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Sample records for collision geometry fluctuations

  1. Collision-geometry fluctuations and triangular flow in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Alver, B.; Roland, G.

    2010-05-01

    We introduce the concepts of participant triangularity and triangular flow in heavy-ion collisions, analogous to the definitions of participant eccentricity and elliptic flow. The participant triangularity characterizes the triangular anisotropy of the initial nuclear overlap geometry and arises from event-by-event fluctuations in the participant-nucleon collision points. In studies using a multiphase transport model (AMPT), a triangular flow signal is observed that is proportional to the participant triangularity and corresponds to a large third Fourier coefficient in two-particle azimuthal correlation functions. Using two-particle azimuthal correlations at large pseudorapidity separations measured by the PHOBOS and STAR experiments, we show that this Fourier component is also present in data. Ratios of the second and third Fourier coefficients in data exhibit similar trends as a function of centrality and transverse momentum as in AMPT calculations. These findings suggest a significant contribution of triangular flow to the ridge and broad away-side features observed in data. Triangular flow provides a new handle on the initial collision geometry and collective expansion dynamics in heavy-ion collisions.

  2. Collision-geometry fluctuations and triangular flow in heavy-ion collisions

    SciTech Connect

    Alver, B.; Roland, G.

    2010-05-15

    We introduce the concepts of participant triangularity and triangular flow in heavy-ion collisions, analogous to the definitions of participant eccentricity and elliptic flow. The participant triangularity characterizes the triangular anisotropy of the initial nuclear overlap geometry and arises from event-by-event fluctuations in the participant-nucleon collision points. In studies using a multiphase transport model (AMPT), a triangular flow signal is observed that is proportional to the participant triangularity and corresponds to a large third Fourier coefficient in two-particle azimuthal correlation functions. Using two-particle azimuthal correlations at large pseudorapidity separations measured by the PHOBOS and STAR experiments, we show that this Fourier component is also present in data. Ratios of the second and third Fourier coefficients in data exhibit similar trends as a function of centrality and transverse momentum as in AMPT calculations. These findings suggest a significant contribution of triangular flow to the ridge and broad away-side features observed in data. Triangular flow provides a new handle on the initial collision geometry and collective expansion dynamics in heavy-ion collisions.

  3. Riemannian geometry of fluctuation theory: An introduction

    NASA Astrophysics Data System (ADS)

    Velazquez, Luisberis

    2016-05-01

    Fluctuation geometry was recently proposed as a counterpart approach of Riemannian geometry of inference theory (information geometry), which describes the geometric features of the statistical manifold M of random events that are described by a family of continuous distributions dpξ(x|θ). This theory states a connection among geometry notions and statistical properties: separation distance as a measure of relative probabilities, curvature as a measure about the existence of irreducible statistical correlations, among others. In statistical mechanics, fluctuation geometry arises as the mathematical apparatus of a Riemannian extension of Einstein fluctuation theory, which is also closely related to Ruppeiner geometry of thermodynamics. Moreover, the curvature tensor allows to express some asymptotic formulae that account for the system fluctuating behavior beyond the gaussian approximation, while curvature scalar appears as a second-order correction of Legendre transformation between thermodynamic potentials.

  4. Measurement of quantum fluctuations in geometry

    SciTech Connect

    Hogan, Craig J.

    2008-05-15

    A particular form for the quantum indeterminacy of relative spacetime position of events is derived from the context of a holographic geometry with a minimum length at the Planck scale. The indeterminacy predicts fluctuations from a classically defined geometry in the form of ''holographic noise'' whose spatial character, absolute normalization, and spectrum are predicted with no parameters. The noise has a distinctive transverse spatial shear signature and a flat power spectral density given by the Planck time. An interferometer signal displays noise due to the uncertainty of relative positions of reflection events. The noise corresponds to an accumulation of phase offset with time that mimics a random walk of those optical elements that change the orientation of a wavefront. It only appears in measurements that compare transverse positions and does not appear at all in purely radial position measurements. A lower bound on holographic noise follows from a covariant upper bound on gravitational entropy. The predicted holographic noise spectrum is estimated to be comparable to measured noise in the currently operating interferometric gravitational-wave detector GEO600. Because of its transverse character, holographic noise is reduced relative to gravitational wave effects in other interferometer designs, such as the LIGO observatories, where beam power is much less in the beam splitter than in the arms.

  5. ELLIPTIC FLOW, INITIAL ECCENTRICITY AND ELLIPTIC FLOW FLUCTUATIONS IN HEAVY ION COLLISIONS AT RHIC.

    SciTech Connect

    NOUICER,R.; ALVER, B.; BACK, B.B.; BAKER, M.D.; BALLINTIJN, M.; BARTON, D.S.; ET AL.

    2007-02-19

    We present measurements of elliptic flow and event-by-event fluctuations established by the PHOBOS experiment. Elliptic flow scaled by participant eccentricity is found to be similar for both systems when collisions with the same number of participants or the same particle area density are compared. The agreement of elliptic flow between Au+Au and Cu+Cu collisions provides evidence that the matter is created in the initial stage of relativistic heavy ion collisions with transverse granularity similar to that of the participant nucleons. The event-by-event fluctuation results reveal that the initial collision geometry is translated into the final state azimuthal particle distribution, leading to an event-by-event proportionality between the observed elliptic flow and initial eccentricity.

  6. Determination of electron-nucleus collisions geometry with forward neutrons

    SciTech Connect

    Zheng, L.; Aschenauer, E.; Lee, J. H.

    2014-12-29

    There are a large number of physics programs one can explore in electron-nucleus collisions at a future electron-ion collider. Collision geometry is very important in these studies, while the measurement for an event-by-event geometric control is rarely discussed in the prior deep-inelastic scattering experiments off a nucleus. This paper seeks to provide some detailed studies on the potential of tagging collision geometries through forward neutron multiplicity measurements with a zero degree calorimeter. As a result, this type of geometry handle, if achieved, can be extremely beneficial in constraining nuclear effects for the electron-nucleus program at an electron-ion collider.

  7. Multiplicity fluctuations due to the temperature fluctuations in high-energy nuclear collisions

    SciTech Connect

    Wilk, Grzegorz; Wlodarczyk, Zbigniew

    2009-05-15

    We investigate the multiplicity fluctuations observed in high-energy nuclear collisions attributing them to intrinsic fluctuations of temperature of the hadronizing system formed in such processes. To account for these fluctuations, we replace the usual Boltzmann-Gibbs (BG) statistics by the nonextensive Tsallis statistics characterized by the nonextensivity parameter q, with |q-1| being a direct measure of fluctuation. In the limit of vanishing fluctuations, q{yields}1 and Tsallis statistics converge to the usual BG. We evaluate the nonextensivity parameter q and its dependence on the hadronizing system size from the experimentally observed collision centrality dependence of the mean multiplicity and its variance Var(N). We attribute the observed system size dependence of q to the finiteness of the hadronizing source, with q=1 corresponding to an infinite, thermalized source with a fixed temperature, and with q>1 (which is observed) corresponding to a finite source in which both the temperature and energy fluctuate.

  8. Geometry-induced fluctuations of olfactory searches in bounded domains

    NASA Astrophysics Data System (ADS)

    Rodríguez, Juan Duque; Gómez-Ullate, David; Mejía-Monasterio, Carlos

    2014-04-01

    In olfactory search an immobile target emits chemical molecules at constant rate. The molecules are transported by the medium, which is assumed to be turbulent. Considering a searcher able to detect such chemical signals and whose motion follows the infotaxis strategy, we study the statistics of the first-passage time to the target when the searcher moves on a finite two-dimensional lattice of different geometries. Far from the target, where the concentration of chemicals is low, the direction of the searcher's first movement is determined by the geometry of the domain and the topology of the lattice, inducing strong fluctuations on the average search time with respect to the initial position of the searcher. The domain is partitioned in well-defined regions characterized by the direction of the first movement. If the search starts over the interface between two different regions, large fluctuations in the search time are observed.

  9. Elliptic flow from collision geometry and rescattering

    SciTech Connect

    Boeggild, H.; Hansen, Ole; Humanic, T. J.

    2009-04-15

    Calculations of elliptic flow based on two initial state models of Au+Au collisions at {radical}(s)=200 GeV/n coupled with a hadronic rescattering calculation are presented. The two initial state models used are a thermal model and a partonic model. Results from these calculations are compared with experiments and it is found that both initial state models give satisfactory representations of elliptic flow measurements, provided that the rescattering is started early enough in the collision process. It is also found that the present hadronic model studies do not show the jet suppression observed experimentally.

  10. Transverse momentum versus multiplicity fluctuations in high-energy nuclear collisions

    SciTech Connect

    Mrowczynski, St.; Rybczynski, M.; Wlodarczyk, Z.

    2004-11-01

    We discuss recently measured event-by-event fluctuations of transverse momentum and of multiplicity in relativistic heavy-ion collisions. It is shown that the nonmonotonic behavior of the p{sub T} fluctuations as a function of collision centrality can be fully explained by the observed nonmonotonic multiplicity fluctuations. A possible mechanism responsible for the multiplicity fluctuations is also considered.

  11. Distribution of zeros in the rough geometry of fluctuating interfaces

    NASA Astrophysics Data System (ADS)

    Zamorategui, Arturo L.; Lecomte, Vivien; Kolton, Alejandro B.

    2016-04-01

    We study numerically the correlations and the distribution of intervals between successive zeros in the fluctuating geometry of stochastic interfaces, described by the Edwards-Wilkinson equation. For equilibrium states we find that the distribution of interval lengths satisfies a truncated Sparre-Andersen theorem. We show that boundary-dependent finite-size effects induce nontrivial correlations, implying that the independent interval property is not exactly satisfied in finite systems. For out-of-equilibrium nonstationary states we derive the scaling law describing the temporal evolution of the density of zeros starting from an uncorrelated initial condition. As a by-product we derive a general criterion of the von Neumann's type to understand how discretization affects the stability of the numerical integration of stochastic interfaces. We consider both diffusive and spatially fractional dynamics. Our results provide an alternative experimental method for extracting universal information of fluctuating interfaces such as domain walls in thin ferromagnets or ferroelectrics, based exclusively on the detection of crossing points.

  12. Distribution of zeros in the rough geometry of fluctuating interfaces.

    PubMed

    Zamorategui, Arturo L; Lecomte, Vivien; Kolton, Alejandro B

    2016-04-01

    We study numerically the correlations and the distribution of intervals between successive zeros in the fluctuating geometry of stochastic interfaces, described by the Edwards-Wilkinson equation. For equilibrium states we find that the distribution of interval lengths satisfies a truncated Sparre-Andersen theorem. We show that boundary-dependent finite-size effects induce nontrivial correlations, implying that the independent interval property is not exactly satisfied in finite systems. For out-of-equilibrium nonstationary states we derive the scaling law describing the temporal evolution of the density of zeros starting from an uncorrelated initial condition. As a by-product we derive a general criterion of the von Neumann's type to understand how discretization affects the stability of the numerical integration of stochastic interfaces. We consider both diffusive and spatially fractional dynamics. Our results provide an alternative experimental method for extracting universal information of fluctuating interfaces such as domain walls in thin ferromagnets or ferroelectrics, based exclusively on the detection of crossing points. PMID:27176265

  13. High energy particle collisions and geometry of horizon

    NASA Astrophysics Data System (ADS)

    Zaslavskii, O. B.

    2016-06-01

    We consider collision of two geodesic particles near the lightlike surface (black hole horizon or naked singularity) of such an axially symmetric rotating or static metric that the coefficient gϕϕ → 0 on this surface. It is shown that the energy in the center of mass frame Ec.m. is indefinitely large even without fine-tuning of particles’ parameters. Kinematically, this is the collision between two rapid particles that approach the horizon almost with the speed of light but at different angles (or they align along the normal to the horizon too slowly). The latter is the reason why the relative velocity tends to that of light, hence to high Ec.m.. Our approach is model-independent. It relies on general properties of geometry and is insensitive to the details of material source that supports the geometries of the type under consideration. For several particular models (the stringy black hole, the Brans-Dicke analogue of the Schwarzschild metric and the Janis-Newman-Winicour one) we recover the results found in literature previously.

  14. Hydrodynamic flow amplitude correlations in event-by-event fluctuating heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Qian, Jing; Heinz, Ulrich

    2016-08-01

    The effects of event-by-event fluctuations in the initial geometry of colliding nuclei are important in the analysis of final flow observables in relativistic heavy-ion collisions. We use hydrodynamic simulations to study the amplitude correlations between different orders of event-by-event fluctuating anisotropic flow harmonics. While the general trends seen in the experimental data are qualitatively reproduced by the model, deviations in detail, in particular for peripheral collisions, point to the need for more elaborate future calculations with a hybrid approach that describes the late hadronic stage of the evolution microscopically. It is demonstrated explicitly that the observed anticorrelation between v2 and v3 is the consequence of approximately linear hydrodynamic response to a similar anticorrelation of the corresponding initial eccentricities ɛ2 and ɛ3. For n > 3 , the hydrodynamic correlations between v2 ,3 and vn deviate from the rescaled correlations among the corresponding initial eccentricities, demonstrating a nonlinear mode coupling effect in higher-order flows.

  15. Charged Hadron Multiplicity Fluctuations in Au+Au and Cu+Cu Collisions from s_NN = 22.5 to 200 GeV

    SciTech Connect

    Adare, A.; Awes, Terry C; Cianciolo, Vince; Efremenko, Yuri; Read Jr, Kenneth F; Silvermyr, David O; Sorensen, Soren P; Stankus, Paul W; Young, Glenn R; PHENIX, Collaboration

    2008-01-01

    A comprehensive survey of event-by-event fluctuations of charged hadron multiplicity in relativistic heavy ions is presented. The survey covers Au+Au collisions at {radical}s{sub NN} = 62.4 and 200 GeV, and Cu+Cu collisions at {radical}s{sub NN} = 22.5,62.4, and 200 GeV. Fluctuations are measured as a function of collision centrality, transverse momentum range, and charge sign. After correcting for nondynamical fluctuations due to fluctuations in the collision geometry within a centrality bin, the remaining dynamical fluctuations expressed as the variance normalized by the mean tend to decrease with increasing centrality. The dynamical fluctuations are consistent with or below the expectation from a superposition of participant nucleon-nucleon collisions based upon p+p data, indicating that this dataset does not exhibit evidence of critical behavior in terms of the compressibility of the system. A comparison of the data with a model where hadrons are independently emitted from a number of hadron clusters suggests that the mean number of hadrons per cluster is small in heavy ion collisions.

  16. Causal diffusion and the survival of charge fluctuations in nuclear collisions

    SciTech Connect

    Aziz, Mohamed Abdel; Gavin, Sean

    2004-09-01

    Diffusion may obliterate fluctuation signals of the QCD phase transition in nuclear collisions at SPS and RHIC energies. We propose a hyperbolic diffusion equation to study the dissipation of net charge fluctuations. This equation is needed in a relativistic context, because the classic parabolic diffusion equation violates causality. We find that causality substantially limits the extent to which diffusion can dissipate these fluctuations.

  17. Eccentricity fluctuations from the color glass condensate in ultrarelativistic heavy ion collisions

    SciTech Connect

    Drescher, Hans-Joachim; Nara, Yasushi

    2007-10-15

    In this Rapid Communication, we determine the fluctuations of the initial eccentricity in heavy-ion collisions caused by fluctuations of the nucleon configurations. This is done via a Monte Carlo implementation of a color glass condensate k{sub t}-factorization approach. The eccentricity fluctuations are found to nearly saturate elliptic flow fluctuations measured recently at RHIC. Extrapolations to LHC energies are shown.

  18. Size fluctuations of the initial source and event-by-event transverse momentum fluctuations in relativistic heavy-ion collisions

    SciTech Connect

    Broniowski, Wojciech; Chojnacki, Mikolaj; Obara, Lukasz

    2009-11-15

    We show that the event-by-event fluctuations of the transverse size of the initial source, which follow directly from the Glauber treatment of the earliest stage of relativistic heavy-ion collisions, cause, after hydrodynamic evolution, fluctuations of the transverse flow velocity at hadronic freeze-out. This, in turn, leads to event-by-event fluctuations of the average transverse momentum, . Simulations with GLISSANDO for the Glauber phase, followed by a realistic hydrodynamic evolution and statistical hadronization carried out with THERMINATOR, lead to agreement with the Relativistic Heavy Ion Collider (RHIC) data. In particular, the magnitude of the effect, its centrality dependence, and the weak dependence on the incident energy are properly reproduced. Our results show that the bulk of the observed event-by-event fluctuations may be explained by the fluctuations of the size of the initial source.

  19. Identity method to study chemical fluctuations in relativistic heavy-ion collisions

    SciTech Connect

    Gazdzicki, Marek; Grebieszkow, Katarzyna; Mackowiak, Maja; Mrowczynski, Stanislaw

    2011-05-15

    Event-by-event fluctuations of the chemical composition of the hadronic final state of relativistic heavy-ion collisions carry valuable information on the properties of strongly interacting matter produced in the collisions. However, in experiments incomplete particle identification distorts the observed fluctuation signals. The effect is quantitatively studied and a new technique for measuring chemical fluctuations, the identity method, is proposed. The method fully eliminates the effect of incomplete particle identification. The application of the identity method to experimental data is explained.

  20. Forward-backward multiplicity fluctuations in heavy nuclei collisions in the wounded nucleon model

    SciTech Connect

    Bzdak, Adam; Wozniak, Krzysztof

    2010-03-15

    We use the wounded nucleon model to study the forward-backward multiplicity fluctuations measured by the PHOBOS Collaboration in Au + Au collisions at sq root(s{sub N{sub N}})=200 GeV. The enhancement of forward-backward fluctuations in Au + Au collisions with respect to the elementary p+p interactions is explained in this model by the asymmetric shape of the pseudorapidity density of produced particles from a single wounded nucleon and the fluctuations of the number of wounded nucleons in the colliding nuclei. The wounded nucleon model describes these experimental data better than the HIJING, AMPT, or UrQMD models do.

  1. Intrinsic fluctuations of the proton saturation momentum scale in high multiplicity p+p collisions

    NASA Astrophysics Data System (ADS)

    McLerran, Larry; Tribedy, Prithwish

    2016-01-01

    High multiplicity events in p+p collisions are studied using the theory of the Color Glass Condensate. We show that intrinsic fluctuations of the proton saturation momentum scale are needed in addition to the sub-nucleonic color charge fluctuations to explain the very high multiplicity tail of distributions in p+p collisions. The origin of such intrinsic fluctuations is presumably non-perturbative in nature. Classical Yang Mills simulations using the IP-Glasma model are performed to make quantitative estimations. We find that fluctuations as large as O(1) of the average values of the saturation momentum scale can lead to rare high multiplicity events seen in p+p data at RHIC and LHC energies. Using the available data on multiplicity distributions we try to constrain the distribution of the proton saturation momentum scale and make predictions for the multiplicity distribution in 13 TeV p+p collisions.

  2. Intrinsic fluctuations of the proton saturation momentum scale in high multiplicity p+p collisions

    SciTech Connect

    McLerran, Larry; Tribedy, Prithwish

    2015-11-02

    High multiplicity events in p+p collisions are studied using the theory of the Color Glass Condensate. Here, we show that intrinsic fluctuations of the proton saturation momentum scale are needed in addition to the sub-nucleonic color charge fluctuations to explain the very high multiplicity tail of distributions in p+p collisions. It is presumed that the origin of such intrinsic fluctuations is non-perturbative in nature. Classical Yang Mills simulations using the IP-Glasma model are performed to make quantitative estimations. Furthermore, we find that fluctuations as large as O(1) of the average values of the saturation momentum scale can lead to rare high multiplicity events seen in p+p data at RHIC and LHC energies. Using the available data on multiplicity distributions we try to constrain the distribution of the proton saturation momentum scale and make predictions for the multiplicity distribution in 13 TeV p+p collisions.

  3. Initial-state fluctuations in collisions between light and heavy ions

    NASA Astrophysics Data System (ADS)

    Welsh, Kevin; Singer, Jordan; Heinz, Ulrich

    2016-08-01

    In high-energy collisions involving small nuclei (p +p or x +Au collisions where x =p , d , or 3He) the fluctuating size, shape, and internal gluonic structure of the nucleon is shown to have a strong effect on the initial size and shape of the fireball of new matter created in the collision. A systematic study of the eccentricity coefficients describing this initial fireball state for several semirealistic models of nucleon substructure and for several practically relevant collision systems involving small nuclei is presented. The key importance of multiplicity fluctuations in such systems is pointed out. Our results show large differences from expectations based on conventional Glauber model simulations of the initial state created in such collisions.

  4. Fluctuations of conserved charges in relativistic heavy ion collisions: An introduction

    NASA Astrophysics Data System (ADS)

    Asakawa, Masayuki; Kitazawa, Masakiyo

    2016-09-01

    Bulk fluctuations of conserved charges measured by event-by-event analysis in relativistic heavy ion collisions are observables which are believed to carry significant amount of information on the hot medium created by the collisions. Active studies have been done recently experimentally, theoretically, and on the lattice. In particular, non-Gaussianity of the fluctuations has acquired much attention recently. In this review, we give a pedagogical introduction to these issues, and survey recent developments in this field of research. Starting from the definition of cumulants, basic concepts in fluctuation physics, such as thermal fluctuations in statistical mechanics and time evolution of fluctuations in diffusive systems, are described. Phenomena which are expected to occur in finite temperature and/or density QCD matter and their measurement by event-by-event analyses are also elucidated.

  5. Fluctuations in charged particle multiplicities in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Mukherjee, Maitreyee; Basu, Sumit; Choudhury, Subikash; Nayak, Tapan K.

    2016-08-01

    Multiplicity distributions of charged particles and their event-by-event fluctuations have been compiled for relativistic heavy-ion collisions from the available experimental data at Brookhaven National Laboratory and CERN and also by the use of an event generator. Multiplicity fluctuations are sensitive to QCD phase transition and to the presence of a critical point in the QCD phase diagram. In addition, multiplicity fluctuations provide baselines for other event-by-event measurements. Multiplicity fluctuation expressed in terms of the scaled variance of the multiplicity distribution is an intensive quantity, but is sensitive to the volume fluctuation of the system. The importance of the choice of narrow centrality bins and the corrections of the centrality bin-width effect for controlling volume fluctuations have been discussed. It is observed that the mean and width of the multiplicity distributions monotonically increase as functions of increasing centrality at all collision energies, whereas the multiplicity fluctuations show minimal variations with centrality. The beam-energy dependence shows that the multiplicity fluctuations have a slow rise at lower collision energies and remain constant at higher energies.

  6. Study of Kaon Isospin Fluctuations in Au+Au Collisions at STAR

    NASA Astrophysics Data System (ADS)

    Rose, Andrew

    2002-10-01

    Recent theoretical studies have suggested that in heavy ion collisions the formation of disoriented chiral condensates (DCC) may result from the restoration and subsequent re-breaking of chiral symmetry. Searches for DCC have so far focused on the pion sector with little attention given to the Kaon sector. Recently however, Kapusta has suggested the observation of enhanced production of Ω and \\overlineΩ at s_NN = 17 GeV, in Pb+Pb collisions, can in part be explained by the production of many small strange DCC regions. Gavin and Kapusta have additionally shown that strange DCCs production may induce anomalous fluctuations of the Kaon total isospin. We present a statistical analysis of Kaon isospin fluctuations in Au+Au collisions at 130- and 200-GeV measured with the STAR apparatus. The analysis is based on the ν_dyn fluctuation measure which correlates the production of neutral and charged kaons.

  7. Eccentricity fluctuation effects on elliptic flow in relativistic heavy ion collisions

    SciTech Connect

    Hirano, Tetsufumi; Nara, Yasushi

    2009-06-15

    We study effects of eccentricity fluctuations on the elliptic flow coefficient v{sub 2} at midrapidity in both Au+Au and Cu+Cu collisions at {radical}(s{sub NN})=200 GeV by using a hybrid model that combines ideal hydrodynamics for space-time evolution of the quark gluon plasma phase and a hadronic transport model for the hadronic matter. For initial conditions in hydrodynamic simulations, both the Glauber model and the color glass condensate model are employed to demonstrate the effect of initial eccentricity fluctuations originating from the nucleon position inside a colliding nucleus. The effect of eccentricity fluctuations is modest in semicentral Au+Au collisions, but significantly enhances v{sub 2} in Cu+Cu collisions.

  8. Event-shape fluctuations and flow correlations in ultra-relativistic heavy-ion collisions

    DOE PAGESBeta

    Jia, Jiangyong

    2014-12-01

    I review recent measurements of a large set of flow observables associated with event-shape fluctuations and collective expansion in heavy ion collisions. First, these flow observables are classified and experiment methods are introduced. The experimental results for each type of observables are then presented and compared to theoretical calculations. A coherent picture of initial condition and collective flow based on linear and non-linear hydrodynamic responses is derived, which qualitatively describe most experimental results. I discuss new types of fluctuation measurements that can further our understanding of the event-shape fluctuations and collective expansion dynamics.

  9. Mechanics, kinematics and geometry of pebble abrasion from binary collisions

    NASA Astrophysics Data System (ADS)

    Miller, K. L.; Jerolmack, D. J.

    2014-12-01

    As sediment is transported downstream as bedload, it collides with the bed causing sharp edges to chip and wear away, rounding the rock through the process of abrasion. Previous work has linked abrasion to downstream fining and rounding of grains, however, there has been little attempt to understand the underlying kinematics of abrasion. Furthermore, most studies neglect the fine particle produced during the abrasion process, as the initial grain gets smaller and rounder. In this research, we preform well-controlled laboratory experiments to determine the functional dependence between impact energy and mass lost from abrasion. We use a double-pendulum "Newton's Cradle" set-up to examine the abrasion between two grains and with a high-speed camera, we can quantify the impact energies during collision. Results from experiments verify that mass loss is proportional to kinetic energy. We define a material parameter that incorporates material density, Young's modulus, and tensile stress and show that this parameter is directly related to the proportionality between mass loss and energy. We identify an initial region of the mass loss curves in which abrasion is independent of energy and material properties; results suggest this region is determined by shape. We show that grain size distributions of daughter products are universal and independent of material; they follow a Weibull distribution, which is expected distribution from brittle fracture theory. Finally, scanning electron microscope (SEM) images show a thin damage zone near the surface, suggesting that collision energy is attenuated over some small skin depth. Overall, we find that pebble abrasion by collision can be characterized by two universal scaling relations - the mass loss versus energy curves and the size distribution of daughter products. Results will be useful for estimating expected abrasion rates in the field, and additionally demonstrate that low-energy collisions produce large quantities of sand

  10. Geometry-induced modification of fluctuation spectrum in quasi-two-dimensional condensates

    NASA Astrophysics Data System (ADS)

    Roy, Arko; Angom, D.

    2016-08-01

    We report the structural transformation of the low-lying spectral modes, especially the Kohn mode, from radial to circular topology as harmonic confining potential is modified to a toroidal one, and this corresponds to a transition from simply to multiply connected geometry. For this we employ the Hartree–Fock–Bogoliubov theory to examine the evolution of low energy quasiparticles. We, then, use the Hartree–Fock–Bogoliubov theory with the Popov approximation to demonstrate the two striking features of quantum and thermal fluctuations. At T = 0, the non-condensate density due to interaction induced quantum fluctuations increases with the transformation from pancake to toroidal geometry. The other feature is, there is a marked change in the density profile of the non-condensate density at finite temperatures with the modification of trapping potential. In particular, the condensate and non-condensate density distributions have overlapping maxima in the toroidal condensate, which is in stark contrast to the case of pancake geometry. The genesis of this difference lies in the nature of the thermal fluctuations.

  11. Initial state fluctuations and final state correlations in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Luzum, Matthew; Petersen, Hannah

    2014-06-01

    We review the phenomenology and theory of bulk observables in ultra-relativistic heavy-ion collisions, focusing on recent developments involving event-by-event fluctuations in the initial stages of a heavy-ion collision, and how they manifest in observed correlations. We first define the relevant observables and show how each measurement is related to underlying theoretical quantities. Then we review the prevailing picture of the various stages of a collision, including the state-of-the-art modeling of the initial stages of a collision and subsequent hydrodynamic evolution, as well as hadronic scattering and freeze-out in the later stages. We then discuss the recent results that have shaped our current understanding and identify the challenges that remain. Finally, we point out open issues and the potential for progress in the field.

  12. Elucidating the event-by-event flow fluctuations in heavy-ion collisions via the event-shape selection technique

    NASA Astrophysics Data System (ADS)

    Huo, Peng; Jia, Jiangyong; Mohapatra, Soumya

    2014-08-01

    The presence of large event-by-event flow fluctuations in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) provides an opportunity to study a broad class of flow observables. This paper explores the correlations among harmonic flow coefficients vn and their phases Φn, as well as the rapidity fluctuation of vn. The study is carried out using the Pb + Pb events generated by the multiphase transport (AMPT) model with fixed impact parameter. The overall ellipticity or triangularity of events is varied by selecting on the eccentricities ɛn or the magnitudes of the flow vector qn in a subevent for n =2 and 3, respectively. The responses of the harmonic coefficients, the event-plane correlations, and the rapidity fluctuations to the change in ɛn and qn are then systematized. Strong positive correlations are observed among all even harmonics v2, v4, and v6 (all increase with q2), between v2 and v5 (both increase with q2), and between v3 and v5 (both increase with q3), consistent with the effects of nonlinear collective response. In contrast, an anticorrelation is observed between v2 and v3 similar to that seen between ɛ2 and ɛ3. These correlation patterns are found to be independent of whether selecting on qn or ɛn, validating the ability of qn in selecting the initial geometry. A forward/backward asymmetry of vn(η) is observed for events selected on qn but not on ɛn, reflecting dynamical fluctuations exposed by the qn selection. Many event-plane correlators show good agreement between qn and ɛn selections, suggesting that their variations with qn are controlled by the change of ɛn in the initial geometry. Hence these correlators may serve as promising observables for disentangling the fluctuations generated in various stages of the evolution of the matter created in heavy ion collisions.

  13. Intrinsic fluctuations of the proton saturation momentum scale in high multiplicity p+p collisions

    DOE PAGESBeta

    McLerran, Larry; Tribedy, Prithwish

    2015-11-02

    High multiplicity events in p+p collisions are studied using the theory of the Color Glass Condensate. Here, we show that intrinsic fluctuations of the proton saturation momentum scale are needed in addition to the sub-nucleonic color charge fluctuations to explain the very high multiplicity tail of distributions in p+p collisions. It is presumed that the origin of such intrinsic fluctuations is non-perturbative in nature. Classical Yang Mills simulations using the IP-Glasma model are performed to make quantitative estimations. Furthermore, we find that fluctuations as large as O(1) of the average values of the saturation momentum scale can lead to raremore » high multiplicity events seen in p+p data at RHIC and LHC energies. Using the available data on multiplicity distributions we try to constrain the distribution of the proton saturation momentum scale and make predictions for the multiplicity distribution in 13 TeV p+p collisions.« less

  14. Sensitivity of flow harmonics to subnucleon scale fluctuations in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Noronha-Hostler, Jacquelyn; Noronha, Jorge; Gyulassy, Miklos

    2016-02-01

    In this paper a new procedure to smooth out the initial energy densities of hydrodynamics is employed to show that the initial spatial eccentricities ɛm ,n, which drive the final state flow harmonics vn, are remarkably robust with respect to variations of the underlying scale of initial energy density spatial gradients, λ , in nucleus-nucleus collisions. For √{s }=2.76 TeV Pb+Pb collisions, the ɛm ,n's (across centrality classes) change by less than 10% if the scale of fluctuations is varied from 0.1 to 1 fm. We show, using the 2+1 Lagrangian hydrodynamic code v-USPhydro, that this robustness is transferred to the final vn's computed within event-by-event viscous hydrodynamics. This indicates that the flow harmonics in nucleus-nucleus collisions are not particularly sensitive to the underlying microscopic subnucleon physics below the confinement scale. On the other hand, the eccentricities of top 1% high multiplicity √{s }=5.02 TeV p +Pb collisions are found to be very sensitive to subnucleonic scale fluctuations, which should be contrasted with the robustness found in peripheral Pb+Pb collisions with the same multiplicity.

  15. Fluctuating initial conditions in heavy ion collisions from the Glauber approach

    SciTech Connect

    Broniowski, Wojciech; Bozek, Piotr; Rybczynski, Maciej

    2007-11-15

    In the framework of the Glauber approach applied to the initial stage of ultra-relativistic heavy-ion collisions we analyze the shape parameters of the early-formed system (fireball) and their event-by-event fluctuations. We test a variety of models: the conventional wounded-nucleon model, a model admixing binary collisions to the wounded nucleons, a model with hot spots, and the hot-spot model where the deposition of energy occurs with a superimposed probability distribution. We look in detail at the so-called participant harmonic moments, {epsilon}*, obtained by an averaging procedure where in each event the system is translated to its center of mass and aligned with the major principal axis of the ellipse of inertia. Quantitative comparisons indicate substantial relative effects for {epsilon}* in variants of Glauber models. However, the dependence of the scaled standard deviation {delta}{epsilon}*/, {epsilon}* on the chosen model is weak. For all models the values range from about 0.5 for the central collisions to about 0.3-0.4 for peripheral collisions, for both gold-gold and copper-copper collisions. They are dominated by statistics and change only by 10-15% from model to model. We provide an approximate analytic expansion for the harmonic moments and their fluctuations given in terms of the fixed-axes moments. For central collisions and in the absence of correlations the expansion gives the simple formula {delta}{epsilon}*/{epsilon}*{approx_equal}{radical}(4/{pi}-1)=0.52. Similarly, we obtain expansions for the radial profiles of the higher harmonics. We investigate the relevance of the shape-fluctuation effects for jet quenching and find them important only for very central events. Finally, we make some comments of relevance for hydrodynamics, the elliptic flow, and its fluctuations. We argue how smooth hydrodynamics leads to the known result v{sub 4}{approx}v{sub 2}{sup 2} and, further, to the prediction {delta}v{sub 4}/v{sub 4}=2{delta}v{sub 2}/v{sub 2}.

  16. Velocity Fluctuations in Kinesin-1 Gliding Motility Assays Originate in Motor Attachment Geometry Variations.

    PubMed

    Palacci, Henri; Idan, Ofer; Armstrong, Megan J; Agarwal, Ashutosh; Nitta, Takahiro; Hess, Henry

    2016-08-01

    Motor proteins such as myosin and kinesin play a major role in cellular cargo transport, muscle contraction, cell division, and engineered nanodevices. Quantifying the collective behavior of coupled motors is critical to our understanding of these systems. An excellent model system is the gliding motility assay, where hundreds of surface-adhered motors propel one cytoskeletal filament such as an actin filament or a microtubule. The filament motion can be observed using fluorescence microscopy, revealing fluctuations in gliding velocity. These velocity fluctuations have been previously quantified by a motional diffusion coefficient, which Sekimoto and Tawada explained as arising from the addition and removal of motors from the linear array of motors propelling the filament as it advances, assuming that different motors are not equally efficient in their force generation. A computational model of kinesin head diffusion and binding to the microtubule allowed us to quantify the heterogeneity of motor efficiency arising from the combination of anharmonic tail stiffness and varying attachment geometries assuming random motor locations on the surface and an absence of coordination between motors. Knowledge of the heterogeneity allows the calculation of the proportionality constant between the motional diffusion coefficient and the motor density. The calculated value (0.3) is within a standard error of our measurements of the motional diffusion coefficient on surfaces with varying motor densities calibrated by landing rate experiments. This allowed us to quantify the loss in efficiency of coupled molecular motors arising from heterogeneity in the attachment geometry. PMID:27414063

  17. Thermal-mechanical fluctuations of fluid membranes in confined geometries: The case of soft confinement

    SciTech Connect

    Podgornik, R.; Parsegian, V.A. )

    1992-02-01

    By definition, membrane or macromolecular assembly is an event of molecular confinement against the configurational entropy of a disordered state. Bilayer membranes under progressive confinement experience a continual damping of undulatory fluctuations, first interpreted as a steric force (Helfrich. Z. Naturforsch. 1978). This paper uses a new, diffusion-equation formalism based on the Feynman-type variational principle to describe how direct interbilayer forces - of hydration, electrostatic double layers, and van der Waals attraction - confine membrane fluctuations. We recover theoretical results to examine measured forces in multilamellar arrays showing that [open quotes]soft[close quotes] collisions, through long-range forces, create a mutual enhancement of both the direct forces and the undulatory steric interactions. Thus, there is yet another way to resolve the old, but false, dilemma to choose between steric and direct forces driving membrane assembly. One may develop a systematic connection between bilayer charge, hydration, and flexibility and the action of configurational entropic forces. The results make clear that one should measure forces between membranes or macromolecules in a way that allows them to express their native mechanical freedom. 15 refs., 3 figs.

  18. Forward-backward multiplicity fluctuation and longitudinal harmonics in high-energy nuclear collisions

    NASA Astrophysics Data System (ADS)

    Jia, Jiangyong; Radhakrishnan, Sooraj; Zhou, Mingliang

    2016-04-01

    An analysis method is proposed to study the forward-backward (FB) multiplicity fluctuation in high-energy nuclear collisions, built on the earlier work of Bzdak and Teaney [Phys. Rev. C 87, 024906 (2013), 10.1103/PhysRevC.87.024906]. The method allows the decomposition of the centrality dependence of average multiplicity from the dynamical event-by-event (EbyE) fluctuation of multiplicity in pseudorapidity. Application of the method to AMPT (A Multi-Phase Transport model) and HIJING (Heavy Ion Jet INteraction Generator) models shows that the long-range component of the FB correlation is captured by a few longitudinal harmonics, with the first component driven by the asymmetry in the number of participating nucleons in the two colliding nuclei. The higher-order longitudinal harmonics are found to be strongly damped in AMPT compared to HIJING, due to weaker short-range correlations as well as the final-state effects present in the AMPT model. Two-particle pseudorapidity correlation reveals interesting charge-dependent short-range structures that are absent in HIJING model. The proposed method opens an avenue to elucidate the particle production mechanism and early time dynamics in heavy-ion collisions. Future analysis directions and prospects of using the pseudorapidity correlation function to understand the centrality bias in p +p , p +A, and A+A collisions are discussed.

  19. Net-Charge Fluctuations in Pb-Pb Collisions at sNN=2.76TeV

    NASA Astrophysics Data System (ADS)

    Abelev, B.; Adam, J.; Adamová, D.; Adare, A. M.; Aggarwal, M. M.; Aglieri Rinella, G.; Agocs, A. G.; Agostinelli, A.; Aguilar Salazar, S.; Ahammed, Z.; Ahmad Masoodi, A.; Ahmad, N.; Ahn, S. A.; Ahn, S. U.; Akindinov, A.; Aleksandrov, D.; Alessandro, B.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Almaráz Aviña, E.; Alme, J.; Alt, T.; Altini, V.; Altinpinar, S.; Altsybeev, I.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Anson, C.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arbor, N.; Arcelli, S.; Arend, A.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Asryan, A.; Augustinus, A.; Averbeck, R.; Awes, T. C.; Äystö, J.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bailhache, R.; Bala, R.; Baldini Ferroli, R.; Baldisseri, A.; Baldit, A.; Baltasar Dos Santos Pedrosa, F.; Bán, J.; Baral, R. C.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartke, J.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batyunya, B.; Baumann, C.; Bearden, I. G.; Beck, H.; Behera, N. K.; Belikov, I.; Bellini, F.; Bellwied, R.; Belmont-Moreno, E.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bergognon, A. A. E.; Berzano, D.; Betev, L.; Bhasin, A.; Bhati, A. K.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Bjelogrlic, S.; Blanco, F.; Blanco, F.; Blau, D.; Blume, C.; Boccioli, M.; Bock, N.; Böttger, S.; Bogdanov, A.; Bøggild, H.; Bogolyubsky, M.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Bose, S.; Bossú, F.; Botje, M.; Boyer, B.; Braidot, E.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Browning, T. A.; Broz, M.; Brun, R.; Bruna, E.; Bruno, G. 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M.; Corrales Morales, Y.; Cortese, P.; Cortés Maldonado, I.; Cosentino, M. R.; Costa, F.; Cotallo, M. E.; Crescio, E.; Crochet, P.; Cruz Alaniz, E.; Cuautle, E.; Cunqueiro, L.; Dainese, A.; Dalsgaard, H. H.; Danu, A.; Das, D.; Das, I.; Das, K.; Dash, S.; Dash, A.; De, S.; de Barros, G. O. V.; De Caro, A.; de Cataldo, G.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; Delagrange, H.; Deloff, A.; Demanov, V.; De Marco, N.; Dénes, E.; De Pasquale, S.; Deppman, A.; Erasmo, G. D.; de Rooij, R.; Diaz Corchero, M. A.; Di Bari, D.; Dietel, T.; Di Liberto, S.; Di Mauro, A.; Di Nezza, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Domínguez, I.; Dönigus, B.; Dordic, O.; Driga, O.; Dubey, A. K.; Ducroux, L.; Dupieux, P.; Dutta Majumdar, M. R.; Dutta Majumdar, A. K.; Elia, D.; Emschermann, D.; Engel, H.; Erdal, H. A.; Espagnon, B.; Estienne, M.; Esumi, S.; Evans, D.; Eyyubova, G.; Fabris, D.; Faivre, J.; Falchieri, D.; Fantoni, A.; Fasel, M.; Fearick, R.; Fedunov, A.; Fehlker, D.; Feldkamp, L.; Felea, D.; Fenton-Olsen, B.; Feofilov, G.; Fernández Téllez, A.; Ferretti, A.; Ferretti, R.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Garabatos, C.; Garcia-Solis, E.; Garishvili, I.; Gerhard, J.; Germain, M.; Geuna, C.; Gheata, A.; Gheata, M.; Ghidini, B.; Ghosh, P.; Di Giglio, C.; Gianotti, P.; Girard, M. R.; Giubellino, P.; Gladysz-Dziadus, E.; Glässel, P.; Gomez, R.; Gonschior, A.; Ferreiro, E. G.; González-Trueba, L. H.; González-Zamora, P.; Gorbunov, S.; Goswami, A.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Grajcarek, R.; Grelli, A.; Grigoras, C.; Grigoras, A.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gros, P.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerra Gutierrez, C.; Guerzoni, B.; Guilbaud, M.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Gutbrod, H.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Han, B. H.; Hanratty, L. D.; Hansen, A.; Harmanova, Z.; Harris, J. W.; Hartig, M.; Hasegan, D.; Hatzifotiadou, D.; Hayrapetyan, A.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Herrmann, N.; Hess, B. A.; Hetland, K. F.; Hicks, B.; Hille, P. T.; Hippolyte, B.; Horaguchi, T.; Hori, Y.; Hristov, P.; Hřivnáčová, I.; Huang, M.; Humanic, T. J.; Hwang, D. S.; Ichou, R.; Ilkaev, R.; Ilkiv, I.; Inaba, M.; Incani, E.; Innocenti, G. M.; Innocenti, P. G.; Ippolitov, M.; Irfan, M.; Ivan, C.; Ivanov, V.; Ivanov, M.; Ivanov, A.; Ivanytskyi, O.; Jachołkowski, A.; Jacobs, P. M.; Jang, H. J.; Jangal, S.; Janik, M. A.; Janik, R.; Jayarathna, P. H. S. Y.; Jena, S.; Jha, D. M.; Jimenez Bustamante, R. T.; Jirden, L.; Jones, P. G.; Jung, H.; Jusko, A.; Kaidalov, A. B.; Kakoyan, V.; Kalcher, S.; Kaliňák, P.; Kalliokoski, T.; Kalweit, A.; Kanaki, K.; Kang, J. H.; Kaplin, V.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karpechev, E.; Kazantsev, A.; Kebschull, U.; Keidel, R.; Khan, P.; Khan, M. M.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, D. W.; Kim, M.; Kim, M.; Kim, S. H.; Kim, D. J.; Kim, S.; Kim, J. H.; Kim, J. S.; Kim, B.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Klay, J. L.; Klein, J.; Klein-Bösing, C.; Kliemant, M.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Koch, K.; Köhler, M. K.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Konevskikh, A.; Korneev, A.; Kour, R.; Kowalski, M.; Kox, S.; Koyithatta Meethaleveedu, G.; Kral, J.; Králik, I.; Kramer, F.; Kraus, I.; Krawutschke, T.; Krelina, M.; Kretz, M.; Krivda, M.; Krizek, F.; Krus, M.; Kryshen, E.; Krzewicki, M.; Kucheriaev, Y.; Kuhn, C.; Kuijer, P. G.; Kulakov, I.; Kumar, J.; Kurashvili, P.; Kurepin, A. B.; Kurepin, A.; Kuryakin, A.; Kushpil, V.; Kushpil, S.; Kvaerno, H.; Kweon, M. J.; Kwon, Y.; Ladrón de Guevara, P.; Lakomov, I.; Langoy, R.; La Pointe, S. L.; Lara, C.; Lardeux, A.; La Rocca, P.; Lazzeroni, C.; Lea, R.; Le Bornec, Y.; Lechman, M.; Lee, S. C.; Lee, K. S.; Lee, G. R.; Lefèvre, F.; Lehnert, J.; Leistam, L.; Lenhardt, M.; Lenti, V.; León, H.; Leoncino, M.; León Monzón, I.; León Vargas, H.; Lévai, P.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Liu, L.; Loenne, P. I.; Loggins, V. R.; Loginov, V.; Lohn, S.; Lohner, D.; Loizides, C.; Loo, K. K.; Lopez, X.; López Torres, E.; Løvhøiden, G.; Lu, X.-G.; Luettig, P.; Lunardon, M.; Luo, J.; Luparello, G.; Luquin, L.; Luzzi, C.; Ma, R.; Ma, K.; Madagodahettige-Don, D. M.; Maevskaya, A.; Mager, M.; Mahapatra, D. P.; Maire, A.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manceau, L.; Mangotra, L.; Manko, V.; Manso, F.; Manzari, V.; Mao, Y.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Marín, A.; Marin Tobon, C. A.; Markert, C.; Martashvili, I.; Martinengo, P.; Martínez, M. I.; Martínez Davalos, A.; Martínez García, G.; Martynov, Y.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastromarco, M.; Mastroserio, A.; Matthews, Z. L.; Matyja, A.; Mayani, D.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; Meddi, F.; Menchaca-Rocha, A.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Milano, L.; Milosevic, J.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitu, C.; Mlynarz, J.; Mohanty, B.; Mohanty, A. K.; Molnar, L.; Montaño Zetina, L.; Monteno, M.; Montes, E.; Moon, T.; Morando, M.; Moreira De Godoy, D. A.; Moretto, S.; Morsch, A.; Muccifora, V.; Mudnic, E.; Muhuri, S.; Mukherjee, M.; Müller, H.; Munhoz, M. G.; Musa, L.; Musso, A.; Nandi, B. K.; Nania, R.; Nappi, E.; Nattrass, C.; Naumov, N. P.; Navin, S.; Nayak, T. K.; Nazarenko, S.; Nazarov, G.; Nedosekin, A.; Nicassio, M.; Niculescu, M.; Nielsen, B. S.; Niida, T.; Nikolaev, S.; Nikolic, V.; Nikulin, S.; Nikulin, V.; Nilsen, B. S.; Nilsson, M. S.; Noferini, F.; Nomokonov, P.; Nooren, G.; Novitzky, N.; Nyanin, A.; Nyatha, A.; Nygaard, C.; Nystrand, J.; Ochirov, A.; Oeschler, H.; Oh, S.; Oh, S. K.; Oleniacz, J.; Oppedisano, C.; Ortiz Velasquez, A.; Ortona, G.; Oskarsson, A.; Ostrowski, P.; Otwinowski, J.; Oyama, K.; Ozawa, K.; Pachmayer, Y.; Pachr, M.; Padilla, F.; Pagano, P.; Paić, G.; Painke, F.; Pajares, C.; Pal, S.; Pal, S. K.; Palaha, A.; Palmeri, A.; Papikyan, V.; Pappalardo, G. S.; Park, W. J.; Passfeld, A.; Pastirčák, B.; Patalakha, D. I.; Paticchio, V.; Pavlinov, A.; Pawlak, T.; Peitzmann, T.; Pereira Da Costa, H.; Pereira De Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Perez Lezama, E.; Perini, D.; Perrino, D.; Peryt, W.; Pesci, A.; Peskov, V.; Pestov, Y.; Petráček, V.; Petran, M.; Petris, M.; Petrov, P.; Petrovici, M.; Petta, C.; Piano, S.; Piccotti, A.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Pitz, N.; Piyarathna, D. B.; Płoskoń, M.; Pluta, J.; Pocheptsov, T.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polák, K.; Polichtchouk, B.; Pop, A.; Porteboeuf-Houssais, S.; Pospíšil, V.; Potukuchi, B.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puchagin, S.; Puddu, G.; Pujol Teixido, J.; Pulvirenti, A.; Punin, V.; Putiš, M.; Putschke, J.; Quercigh, E.; Qvigstad, H.; Rachevski, A.; Rademakers, A.; Radomski, S.; Räihä, T. S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Ramírez Reyes, A.; Raniwala, S.; Raniwala, R.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Real, J. S.; Redlich, K.; Reichelt, P.; Reicher, M.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Rettig, F.; Revol, J.-P.; Reygers, K.; Riccati, L.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Rodrigues Fernandes Rabacal, B.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Rosnet, P.; Rossegger, S.; Rossi, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Ryabinkin, E.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahoo, R.; Sahu, P. K.; Saini, J.; Sakaguchi, H.; Sakai, S.; Sakata, D.; Salgado, C. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sanchez Castro, X.; Šándor, L.; Sandoval, A.; Sano, S.; Sano, M.; Santo, R.; Santoro, R.; Sarkamo, J.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schreiner, S.; Schuchmann, S.; Schukraft, J.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Scott, P. A.; Segato, G.; Selyuzhenkov, I.; Senyukov, S.; Seo, J.; Serci, S.; Serradilla, E.; Sevcenco, A.; Shabetai, A.; Shabratova, G.; Shahoyan, R.; Sharma, N.; Sharma, S.; Rohni, S.; Shigaki, K.; Shimomura, M.; Shtejer, K.; Sibiriak, Y.; Siciliano, M.; Sicking, E.; Siddhanta, S.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, T.; Sinha, B. C.; Sitar, B.; Sitta, M.; Skaali, T. B.; Skjerdal, K.; Smakal, R.; Smirnov, N.; Snellings, R. J. M.; Søgaard, C.; Soltz, R.; Son, H.; Song, M.; Song, J.; Soos, C.; Soramel, F.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Srivastava, B. K.; Stachel, J.; Stan, I.; Stan, I.; Stefanek, G.; Steinbeck, T.; Steinpreis, M.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Stolpovskiy, M.; Strabykin, K.; Strmen, P.; Suaide, A. A. P.; Subieta Vásquez, M. A.; Sugitate, T.; Suire, C.; Sukhorukov, M.; Sultanov, R.; Šumbera, M.; Susa, T.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szostak, A.; Szymanski, M.; Takahashi, J.; Tapia Takaki, J. D.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terrevoli, C.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Tlusty, D.; Toia, A.; Torii, H.; Toscano, L.; Truesdale, D.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ulery, J.; Ullaland, K.; Ulrich, J.; Uras, A.; Urbán, J.; Urciuoli, G. M.; Usai, G. L.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; van der Kolk, N.; Vande Vyvre, P.; van Leeuwen, M.; Vannucci, L.; Vargas, A.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vechernin, V.; Veldhoen, M.; Venaruzzo, M.; Vercellin, E.; Vergara, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Vikhlyantsev, O.; Vilakazi, Z.; Villalobos Baillie, O.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Viyogi, Y. P.; Vodopyanov, A.; Voloshin, K.; Voloshin, S.; Volpe, G.; von Haller, B.; Vranic, D.; Øvrebekk, G.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, V.; Wagner, B.; Wan, R.; Wang, M.; Wang, D.; Wang, Y.; Wang, Y.; Watanabe, K.; Weber, M.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilk, A.; Williams, M. C. S.; Windelband, B.; Xaplanteris Karampatsos, L.; Yaldo, C. G.; Yamaguchi, Y.; Yang, H.; Yang, S.; Yasnopolskiy, S.; Yi, J.; Yin, Z.; Yoo, I.-K.; Yoon, J.; Yu, W.; Yuan, X.; Yushmanov, I.; Zach, C.; Zampolli, C.; Zaporozhets, S.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zelnicek, P.; Zgura, I. S.; Zhalov, M.; Zhang, X.; Zhang, H.; Zhou, F.; Zhou, D.; Zhou, Y.; Zhu, J.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zinovjev, G.; Zoccarato, Y.; Zynovyev, M.; Zyzak, M.

    2013-04-01

    We report the first measurement of the net-charge fluctuations in Pb-Pb collisions at sNN=2.76TeV, measured with the ALICE detector at the CERN Large Hadron Collider. The dynamical fluctuations per unit entropy are observed to decrease when going from peripheral to central collisions. An additional reduction in the amount of fluctuations is seen in comparison to the results from lower energies. We examine the dependence of fluctuations on the pseudorapidity interval, which may account for the dilution of fluctuations during the evolution of the system. We find that the fluctuations at the LHC are smaller compared to the measurements at the BNL Relativistic Heavy Ion Collider, and as such, closer to what has been theoretically predicted for the formation of a quark-gluon plasma.

  20. Calculation of Electronic Absorption Spectra with Account of Thermal Geometry Fluctuations

    NASA Astrophysics Data System (ADS)

    Guzha, Maris V.; Svitenkov, Andrew I.

    2016-08-01

    An influence of thermal fluctuations of molecule's geometry on calculated electronic-absorption Vis/Uv spectra is considered. Paper presents the quantum chemical modeling of the electronic-absorption spectra for the collection of graphene samples (44, 56, 60, 68 atoms). The calculations were performed by time dependent density functional theory (TDDFT) method in combination with molecular dynamics (MD) simulation at T=300 K. The noticeable changing of spectra relative to single point TDDFT calculation was discovered for two of four structures. We associate achieved results with perturbation of hydrogen and carbon atoms on the edges of the structures. We believe that suggested methodology will be useful in application engineering researches of novel molecules and molecular complexes.

  1. Constraints on models for the initial collision geometry in ultrarelativistic heavy ion collisions

    SciTech Connect

    Lacey, Roy A.; Jia, J.; Wei, Rui; Ajitanand, N. N.; Alexander, J. M.; Gong, X.; Taranenko, A.; Pak, R.; Stoecker, Horst

    2010-06-15

    Monte Carlo simulations are used to compute the centrality dependence of the collision zone eccentricities (epsilon{sub 2,4}), for both spherical and deformed ground state nuclei, for different model scenarios. Sizable model dependent differences are observed. They indicate that measurements of the second and fourth order Fourier flow coefficients v{sub 2,4}, expressed as the ratio (v{sub 4}/(v{sub 2}){sup 2}), can provide robust constraints for distinguishing between different theoretical models for the initial-state eccentricity. Such constraints could remove one of the largest impediments to a more precise determination of the specific viscosity from precision v{sub 2,4} measurements at the Relativistic Heavy Ion Collider (RHIC).

  2. Constraints on models for the initial collisions geometry in ultrarelativistic heavy ion collisions

    SciTech Connect

    Lacey, R.; Wei, R.; Ajitanand, N.; Alesander, J.; Gong, X.; Jia, J.; Tarandenko, A.; Pak, R.; Stocker, H.

    2010-06-01

    Monte Carlo simulations are used to compute the centrality dependence of the collision zone eccentricities ({var_epsilon}{sub 2,4}), for both spherical and deformed ground state nuclei, for different model scenarios. Sizable model dependent differences are observed. They indicate that measurements of the second and fourth order Fourier flow coefficients v{sub 2,4}, expressed as the ratio v{sub 4}/(v{sub 2}){sup 2}, can provide robust constraints for distinguishing between different theoretical models for the initial-state eccentricity. Such constraints could remove one of the largest impediments to a more precise determination of the specific viscosity from precision v{sub 2,4} measurements at the Relativistic Heavy Ion Collider (RHIC).

  3. Fluctuation analysis of relativistic nucleus-nucleus collisions in emulsion chambers

    NASA Technical Reports Server (NTRS)

    Mcguire, Stephen C.

    1988-01-01

    An analytical technique was developed for identifying enhanced fluctuations in the angular distributions of secondary particles produced from relativistic nucleus-nucleus collisions. The method is applied under the assumption that the masses of the produced particles are small compared to their linear momenta. The importance of particles rests in the fact that enhanced fluctuations in the rapidity distributions is considered to be an experimental signal for the creation of the quark-gluon-plasma (QGP), a state of nuclear matter predicted from the quantum chromodynamics theory (QCD). In the approach, Monte Carlo simulations are employed that make use of a portable random member generator that allow the calculations to be performed on a desk-top computer. The method is illustrated with data taken from high altitude emulsion exposures and is immediately applicable to similar data from accelerator-based emulsion exposures.

  4. Fluctuations and the rapidity dependence of charged particles spectra in fixed centrality bins in p A collisions

    NASA Astrophysics Data System (ADS)

    McLerran, Larry; Praszalowicz, Michal

    2016-09-01

    We argue that large fluctuations in the saturation momentum are necessary to explain the ATLAS and ALICE data on p A collisions measured at the LHC. Using a form for the distribution of fluctuations motivated by theoretical studies of the non-linear evolution equations for the Color Glass Condensate, we find a remarkably good agreement between theory and the measured distributions. If the saturation momentum fluctuates, we argue that the cross section for a proton probe should also fluctuate, consistent with previous observations.

  5. Superhorizon fluctuations and acoustic oscillations in relativistic heavy-ion collisions

    SciTech Connect

    Mishra, Ananta P.; Mohapatra, Ranjita K.; Saumia, P. S.; Srivastava, Ajit M.

    2008-06-15

    We focus on the initial-state spatial anisotropies, originating at the thermalization stage, for central collisions in relativistic heavy-ion collisions. We propose that a plot of the root-mean-square values of the flow coefficients {radical}(v{sub n}{sup 2}){identical_to}v{sub n}{sup rms}, calculated in a laboratory fixed coordinate system, for a large range of n from 1 to about 30, can give nontrivial information about the initial stages of the system and its evolution. We also argue that for all wavelengths {lambda} of the anisotropy (at the surface of the plasma region) much larger than the acoustic horizon size H{sub s}{sup fr} at the freeze-out stage, the resulting values of v{sub n}{sup rms} should be suppressed by a factor of order 2H{sub s}{sup fr}/{lambda}. For noncentral collisions, these arguments naturally imply a certain amount of suppression of the elliptic flow. Further, by assuming that initial flow velocities are negligible at thermalization stage, we discuss the possibility that the resulting flow could show imprints of coherent oscillations in the plot of v{sub n}{sup rms} for subhorizon modes. For gold-gold collision at 200 GeV/nucleon center-of-mass energy, these features are expected to occur for n{>=}5, with n<4 modes showing suppression due to being superhorizon. This has strong similarities with the physics of the anisotropies of the cosmic microwave background radiation (CMBR) resulting from inflationary density fluctuations in the universe (despite important differences such as the absence of gravity effects for the heavy-ion case). It seems possible that the statistical fluctuations due to finite multiplicity may not be able to mask such features in the flow data or at least a nontrivial overall shape of the plot of v{sub n}{sup rms} may be inferred. In that case, the successes of analysis of CMBR anisotropy power spectrum to get cosmological parameters can be applied for relativistic heavy-ion collisions to learn about various relevant

  6. Fate of the initial state perturbations in heavy ion collisions. II. Glauber fluctuations and sounds

    SciTech Connect

    Staig, Pilar; Shuryak, Edward

    2011-09-15

    Heavy-ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) are well described by the (nearly ideal) hydrodynamics for average events. In the present paper we study initial state fluctuations appearing on an event-by-event basis and the propagation of perturbations induced by them. We found that (i) fluctuations of several of the lowest harmonics have comparable magnitudes and (ii) that at least all odd harmonics are correlated in phase, (iii) thus indicating the local nature of fluctuations. We argue that such local perturbations should be the source of the ''tiny bang,'' a pulse of sound propagating from it. We identify its two fundamental scales as (i) the ''sound horizon'' (analogous to the absolute ruler in cosmic microwave background and galaxy distributions) and (ii) the ''viscous horizon'' separating damped and undamped harmonics. We then qualitatively describe how one can determine them from the data and thus determine two fundamental parameters of the matter: the (average) speed of sound and viscosity. The rest of the paper explains how one can study mutual coherence of various harmonics. For that, one should go beyond the two-particle correlations to three (or more) particles. Mutual coherence is important for the picture of propagating sound waves.

  7. Coulomb three-body effects in ([ital e],2[ital e]) collisions: The ionization of H in coplanar symmetric geometry

    SciTech Connect

    Whelan, C.T.; Allan, R.J.; Rasch, J.; Walters, H.R.J.; Zhang, X.; Roeder, J.; Jung, K.; Ehrhardt, H. Daresbury Laboratory, Warrington WA4 4AD Department of Applied Mathematics and Theoretical Physics, The Queen's University of Belfast, BT7 1NN Belfast, Northern Ireland Fachbereich Physik, Universitaet Kaiserslautern, Erwin Schroedinger Strasse, D6750, Kaiserslautern )

    1994-11-01

    The role of postcollisional and polarization-correlation effects in energy-sharing ([ital e],2[ital e]) collisions is considered. Theoretical and experimental results are presented for the ionization of hydrogen in a symmetric coplanar geometry. A kinematical regime is identified where the triple-differential cross section is sensitive to three-body effects in both the incident and final channels.

  8. Second order and fluctuating hydrodynamic theory of two-particle transverse momentum correlations in nuclear collisions

    NASA Astrophysics Data System (ADS)

    Pokharel, Rajendra K.

    Relativistic heavy ion collision experiments show clear evidence of creation of a very short-lived phase of nuclear matter consisting of color-deconfined quarks and gluons. This matter is known as the quark-gluon plasma (QGP). Fluctuation and correlation measurements of the detected particles have played a very important role in revealing the properties of QGP. In particular, these measurements have shown that the QGP behaves like a nearly perfect liquid. Relativistic hydrodynamics has been successfully used to study how the QGP evolves before the system hadronizes and ultimately produces the final state particles. Transport properties like shear viscosity constitute an important part in such studies. This work is focused on developing a second order hydrodynamic theory for the evolution of two-particle transverse momentum correlations. We use general temperature dependent transport and relaxation coefficients as well as the latest information on equations of state and use both first and second order relativistic viscous hydrodynamics to compute experimentally measurable observables. We will show that our computations using the second order viscous hydrodynamics are in good agreement with experimental data. We also highlight some features that distinguish the second order viscous hydrodynamic evolution of QGP from the first order.

  9. The Facts Are on the Table: Analyzing the Geometry of Coin Collisions

    ERIC Educational Resources Information Center

    Theilmann, Florian

    2014-01-01

    In a typical high school course, the complex physics of collisions is broken up into the dichotomy of perfectly elastic versus completely inelastic collisions. Real-life collisions, however, generally fall between these two extremes. An accurate treatment is still possible, as demonstrated in an investigation of coin collisions. Simple…

  10. Spatially adaptive stochastic methods for fluid-structure interactions subject to thermal fluctuations in domains with complex geometries

    SciTech Connect

    Plunkett, Pat; Hu, Jonathan; Siefert, Christopher; Atzberger, Paul J.

    2014-08-07

    We develop stochastic mixed finite element methods for spatially adaptive simulations of fluid–structure interactions when subject to thermal fluctuations. To account for thermal fluctuations, we introduce a discrete fluctuation–dissipation balance condition to develop compatible stochastic driving fields for our discretization. We also perform analysis that shows our condition is sufficient to ensure results consistent with statistical mechanics. We show the Gibbs–Boltzmann distribution is invariant under the stochastic dynamics of the semi-discretization. To generate efficiently the required stochastic driving fields, we develop a Gibbs sampler based on iterative methods and multigrid to generate fields with O(N) computational complexity. Our stochastic methods provide an alternative to uniform discretizations on periodic domains that rely on Fast Fourier Transforms. To demonstrate in practice our stochastic computational methods, we investigate within channel geometries having internal obstacles and no-slip walls how the mobility/diffusivity of particles depends on location. Furthermore, our methods extend the applicability of fluctuating hydrodynamic approaches by allowing for spatially adaptive resolution of the mechanics and for domains that have complex geometries relevant in many applications.

