France, Kevin; Kirshner, Robert P.; Leibundgut, Bruno; Lundqvist, Peter; McCray, Richard; Spyromilio, Jason; Taddia, Francesco; Jerkstrand, Anders; Mattila, Seppo; Smith, Nathan; Sollerman, Jesper; Wheeler, J. Craig; Crotts, Arlin; Garnavich, Peter; Heng, Kevin; Lawrence, Stephen S.; Panagia, Nino; Pun, Chun S. J.; Sonneborn, George; Sugerman, Ben</p> <p>2016-06-01</p> <p>The circumstellar <span class="hlt">ring</span> of supernova 1987A first became visible a few months after the explosion due to photoionisation by the supernova flash. From 1995 hotspots appeared in the <span class="hlt">ring</span> and their brightness increased nearly exponentially as a result of interaction with the supernova blast wave. Imaging and spectroscopic observations with the Hubble Space Telescope and the Very Large Telescope now show that both the shocked and the unshocked emission components from the <span class="hlt">ring</span> have been decreasing since ~ 2009. In addition, the most recent images reveal the brightening of new spots outside the <span class="hlt">ring</span>. These observations indicate that the hotspots are being dissolved by the shocks and that the blast wave is now expanding and interacting with dense clumps beyond the <span class="hlt">ring</span>. Based on the <span class="hlt">currently</span> observed <span class="hlt">decay</span> we predict that the <span class="hlt">ring</span> will be destroyed by ~ 2025, while the blast wave will reveal the distribution of gas as it expands outside the <span class="hlt">ring</span>, thus tracing the mass-loss history of the supernova progenitor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5595630','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5595630"><span>Determining the strength of the <span class="hlt">ring</span> and the magnetopause <span class="hlt">currents</span> during the initial phase of a geomagnetic storm using cosmic-ray data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Flueckiger, E.O.; Smart, D.F.; Shea, M.A.</p> <p>1990-02-01</p> <p>During a geomagnetic storm the strength of the magnetospheric <span class="hlt">current</span> systems is strongly increased. In the initial phase of most events, however, the magnetic field at the Earth's equator (as characterized by the Dst index) shows only a relatively small perturbation due to the opposite magnetic effects caused by the magnetopause <span class="hlt">currents</span> compared to the <span class="hlt">ring</span> <span class="hlt">current</span>. Analysis of Dst and of the cosmic ray cutoff rigidity changes at about 55 deg geomagnetic latitude offers the unique possibility to estimate the intensity of these two <span class="hlt">current</span> systems separately. The procedure is illustrated for the geomagnetic storm on December 17, 1971.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5027383','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5027383"><span>Determining the strength of the <span class="hlt">ring</span> and the magnetopause <span class="hlt">currents</span> during the initial phase of a geomagnetic storm using cosmic ray data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Flueckiger, E.O. ); Smart, D.F.; Shea, M.A. )</p> <p>1990-02-01</p> <p>During a geomagnetic storm the strength of the magnetospheric <span class="hlt">current</span> systems is strongly increased. In the initial phase of most events, however, the magnetic field at the Earth's equator (as characterized by the Dst index) shows only a relatively small perturbation due to the opposite magnetic effects caused by the magnetopause <span class="hlt">currents</span> compared to the <span class="hlt">ring</span> <span class="hlt">current</span>. Analysis of Dst and of the cosmic ray cutoff rigidity changes at about 55{degree} geomagnetic latitude offers the unique possibility to estimate the intensity of these two <span class="hlt">current</span> systems separately. The procedure is illustrated for the geomagnetic storm on December 17, 1971.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122..475M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122..475M"><span>The role of convection in the buildup of the <span class="hlt">ring</span> <span class="hlt">current</span> pressure during the 17 March 2013 storm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Menz, A. M.; Kistler, L. M.; Mouikis, C. G.; Spence, H. E.; Skoug, R. M.; Funsten, H. O.; Larsen, B. A.; Mitchell, D. G.; Gkioulidou, M.</p> <p>2017-01-01</p> <p>On 17 March 2013, the Van Allen Probes measured the H+ and O+ fluxes of the <span class="hlt">ring</span> <span class="hlt">current</span> during a large geomagnetic storm. Detailed examination of the pressure buildup during the storm shows large differences in the pressure measured by the two spacecraft, with measurements separated by only an hour, and large differences in the pressure measured at different local times. In addition, while the H+ and O+ pressure contributions are about equal during the main phase in the near-Earth plasma sheet outside L = 5.5, the O+ pressure dominates at lower L values. We test whether adiabatic convective transport from the near-Earth plasma sheet (L > 5.5) to the inner magnetosphere can explain these observations by comparing the observed inner magnetospheric distributions with the source distribution at constant magnetic moment, mu. We find that adiabatic convection can account for the enhanced pressure observed during the storm. Using a Weimer 1996 electric field we model the drift trajectories to show that the key features can be explained by variation in the near-Earth plasma sheet population and particle access that changes with energy and L shell. Finally, we show that the dominance of O+ at low L shells is due partly to a near-Earth plasma sheet that is preferentially enhanced in O+ at lower energies (5-10 keV) and partly due to the time dependence in the source combined with longer drift times to low L shells. No source of O+ inside L = 5.5 is required to explain the observations at low L shells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1616736L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1616736L"><span>World Encircling Tectonic Vortex Street - Geostreams Revisited: The Southern <span class="hlt">Ring</span> <span class="hlt">Current</span> EM Plasma-Tectonic Coupling