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Sample records for anneau de collisions dorsay

  1. Au Cern, premières collisions de protons hier

    CERN Document Server

    Galeazzi, Juliette

    2009-01-01

    "Hier, les scientifiques du monde entier ont salué le redémarrage du LHC, grand collisionneur de hadrons, au Cern à Genève. Après quatorze mois d'arrêt, à la suite d'une panne, les expériences ont pris et les premières collisions ont eu lieu" (2 pages)

  2. Etude de la production de photons a grande impulsion transverse dans les collisions hadroniques avec le detecteur UA2

    CERN Document Server

    Bourliaud, Martial

    NOUS ETUDIONS LA PRODUCTION INCLUSIVE DE PHOTONS A GRANDE IMPULSION TRANSVERSE ET A FAIBLE PSEUDORAPIDITE DANS LES COLLISIONS HADRONIQUES. NOUS PRESENTONS DEUX ANALYSES ORIGINALES REALISEES SUR 13 PICOBARN MOINS UN DE COLLISIONS PROTON-ANTIPROTON COLLECTEES PAR LA COLLABORATION UA2' AUPRES DU COLLISIONNEUR SPPS DU CERN. QCD PREDIT QUE CES PHOTONS SONT SOIT EMIS PAR LES QUARKS LORS DES INTERACTIONS A GRAND MOMENT DE TRANSFERT (PHOTONS DIRECTS), SOIT CREES PAR BREMSSTRAHLUNG LORS DE LA FRAGMENTATION DES JETS. LA SECTION EFFICACE TOTALE DE PRODUCTION DE CES PHOTONS A ETE POUR L'ESSENTIEL CALCULEE A L'APPROXIMATION DES LOGARITHMES SOUS-DOMINANTS, AVEC TOUTEFOIS DES INCERTITUDES SUR LA PROPORTION DE PHOTONS DE BREMSSTRAHLUNG AUX FAIBLES VALEURS DE X#T. DU POINT DE VUE EXPERIMENTAL LES PHOTONS OFFRENT L'AVANTAGE D'ETRE BIEN MIEUX MESURES QUE LES JETS, ET NOS MESURES CONSTITUENT DES TESTS DU MODELE DES PARTONS DE QCD. LES PREDICTIONS THEORIQUES ET LES APPLICATIONS IMPORTANTES DE LA PRODUCTION HADRONIQUE DE PHOTONS E...

  3. Collision induced fragmentation dynamics of small metallic clusters; Dynamique de fragmentation induite par collision de petits agregats metalliques

    Energy Technology Data Exchange (ETDEWEB)

    Picard, Y

    1999-04-15

    The goal of this work is the complete analysis of the fragmentation of alkali clusters (Na{sub n}{sup +} (n < 10), NaK{sup +} and K{sub 2}{sup +}) induced by collision with light atomic (He) or molecular (H{sub 2}) targets. The main point is to study how the energy is transmitted to the cluster during the collision and how this energy is shared among the various degrees of freedom of the system and leads to its fragmentation. Two types of interactions govern the collision induced dissociation processes: on one hand, the electronic mechanisms where the target perturbs the electronic cloud and brings the molecule into a dissociative state, and on the other hand, the impulsive mechanisms where the momentum transferred to the atomic cores leads to the rotational-vibrational dissociation of the molecule. The experimental procedure is based on the measurement of the velocity vectors of the outgoing fragments detected in coincidence. This allows to reconstruct the full kinematics of the fragmentation and to separate and characterize for the first time the two types of interactions. The two basic mechanisms of collision induced dissociation are then clearly resolved for the diatomic molecule Na{sub 2}{sup +}. For the heteronuclear molecular ion NaK{sup +}, it is shown that the dissociation process is due to a combination of electronic and impulsive mechanisms in some of the dissociation pathways. The extension to the study of metallic clusters Na{sub n}{sup +} (n < 10) fragmentation shows the role and the relative importance of the electronic and impulsive mechanisms and their evolution with the cluster size. The complete analysis of Na{sub 3}{sup +} multi-fragmentation is also presented. (author)

  4. Spin Interaction under the Collision of Two Kerr-(anti-)de Sitter Black Holes

    CERN Document Server

    Gwak, Bogeun

    2016-01-01

    We have investigated spin interaction under the collision of Kerr-(anti-)de Sitter black holes. The potential of a spin interaction is dependent on the relative rotating directions of the black holes, and this potential can be released as gravitational radiation under the collision. The radiation depends on the cosmological constant and corresponds to the potential of the spin interaction at a limit where one of the black holes is assumed to have small mass and angular momentum. Then, we have shown, approximately, the overall behaviors of the upper bounds on the radiation using thermodynamics. From these bounds, the spin interaction can consistently contribute to the radiation. In addition, the radiation depends on the stability of the black hole synthesized from the collision.

  5. Recherche de leptoquarks de troisième génération dans l’expérience CMS au LHC

    CERN Document Server

    Chasserat, Julien

    L'expérience CMS (Compact Muon Solenoid), construite sur l'anneau du LHC (Large Hadron Collider) a enregistré une quantité colossale de données provenant des collisions proton-proton de 2009 à 2012 à des énergies dans le centre de masse de 7 TeV et 8 TeV. Cette expérience est consacrée aux mesures de précision des paramètres du modèle standard, à l'étude du boson de Higgs ainsi qu'à la mise à l'épreuve de théories au-delà du modèle standard. Un certain nombre de ces théories prévoient l'existence de particules appelées leptoquarks, de nouveaux bosons se couplant à la fois aux leptons et au quarks. La première partie de cette thèse est consacrée à la présentation du Modèle Standard des particules et à une introduction théorique aux leptoquarks. La seconde explique brièvement le fonctionnement du LHC et de l'expérience CMS. La troisième partie est dédiée au travail effectué dans le groupe générateur de CMS au cours de la première année de ma thèse. Cette mission consis...

  6. Effective collision strengths for excitation and de-excitation of nebular [O III] optical and infrared lines with kappa distributed electron energies

    CERN Document Server

    Storey, P J

    2015-01-01

    We present effective collision strengths for electron excitation and de-excitation of the ten forbidden transitions between the five lowest energy levels of the astronomically abundant doubly-ionised oxygen ion, O^{2+}. The raw collision strength data were obtained from an R-matrix intermediate coupling calculation using the Breit-Pauli relativistic approximation published previously by the authors. The effective collision strengths were calculated with kappa-distributed electron energies and are tabulated as a function of the electron temperature and kappa.

  7. Mesures magnétiques de l'aimant dipôle 097 révisé de type MBA

    CERN Document Server

    Dutour, J

    2002-01-01

    Dans l'anneau SPS, les dipôles MBA et MBB sont installés depuis 1975 (assemblés au CERN, Réf. 1 et 2). Lorsque certains de ces aimants sont défectueux, ils sont révisés: changement de chambre, isolation, etc. Après révision, il est nécessaire de contrôler leurs caractéristiques magnétiques. C'est le cas du dipôle MBA 097.

  8. Tumor de colisión periampular Collision tumor of the ampulla of Vater: Carcinoid and adenocarcinoma

    Directory of Open Access Journals (Sweden)

    J. Ferrando Marco

    2007-04-01

    Full Text Available Presentamos un caso de tumor de colisión periampular en el que coexisten un tumor carcinoide de pared duodenal y un adenocarcinoma de cabeza de páncreas. El paciente era un varón de 64 años con historia reciente de diarreas al que se diagnosticó una ictericia obstructiva. Histopatológicamente el tumor resecado mostraba dos neoplasias independientes. Una de ellas constituida por cordones sólidos de células neuroendocrinas que afectaba pared duodenal. La otra está formada por un adenocarcinoma bien diferenciado procedente del páncreas. Ambas neoplasias fueron confirmadas inmunohistoquímicamente. Según la literatura anglosajona revisada tan sólo hemos encontrado seis casos de esta rara coexistencia neoplásica.We report the case of a periampullary collision tumor, in which a duodenal-wall carcinoid and an adenocarcinoma of the head of the pancreas coexisted. We describe the case of a 64-year-old man with a recent history of diarrhea, who was diagnosed with obstructive jaundice. A duodeno-pancreatectomy was performed, and the specimen showed two independent neoplasms in the histopathologic study. Solid cords and nests of neuroendocrine cells in the duodenal wall formed the carcinoid tumor, whereas the other neoplasm was made up of a well-differentiated adenocarcinoma of the pancreas. Both were confirmed by immunohistochemical analysis. According to the literature reviewed, this is the sixth reported case of this rare neoplastic association.

  9. Rencontres de Moriond QCD 2012: Probing the nature of heavy-ion collisions

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    Wednesday began with presentations by experiments worldwide on their investigations into the intriguing nature of the Quark Gluon Plasma (QGP). The ALICE Collaboration examined further preliminary results from the LHC’s 2010 Pb-Pb run, observing that particles containing strange quarks were more abundant than they are in proton-proton collisions – indicating the presence of QGP. They also presented results from the so-called “soft probes” that allow scientists to look at the collective behaviour of the QGP medium.  The ATLAS and CMS Collaborations provided a very different approach to the study heavy ion physics: examining particle energy loss in the QGP by looking at the momentum of particle jets leaving the medium. ATLAS reported their results on a variety of studies using jets, charged hadrons and weak bosons produced in heavy-ion collisions during the 2010 run. Presenting their results from the 2011 run, the CMS Collaboration found that there is energy...

  10. Systèmes de particules et collisions discrètes dans les automates cellulaires

    OpenAIRE

    Richard, Gaétan

    2008-01-01

    The main goal of this thesis is to study systems of particles and collisions in cellular automata. Starting from experimental observations, we give formal definitions of these objects and show how they relate to regular colorings of the plane. Using a symbolic representation of those objects, we introduce a syntactical operation on them: catenation schemes. This operation is linked to an informal operation usually used in algorithmics on cellular automata through a coloring interpretation. We...

  11. Study of heavy ions collision at SIS energies with the detector FOPI; Etude des collisions d'ions lourds aux energies de SIS avec le detecteur FOPI

    Energy Technology Data Exchange (ETDEWEB)

    Bastid, N

    1999-09-23

    The present work has been carried out in the framework of experiments performed with the FOPI detector at the SIS/ESR accelerator facility of GSI-Darmstadt. It is devoted to the study of central and semi-central heavy ion collisions at beam energies ranging from 100 MeV to 2 GeV per nucleon. We present first generalities on relativistic heavy ion collisions then the FOPI detector with a special attention to the FOPI Inner Wall constructed by the Clermont-Ferrand group. The main results of the FOPI collaboration obtained with light and intermediate mass fragments and kaons are presented. A systematic study of the different forms of collection motion of nuclear matter, radial flow in very central reactions, sideward flow and squeeze-out in semi-central collisions, is performed. Further exciting possibilities concerning production and propagation of strangeness at SIS energies will be offered soon with the upgrade of the FOPI detector. The FOPI data have introduced constraints on parameters of theoretical models. Important progress concerning the knowledge of the properties of nuclear matter, the dynamics of the collisions and in-medium effects have been achieved. (author)

  12. Fragments detection of the Ar{sup +} collision in air; Deteccion de fragmentos de la colision de Ar{sup +} en aire

    Energy Technology Data Exchange (ETDEWEB)

    Chaparro V, F. J. [IPN, Escuela Superior de Fisica y Matematicas, Av. IPN s/n, Col. San Pedro Zacatenco, 07738 Mexico D. F. (Mexico); Fuentes M, B. E. [UNAM, Facultad de Ciencias, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Yousif, F. B. [Universidad Autonoma del Estado de Morelos, Facultad de Ciencias, Av. Universidad 1001, Col. Chamilpa, 62210 Cuernavaca, Morelos (Mexico); Roa N, J. A. E., E-mail: javierfranciscocv@gmail.com [Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Departamento de Ciencias Basicas, Av. San Pablo Xalpa No. 1802, Col. Reynosa Tamaulipas, 02200 Mexico D. F. (Mexico)

    2012-10-15

    The different components of a lineal accelerator of particles to low energy that will be used in experiments of atomic and molecular collisions are described. By means of the technique of flight time the fragments of the collision of positive ions were identified in gases. In this work values of some parameters are presented guided to optimize the operation of the accelerator, as well as preliminary data of the collision of argon ions in air. (Author)

  13. Collision Mechanics

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Servis, D.P.; Zhang, Shengming;

    1999-01-01

    The first section of the present report describes the procedures that are being programmed at DTU for evaluation of the external collision dynamics. Then follows a detailed description of a comprehensive finite element analysis of one collision scenario for MS Dextra carried out at NTUA. The last...

  14. A modern and affordable activity at the grammar school: particle collisions; Une activite moderne et abordable au lycee: les collisions de particules

    Energy Technology Data Exchange (ETDEWEB)

    Lagoute, Ch. [Lycee Bellevue, 31 - Toulouse (France)

    2010-12-15

    In the eighties photographs from cloud chambers where used in the French physics curriculum of grammar schools to study particle collisions inside a magnetic field. This was a simple but efficient means to illustrate elastic and non-elastic collisions and energy and momentum conservation laws. The teachers used transparent abacus to determine the radius of curvature from which particle's linear momentum was deduced. Now photographs have been digitized and a software has been created to determine the value of the radius by simple mouse click. This pedagogical tool has become easier to use and remains a very interesting means to make students touch concrete and surprising physics. (A.C.)

  15. Mesures magnétiques d'aimants dipôles de type MBB révisés (MBB 019, 072, 074, 078, 110, 130, 160, 161, 163)

    CERN Document Server

    Dutour, J

    1999-01-01

    Dans l'anneau SPS, les dipôles MBA et MBB sont installés depuis 1975 (assemblés au CERN, Réf. 1 et 2). Lorsque certains de ces aimants sont défectueux, ils sont révisés : Changement de chambre, isolation, etc. Après révision, il est nécessaire de contrôler leurs caractéristiques magnétiques. C'est le cas des dipôles MBB 019, 072, 074, 078, 110, 130, 160, 161, 163.

  16. Simulations of collisions between N-body classical systems in interaction; Simulations de collisions entre systemes classiques a n-corps en interaction

    Energy Technology Data Exchange (ETDEWEB)

    Morisseau, Francois [Laboratoire de Physique Corpusculaire de CAEN, ENSICAEN, Universite de Caen Basse-Normandie, UFR des Sciences, 6 bd Marechal Juin, 14050 Caen Cedex (France)

    2006-05-15

    The Classical N-body Dynamics (CNBD) is dedicated to the simulation of collisions between classical systems. The 2-body interaction used here has the properties of the Van der Waals potential and depends on just a few parameters. This work has two main goals. First, some theoretical approaches assume that the dynamical stage of the collisions plays an important role. Moreover, colliding nuclei are supposed to present a 1. order liquid-gas phase transition. Several signals have been introduced to show this transition. We have searched for two of them: the bimodality of the mass asymmetry and negative heat capacity. We have found them and we give an explanation of their presence in our calculations. Second, we have improved the interaction by adding a Coulomb like potential and by taking into account the stronger proton-neutron interaction in nuclei. Then we have figured out the relations that exist between the parameters of the 2-body interaction and the properties of the systems. These studies allow us to fit the properties of the classical systems to those of the nuclei. In this manuscript the first results of this fit are shown. (author)

  17. Fragmentation of neutral carbon clusters formed by high velocity atomic collision; Fragmentation d'agregats de carbone neutres formes par collision atomique a haute vitesse

    Energy Technology Data Exchange (ETDEWEB)

    Martinet, G

    2004-05-01

    The aim of this work is to understand the fragmentation of small neutral carbon clusters formed by high velocity atomic collision on atomic gas. In this experiment, the main way of deexcitation of neutral clusters formed by electron capture with ionic species is the fragmentation. To measure the channels of fragmentation, a new detection tool based on shape analysis of current pulse delivered by semiconductor detectors has been developed. For the first time, all branching ratios of neutral carbon clusters are measured in an unambiguous way for clusters size up to 10 atoms. The measurements have been compared to a statistical model in microcanonical ensemble (Microcanonical Metropolis Monte Carlo). In this model, various structural properties of carbon clusters are required. These data have been calculated with Density Functional Theory (DFT-B3LYP) to find the geometries of the clusters and then with Coupled Clusters (CCSD(T)) formalism to obtain dissociation energies and other quantities needed to compute fragmentation calculations. The experimental branching ratios have been compared to the fragmentation model which has allowed to find an energy distribution deposited in the collision. Finally, specific cluster effect has been found namely a large population of excited states. This behaviour is completely different of the atomic carbon case for which the electron capture in the ground states predominates. (author)

  18. Lignes de force de l’espace européen

    Directory of Open Access Journals (Sweden)

    Roger Brunet

    2002-06-01

    Full Text Available L'Europe est structurée par plusieurs figures géographiques: une double dissymétrie, une puissante dorsale transverse, un anneau de villes riches ceint de périphéries en transformation, un treillage de grands axes réels et potentiels ; mais elle reste divisée par les frontières et les centralités associées. L'apparition de figures nouvelles (les arcs et l'avancée des limites de l'Europe unie contribuent à changer la donne, mais l'intégration véritable du territoire européen implique que l'on n'hésite plus à engager les « grands travaux » nécessaires.

  19. Characterizing traveling-wave collisions in granular chains starting from integrable limits: The case of the Korteweg-de Vries equation and the Toda lattice

    Science.gov (United States)

    Shen, Y.; Kevrekidis, P. G.; Sen, S.; Hoffman, A.

    2014-08-01

    Our aim in the present work is to develop approximations for the collisional dynamics of traveling waves in the context of granular chains in the presence of precompression. To that effect, we aim to quantify approximations of the relevant Hertzian FPU-type lattice through both the Korteweg-de Vries (KdV) equation and the Toda lattice. Using the availability in such settings of both one-soliton and two-soliton solutions in explicit analytical form, we initialize such coherent structures in the granular chain and observe the proximity of the resulting evolution to the underlying integrable (KdV or Toda) model. While the KdV offers the possibility to accurately capture collisions of solitary waves propagating in the same direction, the Toda lattice enables capturing both copropagating and counterpropagating soliton collisions. The error in the approximation is quantified numerically and connections to bounds established in the mathematical literature are also given.

  20. El teorema de Riemann-Roch y el morfismo de Gysin en geometría aritmética

    OpenAIRE

    Navarro Garmendia, Alberto

    2016-01-01

    Le th eor eme de Riemann-Roch originale a rme que pour tout morphisme propre f : Y ! X entre vari et es quasi-projectifs lisses sur un corps, et tout el ement a 2 K0(Y ) du groupe de Grothendieck des br es vectoriels on a ch(f!(a)) = f {u100000}Td(Tf ) ch(a) (cf. [BS58]). Ici ch est le caract ere de Chern, Td(Tf ) est la classe de Todd du br e tangent relative et f et f! sont les images directes de l'anneau de Chow et K0 respectivement. Apr es, Baum, Fulton et MacPherson ont d emontr e...

  1. Relation between hard photon production and impact parameter in heavy ion collisions at intermediate energies; Dependance de la production de photons durs avec le parametre d`impact dans les collisions entre ions lourds aux energies intermediaires

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Garcia, G.

    1994-06-01

    Hard photons produced in heavy-ions collisions at intermediate energies have been used in order to study hot and compresses nuclear matter created in these collisions (at Ganil). It was found that Bremsstrahlung radiation emitted in np collisions is the main mechanism of hard-photon production for the whole range of impact parameter. Moreover, it was observed a substantial decrease of the hardness of hard-photon spectrum. The BUU model reproduces very well the experimental results, showing that the hardness of the spectrum reflects, mainly, nuclear-matter compression in the first stage of the collision. A new method was developed to measure the density of the nuclear matter created at the beginning of the collision. BUU results and some experimental evidences point out that a significant contribution of hard photons are produced in the last stage of the collision: thermal hard photons. These photons are sensitive to the density oscillation of nuclear matter. Its production cross-section will constitute a measurement of the compressibility of nuclear matter and its spectrum a measure of the temperature. (from author) 64 figs., 60 refs.

  2. Simulation of black hole collisions in asymptotically Anti-de Sitter spacetimes.

    Science.gov (United States)

    Bantilan, Hans; Romatschke, Paul

    2015-02-27

    We present results from the evolution of spacetimes that describe the merger of asymptotically global anti-de Sitter black holes in 5D with an SO(3) symmetry. Prompt scalar field collapse provides us with a mechanism for producing distinct trapped regions on the initial slice, associated with black holes initially at rest. We evolve these black holes towards a merger, and follow the subsequent ring down. The boundary stress tensor of the dual conformal field theory is conformally related to a stress tensor in Minkowski space that inherits an axial symmetry from the bulk SO(3). We compare this boundary stress tensor to its hydrodynamic counterpart with viscous corrections of up to second order, and compare the conformally related stress tensor to ideal hydrodynamic simulations in Minkowski space, initialized at various time slices of the boundary data. Our findings reveal far-from-hydrodynamic behavior at early times, with a transition to ideal hydrodynamics at late times.

  3. Emission of fragments in heavy ion-collisions at Fermi energy; Modes de production des fragments dans les collisions d'ions lourds aux energies intermediaires

    Energy Technology Data Exchange (ETDEWEB)

    Normand, J

    2001-10-01

    The study of reaction mechanisms in Fermi energy domain has shown the dominant binary character of the process. The two heavy sources produced after the first stage of the interaction (the quasi-projectile QP and the quasi-target QT) can experience various decay modes from evaporation to multifragmentation. However, the presence of light fragments at mid rapidity cannot be explained by the standard decay of the QP and the QT. To understand the mechanisms producing such a contribution, the break-up of the QP has been studied on the following systems: Xe+Sn from 25 to 50 MeV/A, Ta+Au and Ta+U at 33, 39.6 MeV/A and U+U at 24 MeV/A. The experiment has been performed at GANIL with the INDRA multidetector. The particular behaviour of the heaviest fragment and the correlation between the charge and the velocity of the fragments suggest a shape deformation followed by the rupture of a neck formed in between the two partners of the collision. The heaviest fragment could be the reminiscence of the projectile. A method based on the angular distribution of the heaviest fragment has allowed to separate the statistical break-up of the QP and the non equilibrated break-up. The statistical break-up ranges from 30 % to 75 % of the break-ups. The comparison of the statistical component with a statistical model gives information about the charge, the angular momentum and the temperature of the QP. The comparison of the non equilibrated component with dynamical models could give information about the parameters of the nuclear interaction in medium. (author)

  4. Fragmentation study of isolated and nano-solvated biomolecules induced by collision with multiply charged ions and neutral particles; Etude de la fragmentation de molecules d'interet biologique isolees et nano-solvatees induite par collision avec des ions multicharges et des particules neutres

    Energy Technology Data Exchange (ETDEWEB)

    Bernigaud, V.