  11. Spatially adaptive stochastic methods for fluid–structure interactions subject to thermal fluctuations in domains with complex geometries

    SciTech Connect

    Plunkett, Pat; Hu, Jonathan; Siefert, Christopher; Atzberger, Paul J.

    2014-11-15

    We develop stochastic mixed finite element methods for spatially adaptive simulations of fluid–structure interactions when subject to thermal fluctuations. To account for thermal fluctuations, we introduce a discrete fluctuation–dissipation balance condition to develop compatible stochastic driving fields for our discretization. We perform analysis that shows our condition is sufficient to ensure results consistent with statistical mechanics. We show the Gibbs–Boltzmann distribution is invariant under the stochastic dynamics of the semi-discretization. To generate efficiently the required stochastic driving fields, we develop a Gibbs sampler based on iterative methods and multigrid to generate fields with O(N) computational complexity. Our stochastic methods provide an alternative to uniform discretizations on periodic domains that rely on Fast Fourier Transforms. To demonstrate in practice our stochastic computational methods, we investigate within channel geometries having internal obstacles and no-slip walls how the mobility/diffusivity of particles depends on location. Our methods extend the applicability of fluctuating hydrodynamic approaches by allowing for spatially adaptive resolution of the mechanics and for domains that have complex geometries relevant in many applications.

  12. Forward-backward multiplicity correlations caused by centrality fluctuations in high-energy heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    He, Ronghua; Qian, Jing; Huo, Lei

    2016-04-01

    We consider that most of the long-range forward-backward multiplicity (FB) correlations in high energy A -A collisions are caused by the centrality fluctuation, and this phenomenon interferes with the measurement of the dynamical correlations greatly. We investigate the relationship between FB correlation strength and centrality by a Monte Carlo simulation and a derivation which are tested by A MultiPhases Transport (AMPT) model in Au+Au collisions at √{sNN}=200 GeV. We compare the FB correlation strengths of AMPT model with the results of the derivation at √{sNN} = 7.7 to 200 GeV. A comparison between the default AMPT model and string melting AMPT model with different partonic scattering sections is made. As a result, we consider that the FB correlation strengths may be dominated by the mixing of different centrality events, and the short-range correlation may be overwhelmed for the most central collisions.

  13. Event-by-Event Fluctuations of Azimuthal Particle Anisotropy in Au+Au Collisions at {radical}(s{sub NN})=200 GeV

    SciTech Connect

    Alver, B.; Ballintijn, M.; Busza, W.; Decowski, M. P.; Gulbrandsen, K.; Henderson, C.; Kane, J. L.; Kulinich, P.; Li, W.; Loizides, C.; Reed, C.; Roland, C.; Roland, G.; Stephans, G. S. F.; Vale, C.; Nieuwenhuizen, G. J. van; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wenger, E.

    2010-04-09

    This Letter presents the first measurement of event-by-event fluctuations of the elliptic flow parameter v{sub 2} in Au+Au collisions at {radical}(s{sub NN})=200 GeV as a function of collision centrality. The relative nonstatistical fluctuations of the v{sub 2} parameter are found to be approximately 40%. The results, including contributions from event-by-event elliptic flow fluctuations and from azimuthal correlations that are unrelated to the reaction plane (nonflow correlations), establish an upper limit on the magnitude of underlying elliptic flow fluctuations. This limit is consistent with predictions based on spatial fluctuations of the participating nucleons in the initial nuclear overlap region. These results provide important constraints on models of the initial state and hydrodynamic evolution of relativistic heavy ion collisions.

  14. 3D Geometry and Kinematics of the Taiwan Arc-continent Collision

    NASA Astrophysics Data System (ADS)

    Carena, S.; Suppe, J.; Wu, Y. M.

    2015-12-01

    In Taiwan two subduction zones (Manila trench and Ryukyu trench) come together in a quasi-orthogonal, kinematically stable configuration. Subduction is ongoing in both trenches, even though the tectonic setting in the Manila trench is that of an arc-continent collision. The upper crust of Eurasia (EU) is decoupled from the rest of the lithosphere by a detachment horizon, which is the main subduction interface between EU and Philippine Sea plate (PSP). The interface is visible in both seismicity and crustal tomography at shallow depths, and it can be followed into the mantle to 450-500 km depth with global tomography. Shortening across the plate boundary is accomplished by a combination of subduction of EU lithosphere, folding and thrusting in the Eurasian upper crust, and a secondary subduction zone within the PSP. We hypothesize that: (1) once arc-continent collision occurs, subduction of Eurasian continental lower crust and upper mantle can continue by lithospheric delamination and by continuity with the much larger Eurasian slab to the south; (2) the upper crust of EU deforms by faulting and folding; (3) the present convergence rate of about 90 mm/yr is limited at most to the last 2 Ma, whereas the long-term rate is about 30 mm/yr and in Taiwan the difference is being taken up by secondary subduction within the PSP margin; (4) a margin-parallel STEP (Subduction-Transform-Edge-Propagator) fault forms the northern limit of Eurasian subduction, which allows the whole system to propagate self-similarly southwestward. No slab breakoff is required for the kinematics of the margin, and none is observed in geophysical or geological data either. This kinematics is consistent with geologic observations: from timing of opening of the southern Okinawa trough, to geometry of geologic boundaries within the Taiwan mountain belt, to geographic distribution, geochemical character, and timing of Quaternary volcanism in the northern Taiwan volcanic zone. We constrained the long

  15. Net-charge fluctuations in Pb-Pb collisions at sqrt[sNN]=2.76  TeV.

    PubMed

    Abelev, B; Adam, J; Adamová, D; Adare, A M; Aggarwal, M M; Aglieri Rinella, G; Agocs, A G; Agostinelli, A; Aguilar Salazar, S; Ahammed, Z; Ahmad Masoodi, A; Ahmad, N; Ahn, S A; Ahn, S U; Akindinov, A; Aleksandrov, D; Alessandro, B; Alfaro Molina, R; Alici, A; Alkin, A; Almaráz Aviña, E; Alme, J; Alt, T; Altini, V; Altinpinar, S; Altsybeev, I; Andrei, C; Andronic, A; Anguelov, V; Anielski, J; Anson, C; Antičić, T; Antinori, F; Antonioli, P; Aphecetche, L; Appelshäuser, H; Arbor, N; Arcelli, S; Arend, A; Armesto, N; Arnaldi, R; Aronsson, T; Arsene, I C; Arslandok, M; Asryan, A; Augustinus, A; Averbeck, R; Awes, T C; Äystö, J; Azmi, M D; Bach, M; Badalà, A; Baek, Y W; Bailhache, R; Bala, R; Baldini Ferroli, R; Baldisseri, A; Baldit, A; Baltasar Dos Santos Pedrosa, F; Bán, J; Baral, R C; Barbera, R; Barile, F; Barnaföldi, G G; Barnby, L S; Barret, V; Bartke, J; Basile, M; Bastid, N; Basu, S; Bathen, B; Batigne, G; Batyunya, B; Baumann, C; Bearden, I G; Beck, H; Behera, N K; Belikov, I; Bellini, F; Bellwied, R; Belmont-Moreno, E; Bencedi, G; Beole, S; Berceanu, I; Bercuci, A; Berdnikov, Y; Berenyi, D; Bergognon, A A E; Berzano, D; Betev, L; Bhasin, A; Bhati, A K; Bhom, J; Bianchi, L; Bianchi, N; Bianchin, C; Bielčík, J; Bielčíková, J; Bilandzic, A; Bjelogrlic, S; Blanco, F; Blanco, F; Blau, D; Blume, C; Boccioli, M; Bock, N; Böttger, S; Bogdanov, A; Bøggild, H; Bogolyubsky, M; Boldizsár, L; Bombara, M; Book, J; Borel, H; Borissov, A; Bose, S; Bossú, F; Botje, M; Boyer, B; Braidot, E; Braun-Munzinger, P; Bregant, M; Breitner, T; Browning, T A; Broz, M; Brun, R; Bruna, E; Bruno, G E; Budnikov, D; Buesching, H; Bufalino, S; Bugaiev, K; Busch, O; Buthelezi, Z; Caballero Orduna, D; Caffarri, D; Cai, X; Caines, H; Calvo Villar, E; Camerini, P; Canoa Roman, V; Cara Romeo, G; Carena, F; Carena, W; Carlin Filho, N; Carminati, F; Carrillo Montoya, C A; Casanova Díaz, A; Castillo Castellanos, J; Castillo Hernandez, J F; Casula, E A R; Catanescu, V; Cavicchioli, C; Ceballos Sanchez, C; Cepila, J; Cerello, P; Chang, B; Chapeland, S; Charvet, J L; Chattopadhyay, S; Chattopadhyay, S; Chawla, I; Cherney, M; Cheshkov, C; Cheynis, B; Chibante Barroso, V; Chinellato, D D; Chochula, P; Chojnacki, M; Choudhury, S; Christakoglou, P; Christensen, C H; Christiansen, P; Chujo, T; Chung, S U; Cicalo, C; Cifarelli, L; Cindolo, F; Cleymans, J; Coccetti, F; Colamaria, F; Colella, D; Conesa Balbastre, G; Conesa del Valle, Z; Constantin, P; Contin, G; Contreras, J G; Cormier, T M; Corrales Morales, Y; Cortese, P; Cortés Maldonado, I; Cosentino, M R; Costa, F; Cotallo, M E; Crescio, E; Crochet, P; Cruz Alaniz, E; Cuautle, E; Cunqueiro, L; Dainese, A; Dalsgaard, H H; Danu, A; Das, D; Das, I; Das, K; Dash, S; Dash, A; De, S; de Barros, G O V; De Caro, A; de Cataldo, G; de Cuveland, J; De Falco, A; De Gruttola, D; Delagrange, H; Deloff, A; Demanov, V; De Marco, N; Dénes, E; De Pasquale, S; Deppman, A; Erasmo, G D; de Rooij, R; Diaz Corchero, M A; Di Bari, D; Dietel, T; Di Liberto, S; Di Mauro, A; Di Nezza, P; Divià, R; Djuvsland, Ø; Dobrin, A; Dobrowolski, T; Domínguez, I; Dönigus, B; Dordic, O; Driga, O; Dubey, A K; Ducroux, L; Dupieux, P; Dutta Majumdar, M R; Dutta Majumdar, A K; Elia, D; Emschermann, D; Engel, H; Erdal, H A; Espagnon, B; Estienne, M; Esumi, S; Evans, D; Eyyubova, G; Fabris, D; Faivre, J; Falchieri, D; Fantoni, A; Fasel, M; Fearick, R; Fedunov, A; Fehlker, D; Feldkamp, L; Felea, D; Fenton-Olsen, B; Feofilov, G; Fernández Téllez, A; Ferretti, A; Ferretti, R; Figiel, J; Figueredo, M A S; Filchagin, S; Finogeev, D; Fionda, F M; Fiore, E M; Floris, M; Foertsch, S; Foka, P; Fokin, S; Fragiacomo, E; Frankenfeld, U; Fuchs, U; Furget, C; Fusco Girard, M; Gaardhøje, J J; Gagliardi, M; Gago, A; Gallio, M; Gangadharan, D R; Ganoti, P; Garabatos, C; Garcia-Solis, E; Garishvili, I; Gerhard, J; Germain, M; Geuna, C; Gheata, A; Gheata, M; Ghidini, B; Ghosh, P; Di Giglio, C; Gianotti, P; Girard, M R; Giubellino, P; Gladysz-Dziadus, E; Glässel, P; Gomez, R; Gonschior, A; Ferreiro, E G; González-Trueba, L H; González-Zamora, P; Gorbunov, S; Goswami, A; Gotovac, S; Grabski, V; Graczykowski, L K; Grajcarek, R; Grelli, A; Grigoras, C; Grigoras, A; Grigoriev, V; Grigoryan, A; Grigoryan, S; Grinyov, B; Grion, N; Gros, P; Grosse-Oetringhaus, J F; Grossiord, J-Y; Grosso, R; Guber, F; Guernane, R; Guerra Gutierrez, C; Guerzoni, B; Guilbaud, M; Gulbrandsen, K; Gunji, T; Gupta, A; Gupta, R; Gutbrod, H; Haaland, Ø; Hadjidakis, C; Haiduc, M; Hamagaki, H; Hamar, G; Han, B H; Hanratty, L D; Hansen, A; Harmanova, Z; Harris, J W; Hartig, M; Hasegan, D; Hatzifotiadou, D; Hayrapetyan, A; Heckel, S T; Heide, M; Helstrup, H; Herghelegiu, A; Herrera Corral, G; Herrmann, N; Hess, B A; Hetland, K F; Hicks, B; Hille, P T; Hippolyte, B; Horaguchi, T; Hori, Y; Hristov, P; Hřivnáčová, I; Huang, M; Humanic, T J; Hwang, D S; Ichou, R; Ilkaev, R; Ilkiv, I; Inaba, M; Incani, E; Innocenti, G M; Innocenti, P G; Ippolitov, M; Irfan, M; Ivan, C; Ivanov, V; Ivanov, M; Ivanov, A; Ivanytskyi, O; Jachołkowski, A; Jacobs, P M; Jang, H J; Jangal, S; Janik, M A; Janik, R; Jayarathna, P H S Y; Jena, S; Jha, D M; Jimenez Bustamante, R T; Jirden, L; Jones, P G; Jung, H; Jusko, A; Kaidalov, A B; Kakoyan, V; Kalcher, S; Kaliňák, P; Kalliokoski, T; Kalweit, A; Kanaki, K; Kang, J H; Kaplin, V; Karasu Uysal, A; Karavichev, O; Karavicheva, T; Karpechev, E; Kazantsev, A; Kebschull, U; Keidel, R; Khan, P; Khan, M M; Khan, S A; Khanzadeev, A; Kharlov, Y; Kileng, B; Kim, D W; Kim, M; Kim, M; Kim, S H; Kim, D J; Kim, S; Kim, J H; Kim, J S; Kim, B; Kim, T; Kirsch, S; Kisel, I; Kiselev, S; Kisiel, A; Klay, J L; Klein, J; Klein-Bösing, C; Kliemant, M; Kluge, A; Knichel, M L; Knospe, A G; Koch, K; Köhler, M K; Kolojvari, A; Kondratiev, V; Kondratyeva, N; Konevskikh, A; Korneev, A; Kour, R; Kowalski, M; Kox, S; Koyithatta Meethaleveedu, G; Kral, J; Králik, I; Kramer, F; Kraus, I; Krawutschke, T; Krelina, M; Kretz, M; Krivda, M; Krizek, F; Krus, M; Kryshen, E; Krzewicki, M; Kucheriaev, Y; Kuhn, C; Kuijer, P G; Kulakov, I; Kumar, J; Kurashvili, P; Kurepin, A B; Kurepin, A; Kuryakin, A; Kushpil, V; Kushpil, S; Kvaerno, H; Kweon, M J; Kwon, Y; Ladrón de Guevara, P; Lakomov, I; Langoy, R; La Pointe, S L; Lara, C; Lardeux, A; La Rocca, P; Lazzeroni, C; Lea, R; Le Bornec, Y; Lechman, M; Lee, S C; Lee, K S; Lee, G R; Lefèvre, F; Lehnert, J; Leistam, L; Lenhardt, M; Lenti, V; León, H; Leoncino, M; León Monzón, I; León Vargas, H; Lévai, P; Lien, J; Lietava, R; Lindal, S; Lindenstruth, V; Lippmann, C; Lisa, M A; Liu, L; Loenne, P I; Loggins, V R; Loginov, V; Lohn, S; Lohner, D; Loizides, C; Loo, K K; Lopez, X; López Torres, E; Løvhøiden, G; Lu, X-G; Luettig, P; Lunardon, M; Luo, J; Luparello, G; Luquin, L; Luzzi, C; Ma, R; Ma, K; Madagodahettige-Don, D M; Maevskaya, A; Mager, M; Mahapatra, D P; Maire, A; Malaev, M; Maldonado Cervantes, I; Malinina, L; Mal'Kevich, D; Malzacher, P; Mamonov, A; Manceau, L; Mangotra, L; Manko, V; Manso, F; Manzari, V; Mao, Y; Marchisone, M; Mareš, J; Margagliotti, G V; Margotti, A; Marín, A; 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    2013-04-12

    We report the first measurement of the net-charge fluctuations in Pb-Pb collisions at sqrt[sNN]=2.76  TeV, measured with the ALICE detector at the CERN Large Hadron Collider. The dynamical fluctuations per unit entropy are observed to decrease when going from peripheral to central collisions. An additional reduction in the amount of fluctuations is seen in comparison to the results from lower energies. We examine the dependence of fluctuations on the pseudorapidity interval, which may account for the dilution of fluctuations during the evolution of the system. We find that the fluctuations at the LHC are smaller compared to the measurements at the BNL Relativistic Heavy Ion Collider, and as such, closer to what has been theoretically predicted for the formation of a quark-gluon plasma.

  16. Net-charge fluctuations in Pb-Pb collisions at sqrt[sNN]=2.76  TeV.

    PubMed

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Kumar, J; Kurashvili, P; Kurepin, A B; Kurepin, A; Kuryakin, A; Kushpil, V; Kushpil, S; Kvaerno, H; Kweon, M J; Kwon, Y; Ladrón de Guevara, P; Lakomov, I; Langoy, R; La Pointe, S L; Lara, C; Lardeux, A; La Rocca, P; Lazzeroni, C; Lea, R; Le Bornec, Y; Lechman, M; Lee, S C; Lee, K S; Lee, G R; Lefèvre, F; Lehnert, J; Leistam, L; Lenhardt, M; Lenti, V; León, H; Leoncino, M; León Monzón, I; León Vargas, H; Lévai, P; Lien, J; Lietava, R; Lindal, S; Lindenstruth, V; Lippmann, C; Lisa, M A; Liu, L; Loenne, P I; Loggins, V R; Loginov, V; Lohn, S; Lohner, D; Loizides, C; Loo, K K; Lopez, X; López Torres, E; Løvhøiden, G; Lu, X-G; Luettig, P; Lunardon, M; Luo, J; Luparello, G; Luquin, L; Luzzi, C; Ma, R; Ma, K; Madagodahettige-Don, D M; Maevskaya, A; Mager, M; Mahapatra, D P; Maire, A; Malaev, M; Maldonado Cervantes, I; Malinina, L; Mal'Kevich, D; Malzacher, P; Mamonov, A; Manceau, L; Mangotra, L; Manko, V; Manso, F; Manzari, V; Mao, Y; Marchisone, M; Mareš, J; Margagliotti, G V; Margotti, A; Marín, A; Marin Tobon, C A; Markert, C; Martashvili, I; Martinengo, P; Martínez, M I; Martínez Davalos, A; Martínez García, G; Martynov, Y; Mas, A; Masciocchi, S; Masera, M; Masoni, A; Massacrier, L; Mastromarco, M; Mastroserio, A; Matthews, Z L; Matyja, A; Mayani, D; Mayer, C; Mazer, J; Mazzoni, M A; Meddi, F; Menchaca-Rocha, A; Mercado Pérez, J; Meres, M; Miake, Y; Milano, L; Milosevic, J; Mischke, A; Mishra, A N; Miśkowiec, D; Mitu, C; Mlynarz, J; Mohanty, B; Mohanty, A K; Molnar, L; Montaño Zetina, L; Monteno, M; Montes, E; Moon, T; Morando, M; Moreira De Godoy, D A; Moretto, S; Morsch, A; Muccifora, V; Mudnic, E; Muhuri, S; Mukherjee, M; Müller, H; Munhoz, M G; Musa, L; Musso, A; Nandi, B K; Nania, R; Nappi, E; Nattrass, C; Naumov, N P; Navin, S; Nayak, T K; Nazarenko, S; Nazarov, G; Nedosekin, A; Nicassio, M; Niculescu, M; Nielsen, B S; Niida, T; Nikolaev, S; Nikolic, V; Nikulin, S; Nikulin, V; Nilsen, B S; Nilsson, M S; Noferini, F; Nomokonov, P; Nooren, G; Novitzky, N; Nyanin, A; Nyatha, A; Nygaard, C; Nystrand, J; Ochirov, A; Oeschler, H; Oh, S; Oh, S K; Oleniacz, J; Oppedisano, C; Ortiz Velasquez, A; Ortona, G; Oskarsson, A; Ostrowski, P; Otwinowski, J; Oyama, K; Ozawa, K; Pachmayer, Y; Pachr, M; Padilla, F; Pagano, P; Paić, G; Painke, F; Pajares, C; Pal, S; Pal, S K; Palaha, A; Palmeri, A; Papikyan, V; Pappalardo, G S; Park, W J; Passfeld, A; Pastirčák, B; Patalakha, D I; Paticchio, V; Pavlinov, A; Pawlak, T; Peitzmann, T; Pereira Da Costa, H; Pereira De Oliveira Filho, E; Peresunko, D; Pérez Lara, C E; Perez Lezama, E; Perini, D; Perrino, D; Peryt, W; Pesci, A; Peskov, V; Pestov, Y; Petráček, V; Petran, M; Petris, M; Petrov, P; Petrovici, M; Petta, C; Piano, S; Piccotti, A; Pikna, M; Pillot, P; Pinazza, O; Pinsky, L; Pitz, N; Piyarathna, D B; Płoskoń, M; Pluta, J; Pocheptsov, T; Pochybova, S; Podesta-Lerma, P L M; Poghosyan, M G; Polák, K; Polichtchouk, B; Pop, A; Porteboeuf-Houssais, S; Pospíšil, V; Potukuchi, B; Prasad, S K; Preghenella, R; Prino, F; Pruneau, C A; Pshenichnov, I; Puchagin, S; Puddu, G; Pujol Teixido, J; Pulvirenti, A; Punin, V; Putiš, M; Putschke, J; Quercigh, E; Qvigstad, H; Rachevski, A; Rademakers, A; Radomski, S; Räihä, T S; Rak, J; Rakotozafindrabe, A; Ramello, L; Ramírez Reyes, A; Raniwala, S; Raniwala, R; Räsänen, S S; Rascanu, B T; Rathee, D; Read, K F; Real, J S; Redlich, K; Reichelt, P; Reicher, M; Renfordt, R; Reolon, A R; Reshetin, A; Rettig, F; Revol, J-P; Reygers, K; Riccati, L; Ricci, R A; Richert, T; Richter, M; Riedler, P; Riegler, W; Riggi, F; Rodrigues Fernandes Rabacal, B; Rodríguez Cahuantzi, M; Rodriguez Manso, A; Røed, K; Rohr, D; Röhrich, D; Romita, R; Ronchetti, F; Rosnet, P; Rossegger, S; Rossi, A; Roy, C; Roy, P; Rubio Montero, A J; Rui, R; Ryabinkin, E; Rybicki, A; Sadovsky, S; Šafařík, K; Sahoo, R; Sahu, P K; Saini, J; Sakaguchi, H; Sakai, S; Sakata, D; Salgado, C A; Salzwedel, J; Sambyal, S; Samsonov, V; Sanchez Castro, X; Šándor, L; Sandoval, A; Sano, S; Sano, M; Santo, R; Santoro, R; Sarkamo, J; Scapparone, E; Scarlassara, F; Scharenberg, R P; Schiaua, C; Schicker, R; Schmidt, C; Schmidt, H R; Schreiner, S; Schuchmann, S; Schukraft, J; Schutz, Y; Schwarz, K; Schweda, K; Scioli, G; Scomparin, E; Scott, R; Scott, P A; Segato, G; Selyuzhenkov, I; Senyukov, S; Seo, J; Serci, S; Serradilla, E; Sevcenco, A; Shabetai, A; Shabratova, G; Shahoyan, R; Sharma, N; Sharma, S; Rohni, S; Shigaki, K; Shimomura, M; Shtejer, K; Sibiriak, Y; Siciliano, M; Sicking, E; Siddhanta, S; Siemiarczuk, T; Silvermyr, D; Silvestre, C; Simatovic, G; Simonetti, G; Singaraju, R; Singh, R; Singha, S; Singhal, V; Sinha, T; Sinha, B C; Sitar, B; Sitta, M; Skaali, T B; Skjerdal, K; Smakal, R; Smirnov, N; Snellings, R J M; Søgaard, C; Soltz, R; Son, H; Song, M; Song, J; Soos, C; Soramel, F; Sputowska, I; Spyropoulou-Stassinaki, M; Srivastava, B K; Stachel, J; Stan, I; Stan, I; Stefanek, G; Steinbeck, T; Steinpreis, M; Stenlund, E; Steyn, G; Stiller, J H; Stocco, D; Stolpovskiy, M; Strabykin, K; Strmen, P; Suaide, A A P; Subieta Vásquez, M A; Sugitate, T; Suire, C; Sukhorukov, M; Sultanov, R; Šumbera, M; Susa, T; Szanto de Toledo, A; Szarka, I; Szczepankiewicz, A; Szostak, A; Szymanski, M; Takahashi, J; Tapia Takaki, J D; Tauro, A; Tejeda Muñoz, G; Telesca, A; Terrevoli, C; Thäder, J; Thomas, D; Tieulent, R; Timmins, A R; Tlusty, D; Toia, A; Torii, H; Toscano, L; Truesdale, D; Trzaska, W H; Tsuji, T; Tumkin, A; Turrisi, R; Tveter, T S; Ulery, J; Ullaland, K; Ulrich, J; Uras, A; Urbán, J; Urciuoli, G M; Usai, G L; Vajzer, M; Vala, M; Valencia Palomo, L; Vallero, S; van der Kolk, N; Vande Vyvre, P; van Leeuwen, M; Vannucci, L; Vargas, A; Varma, R; Vasileiou, M; Vasiliev, A; Vechernin, V; Veldhoen, M; Venaruzzo, M; Vercellin, E; Vergara, S; Vernet, R; Verweij, M; Vickovic, L; Viesti, G; Vikhlyantsev, O; Vilakazi, Z; Villalobos Baillie, O; Vinogradov, A; Vinogradov, L; Vinogradov, Y; Virgili, T; Viyogi, Y P; Vodopyanov, A; Voloshin, K; Voloshin, S; Volpe, G; von Haller, B; Vranic, D; Øvrebekk, G; Vrláková, J; Vulpescu, B; Vyushin, A; Wagner, V; Wagner, B; Wan, R; Wang, M; Wang, D; Wang, Y; Wang, Y; Watanabe, K; Weber, M; Wessels, J P; Westerhoff, U; Wiechula, J; Wikne, J; Wilde, M; Wilk, G; Wilk, A; Williams, M C S; Windelband, B; Xaplanteris Karampatsos, L; Yaldo, C G; Yamaguchi, Y; Yang, H; Yang, S; Yasnopolskiy, S; Yi, J; Yin, Z; Yoo, I-K; Yoon, J; Yu, W; Yuan, X; Yushmanov, I; Zach, C; Zampolli, C; Zaporozhets, S; Zarochentsev, A; Závada, P; Zaviyalov, N; Zbroszczyk, H; Zelnicek, P; Zgura, I S; Zhalov, M; Zhang, X; Zhang, H; Zhou, F; Zhou, D; Zhou, Y; Zhu, J; Zhu, J; Zhu, X; Zichichi, A; Zimmermann, A; Zinovjev, G; Zoccarato, Y; Zynovyev, M; Zyzak, M

    2013-04-12

    We report the first measurement of the net-charge fluctuations in Pb-Pb collisions at sqrt[sNN]=2.76  TeV, measured with the ALICE detector at the CERN Large Hadron Collider. The dynamical fluctuations per unit entropy are observed to decrease when going from peripheral to central collisions. An additional reduction in the amount of fluctuations is seen in comparison to the results from lower energies. We examine the dependence of fluctuations on the pseudorapidity interval, which may account for the dilution of fluctuations during the evolution of the system. We find that the fluctuations at the LHC are smaller compared to the measurements at the BNL Relativistic Heavy Ion Collider, and as such, closer to what has been theoretically predicted for the formation of a quark-gluon plasma. PMID:25167254

  17. On the possible effects of gluon number fluctuations on {gamma}{gamma} collisions at high energies

    SciTech Connect

    Goncalves, V. P.; De Santana Amaral, J. T.

    2013-03-25

    We investigate the effects of the fluctuations on the total {gamma}{gamma}, {gamma}*{gamma}* cross sections and the real photon structure function F{sup {gamma}}{sub 2}(x,Q{sup 2}), considering a saturation phenomenological model for the dipole-dipole cross section and scattering amplitude with fluctuations included.

  18. Beam Energy Scan of Specific Heat Through Temperature Fluctuations in Heavy Ion Collisions

    NASA Astrophysics Data System (ADS)

    Basu, Sumit; Nandi, Basanta K.; Chatterjee, Sandeep; Chatterjee, Rupa; Nayak, Tapan

    2016-01-01

    Temperature fluctuations may have two distinct origins, first, quantum fluctuations that are initial state fluctuations, and second, thermodynamical fluctuations. We discuss a method of extracting the thermodynamic temperature from the mean transverse momentum of pions, by using controllable parameters such as centrality of the system, and range of the transverse momenta. Event-by-event fluctuations in global temperature over a large phase space provide the specific heat of the system. We present Beam Energy Scan of specific heat from data, AMPT and HRG model prediction. Experimental results from NA49, STAR, PHENIX, PHOBOS and ALICE are combined to obtain the specific heat as a function of beam energy. These results are compared to calculations from AMPT event generator, HRG model and lattice calculations, respectively.

  19. Energy dependence of Kπ, pπ and Kp fluctuations in Au+Au collisions from √sNN=7.7 to 200 GeV

    DOE PAGESBeta

    Adamczyk, L.

    2015-08-07

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical Kπ, pπ, and Kp fluctuations as measured by the STAR experiment in central 0–5% Au+Au collisions from center-of-mass collision energies √sNN=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude ofmore » the dynamical fluctuations in event-by-event measurements of the Kπ, pπ, and Kp pairs. The energy dependences of these fluctuations from central 0–5% Au+Au collisions all demonstrate a smooth evolution with collision energy.« less

  20. Dynamics of the Rydberg state population of slow highly charged ions impinging a solid surface at arbitrary collision geometry

    NASA Astrophysics Data System (ADS)

    Nedeljković, N. N.; Majkić, M. D.; Božanić, D. K.; Dojčilović, R. J.

    2016-06-01

    We consider the population dynamics of the intermediate Rydberg states of highly charged ions (core charge Z\\gg 1, principal quantum number {n}{{A}}\\gg 1) interacting with solid surfaces at arbitrary collision geometry. The recently developed resonant two-state vector model for the grazing incidence (2012 J. Phys. B: At. Mol. Opt. Phys. 45 215202) is extended to the quasi-resonant case and arbitrary angle of incidence. According to the model, the population probabilities depend both on the projectile parallel and perpendicular velocity components, in a complementary way. A cascade neutralization process for {{{Xe}}}Z+ ions, for Z=15{--}45, interacting with a conductive-surface is considered by taking into account the population dynamics. For an arbitrary collision geometry and given range of ionic velocities, a micro-staircase model for the simultaneous calculation of the kinetic energy gain and the charge state of the ion in front of the surface is proposed. The relevance of the obtained results for the explanation of the formation of nanostructures on solid surfaces by slow highly charged ions for normal incidence geometry is briefly discussed.

  1. SU-E-T-106: Development of a Collision Prediction Algorithm for Determining Problematic Geometry for SBRT Treatments Using a Stereotactic Body Frame

    SciTech Connect

    Wagar, M; Friesen, S; Mannarino, E

    2014-06-01

    Purpose: Collision between the gantry and the couch or patient during Radiotherapy is not a common concern for conventional RT (static fields or arc). With the increase in the application of stereotactic planning techniques to the body, collisions have become a greater concern. Non-coplanar beam geometry is desirable in stereotatic treatments in order to achieve sharp gradients and a high conformality. Non-coplanar geometry is less intuitive in the body and often requires an iterative process of planning and dry runs to guarantee deliverability. Methods: Purpose written software was developed in order to predict the likelihood of collision between the head of the gantry and the couch, patient or stereotatic body frame. Using the DICOM plan and structures set, exported by the treatment planning system, this software is able to predict the possibility of a collision. Given the plan's isocenter, treatment geometry and exterior contours, the software is able to determine if a particular beam/arc is clinically deliverable or if collision is imminent. Results: The software was tested on real world treatment plans with untreatable beam geometry. Both static non-coplanar and VMAT plans were tested. Of these, the collision prediction software could identify all as having potentially problematic geometry. Re-plans of the same cases were also tested and validated as deliverable. Conclusion: This software is capable of giving good initial indication of deliverability for treatment plans that utilize complex geometry (SBRT) or have lateral isocenters. This software is not intended to replace the standard pre-treatment QA dry run. The effectiveness is limited to those portions of the patient and immobilization devices that have been included in the simulation CT and contoured in the planning system. It will however aid the planner in reducing the iterations required to create complex treatment geometries necessary to achieve ideal conformality and organ sparing.

  2. Event-by-Event Charged-Neutral Fluctuations in Pb + Pb Collisions at 158 A GeV

    SciTech Connect

    Aggarwal, M. M.; Ahammed, Z.; Plasil, F; Silvermyr, David O; Stankus, Paul W; WA98, Collaboration

    2011-01-01

    Charged particles and photons have been measured in central Pb + Pb collisions at 158 A GeV in a common ( )-phase space region in the WA98 experiment at the CERN SPS. The measured distributions have been analyzed to quantify the frequency with which phase space regions of varying sizes have either small or large neutral pion fraction. The measured results are compared with VENUS model simulated events and with mixed events. Events with both large and small charged neutral fluctuations are observed to occur more frequently than expected statistically, as deduced from mixed events, or as predicted by model simulations, with the difference becoming more prominent with decreasing size of the region.

  3. Event-by-event charged-neutral fluctuations in Pb+Pb collisions at 158 A~GeV.

    SciTech Connect

    WA98, Collaboration

    2011-01-01

    Charged particles and photons have been measured in central Pb + Pb collisions at 158 AGeV in a common ({eta}-{phi})-phase space region in the WA98 experiment at the CERN SPS. The measured distributions have been analyzed to quantify the frequency with which phase space regions of varying sizes have either small or large neutral pion fraction. The measured results are compared with VENUS model simulated events and with mixed events. Events with both large and small charged-neutral fluctuations are observed to occur more frequently than expected statistically, as deduced from mixed events, or as predicted by model simulations, with the difference becoming more prominent with decreasing size of the {Delta}{eta}-{Delta}{phi} region.

  4. Effect of modification to tongue and impeller geometry on unsteady flow, pressure fluctuations, and noise in a centrifugal pump

    SciTech Connect

    Dong, R.; Chu, S.; Katz, J.

    1997-07-01

    Particle Image Velocimetry (PIV), pressure, and noise measurements are used to study the effect of modifications to tongue and impeller geometries on the flow structure and resulting noise in a centrifugal pump. It is demonstrated that the primary sources of noise are associated with interactions of the nonuniform outflux from the impeller (jet/wake phenomenon) with the tongue. Consequently, significant reduction of noise is achieved by increasing the gap between the tongue and the impeller up to about 20% of the impeller radius. Further increase in the gap affects the performance adversely with minimal impact on the noise level. When the gap is narrow, the primary sources of noise are impingement of the wake on the tip of the tongue, and tongue oscillations when the pressure difference across it is high. At about 20% gap, the entire wake and its associated vorticity trains miss the tongue, and the only (quite weak) effect of nonuniform outflux is the impingement of the jet on the tongue. An attempt is also made to reduce the nonuniformity in outflux from the impeller by inserting short vanes between the blades. They cause reduction in the size of the original wakes, but generate an additional jet/wake phenomenon of their own. Both wakes are weak to a level that their impacts on local pressure fluctuations and noise are insignificant. The only remaining major contributor to noise is tongue oscillations. This effect is shown to be dependent on the stiffness of the tongue.

  5. Analysis of single events in ultrarelativistic nuclear collisions: A new method to search for critical fluctuations

    SciTech Connect

    Stock, R.

    1995-07-15

    The upcoming generation of experiments with ultrarelativistic heavy nuclear projectiles, at the CERN SPS and at RHIC and LHC, will confront researchers with several thousand identified hadrons per event, suitable detectors provided. An analysis of individual events becomes meaningful concerning a multitude of hadronic signals thought to reveal a transient deconfinement phase transition, or the related critical precursor fluctuations. Transverse momentum spectra, the kaon to pion ratio, and pionic Bose-Einstein correlation are examined, showing how to separate the extreme, probably rare candidate events from the bulk of average events. This type of observables can already be investigated with the Pb beam of the SPS. The author then discusses single event signals that add to the above at RHIC and LHC energies, kaon interferometry, rapidity fluctuation, jet and {gamma} production.

  6. Searching for gluon number fluctuations effects in eA collisions

    SciTech Connect

    Kugeratski, M. S.; Gonçalves, V. P.; Santana Amaral, J. T. de

    2014-11-11

    We propose to investigate the gluon number fluctuations effects in deep inelastic electron-ion scattering at high energies. We estimate the nuclear structure function F{sub 2}{sup A}(x,Q{sup 2}), as well the longitudinal and charm contributions, using a generalization for nuclear targets of the Golec-Biernat-Wusthoff (GBW) model which describes the electron proton HERA data. Here we consider that the nucleus at high energies acts as an amplifier of the physics of high parton densities. For a first investigation we study the scattering with Ca and Pb nuclei. Our preliminary results predict that the effects of gluon number fluctuations are small in the region of the future electron ion collider.

  7. Evidence for x -dependent proton color fluctuations in p A collisions at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Alvioli, M.; Cole, B. A.; Frankfurt, L.; Perepelitsa, D. V.; Strikman, M.

    2016-01-01

    The centrality dependence of forward jet production in p A collisions at the Large Hadron Collider (LHC) has been found to grossly violate the Glauber model prediction in a way that depends on the x in the proton. We argue that this modification pattern provides the first experimental evidence for x -dependent proton color fluctuation effects. On average, parton configurations in the projectile proton containing a parton with large x interact with a nuclear target with a significantly smaller than average cross section and have smaller than average size. We implement the effects of fluctuations of the interaction strength and, using the ATLAS analysis of how hadron production at backward rapidities depends on the number of wounded nucleons, make quantitative predictions for the centrality dependence of the jet production rate as a function of the x -dependent interaction strength σ (x ) . We find that σ (x ) ˜0.6 <σ > gives a good description of the data at x =0.6 . These findings support an explanation of the European Muon Collaboration effect as arising from the suppression of small-size nucleon configurations in the nucleus.

  8. Energy dependence of Kπ, pπ and Kp fluctuations in Au+Au collisions from √sNN=7.7 to 200 GeV

    SciTech Connect

    Adamczyk, L.

    2015-08-07

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical Kπ, pπ, and Kp fluctuations as measured by the STAR experiment in central 0–5% Au+Au collisions from center-of-mass collision energies √sNN=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude of the dynamical fluctuations in event-by-event measurements of the Kπ, pπ, and Kp pairs. The energy dependences of these fluctuations from central 0–5% Au+Au collisions all demonstrate a smooth evolution with collision energy.

  9. Event-by-event hexb pt hexb fluctuations in Au-Au collisions atsqrt(sNN) = 130 GeV

    SciTech Connect

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M; Arkhipkin, D.; Averichev, G.S.; Badyal,S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele,S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj,S.; Bhaskar, P.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar,A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez,M.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Ganti, M.S.; Gutierrez, T.D.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Cronstal, S.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris,J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang,S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.S.; Kopytine,S.M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger,K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; et al.

    2003-09-02

    We present the first large-acceptance measurement of event-wise fluctuations in Au-Au collisions at {radical}s{sub NN} = 130 GeV. Significant nonstatistical fluctuations are observed. The measured fractional r.m.s. width excess of the event-wise distribution for the 15% most-central events for charged hadrons within |{eta}| < 1 and 0.15 {le} p{sub t} {le} 2 GeV/c is 13.7 {+-} 0.1(stat) {+-}1.3(syst)% relative to a statistical reference. The variation of charge-independent fluctuation excess with centrality is non-monotonic but smooth. Charge-dependent nonstatistical fluctuations are also observed.

  10. Azimuthal Anisotropy of π0 Production in Au+Au Collisions at sNN=200GeV: Path-Length Dependence of Jet Quenching and the Role of Initial Geometry

    NASA Astrophysics Data System (ADS)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Alexander, J.; Aoki, K.; Aramaki, Y.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bickley, A. A.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Constantin, P.; Csanád, M.; Csörgő, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Dutta, D.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'Yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M., Jr.; Finger, M.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Garishvili, I.; Glenn, A.; Gong, H.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Hanks, J.; Han, R.; Hartouni, E. P.; Haslum, E.; Hayano, R.; Heffner, M.; Hegyi, S.; Hemmick, T. K.; Hester, T.; He, X.; Hill, J. C.; Hohlmann, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Ide, J.; Ikeda, Y.; Imai, K.; Inaba, M.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Jacak, B. V.; Jia, J.; Jin, J.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kang, J. H.; Kapustinsky, J.; Karatsu, K.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, D. H.; Kim, D. J.; Kim, E. J.; Kim, E.; Kim, S. H.; Kim, Y. J.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kotchetkov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K.; Lee, K. S.; Leitch, M. J.; Leite, M. A. L.; Leitner, E.; Lenzi, B.; Liebing, P.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Li, X.; Love, B.; Luechtenborg, R.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; Matathias, F.; McCumber, M.; McGaughey, P. L.; Means, N.; Meredith, B.; Miake, Y.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, M.; Mitchell, J. T.; Mohanty, A. K.; Morino, Y.; Morreale, A.; Morrison, D. P.; Moukhanova, T. V.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Nouicer, R.; Nyanin, A. S.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Okada, K.; Oka, M.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ružička, P.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakashita, K.; Samsonov, V.; Sano, S.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Sparks, N. A.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sziklai, J.; Takagui, E. M.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tarján, P.; Themann, H.; Thomas, T. L.; Togawa, M.; Toia, A.; Tomášek, L.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Vale, C.; Valle, H.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Wei, F.; Wei, R.; Wessels, J.; White, S. N.; Winter, D.; Wood, J. P.; Woody, C. L.; Wright, R. M.; Wysocki, M.; Xie, W.; Yamaguchi, Y. L.; Yamaura, K.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; Young, G. R.; Younus, I.; You, Z.; Yushmanov, I. E.; Zajc, W. A.; Zhang, C.; Zhou, S.; Zolin, L.; PHENIX Collaboration

    2010-10-01

    We have measured the azimuthal anisotropy of π0 production for 1collisions at sNN=200GeV. The observed anisotropy shows a gradual decrease for 3≲pT≲7-10GeV/c, but remains positive beyond 10GeV/c. The magnitude of this anisotropy is underpredicted, up to at least ˜10GeV/c, by current perturbative QCD (PQCD) energy-loss model calculations. An estimate of the increase in anisotropy expected from initial-geometry modification due to gluon saturation effects and fluctuations is insufficient to account for this discrepancy. Calculations that implement a path-length dependence steeper than what is implied by current PQCD energy-loss models show reasonable agreement with the data.

  11. Azimuthal anisotropy of π⁰ production in Au+Au collisions at sqrt((s)NN)=200  GeV: path-length dependence of jet quenching and the role of initial geometry.

    PubMed

    Adare, A; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Aoki, K; Aramaki, Y; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bickley, A A; Bok, J S; Boyle, K; Brooks, M L; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Chen, C-H; Chi, C Y; Chiu, M; Choi, I J; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Connors, M; Constantin, P; Csanád, M; Csörgo, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Hanks, J; Han, R; Hartouni, E P; Haslum, E; Hayano, R; Heffner, M; Hegyi, S; Hemmick, T K; Hester, T; He, X; Hill, J C; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Ide, J; Ikeda, Y; Imai, K; Inaba, M; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Jacak, B V; Jia, J; Jin, J; Johnson, B M; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kang, J H; Kapustinsky, J; Karatsu, K; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kim, B I; Kim, D H; Kim, D J; Kim, E J; Kim, E; Kim, S H; Kim, Y J; Kinney, E; Kiriluk, K; Kiss, A; Kistenev, E; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotchetkov, D; Kozlov, A; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K B; Lee, K; Lee, K S; Leitch, M J; Leite, M A L; Leitner, E; Lenzi, B; Liebing, P; Linden Levy, L A; Liška, T; Litvinenko, A; Liu, H; Liu, M X; Li, X; Love, B; Luechtenborg, R; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; Means, N; Meredith, B; Miake, Y; Mignerey, A C; Mikeš, P; Miki, K; Milov, A; Mishra, M; Mitchell, J T; Mohanty, A K; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, T; Nakano, K; Newby, J; Nguyen, M; Nouicer, R; Nyanin, A S; O'Brien, E; Oda, S X; Ogilvie, C A; Okada, K; Oka, M; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, I H; Park, J; Park, S K; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Ružička, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Sparks, N A; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sziklai, J; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarján, P; Themann, H; Thomas, T L; Togawa, M; Toia, A; Tomášek, L; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Vinogradov, A A; Virius, M; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Wood, J P; Woody, C L; Wright, R M; Wysocki, M; Xie, W; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; Young, G R; Younus, I; You, Z; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zolin, L

    2010-10-01

    We have measured the azimuthal anisotropy of π⁰ production for 1collisions at sqrt((s)NN)=200  GeV. The observed anisotropy shows a gradual decrease for 3≲p(T)≲7-10  GeV/c, but remains positive beyond 10  GeV/c. The magnitude of this anisotropy is underpredicted, up to at least ∼10  GeV/c, by current perturbative QCD (PQCD) energy-loss model calculations. An estimate of the increase in anisotropy expected from initial-geometry modification due to gluon saturation effects and fluctuations is insufficient to account for this discrepancy. Calculations that implement a path-length dependence steeper than what is implied by current PQCD energy-loss models show reasonable agreement with the data.

  12. Azimuthal Anisotropy of pi Production in Au+Au Collisions at s_NN = 200 GeV: Path-length Dependence of Jet-Quenching and the Role of Initial Geometry

    SciTech Connect

    Adare, A.; Awes, Terry C; Cianciolo, Vince; Efremenko, Yuri; Enokizono, Akitomo; Read Jr, Kenneth F; Silvermyr, David O; Sorensen, Soren P; Stankus, Paul W; PHENIX, Collaboration

    2010-01-01

    We have measured the azimuthal anisotropy of {pi}{sup 0} production for 1 < p{sub T} < 18 GeV/c for Au+Au collisions at {radical}s{sub NN} = 200 GeV. The observed anisotropy shows a gradual decrease for 3 {approx}< p {approx}< 7-10 GeV/c, but remains positive beyond 10 GeV/c. The magnitude of this anisotropy is underpredicted, up to at least {approx}10 GeV/c, by current perturbative QCD (PQCD) energy-loss model calculations. An estimate of the increase in anisotropy expected from initial-geometry modification due to gluon saturation effects and fluctuations is insufficient to account for this discrepancy. Calculations that implement a path-length dependence steeper than what is implied by current PQCD energy-loss models show reasonable agreement with the data.

  13. Evidence for transverse momentum and pseudorapidity dependent event plane fluctuations in PbPb and pPb collisions

    DOE PAGESBeta

    Khachatryan, Vardan

    2015-09-22

    A systematic study of the factorization of long-range azimuthal two-particle correlations into a product of single-particle anisotropies is presented as a function of pT and η of both particles and as a function of the particle multiplicity in PbPb and pPb collisions. The data were taken with the CMS detector for PbPb collisions at √sNN=2.76 TeV and pPb collisions at √sNN=5.02 TeV, covering a very wide range of multiplicity. Factorization is observed to be broken as a function of both particle pT and η. When measured with particles of different pT, the magnitude of the factorization breakdown for the secondmore » Fourier harmonic reaches 20% for very central PbPb collisions but decreases rapidly as the multiplicity decreases. The data are consistent with viscous hydrodynamic predictions, which suggest that the effect of factorization breaking is mainly sensitive to the initial-state conditions rather than to the transport properties (e.g., shear viscosity) of the medium. The factorization breakdown is also computed with particles of different η. The effect is found to be weakest for mid-central PbPb events but becomes larger for more central or peripheral PbPb collisions, and also for very-high-multiplicity pPb collisions. The η-dependent factorization data provide new insights to the longitudinal evolution of the medium formed in heavy ion collisions.« less

  14. Evidence for transverse momentum and pseudorapidity dependent event plane fluctuations in PbPb and pPb collisions

    SciTech Connect

    Khachatryan, Vardan

    2015-09-22

    A systematic study of the factorization of long-range azimuthal two-particle correlations into a product of single-particle anisotropies is presented as a function of pT and η of both particles and as a function of the particle multiplicity in PbPb and pPb collisions. The data were taken with the CMS detector for PbPb collisions at √sNN=2.76 TeV and pPb collisions at √sNN=5.02 TeV, covering a very wide range of multiplicity. Factorization is observed to be broken as a function of both particle pT and η. When measured with particles of different pT, the magnitude of the factorization breakdown for the second Fourier harmonic reaches 20% for very central PbPb collisions but decreases rapidly as the multiplicity decreases. The data are consistent with viscous hydrodynamic predictions, which suggest that the effect of factorization breaking is mainly sensitive to the initial-state conditions rather than to the transport properties (e.g., shear viscosity) of the medium. The factorization breakdown is also computed with particles of different η. The effect is found to be weakest for mid-central PbPb events but becomes larger for more central or peripheral PbPb collisions, and also for very-high-multiplicity pPb collisions. The η-dependent factorization data provide new insights to the longitudinal evolution of the medium formed in heavy ion collisions.

  15. Event-by-event fluctuations in a perturbative QCD + saturation + hydrodynamics model: Determining QCD matter shear viscosity in ultrarelativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Niemi, H.; Eskola, K. J.; Paatelainen, R.

    2016-02-01

    We introduce an event-by-event perturbative-QCD + saturation + hydro ("EKRT") framework for ultrarelativistic heavy-ion collisions, where we compute the produced fluctuating QCD-matter energy densities from next-to-leading-order perturbative QCD using a saturation conjecture to control soft-particle production and describe the space-time evolution of the QCD matter with dissipative fluid dynamics, event by event. We perform a simultaneous comparison of the centrality dependence of hadronic multiplicities, transverse momentum spectra, and flow coefficients of the azimuth-angle asymmetries against the LHC and RHIC measurements. We compare also the computed event-by-event probability distributions of relative fluctuations of elliptic flow and event-plane angle correlations with the experimental data from Pb +Pb collisions at the LHC. We show how such a systematic multienergy and multiobservable analysis tests the initial-state calculation and the applicability region of hydrodynamics and, in particular, how it constrains the temperature dependence of the shear viscosity-to-entropy ratio of QCD matter in its different phases in a remarkably consistent manner.

  16. New PHOBOS results on event-by-event fluctuations

    SciTech Connect

    Alver, B.; Ballintijn, M.; Busza, W.; Decowski, M. P.; Gulbrandsen, K.; Henderson, C.; Kane, J. L.; Kulinich, P.; Li, W.; Loizides, C.; Reed, C.; Roland, C.; Roland, G.; Rosenberg, L.; Sarin, P.; Stephans, G. S. F.; Vale, C.; Nieuwenhuizen, G. J. van; Vaurynovich, S. S.; Verdier, R.

    2006-04-11

    We present new results from the PHOBOS experiment at RHIC on event-by-event fluctuations of particle multiplicities and angular distributions in nucleus-nucleus collisions at RHIC. Our data for Au+Au collisions at {radical}(s{sub NN}) = 200 GeV show that at a level of 10-4 or less, no rare, large-amplitude fluctuations in the total multiplicity distributions or the shape of the pseudorapidity distributions are observed. We however find significant short-range multiplicity correlations in these data, that can be described as particle production in clusters. In Cu+Cu collisions, we observe large final-state azimuthal anisotropies {nu}2. A common scaling behavior for Cu+Cu and Au+Au for these anisotropies emerges when fluctuations in the initial state geometry are taken into account.

  17. Measurement of Density Correlations in Pseudorapidity via Charged Particle Multiplicity Fluctuations in Au+Au Collisions at sqrt(sNN) = 200 GeV

    SciTech Connect

    Adler, S. S.; Awes, Terry C; Batsouli, Sotiria; Cianciolo, Vince; Efremenko, Yuri; Read Jr, Kenneth F; Silvermyr, David O; Sorensen, Soren P; Stankus, Paul W; Young, Glenn R; Zhang, Chun; PHENIX, Collaboration

    2007-09-01

    Longitudinal density correlations of produced matter in Au+Au collisions at sqrt(s{sub NN})=200 GeV have been measured from the inclusive charged particle distributions as a function of pseudorapidity window sizes. The extracted {alpha}{xi} parameter, related to the susceptibility of the density fluctuations in the long-wavelength limit, exhibits a nonmonotonic behavior as a function of the number of participant nucleons, N{sub part}. A local maximum is seen at N{sub part}{approx}90, with corresponding energy density based on the Bjorken picture of {epsilon}{sub Bj}{tau}{approx}2.4 GeV/(fm{sup 2}c) with a transverse area size of 60 fm2. This behavior may suggest a critical phase boundary based on the Ginzburg-Landau framework.

  18. Spin and isospin fluctuations in heavy ion collisions and their dependence upon the shape of the dinuclear complex

    SciTech Connect

    Moretto, L.G.

    1980-08-01

    The relevance of higher multipoles of giant isovector modes in the charge distribution of deep inelastic fragments is discussed and found to depend strongly on mass asymmetry. The sources of angular momentum fluctuations are investigated. Quantal effects are considered as well as effects arising from non-equilibrium and equilibrium statistical fluctuations. A model based upon equilibrium statistical mechanics is considered in detail, and used to predict both 2nd moments of the angular momentum distributions and the angular momentum misalignment. Analytical expressions are derived to calculate the angular distributions of sequentially emitted particles, fission fragments, as well as gamma rays in terms of the angular momentum misalignment. Recent data on the angular distributions of sequential alphas, fission and gamma rays are analyzed in terms of the model. 29 figures, 1 table.

  19. Strange fluctuations at RHIC

    NASA Astrophysics Data System (ADS)

    Abdel Aziz, Mohamed; Gavin, Sean

    2004-01-01

    Net charge fluctuations measured by the STAR experiment at RHIC agree with hadronic event generators, suggesting that more sensitive fluctuation observables are needed to extract information on collision dynamics. Important information on isospin fluctuations can be extracted from K0SK± measurements. Gavin and Kapusta proposed that disoriented chiral condensate can produce extraordinary isospin fluctuations in both strange and non-strange mesons. However, even in the absence of such a contribution, we argue that this observable is very sensitive to the collision dynamics.

  20. Hadronization geometry and charge-dependent two-particlecorrelation on momentum subspace (eta, phi) in Au-Au collisions atsqrt(sNN) = 130 GeV

    SciTech Connect

    Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson,B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Bai, Y.; Balewski,J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bharadwaj, S.; Bhasin, A.; Bhati, A.K.; Bhatia, V.S.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.V.; Bravar,A.; Bystersky, M.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de laBarca Sanchez, M.; Carroll, J.; Castillo, J.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopdhyay, S.; Chen, H.F.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; De Moura, M.M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip,P.; Finch, E.; Fine, V.; Fisyak, Y.; Foley, K.J.; Fomenko, K.; Fu, J.; Gagliardi, C.A.; Gans, J.; Ganti, M.S.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guo, Y.; Gupta, A.; Guiterrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry,T.W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann,G.W.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Jones,P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Khodyrv,V.Yu.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Kopytine, S.M.; Kotchenda, L.; Kramer, M.; Kravtsov, P.; Kravtsov, V.I.; Krueger, K.; Kuhn, C.; Kulikov,A.I.; et al.

    2004-09-23

    We present the first measurements of charge-dependent two-particle correlations on momentum-space difference variables {eta}{sub 1}-{eta}{sub 2} (pseudorapidity) and {phi}{sub 1}-{phi}{sub 2} (azimuth) for primary charged hadrons with transverse momentum 0.15 {le} p{sub t} {le} 2 GeV/c and |{eta}| {le} 1.3 from Au-Au collisions at {radical}s{sub NN} = 130 GeV. We observe correlation structures not predicted by theory but consistent with evolution of hadron emission geometry with increasing centrality from one-dimensional fragmentation of color strings to higher-dimensional fragmentation of a hadron-opaque bulk medium.

  1. Fluctuations of charge separation perpendicular to the event plane and local parity violation in √sNN =200 GeV Au + Au collisions at the BNL Relativistic Heavy Ion Collider

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E.; Averichev, G. S.; Balewski, J.; Banerjee, A.; Barnovska, Z.; Beavis, D. R.; Bellwied, R.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bruna, E.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, P.; Chwastowski, J.; Codrington, M. J. M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Leyva, A. Davila; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; de Souza, R. Derradi; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Dion, A.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elnimr, M.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Fersch, R. G.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Gliske, S.; Grebenyuk, O. G.; Grosnick, D.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Hays-Wehle, J. P.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jena, C.; Judd, E. G.; Kabana, S.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Kikola, D. P.; Kiryluk, J.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Korsch, W.; Kotchenda, L.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; LaPointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Leight, W.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Mioduszewski, S.; Mitrovski, M. K.; Mohammed, Y.; Mohanty, B.; Mondal, M. M.; Munhoz, M. G.; Mustafa, M. K.; Naglis, M.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nogach, L. V.; Novak, J.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; Olson, D.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Plyku, D.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Powell, C. B.; Pruneau, C.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, B.; Schmitz, N.; Schuster, T. R.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shao, M.; Sharma, B.; Sharma, M.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; de Toledo, A. Szanto; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, W.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2013-12-01

    Previous experimental results based on data (˜15×106 events) collected by the STAR detector at the BNL Relativistic Heavy Ion Collider suggest event-by-event charge-separation fluctuations perpendicular to the event plane in noncentral heavy-ion collisions. Here we present the correlator previously used split into its two component parts to reveal correlations parallel and perpendicular to the event plane. The results are from a high-statistics 200-GeV Au + Au collisions data set (57×106 events) collected by the STAR experiment. We explicitly count units of charge separation from which we find clear evidence for more charge-separation fluctuations perpendicular than parallel to the event plane. We also employ a modified correlator to study the possible P-even background in same- and opposite-charge correlations, and find that the P-even background may largely be explained by momentum conservation and collective motion.

  2. Non-Gaussian eccentricity fluctuations

    NASA Astrophysics Data System (ADS)

    Grönqvist, Hanna; Blaizot, Jean-Paul; Ollitrault, Jean-Yves

    2016-09-01

    We study the fluctuations of the anisotropy of the energy density profile created in a high-energy collision at the LHC. We show that the anisotropy in harmonic n has generic non-Gaussian fluctuations. We argue that these non-Gaussianities have a universal character for small systems such as p+Pb collisions, but not for large systems such as Pb+Pb collisions where they depend on the underlying non-Gaussian statistics of the initial density profile. We generalize expressions for the eccentricity cumulants ɛ2{4 } and ɛ3{4 } previously obtained within the independent-source model to a general fluctuating initial density profile.

  3. Energy dependence of transverse momentum fluctuations in Pb+Pb collisions at the CERN Super Proton Synchrotron (SPS) at 20A to 158A GeV

    SciTech Connect

    NA49 Collaboration; Anticic, T.

    2009-04-15

    Results are presented on event-by-event fluctuations of transverse momenta p{sub T} in central Pb+Pb interactions at 20A, 30A, 40A, 80A, and 158A GeV. The analysis was performed for charged particles at forward center-of-mass rapidity (1.1 < y*{sub {pi}} < 2.6). Three fluctuation measures were studied: the distribution of average transverse momentum M(p{sub T}) in the event, the {phi}{sub p{sub T}} fluctuation measure, and two-particle transverse momentum correlations. Fluctuations of p{sub T} are small and show no significant energy dependence in the energy range of the CERN Super Proton Synchrotron. Results are compared with QCD-inspired predictions for the critical point, and with the UrQMD model. Transverse momentum fluctuations, similar to multiplicity fluctuations, do not show the increase expected for freeze-out near the critical point of QCD.

  4. Particle number fluctuations in a canonical ensemble

    SciTech Connect

    Begun, V.V.; Gazdzicki, M.; Gorenstein, M.I.; Zozulya, O.S.

    2004-09-01

    Fluctuations of charged particle number are studied in the canonical ensemble. In the infinite volume limit the fluctuations in the canonical ensemble are different from the fluctuations in the grand canonical one. Thus, the well-known equivalence of both ensembles for the average quantities does not extend for the fluctuations. In view of the possible relevance of the results for the analysis of fluctuations in nuclear collisions at high energies, a role of the limited kinematical acceptance is studied.

  5. Consequences of high-x proton size fluctuations in small collision systems at √{sNN}=200 GeV

    NASA Astrophysics Data System (ADS)

    McGlinchey, D.; Nagle, J. L.; Perepelitsa, D. V.

    2016-08-01

    Recent measurements of jet production rates at large transverse momentum (pT) in the collisions of small projectiles with large nuclei at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider indicate that they have an unexpected relationship with estimates of the collision centrality. One compelling interpretation of the data is that they capture an xp-dependent decrease in the average interaction strength of the nucleon in the projectile undergoing a hard scattering. A weakly interacting or "shrinking" nucleon in the projectile strikes fewer nucleons in the nucleus, resulting in a particular pattern of centrality-dependent modifications to high-pT processes. We describe a simple one-parameter geometric implementation of this picture within a modified Monte Carlo Glauber model tuned to d +Au jet data, and explore two of its major consequences. First, the model predicts a particular projectile-species effect on the centrality dependence at high xp, opposite to that expected from a final state energy loss effect. Second, we find that some of the large centrality dependence observed for forward dihadron production in d +Au collisions at RHIC may arise from the physics of the "shrinking" projectile nucleon, in addition to impact parameter dependent shadowing or saturation effects at low nuclear x . We conclude that analogous measurements in recently collected p +Au and 3He+Au collision data at RHIC can provide a unique test of these predictions.

  6. Collective effects in light-heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Schenke, Björn; Venugopalan, Raju

    2014-11-01

    We present results for the azimuthal anisotropy of charged hadron distributions in A+A, p+A, d+A, and 3He+A collisions within the IP-Glasma+MUSIC model. Obtained anisotropies are due to the fluid dynamic response of the system to the fluctuating initial geometry of the interaction region. While the elliptic and triangular anisotropies in peripheral Pb+Pb collisions at √{ s} = 2.76 TeV are well described by the model, the same quantities in √{ s} = 5.02 TeV p+Pb collisions underestimate the experimental data. This disagreement can be due to neglected initial state correlations or the lack of a detailed description of the fluctuating spatial structure of the proton, or both. We further present predictions for azimuthal anisotropies in p+Au, d+Au, and 3He+Au collisions at √{ s} = 200 GeV. For d+Au and 3He+Au collisions we expect the detailed substructure of the nucleon to become less important.