in the Western Pacific Rim</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leybourne, Bruce; Smoot, Christian; Longhinos, Biju</p> <p>2014-05-01</p> <p>Interplanetary Magnetic Field (IMF) coupling to south polar magnetic <span class="hlt">ring</span> <span class="hlt">currents</span> transfers induction energy to the Southern Geostream <span class="hlt">ringing</span> Antarctica and underlying its encircling mid-ocean ridge structure. Magnetic reconnection between the southward interplanetary magnetic field and the magnetic field of the earth is the primary energy transfer mechanism between the solar wind and the magnetosphere. Induced telluric <span class="hlt">currents</span> focused within joule spikes along Geostreams heat the southern Pacific. Alignment of the Australian Antarctic Discordance to other tectonic vortexes along the Western Pacific Rim, provide electrical connections to Earths core that modulate global telluric <span class="hlt">currents</span>. The Banda Sea Triple Junction, a mantle vortex north of Australia, and the Lake Baikal Continental Rift vortex in the northern hemisphere modulate atmospheric Jetstream patterns gravitationally linked to internal density oscillations induced by these telluric <span class="hlt">currents</span>. These telluric <span class="hlt">currents</span> are driven by solar magnetic power, rotation and orbital dynamics. A solar rotation 40 day power spectrum in polarity controls north-south migration of earthquakes along the Western Pacific Rim and manifest as the Madden Julian Oscillation a well-documented climate cycle. Solar plasma turbulence cycles related to Hale flares trigger El Nino Southern Oscillations (ENSO's), while solar magnetic field strength frequencies dominate global warming and cooling trends indexed to the Pacific Decadal Oscillation. These Pacific climate anomalies are solar-electro-tectonically modulated via coupling to tropical geostream vortex streets. Particularly the section along the Central Pacific Megatrend connecting the Banda Sea Triple Junction (up welling mantle vortex) north of Australia with the Easter Island & Juan Fernandez twin rotating micro-plates (twin down welling mantle vortexes) along the East Pacific Rise modulating ENSO. Solar eruptions also enhance the equatorial <span class="hlt">ring</span> <span class="hlt">current</span> located</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993PhDT.......204M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993PhDT.......204M"><span>Search for Flavor Changing Neutral <span class="hlt">Current</span> <span class="hlt">Decay</span> Neutral D Meson Going to Positive Muon Muon Produced in 800 Gev/c Proton-Silicon Interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mo, Guanghui</p> <p></p> <p>This thesis presents a search for the flavor changing neutral <span class="hlt">current</span> (FCNC) <span class="hlt">decay</span>, D^0 to mu^+mu^-, in 800 GeV/c proton-silicon interactions. FCNC is highly suppressed in the standard model, and D^0 to mu^+mu^- is expected to occur with a branching ratio around 10^ {-16}. However, some models predict a much larger branching ratio of ~10 ^{-9}. Therefore, the <span class="hlt">decay</span> D^0 to mu^+mu ^- provides an important test of the standard model. A total of 33.5 million dimuon events from the E771 experiment in Fermilab were analyzed. The dimuon invariant mass spectrum between 0.3-8.0 GeV/c^2 was studied in detail. Dimuon resonances of rho^0, omega, phi, J/psi, and psi^' were observed. Their production cross sections, masses, and the full width of rho^0 were measured. No evidence was found for the FCNC <span class="hlt">decays</span>, D^0 to mu^+mu^- and B ^0 to mu^+mu^-. An upper limit for the D^0 to mu ^+mu^- (or | D^0 to mu^+mu^- ) <span class="hlt">decay</span> branching ratio was determined to be < 1.1 times 10^ {-5}, which is equally stringent as the published <span class="hlt">current</span> upper limit of <1.1 times 10^{-5} .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhRvB..88l5424F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvB..88l5424F"><span>Coexistence of diffusive resistance and ballistic persistent <span class="hlt">current</span> in disordered metallic <span class="hlt">rings</span> with rough edges: Possible origin of puzzling experimental values</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feilhauer, J.; Moško, M.</p> <p>2013-09-01</p> <p>Typical persistent <span class="hlt">current</span> (Ityp) in a mesoscopic normal metal <span class="hlt">ring</span> with disorder due to rough edges and random grain boundaries is calculated by use of a scattering matrix method. In addition, resistance of a corresponding metallic wire is obtained from the Landauer formula and the electron mean free path (l) is determined. If disorder is due to the rough edges, a ballistic persistent <span class="hlt">current</span> Ityp≃evF/L is found to coexist with the diffusive resistance (∝L/l), where vF is the Fermi velocity and L≫l is the <span class="hlt">ring</span> length. This ballistic <span class="hlt">current</span> is due to a single electron that moves almost in parallel with the rough edges and thus hits them rarely (it is shown that this parallel motion exists in the <span class="hlt">ring</span> geometry due to the Hartree-Fock interaction). Our finding agrees with a puzzling experimental result Ityp≃evF/L, reported by Chandrasekhar [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.67.3578 67, 3578 (1991)] for metallic <span class="hlt">rings</span> of length L≃100l. If disorder is due to the grain boundaries, our data reproduce the theoretical result Ityp≃(evF/L)(l/L) that holds for the white-noise-like disorder and has been observed in recent experiments. Thus, result Ityp≃evF/L in a disordered metallic <span class="hlt">ring</span> of length L≫l is as normal as result Ityp≃(evF/L)(l/L). Which result is observed depends on the nature of disorder. Experiments that would determine Ityp and l in correlation with the nature of disorder can be instructive.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM43A4252Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM43A4252Y"><span>Source of O+ in the <span class="hlt">ring</span> <span class="hlt">current</span>: Van Allen Probes observations during the 1 June 2013 storm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, J.; Song, P.; Burke, W. J.; Zhang, J.; Noah, M.; Larsen, B.; Spence, H. E.; Reeves, G. D.