    2009-08-27

    This thesis concerns a gas phase study of the fragmentation of bio-molecular systems induced by slow collisions with multiply charged ions (in the keV-region), alkali atoms and rare gases. The main objective was to study the physical processes involved in the dissociation of highly electronically excited systems. In order to elucidate the intrinsic properties of certain biomolecules (porphyrins and amino acids) we have performed experiments in the gas phase with isolated systems. The obtained results demonstrate the high stability of porphyrins after electron removal and attachment. Furthermore, a dependence of the fragmentation pattern produced by multiply charged ions on the isomeric structure of the alanine molecule has been shown. In a second part of the thesis, a strong influence of the environment of the biomolecule on the fragmentation channels, their modification and their new opening, has been clearly proven. This phenomenon occurs in the presence of other surrounding biomolecules (clusters of nucleobases) as well as for molecules of a solvent (molecules of water, methanol and acetonitrile) in which the biomolecule is embedded. In order to extend these studies to larger systems, a new experimental set-up, based on an electro-spray ion source combined with a quadrupole mass filter has been developed. Due to the successful tests and proposed improvements of the device future experiments will become available concerning the fragmentation of large charged and solvated bio-molecular systems induced by collision processes. (author) [French] Cette these est une etude de la fragmentation en phase gazeuse de molecules d'interet biologique soumises a des collisions avec des ions multicharges de basse energie (energie cinetique de quelques keV) et des atomes alcalins ou de gaz rare. L'objectif est d'etudier les processus physique qui conduisent a la dissociation de ces systemes soumis a une excitation electronique intense. Afin de mettre en evidence

  5. Methods of selection in heavy ion collisions at Fermi energies and de-excitation modes with the INDRA multi-detector; Methodes de tri dans les collisions d'ions lourds aux energies de Fermi et modes de desexcitation avec le multidetecteur INDRA

    Energy Technology Data Exchange (ETDEWEB)

    Lautesse, Ph

    2005-11-15

    The progress made in particle detection, particularly the design of multi-detectors, like INDRA, that cover a solid angle of almost 4{pi}, have given a new impetus to heavy ion collisions. These detectors are demanding for an efficient way of selecting events that have a common history or similar features, for instance the events representing the de-excitation of a unique emitter. The problem is to find the adequate variable on which the discrimination can be based. Different methods are proposed in this work, the common point is that they require efficient models to reproduce and analyse experimental data in order to apprehend the equation of state of nuclear matter. Most of these models are based on the numerically solving of the nuclear Boltzmann equation. The application to the Ni + Ni reaction with an energy ranging from a few A.MeV to more than 50 A.MeV illustrates this work. (A.C.)

  6. Contribution to the analysis of dileptons production reactions in proton-proton collision with HADES; Contribution a l'analyse de reactions de production de dileptons en collision proton-proton avec HADES

    Energy Technology Data Exchange (ETDEWEB)

    Moriniere, E

    2008-03-15

    The most recent analysis of dilepton spectra, produced in heavy ion collisions, have shown the need for a precise knowledge of all dilepton production channels. The experimental HADES facility, installed on the GSI accelerator site, is appropriate for that goal. Thus, the Dalitz decay branching ratio of {delta} resonance ({delta} {yields} Ne{sup +}e{sup -}), which has never been measured, is studied in this work. Moreover, the pp {yields} p/ {delta}{sup +} {yields} ppe{sup +-} reaction could allow to provide some information about the internal resonance structure and more precisely, about the electromagnetic transition N - A form factors. The analysis of simulations shows the feasibility of this experiment, estimates the counting yield as well as the Signal over Background ratio. This analysis shows also the great importance of the momentum resolution of the detector for the success of this experiment. The momentum resolution must be investigated. In this work, an attempt to find out the most important contributions to the measured resolution is presented. The calibration step, which provides the relation between electronic time and physical time, the detector alignment (global, relative or internal) as well as the tracking method are studied. Some methods for improvement of these different contributions are proposed in order to reach the optimal resolution. (author)

  7. Thermal Bremsstrahlung probing nuclear multifragmentation in nucleus-nucleus collisions around the Fermi energy; Bremsstrahlung thermique comme sonde de la multifragmentation nucleaire dans les collisions noyau-noyau aux energies de Fermi

    Energy Technology Data Exchange (ETDEWEB)

    D' Enterria, D.G

    2000-05-15

    The thermodynamical properties of nuclear matter at moderate temperatures and densities, in the vicinity of the predicted nuclear liquid-gas phase transition, are studied using as experimental probe the hard-photons (E{sub {gamma}} > 30 MeV) emitted in nucleus-nucleus collisions. Photon and charged-particle production in four different heavy-ion reactions (Ar{sup 36} + Au{sup 197}, Ag{sup 107}, Ni{sup 58}, C{sup 12} at 60 A*MeV) is measured exclusively and inclusively coupling the TAPS photon spectrometer with two charged-particle and intermediate-mass-fragment detectors covering nearly 4{pi}. We confirm that Bremsstrahlung emission in first-chance (off-equilibrium) proton-neutron collisions (pn{gamma}) is the dominant origin of hard photons. We also firmly establish the existence of a thermal radiation component emitted in second-chance proton-neutron collisions. This thermal Bremsstrahlung emission takes place in semi-central and central nucleus-nucleus reactions involving heavy targets. We exploit this observation i) to demonstrate that thermal equilibrium is reached during the reaction, ii) to establish a new thermometer of nuclear matter based on Bremsstrahlung photons, iii) to derive the thermodynamical properties of the excited nuclear sources and, in particular, to establish a 'caloric curve' (temperature versus excitation energy), and iv) to assess the time-scales of the nuclear break-up process. (author)

  8. Compilation of electron collision excitation cross sections for neutral argon; Compilacion de resultados de secciones eficaces de excitacion para niveles del Argon neutro

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, F.

    1993-07-01

    The present work presents a compilation and critical analysis of the available data on electron collision excitation cross sections for neutral Argon levels. This study includes: 1.- A detailed description in intermediate coupling for all the levels belonging the 20 configurations 3p5 ns (n=4to 12), np(n=4to8) and nd(n=3to8)of neutral Argon. 2.- Calculation of the electron collision excitation cross sections in Born and Born-Oppenheimer-Ochkur approximations for all the levels in the 14 configurations 3p5 ns (n=4 to 7), np (n=4 to 7) and nd (n=3 to 8). 3.- comparison and discussion of the compiled data. These are the experimental and theoretical values available from the literature, and those from this work. 4.- Analysis of the regularities and systematic behaviors in order to determine which values can be considered more reliable. It is show that the concept of one electron cross section results quite useful for this purpose. In some cases it has been possible to obtain in this way approximate analytical expressions interpolating the experimental data. 5.- All the experimental and theoretical values studied are graphically presented and compared. 6.- The last part of the work includes a listing of several general purpose programs for Atomic Physics calculations developed for this work. (Author) 35 refs.

  9. Comprehensive de novo peptide sequencing from MS/MS pairs generated through complementary collision induced dissociation and 351 nm ultraviolet photodissociation.

    Science.gov (United States)

    Horton, Andrew Pitchford; Robotham, Scott A; Cannon, Joe R; Holden, Dustin D; Marcotte, Edward M; Brodbelt, Jennifer S

    2017-02-24

    We describe a strategy for de novo peptide sequencing based on matched pairs of tandem mass spectra (MS/MS) obtained by collision induced dissociation (CID) and 351 nm ultraviolet photodissociation (UVPD). Each precursor ion is isolated twice with the mass spectrometer switching between CID and UVPD activation modes to obtain a complementary MS/MS pair. To interpret these paired spectra, we modified the UVnovo de novo sequencing software to automatically learn from and interpret fragmentation spectra, provided a representative set of training data. This machine learning procedure, using random forests, synthesizes information from one or multiple complementary spectra, such as the CID/UVPD pairs, into peptide fragmentation site predictions. In doing so, the burden of fragmentation model definition shifts from programmer to machine and opens up the model parameter space for inclusion of nonobvious features and interactions. This spectral synthesis also serves to transform distinct types of spectra into a common representation for subsequent activation-independent processing steps. Then, independent from precursor activation constraints, UVnovo's de novo sequencing procedure generates and scores sequence candidates for each precursor. We demonstrate the combined experimental and computational approach for de novo sequencing using whole cell E. coli lysate. In benchmarks on the CID/UVPD data, UVnovo assigned correct full-length sequences to 83% of the spectral pairs of doubly charged ions with high-confidence database identifications. Considering only top-ranked de novo predictions, 70% of the pairs were deciphered correctly. This de novo sequencing performance exceeds that of PEAKS and PepNovo on the CID spectra and that of UVnovo on CID or UVPD spectra alone. As presented here, the methods for paired CID/UVPD spectral acquisition and interpretation constitute a powerful workflow for high-throughput and accurate de novo peptide sequencing.

  10. Mesure de la production de J/psi en collisions p-Pb au LHC avec le spectromètre à muons d'ALICE

    CERN Document Server

    Lakomov, Igor

    Hard probes represent one of the hottest topics of the modern high energy physics. The production mechanism of quarkonia (mesons composed of a charm or beauty quark and its antiquark) in hadronic collisions is of particular interest. The suppression of J/psi and other charmonium states was predicted as one of the first signatures of the Quark Gluon Plasma (QGP) formation and was seen at RHIC and SPS. It was also studied at the LHC in Pb-Pb collisions. However, other effects can affect the charmonium production in Pb-Pb collisions without the presence of the QGP. These effects are inherent to the use of nuclei and are called “Cold Nuclear Matter” (CNM) effects. They can be studied in p-Pb collisions. This thesis is dedicated to the studies of J/psi production in p-Pb collisions at the LHC at a center of mass energy of 5.02 TeV per nucleon pair. J/psi production is studied as a function of transverse momentum, rapidity and event activity. These results represent a significant step to better understanding of...

  11. Fragmentation d'agrégats de carbone (multi) chargés formés par ionisation et excitation en collision de haute vitesse

    OpenAIRE

    2005-01-01

    M L. ADOUI, Rapporteur Mme L. CHEN, Rapporteur M P.A. HERVIEUX Mme C. JOBLIN Mme L. TCHANG-BRILLET, Présidente du jury; The present work is devoted to the study of the excitation, ionisation and fragmentation of monocharged carbon clusters C^+_n (n \\leq 10) induced by high velocity (2.6au) collision on helium gas. For this velocity regime the electronic mechanisms of excitation and ionisation are dominant. The collision processes (electronic excitation, simple and (multi) ionisation, fragment...

  12. Etude des mécanismes des réactions induites par les noyaux à halo de neutrons $^{11}Be$ (49,2 MeV/nucléon) et $ ^{6}He$ (41,5 MeéV/nucléon) sur le plomb en fonction de l'inélasticité des collisions

    CERN Document Server

    Patois, Y

    2001-01-01

    Etude des mécanismes des réactions induites par les noyaux à halo de neutrons $^{11}Be$ (49,2 MeV/nucléon) et $ ^{6}He$ (41,5 MeéV/nucléon) sur le plomb en fonction de l'inélasticité des collisions

  13. Mesures magnétiques d'aimants dipôles de type MBA révisés (MBA 005, 244, 297, 375)

    CERN Document Server

    Dutour, J

    2000-01-01

    Dans l'anneau SPS, les dipôles MBA et MBB sont installés depuis 1975 (assemblés au CERN, Réf. 1 et 2). Lorsque certains de ces aimants sont défectueux, ils sont révisés: changement de chambre, isolation, etc. Après révision, il est nécessaire de contrôler leurs caractéristiques magnétiques. De même, sont contrôlés aussi les aimants de réserve stockes dans le hall 867. C'est le cas des dipôles MBA 005, 244, 297, 375.

  14. Study of heavy ion collisions at Fermi energy: is the methodology orientating our understanding of physics?; Etude des collisions d'ions lourds aux energies de Fermi: les demarches utilisees orientent-elles notre comprehension de la physique?

    Energy Technology Data Exchange (ETDEWEB)

    Bacri, Ch.O

    2001-07-01

    The analysis of the reaction products in the case of a multi-fragmentation reaction requires an efficient sorting of the experimental data. A collision, detected in a 4{pi} detector generates about 100 parameters that are measured. Experimental data have to be reduced to the part most meaningful of the studied event. A model of the reaction is necessary to discard or value variables on which the sorting could be based. The selection of experimental data implies almost always the introduction of a bias that is necessary to know in order to continue a thorough analysis of the experimental results. A theoretical work is then necessary not only in the view of the comparison between results and predictions but also to validate the assumptions that have been made to sort out the experimental data. This method is applied to the study of the nuclear reaction: Gd + U at 36 MeV/U. (A.C.)

  15. Dynamical effects and fission in the heavy ion collisions at incident energies near the Fermi energy; Effets dynamiques et fission dans les collisions d`ions lourds a des energies incidentes voisines de l`energie de Fermi

    Energy Technology Data Exchange (ETDEWEB)

    Jean Colin [Lab. de Physique Corpusculaire, Caen Univ., 14 (France)

    1997-12-01

    In this work we have studied the reaction mechanisms implied in the heavy ion collisions at energies near the Fermi level. We have observed the predominance of binary processes (2 principal nuclei in the exit channel) and selected events leading to the fission of one of the two fragmentation products. On the basis of the study of angular distributions of fission fragments and associated light particles, we have determined the angular momentum of the nucleus in the moment of fission and the angular momentum transfer in the interaction. The comparison of experimental values of the angular momentum transferred with the theoretical models enables the characterization of projectile-target interaction. For the different systems studied, the spin of fissioning nucleus ranges between 30 {Dirac_h} and 60 {Dirac_h} while the transferred angular momentum may reach 90 {Dirac_h}. For these studies the determinant parameter is the sequence of emission of light particles and fragments, hence the lifetime associated to each processes. For central collisions we have measured pre-fission lifetimes lower then 10{sup -21} sec. These values are very short in comparison with the statistical fission processes, what prompted to search for off-equilibrium (non-statistical) phenomena in the data. Taking into account the charges of the fission fragments we were able to isolate a dynamical component and a statistical component in the fission process. We have compared these two classes of events and showed that there is a relative excess of energy between the fragments when the origin of scission is dynamical. We hope to derive of this observable the nuclear deformation velocity and constrain the value of the nuclear matter viscosity in comparison with the theoretical models 54 refs., 27 figs., 2 tabs.

  16. Holographic heavy ion collisions with baryon charge

    CERN Document Server

    Casalderrey-Solana, Jorge; van der Schee, Wilke; Triana, Miquel

    2016-01-01

    We numerically simulate collisions of charged shockwaves in Einstein-Maxwell theory in anti-de Sitter space as a toy model of heavy ion collisions with non-zero baryon charge. The stress tensor and the baryon current become well described by charged hydrodynamics at roughly the same time. The effect of the charge density on generic observables is typically no larger than 15\\%. %The rapidity profile of the charge is wider than the profile of the local energy density. We find significant stopping of the baryon charge and compare our results with those in heavy ion collision experiments.

  17. Whole study of nuclear matter collective motion in central collisions of heavy ions of the FOPI detector; Etude complete du mouvement collectif de la matiere nucleaire dans les collisions centrales d'ions lourds avec le detecteur FOPI

    Energy Technology Data Exchange (ETDEWEB)

    Bendarag, A

    1999-07-09

    In this work we study the collective phenomena in the central collisions of heavy ions for the Au + Au, Xe + CsI and Ni + Ni systems at incident energies from 150 to 400 MeV/nucleon with the data of the FOPI detector. In order to describe completely the flow of the nuclear matter, we fit the double differential momentum distributions with two-dimensional Gaussian. We study the characteristic parameters of the collective flow (flow range, aspect ratios, flow parameter) versus the charge and the mass of the fragments as well as the incident energy and the centrality of the collisions. The transverse energy is used for selecting the central collisions. The method of the Gaussian fits requires also to reconstruct the reaction plane of the event. Then we correct the parameters for the finite number of particles effects and account for the influence of the acceptance of the detector. We confirm the importance of the thermal motion for the light charge or mass fragments and, conversely, the predominance of the collective motion for the heavy fragments. A common flow angle for all the types of particles is highlighted for the first time, demonstrating the power of the method of the Gaussian fits; The evolution of the other parameters confirms the observations done with other methods of flow analysis. These results should contribute to put constraints on the collision models and to enlarge our knowledge of the properties of the nuclear matter. (author)

  18. Nonlinear structures of the Korteweg-de Vries and modified Korteweg-de Vries equations in non-Maxwellian electron-positron-ion plasma: Solitons collision and rogue waves

    Energy Technology Data Exchange (ETDEWEB)

    El-Tantawy, S. A., E-mail: samireltantawy@yahoo.com [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt); Moslem, W. M., E-mail: wmmoslem@hotmail.com [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt); Centre for Theoretical Physics, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt)

    2014-05-15

    Solitons (small-amplitude long-lived waves) collision and rogue waves (large-amplitude short-lived waves) in non-Maxwellian electron-positron-ion plasma have been investigated. For the solitons collision, the extended Poincaré-Lighthill-Kuo perturbation method is used to derive the coupled Korteweg-de Vries (KdV) equations with the quadratic nonlinearities and their corresponding phase shifts. The calculations reveal that both positive and negative polarity solitons can propagate in the present model. At critical value of plasma parameters, the coefficients of the quadratic nonlinearities disappear. Therefore, the coupled modified KdV (mKdV) equations with cubic nonlinearities and their corresponding phase shifts have been derived. The effects of the electron-to-positron temperature ratio, the ion-to-electron temperature ratio, the positron-to-ion concentration, and the nonextensive parameter on the colliding solitons profiles and their corresponding phase shifts are examined. Moreover, generation of ion-acoustic rogue waves from small-amplitude initial perturbations in plasmas is studied in the framework of the mKdV equation. The properties of the ion-acoustic rogue waves are examined within a nonlinear Schrödinger equation (NLSE) that has been derived from the mKdV equation. The dependence of the rogue wave profile on the relevant physical parameters has been investigated. Furthermore, it is found that the NLSE that has been derived from the KdV equation cannot support the propagation of rogue waves.

  19. Ionizing collisions: a new diagnostic for Bose-Einstein condensates of metastable helium; Collisions ionisantes: un nouveau diagnostic pour les condensats de Bose-Einstein d'helium metastable

    Energy Technology Data Exchange (ETDEWEB)

    Sirjean, O

    2003-06-01

    At this writing, metastable helium (23S1) is the only example of Bose-Einstein condensation of an atom in an excited electronic state. The corresponding internal energy permits efficient and fast electronic detection of the atoms using a micro-channel plate detector (MCP). Moreover, this energy is responsible for ionizing collisions inside the magnetically trapped cloud (Penning ionization). These ions are also easily detected by the MCP. This thesis begins by describing the characteristics of the MCP detector. Next, the experimental procedure to achieve Bose-Einstein condensation is presented. These preliminaries are followed by a description of the experiments performed in order to determine the origin of the ions produced and by a presentation of some of the new experimental possibilities provided by the ion signal. For clouds with a low enough density, ions are mainly produced by collisions with the residual gas, and the signal is proportional to the number of trapped atoms. For clouds with a sufficiently high density, for example close to the condensation threshold, ions are mainly produced by 2- and 3-body collisions. In this case, the ion signal is also related to the density of the cloud. Depending on the density, the signal gives a real-time and 'non-destructive' measurement of these different characteristics. In particular, we have shown it is a valuable indicator of the onset of condensation, because it signals the sudden increase of density which then occurs. By studying the ion rate versus the density and the number of atoms for pure condensates and for thermal clouds at critical temperature, we have measured the collision rate constants for these ionizing processes. Our results are in agreement with theoretical predictions. (author)

  20. Exclusive study of Ni+Ni and Ni+Au central collisions: phase coexistence and spinodal decomposition; Etude exclusive des collisions centrales Ni+Ni et Ni+Au: coexistence de phase et decomposition spinodale

    Energy Technology Data Exchange (ETDEWEB)

    Guiot, B

    2002-12-01

    The INDRA multidetector allowed us to study the Ni+Ni collisions at 32A MeV and the Ni+Au collisions at 52,4 MeV. Central collisions leading to 'quasi-fused' systems were isolated using multidimensional analysis techniques: the Discriminant Analysis and the Principal Component Analysis. Comparison with a statistical model shows that the selected events are compatible with thermodynamical equilibrium. The average thermal excitation energy is 5A MeV for both systems. Calculations of heat capacities show that the deexcitation of the hot sources are akin to a liquid-gas phase transition of nuclear matter. Indeed heat capacities exhibit a negative branch as expected for a phase transition of a finite system. The dynamics of this phase transition has been investigated by applying the charge correlation method. An enhanced production of events with equal-sized fragments has been evidenced for Ni+Au at 52A MeV. No signal was found for Ni+Ni at 32A MeV. Finally this method was improved by taking into account the total charge conservation. The signal is seen more clearly for Ni+Au at 52A MeV, but is ambiguous for Ni+Ni at 32A MeV. The path followed in the state diagram, or the involved time scales, seem to be different for these systems. (authors)

  1. Dynamics of heavy nucleus collisions in the reaction {sup 86}Kr+{sup 165}Ho at 60 MeV/n by means of the DeMoN neutron multi-detector; Etude de la dynamique des collisions entre noyaux lourdes dans la reaction {sup 86}Kr + {sup 165}Ho a 60 MeV/n a l`aide du multidetecteur de neutron DeMoN

    Energy Technology Data Exchange (ETDEWEB)

    Dorvaux, Olivier [Centre de Recherches Nucleaires de Strasbourg-Cronenbourg, 67 (France)

    1997-01-14

    This work is dedicated to the study of binary dissipative collisions for the system Kr + Ho at 60 AMeV. The first chapter is devoted to the used experimental set-up. In particular, the neutron detector DeMoN and a new parallel plate avalanche counter, achieved for this experiment are described. In the next chapters we analyse the neutron energy spectra. The study is fulfilled through a simulation taking into account two, and then, three sources in order to upraise the excitation energy sharing between the two residual fragments. The final results of the equal excitation energy sharing is compared to the predictions of a statistical model and a participant-spectator one. This study also underlines an intermediate velocity source which has the main characteristics of a neck emission. In the last chapter the neutron energy spectra analysed in the frame of the projectile-like-fragment (PLF) show the existence of the light particle emission component called pre-thermalization. It means that, in a first step of the collision there is a competition between the deposit of energy in the system and its removal. From this analysis we can say that the temperature of the residual fragments is usually overestimated. The resulting temperature of the PLF is quite low, and is about 3.5 MeV. (author) 47 refs., 52 figs., 5 tabs.

  2. Collision Induced Galaxy Formation

    CERN Document Server

    Balland, C; Schäffer, R

    1997-01-01

    We present a semi-analytical model in which galaxy collisions and strong tidal interactions, both in the field and during the collapse phase of groups and clusters help determine galaxy morphology. From a semi-analytical analysis based on simulation results of tidal collisions (Aguilar & White 1985), we propose simple rules for energy exchanges during collisions that allow to discriminate between different Hubble types: efficient collisions result in the disruption of disks and substantial star formation, leading to the formation of elliptical galaxies; inefficient collisions allow a large gas reservoir to survive and form disks. Assuming that galaxy formation proceeds in a Omega_0=1 Cold Dark Matter universe, the model both reproduces a number of observations and makes predictions, among which are the redshifts of formation of the different Hubble types in the field. When the model is normalized to the present day abundance of X-ray clusters, the amount of energy exchange needed to produce elliptical gal...

  3. Bubble collision with gravitation

    CERN Document Server

    Hwang, Dong-il; Lee, Wonwoo; Yeom, Dong-han

    2012-01-01

    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.

  4. Quantum chromodynamics at high energy, theory and phenomenology at hadron colliders; Chromodynamique quantique a haute energie, theorie et phenomenologie appliquee aux collisions de hadrons

    Energy Technology Data Exchange (ETDEWEB)

    Marquet, C

    2006-09-15

    When probing small distances inside a hadron, one can resolve its partonic constituents: quarks and gluons that obey the laws of perturbative Quantum Chromodynamics (QCD). This substructure reveals itself in hadronic collisions characterized by a large momentum transfer: in such collisions, a hadron acts like a collection of partons whose interactions can be described in QCD. In a collision at moderate energy, a hadron looks dilute and the partons interact incoherently. As the collision energy increases, the parton density inside the hadron grows. Eventually, at some energy much bigger than the momentum transfer, one enters the saturation regime of QCD: the gluon density has become so large that collective effects are important. We introduce a formalism suitable to study hadronic collisions in the high-energy limit in QCD, and the transition to the saturation regime. In this framework, we derive known results that are needed to present our personal contributions and we compute different cross-sections in the context of hard diffraction and particle production. We study the transition to the saturation regime as given by the Balitsky-Kovchegov equation. In particular we derive properties of its solutions.We apply our results to deep inelastic scattering and show that, in the energy range of the HERA collider, the predictions of high-energy QCD are in good agreement with the data. We also consider jet production in hadronic collisions and discuss the possibility to test saturation at the Large Hadron Collider. (author)

  5. Intermediate energies heavy ion collisions : study of the charged particles emission dynamics and emitters characterization; Collisions d`ions lourds aux energies intermediaires: etude de la dynamique d`emission des particules chargees et caracterisation des emetteurs

    Energy Technology Data Exchange (ETDEWEB)

    Bauge, E.