  7. K/pi Fluctuations at relativistic energies.

    PubMed

    Abelev, B I; Aggarwal, M M; Ahammed, Z; Anderson, B D; Arkhipkin, D; Averichev, G S; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Baumgart, S; Beavis, D R; Bellwied, R; Benedosso, F; Betancourt, M J; Betts, R R; Bhasin, A; Bhati, A K; Bichsel, H; Bielcik, J; Bielcikova, J; Biritz, B; Bland, L C; Bombara, M; Bonner, B E; Botje, M; Bouchet, J; Braidot, E; Brandin, A V; Bruna, E; Bueltmann, S; Burton, T P; Bystersky, M; Cai, X Z; Caines, H; de la Barca Sánchez, M Calderón; Catu, O; Cebra, D; Cendejas, R; Cervantes, M C; Chajecki, Z; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, J Y; Cheng, J; Cherney, M; Chikanian, A; Choi, K E; Christie, W; Clarke, R F; Codrington, M J M; Corliss, R; Cormier, T M; Cosentino, M R; Cramer, J G; Crawford, H J; Das, D; Das, S; Dash, S; Daugherity, M; De Silva, L C; Dedovich, T G; DePhillips, M; Derevschikov, A A; de Souza, R Derradi; Didenko, L; Djawotho, P; Dogra, S M; Dong, X; Drachenberg, J L; Draper, J E; Dunlop, J C; Mazumdar, M R Dutta; Edwards, W R; Efimov, L G; Elhalhuli, E; Elnimr, M; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Eun, L; Fachini, P; Fatemi, R; Fedorisin, J; Feng, A; Filip, P; Finch, E; Fine, V; Fisyak, Y; Gagliardi, C A; Gaillard, L; Gangadharan, D R; Ganti, M S; Garcia-Solis, E J; Geromitsos, A; Geurts, F; Ghazikhanian, V; Ghosh, P; Gorbunov, Y N; Gordon, A; Grebenyuk, O; Grosnick, D; Grube, B; Guertin, S M; Guimaraes, K S F F; Gupta, A; Gupta, N; Guryn, W; Haag, B; Hallman, T J; Hamed, A; Harris, J W; He, W; Heinz, M; Heppelmann, S; Hippolyte, B; Hirsch, A; Hjort, E; Hoffman, A M; Hoffmann, G W; Hofman, D J; Hollis, R S; Huang, H Z; Humanic, T J; Huo, L; Igo, G; Iordanova, A; Jacobs, P; Jacobs, W W; Jakl, P; Jena, C; Jin, F; Jones, C L; Jones, P G; Joseph, J; Judd, E G; Kabana, S; Kajimoto, K; Kang, K; Kapitan, J; Keane, D; Kechechyan, A; Kettler, D; Khodyrev, V Yu; Kikola, D P; Kiryluk, J; Kisiel, A; Klein, S R; Knospe, A G; Kocoloski, A; Koetke, D D; Kopytine, M; Korsch, W; Kotchenda, L; Kouchpil, V; Kravtsov, P; Kravtsov, V I; Krueger, K; Krus, M; Kuhn, C; Kumar, L; Kurnadi, P; Lamont, M A C; Landgraf, J M; LaPointe, S; Lauret, J; Lebedev, A; Lednicky, R; Lee, C-H; Lee, J H; Leight, W; LeVine, M J; Li, C; Li, N; Li, Y; Lin, G; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, J; Liu, L; Ljubicic, T; Llope, W J; Longacre, R S; Love, W A; Lu, Y; Ludlam, T; Ma, G L; Ma, Y G; Mahapatra, D P; Majka, R; Mall, O I; Mangotra, L K; Manweiler, R; Margetis, S; Markert, C; Matis, H S; Matulenko, Yu A; McDonald, D; McShane, T S; Meschanin, A; Milner, R; Minaev, N G; Mioduszewski, S; Mischke, A; Mohanty, B; Morozov, D A; Munhoz, M G; Nandi, B K; Nattrass, C; Nayak, T K; Nelson, J M; Netrakanti, P K; Ng, M J; Nogach, L V; Nurushev, S B; Odyniec, G; Ogawa, A; Okada, H; Okorokov, V; Olson, D; Pachr, M; Page, B S; Pal, S K; Pandit, Y; Panebratsev, Y; Pawlak, T; Peitzmann, T; Perevoztchikov, V; Perkins, C; Peryt, W; Phatak, S C; Pile, P; Planinic, M; Pluta, J; Plyku, D; Poljak, N; Poskanzer, A M; Potukuchi, B V K S; Prindle, D; Pruneau, C; Pruthi, N K; Pujahari, P R; Putschke, J; Raniwala, R; Raniwala, S; Redwine, R; Reed, R; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Rose, A; Roy, C; Ruan, L; Russcher, M J; Sahoo, R; Sakrejda, I; Sakuma, T; Salur, S; Sandweiss, J; Sarsour, M; Schambach, J; Scharenberg, R P; Schmitz, N; Seger, J; Selyuzhenkov, I; Seyboth, P; Shabetai, A; Shahaliev, E; Shao, M; Sharma, M; Shi, S S; Shi, X-H; Sichtermann, E P; Simon, F; Singaraju, R N; Skoby, M J; Smirnov, N; Snellings, R; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stadnik, A; Stanislaus, T D S; Staszak, D; Strikhanov, M; Stringfellow, B; Suaide, A A P; Suarez, M C; Subba, N L; Sumbera, M; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Symons, T J M; de Toledo, A Szanto; Takahashi, J; Tang, A H; Tang, Z; Tarini, L H; Tarnowsky, T; Thein, D; Thomas, J H; Tian, J; Timmins, A R; Timoshenko, S; Tlusty, D; Tokarev, M; Tram, V N; Trattner, A L; Trentalange, S; Tribble, R E; Tsai, O D; Ulery, J; Ullrich, T; Underwood, D G; Van Buren, G; van Leeuwen, M; Molen, A M Vander; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasilevski, I M; Vasiliev, A N; Videbaek, F; Vigdor, S E; Viyogi, Y P; Vokal, S; Voloshin, S A; Wada, M; Walker, M; Wang, F; Wang, G; Wang, J S; Wang, Q; Wang, X; Wang, X L; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wu, Y; Xie, W; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yang, P; Yepes, P; Yip, K; Yoo, I-K; Yue, Q; Zawisza, M; Zbroszczyk, H; Zhan, W; Zhang, S; Zhang, W M; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, Y; Zhong, C; Zhou, J; Zoulkarneev, R; Zoulkarneeva, Y; Zuo, J X

    2009-08-28

    We report K/pi fluctuations from Au + Au collisions at sqrt[s(NN)]= 19.6, 62.4, 130, and 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider. K/pi fluctuations in central collisions show little dependence on incident energy and are on the same order as those from NA49 at the Super Proton Synchrotron in central Pb + Pb collisions at sqrt[s(NN)]=12.3 and 17.3 GeV. We report results for the collision centrality dependence of K/pi fluctuations and results for charge-separated fluctuations. We observe that the K/pi fluctuations scale with the charged particle multiplicity density. PMID:19792791

  8. Fluctuation Probes of Quark Deconfinement

    SciTech Connect

    Asakawa, Masayuki; Heinz, Ulrich; Mueller, Berndt

    2000-09-04

    The size of the average fluctuations of net baryon number and electric charge in a finite volume of hadronic matter differs widely between the confined and deconfined phases. These differences may be exploited as indicators of the formation of a quark-gluon plasma in relativistic heavy-ion collisions, because fluctuations created in the initial state survive until freeze-out due to the rapid expansion of the hot fireball. (c) 2000 The American Physical Society.

  9. Event-by-event elliptic flow fluctuations from PHOBOS.

    SciTech Connect

    Alver, B.; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Physics; BNL; Inst. of Nuclear Physics; Massachusetts Inst. of Tech.; National Central Univ.; Univ. of Maryland; Univ. of Rochester

    2009-04-01

    Recently PHOBOS has focused on the study of fluctuations and correlations in particle production in heavy-ion collisions at the highest energies delivered by the Relativistic Heavy Ion Collider (RHIC). In this report, we present results on event-by-event elliptic flow fluctuations in Au + Au collisions at {radical}s{sub NN} = 200 GeV. A data-driven method was used to estimate the dominant contribution from non-flow correlations. Over the broad range of collision centralities, the observed large elliptic flow fluctuations are in agreement with the fluctuations in the initial source eccentricity.

  10. Waiting for rare entropic fluctuations

    NASA Astrophysics Data System (ADS)

    Saito, Keiji; Dhar, Abhishek

    2016-06-01

    Nonequilibrium fluctuations of various stochastic variables, such as work and entropy production, have been widely discussed recently in the context of large deviations, cumulants and fluctuation relations. Typically one looks at the probability distributions for entropic fluctuations of various sizes to occur in a fixed time interval. An important and natural question is to ask for the time one has to wait to see fluctuations of a desired size. We address this question by studying the first-passage time distribution (FPTD). We derive the general basic equation to get the FPTD for entropic variables. Based on this, the FPTD on entropy production in a driven colloidal particle in the ring geometry is illustrated. A general asymptotic form of the FPTD and integral fluctuation relation symmetry in terms of the first passages are found.

  11. Transverse Momentum Fluctuations at RHIC

    NASA Astrophysics Data System (ADS)

    Gavin, Sean; Abdel-Aziz, Mohamed

    2004-10-01

    PHENIX and STAR data in Au+Au collisions at RHIC show that transverse momentum fluctuations increase as centrality increases. The approach to local thermal equilibrium can explain the similar centrality dependence of the average transverse momentum and its fluctuations [1]. Alternatively, this dependence can be attributed to jet effects, although the mechanism has not been spelled out in the literature [2]. Certainly both mechanisms play a role at some level. We review the nonequilibrium description of parton thermalization in [1]. We then extend the formulation to account for contributions to fluctuations from the energy loss of the high transverse momentum particles. Calculations are then compared to the measured average transverse momentum and its fluctuations. We then discuss how correlation function measurements may distinguish these effects. [1] Sean Gavin, Phys.Rev.Lett. 92 (2004) 162301. [2] S. S. Adler et al. [PHENIX Collaboration], arXiv:nucl-ex/0310005.

  12. Parametric instability of classical Yang-Mills fields in an expanding geometry

    NASA Astrophysics Data System (ADS)

    Tsutsui, Shoichiro; Kunihiro, Teiji; Ohnishi, Akira

    2016-07-01

    We investigate the instability of a classical Yang-Mills field in an expanding geometry under a color magnetic background field within the linear regime. We consider homogeneous, boost-invariant, and time-dependent color magnetic fields simulating the glasma configuration. We introduce the conformal coordinates which enable us to map an expanding problem approximately into a nonexpanding problem. We find that the fluctuations with finite longitudinal momenta can grow exponentially due to parametric instability. Fluctuations with finite transverse momenta can also show parametric instability, but their momenta are restricted to be small. The most unstable modes start to grow exponentially in the early stage of the dynamics, and they may affect the thermalization in heavy-ion collisions.

  13. K/pi Fluctuations at Relativistic Energies

    SciTech Connect

    STAR Collaboration; Abelev, B.I.

    2009-08-24

    We report results for K/{pi} fluctuations from Au+Au collisions at {radical}sNN = 19.6, 62.4, 130, and 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider. Our results for K/{pi} fluctuations in central collisions show little dependence on the incident energies studied and are on the same order as results observed by NA49 at the Super Proton Synchrotron in central Pb+Pb collisions at {radical}sNN = 12.3 and 17.3 GeV. We also report results for the collision centrality dependence of K/{pi} fluctuations as well as results for K{sup +}/{pi}{sup +}, K{sup -}/{pi}{sup -}, K{sup +}/{pi}{sup -}, and K{sup -}/{pi}{sup +} fluctuations. We observe that the K/{pi} fluctuations scale with the multiplicity density, dN/d{eta}, rather than the number of participating nucleons.

  14. Molecular Geometry.

    ERIC Educational Resources Information Center

    Desseyn, H. O.; And Others

    1985-01-01

    Compares linear-nonlinear and planar-nonplanar geometry through the valence-shell electron pairs repulsion (V.S.E.P.R.), Mulliken-Walsh, and electrostatic force theories. Indicates that although the V.S.E.P.R. theory has more advantages for elementary courses, an explanation of the best features of the different theories offers students a better…

  15. Fluctuations of cross sections seen in cosmic ray data

    SciTech Connect

    Wilk, G. ); Wlodarczyk, Z. )

    1994-08-01

    We argue that the unexpected nonexponential behavior of some cosmic ray data is just a manifestation of cross section fluctuations discussed recently in the literature and observed in nuclear collisions and in diffraction dissociation experiments on accelerators.

  16. Interaction matrix element fluctuations in quantum dots

    SciTech Connect

    Kaplan, L.; Alhassid, Y.

    2008-04-04

    In the Coulomb blockade regime of a ballistic quantum dot, the distribution of conductance peak spacings is well known to be incorrectly predicted by a single-particle picture; instead, matrix element fluctuations of the residual electronic interaction need to be taken into account. In the normalized random-wave model, valid in the semiclassical limit where the number of electrons in the dot becomes large, we obtain analytic expressions for the fluctuations of two-body and one-body matrix elements. However, these fluctuations may be too small to explain low-temperature experimental data. We have examined matrix element fluctuations in realistic chaotic geometries, and shown that at energies of experimental interest these fluctuations generically exceed by a factor of about 3-4 the predictions of the random wave model. Even larger fluctuations occur in geometries with a mixed chaotic-regular phase space. These results may allow for much better agreement between the Hartree-Fock picture and experiment. Among other findings, we show that the distribution of interaction matrix elements is strongly non-Gaussian in the parameter range of experimental interest, even in the random wave model. We also find that the enhanced fluctuations in realistic geometries cannot be computed using a leading-order semiclassical approach, but may be understood in terms of short-time dynamics.

  17. Evolution of fluctuations near QCD critical point

    SciTech Connect

    Stephanov, M. A.

    2010-03-01

    We propose to describe the time evolution of quasistationary fluctuations near QCD critical point by a system of stochastic Boltzmann-Langevin-Vlasov-type equations. We derive the equations and study the system analytically in the linearized regime. Known results for equilibrium stationary fluctuations as well as the critical scaling of diffusion coefficient are reproduced. We apply the approach to the long-standing question of the fate of the critical point fluctuations during the hadronic rescattering stage of the heavy-ion collision after chemical freeze-out. We find that if conserved particle number fluctuations survive the rescattering, so do, under a certain additional condition, the fluctuations of nonconserved quantities, such as mean transverse momentum. We derive a simple analytical formula for the magnitude of this memory effect.

  18. Cold nuclear matter effects on J/ψ yields as a function of rapidity and nuclear geometry in d+A collisions at sqrt[s(NN)]=200  GeV.

    PubMed

    Adare, A; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Angerami, A; Aoki, K; Apadula, N; Aphecetche, L; Aramaki, Y; Asai, J; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Basye, A T; Bathe, S; Batsouli, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bhom, J H; Bickley, A A; Blau, D S; Boissevain, J G; Bok, J S; Borel, H; Boyle, K; Brooks, M L; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Caringi, A; Chang, B S; Chang, W C; Charvet, J-L; Chen, C-H; Chernichenko, S; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Churyn, A; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Conesa del Valle, Z; Connors, M; Constantin, P; Csanád, M; Csörgo, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Dayananda, M K; Denisov, A; d'Enterria, D; Deshpande, A; Desmond, E J; Dharmawardane, K V; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Dubey, A K; Durham, J M; Durum, A; Dutta, D; Dzhordzhadze, V; D'Orazio, L; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Eyser, K O; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grim, G; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Hadj Henni, A; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Hartouni, E P; Haruna, K; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Iinuma, H; Ikeda, Y; Imai, K; Imrek, J; Inaba, M; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Iwanaga, Y; Jacak, B V; Jia, J; Jiang, X; Jin, J; Johnson, B M; Jones, T; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kang, J H; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kikuchi, J; Kim, A; Kim, B I; Kim, D H; Kim, D J; Kim, E; Kim, E J; Kim, S H; Kim, Y-J; Kinney, E; Kiriluk, K; Kiss, Á; Kistenev, E; Klay, J; Klein-Boesing, C; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kozlov, A; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Layton, D; Lebedev, A; Lee, D M; Lee, J; Lee, K B; Lee, K S; Lee, T; Leitch, M J; Leite, M A L; Lenzi, B; Li, X; Lichtenwalner, P; Liebing, P; Linden Levy, L A; Liška, T; Litvinenko, A; Liu, H; Liu, M X; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mannel, E; Mao, Y; Mašek, L; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; McGlinchey, D; Means, N; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Mikeš, P; Miki, K; Milov, A; Mishra, M; Mitchell, J T; Mohanty, A K; Moon, H J; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Mukhopadhyay, D; Murakami, T; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nam, S; Newby, J; Nguyen, M; Nihashi, M; Niita, T; Nouicer, R; Nyanin, A S; Oakley, C; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, I H; Park, J; Park, S K; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Petti, R; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Rembeczki, S; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Ružička, P; Rykov, V L; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakai, S; Sakashita, K; Samsonov, V; Sano, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Semenov, V; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Suire, C; Sukhanov, A; Sziklai, J; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarján, P; Themann, H; Thomas, D; Thomas, T L; Togawa, M; Toia, A; Tomášek, L; Tomita, Y; Torii, H; Towell, R S; Tram, V-N; Tserruya, I; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Vinogradov, A A; Virius, M; Vossen, A; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Woody, C L; Wright, R M; Wysocki, M; Xie, W; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; You, Z; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zaudtke, O; Zhang, C; Zhou, S; Zolin, L

    2011-09-30

    We present measurements of J/ψ yields in d+Au collisions at sqrt[s(NN)]=200  GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/ψ rapidity (-2.2

  19. Cold Nuclear Matter Effects on J/{psi} Yields as a Function of Rapidity and Nuclear Geometry in d+A Collisions at {radical}(s{sub NN})=200 GeV

    SciTech Connect

    Adare, A.; Bickley, A. A.; Ellinghaus, F.; Kinney, E.; Kiriluk, K.; Linden Levy, L. A.; Nagle, J. L.; Rosen, C. A.; Seele, J.; Wysocki, M.; Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L.; Aidala, C.; Datta, A.; Ajitanand, N. N.

    2011-09-30

    We present measurements of J/{psi} yields in d+Au collisions at {radical}(s{sub NN})=200 GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/{psi} rapidity (-2.2

  20. A unified theory of tokamak transport via the generalized Balescu--Lenard collision operator

    SciTech Connect

    Mynick, H.E.; Duvall, R.E.

    1988-06-01

    A unified basis from which to study the transport of tokamaks at low collisionality is provided by specializing the ''generalized Balescu--Lenard'' collision operator to toridal geometry. Explicitly evaluating this operator, ripple, turbulent, and neoclassical transport coefficients are obtained, simply by further specializing the single operator to different particular classes of fluctuation wavelength and mode structure. For each class of fluctuations, the operator possesses a diffusive, test-particle contribution D, and in addition a dynamic drag term F, which makes the operator self-consistent, and whose presence is accordingly essential for the resultant fluxes to possess the appropriate conservation laws and symmetrics. These properties, well-known for axisymmetric transport, are demonstrated for one type of turbulent transport, chosen for definiteness, by explicit evaluation of both ''anomalous diffusion'' term arising from D, as well as the closely related test particle calculations, but is shown to have an important impact on the predicted fluxes. 16 refs., 1 fig.

  1. Collision tectonics

    SciTech Connect

    Coward, M.P.; Ries, A.C.

    1985-01-01

    The motions of lithospheric plates have produced most existing mountain ranges, but structures produced as a result of, and following the collision of continental plates need to be distinguished from those produced before by subduction. If subduction is normally only stopped when collision occurs, then most geologically ancient fold belts must be collisional, so it is essential to recognize and understand the effects of the collision process. This book consists of papers that review collision tectonics, covering tectonics, structure, geochemistry, paleomagnetism, metamorphism, and magmatism.

  2. Azimuthal anisotropy of π0 and η mesons in Au + Au collisions at √sNN =200 GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Alexander, J.; Aoki, K.; Aramaki, Y.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bickley, A. A.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Constantin, P.; Csanád, M.; Csörgő, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Dutta, D.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Garishvili, I.; Glenn, A.; Gong, H.; Gonin, M.; Goto, Y.; de Cassagnac, R. Granier; Grau, N.; Greene, S. V.; Perdekamp, M. Grosse; Gunji, T.; Gustafsson, H.-Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Hartouni, E. P.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Ide, J.; Ikeda, Y.; Imai, K.; Inaba, M.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Jacak, B. V.; Jia, J.; Jin, J.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kang, J. H.; Kapustinsky, J.; Karatsu, K.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E.-J.; Kim, S. H.; Kim, Y.-J.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kotchetkov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K.; Lee, K. B.; Lee, K. S.; Leitch, M. J.; Leite, M. A. L.; Leitner, E.; Lenzi, B.; Li, X.; Liebing, P.; Levy, L. A. Linden; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Luechtenborg, R.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; Matathias, F.; McCumber, M.; McGaughey, P. L.; Means, N.; Meredith, B.; Miake, Y.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, M.; Mitchell, J. T.; Mohanty, A. K.; Morino, Y.; Morreale, A.; Morrison, D. P.; Moukhanova, T. V.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Nouicer, R.; Nyanin, A. S.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ružička, P.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakashita, K.; Samsonov, V.; Sano, S.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Sparks, N. A.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sziklai, J.; Takagui, E. M.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tarján, P.; Themann, H.; Thomas, T. L.; Togawa, M.; Toia, A.; Tomášek, L.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Vale, C.; Valle, H.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Wei, F.; Wei, R.; Wessels, J.; White, S. N.; Winter, D.; Wood, J. P.; Woody, C. L.; Wright, R. M.; Wysocki, M.; Xie, W.; Yamaguchi, Y. L.; Yamaura, K.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zhang, C.; Zhou, S.; Zolin, L.; Phenix Collaboration

    2013-12-01

    The azimuthal anisotropy coefficients v2 and v4 of π0 and η mesons are measured in Au + Au collisions at √sNN =200 GeV as a function of transverse momentum pT (1-14 GeV/c) and centrality. The extracted v2 coefficients are found to be consistent between the two meson species over the measured pT range. The ratio of v4/v22 for π0 mesons is found to be independent of pT for 1-9 GeV/c, implying a lack of sensitivity of the ratio to the change of underlying physics with pT. Furthermore, the ratio of v4/v22 is systematically larger in central collisions, which may reflect the combined effects of fluctuations in the initial collision geometry and finite viscosity in the evolving medium.

  3. Causal Diffusion and the Survival of Charge Fluctuations

    NASA Astrophysics Data System (ADS)

    Abdel-Aziz, Mohamed; Gavin, Sean

    2004-10-01

    Diffusion may obliterate fluctuation signals of the QCD phase transition in nuclear collisions at SPS and RHIC energies. We propose a hyperbolic diffusion equation to study the dissipation of net charge fluctuations [1]. This equation is needed in a relativistic context, because the classic parabolic diffusion equation violates causality. We find that causality substantially limits the extent to which diffusion can dissipate these fluctuations. [1] M. Abdel-Aziz and S. Gavin, nucl-th/0404058

  4. On zero frequency magnetic fluctuations in plasmas

    SciTech Connect

    Tajima, T.; Cable, S. . Inst. for Fusion Studies); Kulsrud, R.M. . Dept. of Astrophysical Sciences)

    1992-01-01

    A plasma sustains fluctuations of electromagnetic fields and particle density even in a thermal equilibrium and such fluctuations have a large zero frequency peak. The level of fluctuations in the plasma for a given wavelength and frequency of electromagnetic fields is calculated through the fluctuation-dissipation theorem. The frequency spectrum shows that the energy contained in this peak is complementary to the energy lost'' by the plasma cutoff effect. The level of the zero (or nearly zero) frequency magnetic is computed as {l angle}B{sup 2}{r angle}{sup 0}/ 8{pi} = 1/2{pi}{sup 3}T({omega}{sub p}/c){sup 3}, where T and {omega}{sub p} are the temperature and plasma frequency. The relation between the nonradiative and radiative fluctuations is elucidated. Both a simple collision model and a kinetic theoretic treatment are presented with essentially the same results. The size of the fluctuations is {lambda} {approximately} (c/{omega}{sub p})({eta}/{omega}){sup {1/2}}, where {eta} and {omega} are the collision frequency and the (nearly zero) frequency of magnetic fields oscillations. Perhaps the most dramatic application of the present theory, however, is to the cosmological plasma of early epoch. Implications of these magnetic fields in the early Universe are discussed. Quantum mechanical calculations are also carried out for degenerate plasmas.

  5. On zero frequency magnetic fluctuations in plasmas

    SciTech Connect

    Tajima, T.; Cable, S.; Kulsrud, R.M.

    1992-01-01

    A plasma sustains fluctuations of electromagnetic fields and particle density even in a thermal equilibrium and such fluctuations have a large zero frequency peak. The level of fluctuations in the plasma for a given wavelength and frequency of electromagnetic fields is calculated through the fluctuation-dissipation theorem. The frequency spectrum shows that the energy contained in this peak is complementary to the energy ``lost`` by the plasma cutoff effect. The level of the zero (or nearly zero) frequency magnetic is computed as {l_angle}B{sup 2}{r_angle}{sup 0}/ 8{pi} = 1/2{pi}{sup 3}T({omega}{sub p}/c){sup 3}, where T and {omega}{sub p} are the temperature and plasma frequency. The relation between the nonradiative and radiative fluctuations is elucidated. Both a simple collision model and a kinetic theoretic treatment are presented with essentially the same results. The size of the fluctuations is {lambda} {approximately} (c/{omega}{sub p})({eta}/{omega}){sup {1/2}}, where {eta} and {omega} are the collision frequency and the (nearly zero) frequency of magnetic fields oscillations. Perhaps the most dramatic application of the present theory, however, is to the cosmological plasma of early epoch. Implications of these magnetic fields in the early Universe are discussed. Quantum mechanical calculations are also carried out for degenerate plasmas.

  6. Linear Collisions

    ERIC Educational Resources Information Center

    Walkiewicz, T. A.; Newby, N. D., Jr.

    1972-01-01

    A discussion of linear collisions between two or three objects is related to a junior-level course in analytical mechanics. The theoretical discussion uses a geometrical approach that treats elastic and inelastic collisions from a unified point of view. Experiments with a linear air track are described. (Author/TS)

  7. Nonmonotonic Thermal Casimir Force from Geometry-Temperature Interplay

    SciTech Connect

    Weber, Alexej; Gies, Holger

    2010-07-23

    The geometry dependence of Casimir forces is significantly more pronounced in the presence of thermal fluctuations due to a generic geometry-temperature interplay. We show that the thermal force for standard sphere-plate or cylinder-plate geometries develops a nonmonotonic behavior already in the simple case of a fluctuating Dirichlet scalar. In particular, the attractive thermal force can increase for increasing distances below a critical temperature. This anomalous behavior is triggered by a reweighting of relevant fluctuations on the scale of the thermal wavelength. The essence of the phenomenon becomes transparent within the worldline picture of the Casimir effect.

  8. Lévy walks with velocity fluctuations.

    PubMed

    Denisov, S; Zaburdaev, V; Hänggi, P

    2012-03-01

    The standard Lévy walk is performed by a particle that moves ballistically between randomly occurring collisions when the intercollision time is a random variable governed by a power-law distribution. During instantaneous collision events, the particle randomly changes the direction of motion but maintains the same constant speed. We generalize the standard model to incorporate velocity fluctuations into the process. Two types of models are considered, namely (i) with a walker changing the direction and absolute value of its velocity during collisions only, and (ii) with a walker whose velocity continuously fluctuates. We present a full analytic evaluation of both models and emphasize the importance of initial conditions. We show that, in the limit of weak velocity fluctuations, the integral diffusion characteristics and the bulk of diffusion profiles are identical to those for the standard Lévy walk. However, the type of underlying velocity fluctuations can be identified by looking at the ballistic regions of the diffusion profiles. Our analytical results are corroborated by numerical simulations. PMID:22587079

  9. Casimir effects for classical and quantum liquids in slab geometry: A brief review

    SciTech Connect

    Biswas, Shyamal

    2015-05-15

    We analytically explore Casimir effects for confinement of classical and quantum fluctuations in slab (film) geometry (i) for classical (critical) fluctuations over {sup 4}He liquid around the λ point, and (ii) for quantum (phonon) fluctuations of Bogoliubov excitations over an interacting Bose-Einstein condensate. We also briefly review Casimir effects for confinement of quantum vacuum fluctuations confined to two plates of different geometries.

  10. Measurements of Higher Order Flow Harmonics in Au+Au Collisions at sNN=200GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Alexander, J.; Aoki, K.; Aramaki, Y.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bickley, A. A.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Constantin, P.; Csanád, M.; Csörgő, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Dutta, D.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'Yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M., Jr.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Garishvili, I.; Glenn, A.; Gong, H.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Hartouni, E. P.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Ide, J.; Ikeda, Y.; Imai, K.; Inaba, M.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Jacak, B. V.; Jia, J.; Jin, J.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kang, J. H.; Kapustinsky, J.; Karatsu, K.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E. J.; Kim, S. H.; Kim, Y. J.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kotchetkov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K.; Lee, K. B.; Lee, K. S.; Leitch, M. J.; Leite, M. A. L.; Leitner, E.; Lenzi, B.; Li, X.; Liebing, P.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Luechtenborg, R.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; Matathias, F.; McCumber, M.; McGaughey, P. L.; Means, N.; Meredith, B.; Miake, Y.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, M.; Mitchell, J. T.; Mohanty, A. K.; Morino, Y.; Morreale, A.; Morrison, D. P.; Moukhanova, T. V.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Nouicer, R.; Nyanin, A. S.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ružička, P.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakashita, K.; Samsonov, V.; Sano, S.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Sparks, N. A.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sziklai, J.; Takagui, E. M.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tarján, P.; Themann, H.; Thomas, T. L.; Togawa, M.; Toia, A.; Tomášek, L.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Vale, C.; Valle, H.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Wei, F.; Wei, R.; Wessels, J.; White, S. N.; Winter, D.; Wood, J. P.; Woody, C. L.; Wright, R. M.; Wysocki, M.; Xie, W.; Yamaguchi, Y. L.; Yamaura, K.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zhang, C.; Zhou, S.; Zolin, L.

    2011-12-01

    Flow coefficients vn for n=2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at sNN=200GeV, are measured relative to event planes Ψn, determined at large rapidity. We report vn as a function of transverse momentum and collision centrality, and study the correlations among the event planes of different order n. The vn are well described by hydrodynamic models which employ a Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on the interplay between initial conditions and the effects of viscosity as the system evolves. This new constraint can serve to improve the precision of the extracted shear viscosity to entropy density ratio η/s.

  11. Measurements of higher order flow harmonics in Au+Au collisions at √s(NN)=200 GeV.

    PubMed

    Adare, A; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Aoki, K; Aramaki, Y; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bickley, A A; Bok, J S; Boyle, K; Brooks, M L; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Chen, C-H; Chi, C Y; Chiu, M; Choi, I J; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Connors, M; Constantin, P; Csanád, M; Csörgo, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Hartouni, E P; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Ide, J; Ikeda, Y; Imai, K; Inaba, M; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Jacak, B V; Jia, J; Jin, J; Johnson, B M; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kang, J H; Kapustinsky, J; Karatsu, K; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kim, B I; Kim, D H; Kim, D J; Kim, E; Kim, E J; Kim, S H; Kim, Y J; Kinney, E; Kiriluk, K; Kiss, Á; Kistenev, E; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotchetkov, D; Kozlov, A; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K; Lee, K B; Lee, K S; Leitch, M J; Leite, M A L; Leitner, E; Lenzi, B; Li, X; Liebing, P; Linden Levy, L A; Liška, T; Litvinenko, A; Liu, H; Liu, M X; Love, B; Luechtenborg, R; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; Means, N; Meredith, B; Miake, Y; Mignerey, A C; Mikeš, P; Miki, K; Milov, A; Mishra, M; Mitchell, J T; Mohanty, A K; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, T; Nakano, K; Newby, J; Nguyen, M; Nouicer, R; Nyanin, A S; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, I H; Park, J; Park, S K; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Ružička, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Sparks, N A; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sziklai, J; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarján, P; Themann, H; Thomas, T L; Togawa, M; Toia, A; Tomášek, L; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Vinogradov, A A; Virius, M; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Wood, J P; Woody, C L; Wright, R M; Wysocki, M; Xie, W; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; You, Z; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zolin, L

    2011-12-16

    Flow coefficients ν(n) for n=2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at √s(NN)=200 GeV, are measured relative to event planes Ψ(n), determined at large rapidity. We report ν(n) as a function of transverse momentum and collision centrality, and study the correlations among the event planes of different order n. The ν(n) are well described by hydrodynamic models which employ a Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on the interplay between initial conditions and the effects of viscosity as the system evolves. This new constraint can serve to improve the precision of the extracted shear viscosity to entropy density ratio η/s.

  12. Measurements of Higher Order Flow Harmonics in Au plus Au collisions at root s(NN)=200 Gev

    SciTech Connect

    Adare A.; PHENIX Collaboration

    2011-12-01

    Flow coefficients v{sub n} for n = 2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at {radical}s{sub NN} = 200 GeV, are measured relative to event planes {Psi}{sub n}, determined at large rapidity. We report v{sub n} as a function of transverse momentum and collision centrality, and study the correlations among the event planes of different order n. The v{sub n} are well described by hydrodynamic models which employ a Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on the interplay between initial conditions and the effects of viscosity as the system evolves. This new constraint can serve to improve the precision of the extracted shear viscosity to entropy density ratio {eta}/s.

  13. Beam Energy and System Size Dependence of Dynamical Net Charge Fluctuations

    SciTech Connect

    STAR Coll

    2008-07-21

    We present measurements of net charge fluctuations in Au + Au collisions at {radical}s{sub NN} = 19.6, 62.4, 130, and 200 GeV, Cu + Cu collisions at {radical}s{sub NN} = 62.4, 200 GeV, and p + p collisions at {radical}s = 200 GeV using the dynamical net charge fluctuations measure {nu}{sub {+-},dyn}. We observe that the dynamical fluctuations are non-zero at all energies and exhibit a modest dependence on beam energy. A weak system size dependence is also observed. We examine the collision centrality dependence of the net charge fluctuations and find that dynamical net charge fluctuations violate 1/N{sub ch} scaling, but display approximate 1/N{sub part} scaling. We also study the azimuthal and rapidity dependence of the net charge correlation strength and observe strong dependence on the azimuthal angular range and pseudorapidity widths integrated to measure the correlation.

  14. Convection in Slab and Spheroidal Geometries

    NASA Technical Reports Server (NTRS)

    Porter, David H.; Woodward, Paul R.; Jacobs, Michael L.

    2000-01-01

    Three-dimensional numerical simulations of compressible turbulent thermally driven convection, in both slab and spheroidal geometries, are reviewed and analyzed in terms of velocity spectra and mixing-length theory. The same ideal gas model is used in both geometries, and resulting flows are compared. The piecewise-parabolic method (PPM), with either thermal conductivity or photospheric boundary conditions, is used to solve the fluid equations of motion. Fluid motions in both geometries exhibit a Kolmogorov-like k(sup -5/3) range in their velocity spectra. The longest wavelength modes are energetically dominant in both geometries, typically leading to one convection cell dominating the flow. In spheroidal geometry, a dipolar flow dominates the largest scale convective motions. Downflows are intensely turbulent and up drafts are relatively laminar in both geometries. In slab geometry, correlations between temperature and velocity fluctuations, which lead to the enthalpy flux, are fairly independent of depth. In spheroidal geometry this same correlation increases linearly with radius over the inner 70 percent by radius, in which the local pressure scale heights are a sizable fraction of the radius. The effects from the impenetrable boundary conditions in the slab geometry models are confused with the effects from non-local convection. In spheroidal geometry nonlocal effects, due to coherent plumes, are seen as far as several pressure scale heights from the lower boundary and are clearly distinguishable from boundary effects.

  15. Eventwise mean-pt fluctuations versus minimum-bias jets (minijets) at energies available at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Trainor, Thomas A.

    2015-08-01

    Fluctuation measurements of eventwise mean transverse momentum for p -p and Pb-Pb collisions at the CERN Large Hadron Collider (LHC) have been reported recently. In that study it was concluded that the strength of "nonstatistical" fluctuations decreases with increasing particle multiplicity nch (or A -A centrality) and is nearly independent of collision energy over a large interval. Among several potential mechanisms for those trends the onset of thermalization and collectivity are mentioned. The LHC analysis employed one fluctuation measure selected from several possibilities. An alternative fluctuation measure reveals a strong increase of pt fluctuations with nc h (or A -A centrality) and collision energy, consistent with previous measurements at the BNL Relativistic Heavy Ion Collider (RHIC). The pt fluctuation data for LHC p -p collisions can be described accurately by a two-component (soft +hard ) model (TCM) in which the hard component represents dijet production. The data for Pb-Pb collisions are described accurately by a TCM reference for more-peripheral collisions (suggesting transparent collisions), but the data deviate quantitatively from the reference for more-central collisions, suggesting a modification of jet formation. Overall fluctuation data trends suggest that minimum-bias jets (minijets) dominate pt fluctuations at both the LHC and the RHIC.

  16. Evidence of Strong Proton Shape Fluctuations from Incoherent Diffraction.

    PubMed

    Mäntysaari, Heikki; Schenke, Björn

    2016-07-29

    We show within the saturation framework that measurements of exclusive vector meson production at high energy provide evidence for strong geometric fluctuations of the proton. In comparison, the effect of saturation scale and color charge fluctuations is weak. This knowledge will allow detailed future measurements of the incoherent cross section to tightly constrain the fluctuating geometry of the proton as a function of the parton momentum fraction x. PMID:27517767

  17. Evidence of Strong Proton Shape Fluctuations from Incoherent Diffraction

    NASA Astrophysics Data System (ADS)

    Mäntysaari, Heikki; Schenke, Björn

    2016-07-01

    We show within the saturation framework that measurements of exclusive vector meson production at high energy provide evidence for strong geometric fluctuations of the proton. In comparison, the effect of saturation scale and color charge fluctuations is weak. This knowledge will allow detailed future measurements of the incoherent cross section to tightly constrain the fluctuating geometry of the proton as a function of the parton momentum fraction x .

  18. Vorticity in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Deng, Wei-Tian; Huang, Xu-Guang

    2016-06-01

    We study the event-by-event generation of flow vorticity in the BNL Relativistic Heavy Ion Collider Au +Au collisions and CERN Large Hadron Collider Pb +Pb collisions by using the hijing model. Different definitions of the vorticity field and velocity field are considered. A variety of properties of the vorticity are explored, including the impact parameter dependence, the collision energy dependence, the spatial distribution, the event-by-event fluctuation of the magnitude and azimuthal direction, and the time evolution. In addition, the spatial distribution of the flow helicity is also studied.

  19. Theoretical Concepts for Ultra-Relativistic Heavy Ion Collisions

    SciTech Connect

    McLerran,L.

    2009-07-27

    Various forms of matter may be produced in ultra-relativistic heavy ion collisions. These are the Quark GluonPlasma, the Color Glass Condensate , the Glasma and Quarkyoninc Matter. A novel effect that may beassociated with topological charge fluctuations is the Chiral Magnetic Effect. I explain these concepts andexplain how they may be seen in ultra-relatvistic heavy ion collisions

  20. Reactive Collision Avoidance Algorithm

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel; Acikmese, Behcet; Ploen, Scott; Hadaegh, Fred

    2010-01-01

    The reactive collision avoidance (RCA) algorithm allows a spacecraft to find a fuel-optimal trajectory for avoiding an arbitrary number of colliding spacecraft in real time while accounting for acceleration limits. In addition to spacecraft, the technology can be used for vehicles that can accelerate in any direction, such as helicopters and submersibles. In contrast to existing, passive algorithms that simultaneously design trajectories for a cluster of vehicles working to achieve a common goal, RCA is implemented onboard spacecraft only when an imminent collision is detected, and then plans a collision avoidance maneuver for only that host vehicle, thus preventing a collision in an off-nominal situation for which passive algorithms cannot. An example scenario for such a situation might be when a spacecraft in the cluster is approaching another one, but enters safe mode and begins to drift. Functionally, the RCA detects colliding spacecraft, plans an evasion trajectory by solving the Evasion Trajectory Problem (ETP), and then recovers after the collision is avoided. A direct optimization approach was used to develop the algorithm so it can run in real time. In this innovation, a parameterized class of avoidance trajectories is specified, and then the optimal trajectory is found by searching over the parameters. The class of trajectories is selected as bang-off-bang as motivated by optimal control theory. That is, an avoiding spacecraft first applies full acceleration in a constant direction, then coasts, and finally applies full acceleration to stop. The parameter optimization problem can be solved offline and stored as a look-up table of values. Using a look-up table allows the algorithm to run in real time. Given a colliding spacecraft, the properties of the collision geometry serve as indices of the look-up table that gives the optimal trajectory. For multiple colliding spacecraft, the set of trajectories that avoid all spacecraft is rapidly searched on

  1. Identity method-a new tool for studying chemical fluctuations

    SciTech Connect

    Mackowiak, M.

    2012-06-15

    Event-by-event fluctuations of the chemical composition of the hadronic system produced in nuclear collisions are believed to be sensitive to properties of the transition between confined and deconfined strongly interacting matter. In this paper a new technique for the study of chemical fluctuation, the identity method, is introduced and its features are discussed. The method is tested using data on central PbPb collisions at 40 A GeV registered by the NA49 experiment at the CERN SPS.

  2. Effective cosmological constant induced by stochastic fluctuations of Newton's constant

    NASA Astrophysics Data System (ADS)

    de Cesare, Marco; Lizzi, Fedele; Sakellariadou, Mairi

    2016-09-01

    We consider implications of the microscopic dynamics of spacetime for the evolution of cosmological models. We argue that quantum geometry effects may lead to stochastic fluctuations of the gravitational constant, which is thus considered as a macroscopic effective dynamical quantity. Consistency with Riemannian geometry entails the presence of a time-dependent dark energy term in the modified field equations, which can be expressed in terms of the dynamical gravitational constant. We suggest that the late-time accelerated expansion of the Universe may be ascribed to quantum fluctuations in the geometry of spacetime rather than the vacuum energy from the matter sector.

  3. Probing Quark Gluon Liquid Using Transverse Momentum Fluctuations

    NASA Astrophysics Data System (ADS)

    Abdel-Aziz, Mohamed; Gavin, Sean

    2006-08-01

    The onset of equilibration of partons in nuclear collisions may lead to related trends in the centrality dependence of , p fluctuations, and net charge fluctuations [S. Gavin, Phys. Rev. Lett. 92, 162301 (2004); J. Phys. G 30, S1385 (2004)]. We extend the transport description of ref. [S. Gavin, Phys. Rev. Lett. 92, 162301 (2004); J. Phys. G 30, S1385 (2004)] to include radial flow.

  4. Nonlinear evolution of drift instabilities in the presence of collisions

    SciTech Connect

    Federici, J.F.; Lee, W.W.; Tang, W.M.

    1986-07-01

    Nonlinear evolution of drift instabilities in the presence of electron-ion collisions in a shear-free slab has been studied by using gyrokinetic particle simulation techniques as well as by solving, both numerically and analytically, model mode-coupling equations. The purpose of the investigation is to determine the mechanisms responsible for the nonlinear saturation of the instability and for the ensuing steady-state transport. Such an insight is very valuable for understanding drift wave problems in more complicated geometries. The results indicate that the electron E x B convection is the dominant mechanism for saturation. It is also found that the saturation amplitude and the associated quasilinear diffusion are greatly enhanced over their collisionless values as a result of weak collisions. In the highly collisional (fluid) limit, there is an upper bound for saturation with ephi/T/sub e/ approx. = (..omega../sub l//..cap omega../sub i/)/(k/sub perpendicular/rho/sub s/)/sup 2/. The associated quasilinear diffusion, which increases with collisionality, takes the form of D/sub ql/ approx. = ..gamma../sub l//k/sub perpendicular//sup 2/, where ..omega../sub l/ and ..gamma../sub l/ are the linear frequency and growth rate, respectively. In the steady state, the diffusion process becomes stochastic in nature. The relevant mechanisms here are related to the velocity-space nonlinearities and background fluctuations. The magnitude of the diffusion at this stage can be comparable to that of quasilinear diffusion in the presence of collisions, and it remains finite even in the collisionless limit.

  5. Geometry in Medias Res

    ERIC Educational Resources Information Center

    Cukier, Mimi; Asdourian, Tony; Thakker, Anand

    2012-01-01

    Geometry provides a natural window into what it is like to do mathematics. In the world of geometry, playful experimentation is often more fruitful than following a procedure, and logic plus a few axioms can open new worlds. Nonetheless, teaching a geometry course in a way that combines both rigor and play can be difficult. Many geometry courses…

  6. Revealing "flickering" of the interaction strength in pA collisions at the CERN LHC

    NASA Astrophysics Data System (ADS)

    Alvioli, M.; Frankfurt, L.; Guzey, V.; Strikman, M.

    2014-09-01

    Using the high-energy color fluctuation formalism to include inelastic diffractive processes and taking into account the collision geometry and short-range nucleon-nucleon correlations in nuclei, we assess various manifestations of "flickering" of the parton wave function of a rapid proton in pA interactions focusing at energies available at the CERN Large Hadron Collider (LHC) in soft QCD processes and in the special soft QCD processes accompanying hard processes. We evaluate the number of wounded nucleons, Ncoll—the number of inelastic collisions of projectiles—in these processes and find a nontrivial relation between the hard collision rate and centrality. We study the distribution over Ncoll for a hard trigger selecting configurations in the nucleon with the strength larger or smaller than the average one and argue that the pattern observed in the LHC pA measurements by CMS and ATLAS for jets carrying a large fraction of the proton momentum, xp, is consistent with the expectation that these configurations interact with the strength which is significantly smaller than the average one, a factor of two smaller for xp˜0.5. We also study the leading twist shadowing and the European Muon Collaboration effects for superdense nuclear matter configurations probed in the events with a larger-than-average number of wounded nucleons. We also argue that taking into account energy-momentum conservation does not change the distribution over Ncoll but suppresses hadron production at central rapidities.

  7. Proteins, fluctuations and complexity

    SciTech Connect

    Frauenfelder, Hans; Chen, Guo; Fenimore, Paul W

    2008-01-01

    Glasses, supercooled liquids, and proteins share common properties, in particular the existence of two different types of fluctuations, {alpha} and {beta}. While the effect of the {alpha} fluctuations on proteins has been known for a few years, the effect of {beta} fluctuations has not been understood. By comparing neutron scattering data on the protein myoglobin with the {beta} fluctuations in the hydration shell measured by dielectric spectroscopy we show that the internal protein motions are slaved to these fluctuations. We also show that there is no 'dynamic transition' in proteins near 200 K. The rapid increase in the mean square displacement with temperature in many neutron scattering experiments is quantitatively predicted by the {beta} fluctuations in the hydration shell.

  8. Correlation of transverse momentum and multiplicity in a superposition model of nucleus-nucleus collisions

    SciTech Connect

    Mrowczynski, Stanislaw

    2006-04-15

    In p-p collisions the average transverse momentum is known to be correlated with the multiplicity of produced particles. The correlation is shown to survive in a superposition model of nucleus-nucleus collisions. When properly parametrized, the correlation strength appears to be independent of the collision centrality--it is the same in p-p and central A-A collisions. However, the correlation is strongly suppressed by the centrality fluctuations.

  9. Fluctuation relations for spintronics.

    PubMed

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

    2012-06-15

    Fluctuation relations are derived in systems where the spin degree of freedom and magnetic interactions play a crucial role. The form of the nonequilibrium fluctuation theorems relies on the assumption of a local balance condition. We demonstrate that in some cases the presence of magnetic interactions violates this condition. Nevertheless, fluctuation relations can be obtained from the microreversibility principle sustained only at equilibrium as a symmetry of the cumulant generating function for spin currents. We illustrate the spintronic fluctuation relations for a quantum dot coupled to partially polarized helical edge states.

  10. Combinatorial Geometry Printer Plotting.

    1987-01-05

    Picture generates plots of two-dimensional slices through the three-dimensional geometry described by the combinatorial geometry (CG) package used in such codes as MORSE and QAD-CG. These plots are printed on a standard line printer.

  11. Collision lifetimes of polyatomic molecules at low temperatures: Benzene–benzene vs benzene–rare gas atom collisions

    SciTech Connect

    Cui, Jie; Krems, Roman V.; Li, Zhiying

    2014-10-28

    We use classical trajectory calculations to study the effects of the interaction strength and the geometry of rigid polyatomic molecules on the formation of long-lived collision complexes at low collision energies. We first compare the results of the calculations for collisions of benzene molecules with rare gas atoms He, Ne, Ar, Kr, and Xe. The comparison illustrates that the mean lifetimes of the collision complexes increase monotonically with the strength of the atom–molecule interaction. We then compare the results of the atom–benzene calculations with those for benzene–benzene collisions. The comparison illustrates that the mean lifetimes of the benzene–benzene collision complexes are significantly reduced due to non-ergodic effects prohibiting the molecules from sampling the entire configuration space. We find that the thermally averaged lifetimes of the benzene–benzene collisions are much shorter than those for Xe with benzene and similar to those for Ne with benzene.

  12. Geometry and Erdkinder.

    ERIC Educational Resources Information Center

    McDonald, Nathaniel J.

    2001-01-01

    Chronicles a teacher's first year teaching geometry at the Hershey Montessori Farm School in Huntsburg, Ohio. Instructional methods relied on Euclid primary readings and combined pure abstract logic with practical applications of geometry on the land. The course included geometry background imparted by Montessori elementary materials as well as…

  13. Metric fluctuations of an evaporating black hole from backreaction of stress tensor fluctuations

    SciTech Connect

    Hu, B. L.; Roura, Albert

    2007-12-15

    This paper delineates the first steps in a systematic quantitative study of the spacetime fluctuations induced by quantum fields in an evaporating black hole under the stochastic gravity program. The central object of interest is the noise kernel, which is the symmetrized two-point quantum correlation function of the stress tensor operator. As a concrete example we apply it to the study of the spherically symmetric sector of metric perturbations around an evaporating black hole background geometry. For macroscopic black holes we find that those fluctuations grow and eventually become important when considering sufficiently long periods of time (of the order of the evaporation time), but well before the Planckian regime is reached. In addition, the assumption of a simple correlation between the fluctuations of the energy flux crossing the horizon and far from it, which was made in earlier work on spherically symmetric induced fluctuations, is carefully scrutinized and found to be invalid. Our analysis suggests the existence of an infinite amplitude for the fluctuations when trying to localize the horizon as a three-dimensional hypersurface, as in the classical case, and, as a consequence, a more accurate picture of the horizon as possessing a finite effective width due to quantum fluctuations. This is supported by a systematic analysis of the noise kernel in curved spacetime smeared with different functions under different conditions; the details are collected in the appendixes. This case study shows a pathway for probing quantum metric fluctuations near the horizon and understanding their physical meaning.

  14. SCALING PROPERTIES OF FLUCTUATION RESULTS FROM THE PHENIX EXPERIMENT AT RHIC.

    SciTech Connect

    MITCHELL,J.T.

    2006-06-05

    The PHENIX Experiment at the Relativistic Heavy Ion Collider has made measurements of event-by-event fluctuations in the charged particle multiplicity as a function of collision energy, centrality, collision species, and transverse momentum in several heavy ion collision systems. It is observed that the fluctuations in terms of {sigma}{sup 2}/{mu}{sup 2} exhibit a universal power-law scaling as a function of N{sub participants} that is independent of the transverse momentum range of the measurement.

  15. Interferometric tests of Planckian quantum geometry models

    NASA Astrophysics Data System (ADS)

    Kwon, Ohkyung; Hogan, Craig J.

    2016-05-01

    The effect of Planck scale quantum geometrical effects on measurements with interferometers is estimated with standard physics, and with a variety of proposed extensions. It is shown that effects are negligible in standard field theory with canonically quantized gravity. Statistical noise levels are estimated in a variety of proposals for nonstandard metric fluctuations, and these alternatives are constrained using upper bounds on stochastic metric fluctuations from LIGO. Idealized models of several interferometer system architectures are used to predict signal noise spectra in a quantum geometry that cannot be described by a fluctuating metric, in which position noise arises from holographic bounds on directional information. Predictions in this case are shown to be close to current and projected experimental bounds.

  16. Interferometric tests of Planckian quantum geometry models

    DOE PAGESBeta

    Kwon, Ohkyung; Hogan, Craig J.

    2016-04-19

    The effect of Planck scale quantum geometrical effects on measurements with interferometers is estimated with standard physics, and with a variety of proposed extensions. It is shown that effects are negligible in standard field theory with canonically quantized gravity. Statistical noise levels are estimated in a variety of proposals for nonstandard metric fluctuations, and these alternatives are constrained using upper bounds on stochastic metric fluctuations from LIGO. Idealized models of several interferometer system architectures are used to predict signal noise spectra in a quantum geometry that cannot be described by a fluctuating metric, in which position noise arises from holographicmore » bounds on directional information. Lastly, predictions in this case are shown to be close to current and projected experimental bounds.« less

  17. Spatial fluctuation theorem

    NASA Astrophysics Data System (ADS)

    Pérez-Espigares, Carlos; Redig, Frank; Giardinà, Cristian

    2015-08-01

    For non-equilibrium systems of interacting particles and for interacting diffusions in d-dimensions, a novel fluctuation relation is derived. The theorem establishes a quantitative relation between the probabilities of observing two current values in different spatial directions. The result is a consequence of spatial symmetries of the microscopic dynamics, generalizing in this way the Gallavotti-Cohen fluctuation theorem related to the time-reversal symmetry. This new perspective opens up the possibility of direct experimental measurements of fluctuation relations of vectorial observables.

  18. Fluctuations In Electrohydrodynamic Instability

    NASA Astrophysics Data System (ADS)

    Bianco, Francesco; Lucchesi, Mauro; Capaccioli, Simone; Fronzoni, Leone; Allegrini, Paolo

    2005-11-01

    Electrohydrodynamic Convection in Liquid Crystals (EHC) is a good system for the experimental study of spatio-temporal chaos. Particularly interesting is the behavior of the Nematic in presence of weak turbulence where ordered and disordered states are mixed. In this case, the fluctuations of velocity and electric current, for instance, are typical fluctuations of a system far from equilibrium. Recently some authors have analyzed the amplitude of the fluctuations as function of the applied electric field and they present interesting interpretations provided by some theories. Although important results have been obtained by these authors, many aspects of the dynamical behavior have to be further analyzed as the role of some localized coherences inside the turbulence regions. The direct optical observation allows us to make a correspondence between fluctuations and patterns, providing important information for a theoretical interpretation.

  19. Onset of radial flow in p+p collisions

    DOE PAGESBeta

    Jiang, Kun; Zhu, Yinying; Liu, Weitao; Chen, Hongfang; Li, Cheng; Ruan, Lijuan; Tang, Zebo; Xu, Zhangbu

    2015-02-23

    It has been debated for decades whether hadrons emerging from p+p collisions exhibit collective expansion. The signal of the collective motion in p+p collisions is not as clear as in heavy-ion collisions because of the low multiplicity and large fluctuation in p+p collisions. Tsallis Blast-Wave (TBW) model is a thermodynamic approach, introduced to handle the overwhelming correlation and fluctuation in the hadronic processes. We have systematically studied the identified particle spectra in p+p collisions from RHIC to LHC using TBW and found no appreciable radial flow in p+p collisions below √s = 900 GeV. At LHC higher energy of 7more » TeV in p+p collisions, the radial flow velocity achieves an average of (β) = 0.320 ± 0.005. This flow velocity is comparable to that in peripheral (40-60%) Au+Au collisions at RHIC. In addition, breaking of the identified particle spectra mT scaling was also observed at LHC from a model independent test.« less

  20. Explaination of nonlocal granular fluidity in terms of microscopic fluctuations

    NASA Astrophysics Data System (ADS)

    Zhang, Qiong; Kamrin, Ken

    A recently proposed granular constitutive law has shown capability to predict nonlocal granular rheology using a variable denoted ``granular fluidity''. This work is aimed at finding the microscopic physical meaning of fluidity in terms of fluctuations such as fluctuation of normalized shear stress and fluctuation of velocity. We try to predict the fluidity as a function of the fluctuation of normalized shear stress, and also test Eyring equation and kinetic theory based on the theoretical prediction proposed in other work. We find a consistent definition for the fluidity to be proportional to the product of the velocity fluctuations and some function of packing fraction divided by the average diameter of the grains. This definition shows predictive ability in multiple geometries for which flow behavior is nonlocal. It is notable that the fluidity is well-defined as a function of kinematic state variables, as one would hope for a quantity of this nature.

  1. Revealing proton shape fluctuations with incoherent diffraction at high energy

    NASA Astrophysics Data System (ADS)

    Mäntysaari, Heikki; Schenke, Björn

    2016-08-01

    The differential cross section of exclusive diffractive vector meson production in electron proton collisions carries important information on the geometric structure of the proton. More specifically, the coherent cross section as a function of the transferred transverse momentum is sensitive to the size of the proton, while the incoherent or proton dissociative cross section is sensitive to fluctuations of the gluon distribution in coordinate space. We show that at high energies the experimentally measured coherent and incoherent cross sections for the production of J /Ψ mesons are very well reproduced within the color glass condensate framework when strong geometric fluctuations of the gluon distribution in the proton are included. For ρ meson production, we also find reasonable agreement. We study in detail the dependence of our results on various model parameters, including the average proton shape, analyze the effect of saturation scale and color charge fluctuations and constrain the degree of geometric fluctuations.

  2. Basins in ARC-continental collisions

    USGS Publications Warehouse

    Draut, Amy E.; Clift, Peter D.; Busby, Cathy; Azor, Antonio

    2012-01-01

    Arc-continent collisions occur commonly in the plate-tectonic cycle and result in rapidly formed and rapidly collapsing orogens, often spanning just 5-15 My. Growth of continental masses through arc-continent collision is widely thought to be a major process governing the structural and geochemical evolution of the continental crust over geologic time. Collisions of intra-oceanic arcs with passive continental margins (a situation in which the arc, on the upper plate, faces the continent) involve a substantially different geometry than collisions of intra-oceanic arcs with active continental margins (a situation requiring more than one convergence zone and in which the arc, on the lower plate, backs into the continent), with variable preservation potential for basins in each case. Substantial differences also occur between trench and forearc evolution in tectonically erosive versus tectonically accreting margins, both before and after collision. We examine the evolution of trenches, trench-slope basins, forearc basins, intra-arc basins, and backarc basins during arc-continent collision. The preservation potential of trench-slope basins is low; in collision they are rapidly uplifted and eroded, and at erosive margins they are progressively destroyed by subduction erosion. Post-collisional preservation of trench sediment and trench-slope basins is biased toward margins that were tectonically accreting for a substantial length of time before collision. Forearc basins in erosive margins are usually floored by strong lithosphere and may survive collision with a passive margin, sometimes continuing sedimentation throughout collision and orogeny. The low flexural rigidity of intra-arc basins makes them deep and, if preserved, potentially long records of arc and collisional tectonism. Backarc basins, in contrast, are typically subducted and their sediment either lost or preserved only as fragments in melange sequences. A substantial proportion of the sediment derived from

  3. Geometry + Technology = Proof

    ERIC Educational Resources Information Center

    Lyublinskaya, Irina; Funsch, Dan

    2012-01-01

    Several interactive geometry software packages are available today to secondary school teachers. An example is The Geometer's Sketchpad[R] (GSP), also known as Dynamic Geometry[R] software, developed by Key Curriculum Press. This numeric based technology has been widely adopted in the last twenty years, and a vast amount of creativity has been…

  4. Euclidean Geometry via Programming.

    ERIC Educational Resources Information Center

    Filimonov, Rossen; Kreith, Kurt

    1992-01-01

    Describes the Plane Geometry System computer software developed at the Educational Computer Systems laboratory in Sofia, Bulgaria. The system enables students to use the concept of "algorithm" to correspond to the process of "deductive proof" in the development of plane geometry. Provides an example of the software's capability and compares it to…

  5. Geometry of membrane fission.

    PubMed

    Frolov, Vadim A; Escalada, Artur; Akimov, Sergey A; Shnyrova, Anna V

    2015-01-01

    Cellular membranes define the functional geometry of intracellular space. Formation of new membrane compartments and maintenance of complex organelles require division and disconnection of cellular membranes, a process termed membrane fission. Peripheral membrane proteins generally control membrane remodeling during fission. Local membrane stresses, reflecting molecular geometry of membrane-interacting parts of these proteins, sum up to produce the key membrane geometries of fission: the saddle-shaped neck and hour-glass hemifission intermediate. Here, we review the fundamental principles behind the translation of molecular geometry into membrane shape and topology during fission. We emphasize the central role the membrane insertion of specialized protein domains plays in orchestrating fission in vitro and in cells. We further compare individual to synergistic action of the membrane insertion during fission mediated by individual protein species, proteins complexes or membrane domains. Finally, we describe how local geometry of fission intermediates defines the functional design of the protein complexes catalyzing fission of cellular membranes. PMID:25062896

  6. Ternary drop collisions

    NASA Astrophysics Data System (ADS)

    Hinterbichler, Hannes; Planchette, Carole; Brenn, Günter

    2015-10-01

    It has been recently proposed to use drop collisions for producing advanced particles or well-defined capsules, or to perform chemical reactions where the merged drops constitute a micro-reactor. For all these promising applications, it is essential to determine whether the merged drops remain stable after the collision, forming a single entity, or if they break up. This topic, widely investigated for binary drop collisions of miscible and immiscible liquid, is quite unexplored for ternary drop collisions. The current study aims to close this gap by experimentally investigating collisions between three equal-sized drops of the same liquid arranged centri-symmetrically. Three drop generators are simultaneously operated to obtain controlled ternary drop collisions. The collision outcomes are observed via photographs and compared to those of binary collisions. Similar to binary collisions, a regime map is built, showing coalescence and bouncing as well as reflexive and stretching separation. Significant differences are observed in the transitions between these regimes.

  7. Fluctuating shells under pressure

    PubMed Central

    Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.

    2012-01-01

    Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules. PMID:23150558

  8. Chiral Magnetic Effect in Heavy Ion Collisions

    DOE PAGESBeta

    Liao, Jinfeng

    2016-12-01

    The Chiral Magnetic Effect (CME) is a remarkable phenomenon that stems from highly nontrivial interplay of QCD chiral symmetry, axial anomaly, and gluonic topology. We show it is of fundamental importance to search for the CME in experiments. The heavy ion collisions provide a unique environment where a hot chiral-symmetric quark-gluon plasma is created, gluonic topological fluctuations generate chirality imbalance, and very strong magnetic fields |Β→|~m2π are present during the early stage of such collisions. Significant efforts have been made to look for CME signals in heavy ion collision experiments. Lastly, in this contribution we give a brief overview onmore » the status of such efforts.« less

  9. Intermittency in {sup 32}S + S and {sup 32}S + Au collisions at the CERN SPS

    SciTech Connect

    Bloomer, M.A.; Jacobs, P.; WA80 Collaboration

    1991-12-01

    Nonstatistical or ``intermittent`` fluctuations of charged particle multiplicities have been investigated at the CERN SPS with the WA80 multiplicity array for {sup 32}S+S and {sup 32}S+Au collisions of varying centrality. Within the phase space domain studied there is no evidence for intermittency in these collisions beyond that accounted for by FRITIOF filtered through a full detector simulation.

  10. Intermittency in sup 32 S + S and sup 32 S + Au collisions at the CERN SPS

    SciTech Connect

    Bloomer, M.A.; Jacobs, P.

    1991-12-01

    Nonstatistical or intermittent'' fluctuations of charged particle multiplicities have been investigated at the CERN SPS with the WA80 multiplicity array for {sup 32}S+S and {sup 32}S+Au collisions of varying centrality. Within the phase space domain studied there is no evidence for intermittency in these collisions beyond that accounted for by FRITIOF filtered through a full detector simulation.

  11. Power law in a microcanonical ensemble with scaling volume fluctuations

    SciTech Connect

    Begun, V. V.; Gazdzicki, M.; Gorenstein, M. I.

    2008-08-15

    Volume fluctuations are introduced in a statistical modeling of relativistic particle collisions. The microcanonical ensemble is used, and the volume fluctuations are assumed to have specific scaling properties. This leads to the KNO scaling of the particle multiplicity distributions as measured in p+p interactions. A striking prediction of the model is a power law form of the single particle momentum spectrum at high momenta. Moreover, the mean multiplicity of heavy particles also decreases as a function of the particle mass according to a power law. Finally, it is shown that the dependence of the momentum spectrum on the particle mass and momentum reduces to the dependence on the particle energy. These results resemble the properties of particle production in collisions of high energy particles.

  12. FLUCTUATION AND LOW TRANSVERSE MOMENTUM CORRELATION RESULTS FROM PHENIX.

    SciTech Connect

    MITCHELL,J.T.

    2006-07-03

    The PHENIX Experiment at the Relativistic Heavy Ion Collider has conducted a survey of fluctuations in charged hadron multiplicity in Au+Au and Cu+Cu collisions at {radical}s{sub NN} = 22, 62, and 200 GeV. A universal power law scaling for multiplicity fluctuations expressed as {sigma}{sup 2}/{mu}{sup 2} is observed as a function of N{sub part} for all species studied that is independent of the transverse momentum range of the measurement. PHENIX has also measured transverse momentum correlation amplitudes in p+p, d+Au, and Au+Au collisions. At low transverse momentum, significant differences in the correlations between the baseline p+p and d+Au data and the Au+Au data are presented.