</p> <p>2014-12-01</p> <p>During magnetic storms, the concentration of O+ ions in the <span class="hlt">ring</span> <span class="hlt">current</span> can increase substantially. The mechanisms that energize these O+ ions so that they gain enough energy to escape from the ionosphere into the magnetosphere have long been debated. The highly sensitive HOPE (Helium, Oxygen, Proton, and Electron) instrument onboard the Van Allen Probe satellites provide an opportunity to investigate this problem. The two satellites are in nearly identical highly-elliptical, low-inclination (~10°) orbits with a perigee of 1.1 Earth radii (RE), an apogee of 5.8 RE, and a period of ~9 hours. We study a storm event whose SSC occurred near 15:00 UT on 31 May 2013 followed by a lengthy initial phase. The main phase began early on 1 June, reaching a Sym-H minimum of - 134 nT at 07:54 UT. We have identified a large energetic proton enhancement event which is marked by a significant increase in the fluxes of high-energy ions in the deep portion of the main phase. We concentrate on the relative dynamics of H+ and O+. From 03:00 UT to 06:50 UT, there were a few quasi-periodic enhancements of O+ fluxes in the 200 eV to 3.5 keV energy range. A Fourier analysis shows clear power around 30 min periods and excellent coherence among these channels. These enhancements further show clear dispersion with high-energy channels increasing first followed by lower energy channels. During the event, the satellites were near the apogee in the pre-midnight local time sector. The location of the source region can be inferred by energy dispersion based on the time-of-flight effect. One may show that if the particles in different energies were produced at the same time and location, time is linearly correlated with the reciprocal of square-root of the energy for the enhanced fluxes and the source distance can be derived by the slope of the lines of enhanced fluxes. During the event, we identified 8 such enhancements. The sources of these O+ ions appear to be from similar distance to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.675b2007C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.675b2007C"><span>Baryonic B <span class="hlt">Decays</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chistov, R.</p> <p>2016-02-01</p> <p>In this talk the <span class="hlt">decays</span> of B-mesons into baryons are discussed. Large mass of B-meson makes possible the <span class="hlt">decays</span> of the type B → baryon (+mesons). Experimental observations and measurements of these <span class="hlt">decays</span> at B-factories Belle and BaBar have stimulate the development of theoretical models in this field. We briefly review the experimental results together with the <span class="hlt">current</span> theoretical models which describe baryonic B <span class="hlt">decays</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvD..93k3010C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvD..93k3010C"><span>Searching for flavor changing neutral <span class="hlt">currents</span> in t →H c , H →τ τ <span class="hlt">decays</span> at the LHC</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Xin; Xia, Li-Gang</p> <p>2016-06-01</p> <p>The prospects of searching for the flavor changing neutral <span class="hlt">current</span> effect in the <span class="hlt">decay</span> of t →H c , H →τ τ are investigated with the simulated p -p collision data for the ATLAS detector at the LHC, where the Higgs mass is assumed to be 125 GeV. A fit based on the constraints from the Higgs mass and the tau <span class="hlt">decay</span> kinematics is performed for each event, which improves significantly the Higgs and top mass reconstruction and helps the signal-background separation. Boosted decision trees discriminants are developed to achieve an optimal sensitivity of searching for the flavor changing neutral <span class="hlt">current</span> signal. An expected upper limit of the branching ratio B (t →H c ) at 95% confidence level of 0.25% is obtained with a data set of 100 fb-1 at √{s }=13 TeV during the LHC Run-2 period.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Tin&pg=5&id=EJ387792','ERIC'); return false;" href="http://eric.ed.gov/?q=Tin&pg=5&id=EJ387792"><span>Aromatic <span class="hlt">Ring</span> <span class="hlt">Currents</span> Illustrated--NMR Spectra of Tin(IV) Porphyrin Complexes. An Advanced Undergraduate Experiment.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Arnold, Dennis P.</p> <p>1988-01-01</p> <p>Attempts to show that in the closed loops of cyclic structures the protons situated in conic regions above and below the <span class="hlt">ring</span> will be shielded. Uses the diamagnetic and air stable octahedral tin(IV) complexes of porphyrins for study. Notes complexes crystallize easily and offer spectacular purple colors. (MVL)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvC..92e5502S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvC..92e5502S"><span>Reexamining the light neutrino exchange mechanism of the 0 ν β β <span class="hlt">decay</span> with left- and right-handed leptonic and hadronic <span class="hlt">currents</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Štefánik, Dušan; Dvornický, Rastislav; Šimkovic, Fedor; Vogel, Petr</p> <p>2015-11-01</p> <p>The extension of the Majorana neutrino mass mechanism of the neutrinoless double-beta <span class="hlt">decay</span> (0 ν β β ) with the inclusion of right-handed leptonic and hadronic <span class="hlt">currents</span> is revisited. While only the exchange of light neutrinos is assumed, the s1 /2 and p1 /2 states of emitted electrons as well as recoil corrections to the nucleon <span class="hlt">currents</span> are taken into account. Within the standard approximations the <span class="hlt">decay</span> rate is factorized into a sum of products of kinematical phase-space factors, nuclear matrix elements, and the fundamental parameters that characterize the lepton number violation. Unlike in the previous treatments, the induced pseudoscalar term of hadron <span class="hlt">current</span> is included, resulting in additional nuclear matrix elements. An improved numerical computation of the phase-space factors is