    1994-07-01

    In heavy ion collisions at intermediate energies, reaction processes are ranging from slow processes where equilibrium is achieved between every emission, up to direct processes where nucleon nucleon scattering and phase space availability are the deciding factors. In order to investigate this transition, both the emission dynamics and the characteristics of the emitter have been studied, both theoretically and experimentally in the AMPHORA detector, for the systems 7, 17, 27 and 34 AMeV, {sup 40}Ar+Al, {sup 40}Ar+Cu and {sup 40}Ar+Ag. First, the linear momentum transfer of the most central collisions has been evaluated for these systems, by measuring the velocity of heavy residues. Then, by measuring azimuthal angle correlations functions, and by comparing them with statistical model predictions, the average angular momentum of the emitter has been evaluated. To study the charged particles emission dynamics, experimental azimuthal angle and relative momentum correlation functions have been compared with simulations based on a classical trajectory model. Finally, predictions of an advanced BUU model have been studied for the system 34 AMeV 40 Ar+Al. (authors). 69 refs., 52 figs., 5 tabs.

  6. Study of the open charm and Drell-Yan production in p + p collisions at 200 GeV with the Phenix detector at RHIC; Etude de la production de charme ouvert et de Drell-Yan dans les collisions p + p a 200 GeV avec le detecteur Phenix a RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Gadrat, S

    2005-09-15

    Ultra-relativistic heavy ions collisions allow the study of nuclear matter under extreme conditions of temperature and pressure and, more specifically, of a new phase of nuclear matter: the quarks and gluons plasma (QGP). The RHIC collider, located at the Brookhaven National Laboratory (Usa), produces such collisions. PHENIX, one of the four operational detectors at the collider, is the only one capable of measuring muons. In this dissertation, we present a dimuon data analysis, which data have been collected by PHENIX in p + p collisions during two data taking runs (3 and 4). p + p collisions provide a requisite reference for the understanding of heavy ions collisions. The aim of the analysis discussed in this dissertation is to extract the cross sections of the main physical components of the dimuon spectrum observed at RHIC for p + p collisions: J/{psi}, open charm and Drell-Yan. This analysis is based on a global line shape fit of the dimuon mass spectrum. This fit has been possible thanks to prior simulation study of the mass distribution shapes of these different components. Production yields were obtained from the fit. Lastly, the response function study for each components and the use of various efficiencies led to the estimate of the different production cross sections. The results have been compared to other existing measurements and show an overall good agreement. The work presented in this dissertation offers a first estimate of the open charm production cross section in the dimuon channel, as well as a first estimate of the Drell-Yan production cross section at RHIC for p + p collisions: {sigma}(J/{psi} {yields} {mu}{mu}) = (2.9 {+-} 0.1) {mu}b; {sigma}(cc-bar {yields} {mu}{mu}) = (0.96 {+-} 0.18) mb; {sigma}(Drell-Yan {yields} {mu}{mu}) = (0.20 {+-} 0.04) {mu}b.

  7. Mechanisms of reaction and energy dissipation in the nucleus-nucleus symmetric collisions at 25 to 74 MeV/u: contribution of exclusive measurements of the INDRA multidetector; Mecanismes de reaction et de dissipation de l`energie dans les collisions symetriques noyau-noyau de 25 a 74 MeV/u: apport des mesures exclusives du multidetecteur INDRA

    Energy Technology Data Exchange (ETDEWEB)

    Metivier, V. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire

    1995-04-01

    This work is about the first experimental results obtained with the INDRA multidetector. First, the characterization of reaction mechanisms is performed. For complete events, global description of the collision is performed and compared with theoretical calculations. Dissipative binary mechanisms represent the largest part of the cross section for violent collisions whatever the bombarding energy (from 25 to 74 MeV/u) for the studied systems (Ar + KCl and Xe + Sn). The two outgoing products decay takes place through light charged particle and fragment emission. The reconstruction of the two primary sources is achieved, allowing thus the study of the evolution of the energy dissipation. Excitation energies exceeding 10 MeV/u are reached. The decay of the primary outgoing partners can be understood in a statistical model approach and the role of collective modes like expansion energy seems to be negligible. The study of the angular distributions points out angular momentum effects, `proximity effect` and a dynamical ternary process corresponding to the emission of a light fragment in between the two heavier products. For the most violent collisions, events can also be interpreted in terms of the multifragmentation of a single source, at least for the Xe + Sn system at 50 MeV/u (80 m barn). For the lower incident energies, fusion residues associated to the largest dissipations are recognized, but the cross sections is small (35 m barn for the Ar + KCl system at 32 MeV/u). (author) 91 refs.

  8. Collisions of Random Walks

    CERN Document Server

    Barlow, Martin T; Sousi, Perla

    2010-01-01

    A recurrent graph $G$ has the infinite collision property if two independent random walks on $G$, started at the same point, collide infinitely often a.s. We give a simple criterion in terms of Green functions for a graph to have this property, and use it to prove that a critical Galton-Watson tree with finite variance conditioned to survive, the incipient infinite cluster in $\\Z^d$ with $d \\ge 19$ and the uniform spanning tree in $\\Z^2$ all have the infinite collision property. For power-law combs and spherically symmetric trees, we determine precisely the phase boundary for the infinite collision property.

  9. Nuclear fragmentation in central collisions: Ni + Au from 32 to 90 A*MeV; Fragmentation dans les collisions centrales du systeme Ni + Au de 32 a 90 A MeV

    Energy Technology Data Exchange (ETDEWEB)

    Bellaize, N

    2000-11-03

    Heavy ion collisions are one of tools for studying nuclear system far away from its equilibrium state. This work concerns the most violent collisions in the Ni + Au system for incident energies ranging from 32 up to 90 AMeV. These events were detected with the multidetector INDRA and selected by the Principal Component Analysis (multidimensional analysis). This method classifies the events according their detection features and their degree of dissipation. We observed two deexcitation mechanisms: a fusion/fission - evaporation process and a multifragmentation process. Those two coexist from 32 to 52 AMeV whereas only one subsists at 90 AMeV. For those two mechanisms, an component was observed which seems to be linked to the initial phase of the reaction. The energy fluctuations of this component leads to variations in the energy deposit which determines the deexcitation of the system. The experimental multifragmentation data of the Ni + Au system (52 and 90 AMeV) were compared to the predictions of a statistical model and to the experimental data of the system Xe + Sn at 50 AMeV (also detected with INDRA). These comparisons show the lack of collective radial energy for fragments (Z{>=}10) in the Ni + Au system, and show that the degree of multifragmentation depends of the thermal excitation energy. Mean kinetic energies of particles and lights fragments (Z{>=}10) are larger in the Ni + Au system than the Xe + Sn system. This observation shows that these particles are more sensitive to the entrance channel for an asymmetric system than for a symmetric system (for the same number of nucleons). (author)

  10. Electron-molecule collisions

    CERN Document Server

    Takayanagi, Kazuo

    1984-01-01

    Scattering phenomena play an important role in modern physics. Many significant discoveries have been made through collision experiments. Amongst diverse kinds of collision systems, this book sheds light on the collision of an electron with a molecule. The electron-molecule collision provides a basic scattering problem. It is scattering by a nonspherical, multicentered composite particle with its centers having degrees of freedom of motion. The molecule can even disintegrate, Le., dissociate or ionize into fragments, some or all of which may also be molecules. Although it is a difficult problem, the recent theoretical, experimental, and computational progress has been so significant as to warrant publication of a book that specializes in this field. The progress owes partly to technical develop­ ments in measurements and computations. No less important has been the great and continuing stimulus from such fields of application as astrophysics, the physics of the earth's upper atmosphere, laser physics, radiat...

  11. Study of the color effect in a quark-gluon plasma on the production rates of quarkonia in heavy ion collisions in the Phenix experiment; Etude de l'effet d'ecrantage de couleur dans un plasma de quarks et de gluons sur les taux de production des quarkonia dans les collisions d'ions lourds aupres de l'experience Phenix

    Energy Technology Data Exchange (ETDEWEB)

    Rakotozafindrabe, A

    2007-05-15

    This work deals with the measurement of the production of J/{psi} in Cu + Cu collisions at 200 GeV per nucleon pair via their decay channel into 2 muons. The experimental data used is that collected during the 2005 campaign at the RHIC. In the first chapter, we present the theoretical context of the study of quark-gluon plasmas (QGP) and its production in relativistic heavy ion collisions. The second chapter deals with the production of J/{psi} in proton-proton collisions and in case of light ion collisions where QGP can not be produced. The experimental setting is presented in the third chapter, particularly the muon spectrometer and the detectors whose purpose is to measure collision centrality. Data analysis concerning the extraction of the signal and the reconstruction of data is described in the fourth chapter. The method that has enabled us to extract the production of the J/{psi} as well as its uncertainties is detailed in the fifth chapter.

  12. Sécurité des occupants d'un véhicule de transport guidé soumis à une collision ou à un freinage d'urgence

    OpenAIRE

    2007-01-01

    La sécurité des occupants d'un véhicule de transport guidé est une thématique en plein essor, notamment sous son aspect biomécanique. L'analyse des scénarios préoccupants d'accidents fait ressortir une grande diversité, laquelle concerne tout d'abord les niveaux de perturbations, depuis les incidents mineurs (tels qu'un un freinage d'urgence), fréquents, jusqu'aux impacts à très forte énergie (tels qu'une collision entre un train et un poids lourd immobilisé sur un passage à niveau), beaucoup...

  13. Mesure de la section efficace de production des quarks beaux et charmés à partir de leur désintegration semileptonique en électrons avec l'experience ATLAS dans les collisions protons-protons a sqrt(s) = 7 TeV au LHC.

    CERN Document Server

    Bordoni, Stefania

    Le thème central de la thèse est la mesure de la section efficace de production des électrons venant de la désintégration des quarks lourds (b et c) avec l'expérience ATLAS dans les collisions proton-proton à sqrt(s)=7 TeV au LHC. La calibration du calorimètre électromagnétique et la reconstruction des électrons jouent un rôle cardinal dans l'analyse développée dans cette thèse. Ces thématiques sont traitées dans la première partie du manuscrit. L'étude des systématiques liées à la variation des constantes de calibration paramètrant la chaîne de lecture du calorimètre et qui affectent la reconstruction de l'énergie des cellules est presentée. La description des procédures de reconstruction des événements dans le détecteur ATLAS est ensuite traitée. Les cas de mauvaise reconstruction sont abordés et une étude de l'estimation du taux des faux leptons dans des événements multi-jets est présentée. La deuxième partie de la thèse est dédiée à la mesure de la section ef...

  14. Ion Collision, Theory

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. Statistical and off-equilibrium production of fragments in heavy ion collisions at intermediate energies; Production statistique et hors-equilibre de fragments dans les collisions d`ions lourdes aux energies intermediaires

    Energy Technology Data Exchange (ETDEWEB)

    Bocage, Frederic [Lab. de Physique Corpusculaire, Caen Univ., 14 - Caen (France)

    1998-12-15

    The study of reaction products, fragments and light charged particles, emitted during heavy-ion collisions at intermediate energies has shown the dominant binary dissipative character of the reaction, which is persisting for almost all impact parameters. However, in comparison with this purely binary process, an excess of nuclear matter is observed in-between the quasi-projectile and the quasi-target. To understand the mechanisms producing such an excess, this work studies more precisely the breakup in two fragments of the quasi-projectile formed in Xe+Sn, from 25 to 50 MeV/u, and Gd+C and Gd+U at 36 MeV/u. The data were obtained during the first INDRA experiment at GANIL. The angular distributions of the two fragments show the competition between statistical fission and non-equilibrated breakup of the quasi-projectile. In the second case, the two fragments are aligned along the separation axis of the two primary partners. The comparison of the fission directions and probabilities with statistical models allows us to measure the fission time, as well as the angular momentum, temperature and size of the fissioning residue. The relative velocities are compatible with Coulomb and thermal effects in the case of statistical fission and are found much higher for the breakup of a non-equilibrated quasi-projectile, which indicates that the projectile was deformed during interaction with the target. Such deformations should be compared with dynamical calculations in order to constrain the viscosity of nuclear matter and the parameters of the nucleon-nucleon interaction, (author) 148 refs., 77 figs., 11 tabs.

  16. Isotopic gradient along the new hebrides arc (Vanuatu, SW Pacific). Collision of the d`entrecasteaux zone and heterogeneity of mantle sources; Gradient isotopique le long de l`arc des nouvelles hebrides (Vanuatu, Pacifique sud-ouest). Collision de la zone d`entrecasteaux et heterogeneite des sources mantelliques

    Energy Technology Data Exchange (ETDEWEB)

    Laporte, Ch.; Cluzel, D. [Universite Francaise du Pacifique, Noumea, Nouvelle-Caledonie, 98 - Noumea (France); Laporte, Ch.; Briqueu, L. [Montpellier-2 Univ., 34 (France); Eissen, J.Ph. [ORSTOM, 29 - Plouzane (France)

    1998-01-01

    The recent volcanic activity of the New Hebrides arc (Vanuatu) has been influenced by the collision with the d`Entrecasteaux Zone, the composition of which remains uncertain. New trace elements and isotopic data from these lavas allow previous interpretations of compositional gradients along the arc to be qualified. The geochemical compositions of lavas display abrupt changes from calc-alkaline compositions straight in front of the collision zone, to arc-tholeiites on both sides. In contrast, isotopic compositions display a progressive variation related to less and less enriched sources away from the collision zone, evolving toward `normal` MORB-type sources. Such a trend suggests that two types of contamination have occurred in front of the collision zone, a magmatic contamination due to the subduction of an older lithosphere ({sup 206}Pb/{sup 204}Pb trend) and contamination by an `enriched-type` mantle component (Dupal feature). (authors) 17 refs.

  17. Gyrokinetic linearized Landau collision operator

    DEFF Research Database (Denmark)

    Madsen, Jens

    2013-01-01

    The full gyrokinetic electrostatic linearized Landau collision operator is calculated including the equilibrium operator, which represents the effect of collisions between gyrokinetic Maxwellian particles. First, the equilibrium operator describes energy exchange between different plasma species...

  18. Présentations inhabituelles d'un syndrome de Plummer-Vinson chez l'africain de race noire: à propos de deux observations

    Science.gov (United States)

    Berthé, Adama; Diop, Madoky Magatte; Toure, Papa Souleymane; Tall, Cheikh Tidiane; Fulgence Faye, Abdoul; Diop, Bernard Marcel; Ka, Mamadou Mourtalla

    2014-01-01

    Le syndrome de Plummer Vinson (SPV) est une affection rare caractérisée par une dysphagie cervicale associée à une anémie ferriprive et un anneau sur l’œsophage supérieur. Parfois, son mode de présentation inhabituelle peut faire errer le diagnostic. Le rétrécissement annulaire peut être de découverte fortuite lors d'une endoscopie digestive haute. Nous rapportons deux observations de syndrome de Plummer-Vinson chez des sujets de genre masculin et féminin. Celles-ci ont comme point commun une découverte fortuite lors d'une endoscopie digestive haute. La première observation concernait un garçon de 14 ans aux antécédents de brûlure caustique de l’œsophage dans l'enfance avec dysphagie haute passagère ne l'inquiétant pas depuis lors. Il était reçu en urgence pour une endoscopie digestive haute motivée par une dysphagie de survenue brutale secondaire à une prise d'aliment solide. L'examen clinique avait objectivé une chéilite angulaire. La biologie montrait un abaissement de la ferritinémie sans anémie. L'endoscopie avait mis en évidence un anneau circulaire franchi avec ressaut au niveau de la bouche de Killian. Elle avait également permis l'extraction d'un corps étranger à type de noyau de « pain de singe » mais la lumière de l’œsophage était infranchissable à partir du niveau d'arrêt. Le transit œsophagien montrait un ralentissement du produit de contraste au niveau de l'sophage cervical et thoracique sans lésions morphologiques. Dans la deuxième observation, il s'agissait d'une jeune femme de 35 ans adressée à l unité d'endoscopie digestive pour objectiver une gastrite atrophique sur une suspicion de la maladie de Biermer. La fibroscopie mettait alors en évidence, un rétrécissement annulaire infranchissable à 18 centimètres des arcades dentaires. La biologie montrait une anémie avec augmentation de la ferritinémie. Dans les deux cas, le traitement martial était systématique associé à des séances de

  19. A method for detection of mechanical collisions and couch-beam intersections; Un metodo para la prediccion de colisiones mecanicas y de intersecciones del haz con la mesa de tratamiento

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Galiano, P.; Crelgo Alonso, D.; Gonzalez Sancho, J. M.; Vivanco Parellada, J.; Fernandez Garcia, J.; Barbes Fernandez, B.; Pamos Urena, M.; Monserrat Fuertes, T.

    2009-07-01

    Two software applications for avoiding mechanical collisions and beam blocking by the couch are described. The method used is based on a simplified model of the couch cross-sections and a very simple routine. The algorithms employed and the graphical interfaces developed are described, along with several software implementation tests. The accuracy of predictions was within 5 mm, therefore the results are satisfactory despite the simple approach assumed. (Author) 11 refs.

  20. Methodology of hot nucleus calorimetry and thermometry produced by nuclear reactions around Fermi energies; Methodologie de la calorimetrie et de la thermometrie des noyaux chauds formes lors de collisions nucleaires aux energies de Fermi

    Energy Technology Data Exchange (ETDEWEB)

    Vient, E

    2006-12-15

    This work deals with the calorimetry and thermometry of hot nuclei produced in collisions Xe + Sn between 25 and 100 MeV/u. The apparatus for hot nucleus physical characterization is the 4{pi} detector array Indra. This study was made by using the event generators Gemini, Simon and Hipse and a data-processing filter simulating the complete operation of the multi-detector. The first chapter presents the different ways of producing hot nuclei. In the second and third chapters, the author presents a critical methodological study of calorimetry and thermometry applied to hot nuclei, different methods are reviewed, their accuracy and application range are assessed. All the calorimetry methods rely on the assumption that we are able to discriminate decay products of the hot nucleus from evaporated particles. In the fourth chapter, the author gives some ways of improving calorimetry characterization of the hot nucleus. An alternative method of calorimetry is proposed in the fifth chapter, this method is based on the experimental determination of an evaporation probability that is deduced from the physical characteristics of the particles present in a restricted domain of the space of velocities.

  1. Observation of correlated atom pairs in spontaneous four wave mixing of two colliding Bose-Einstein condensates; Observation de paires d'atomes correles au travers de la collision de deux condensats de Bose-Einstein

    Energy Technology Data Exchange (ETDEWEB)

    Perrin, A

    2007-11-15

    In this thesis, we report on the observation of pairs of correlated atoms produced in the collision of two Bose-Einstein condensates of metastable helium. Three laser beams perform a Raman transfer which extracts the condensate from the magnetic trap and separates it into two parts with opposite mean momenta. While the condensates propagate, elastic scattering of pairs of atoms occurs, whose momenta satisfy energy and momentum conservation laws. Metastable helium atoms large internal energy allows the use of a position-sensitive, single-atom detector which permits a three-dimensional reconstruction of the scattered atoms'momenta. The statistics of these momenta show correlations for atoms with opposite momenta. The measured correlation volume can be understood from the uncertainty-limited momentum spread of the colliding condensates. This interpretation is confirmed by the observation of the momentum correlation function for two atoms scattered in the same direction. This latter effect is a manifestation of the Hanbury Brown-Twiss effect for indistinguishable bosons. Such a correlated-atom-pair source is a first step towards experiments in which one would like to confirm the pairs'entanglement. (author)

  2. Elementary Collisions with HADES

    CERN Document Server

    Fröhlich, I; Agakichiev, G; Agodi, C; Balanda, A; Bellia, G; Belver, D; Belyaev, A; Blanco, A; Böhmer, M; Boyard, J L; Braun-Munzinger, P; Cabanelas, P; Castro, E; Chernenko, S; Christ, T; Destefanis, M; Daz, J; Dohrmann, F; Dybczak, A; Eberl, T; Fabbietti, L; Fateev, O; Finocchiaro, P; Fonte, Paulo J R; Friese, J; Galatyuk, T; Garzn, J A; Gernhuser, R; Gilardi, C; Golubeva, M; Gonzalez-Diaz, D; Grosse, E; Guber, F; Heilmann, M; Hennino, T; Holzmann, R; Ierusalimov, A; Iori, I; Ivashkin, A; Jurkovic, M; Kmpfer, B; Kanaki, K; Karavicheva, T; Kirschner, D; König, I; König, W; Kolb, B W; Kotte, R; Kozuch, A; Krizek, F; Krcken, R; Khn, W; Kugler, A; Kurepin, A; Lamas-Valverde, J; Lang, S; Lange, J S; Lopes, L; Maier, L; Mangiarotti, A; Marn, J; Markert, J; Metag, V; Michalska, B; Mishra, D; Morinire, E; Mousa, J; Müntz, C; Naumann, Lutz; Novotny, R; Otwinowski, J; Pachmayer, Y C; Palka, M; Parpottas, Y; Pechenov, V; Pechenova, O; Prez Cavalcanti, T; Przygoda, W; Ramstein, B; Reshetin, A; Roy-Stephan, M; Rustamov, A; Sadovskii, A; Sailer, B; Salabura, P; Schmah, A; Simon, R; Spataro, S; Spruck, B; Strbele, H; Stroth, J; Sturm, C; Sudol, M; Tarantola, A; Teilab, K; Tlustý, P; Traxler, M; Trebacz, R; Tsertos, H; Veretenkin, I; Wagner, V; Wen, H; Wisniowski, M; Wojcik, T; Wstenfeld, J; Yurevich, S; Zanevsky, Y; Zumbruch, P

    2007-01-01

    The "High Acceptance DiElectron Spectrometer" (HADES) at GSI, Darmstadt, is investigating the production of e+e- pairs in A+A, p+A and N+N collisions. The latter program allows for the reconstruction of individual sources. This strategy will be roughly outlined in this contribution and preliminary pp/pn data is shown.

  3. Photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Collisions in soccer kicking

    DEFF Research Database (Denmark)

    Andersen, Thomas Bull; Dörge, Henrik C.; Thomsen, Franz Ib

    1999-01-01

    An equation to describe the velocity of the soccer ball after the collision with a foot was derived. On the basis of experimental results it was possible to exclude certain factors and only describe the angular momentum of the system, consisting of the shank, the foot and the ball, leading...

  5. Droplet collisions in turbulence

    NARCIS (Netherlands)

    Oldenziel, G.

    2014-01-01

    Liquid droplets occur in many natural phenomena and play an important role in a large number of industrial applications. One of the distinct properties of droplets as opposed to solid particles is their ability to merge, or coalesce upon collision. Coalescence of liquid drops is of importance in for

  6. Study of the fragmentation of astrophysical interest molecules (C{sub n}H{sub m}) induced by high velocity collision; Etude de la fragmentation de molecules d'interet astrophysique de type C{sub n}H{sub m} par collision atomique de haute vitesse

    Energy Technology Data Exchange (ETDEWEB)

    Tuna, Th

    2008-07-15

    This work shows the study of atom-molecule collision processes in the high velocity domain (v=4,5 a.u). The molecules concerned by this work are small unsaturated hydrocarbons C{sub 1-4}H and C{sub 3}H{sub 2}. Molecules are accelerated with the Tandem accelerator in Orsay and their fragmentation is analyzed by the 4{pi}, 100% efficient detector, AGAT. Thanks to a shape analysis of the current signal from the silicon detectors in association with the well known grid method, we are able to measure all the fragmentation channels of the incident molecule. These dissociation measurements have been introduced in the modelization of two objects of the interstellar medium in which a lot of hydrocarbon molecules have been observed (TMC1, horse-head nebula). We have extended our branching ratios obtained by high velocity collision to other electronic processes included in the chemical database like photodissociation and dissociative recombination. This procedure is feasible under an assumption of the statistical point of view of the molecular fragmentation. The deviations following our modification are very small in the modelization of TMC1 but significant in the photodissociation region. The first part is dedicated to the description of the experimental setting that has enabled us to study the fragmentation of C{sub n}H{sub m} molecules: the Orsay's Tandem accelerator and the Agat detector. The second part deals with negative ion sources and particularly with the Sahat source that is based on electronic impact and has shown good features for the production of anions and correct stability for its use with accelerators. The third part is dedicated to the experimental results in terms of cross-sections, number of fragments and branching ratios, associated to the various collisional processes. The last part presents an application of our measurement of fragmentation data to astro-chemistry. In this field, the simulation codes of the inter-stellar medium require databases

  7. Half collision resonance phenomena in molecules

    Energy Technology Data Exchange (ETDEWEB)

    Maximo Garcia-Sucre (Universidad Central de Venezuela, Caracas (Venezuela)); Raseev, G. (Paris-11 Univ., 91 - Orsay (France)); Ross, S.C. (New Brunswick Univ., Fredericton, NB (Canada)) (eds.)