  13. Fluctuating Asymmetry and Intelligence

    ERIC Educational Resources Information Center

    Bates, Timothy C.

    2007-01-01

    The general factor of mental ability ("g") may reflect general biological fitness. If so, "g"-loaded measures such as Raven's progressive matrices should be related to morphological measures of fitness such as fluctuating asymmetry (FA: left-right asymmetry of a set of typically left-right symmetrical body traits such as finger lengths). This…

  14. GRADFLEX: Fluctuations in Microgravity

    NASA Technical Reports Server (NTRS)

    Vailati, A.; Cerbino, R.; Mazzoni, S.; Giglio, M.; Nikolaenko, G.; Cannell, D. S.; Meyer, W. V.; Smart, A. E.

    2004-01-01

    We present the results of experimental investigations of gradient driven fluctuations induced in a liquid mixture with a concentration gradient and in a single-component fluid with a temperature gradient. We also describe the experimental apparatus being developed to carry out similar measurement under microgravity conditions.

  15. Noncommutative Geometry and Physics

    SciTech Connect

    Connes, Alain

    2006-11-03

    In this very short essay we shall describe a 'spectral' point of view on geometry which allows to start taking into account the lessons from both renormalization and of general relativity. We shall first do that for renormalization and explain in rough outline the content of our recent collaborations with Dirk Kreimer and Matilde Marcolli leading to the universal Galois symmetry of renormalizable quantum field theories provided by the renormalization group in its cosmic Galois group incarnation. As far as general relativity is concerned, since the functional integral cannot be treated in the traditional perturbative manner, it relies heavily as a 'sum over geometries' on the chosen paradigm of geometric space. This will give us the occasion to discuss, in the light of noncommutative geometry, the issue of 'observables' in gravity and our joint work with Ali Chamseddine on the spectral action, with a first attempt to write down a functional integral on the space of noncommutative geometries.

  16. What Is Geometry?

    ERIC Educational Resources Information Center

    Chern, Shiing-Shen

    1990-01-01

    Discussed are the major historical developments of geometry. Euclid, Descartes, Klein's Erlanger Program, Gaus and Riemann, globalization, topology, Elie Cartan, and an application to molecular biology are included as topics. (KR)

  17. Proof in Transformation Geometry

    ERIC Educational Resources Information Center

    Bell, A. W.

    1971-01-01

    The first of three articles showing how inductively-obtained results in transformation geometry may be organized into a deductive system. This article discusses two approaches to enlargement (dilatation), one using coordinates and the other using synthetic methods. (MM)

  18. Gingerbread-House Geometry.

    ERIC Educational Resources Information Center

    Emenaker, Charles E.

    1999-01-01

    Describes a sixth-grade interdisciplinary geometry unit based on Charles Dickens's "A Christmas Carol". Focuses on finding area, volume, and perimeter, and working with estimation, decimals, and fractions in the context of making gingerbread houses. (ASK)

  19. Measurement of flow harmonics with multi-particle cumulants in Pb+Pb collisions at √sNN = 2.76  TeV with the ATLAS detector

    DOE PAGESBeta

    Aad, G.

    2014-11-26

    ATLAS measurements of the azimuthal anisotropy in lead–lead collisions at √sNN = 2.76 TeV are shown using a dataset of approximately 7 μb–1 collected at the LHC in 2010. The measurements are performed for charged particles with transverse momenta 0.5 < pT < 20 GeV and in the pseudorapidity range |η| < 2.5. The anisotropy is characterized by the Fourier coefficients, vn, of the charged-particle azimuthal angle distribution for n = 2–4. The Fourier coefficients are evaluated using multi-particle cumulants calculated with the generating function method. Results on the transverse momentum, pseudorapidity and centrality dependence of the vn coefficients aremore » presented. The elliptic flow, v2, is obtained from the two-, four-, six- and eight-particle cumulants while higher-order coefficients, v3 and v4, are determined with two- and four-particle cumulants. Flow harmonics vn measured with four-particle cumulants are significantly reduced compared to the measurement involving two-particle cumulants. A comparison to vn measurements obtained using different analysis methods and previously reported by the LHC experiments is also shown. Results of measurements of flow fluctuations evaluated with multi-particle cumulants are shown as a function of transverse momentum and the collision centrality. As a result, models of the initial spatial geometry and its fluctuations fail to describe the flow fluctuations measurements.« less

  20. Induced geometry from disformal transformation

    NASA Astrophysics Data System (ADS)

    Yuan, Fang-Fang; Huang, Peng

    2015-05-01

    In this note, we use the disformal transformation to induce a geometry from the manifold which is originally Riemannian. The new geometry obtained here can be considered as a generalization of Weyl integrable geometry. Based on these results, we further propose a geometry which is naturally a generalization of Weyl geometry.

  1. Terrestrial Gravity Fluctuations

    NASA Astrophysics Data System (ADS)

    Harms, Jan

    2015-12-01

    Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10‑23 Hz‑1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of

  2. Gravity waves from cosmic bubble collisions

    SciTech Connect

    Salem, Michael P.; Saraswat, Prashant; Shaghoulian, Edgar E-mail: ps88@stanford.edu

    2013-02-01

    Our local Hubble volume might be contained within a bubble that nucleated in a false vacuum with only two large spatial dimensions. We study bubble collisions in this scenario and find that they generate gravity waves, which are made possible in this context by the reduced symmetry of the global geometry. These gravity waves would produce B-mode polarization in the cosmic microwave background, which could in principle dominate over the inflationary background.

  3. Software Geometry in Simulations

    NASA Astrophysics Data System (ADS)

    Alion, Tyler; Viren, Brett; Junk, Tom

    2015-04-01

    The Long Baseline Neutrino Experiment (LBNE) involves many detectors. The experiment's near detector (ND) facility, may ultimately involve several detectors. The far detector (FD) will be significantly larger than any other Liquid Argon (LAr) detector yet constructed; many prototype detectors are being constructed and studied to motivate a plethora of proposed FD designs. Whether it be a constructed prototype or a proposed ND/FD design, every design must be simulated and analyzed. This presents a considerable challenge to LBNE software experts; each detector geometry must be described to the simulation software in an efficient way which allows for multiple authors to easily collaborate. Furthermore, different geometry versions must be tracked throughout their use. We present a framework called General Geometry Description (GGD), written and developed by LBNE software collaborators for managing software to generate geometries. Though GGD is flexible enough to be used by any experiment working with detectors, we present it's first use in generating Geometry Description Markup Language (GDML) files to interface with LArSoft, a framework of detector simulations, event reconstruction, and data analyses written for all LAr technology users at Fermilab. Brett is the other of the framework discussed here, the General Geometry Description (GGD).

  4. Common Geometry Module

    2005-01-01

    The Common Geometry Module (CGM) is a code library which provides geometry functionality used for mesh generation and other applications. This functionality includes that commonly found in solid modeling engines, like geometry creation, query and modification; CGM also includes capabilities not commonly found in solid modeling engines, like geometry decomposition tools and support for shared material interfaces. CGM is built upon the ACIS solid modeling engine, but also includes geometry capability developed beside and onmore » top of ACIS. CGM can be used as-is to provide geometry functionality for codes needing this capability. However, CGM can also be extended using derived classes in C++, allowing the geometric model to serve as the basis for other applications, for example mesh generation. CGM is supported on Sun Solaris, SGI, HP, IBM, DEC, Linux and Windows NT platforms. CGM also indudes support for loading ACIS models on parallel computers, using MPI-based communication. Future plans for CGM are to port it to different solid modeling engines, including Pro/Engineer or SolidWorks. CGM is being released into the public domain under an LGPL license; the ACIS-based engine is available to ACIS licensees on request.« less

  5. Nanoparticle coagulation in fractionally charged and charge fluctuating dusty plasmas

    SciTech Connect

    Nunomura, Shota; Kondo, Michio; Shiratani, Masaharu; Koga, Kazunori; Watanabe, Yukio

    2008-08-15

    The kinetics of nanoparticle coagulation has been studied in fractionally charged and charge fluctuating dusty plasmas. The coagulation occurs when the mutual collision frequency among nanoparticles exceeds their charging and decharging/neutralization frequency. Interestingly, the coagulation is suppressed while a fraction (several percent) of nanoparticles are negatively charged in a plasma, in which stochastic charging plays an important role. A model is developed to predict a phase diagram of the coagulation and its suppression.

  6. Local geometry of isoscalar surfaces.

    PubMed

    Dopazo, César; Martín, Jesús; Hierro, Juan

    2007-11-01

    An inert dynamically passive scalar in a constant density fluid forced by a statistically homogeneous field of turbulence has been investigated using the results of a 256(3) grid direct numerical simulation. Mixing characteristics are characterized in terms of either principal curvatures or mean and Gauss curvatures. The most probable small-scale scalar geometries are flat and tilelike isosurfaces. Preliminary correlations between flow and scalar small-scale structures associate highly curved saddle points with large-strain regions and elliptic points with vorticity-dominated zones. The concavity of the scalar profiles along the isosurface normal coordinate xn correlates well with negative mean curvatures, Gauss curvatures displaying any sign, which correspond to scalar minima, tiles, or saddle points; on the other hand, convexity along xn is associated with positive mean curvatures, Gauss curvatures ranging from negative to positive signs, featuring maxima, tiles, or saddle points; inflection points along xn correlate well with small values of the mean curvature and zero or negative values of kg, corresponding to plane isosurfaces or saddle points with curvatures of equal and opposite signs. Small values of the scalar gradient are associated with elliptic points, either concave or convex (kg>0) , for both concave and convex scalar profiles along xn. Large values of the scalar gradient (or, equivalently, scalar fluctuation dissipation rates) are generally connected with small values of the Gauss curvature (either flat or moderate-curvature tilelike local geometries), with both concave and convex scalar profiles along xn equally probable. Vortical local flow structures correlate well with small and moderate values of the scalar gradient, while strain-dominated regions are associated with large values. PMID:18233765

  7. Primordial Particles; Collisions of Inelastic Particles

    NASA Astrophysics Data System (ADS)

    Sagi, George

    2011-03-01

    Three-dimensional matter is not defined by Euclidian or Cartesian geometries. Newton's and Einstein's laws are related to the motions of elastic masses. The study of collisions of inelastic particles opens up new vistas in physics. The present article reveals how such particles create clusters composed of various numbers of particles. The Probability of each formation, duplets, triplets, etc. can be calculated. The particles are held together by a binding force, and depending upon the angles of collisions they may also rotate around their center of geometry. Because of these unique properties such inelastic particles are referred to as primordial particles, Pp. When a given density of Pp per cubic space is given, then random collisions create a field. The calculation of the properties of such primordial field is very complex and beyond the present study. However, the angles of collisions are infinite in principle, but the probabilities of various cluster sizes are quantum dependent. Consequently, field calculations will require new complex mathematical methods to be discovered yet.

  8. A space-based concept for a collision warning sensor

    NASA Technical Reports Server (NTRS)

    Talent, David L.; Vilas, Faith

    1990-01-01

    This paper describes a concept for a space-based collision warning sensor experiment, the Debris Collision Warning Sensor (DCWS) experiment, in which the sensor will rely on passive sensing of debris in optical and IR passband. The DCWS experiment will be carried out under various conditions of solar phase angle and pass geometry; debris from 1.5 m to 1 mm diam will be observable. The mission characteristics include inclination in the 55-60 deg range and an altitude of about 500 km. The results of the DCWS experiment will be used to generate collision warning scenarios for the Space Station Freedom.

  9. Probability of satellite collision

    NASA Technical Reports Server (NTRS)

    Mccarter, J. W.

    1972-01-01

    A method is presented for computing the probability of a collision between a particular artificial earth satellite and any one of the total population of earth satellites. The collision hazard incurred by the proposed modular Space Station is assessed using the technique presented. The results of a parametric study to determine what type of satellite orbits produce the greatest contribution to the total collision probability are presented. Collision probability for the Space Station is given as a function of Space Station altitude and inclination. Collision probability was also parameterized over miss distance and mission duration.

  10. Elastic Collisions and Gravity

    NASA Astrophysics Data System (ADS)

    Ball, Steven

    2009-04-01

    Elastic collisions are fascinating demonstrations of conservation principles. The mediating force must be conservative in an elastic collision. Truly elastic collisions take place only when the objects in collision do not touch, e.g. magnetic bumpers on low friction carts. This requires that we define a collision as a momentum transfer. Elastic collisions in 1-D can be solved in general and the implications are quite remarkable. For example, a heavy object moving initially towards a light object followed by an elastic collision results in a final velocity of the light object greater than either initial velocity. This is easily demonstrated with low friction carts. Gravitational elastic collisions involving a light spacecraft and an extremely massive body like a moon or planet can be approximated as 1-D collisions, such as the ``free return'' trajectory of Apollo 13 around the moon. The most fascinating gravitational collisions involve the gravitational slingshot effect used to boost spacecraft velocities. The maximum gravitational slingshot effect occurs when approaching a nearly 1-D collision, revealing that the spacecraft can be boosted to greater than twice the planet velocity, enabling the spacecraft to travel much further away from the Sun.

  11. Physics of fashion fluctuations

    NASA Astrophysics Data System (ADS)

    Donangelo, R.; Hansen, A.; Sneppen, K.; Souza, S. R.

    2000-12-01

    We consider a market where many agents trade different types of products with each other. We model development of collective modes in this market, and quantify these by fluctuations that scale with time with a Hurst exponent of about 0.7. We demonstrate that individual products in the model occasionally become globally accepted means of exchange, and simultaneously become very actively traded. Thus collective features similar to money spontaneously emerge, without any a priori reason.

  12. Extracting primordial density fluctuations

    PubMed

    Gawiser; Silk

    1998-05-29

    The combination of detections of anisotropy in cosmic microwave background radiation and observations of the large-scale distribution of galaxies probes the primordial density fluctuations of the universe on spatial scales varying by three orders of magnitude. These data are found to be inconsistent with the predictions of several popular cosmological models. Agreement between the data and the cold + hot dark matter model, however, suggests that a significant fraction of the matter in the universe may consist of massive neutrinos.

  13. Geometry and Cloaking Devices

    NASA Astrophysics Data System (ADS)

    Ochiai, T.; Nacher, J. C.

    2011-09-01

    Recently, the application of geometry and conformal mappings to artificial materials (metamaterials) has attracted the attention in various research communities. These materials, characterized by a unique man-made structure, have unusual optical properties, which materials found in nature do not exhibit. By applying the geometry and conformal mappings theory to metamaterial science, it may be possible to realize so-called "Harry Potter cloaking device". Although such a device is still in the science fiction realm, several works have shown that by using such metamaterials it may be possible to control the direction of the electromagnetic field at will. We could then make an object hidden inside of a cloaking device. Here, we will explain how to design invisibility device using differential geometry and conformal mappings.

  14. Origins of cellular geometry

    PubMed Central

    2011-01-01

    Cells are highly complex and orderly machines, with defined shapes and a startling variety of internal organizations. Complex geometry is a feature of both free-living unicellular organisms and cells inside multicellular animals. Where does the geometry of a cell come from? Many of the same questions that arise in developmental biology can also be asked of cells, but in most cases we do not know the answers. How much of cellular organization is dictated by global cell polarity cues as opposed to local interactions between cellular components? Does cellular structure persist across cell generations? What is the relationship between cell geometry and tissue organization? What ensures that intracellular structures are scaled to the overall size of the cell? Cell biology is only now beginning to come to grips with these questions. PMID:21880160

  15. Students Discovering Spherical Geometry Using Dynamic Geometry Software

    ERIC Educational Resources Information Center

    Guven, Bulent; Karatas, Ilhan

    2009-01-01

    Dynamic geometry software (DGS) such as Cabri and Geometers' Sketchpad has been regularly used worldwide for teaching and learning Euclidean geometry for a long time. The DGS with its inductive nature allows students to learn Euclidean geometry via explorations. However, with respect to non-Euclidean geometries, do we need to introduce them to…

  16. Computational synthetic geometry

    SciTech Connect

    Sturmfels, B. )

    1988-01-01

    This book deals with methods for realizing abstract geometric objects in concrete vector spaces. It considers a large class of problems from convexity and discrete geometry including constructing convex polytopes from simplicial complexes, vector geometries from incidence structures and hyperplane arrangements from oriented matroids. It appears that algorithms for these constructions exist if and only if arbitrary polynomial equations are decidable with respect to the underlying field. Besides such complexity theorems, a variety of symbolic algorithms are discussed, and the methods are applied to obtain mathematical results on convex polytopes, projective configurations and the combinatories of Grassmann varieties.

  17. Net baryon fluctuations from a crossover equation of state

    NASA Astrophysics Data System (ADS)

    Kapusta, J.; Albright, M.; Young, C.

    2016-08-01

    We have constructed an equation of state which smoothly interpolates between an excluded-volume hadron resonance gas at low energy density to a plasma of quarks and gluons at high energy density. This crossover equation of state agrees very well with lattice calculations at both zero and nonzero baryon chemical potential. We use it to compute the variance, skewness, and kurtosis of fluctuations of baryon number, and compare to measurements of proton number fluctuations in central Au-Au collisions as measured by the STAR Collaboration in a beam energy scan at the Relativistic Heavy-Ion Collider. The crossover equation of state can reproduce the data if the fluctuations are frozen out at temperatures well below than the average chemical freeze-out.

  18. Beam-energy and system-size dependence of dynamical net charge fluctuations.

    SciTech Connect

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Krueger, K.; Spinka, H. M.; Underwood, D. G.; High Energy Physics; Univ. of IIlinois; Panjab Univ.; Variable Energy Cyclotron Centre; Kent State Univ.; Particle Physic Lab.; STAR Collaboration

    2009-01-01

    We present measurements of net charge fluctuations in Au+Au collisions at {radical}s{sub NN} = 19.6, 62.4, 130, and 200 GeV, Cu+Cu collisions at {radical}s{sub NN} = 62.4 and 200 GeV, and p+p collisions at {radical}s = 200 GeV using the dynamical net charge fluctuations measure {nu}{sub +-,dyn}. We observe that the dynamical fluctuations are nonzero at all energies and exhibit a modest dependence on beam energy. A weak system size dependence is also observed. We examine the collision centrality dependence of the net charge fluctuations and find that dynamical net charge fluctuations violate 1/N{sub ch} scaling but display approximate 1/N{sub part} scaling. We also study the azimuthal and rapidity dependence of the net charge correlation strength and observe strong dependence on the azimuthal angular range and pseudorapidity widths integrated to measure the correlation.

  19. Fluctuations in Schottky barrier heights

    NASA Astrophysics Data System (ADS)

    Mahan, G. D.

    1984-02-01

    A double Schottky barrier is often formed at the grain boundary in polycrystalline semiconductors. The barrier height is shown to fluctuate in value due to the random nature of the impurity positions. The magnitude of the fluctuations is 0.1 eV, and the fluctuations cause the barrier height measured by capacitance to differ from the one measured by electrical conductivity.

  20. Wall pressure fluctuations in rectangular partial enclosures

    NASA Astrophysics Data System (ADS)

    Pagliaroli, T.; Camussi, R.

    2015-04-01

    Wall pressure fluctuations generated within rectangular partial enclosures (RPEs) have been studied experimentally for a broad range of geometrical parameters. The geometry represents a simplified version of a new generation trapped vortex combustor and consisted of a rectangular cavity connected to a neck of smaller size. Wall pressure fluctuations have been measured through wall mounted microphones providing single and multi-variate pressure statistics both in the physical space and in the Fourier domain. In order to interpret the pressure signals, aerodynamic and acoustic investigations have been carried out as well for several cavity-neck ratios. The analysis of the acoustic response of the cavity has been conducted both numerically and experimentally and a simple theoretical model has been proposed to predict the frequency of the acoustic resonances. The aerodynamic study has been carried out through PIV measurements that provided characterization in terms of the geometrical parameters of both the large-scale vortex generated within the cavity and the recirculation zone formed upstream of the neck. The use of the POD decomposition permitted us to correlate the dynamics of the recirculation with the observed pressure statistics. The aerodynamic and acoustic investigations allowed us to interpret exhaustively the wall pressure cross-statistics and to separate contributions induced by hydrodynamic and purely acoustic pressure fluctuations.

  1. Single-shot fluctuations in waveguided high-harmonic generation.

    PubMed

    Goh, S J; Tao, Y; van der Slot, P J M; Bastiaens, H J M; Herek, J; Biedron, S G; Danailov, M B; Milton, S V; Boller, K-J

    2015-09-21

    For exploring the application potential of coherent soft x-ray (SXR) and extreme ultraviolet radiation (XUV) provided by high-harmonic generation, it is important to characterize the central output parameters. Of specific importance are pulse-to-pulse (shot-to-shot) fluctuations of the high-harmonic output energy, fluctuations of the direction of the emission (pointing instabilities), and fluctuations of the beam divergence and shape that reduce the spatial coherence. We present the first single-shot measurements of waveguided high-harmonic generation in a waveguided (capillary-based) geometry. Using a capillary waveguide filled with Argon gas as the nonlinear medium, we provide the first characterization of shot-to-shot fluctuations of the pulse energy, of the divergence and of the beam pointing. We record the strength of these fluctuations vs. two basic input parameters, which are the drive laser pulse energy and the gas pressure in the capillary waveguide. In correlation measurements between single-shot drive laser beam profiles and single-shot high-harmonic beam profiles we prove the absence of drive laser beam-pointing-induced fluctuations in the high-harmonic output. We attribute the main source of high-harmonic fluctuations to ionization-induced nonlinear mode mixing during propagation of the drive laser pulse inside the capillary waveguide. PMID:26406689

  2. Advanced geometries and regimes

    SciTech Connect

    Bulanov, S. S.; Bulanov, S. V.; Turchetti, G.; Limpouch, J.; Klimo, O.; Psikal, J.; Margarone, D.; Korn, G.

    2013-07-26

    We review and discuss different schemes of laser ion acceleration as well as advanced target geometries in connection with the development of the laser-driven proton source for hadron therapy of oncological diseases, which is a part of the ELIMED project.

  3. Spacetime and Euclidean geometry

    NASA Astrophysics Data System (ADS)

    Brill, Dieter; Jacobson, Ted

    2006-04-01

    Using only the principle of relativity and Euclidean geometry we show in this pedagogical article that the square of proper time or length in a two-dimensional spacetime diagram is proportional to the Euclidean area of the corresponding causal domain. We use this relation to derive the Minkowski line element by two geometric proofs of the spacetime Pythagoras theorem.

  4. Listening to Geometry

    ERIC Educational Resources Information Center

    Cooper, Brett D.; Barger, Rita

    2009-01-01

    The many connections between music and mathematics are well known. The length of a plucked string determines its tone, the time signature of a piece of music is a ratio, and note durations are measured in fractions. One connection commonly overlooked is that between music and geometry--specifically, geometric transformations, including…

  5. Making Solid Geometry Solid.

    ERIC Educational Resources Information Center

    Hartz, Viggo

    1981-01-01

    Allowing students to use a polystyrene cutter to fashion their own three-dimensional models is suggested as a means of allowing individuals to experience problems and develop ideas related to solid geometry. A list of ideas that can lead to mathematical discovery is provided. (MP)

  6. Teaching Geometry with Tangrams.

    ERIC Educational Resources Information Center

    Russell, Dorothy S.; Bologna, Elaine M.

    1982-01-01

    Geometry is viewed as the most neglected area of the elementary school mathematics curriculum. Tangram activities provide numerous worthwhile mathematical experiences for children. A method of constructing tangrams through paper folding is followed by suggested spatial visualization, measurement, and additional activities. (MP)

  7. Sliding vane geometry turbines

    DOEpatents

    Sun, Harold Huimin; Zhang, Jizhong; Hu, Liangjun; Hanna, Dave R

    2014-12-30

    Various systems and methods are described for a variable geometry turbine. In one example, a turbine nozzle comprises a central axis and a nozzle vane. The nozzle vane includes a stationary vane and a sliding vane. The sliding vane is positioned to slide in a direction substantially tangent to an inner circumference of the turbine nozzle and in contact with the stationary vane.

  8. Gravity is Geometry.

    ERIC Educational Resources Information Center

    MacKeown, P. K.

    1984-01-01

    Clarifies two concepts of gravity--those of a fictitious force and those of how space and time may have geometry. Reviews the position of Newton's theory of gravity in the context of special relativity and considers why gravity (as distinct from electromagnetics) lends itself to Einstein's revolutionary interpretation. (JN)

  9. The Helen of Geometry

    ERIC Educational Resources Information Center

    Martin, John

    2010-01-01

    The cycloid has been called the Helen of Geometry, not only because of its beautiful properties but also because of the quarrels it provoked between famous mathematicians of the 17th century. This article surveys the history of the cycloid and its importance in the development of the calculus.

  10. Geometry and physics

    PubMed Central

    Atiyah, Michael; Dijkgraaf, Robbert; Hitchin, Nigel

    2010-01-01

    We review the remarkably fruitful interactions between mathematics and quantum physics in the past decades, pointing out some general trends and highlighting several examples, such as the counting of curves in algebraic geometry, invariants of knots and four-dimensional topology. PMID:20123740

  11. The Geometry of Viruses.

    ERIC Educational Resources Information Center

    Case, Christine L.

    1991-01-01

    Presented is an activity in which students make models of viruses, which allows them to visualize the shape of these microorganisms. Included are some background on viruses, the biology and geometry of viruses, directions for building viruses, a comparison of cells and viruses, and questions for students. (KR)

  12. GEOMETRY, TENTATIVE GUIDES.

    ERIC Educational Resources Information Center

    KLIER, KATHERINE M.

    PRESENTED IS A FUSED COURSE IN PLANE, SOLID, AND COORDINATE GEOMETRY. ELEMENTARY SET THEORY, LOGIC, AND THE PRINCIPLE OF SEPARATION PROVIDE UNIFYING THREADS THROUGHOUT THE TEXT. THE TWO CURRICULUM GUIDES HAVE BEEN PREPARED FOR USE WITH TWO DIFFERENT TEXTS. EITHER CURRICULUM GUIDE MAY BE USED DEPENDING UPON THE CHOICE OF THE TEACHER AND THE NEEDS…

  13. Fluctuations in granular media

    NASA Astrophysics Data System (ADS)

    Howell, Daniel W.; Behringer, R. P.; Veje, C. T.

    1999-09-01

    Dense slowly evolving or static granular materials exhibit strong force fluctuations even though the spatial disorder of the grains is relatively weak. Typically, forces are carried preferentially along a network of "force chains." These consist of linearly aligned grains with larger-than-average force. A growing body of work has explored the nature of these fluctuations. We first briefly review recent work concerning stress fluctuations. We then focus on a series of experiments in both two- and three-dimension [(2D) and (3D)] to characterize force fluctuations in slowly sheared systems. Both sets of experiments show strong temporal fluctuations in the local stress/force; the length scales of these fluctuations extend up to 102 grains. In 2D, we use photoelastic disks that permit visualization of the internal force structure. From this we can make comparisons to recent models and calculations that predict the distributions of forces. Typically, these models indicate that the distributions should fall off exponentially at large force. We find in the experiments that the force distributions change systematically as we change the mean packing fraction, γ. For γ's typical of dense packings of nondeformable grains, we see distributions that are consistent with an exponential decrease at large forces. For both lower and higher γ, the observed force distributions appear to differ from this prediction, with a more Gaussian distribution at larger γ and perhaps a power law at lower γ. For high γ, the distributions differ from this prediction because the grains begin to deform, allowing more grains to carry the applied force, and causing the distributions to have a local maximum at nonzero force. It is less clear why the distributions differ from the models at lower γ. An exploration in γ has led to the discovery of an interesting continuous or "critical" transition (the strengthening/softening transition) in which the mean stress is the order parameter, and the mean

  14. Geometry of PDE's. IV

    NASA Astrophysics Data System (ADS)

    Prástaro, Agostino

    2008-02-01

    Following our previous results on this subject [R.P. Agarwal, A. Prástaro, Geometry of PDE's. III(I): Webs on PDE's and integral bordism groups. The general theory, Adv. Math. Sci. Appl. 17 (2007) 239-266; R.P. Agarwal, A. Prástaro, Geometry of PDE's. III(II): Webs on PDE's and integral bordism groups. Applications to Riemannian geometry PDE's, Adv. Math. Sci. Appl. 17 (2007) 267-285; A. Prástaro, Geometry of PDE's and Mechanics, World Scientific, Singapore, 1996; A. Prástaro, Quantum and integral (co)bordism in partial differential equations, Acta Appl. Math. (5) (3) (1998) 243-302; A. Prástaro, (Co)bordism groups in PDE's, Acta Appl. Math. 59 (2) (1999) 111-201; A. Prástaro, Quantized Partial Differential Equations, World Scientific Publishing Co, Singapore, 2004, 500 pp.; A. Prástaro, Geometry of PDE's. I: Integral bordism groups in PDE's, J. Math. Anal. Appl. 319 (2006) 547-566; A. Prástaro, Geometry of PDE's. II: Variational PDE's and integral bordism groups, J. Math. Anal. Appl. 321 (2006) 930-948; A. Prástaro, Th.M. Rassias, Ulam stability in geometry of PDE's, Nonlinear Funct. Anal. Appl. 8 (2) (2003) 259-278; I. Stakgold, Boundary Value Problems of Mathematical Physics, I, The MacMillan Company, New York, 1967; I. Stakgold, Boundary Value Problems of Mathematical Physics, II, Collier-MacMillan, Canada, Ltd, Toronto, Ontario, 1968], integral bordism groups of the Navier-Stokes equation are calculated for smooth, singular and weak solutions, respectively. Then a characterization of global solutions is made on this ground. Enough conditions to assure existence of global smooth solutions are given and related to nullity of integral characteristic numbers of the boundaries. Stability of global solutions are related to some characteristic numbers of the space-like Cauchy dataE Global solutions of variational problems constrained by (NS) are classified by means of suitable integral bordism groups too.

  15. Study on Pyroelectric Harvesters with Various Geometry.

    PubMed

    Siao, An-Shen; Chao, Ching-Kong; Hsiao, Chun-Ching

    2015-01-01

    Pyroelectric harvesters convert time-dependent temperature variations into electric current. The appropriate geometry of the pyroelectric cells, coupled with the optimal period of temperature fluctuations, is key to driving the optimal load resistance, which enhances the performance of pyroelectric harvesters. The induced charge increases when the thickness of the pyroelectric cells decreases. Moreover, the induced charge is extremely reduced for the thinner pyroelectric cell when not used for the optimal period. The maximum harvested power is achieved when a 100 μm-thick PZT (Lead zirconate titanate) cell is used to drive the optimal load resistance of about 40 MΩ. Moreover, the harvested power is greatly reduced when the working resistance diverges even slightly from the optimal load resistance. The stored voltage generated from the 75 μm-thick PZT cell is less than that from the 400 μm-thick PZT cell for a period longer than 64 s. Although the thinner PZT cell is advantageous in that it enhances the efficiency of the pyroelectric harvester, the much thinner 75 μm-thick PZT cell and the divergence from the optimal period further diminish the performance of the pyroelectric cell. Therefore, the designers of pyroelectric harvesters need to consider the coupling effect between the geometry of the pyroelectric cells and the optimal period of temperature fluctuations to drive the optimal load resistance. PMID:26270666

  16. Study on Pyroelectric Harvesters with Various Geometry

    PubMed Central

    Siao, An-Shen; Chao, Ching-Kong; Hsiao, Chun-Ching

    2015-01-01

    Pyroelectric harvesters convert time-dependent temperature variations into electric current. The appropriate geometry of the pyroelectric cells, coupled with the optimal period of temperature fluctuations, is key to driving the optimal load resistance, which enhances the performance of pyroelectric harvesters. The induced charge increases when the thickness of the pyroelectric cells decreases. Moreover, the induced charge is extremely reduced for the thinner pyroelectric cell when not used for the optimal period. The maximum harvested power is achieved when a 100 μm-thick PZT (Lead zirconate titanate) cell is used to drive the optimal load resistance of about 40 MΩ. Moreover, the harvested power is greatly reduced when the working resistance diverges even slightly from the optimal load resistance. The stored voltage generated from the 75 μm-thick PZT cell is less than that from the 400 μm-thick PZT cell for a period longer than 64 s. Although the thinner PZT cell is advantageous in that it enhances the efficiency of the pyroelectric harvester, the much thinner 75 μm-thick PZT cell and the divergence from the optimal period further diminish the performance of the pyroelectric cell. Therefore, the designers of pyroelectric harvesters need to consider the coupling effect between the geometry of the pyroelectric cells and the optimal period of temperature fluctuations to drive the optimal load resistance. PMID:26270666

  17. An introduction to Minkowski geometries

    NASA Astrophysics Data System (ADS)

    Farnsworth, David L.

    2016-07-01

    The fundamental ideas of Minkowski geometries are presented. Learning about Minkowski geometries can sharpen our students' understanding of concepts such as distance measurement. Many of its ideas are important and accessible to undergraduate students. Following a brief overview, distance and orthogonality in Minkowski geometries are thoroughly discussed and many illustrative examples and applications are supplied. Suggestions for further study of these geometries are given. Indeed, Minkowski geometries are an excellent source of topics for undergraduate research and independent study.

  18. Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at √{sNN}=2.76 TeV

    NASA Astrophysics Data System (ADS)

    Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Almaraz, J. R. M.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baltasar Dos Santos Pedrosa, F.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Chunhui, Z.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. 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G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gulkanyan, H.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hansen, A.; Harris, J. W.; Hartmann, H.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hilden, T. E.; Hillemanns, H.; Hippolyte, B.; Hosokawa, R.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Ilkiv, I.; Inaba, M.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacobs, P. M.; Jadlovska, S.; Jahnke, C.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Khan, K. H.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, B.; Kim, D. W.; Kim, D. J.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobayashi, T.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Kral, J.; Králik, I.; Kravčáková, A.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kugathasan, T.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Legrand, I.; Lehas, F.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Luz, P. H. F. N. D.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Martynov, Y.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Masui, H.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; McDonald, D.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Morando, M.; Moreira de Godoy, D. A.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Murray, S.; Musa, L.; Musinsky, J.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pajares, C.; Pal, S. K.; Pan, J.; Pandey, A. K.; Pant, D.; Papcun, P.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Peitzmann, T.; Pereira da Costa, H.; Pereira de Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Real, J. S.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Rettig, F.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rivetti, A.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salgado, C. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sanchez Castro, X.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Seo, J.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Soltz, R.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Srivastava, B. K.; Stachel, J.; Stan, I.; Stefanek, G.; Steinpreis, M.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Sultanov, R.; Šumbera, M.; Symons, T. J. M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tangaro, M. A.; Tapia Takaki, J. D.; Tarantola Peloni, A.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Wang, Y.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yang, H.; Yang, P.; Yano, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.; Alice Collaboration

    2016-03-01

    We report on results obtained with the event-shape engineering technique applied to Pb-Pb collisions at √{sNN}=2.76 TeV. By selecting events in the same centrality interval, but with very different average flow, different initial-state conditions can be studied. We find the effect of the event-shape selection on the elliptic flow coefficient v2 to be almost independent of transverse momentum pT, which is as expected if this effect is attributable to fluctuations in the initial geometry of the system. Charged-hadron, -pion, -kaon, and -proton transverse momentum distributions are found to be harder in events with higher-than-average elliptic flow, indicating an interplay between radial and elliptic flow.

  19. Fluctuating nematic elastomer membranes.

    PubMed

    Xing, Xiangjun; Mukhopadhyay, Ranjan; Lubensky, T C; Radzihovsky, Leo

    2003-08-01

    We study the flat phase of nematic elastomer membranes with rotational symmetry spontaneously broken by an in-plane nematic order. Such a state is characterized by a vanishing elastic modulus for simple shear and soft transverse phonons. At harmonic level, the in-plane orientational (nematic) order is stable to thermal fluctuations that lead to short-range in-plane translational (phonon) correlations. To treat thermal fluctuations and relevant elastic nonlinearities, we introduce two generalizations of two-dimensional membranes in a three-dimensional space to arbitrary D-dimensional membranes embedded in a d-dimensional space and analyze their anomalous elasticities in an expansion about D=4. We find a stable fixed point that controls long-scale properties of nematic elastomer membranes. It is characterized by singular in-plane elastic moduli that vanish as a power law eta(lambda)=4-D of a relevant inverse length scale (e.g., wave vector) and a finite bending rigidity. Our predictions are asymptotically exact near four dimensions. PMID:14524954

  20. Fluctuating nematic elastomer membranes

    NASA Astrophysics Data System (ADS)

    Xing, Xiangjun; Mukhopadhyay, Ranjan; Lubensky, T. C.; Radzihovsky, Leo

    2003-08-01

    We study the flat phase of nematic elastomer membranes with rotational symmetry spontaneously broken by an in-plane nematic order. Such a state is characterized by a vanishing elastic modulus for simple shear and soft transverse phonons. At harmonic level, the in-plane orientational (nematic) order is stable to thermal fluctuations that lead to short-range in-plane translational (phonon) correlations. To treat thermal fluctuations and relevant elastic nonlinearities, we introduce two generalizations of two-dimensional membranes in a three-dimensional space to arbitrary D-dimensional membranes embedded in a d-dimensional space and analyze their anomalous elasticities in an expansion about D=4. We find a stable fixed point that controls long-scale properties of nematic elastomer membranes. It is characterized by singular in-plane elastic moduli that vanish as a power law ηλ=4-D of a relevant inverse length scale (e.g., wave vector) and a finite bending rigidity. Our predictions are asymptotically exact near four dimensions.

  1. Fitness in fluctuating environments

    NASA Astrophysics Data System (ADS)

    Tanase Nicola, Sorin; Nemenman, Ilya

    2011-03-01

    Often environments change faster than the time needed to evolve optimal phenotypes through cycles of mutation and selection. We focus on this case, but assume that environmental oscillations are slower than an individual's lifetime. This is relevant, for example, for bacterial populations confronted with daily environmental changes. We analyze a resource-limited competition between a mutant phenotype and the ancestor. Environmental dynamics is represented by periodically varying, off-phase parameters of the corresponding Lotka-Volterra model. For the very slow dynamics (but still faster than the fixation time scale) the strength and the sign of selection are functions of the birth/death rates averaged over all of the environmental states and independent of the period of the fluctuations. For faster fluctuations, selection depends on the particular sequence of the successive environmental states. In particular, a time reversal of the environmental dynamics can change the sign of the selection. We conclude that the fittest phenotype in a changing environment can be very different from both the optimal phenotype in the average environment, and the phenotype with the largest average fitness.

  2. Disequilibration by Planetary Collision

    NASA Astrophysics Data System (ADS)

    Asphaug, E. I.; Jutzi, M.

    2010-12-01

    Molten planets equilibrate gravitationally, chemically, and thermally. Large scale collisions (a.k.a. giant impacts, similar-sized collisions) can upset the apple cart by bringing core material, late in the game, into mixture with mantle products, and by shredding stratified planets into strands of mantle and clumps of core (c.g. Asphaug et al. Nature 2006). Atmophiles and volatiles come along for the ride, and can find themselves in disequilibrium mixtures not anticipated by one-dimensional models of planetary evolution, or by planet growth models in which planets stick, merge, and mix perfectly in the aftermath of a collision. We present very high resolution case studies of such collisions.

  3. Azimuthal Anisotropy in U +U and Au +Au Collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandin, A. V.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, H. Z.; Huang, B.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, W.; Li, Y.; Li, C.; Li, Z. M.; Li, X.; Li, X.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, L.; Ma, R.; Ma, Y. G.; Ma, G. L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Meehan, K.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D. L.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Peterson, A.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B. J.; Sun, X.; Sun, X. M.; Sun, Z.; Sun, Y.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A. N.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbaek, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, Y.; Wang, H.; Wang, J. S.; Wang, Y.; Wang, G.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, Y. F.; Xu, N.; Xu, Z.; Xu, Q. H.; Xu, H.; Yang, Y.; Yang, Y.; Yang, C.; Yang, S.; Yang, Q.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, J. B.; Zhang, J.; Zhang, Z.; Zhang, S.; Zhang, Y.; Zhang, J. L.; Zhao, F.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2015-11-01

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2 } and v2{4 }, for charged hadrons from U +U collisions at √{sNN }=193 GeV and Au +Au collisions at √{sNN}=200 GeV . Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2 } on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U +U collisions. We also show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

  4. Turbulent magnetic fluctuations in laboratory reconnection

    NASA Astrophysics Data System (ADS)

    Von Stechow, Adrian; Grulke, Olaf; Klinger, Thomas

    2016-07-01

    The role of fluctuations and turbulence is an important question in astrophysics. While direct observations in space are rare and difficult dedicated laboratory experiments provide a versatile environment for the investigation of magnetic reconnection due to their good diagnostic access and wide range of accessible plasma parameters. As such, they also provide an ideal chance for the validation of space plasma reconnection theories and numerical simulation results. In particular, we studied magnetic fluctuations within reconnecting current sheets for various reconnection parameters such as the reconnection rate, guide field, as well as plasma density and temperature. These fluctuations have been previously interpreted as signatures of current sheet plasma instabilities in space and laboratory systems. Especially in low collisionality plasmas these may provide a source of anomalous resistivity and thereby contribute a significant fraction of the reconnection rate. We present fluctuation measurements from two complementary reconnection experiments and compare them to numerical simulation results. VINETA.II (Greifswald, Germany) is a cylindrical, high guide field reconnection experiment with an open field line geometry. The reconnecting current sheet has a three-dimensional structure that is predominantly set by the magnetic pitch angle which results from the superposition of the guide field and the in-plane reconnecting field. Within this current sheet, high frequency magnetic fluctuations are observed that correlate well with the local current density and show a power law spectrum with a spectral break at the lower hybrid frequency. Their correlation lengths are found to be extremely short, but propagation is nonetheless observed with high phase velocities that match the Whistler dispersion. To date, the experiment has been run with an external driving field at frequencies higher than the ion cyclotron frequency f_{ci}, which implies that the EMHD framework applies

  5. Geometry definition with MAZE

    SciTech Connect

    Nebeck, H.E.

    1986-08-01

    The MAZE mesh generator represents an arbitrary two dimensional region of space as an ordered collection of quadrilateral elements. Each element is defined by its four corner points (nodes) and an integer material number. Models are created by subdividing the region(s) of interest into one or more PARTS and specifying the element distribution in each part. Then, parts can be merged together to form the meshed representation of the entire region. Applying boundary conditions and describing material properties completes the model construction process. This activity takes place in three distinct phases: phase I-define geometry, subdivide regions into elements; phase II-refine geometry, establish interface and boundary conditions; phase III-describe material properties. This work presents explanations and examples of the phase I commands, along with an overview of the MAZE mesh generation process.

  6. Cylindrical geometry hall thruster

    DOEpatents

    Raitses, Yevgeny; Fisch, Nathaniel J.

    2002-01-01

    An apparatus and method for thrusting plasma, utilizing a Hall thruster with a cylindrical geometry, wherein ions are accelerated in substantially the axial direction. The apparatus is suitable for operation at low power. It employs small size thruster components, including a ceramic channel, with the center pole piece of the conventional annular design thruster eliminated or greatly reduced. Efficient operation is accomplished through magnetic fields with a substantial radial component. The propellant gas is ionized at an optimal location in the thruster. A further improvement is accomplished by segmented electrodes, which produce localized voltage drops within the thruster at optimally prescribed locations. The apparatus differs from a conventional Hall thruster, which has an annular geometry, not well suited to scaling to small size, because the small size for an annular design has a great deal of surface area relative to the volume.

  7. Fluctuation effects in grain growth

    NASA Astrophysics Data System (ADS)

    Kim, Seong Gyoon; Park, Yong Bum

    2016-08-01

    In this study, we attempted to clarify the roles of fluctuation effects in grain growth. To capture the persistent nature in both space and time of fluctuations due to variations in the local surroundings of individual grains, we developed a local mean-field model. The fluctuation strength in this model is arbitrarily controlled by employing an artificial number, n , of nearest neighbor grains. Large-scale numerical computations of the model for various n values and initial GSDs were carried out to follow transient behaviors and determine the steady states. This study reveals that, in the classical mean-field model with no fluctuation effects, the steady state is not unique but is strongly dependent upon the initial GSD. However, a small fluctuation drives the mean-field model to reach the Hillert solution, independent of the fluctuation strength and initial GSD, as long as the fluctuation strength is sufficiently small. On the other hand, when the fluctuation is sufficiently strong, the fluctuation pushes the steady state of the mean-field model out of the Hillert solution, and its strength determines a unique steady state independent of the initial GSD. The strong fluctuation makes the GSD more symmetric than the Hillert distribution. Computations designed to mimic actual 2 and 3D grain growth were carried out by taking the number of nearest neighbors of each grain as a function of the scaled grain size. The resultant GSDs in two and three dimensions were compared with the direct simulations of ideal grain growth.

  8. Particle-Number Fluctuations and Correlations in Transfer Reactions Obtained Using the Balian-Veneroni Variational Principle

    SciTech Connect

    Simenel, Cedric

    2011-03-18

    The Balian-Veneroni (BV) variational principle, which optimizes the evolution of the state according to the relevant observable, is used at the mean-field level to determine the particle-number fluctuations in fragments of many-body systems. For fermions, the numerical evaluation of such fluctuations requires the use of a time-dependent Hartree-Fock (TDHF) code. Proton, neutron, and total nucleon number fluctuations in fragments produced in collisions of two {sup 40}Ca are computed well above the fusion barrier. For deep-inelastic collisions, the fluctuations calculated from the BV variational principle are much larger than standard TDHF results, and closer to experimental fluctuations. Correlations between proton and neutron numbers are determined. These correlations are shown to be larger with exotic systems where charge equilibration occurs.

  9. Inflation from quantum geometry.

    PubMed

    Bojowald, Martin

    2002-12-23

    Quantum geometry predicts that a universe evolves through an inflationary phase at small volume before exiting gracefully into a standard Friedmann phase. This does not require the introduction of additional matter fields with ad hoc potentials; rather, it occurs because of a quantum gravity modification of the kinetic part of ordinary matter Hamiltonians. An application of the same mechanism can explain why the present day cosmological acceleration is so tiny.

  10. Geometry of Quantum States

    NASA Astrophysics Data System (ADS)

    Bengtsson, Ingemar; Zyczkowski, Karol

    2007-12-01

    Preface; 1. Convexity, colours and statistics; 2. Geometry of probability distributions; 3. Much ado about spheres; 4. Complex projective spaces; 5. Outline of quantum mechanics; 6. Coherent states and group actions; 7. The stellar representation; 8. The space of density matrices; 9. Purification of mixed quantum states; 10. Quantum operations; 11. Duality: maps versus states; 12. Density matrices and entropies; 13. Distinguishability measures; 14. Monotone metrics and measures; 15. Quantum entanglement; Epilogue; Appendices; References; Index.

  11. Freezing in confined geometries

    NASA Technical Reports Server (NTRS)

    Sokol, P. E.; Ma, W. J.; Herwig, K. W.; Snow, W. M.; Wang, Y.; Koplik, Joel; Banavar, Jayanth R.

    1992-01-01

    Results of detailed structural studies, using elastic neutron scattering, of the freezing of liquid O2 and D2 in porous vycor glass, are presented. The experimental studies have been complemented by computer simulations of the dynamics of freezing of a Lennard-Jones liquid in narrow channels bounded by molecular walls. Results point to a new simple physical interpretation of freezing in confined geometries.

  12. Integral geometry and holography

    SciTech Connect

    Czech, Bartlomiej; Lamprou, Lampros; McCandlish, Samuel; Sully, James

    2015-10-27

    We present a mathematical framework which underlies the connection between information theory and the bulk spacetime in the AdS3/CFT2 correspondence. A key concept is kinematic space: an auxiliary Lorentzian geometry whose metric is defined in terms of conditional mutual informations and which organizes the entanglement pattern of a CFT state. When the field theory has a holographic dual obeying the Ryu-Takayanagi proposal, kinematic space has a direct geometric meaning: it is the space of bulk geodesics studied in integral geometry. Lengths of bulk curves are computed by kinematic volumes, giving a precise entropic interpretation of the length of any bulk curve. We explain how basic geometric concepts -- points, distances and angles -- are reflected in kinematic space, allowing one to reconstruct a large class of spatial bulk geometries from boundary entanglement entropies. In this way, kinematic space translates between information theoretic and geometric descriptions of a CFT state. As an example, we discuss in detail the static slice of AdS3 whose kinematic space is two-dimensional de Sitter space.

  13. Integral geometry and holography

    DOE PAGESBeta

    Czech, Bartlomiej; Lamprou, Lampros; McCandlish, Samuel; Sully, James

    2015-10-27

    We present a mathematical framework which underlies the connection between information theory and the bulk spacetime in the AdS3/CFT2 correspondence. A key concept is kinematic space: an auxiliary Lorentzian geometry whose metric is defined in terms of conditional mutual informations and which organizes the entanglement pattern of a CFT state. When the field theory has a holographic dual obeying the Ryu-Takayanagi proposal, kinematic space has a direct geometric meaning: it is the space of bulk geodesics studied in integral geometry. Lengths of bulk curves are computed by kinematic volumes, giving a precise entropic interpretation of the length of any bulkmore » curve. We explain how basic geometric concepts -- points, distances and angles -- are reflected in kinematic space, allowing one to reconstruct a large class of spatial bulk geometries from boundary entanglement entropies. In this way, kinematic space translates between information theoretic and geometric descriptions of a CFT state. As an example, we discuss in detail the static slice of AdS3 whose kinematic space is two-dimensional de Sitter space.« less

  14. Emergent Complex Network Geometry

    NASA Astrophysics Data System (ADS)

    Wu, Zhihao; Menichetti, Giulia; Rahmede, Christoph; Bianconi, Ginestra

    2015-05-01

    Networks are mathematical structures that are universally used to describe a large variety of complex systems such as the brain or the Internet. Characterizing the geometrical properties of these networks has become increasingly relevant for routing problems, inference and data mining. In real growing networks, topological, structural and geometrical properties emerge spontaneously from their dynamical rules. Nevertheless we still miss a model in which networks develop an emergent complex geometry. Here we show that a single two parameter network model, the growing geometrical network, can generate complex network geometries with non-trivial distribution of curvatures, combining exponential growth and small-world properties with finite spectral dimensionality. In one limit, the non-equilibrium dynamical rules of these networks can generate scale-free networks with clustering and communities, in another limit planar random geometries with non-trivial modularity. Finally we find that these properties of the geometrical growing networks are present in a large set of real networks describing biological, social and technological systems.

  15. Worldline numerics for energy-momentum tensors in Casimir geometries

    NASA Astrophysics Data System (ADS)

    Schäfer, Marco; Huet, Idrish; Gies, Holger

    2016-04-01

    We develop the worldline formalism for computations of composite operators such as the fluctuation induced energy-momentum tensor. As an example, we use a fluctuating real scalar field subject to Dirichlet boundary conditions. The resulting worldline representation can be evaluated by worldline Monte-Carlo methods in continuous spacetime. We benchmark this worldline numerical algorithm with the aid of analytically accessible single-plate and parallel-plate Casimir configurations, providing a detailed analysis of statistical and systematic errors. The method generalizes straightforwardly to arbitrary Casimir geometries and general background potentials.

  16. Time evolution of temperature fluctuation in a non-equilibrated system

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Trambak; Garg, Prakhar; Sahoo, Raghunath; Samantray, Prasant

    2016-09-01

    The evolution equation for inhomogeneous and anisotropic temperature fluctuation inside a medium is derived within the ambit of Boltzmann Transport Equation (BTE) for a hot gas of massless particles. Also, specializing to a situation created after a heavy-ion collision (HIC), we analyze the Fourier space variation of temperature fluctuation of the medium using its temperature profile. The effect of viscosity on the variation of fluctuations in the latter case is investigated and possible implications for early universe cosmology, and its connection with HICs are also explored.

  17. Fluctuating multicomponent lattice Boltzmann model

    NASA Astrophysics Data System (ADS)

    Belardinelli, D.; Sbragaglia, M.; Biferale, L.; Gross, M.; Varnik, F.

    2015-02-01

    Current implementations of fluctuating lattice Boltzmann equations (FLBEs) describe single component fluids. In this paper, a model based on the continuum kinetic Boltzmann equation for describing multicomponent fluids is extended to incorporate the effects of thermal fluctuations. The thus obtained fluctuating Boltzmann equation is first linearized to apply the theory of linear fluctuations, and expressions for the noise covariances are determined by invoking the fluctuation-dissipation theorem directly at the kinetic level. Crucial for our analysis is the projection of the Boltzmann equation onto the orthonormal Hermite basis. By integrating in space and time the fluctuating Boltzmann equation with a discrete number of velocities, the FLBE is obtained for both ideal and nonideal multicomponent fluids. Numerical simulations are specialized to the case where mean-field interactions are introduced on the lattice, indicating a proper thermalization of the system.

  18. Fluctuating Thermodynamics for Biological Processes

    NASA Astrophysics Data System (ADS)

    Ham, Sihyun

    Because biomolecular processes are largely under thermodynamic control, dynamic extension of thermodynamics is necessary to uncover the mechanisms and driving factors of fluctuating processes. The fluctuating thermodynamics technology presented in this talk offers a practical means for the thermodynamic characterization of conformational dynamics in biomolecules. The use of fluctuating thermodynamics has the potential to provide a comprehensive picture of fluctuating phenomena in diverse biological processes. Through the application of fluctuating thermodynamics, we provide a thermodynamic perspective on the misfolding and aggregation of the various proteins associated with human diseases. In this talk, I will present the detailed concepts and applications of the fluctuating thermodynamics technology for elucidating biological processes. This work was supported by Samsung Science and Technology Foundation under Project Number SSTF-BA1401-13.

  19. Ball Collision Experiments

    ERIC Educational Resources Information Center

    Cross, R.

    2015-01-01

    Experiments are described on collisions between two billiard balls and between a bat and a ball. The experiments are designed to extend a student's understanding of collision events and could be used either as a classroom demonstration or for a student project.

  20. Elastic and Inelastic Collisions

    ERIC Educational Resources Information Center

    Gluck, Paul

    2010-01-01

    There have been two articles in this journal that described a pair of collision carts used to demonstrate vividly the difference between elastic and inelastic collisions. One cart had a series of washers that were mounted rigidly on a rigid wooden framework, the other had washers mounted on rubber bands stretched across a framework. The rigidly…

  1. Bubble collision with gravitation

    SciTech Connect

    Hwang, Dong-il; Lee, Bum-Hoon; Lee, Wonwoo; Yeom, Dong-han E-mail: bhl@sogang.ac.kr E-mail: innocent.yeom@gmail.com

    2012-07-01

    In this paper, we study vacuum bubble collisions with various potentials including gravitation, assuming spherical, planar, and hyperbolic symmetry. We use numerical calculations from double-null formalism. Spherical symmetry can mimic the formation of a black hole via multiple bubble collisions. Planar and especially hyperbolic symmetry describes two bubble collisions. We study both cases, when two true vacuum regions have the same field value or different field values, by varying tensions. For the latter case, we also test symmetric and asymmetric bubble collisions, and see details of causal structures. If the colliding energy is sufficient, then the vacuum can be destabilized, and it is also demonstrated. This double-null formalism can be a complementary approach in the context of bubble collisions.

  2. Collision risk assessment

    NASA Astrophysics Data System (ADS)

    Sánchez Ortiz, N.; Belló Mora, M.; Graziano, M.; Pina Caballero, F.; Sánchez Pérez, J. M.; Klinkrad, H.

    2001-10-01

    Avoidance of near misses or collisions is required for almost all satellites on orbit, but it is of particular interest for manned missions and spacecraft at densely populated regions. In order to avoid these possible collisions, it is needed to determine a possible conjunction and its associated uncertainty. Two main constraints must be taken into account when a tool to forecast the collision risk of an object is being developed: the high number of objects in space and the accuracy of the catalogued object data. The number of objects on Earth orbit makes impossible to propagate all the catalogued objects, thus filtering and parallel processing techniques are presented. The accuracy of the catalogued object data and the propagation of the error over the time identify a position ellipsoid of error, whose behaviour has an important influence on some parameters on the filtering techniques and the way the collision probability is computed. Some collision probability methods are presented.

  3. Future foam: Nontrivial topology from bubble collisions in eternal inflation

    SciTech Connect

    Bousso, Raphael; Freivogel, Ben; Yang, I-S.; Sekino, Yasuhiro; Shenker, Stephen; Susskind, Leonard; Yeh, C.-P.

    2008-09-15

    We study pocket universes which have zero cosmological constant and nontrivial boundary topology. These arise from bubble collisions in eternal inflation. Using a simplified dust model of collisions we find that boundaries of any genus can occur. Using a radiation shell model we perform analytic studies in the thin-wall limit to show the existence of geometries with a single toroidal boundary. We give plausibility arguments that higher genus boundaries can also occur. In geometries with one boundary of any genus a timelike observer can see the entire boundary. Geometries with multiple disconnected boundaries can also occur. In the spherical case with two boundaries the boundaries are separated by a horizon. Our results suggest that the holographic dual description for eternal inflation, proposed by Freivogel, Sekino, Susskind and Yeh, should include summation over the genus of the base space of the dual conformal field theory. We point out peculiarities of this genus expansion compared to the string perturbation series.

  4. Geometry for the Secondary School

    ERIC Educational Resources Information Center

    Moalem, D.

    1977-01-01

    A sequential but non-axiomatic high school geometry course which includes Euclidean, transformation, and analytic geometry and vectors and matrices, and emphasizes the invariance property of transformations, is outlined. Sample problems, solutions, and comments are included. (MN)

  5. Strange metals from quantum geometric fluctuations of interfaces

    NASA Astrophysics Data System (ADS)

    She, Jian-Huang; Bishop, A. R.; Balatsky, Alexander V.

    2016-05-01

    Our current understanding of strongly correlated electron systems is based on a homogeneous framework. Here we take a step going beyond this paradigm by incorporating inhomogeneity from the beginning. Specifying to systems near the Mott metal-insulator transition, we propose a real-space picture of itinerant electrons functioning in the fluctuating geometries bounded by interfaces between metallic and insulating regions. In 2+1 dimensions, the interfaces are closed bosonic strings, and we have a system of strings coupled to itinerant electrons. When the interface tension vanishes, the geometric fluctuations become critical, which gives rise to non-Fermi-liquid behavior for the itinerant electrons. In particular, the poles of the fermion Green's function can be converted to zeros, indicating the absence of propagating quasiparticles. Furthermore, the quantum geometric fluctuations mediate Cooper pairing among the itinerant electrons, indicating the intrinsic instability of electronic systems near the Mott transition.

  6. Density Fluctuations of Hard-Sphere Fluids in Narrow Confinement

    NASA Astrophysics Data System (ADS)

    Nygârd, Kim; Sarman, Sten; Hyltegren, Kristin; Chodankar, Shirish; Perret, Edith; Buitenhuis, Johan; van der Veen, J. Friso; Kjellander, Roland

    2016-01-01

    Spatial confinement induces microscopic ordering of fluids, which in turn alters many of their dynamic and thermodynamic properties. However, the isothermal compressibility has hitherto been largely overlooked in the literature, despite its obvious connection to the underlying microscopic structure and density fluctuations in confined geometries. Here, we address this issue by probing density profiles and structure factors of hard-sphere fluids in various narrow slits, using x-ray scattering from colloid-filled nanofluidic containers and integral-equation-based statistical mechanics at the level of pair distributions for inhomogeneous fluids. Most importantly, we demonstrate that density fluctuations and isothermal compressibilities in confined fluids can be obtained experimentally from the long-wavelength limit of the structure factor, providing a formally exact and experimentally accessible connection between microscopic structure and macroscopic, thermodynamic properties. Our approach will thus, for example, allow direct experimental verification of theoretically predicted enhanced density fluctuations in liquids near solvophobic interfaces.

  7. ACCELERATION OF VERY SMALL DUST GRAINS DUE TO RANDOM CHARGE FLUCTUATIONS

    SciTech Connect

    Hoang, Thiem; Lazarian, A.

    2012-12-20

    We study the acceleration of very small dust grains including polycyclic aromatic hydrocarbons arising from electrostatic interactions of dust grains that have charge fluctuating randomly in time. Random charge fluctuations of very small grains due to discrete charging events (i.e., sticking collisions with electrons and ions in plasma, and emission of photoelectrons by UV photons) are simulated using the Monte Carlo (MC) method. The motion of dust grains in randomly fluctuating electric fields induced by surrounding charged grains is studied using MC simulations. We identify the acceleration induced by random charge fluctuations as a dominant acceleration mechanism for very small grains in the diffuse interstellar medium (ISM). We find that this acceleration mechanism is efficient for environments with a low degree of ionization (i.e., large Debye length), where charge fluctuations are slow but have a large amplitude. The implications of the present acceleration mechanism for grain coagulation and shattering in the diffuse ISM and dark clouds are also discussed.

  8. Computer-Aided Geometry Modeling

    NASA Technical Reports Server (NTRS)

    Shoosmith, J. N. (Compiler); Fulton, R. E. (Compiler)

    1984-01-01

    Techniques in computer-aided geometry modeling and their application are addressed. Mathematical modeling, solid geometry models, management of geometric data, development of geometry standards, and interactive and graphic procedures are discussed. The applications include aeronautical and aerospace structures design, fluid flow modeling, and gas turbine design.

  9. Teaching of Geometry in Bulgaria

    ERIC Educational Resources Information Center

    Bankov, Kiril

    2013-01-01

    Geometry plays an important role in the school mathematics curriculum all around the world. Teaching of geometry varies a lot (Hoyls, Foxman, & Kuchemann, 2001). Many countries revise the objectives, the content, and the approaches to the geometry in school. Studies of the processes show that there are not common trends of these changes…

  10. Eccentricity and elliptic flow in pp collisions at the LHC

    NASA Astrophysics Data System (ADS)

    Avsar, E.; Hatta, Y.; Flensburg, C.; Ollitrault, J.-Y.; Ueda, T.

    2011-12-01

    High-multiplicity proton-proton collisions at the LHC may exhibit collective phenomena such as elliptic flow. We study this issue using DIPSY, a brand-new Monte Carlo event generator which features almost-NLO BFKL dynamics and describes the transverse shape of the proton including all fluctuations. We predict the eccentricity of the collision as a function of the multiplicity and estimate the magnitude of elliptic flow. We suggest that flow can be signaled by a sign change in the four-particle azimuthal correlation.

  11. Using higher moments of fluctuations and their ratios in the search for the QCD critical point

    SciTech Connect

    Athanasiou, Christiana; Rajagopal, Krishna; Stephanov, Misha

    2010-10-01

    The QCD critical point can be found in heavy-ion collision experiments via the nonmonotonic behavior of many fluctuation observables as a function of the collision energy. The event-by-event fluctuations of various particle multiplicities are enhanced in those collisions that freeze-out near the critical point. Higher, non-Gaussian, moments of the event-by-event distributions of such observables are particularly sensitive to critical fluctuations, since their magnitude depends on the critical correlation length to a high power. We present quantitative estimates of the contribution of critical fluctuations to the third and fourth moments of the pion, proton and net proton multiplicities, as well as estimates of various measures of pion-proton correlations, all as a function of the same five nonuniversal parameters, one of which is the correlation length that parametrizes proximity to the critical point. We show how to use nontrivial but parameter-independent ratios among these more than a dozen fluctuation observables to discover the critical point. We also construct ratios that, if the critical point is found, can be used to overconstrain the values of the nonuniversal parameters.

  12. Ratios of Fluctuation Observables in the Search for the QCD Critical Point

    NASA Astrophysics Data System (ADS)

    Athanasiou, Christiana; Rajagopal, Krishna; Stephanov, Misha

    2011-01-01

    The QCD critical point can be found in heavy ion collision experiments via the non-monotonic behavior of many fluctuation observables as a function of the collision energy. The event-by-event fluctuations of various particle multiplicities are enhanced in those collisions that freeze out near the critical point. Higher, non-Gaussian, moments of the event-by-event distributions of such observables are particularly sensitive to critical fluctuations, since their magnitude depends on the critical correlation length to a high power. We present quantitative estimates of the contribution of critical fluctuations to the third and fourth moments of the pion and proton, as well as estimates of various measures of pion-proton correlations, all as a function of the same five non-universal parameters. We show how to use nontrivial but parameter independent ratios among these more than a dozen fluctuation observables to discover the critical point. We also construct ratios that, if the critical point is found, can be used to overconstrain the values of the non-universal parameters.