presented, based on the exact Dirac wave functions of the s1 /2 and p1 /2 electrons with finite nuclear size and electron screening taken into account. The dependence of values of these phase-space factors on the different approximation schemes used in evaluation of electron wave functions is discussed. The upper limits for effective neutrino mass and the parameters <λ > and <η > characterizing the right-handed <span class="hlt">current</span> mechanism are deduced from data on the 0 ν β β <span class="hlt">decay</span> of <mml:mmultiscripts>Ge<mml:mprescripts></mml:mprescripts>76 </mml:mmultiscripts> and <mml:mmultiscripts>Xe<mml:mprescripts></mml:mprescripts>136 </mml:mmultiscripts> using nuclear matrix elements calculated within the nuclear shell model and quasiparticle random phase approximation. The differential <span class="hlt">decay</span> rates, i.e., the angular correlations and the single electron energy distributions for various combinations of the total lepton number violating parameters that can help to disentangle the possible mechanism, are described and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1336413','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1336413"><span>Search for top quark <span class="hlt">decays</span> via Higgs-boson-mediated flavor-changing neutral <span class="hlt">currents</span> in pp collisions at sqrt(s) = 8 TeV</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Khachatryan, Vardan; et al.</p> <p>2016-10-16</p> <p>A search is performed for Higgs-boson-mediated flavor-changing neutral <span class="hlt">currents</span> in the <span class="hlt">decays</span> of top quarks. The search is based on proton-proton collision data corresponding to an integrated luminosity of 19.7 inverse-femtobarns at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC. Events in which a top quark pair is produced with one top quark <span class="hlt">decaying</span> into a charm or up quark and a Higgs boson (H), and the other top quark <span class="hlt">decaying</span> into a bottom quark and a W boson are selected. The Higgs boson in these events is assumed to subsequently <span class="hlt">decay</span> into either dibosons or difermions. No significant excess is observed above the expected standard model background, and an upper limit at the 95% confidence level is set on the branching fraction B(t -> Hc) of 0.40% and B(t -> Hu) of 0.55%, where the expected upper limits are 0.43% and 0.40\\%, respectively. These results correspond to upper limits on the square of the flavor-changing Higgs boson Yukawa couplings | lambda[tc]^H |^2 < 6.9E-3 and | lambda[tu]^H |^2 < 9.8E-3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JHEP...02..079K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JHEP...02..079K"><span>Search for top quark <span class="hlt">decays</span> via Higgs-boson-mediated flavor-changing neutral <span class="hlt">currents</span> in pp collisions at √{s}=8 TeV</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; König, A.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Strauss, J.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; De Wolf, E. A.; Janssen, X.; Knutsson, A.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; De Bruyn, I.; Deroover, K.; Heracleous, N.; Lowette, S.; Moortgat, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Brun, H.; Caillol, C.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Léonard, A.; Luetic, J.; Maerschalk, T.; Marinov, A.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cimmino, A.; Cornelis, T.; Dobur, D.; Fagot, A.; Garcia, G.; Gul, M.; Mccartin, J.; Poyraz, D.; Salva, S.; Schöfbeck, R.; Tytgat, M.; Van Driessche, W.; Yazgan, E.; Zaganidis, N.; Beluffi, C.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; Ceard, L.; De Visscher, S.; Delaere, C.; Delcourt, M.; Forthomme, L.; Francois, B.; Giammanco, A.; Jafari, A.; Jez, P.; Komm, M.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Nuttens, C.; Piotrzkowski, K.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Correa Martins Junior, M.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Matos Figueiredo, D.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Cheng, T.; Du, R.; Jiang, C. H.; Leggat, D.; Liu, Z.; Romeo, F.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Zhang, H.; Zhao, J.; Asawatangtrakuldee, C.; Ban, Y.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Micanovic, S.; Sudic, L.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M.; Carrera Jarrin, E.; Abdelalim, A. A.; El-khateeb, E.; Mahmoud, M. A.; Radi, A.; Calpas, B.; Kadastik, M.; Murumaa, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Peltola, T.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Ghosh, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Locci, E.; Machet, M.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Zghiche, A.; Abdulsalam, A.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Chapon, E.; Charlot, C.; Davignon, O.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Miné, P.; Naranjo, I. N.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Regnard, S.; Salerno, R.; Sirois, Y.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Agram, J.-L.; Andrea, J.; Aubin, A.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Le Bihan, A.-C.; Merlin, J. A.; Skovpen, K.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Bouvier, E.; Carrillo Montoya, C. A.; Chierici, R.; Contardo, D.; Courbon, B.; Depasse, P.; El Mamouni, H.; Fan, J.; Fay, J.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sabes, D.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Toriashvili, T.; Tsamalaidze, Z.; Autermann, C.; Beranek, S.; Feld, L.; Heister, A.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Preuten, M.; Raupach, F.; Schael, S.; Schomakers, C.; Schulte, J. F.; Schulz, J.; Verlage, T.; Weber, H.; Zhukov, V.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Olschewski, M.; Padeken, K.; Papacz, P.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Erdogan, Y.; Flügge, G.; Hoehle, F.; Kargoll, B.; Kress, T.; Künsken, A.; Lingemann, J.; Nehrkorn, A.; Nowack, A.; Nugent, I. M.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Asin, I.; Beernaert, K.; Behnke, O.; Behrens, U.; Bin Anuar, A. A.; Borras, K.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Eckerlin, G.; Eckstein, D.