    1991-01-01

    The Escuela Latinoamericana de Fisica (ELAF) is a series of meeting s that for 28 years has played an important role in research-level teaching of physics in Latin America. This book contains the proceedings of ELAF 90 which was held at the Instituto Venezolano de Investigaciones Cientificas (IVIC) in Caracas, Venezuela from July 23 to August 3, 1990, as part of the commemoration of the 30th anniversary of IVIC. In contrast to previous ELAF's that were of general scope, ELAF 90 centered on a particular subject matter: Half Collisional Resonance Phenomena in Molecules, Experimental and Theoretical Approaches. The term Half Collision'' refers to the fragmentation of a molecular system following is excitation by light. The lack of an incident fragmentation of a molecular system following is excitation by light. The lack of an incident particle (other than the photon) in the fragmentation process is what leads to the term. The purpose of this volume is to present current results in the experimental and theoretical study of half collisions and also to include pedagogical papers at an introductory or intermediate level. The contributions are grouped into several sections; light sources; ionization; dissociation-experimental; dissociation-theory; competition between ionization and dissociation; and particle-molecule collisions.

  8. A comparative study of the low energy HD+o-/p-H2 rotational excitation/de-excitation collisions and elastic scattering

    CERN Document Server

    Sultanov, Renat A; Adhikari, S K

    2011-01-01

    The precise Diep and Johnson H2-H2 potential energy surface (PES), obtained from the first principles has been adjusted through appropriate rotation of the three-dimensional coordinate system and applied to low-temperature (T < 300 K) HD+o-/p-H2 collisions of astrophysical interest. A non-reactive quantum mechanical close-coupling method is used to carry out computation for the total rotational state-to-state cross sections and thermal rate coefficients. A comparative study with previous calculations is presented.

  9. Collision Probability Analysis

    DEFF Research Database (Denmark)

    Hansen, Peter Friis; Pedersen, Preben Terndrup

    1998-01-01

    It is the purpose of this report to apply a rational model for prediction of ship-ship collision probabilities as function of the ship and the crew characteristics and the navigational environment for MS Dextra sailing on a route between Cadiz and the Canary Islands.The most important ship and crew...... characteristics are: ship speed, ship manoeuvrability, the layout of the navigational bridge, the radar system, the number and the training of navigators, the presence of a look out etc. The main parameters affecting the navigational environment are ship traffic density, probability distributions of wind speeds...... probability, i.e. a study of the navigator's role in resolving critical situations, a causation factor is derived as a second step.The report documents the first step in a probabilistic collision damage analysis. Future work will inlcude calculation of energy released for crushing of structures giving...

  10. Modeling and numerical study of two phase flow; Modelisation et etude numerique d'ecoulements diphasiques: 1- Modelisation d'un ecoulement homogene equilibre 2- Modelisation des collisions entre gouttelettes a l'aide d'un modele simplifie de type BGK

    Energy Technology Data Exchange (ETDEWEB)

    Champmartin, A.

    2011-02-28

    This thesis describes the modelization and the simulation of two-phase systems composed of droplets moving in a gas. The two phases interact with each other and the type of model to consider directly depends on the type of simulations targeted. In the first part, the two phases are considered as fluid and are described using a mixture model with a drift relation (to be able to follow the relative velocity between the two phases and take into account two velocities), the two-phase flows are assumed at the equilibrium in temperature and pressure. This part of the manuscript consists of the derivation of the equations, writing a numerical scheme associated with this set of equations, a study of this scheme and simulations. A mathematical study of this model (hyperbolicity in a simplified framework, linear stability analysis of the system around a steady state) was conducted in a frame where the gas is assumed baro-tropic. The second part is devoted to the modelization of the effect of inelastic collisions on the particles when the time of the simulation is shorter and the droplets can no longer be seen as a fluid. We introduce a model of inelastic collisions for droplets in a spray, leading to a specific Boltzmann kernel. Then, we build caricatures of this kernel of BGK type, in which the behavior of the first moments of the solution of the Boltzmann equation (that is mass, momentum, directional temperatures, variance of the internal energy) are mimicked. The quality of these caricatures is tested numerically at the end. (author) [French] Cette these decrit la modelisation et la simulation de systemes a deux phases composees de particules evoluant dans un gaz. Les deux phases interagissent entre elles et le type de modele a considerer depend directement du type de simulations envisagees. Dans une premiere partie, les deux phases sont considerees comme des fluides, elles sont decrites a l'aide d'un modele de melange avec une relation de derive (permettant de

  11. Mesure de la Polarisation des Lambda Produits dans les Collisions Positron-Electron AU Lep a L'aide du Detecteur Opal

    Science.gov (United States)

    Vandenplas, Denis

    Le Modele Standard est le cadre theorique general qui, jusqu'a present, a permis l'interpretation de tous les resultats experimentaux en physique des hautes energies. Cette theorie decrit, entre autres, la production d'une paire de particules elementaires, formee d'un quark et d'un antiquark, a partir de la desintegration de l'un des bosons mediateurs de l'interaction faible, le Z^0. Cependant, dans ce cas precis, la transformation subsequente des quarks primaires en particules reelles, un processus appele hadronisation, n'est decrite qu'a l'aide de modeles phenomenologiques. Afin de sonder les mecanismes de l'hadronisation, cette these presente la mesure du transfert du spin d'un quark etrange primaire a une particule appelee Lambda lors des desintegrations hadroniques du Z^0. L'etude a ete realisee dans le cadre de la collaboration OPAL, une des quatre experiences menees au collisionneur LEP, la ou des electrons et des positrons sont acceleres jusqu'a une energie commune, sqrt{s} = {rm E_ {cm}}, voisine de l'energie de production du rm Z^0, M_{Z ^0} egale a 91.3 GeV. La theorie electrofaible precise la direction du spin, c'est-a-dire la polarisation, d'un quark etrange primaire provenant de la desintegration d'un Z ^0. Quant a lui, le modele des quarks etablit que l'orientation du spin d'un Lambda est directement reliee a la polarisation du quark etrange dont il provient. La question est de determiner dans quelle mesure la polarisation du quark primaire est transmise au Lambda a la suite du processus de l'hadronisation, decrit dans le cadre de la ChromoDynamique Quantique. Une estimation, qui tient compte de tous ces differents aspects theoriques, evalue a 30% la polarisation des Lambda dont l'impulsion est superieure a 15 GeV/c. La mesure experimentale de la polarisation repose sur l'identification des Lambda a partir de la reconstitution de la desintegration Lambdato ppi^-. Ce processus, qui se deroule par le biais de l'interaction faible, viole la parite car

  12. Experimental study of multi-electronic processes on grazing incidence ions collision with LiF(001) surface; Etude experimentale des processus multi-electroniques lors de collisions d'ions en incidence rasante sur une surface de LiF(001)

    Energy Technology Data Exchange (ETDEWEB)

    Momeni, A

    2003-01-15

    This manuscript deals with different experimental studies on grazing incidence (< 3 degrees) collisions of mono-charged ions at low energies (< 3 keV). The incident beam is chopped. Deflection plates allow a charge analysis of scattered particles after collision detected on a position sensitive detector. Secondary particles (electrons and ions) are collected on a 2{pi} detector made of 16 detection units (2 microchannel plates) Energy loss measurement (translational spectroscopy) associated to the detection of scattered particles in coincidence with secondary electrons emitted during the collision of neon lead to characterization of excited states of the target. Theses excited surface states, when localised at one halogen site are namely excitons and when localised at two holes are known as trions. This is the first characterisation of these states by ion impact at surfaces. For neon ions the capture is mediated by Auger neutralisation. Fluorine atoms collision confirmed the established threshold behaviour for the formation of negative fluorine ions. For positive incident fluorine, observation of negative ions under this threshold is an experimental evidence that double capture occurs at least under this threshold. According to the energy loss, interaction between two holes left at neighbouring sites on the surface is obvious. The statistical correlation is accompanied by spatial correlation where electron captures are made into neighbouring halogen sites. There is no experimental evidence to distinguish between bi-electronic capture and second order mono-electronic capture. A theoretical study seems to indicate that second order transition dominates the interaction. (author)

  13. Topics in atomic collision theory

    CERN Document Server

    Geltman, Sydney; Brueckner, Keith A

    1969-01-01

    Topics in Atomic Collision Theory originated in a course of graduate lectures given at the University of Colorado and at University College in London. It is recommended for students in physics and related fields who are interested in the application of quantum scattering theory to low-energy atomic collision phenomena. No attention is given to the electromagnetic, nuclear, or elementary particle domains. The book is organized into three parts: static field scattering, electron-atom collisions, and atom-atom collisions. These are in the order of increasing physical complexity and hence necessar

  14. Study of the production of J/{psi} in Au-Au collisions at 200 GeV per nucleon pair in the PHENIX experiment; Etude de la production du J/{psi} dans les collisions or-or a 200 GeV par paire de nucleons dans l'experience PHENIX

    Energy Technology Data Exchange (ETDEWEB)

    Tram, V.N

    2006-01-15

    One of the most promising signature of Quark Gluon Plasma formation is the heavy quarkonium suppression due to color screening effect. First experiments at the SPS (CERN) have measured an 'anomalous suppression' of the J/{psi} yields (cc-bar state) in central Pb+Pb collisions. However, measurements at different collision energies and with different ions are mandatory to conclude about the discovery of a new state of nuclear matter. This thesis describes the J/{psi} production measured in the dimuon decay channel by the PHENIX experiment (RHIC) studying Au+Au collisions at 200 GeV in the center of mass. The J/{psi} yield measured in the most central collisions is suppressed by a factor of 3 as compared to the yield expected assuming binary scaling. Within the error bars, the suppression does not affect the J/{psi}'s rapidity distribution. However, a broadening of the transverse momentum distribution is observed as compared to the distribution measured in p+p collisions. In order to understand this suppression, 'cold nuclear effects', namely nuclear absorption and shadowing, are to be taken into account. These effects can describe neither the suppression amplitude nor the suppression pattern, suggesting that other mechanisms are involved. Predictions from different models which reproduce the suppression observed by NA50, can hardly describe the PHENIX measurements and over-estimate the suppression at RHIC. Comparisons with predictions from models including recombination of charm quarks give a reasonable description of the suppression amplitude as a function of centrality. However, these predictions are not in good agreement with the observed rapidity and transverse momentum distributions. Finally, one possible scenario is that the temperature at RHIC is not high enough to reach direct J/{psi} melting and that the measured suppression is due to the sequential disappearance from higher mass resonances ({chi}{sub c} and {psi}'). In this

  15. Vocal Fold Collision Modeling

    DEFF Research Database (Denmark)

    Granados, Alba; Brunskog, Jonas; Misztal, M. K.

    2015-01-01

    When vocal folds vibrate at normal speaking frequencies, collisions occurs. The numerics and formulations behind a position-based continuum model of contact is an active field of research in the contact mechanics community. In this paper, a frictionless three-dimensional finite element model...... on the penalty parameter value. Furthermore, the Lagrange approach shows poor results with regard to instantaneous contact force estimation. This motivates the use of an Augmented Lagrange approach to regularize the Lagrange contact force solution. Finally, the effect of the interpenetration volume on contact...

  16. Molecular collision theory

    CERN Document Server

    Child, M S

    2010-01-01

    This high-level monograph offers an excellent introduction to the theory required for interpretation of an increasingly sophisticated range of molecular scattering experiments. There are five helpful appendixes dealing with continuum wavefunctions, Green's functions, semi-classical connection formulae, curve-crossing in the momentum representation, and elements of classical mechanics.The contents of this volume have been chosen to emphasize the quantum mechanical and semi-classical nature of collision events, with little attention given to purely classical behavior. The treatment is essentiall

  17. Collision of two Hopfions

    CERN Document Server

    Arrayás, M

    2016-01-01

    We study the collision of two hopfions or Hopf-Ra\\~nada electromagnetic fields. The superposition of two of such fields, travelling in opposite directions, yields different topology for the electric and magnetic field lines. Controlling the angular momentum of such fields, we can control the topology of the flow associated to the field lines, and the energy distribution. The concept of electromagnetic helicity and the exchange between its magnetic and electric components are used to explain the different behaviours observed when the angular momentum is reversed.

  18. Development of a spectral analyzer for radio-frequencies; Etude et realisation d'un analyseur de spectres pour radio-frequences

    Energy Technology Data Exchange (ETDEWEB)

    Bourbigot, J. [Commission a l' Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-04-01

    This report describes an apparatus designed to show on the screen of a cathode ray tube the amplitude and frequency distribution of the spectral components of a given signal. The frequency range is from 5 kHz to 25 MHz. Two fundamental elements are used in the development of this apparatus, a ferrite and a ring modulator. The basic properties of these elements are studied and discussed. A theoretical study for the determination of the fundamental parameters of the analyzer is presented in the Appendix. (author) [French] On decrit un appareil qui permet de representer sur l'ecran d'un tube a rayons cathodiques la distribution en frequence et en amplitude des composantes spectrales d'un signal donne. Il fonctionne dans la gamme de frequences s'etendant de 5 kHz a 25 MHz. Deux elements interviennent fondamentalement dans la realisation de cet appareil: un echantillon de ferrite et un modulateur en anneau. Des proprietes particulieres de ces elements sont etudiees et discutees. En annexe une theorie s'appliquant a la determination de parametres fondamentaux de l'analyseur est developpee. (auteur)

  19. Outer Dynamics of Ship Collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup

    1996-01-01

    The purpose is to present analysis procedures for the motion of ships during ship-ship collisions and for ship collisions with offshore structures. The aim is to estimate that part of the lost kinetic energy which will have to be absorbed by rupture and plastic damage of the colliding structures....

  20. Photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Collisions in young triple systems

    CERN Document Server

    Rawiraswattana, Krisada; Goodwin, Simon P

    2011-01-01

    We perform N-body simulations of young triple systems consisting of two low-mass companions orbiting around a significantly more massive primary. We find that, when the orbits of the companions are coplanar and not too widely separated, the chance of a collision between the two companions can be as high as 20 per cent. Collisions between one of the companions (always the less massive) and the primary can also occur in systems with unequal-mass companions. The chance of collisions is a few per cent in systems with more realistic initial conditions, such as with slightly non-coplanar orbits and unequal-mass companions. If the companions start widely separated then collision are very rare except in some cases when the total mass of the companions is large. We suggest that collisions between members of young multiple systems may explain some unusual young multiple systems such as apparently non-coeval companions.

  2. Influence of quantum diffraction and shielding on electron-ion collision in two-component semiclassical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Woo-Pyo [Department of Electronics Engineering, Catholic University of Daegu, Hayang 712-702 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590 (United States); Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of)

    2015-01-15

    The influence of quantum diffraction and shielding on the electron-ion collision process is investigated in two-component semiclassical plasmas. The eikonal method and micropotential taking into account the quantum diffraction and shielding are used to obtain the eikonal scattering phase shift and the eikonal collision cross section as functions of the collision energy, density parameter, Debye length, electron de Broglie wavelength, and the impact parameter. The result shows that the quantum diffraction and shielding effects suppress the eikonal scattering phase shift as well as the differential eikonal collision cross section, especially, in small-impact parameter regions. It is also shown that the quantum shielding effect on the eikonal collision cross section is more important in low-collision energies. In addition, it is found that the eikonal collision cross section increases with an increase in the density parameter. The variations of the eikonal cross section due to the quantum diffraction and shielding effects are also discussed.

  3. COLISÃO DE DIREITOS: A LIBERDADE DE IMPRENSA E OS DIREITOS DA PERSONALIDADE DE CRIANÇAS E ADOLESCENTES / COLLISION OF RIGHTS: FREEDOM OF THE PRESS AND RIGHTS OF PERSONALITY OF CHILDREN AND ADOLESCENTS

    Directory of Open Access Journals (Sweden)

    Rômulo Magalhães Fernandes

    2016-12-01

    Full Text Available This paper discusses the recurring theme of the collision of fundamental rights, in particular the rights of the personality of people in development and press freedom. In the current Brazilian scenario, where the mass media gains centrality in shaping and dissemination of information in the country, it is perceived by some mass media, the daily practice of exploring the use of the image of children and adolescents, in which they are exposed to vexatious and embarrassing situations. With no claim to suppress freedom of the press for the rights of children and adolescents, or vice versa, this article aims to deepen the solution of conflicts between those rights guaranteed in the Constitution of 1988. For this purpose, it is adopted as a method to resolve this conflict the weighting of property and assets from the application of the principle of proportionality in this case. In this sense, there are the doctrinal contributions of Robert Alexy and Ronald Dworkin and the study of decisions of the Supreme Court (STF.

  4. Transmission Sur Fibres Optiques Dans Un Systeme D'Archivage Et De Communication D'Images Pour Des Applications Medicales

    Science.gov (United States)

    Aaron, Gilles; Bonnard, Rene

    1984-03-01

    Dans l'hOpital, le besoin d'un reseau de communication electronique ne cesse de crottre au fur et a mesure de la numerisation des images. Ce reseau local a pour but de relier quelques sources d'images telles la radiologie numerique, la tomodensitometrie, la resonance magnetique nucleaire, l'echographie ultraso-nore etc..., a un systme d'archivage. Des consoles de visualisation interacti-ves peuvent etre utilisees dans les salles d'examens, les bureaux des medecins et les services de soins. Dans un tel systme, trois caracteristiques princi-pales doivent etre prises en compte le debit, la longueur du cable et le nombre de connexions. - Le debit est tr?)s important, en effet, un temps de reponse maxima de quel-ques secondes doit etre garanti pour des images de plusieurs millions d'ele-ments binaires. - La distance entre connexions peut etre de quelques km dans certains grands hopitaux. - Le nombre de connexions au reseau ne depasse jamais quelques dizaines car les sources d'images et les unites de traitement representent des materiels importants, par ailleurs les consoles de visualisation simples peuvent etre groupees en grappe. Toutes ces conditions sont remplies par les transmissions sur fibres optiques. Selon la topologie et la methode d'accNs, deux solutions peuvent etre envisa-gees : - Anneau actif - Etoile active ou passive Enfin, les developpements de Thomson-CSF en composants pour transmissions optiques pour les grands reseaux de tel4distribution nous apportent un support technologique et une production de masse qui diminuera les collts du materiel.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    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.

  6. Consumers’ Collision Insurance Decisions

    DEFF Research Database (Denmark)

    Austin, Laurel; Fischhoff, Baruch

    Using interviews with 74 drivers, we elicit and analyse how people think about collision coverage and, more generally, about insurance decisions. We compare the judgments and behaviours of these decision makers to the predictions of a range of theoretical models: (a) A model developed by Lee (2007......), which refines EU theory to incorporate income and predicts that property insurance is a normal good; (b) a mental accounting model based on the idea that consumers budget their income across consumption categories (Thaler, 1985); and (c) the baseline, classic EU theory, which predicts that insurance...... is an inferior good (Mossin, 1968). The behaviour reported by subjects in our study suggests that insurance is a normal good, while their verbal reports reveal desires to balance two conflicting goals in deductible decisions, keeping premiums “affordable” and keeping deductibles “affordable,” which suggests...

  7. Extraction of the high transverse momentum photons in proton + proton collisions at 200 GeV in the PHENIX experiment at RHIC; Isolation des photons de grande impulsion transverse dans les collisions proton+proton a 200 GeV dans l'experience PHENIX au RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Hadl Henni, Ahmed [Ecole doctorale STIM, Sciences et Technologies de l' Information et des Materiaux, Ecole Centrale de Nantes, Universite de Nantes, Ecole des Mines de Nantes, 1 rue de la Noe, BP 92101, 44321 Nantes Cedex 3 (France)

    2007-02-15

    Ultra-relativistic heavy ions collisions allow to reach a hot and dense matter. This new state, called Quarks and Gluons Plasma (QGP), would exist at the first moment of our universe according to the Big Bang theory. The PHENIX experiment, one of the interaction point of the RHIC collider at Brookhaven National Laboratory (USA), aims to study the QGP's signatures. Photons don't interact strongly with the matter and so are an accurate tool to explore the phase of QGP. Moreover photons are emitted during all the phases of the nuclear collision: from the initial state to the final hadronization. We will present a direct photon, produced by hard scattering process in the beginning of the collision, identification method (SICA, Spectroscopic Isolation Cut Analysis) applied on p + p collisions at 200 GeV. This method allows for a better discrimination between direct photons and the other contribution (mainly the electromagnetic decay of the neutral pion). One could find in this thesis the direct photon rate production obtained by SICA and compared to other analysis. With the p + p collisions we have an important reference for the more heavier collisions (Au + Au) where we assume the QGP formation. (author)

  8. Determination of the excitation energy and angular momentum of the quasi-projectiles produced in the heavy ion collisions Xe + Sn; Determination de l'energie d'excitation et du moment angulaire des quasi-projectiles produits dans les collisions d'ions lourds Xe + Sn

    Energy Technology Data Exchange (ETDEWEB)

    Genouin-Duhamel, Emmanuel [Lab. de Physique Corpusculaire, Caen Univ., 14 Caen (France)

    1999-04-08

    This work is a contribution to the study of properties of hot nuclei formed in heavy ion collisions at intermediate energies. The experiment has been performed with the INDRA multidetector. It is shown that most of the reaction cross section is associated with binary dissipative collisions, accompanied by the production of particles from a region between the two reaction partners. This study is focussed on excitation energy and angular momentum of projectile-like fragment (PLF) in {sup 129}Xe + {sup nat}Sn reactions from 25 to 50 MeV per nucleon. Several methods are used to characterize hot nuclei (velocity, charge, mass and excitation energy). All these methods are compared between them and indicate that high energies are deposited in the nuclei during collision (it may exceed the nucleus binding energy). The angular momentum transferred into intrinsic spin to PLF in the peripheral collisions has been deduced from angular distributions and kinetic energies of the emitted light charged particles (atomic number smaller ar equal to 2). Both methods agree qualitatively. The spin values decrease with the violence of the collision. These values correspond to values averaged over the whole deexcitation chain of nuclei. The predictions of transport models reproduce qualitatively the most peripheral collisions and suggest that high spins are transferred to PLF (from 30 to 50 {Dirac_h}). Larger angular momentum values are observed at the lowest incident energy. The time hierarchy in the evaporation process and the role of mid-rapidity emission are also discussed.