  13. Using Higher Moments of Fluctuations and their Ratios in the Search for the QCD Critical Point

    NASA Astrophysics Data System (ADS)

    Athanasiou, Christiana; Rajagopal, Krishna; Stephanov, Misha

    2010-11-01

    The QCD critical point can be found in heavy ion collision experiments via the non-monotonic behavior of many fluctuation observables as a function of the collision energy. The event-by-event fluctuations of various particle multiplicities and momenta are enhanced in those collisions that freeze out near the critical point. Higher, non-Gaussian, moments of the event-by-event distributions of such observables are particularly sensitive to critical fluctuations, since their magnitude depends on the critical correlation length to a high power. We present quantitative estimates of the contribution of critical fluctuations to the third and fourth moments of the pion, proton and net proton multiplicities and mean transverse momenta, as well as estimates of various measures of pion-proton correlations, all as a function of the same five non-universal parameters, one of which is the correlation length that parametrizes proximity to the critical point. From these several dozen fluctuation observables, many dimensionless ratios can be constructed. We show how to use these ratios to discover the critical point and, if it is found, to overconstrain the values of the non-universal parameters.

  14. Fluctuations in electron cyclotron resonance plasma in a divergent magnetic field

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Sudeep; Fredriksen, Åshild; Chandra, Sayan

    2016-02-01

    The dependence of fluctuations on electron-neutral collision frequency (νen) and the radial location is investigated in an electron cyclotron resonance plasma in a divergent magnetic field region for a set of magnetic fields. Results indicate that the fluctuations depend strongly on the collision frequency. At lower magnetic fields and νen, the fluctuation levels are small and are observed to peak around 3-5 cm from the central plasma region. Coherent wave modes are found to contribute up to about 30% of the total fluctuation power, and two to three harmonics are present in the power spectra. There are two principal modes present in the discharge: one appears to be a dissipative mode associated with a collisional drift wave instability initiated at a lower pressure (collision frequencies) (˜0.5 mTorr) and is stabilized at a higher pressure (≳3 mTorr). The other mode appears at intermediate pressure (≳1.75 mTorr) and possesses the signature of a flute instability. The fluctuation levels indicate that flute modes are predominant in the discharge at higher pressures ( >1.75 mTorr) and at higher values of the magnetic field (˜540 Gauss).

  15. Azimuthal anisotropy in U+U collisions at STAR

    DOE PAGESBeta

    Wang, Hui; Sorensen, Paul

    2014-10-06

    The azimuthal anisotropy of particle production is commonly used in high-energy nuclear collisions to study the early evolution of the expanding system. The prolate shape of uranium nuclei makes it possible to study how the geometry of the colliding nuclei affects final state anisotropies. It also provides a unique opportunity to understand how entropy is produced in heavy ion collisions. In this paper, the two- and four- particle cumulant v2 (v2{2} and v2{4}) from U+U collisions at √sNN = 193 GeV and Au+Au collisions at √sNN = 200 GeV for inclusive charged hadrons will be presented. The STAR Zero Degreemore » Calorimeters are used to select very central collisions. Differences were observed between the multiplicity dependence of v2{2} for most central Au+Au and U+U collisions. The multiplicity dependence of v2{2} in central collisions were compared to Monte Carlo Glauber model predictions and it was seen that this model cannot explain the present results. (auth)« less

  16. Azimuthal anisotropy in U+U collisions at STAR

    SciTech Connect

    Wang, Hui; Sorensen, Paul

    2014-10-06

    The azimuthal anisotropy of particle production is commonly used in high-energy nuclear collisions to study the early evolution of the expanding system. The prolate shape of uranium nuclei makes it possible to study how the geometry of the colliding nuclei affects final state anisotropies. It also provides a unique opportunity to understand how entropy is produced in heavy ion collisions. In this paper, the two- and four- particle cumulant v2 (v2{2} and v2{4}) from U+U collisions at √sNN = 193 GeV and Au+Au collisions at √sNN = 200 GeV for inclusive charged hadrons will be presented. The STAR Zero Degree Calorimeters are used to select very central collisions. Differences were observed between the multiplicity dependence of v2{2} for most central Au+Au and U+U collisions. The multiplicity dependence of v2{2} in central collisions were compared to Monte Carlo Glauber model predictions and it was seen that this model cannot explain the present results. (auth)

  17. Electronic density fluctuation associated to coherent plasmon excitations

    NASA Astrophysics Data System (ADS)

    Gervasoni, Juana; Segui, Silvina; Arista, Nestor

    2011-10-01

    In this work we analyze, in the frame of the coherent states, the fluctuation of the electronic collective modes associated with the wake potential generated by an external particle of charge Ze. This perturbation is described as coherent states of plasmons spatially localized in an average distance of the order of the velocity of the projectile divided by the plasmon frequency of the material. One of the most important features is that in all the cases, for different trajectories of the external particle, and for different structures of the material, the fluctuations are not negligible. In particular, we observe that due to the importance of the surface in nanostructured materials, the fluctuation of density is very sensitive to their geometry and composition, fact that must have taken into account for the nanodevices designs. In this work we analyze, in the frame of the coherent states, the fluctuation of the electronic collective modes associated with the wake potential generated by an external particle of charge Ze. This perturbation is described as coherent states of plasmons spatially localized in an average distance of the order of the velocity of the projectile divided by the plasmon frequency of the material. One of the most important features is that in all the cases, for different trajectories of the external particle, and for different structures of the material, the fluctuations are not negligible. In particular, we observe that due to the importance of the surface in nanostructured materials, the fluctuation of density is very sensitive to their geometry and composition, fact that must have taken into account for the nanodevices designs. Acknowledgements to CNEA and CONICET, Argentina.

  18. Geometry of Quantum States

    NASA Astrophysics Data System (ADS)

    Bengtsson, Ingemar; Zyczkowski, Karol

    2006-05-01

    Quantum information theory is at the frontiers of physics, mathematics and information science, offering a variety of solutions that are impossible using classical theory. This book provides an introduction to the key concepts used in processing quantum information and reveals that quantum mechanics is a generalisation of classical probability theory. After a gentle introduction to the necessary mathematics the authors describe the geometry of quantum state spaces. Focusing on finite dimensional Hilbert spaces, they discuss the statistical distance measures and entropies used in quantum theory. The final part of the book is devoted to quantum entanglement - a non-intuitive phenomenon discovered by Schrödinger, which has become a key resource for quantum computation. This richly-illustrated book is useful to a broad audience of graduates and researchers interested in quantum information theory. Exercises follow each chapter, with hints and answers supplied. The first book to focus on the geometry of quantum states Stresses the similarities and differences between classical and quantum theory Uses a non-technical style and numerous figures to make the book accessible to non-specialists

  19. Gyrokinetic analysis of shear flow instability in torodial geometry

    NASA Astrophysics Data System (ADS)

    Yoon, Eisung; Hahm, T. S.

    2008-11-01

    Motivated by recent observation of intrinsic rotation in tokamak plasmas, we study linear stability of ion gyroradius scale short wavelength fluctuations in the presence of sheared parallel flow, ion temperature gradient, and toroidal mode coupling. Our gyrokinetic approach in toroidal geometry is an extension of previous studies including those by Catto et al., [Phys. Fluids 16 1719 (1973)] Mattor and Diamond [Phys. Fluids 31 1180 (1988)], and Artun and Tang [Phys. Fluids B 4 1102 (1992)].

  20. Azimuthal HBT and Transverse Momentum Fluctuations from CERES.

    SciTech Connect

    Miskowiec,D.; Rehak, P.; et al.

    2007-07-09

    CERES is a dilepton experiment at the CERN SPS, known for its observation of enhanced production of low mass efe- pairs in collisions between heavy nuclei [1]. The upgrade of CERES in 1997-1998 by a radial Time Projection Chamber (TPC) [2] allowed to improve the momentum resolution and the particle identification capability while retaining the cylindrical symmetry. The upgraded experiment is shown in Fig. 1. The upgrade also extended the sensitivity of CERES to hadrons and made possible results like those described below. The measurement of central Pb+Au collisions at the maximum SPS energy of 158 GeV per nucleon in the fall of 2000 was the first run of the fully upgraded CERES and at the same time the last run of this experiment. About 30 million Pb+Au collision events at 158 GeV per nucleon were collected, most of them with centrality within the top 7% of the geometrical cross section {sigma}{sub G} = 6.94 b. Small samples of the 20% and the minimum bias collisions, as well as a short run at 80 AGeV, were recorded in addition. The dilepton mass spectra from this experiment were published in [3]. In this talk I present two particular results of hadron analysis, the azimuthal dependence of two-pion correlations and a differential p{sub t} fluctuation study.

  1. Force Fluctuations and Correlations

    NASA Astrophysics Data System (ADS)

    Behringer, Robert

    1998-03-01

    Granular materials exhibit a rich array of dynamic and static phenomena which are only partly understood. Here, I focus on fluctuations in kinetic properties and in forces for slowly sheared granular materials. We have carried out a series of experiments in both 2D and in 3D. For 2D, we use a novel apparatus which allows us to quantify the forces, positions and orientations associated with individual grains. For slow to moderate shear rates, we find rate independence except for small random deviations which are associated with very long time changes in the system. The system evolves to a nearly steady average flow profile in which the velocity falls off approximately exponentially with distance from the shearing surface. The particle rotation shows systematic oscillations near the shearing surface. Velocity profiles show a complicated non-gaussian structure. Force measurements in both the 2D and 3D system are approximately exponentially distributed, but there are also some systematic deviations. Companion calculations by S. Schoellmann, S. Luding and H. Herrmann capture a number of these features. The experimental work has been carried out partially at Duke and partially at the E.S.P.C.I. Paris in collaboration with D. Howell, B. Miller, S. Tennakoon, and C. Veje.

  2. Fluctuations as stochastic deformation

    NASA Astrophysics Data System (ADS)

    Kazinski, P. O.

    2008-04-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic deformation to appropriate relativistic classical models. The analog of the Fokker-Planck equation associated with the stochastic Lorentz-Dirac equation is derived too. The stochastic deformation of the models of a free scalar field and an electromagnetic field is investigated. It turns out that in the latter case the obtained stochastic model describes a fluctuating electromagnetic field in a transparent medium.

  3. Fluctuations as stochastic deformation.

    PubMed

    Kazinski, P O

    2008-04-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic deformation to appropriate relativistic classical models. The analog of the Fokker-Planck equation associated with the stochastic Lorentz-Dirac equation is derived too. The stochastic deformation of the models of a free scalar field and an electromagnetic field is investigated. It turns out that in the latter case the obtained stochastic model describes a fluctuating electromagnetic field in a transparent medium.

  4. Chemical Applications of Fluctuation Spectroscopy.

    ERIC Educational Resources Information Center

    Green, Michael E.

    1984-01-01

    Examines some of the possibilities for applying the noise spectroscopic technique as well as the origin of noise (or fluctuations) which accompanies transport in physical systems. Indicates that fluctuation techniques are useful in studying liposome and micelle suspensions, liquid-liquid surfaces, semiconductors, and semiconductor devices. (JN)

  5. Conjunctions and Collision Avoidance with Electrodynamic Tethers

    NASA Astrophysics Data System (ADS)

    Levin, E.

    2013-09-01

    Electrodynamic propulsion technology is currently in development by NASA, ESA, and JAXA for the purpose of affordable removal of large debris objects from LEO. At the same time, the Naval Research Laboratory is preparing a 3U CubeSat with a 1-km electrodynamic tether for a flight demonstration of electrodynamic propulsion. This type of propulsion does not require fuel. The electrodynamic thrust is the Lorentz force acting on the electric current in a long conductor (tether) in the geomagnetic field. Electrons are collected from the ambient plasma on one end and emitted back into the plasma from the other end. The electric current loop is closed through the ionosphere, as demonstrated in two previous flights. The vehicle is solar powered. To support safe navigation of electrodynamic tethers, proper conjunction analysis and collision avoidance strategies are needed. The typical lengths of electrodynamic tethers for near-term applications are measured in kilometers, and the conjunction geometry is very different from the geometry of conjunctions between compact objects. It is commonly thought that the collision cross-section in a conjunction between a tether and a compact object is represented by the product of the tether length and the size of the object. However, rigorous analysis shows that this is not the case, and that the above assumption leads to grossly overestimated collision probabilities. The paper will present the results of a detailed mathematical analysis of the conjunction geometry and collision probabilities in close approaches between electrodynamic tethers and compact objects, such as satellites, rocket bodies, and debris fragments. Electrodynamic spacecraft will not require fuel, and therefore, can thrust constantly. Their orbit transfers can take many days, but can result in major orbit changes, including large rotations of the orbital plane, both in the inclination and the node. During these orbit transfers, the electrodynamic spacecraft will

  6. Frequency fluctuations in silicon nanoresonators

    PubMed Central

    Sansa, Marc; Sage, Eric; Bullard, Elizabeth C.; Gély, Marc; Alava, Thomas; Colinet, Eric; Naik, Akshay K.; Villanueva, Luis Guillermo; Duraffourg, Laurent; Roukes, Michael L.; Jourdan, Guillaume; Hentz, Sébastien

    2016-01-01

    Frequency stability is key to performance of nanoresonators. This stability is thought to reach a limit with the resonator’s ability to resolve thermally-induced vibrations. Although measurements and predictions of resonator stability usually disregard fluctuations in the mechanical frequency response, these fluctuations have recently attracted considerable theoretical interest. However, their existence is very difficult to demonstrate experimentally. Here, through a literature review, we show that all studies of frequency stability report values several orders of magnitude larger than the limit imposed by thermomechanical noise. We studied a monocrystalline silicon nanoresonator at room temperature, and found a similar discrepancy. We propose a new method to show this was due to the presence of frequency fluctuations, of unexpected level. The fluctuations were not due to the instrumentation system, or to any other of the known sources investigated. These results challenge our current understanding of frequency fluctuations and call for a change in practices. PMID:26925826

  7. Frequency fluctuations in silicon nanoresonators

    NASA Astrophysics Data System (ADS)

    Sansa, Marc; Sage, Eric; Bullard, Elizabeth C.; Gély, Marc; Alava, Thomas; Colinet, Eric; Naik, Akshay K.; Villanueva, Luis Guillermo; Duraffourg, Laurent; Roukes, Michael L.; Jourdan, Guillaume; Hentz, Sébastien

    2016-06-01

    Frequency stability is key to the performance of nanoresonators. This stability is thought to reach a limit with the resonator's ability to resolve thermally induced vibrations. Although measurements and predictions of resonator stability usually disregard fluctuations in the mechanical frequency response, these fluctuations have recently attracted considerable theoretical interest. However, their existence is very difficult to demonstrate experimentally. Here, through a literature review, we show that all studies of frequency stability report values several orders of magnitude larger than the limit imposed by thermomechanical noise. We studied a monocrystalline silicon nanoresonator at room temperature and found a similar discrepancy. We propose a new method to show that this was due to the presence of frequency fluctuations, of unexpected level. The fluctuations were not due to the instrumentation system, or to any other of the known sources investigated. These results challenge our current understanding of frequency fluctuations and call for a change in practices.

  8. Fluctuation phenomena in layered superconductors

    SciTech Connect

    Klemm, R.A.

    1996-10-01

    Gaussian fluctuations in layered superconductors have been the subject of study for many years. Although the FD was studied in detail long ago, the FC (fluctuation conductivity) was studied only recently, since the MT and DOS diagrams were previously neglected. Recent comparisons with experiment on YBCO have shown that the DOS diagrams are important and can lead to qualitatively different behaviors for the FC parallel and perpendicular to the layers. In both cases, Gaussian fluctuations fit the data above {Tc} very well, even for YBCO. To date, nearly all calculations of fluctuation quantities were for B{parallel}{cflx c}. Nevertheless, it should be possible to treat an arbitrary B, but the evaluation of the required matrix elements for the fluctuation quantities will be more complicated.

  9. Core fluctuations test. Revision 1

    SciTech Connect

    Betts, W.S.

    1987-06-01

    Fluctuations were first encountered in the Fort St. Vrain reactor early in cycle 1 operation, during the initial rise from 40% to 70% power. Subsequent in-core tests and operation throughout cycles 1 and 2 demonstrated that fluctuations were repeatable, occurring at core pressure drops of between 2.5 psi and 4.0 psi, and that in each instance their characteristics were very similar. Subsequently, tests and analysis were done to understand the core fluctuation phenomenon. These efforts also lead to a design fix which stopped these fluctuations in the FSV reactor core. This fix required that keys be used in addition to the keys in the core support floor which already existed. This report outlines a test plan to validate that core fluctuations will not occur in the MHTGR core. 2 refs., 12 figs., 3 tabs.

  10. Cosmic bubble collisions

    NASA Astrophysics Data System (ADS)

    Kleban, Matthew

    2011-10-01

    I briefly review the physics of cosmic bubble collisions in false-vacuum eternal inflation. My purpose is to provide an introduction to the subject for readers unfamiliar with it, focussing on recent work related to the prospects for observing the effects of bubble collisions in cosmology. I will attempt to explain the essential physical points as simply and concisely as possible, leaving most technical details to the references. I make no attempt to be comprehensive or complete. I also present a new solution to Einstein's equations that represents a bubble universe after a collision, containing vacuum energy and ingoing null radiation with an arbitrary density profile.

  11. Geometry controlled anomalous diffusion in random fractal geometries: looking beyond the infinite cluster.

    PubMed

    Mardoukhi, Yousof; Jeon, Jae-Hyung; Metzler, Ralf

    2015-11-28

    We investigate the ergodic properties of a random walker performing (anomalous) diffusion on a random fractal geometry. Extensive Monte Carlo simulations of the motion of tracer particles on an ensemble of realisations of percolation clusters are performed for a wide range of percolation densities. Single trajectories of the tracer motion are analysed to quantify the time averaged mean squared displacement (MSD) and to compare this with the ensemble averaged MSD of the particle motion. Other complementary physical observables associated with ergodicity are studied, as well. It turns out that the time averaged MSD of individual realisations exhibits non-vanishing fluctuations even in the limit of very long observation times as the percolation density approaches the critical value. This apparent non-ergodic behaviour concurs with the ergodic behaviour on the ensemble averaged level. We demonstrate how the non-vanishing fluctuations in single particle trajectories are analytically expressed in terms of the fractal dimension and the cluster size distribution of the random geometry, thus being of purely geometrical origin. Moreover, we reveal that the convergence scaling law to ergodicity, which is known to be inversely proportional to the observation time T for ergodic diffusion processes, follows a power-law ∼T(-h) with h < 1 due to the fractal structure of the accessible space. These results provide useful measures for differentiating the subdiffusion on random fractals from an otherwise closely related process, namely, fractional Brownian motion. Implications of our results on the analysis of single particle tracking experiments are provided.

  12. Speed-dependent collision effects on radar back-scattering from the ionosphere. [incoherent scatter radar

    NASA Technical Reports Server (NTRS)

    Behl, Y. K.; Theimer, O. H.

    1982-01-01

    The question whether the differences between fluctuation spectra for linearly speed-dependent and speed-independent collision frequencies could account for disagreements between rocket and incoherent scatter estimate was addressed. The basic theory used for computing the fluctuation spectrum is outlined. The speed-dependence of the charge-neutral collision frequency is discussed, with special emphasis on its derivation from the mobility measurements. Various developments of the computer code used for the computation of the fluctuation spectrum are described. The range of values of input parameters typical to the collision-dominated ionosphere are briefly described. The computational results are presented, and the significance and limitation of these results and the future scope of the research are discussed.

  13. Geometry from Gauge Theory

    SciTech Connect

    Correa, Diego H.; Silva, Guillermo A.

    2008-07-28

    We discuss how geometrical and topological aspects of certain (1/2)-BPS type IIB geometries are captured by their dual operators in N = 4 Super Yang-Mills theory. The type IIB solutions are characterized by arbitrary droplet pictures in a plane and we consider, in particular, axially symmetric droplets. The 1-loop anomalous dimension of the dual gauge theory operators probed with single traces is described by some bosonic lattice Hamiltonians. These Hamiltonians are shown to encode the topology of the droplets. In appropriate BMN limits, the Hamiltonians spectrum reproduces the spectrum of near-BPS string excitations propagating along each of the individual edges of the droplet. We also study semiclassical regimes for the Hamiltonians. For droplets having disconnected constituents, the Hamiltonian admits different complimentary semiclassical descriptions, each one replicating the semiclassical description for closed strings extending in each of the constituents.

  14. Critique of information geometry

    SciTech Connect

    Skilling, John

    2014-12-05

    As applied to probability, information geometry fails because probability distributions do not form a metric space. Probability theory rests on a compelling foundation of elementary symmetries, which also support information (aka minus entropy, Kullback-Leibler) H(p;q) as the unique measure of divergence from source probability distribution q to destination p. Because the only compatible connective H is from≠to asymmetric, H(p;q)≠H(q;p), there can be no compatible geometrical distance (which would necessarily be from=to symmetric). Hence there is no distance relationship compatible with the structure of probability theory. Metrics g and densities sqrt(det(g)) interpreted as prior probabilities follow from the definition of distance, and must fail likewise. Various metrics and corresponding priors have been proposed, Fisher's being the most popular, but all must behave unacceptably. This is illustrated with simple counter-examples.

  15. Optically defined mechanical geometry

    NASA Astrophysics Data System (ADS)

    Barasheed, Abeer Z.; Müller, Tina; Sankey, Jack C.

    2016-05-01

    In the field of optomechanics, radiation forces have provided a particularly high level of control over the frequency and dissipation of mechanical elements. Here we propose a class of optomechanical systems in which light exerts a similarly profound influence over two other fundamental parameters: geometry and mass. By applying an optical trap to one lattice site of an extended phononic crystal, we show it is possible to create a tunable, localized mechanical mode. Owing to light's simultaneous and constructive coupling with the structure's continuum of modes, we estimate that a trap power at the level of a single intracavity photon should be capable of producing a significant effect within a realistic, chip-scale device.

  16. Deformation driven by subduction and microplate collision: Geodynamics of Cook Inlet basin, Alaska

    USGS Publications Warehouse

    Bruhn, R.L.; Haeussler, P.J.

    2006-01-01

    Late Neogene and younger deformation in Cook Inlet basin is caused by dextral transpression in the plate margin of south-central Alaska. Collision and subduction of the Yakutat microplate at the northeastern end of the Aleutian subduction zone is driving the accretionary complex of the Chugach and Kenai Mountains toward the Alaska Range on the opposite side of the basin. This deformation creates belts of fault-cored anticlines that are prolific traps of hydrocarbons and are also potential sources for damaging earthquakes. The faults dip steeply, extend into the Mesozoic basement beneath the Tertiary basin fill, and form conjugate flower structures at some localities. Comparing the geometry of the natural faults and folds with analog models created in a sandbox deformation apparatus suggests that some of the faults accommodate significant dextral as well as reverse-slip motion. We develop a tectonic model in which dextral shearing and horizontal shortening of the basin is driven by microplate collision with an additional component of thrust-type strain caused by plate subduction. This model predicts temporally fluctuating stress fields that are coupled to the recurrence intervals of large-magnitude subduction zone earthquakes. The maximum principal compressive stress is oriented east-southeast to east-northeast with nearly vertical least compressive stress when the basin's lithosphere is mostly decoupled from the underlying subduction megathrust. This stress tensor is compatible with principal stresses inferred from focal mechanisms of earthquakes that occur within the crust beneath Cook Inlet basin. Locking of the megathrust between great magnitude earthquakes may cause the maximum principal compressive stress to rotate toward the northwest. Moderate dipping faults that strike north to northeast may be optimally oriented for rupture in the ambient stress field, but steeply dipping faults within the cores of some anticlines are unfavorably oriented with respect to

  17. Magnetism in curved geometries

    NASA Astrophysics Data System (ADS)

    Streubel, Robert; Fischer, Peter; Kronast, Florian; Kravchuk, Volodymyr P.; Sheka, Denis D.; Gaididei, Yuri; Schmidt, Oliver G.; Makarov, Denys

    2016-09-01

    Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or to launch novel functionalities by tailoring the geometry of an object, e.g. its local curvature. In a generic electronic system, curvature results in the appearance of scalar and vector geometric potentials inducing anisotropic and chiral effects. In the specific case of magnetism, even in the simplest case of a curved anisotropic Heisenberg magnet, the curvilinear geometry manifests two exchange-driven interactions, namely effective anisotropy and antisymmetric exchange, i.e. Dzyaloshinskii–Moriya-like interaction. As a consequence, a family of novel curvature-driven effects emerges, which includes magnetochiral effects and topologically induced magnetization patterning, resulting in theoretically predicted unlimited domain wall velocities, chirality symmetry breaking and Cherenkov-like effects for magnons. The broad range of altered physical properties makes these curved architectures appealing in view of fundamental research on e.g. skyrmionic systems, magnonic crystals or exotic spin configurations. In addition to these rich physics, the application potential of three-dimensionally shaped objects is currently being explored as magnetic field sensorics for magnetofluidic applications, spin-wave filters, advanced magneto-encephalography devices for diagnosis of epilepsy or for energy-efficient racetrack memory devices. These recent developments ranging from theoretical predictions over fabrication of three-dimensionally curved magnetic thin films, hollow cylinders or wires, to their characterization using integral means as well as the development of advanced tomography approaches are in the focus of this review.

  18. Magnetism in curved geometries

    NASA Astrophysics Data System (ADS)

    Streubel, Robert; Fischer, Peter; Kronast, Florian; Kravchuk, Volodymyr P.; Sheka, Denis D.; Gaididei, Yuri; Schmidt, Oliver G.; Makarov, Denys

    2016-09-01

    Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or to launch novel functionalities by tailoring the geometry of an object, e.g. its local curvature. In a generic electronic system, curvature results in the appearance of scalar and vector geometric potentials inducing anisotropic and chiral effects. In the specific case of magnetism, even in the simplest case of a curved anisotropic Heisenberg magnet, the curvilinear geometry manifests two exchange-driven interactions, namely effective anisotropy and antisymmetric exchange, i.e. Dzyaloshinskii-Moriya-like interaction. As a consequence, a family of novel curvature-driven effects emerges, which includes magnetochiral effects and topologically induced magnetization patterning, resulting in theoretically predicted unlimited domain wall velocities, chirality symmetry breaking and Cherenkov-like effects for magnons. The broad range of altered physical properties makes these curved architectures appealing in view of fundamental research on e.g. skyrmionic systems, magnonic crystals or exotic spin configurations. In addition to these rich physics, the application potential of three-dimensionally shaped objects is currently being explored as magnetic field sensorics for magnetofluidic applications, spin-wave filters, advanced magneto-encephalography devices for diagnosis of epilepsy or for energy-efficient racetrack memory devices. These recent developments ranging from theoretical predictions over fabrication of three-dimensionally curved magnetic thin films, hollow cylinders or wires, to their characterization using integral means as well as the development of advanced tomography approaches are in the focus of this review.

  19. Thermal spin fluctuations in spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Melé-Messeguer, M.; Juliá-Díaz, B.; Polls, A.; Santos, L.

    2013-03-01

    We study the thermal activation of spin fluctuations in dynamically stable spinor Bose-Einstein condensates. We analyze the specific cases of a nondipolar spin-1 condensate in the state m=0, where thermal activation results from spin-changing collisions, and of a chromium condensate in the maximally stretched state m=-3, where thermal spin fluctuations are due to dipole-induced spin relaxation. In both cases, we show that the low energy associated to the spinor physics may be employed for thermometry purposes down to extremely low temperatures, typically impossible to measure in Bose-Einstein condensates with the usual thermometric techniques. Moreover, the peculiar dependence of the system's entropy with the applied Zeeman energy opens a possible route for adiabatic cooling.

  20. Newton's Strange Collisions.

    ERIC Educational Resources Information Center

    Erlichson, Herman

    1995-01-01

    Discusses Newton's apparent oversight of the role of energy considerations in collisions between two spherical bodies related to the third corollary of his "Laws of Motion." Investigates several theories that provide solutions to the mysterious oversight. (LZ)

  1. The Sandbag Collision

    NASA Astrophysics Data System (ADS)

    Zou, Xueli

    2006-10-01

    As physics teachers, we all know that many introductory physics students have difficulties in understanding conservation of energy during inelastic collisions where the difficult-to-visualize concept of internal energy is involved. An interesting approach using a pair of model carts1,2 has been developed to help students visualize and understand the concept of internal thermal energy involved during an inelastic collision. This paper will illustrate a sandbag collision experiment that uses visible deformation of the sandbag to help students visualize where the kinetic energy goes during an inelastic collision. This experiment problem (as shown in Fig. 1) can be broken into three small subparts: 1) The pendulum bob swings down until right before hitting the box—a conservation of energy problem; 2) The bob collides with the box—a conservation of momentum problem; 3) The box slides on the table until it comes to a stop—a conservation of energy problem or a dynamics problem.

  2. Physics of Nuclear Collisions at High Energy

    SciTech Connect

    Hwa, Rudolph C.

    2012-05-01

    A wide range of problems has been investigated in the research program during the period of this grant. Although the major effort has been in the subject of heavy-ion collisions, we have also studied problems in biological and other physical systems. The method of analysis used in reducing complex data in multiparticle production to simple descriptions can also be applied to the study of complex systems of very different nature. Phase transition is an important phenomenon in many areas of physics, and for heavy-ion collisions we study the fluctuations of multiplicities at the critical point. Human brain activities as revealed in EEG also involve fluctuations in time series, and we have found that our experience enables us to find the appropriate quantification of the fluctuations in ways that can differentiate stroke and normal subjects. The main topic that characterizes the research at Oregon in heavy-ion collisions is the recombination model for the treatment of the hadronization process. We have avoided the hydrodynamical model partly because there is already a large community engaged in it, but more significantly we have found the assumption of rapid thermalization unconvincing. Recent results in studying LHC physics lead us to provide more evidence that shower partons are very important even at low p_T, but are ignored by hydro. It is not easy to work in an environment where the conventional wisdom regards our approach as being incorrect because it does not adhere to the standard paradigm. But that is just what a vibrant research community needs: unconventional approach may find evidences that can challenge the orthodoxy. An example is the usual belief that elliptic flow in fluid dynamics gives rise to azimuthal anisotropy. We claim that it is only sufficient but not necessary. With more data from LHC and more independent thinkers working on the subject what is sufficient as a theory may turn out to be incorrect in reality. Another area of investigation that

  3. Dynamics and Geometry of Equilibrium Laboratory Channels Well Above Threshold

    NASA Astrophysics Data System (ADS)

    Salter, G.; Jerolmack, D. J.

    2013-12-01

    The mechanisms governing the equilibrium channel geometry of alluvial rivers which transport sediment at well above the threshold of motion remain poorly understood. In nature, bed-load dominated gravel rivers are organized such that the channel-forming Shields stress is just at the threshold of motion on the banks. Most equilibrium channels created in laboratory experiments conform to this threshold geometry. However, sandy rivers in nature typically exhibit a Shields stress well above critical, and transport grains in suspension; this condition has not been replicated in the laboratory. The equilibrium geometry of these channels allow for sediment transport on the banks, leading to the stable channel paradox: bank stability seems incompatible with sediment transport. There must be a mechanism for delivering sediment back to the banks to counteract erosion. It is unclear whether bed-load and suspended-load rivers represent two unique stable equilibrium configurations, or whether there exists a continuum of possible geometries ranging from threshold to many times above threshold. Here we present laboratory experiments that produce a single-thread channel that transports grains at a Shields stress well above critical, using low-density acrylic sediment driven by a turbulent flow. Water and sediment are recirculated, and experiments are run at several different water discharge values to explore the transition from bed-load to suspension-dominated channels. Channel cross-section topographic scans and overhead images are used to quantify channel geometry and dynamics, and ensure that experiments reach a statistical steady state. Although statistical fluctuations are apparent, definite equilibrium channel geometries arise for each discharge. We relate channel geometry to dominant transport conditions using measured sediment flux and Shields stress values associated with steady-state dynamics, and characterize the nature of the transition from bed load to suspended load

  4. Photon-photon collisions

    SciTech Connect

    Burke, D.L.

    1982-10-01

    Studies of photon-photon collisions are reviewed with particular emphasis on new results reported to this conference. These include results on light meson spectroscopy and deep inelastic e..gamma.. scattering. Considerable work has now been accumulated on resonance production by ..gamma gamma.. collisions. Preliminary high statistics studies of the photon structure function F/sub 2//sup ..gamma../(x,Q/sup 2/) are given and comments are made on the problems that remain to be solved.

  5. Preheating in bubble collisions

    SciTech Connect

    Zhang Jun; Piao Yunsong

    2010-08-15

    In a landscape with metastable minima, the bubbles will inevitably nucleate. We show that when the bubbles collide, due to the dramatic oscillation of the field at the collision region, the energy deposited in the bubble walls can be efficiently released by the explosive production of the particles. In this sense, the collision of bubbles is actually highly inelastic. The cosmological implications of this result are discussed.

  6. Launch Collision Probability

    NASA Technical Reports Server (NTRS)

    Bollenbacher, Gary; Guptill, James D.

    1999-01-01

    This report analyzes the probability of a launch vehicle colliding with one of the nearly 10,000 tracked objects orbiting the Earth, given that an object on a near-collision course with the launch vehicle has been identified. Knowledge of the probability of collision throughout the launch window can be used to avoid launching at times when the probability of collision is unacceptably high. The analysis in this report assumes that the positions of the orbiting objects and the launch vehicle can be predicted as a function of time and therefore that any tracked object which comes close to the launch vehicle can be identified. The analysis further assumes that the position uncertainty of the launch vehicle and the approaching space object can be described with position covariance matrices. With these and some additional simplifying assumptions, a closed-form solution is developed using two approaches. The solution shows that the probability of collision is a function of position uncertainties, the size of the two potentially colliding objects, and the nominal separation distance at the point of closest approach. ne impact of the simplifying assumptions on the accuracy of the final result is assessed and the application of the results to the Cassini mission, launched in October 1997, is described. Other factors that affect the probability of collision are also discussed. Finally, the report offers alternative approaches that can be used to evaluate the probability of collision.

  7. Fluctuation driven EMFs in the Madison Dynamo Experiment

    NASA Astrophysics Data System (ADS)

    Kaplan, Elliot; Brown, Ben; Clark, Mike; Nornberg, Mark; Rahbarnia, Kian; Rasmus, Alex; Taylor, Zane; Forest, Cary

    2013-04-01

    The Madison Dynamo Experiment is a 1 m diameter sphere filled with liquid Sodium designed to study MHD in a simply connected geometry. Two impellers drive a two-vortex flow, based on the calculations of Dudley and James, intended to excite system-scale dynamo instability. We present a collection of results from experiments measuring hydrodynamic fluctuations and their MHD effects. An equatorial baffle was added to the experiment in order to diminish the large-eddy hydrodynamic fluctuations by stabilizing the shear layer between the two counter-rotating flow cells. The change in the fluctuation levels was inferred from the change in the spatial spectrum of the induced magnetic field. This reduction correlated with a 2.4 times increase in the induced toroidal magnetic field (a proxy measure of the effective resistivity). Furthermore, the local velocity fluctuations were directly measured by the addition of a 3-d emf probe (a strong permanent magnet inserted into the flow with electrical leads to measure the induced voltage, and magnetic probes to determine the magnetic fluctuations). The measured emfs are consistent with the enhanced magnetic diffusivity interpretation of mean-field MHD.

  8. GMC COLLISIONS AS TRIGGERS OF STAR FORMATION. I. PARAMETER SPACE EXPLORATION WITH 2D SIMULATIONS

    SciTech Connect

    Wu, Benjamin; Loo, Sven Van; Tan, Jonathan C.; Bruderer, Simon

    2015-09-20

    We utilize magnetohydrodynamic (MHD) simulations to develop a numerical model for giant molecular cloud (GMC)–GMC collisions between nearly magnetically critical clouds. The goal is to determine if, and under what circumstances, cloud collisions can cause pre-existing magnetically subcritical clumps to become supercritical and undergo gravitational collapse. We first develop and implement new photodissociation region based heating and cooling functions that span the atomic to molecular transition, creating a multiphase ISM and allowing modeling of non-equilibrium temperature structures. Then in 2D and with ideal MHD, we explore a wide parameter space of magnetic field strength, magnetic field geometry, collision velocity, and impact parameter and compare isolated versus colliding clouds. We find factors of ∼2–3 increase in mean clump density from typical collisions, with strong dependence on collision velocity and magnetic field strength, but ultimately limited by flux-freezing in 2D geometries. For geometries enabling flow along magnetic field lines, greater degrees of collapse are seen. We discuss observational diagnostics of cloud collisions, focussing on {sup 13}CO(J = 2–1), {sup 13}CO(J = 3–2), and {sup 12}CO(J = 8–7) integrated intensity maps and spectra, which we synthesize from our simulation outputs. We find that the ratio of J = 8–7 to lower-J emission is a powerful diagnostic probe of GMC collisions.

  9. Spinodal phase separation in relativistic nuclear collisions

    SciTech Connect

    Randrup, Joergen

    2010-09-15

    The spinodal amplification of density fluctuations is treated perturbatively within dissipative fluid dynamics for the purpose of elucidating the prospects for this mechanism to cause a phase separation to occur during a relativistic nuclear collision. The present study includes not only viscosity but also heat conduction (whose effect on the growth rates is of comparable magnitude but opposite), as well as a gradient term in the local pressure, and the corresponding dispersion relation for collective modes in bulk matter is derived from relativistic fluid dynamics. A suitable two-phase equation of state is obtained by interpolation between a hadronic gas and a quark-gluon plasma, while the transport coefficients are approximated by simple parametrizations that are suitable at any degree of net baryon density. We calculate the degree of spinodal amplification occurring along specific dynamical phase trajectories characteristic of nuclear collision at various energies. The results bring out the important fact that the prospects for spinodal phase separation to occur can be greatly enhanced by careful tuning of the collision energy to ensure that the thermodynamic conditions associated with the maximum compression lie inside the region of spinodal instability.

  10. Light nuclei production in relativistic Au+nucleus collisions

    SciTech Connect

    Bennett, M. J.; Pope, J. K.; Beavis, D.; Carroll, J. B.; Chiba, J.; Chikanian, A.; Crawford, H. J.; Cronqvist, M.; Dardenne, Y.; Kumar, B. S.; Nagle, J. L.; Debbe, R.; Doke, T.; Engelage, J.; Greiner, L.; Hayano, R S; Hallman, Timothy J.; Heckman, H. H.; Kashiwagi, T.; Kikuchi, J.; Tanaka, K. H.; Kumar, B. S.; Kuo, C.; Lindstrom, P. J.; Mitchell, J. W.; Nagle, J. L.; Stankus, P.; Tanaka, K. H.; Welsh, R. C.; Zhan, W.

    1998-08-01

    We have measured the yields of protons and A=2-4 nuclei in collisions between 10.8 A GeV/ c Au beams and targets of Al, Cu, and Au. The data, which cover a broad rapidity range at low transverse momenta, were measured as a function of collision centrality using a focusing beam line spectrometer and a high-rate centrality detector. We investigate the dependence of coalescence parameters on event geometry. The data are compared with the predictions of an RQMD+coalescence model. {copyright} {ital 1998} {ital The American Physical Society}

  11. Visually guided collision avoidance and collision achievement.

    PubMed

    Regan; Gray

    2000-03-01

    To survive on today's highways, a driver must have highly developed skills in visually guided collision avoidance. To play such games as cricket, tennis or baseball demands accurate, precise and reliable collision achievement. This review discusses evidence that some of these tasks are performed by predicting where an object will be at some sharply defined instant, several hundred milliseconds in the future, while other tasks are performed by utilizing the fact that some of our motor actions change what we see in ways that obey lawful relationships, and can therefore be learned. Several monocular and binocular visual correlates of the direction of an object's motion relative to the observer's head have been derived theoretically, along with visual correlates of the time to collision with an approaching object. Although laboratory psychophysics can identify putative neural mechanisms by showing which of the known correlates are processed by the human visual system independently of other visual information, it is only field research on, for example, driving, aviation and sport that can show which visual cues are actually used in these activities. This article reviews this research and describes a general psychophysically based rational approach to the design of such field studies.

  12. Designer switches: Effect of contact geometry on the transient current of a strongly correlated quantum dot

    NASA Astrophysics Data System (ADS)

    Goker, Ali Ihsan; Zhu, Zhiyong; Schwingenschlogl, Udo; Manchon, Aurelien

    2011-03-01

    The time-dependent non-crossing approximation is utilized to investigate the influence of the geometry of contacts made of gold on time dependent current through a quantum dot suddenly shifted into the Kondo regime via a gate voltage. For an asymmetrically coupled system, instantaneous conductance exhibits complex fluctuations. We identify the frequencies participating in these fluctuations and they turn out to be proportional to the separation between the sharp features in the density of states and the Fermi level. Increasing ambient temperature or bias quenches the amplitude of these fluctuations. This suggests that the interference between the emerging Kondo resonance and the van Hove singularities in the density of states is the underlying microscopic mechanism for these fluctuations. Based on these observations, we predict that using different electrode geometries would give rise to drastically different transient currents which can be accessed with state-of-the-art ultrafast pump-probe techniques. King Abdullah University of Science and Technology.

  13. Signatures of new phenomena in ultrarelativistic nuclear collisions

    SciTech Connect

    Gyulassy, M.

    1983-11-01

    Three classes of observables are discussed which may shed light on the properties of the quark-gluon plasma formed in ultrarelativistic nuclear collisions. They are: (1) thermometers: the penetrating probes ..mu../sup +/..mu../sup -/, ..gamma.., c, (2) barometers: transverse flow via

    , and (3) seismometers: fluctuations of dN/dy and dE perpendicular/dy. The need for reliable estimates of the background due to the non-equilibrium processes is emphasized. 49 references.

  14. Planetary Image Geometry Library

    NASA Technical Reports Server (NTRS)

    Deen, Robert C.; Pariser, Oleg

    2010-01-01

    The Planetary Image Geometry (PIG) library is a multi-mission library used for projecting images (EDRs, or Experiment Data Records) and managing their geometry for in-situ missions. A collection of models describes cameras and their articulation, allowing application programs such as mosaickers, terrain generators, and pointing correction tools to be written in a multi-mission manner, without any knowledge of parameters specific to the supported missions. Camera model objects allow transformation of image coordinates to and from view vectors in XYZ space. Pointing models, specific to each mission, describe how to orient the camera models based on telemetry or other information. Surface models describe the surface in general terms. Coordinate system objects manage the various coordinate systems involved in most missions. File objects manage access to metadata (labels, including telemetry information) in the input EDRs and RDRs (Reduced Data Records). Label models manage metadata information in output files. Site objects keep track of different locations where the spacecraft might be at a given time. Radiometry models allow correction of radiometry for an image. Mission objects contain basic mission parameters. Pointing adjustment ("nav") files allow pointing to be corrected. The object-oriented structure (C++) makes it easy to subclass just the pieces of the library that are truly mission-specific. Typically, this involves just the pointing model and coordinate systems, and parts of the file model. Once the library was developed (initially for Mars Polar Lander, MPL), adding new missions ranged from two days to a few months, resulting in significant cost savings as compared to rewriting all the application programs for each mission. Currently supported missions include Mars Pathfinder (MPF), MPL, Mars Exploration Rover (MER), Phoenix, and Mars Science Lab (MSL). Applications based on this library create the majority of operational image RDRs for those missions. A

  15. Investigating Fractal Geometry Using LOGO.

    ERIC Educational Resources Information Center

    Thomas, David A.

    1989-01-01

    Discusses dimensionality in Euclidean geometry. Presents methods to produce fractals using LOGO. Uses the idea of self-similarity. Included are program listings and suggested extension activities. (MVL)

  16. Principle of minimal work fluctuations

    NASA Astrophysics Data System (ADS)

    Xiao, Gaoyang; Gong, Jiangbin

    2015-08-01

    Understanding and manipulating work fluctuations in microscale and nanoscale systems are of both fundamental and practical interest. For example, in considering the Jarzynski equality =e-β Δ F , a change in the fluctuations of e-β W may impact how rapidly the statistical average of e-β W converges towards the theoretical value e-β Δ F, where W is the work, β is the inverse temperature, and Δ F is the free energy difference between two equilibrium states. Motivated by our previous study aiming at the suppression of work fluctuations, here we obtain a principle of minimal work fluctuations. In brief, adiabatic processes as treated in quantum and classical adiabatic theorems yield the minimal fluctuations in e-β W. In the quantum domain, if a system initially prepared at thermal equilibrium is subjected to a work protocol but isolated from a bath during the time evolution, then a quantum adiabatic process without energy level crossing (or an assisted adiabatic process reaching the same final states as in a conventional adiabatic process) yields the minimal fluctuations in e-β W, where W is the quantum work defined by two energy measurements at the beginning and at the end of the process. In the classical domain where the classical work protocol is realizable by an adiabatic process, then the classical adiabatic process also yields the minimal fluctuations in e-β W. Numerical experiments based on a Landau-Zener process confirm our theory in the quantum domain, and our theory in the classical domain explains our previous numerical findings regarding the suppression of classical work fluctuations [G. Y. Xiao and J. B. Gong, Phys. Rev. E 90, 052132 (2014), 10.1103/PhysRevE.90.052132].

  17. Principle of minimal work fluctuations.

    PubMed

    Xiao, Gaoyang; Gong, Jiangbin

    2015-08-01

    Understanding and manipulating work fluctuations in microscale and nanoscale systems are of both fundamental and practical interest. For example, in considering the Jarzynski equality 〈e-βW〉=e-βΔF, a change in the fluctuations of e-βW may impact how rapidly the statistical average of e-βW converges towards the theoretical value e-βΔF, where W is the work, β is the inverse temperature, and ΔF is the free energy difference between two equilibrium states. Motivated by our previous study aiming at the suppression of work fluctuations, here we obtain a principle of minimal work fluctuations. In brief, adiabatic processes as treated in quantum and classical adiabatic theorems yield the minimal fluctuations in e-βW. In the quantum domain, if a system initially prepared at thermal equilibrium is subjected to a work protocol but isolated from a bath during the time evolution, then a quantum adiabatic process without energy level crossing (or an assisted adiabatic process reaching the same final states as in a conventional adiabatic process) yields the minimal fluctuations in e-βW, where W is the quantum work defined by two energy measurements at the beginning and at the end of the process. In the classical domain where the classical work protocol is realizable by an adiabatic process, then the classical adiabatic process also yields the minimal fluctuations in e-βW. Numerical experiments based on a Landau-Zener process confirm our theory in the quantum domain, and our theory in the classical domain explains our previous numerical findings regarding the suppression of classical work fluctuations [G. Y. Xiao and J. B. Gong, Phys. Rev. E 90, 052132 (2014)].

  18. Fluctuations in classical sum rules.

    PubMed

    Elton, John R; Lakshminarayan, Arul; Tomsovic, Steven

    2010-10-01

    Classical sum rules arise in a wide variety of physical contexts. Asymptotic expressions have been derived for many of these sum rules in the limit of long orbital period (or large action). Although sum-rule convergence may well be exponentially rapid for chaotic systems in a global phase-space sense with time, individual contributions to the sums may fluctuate with a width which diverges in time. Our interest is in the global convergence of sum rules as well as their local fluctuations. It turns out that a simple version of a lazy baker map gives an ideal system in which classical sum rules, their corrections, and their fluctuations can be worked out analytically. This is worked out in detail for the Hannay-Ozorio sum rule. In this particular case the rate of convergence of the sum rule is found to be governed by the Pollicott-Ruelle resonances, and both local and global boundaries for which the sum rule may converge are given. In addition, the width of the fluctuations is considered and worked out analytically, and it is shown to have an interesting dependence on the location of the region over which the sum rule is applied. It is also found that as the region of application is decreased in size the fluctuations grow. This suggests a way of controlling the length scale of the fluctuations by considering a time dependent phase-space volume, which for the lazy baker map decreases exponentially rapidly with time.

  19. Generalised tensor fluctuations and inflation

    SciTech Connect

    Cannone, Dario; Tasinato, Gianmassimo; Wands, David E-mail: g.tasinato@swansea.ac.uk

    2015-01-01

    Using an effective field theory approach to inflation, we examine novel properties of the spectrum of inflationary tensor fluctuations, that arise when breaking some of the symmetries or requirements usually imposed on the dynamics of perturbations. During single-clock inflation, time-reparameterization invariance is broken by a time-dependent cosmological background. In order to explore more general scenarios, we consider the possibility that spatial diffeomorphism invariance is also broken by effective mass terms or by derivative operators for the metric fluctuations in the Lagrangian. We investigate the cosmological consequences of the breaking of spatial diffeomorphisms, focussing on operators that affect the power spectrum of fluctuations. We identify the operators for tensor fluctuations that can provide a blue spectrum without violating the null energy condition, and operators for scalar fluctuations that lead to non-conservation of the comoving curvature perturbation on superhorizon scales even in single-clock inflation. In the last part of our work, we also examine the consequences of operators containing more than two spatial derivatives, discussing how they affect the sound speed of tensor fluctuations, and showing that they can mimic some of the interesting effects of symmetry breaking operators, even in scenarios that preserve spatial diffeomorphism invariance.

  20. Quantum fluctuations of radiation pressure

    SciTech Connect

    Wu, Chun-Hsien; Ford, L. H.

    2001-08-15

    Quantum fluctuations of electromagnetic radiation pressure are discussed. We use an approach based on the quantum stress tensor to calculate the fluctuations in velocity and position of a mirror subjected to electromagnetic radiation. Our approach reveals that radiation pressure fluctuations in the case of a coherent state are due to a cross term between vacuum and state dependent terms in a stress tensor operator product. Thus observation of these fluctuations would entail experimental confirmation of this cross term. We first analyze the pressure fluctuations on a single, perfectly reflecting mirror, and then study the case of an interferometer. This involves a study of the effects of multiple bounces in one arm, as well as the correlations of the pressure fluctuations between arms of the interferometer. In all cases, our results are consistent with those previously obtained by Caves using different methods. We argue that the agreement between the different methods supports the reality of the cross term and justifies the methods used in its evaluation.

  1. Modeling of Momentum Correlations in Heavy Ion Collisions

    NASA Astrophysics Data System (ADS)

    Pruneau, Claude; Sharma, Monika

    2010-02-01

    Measurements of transverse momentum (pt) correlations and fluctuations in heavy ion collisions (HIC) are of interest because they provide information on the collision dynamics not readily available from number correlations. For instance, pt fluctuations are expected to diverge for a system near its tri-critical point [1]. Integral momentum correlations may also be used to estimate the shear viscosity of the quark gluon plasma produced in HIC [2]. Integral correlations measured over large fractions of the particle phase space average out several dynamical contributions and as such may be difficult to interpret. It is thus of interest to seek extensions of integral correlation variables that may provide more detailed information about the collision dynamics. We introduce a variety of differential momentum correlations and discuss their basic properties in the light of simple toy models. We also present theoretical predictions based on the PYTHIA, HIJING, AMPT, and EPOS models. Finally, we discuss the interplay of various dynamical effects that may play a role in the determination of the shear viscosity based on the broadening of momentum correlations measured as function of collision centrality. [1] L. Stodolsky, Phys. Rev. Lett. 75 (1995) 1044. [2] S. Gavin and M. A. Aziz, Phys. Rev. Lett. 97 (2006) 162302. )

  2. High-Frequency Fluctuations During Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Jara-Almonte, J.; Ji, H.; Daughton, W. S.; Roytershteyn, V.; Yamada, M.; Yoo, J.; Fox, W. R., II

    2014-12-01

    During collisionless reconnection, the decoupling of the field from the plasma is known to occur only within the localized ion and electron diffusion regions, however predictions from fully kinetic simulations do not agree with experimental observations on the size of the electron diffusion region, implying differing reconnection mechanisms. Previous experiments, along with 2D and 3D simulations, have conclusively shown that this discrepancy cannot be explained by either classical collisions or Lower-Hybrid Drift Instability (Roytershtyn 2010, 2013). Due to computational limitations, however, previous simulations were constrained to have minimal scale separation between the electron skin depth and the Debye length (de/λD ~ 10), much smaller than in experiments (de/λD ~ 300). This lack of scale-separation can drastically modify the electrostatic microphysics within the diffusion layer. Using 3D, fully explicit kinetic simulations with a realistic and unprecedentedly large separation between the Debye length and the electron skin depth, de/λD = 64, we show that high frequency electrostatic waves (ω >> ωLH) can exist within the electron diffusion region. These waves generate small-scale turbulence within the electron diffusion region which acts to broaden the layer. Anomalous resistivity is also generated by the turbulence and significantly modifies the force balance. In addition to simulation results, initial experimental measurements of high frequency fluctuations (electrostatic and electromagnetic, f ≤ 1 GHz) in the Magnetic Reconnection Experiment (MRX) will be presented.

  3. Universal properties of branching random walks in confined geometries

    NASA Astrophysics Data System (ADS)

    de Mulatier, C.; Mazzolo, A.; Zoia, A.

    2014-08-01

    Characterizing the occupation statistics of random walks through confined geometries amounts to assessing the distribution of the travelled length ℓ and the number of collisions n performed by the stochastic process in a given region, for which remarkably simple Cauchy-like formulas were established in the case of branching Pearson random walks with exponentially distributed jumps. In this letter, we derive two key results: first, we show that such formulas strikingly carry over to the much broader class of branching processes with arbitrary jumps, and have thus a universal character; second, we obtain a stronger version of these formulas relating the travelled length density and the collision density at any point of the phase space. Our results are key to such technological issues as the analysis of radiation flow for nuclear reactor design and medical diagnosis and apply more broadly to physical and biological systems with diffusion, reproduction and death.

  4. Ion Collision, Theory

    SciTech Connect

    Shukla, Anil K.

    2013-09-11

    The outcome of a collision between an ion and neutral species depends on the chemical and physical properties of the two reactants, their relative velocities, and the impact parameter of their trajectories. These include elastic and inelastic scattering of the colliding particles, charge transfer (including dissociative charge transfer), atom abstraction, complex formation and dissociation of the colliding ion. Each of these reactions may be characterized in terms of their energy-dependent rate coefficients, cross sections and reaction kinetics. A theoretical framework that emphasizes simple models and classical mechanics is presented for these processes. Collision processes are addressed in two categories of low-energy and high-energy collisions. Experiments under thermal or quasi-thermal conditions–swarms, drift tubes, chemical ionization and ion cyclotron resonance are strongly influenced by long-range forces and often involve collisions in which atom exchange and extensive energy exchange are common characteristics. High-energy collisions are typically impulsive, involve short-range intermolecular forces and are direct, fast processes.

  5. GPS: Geometry, Probability, and Statistics

    ERIC Educational Resources Information Center

    Field, Mike

    2012-01-01

    It might be said that for most occupations there is now less of a need for mathematics than there was say fifty years ago. But, the author argues, geometry, probability, and statistics constitute essential knowledge for everyone. Maybe not the geometry of Euclid, but certainly geometrical ways of thinking that might enable us to describe the world…

  6. Linguistic geometry for autonomous navigation

    SciTech Connect

    Stilman, B.

    1995-09-01

    To discover the inner properties of human expert heuristics, which were successful in a certain class of complex control systems, we develop a formal theory, the Linguistic Geometry. This paper reports two examples of application of Linguistic Geometry to autonomous navigation of aerospace vehicles that demonstrate dramatic search reduction.

  7. Microscope collision protection apparatus

    DOEpatents

    DeNure, Charles R.

    2001-10-23

    A microscope collision protection apparatus for a remote control microscope which protects the optical and associated components from damage in the event of an uncontrolled collision with a specimen, regardless of the specimen size or shape. In a preferred embodiment, the apparatus includes a counterbalanced slide for mounting the microscope's optical components. This slide replaces the rigid mounts on conventional upright microscopes with a precision ball bearing slide. As the specimen contacts an optical component, the contacting force will move the slide and the optical components mounted thereon. This movement will protect the optical and associated components from damage as the movement causes a limit switch to be actuated, thereby stopping all motors responsible for the collision.

  8. Collision of cosmic superstrings

    SciTech Connect

    Copeland, E. J.; Firouzjahi, H.; Kibble, T. W. B.; Steer, D. A.

    2008-03-15

    We study the formation of three-string junctions between (p,q)-cosmic superstrings, and collisions between such strings and show that kinematic constraints analogous to those found previously for collisions of Nambu-Goto strings apply here too, with suitable modifications to take account of the additional requirements of flux conservation. We examine in detail several examples involving collisions between strings with low values of p and q, and also examine the rates of growth or shrinkage of strings at a junction. Finally, we briefly discuss the formation of junctions for strings in a warped space, specifically with a Klebanov-Strassler throat, and show that similar constraints still apply with changes to the parameters taking account of the warping and the background flux.

  9. Quantum fluctuations and dynamic clustering of fluctuating Cooper pairs.

    SciTech Connect

    Glatz, A.; Varlamov, A. A.; Vinokur, V. M.

    2011-05-01

    We derive the complete expression for the fluctuation conductivity in two-dimensional superconductors as a function of the temperature and the magnetic field in the whole fluctuation region above the upper critical field H{sub c2}(T). Focusing on the vicinity of the quantum phase transition near zero temperature, we propose that as the magnetic field approaches the line near H{sub c2}(0) from above, a peculiar dynamic state consisting of clusters of coherently rotating fluctuation Cooper pairs forms and estimate the characteristic size and lifetime of such clusters. We find the zero-temperature magnetic-field dependence of the transverse magnetoconductivity above H{sub c2}(0) in layered superconductors.

  10. Lobachevsky's Geometry and Research of Geometry of the Universe

    NASA Astrophysics Data System (ADS)

    Brylevskaya, L. I.

    2008-10-01

    For the first time N. I. Lobachevsky gave a talk on the new geometry in 1826; three years after he had published a work "On the fundamentals of geometry", containing all fundamental theorems and methods of non-Euclidean geometry. A small part of the article was devoted to the study of geometry of the Universe. The interpretation of geometrical concepts in pure empirical way was typical for mathematicians at the beginning of the XIX century; in this connection it was important for scientists to find application of his geometry. Having the purpose to determine experimentally the properties of real physical Space, Lobachevsky decided to calculate the sum of angles in a huge triangle with two vertexes in opposite points of the terrestrial orbit and the third -- on the remote star. Investigating the possibilities of solution of the set task, Lobachevsky faced the difficulties of theoretical, technical and methodological character. More detailed research of different aspects of the problem led Lobachevsky to the comprehension of impossibility to obtain the values required for the goal achievement, and he called his geometry an imaginary geometry.

  11. Topics in fluctuating nonlinear hydrodynamics

    SciTech Connect

    Milner, S.T.

    1986-01-01

    Models of fluctuating nonlinear hydrodynamics have enjoyed much success in explaining the effect of long-wavelength fluctuations in diverse hydrodynamic systems. This thesis explores two such problems; in both, the body of hydrodynamic assumptions powerfully constrains the predictions of a well-posed theory. The effects of layer fluctuations in smectic-A liquid crystals are first examined. The static theory (introduced by Grinstein and Pelcovits) is reviewed. Ward identities, resulting from the arbitrariness of the layering direction, are derived and exploited. The static results motivate an examination of dynamic fluctuation effects. A new sound-damping experiment is proposed that would probe singular dependence of viscosities on applied stress. A theory of Procaccia and Gitterman that reaction rates of chemically reacting binary mixtures are drastically reduced near their thermodynamic critical points is analyzed. Hydrodynamic arguments and Van Hove theory are applied, concluding that the PG idea is drastically slowed, and spatially varying composition fluctuations are at best slowed down over a narrow range of wavenumbers.

  12. Measurement of flow harmonics with multi-particle cumulants in Pb+Pb collisions at √sNN = 2.76  TeV with the ATLAS detector

    SciTech Connect

    Aad, G.

    2014-11-26

    ATLAS measurements of the azimuthal anisotropy in lead–lead collisions at √sNN = 2.76 TeV are shown using a dataset of approximately 7 μb–1 collected at the LHC in 2010. The measurements are performed for charged particles with transverse momenta 0.5 < pT < 20 GeV and in the pseudorapidity range |η| < 2.5. The anisotropy is characterized by the Fourier coefficients, vn, of the charged-particle azimuthal angle distribution for n = 2–4. The Fourier coefficients are evaluated using multi-particle cumulants calculated with the generating function method. Results on the transverse momentum, pseudorapidity and centrality dependence of the vn coefficients are presented. The elliptic flow, v2, is obtained from the two-, four-, six- and eight-particle cumulants while higher-order coefficients, v3 and v4, are determined with two- and four-particle cumulants. Flow harmonics vn measured with four-particle cumulants are significantly reduced compared to the measurement involving two-particle cumulants. A comparison to vn measurements obtained using different analysis methods and previously reported by the LHC experiments is also shown. Results of measurements of flow fluctuations evaluated with multi-particle cumulants are shown as a function of transverse momentum and the collision centrality. As a result, models of the initial spatial geometry and its fluctuations fail to describe the flow fluctuations measurements.

  13. TURBULENCE-INDUCED RELATIVE VELOCITY OF DUST PARTICLES. IV. THE COLLISION KERNEL

    SciTech Connect

    Pan, Liubin; Padoan, Paolo E-mail: ppadoan@icc.ub.edu

    2014-12-20

    Motivated by its importance for modeling dust particle growth in protoplanetary disks, we study turbulence-induced collision statistics of inertial particles as a function of the particle friction time, τ{sub p}. We show that turbulent clustering significantly enhances the collision rate for particles of similar sizes with τ{sub p} corresponding to the inertial range of the flow. If the friction time, τ{sub p,} {sub h}, of the larger particle is in the inertial range, the collision kernel per unit cross section increases with increasing friction time, τ{sub p,} {sub l}, of the smaller particle and reaches the maximum at τ{sub p,} {sub l} = τ{sub p,} {sub h}, where the clustering effect peaks. This feature is not captured by the commonly used kernel formula, which neglects the effect of clustering. We argue that turbulent clustering helps alleviate the bouncing barrier problem for planetesimal formation. We also investigate the collision velocity statistics using a collision-rate weighting factor to account for higher collision frequency for particle pairs with larger relative velocity. For τ{sub p,} {sub h} in the inertial range, the rms relative velocity with collision-rate weighting is found to be invariant with τ{sub p,} {sub l} and scales with τ{sub p,} {sub h} roughly as ∝ τ{sub p,h}{sup 1/2}. The weighting factor favors collisions with larger relative velocity, and including it leads to more destructive and less sticking collisions. We compare two collision kernel formulations based on spherical and cylindrical geometries. The two formulations give consistent results for the collision rate and the collision-rate weighted statistics, except that the spherical formulation predicts more head-on collisions than the cylindrical formulation.

  14. Thermodynamic constraints on fluctuation phenomena

    NASA Astrophysics Data System (ADS)

    Maroney, O. J. E.

    2009-12-01

    The relationships among reversible Carnot cycles, the absence of perpetual motion machines, and the existence of a nondecreasing globally unique entropy function form the starting point of many textbook presentations of the foundations of thermodynamics. However, the thermal fluctuation phenomena associated with statistical mechanics has been argued to restrict the domain of validity of this basis of the second law of thermodynamics. Here we demonstrate that fluctuation phenomena can be incorporated into the traditional presentation, extending rather than restricting the domain of validity of the phenomenologically motivated second law. Consistency conditions lead to constraints upon the possible spectrum of thermal fluctuations. In a special case this uniquely selects the Gibbs canonical distribution and more generally incorporates the Tsallis distributions. No particular model of microscopic dynamics need be assumed.