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Grados Luyando, J. M.; Gunnellini, P.; Harb, A.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Karacheban, O.; Kasemann, M.; Keaveney, J.; Kieseler, J.; Kleinwort, C.; Korol, I.; Lange, W.; Lelek, A.; Leonard, J.; Lipka, K.; Lobanov, A.; Lohmann, W.; Mankel, R.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Ntomari, E.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Roland, B.; Sahin, M. Ö.; Saxena, P.; Schoerner-Sadenius, T.; Seitz, C.; Spannagel, S.; Stefaniuk, N.; Trippkewitz, K. D.; Van Onsem, G. P.; Walsh, R.; Wissing, C.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Dreyer, T.; Garutti, E.; Goebel, K.; Gonzalez, D.; Haller, J.; Hoffmann, M.; Höing, R. S.; Junkes, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Lapsien, T.; Lenz, T.; Marchesini, I.; Marconi, D.; Meyer, M.; Niedziela, M.; Nowatschin, D.; Ott, J.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Poehlsen, J.; Sander, C.; Scharf, C.; Schleper, P.; Schlieckau, E.; Schmidt, A.; Schumann, S.; Schwandt, J.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Stöver, M.; Tholen, H.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Vormwald, B.; Barth, C.; Baus, C.; Berger, J.; Butz, E.; Chwalek, T.; Colombo, F.; De Boer, W.; Dierlamm, A.; Fink, S.; Friese, R.; Giffels, M.; Gilbert, A.; Haitz, D.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Katkov, I.; Kornmayer, A.; Lobelle Pardo, P.; Maier, B.; Mildner, H.; Mozer, M. U.; Müller, T.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Röcker, S.; Roscher, F.; Schröder, M.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wagner-Kuhr, J.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Topsis-Giotis, I.; Agapitos, A.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Tziaferi, E.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Loukas, N.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Filipovic, N.; Bencze, G.; Hajdu, C.; Hidas, P.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Molnar, J.; Szillasi, Z.; Bartók, M.; Makovec, A.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Bahinipati, S.; Choudhury, S.; Mal, P.; Mandal, K.; Nayak, A.; Sahoo, D. K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Chawla, R.; Gupta, R.; Bhawandeep, U.; Kalsi, A. K.; Kaur, A.; Kaur, M.; Kumar, R.; Mehta, A.; Mittal, M.; Singh, J. B.; Walia, G.; Kumar, Ashok; Bhardwaj, A.; Choudhary, B. C.; Garg, R. 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M.; Lanza, G.; Lista, L.; Meola, S.; Merola, M.; Paolucci, P.; Sciacca, C.; Thyssen, F.; Azzi, P.; Bacchetta, N.; Benato, L.; Bisello, D.; Boletti, A.; Carlin, R.; Carvalho Antunes De Oliveira, A.; Checchia, P.; Dall'Osso, M.; De Castro Manzano, P.; Dorigo, T.; Dosselli, U.; Gasparini, F.; Gasparini, U.; Gozzelino, A.; Lacaprara, S.; Margoni, M.; Meneguzzo, A. T.; Pazzini, J.; Pozzobon, N.; Ronchese, P.; Simonetto, F.; Torassa, E.; Zanetti, M.; Zotto, P.; Zucchetta, A.; Zumerle, G.; Braghieri, A.; Magnani, A.; Montagna, P.; Ratti, S. P.; Re, V.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Alunni Solestizi, L.; Bilei, G. M.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Leonardi, R.; Mantovani, G.; Menichelli, M.; Saha, A.; Santocchia, A.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Bernardini, J.; Boccali, T.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Rizzi, A.; SavoyNavarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; Cipriani, M.; D'imperio, G.; Del Re, D.; Diemoz, M.; Gelli, S.; Jorda, C.; Longo, E.; Margaroli, F.; Meridiani, P.; Organtini, G.; Paramatti, R.; Preiato, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bartosik, N.; Bellan, R.; Biino, C.; Cartiglia, N.; Costa, M.; Covarelli, R.; Degano, A.; Demaria, N.; Finco, L.; Kiani, B.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Monteil, E.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Ravera, F.; Romero, A.; Ruspa, M.; Sacchi, R.; Shchelina, K.; Sola, V.; Solano, A.; Staiano, A.; Traczyk, P.; Belforte, S.; Candelise, V.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; La Licata, C.; Schizzi, A.; Zanetti, A.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Lee, S.; Lee, S. W.; Oh, Y. D.; Sekmen, S.; Son, D. C.; Yang, Y. C.; Kim, H.; Lee, A.; Brochero Cifuentes, J. A.; Kim, T. J.; Cho, S.; Choi, S.; Go, Y.; Gyun, D.; Ha, S.; Hong, B.; Jo, Y.; Kim, Y.; Lee, B.; Lee, K.; Lee, K. S.; Lee, S.; Lim, J.; Park, S. K.; Roh, Y.; Almond, J.; Kim, J.; Oh, S. B.; Seo, S. h.; Yang, U. K.; Yoo, H. D.; Yu, G. B.; Choi, M.; Kim, H.; Kim, H.; Kim, J. H.; Lee, J. S. H.; Park, I. C.; Ryu, G.; Ryu, M. S.; Choi, Y.; Goh, J.; Kim, D.; Kwon, E.; Lee, J.; Yu, I.; Dudenas, V.; Juodagalvis, A.; Vaitkus, J.; Ahmed, I.; Ibrahim, Z. A.; Komaragiri, J. R.; Md Ali, M. A. B.; Mohamad Idris, F.; Wan Abdullah, W. A. T.; Yusli, M. N.; Zolkapli, Z.; Castilla-Valdez, H.; De La Cruz-Burelo, E.; Heredia-De La Cruz, I.; Hernandez-Almada, A.; Lopez-Fernandez, R.; Mejia Guisao, J.; Sanchez-Hernandez, A.; Carrillo Moreno, S.; Vazquez Valencia, F.; Carpinteyro, S.; Pedraza, I.; Salazar Ibarguen, H. A.; Uribe Estrada, C.; Morelos Pineda, A.; Krofcheck, D.; Butler, P. H.; Ahmad, A.; Ahmad, M.; Hassan, Q.; Hoorani, H. R.; Khan, W. A.; Shah, M. A.; Shoaib, M.; Waqas, M.; Bialkowska, H.; Bluj, M.; Boimska, B.; Frueboes, T.; Górski, M.; Kazana, M.; Nawrocki, K.; Romanowska-Rybinska, K.; Szleper, M.; Zalewski, P.; Bunkowski, K.; Byszuk, A.; Doroba, K.; Kalinowski, A.; Konecki, M.; Krolikowski, J.; Misiura, M.; Olszewski, M.; Walczak, M.; Bargassa, P.; Beirão Da Cruz E Silva, C.; Di Francesco, A.; Faccioli, P.; Ferreira Parracho, P. G.; Gallinaro, M.; Hollar, J.; Leonardo, N.; Lloret Iglesias, L.; Nemallapudi, M. V.; Rodrigues Antunes, J.; Seixas, J.; Toldaiev, O.; Vadruccio, D.; Varela, J.; Vischia, P.; Bunin, P.; Golunov, A.; Golutvin, I.; Gorbounov, N.; Karjavin, V.; Korenkov, V.; Lanev, A.; Malakhov, A.; Matveev, V.; Mitsyn, V. V.; Moisenz, P.; Palichik, V.; Perelygin, V.; Shmatov, S.; Shulha, S.; Skatchkov, N.; Smirnov, V.; Tikhonenko, E.; Zarubin, A.; Chtchipounov, L.; Golovtsov, V.; Ivanov, Y.; Kim, V.; Kuznetsova, E.; Murzin, V.; Oreshkin, V.; Sulimov, V.; Vorobyev, A.; Andreev, Yu.; Dermenev, A.; Gninenko, S.; Golubev, N.; Karneyeu, A.; Kirsanov, M.; Krasnikov, N.; Pashenkov, A.; Tlisov, D.; Toropin, A.; Epshteyn, V.; Gavrilov, V.; Lychkovskaya, N.; Popov, V.; Pozdnyakov, I.; Safronov, G.; Spiridonov, A.; Toms, M.; Vlasov, E.; Zhokin, A.; Chistov, R.; Rusinov, V.; Tarkovskii, E.; Andreev, V.