  9. Study and conception of the decay ring of a neutrino facility using the {beta} decays of the helium 6 and neon 18 nuclei produced by an intense beam of protons hitting various targets; Etude et conception de l'anneau de desintegration d'une usine a neutrinos utilisant les decroissances {beta} des noyaux helium 6 et neon 18 produits par un faisceau intense de protons frappant diverses cibles

    Energy Technology Data Exchange (ETDEWEB)

    Chance, A

    2007-09-15

    The study of the neutrino oscillation between its different flavours needs pure and very intense flux of energetic, well collimated neutrinos with a well determined energy spectrum. So, a dedicated machine seems necessary nowadays. Among the different concepts of neutrino facilities, the one which will be studied here, called Beta-Beams, lies on the neutrino production by beta decay of radioactive ions after their acceleration. More precisely, the thesis is focused on the study and the design of the race-track-shaped storage ring of the high energy ions. Its aim is to store the ions until decaying. After a brief description of the neutrino oscillation mechanism and a review of the different experiments, an introduction to the neutrino facility concept and more precisely to the Beta-Beams will be given. Then, the issues linked to the Beta-Beams will be presented. After a description of the beam transport formalism, a first design and the optical properties of the ring will be then given. The effects of the misalignment and of the field errors in the dipoles have been studied. The dynamic aperture optimization is then realized. Handling of the decay losses or the energy collimation scheme will be developed. The off-momentum injection needed in presence of a circulating beam will be explained. Finally, the specific radiofrequency program needed by the beam merging will be presented. (author)

  10. Study of the background noise generated by the accelerator PEP-2 with a CsI(Na) scanning ring. Study of mass difference between B neutral mesons by using BABAR detector and DI-leptons events; Etude du bruit de fond engendre par l'accelerateur PEP-2 avec un anneau de cristaux de CsI(Na). Etude des oscillations des mesons B neutres avec le detecteur BaBar en utilisant les evenements DI-Leptons

    Energy Technology Data Exchange (ETDEWEB)

    Domenico, G. de

    2000-06-14

    The first part of this report is dedicated to the CP-violation in the sector of B quarks and to its experimental proof through 2 major equipment: the B meson factory PEP-2 and the detector BABAR. The second part deals with the background noise generated by PEP-2. The third part presents the study of the oscillations of neutral B mesons with the detector BABAR. The study of the background noise shows important differences between the experimental data and the simulation. These differences are thought to be due on one hand to the lack of accuracy of pressure models that set the normalisation of the simulated background noise, and on the other hand to the absence of simulation of particles that undergo Coulomb diffusion and do more than a lap before bumping into the void tube. The second hypothesis is backed by the evaluation of the collimation effect of the beam that appears to be more important in experimental data than in the simulation. Among the main results given by the BABAR collaboration, the measurement of the oscillation frequency of the neutral B meson is very important. This measurement is based on semi-leptonic decays of B mesons in order to tag the favour of neutral B mesons at the very moment of their decay. The data analysis was performed over 2.3 10{sup 6} decays of B meson pairs and we obtained: {delta}m{sub d} = (0.495 {+-} 0.026 {+-} 0.023) {Dirac_h}ps{sup -1}. The accuracy on the value of {delta}m{sub d} could be improved by using tagging methods based on the semi-exclusive then exclusive reconstruction of neutral B mesons. (A.C.)

  11. Reversible Simulations of Elastic Collisions

    CERN Document Server

    Perumalla, Kalyan S

    2013-01-01

    Consider a system of N identical hard spherical particles moving in a d-dimensional box and undergoing elastic, possibly multi-particle, collisions. We develop a new algorithm that recovers the pre-collision state from the post-collision state of the system, across a series of consecutive collisions, with essentially no memory overhead. The challenge in achieving reversibility for an n-particle collision (where, n << N) arises from the presence of nd-d-1 degrees of freedom during each collision, and from the complex geometrical constraints placed on the colliding particles. To reverse the collisions in a traditional simulation setting, all of the particular realizations of these degrees of freedom during the forward simulation must be saved. This limitation is addressed here by first performing a pseudo-randomization of angles, ensuring determinism in the reverse path for any values of n and d. To address the more difficult problem of geometrical and dynamic constraints, a new approach is developed whic...

  12. L'anneau est resté dans l'ombre

    CERN Multimedia

    Monin, Valérie

    2004-01-01

    Approximately four thousand people came to Crozet to celebrate the fiftieth anniversary of CERN and to see the LHC illumination but were disappointed. It was not the full circumference of the LHC Ring which was floodlit as expected but only its eight access points (1 page)

  13. The study of the components of matter collective flow in the collisions of {sup 64} Zn on {sup 58} Ni at 35 to 79 MeV/u; Etude des composantes de l`ecoulement collectif de matiere dans les collisions {sup 64} Zn sur {sup 58} Ni de 35 a 79 MeV/u

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, R. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire

    1995-06-01

    In a nucleus-nucleus collision the collective motion of matter, emitted from the overlapping region, give information on the properties of nuclear matter out-of-equilibrium. The characteristics of this motion have been studied on the {sup 64} Zn on {sup 58} Ni system up to 79 MeV per nucleon, using the flow parameter and the azimuthal distributions. We studied the evolution of those quantities with the incident energy, the impact parameter and the charge of particle. The experiment has been done at GANIL using the multidetectors of light particles and fragments, Mur and Tonneau. For estimating the impact parameter, two global variables have been used: the average parallel velocity and the total perpendicular momentum. For determining the reaction plane two methods have been used: the transverse momentum analysis and the azimuthal correlation method. The results are not sensitive to the global variable or method. The measured values revealed the inversion of the direction of sideward flow. The energy of vanishing flow ranges from 55 to 75 MeV per nucleon when the impact parameter increases from 1 to 6 fm. In the same way, the aspect of the azimuthal distribution changes from in-plane to out-of-plane enhancement when the energy increases, providing with a new indication of change in the interaction dynamics. The energy of isotropic emission lies between 45 and 65 MeV per nucleon depending of the impact parameter. For alpha particles, the flow parameter and the azimuthal asymmetry are greater than for protons, due to a smaller thermal dispersion. A Landau-Vlasov model using a non-local Gogny force is able to reproduce the global characteristics experimentally observed (rapidity and transverse momentum distributions). The calculated flow and azimuthal asymmetry values reproduce the experimental ones for an incompressibility modulus near 230 MeV. The study of the dependence on nucleon-nucleon cross section in nuclear medium must be pursued. (author) 37 refs.

  14. Control of the 133 cesium cold collisions, search for a variation of the fine structure constant using a dual rubidium-cesium atomic fountain; Controle des collisions froides du cesium {sup 133}Cs: tests de la variation de la constante de structure fine a l'aide d'une fontaine atomique double rubidium-cesium

    Energy Technology Data Exchange (ETDEWEB)

    Marion, H

    2005-03-15

    We developed a method of measurement of the frequency shift due to the collisions between cold atoms. This is the main systematic limitation for the accuracy of the Cs{sup 133} based fountains ({approx} 10{sup -15} in relative frequency). Consequently, we can measure this effect near 0.5% This opens prospects for improvements of the fountains performances in term of accuracy until 10{sup -16}. The fountain has also obtained a stability about 10{sup -14} at 1 s. We discovered for the first time, at very low magnetic field (5 {+-} 1 mG), Feshbach resonances. We also took a new absolute measurement of the hyperfine transition of the Rb{sup 87}, which is the most precise ever carried out and is used now as definition for the secondary standard. By comparing this value with those measured the previous years, we could carry out a test of the stability of the fine structure constant on the level of 10{sup -15} /yr. We led local comparisons between atomic fountains and the other fountains of the laboratory. Most stable it is unrolled with a combined stability of 5.10{sup -14} at 1 s. The behavior of the difference of the two clocks goes like white frequency noise up to 3.10{sup -16}. The assessment of the dual fountain accuracy budget has been evaluated at 7.10{sup -16} for the cesium part and 8.10{sup -16} for the rubidium part. We contributed to the realization of the scale of International Atomic Time, by series of calibrations of hydrogen masers. An atomic comparison of fountain by satellite links was tested between our laboratory and our German counterpart. This measurement has determined the good agreement between the two clocks. (author)

  15. On Impact Mechanics in Ship Collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    The purpose of this paper is to present analytical, closed-form expressions for the energy released for crushing and the impact impulse during ship collisions. Ship-ship collisions, ship collisions with rigid walls and ship collisions with flexible offshore structures are considered. The derived ...

  16. Collision Geometry and Flow in Uranium+Uranium Collisions

    CERN Document Server

    Goldschmidt, Andy; Shen, Chun; Heinz, Ulrich

    2015-01-01

    Using event-by-event viscous fluid dynamics to evolve fluctuating initial density profiles from the Monte-Carlo Glauber model for U+U collisions, we report a "knee"-like structure in the elliptic flow as a function of collision centrality, located around the 0.5% most central collisions as measured by the final charged multiplicity. This knee is due to the preferential selection of tip-on-tip collision geometries by a high-multiplicity trigger. Such a knee structure is not seen in the STAR data. This rules out the two-component MC-Glauber model for initial energy and entropy production. Hence an enrichment of tip-tip configurations by triggering solely on high-multiplicity in the U+U collisions does not work. On the other hand, by using the Zero Degree Calorimeters (ZDCs) coupled with event-shape engineering such a selection is possible. We identify the selection purity of body-body and tip-tip events in full-overlap U+U collisions. By additionally constraining the asymmetry of the ZDC signals we can further ...

  17. On impact mechanics in ship collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    The purpose of this paper is to present analytical, closed-form expressions for the energy released for crushing and the impact impulse during ship collisions. Ship–ship collisions, ship collisions with rigid walls and ship collisions with flexible offshore structures are considered. The derived ...... of illustrative examples are presented. The procedure presented in the paper is well suited for inclusion in a probabilistic calculation model for damage of ship structures due to collisions....

  18. Radiative collision-induced photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Nayfeh, M.H.; Payne, M.G.

    1978-05-01

    Semiclassical expressions of two-photon ionization of atoms induced by radiative collisions are derived. The dependence of the ionization yield on the atomic forces, field intensity, and energy gap is derived. Although absorption tends to decrease as the field intensity rises due to stimulated emission at the second crossing, the two-photon ionization yield can be nearly saturated at the first crossing, thus enhancing the absorption. Both regions, ionization in single collisions and ionization between collisions, are treated. In the latter we find that saturation of the ionization can be achieved at much reduced intensities. This process promises an extremely sensitive method for studying radiative collisions, especially when absorption or fluorescence becomes extremely weak.

  19. Collisions of Vortex Filament Pairs

    Science.gov (United States)

    Banica, Valeria; Faou, Erwan; Miot, Evelyne

    2014-12-01

    We consider the problem of collisions of vortex filaments for a model introduced by Klein et al. (J Fluid Mech 288:201-248, 1995) and Zakharov (Sov Phys Usp 31(7):672-674, 1988, Lect. Notes Phys 536:369-385, 1999) to describe the interaction of almost parallel vortex filaments in three-dimensional fluids. Since the results of Crow (AIAA J 8:2172-2179, 1970) examples of collisions are searched as perturbations of antiparallel translating pairs of filaments, with initial perturbations related to the unstable mode of the linearized problem; most results are numerical calculations. In this article, we first consider a related model for the evolution of pairs of filaments, and we display another type of initial perturbation leading to collision in finite time. Moreover, we give numerical evidence that it also leads to collision through the initial model. We finally study the self-similar solutions of the model.

  20. Neuromorphic UAS Collision Avoidance Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Using biologically-inspired neuromorphic optic flow algorithms is a novel approach in collision avoidance for UAS. Traditional computer vision algorithms rely on...

  1. DROPLET COLLISION AND COALESCENCE MODEL

    Institute of Scientific and Technical Information of China (English)

    LI Qiang; CAI Ti-min; HE Guo-qiang; HU Chun-bo

    2006-01-01

    A new droplet collision and coalescence model was presented, a quick-sort method for locating collision partners was also devised and based on theoretical and experimental results, further advancement was made to the droplet collision outcome.The advantages of the two implementations of smoothed particle hydrodynamics (SPH)method were used to limit the collision of droplets to a given number of nearest droplets and define the probability of coalescence, numerical simulations were carried out for model validation. Results show that the model presented is mesh-independent and less time consuming, it can not only maintains the system momentum conservation perfectly, but not susceptible to initial droplet size distribution as well.

  2. collision zone of an ISR

    CERN Document Server

    This is a collision region from the world’s first proton collider, the Intersecting Storage Rings. The ISR was used at CERN from 1971-84 to study proton-proton collisions at the highest energy then available (60GeV). When operational, ISR collision regions were surrounded by detectors as shown in the photo. In 1972, the surprising discovery of fragments flying out sideways from head-on proton-proton collisions was the first evidence of quark-quark scattering inside the colliding protons . This was similar to Rutherford’s observation in 1911 of alpha particles scattering off the tiny nucleus inside atoms of gold. The ISR beamtubes had to be as empty as outer space, a vacuum 100 000 times better than other CERN machines at the time.

  3. collision region of the ISR

    CERN Multimedia

    1970-01-01

    This is a collision region from the world’s first proton collider, the Intersecting Storage Rings. The ISR was used at CERN from 1971-84 to study proton-proton collisions at the highest energy then available (60GeV). When operational, ISR collision regions were surrounded by detectors as shown in the photo. In 1972, the surprising discovery of fragments flying out sideways from head-on proton-proton collisions was the first evidence of quark-quark scattering inside the colliding protons . This was similar to Rutherford’s observation in 1911 of alpha particles scattering off the tiny nucleus inside atoms of gold. The ISR beamtubes had to be as empty as outer space, a vacuum 100 000 times better than other CERN machines at the time.

  4. Do speed cameras reduce collisions?

    Science.gov (United States)

    Skubic, Jeffrey; Johnson, Steven B; Salvino, Chris; Vanhoy, Steven; Hu, Chengcheng

    2013-01-01

    We investigated the effects of speed cameras along a 26 mile segment in metropolitan Phoenix, Arizona. Motor vehicle collisions were retrospectively identified according to three time periods - before cameras were placed, while cameras were in place and after cameras were removed. A 14 mile segment in the same area without cameras was used for control purposes. Five cofounding variables were eliminated. In this study, the placement or removal of interstate highway speed cameras did not independently affect the incidence of motor vehicle collisions.

  5. Airborne Collision Avoidance System X

    Science.gov (United States)

    2015-06-01

    avoidance system on behalf of the Federal Aviation Adminis- tration (FAA). The current Traffic Alert and Collision Avoidance System II (TCAS II...transformations to the National Airspace System are being imple- mented through the FAA’s Next-Genera- tion Air Transportation System (NextGen). With the goal...weighted states to provide a single, optimal action. If a collision avoidance This work is sponsored by the Federal Aviation Administration under Air

  6. Study of charge correlation for Z {<=} 2 obtained in Au+Au collisions with incident energy from 150 up to 400 MeV/A. FOPI detector is used; Etude des correlations des charges Z {<=} 2 obtenues lors des collisions Au+Au aux energies incidentes de 150 a 400 MeV/A avec le detecteur fopi

    Energy Technology Data Exchange (ETDEWEB)

    Pras, Ph

    1997-01-24

    In the first part of this work we present what information can be driven from heavy ion collision studies and what can be expected from the state equation of nuclear matter. We introduce the notion of centrality and the concept of spectator-participant. The different models of collisions are reviewed. The theory of correlations between light particles is used as a tool to predict some results about the shape and population density of theoretical spectra.The Coulomb model which implies a thermal interpretation of heavy ion collisions is modified in order to take excited states into account and to reproduce the collective phenomena of flow and squeeze-out. Within the frame of this modified Coulomb model 3 notions of nuclear temperature are compared. A discussion is lead to find out the temperature of nuclear matter at the very moment of fragmentation. (A.C.) 134 refs.

  7. Collision Geometry and Flow in Uranium+Uranium Collisions

    CERN Document Server

    Goldschmidt, Andy; Shen, Chun; Heinz, Ulrich

    2015-01-01

    Using event-by-event viscous fluid dynamics to evolve fluctuating initial density profiles from the Monte-Carlo Glauber model for U+U collisions, we report a "knee"-like structure in the elliptic flow as a function of collision centrality, located near 0.5% centrality as measured by the final charged multiplicity. This knee is due to the preferential selection of tip-on-tip collision geometries by a high-multiplicity trigger. Such a knee structure is not seen in the STAR data. This rules out the two-component MC-Glauber model for initial energy and entropy production. An enrichment of tip-tip configurations by triggering solely on high-multiplicity in the U+U collisions thus does not work. On the other hand, using the Zero Degree Calorimeters (ZDCs) coupled with event-shape engineering, we identify the selection purity of body-body and tip-tip events in the full-overlap U+U collisions. With additional constraints on the asymmetry of the ZDC signals one can further increases the probability of selecting tip-ti...

  8. Supersonic Cloud Collision-II

    CERN Document Server

    Anathpindika, S

    2009-01-01

    In this, second paper of the sequel of two papers, we present five SPH simulations of fast head-on cloud collisions and study the evolution of the ram pressure confined gas slab. Anathpindika (2008) (hereafter paper I) considered highly supersonic cloud collisions and examined the effect of bending and shearing instabilities on the shocked gas slab. The post-collision shock here, as in paper I, is also modelled by a simple barotropic equation of state (EOS). However, a much stiffer EOS is used to model the shock resulting from a low velocity cloud collision. We explore the parameter space by varying the pre-collision velocity and the impact parameter. We observe that pressure confined gas slabs become Jeans unstable if the sound crossing time, $t_{cr}$, is much larger than the freefall time, $t_{ff}$, of putative clumps condensing out of them. Self gravitating clumps may spawn multiple/larger $N$-body star clusters. We also suggest that warmer gas slabs are unlikely to fragment and may end up as diffuse gas c...

  9. Etude de la production de photons isolés dans les états finals hadroniques des collisions e+e- au LEP dans l'expérience ALEPH

    CERN Document Server

    Si Mohand, D

    Les photons isolés, observés dans les désintégrations hadroniques du bozon Z0 créé dans les annihilations électron-positron au LEP, proviennent essentiellement du rayonnement électromagnétique des quarks. Ces photons, qui ne sont pas affectés par la fragmentation, sont particulièrement sensibles à l'émission de gluons; leur étude, à l'aide d'algorithmes de simulation tels que JETSET, ARIADNE et HERWIG, constitue un moyen simple et précis de tester les différentes approches de QCD, en particulier dans la description de la compétition photon-gluon. Notre analyse a révélé que JETSET prédit (20±6)% moins de photons directs que le nombre mesuré expérimentalement. ARIADNE, en revanche, semble surestimer légèrement le taux de production de photons directs de (6±4)% alors que HERWIG reproduit fidèlement l'ensemble de nos mesures. Après correction des pertes d'acceptance et des effets d'hadronisation, le rapport d'embranchement du Z0 en hadrons plus photon, normalisé au rapport d'embranc...

  10. Study of the production of di-muons in In-In collisions in the experiment NA60 of CERN-SPS; Etude de la production des dimuons dans les collisions In-In dans l'experience NA60 au CERN-SPS

    Energy Technology Data Exchange (ETDEWEB)

    Ducroux, L

    2006-09-15

    CERN's experiment NA60 investigates the production of pairs of muons in In-In collisions at an energy of 158 GeV/c/nucleon. The experimental setting includes a vertex telescope composed of a series of pixel detectors submitted to a magnetic field. This telescope is located in the target area of the muon spectrometer and has given accurate information on the kinematics of the di-muons produced in the collisions. The information collected by the vertex telescope allows the discrimination of prompt events from those coming from the decay of resonances. We have used a method for the reconstruction of the tracks based on the principal component analysis (PCA). We have shown that the excess of di-muons in the domain of low masses comes from a broadening of the {rho} meson in the dense and hot medium produced by the collision. In the domain of intermediate masses (between that of {phi} and that of J/{psi}) the excess has a prompt feature and as a consequence an increase of the charm rate is banned. We have also proved that the production of J/{psi} was abnormal in In-In system as it was in Pb-Pb collisions. (A.C.)

  11. Chemical and dynamics properties of heavy ion collisions at RHIC energies by the measurement of the production of the doubly strange baryons in the STAR experiment; Proprietes chimiques et dynamiques des collisions d'ions lourds aux energies du RHIC par la mesure de la production des baryons doublement etranges dans l'experience STAR

    Energy Technology Data Exchange (ETDEWEB)

    Estienne, M

    2005-04-15

    Lattice QCD calculations predict, at {mu}{sub B} {approx} 0, a crossover from ordinary hadronic matter to a Quark Gluon Plasma. Heavy ion collisions have been proposed to recreate it in the laboratory and to study its properties. The Au+Au, d+Au collisions at {radical}(S{sub NN}) = 200 GeV and the Au+Au ones at 62.4 GeV delivered at RHIC have been probed by the measurement of the {xi} particles in the STAR experiment. Their yield evolution with collision energy and system size gives size to the chemical properties of the reaction in the framework of hadronic and statistical models. The {xi} R{sub CP} shows: (1) a meson/baryon dependence for 2 < {sub pT} < 5 GeV/c well reproduced by quark coalescence and recombination models, (2) the formation of a dense matter signed by a R{sub CP} suppression at {sub pT} > 3 GeV/c, (3) strong interactions between constituents suggesting the existence of strong collectivity in the medium. The {xi} transverse flow seems to be interesting to probe the early stage the collision with presumably partonic degrees of freedom. (author)

  12. Quantum diffraction effects on the atomic polarization collision in partially ionized dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Electrical and Computer Engineering, MC 0407, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0407, USA and Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of)

    2014-04-15

    The influence of quantum diffraction on the electron-atom polarization collision process is investigated in partially ionized dense plasmas. The pseudopotential model and eikonal method are employed to obtain the eikonal phase shift and eikonal cross section as functions of the impact parameter, collision energy, Debye length, electron de Broglie wavelength, and atomic polarizability. The results show that the eikonal phase shift for the electron-hydrogen atom polarization collision decreases with an increase of the electron de Broglie wavelength. It is important to note that the influence of quantum diffraction produces the repulsive part in the electron-atom polarization interaction. It is also found that the quantum diffraction effect enhances the differential eikonal cross section. Additionally, the total eikonal cross section decreases with increasing electron de Broglie wavelength. The variations of the eikonal cross section due to the influence of finite size of the de Broglie wavelength and Debye radius are also discussed.

  13. Survey of Collision Avoidance and Ranging Sensors for Mobile Robots. Revision 1

    Science.gov (United States)

    1992-12-01

    AD-A269 846 Technical Report 1194 December 1992 Survey of Collision Avoidance and Ranging Sensors for Mobile Robots Revision 1 H. R. Everett D. E...Survey of Collision Avoidance and Ranging Sensors for Mobile Robots Revision 1 H. R. Everett D. E. DeMuth E. H. Stitz Accesior. For NTIS CRA&M DTIC TAB...3.3.7 Error Eliminating Rapid Ultrasonic Firing ........................ 118 3.3.8 Potential Field Obstacle Avoidance for Large Mobile Robots ........ 118

  14. L'astronomie dans le monde

    OpenAIRE

    Manfroid, Jean

    2012-01-01

    L’anneau F de Saturne; Planètes rocheuses et zonehabitable; Lentilles gravitationnelles; Neutrinos volages; Compter les bulles; BOSS; Kepler; Tourbillon martien; Pointillés martiens; Bombardement; Trous noirs voraces; Matière noire

  15. QCD in heavy ion collisions

    CERN Document Server

    Iancu, Edmond

    2014-01-01

    These lectures provide a modern introduction to selected topics in the physics of ultrarelativistic heavy ion collisions which shed light on the fundamental theory of strong interactions, the Quantum Chromodynamics. The emphasis is on the partonic forms of QCD matter which exist in the early and intermediate stages of a collision -- the colour glass condensate, the glasma, and the quark-gluon plasma -- and on the effective theories that are used for their description. These theories provide qualitative and even quantitative insight into a wealth of remarkable phenomena observed in nucleus-nucleus or deuteron-nucleus collisions at RHIC and/or the LHC, like the suppression of particle production and of azimuthal correlations at forward rapidities, the energy and centrality dependence of the multiplicities, the ridge effect, the limiting fragmentation, the jet quenching, or the dijet asymmetry.