  15. Fluctuational electrodynamics of hyperbolic metamaterials

    SciTech Connect

    Guo, Yu; Jacob, Zubin

    2014-06-21

    We give a detailed account of equilibrium and non-equilibrium fluctuational electrodynamics of hyperbolic metamaterials. We show the unifying aspects of two different approaches; one utilizes the second kind of fluctuation dissipation theorem and the other makes use of the scattering method. We analyze the near-field of hyperbolic media at finite temperatures and show that the lack of spatial coherence can be attributed to the multi-modal nature of super-Planckian thermal emission. We also adopt the analysis to phonon-polaritonic super-lattice metamaterials and describe the regimes suitable for experimental verification of our predicted effects. The results reveal that far-field thermal emission spectra are dominated by epsilon-near-zero and epsilon-near-pole responses as expected from Kirchoff's laws. Our work should aid both theorists and experimentalists to study complex media and engineer equilibrium and non-equilibrium fluctuations for applications in thermal photonics.

  16. Fluctuations in relativistic causal hydrodynamics

    NASA Astrophysics Data System (ADS)

    Kumar, Avdhesh; Bhatt, Jitesh R.; Mishra, Ananta P.

    2014-05-01

    Formalism to calculate the hydrodynamic fluctuations by applying the Onsager theory to the relativistic Navier-Stokes equation is already known. In this work, we calculate hydrodynamic fluctuations within the framework of the second order hydrodynamics of Müller, Israel and Stewart and its generalization to the third order. We have also calculated the fluctuations for several other causal hydrodynamical equations. We show that the form for the Onsager-coefficients and form of the correlation functions remain the same as those obtained by the relativistic Navier-Stokes equation and do not depend on any specific model of hydrodynamics. Further we numerically investigate evolution of the correlation function using the one dimensional boost-invariant (Bjorken) flow. We compare the correlation functions obtained using the causal hydrodynamics with the correlation function for the relativistic Navier-Stokes equation. We find that the qualitative behavior of the correlation functions remains the same for all the models of the causal hydrodynamics.

  17. Thermodynamic constraints on fluctuation phenomena.

    PubMed

    Maroney, O J E

    2009-12-01

    The relationships among reversible Carnot cycles, the absence of perpetual motion machines, and the existence of a nondecreasing globally unique entropy function form the starting point of many textbook presentations of the foundations of thermodynamics. However, the thermal fluctuation phenomena associated with statistical mechanics has been argued to restrict the domain of validity of this basis of the second law of thermodynamics. Here we demonstrate that fluctuation phenomena can be incorporated into the traditional presentation, extending rather than restricting the domain of validity of the phenomenologically motivated second law. Consistency conditions lead to constraints upon the possible spectrum of thermal fluctuations. In a special case this uniquely selects the Gibbs canonical distribution and more generally incorporates the Tsallis distributions. No particular model of microscopic dynamics need be assumed.

  18. Multiplicity fluctuations of identified hadrons in p+p interactions at SPS energies

    NASA Astrophysics Data System (ADS)

    Maćkowiak-Pawłowska, Maja; Wilczek, Andrzej; Na61 Collaboration

    2014-05-01

    Study of energy and system size fluctuations of identified hadrons is one of the key goals of NA61/SHINE at the CERN SPS. Results may allow to discover the critical point (CP) of strongly interacting matter as well as to uncover properties of the onset of deconfinement (OD). But fluctuations exhibit numerous other sources starting from most basic ones like volume effects and conservation laws. NA49 seems to observe fluctuations related to CP in collisions of medium size nuclei at top SPS energy. However, this result will remain inconclusive until systematic data on energy and system size dependence will be available. Moreover, fluctuations in p+p as well as in Pb+Pb interactions should be better understood. In this contribution results on multiplicity fluctuations of identified hadrons in p+p interactions at the CERN SPS energies will be presented. The NA61 data will be compared with the corresponding results from central Pb+Pb collisions of NA49 in the common acceptance region of both experiments. Moreover, predictions of models (EPOS, UrQMD and HSD) for both reactions will be tested.

  19. Thermal fluctuations and rubber elasticity.

    PubMed

    Xing, Xiangjun; Goldbart, Paul M; Radzihovsky, Leo

    2007-02-16

    The effects of thermal elastic fluctuations in rubbery materials are examined. It is shown that, due to their interplay with the incompressibility constraint, these fluctuations qualitatively modify the large-deformation stress-strain relation, compared to that of classical rubber elasticity. To leading order, this mechanism provides a simple and generic explanation for the peak structure of Mooney-Rivlin stress-strain relation and shows good agreement with experiments. It also leads to the prediction of a phonon correlation function that depends on the external deformation. PMID:17359034

  20. Thermal Fluctuations and Rubber Elasticity

    NASA Astrophysics Data System (ADS)

    Xing, Xiangjun; Goldbart, Paul M.; Radzihovsky, Leo

    2007-02-01

    The effects of thermal elastic fluctuations in rubbery materials are examined. It is shown that, due to their interplay with the incompressibility constraint, these fluctuations qualitatively modify the large-deformation stress-strain relation, compared to that of classical rubber elasticity. To leading order, this mechanism provides a simple and generic explanation for the peak structure of Mooney-Rivlin stress-strain relation and shows good agreement with experiments. It also leads to the prediction of a phonon correlation function that depends on the external deformation.

  1. Fluctuation driven electroweak phase transition

    NASA Technical Reports Server (NTRS)

    Gleiser, Marcelo; Kolb, Edward W.

    1991-01-01

    We examine the dynamics of the electroweak phase transition in the early Universe. For Higgs masses in the range 46 less than or = M sub H less than or = 150 GeV and top quark masses less than 200 GeV, regions of symmetric and asymmetric vacuum coexist to below the critical temperature, with thermal equilibrium between the two phases maintained by fluctuations of both phases. We propose that the transition to the asymmetric vacuum is completed by percolation of these subcritical fluctuations. Our results are relevant to scenarios of baryogenesis that invoke a weakly first-order phase transition at the electroweak scale.

  2. NeXSPheRIO results on elliptic-flow fluctuations at RHIC

    SciTech Connect

    Hama, Y. Andrade, R. P. G.; Grassi, F.; Qian, W.-L.; Osada, T.; Aguiar, C. E.; Kodama, T.

    2008-09-15

    By using the NeXSPheRIO code, we study the elliptic-flow fluctuations in Au + Au collisions at 200 A GeV. It is shown that, by fixing the parameters of the model to correctly reproduce the charged pseudorapidity and the transverse-momentum distributions, reasonable agreement of with data is obtained, both as function of pseudorapidity as well as of transverse momentum, for charged particles. Our results on elliptic-flow fluctuations are in good agreement with the recently measured data on experiments.

  3. Quantum Consequences of Parameterizing Geometry

    NASA Astrophysics Data System (ADS)

    Wanas, M. I.

    2002-12-01

    The marriage between geometrization and quantization is not successful, so far. It is well known that quantization of gravity , using known quantization schemes, is not satisfactory. It may be of interest to look for another approach to this problem. Recently, it is shown that geometries with torsion admit quantum paths. Such geometries should be parameterizied in order to preserve the quantum properties appeared in the paths. The present work explores the consequences of parameterizing such geometry. It is shown that quantum properties, appeared in the path equations, are transferred to other geometric entities.

  4. CATIA-GDML geometry builder

    NASA Astrophysics Data System (ADS)

    Belogurov, S.; Berchun, Yu; Chernogorov, A.; Malzacher, P.; Ovcharenko, E.; Semennikov, A.

    2011-12-01

    Due to conceptual difference between geometry descriptions in Computer-Aided Design (CAD) systems and particle transport Monte Carlo (MC) codes direct conversion of detector geometry in either direction is not feasible. An original set of tools has been developed for building a GEANT4/ROOT compatible geometry in the CATIA CAD system and exchanging it with mentioned MC packages using GDML file format. A Special structure of a CATIA product tree, a wide range of primitives, different types of multiple volume instantiation, and supporting macros have been implemented.

  5. Space collision threat mitigation

    NASA Astrophysics Data System (ADS)

    Zatezalo, Aleksandar; Stipanović, Dušan; Mehra, Raman K.; Pham, Khanh

    2014-06-01

    Mitigation of possible collision threats to current and future operations in space environments is an important an challenging task considering high nonlinearity of orbital dynamics and discrete measurement updates. Such discrete observations are relatively scarce with respect to space dynamics including possible unintentional or intentional rocket propulsion based maneuvers even in scenarios when measurement collections are focused to a one single target of interest. In our paper, this problem is addressed in terms of multihypothesis and multimodel estimation in conjunction with multi-agent multigoal game theoretic guaranteed evasion strategies. Collision threat estimation is formulated using conditional probabilities of time dependent hypotheses and spacecraft controls which are computed using Liapunov-like approach. Based on this formulation, time dependent functional forms of multi-objective utility functions are derived given threat collision risk levels. For demonstrating developed concepts, numerical methods are developed using nonlinear filtering methodology for updating hypothesis sets and corresponding conditional probabilities. Space platform associated sensor resources are managed using previously developed and demonstrated information-theoretic objective functions and optimization methods. Consequently, estimation and numerical methods are evaluated and demonstrated on a realistic Low Earth Orbit collision encounter.

  6. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  7. Atomic collisions, inelastic indeed

    NASA Astrophysics Data System (ADS)

    Bercegol, Herve; Ferrando, Gwenael; Lehoucq, Roland

    At the turn of the twentieth century, a hot controversy raged about the ability of Boltzmann's framework to take care of irreversibility. The so-called Loschmidt's paradox progressively faded with time during the last hundred years, due to the predictive efficiency of statistical mechanics. However, one detail at the origin of the controversy - the elasticity of atomic collisions - was not completely challenged. A semi-classical treatment of two atoms interacting with the vacuum zero-point field permits to predict a friction force acting against the rotation of the pair of atoms. By its form and its level, the calculated torque is a candidate as a physical cause for diffusion of energy and angular momentum, and consequently for entropy growth. It opens the way to a revision of the standard vision of irreversibility. This presentation will focus on two points. First we will discuss the recent result in a broader context of electromagnetic interactions during microscopic collisions. The predicted friction phenomenon can be compared to and distinguished from Collision-Induced Emission and other types of inelastic collisions. Second we will investigate the consequences of the friction torque on calculated trajectories of colliding atoms, quantifying the generation of dimers linked by dispersion forces.

  8. Charge-dependent azimuthal correlations from AuAu to UU collisions

    NASA Astrophysics Data System (ADS)

    Bloczynski, John; Huang, Xu-Guang; Zhang, Xilin; Liao, Jinfeng

    2015-07-01

    We study the charge-dependent azimuthal correlations in relativistic heavy ion collisions, as motivated by the search for the Chiral Magnetic Effect (CME) and the investigation of related background contributions. In particular we aim to understand how these correlations induced by various proposed effects evolve from collisions with AuAu system to that with UU system. To do that, we quantify the generation of magnetic field in UU collisions at RHIC energy and its azimuthal correlation with the matter geometry using event-by-event simulations. Taking the experimental data for charge-dependent azimuthal correlations from AuAu collisions and extrapolating to UU with reasonable assumptions, we examine the resulting correlations to be expected in UU collisions and compare them with recent STAR measurements. Based on such analysis we discuss the viability for explaining the data with a combination of the CME-like and flow-induced contributions.

  9. QGP flow fluctuations and the characteristics of higher moments

    NASA Astrophysics Data System (ADS)

    Wang, D. J.; Csernai, L. P.; Strottman, D.; Anderlik, Cs.; Cheng, Y.; Zhou, D. M.; Yan, Y. L.; Cai, X.; Sa, B. H.

    2012-11-01

    The dynamical development of expanding Quark-gluon Plasma (QGP) flow is studied in a 3+1D fluid dynamical model with a globally symmetric, initial condition. We minimize fluctuations arising from complex dynamical processes at finite impact parameters and from fluctuating random initial conditions to have a conservative fluid dynamical background estimate for the statistical distributions of the thermodynamical parameters. We also avoid a phase transition in the equation of state, and we let the matter supercool during the expansion. Then central Pb + Pb collisions at sqrt{s_{NN}}=2.76 TeV are studied in an almost perfect fluid dynamical model, with azimuthally symmetric initial state generated in a dynamical flux-tube model. The general development of thermodynamical extensives are also shown for lower energies. We observe considerable deviations from a thermal equilibrium source, changing skewness and kurtosis by time depending on beam energy as a consequence of the fluid dynamical expansion arising from a least fluctuating initial state.

  10. Interferometers as probes of Planckian quantum geometry

    NASA Astrophysics Data System (ADS)

    Hogan, Craig J.

    2012-03-01

    A theory of position of massive bodies is proposed that results in an observable quantum behavior of geometry at the Planck scale, tP. Departures from classical world lines in flat spacetime are described by Planckian noncommuting operators for position in different directions, as defined by interactions with null waves. The resulting evolution of position wave functions in two dimensions displays a new kind of directionally coherent quantum noise of transverse position. The amplitude of the effect in physical units is predicted with no parameters, by equating the number of degrees of freedom of position wave functions on a 2D space-like surface with the entropy density of a black hole event horizon of the same area. In a region of size L, the effect resembles spatially and directionally coherent random transverse shear deformations on time scale ≈L/c with typical amplitude ≈ctPL. This quantum-geometrical “holographic noise” in position is not describable as fluctuations of a quantized metric, or as any kind of fluctuation, dispersion or propagation effect in quantum fields. In a Michelson interferometer the effect appears as noise that resembles a random Planckian walk of the beam splitter for durations up to the light-crossing time. Signal spectra and correlation functions in interferometers are derived, and predicted to be comparable with the sensitivities of current and planned experiments. It is proposed that nearly colocated Michelson interferometers of laboratory scale, cross-correlated at high frequency, can test the Planckian noise prediction with current technology.

  11. Instability of supersymmetric microstate geometries

    NASA Astrophysics Data System (ADS)

    Eperon, Felicity C.; Reall, Harvey S.; Santos, Jorge E.

    2016-10-01

    We investigate the classical stability of supersymmetric, asymptotically flat, microstate geometries with five non-compact dimensions. Such geometries admit an "evanescent ergosurface": a timelike hypersurface of infinite redshift. On such a surface, there are null geodesics with zero energy relative to infinity. These geodesics are stably trapped in the potential well near the ergosurface. We present a heuristic argument indicating that this feature is likely to lead to a nonlinear instability of these solutions. We argue that the precursor of such an instability can be seen in the behaviour of linear perturbations: nonlinear stability would require that all linear perturbations decay sufficiently rapidly but the stable trapping implies that some linear perturbation decay very slowly. We study this in detail for the most symmetric microstate geometries. By constructing quasinormal modes of these geometries we show that generic linear perturbations decay slower than any inverse power of time.

  12. Formation geometries for multistatic SAR tomography

    NASA Astrophysics Data System (ADS)

    Fasano, Giancarmine; Renga, Alfredo; D'Errico, Marco

    2014-03-01

    This paper analyzes relative orbit design for multi-satellite radar missions aimed at multistatic SAR tomography. To this end, formation requirements and performance parameters are derived by adapting existing models for SAR tomography to single pass techniques. Then, relative trajectory design is carried out on the basis of an analytical relative motion model including secular J2 effects. By properly scaling the differences in orbital parameters, different formation geometries enable uniform sampling of the effective baseline along the whole orbit. The difference among the possible choices lies in latitude coverage, formation stability, and collision avoidance aspects. A numerical example of relative trajectory design is discussed considering L-band as operating frequency. In particular, achievable height resolution and unambiguous height along the orbit are pointed out for a multi-cartwheel, a multi-pendulum, and a multi-helix formation. In view of future implementation of a multi-satellite SAR tomography mission, new concepts aimed at the reduction of required satellites, and long term evolution of designed formations, are also discussed.

  13. Studying Phase Transitions in Nuclear Collisions

    SciTech Connect

    Mishustin, I.N.

    2000-12-31

    Three main topics are discussed concerning the theoretical description and observable signatures of possible phase transitions in nuclear collisions. The first one is related to the multifragmentation of equilibrated sources and its connection to a liquid-gas phase transition in finite systems. The second one deals with the Coulomb excitation of ultrarelativistic heavy ions resulting in their deep disintegration. The third topic is devoted to the description of a first-order phase transition in rapidly expanding matter. The resulting picture is that a strong collective flow of matter will lead to the fragmentation of a metastable phase into droplets. If the transition from quark-gluon plasma to hadron gas is of the first order, it will manifest itself by strong nonstatistical fluctuations in observable hadron distributions.

  14. Stage fluctuations of Wisconsin lakes

    USGS Publications Warehouse

    House, Leo B.

    1985-01-01

    This report describes lake-stage fluctuations of 83 gaged lakes in Wisconsin and presents techniques for estimating stage fluctuation at ungaged lakes. Included are stage information at 83 lakes and stage-frequency data for 32 of these lakes that had sufficient record for analysis. Lakes are classified by a hydrologic-topographic lake classification scheme as ground-water flowthrough (GWF) lakes, surface-water drainage (SWD) lakes, and surface-water flow-through (SWF) lakes. Lakes within the same class were found to have similar water-level fluctuations. The lake-stage records indicate that most annual maximums occur during the months of May and June for all three classes. Annual minimum lake levels generally occur in September for surface-water drainage lakes, in March for surface-water flowthrough lakes, and in November for ground-water flow-through lakes. Data for each lake include location, period of water-level record, hydrologic classification, drainage area, surface area, lake volume, maximum depth, long-term mean stage and its standard deviation, maximum and minimum observed lake stage, and the average annual lake-stage fluctuation.

  15. Low Mach number fluctuating hydrodynamics of multispecies liquid mixtures

    SciTech Connect

    Donev, Aleksandar Bhattacharjee, Amit Kumar; Nonaka, Andy; Bell, John B.; Garcia, Alejandro L.

    2015-03-15

    miscible interface due to coupling between Rayleigh–Taylor and double-diffusive convective modes,” Phys. Fluids 25, 024107 (2013)] in a Hele-Shaw cell. We find that giant nonequilibrium fluctuations can trigger the instability but are eventually dominated by the deterministic growth of the unstable mode, in both quasi-two-dimensional (Hele-Shaw) and fully three-dimensional geometries used in typical shadowgraph experiments.

  16. Plate rotation during continental collision and its relationship with the exhumation of UHP metamorphic terranes: Application to the Norwegian Caledonides

    NASA Astrophysics Data System (ADS)

    Bottrill, A. D.; van Hunen, J.; Cuthbert, S. J.; Brueckner, H. K.; Allen, M. B.

    2014-05-01

    variation and asynchronous onset of collision during the convergence of continents can significantly affect the burial and exhumation of subducted continental crust. Here we use 3-D numerical models for continental collision to discuss how deep burial and exhumation of high and ultrahigh pressure metamorphic (HP/UHP) rocks are enhanced by diachronous collision and the resulting rotation of the colliding plates. Rotation during collision locally favors eduction, the inversion of the subduction, and may explain the discontinuous distribution of ultra-high pressure (UHP) terranes along collision zones. For example, the terminal (Scandian) collision of Baltica and Laurentia, which formed the Scandinavian Caledonides, resulted in the exhumation of only one large HP/UHP terrane, the Western Gneiss Complex (WGC), near the southern end of the collision zone. Rotation of the subducting Baltica plate during collision may provide an explanation for this distribution. We explore this hypothesis by comparing orthogonal and diachronous collision models and conclude that a diachronous collision can transport continental material up to 60 km deeper, and heat material up to 300°C hotter, than an orthogonal collision. Our diachronous collision model predicts that subducted continental margin material returns to the surface only in the region where collision initiated. The diachronous collision model is consistent with petrological and geochonological observations from the WGC and makes predictions for the general evolution of the Scandinavian Caledonides. We propose the collision between Laurentia and Baltica started at the southern end of the collisional zone, and propagated northward. This asymmetric geometry resulted in the counter clockwise rotation of Baltica with respect to Laurentia, consistent with paleomagnetic data from other studies. Our model may have applications to other orogens with regional UHP terranes, such as the Dabie Shan and Papua New Guinea cases, where block

  17. Onset of radial flow in p+p collisions

    SciTech Connect

    Jiang, Kun; Zhu, Yinying; Liu, Weitao; Chen, Hongfang; Li, Cheng; Ruan, Lijuan; Tang, Zebo; Xu, Zhangbu

    2015-02-23

    It has been debated for decades whether hadrons emerging from p+p collisions exhibit collective expansion. The signal of the collective motion in p+p collisions is not as clear as in heavy-ion collisions because of the low multiplicity and large fluctuation in p+p collisions. Tsallis Blast-Wave (TBW) model is a thermodynamic approach, introduced to handle the overwhelming correlation and fluctuation in the hadronic processes. We have systematically studied the identified particle spectra in p+p collisions from RHIC to LHC using TBW and found no appreciable radial flow in p+p collisions below √s = 900 GeV. At LHC higher energy of 7 TeV in p+p collisions, the radial flow velocity achieves an average of (β) = 0.320 ± 0.005. This flow velocity is comparable to that in peripheral (40-60%) Au+Au collisions at RHIC. In addition, breaking of the identified particle spectra mT scaling was also observed at LHC from a model independent test.

  18. Mode-by-mode fluid dynamics for relativistic heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Floerchinger, Stefan; Wiedemann, Urs Achim

    2014-01-01

    We propose to study the fluid dynamic propagation of fluctuations in relativistic heavy ion collisions differentially with respect to their azimuthal, radial and longitudinal wavelength. To this end, we introduce a background-fluctuation splitting and a Bessel-Fourier decomposition of the fluctuating modes. We demonstrate how the fluid dynamic evolution of realistic events can be built up from the propagation of individual modes. We describe the main elements of this mode-by-mode fluid dynamics, and we discuss its use in the fluid dynamic analysis of heavy ion collisions. As a first illustration, we quantify to what extent only fluctuations of sufficiently large radial wave length contribute to harmonic flow coefficients. We find that fluctuations of short wave length are suppressed not only due to larger dissipative effects, but also due to a geometrical averaging over the freeze-out hyper-surface. In this way, our study further substantiates the picture that harmonic flow coefficients give access to a coarse-grained version of the initial conditions for heavy ion collisions, only.

  19. Fluctuating Hydrodynamics Confronts the Rapidity Dependence of Transverse Momentum Fluctuations

    NASA Astrophysics Data System (ADS)

    Pokharel, Rajendra; Gavin, Sean; Moschelli, George

    2012-10-01

    Interest in the development of the theory of fluctuating hydrodynamics is growing [1]. Early efforts suggested that viscous diffusion broadens the rapidity dependence of transverse momentum correlations [2]. That work stimulated an experimental analysis by STAR [3]. We attack this new data along two fronts. First, we compute STAR's fluctuation observable using the NeXSPheRIO code, which combines fluctuating initial conditions from a string fragmentation model with deterministic viscosity-free hydrodynamic evolution. We find that NeXSPheRIO produces a longitudinal narrowing, in contrast to the data. Second, we study the hydrodynamic evolution using second order causal viscous hydrodynamics including Langevin noise. We obtain a deterministic evolution equation for the transverse momentum density correlation function. We use the latest theoretical equations of state and transport coefficients to compute STAR's observable. The results are in excellent accord with the measured broadening. In addition, we predict features of the distribution that can distinguish 2nd and 1st order diffusion. [4pt] [1] J. Kapusta, B. Mueller, M. Stephanov, arXiv:1112.6405 [nucl-th].[0pt] [2] S. Gavin and M. Abdel-Aziz, Phys. Rev. Lett. 97, 162302 (2006)[0pt] [3] H. Agakishiev et al., STAR, STAR, Phys. Lett. B704

  20. Collision Avoidance System

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Ames Research Center teamed with the Federal Aviation Administration (FAA) to study human performance factors associated with the use of the Traffic Alert and Collision Avoidance system (TCAS II) in an operational environment. TCAS is designed to alert pilots of the presence of other aircraft in their vicinity, to identify and track those who could be a threat, and to recommend action to avoid a collision. Ames conducted three laboratory experiments. The first showed that pilots were able to use the TCAS II correctly in the allowable time. The second tested pilots' response to changes in the avoidance advisories, and the third examined pilots' reactions to alternative displays. After a 1989 congressional mandate, the FAA ruled that TCAS would be required on all passenger carrying aircraft (to be phased in completely by 1995).

  1. Interaction of dust-ion acoustic solitary waves in nonplanar geometry with electrons featuring Tsallis distribution

    SciTech Connect

    Narayan Ghosh, Uday; Chatterjee, Prasanta; Tribeche, Mouloud

    2012-11-15

    The head-on collisions between nonplanar dust-ion acoustic solitary waves are dealt with by an extended version of Poincare-Lighthill-Kuo perturbation method, for a plasma having stationary dust grains, inertial ions, and nonextensive electrons. The nonplanar geometry modified analytical phase-shift after a head-on collision is derived. It is found that as the nonextensive character of the electrons becomes important, the phase-shift decreases monotonically before levelling-off at a constant value. This leads us to think that nonextensivity may have a stabilizing effect on the phase-shift.

  2. Cosmic bubble and domain wall instabilities I: parametric amplification of linear fluctuations

    SciTech Connect

    Braden, Jonathan; Bond, J. Richard; Mersini-Houghton, Laura

    2015-03-03

    This is the first paper in a series where we study collisions of nucleated bubbles taking into account the effects of small initial (quantum) fluctuations in a fully 3+1-dimensional setting. In this paper, we consider the evolution of linear fluctuations around highly symmetric though inhomogeneous backgrounds. In particular, we demonstrate that a large degree of asymmetry develops over time from tiny initial fluctuations superposed upon planar and SO(2,1) symmetric backgrounds. These fluctuations are inevitable consequences of zero-point vacuum oscillations, so excluding them by enforcing a high degree of spatial symmetry is inconsistent in a quantum treatment. To simplify the analysis we consider the limit of two colliding planar walls, with mode functions for the fluctuations characterized by the wavenumber transverse to the collision direction and a longitudinal shape along the collision direction x, which we solve for. In the linear regime, the fluctuations obey a linear wave equation with a time- and space-dependent mass m{sub eff}(x,t). In situations where the walls collide multiple times, m{sub eff} oscillates in time. We use Floquet theory to study the evolution of the fluctuations and generalize the calculations familiar from the preheating literature to the case with many coupled degrees of freedom. The inhomogeneous case has bands of unstable transverse wavenumbers k{sub ⊥} whose corresponding mode functions grow exponentially. By examining the detailed spatial structure of the mode functions in x, we identify both broad and narrow parametric resonance generalizations of the homogeneous m{sub eff}(t) case of preheating. The unstable k{sub ⊥} modes are longitudinally localized, yet can be described as quasiparticles in the Bogoliubov sense. We define an effective occupation number and show they are created in bursts for the case of well-defined collisions in the background. The transverse-longitudinal coupling accompanying nonlinearity radically

  3. Chromodynamic fluctuations in quark-gluon plasma

    SciTech Connect

    Mrowczynski, Stanislaw

    2008-05-15

    Fluctuations of chromodynamic fields in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average colorless, stationary, and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long-time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum which is provided by the fluctuation-dissipation relation. Fluctuations in the unstable plasma, where the memory of initial fluctuations is not lost, are also discussed.

  4. A Look at Heavy Ion Collisions Through the SO(3)-Invariant Flow

    NASA Astrophysics Data System (ADS)

    Staig Fernandez, Maria del Pilar

    One of the measurements obtained from heavy ion collisions is the correlation between two final particles as a function of the difference of azimuthal angle and pseudorapidity. These correlations show structure in the azimuthal direction that is elongated in pseudorapidity, and that has its origin in the initial state after the collision, and in its evolution. We implemented a Glauber Monte Carlo code to study initial state fluctuations that appear on an event by event basis because of the random positions of the nucleons in the nuclei. We calculated the initial average deformations and their fluctuations as a function of the centrality of the collision and found that for central collisions all of the asymmetry parameters are on equal footing, but that as the collisions become more peripheral the second asymmetry parameter becomes more important, because of the almond-like shape of the region where the two nuclei intersect. To study the evolution of the matter created after the collision we used the SO(3)-invariant flow developed by S. Gubser and A. Yarom, that is an extension of Bjorken flow that includes flow in the radial direction. The hydrodynamic equations including perturbations to this background can be solved analytically in terms of known special functions that can be collected to describe the shape of a specific perturbation. We used as initial condition a Gaussian perturbation, and found that the two particle correlation obtained resembles the curve from experiments. We also explored the effects of viscosity on the final particle correlation, and on the spectra of the flow coefficients, and found that viscosity kills the higher harmonics. The same method can be used to study other perturbations to the background. In particular, we studied fluctuations that appear near the critical temperature produced by Quark Gluon Plasma clusters undergoing a Rayleigh type collapse, and suggest that the observed widening in rapidity correlations may be an indication

  5. Hydrogen-antihydrogen collisions

    PubMed

    Froelich; Jonsell; Saenz; Zygelman; Dalgarno

    2000-05-15

    Matter-antimatter interactions are investigated using hydrogen-antihydrogen collisions as an example. Cross sections for elastic scattering and for the antihydrogen loss (either through the rearrangement reaction, resulting in formation of protonium and positronium according to H+&Hmacr;-->p&pmacr;+e(+)e(-), or via annihilation in flight) are calculated for the first time in a fully quantum mechanical approach. Implications for experiments intending to trap and cool antihydrogen are discussed.

  6. Operational Collision Avoidance

    NASA Technical Reports Server (NTRS)

    Guit, Bill

    2015-01-01

    This presentation will describe the early days of the EOS Aqua and Aura operational collision avoidance process. It will highlight EOS debris avoidance maneuvers, EOS high interest event statistic and A-Train systematic conjunctions and conclude with future challenges. This is related to earlier e-DAA (tracking number 21692) that an abstract was submitted to a different conference. Eric Moyer, ESMO Deputy Project Manager has reviewed and approved this presentation on May 6, 2015

  7. Torqued fireballs in relativistic heavy-ion collisions

    SciTech Connect

    Bozek, Piotr; Broniowski, Wojciech; Moreira, Joao

    2011-03-15

    We show that the fluctuations in the wounded-nucleon model of the initial stage of relativistic heavy-ion collisions, together with the natural assumption that the forward- (backward-) moving wounded nucleons emit particles preferably in the forward (backward) direction, lead to an event-by-event torqued fireball. The principal axes associated with the transverse shape are rotated in the forward region in the opposite direction than in the backward region. On the average, the standard deviation of the relative torque angle between the forward and backward rapidity regions is {approx}20 deg. for the central and 10 deg. for the midperipheral collisions. The hydrodynamic expansion of a torqued fireball leads to a torqued collective flow, yielding, in turn, torqued principal axes of the transverse-momentum distributions at different rapidities. We propose experimental measures, based on cumulants involving particles in different rapidity regions, which should allow for a quantitative determination of the effect from the data. To estimate the nonflow contributions from resonance decays we run Monte Carlo simulations with therminator, a thermal heavy-ion generator. If the event-by-event torque effect is found in the data, it will support the assumptions concerning the fluctuations in the early stage of the fireball formation, as well as the hypothesis of the asymmetric rapidity shape of the emission functions of the moving sources in the nucleus-nucleus collisions.

  8. Neogene-Quaternary eustasy and collision tectonism in western Taiwan

    SciTech Connect

    Teng, L.S. )

    1991-03-01

    Taiwan is an active orogen formed by the collision between the Luzon arc and the Asian continent. Thick late Cenozoic coastal to shallow marine deposits exposed in the western foothills of western Taiwan preserved the sedimentary record of both tectonic and eustatic influences. Relating to the arc-continent collision, the Oligocene-Miocene deposits can be regarded as the pre-collisional continental margin sequence and the Pliocene-Quaternary deposits as the post-collisional foreland basin sequence. Geohistory analysis shows that the rates of sediment accumulation and basin subsidence remained low during the Miocene but increased dramatically during the Pliocene-Quaternary, reflecting the effects of exacerbated loading and unroofing of the growing orogen. In spite of the intense tectonic influence, facies variations in both the continental margin sequence and the foreland basin sequence are chronostratigraphically consistent with global eustatic fluctuations. It appears that eustatic fluctuations were able to leave a distinct signature in stratigraphic records regardless of the effects of collision tectonics.

  9. Two-body nucleon-nucleon correlations in Glauber models of relativistic heavy-ion collisions

    SciTech Connect

    Broniowski, Wojciech; Rybczynski, Maciej

    2010-06-15

    We investigate the influence of the central two-body nucleon-nucleon correlations on several quantities observed in relativistic heavy-ion collisions. It is demonstrated with explicit Monte Carlo simulations that the basic correlation measures observed in relativistic heavy-ion collisions, such as the fluctuations of participant eccentricity, initial size fluctuations, or the fluctuations of the number of sources producing particles, are all sensitive to the inclusion of the two-body correlations. The effect is at the level of about 10-20%. Moreover, the realistic (Gaussian) correlation function gives indistinguishable results from the hard-core repulsion, with the expulsion distance set to 0.9 fm. Thus, we verify that for investigations of the considered correlation measures, it is sufficient to use the Monte Carlo generators accounting for the hard-core repulsion.

  10. Strain Functionals for Characterizing Atomistic Geometries

    NASA Astrophysics Data System (ADS)

    Kober, Edward; Rudin, Sven

    The development of a set of strain tensor functionals that are capable of characterizing arbitrarily ordered atomistic structures is described. This approach defines a Gaussian-weighted neighborhood around each atom and characterizes that local geometry in terms of n-th order strain tensors, which are equivalent to the moments of the neighborhood. Fourth order expansions can distinguish the cubic structures (and deformations thereof), but sixth order expansions are required to fully characterize hexagonal structures. Other methods used to characterize atomic structures, such as the Steinhardt parameters or the centrosymmetry metric, can be derived from this more general approach. These functions are continuous and smooth and much less sensitive to thermal fluctuations than other descriptors based on discrete neighborhoods. They allow material phases, deformations, and a large number of defect structures to be readily identified and classified. Applications to the analysis of shock-loaded samples of Cu, Ta and Ti will be presented. This strain functional basis can also then be used for developing interatomic potential functions, and an initial application to Cu will be presented.

  11. Density Fluctuations in Liquid Water

    NASA Astrophysics Data System (ADS)

    English, Niall J.; Tse, John S.

    2011-01-01

    The density distributions and fluctuations in grids of varying size in liquid water at ambient pressure, both above the freezing point and in the supercooled state, are analyzed from the trajectories obtained from large-scale molecular dynamics simulations. It is found that the occurrence of low- and high-density regions (LDL and HDL) is transient and their respective residence times are dependent on the size of the simulated system. The spatial extent of density-density correlation is found to be within 7 Å or less. The temporal existence of LDL and HDL arises as a result of natural density fluctuations of an equilibrium system. The density of bulk water at ambient conditions is homogenous.

  12. Algorithm refinement for fluctuating hydrodynamics

    SciTech Connect

    Williams, Sarah A.; Bell, John B.; Garcia, Alejandro L.

    2007-07-03

    This paper introduces an adaptive mesh and algorithmrefinement method for fluctuating hydrodynamics. This particle-continuumhybrid simulates the dynamics of a compressible fluid with thermalfluctuations. The particle algorithm is direct simulation Monte Carlo(DSMC), a molecular-level scheme based on the Boltzmann equation. Thecontinuum algorithm is based on the Landau-Lifshitz Navier-Stokes (LLNS)equations, which incorporate thermal fluctuations into macroscopichydrodynamics by using stochastic fluxes. It uses a recently-developedsolver for LLNS, based on third-order Runge-Kutta. We present numericaltests of systems in and out of equilibrium, including time-dependentsystems, and demonstrate dynamic adaptive refinement by the computationof a moving shock wave. Mean system behavior and second moment statisticsof our simulations match theoretical values and benchmarks well. We findthat particular attention should be paid to the spectrum of the flux atthe interface between the particle and continuum methods, specificallyfor the non-hydrodynamic (kinetic) time scales.

  13. Random numbers from vacuum fluctuations

    NASA Astrophysics Data System (ADS)

    Shi, Yicheng; Chng, Brenda; Kurtsiefer, Christian

    2016-07-01

    We implement a quantum random number generator based on a balanced homodyne measurement of vacuum fluctuations of the electromagnetic field. The digitized signal is directly processed with a fast randomness extraction scheme based on a linear feedback shift register. The random bit stream is continuously read in a computer at a rate of about 480 Mbit/s and passes an extended test suite for random numbers.

  14. Facing rim cavities fluctuation modes

    NASA Astrophysics Data System (ADS)

    Casalino, Damiano; Ribeiro, André F. P.; Fares, Ehab

    2014-06-01

    Cavity modes taking place in the rims of two opposite wheels are investigated through Lattice-Boltzmann CFD simulations. Based on previous observations carried out by the authors during the BANC-II/LAGOON landing gear aeroacoustic study, a resonance mode can take place in the volume between the wheels of a two-wheel landing gear, involving a coupling between shear-layer vortical fluctuations and acoustic modes resulting from the combination of round cavity modes and wheel-to-wheel transversal acoustic modes. As a result, side force fluctuations and tonal noise side radiation take place. A parametric study of the cavity mode properties is carried out in the present work by varying the distance between the wheels. Moreover, the effects due to the presence of the axle are investigated by removing the axle from the two-wheel assembly. The azimuthal properties of the modes are scrutinized by filtering the unsteady flow in narrow bands around the tonal frequencies and investigating the azimuthal structure of the filtered fluctuation modes. Estimation of the tone frequencies with an ad hoc proposed analytical formula confirms the observed modal properties of the filtered unsteady flow solutions. The present study constitutes a primary step in the description of facing rim cavity modes as a possible source of landing gear tonal noise.

  15. Earthquake cycles in complex geometries

    NASA Astrophysics Data System (ADS)

    Romanet, Pierre; Bhat, Harsha; Madariaga, Raul

    2016-04-01

    Our understanding of earthquake cycles, from a modelling perspective, comes mainly from theoretical, and numerical, work on a single straight fault. However, natural fault systems are geometrically complex. Modelling complex fault geometry (bends, kinks and multiple faults) is in itself a challenge as it is computationally intensive. To overcome this difficulty, we appeal to the Fast Multipole Method which was developed in the context of modelling N-body problems. This method is then used to model the quasi-dynamic response of multiple faults, with complex geometries, that are governed by rate and state friction laws. Our preliminary findings tell us that when stress interaction between faults, due to complex geometry, is accounted then even strongly rate-weakening faults (a-b)<0 show a complex spectrum of slow slip and dynamic ruptures.

  16. Conventionalism and integrable Weyl geometry

    NASA Astrophysics Data System (ADS)

    Pucheu, M. L.

    2015-03-01

    Since the appearance of Einstein's general relativity, gravitation has been associated to the space-time curvature. This theory introduced a geometrodynamic language which became a convenient tool to predict matter behaviour. However, the properties of space-time itself cannot be measurable by experiments. Taking Poincaré idea that the geometry of space-time is merely a convention, we show that the general theory of relativity can be completely reformulated in a more general setting, a generalization of Riemannian geometry, namely, the Weyl integrable geometry. The choice of this new mathematical language implies, among other things, that the path of particles and light rays should now correspond to Weylian geodesies. Such modification in the dynamic of bodies brings a new perception of physical phenomena that we will explore.

  17. Frustrated Order on Extrinsic Geometries

    SciTech Connect

    Mbanga, Badel L.; Grason, Gregory M.; Santangelo, Christian D.

    2012-01-03

    We study, numerically and theoretically, defects in an anisotropic liquid that couple to the extrinsic geometry of a surface. Though the intrinsic geometry tends to confine topological defects to regions of large Gaussian curvature, extrinsic couplings tend to orient the order along the local direction of maximum or minimum bending. This additional frustration is generically unavoidable, and leads to complex ground-state thermodynamics. Using the catenoid as a prototype, we show, in contradistinction to the well-known effects of intrinsic geometry, that extrinsic curvature expels disclinations from the region of maximum curvature above a critical coupling threshold. On catenoids lacking an “inside-outside” symmetry, defects are expelled altogether above a critical neck size.

  18. Quantum geometry and gravitational entropy

    SciTech Connect

    Simon, Joan; Balasubramanian, Vijay; Czech, Bart Iomiej; Larjo, Klaus; Marolf, Donald; Simon, Joan

    2007-05-29

    Most quantum states have wavefunctions that are widely spread over the accessible Hilbert space and hence do not have a good description in terms of a single classical geometry. In order to understand when geometric descriptions are possible, we exploit the AdS/CFT correspondence in the half-BPS sector of asymptotically AdS_5 x S5 universes. In this sector we devise a"coarse-grained metric operator" whose eigenstates are well described by a single spacetime topology and geometry. We show that such half-BPS universes have a non-vanishing entropy if and only if the metric is singular, and that the entropy arises from coarse-graining the geometry. Finally, we use our entropy formula to find the most entropic spacetimes with fixed asymptotic moments beyond the global charges.

  19. Before They Were Plateaus: Views of Early Orogenesis from the Greater Caucasus in the Arabia-Eurasia Collision

    NASA Astrophysics Data System (ADS)

    Forte, A. M.; Cowgill, E.

    2012-12-01

    largely unaffected by coeval rapid exhumation of the GC. Instead, stratigraphy is strongly tied to base-level of the adjacent, internally drained Caspian Sea. The Caspian was isolated from the global ocean in the Pliocene as continued orogeny within the Arabia-Eurasia collision cut off marine pathways. Since isolation, Caspian base-level has independently been driven by variations in regional climate and runoff leading to non-linear fluctuations. We suggest that Caspian Sea level is the primary control on the GC foreland basin stratigraphic record and causes large (> 1 km) and rapid (~1-10 kyr) base-level changes. Results from the GC suggest that during progressive orogeny, collision of two smaller orogens can dramatically influence the structural geometry and morphology of orogenic systems. As water bodies in foreland basins are disconnected from the ocean, their base-level becomes tied to regional climate, can be chaotic, and can exert primary control on the stratigraphy of the foreland basin. In such a scenario, the base-level component will dominate the stratigraphic record, making it difficult to identify and tease out tectonic signals. Examination of how these processes alter both the structural geometry of a young orogenic system and the preservation potential of these changes in marginal basin stratigraphy provides key glimpses of early stages of plateau formation.

  20. Cosmic bubble and domain wall instabilities III: the role of oscillons in three-dimensional bubble collisions

    SciTech Connect

    Bond, J. Richard; Braden, Jonathan; Mersini-Houghton, Laura E-mail: j.braden@ucl.ac.uk

    2015-09-01

    We study collisions between pairs of bubbles nucleated in an ambient false vacuum. For the first time, we include the effects of small initial (quantum) fluctuations around the instanton profiles describing the most likely initial bubble profile. Past studies of this problem neglect these fluctuations and work under the assumption that the collisions posess an exact SO(2,1) symmetry. We use three-dimensional lattice simulations to demonstrate that for double-well potentials, small initial perturbations to this symmetry can be amplified as the system evolves. Initially the amplification is well-described by linear perturbation theory around the SO(2,1) background, but the onset of strong nonlinearities amongst the fluctuations quickly leads to a drastic breaking of the original SO(2,1) symmetry and the production of oscillons in the collision region. We explore several single-field models, and we find it is hard to both realize inflation inside of a bubble and produce oscillons in a collision. Finally, we extend our results to a simple two-field model. The additional freedom allowed by the second field allows us to construct viable inflationary models that allow oscillon production in collisions. The breaking of the SO(2,1) symmetry allows for a new class of observational signatures from bubble collisions that do not posess azimuthal symmetry, including the production of gravitational waves which cannot be supported by an SO(2,1) spacetime.

  1. RSRM Propellant Grain Geometry Modification

    NASA Technical Reports Server (NTRS)

    Schorr, Andrew A.; Endicott, Joni B.; McCool, Alex (Technical Monitor)

    2000-01-01

    This document is composed of viewgraphs about the RSRM propellant grain geometry modification project, which hopes to improve personnel and system safety by modifying propellant grain geometry to improve structural factors of safety. Using techniques such as Finite Element Analysis to determine blend radii required to reduce localized stresses, and ballistic predictions to ensure that the ballistics, ignition transient and Block Model have not been adversely affected, the project hopes to build and test FSM-10 with a new design, and determine flight effectivity pending successful test evaluation.

  2. Geometry, topology, and string theory

    SciTech Connect

    Varadarajan, Uday

    2003-07-10

    A variety of scenarios are considered which shed light upon the uses and limitations of classical geometric and topological notions in string theory. The primary focus is on situations in which D-brane or string probes of a given classical space-time see the geometry quite differently than one might naively expect. In particular, situations in which extra dimensions, non-commutative geometries as well as other non-local structures emerge are explored in detail. Further, a preliminary exploration of such issues in Lorentzian space-times with non-trivial causal structures within string theory is initiated.

  3. Geometry of generalized depolarizing channels

    SciTech Connect

    Burrell, Christian K.

    2009-10-15

    A generalized depolarizing channel acts on an N-dimensional quantum system to compress the 'Bloch ball' in N{sup 2}-1 directions; it has a corresponding compression vector. We investigate the geometry of these compression vectors and prove a conjecture of Dixit and Sudarshan [Phys. Rev. A 78, 032308 (2008)], namely, that when N=2{sup d} (i.e., the system consists of d qubits), and we work in the Pauli basis then the set of all compression vectors forms a simplex. We extend this result by investigating the geometry in other bases; in particular we find precisely when the set of all compression vectors forms a simplex.

  4. Catching Collisions in the LHC

    ScienceCinema

    Fruguiele, Claudia; Hirschauer, Jim

    2016-07-12

    Now that the Large Hadron Collider has officially turned back on for its second run, within every proton collision could emerge the next new discovery in particle physics. Learn how the detectors on the Compact Muon Solenoid, or CMS, experiment capture and track particles as they are expelled from a collision. Talking us through these collisions are Claudia Fruguiele and Jim Hirschauer of Fermi National Accelerator Laboratory, the largest U.S. institution collaborating on the LHC.

  5. Catching Collisions in the LHC

    SciTech Connect

    Fruguiele, Claudia; Hirschauer, Jim

    2015-06-16

    Now that the Large Hadron Collider has officially turned back on for its second run, within every proton collision could emerge the next new discovery in particle physics. Learn how the detectors on the Compact Muon Solenoid, or CMS, experiment capture and track particles as they are expelled from a collision. Talking us through these collisions are Claudia Fruguiele and Jim Hirschauer of Fermi National Accelerator Laboratory, the largest U.S. institution collaborating on the LHC.

  6. Collision-induced dissociation of fluoropyridinide anions

    NASA Astrophysics Data System (ADS)

    Kato, Shuji; Lineberger, W. Carl; Bierbaum, Veronica M.

    2007-10-01

    Collision-induced dissociation of ortho-fluoro, meta-fluoro, and 2,6-difluoropyridinide anions are studied using the selected ion flow tube technique. Structures and energetics of the reactants, transition states, and products are calculated at the MP4(SDQ)/6-31 + G(d) level of theory based on the B3LYP/6-311++G(d,p) and/or MP2/6-31 + G(d) optimized geometries. The monofluoropyridinide anions (C5NH3F-) dissociate almost exclusively via loss of an HF molecule, i.e., C5NH2- + HF at low collision energies, in addition to loss of F- at higher energies. 2,6-Difluoropyridinide anions (C5NH2F2-) dissociate via successive loss of HF molecules to form C5NHF- then C5N- depending on the collision energy. The CID results strongly suggest formation of ring-intact pyridynide structures (C5NH2-, C5NHF-) with a bent triple bond embedded in the azine ring systems. Calculated reaction energy diagrams are totally consistent with the experimental observations. Didehydropyridynides C5NH2- and C5NHF- have substantial barriers to decomposition. Tetradehydropyridynide C5N- is a highly strained ring system and metastable with a predicted barrier of about 5 kcal mol-1 (20 kJ mol-1) toward ring-opening to a linear NCCCCC- structure. The observed C5N- species is most likely the linear anion under experimental conditions; however, the ring-intact C5N- pyridynide is a highly energetic species releasing about 80 kcal mol-1 (340 kJ mol-1) of energy upon the ring-opening.

  7. Current fluctuations in stochastic lattice gases.

    PubMed

    Bertini, L; De Sole, A; Gabrielli, D; Jona-Lasinio, G; Landim, C

    2005-01-28

    We study current fluctuations in lattice gases in the macroscopic limit extending the dynamic approach for density fluctuations developed in previous articles. More precisely, we establish a large deviation theory for the space-time fluctuations of the empirical current which include the previous results. We then estimate the probability of a fluctuation of the average current over a large time interval. It turns out that recent results by Bodineau and Derrida [Phys. Rev. Lett. 92, 180601 (2004)

  8. Plate rotation during continental collision and its relationship with the exhumation of UHP metamorphic terranes: application to the Norwegian Caledonides

    NASA Astrophysics Data System (ADS)

    Bottrill, Andrew; van Hunen, Jeroan; Cuthbert, Simon; Allen, Mark; Brueckner, Hannes

    2014-05-01

    Lateral variation and asynchronous onset of collision during the convergence of continents can significantly affect the burial and exhumation of subducting material. We use 3D numerical models for continental collision to discuss how deep burial and exhumation of ultra-high pressure metamorphic rocks are enhanced by oblique convergence and resulting rotation of the colliding plates. Rotation during collision locally favours eduction, the inversion of the subduction process following ocean slab break-off, and may relate to the discontinuous distribution of ultra-high pressure (UHP) terranes along collision zones. For example the terminal (Scandian) collision of Baltica and Laurentia, which formed the Scandinavian Caledonides resulted in the exhumation of only one large high pressure/ultra-high pressure (HP/UHP) terrane, the Western Gneiss Complex (WGC), near the southern end of the collision zone. Rotation of the subducting Baltica plate during collision may provide a likely explanation for this distribution. We explore this hypothesis by comparing orthogonal and oblique collision models and conclude that an oblique collision can transport continental material up to 60km deeper, and heat material up to 300°C hotter, than an orthogonal collision. Our oblique collision model predicts that subducted continental margin material returns to the surface only in the region where collision initiated. The oblique collision model is consistent with petrological and geochonological observations from the Western Gneiss Complex and makes predictions for the general evolution of the Scandinavian Caledonides. We propose the collision between Laurentia and Baltica started at the southern end of the collisional zone, and propagated northward. This asymmetric geometry resulted in the counter clockwise rotation of Baltica and the northwards movement of Baltica's rotational pole with respect to Laurentia, consistent with paleomagnetic data from other studies. Our model has applications

  9. Fractal dynamics of light scattering intensity fluctuation in disordered dusty plasmas

    SciTech Connect

    Safaai, S. S.; Muniandy, S. V.; Chew, W. X.; Asgari, H.; Yap, S. L.; Wong, C. S.

    2013-10-15

    Dynamic light scattering (DLS) technique is a simple and yet powerful technique for characterizing particle properties and dynamics in complex liquids and gases, including dusty plasmas. Intensity fluctuation in DLS experiments often studied using correlation analysis with assumption that the fluctuation is statistically stationary. In this study, the temporal variation of the nonstationary intensity fluctuation is analyzed directly to show the existence of fractal characteristics by employing wavelet scalogram approach. Wavelet based scale decomposition approach is used to separate non-scaling background noise (without dust) from scaling intensity fluctuation from dusty plasma. The Hurst exponents for light intensity fluctuation in dusty plasma at different neutral gas pressures are determined. At low pressures, weaker damping of dust motions via collisions with neutral gases results in stronger persistent behavior in the fluctuation of DLS time series. The fractal scaling Hurst exponent is demonstrated to be useful for characterizing structural phases in complex disordered dusty plasma, especially when particle configuration or sizes are highly inhomogeneous which makes the standard pair-correlation function difficult to interpret. The results from fractal analysis are compared with alternative interpretation of disorder based on approximate entropy and particle transport using mean square displacement.

  10. Identity method for particle number fluctuations and correlations

    SciTech Connect

    Gorenstein, M. I.

    2011-08-15

    An incomplete particle identification distorts the observed event-by-event fluctuations of the hadron chemical composition in nucleus-nucleus collisions. A new experimental technique called the identity method was recently proposed. It eliminated the misidentification problem for one specific combination of the second moments in a system of two hadron species. In the present paper, this method is extended to calculate all the second moments in a system with an arbitrary number of hadron species. Special linear combinations of the second moments are introduced. These combinations are presented in terms of single-particle variables and can be found experimentally from the event-by-event averaging. The mathematical problem is then reduced to solving a system of linear equations. The effect of incomplete particle identification is fully eliminated from the final results.

  11. Fluctuations of doublet splittings using the annular billiard

    SciTech Connect

    Egydio de Carvalho, R.; Mijolaro, A.P.

    2004-11-01

    We study the statistical distribution of quantum energy splittings due to a dynamical tunneling. The system, the annular billiard, has whispering quasimodes due to a discrete symmetry that exists even when chaos is present in the underlying classical dynamics. Symmetric and antisymmetric combinations of these quasimodes correspond to quantum doublet states whose degeneracies decrease as the circles become more eccentric. We construct numerical ensembles composed of splittings for two distinct regimes, one which we call semiclassical for high quantum numbers and high energies where the whispering regions are connected by chaos, and other which we call quantal for low quantum numbers, low energies, and near integrable where dynamical tunneling is not a dominant mechanism. In both cases we observe a variation on the fluctuation amplitudes, but their mean behaviors follow the formula of Leyvraz and Ullmo [J. Phys. A 29, 2529 (1996)]. A description of a three-level collision involving a doublet and a singlet is also provided through a numerical example.

  12. Magnetic Shift of the Chemical Freeze-out and Electric Charge Fluctuations.

    PubMed

    Fukushima, Kenji; Hidaka, Yoshimasa

    2016-09-01

    We discuss the effect of a strong magnetic field on the chemical freeze-out points in ultrarelativistic heavy-ion collisions. As a result of inverse magnetic catalysis or magnetic inhibition, the crossover onset to hot and dense matter out of quarks and gluons should be shifted to a lower temperature. To quantify this shift we employ the hadron resonance gas model and an empirical condition for the chemical freeze-out. We point out that the charged particle abundances are significantly affected by the magnetic field so that the electric charge fluctuation is largely enhanced, especially at high baryon density. The charge conservation partially cancels the enhancement, but our calculation shows that the electric charge fluctuation could serve as a magnetometer. We find that the fluctuation exhibits a crossover behavior rapidly increased for eB≳(0.4  GeV)^{2}, while the charge chemical potential has smoother behavior with an increasing magnetic field. PMID:27636469

  13. Magnetic Shift of the Chemical Freeze-out and Electric Charge Fluctuations

    NASA Astrophysics Data System (ADS)

    Fukushima, Kenji; Hidaka, Yoshimasa

    2016-09-01

    We discuss the effect of a strong magnetic field on the chemical freeze-out points in ultrarelativistic heavy-ion collisions. As a result of inverse magnetic catalysis or magnetic inhibition, the crossover onset to hot and dense matter out of quarks and gluons should be shifted to a lower temperature. To quantify this shift we employ the hadron resonance gas model and an empirical condition for the chemical freeze-out. We point out that the charged particle abundances are significantly affected by the magnetic field so that the electric charge fluctuation is largely enhanced, especially at high baryon density. The charge conservation partially cancels the enhancement, but our calculation shows that the electric charge fluctuation could serve as a magnetometer. We find that the fluctuation exhibits a crossover behavior rapidly increased for e B ≳(0.4 GeV )2, while the charge chemical potential has smoother behavior with an increasing magnetic field.

  14. Signatures of α clustering in light nuclei from relativistic nuclear collisions.

    PubMed

    Broniowski, Wojciech; Ruiz Arriola, Enrique

    2014-03-21

    We argue that relativistic nuclear collisions may provide experimental evidence of α clustering in light nuclei. A light α-clustered nucleus has a large intrinsic deformation. When collided against a heavy nucleus at very high energies, this deformation transforms into the deformation of the fireball in the transverse plane. The subsequent collective evolution of the fireball leads to harmonic flow reflecting the deformation of the initial shape, which can be measured with standard methods of relativistic heavy-ion collisions. We illustrate the feasibility of the idea by modeling the (12)C-(208)Pb collisions and point out that very significant quantitative and qualitative differences between the α-clustered and uniform (12)C nucleus occur in such quantities as the triangular flow, its event-by-event fluctuations, or the correlations of the elliptic and triangular flows. The proposal offers a possibility of studying low-energy nuclear structure phenomena with "snapshots" made with relativistic heavy-ion collisions.

  15. Charge-dependent azimuthal correlations of secondary particles in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Okorokov, V.; Parfenov, P.

    2016-02-01

    The P/CP symmetry breaking in quantum chromodynamics (QCD) could be realized via transitions between local fluctuations of gauge fields. Azimuthal correlations which characterize the asymmetry of the emitted charged particles with respect to the reaction plane in non-central nucleus-nucleus collisions are the promising tools for experimental study of local P/CP violation in the strong interactions. The preliminary estimations of correlators within the model of chiral magnetic effect are presented for types of nuclei and collision energies corresponded to RHIC and the LHC beams for two various nuclear densities, namely, for approach of the hard sphere and for the two-component Fermi model. Besides of the correlator estimations for the symmetric collisions, the preliminary results for magnetic field in asymmetric Cu + Au collisions are also shown.

  16. Single particle momentum and angular distributions in hadron-hadron collisions at ultrahigh energies

    NASA Technical Reports Server (NTRS)

    Chou, T. T.; Chen, N. Y.

    1985-01-01

    The forward-backward charged multiplicity distribution (P n sub F, n sub B) of events in the 540 GeV antiproton-proton collider has been extensively studied by the UA5 Collaboration. It was pointed out that the distribution with respect to n = n sub F + n sub B satisfies approximate KNO scaling and that with respect to Z = n sub F - n sub B is binomial. The geometrical model of hadron-hadron collision interprets the large multiplicity fluctuation as due to the widely different nature of collisions at different impact parameters b. For a single impact parameter b, the collision in the geometrical model should exhibit stochastic behavior. This separation of the stochastic and nonstochastic (KNO) aspects of multiparticle production processes gives conceptually a lucid and attractive picture of such collisions, leading to the concept of partition temperature T sub p and the single particle momentum spectrum to be discussed in detail.

  17. Scaling of fluctuations in a trapped binary condensate

    NASA Astrophysics Data System (ADS)

    Bisset, R. N.; Wilson, R. M.; Ticknor, C.

    2015-05-01

    We demonstrate that measurements of number fluctuations within finite cells provide a direct means to study susceptibility scaling in a trapped two-component Bose-Einstein condensate. This system supports a second-order phase transition between miscible (cospatial) and immiscible (symmetry-broken) states that is driven by a diverging susceptibility to magnetic fluctuations. As the transition is approached from the miscible side the magnetic susceptibility is found to depend strongly on the geometry and orientation of the observation cell. However, a scaling exponent consistent with that for the homogenous gas (γ =1 ) can be recovered, for all cells considered, as long as the fit excludes the region in the immediate vicinity of the critical point. As the transition is approached from the immiscible side, the magnetic fluctuations exhibit a nontrivial scaling exponent γ ≃1.30 . Interestingly, on both sides of the transition, we find it best to extract the exponents using an observation cell that encompasses half of the trapped system. This implies that relatively low-resolution in situ imaging will be sufficient for the investigation of these exponents. We also investigate the gap energy and find exponents ν z =0.505 on the miscible side and, unexpectedly, ν z =0.60 (3) for the immiscible phase.

  18. Rotation shear induced fluctuation decorrelation in a toroidal plasma

    SciTech Connect

    Hahm, T.S.

    1994-06-01

    The enhanced decorrelation of fluctuations by the combined effects of the E {times} B flow (V{sub E}) shear, the parallel flow (V{sub {parallel}}) shear, and the magnetic shear is studied in toroidal geometry. A two-point nonlinear analysis previously utilized in a cylindrical model shows that the reduction of the radial correlation length below its ambient turbulence value ({Delta}r{sub 0}) is characterized by the ratio between the shearing rate {omega}{sub s} and the ambient turbulence scattering rate {Delta}{omega}{sub T}. The derived shearing rate is given by {omega}{sub s}{sup 2} = ({Delta}r{sub 0}){sup 2}[1/{Delta}{phi}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(qV{sub E}/r){r_brace}{sup 2} + 1/{Delta}{eta}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(V{parallel}/qR){r_brace}{sup 2}], where {Delta}{phi} and {Delta}{eta} are the correlation angles of the ambient turbulence along the toroidal and parallel directions. This result deviates significantly from the cylindrical result for high magnetic shear or for ballooning-like fluctuations. For suppression of flute-like fluctuations, only the radial shear of qV{sub E}/r contributes, and the radial shear of V{parallel}/qR is irrelevant regardless of the plasma rotation direction.

  19. Cosmological implications of modified gravity induced by quantum metric fluctuations

    NASA Astrophysics Data System (ADS)

    Liu, Xing; Harko, Tiberiu; Liang, Shi-Dong

    2016-08-01

    We investigate the cosmological implications of modified gravities induced by the quantum fluctuations of the gravitational metric. If the metric can be decomposed as the sum of the classical and of a fluctuating part, of quantum origin, then the corresponding Einstein quantum gravity generates at the classical level modified gravity models with a non-minimal coupling between geometry and matter. As a first step in our study, after assuming that the expectation value of the quantum correction can be generally expressed in terms of an arbitrary second order tensor constructed from the metric and from the thermodynamic quantities characterizing the matter content of the Universe, we derive the (classical) gravitational field equations in their general form. We analyze in detail the cosmological models obtained by assuming that the quantum correction tensor is given by the coupling of a scalar field and of a scalar function to the metric tensor, and by a term proportional to the matter energy-momentum tensor. For each considered model we obtain the gravitational field equations, and the generalized Friedmann equations for the case of a flat homogeneous and isotropic geometry. In some of these models the divergence of the matter energy-momentum tensor is non-zero, indicating a process of matter creation, which corresponds to an irreversible energy flow from the gravitational field to the matter fluid, and which is direct consequence of the non-minimal curvature-matter coupling. The cosmological evolution equations of these modified gravity models induced by the quantum fluctuations of the metric are investigated in detail by using both analytical and numerical methods, and it is shown that a large variety of cosmological models can be constructed, which, depending on the numerical values of the model parameters, can exhibit both accelerating and decelerating behaviors.

  20. Teaching Activity-Based Taxicab Geometry

    ERIC Educational Resources Information Center

    Ada, Tuba

    2013-01-01

    This study aimed on the process of teaching taxicab geometry, a non-Euclidean geometry that is easy to understand and similar to Euclidean geometry with its axiomatic structure. In this regard, several teaching activities were designed such as measuring taxicab distance, defining a taxicab circle, finding a geometric locus in taxicab geometry, and…

  1. Disoriented Chiral Condensates in High-Energy Nuclear Collisions

    SciTech Connect

    Randrup, Jorgen

    2000-10-18

    This brief lecture series discusses how our current understanding of chiral symmetry may be tested more globally in high-energy nuclear collisions by suitable extraction of pionic observables. After briefly recalling the general features of chiral symmetry, we focus on the SU(2) linear sigma model and show how a semi-classical mean-field treatment makes it possible to calculate its statistical properties, including the chiral phase diagram. Subsequently, we consider scenarios of relevance to high-energy collisions and discuss the features of the ensuing non-equilibrium dynamics and the associated characteristic signals. Finally, we illustrate how the presence of vacuum fluctuations or the inclusion of strangeness may affect the results quantitatively.

  2. LOGO Based Instruction in Geometry.

    ERIC Educational Resources Information Center

    Yusuf, Mian Muhammad

    The objective of this pretest-posttest Quasi-Experimental Design study was to determine the effects of LOGO Based Instruction (LBI) compared to instruction by teacher lecture and pencil-and-paper activities on: (1) students' understanding of the concepts of point, ray, line, and line segment; (2) students' attitudes toward learning geometry,…

  3. Exploring Bundling Theory with Geometry

    ERIC Educational Resources Information Center

    Eckalbar, John C.

    2006-01-01

    The author shows how instructors might successfully introduce students in principles and intermediate microeconomic theory classes to the topic of bundling (i.e., the selling of two or more goods as a package, rather than separately). It is surprising how much students can learn using only the tools of high school geometry. To be specific, one can…

  4. General Relativity: Geometry Meets Physics

    ERIC Educational Resources Information Center

    Thomsen, Dietrick E.