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Leonidov, A.; Rusakov, S. V.; Terkulov, A.; Baskakov, A.; Belyaev, A.; Boos, E.; Bunichev, V.; Dubinin, M.; Dudko, L.; Ershov, A.; Klyukhin, V.; Kodolova, O.; Korneeva, N.; Lokhtin, I.; Miagkov, I.; Obraztsov, S.; Perfilov, M.; Savrin, V.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Elumakhov, D.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Krychkine, V.; Petrov, V.; Ryutin, R.; Sobol, A.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Cirkovic, P.; Devetak, D.; Milosevic, J.; Rekovic, V.; Alcaraz Maestre, J.; Calvo, E.; Cerrada, M.; Chamizo Llatas, M.; Colino, N.; De La Cruz, B.; Delgado Peris, A.; Escalante Del Valle, A.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Navarro De Martino, E.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; de Trocóniz, J. F.; Missiroli, M.; Moran, D.; Cuevas, J.; Fernandez Menendez, J.; Gonzalez Caballero, I.; González Fernández, J. R.; Palencia Cortezon, E.; Sanchez Cruz, S.; Vizan Garcia, J. M.; Cabrillo, I. J.; Calderon, A.; Castiñeiras De Saa, J. R.; Curras, E.; Fernandez, M.; Garcia-Ferrero, J.; Gomez, G.; Lopez Virto, A.; Marco, J.; Martinez Rivero, C.; Matorras, F.; Piedra Gomez, J.; Rodrigo, T.; Ruiz-Jimeno, A.; Scodellaro, L.; Trevisani, N.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Auffray, E.; Auzinger, G.; Bachtis, M.; Baillon, P.; Ball, A. 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B.; Schäfer, C.; Schwick, C.; Seidel, M.; Sharma, A.; Silva, P.; Simon, M.; Sphicas, P.; Steggemann, J.; Stoye, M.; Takahashi, Y.; Tosi, M.; Treille, D.; Triossi, A.; Tsirou, A.; Veckalns, V.; Veres, G. I.; Wardle, N.; Wöhri, H. K.; Zagozdzinska, A.; Zeuner, W. D.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Bachmair, F.; Bäni, L.; Bianchini, L.; Casal, B.; Dissertori, G.; Dittmar, M.; Donegà, M.; Eller, P.; Grab, C.; Heidegger, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lecomte, P.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meinhard, M. T.; Meister, D.; Micheli, F.; Musella, P.; Nessi-Tedaldi, F.; Pandolfi, F.; Pata, J.; Pauss, F.; Perrin, G.; Perrozzi, L.; Quittnat, M.; Rossini, M.; Schönenberger, M.; Starodumov, A.; Takahashi, M.; Tavolaro, V. R.; Theofilatos, K.; Wallny, R.; Aarrestad, T. K.; Amsler, C.; Caminada, L.; Canelli, M. F.; Chiochia, V.; De Cosa, A.; Galloni, C.; Hinzmann, A.; Hreus, T.; Kilminster, B.; Lange, C.; Ngadiuba, J.; Pinna, D.; Rauco, G.; Robmann, P.; Salerno, D.; Yang, Y.; Doan, T. H.; Jain, Sh.; Khurana, R.; Konyushikhin, M.; Kuo, C. M.; Lin, W.; Lu, Y. J.; Pozdnyakov, A.; Yu, S. S.; Kumar, Arun; Chang, P.; Chang, Y. H.; Chang, Y. W.; Chao, Y.; Chen, K. F.; Chen, P. H.; Dietz, C.; Fiori, F.; Hou, W.-S.; Hsiung, Y.; Liu, Y. F.; Lu, R.-S.; Miñano Moya, M.; Paganis, E.; Psallidas, A.; Tsai, J. f.; Tzeng, Y. M.; Asavapibhop, B.; Singh, G.; Srimanobhas, N.; Suwonjandee, N.; Adiguzel, A.; Cerci, S.; Damarseckin, S.; Demiroglu, Z. S.; Dozen, C.; Dumanoglu, I.; Girgis, S.; Gokbulut, G.; Guler, Y.; Gurpinar, E.; Hos, I.; Kangal, E. E.; Onengut, G.; Ozdemir, K.; Sunar Cerci, D.; Tali, B.; Topakli, H.; Turkcapar, S.; Zorbilmez, C.; Bilin, B.; Bilmis, S.; Isildak, B.; Karapinar, G.; Yalvac, M.; Zeyrek, M.; Gülmez, E.; Kaya, M.; Kaya, O.; Yetkin, E. 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T.; Jensen, F.; Johnson, A.; Krohn, M.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; Mirman, N.; Nicolas Kaufman, G.; Patterson, J. R.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Sun, W.; Tan, S. M.; Tao, Z.; Thom, J.; Tucker, J.; Wittich, P.; Winn, D.; Abdullin, S.; Albrow, M.; Apollinari, G.; Banerjee, S.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Cheung, H. W. K.; Chlebana, F.; Cihangir, S.; Cremonesi, M.; Elvira, V. D.; Fisk, I.; Freeman, J.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Hare, D.; Harris, R. M.; Hasegawa, S.; Hirschauer, J.; Hu, Z.; Jayatilaka, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kreis, B.; Lammel, S.; Linacre, J.; Lincoln, D.; Lipton, R.; Liu, T.; Lopes De Sá, R.; Lykken, J.; Maeshima, K.; Magini, N.; Marraffino, J. M.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; Newman-Holmes, C.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Ristori, L.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Das, S.; Field, R. D.; Furic, I. K.; Konigsberg, J.; Korytov, A.; Ma, P.; Matchev, K.; Mei, H.; Milenovic, P.; Mitselmakher, G.; Rank, D.; Shchutska, L.; Sperka, D.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Ackert, A.; Adams, J. R.; Adams, T.; Askew, A.; Bein, S.; Diamond, B.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Khatiwada, A.; Prosper, H.; Santra, A.; Weinberg, M.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Bucinskaite, I.; Cavanaugh, R.; Evdokimov, O.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Kurt, P.; O'Brien, C.; Sandoval Gonzalez, I. D.; Turner, P.; Varelas, N.; Wu, Z.; Zakaria, M.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Anderson, I.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Osherson, M.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; Xin, Y.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Bowen, J.; Bruner, C.; Castle, J.; Kenny, R. P.; Kropivnitskaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Sanders, S.; Stringer, R.; Tapia Takaki, J. D.; Wang, Q.; Ivanov, A.; Kaadze, K.; Khalil, S.; Makouski, M.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Toda, S.; Lange, D.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Gomez, J. A.; Hadley, N. J.; Jabeen, S.; Kellogg, R. G.; Kolberg, T.; Kunkle, J.; Lu, Y.; Mignerey, A. C.; Shin, Y. H.; Skuja, A.; Tonjes, M. B.; Tonwar, S. C.; Apyan, A.; Barbieri, R.; Baty, A.; Bi, R.; Bierwagen, K.; Brandt, S.; Busza, W.; Cali, I. A.; Demiragli, Z.; Di Matteo, L.; Gomez Ceballos, G.; Goncharov, M.; Gulhan, D.; Hsu, D.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Krajczar, K.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Marini, A. C.; Mcginn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Salfeld-Nebgen, J.; Stephans, G. S. F.; Sumorok, K.; Tatar, K.; Varma, M.; Velicanu, D.; Veverka, J.; Wang, J.; Wang, T. W.; Wyslouch, B.; Yang, M.; Zhukova, V.; Benvenuti, A. C.; Chatterjee, R. M.; Evans, A.; Finkel, A.; Gude, A.; Hansen, P.; Kalafut, S.; Kao, S. C.