  16. Polarized Proton Collisions at RHIC

    CERN Document Server

    Bai, Mei; Alekseev, Igor G; Alessi, James; Beebe-Wang, Joanne; Blaskiewicz, Michael; Bravar, Alessandro; Brennan, Joseph M; Bruno, Donald; Bunce, Gerry; Butler, John J; Cameron, Peter; Connolly, Roger; De Long, Joseph; Drees, Angelika; Fischer, Wolfram; Ganetis, George; Gardner, Chris J; Glenn, Joseph; Hayes, Thomas; Hseuh Hsiao Chaun; Huang, Haixin; Ingrassia, Peter; Iriso, Ubaldo; Laster, Jonathan S; Lee, Roger C; Luccio, Alfredo U; Luo, Yun; MacKay, William W; Makdisi, Yousef; Marr, Gregory J; Marusic, Al; McIntyre, Gary; Michnoff, Robert; Montag, Christoph; Morris, John; Nicoletti, Tony; Oddo, Peter; Oerter, Brian; Osamu, Jinnouchi; Pilat, Fulvia Caterina; Ptitsyn, Vadim; Roser, Thomas; Satogata, Todd; Smith, Kevin T; Svirida, Dima; Tepikian, Steven; Tomas, Rogelio; Trbojevic, Dejan; Tsoupas, Nicholaos; Tuozzolo, Joseph; Vetter, Kurt; Wilinski, Michelle; Zaltsman, Alex; Zelenski, Anatoli; Zeno, Keith; Zhang, S Y

    2005-01-01

    The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limite...

  17. Collision Rate Monitors for LHC

    CERN Document Server

    Bravin, E; Burger, S; Byrd, J M; Chow, K; Dutriat, C; Jolliot, M; Lefèvre, T; Matis, H S; Monroy, M; Talanov, V; Turner, W C; Ratti, A; Renet, S

    2007-01-01

    Collision rate monitors are essential in bringing particle beams into collision and optimizing the performances of a collider. In the case of LHC the relative luminosity will be monitored by measuring the flux of small angle neutral particles produced in the collisions. Due to the very different luminosity levels at the four interaction regions (IR) of LHC two different types of monitors have been developed. At the high luminosity IR (ATLAS and CMS) fast ionization chambers will be installed while at the other two (ALICE and LHC-b) solid state polycrystalline Cadmium Telluride (CdTe) detectors will be used. The ionization chambers are being developed by LBNL while the CdTe monitors are being developed by CERN and CEA-LETI.

  18. Semiholography for heavy ion collisions

    CERN Document Server

    Mukhopadhyay, Ayan

    2016-01-01

    The formation of QGP in heavy ion collisions gives us a great opportunity for learning about nonperturbative dynamics of QCD. Semiholography provides a new consistent framework to combine perturbative and non-perturbative effects in a coherent way and can be applied to obtain an effective description for heavy ion collisions. In particular, it allows us to include nonperturbative effects in existing glasma effective theory and QCD kinetic theory for the weakly coupled saturated degrees of freedom liberated by the collisions in the initial stages in a consistent manner. We argue why the full framework should be able to confront experiments with only a few phenomenological parameters and present feasibility tests for the necessary numerical computations. Furthermore, we discuss that semiholography leads to a new description of collective flow in the form of a generalised non-Newtonian fluid. We discuss some open questions which we hope to answer in the near future.

  19. Timescales in heavy ion collisions

    CERN Document Server

    Lisa, Mike

    2016-01-01

    The study of high energy collisions between heavy nuclei is a field unto itself, distinct from nuclear and particle physics. A defining aspect of heavy ion physics is the importance of a bulk, self-interacting system with a rich space-time substructure. I focus on the issue of timescales in heavy ion collisions, starting with proof from low-energy collisions that femtoscopy can, indeed, measure very long timescales. I then discuss the relativistic case, where detailed measurements over three orders of magnitude in energy reveal a timescale increase that might be due to a first-order phase transition. I discuss also consistency in evolution timescales as determined from traditional longitudinal sizes and a novel analysis using shape information.

  20. Plasma diagnostics of the SIMPA Ecr ion source by X-ray spectroscopy, Collisions of H-like Neon ions with Argon clusters; Diagnostic du plasma de la source d'ions ECR SIMPA par spectroscopie X, Collision d'ions neon hydrogenoides avec des agregats d'argon

    Energy Technology Data Exchange (ETDEWEB)

    Adrouche, N

    2006-09-15

    The first part of this thesis is devoted to the SIMPA ECR ion source characterization, first, I explored the ion source's capacities on the point of view of extracted currents for three elements, argon, krypton and neon. By analyzing the Bremsstrahlung spectra, I determined the electronic temperature in the plasma and the electronic and ionic densities. In a second time, I recorded high resolution X-spectra of argon and krypton plasma's. By taking into account the principal mechanisms of production of a K hole in the ions inside the plasma, I determined the ionic densities of the high charge states of argon. Lastly, I highlighted a correlation between the ions charge states densities with the intensities of extracted currents. The second part of the thesis is devoted to Ne{sup 9+-} argon clusters collisions. First, I presented simple and effective theoretical models allowing to describe the phenomena occurring during a collision, from the point of view of the projectile. I carried out a simulation for a collision of an ion Ne{sup 9+} with an argon cluster of a given size, which has enabled us to know the energy levels populated during the electronic capture and to follow the number of electrons in each projectile shell. Lastly, I presented the first results of a collision between a Ne{sup 9+} beam and argon clusters. These results, have enabled me by using projectile X-ray spectroscopy during the ions-clusters collision, to evidence a strong clustering of targets atoms and to highlight an electronic multi-capture in the projectile ion excited states. (author)

  1. MULTIPLE GALAXY COLLISIONS

    Science.gov (United States)

    2002-01-01

    Here is a sampling of 15 ultraluminous infrared galaxies viewed by NASA's Hubble Space Telescope. Hubble's sharp vision reveals more complexity within these galaxies, which astronomers are interpreting as evidence of a multiple-galaxy pileup. These images, taken by the Wide Field and Planetary Camera 2, are part of a three-year study of 123 galaxies within 3 billion light-years of Earth. The study was conducted in 1996, 1997, and 1999. False colors were assigned to these photos to enhance fine details within these coalescing galaxies. Credits: NASA, Kirk Borne (Raytheon and NASA Goddard Space Flight Center, Greenbelt, Md.), Luis Colina (Instituto de Fisica de Cantabria, Spain), and Howard Bushouse and Ray Lucas (Space Telescope Science Institute, Baltimore, Md.)

  2. Forme des territoires communaux et structure du bâti dans les cantons de Vaud et de Neuchâtel

    Directory of Open Access Journals (Sweden)

    Daniel Glauser

    2012-04-01

    Full Text Available En Suisse romande, la topographie marquée du paysage allant de la chaîne jurassienne à celle des Alpes, ainsi que l'histoire du peuplement, ont contribué à générer une grande variété de formes de colonisation. Dans les cantons de Vaud et de Neuchâtel notamment, on observe aussi bien du paysage de bocage que des territoires marqués par l'assolement triennal collectif avec des exploitations agricoles en « champs ouverts » (openfield. Les villages sont organisés selon une grande variété de schémas, avec des structures linéaires horizontales, montantes ou en épi, des formes rayonnantes sur un point ou sur un anneau. La dispersion de l'habitat rural obéit également à différents modèles : petits hameaux, par unité d'exploitation avec une répartition alvéolaire ou en bandes des domaines.In French-speaking Switzerland, the characteristic topography of the landscape, between the mountain ranges of the Jura and the Alps, along with the history of how these landscapes were peopled, have given rise to a wide variety of forms of settlement. In the cantons of Vaud and Neufchatel in particular, there are landscapes of mixed pasture and woodland (bocage as well as territories characterised by the collective three-field system with open-field farms. The villages too are structured according to a broad variety of patterns: horizontal linear structures, structures going up the slope with branches going off at angles, structures with radial patterns leading off from a central point or from a ring. Dispersed rural dwellings also follow different models: small hamlets with individual farms or with organisations in honeycomb patterns or bands of property.

  3. Diffractive Bremsstrahlung in Hadronic Collisions

    Directory of Open Access Journals (Sweden)

    Roman Pasechnik

    2015-01-01

    Full Text Available Production of heavy photons (Drell-Yan, gauge bosons, Higgs bosons, and heavy flavors, which is treated within the QCD parton model as a result of hard parton-parton collision, can be considered a bremsstrahlung process in the target rest frame. In this review, we discuss the basic features of the diffractive channels of these processes in the framework of color dipole approach. The main observation is a dramatic breakdown of diffractive QCD factorisation due to the interplay between soft and hard interactions, which dominates these processes. This observation is crucial for phenomenological studies of diffractive reactions in high energy hadronic collisions.

  4. Collision Risk Analysis for HSC

    DEFF Research Database (Denmark)

    Urban, Jesper; Pedersen, Preben Terndrup; Simonsen, Bo Cerup

    1999-01-01

    High Speed Craft (HSC) have a risk profile, which is distinctly different from conventional ferries. Due to different hull building material, structural layout, compartmentation and operation, both frequency and consequences of collision and grounding accidents must be expected to be different from...... conventional ships. To reach a documented level of safety, it is therefore not possible directly to transfer experience with conventional ships. The purpose of this paper is to present new rational scientific tools to assess and quantify the collision risk associated with HSC transportation. The paper...

  5. Collisions in Chiral Kinetic Theory

    CERN Document Server

    Chen, Jing-Yuan; Stephanov, Mikhail A

    2015-01-01

    Using a covariant formalism, we construct a chiral kinetic theory Lorentz invariant to order $\\mathcal O(\\hbar)$ which includes collisions. We find a new contribution to the particle number current due to the side jumps required by the conservation of angular momentum during collisions. We also find a conserved symmetric stress-energy tensor as well as the $H$-function obeying Boltzmann's $H$-theorem. We demonstrate their use by finding a general equilibrium solution and the values of the anomalous transport coefficients characterizing chiral vortical effect.

  6. NA49: lead-lead collision

    CERN Document Server

    1996-01-01

    This is an image of an actual lead ion collision taken from tracking detectors on the NA49 experiment, part of the heavy ion project at CERN. These collisions produce a very complicated array of hadrons as the heavy ions break up. It is hoped that one of these collisions will eventually create a new state of matter known as quark-gluon plasma.

  7. General characteristics of hadron-hadron collisions

    CERN Document Server

    Kittel, E W

    2004-01-01

    Soft multiparticle production in hadron-hadron collisions is reviewed with particular emphasis on its role as a standard for heavy-ion collisions at SPS and RHIC energies and as a bridge interpolating between the most simple e **+e**- and the most complex AA collisions.

  8. Study of the muon production from open heavy flavours predicted by the Color Glass Condensate model in proton-proton and proton-lead collision with the Alice muon spectrometer at LHC; Etude de la production de muons issus des saveurs lourdes predite par le modele de Color Glass Condensate dans les collisions proton-proton et proton-plomb dans l'acceptance du spectrometre a muons de l'experience Alice du LHC

    Energy Technology Data Exchange (ETDEWEB)

    Charpy, A

    2007-10-15

    The whole particle physics community is waiting for the Large Hadron Collider (LHC) commissioning at CERN. Indeed, the potential of discovery is very large in lots of themes. In particular, it will be possible to test the developments of the Quantum Chromodynamics (QCD) achieved during last years. One of these, the Colour Glass Condensate, describes the parton distributions of the nucleus in the saturation region, i.e. at small x. This theoretical description of the initial conditions of the heavy ion collisions is necessary to predict the heavy quark cross section production which evolves in a possible deconfined matter: the Quark-Gluon Plasma (PQG). ALICE is the LHC experiment mainly dedicated to the study of the PQG produced in ultra-relativistic heavy ion collisions. The measurement of J /{psi} and {upsilon} resonance suppression is a signature of this deconfined medium which is studied with the ALICE muon spectrometer. Its acceptance at large rapidity is well adapted for studying the prediction of CGC at small-x. The first part of this report presents the results of beam test experiment at CERN. It was the first time that the muon spectrometer tracking chambers were tested equipped with the final version of the front end electronics and the data acquisition system CROCUS. The relevant calibration parameters of the front end electronics were introduced in the analysis in order to improve the quality of the track reconstruction. In the second part. these parameters were used in the simulations. The last part proposes a study of the CGC with the ALICE muon spectrometer. involving the measurements of open charm and open beauty. (author)

  9. Dijet imbalance in hadronic collisions

    NARCIS (Netherlands)

    Boer, Daniel; Mulders, Piet J.; Pisano, Cristian

    2009-01-01

    The imbalance of dijets produced in hadronic collisions has been used to extract the average transverse momentum of partons inside the hadrons. In this paper we discuss new contributions to the dijet imbalance that could complicate or even hamper this extraction. They are due to polarization of init

  10. High velocity collisions of nanoparticles

    Science.gov (United States)

    Johnson, Donald F.; Mattson, William D.

    2017-01-01

    Nanoparticles (NPs) are a unique class of material with highly functionalizable surfaces and exciting applications. With a large surface-to-volume ratio and potentially high surface tension, shocked nanoparticles might display unique materials behavior. Using density functional theory, we have simulated high-velocity NP collisions under a variety of conditions. NPs composed of diamond-C, cubic-BN, and diamond-Si were considered with particle sizes up to 3.5 nm diameter. Additional simulations involved NPs that were destabilized by incorporating internal strain. The initial spherical NP structures were carved out of bulk crystals while the NPs with internal strain were constructed as a dense core (compressive strain) encompassed by a thin shell (tensile strain). Both on-axis and off-axis collisions were simulated at 10 km/s relative velocity. The amount of internal strain was artificially increased by creating a dense inner core with bond lengths compressed up to 8%. Collision dynamics, shock propagation, and fragmentation will be analyzed, but the simulation are ongoing and results are not finalized. The effect of material properties, internal strain, and collision velocity will be discussed.

  11. Cern collisions light up Copenhagen

    CERN Multimedia

    Banks, Michael

    2010-01-01

    "Anyone passing by the Niels Bohr Institute in Copenhagen, Denmark, might be startled by some strange moving lights on the facade of the institute's main building. In fact, the dancing beams show, almost in real time, collisions form the Atlas experiment at Cern's Large Hadron Collider (LHC)" (1 paragraph)

  12. Quarkonium production in hadronic collisions

    Energy Technology Data Exchange (ETDEWEB)

    Gavai, R. [Tata Institute for Fundamental Research, Bombay (India); Schuler, G.A.; Sridhar, K. [CERN, Geneva (Switzerland)] [and others

    1995-07-01

    We summarize the theoretical description of charmonium and bottonium production in hadronic collisions and compare it to the available data from hadron-nucleon interactions. With the parameters of the theory established by these data, we obtain predictions for quarkonium production at RHIC and LHC energies.

  13. Outer Dynamics of Ship Collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup

    1996-01-01

    The purpose of these notes is to present analysis procedures for the motion of ships during ship-ship collisions and for ship collisons with offshore structures. The aim is to estimate that part of the lost kinetic energy which will have to be absorbed by rupture and plastic damage of the collidi...

  14. Study of the production of {phi}, {rho}, {omega} mesons in the ultra-relativistic heavy ion collisions at the SPS of CERN; Etude de la production des mesons {phi}, {rho} et {omega} dans les collisions d'ions lourds ultra-relativistes au SPS du CERN (dans l'experience NA50)

    Energy Technology Data Exchange (ETDEWEB)

    Villatte, L

    2001-03-28

    The NA50 experiment is one of the experiment using the SPS (Super Proton Synchrotron) beam at CERN (european laboratory for particle physics). One of the common aim of the SPS experiment is to look for the existence of a new state of the nuclear matter: the quark-gluon plasma. Among the proposed signatures of the quark-gluon plasma is the enhanced production of particles containing strange quarks. In the current work, the NA50/NA38 experiment data are analysed and the relative production of the {phi} and {rho} + {omega} mesons are obtained from Pb-Pb collisions at 158 and S-U at 200 GeV per nucleon. The measured ({phi}/({rho} +{omega})){mu}{mu} ratio as a function of the transverse mass does not present any unexpected behavior, however, central collisions as compared to peripheral collisions show an increase by a factor 1.7. The {phi} and {rho}+{omega} multiplicities are extracted for the Pb-Pb collisions and show that the enhancement of the ({phi}/({rho}+{omega})){mu}{mu} ratio is due to the {phi} meson production increase. The evolution of the {phi} meson multiplicity, versus the number of participant nucleus (N{sub part}), is different from that of the multi-strange baryons. The effective temperatures are deduced from the study of the {phi} and {rho} + {omega} production cross sections with respect to the transverse mass and compared to those obtained by other experiments and other particles. An additional study is done to extract the K/{pi} ratio versus N{sub part}. (authors)

  15. Observation of atomic collisions in crystalline solids

    CERN Document Server

    Nelson, R S; Gevers, R

    2013-01-01

    The Observation of Atomic Collisions in Crystalline Solids presents a critical account of the more important experiments which have provided the basis for a better understanding of atomic collision phenomena in crystalline solids. Collisions have been divided into two artificial regimes; primary collisions which deal with the interaction of the incident particles with the solid, and secondary collisions which deal with those events which occur as a result of lattice atoms recoiling from primary encounters. Although the book is intended principally for the experimentalist some simple theoretica

  16. Relaciones entre topografía del terreno y morfología de los edificios volcánicos basálticos monogénicos de Tenerife (Islas Canarias, España

    Directory of Open Access Journals (Sweden)

    Dóniz Páez, Javier

    2011-06-01

    volcans en forme d’anneau et des 205 en forme de fer à cheval. On peut observer qu’il existe dans les deux cas des corrélations élevées de l’ordre de 0,95. 95% des volcans en forme d’anneau sont situés dans des zones topographiques planes (< 10°, tandis que 95% des volcans ouverts en forme de fer à cheval se trouvent dans des zones topographiques plus accidentées. Traditionnellement, la topographie a été considérée un facteur secondaire dans la forme des volcans. Pourtant, selon ces données, il s’agit d’un facteur clé qui contrôle la morphologie des volcans basaltiques monogéniques.

  17. Photonic, Electronic and Atomic Collisions

    Science.gov (United States)

    Fainstein, Pablo D.; Lima, Marco Aurelio P.; Miraglia, Jorge E.; Montenegro, Eduardo C.; Rivarola, Roberto D.

    2006-11-01

    Plenary. Electron collisions - past, present and future / J. W. McConkey. Collisions of slow highly charged ions with surfaces / J. Burgdörfer ... [et al.]. Atomic collisions studied with "reaction-microscopes" / R. Moshammer ... [et al.]. Rydberg atoms: a microscale laboratory for studying electron-molecule tnteractions / F. B. Dunning -- Collisions involvintg photons. Quantum control of photochemical reaction dynamics and molecular functions / M. Yamaki ... [et al.]. Manipulating and viewing Rydberg wavepackets / R. R. Jones. Angle-resolved photoelectrons as a probe of strong-field interactions / M. Vrakking. Ultracold Rydberg atoms in a structured environment / I. C. H. Liu and J. M. Rost. Synchrotron-radiation-based recoil ion momentum spectroscopy of laser cooled and trapped cesium atoms / L. H. Coutinho. Reconstruction of attosecond pulse trains / Y. Mairesse ... [et al.]. Selective excitation of metastable atomic states by Femto- and attosecond laser pulses / A. D. Kondorskiy. Accurate calculations of triple differential cross sections for double photoionization of the hygrogen molecule / W. Vanroose ... [et al.]. Double and triple photoionization of Li and Be / J. Colgan, M. S. Pindzola and F. Robicheaux. Few/many body dynamics in strong laser fields / J. Zanghellini and T. Brabec. Rescattering-induced effects in electron-atom scattering in the presence of a circularly polarized laser field / A. V. Flegel ... [et al.]. Multidimensional photoelectron spectroscopy / P. Lablanquie ... [et al.]. Few photon and strongly driven transitions in the XUV and beyond / P. Lambropoulos, L. A. A. Nikolopoulos and S. I. Themelis. Ionization dynamics of atomic clusters in intense laser pulses / U. Saalmann and J. M. Rost. On the second order autocorrelation of an XUV attosecond pulse train / E. P. Benis ... [et al.]. Evidence for rescattering in molecular dissociation / I. D. Williams ... [et al.]. Photoionizing ions using synchrotron radiation / R. Phaneuf. Photo double

  18. Fluid moments of the nonlinear Landau collision operator

    Science.gov (United States)

    Hirvijoki, Eero; Lingam, Manasvi; Pfefferlé, David; Comisso, Luca; Candy, Jeff; Bhattacharjee, Amitava

    2016-10-01

    One important problem in plasma physics is the lack of an accurate and complete description of Coulomb collisions in associated fluid models. To shed light on the problem, this work introduces an integral identity involving the multivariate Hermite tensor polynomials and presents a method for computing exact expressions for the fluid moments of the nonlinear Landau collision operator. The proposed methodology provides a systematic and rigorous means of extending the validity of fluid models that have an underlying inverse-square force particle dynamics to arbitrary collisionality and flow. (For details, see arXiv:1605.07589) This research is supported by the Department of Energy Contract No. DE-AC02-09CH11466 and the National Science Foundation Grant Nos. AGS-1338944 and AGS-1552142.

  19. Shielding ultracold dipolar molecular collisions with electric fields

    Science.gov (United States)

    Quéméner, Goulven; Bohn, John

    2016-05-01

    The prospect for shielding ultracold dipolar molecules from inelastic and reactive collisions is investigated. Molecules placed in their first rotationally excited states are found to exhibit effective long-range repulsion for applied electric fields above a certain critical value. This repulsion can safely allow the molecules to scatter while reducing the risk of inelastic or chemically reactive collisions. Several molecular species of molecules of experimental interest such as NaRb, NaK, RbSr, SrF, BaF, and YO, are considered and all are shown to exhibit orders of magnitude suppression in quenching rates in a sufficiently strong laboratory electric field. We acknowledge the financial support of the COPOMOL project (ANR-13-IS04-0004) from Agence Nationale de la Recherche and the ARO MURI Grant No. W911NF-12-1-0476.

  20. Diphoton production in high-energy p+A collisions

    CERN Document Server

    Kovner, Alex

    2014-01-01

    We consider semi-inclusive diphoton+jet and inclusive diphoton production in high-energy proton-nucleus collisions, treating the target nucleus as a Color-Glass-Condensate while the projectile proton in the parton model. We obtain the prompt diphoton production cross-section in terms of fragmentation and direct contributions. The fragmentation part is given in terms of single-photon and double-photon fragmentation functions. We study prompt, direct and fragmentation diphoton correlations in p+p and p+A collisions at the LHC, and show that at low values of transverse momenta of the produced photon pair, these correlations are sensitive to saturation effects. We show that back-to-back (de)-correlations in prompt diphoton production are stronger in fragmentation part than in the direct one.

  1. Diphoton production in high-energy p+A collisions

    Science.gov (United States)

    Kovner, Alex; Rezaeian, Amir H.

    2014-07-01

    We consider semi-inclusive diphoton +jet and inclusive diphoton production in high-energy proton-nucleus collisions, treating the target nucleus as a color-glass condensate and the projectile proton in the parton model. We obtain the prompt diphoton production cross section in terms of fragmentation and direct contributions. The fragmentation part is given in terms of single-photon and double-photon fragmentation functions. We study prompt, direct, and fragmentation diphoton correlations in p +p and p +A collisions at the LHC and show that at low values of transverse momenta of the produced photon pair these correlations are sensitive to saturation effects. We show that back-to-back (de)correlations in prompt diphoton production are stronger in the fragmentation part than in the direct one.

  2. Cosmic Collisions The Hubble Atlas of Merging Galaxies

    CERN Document Server

    Christensen, Lars Lindberg; Martin, Davide

    2009-01-01

    Lars Lindberg Christensen, Raquel Yumi Shida & Davide De Martin Cosmic Collisions: The Hubble Atlas of Merging Galaxies Like majestic ships in the grandest night, galaxies can slip ever closer until their mutual gravitational interaction begins to mold them into intricate figures that are finally, and irreversibly, woven together. It is an immense cosmic dance, choreographed by gravity. Cosmic Collisions contains a hundred new, many thus far unpublished, images of colliding galaxies from the NASA/ESA Hubble Space Telescope. It is believed that many present-day galaxies, including the Milky Way, were assembled from such a coalescence of smaller galaxies, occurring over billions of years. Triggered by the colossal and violent interaction between the galaxies, stars form from large clouds of gas in firework bursts, creating brilliant blue star clusters. The importance of these cosmic encounters reaches far beyond the stunning Hubble images. They may, in fact, be among the most important processes that shape ...