    1975-01-01

    Observing the relationship of general relativity and the geometry of space-time, the author questions whether the rest of physics has geometrical explanations. As a partial answer he discusses current research on subatomic particles employing geometric transformations, and cites the existence of geometrical definitions of physical quantities such…

  5. Teaching Geometry According to Euclid.

    ERIC Educational Resources Information Center

    Hartshorne, Robin

    2000-01-01

    This essay contains some reflections and questions arising from encounters with the text of Euclid's Elements. The reflections arise out of the teaching of a course in Euclidean and non-Euclidean geometry to undergraduates. It is concluded that teachers of such courses should read Euclid and ask questions, then teach a course on Euclid and later…

  6. Analogical Reasoning in Geometry Education

    ERIC Educational Resources Information Center

    Magdas, Ioana

    2015-01-01

    The analogical reasoning isn't used only in mathematics but also in everyday life. In this article we approach the analogical reasoning in Geometry Education. The novelty of this article is a classification of geometrical analogies by reasoning type and their exemplification. Our classification includes: analogies for understanding and setting a…

  7. Foucault pendulum through basic geometry

    NASA Astrophysics Data System (ADS)

    von Bergmann, Jens; von Bergmann, HsingChi

    2007-10-01

    We provide a thorough explanation of the Foucault pendulum that utilizes its underlying geometry on a level suitable for science students not necessarily familiar with calculus. We also explain how the geometrically understood Foucault pendulum can serve as a prototype for more advanced phenomena in physics known as Berry's phase or geometric phases.

  8. Spectral geometry of symplectic spinors

    NASA Astrophysics Data System (ADS)

    Vassilevich, Dmitri

    2015-10-01

    Symplectic spinors form an infinite-rank vector bundle. Dirac operators on this bundle were constructed recently by Habermann, K. ["The Dirac operator on symplectic spinors," Ann. Global Anal. Geom. 13, 155-168 (1995)]. Here we study the spectral geometry aspects of these operators. In particular, we define the associated distance function and compute the heat trace asymptotics.

  9. Exploring Fractal Geometry with Children.

    ERIC Educational Resources Information Center

    Vacc, Nancy Nesbitt

    1999-01-01

    Heightens the awareness of elementary school teachers, teacher educators, and teacher-education researchers of possible applications of fractal geometry with children and, subsequently, initiates discussion about the appropriateness of including this new mathematics in the elementary curriculum. Presents activities for exploring children's…

  10. Differential geometry meets the cell.

    PubMed

    Marshall, Wallace F

    2013-07-18

    A new study by Terasaki et al. highlights the role of physical forces in biological form by showing that connections between stacked endoplasmic reticulum cisternae have a shape well known in classical differential geometry, the helicoid, and that this shape is a predictable consequence of membrane physics.

  11. Instructional Identities of Geometry Students

    ERIC Educational Resources Information Center

    Aaron, Wendy Rose; Herbst, Patricio

    2012-01-01

    We inspect the hypothesis that geometry students may be oriented toward how they expect that the teacher will evaluate them as students or otherwise oriented to how they expect that their work will give them opportunities to do mathematics. The results reported here are based on a mixed-methods analysis of twenty-two interviews with high school…

  12. Physiological optics and physical geometry.

    PubMed

    Hyder, D J

    2001-09-01

    Hermann von Helmholtz's distinction between "pure intuitive" and "physical" geometry must be counted as the most influential of his many contributions to the philosophy of science. In a series of papers from the 1860s and 70s, Helmholtz argued against Kant's claim that our knowledge of Euclidean geometry was an a priori condition for empirical knowledge. He claimed that geometrical propositions could be meaningful only if they were taken to concern the behaviors of physical bodies used in measurement, from which it followed that it was posterior to our acquaintance with this behavior. This paper argues that Helmholtz's understanding of geometry was fundamentally shaped by his work in sense-physiology, above all on the continuum of colors. For in the course of that research, Helmholtz was forced to realize that the color-space had no inherent metrical structure. The latter was a product of axiomatic definitions of color-addition and the empirical results of such additions. Helmholtz's development of these views is explained with detailed reference to the competing work of the mathematician Hermann Grassmann and that of the young James Clerk Maxwell. It is this separation between 1) essential properties of a continuum, 2) supplementary axioms concerning distance-measurement, and 3) the behaviors of the physical apparatus used to realize the axioms, which is definitive of Helmholtz's arguments concerning geometry.

  13. Noncommutative geometry inspired entropic inflation

    NASA Astrophysics Data System (ADS)

    Nozari, Kourosh; Akhshabi, Siamak

    2011-06-01

    Recently Verlinde proposed that gravity can be described as an emergent phenomena arising from changes in the information associated with the positions of material bodies. By using noncommutative geometry as a way to describe the microscopic microstructure of quantum spacetime, we derive modified Friedmann equation in this setup and study the entropic force modifications to the inflationary dynamics of early universe.

  14. Math Sense: Algebra and Geometry.

    ERIC Educational Resources Information Center

    Howett, Jerry

    This book is designed to help students gain the range of math skills they need to succeed in life, work, and on standardized tests; overcome math anxiety; discover math as interesting and purposeful; and develop good number sense. Topics covered in this book include algebra and geometry. Lessons are organized around four strands: (1) skill lessons…

  15. Signature geometry and quantum engineering

    NASA Astrophysics Data System (ADS)

    Samociuk, Stefan

    2013-09-01

    As the operating frequency of electromagnetic based devices increase, physical design geometry is playing an ever more important role. Evidence is considered in support of a relationship between the dimensionality of primitive geometric forms, such as transistors, and corresponding electromagnetic coupling efficiency. The industry of electronics is defined as the construction of devices by the patterning of primitive forms to physical materials. Examples are given to show the evolution of these primitives, down to nano scales, are requiring exacting geometry and three dimensional content. Consideration of microwave monolithic integrated circuits,(MMIC), photonics and metamaterials,(MM), support this trend and also add new requirements of strict geometric periodicity and multiplicity. Signature geometries,(SG), are characterized by distinctive attributes and examples are given. The transcendent form transcode algorithm, (TTA) is introduced as a multi dimensional SG and its use in designing photonic integrated circuits and metamaterials is discussed . A creative commons licensed research database, TRANSFORM, containing TTA geometries in OASIS file formats is described. An experimental methodology for using the database is given. Multidimensional SG and extraction of three dimensional cross sections as primitive forms is discussed as a foundation for quantum engineering and the exploitation of phenomena other than the electromagnetic.

  16. Heavy ion collisions

    SciTech Connect

    Jacak, B.V.

    1994-11-01

    Heavy ion collisions at very high energies provide an opportunity to recreate in the laboratory the conditions which existed very early in the universe, just after the big bang. We prepare matter at very high energy density and search for evidence that the quarks and gluons are deconfined. I describe the kinds of observables that are experimentally accessible to characterize the system and to search for evidence of new physics. A wealth of information is now available from CERN and BNL heavy ion experiments. I discuss recent results on two particle correlations, strangeness production, and dilepton and direct photon distributions.

  17. Hydrogen-Antihydrogen Collisions

    SciTech Connect

    Froelich, P.; Jonsell, S.; Saenz, A.; Zygelman, B.; Dalgarno, A.

    2000-05-15

    Matter-antimatter interactions are investigated using hydrogen-antihydrogen collisions as an example. Cross sections for elastic scattering and for the antihydrogen loss (either through the rearrangement reaction, resulting in formation of protonium and positronium according to H+H(bar sign){yields}p p(bar sign)+e{sup +}e{sup -} , or via annihilation in flight) are calculated for the first time in a fully quantum mechanical approach. Implications for experiments intending to trap and cool antihydrogen are discussed. (c) 2000 The American Physical Society.

  18. Cell Volume Fluctuations in MDCK Monolayers

    PubMed Central

    Zehnder, Steven M.; Suaris, Melanie; Bellaire, Madisonclaire M.; Angelini, Thomas E.

    2015-01-01

    Cells moving collectively in tissues constitute a form of active matter, in which collective motion depends strongly on driven fluctuations at the single-cell scale. Fluctuations in cell area and number density are often seen in monolayers, yet their role in collective migration is not known. Here we study density fluctuations at the single- and multicell level, finding that single-cell volumes oscillate with a timescale of 4 h and an amplitude of 20%; the timescale and amplitude are found to depend on cytoskeletal activity. At the multicellular scale, density fluctuations violate the central limit theorem, highlighting the role of nonequilibrium driving forces in multicellular density fluctuations. PMID:25606673

  19. Fluctuation theorem for partially masked nonequilibrium dynamics.

    PubMed

    Shiraishi, Naoto; Sagawa, Takahiro

    2015-01-01

    We establish a generalization of the fluctuation theorem for partially masked nonequilibrium dynamics. We introduce a partial entropy production with a subset of all possible transitions, and show that the partial entropy production satisfies the integral fluctuation theorem. Our result reveals the fundamental properties of a broad class of autonomous as well as nonautonomous nanomachines. In particular, our result gives a unified fluctuation theorem for both autonomous and nonautonomous Maxwell's demons, where mutual information plays a crucial role. Furthermore, we derive a fluctuation-dissipation theorem that relates nonequilibrium stationary current to two kinds of equilibrium fluctuations. PMID:25679593

  20. Fluctuation theorem for partially masked nonequilibrium dynamics

    NASA Astrophysics Data System (ADS)

    Shiraishi, Naoto; Sagawa, Takahiro

    2015-01-01

    We establish a generalization of the fluctuation theorem for partially masked nonequilibrium dynamics. We introduce a partial entropy production with a subset of all possible transitions, and show that the partial entropy production satisfies the integral fluctuation theorem. Our result reveals the fundamental properties of a broad class of autonomous as well as nonautonomous nanomachines. In particular, our result gives a unified fluctuation theorem for both autonomous and nonautonomous Maxwell's demons, where mutual information plays a crucial role. Furthermore, we derive a fluctuation-dissipation theorem that relates nonequilibrium stationary current to two kinds of equilibrium fluctuations.

  1. A clinically feasible method for the detection of potential collision in proton therapy

    SciTech Connect

    Zou Wei; Lin Haibo; Plastaras, John P.; Wang Huanshu; Bui, Viet; Vapiwala, Neha; McDonough, James; Tochner, Zelig; Both, Stefan

    2012-11-15

    Purpose: Potential collision between the patient/couch and the gantry could delay the start of the treatment and reduce clinical efficiency. The ability to accurately detect possible collisions during the treatment planning phase is desired. Such collision detection should account for the specific proton gantry design, the treatment beam configuration, couch orientation, and the patient specific geometry. In this paper the authors developed an approach to detect possible patient-machine collisions using patient treatment plan data. Methods: The geometry of the machine and the patient was reconstructed relative to the isocenter of the proton treatment room. The surface contour of the gantry was first captured from the proton computer aided design and reconstructed to account for specific gantry rotation, snout position, collimator rotation, and range compensator dimensions based on the patient treatment plan data. The patient body and couch contours were captured from the patient's CT DICOM structure file. They were reconstructed relative to the isocenter taking into account treatment couch rotation. For potential collision that occurs at body portions where no CT images exist, scout images are used to construct the body contour. A software program was developed using a ray casting algorithm that was applied to detect collisions by determining if any of the patient and couch contour points fall into the spatial polygons formed by the proton gantry surfaces. Results: Twenty-four patient plans with or without potential collisions were retrospectively identified and analyzed using the collision detection software. In addition, five collision cases were artificially generated using an anthropomorphic phantom. The program successfully detected the collisions in all cases. The calculation time for each case was within 20 s. The software program was implemented in the authors' clinic to detect patient-gantry or gantry-couch collisions in the treatment planning phase

  2. Velocity fluctuations of fission fragments

    NASA Astrophysics Data System (ADS)

    Llanes-Estrada, Felipe J.; Carmona, Belén Martínez; Martínez, Jose L. Muñoz

    2016-02-01

    We propose event by event velocity fluctuations of nuclear fission fragments as an additional interesting observable that gives access to the nuclear temperature in an independent way from spectral measurements and relates the diffusion and friction coefficients for the relative fragment coordinate in Kramers-like models (in which some aspects of fission can be understood as the diffusion of a collective variable through a potential barrier). We point out that neutron emission by the heavy fragments can be treated in effective theory if corrections to the velocity distribution are needed.

  3. Simulation of nanoscale density fluctuations

    NASA Astrophysics Data System (ADS)

    Reiss, Howard; Bowles, Richard K.

    2000-11-01

    Problems associated with the simulation of density fluctuations of limited breadth in a small cell are exposed and studied. The fluctuations are viewed as "physical clusters" of the type that might appear in nucleation processes and related phenomena. One of the most important features of the study stems from the fact that the simulation of a small heterogeneity in a macroscopic system presents problems that do not occur in the simulation of a bulk homogeneous property of the system. For example, once having simulated the probability of appearance of the fluctuation in a small cell, how is that result to be "mapped" onto the macrosystem in order to specify the equilibrium number of such fluctuations in that system? This problem is closely associated with the proper separation of the translational and internal degrees of freedom of the system, and has arisen in a number of fields, including the theory of nucleation. There are other problems associated with exponential dependence of cluster probability on the work of formation of the cluster, and also with rareness of some important clusters. In the latter case, simulative "umbrella sampling" does not always solve the entire problem. The present study is confined to clusters that appear in rarefied gases. Such systems are important in a number of scenarios, including nucleation processes. Several cluster models are considered including those consisting of molecules confined to a "container" of fixed volume and those constructed on the center of mass of the cluster. Connections between them are derived and rigorous solutions to the mapping problem are derived. Quantitative measures for the accuracy of approximate solutions, applied to cases in which the cluster is compact, are provided and exact solutions are provided even for the noncompact case. Some surprising results emerge from the study, among which is the fact that a cluster whose location is determined by one of its molecules, does not always have a

  4. Geochemical Interpretation of Collision Volcanism

    NASA Astrophysics Data System (ADS)

    Pearce, Julian

    2014-05-01

    Collision volcanism can be defined as volcanism that takes place during an orogeny from the moment that continental subduction starts to the end of orogenic collapse. Its importance in the Geological Record is greatly underestimated as collision volcanics are easily misinterpreted as being of volcanic arc, extensional or mantle plume origin. There are many types of collision volcanic province: continent-island arc collision (e.g. Banda arc); continent-active margin collision (e.g. Tibet, Turkey-Iran); continent-rear-arc collision (e.g. Bolivia); continent-continent collision (e.g. Tuscany); and island arc-island arc collision (e.g. Taiwan). Superimposed on this variability is the fact that every orogeny is different in detail. Nonetheless, there is a general theme of cyclicity on different time scales. This starts with syn-collision volcanism resulting from the subduction of an ocean-continent transition and continental lithosphere, and continues through post-collision volcanism. The latter can be subdivided into orogenic volcanism, which is related to thickened crust, and post-orogenic, which is related to orogenic collapse. Typically, but not always, collision volcanism is preceded by normal arc volcanism and followed by normal intraplate volcanism. Identification and interpretation of collision volcanism in the Geologic Record is greatly facilitated if a dated stratigraphic sequence is present so that the petrogenic evolution can be traced. In any case, the basis of fingerprinting collision terranes is to use geochemical proxies for mantle and subduction fluxes, slab temperatures, and depths and degrees of melting. For example, syn-collision volcanism is characterized by a high subduction flux relative to mantle flux because of the high input flux of fusible sediment and crust coupled with limited mantle flow, and because of high slab temperatures resulting from the decrease in subduction rate. The resulting geochemical patterns are similar regardless of

  5. Triangular flow of thermal photons from an event-by-event hydrodynamic model for 2.76 A TeV Pb + Pb collisions at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Chatterjee, Rupa; Srivastava, Dinesh K.; Renk, Thorsten

    2016-07-01

    We calculate the triangular flow parameter v3 of thermal photons from an event-by-event ideal hydrodynamic model for 0-40% central collisions of Pb nuclei at √{sN N}=2.76 TeV at the CERN Large Hadron Collider. v3 determined with respect to the participant plane (PP) is found to be nonzero and positive, and its pT dependence is qualitatively similar to the elliptic flow parameter v2(PP) of thermal photons in the range 1 ≤pT≤6 GeV/c . In the range pT≤ 3 GeV/c , v3(PP) is found to be about 50-75% of v2(PP) and for pT> 3 GeV/c the two anisotropy parameters become comparable. The value of v3 is driven by local density fluctuations both directly via the creation of triangular geometry and indirectly via additional flow. As expected, the triangular flow parameter calculated with respect to the reaction plane v3(RP) is found to be close to zero. We show that v3(PP) strongly depends on the spatial size of fluctuations, especially in the higher pT(≥3 GeV /c ) region where a larger value of σ results in a smaller v3(PP ) . In addition, v3(PP ) is found to increase with the assumed formation time of the thermalized system.

  6. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1985-01-01

    The study of photon-photon collisions has progressed enormously, stimulated by new data and new calculational tools for QCD. In the future we can expect precise determinations of ..cap alpha../sub s/ and ..lambda../sup ms/ from the ..gamma..*..gamma.. ..-->.. ..pi../sup 0/ form factor and the photon structure function, as well as detailed checks of QCD, determination of the shape of the hadron distribution amplitudes from ..gamma gamma.. ..-->.. H anti H, reconstruction of sigma/sub ..gamma gamma../ from exclusive channels at low W/sub ..gamma gamma../, definitive studies of high p/sub T/ hadron and jet production, and studies of threshold production of charmed systems. Photon-photon collisions, along with radiative decays of the psi and UPSILON, are ideal for the study of multiquark and gluonic resonances. We have emphasized the potential for resonance formation near threshold in virtually every hadronic exclusive channel, including heavy quark states c anti c c anti c, c anti c u anti u, etc. At higher energies SLC, LEP, ...) parity-violating electroweak effects and Higgs production due to equivalent Z/sup 0/ and W/sup + -/ beams from e ..-->.. eZ/sup 0/ and e ..-->.. nu W will become important. 44 references.

  7. Collision in space

    NASA Technical Reports Server (NTRS)

    Ellis, S. R.

    2000-01-01

    On June 25, 1997, the Russian supply spacecraft Progress 234 collided with the Mir space station, rupturing Mir's pressure hull, throwing it into an uncontrolled attitude drift, and nearly forcing evacuation of the station. Like many high-profile accidents, this collision was the consequence of a chain of events leading to the final piloting errors that were its immediate cause. The discussion in this article does not resolve the relative contributions of the actions and decisions in this chain. Neither does it suggest corrective measures, many of which are straightforward and have already been implemented by the National Aeronautics and Space Administration (NASA) and the Russian Space Agency. Rather, its purpose is to identify the human factors that played a pervasive role in the incident. Workplace stress, fatigue, and sleep deprivation were identified by NASA as contributory factors in the Mir-Progress collision (Culbertson, 1997; NASA, forthcoming), but other contributing factors, such as requiring crew to perform difficult tasks for which their training is not current, could potentially become important factors in future situations.

  8. Recognition of movement object collision

    NASA Astrophysics Data System (ADS)

    Chang, Hsiao Tsu; Sun, Geng-tian; Zhang, Yan

    1991-03-01

    The paper explores the collision recognition of two objects in both crisscross and revolution motions A mathematical model has been established based on the continuation theory. The objects of any shape may be regarded as being built of many 3siniplexes or their convex hulls. Therefore the collision problem of two object in motion can be reduced to the collision of two corresponding 3siinplexes on two respective objects accordingly. Thus an optimized algorithm is developed for collision avoidance which is suitable for computer control and eliminating the need for vision aid. With this algorithm computation time has been reduced significantly. This algorithm is applicable to the path planning of mobile robots And also is applicable to collision avoidance of the anthropomorphic arms grasping two complicated shaped objects. The algorithm is realized using LISP language on a VAX8350 minicomputer.

  9. Dielectric fluctuations in force microscopy: noncontact friction and frequency jitter.

    PubMed

    Yazdanian, Showkat M; Marohn, John A; Loring, Roger F

    2008-06-14

    Electric force microscopy, in which a charged probe oscillates tens to hundreds of nanometers above a sample surface, provides direct mechanical detection of relaxation in molecular materials. Noncontact friction, the damping of the probe's motions, reflects the dielectric function at the resonant frequency of the probe, while fluctuations in the probe frequency are induced by slower molecular motions. We present a unified theoretical picture of both measurements, which relates the noncontact friction and the power spectrum of the frequency jitter to dielectric properties of the sample and to experimental geometry. Each observable is related to an equilibrium correlation function associated with electric field fluctuations, which is determined by two alternative, complementary strategies for a dielectric continuum model of the sample. The first method is based on the calculation of a response function associated with the polarization of the dielectric by a time-varying external charge distribution. The second approach employs a stochastic form of Maxwell's equations, which incorporate a fluctuating electric polarization, to compute directly the equilibrium correlation function in the absence of an external charge distribution. This approach includes effects associated with the propagation of radiation. In the experimentally relevant limit that the tip-sample distance is small compared to pertinent wavelengths of radiation, the two methods yield identical results. Measurements of the power spectrum of frequency fluctuations of an ultrasensitive cantilever together with measurements of the noncontact friction over a poly(methylmethacrylate) film are used to estimate the minimum experimentally detectable frequency jitter. The predicted jitter for this polymer is shown to exceed this threshold, demonstrating the feasibility of the measurement. PMID:18554042

  10. Fluctuations and the Hofmeister effect.

    PubMed Central

    Neagu, A; Neagu, M; Dér, A

    2001-01-01

    The Hofmeister effect consists in changes of protein solubility triggered by neutral electrolyte cosolutes. Based on the assumption that salts cause stochastic fluctuations of the free energy barrier profiles, a kinetic theory of this phenomenon is proposed. An exponentially correlated noise, of amplitude proportional to the salt concentration, is added to each energy level, and the time-dependence of the mean protein concentration is calculated. It is found that the theory yields the well-known Setschenow equation if the noise correlation time is low in comparison to the aggregation time constant. Experimental data on salting-in agents are well fitted, whereas, in the case of salting-out cosolutes, two independent dichotomic fluctuations are needed to fit the data. This may result from the fact that, in both cases, the low-concentration regime is dominated by salting-in electrostatic contributions, whereas, at high salt concentrations, electron donor/acceptor interactions become important; these have opposite effects. The theory offers a novel way to metricate Hofmeister effects and also leads to thermodynamic quantities, which account for the influence of salts. The formalism may also be applied to describe kinetic phenomena in the presence of cosolutes. PMID:11509345

  11. Universal bounds on current fluctuations

    NASA Astrophysics Data System (ADS)

    Pietzonka, Patrick; Barato, Andre C.; Seifert, Udo

    2016-05-01

    For current fluctuations in nonequilibrium steady states of Markovian processes, we derive four different universal bounds valid beyond the Gaussian regime. Different variants of these bounds apply to either the entropy change or any individual current, e.g., the rate of substrate consumption in a chemical reaction or the electron current in an electronic device. The bounds vary with respect to their degree of universality and tightness. A universal parabolic bound on the generating function of an arbitrary current depends solely on the average entropy production. A second, stronger bound requires knowledge both of the thermodynamic forces that drive the system and of the topology of the network of states. These two bounds are conjectures based on extensive numerics. An exponential bound that depends only on the average entropy production and the average number of transitions per time is rigorously proved. This bound has no obvious relation to the parabolic bound but it is typically tighter further away from equilibrium. An asymptotic bound that depends on the specific transition rates and becomes tight for large fluctuations is also derived. This bound allows for the prediction of the asymptotic growth of the generating function. Even though our results are restricted to networks with a finite number of states, we show that the parabolic bound is also valid for three paradigmatic examples of driven diffusive systems for which the generating function can be calculated using the additivity principle. Our bounds provide a general class of constraints for nonequilibrium systems.

  12. Rapid fluctuations in solar flares

    NASA Technical Reports Server (NTRS)

    Sturrock, Peter A.

    1986-01-01

    Study of rapid fluctuations in the emission of radiation from solar flares provides a promising approach for probing the magneto-plasma structure and plasma processes that are responsible for a flare. It is proposed that elementary flare bursts in X-ray and microwave emission may be attributed to fine structure of the coronal magnetic field, related to the aggregation of photospheric magnetic field into magnetic knots. Fluctuations that occur on a subsecond time-scale may be due to magnetic islands that develop in current sheets during magnetic reconnection. The impulsive phase may sometimes represent the superposition of a large number of the elementary energy-release processes responsible for elementary flare bursts. If so, the challenge of trying to explain the properties of the impulsive phase in terms of the properties of the elementary processes must be faced. Magnetic field configurations that might produce solar flares are divided into a number of categories, depending on: whether or not there is a filament; whether there is no current sheet, a closed current sheet, or an open current sheet; and whether the filament erupts into the corona, or is ejected completely from the Sun's atmosphere. Analysis of the properties of these possible configurations is compared with different types of flares, and to Bai's subdivision of gamma-ray/proton events.

  13. Protrusion Fluctuations Direct Cell Motion

    PubMed Central

    Caballero, David; Voituriez, Raphaël; Riveline, Daniel

    2014-01-01

    Many physiological phenomena involve directional cell migration. It is usually attributed to chemical gradients in vivo. Recently, other cues have been shown to guide cells in vitro, including stiffness/adhesion gradients or micropatterned adhesive motifs. However, the cellular mechanism leading to these biased migrations remains unknown, and, often, even the direction of motion is unpredictable. In this study, we show the key role of fluctuating protrusions on ratchet-like structures in driving NIH3T3 cell migration. We identified the concept of efficient protrusion and an associated direction index. Our analysis of the protrusion statistics facilitated the quantitative prediction of cell trajectories in all investigated conditions. We varied the external cues by changing the adhesive patterns. We also modified the internal cues using drug treatments, which modified the protrusion activity. Stochasticity affects the short- and long-term steps. We developed a theoretical model showing that an asymmetry in the protrusion fluctuations is sufficient for predicting all measures associated with the long-term motion, which can be described as a biased persistent random walk. PMID:24988339

  14. A Computational Study of Systemic Hydration in Vocal Fold Collision

    PubMed Central

    Bhattacharya, Pinaki; Siegmund, Thomas

    2013-01-01

    Mechanical stresses develop within vocal fold (VF) soft tissues, due to phonation-associated vibration and collision. These stresses in turn affect the hydration of VF tissue and thus influence voice health. In this paper, high-fidelty numerical computations are described taking into account fully three-dimensional geometry, realistic tissue and air properties, and high-amplitude vibration and collision. A segregated solver approach is employed, using sophisticated commercial solvers for both the VF tissue and glottal airflow domains. The tissue viscoelastic properties were derived from a biphasic formulation. Two cases were considered, whereby the tissue viscoelastic properties corresponded to two different volume fractions of the fluid phase of the VF tissue. For each case, hydrostatic stresses occurring as a result of vibration and collision were investigated. Assuming the VF tissue to be poroelastic, interstitial fluid movement within VF tissue was estimated from the hydrostatic stress gradient. Computed measures of overall VF dynamics (peak air-flow velocity, magnitude of VF deformation, frequency of vibration and contact pressure) were well within the range of experimentally observed values. The VF motion leading to mechanical stresses within the VFs and their effect on the interstitial fluid flux is detailed. It is found that average deformation and vibration of VFs tends to increase the state of hydration of the VF tissue whereas VF collision works to reduce hydration. PMID:23531170

  15. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    SciTech Connect

    Rosenberg, M. J.; Li, C. K.; Fox, W.; Igumenshchev, I.; Seguin, F. H.; Town, R. P.; Frenje, J. A.; Stoeckl, C.; Glebov, V.; Petrasso, R. D.

    2015-04-08

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β~10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell (PIC) simulations predict a stronger flux compression and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.

  16. Finite-geometry models of electric field noise from patch potentials in ion traps

    SciTech Connect

    Low, Guang Hao; Herskind, Peter F.; Chuang, Isaac L.

    2011-11-15

    We model electric field noise from fluctuating patch potentials on conducting surfaces by taking into account the finite geometry of the ion trap electrodes to gain insight into the origin of anomalous heating in ion traps. The scaling of anomalous heating rates with surface distance d is obtained for several generic geometries of relevance to current ion trap designs, ranging from planar to spheroidal electrodes. The influence of patch size is studied both by solving Laplace's equation in terms of the appropriate Green's function as well as through an eigenfunction expansion. Scaling with surface distance is found to be highly dependent on the choice of geometry and the relative scale between the spatial extent of the electrode, the ion-electrode distance, and the patch size. Our model generally supports the d{sup -4} dependence currently found by most experiments and models, but also predicts geometry-driven deviations from this trend.

  17. Stringy differential geometry, beyond Riemann

    NASA Astrophysics Data System (ADS)

    Jeon, Imtak; Lee, Kanghoon; Park, Jeong-Hyuck

    2011-08-01

    While the fundamental object in Riemannian geometry is a metric, closed string theories call for us to put a two-form gauge field and a scalar dilaton on an equal footing with the metric. Here we propose a novel differential geometry that treats the three objects in a unified manner, manifests not only diffeomorphism and one-form gauge symmetry but also O(D,D) T-duality, and enables us to rewrite the known low energy effective action of them as a single term. Further, we develop a corresponding vielbein formalism and gauge the internal symmetry that is given by a direct product of two local Lorentz groups, SO(1,D-1)×SŌ(1,D-1). We comment that the notion of cosmological constant naturally changes.

  18. Geometry-invariant resonant cavities

    PubMed Central

    Liberal, I.; Mahmoud, A. M.; Engheta, N.

    2016-01-01

    Resonant cavities are one of the basic building blocks in various disciplines of science and technology, with numerous applications ranging from abstract theoretical modelling to everyday life devices. The eigenfrequencies of conventional cavities are a function of their geometry, and, thus, the size and shape of a resonant cavity is selected to operate at a specific frequency. Here we demonstrate theoretically the existence of geometry-invariant resonant cavities, that is, resonators whose eigenfrequencies are invariant with respect to geometrical deformations of their external boundaries. This effect is obtained by exploiting the unusual properties of zero-index metamaterials, such as epsilon-near-zero media, which enable decoupling of the temporal and spatial field variations in the lossless limit. This new class of resonators may inspire alternative design concepts, and it might lead to the first generation of deformable resonant devices. PMID:27010103

  19. Geometry of area without length

    NASA Astrophysics Data System (ADS)

    Ho, Pei-Ming; Inami, Takeo

    2016-01-01

    To define a free string by the Nambu-Goto action, all we need is the notion of area, and mathematically the area can be defined directly in the absence of a metric. Motivated by the possibility that string theory admits backgrounds where the notion of length is not well defined but a definition of area is given, we study space-time geometries based on the generalization of a metric to an area metric. In analogy with Riemannian geometry, we define the analogues of connections, curvatures, and Einstein tensor. We propose a formulation generalizing Einstein's theory that will be useful if at a certain stage or a certain scale the metric is ill defined and the space-time is better characterized by the notion of area. Static spherical solutions are found for the generalized Einstein equation in vacuum, including the Schwarzschild solution as a special case.

  20. Hyperbolic geometry for colour metrics.

    PubMed

    Farup, Ivar

    2014-05-19

    It is well established from both colour difference and colour order perpectives that the colour space cannot be Euclidean. In spite of this, most colour spaces still in use today are Euclidean, and the best Euclidean colour metrics are performing comparably to state-of-the-art non-Euclidean metrics. In this paper, it is shown that a transformation from Euclidean to hyperbolic geometry (i.e., constant negative curvature) for the chromatic plane can significantly improve the performance of Euclidean colour metrics to the point where they are statistically significantly better than state-of-the-art non-Euclidean metrics on standard data sets. The resulting hyperbolic geometry nicely models both qualitatively and quantitatively the hue super-importance phenomenon observed in colour order systems.

  1. Collision detection for planning collision-free motion of two robot arms

    NASA Technical Reports Server (NTRS)

    Basta, Robert A.; Mehrotra, Rajiv; Varanasi, Murali R.

    1988-01-01

    The authors focus on collision detection for planning collision-free motion of two robot arms in a common workspace. A collision-free motion is obtained by detecting collisions along the straight-line trajectories of the robots using a sphere model for the wrists and then replanning the paths and/or trajectories of one or both of the robots to avoid collisions. A novel approach to collision detection is presented and a discussion on collision avoidance is given.

  2. Geometry Dependence of Stellarator Turbulence

    SciTech Connect

    H.E. Mynick, P. Xanthopoulos and A.H. Boozer

    2009-08-10

    Using the nonlinear gyrokinetic code package GENE/GIST, we study the turbulent transport in a broad family of stellarator designs, to understand the geometry-dependence of the microturbulence. By using a set of flux tubes on a given flux surface, we construct a picture of the 2D structure of the microturbulence over that surface, and relate this to relevant geometric quantities, such as the curvature, local shear, and effective potential in the Schrodinger-like equation governing linear drift modes.

  3. Orbit propagation in Minkowskian geometry

    NASA Astrophysics Data System (ADS)

    Roa, Javier; Peláez, Jesús

    2015-09-01

    The geometry of hyperbolic orbits suggests that Minkowskian geometry, and not Euclidean, may provide the most adequate description of the motion. This idea is explored in order to derive a new regularized formulation for propagating arbitrarily perturbed hyperbolic orbits. The mathematical foundations underlying Minkowski space-time are exploited to describe hyperbolic orbits. Hypercomplex numbers are introduced to define the rotations, vectors, and metrics in the problem: the evolution of the eccentricity vector is described on the Minkowski plane in terms of hyperbolic numbers, and the orbital plane is described on the inertial reference using quaternions. A set of eight orbital elements is introduced, namely a time-element, the components of the eccentricity vector in , the semimajor axis, and the components of the quaternion defining the orbital plane. The resulting formulation provides a deep insight into the geometry of hyperbolic orbits. The performance of the formulation in long-term propagations is studied. The orbits of four hyperbolic comets are integrated and the accuracy of the solution is compared to other regularized formulations. The resulting formulation improves the stability of the integration process and it is not affected by the perihelion passage. It provides a level of accuracy that may not be reached by the compared formulations, at the cost of increasing the computational time.

  4. Symmetries in fluctuations far from equilibrium.

    PubMed

    Hurtado, Pablo I; Pérez-Espigares, Carlos; del Pozo, Jesús J; Garrido, Pedro L

    2011-05-10

    Fluctuations arise universally in nature as a reflection of the discrete microscopic world at the macroscopic level. Despite their apparent noisy origin, fluctuations encode fundamental aspects of the physics of the system at hand, crucial to understand irreversibility and nonequilibrium behavior. To sustain a given fluctuation, a system traverses a precise optimal path in phase space. Here we show that by demanding invariance of optimal paths under symmetry transformations, new and general fluctuation relations valid arbitrarily far from equilibrium are unveiled. This opens an unexplored route toward a deeper understanding of nonequilibrium physics by bringing symmetry principles to the realm of fluctuations. We illustrate this concept studying symmetries of the current distribution out of equilibrium. In particular we derive an isometric fluctuation relation that links in a strikingly simple manner the probabilities of any pair of isometric current fluctuations. This relation, which results from the time-reversibility of the dynamics, includes as a particular instance the Gallavotti-Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by time-reversibility on the statistics of nonequilibrium fluctuations. The new symmetry implies remarkable hierarchies of equations for the current cumulants and the nonlinear response coefficients, going far beyond Onsager's reciprocity relations and Green-Kubo formulas. We confirm the validity of the new symmetry relation in extensive numerical simulations, and suggest that the idea of symmetry in fluctuations as invariance of optimal paths has far-reaching consequences in diverse fields.

  5. Symmetries in fluctuations far from equilibrium

    PubMed Central

    Hurtado, Pablo I.; Pérez-Espigares, Carlos; del Pozo, Jesús J.; Garrido, Pedro L.

    2011-01-01

    Fluctuations arise universally in nature as a reflection of the discrete microscopic world at the macroscopic level. Despite their apparent noisy origin, fluctuations encode fundamental aspects of the physics of the system at hand, crucial to understand irreversibility and nonequilibrium behavior. To sustain a given fluctuation, a system traverses a precise optimal path in phase space. Here we show that by demanding invariance of optimal paths under symmetry transformations, new and general fluctuation relations valid arbitrarily far from equilibrium are unveiled. This opens an unexplored route toward a deeper understanding of nonequilibrium physics by bringing symmetry principles to the realm of fluctuations. We illustrate this concept studying symmetries of the current distribution out of equilibrium. In particular we derive an isometric fluctuation relation that links in a strikingly simple manner the probabilities of any pair of isometric current fluctuations. This relation, which results from the time-reversibility of the dynamics, includes as a particular instance the Gallavotti–Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by time-reversibility on the statistics of nonequilibrium fluctuations. The new symmetry implies remarkable hierarchies of equations for the current cumulants and the nonlinear response coefficients, going far beyond Onsager’s reciprocity relations and Green–Kubo formulas. We confirm the validity of the new symmetry relation in extensive numerical simulations, and suggest that the idea of symmetry in fluctuations as invariance of optimal paths has far-reaching consequences in diverse fields. PMID:21493865

  6. Sixteenth International Conference on the physics of electronic and atomic collisions

    SciTech Connect

    Dalgarno, A.; Freund, R.S.; Lubell, M.S.; Lucatorto, T.B.

    1989-01-01

    This report contains abstracts of papers on the following topics: photons, electron-atom collisions; electron-molecule collisions; electron-ion collisions; collisions involving exotic species; ion- atom collisions, ion-molecule or atom-molecule collisions; atom-atom collisions; ion-ion collisions; collisions involving rydberg atoms; field assisted collisions; collisions involving clusters and collisions involving condensed matter.

  7. Geometry controls conformation of graphene sheets: membranes, ribbons, and scrolls.

    PubMed

    Xu, Zhiping; Buehler, Markus J

    2010-07-27

    Graphene features a two-dimensional structure, where applications from electronic building blocks to reinforced composites are emerging, enabled through the utilization of its intriguing electrical, mechanical, and thermal properties. These properties are controlled by the structural makeup of graphene, which is known to display multiple morphologies that change under thermal fluctuations and variations of its geometry. However, as of now, a systematic understanding of the relationship between the conformation of graphene and its geometry remains unknown, preventing rational bottom-up design of materials, structures, and devices. Here, we present a conformational phase diagram for rectangular graphene sheets, defined by their geometry (size and aspect ratio), boundary conditions, and the environmental conditions such as supporting substrates and chemical modifications, as well as changes in temperature. We discover the occurrence of three major structural arrangements in membrane, ribbon, and scroll phases as the aspect ratio of the graphene nanoribbon increases. A theoretical and computational analysis of governing mechanisms for each conformation is provided. PMID:20597529

  8. Speed-dependent collision effects on radar back-scattering from the ionosphere

    NASA Technical Reports Server (NTRS)

    Theimer, O.

    1981-01-01

    A computer code to accurately compute the fluctuation spectrum for linearly speed dependent collision frequencies was developed. The effect of ignoring the speed dependence on the estimates of ionospheric parameters was determined. It is shown that disagreements between the rocket and the incoherent scatter estimates could be partially resolved if the correct speed dependence of the i-n collision frequency is not ignored. This problem is also relevant to the study of ionospheric irregularities in the auroral E-region and their effects on the radio communication with satellites.

  9. Initial state characteristics of proton-nucleus collisions from Glauber Monte Carlo

    NASA Astrophysics Data System (ADS)

    Rybczynski, Maciej; Wlodarczyk, Zbigniew

    2015-08-01

    Fluctuations in physics observables in high energy ion collisions have been a topic of particular interest in recent years as they may provide important signals regarding the formation of quark-gluon plasma and the existence of a critical point. We provide predictions for basic initial state characteristics of proton-nucleus collisions from Glauber Monte Carlo models. The following systems were simulated and analysed: p + 12C, p + 14N, p + 63Cu, and p + 208Pb at wide energy range. We apply GLISSANDO accordingly fitted to tasks defined in this paper.

  10. Azimuthal anisotophy in U + U and Au + Au collisions at RHIC

    SciTech Connect

    Adamczyk, L.

    2015-11-24

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2} and v2{4}, for charged hadrons from U+U collisions at √SNN = 193 GeV and Au+Au collisions at √SNN = 200 GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. As a result, we also show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

  11. Azimuthal anisotophy in U + U and Au + Au collisions at RHIC

    DOE PAGESBeta

    Adamczyk, L.

    2015-11-24

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2} and v2{4}, for charged hadrons from U+U collisions at √SNN = 193 GeV and Au+Au collisions at √SNN = 200 GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. As a result, we alsomore » show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.« less

  12. Rubidium-Strontium collisions

    NASA Astrophysics Data System (ADS)

    Kleinert, Michaela; Potter, Garrett; Whitehead, Marc; McEntee, Elyse; Koll, Christopher J.

    2010-03-01

    The invention of the magneto-optical trap (MOT) in 1987 - which was awarded the Noble Price in Physics 10 years later - has enabled many new and exciting experiments. Among them are precision measurements of basic atomic properties, ultracold collisions, Bose-Einstein Condensates, atom lasers, etc.. Recent developments in the field of atomic and molecular physics have included the creation of diatomic (homo- and heteronuclear) molecules. These ultracold molecules promise to revolutionize physical chemistry, few-body physics, precision measurements and quantum information processing, similar to how ultracold atoms revolutionized AMO physics several years ago. We will present our first results of a mixed alkaline (rubidium) and alkaline-earth (strontium) magneto-optical trap.

  13. Geosynchronous satellite collision avoidance

    NASA Technical Reports Server (NTRS)

    Fraser, W.

    1985-01-01

    The increases in the number of satellite systems, the growing dependency on these systems, and the potentially hazardous conjunctions in space, dictates careful management of satellite positions. The potential for satellite collision increases as more objects are placed in orbit. At geosynchronous altitudes active satellites maintain fixed longitudinal station-keeping control while inactive satellites and debris generally drift around the globe or oscillate about two geopotential stable points. Portions of the total objects in geosynchronous orbit are tracked by ground stations while a significant number of additional pieces of space debris regularly pass through geosynchronous orbit altitudes. The probability of an operational satellite colliding with another satellite or a piece of space debris will increase in the number of space objects, their sizes, and on-orbit lifetimes.

  14. Collision avoidance sensor skin

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The objective was to totally eliminate the possibility of a robot (or any mechanism for that matter) inducing a collision in space operations. We were particularly concerned that human beings were safe under all circumstances. This was apparently accomplished, and it is shown that GSFC has a system that is ready for space qualification and flight. However, it soon became apparent that much more could be accomplished with this technology. Payloads could be made invulnerable to collision avoidance and the blind spots behind them eliminated. This could be accomplished by a simple, non-imaging set of 'Capaciflector' sensors on each payload. It also is evident that this system could be used to align and dock the system with a wide margin of safety. Throughout, lighting problems could be ignored, and unexpected events and modeling errors taken in stride. At the same time, computational requirements would be reduced. This can be done in a simple, rugged, reliable manner that will not disturb the form factor of space systems. It will be practical for space applications. The lab experiments indicate we are well on the way to accomplishing this. Still, the research trail goes deeper. It now appears that the sensors can be extended to end effectors to provide precontact information and make robot docking (or any docking connection) very smooth, with minimal loads impacted back into the mating structures. This type of ability would be a major step forward in basic control techniques in space. There are, however, baseline and restructuring issues to be tackled. The payloads must get power and signals to them from the robot or from the astronaut servicing tool. This requires a standard electromechanical interface. Any of several could be used. The GSFC prototype shown in this presentation is a good one. Sensors with their attendant electronics must be added to the payloads, end effectors, and robot arms and integrated into the system.

  15. Network geometry with flavor: From complexity to quantum geometry

    NASA Astrophysics Data System (ADS)

    Bianconi, Ginestra; Rahmede, Christoph

    2016-03-01

    Network geometry is attracting increasing attention because it has a wide range of applications, ranging from data mining to routing protocols in the Internet. At the same time advances in the understanding of the geometrical properties of networks are essential for further progress in quantum gravity. In network geometry, simplicial complexes describing the interaction between two or more nodes play a special role. In fact these structures can be used to discretize a geometrical d -dimensional space, and for this reason they have already been widely used in quantum gravity. Here we introduce the network geometry with flavor s =-1 ,0 ,1 (NGF) describing simplicial complexes defined in arbitrary dimension d and evolving by a nonequilibrium dynamics. The NGF can generate discrete geometries of different natures, ranging from chains and higher-dimensional manifolds to scale-free networks with small-world properties, scale-free degree distribution, and nontrivial community structure. The NGF admits as limiting cases both the Bianconi-Barabási models for complex networks, the stochastic Apollonian network, and the recently introduced model for complex quantum network manifolds. The thermodynamic properties of NGF reveal that NGF obeys a generalized area law opening a new scenario for formulating its coarse-grained limit. The structure of NGF is strongly dependent on the dimensionality d . In d =1 NGFs grow complex networks for which the preferential attachment mechanism is necessary in order to obtain a scale-free degree distribution. Instead, for NGF with dimension d >1 it is not necessary to have an explicit preferential attachment rule to generate scale-free topologies. We also show that NGF admits a quantum mechanical description in terms of associated quantum network states. Quantum network states evolve by a Markovian dynamics and a quantum network state at time t encodes all possible NGF evolutions up to time t . Interestingly the NGF remains fully classical but

  16. Network geometry with flavor: From complexity to quantum geometry.

    PubMed

    Bianconi, Ginestra; Rahmede, Christoph

    2016-03-01

    Network geometry is attracting increasing attention because it has a wide range of applications, ranging from data mining to routing protocols in the Internet. At the same time advances in the understanding of the geometrical properties of networks are essential for further progress in quantum gravity. In network geometry, simplicial complexes describing the interaction between two or more nodes play a special role. In fact these structures can be used to discretize a geometrical d-dimensional space, and for this reason they have already been widely used in quantum gravity. Here we introduce the network geometry with flavor s=-1,0,1 (NGF) describing simplicial complexes defined in arbitrary dimension d and evolving by a nonequilibrium dynamics. The NGF can generate discrete geometries of different natures, ranging from chains and higher-dimensional manifolds to scale-free networks with small-world properties, scale-free degree distribution, and nontrivial community structure. The NGF admits as limiting cases both the Bianconi-Barabási models for complex networks, the stochastic Apollonian network, and the recently introduced model for complex quantum network manifolds. The thermodynamic properties of NGF reveal that NGF obeys a generalized area law opening a new scenario for formulating its coarse-grained limit. The structure of NGF is strongly dependent on the dimensionality d. In d=1 NGFs grow complex networks for which the preferential attachment mechanism is necessary in order to obtain a scale-free degree distribution. Instead, for NGF with dimension d>1 it is not necessary to have an explicit preferential attachment rule to generate scale-free topologies. We also show that NGF admits a quantum mechanical description in terms of associated quantum network states. Quantum network states evolve by a Markovian dynamics and a quantum network state at time t encodes all possible NGF evolutions up to time t. Interestingly the NGF remains fully classical but its

  17. Network geometry with flavor: From complexity to quantum geometry.

    PubMed

    Bianconi, Ginestra; Rahmede, Christoph

    2016-03-01

    Network geometry is attracting increasing attention because it has a wide range of applications, ranging from data mining to routing protocols in the Internet. At the same time advances in the understanding of the geometrical properties of networks are essential for further progress in quantum gravity. In network geometry, simplicial complexes describing the interaction between two or more nodes play a special role. In fact these structures can be used to discretize a geometrical d-dimensional space, and for this reason they have already been widely used in quantum gravity. Here we introduce the network geometry with flavor s=-1,0,1 (NGF) describing simplicial complexes defined in arbitrary dimension d and evolving by a nonequilibrium dynamics. The NGF can generate discrete geometries of different natures, ranging from chains and higher-dimensional manifolds to scale-free networks with small-world properties, scale-free degree distribution, and nontrivial community structure. The NGF admits as limiting cases both the Bianconi-Barabási models for complex networks, the stochastic Apollonian network, and the recently introduced model for complex quantum network manifolds. The thermodynamic properties of NGF reveal that NGF obeys a generalized area law opening a new scenario for formulating its coarse-grained limit. The structure of NGF is strongly dependent on the dimensionality d. In d=1 NGFs grow complex networks for which the preferential attachment mechanism is necessary in order to obtain a scale-free degree distribution. Instead, for NGF with dimension d>1 it is not necessary to have an explicit preferential attachment rule to generate scale-free topologies. We also show that NGF admits a quantum mechanical description in terms of associated quantum network states. Quantum network states evolve by a Markovian dynamics and a quantum network state at time t encodes all possible NGF evolutions up to time t. Interestingly the NGF remains fully classical but its

  18. Fluctuations in strongly coupled cosmologies

    SciTech Connect

    Bonometto, Silvio A.; Mainini, Roberto E-mail: mainini@mib.infn.it

    2014-03-01

    In the early Universe, a dual component made of coupled CDM and a scalar field Φ, if their coupling β > (3){sup 1/2}/2, owns an attractor solution, making them a stationary fraction of cosmic energy during the radiation dominated era. Along the attractor, both such components expand ∝a{sup −4} and have early density parameters Ω{sub d} = 1/(4β{sup 2}) and Ω{sub c} = 2 Ω{sub d} (field and CDM, respectively). In a previous paper it was shown that, if a further component, expanding ∝a{sup −3}, breaks such stationary expansion at z ∼ 3–5 × 10{sup 3}, cosmic components gradually acquire densities consistent with observations. This paper, first of all, considers the case that this component is warm. However, its main topic is the analysis of fluctuation evolution: out of horizon modes are then determined; their entry into horizon is numerically evaluated as well as the dependence of Meszaros effect on the coupling β; finally, we compute: (i) transfer function and linear spectral function; (ii) CMB C{sub l} spectra. Both are close to standard ΛCDM models; in particular, the former one can be so down to a scale smaller than Milky Way, in spite of its main DM component being made of particles of mass < 1 keV. The previously coupled CDM component, whose present density parameter is O(10{sup −3}), exhibits wider fluctuations δρ/ρ, but approximately β-independent δρ values. We discuss how lower scale features of these cosmologies might ease quite a few problems that ΛCDM does not easily solve.

  19. Resonant tunneling of fluctuation Cooper pairs

    DOE PAGESBeta

    Galda, Alexey; Mel'nikov, A. S.; Vinokur, V. M.

    2015-02-09

    Superconducting fluctuations have proved to be an irreplaceable source of information about microscopic and macroscopic material parameters that could be inferred from the experiment. According to common wisdom, the effect of thermodynamic fluctuations in the vicinity of the superconducting transition temperature, Tc, is to round off all of the sharp corners and discontinuities, which otherwise would have been expected to occur at Tc. Here we report the current spikes due to radiation-induced resonant tunneling of fluctuation Cooper pairs between two superconductors which grow even sharper and more pronounced upon approach to Tc. This striking effect offers an unprecedented tool formore » direct measurements of fluctuation Cooper pair lifetime, which is key to our understanding of the fluctuation regime, most notably to nature of the pseudogap state in high-temperature superconductors. Our finding marks a radical departure from the conventional view of superconducting fluctuations as a blurring and rounding phenomenon.« less

  20. Resonant tunneling of fluctuation Cooper pairs

    SciTech Connect

    Galda, Alexey; Mel'nikov, A. S.; Vinokur, V. M.

    2015-02-09

    Superconducting fluctuations have proved to be an irreplaceable source of information about microscopic and macroscopic material parameters that could be inferred from the experiment. According to common wisdom, the effect of thermodynamic fluctuations in the vicinity of the superconducting transition temperature, Tc, is to round off all of the sharp corners and discontinuities, which otherwise would have been expected to occur at Tc. Here we report the current spikes due to radiation-induced resonant tunneling of fluctuation Cooper pairs between two superconductors which grow even sharper and more pronounced upon approach to Tc. This striking effect offers an unprecedented tool for direct measurements of fluctuation Cooper pair lifetime, which is key to our understanding of the fluctuation regime, most notably to nature of the pseudogap state in high-temperature superconductors. Our finding marks a radical departure from the conventional view of superconducting fluctuations as a blurring and rounding phenomenon.

  1. Transport and collision dynamics in periodic asymmetric obstacle arrays: Rational design of microfluidic rare-cell immunocapture devices

    NASA Astrophysics Data System (ADS)

    Gleghorn, Jason P.; Smith, James P.; Kirby, Brian J.

    2013-09-01

    Microfluidic obstacle arrays have been used in numerous applications, and their ability to sort particles or capture rare cells from complex samples has broad and impactful applications in biology and medicine. We have investigated the transport and collision dynamics of particles in periodic obstacle arrays to guide the design of convective, rather than diffusive, transport-based immunocapture microdevices. Ballistic and full computational fluid dynamics simulations are used to understand the collision modes that evolve in cylindrical obstacle arrays with various geometries. We identify previously unrecognized collision mode structures and differential size-based collision frequencies that emerge from these arrays. Previous descriptions of transverse displacements that assume unidirectional flow in these obstacle arrays cannot capture mode transitions properly as these descriptions fail to capture the dependence of the mode transitions on column spacing and the attendant change in the flow field. Using these analytical and computational simulations, we elucidate design parameters that induce high collision rates for all particles larger than a threshold size or selectively increase collision frequencies for a narrow range of particle sizes within a polydisperse population. Furthermore, we investigate how the particle Péclet number affects collision dynamics and mode transitions and demonstrate that experimental observations from various obstacle array geometries are well described by our computational model.

  2. Temporal Fluctuations in a 100-A LaB6 Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Jorns, Benjamin A.; Mikellides, Ioannis G.; Goebel, Dan M.

    2013-01-01

    The temporal fluctuations in the near plume of a 100-Amperes LaB6 (Lanthanum hexaboride) hollow cathode are experimentally investigated. At high currents, turbulent oscillations may contribute to two of the anomalous processes of hollow cathode operation - anomalous resistivity and the production of energetic ions. A detailed study of the properties of the oscillations in a high current cathode is necessary to determine the impact of the fluctuation spectrum on these two effects. In this investigation, a probe array is employed to measure the amplitude and dispersion of axial modes in the plume while a retarding potential analyzer yields estimates of the radial ion energy distribution. The onset of the ion acoustic turbulence (IAT) is observed at high current values, and the character of the turbulent spectrum is shown to agree with weak turbulent theory: the amplitude of the spectrum decreases with flow rate but increases with discharge current. Estimates of the anomalous collision frequency based on experimental observations indicate that the IAT collision frequency can exceed the classical collision frequency at sufficiently high discharge current densities. Additionally, the onset of the IAT is shown to be correlated with the appearance of a high energy ion tail and that the energy in this tail is comparable to the energy in the experimentally-observed IAT.

  3. Nonequilibrium fluctuations in a frictional granular motor: experiments and kinetic theory.

    PubMed

    Gnoli, Andrea; Sarracino, Alessandro; Puglisi, Andrea; Petri, Alberto

    2013-05-01

    We report the study of an experimental granular Brownian motor, inspired by the one published in Eshuis et al. [Phys. Rev. Lett. 104, 248001 (2010)], but different in some ingredients. As in that previous work, the motor is constituted by a rotating blade, the surfaces of which break the rotation-inversion symmetry through alternated patches of different inelasticity, immersed in a gas of granular particles. The main difference of our experimental setup is in the orientation of the main axis, which is parallel to the (vertical) direction of shaking of the granular fluid, guaranteeing an isotropic distribution for the velocities of colliding grains, characterized by a variance v(0)(2). We also keep the granular system diluted, in order to compare with Boltzmann-equation-based kinetic theory. In agreement with theory, we observe the crucial role of Coulomb friction which induces two main regimes: (i) rare collisions, with an average angular velocity <ω>~v(0)(3), and (ii) frequent collisions (FC), with <ω>~v(0). We also study the fluctuations of the angle spanned in a large-time interval Δθ, which in the FC regime is proportional to the work done upon the motor. We observe that the fluctuation relation is satisfied with a slope which weakly depends on the relative collision frequency.

  4. Thermal blurring of event-by-event fluctuations generated by rapidity conversion

    NASA Astrophysics Data System (ADS)

    Ohnishi, Yutaro; Kitazawa, Masakiyo; Asakawa, Masayuki

    2016-10-01

    We study the effect of thermal blurring caused by the use of (momentum-space) rapidity as a proxy of coordinate-space rapidity in experimental measurements of conserved-charge fluctuations in relativistic heavy-ion collisions. In theoretical studies assuming statistical mechanics, calculated fluctuations are those in a spatial volume. Experiments, on the other hand, can measure fluctuations only in a momentum space in the final state. In a standard argument to compare experimental results for a momentum space with theoretical studies for a coordinate space, rapidities of particles are implicitly regarded as equivalent to their coordinate-space rapidity. We show that the relation of two fluctuations is significantly altered by the existence of the thermal motion, i.e., thermal blurring. We discuss that the thermal blurring can be regarded as a part of the diffusion process, and the effect can be understood by studying the rapidity window dependences of fluctuations. Centrality dependence of the thermal blurring effect is also discussed.

  5. Probing Nanoscale Surface Enhanced Raman Scattering Fluctuation Dynamics using Correlated AFM and Confocal Ultramicroscopy

    SciTech Connect

    Suh, Yung D.; Schenter, Gregory K.; Zhu, Leyun; Lu, H PETER.

    2003-10-01

    We have studied the laser-excitation-intensity-dependent and Ag-nanocluster interstitial-site-dependent SERS intensity fluctuations under low molecule surface coverage of rhodamine 6G and cytochrome c. a new two-channel photon time-stamping system coupled with atomic force microscopic (AFM), Raman spectroscopic, and imaging microscopy was developed and applied to record Raman intensity fluctuation trajectories at sub-microsecond resolution correlated with in-situ characterization of the nanoparticle clusters. Our experimental results suggest that the nanoconfinement of the local electromagnetic-field enhancement and the interaction of the local field with the molecules, presumably under rotational motions, result in nano-Raman fluctuations. The SERS spectral fluctuation was pertinent to the nanoscale local enhancement and local interaction of the molecules with the surface when the number of molecules to contribute the microscopic Raman signal collected from a diffraction-limited focus spot. The SERS fluctuation dynamics were both photo-induced and spontaneous for rhodamine 6G, but only the photo-induced interstitial sites with heterogeneous geometries. To interpret the observed nano-SERS fluctuation dynamics, we used computer simulation of optical multiple scattering, based on multi-sphere scattering Mie theory, and rotational diffusion of molecules at an interstitial site, based on a random walk in orientation space.

  6. The Effect of Geometry Instruction with Dynamic Geometry Software; GeoGebra on Van Hiele Geometry Understanding Levels of Students

    ERIC Educational Resources Information Center

    Kutluca, Tamer

    2013-01-01

    The aim of this study is to investigate the effect of dynamic geometry software GeoGebra on Van Hiele geometry understanding level of students at 11th grade geometry course. The study was conducted with pre and posttest control group quasi-experimental method. The sample of the study was 42 eleventh grade students studying in the spring term of…

  7. Optical probe with light fluctuation protection

    DOEpatents

    Da Silva, Luiz B.; Chase, Charles L.

    2003-11-11

    An optical probe for tissue identification includes an elongated body. Optical fibers are located within the elongated body for transmitting light to and from the tissue. Light fluctuation protection is associated with the optical fibers. In one embodiment the light fluctuation protection includes a reflective coating on the optical fibers to reduce stray light. In another embodiment the light fluctuation protection includes a filler with very high absorption located within the elongated body between the optical fibers.

  8. Collisions in the Oort Cloud

    SciTech Connect

    Stern, S.A.

    1988-03-01

    The present assessment of the consequentiality of physical collisions between Oort Cloud objects by a first-generation model indicates that natural power-law population structures produce significant numbers of collisions between each comet and smaller objects over the age of the solar system. These collisions are held to constitute a feedback mechanism for small debris production. The impacts yield extensive comet surface evolution in the cloud, in conditions where the number of small orbiting objects conforms to the standard power-law populations. 16 references.

  9. Correlation of combustor acoustic power levels inferred from internal fluctuating pressure measurements

    NASA Technical Reports Server (NTRS)

    Vonglahn, U. H.

    1978-01-01

    Combustion chamber acoustic power levels inferred from internal fluctuating pressure measurements are correlated with operating conditions and chamber geometries over a wide range. The variables include considerations of chamber design (can, annular, and reverse-flow annular) and size, number of fuel nozzles, burner staging and fuel split, airflow and heat release rates, and chamber inlet pressure and temperature levels. The correlated data include those obtained with combustion component development rigs as well as engines.

  10. A Whirlwind Tour of Computational Geometry.

    ERIC Educational Resources Information Center

    Graham, Ron; Yao, Frances

    1990-01-01

    Described is computational geometry which used concepts and results from classical geometry, topology, combinatorics, as well as standard algorithmic techniques such as sorting and searching, graph manipulations, and linear programing. Also included are special techniques and paradigms. (KR)

  11. Optimizing solar-cell grid geometry

    NASA Technical Reports Server (NTRS)

    Crossley, A. P.

    1969-01-01

    Trade-off analysis and mathematical expressions calculate optimum grid geometry in terms of various cell parameters. Determination of the grid geometry provides proper balance between grid resistance and cell output to optimize the energy conversion process.

  12. The Geometry of Quasar Outflows

    NASA Astrophysics Data System (ADS)

    Ganguly, Rajib

    2012-10-01

    Quasar outflows are important for understanding the accretion and growth processes of the central black hole, but also potentially play a role in feedback to the galaxy, halting star formation and infall of gas. A big uncertainty lies in the geometry and density of these outflows, especially as a function of ionization and velocity. We aim to tackle this using the archival COS M grating spectra of 266 quasars. We separate the geometry of outflows into two parts: the solid angle subtended around the black hole, and the distance of the outflow from the central engine. Large numbers of quasars with high resolution spectra are required for each aspect of this statistical investigation. First, we will determine which/how many absorption-line systems are intrinsic through both partial covering methods and statistical assessments. Second, we will consider the incidence of intrinsic absorbers as a function of quasar property {e.g., radio-loudness, SED shape, black hole mass, bolometric luminosity}. This will reveal what determines the solid angle. This can only be done at moderate redshifts where quasars with a larger range of properties are observable, and hence requires HST/COS. Third, we will use the wide range of diagnostic lines to constrain the physical conditions of the absorbers. We will target the CIII*1175 complex and apply photoionization models to constrain the densities and ionization parameters. This will provide the largest set yet of intrinsic absorbers with systematic distance constraints. In tandem with the solid angles, this work will inform models regarding the geometry of quasar outflows.

  13. The geometry of musical chords.

    PubMed

    Tymoczko, Dmitri

    2006-07-01

    A musical chord can be represented as a point in a geometrical space called an orbifold. Line segments represent mappings from the notes of one chord to those of another. Composers in a wide range of styles have exploited the non-Euclidean geometry of these spaces, typically by using short line segments between structurally similar chords. Such line segments exist only when chords are nearly symmetrical under translation, reflection, or permutation. Paradigmatically consonant and dissonant chords possess different near-symmetries and suggest different musical uses.

  14. Worldsheet geometries of ambitwistor string

    NASA Astrophysics Data System (ADS)

    Ohmori, Kantaro

    2015-06-01

    Mason and Skinner proposed the ambitwistor string theory which directly reproduces the formulas for the amplitudes of massless particles proposed by Cachazo, He and Yuan. In this paper we discuss geometries of the moduli space of worldsheets associated to the bosonic or the RNS ambitwistor string. Further, we investigate the factorization properties of the amplitudes when an internal momentum is near on-shell in the abstract CFT language. Along the way, we propose the existence of the ambitwistor strings with three or four fermionic worldsheet currents.

  15. Emergent Calabi-Yau geometry.

    PubMed

    Ooguri, Hirosi; Yamazaki, Masahito

    2009-04-24

    We show how the smooth geometry of Calabi-Yau manifolds emerges from the thermodynamic limit of the statistical mechanical model of crystal melting defined in our previous paper. In particular, the thermodynamic partition function of molten crystals is shown to be equal to the classical limit of the partition function of the topological string theory by relating the Ronkin function of the characteristic polynomial of the crystal melting model to the holomorphic 3-form on the corresponding Calabi-Yau manifold. PMID:19518695

  16. Exceptional geometry and Borcherds superalgebras

    NASA Astrophysics Data System (ADS)

    Palmkvist, Jakob

    2015-11-01

    We study generalized diffeomorphisms in exceptional geometry with U-duality group E n( n) from an algebraic point of view. By extending the Lie algebra {e}_n to an infinite-dimensional Borcherds superalgebra, involving also the extension to {e}_{n+1} , the generalized Lie derivatives can be expressed in a simple way, and the expressions take the same form for any n ≤ 7. The closure of the transformations then follows from the Jacobi identity and the grading of {e}_{n+1} with respect to {e}_n.