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bartek, R.; Bloom, K.; Bose, S.; Claes, D. R.; Dominguez, A.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Knowlton, D.; Kravchenko, I.; Meier, F.; Monroy, J.; Siado, J. E.; Snow, G. R.; Stieger, B.; Alyari, M.; Dolen, J.; George, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kaisen, J.; Kharchilava, A.; Kumar, A.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Baumgartel, D.; Chasco, M.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Teixeira De Lima, R.; Trocino, D.; Wang, R.-J.; Wood, D.; Bhattacharya, S.; Hahn, K. A.; Kubik, A.; Low, J. F.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Smith, G.; Taroni, S.; Valls, N.; Wayne, M.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Brinson, J.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Hughes, R.; Ji, W.; Liu, B.; Luo, W.; Puigh, D.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Luo, J.; Marlow, D.; Medvedeva, T.; Mooney, M.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Tully, C.; Zuranski, A.; Malik, S.; Barker, A.; Barnes, V. E.; Benedetti, D.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Jung, K.; Miller, D. H.; Neumeister, N.; Radburn-Smith, B. C.; Shi, X.; Sun, J.; Svyatkovskiy, A.; Wang, F.; Xie, W.; Xu, L.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Redjimi, R.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Betchart, B.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Chou, J. P.; Contreras-Campana, E.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hidas, D.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Nash, K.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Castaneda Hernandez, A.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Juska, E.; Kamon, T.; Krutelyov, V.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Rose, A.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Delannoy, A. G.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Sun, X.; Wang, Y.; Wolfe, E.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Lamichhane, P.; Sturdy, J.; Belknap, D. A.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Ojalvo, I.; Perry, T.; Pierro, G. A.; Polese, G.; Ruggles, T.; Savin, A.; Sharma, A.; Smith, N.; Smith, W. H.; Taylor, D.; Verwilligen, P.; Woods, N.; Bhowmik, S.; Dewanjee, R. K.; Ganguly, S.; Kumar, S.; Maity, M.; Parida, B.; Sarkar, T.</p> <p>2017-02-01</p> <p>A search is performed for Higgs-boson-mediated flavor-changing neutral <span class="hlt">currents</span> in the <span class="hlt">decays</span> of top quarks. The search is based on proton-proton collision data corresponding to an integrated luminosity of 19.7 fb-1 at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC. Events in which a top quark pair is produced with one top quark <span class="hlt">decaying</span> into a charm or up quark and a Higgs boson (H), and the other top quark <span class="hlt">decaying</span> into a bottom quark and a W boson are selected. The Higgs boson in these events is assumed to subsequently <span class="hlt">decay</span> into either dibosons or difermions. No significant excess is observed above the expected standard model background, and an upper limit at the 95% confidence level is set on the branching fraction ℬ(t → Hc) of 0.40% and ℬ(t → Hu) of 0.55%, where the expected upper limits are 0.43% and 0.40%, respectively. These results correspond to upper limits on the square of the flavor-changing Higgs boson Yukawa couplings | λ tc H |2 < 6.9 × 10- 3 and | λ tu H |2 < 9.8 × 10- 3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1336413-search-top-quark-decays-via-higgs-boson-mediated-flavor-changing-neutral-currents-pp-collisions-tev','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1336413-search-top-quark-decays-via-higgs-boson-mediated-flavor-changing-neutral-currents-pp-collisions-tev"><span>Search for top quark <span class="hlt">decays</span> via Higgs-boson-mediated flavor-changing neutral <span class="hlt">currents</span> in pp collisions at √s = 8 TeV</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; ...</p> <p>2017-02-15</p> <p>Here, a search is performed for Higgs-boson-mediated flavor-changing neutral <span class="hlt">currents</span> in the <span class="hlt">decays</span> of top quarks. The search is based on proton-proton collision data corresponding to an integrated luminosity of 19.7 fb–1 at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC. Events in which a top quark pair is produced with one top quark <span class="hlt">decaying</span> into a charm or up quark and a Higgs boson (H), and the other top quark <span class="hlt">decaying</span> into a bottom quark and a W boson are selected. The Higgs boson in these events is assumed to subsequently <span class="hlt">decay</span> into either dibosons or difermions. No significant excess is observed above the expected standard model background, and an upper limit at the 95% confidence level is set on the branching fraction B(t → Hc) of 0.40% and B(t → Hu) of 0.55%, where the expected upper limits are 0.43% and 0.40\\%, respectively. These results correspond to upper limits on the square of the flavor-changing Higgs boson Yukawa couplingsmore » $$|\\lambda^{H}_{tu}|^2$$ < 6.9E-3 and $$|\\lambda^{H}_{tu}|^2$$ < 9.8 x 10$$^{-3}$$.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1336413-search-top-quark-decays-via-higgs-boson-mediated-flavor-changing-neutral-currents-pp-collisions-sqrt-tev','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1336413-search-top-quark-decays-via-higgs-boson-mediated-flavor-changing-neutral-currents-pp-collisions-sqrt-tev"><span>Search for top quark <span class="hlt">decays</span> via Higgs-boson-mediated flavor-changing neutral <span class="hlt">currents</span> in pp collisions at $$ \\sqrt{s}=8 $$ TeV</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Khachatryan, Vardan</p> <p>2017-02-15</p> <p>A search is performed for Higgs-boson-mediated flavor-changing neutral <span class="hlt">currents</span> in the <span class="hlt">decays</span> of top quarks. The search is based on proton-proton collision data corresponding to an integrated luminosity of 19.7 inverse-femtobarns at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC. Events in which a top quark pair is produced with one top quark <span class="hlt">decaying</span> into a charm or up quark and a Higgs boson (H), and the other top quark <span class="hlt">decaying</span> into a bottom quark and a W boson are selected. The Higgs boson in these events is assumed to subsequently <span class="hlt">decay</span> into either dibosons or difermions. No significant excess is observed above the expected standard model background, and an upper limit at the 95% confidence level is set on the branching fraction B(t -> Hc) of 0.40% and B(t -> Hu) of 0.55%, where the expected upper limits are 0.43% and 0.40\\%, respectively. These results correspond to upper limits on the square of the flavor-changing Higgs boson Yukawa couplingsmore » $$|\\lambda^{H}_{tu}|^2$$ < 6.9E-3 and $$|\\lambda^{H}_{tu}|^2$$ < 9.8 x 10$$^{-3}$$.