  3. Probing transverse momentum broadening in heavy ion collisions

    Science.gov (United States)

    Mueller, A. H.; Wu, Bin; Xiao, Bo-Wen; Yuan, Feng

    2016-12-01

    We study the dijet azimuthal de-correlation in relativistic heavy ion collisions as an important probe of the transverse momentum broadening effects of a high energy jet traversing the quark-gluon plasma. We take into account both the soft gluon radiation in vacuum associated with the Sudakov logarithms and the jet PT-broadening effects in the QCD medium. We find that the Sudakov effects are dominant at the LHC, while the medium effects can play an important role at RHIC energies. This explains why the LHC experiments have not yet observed sizable PT-broadening effects in the measurement of dijet azimuthal correlations in heavy ion collisions. Future investigations at RHIC will provide a unique opportunity to study the PT-broadening effects and help to pin down the underlying mechanism for jet energy loss in a hot and dense medium.

  4. Collisions engineering. Theory and applications

    Energy Technology Data Exchange (ETDEWEB)

    Fremond, Michel [Rome ' ' Tor Vergata' ' Univ. (Italy). Dept. of Civil Engineering and Computer Science

    2017-02-01

    This book investigates collisions occurring in the motion of solids, in the motion of fluids but also in the motion of pedestrians in crowds. The duration of these presented collisions is short compared to the whole duration of the motion: they are assumed instantaneous. The innovative concept demonstrated in this book is that a system made of two solids, is deformable because their relative position changes. The definition of the velocities of deformation of the system introduced in the classical developments of mechanics, the principle of the virtual work and the laws of thermodynamics, allows a large range of applications such as crowd motions, debris flow motions, and shape memory alloys motions. The set of the applications is even larger: social sciences and mechanics are unified to predict the motion of crowds with application to transport management and to evacuation of theaters management.

  5. Collisions engineering theory and applications

    CERN Document Server

    Frémond, Michel

    2017-01-01

    This book investigates collisions occurring in the motion of solids, in the motion of fluids but also in the motion of pedestrians in crowds. The duration of these presented collisions is short compared to the whole duration of the motion: they are assumed instantaneous. The innovative concept demonstrated in this book is that a system made of two solids, is deformable because their relative position changes. The definition of the velocities of deformation of the system introduced in the classical developments of mechanics, the principle of the virtual work and the laws of thermodynamics, allows a large range of applications such as crowd motions, debris flow motions, and shape memory alloys motions. The set of the applications is even larger: social sciences and mechanics are unified to predict the motion of crowds with application to transport management and to evacuation of theaters management.

  6. Gravitational waves from cosmic bubble collisions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-Hoon [Ewha Womans University, Basic Science Research Institute, Seoul (Korea, Republic of); Ewha Womans University, Institute for the Early Universe, Seoul (Korea, Republic of); Lee, Bum-Hoon [Sogang University, Center for Quantum Spacetime, Seoul (Korea, Republic of); Sogang University, Department of Physics, Seoul (Korea, Republic of); Lee, Wonwoo [Sogang University, Center for Quantum Spacetime, Seoul (Korea, Republic of); Yang, Jongmann [Ewha Womans University, Basic Science Research Institute, Seoul (Korea, Republic of); Ewha Womans University, Institute for the Early Universe, Seoul (Korea, Republic of); Ewha Womans University, Department of Physics, Seoul (Korea, Republic of); Yeom, Dong-han [Sogang University, Center for Quantum Spacetime, Seoul (Korea, Republic of); Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan); National Taiwan University, Leung Center for Cosmology and Particle Astrophysics, Taipei (China)

    2015-03-01

    Cosmic bubbles are nucleated through the quantum tunneling process. After nucleation they would expand and undergo collisions with each other. In this paper, we focus in particular on collisions of two equal-sized bubbles and compute gravitational waves emitted from the collisions. First, we study the mechanism of the collisions by means of a real scalar field and its quartic potential. Then, using this model, we compute gravitational waves from the collisions in a straightforward manner. In the quadrupole approximation, time-domain gravitational waveforms are directly obtained by integrating the energy-momentum tensors over the volume of the wave sources, where the energy-momentum tensors are expressed in terms of the scalar field, the local geometry and the potential. We present gravitational waveforms emitted during (i) the initial-to-intermediate stage of strong collisions and (ii) the final stage of weak collisions: the former is obtained numerically, in full General Relativity and the latter analytically, in the flat spacetime approximation. We gain qualitative insights into the time-domain gravitational waveforms from bubble collisions: during (i), the waveforms show the non-linearity of the collisions, characterized by a modulating frequency and cusp-like bumps, whereas during (ii), the waveforms exhibit the linearity of the collisions, featured by smooth monochromatic oscillations. (orig.)

  7. Do Speed Cameras Reduce Collisions?

    OpenAIRE

    Skubic, Jeffrey; Johnson, Steven B.; Salvino, Chris; Vanhoy, Steven; Hu, Chengcheng

    2013-01-01

    We investigated the effects of speed cameras along a 26 mile segment in metropolitan Phoenix, Arizona. Motor vehicle collisions were retrospectively identified according to three time periods – before cameras were placed, while cameras were in place and after cameras were removed. A 14 mile segment in the same area without cameras was used for control purposes. Five cofounding variables were eliminated. In this study, the placement or removal of interstate highway speed cameras did not indepe...

  8. The Automatic Galaxy Collision Software

    CERN Document Server

    Smith, Beverly J; Pfeiffer, Phillip; Perkins, Sam; Barkanic, Jason; Fritts, Steve; Southerland, Derek; Manchikalapudi, Dinikar; Baker, Matt; Luckey, John; Franklin, Coral; Moffett, Amanda; Struck, Curtis

    2009-01-01

    The key to understanding the physical processes that occur during galaxy interactions is dynamical modeling, and especially the detailed matching of numerical models to specific systems. To make modeling interacting galaxies more efficient, we have constructed the `Automatic Galaxy Collision' (AGC) code, which requires less human intervention in finding good matches to data. We present some preliminary results from this code for the well-studied system Arp 284 (NGC 7714/5), and address questions of uniqueness of solutions.

  9. QCD studies in ep collisions

    Energy Technology Data Exchange (ETDEWEB)

    Smith, W.H. [Univ. of Wisconsin, Madison, WI (United States). Physics Dept.

    1997-06-01

    These lectures describe QCD physics studies over the period 1992--1996 from data taken with collisions of 27 GeV electrons and positrons with 820 GeV protons at the HERA collider at DESY by the two general-purpose detectors H1 and ZEUS. The focus of these lectures is on structure functions and jet production in deep inelastic scattering, photoproduction, and diffraction. The topics covered start with a general introduction to HERA and ep scattering. Structure functions are discussed. This includes the parton model, scaling violation, and the extraction of F{sub 2}, which is used to determine the gluon momentum distribution. Both low and high Q{sup 2} regimes are discussed. The low Q{sup 2} transition from perturbative QCD to soft hadronic physics is examined. Jet production in deep inelastic scattering to measure {alpha}{sub s}, and in photoproduction to study resolved and direct photoproduction, is also presented. This is followed by a discussion of diffraction that begins with a general introduction to diffraction in hadronic collisions and its relation to ep collisions, and moves on to deep inelastic scattering, where the structure of diffractive exchange is studied, and in photoproduction, where dijet production provides insights into the structure of the Pomeron. 95 refs., 39 figs.

  10. Study of the reactions resulting in heavy fragment formation in the collisions {sup 40}Ar + Cu, Ag and Au at 8 to 115 MeV/u; Etude des reactions avec formation d`un fragment lourd dans les collisions {sup 40}Ar + Cu, Ag et Au de 8 a 115 MeV/u

    Energy Technology Data Exchange (ETDEWEB)

    Colin, Eric Yves [Universite Claude Bernard Lyon-1, 69 - Lyon (France)

    1998-11-06

    This work concerns the study of nuclear collisions showing a heavy fragment in {sup 40}Ar + Cu, Ag and Au from 8 A MeV to 115 A MeV. The reactions are classified by centrality or collision violence via the multiplicity of charged particles detected in a 4{pi} array. For the most peripheral reactions (low multiplicities) we always find a projectile-like fragment with velocity near to that of the beam and a heavy target-like fragment with very small velocity. For the more central collisions we find the well-known incomplete fusion reactions at 17 and 27 A MeV. Above 27 A MeV two groups of very dissipative reactions are observed, both with high charged particle multiplicities. The first reaction group forms several fragments with Z {<=} 10 and average longitudinal velocity near to that of c.m. These are very rare, and are found only for the highest 1% of multiplicities. They produce a heavy fragment and a forward spray ({theta}{<=}60 angle) of particles with charge going from 1 to {approx_equal}13. The momentum carried out by the spray is randomly spread over all the particles. In spite of the increase of momentum carried by this spray with increasing beam energy, a heavy emission source is formed with 1 - 2 GeV of excitation energy. After a phase of expansion, especially signaled by Z = 1 particles, this source then evaporates many particles. Finally we observed the remaining heavy residual nucleus. (author) 117 refs., 85 figs., 12 tabs.

  11. Study of the heavy ions (Au+Au at 150 AMeV) collisions with the FOPI detector. Comparison with the Landau-Vlasov model; Etude des collisions d`ions lourds AU+AU a 150 A.MeV avec le detecteur FOPI. Comparaison avec le modele de Landau-Vlasov

    Energy Technology Data Exchange (ETDEWEB)

    Boussange, S.

    1995-09-15

    In this thesis, heavy ions (Au+Au) collisions experiments are made at 150 AMeV.In the first part, a general study of the nuclear matter equation is presented. Then the used Landau-Vlasov theoretical model is describe. The third part presents the FOPI experience and the details of how to obtain this theoretical predictions (filter, cuts, corrections, possible centrality selections).At the end, experimental results and comparisons with the Landau-Vlasov model are presented. (TEC). 105 refs., 96 figs., 14 tabs.

  12. Planetesimal collisions as a chondrule forming event

    CERN Document Server

    Wakita, Shigeru; Oshino, Shoichi; Hasegawa, Yasuhiro

    2016-01-01

    Chondritic meteorites contain unique spherical materials named chondrules: sub-mm sized silicate grains once melted in a high temperature condition in the solar nebula. We numerically explore one of chondrule forming processes, planetesimal collisions. Previous studies found that impact jetting via protoplanet-planetesimal collisions make chondrules with an amount of 1 % of impactors' mass, when impact velocity exceeds 2.5 km s$^{-1}$. Based on the mineralogical data of chondrules, undifferentiated planetesimals would be more suitable for chondrule-forming collisions than potentially differentiated protoplanets. We examine planetesimal-planetesimal collisions using a shock physics code and find two things: one is that planetesimal-planetesimal collisions produce the nearly same amount of chondrules as protoplanet-planetesimal collisions ($\\sim$ 1 %). The other is that the amount of produced chondrules becomes larger as the impact velocity increases when two planetesimals collide with each other. We also find ...

  13. A model for collisions in granular gases

    OpenAIRE

    Brilliantov, Nikolai V.; Spahn, Frank; Hertzsch, Jan-Martin; Poeschel, Thorsten

    2002-01-01

    We propose a model for collisions between particles of a granular material and calculate the restitution coefficients for the normal and tangential motion as functions of the impact velocity from considerations of dissipative viscoelastic collisions. Existing models of impact with dissipation as well as the classical Hertz impact theory are included in the present model as special cases. We find that the type of collision (smooth, reflecting or sticky) is determined by the impact velocity and...

  14. Strange particle correlations measured by the Star experiment in ultra-relativistic heavy ion collisions a RHIC; Etude des correlations de particules etranges mesurees par l'experience STAR dans les collisions d'ions lourds ultra-relativistes au RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Renault, G

    2004-09-01

    Non-identical correlation functions allow to study the space-time evolution of the source of particles formed in ultra-relativistic heavy ion collisions. The STAR experiment is dedicated to probe the formation of a new state of nuclear matter called Quark Gluon Plasma. The proton - lambda correlation function is supposed to be more sensitive to bigger source sizes than the proton - proton because of the absence of the final state Coulomb interaction. In this thesis, proton - lambda, anti-proton - anti-lambda, anti-proton - lambda and proton - anti-lambda correlation functions are studied in Au+Au collisions at {radical}S{sub NN} = 200 GeV using an analytical model. The proton - lambda and anti-proton - anti-lambda correlation functions exhibit the same behavior as in previous measurements. The anti-proton - lambda and proton - anti-lambda correlation functions, measured for the first time, show a very strong signal corresponding to the baryon - anti-baryon annihilation channel. Parameterizing the correlation functions has allowed to characterize final state interactions. (author)

  15. Ultrarelativistic nuclear collisions: Direction of spectator flow

    Science.gov (United States)

    Voloshin, Sergei A.; Niida, Takafumi

    2016-08-01

    In high-energy heavy-ion collisions, the directed flow of particles is conventionally measured with respect to that of the projectile spectators, which is defined as positive x direction, but it is not known if the spectators deflect in the outward or inward directions—outward or toward the center line of the collision. In this Communication we discuss how the measurements of the directed flow at midrapidity, especially in asymmetric collision such as Cu +Au , can be used to answer this question. We show that the existing data strongly favor the case that the spectators, in the ultrarelativistic collisions, on average deflect outward.

  16. Ionization in collisions between metastable hydrogen atoms

    Science.gov (United States)

    Bohr, Alex; Blickle, Andrew; Paolini, Stephen; Ohlinger, Luke; Forrey, Robert

    2012-06-01

    Associative and Penning ionization cross sections are calculated for collisions between metastable hydrogen 2s atoms at thermal energies. Cross sections for deuterium 2s collisions are also reported. The associative ionization cross sections behave as E-1 for collision energy E, in agreement with an existing experiment. The Penning ionization cross sections dominate for all energies and are found to follow the E-2/3 behavior that was predicted in previous work for the total ionization cross section. The magnitudes of our theoretical associative ionization cross sections for H(2s)+H(2s) collisions are between two and four times larger than the experimental data.

  17. Telerobotics with whole arm collision avoidance

    Energy Technology Data Exchange (ETDEWEB)

    Wilhelmsen, K.; Strenn, S.

    1993-09-01

    The complexity of teleorbotic operations in a cluttered environment is exacerbated by the need to present collision information to the operator in an understandable fashion. In addition to preventing movements which will cause collisions, a system providing some form of virtual force reflection (VFR) is desirable. With this goal in mind, Lawrence Livermore National Laboratory (LLNL) has installed a kinematically master/slave system and developed a whole arm collision avoidance system which interacts directly with the telerobotic controller. LLNL has also provided a structure to allow for automated upgrades of workcell models and provide collision avoidance even in a dynamically changing workcell.

  18. The effect of q-distributed electrons on the head-on collision of ion acoustic solitary waves

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Uday Narayan; Chatterjee, Prasanta [Department of Mathematics, Siksha Bhavana Visva Bharati University, Santiniketan 731235 (India); Roychoudhury, Rajkumar [Physics and Applied Mathematics, ISI, Kolkata 700009 (India)

    2012-01-15

    The head-on collision of ion acoustic solitary waves (IASWs) in two component plasma comprising nonextensive distributed electrons is investigated. Two opposite directional Kortewg-de-vries (KdV) equations are derived and the phase shift due to collision is obtained using the extended version of Poincare-Lighthill-Kuo method. Different ranges of nonextensive parameter q are considered and their effects on phase shifts are observed. It is found that the presence of nonextensive distributed electrons plays a significant role on the nature of collision of ion acoustic solitary waves.

  19. Quantifying the sQGP - Heavy Ion Collisions at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Seto, Richard [Univ. of California, Riverside, CA (United States)

    2014-12-01

    This is the closeout for DE-FG02-86ER40271 entitled Quantifying the sQGP - Heavy Ion Collisions at the RHIC. Two major things were accomplished. The first, is the physics planning, design, approval, construction, and commissioning of the MPC-EX. The MPC-EX is an electromagnetic calorimeter covering a rapidity of 3<|eta|<4, which was added to the PHENIX detector. Its primary aim is to measure low-x gluons, in order to understand the suppression seen in a variety of signatures, such as the J/Psi. A candidate to explain this phenomena is the Color Glass Condensate (CGC) A second task was to look at collisions of asymmetric species, in particularly Cu+Au. The signature was the suppression of J/Psi mesons at forward and backward rapidity, where a stronger suppression was seen in the copper going direction. While the blue of the suppression is due to hot nuclear matter effects (e.g. screening) the increase in suppression on the Au side was consistent with cold nuclear matter effects seen in d+Au collisions. A major candidate for the explanation of this phenomena is the aforementioned CGC. Finally the work on sPHENIX, particularly an extension to the forward region, called fsPHENIX is described.

  20. Les incommensurables

    CERN Document Server

    Houdart, Sophie

    2015-01-01

    Le Large Hadron Collider, ou grand collisionneur de hadrons, est l'accélérateur de particules le plus grand et le plus puissant du monde. Prenant la forme d'un anneau de 26,659 kilomètres de circonférence, lové 100 mètres sous terre et officiellement domicilié à Meyrin, à la frontière de la France et de la Suisse, il est constitué d'aimants supraconducteurs et de structures accélératrices qui augmentent l'énergie des particules qui y circulent. Chaque jour, à l'intérieur de l'accélérateur, deux faisceaux de particules qui circulent en sens contraire à des énergies très élevées avant de rentrer en collision l'un avec l'autre. Les particules, lancées à 99,9999991 % de la vitesse de la lumière, effectuent 11245 fois le tour de l'accélérateur par seconde et entrent en collision quelque 600 millions de fois par seconde. Les Incommensurables est une minutieuse enquête de terrain sur cette "cathédrale" enfouie qui offre la possibilité de se connecter à l'immensité et aux mystères de...

  1. Broadening of Plasmonic Resonance Due to Electron Collisions with Nanoparticle Boundary: а Quantum Mechanical Consideration

    DEFF Research Database (Denmark)

    Uskov, Alexander; Protsenko, Igor E.; Mortensen, N. Asger

    2014-01-01

    We present a quantum mechanical approach to calculate broadening of plasmonic resonances in metallic nanostructures due to collisions of electrons with the surface of the structure. The approach is applicable if the characteristic size of the structure is much larger than the de Broglie electron ...

  2. Positron collisions with alkali-metal atoms

    Science.gov (United States)

    Gien, T. T.

    1990-01-01

    The total cross sections for positron and electron collisions with potassium, sodium, lithium and rubidium are calculated, employing the modified Glauber approximation. The Modified Glauber cross sections for positron collision with potassium and sodium at low intermediate energies are found to agree reasonably well with existing experimental data.

  3. Z to Muon Muon Collision Event Animation

    CERN Multimedia

    ATLAS experiment

    2010-01-01

    This animation was created of an actual ATLAS collision event in 2010. This animation shows from the particle view the race through the LHC, ending in the detector where the particle collision occurs. Candidate for an event with a Z boson decaying to two muons.

  4. Theory and Validation for the Collision Module

    DEFF Research Database (Denmark)

    Simonsen, Bo Cerup

    1999-01-01

    This report describes basic modelling principles, the theoretical background and validation examples for the Collision Module for the computer program DAMAGE.......This report describes basic modelling principles, the theoretical background and validation examples for the Collision Module for the computer program DAMAGE....

  5. Lambda Polarization in Lead-Lead Collisions

    NARCIS (Netherlands)

    Schillings, Eelco

    2003-01-01

    In this thesis the production and polarization of Lambda particles produced in Pb-Pb collisions at a beam energy of 158 GeV/c per nucleon are studied. In these collisions nuclear matter is compressed and heated and under these conditions it is possible that a quark-gluon plasma (QGP) is created. In

  6. Freestart collision for full SHA-1

    NARCIS (Netherlands)

    Stevens, M.M.J.; Karpman, P.; Peyrin, T.

    2015-01-01

    We present in this article a freestart collision example for SHA-1, i.e., a collision for its internal compression function. This is the first practical break of the full SHA-1, reaching all 80 out of 80 steps, while only 10 days of computation on a 64 GPU cluster were necessary to perform the attac

  7. Mechanical Energy Changes in Perfectly Inelastic Collisions

    Science.gov (United States)

    Mungan, Carl E.

    2013-01-01

    Suppose a block of mass "m"[subscript 1] traveling at speed "v"[subscript 1] makes a one-dimensional perfectly inelastic collision with another block of mass "m"[subscript 2]. What else does one need to know to calculate the fraction of the mechanical energy that is dissipated in the collision? (Contains 1 figure.)

  8. Long-Range Collisions in Magnetized Plasmas

    Science.gov (United States)

    Dubin, D.

    2015-12-01

    Astrophysical (and earthbound) plasmas in strong magnetic fields exhibit collisional effects that are not described by classical collision theory nor by the standard collision operators, such as the Landau or Balescu-Lenard operators. These theories implicitly neglect "long-range" collisions, i.e. collisions with impact parameters large compared to the cyclotron radius. This presentation will review several important physical effects such collisions have on various phenomena, including cross-magnetic field diffusion, heat conduction, and collisional slowing parallel to the magnetic field. Long-range collisions are analyzed as guiding-centers moving in one-dimension along the magnetic field, with parallel energy and momentum transferred to particles on separate field lines through the screened Coulomb interaction. This causes cross-field heat transport that is independent of magnetic field strength B (as opposed to the classical 1/B2 scaling), and enhances the rate of collisional slowing parallel to B. The Coulomb interaction between guiding centers on different field lines also produces random ExB drifts that enhance cross-magnetic field diffusion compared to the classical theory. The theory of long-range guiding center collisions must also include the novel effect of "collisional caging": plasma noise causes two colliding guiding centers to diffuse in relative parallel velocity, reversing their motion along B and colliding several times before becoming uncorrelated. This further enhances cross-field diffusion from long-range collisions by a factor of three, and enhances parallel slowing by a factor of approximately 1.5.

  9. Propagation and collision of soliton rings in quantum semiconductor plasmas

    Energy Technology Data Exchange (ETDEWEB)

    El-Shamy, E.F., E-mail: emadel_shamy@hotmail.com [Department of Physics, Faculty of Science, Damietta University, New Damietta, 34517 (Egypt); Department of Physics, College of Science, King Khalid University, P.O. 9004, Abha (Saudi Arabia); Gohman, F.S., E-mail: fulh2012kku@hotmail.com [Department of Physics, College of Science for Girls in Abha, King Khalid University, Abha, P.O. 960 (Saudi Arabia)

    2014-07-18

    The intrinsic localization of electrostatic wave energies in quantum semiconductor plasmas can be described by solitary pulses. The collision properties of these pulses are investigated. In the present study, the fundamental model includes the quantum term, degenerate pressure of the plasma species, and the electron/hole exchange–correlation effects. In cylindrical geometry, using the extended Poincaré–Lighthill–Kuo (PLK) method, the Korteweg–de Vries (KdV) equations and the analytical phase shifts after the collision of two soliton rings are derived. Typical values for GaSb and GaN semiconductors are used to estimate the basic features of soliton rings. It is found that the pulses of GaSb semiconductor carry more energies than the pulses of GaN semiconductor. In addition, the degenerate pressure terms of electrons and holes have strong impact on the phase shift. The present theory may be useful to analyze the collision of localized coherent electrostatic waves in quantum semiconductor plasmas. - Highlights: • The propagation and the collision of pulses in quantum semiconductor plasmas are studied. • Numerical calculations reveal that pulses may exist only in dark soliton rings for electron–hole quantum plasmas. • Typical values for GaSb and GaN semiconductors are used to estimate the basic features of soliton rings. • It is found that the pulses of GaSb semiconductor carry more energies than the pulses of GaN semiconductor. • The degenerate pressure terms of electrons and holes have strong impact on the phase shift.