  17. Teaching Geometry: An Experiential and Artistic Approach.

    ERIC Educational Resources Information Center

    Ogletree, Earl J.

    The view that geometry should be taught at every grade level is promoted. Primary and elementary school children are thought to rarely have any direct experience with geometry, except on an incidental basis. Children are supposed to be able to learn geometry rather easily, so long as the method and content are adapted to their development and…

  18. Preservice Primary School Teachers' Elementary Geometry Knowledge

    ERIC Educational Resources Information Center

    Marchis, Iuliana

    2012-01-01

    Geometrical notions and properties occur in real-world problems, thus Geometry has an important place in school Mathematics curricula. Primary school curricula lays the foundation of Geometry knowledge, pupils learn Geometry notions and properties by exploring their environment. Thus it is very important that primary school teachers have a good…

  19. Geometry in the Early Years: A Commentary

    ERIC Educational Resources Information Center

    Dindyal, Jaguthsing

    2015-01-01

    The primary goal of this paper is to provide a commentary on the teaching and learning of geometry in the early years of schooling with the set of papers in this issue as a guiding factor. It is structured around issues about geometry education of young learners, such as: what should we teach in geometry and why; representation of geometrical…

  20. Engaging All Students with "Impossible Geometry"

    ERIC Educational Resources Information Center

    Wiest, Lynda R.; Ayebo, Abraham; Dornoo, Michael D.

    2010-01-01

    Geometry is an area in which Australian students performed particularly poorly on the 2007 Trends in International Mathematics and Science Study (TIMSS). One innovative area of recreational geometry that has rich potential to engage and challenge a wide variety of students is "impossible geometry." An impossible geometric object is a…

  1. Geometry: Career Related Units. Teacher's Edition.

    ERIC Educational Resources Information Center

    Pierro, Mike; And Others

    Using six geometry units as resource units, the document explores 22 math-related careers. The authors intend the document to provide senior high school students with career orientation and exploration experiences while they learn geometry skills. The units are to be considered as a part of a geometry course, not a course by themselves. The six…

  2. Millimeter-wave backscatter diagnostic for the study of short scale length plasma fluctuations (invited)

    SciTech Connect

    Rhodes, T. L.; Peebles, W. A.; Nguyen, X.; VanZeeland, M. A.; De Grassie, J. S.; Doyle, E. J.; Wang, G.; Zeng, L.

    2006-10-15

    The development, laboratory tests, and experimental results relating to a new high-k diagnostic technique for the study of short scale length turbulence are reported. The system is based on backscattering of a millimeter-wave (94 GHz) probe beam by density fluctuations within the plasma. This diagnostic has been fully integrated with an upgraded far-infrared forward scattering system on the DIII-D tokamak. The combined system monitors a broad turbulent spectral range from 0 to 40 cm{sup -1}. Short-scale (e.g., electron temperature gradient scale) modes as well as longer wavelength (e.g., ion temperature gradient and trapped electron mode scale) instabilities are simultaneously monitored to accurately characterize plasma turbulence. The backscattering geometry and innovative use of the second harmonic electron cyclotron resonance as an internal 'beam dump' allow detection of small level fluctuations at high k, while maximizing discrimination against the ubiquitous, larger level, low-k fluctuations.

  3. Brownian motion in Robertson-Walker spacetimes from electromagnetic vacuum fluctuations

    SciTech Connect

    Bessa, Carlos H. G.; Bezerra, V. B.; Ford, L. H.

    2009-06-15

    We consider the effects of the vacuum fluctuations of a quantized electromagnetic field on particles in an expanding universe. We find that these particles typically undergo Brownian motion and acquire a nonzero mean squared velocity that depends on the scale factor of the universe. This Brownian motion can be interpreted as due to noncancellation of anticorrelated vacuum fluctuations in the time-dependent background spacetime. Alternatively, one can interpret this effect as the particles acquiring energy from the background spacetime geometry, a phenomenon that cannot occur in a static spacetime. We treat several types of coupling between the electromagnetic field and the particles and several model universes. We also consider both free particles, which, on the average, move on geodesics, and particles in bound systems. There are significant differences between these two cases, which illustrates that nongeodesic motion alters the effects of the vacuum fluctuations. We discuss the possible applications of this Brownian motion effect to cosmological scenarios.

  4. Continental collisions and seismic signature

    NASA Astrophysics Data System (ADS)

    Meissner, R.; Wever, Th.; Sadowiak, P.

    1991-04-01

    Reflection seismics in compressional belts has revealed the structure of crustal shortening and thickening processes, showing complex patterns of indentation and interfingering of colliding crusts and subcrustal lithospheres. Generally, in the upper crust large zones of detachments develop, often showing duplexes and 'crocodile' structures. The lower crust from zones of active collision (e.g. Alps, Pyrenees) is characterized by strongly dipping reflections. The base of the crust with the Moho must be continuously equilibrating after orogenic collapse as areas of former continental collision exhibit flat Mohos and subhorizontal reflections. The depth to the Moho increases during collision and decreases after the onset of post-orogenic extension, until finally the crustal root disappears completely together with the erosion of the mountains. Processes, active during continental collisions and orogenic collapse, create distinct structures which are imaged by reflection seismic profiling. Examples are shown and discussed.

  5. Milky Way's Head On Collision

    NASA Video Gallery

    This animation depicts the collision between our Milky Way galaxy and the Andromeda galaxy. Hubble Space Telescope observations indicate that the two galaxies, pulled together by their mutual gravi...

  6. Theoretical studies of molecular collisions

    NASA Technical Reports Server (NTRS)

    Kouri, Donald J.

    1991-01-01

    The following subject areas are covered: (1) total integral reactive cross sections and vibrationally resolved reaction probabilities for F + H2 = HF + H; (2) a theoretical study of inelastic O + N2 collisions; (3) body frame close coupling wave packet approach to gas phase atom-rigit rotor inelastic collisions; (4) wave packet study of gas phase atom-rigit motor scattering; (5) the application of optical potentials for reactive scattering; (6) time dependent, three dimensional body frame quantal wave packet treatment of the H + H2 exchange reaction; (7) a time dependent wave packet approach to atom-diatom reactive collision probabilities; (8) time dependent wave packet for the complete determination of s-matrix elements for reactive molecular collisions in three dimensions; (9) a comparison of three time dependent wave packet methods for calculating electron-atom elastic scattering cross sections; and (10) a numerically exact full wave packet approach to molecule-surface scattering.

  7. Centrality dependence of high-p(T) hadron suppression in Au+Au collisions at sqrt[s(NN)]=130 GeV.

    PubMed

    Adler, C; Ahammed, Z; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Caines, H; Calderón de la Barca Sánchez, M; Cardenas, A; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Deng, W S; Derevschikov, A A; Didenko, L; Dietel, T; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Filimonov, K; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Grachov, O; Grigoriev, V; Guedon, M; Gushin, E; Hallman, T J; Hardtke, D; Harris, J W; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Humanic, T J; Igo, G; Ishihara, A; Ivanshin, Yu I; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lakehal-Ayat, L; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; LoCurto, G; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Majka, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mitchell, J; Moiseenko, V A; Moore, C F; Morozov, V; de Moura, M M; Munhoz, M G; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Rykov, V; Sakrejda, I; Salur, S; Sandweiss, J; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schüttauf, A; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimanskii, S S; Shvetcov, V S; Skoro, G; Smirnov, N; Snellings, R; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thomas, J H; Thompson, M; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasilevski, I M; Vasiliev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, W M; Zoulkarneev, R; Zubarev, A N

    2002-11-11

    Inclusive transverse momentum distributions of charged hadrons within 0.2collisions at sqrt[s(NN)]=130 GeV. Hadron yields are suppressed at high p(T) in central collisions relative to peripheral collisions and to a nucleon-nucleon reference scaled for collision geometry. Peripheral collisions are not suppressed relative to the nucleon-nucleon reference. The suppression varies continuously at intermediate centralities. The results indicate significant nuclear medium effects on high-p(T) hadron production in heavy-ion collisions at high energy. PMID:12443470

  8. Geometry of modified Newtonian dynamics

    NASA Astrophysics Data System (ADS)

    Skordis, Constantinos; Zlosnik, Tom

    2012-02-01

    Modified Newtonian dynamics is an empirical modification to Poisson’s equation which has had success in accounting for the “gravitational field” Φ in a variety of astrophysical systems. The field Φ may be interpreted in terms of the weak-field limit of a variety of spacetime geometries. Here we consider three of these geometries in a more comprehensive manner and look at the effect on timelike and null geodesics. In particular we consider the aquadratic Lagrangian (AQUAL) theory, tensor-vector-scalar (TeVeS) theory and generalized Einstein-aether theory. We uncover a number of novel features, some of which are specific to the theory considered while others are generic. In the case of AQUAL and TeVeS theories, the spacetime exhibits an excess (AQUAL) or deficit TeVeS solid angle akin to the case of a Barriola-Vilenkin global monopole. In the case of generalized Einstein-aether, a disformal symmetry of the action emerges in the limit of ∇→Φ→0. Finally, in all theories studied, massive particles can never reach spatial infinity while photons can do so only after experiencing infinite redshift.

  9. Quanta of geometry: noncommutative aspects.

    PubMed

    Chamseddine, Ali H; Connes, Alain; Mukhanov, Viatcheslav

    2015-03-01

    In the construction of spectral manifolds in noncommutative geometry, a higher degree Heisenberg commutation relation involving the Dirac operator and the Feynman slash of real scalar fields naturally appears and implies, by equality with the index formula, the quantization of the volume. We first show that this condition implies that the manifold decomposes into disconnected spheres, which will represent quanta of geometry. We then refine the condition by involving the real structure and two types of geometric quanta, and show that connected spin manifolds with large quantized volume are then obtained as solutions. The two algebras M_{2}(H) and M_{4}(C) are obtained, which are the exact constituents of the standard model. Using the two maps from M_{4} to S^{4} the four-manifold is built out of a very large number of the two kinds of spheres of Planckian volume. We give several physical applications of this scheme such as quantization of the cosmological constant, mimetic dark matter, and area quantization of black holes. PMID:25793795

  10. Turbine engine variable geometry device

    NASA Technical Reports Server (NTRS)

    Rogo, Casimir (Inventor); Lenz, Herman N. (Inventor)

    1985-01-01

    A variable geometry device for use with the turbine nozzle of a turbine engine of the type having a support housing and a combustion chamber contained within the support housing. A pair of spaced walls in the support housing define an annular and radially extending nozzle passageway. The outer end of the nozzle passageway is open to the combustion chamber while the inner end of the nozzle passageway is open to one or more turbine stages. A plurality of circumferentially spaced nozzle vanes are mounted to one of the spaced walls and protrude across the nozzle passageway. An annular opening is formed around the opposite spaced wall and an annular ring is axially slidably mounted within the opening. A motor is operatively connected to this ring and, upon actuation, axially displaces the ring within the nozzle passageway. In addition, the ring includes a plurality of circumferentially spaced slots which register with the nozzle vanes so that the vane geometry remains the same despite axial displacement of the ring.

  11. Interactive rendering of dynamic geometry.

    PubMed

    Ponchio, Federico; Hormann, Kai

    2008-01-01

    Fluid simulations typically produce complex three-dimensional (3D) isosurfaces whose geometry and topology change over time. The standard way of representing such "dynamic geometry" is by a set of isosurfaces that are extracted individually at certain time steps. An alternative strategy is to represent the whole sequence as a four-dimensional (4D) tetrahedral mesh. The iso-surface at a specific time step can then be computed by intersecting the tetrahedral mesh with a 3D hyperplane. This not only allows the animation of the surface continuously over time without having to worry about the topological changes, but also enables simplification algorithms to exploit temporal coherence. We show how to interactively render such 4D tetrahedral meshes by improving previous GPU-accelerated techniques and building an out-of-core multi-resolution structure based on quadric error simplification. As a second application, we apply our framework to time-varying surfaces that result from morphing one triangle mesh into another. PMID:18467764

  12. Geometry and the quantum: basics

    NASA Astrophysics Data System (ADS)

    Chamseddine, Ali H.; Connes, Alain; Mukhanov, Viatcheslav

    2014-12-01

    Motivated by the construction of spectral manifolds in noncommutative geometry, we introduce a higher degree Heisenberg commutation relation involving the Dirac operator and the Feynman slash of scalar fields. This commutation relation appears in two versions, one sided and two sided. It implies the quantization of the volume. In the one-sided case it implies that the manifold decomposes into a disconnected sum of spheres which will represent quanta of geometry. The two sided version in dimension 4 predicts the two algebras M 2(ℍ) and M 4(ℂ) which are the algebraic constituents of the Standard Model of particle physics. This taken together with the non-commutative algebra of functions allows one to reconstruct, using the spectral action, the Lagrangian of gravity coupled with the Standard Model. We show that any connected Riemannian Spin 4-manifold with quantized volume > 4 (in suitable units) appears as an irreducible representation of the two-sided commutation relations in dimension 4 and that these representations give a seductive model of the "particle picture" for a theory of quantum gravity in which both the Einstein geometric standpoint and the Standard Model emerge from Quantum Mechanics. Physical applications of this quantization scheme will follow in a separate publication.

  13. Neuronal activity controls transsynaptic geometry

    PubMed Central

    Glebov, Oleg O.; Cox, Susan; Humphreys, Lawrence; Burrone, Juan

    2016-01-01

    The neuronal synapse is comprised of several distinct zones, including presynaptic vesicle zone (SVZ), active zone (AZ) and postsynaptic density (PSD). While correct relative positioning of these zones is believed to be essential for synaptic function, the mechanisms controlling their mutual localization remain unexplored. Here, we employ high-throughput quantitative confocal imaging, super-resolution and electron microscopy to visualize organization of synaptic subdomains in hippocampal neurons. Silencing of neuronal activity leads to reversible reorganization of the synaptic geometry, resulting in a increased overlap between immunostained AZ and PSD markers; in contrast, the SVZ-AZ spatial coupling is decreased. Bayesian blinking and bleaching (3B) reconstruction reveals that the distance between the AZ-PSD distance is decreased by 30 nm, while electron microscopy shows that the width of the synaptic cleft is decreased by 1.1 nm. Our findings show that multiple aspects of synaptic geometry are dynamically controlled by neuronal activity and suggest mutual repositioning of synaptic components as a potential novel mechanism contributing to the homeostatic forms of synaptic plasticity. PMID:26951792

  14. Alternative cosmology from cusp geometries

    NASA Astrophysics Data System (ADS)

    Rosa, Reinaldo; Herbin Stalder Díaz, Diego

    We study an alternative geometrical approach on the problem of classical cosmological singularity. It is based on a generalized function f(x,y)=x(2+y^2=(1-z)z^n) which consists of a cusped projected coupled isosurface. Such a projected geometry is computed and analized into the context of Friedmann singularity-free cosmology where a pre-big bang scenario is considered. Assuming that the mechanism of cusp formation is described by non-linear oscillations of a pre- big bang extended very high energy density field (>3x10^{94} kg/m^3$), we show that the action under the gravitational field follows a tautochrone of revolution, understood here as the primary projected geometry that alternatively replaces the Friedmann singularity in the standard big bang theory. As shown here this new approach allows us to interpret the nature of both matter and dark energy from first geometric principles [1]. [1] Rosa et al. DOI: 10.1063/1.4756991

  15. Fuzzy Logic for Incidence Geometry

    PubMed Central

    2016-01-01

    The paper presents a mathematical framework for approximate geometric reasoning with extended objects in the context of Geography, in which all entities and their relationships are described by human language. These entities could be labelled by commonly used names of landmarks, water areas, and so forth. Unlike single points that are given in Cartesian coordinates, these geographic entities are extended in space and often loosely defined, but people easily perform spatial reasoning with extended geographic objects “as if they were points.” Unfortunately, up to date, geographic information systems (GIS) miss the capability of geometric reasoning with extended objects. The aim of the paper is to present a mathematical apparatus for approximate geometric reasoning with extended objects that is usable in GIS. In the paper we discuss the fuzzy logic (Aliev and Tserkovny, 2011) as a reasoning system for geometry of extended objects, as well as a basis for fuzzification of the axioms of incidence geometry. The same fuzzy logic was used for fuzzification of Euclid's first postulate. Fuzzy equivalence relation “extended lines sameness” is introduced. For its approximation we also utilize a fuzzy conditional inference, which is based on proposed fuzzy “degree of indiscernibility” and “discernibility measure” of extended points. PMID:27689133

  16. Weyl gravity and Cartan geometry

    NASA Astrophysics Data System (ADS)

    Attard, J.; François, J.; Lazzarini, S.

    2016-04-01

    We point out that the Cartan geometry known as the second-order conformal structure provides a natural differential geometric framework underlying gauge theories of conformal gravity. We are concerned with two theories: the first one is the associated Yang-Mills-like Lagrangian, while the second, inspired by [1], is a slightly more general one that relaxes the conformal Cartan geometry. The corresponding gauge symmetry is treated within the Becchi-Rouet-Stora-Tyutin language. We show that the Weyl gauge potential is a spurious degree of freedom, analogous to a Stueckelberg field, that can be eliminated through the dressing field method. We derive sets of field equations for both the studied Lagrangians. For the second one, they constrain the gauge field to be the "normal conformal Cartan connection.''Finally, we provide in a Lagrangian framework a justification of the identification, in dimension 4, of the Bach tensor with the Yang-Mills current of the normal conformal Cartan connection, as proved in [2].

  17. Target Detection Using Fractal Geometry

    NASA Technical Reports Server (NTRS)

    Fuller, J. Joseph

    1991-01-01

    The concepts and theory of fractal geometry were applied to the problem of segmenting a 256 x 256 pixel image so that manmade objects could be extracted from natural backgrounds. The two most important measurements necessary to extract these manmade objects were fractal dimension and lacunarity. Provision was made to pass the manmade portion to a lookup table for subsequent identification. A computer program was written to construct cloud backgrounds of fractal dimensions which were allowed to vary between 2.2 and 2.8. Images of three model space targets were combined with these backgrounds to provide a data set for testing the validity of the approach. Once the data set was constructed, computer programs were written to extract estimates of the fractal dimension and lacunarity on 4 x 4 pixel subsets of the image. It was shown that for clouds of fractal dimension 2.7 or less, appropriate thresholding on fractal dimension and lacunarity yielded a 64 x 64 edge-detected image with all or most of the cloud background removed. These images were enhanced by an erosion and dilation to provide the final image passed to the lookup table. While the ultimate goal was to pass the final image to a neural network for identification, this work shows the applicability of fractal geometry to the problems of image segmentation, edge detection and separating a target of interest from a natural background.

  18. Initial conditions dependency in heavy-quarks suppression in ultra-relativistic collisions

    SciTech Connect

    Alves Garcia Prado, Caio; Alarcon do Passo Suaide, Alexandre

    2013-05-06

    Heavy quark suppression in central Au+Au collisions is expected to be smaller than that of light quarks. However experimental data suggest that they are evenly suppressed. We propose considering fluctuations in the medium as they may lead to high-density regions which in turn can cause a considerable quark suppression at the early stages of the collision evolution. To analyse the overall effect of these fluctuations we perform computer simulations of charm and bottom propagating through the quark-gluon plasma and obtain estimates of the nuclear modification factor R{sub AA}. This quantity gives us information about the heavy quark suppression that can be compared to published experimental data from the STAR experiment.

  19. Hidden geometry of traffic jamming

    NASA Astrophysics Data System (ADS)

    Andjelković, Miroslav; Gupte, Neelima; Tadić, Bosiljka

    2015-05-01

    We introduce an approach based on algebraic topological methods that allow an accurate characterization of jamming in dynamical systems with queues. As a prototype system, we analyze the traffic of information packets with navigation and queuing at nodes on a network substrate in distinct dynamical regimes. A temporal sequence of traffic density fluctuations is mapped onto a mathematical graph in which each vertex denotes one dynamical state of the system. The coupling complexity between these states is revealed by classifying agglomerates of high-dimensional cliques that are intermingled at different topological levels and quantified by a set of geometrical and entropy measures. The free-flow, jamming, and congested traffic regimes result in graphs of different structure, while the largest geometrical complexity and minimum entropy mark the edge of the jamming region.

  20. Fluctuations and discreteness in diffusion limited growth

    NASA Astrophysics Data System (ADS)

    Devita, Jason P.

    This thesis explores the effects of fluctuations and discreteness on the growth of physical systems where diffusion plays an important role. It focuses on three related problems, all dependent on diffusion in a fundamental way, but each with its own unique challenges. With diffusion-limited aggregation (DLA), the relationship between noisy and noise-free Laplacian growth is probed by averaging the results of noisy growth. By doing so in a channel geometry, we are able to compare to known solutions of the noise-free problem. We see that while the two are comparable, there are discrepancies which are not well understood. In molecular beam epitaxy (MBE), we create efficient computational algorithms, by replacing random walkers (diffusing atoms) with approximately equivalent processes. In one case, the atoms are replaced by a continuum field. Solving for the dynamics of the field yields---in an average sense---the dynamics of the atoms. In the other case, the atoms are treated as individual random-walking particles, but the details of the dynamics are changed to an (approximately) equivalent set of dynamics. This approach involves allowing adatoms to take long hops. We see approximately an order of magnitude speed up for simulating island dynamics, mound growth, and Ostwald ripening. Some ideas from the study of MBE are carried over to the study of front propagation in reaction-diffusion systems. Many of the analytic results about front propagation are derived from continuum models. It is unclear, however, that these results accurately describe the properties of a discrete system. It is reasonable to think that discrete systems will converge to the continuum results when sufficiently many particles are included. However, computational evidence of this is difficult to obtain, since the interesting properties tend to depend on a power law of the logarithm of the number of particles. Thus, the number of particles included in simulations must be exceedingly large. By

  1. Fluctuations in Urban Traffic Networks

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Dong; Li, Li; Zhang, Yi; Hu, Jian-Ming; Jin, Xue-Xiang

    Urban traffic network is a typical complex system, in which movements of tremendous microscopic traffic participants (pedestrians, bicyclists and vehicles) form complicated spatial and temporal dynamics. We collected flow volumes data on the time-dependent activity of a typical urban traffic network, finding that the coupling between the average flux and the fluctuation on individual links obeys a certain scaling law, with a wide variety of scaling exponents between 1/2 and 1. These scaling phenomena can explain the interaction between the nodes' internal dynamics (i.e. queuing at intersections, car-following in driving) and changes in the external (network-wide) traffic demand (i.e. the every day increase of traffic amount during peak hours and shocking caused by traffic accidents), allowing us to further understand the mechanisms governing the transportation system's collective behavior. Multiscaling and hotspot features are observed in the traffic flow data as well. But the reason why the separated internal dynamics are comparable to the external dynamics in magnitude is still unclear and needs further investigations.

  2. Measuring shape fluctuations in biological membranes

    NASA Astrophysics Data System (ADS)

    Monzel, C.; Sengupta, K.

    2016-06-01

    Shape fluctuations of lipid membranes have intrigued cell biologists and physicists alike. In the cellular context, their origin—thermal or active—and their physiological significance are open questions. These small incessant displacements, also called membrane undulations, have mostly been studied in model membranes and membranes of simple cells like erythrocytes. Thermal fluctuations of such membranes have been very well described both theoretically and experimentally; active fluctuations are a topic of current interest. Experimentally, membrane fluctuations are not easy to measure, the main challenge being to develop techniques which are capable of measuring very small displacements at very high speed, and preferably over a large area and long time. Scattering techniques have given access to fluctuations in membrane stacks and a variety of optical microscopy based techniques have been devised to study membrane fluctuations of unilamellar vesicles, erythrocytes and other cells. Among them are flicker spectroscopy, dynamic light scattering, diffraction phase microscopy and reflection interference contrast microscopy. Each of these techniques has its advantages and limitations. Here we review the basic principles of the major experimental techniques used to measure bending or shape fluctuations of biomembranes. We report seminal results obtained with each technique and highlight how these studies furthered our understanding of physical properties of membranes and their interactions. We also discuss suggested role of membrane fluctuations in different biological processes.

  3. Fluctuation theorem and mesoscopic chemical clocks.

    PubMed

    Andrieux, David; Gaspard, Pierre

    2008-04-21

    The fluctuation theorems for dissipation and the currents are applied to the stochastic version of the reversible Brusselator model of nonequilibrium oscillating reactions. It is verified that the symmetry of these theorems holds far from equilibrium in the regimes of noisy oscillations. Moreover, the fluctuation theorem for the currents is also verified for a truncated Brusselator model. PMID:18433234

  4. Fluctuation theorem and mesoscopic chemical clocks

    NASA Astrophysics Data System (ADS)

    Andrieux, David; Gaspard, Pierre

    2008-04-01

    The fluctuation theorems for dissipation and the currents are applied to the stochastic version of the reversible Brusselator model of nonequilibrium oscillating reactions. It is verified that the symmetry of these theorems holds far from equilibrium in the regimes of noisy oscillations. Moreover, the fluctuation theorem for the currents is also verified for a truncated Brusselator model.

  5. A Hydrodynamic Analysis of Collective Flow in Heavy-Ion Collisions

    NASA Astrophysics Data System (ADS)

    Yan, Li

    Recent progress in the hydrodynamic simulation of heavy-ion collisions have characterized the fluctuating initial state and the viscous corrections to the corresponding collective flow. These fluctuations naturally explain the "ridge" and "shoulder" structure of the measured two-particle correlation functions at RHIC and the LHC. We introduce a cumulant expansion for analyzing the azimuthal fluctuations in the initial state. The cumulant definitions systematically describe the azimuthal anisotropy order by order. In particular, the dipole asymmetry epsilon 1 appears at third order in the expansion, and the response to this initial fluctuation produces a radipity even dipole flow v 1, which has been subsequently confirmed by experiment. In addition, the cumulant expansion organizes the study of the nonlinear response to the initial conditions. The linear and nonlinear response coefficients to a given initial state were calculated with ideal and viscous hydrodynamic simulations. The collective flow is generated either linearly or nonlinearly, and the relative contribution of these two mechanisms to the observed flow pattern is calculated as a function of harmonic order, collision centrality, and the shear viscosity. For non-central collisions and high harmonic orders n ≥ 4, the nonlinear response is the dominant mechanism. This result is also seen in event-by-event hydrodynamic simulations. Using the cumulant expansion and the corresponding linear and nonlinear response coefficients, we determine the event plane correlations and compare to first measurements of this type. The observed event plane correlations are rooted in the initial state participant plane correlations, but a large fraction of the observed correlations are determined by harmonic mixing during the bulk expansion. Viscous corrections to the hydrodynamic formulation of collective flow are reflected in hydrodynamic equations of motion, as well as the correction to the distribution function at freeze

  6. Determination of freeze-out conditions from fluctuations in the Hadron Resonance Gas model

    NASA Astrophysics Data System (ADS)

    Alba, P.; Alberico, W.; Bellwied, R.; Bluhm, M.; Mantovani Sarti, V.; Nahrgang, M.; Ratti, C.

    2015-04-01

    Fluctuations of conserved charges measured in Heavy-Ion Collisions (HICs) received increasing attention in recent years, because they are good candidates to explore the phase diagram of QCD matter. During the last year, net-electric charge and net-proton moments of multiplicities measured at RHIC have been published by the STAR collaboration, for a range of collision energies which spans a region of the phase diagram at finite chemical potential. Here we present a new freeze-out curve obtained using the Hadron Resonance Gas (HRG) model approach to fit these experimental data. The HRG model is modified in order to have a realistic description of the HICs: kinematic cuts, resonance feed-down and resonance regeneration are taken into account. Our result is in agreement with preliminary studies by the ALICE collaboration, and is supported by a recent lattice analysis of the same quantities.

  7. Force fluctuations in three-dimensional suspended fibroblasts

    PubMed Central

    Schlosser, Florian; Rehfeldt, Florian; Schmidt, Christoph F.

    2015-01-01

    Cells are sensitive to mechanical cues from their environment and at the same time generate and transmit forces to their surroundings. To test quantitatively forces generated by cells not attached to a substrate, we used a dual optical trap to suspend 3T3 fibroblasts between two fibronectin-coated beads. In this simple geometry, we measured both the cells' elastic properties and the force fluctuations they generate with high bandwidth. Cell stiffness decreased substantially with both myosin inhibition by blebbistatin and serum-starvation, but not with microtubule depolymerization by nocodazole. We show that cortical forces generated by non-muscle myosin II deform the cell from its rounded shape in the frequency regime from 0.1 to 10 Hz. The amplitudes of these forces were strongly reduced by blebbistatin and serum starvation, but were unaffected by depolymerization of microtubules. Force fluctuations show a spectrum that is characteristic for an elastic network activated by random sustained stresses with abrupt transitions. PMID:25533089

  8. Correlated fluctuations near the QCD critical point

    NASA Astrophysics Data System (ADS)

    Jiang, Lijia; Li, Pengfei; Song, Huichao

    2016-08-01

    In this article, we introduce a freeze-out scheme for the dynamical models near the QCD critical point through coupling the decoupled classical particles with the order parameter field. With a modified distribution function that satisfies specific static fluctuations, we calculate the correlated fluctuations of net protons on the hydrodynamic freeze-out surface. A comparison with recent STAR data shows that our model calculations could roughly reproduce energy-dependent cumulant C4 and κ σ2 of net protons through tuning the related parameters. However, the calculated C2 and C3 with both Poisson and binomial baselines are always above the experimental data due to the positive contributions from the static critical fluctuations. To qualitatively and quantitatively describe all the related experimental data, the dynamical critical fluctuations and more realistic noncritical fluctuation baselines should be investigated in the near future.

  9. Magnetic Fluctuations in the Martian Ionosphere

    NASA Technical Reports Server (NTRS)

    Espley, Jared

    2010-01-01

    The Martian ionosphere is influenced by both the solar wind and the regional magnetic fields present in the Martian crust. Both influences ought to cause time variable changes in the magnetic fields present in the ionosphere. I report observations of these magnetic field fluctuations in the Martian ionosphere. I use data from the Mars Global Surveyor magnetometer instrument. By using data from the aerobraking low altitude passes (approx. 200 km) I find that there are numerous fluctuations both near and far from the strong crustal sources. Using data from the 400 km altitude mapping phase (which is near the topside of the primary ionosphere), I look at the comparative strength of the fluctuations relative to the solar wind and temporal variations. I discuss which wave modes and instabilities could be contributing to these fluctuations. I also discuss the implications of these fluctuations for understanding energy transfer in the Martian system and the effects on atmospheric escape.

  10. Solar wind thermally induced magnetic fluctuations.

    PubMed

    Navarro, R E; Moya, P S; Muñoz, V; Araneda, J A; F-Viñas, A; Valdivia, J A

    2014-06-20

    A kinetic description of Alfvén-cyclotron magnetic fluctuations for anisotropic electron-proton quasistable plasmas is studied. An analytical treatment, based on the fluctuation-dissipation theorem, consistently shows that spontaneous fluctuations in plasmas with stable distributions significantly contribute to the observed magnetic fluctuations in the solar wind, as seen, for example, in [S. D. Bale et al., Phys. Rev. Lett. 103, 211101 (2009)], even far below from the instability thresholds. Furthermore, these results, which do not require any adjustable parameters or wave excitations, are consistent with the results provided by hybrid simulations. It is expected that this analysis contributes to our understanding of the nature of magnetic fluctuations in the solar wind.

  11. Homeostatic Fluctuations of a Tissue Surface

    NASA Astrophysics Data System (ADS)

    Risler, Thomas; Peilloux, Aurélien; Prost, Jacques

    2015-12-01

    We study the surface fluctuations of a tissue with a dynamics dictated by cell-rearrangement, cell-division, and cell-death processes. Surface fluctuations are calculated in the homeostatic state, where cell division and cell death equilibrate on average. The obtained fluctuation spectrum can be mapped onto several other spectra such as those characterizing incompressible fluids, compressible Maxwell elastomers, or permeable membranes in appropriate asymptotic regimes. Since cell division and cell death are out-of-equilibrium processes, detailed balance is broken, but a generalized fluctuation-response relation is satisfied in terms of appropriate observables. Our work is a first step toward the description of the out-of-equilibrium fluctuations of the surface of a thick epithelium and its dynamical response to external perturbations.

  12. Thickness fluctuations in black lipid membranes.

    PubMed Central

    Hladky, S B; Gruen, D W

    1982-01-01

    Because a black lipid membrane is compressible, there will be spontaneous fluctuations in its thickness. Qualitative arguments are given that the preferred configuration of the membranes is flat and that thickness fluctuations are smaller in amplitude than the differences in mean thickness observed using different hydrocarbon solvents. Fluctuations with short characteristic lengths will not be large as a result of the large amounts of oil-water contact these would entail. Quantitative analysis based on an extension of the treatment for soap films, predicts that the root mean square (rms) amplitude for fluctuations of wavelength longer than approximately 10 nm is negligible for glyceryl monooleate membranes with squalene (less than 3%) but may be approximately 20% with n-decane. rms fluctuations of 20% would lead to a discrepancy between the rms thickness of the core and the mean reciprocal thickness of only 6%. PMID:7104437

  13. Spontaneous symmetry breaking at the fluctuating level.

    PubMed

    Hurtado, Pablo I; Garrido, Pedro L

    2011-10-28

    Phase transitions not allowed in equilibrium steady states may happen, however, at the fluctuating level. We observe for the first time this striking and general phenomenon measuring current fluctuations in an isolated diffusive system. While small fluctuations result from the sum of weakly correlated local events, for currents above a critical threshold the system self-organizes into a coherent traveling wave which facilitates the current deviation by gathering energy in a localized packet, thus breaking translation invariance. This results in Gaussian statistics for small fluctuations but non-Gaussian tails above the critical current. Our observations, which agree with predictions derived from hydrodynamic fluctuation theory, strongly suggest that rare events are generically associated with coherent, self-organized patterns which enhance their probability.

  14. Coupled Quantum Fluctuations and Quantum Annealing

    NASA Astrophysics Data System (ADS)

    Hormozi, Layla; Kerman, Jamie

    We study the relative effectiveness of coupled quantum fluctuations, compared to single spin fluctuations, in the performance of quantum annealing. We focus on problem Hamiltonians resembling the the Sherrington-Kirkpatrick model of Ising spin glass and compare the effectiveness of different types of fluctuations by numerically calculating the relative success probabilities and residual energies in fully-connected spin systems. We find that for a small class of instances coupled fluctuations can provide improvement over single spin fluctuations and analyze the properties of the corresponding class. Disclaimer: This research was funded by ODNI, IARPA via MIT Lincoln Laboratory under Air Force Contract No. FA8721-05-C-0002. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ODNI, IARPA, or the US Government.

  15. Computational Analysis of an effect of aerodynamic pressure on the side view mirror geometry

    NASA Astrophysics Data System (ADS)

    Murukesavan, P.; Mu'tasim, M. A. N.; Sahat, I. M.

    2013-12-01

    This paper describes the evaluation of aerodynamic flow effects on side mirror geometry for a passenger car using ANSYS Fluent CFD simulation software. Results from analysis of pressure coefficient on side view mirror designs is evaluated to analyse the unsteady forces that cause fluctuations to mirror surface and image blurring. The fluctuation also causes drag forces that increase the overall drag coefficient, with an assumption resulting in higher fuel consumption and emission. Three features of side view mirror design were investigated with two input velocity parameters of 17 m/s and 33 m/s. Results indicate that the half-sphere design shows the most effective design with less pressure coefficient fluctuation and drag coefficient.

  16. Forces and fluctuations in planar, spherical and tubular membranes

    NASA Astrophysics Data System (ADS)

    Barbetta, Camilla

    2010-11-01

    Lipid membranes constitute very particular materials: on the one hand, they break very easily under microscopical stretching; on the other hand, they are extremely flexible, presenting deformations even at small scales. Consequently, a piece of membrane has an area excess relative to its optically resolvable area, also called projected area. From a mechanical point of view, we can thus identify three tensions associated to lipid membranes: the mechanical effective tension τ, associated to an increase in the projected area and to the flattening of the fluctuations; the tension sigma, associated to the microscopical area of the membrane and thus non measurable, but commonly used in theoretical predictions; and its macroscopical counterpart measured through the fluctuation spectrum, r. Up to now, the equality between these quantities was taken for granted when analyzing experimental data. In this dissertation, we have studied, using the projected stress tensor, whether and under which conditions it is justified to assume τ = sigma. We studied three geometries (planar, spherical and cylindrical) and obtained the relation τ approx sigma - sigma_0, where sigma_0 is a constant depending only on the membrane's high frequency cutoff and on the temperature. Accordingly, we conclude that neglecting the difference between τ and sigma is justifiable only to membranes under large tensions: in the case of small tensions, corrections must be taken into account. We have studied the implications of this result to the interpretation of experiments involving membrane nanotubes. Regarding r, we have questioned a former demonstration concerning its equality with τ. Finally, the force fluctuation for planar membranes and membrane nanotubes was quantified for the first time.

  17. Differential Geometry Based Multiscale Models

    PubMed Central

    Wei, Guo-Wei

    2010-01-01

    Large chemical and biological systems such as fuel cells, ion channels, molecular motors, and viruses are of great importance to the scientific community and public health. Typically, these complex systems in conjunction with their aquatic environment pose a fabulous challenge to theoretical description, simulation, and prediction. In this work, we propose a differential geometry based multiscale paradigm to model complex macromolecular systems, and to put macroscopic and microscopic descriptions on an equal footing. In our approach, the differential geometry theory of surfaces and geometric measure theory are employed as a natural means to couple the macroscopic continuum mechanical description of the aquatic environment with the microscopic discrete atom-istic description of the macromolecule. Multiscale free energy functionals, or multiscale action functionals are constructed as a unified framework to derive the governing equations for the dynamics of different scales and different descriptions. Two types of aqueous macromolecular complexes, ones that are near equilibrium and others that are far from equilibrium, are considered in our formulations. We show that generalized Navier–Stokes equations for the fluid dynamics, generalized Poisson equations or generalized Poisson–Boltzmann equations for electrostatic interactions, and Newton's equation for the molecular dynamics can be derived by the least action principle. These equations are coupled through the continuum-discrete interface whose dynamics is governed by potential driven geometric flows. Comparison is given to classical descriptions of the fluid and electrostatic interactions without geometric flow based micro-macro interfaces. The detailed balance of forces is emphasized in the present work. We further extend the proposed multiscale paradigm to micro-macro analysis of electrohydrodynamics, electrophoresis, fuel cells, and ion channels. We derive generalized Poisson–Nernst–Planck equations that

  18. Differential geometry based multiscale models.

    PubMed

    Wei, Guo-Wei

    2010-08-01

    Large chemical and biological systems such as fuel cells, ion channels, molecular motors, and viruses are of great importance to the scientific community and public health. Typically, these complex systems in conjunction with their aquatic environment pose a fabulous challenge to theoretical description, simulation, and prediction. In this work, we propose a differential geometry based multiscale paradigm to model complex macromolecular systems, and to put macroscopic and microscopic descriptions on an equal footing. In our approach, the differential geometry theory of surfaces and geometric measure theory are employed as a natural means to couple the macroscopic continuum mechanical description of the aquatic environment with the microscopic discrete atomistic description of the macromolecule. Multiscale free energy functionals, or multiscale action functionals are constructed as a unified framework to derive the governing equations for the dynamics of different scales and different descriptions. Two types of aqueous macromolecular complexes, ones that are near equilibrium and others that are far from equilibrium, are considered in our formulations. We show that generalized Navier-Stokes equations for the fluid dynamics, generalized Poisson equations or generalized Poisson-Boltzmann equations for electrostatic interactions, and Newton's equation for the molecular dynamics can be derived by the least action principle. These equations are coupled through the continuum-discrete interface whose dynamics is governed by potential driven geometric flows. Comparison is given to classical descriptions of the fluid and electrostatic interactions without geometric flow based micro-macro interfaces. The detailed balance of forces is emphasized in the present work. We further extend the proposed multiscale paradigm to micro-macro analysis of electrohydrodynamics, electrophoresis, fuel cells, and ion channels. We derive generalized Poisson-Nernst-Planck equations that are

  19. Differential geometry based multiscale models.

    PubMed

    Wei, Guo-Wei

    2010-08-01

    Large chemical and biological systems such as fuel cells, ion channels, molecular motors, and viruses are of great importance to the scientific community and public health. Typically, these complex systems in conjunction with their aquatic environment pose a fabulous challenge to theoretical description, simulation, and prediction. In this work, we propose a differential geometry based multiscale paradigm to model complex macromolecular systems, and to put macroscopic and microscopic descriptions on an equal footing. In our approach, the differential geometry theory of surfaces and geometric measure theory are employed as a natural means to couple the macroscopic continuum mechanical description of the aquatic environment with the microscopic discrete atomistic description of the macromolecule. Multiscale free energy functionals, or multiscale action functionals are constructed as a unified framework to derive the governing equations for the dynamics of different scales and different descriptions. Two types of aqueous macromolecular complexes, ones that are near equilibrium and others that are far from equilibrium, are considered in our formulations. We show that generalized Navier-Stokes equations for the fluid dynamics, generalized Poisson equations or generalized Poisson-Boltzmann equations for electrostatic interactions, and Newton's equation for the molecular dynamics can be derived by the least action principle. These equations are coupled through the continuum-discrete interface whose dynamics is governed by potential driven geometric flows. Comparison is given to classical descriptions of the fluid and electrostatic interactions without geometric flow based micro-macro interfaces. The detailed balance of forces is emphasized in the present work. We further extend the proposed multiscale paradigm to micro-macro analysis of electrohydrodynamics, electrophoresis, fuel cells, and ion channels. We derive generalized Poisson-Nernst-Planck equations that are

  20. Particle rebound characteristics of turbomachinery cascade leading edge geometry

    NASA Astrophysics Data System (ADS)

    Siravuri, Sastri

    The objective of this research work is to investigate and understand the complex phenomena associated with the mechanism of particle impacts on turbomachinery cascade leading edge geometry. At present, there is a need for experimental work in basic and applied research to find out the parameters that are relevant to particle rebound characteristics on turbomachinery blades. In the present work, experiments were conducted with air velocity at 15 m/s (˜50 ft/sec) and at 30 m/s (˜100 ft/sec) using high-speed photography and Laser Doppler Velocimetry (LDV). Silica sand particles of 1000--1500 micron size were used for this study. In the present investigation, particle rebound data was obtained for cylindrical targets with radius of curvature representative of leading edge geometry (cylinder diameter = 4.5mm & 6.5 mm) using LDV. The numerical simulations, which are based on non-linear dynamic analysis, were also performed using the finite element code DYNA3-D. Several different material models viz elastic-elastic, elastic-plastic, elastic-plastic with friction & isotropic-elastic-plastic with dynamic friction and particle rotation were used in the DYNA3-D numerical analysis. The computational results include a time history of the displacement, stress and strain profiles through the particle collision. Numerical results are presented for the rebound conditions of spherical silica sand particle for different pre-collision velocities. The computed particle restitution coefficients, after they reach steady rebound conditions, are compared with experimental results obtained from LDV. A probabilistic model was developed to incorporate the uncertainties in the impact velocity in the numerical model. Histograms and Cumulative Distribution Functions (CDFs) for impact velocity were obtained from experimental LDV data. Ten randomly selected probabilities for each impact angle were used to calculate the impact velocity from cumulative distribution function. This randomly selected

  1. Cosmology for quadratic gravity in generalized Weyl geometry

    NASA Astrophysics Data System (ADS)

    Beltrán Jiménez, Jose; Heisenberg, Lavinia; Koivisto, Tomi S.

    2016-04-01

    A class of vector-tensor theories arises naturally in the framework of quadratic gravity in spacetimes with linear vector distortion. Requiring the absence of ghosts for the vector field imposes an interesting condition on the allowed connections with vector distortion: the resulting one-parameter family of connections generalises the usual Weyl geometry with polar torsion. The cosmology of this class of theories is studied, focusing on isotropic solutions wherein the vector field is dominated by the temporal component. De Sitter attractors are found and inhomogeneous perturbations around such backgrounds are analysed. In particular, further constraints on the models are imposed by excluding pathologies in the scalar, vector and tensor fluctuations. Various exact background solutions are presented, describing a constant and an evolving dark energy, a bounce and a self-tuning de Sitter phase. However, the latter two scenarios are not viable under a closer scrutiny.

  2. Fluctuating dimension in a discrete model for quantum gravity based on the spectral principle.

    PubMed

    de Albuquerque, Luiz C; deLyra, Jorge L; Teotonio-Sobrinho, Paulo

    2003-08-22

    The spectral principle of Connes and Chamseddine is used as a starting point to define a discrete model for Euclidean quantum gravity. Instead of summing over ordinary geometries, we consider the sum over generalized geometries where topology, metric, and dimension can fluctuate. The model describes the geometry of spaces with a countable number n of points, and is related to the Gaussian unitary ensemble of Hermitian matrices. We show that this simple model has two phases. The expectation value , the average number of points in the Universe, is finite in one phase and diverges in the other. We compute the critical point as well as the critical exponent of . Moreover, the space-time dimension delta is a dynamical observable in our model, and plays the role of an order parameter. The computation of is discussed and an upper bound is found, < 2.

  3. Interactive graphics for geometry modeling

    NASA Technical Reports Server (NTRS)

    Wozny, M. J.

    1984-01-01

    An interactive vector capability to create geometry and a raster color shaded rendering capability to sample and verify interim geometric design steps through color snapshots is described. The development is outlined of the underlying methodology which facilitates computer aided engineering and design. At present, raster systems cannot match the interactivity and line-drawing capability of refresh vector systems. Consequently, an intermediate step in mechanical design is used to create objects interactively on the vector display and then scan convert the wireframe model to render it as a color shaded object on a raster display. Several algorithms are presented for rendering such objects. Superquadric solid primitive extend the class of primitives normally used in solid modelers.

  4. Quantum gauge theories from geometry

    NASA Astrophysics Data System (ADS)

    Galehouse, Daniel C.

    2006-03-01

    Geometrical theories have been developed to describe quantum interacting particles with full mathematical covariance. They possess a sophisticated gauge structure that derives from the fundamental properties of the geometry. These theories are all implicitly quantized and come in three known types: Weyl, non-compactified Kaluza-Klein, and, as presented here, Dirac. The spin one-half particle is a conformal wave in an eight dimensional Riemannian space. The coordinates transform locally as spinors and project into space time to give the known gravitational and electromagnetic forces. The gauge structure of the weak interactions appears as well, as in this space the electron transforms into a neutrino under hyper-rotations. The possibility of including the strong interactions and the corresponding gauge system is discussed.

  5. Noncommutative Geometry and Basic Physics

    NASA Astrophysics Data System (ADS)

    Kastler, Daniel

    Alain Connes' noncommutative geometry, started in 1982 [0], widely developed in 1994 as expounded in his book at this date [0] (it has grown meanwhile) is a systematic quantization of mathematics parallel to the quantization of physics effected in the twenties.This theory widens the scope of mathematics in a manner congenial to physics, reorganizes the existing ("classical") mathematics of which it produces an hitherto unsuspected unification, and provides basic physics (the synthesis of elementary particles and gravitation) with a programme of renewal which has thus far achieved a clarification of the classical (tree-level) aspects of a new synthesis of the (Euclidean) standard model with gravitation [32],[33]: this is the subject of the present lectures - with the inherent tentative prediction of the Higgs mass.

  6. Geometry of discrete quantum computing

    NASA Astrophysics Data System (ADS)

    Hanson, Andrew J.; Ortiz, Gerardo; Sabry, Amr; Tai, Yu-Tsung

    2013-05-01

    Conventional quantum computing entails a geometry based on the description of an n-qubit state using 2n infinite precision complex numbers denoting a vector in a Hilbert space. Such numbers are in general uncomputable using any real-world resources, and, if we have the idea of physical law as some kind of computational algorithm of the universe, we would be compelled to alter our descriptions of physics to be consistent with computable numbers. Our purpose here is to examine the geometric implications of using finite fields Fp and finite complexified fields \\mathbf {F}_{p^2} (based on primes p congruent to 3 (mod4)) as the basis for computations in a theory of discrete quantum computing, which would therefore become a computable theory. Because the states of a discrete n-qubit system are in principle enumerable, we are able to determine the proportions of entangled and unentangled states. In particular, we extend the Hopf fibration that defines the irreducible state space of conventional continuous n-qubit theories (which is the complex projective space \\mathbf {CP}^{2^{n}-1}) to an analogous discrete geometry in which the Hopf circle for any n is found to be a discrete set of p + 1 points. The tally of unit-length n-qubit states is given, and reduced via the generalized Hopf fibration to \\mathbf {DCP}^{2^{n}-1}, the discrete analogue of the complex projective space, which has p^{2^{n}-1} (p-1)\\,\\prod _{k=1}^{n-1} ( p^{2^{k}}+1) irreducible states. Using a measure of entanglement, the purity, we explore the entanglement features of discrete quantum states and find that the n-qubit states based on the complexified field \\mathbf {F}_{p^2} have pn(p - 1)n unentangled states (the product of the tally for a single qubit) with purity 1, and they have pn + 1(p - 1)(p + 1)n - 1 maximally entangled states with purity zero.

  7. Changing the Structure Boundary Geometry

    SciTech Connect

    Karasev, Viktor; Dzlieva, Elena; Ivanov, Artyom

    2008-09-07

    Analysis of previously obtained results shows that hexagonal crystal lattice is the dominant type of ordering, in particular, in striated glow discharges. We explore the possibility for changing the dust distribution in horizontal cross sections of relatively highly ordered structures in a glow-discharge. Presuming that boundary geometry can affect dust distribution, we used cylindrical coolers held at 0 deg. C and placed against a striation containing a structure, to change the geometry of its outer boundary. By varying the number of coolers, their positions, and their separations from the tube wall, azimuthally asymmetric thermophoretic forces can be used to form polygonal boundaries and vary the angles between their segments (in a horizontal cross section). The corner in the structure's boundary of 60 deg. stimulates formation of hexagonal cells. The structure between the supported parallel boundaries is also characterized by stable hexagonal ordering. We found that a single linear boundary segment does not give rise to any sizable domain, but generates a lattice extending from the boundary (without edge defects). A square lattice can be formed by setting the angle equal to 90 deg. . However, angles of 45 deg. and 135 deg. turned out easier to form. Square lattice was created by forming a near-135 deg. corner with four coolers. It was noted that no grain ordering is observed in the region adjacent to corners of angles smaller than 30 deg. , which do not promote ordering into cells of any shape. Thus, manipulation of a structure boundary can be used to change dust distribution, create structures free of the ubiquitous edge defects that destroy orientation order, and probably change the crystal lattice type.

  8. Digital breast tomosynthesis geometry calibration

    NASA Astrophysics Data System (ADS)

    Wang, Xinying; Mainprize, James G.; Kempston, Michael P.; Mawdsley, Gordon E.; Yaffe, Martin J.

    2007-03-01

    Digital Breast Tomosynthesis (DBT) is a 3D x-ray technique for imaging the breast. The x-ray tube, mounted on a gantry, moves in an arc over a limited angular range around the breast while 7-15 images are acquired over a period of a few seconds. A reconstruction algorithm is used to create a 3D volume dataset from the projection images. This procedure reduces the effects of tissue superposition, often responsible for degrading the quality of projection mammograms. This may help improve sensitivity of cancer detection, while reducing the number of false positive results. For DBT, images are acquired at a set of gantry rotation angles. The image reconstruction process requires several geometrical factors associated with image acquisition to be known accurately, however, vibration, encoder inaccuracy, the effects of gravity on the gantry arm and manufacturing tolerances can produce deviations from the desired acquisition geometry. Unlike cone-beam CT, in which a complete dataset is acquired (500+ projections over 180°), tomosynthesis reconstruction is challenging in that the angular range is narrow (typically from 20°-45°) and there are fewer projection images (~7-15). With such a limited dataset, reconstruction is very sensitive to geometric alignment. Uncertainties in factors such as detector tilt, gantry angle, focal spot location, source-detector distance and source-pivot distance can produce several artifacts in the reconstructed volume. To accurately and efficiently calculate the location and angles of orientation of critical components of the system in DBT geometry, a suitable phantom is required. We have designed a calibration phantom for tomosynthesis and developed software for accurate measurement of the geometric parameters of a DBT system. These have been tested both by simulation and experiment. We will present estimates of the precision available with this technique for a prototype DBT system.

  9. Path Toward a Unifid Geometry for Radiation Transport

    NASA Technical Reports Server (NTRS)

    Lee, Kerry; Barzilla, Janet; Davis, Andrew; Zachmann

    2014-01-01

    The Direct Accelerated Geometry for Radiation Analysis and Design (DAGRAD) element of the RadWorks Project under Advanced Exploration Systems (AES) within the Space Technology Mission Directorate (STMD) of NASA will enable new designs and concepts of operation for radiation risk assessment, mitigation and protection. This element is designed to produce a solution that will allow NASA to calculate the transport of space radiation through complex computer-aided design (CAD) models using the state-of-the-art analytic and Monte Carlo radiation transport codes. Due to the inherent hazard of astronaut and spacecraft exposure to ionizing radiation in low-Earth orbit (LEO) or in deep space, risk analyses must be performed for all crew vehicles and habitats. Incorporating these analyses into the design process can minimize the mass needed solely for radiation protection. Transport of the radiation fields as they pass through shielding and body materials can be simulated using Monte Carlo techniques or described by the Boltzmann equation, which is obtained by balancing changes in particle fluxes as they traverse a small volume of material with the gains and losses caused by atomic and nuclear collisions. Deterministic codes that solve the Boltzmann transport equation, such as HZETRN [high charge and energy transport code developed by NASA Langley Research Center (LaRC)], are generally computationally faster than Monte Carlo codes such as FLUKA, GEANT4, MCNP(X) or PHITS; however, they are currently limited to transport in one dimension, which poorly represents the secondary light ion and neutron radiation fields. NASA currently uses HZETRN space radiation transport software, both because it is computationally efficient and because proven methods have been developed for using this software to analyze complex geometries. Although Monte Carlo codes describe the relevant physics in a fully three-dimensional manner, their computational costs have thus far prevented their

  10. Stochastic simulation of fluctuation stage of phase transfer on solid surface during thin film formation

    SciTech Connect

    Bondareva, A.L.; Zmievskaya, G.I.

    2005-05-16

    Ions irradiation leads to nano-scale islands of thin cover formation. Influence on a solid surface of the following processes: fluctuation stage of phase transition (new phase island formation), its migration under long-range potentials of interaction which leads to brownian motion of islands on the surface, inelastic collisions of islands has been simulated by stochastic analogue method. The calculated time evolution of islands kinetic distribution function from islands square sizes and coordinates of its masses centres on the surface is calculated taking into account non-linear Gibbs energy of islands formation, which depends on lattice elastic responses as well on dislocation influence.

  11. Effect of resonance decay on conserved number fluctuations in a hadron resonance gas model

    NASA Astrophysics Data System (ADS)

    Mishra, D. K.; Garg, P.; Netrakanti, P. K.; Mohanty, A. K.

    2016-07-01

    We study the effect of charged secondaries coming from resonance decay on the net-baryon, net-charge, and net-strangeness fluctuations in high-energy heavy-ion collisions within the hadron resonance gas (HRG) model. We emphasize the importance of including weak decays along with other resonance decays in the HRG, while comparing with the experimental observables. The effect of kinematic cuts on resonances and primordial particles on the conserved number fluctuations are also studied. The HRG model calculations with the inclusion of resonance decays and kinematical cuts are compared with the recent experimental data from STAR and PHENIX experiments. We find good agreement between our model calculations and the experimental measurements for both net-proton and net-charge distributions.

  12. Studies of fluctuation processes in nuclear collisions. Progress report, March 1, 1993--April 30, 1994

    SciTech Connect

    Ayik, S.

    1994-05-01

    This report summarizes the progress on grant No.FG05-89ER40530 during the period March 1, 1993 to April 30, 1994. By extending our previous work on the fluid dynamical treatment of the nuclear collective motion, we deduced from the Boltzmann-Langevin (BL) model a set of transport equations for N collective variables and calculated the associated transport coefficients. Work has also continued on investigating the relation between the BUU model and the BL model for the average evolution. The principle investigator spent a fruitful summer (1993) at LBL, where in collaboration with J. Raindrop, we developed a numerical method for simulating the stochastic evolution of the phase-space density near local equilibrium. Two papers have appeared in Phys. Rev. C and Nucl. Phys. A, two papers have been accepted for publication, both in Nucl. Phys. A, and two manuscripts have been submitted to Z. Phys. A for publication. Several seminars/contributed talks were given at various meetings and an invited talk was presented at the NATO Advanced Study Institution Hot and Dense Matter, Bodrum/Turkey.

  13. Reduction of discretization error for ray tracing of MOC through a correction on collision probabilities

    SciTech Connect

    Tabuchi, M.; Tatsumi, M.; Yamamoto, A.; Endo, T.

    2013-07-01

    A new correction model for ray tracing of the method of characteristics is proposed in order to reduce discretization error. As the ray tracing parameters such as azimuthal angle division, polar angle division and ray separation are considered in this study. In the method of characteristics, region average scalar fluxes can be implicitly expressed by collision probabilities, although these collision probabilities are not directly treated in the ordinary calculation scheme. From this viewpoint, difference between a coarse ray tracing condition and a detailed one can be interpreted as the difference in the estimation of collision probabilities. In other words, the discretization error for ray tracing can be recognized as a consequence of inaccurate collision probabilities caused by coarse ray tracing. This discussion suggests that accurate region average scalar flux can be obtained through an appropriate correction on collision probabilities. In this paper, a correction model on collision probabilities is theoretically derived based on the neutron balance equation, and its validity is confirmed through typical single assembly calculations. The effectiveness of the present correction method is also discussed in this paper. It is confirmed that discretization error for ray tracing can be significantly reduced by the present correction method in a multi-assembly calculation, though the correction factor is estimated in single assembly geometry. (authors)

  14. Neutrino propagation in a fluctuating sun

    SciTech Connect

    Burgess, C.P.; Michaud, D.

    1997-05-01

    We adapt to neutrino physics a general formulation for particle propagation in fluctuating media, initially developed for applications to electromagnetism and neutron optics. In leading approximation this formalism leads to the usual MSW effective Hamiltonian governing neutrino propagation through a medium. Next-to-leading contributions describe deviations from this description, which arise due to neutrino interactions with fluctuations in the medium. We compute these corrections for two types of fluctuations: (i) microscopic thermal fluctuations and (ii) macroscopic fluctuations in the medium{close_quote}s density. While the first of these reproduces standard estimates, which are negligible for applications to solar neutrinos, we find that the second can be quite large, since it grows in size with the correlation length of the fluctuation. We consider two models in some detail. For fluctuations whose correlations extend only over a local region in space of length l, appreciable effects for MSW oscillations arise if ({delta}n/n){sup 2}l{approx_gt}100m or so. Alternatively, a crude model of helioseismic p-waves gives appreciable effects only when ({delta}n/n){approx_gt}1{percent}. In general the dominant effect is to diminish the quality of the resonance, making the suppression of the {sup 7}Be neutrinos a good experimental probe of fluctuations deep within the sun. Fluctuations can also provide a new mechanism for reducing the solar neutrino flux, giving an energy-independent suppression factor of 1/2 away from the resonant region, even for small vacuum mixing angles. {copyright} 1997 Academic Press, Inc.

  15. Automatic Collision Avoidance Technology (ACAT)

    NASA Technical Reports Server (NTRS)

    Swihart, Donald E.; Skoog, Mark A.

    2007-01-01

    This document represents two views of the Automatic Collision Avoidance Technology (ACAT). One viewgraph presentation reviews the development and system design of Automatic Collision Avoidance Technology (ACAT). Two types of ACAT exist: Automatic Ground Collision Avoidance (AGCAS) and Automatic Air Collision Avoidance (AACAS). The AGCAS Uses Digital Terrain Elevation Data (DTED) for mapping functions, and uses Navigation data to place aircraft on map. It then scans DTED in front of and around aircraft and uses future aircraft trajectory (5g) to provide automatic flyup maneuver when required. The AACAS uses data link to determine position and closing rate. It contains several canned maneuvers to avoid collision. Automatic maneuvers can occur at last instant and both aircraft maneuver when using data link. The system can use sensor in place of data link. The second viewgraph presentation reviews the development of a flight test and an evaluation of the test. A review of the operation and comparison of the AGCAS and a pilot's performance are given. The same review is given for the AACAS is given.

  16. Propagation of the lower hybrid wave in a density fluctuating scrape-off layer (SOL)

    NASA Astrophysics Data System (ADS)

    Madi, M.; Peysson, Y.; Decker, J.; Kabalan, K. Y.

    2015-12-01

    The perturbation of the lower hybrid wave (LH) power spectrum by fluctuations of the plasma in the vicinity of the antenna is investigated by solving the full wave equation in a slab geometry using COMSOL Multiphysics®. The numerical model whose generality allows to study the effect of various types of fluctuations, including those with short characteristic wavelengths is validated against a coupling code in quiescent regimes. When electron density fluctuations along the toroidal direction are incorporated in the dielectric tensor over a thin perturbed layer in front of the grill, the power spectrum may be strongly modified from the antenna mouth to the plasma separatrix as the LH wave propagates. The diffraction effect by density fluctuations leads to the appearance of multiple satellite lobes with randomly varying positions and the averaged perturbation is found to be maximum for the Fourier components of the fluctuating spectrum in the vicinity of the launched LH wavelength. This highlights that fast toroidal inhomogeneities with short characteristics length scales in front of the grill may change significantly the initial LH power spectrum used in coupled ray-tracing and Fokker-Planck calculations.

  17. Geometries of Karman Vortex Street

    NASA Astrophysics Data System (ADS)

    Roushan, Pedram; Wu, X. L.

    2004-03-01

    The Bénard-von Kármán vortex street is studied in a flowing soap film channel. The two-dimensional fluid flow in the film allows stable vortex streets to be generated and investigated over a broad range of Reynolds numbers, 10fluctuations beneath the rod. This simple model not only explains the near wake shape of the street, but also allows other useful information such as the kinetic energy injected into the fluid and the drag coefficient CD to be extracted.

  18. On the fluctuation induced mass enhancement

    NASA Astrophysics Data System (ADS)

    Van Hoa, Nguyen; Tuan, Vu Ngoc; Van Xuan, Le; Lan, Nguyen Tri; Viet, Nguyen Ai

    2016-06-01

    The effective mass induced by the background fluctuation on particles is considered. The analytical results show that the effective mass depends only on the properties of fluctuation, and takes non-zero value when and only when fluctuation mean value is non-zero. The possible applications of the obtained results to complex systems such as biology and ecology where environmental factors lead to the changes of the information exchange ranges from long to short one are discussed, i.e. the possibility of using physical modeling techniques to investigate macroscopic behaviors of some complex systems under consideration.

  19. Statistical regimes of random laser fluctuations

    SciTech Connect

    Lepri, Stefano; Cavalieri, Stefano; Oppo, Gian-Luca; Wiersma, Diederik S.

    2007-06-15

    Statistical fluctuations of the light emitted from amplifying random media are studied theoretically and numerically. The characteristic scales of the diffusive motion of light lead to Gaussian or power-law (Levy) distributed fluctuations depending on external control parameters. In the Levy regime, the output pulse is highly irregular leading to huge deviations from a mean-field description. Monte Carlo simulations of a simplified model which includes the population of the medium demonstrate the two statistical regimes and provide a comparison with dynamical rate equations. Different statistics of the fluctuations helps to explain recent experimental observations reported in the literature.

  20. Nonisothermal fluctuating hydrodynamics and Brownian motion

    NASA Astrophysics Data System (ADS)

    Falasco, G.; Kroy, K.

    2016-03-01

    The classical theory of Brownian dynamics follows from coarse graining the underlying linearized fluctuating hydrodynamics of the solvent. We extend this procedure to globally nonisothermal conditions, requiring only a local thermal equilibration of the solvent. Starting from the conservation laws, we establish the stochastic equations of motion for the fluid momentum fluctuations in the presence of a suspended Brownian particle. These are then contracted to the nonisothermal generalized Langevin description of the suspended particle alone, for which the coupling to stochastic temperature fluctuations is found to be negligible under typical experimental conditions.