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730019709','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730019709"><span>Direct observations in the dusk hours of the characteristics of the storm-time <span class="hlt">ring</span> <span class="hlt">current</span> particles during the beginning of magnetic storms</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, P. H.; Hoffman, R. A.</p> <p>1973-01-01</p> <p>The characteristic features of the initial enhancement of the storm-time <span class="hlt">ring</span> <span class="hlt">current</span> particles in the evening hours are consistent with flow patterns resulting from a combination of inward convection, gradient drift, and corotation which carries plasma sheet protons into low L-values near midnight and the higher energy proton component into the plasmasphere and through the evening hours. Data from four magnetic storms during the early life of Explorer 45, when the local time of apogee was in the afternoon and evening hours, show that protons with lower magnetic moments penetrate deeper into the magnetosphere until a low limit, determined by the corotation and gradient drift forces, is reached. Such particle motions produce the stable energy dependent inner boundary of the <span class="hlt">ring</span> <span class="hlt">current</span> protons inside the plasmapause in the dusk sector and also provide the mechanism for energy injection into the <span class="hlt">ring</span> <span class="hlt">current</span> region. From the analyses of the pitch angle distributions it is evident that charge exchange and wave particle interactions are not the dominant causes of this inner boundary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMSM11A1553M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMSM11A1553M"><span>Low altitude emission of <span class="hlt">ring</span> <span class="hlt">current</span> ENA’s spanning 1-100 keV as observed by IMAGE and TWINS: Select case studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mackler, D. A.; Goldstein, J.; Jahn, J.; Pollock, C. J.; Redfern, J.</p> <p>2009-12-01</p> <p><span class="hlt">Ring</span> <span class="hlt">current</span> ion precipitation during the main phase of geomagnetic storms plays a role in magnetosphere/ionosphere/thermosphere coupling. This precipitation can be a regionally dominant source of energy deposition and ionization in Earths’ upper atmosphere. Charge exchange between <span class="hlt">ring</span> <span class="hlt">current</span> ions spiraling into the high latitude upper atmosphere and terrestrial neutral constituents produces a non-isotropic distribution of escaping Energetic Neutral Atoms (ENA). ENA’s produced in such a manner are no longer tied to the magnetic field, and can therefore be observed remotely by orbiting platforms. Those ENAs emitted from altitudes of several hundred km at <span class="hlt">ring</span> <span class="hlt">current</span> and/or plasma sheet magnetic footpoints often form very bright signatures, and have been referred to as Low Altitude Emissions (LAE). In this study we will build on previous work in detecting LAE signatures in the IMAGE/MENA dataset. The algorithm used in the MENA study will be modified to detect LAE signatures in IMAGE/HENA and TWINS images over an energy range covering roughly 1-100 keV. The study will initially be limited to detections using hydrogen ENA’s, with the option to expand into oxygen in future work. The operational epochs of the IMAGE and TWINS platforms allow the opportunity to select interesting periods of geomagnetic activity over most of one solar cycle to use as case studies, focusing on the relationship of LAE’s to geomagnetic storms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996DPS....28.1815M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996DPS....28.1815M"><span>On the Formation of Planetary <span class="hlt">Rings</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Molnar, L. A.; Dunn, D. E.</p> <p>1996-09-01</p> <p>A variety of arguments put forth in recent years lead to the conclusion that most, if not all, planetary <span class="hlt">rings</span> are too young to be primordial, and are evolving too rapidly to survive for the life of the solar system (see, e.g., Esposito 1993, AREPS, 21, 487, and references therein). At the same time <span class="hlt">rings</span> are ubiquitous around the giant planets. A <span class="hlt">ring</span> formation mechanism is therefore needed that can be repeated on a time scale no greater than the lifetime of the <span class="hlt">rings</span>. Several mechanisms have been suggested, but there is as yet no consensus. In this poster we consider a new hypothesis: that satellites with orbits inside the synchronous orbit serve as a reservoir of potential <span class="hlt">ring</span> material. Tides raised on the planets by these satellites will cause their orbits to <span class="hlt">decay</span> until they the satellites are fractured by tidal stress. <span class="hlt">Current</span> conditions at Uranus and Neptune are consistent with this <span class="hlt">ring</span> formation mechanism for those planets. By contrast the mechanism seems unlikely to be important for the more rapidly rotating Jupiter and Saturn.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhRvD..80e2001A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhRvD..80e2001A"><span>Search for the neutral <span class="hlt">current</span> top quark <span class="hlt">decay</span> t→Zc using the ratio of Z-boson+4jets to W-boson+4jets production</span></a></p> <p><a target="_blank" href="htt