  10. The Effects of Aseismic Ridge Collision on Upper Plate Deformation: Cocos Ridge Collision and Deformation of the Western Caribbean

    Science.gov (United States)

    La Femina, P. C.; Govers, R. M. A.; Ruiz, G.; Geirsson, H.; Camacho, E.; Mora-Paez, H.

    2015-12-01

    The collision of the Panamanian isthmus with northwestern South America is thought to have initiated as early as Oligocene - Miocene time (23-25 Ma) based on geologic and geophysical data and paleogeographic reconstructions. This collision was driven by eastward-directed subduction beneath northwestern South America. Cocos - Caribbean convergence along the Middle America Trench, and Nazca - Caribbean oblique convergence along the South Panama Deformed Belt have resulted in complex deformation of the southwestern Caribbean since Miocene - Pliocene time. Subduction and collision of the aseismic Cocos Ridge is thought to have initiated volcanism and uplift of the Cordillera de Talamanca, Costa Rica; 2) Quaternary migration of the volcanic arc toward the back-arc in Costa Rica; 3) Quaternary to present deformation within the Central Costa Rica Deformed Belt; 4) Quaternary to present shortening across the fore-arc Fila Costeña fold and thrust belt and back-arc North Panama Deformed Belt (NPDB); 5) Quaternary to present outer fore-arc uplift of Nicoya Peninsula above the seamount domain, and the Osa and Burica peninsulas above the ridge; and 6) Pleistocene to present northwestward motion of the Central American Fore Arc (CAFA) and northeastward motion of the Panama Region. We investigate the geodynamic effects of Cocos Ridge collision on motion of the Panama Region with a new geodynamic model. The model is compared to a new 1993-2015 GPS-derived three-dimensional velocity field for the western Caribbean and northwestern South America. Specifically, we test the hypotheses that the Cocos Ridge is the main driver for upper plate deformation in the western Caribbean. Our models indicate that Cocos Ridge collision drives northwest-directed motion of the CAFA and the northeast-directed motion of the Panama Region. The Panama Region is driven into the Caribbean across the NPDB and into northwestern South America, which is also converging with the Panama Region, pushing it

  11. Fixed Target Collisions at STAR

    Science.gov (United States)

    Meehan, Kathryn C.

    2016-12-01

    The RHIC Beam Energy Scan (BES) program was proposed to look for the turn-off of signatures of the quark gluon plasma (QGP), search for a possible QCD critical point, and study the nature of the phase transition between hadronic and partonic matter. Previous results have been used to claim that the onset of deconfinement occurs at a center-of-mass energy of 7 GeV. Data from lower energies are needed to test if this onset occurs. The goal of the STAR Fixed-Target Program is to extend the collision energy range in BES II to energies that are likely below the onset of deconfinement. Currently, STAR has inserted a gold target into the beam pipe and conducted test runs at center-of-mass energies of 3.9 and 4.5 GeV. Tests have been done with both Au and Al beams. First physics results from a Coulomb potential analysis of Au + Au fixed-target collisions are presented and are found to be consistent with results from previous experiments. Furthermore, the Coulomb potential, which is sensitive to the Z of the projectile and degree of baryonic stopping, will be compared to published results from the AGS.

  12. Holographic collisions in confining theories

    CERN Document Server

    Cardoso, Vitor; Mateos, David; Pani, Paolo; Rocha, Jorge V

    2013-01-01

    We study the gravitational dual of a high-energy collision in a confining gauge theory. We consider a linearized approach in which two point particles traveling in an AdS-soliton background suddenly collide to form an object at rest (presumably a black hole for large enough center-of-mass energies). The resulting radiation exhibits the features expected in a theory with a mass gap: late-time power law tails of the form t^(-3/2), the failure of Huygens' principle and distortion of the wave pattern as it propagates. The energy spectrum is exponentially suppressed for frequencies smaller than the gauge theory mass gap. Consequently, we observe no memory effect in the gravitational waveforms. At larger frequencies the spectrum has an upward-stairway structure, which corresponds to the excitation of the tower of massive states in the confining gauge theory. We discuss the importance of phenomenological cutoffs to regularize the divergent spectrum, and the aspects of the full non-linear collision that are expected ...

  13. Simulating Collisions for Hydrokinetic Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Richmond, Marshall C.; Romero Gomez, Pedro DJ; Rakowski, Cynthia L.

    2013-10-01

    Evaluations of blade-strike on an axial-flow Marine Hydrokinetic turbine were conducted using a conventional methodology as well as an alternative modeling approach proposed in the present document. The proposed methodology integrates the following components into a Computa- tional Fluid Dynamics (CFD) model: (i) advanced eddy-resolving flow simulations, (ii) ambient turbulence based on field data, (iii) moving turbine blades in highly transient flows, and (iv) Lagrangian particles to mimic the potential fish pathways. The sensitivity of blade-strike prob- ability to the following conditions was also evaluated: (i) to the turbulent environment, (ii) to fish size and (iii) to mean stream flow velocity. The proposed methodology provided fraction of collisions and offered the capability of analyzing the causal relationships between the flow envi- ronment and resulting strikes on rotating blades. Overall, the conventional methodology largely overestimates the probability of strike, and lacks the ability to produce potential fish and aquatic biota trajectories as they interact with the rotating turbine. By using a set of experimental corre- lations of exposure-response of living fish colliding on moving blades, the occurrence, frequency and intensity of the particle collisions was next used to calculate the survival rate of fish crossing the MHK turbine. This step indicated survival rates always greater than 98%. Although the proposed CFD framework is computationally more expensive, it provides the advantage of evaluating multiple mechanisms of stress and injury of hydrokinetic turbine devices on fish.

  14. Replacement collision sequence studies in iron

    CERN Document Server

    Hou, M; Becquart, C S

    2002-01-01

    The properties of replacement collision sequences (RCS) in iron and their contribution to radiation damage are studied as they are generated in atomic collision cascades with the binary collision approximation Marlowe. Length distributions of RCS in collision cascades generated by primaries with a couple of ten keV kinetic energies are predicted short. Whatever the interatomic potential employed, at least 90% of the generated RCS have a length of no more than three successive collisions, whatever the directions. This property was found for all the known phases of iron at standard pressure (bcc and fcc). The RCS length distributions are not significantly influenced by the temperature nor by the accurate form of the model describing the energy loss in RCS. Close to 50% of the stable Frenkel pairs (FP) created result from RCS that are shorter than the vacancy-interstitial recombination distance estimated on the basis of molecular dynamics calculations. The other half results from longer RCS (about five successiv...

  15. The epidemiology of bicyclist's collision accidents

    DEFF Research Database (Denmark)

    Larsen, L. B.

    1994-01-01

    of bicyclists and risk situations. The findings should make a basis for preventive programmes in order to decrease the number and severity of bicyclists collision accidents. Data from the emergency room in a 2 year period was combined with data from questionnaires. The study group consisted of 1021 bicyclists...... group of accidents were the collisions with the 'soft' road users (bicyclists, mopeds, and pedestrians) and another group were the collisions with the 'hard' road users (motor vehicles, motorcycles). Preventive measures have to be directed at both these groups of accidents. To decrease the number...... of collision accidents with motor vehicles it is necessary to separate the bicyclists from the 'hard road traffic' especially at crossings. Preventive measures must also be directed at the bicyclists. Information must be given to warn the bicyclists against the risks, not only for collisions with motor...

  16. Etude des caractéristiques d'une cavité laser en X de forte puissance

    Science.gov (United States)

    Grevey, D. F.; Badawi, K. F.; Boquillon, J. P.; Taisne, B.; Jacrot, G.

    1992-05-01

    This study is devoted to a new ring cavity, an X geometry. It allows to obtain about 280W in opposite to the 450W of the initial linear cavity. The difference in the values comes from the formation of an instable cavity due to the length of the cavity which is longer. Expecting that, the quality factor of the beam is lower for the X configuration and consequently power density are higher and cutting speed are 50% greater than for the linear system. Concerning welding, due to the higher level of power density, the key hole is more easily formed than with the linear configuration and the penetration increases. So, even if the optical way is difficult to adjust, cutting and welding performances are interesting. Cette étude est relative à une nouvelle cavité en anneau, avec une géométrie en “X”. Elle permet d'obtenir un faisceau de meilleure qualité que lorsque la cavité est sous forme linéaire, et par suite les puissances spécifiques peuvent être multipliées par un facteur 10 au moins. Ce gain, qui se fait au détriment de la puissance moyenne maximale délivrable (75% de celle atteinte avec la configuration linéaire) reste intéressant car les vitesses de découpe et de soudage en faibles épaisseurs sont augmentées d'environ 50%.

  17. Basins in ARC-continental collisions

    Science.gov (United States)

    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

  18. Photon scattering in muon collisions.

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, M.

    1997-12-18

    The authors estimate the benefit of muon colliders for photon physics. They calculate the rate at which photons are emitted from muon beams in different production mechanisms. Bremsstrahlung is reduced, beamstrahlung disappears, and laser backscattering suffers from a bad conversion of the incoming to the outgoing photon beam in addition to requiring very short wavelengths. As a consequence, the cross sections for jet photoproduction in {mu}p and {mu}{sup +} {mu}{sup {minus}} collisions are reduced by factors of 2.2 and 5 compared to ep and e{sup +} e{sup {minus}} machines. However, the cross sections remain sizable and measurable giving access to the photon and proton parton densities down to x values of 10{sup {minus}3} to 10{sup {minus}4}.

  19. Relativistic heavy-ion collisions

    CERN Document Server

    Bhalerao, Rajeev S

    2014-01-01

    The field of relativistic heavy-ion collisions is introduced to the high-energy physics students with no prior knowledge in this area. The emphasis is on the two most important observables, namely the azimuthal collective flow and jet quenching, and on the role fluid dynamics plays in the interpretation of the data. Other important observables described briefly are constituent quark number scaling, ratios of particle abundances, strangeness enhancement, and sequential melting of heavy quarkonia. Comparison is made of some of the basic heavy-ion results obtained at LHC with those obtained at RHIC. Initial findings at LHC which seem to be in apparent conflict with the accumulated RHIC data are highlighted.

  20. Study on Collision Characters for SPAR Platform

    Institute of Scientific and Technical Information of China (English)

    HU Zhi-qiang; CUI Wei-cheng

    2008-01-01

    This paper presents the research on the external mechanism of collision characters for a SPAR platform. The collision characters of SPAR platform have not attracted so much attention as that of ships in the past, because short of this kind of collision accidents reported. But with the increasing number of SPAR platforms in the world, the possibility of such kind of accident also increases. Therefore, it is necessary to master the character of SPAR collision. Model test technique is employed to study the external mechanism. The collision scenario is a ship colliding with a SPAR platform moored in the site with 1500 meters water depth. The striking ship hits the SPAR platform on the hard tank near water surface in its longitudinal direction. The specifics of the SPAR's motions and the tension forces of the mooring lines are collected to summarize the hydrodynamic characters in the collision scenario. It is found that the maximal displacements and the maximal pitch angles of the SPAR platform, and the maximal tension forces of mooring lines are all linearly proportional to the initial velocity of the striking ship basically. Mooring lines play elastic roles in the collision course.

  1. Jet Production in p-Pb Collisions

    CERN Document Server

    Connors, Megan

    2014-01-01

    One of the major results from the study of high energy heavy ion collisions is the observation of jet quenching. The suppression of the number of jets observed in heavy ion collisions relative to pp collisions at the same energy scaled by the number of binary collisions, is attributed to partonic energy loss in the quark gluon plasma (QGP). However, cold nuclear matter effects due to the presence of a nucleus in the initial state could also influence this measurement. To disentangle these effects p-Pb collisions are studied, where QGP formation is not expected to occur and only cold nuclear matter effects are present. In addition to being an important baseline for understanding jet quenching, jets in p-Pb collisions may also be used to provide constraints on the nuclear parton distribution functions. Fully reconstructed jets measured using the ALICE tracking system and electro-magnetic calorimeter in p-Pb collisions at $\\sqrt{s_{NN}}=5.02$ TeV are reported. In addition to the spectra, studies of the jet fragm...

  2. CHARACTERIZATION OF WILD PIG VEHICLE COLLISIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, J; Paul E. Johns, P

    2007-05-23

    Wild pig (Sus scrofa) collisions with vehicles are known to occur in the United States, but only minimal information describing these accidents has been reported. In an effort to better characterize these accidents, data were collected from 179 wild pig-vehicle collisions from a location in west central South Carolina. Data included accident parameters pertaining to the animals involved, time, location, and human impacts. The age structure of the animals involved was significantly older than that found in the population. Most collisions involved single animals; however, up to seven animals were involved in individual accidents. As the number of animals per collision increased, the age and body mass of the individuals involved decreased. The percentage of males was significantly higher in the single-animal accidents. Annual attrition due to vehicle collisions averaged 0.8 percent of the population. Wild pig-vehicle collisions occurred year-round and throughout the 24-hour daily time period. Most accidents were at night. The presence of lateral barriers was significantly more frequent at the collision locations. Human injuries were infrequent but potentially serious. The mean vehicle damage estimate was $1,173.

  3. Electron emission following collisions between multi-charged ions and D{sub 2} molecules; Etude de l'emission electronique induite par impact d'ion multicharge sur la molecule D{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, G

    2004-05-15

    Dissociative ionisation mechanisms induced in collisions involving a highly charged ion (S{sup 15+}, 13.6 MeV/u) and a molecular deuterium target, have been studied through momentum vector correlations of both the D{sup +} fragments and the electrons produced. An experimental apparatus has been developed in order to detect in coincidence all the charged particles produced during the collision. The measurement of their momentum vectors, which allows one to determine both their kinetic energy and direction of emission with respect to the projectile one, combines Time of Flight, Position Sensitive Detection, and multi-coincidence techniques. The correlation of the fragment and electron kinetic energies enables not only to determine branching ratios between the dissociative ionisation pathways, but also to separate unambiguously kinetic energy distributions of fragments associated to each process. Finally, the angular distributions of ejected electrons, as a function of the orientation of the molecular axis with respect to the projectile direction, are deduced from the spatial correlation. Measurements are compared to theoretical angular distributions obtained using the CDW-EIS (Continuum Distorted Wave-Eikonal Initial State) method. (author)

  4. Mid-air collisions enhance saltation

    CERN Document Server

    Carneiro, M V; Pähtz, T; Herrmann, H J

    2013-01-01

    Here we address the old question in Aeolian particle transport about the importance of mid-air collisions. We find that surprisingly these collisions do enhance the overall flux substantially. The effect depends strongly on restitution coefficient and wind speed. We can explain this observation as a consequence of a "soft bed" of grains which floats above the surface and reflects the highest flying particles. We make the unexpected observation that the flux is maximized for an intermediate restitution coefficient of about 0.65, which is comparable to the values experimentally measured for collisions between sand grains.

  5. Cold heteronuclear atom-ion collisions

    CERN Document Server

    Zipkes, Christoph; Ratschbacher, Lothar; Sias, Carlo; Köhl, Michael

    2010-01-01

    We study cold heteronuclear atom ion collisions by immersing a trapped single ion into an ultracold atomic cloud. Using ultracold atoms as reaction targets, our measurement is sensitive to elastic collisions with extremely small energy transfer. The observed energy-dependent elastic atom-ion scattering rate deviates significantly from the prediction of Langevin but is in full agreement with the quantum mechanical cross section. Additionally, we characterize inelastic collisions leading to chemical reactions at the single particle level and measure the energy-dependent reaction rate constants. The reaction products are identified by in-trap mass spectrometry, revealing the branching ratio between radiative and non-radiative charge exchange processes.

  6. Vorticity in Heavy-Ion Collisions

    CERN Document Server

    Deng, Wei-Tian

    2016-01-01

    We study the event-by-event generation of flow vorticity in RHIC Au + Au collisions and LHC 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.

  7. Vorticity in heavy-ion collisions

    Science.gov (United States)

    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.

  8. Wireless vehicular networks for car collision avoidance

    CERN Document Server

    2013-01-01

    Wireless Vehicular Networks for Car Collision Avoidance focuses on the development of the ITS (Intelligent Transportation Systems) in order to minimize vehicular accidents. The book presents and analyses a range of concrete accident scenarios while examining the causes of vehicular collision and proposing countermeasures based on wireless vehicular networks. The book also describes the vehicular network standards and quality of service mechanisms focusing on improving critical dissemination of safety information. With recommendations on techniques and protocols to consider when improving road safety policies in order to minimize crashes and collision risks.

  9. Étude de la production inclusive de $J/\\psi$ dans les collisions Pb-Pb à $\\sqrt{s_{_{\\rm NN}}}=2,76$ TeV avec le spectromètre à muons de l'expérience ALICE au LHC

    CERN Document Server

    Lardeux, Antoine

    The quantum chromodynamics theory predicts the existence of a deconfined state of matter called Quark Gluon Plasma (QGP). Experimentally, the formation of a QGP is expected under the extreme conditions of temperature and density reached in ultra-relativistic heavy-ion collisions. Many observables were proposed to observe and characterize indirectly such a state of matter. In particular, the phenomena of suppression and (re)combination of the $J/\\psi$ meson in the QGP are extensively studied. This thesis presents the analysis of the inclusive production of $J/\\psi$ in Pb-Pb collisions, at a center of mass energy $\\sqrt{s_{_{\\rm NN}}}=2.76$ TeV, detected with the ALICE muon spectrometer at the LHC. From the high statistics of events collected during 2011 data taking, the $J/\\psi$ nuclear modification factor was measured as a function of transverse momentum, rapidity and collision centrality. The $J/\\psi$ mean transverse momentum was also measured as a function of centrality. The predictions of theoretical...

  10. Collision geometry and particle production in high energy heavy ion collision experiments

    Institute of Scientific and Technical Information of China (English)

    WANG Ya-Ping; ZHOU Dai-Mei; HUANG Rui-Dian; CAI Xu

    2008-01-01

    An overview of research status of soft physics in high energy heavy-ion collision experiments and recent experimental results are presented.This paper includes four parts:1)Theoretical predictions of quarkgluon plasma and introduction for high energy heavy ion collision experiments.2)Experimental status on collision geometry.3)Experimental status on particle production.4)Conclusion and outlook for research status of soft physics in LHC/ALICE.

  11. Head on collision of multi-solitons in an electron-positron-ion plasma having superthermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Kaushik, E-mail: kaushikbolpur@rediffmail.com [Beluti M. K. M. High School, P.O. Beluti, Birbhum, West Bengal 731301 (India); Chatterjee, Prasanta, E-mail: prasantachatterjee1@rediffmail.com; Roychoudhury, Rajkumar [Department of Mathematics, Siksha Bhavana Visva Bharati, Santiniketan 731235 (India)

    2014-10-15

    The head-on collision and overtaking collision of four solitons in a plasma comprising superthermal electrons, cold ions, and Boltzmann distributed positrons are investigated using the extended Poincare-Lighthill-Kuo (PLK) together with Hirota's method. PLK method yields two separate Korteweg-de Vries (KdV) equations where solitons obtained from any KdV equation move along a direction opposite to that of solitons obtained from the other KdV equation, While Hirota's method gives multi-soliton solution for each KdV equation all of which move along the same direction where the fastest moving soliton eventually overtakes the other ones. We have considered here two soliton solutions obtained from Hirota's method. Phase shifts acquired by each soliton due to both head-on collision and overtaking collision are calculated analytically.

  12. Looking for the Odderon in photon collisions

    CERN Document Server

    Pire, Bernard; Szymanowski, Lech; Wallon, Samuel

    2010-01-01

    We discuss the production of two pion pairs in photon collisions at high energies. We calculate the according matrix elements in k_T-factorization and discuss the possibility to reveal the existence of the perturbative Odderon by charge asymmetries.

  13. Particle Interferometry in Heavy-Ion Collisions

    CERN Document Server

    Heinz, Ulrich W

    1997-01-01

    By measuring hadronic single-particle spectra and two-particle correlations in heavy-ion collisions, the size and dynamical state of the collision fireball at freeze-out can be reconstructed. I discuss the relevant theoretical methods and their limitations. By applying the formalism to recent pion correlation data from Pb+Pb collisions at CERN we demonstrate that the collision zone has undergone strong transverse growth before freeze-out (by a factor 2-3 in each direction), and that it expands both longitudinally and transversally. From the thermal and flow energy density at freeze-out the energy density at the onset of transverse expansion can be estimated from conservation laws. It comfortably exceeds the critical value for the transition to color deconfined matter.

  14. Theory overview of Heavy Ion collisions

    CERN Document Server

    Lappi, T

    2016-01-01

    This presentation discusses some recently active topics in the theoretical interpretation of high energy heavy ion collisions at the LHC and at RHIC. We argue that the standard paradigm for understanding the spacetime evolution of the bulk of the matter produced in the collision is provided by viscous relativistic hydrodynamics, which can be used to systematically extract properties of the QCD medium from experimental results. The initial conditions of this hydrodynamical evolution are increasingly well understood in terms of gluon saturation, and can be quantified using Classical Yang-Mills fields and QCD effective kinetic theory. Hard and electromagnetic probes of the plasma provide additional constraints. A particularly fascinating subject are high multiplicity proton-proton and proton-nucleus collisions, where some of the characteristics previously attributed to only nucleus-nucleus collisions have been observed.

  15. System size in relativistic heavy ion collisions

    Institute of Scientific and Technical Information of China (English)

    WANG Yang-Yang; ZHAO Lin-Jie; YUAN Zhong-Sheng; ZHANG Dan-Dan; FANG Wei; XU Ming-Mei

    2011-01-01

    System size is more than a geometrical quantity in relativistic heavy ion collisions; it is closely related to evolution process,i.e.a different system size corresponds to a different evolution process,and whether QGP is produced depends on the system size.We propose that the system size should be under the same level when comparing the measurements from different colliding nuclei.The equivalence of the peripheral collisions of Au-Au and the central collisions of smaller nuclei is studied using the Monte Carlo method.Comparing the transverse overlapping area of the colliding nuclei,the number of participant nucleons and the number of nucleon-nucleon binary collisions in various colliding nuclei,we give an estimate of the correspondence in system size.This is helpful in the experimental comparison of the measurements from different colliding nuclei.

  16. Active Collision Avoidance for Planetary Landers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advancements in radar technology have resulted in commercial, automotive collision avoidance radars. These radar systems typically use 37GHz or 77GHz interferometry...

  17. VT Vehicle-Animal Collisions - 2006

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This data (ROADKILL06) describes the locations of vehicle-animal collisions. This shapefile is a collection of collsion information collected by...

  18. Some soft aspects of relativistic ion collisions

    CERN Document Server

    Boimska, Bozena

    2009-01-01

    Concepts of wounded nucleon and quark participants have been used for years to parametrize and/or to explain many features of high energy nuclear collisions. Some results illustrating successes and failures of these two approaches are presented, including the latest developments. In particular, results on identified particle production from nuclear collisions measured by the NA49 experiment at the CERN-SPS are shown. The study has been done for both the nucleon and the constituent quark frameworks using the nuclear overlap model. In addition, some preliminary observations concerning the behavior of pT spectra at forward rapidities, expressed in terms of the nuclear modification factor, for hadron-nucleus collisions at the SPS energy are also presented. These results are in relevance to RHIC results for deuteron-gold collisions often interpreted as a manifestation of saturation and/or color glass condensate.

  19. Novel energy sharing collisions of multicomponent solitons

    Indian Academy of Sciences (India)

    T Kanna; K Sakkaravarthi; M Vijayajayanthi

    2015-11-01

    In this paper, we discuss the fascinating energy sharing collisions of multicomponent solitons in certain incoherently coupled and coherently coupled nonlinear Schrödinger-type equations arising in the context of nonlinear optics.

  20. Collision Avoidance of Trains Using Arm7

    Directory of Open Access Journals (Sweden)

    Dr. K. R. R. Mohan Rao

    2015-11-01

    Full Text Available Railways are the popular mode of Transport in almost all major cities of the World. Railways are the most widely used and comfortable modes of transportation system. The major cause for railway accidents is collision of trains on the same track. The main aim of this anti collision system is to identify collision points and to report these error cases to main control room nearer to the station as well as grid control station. Majority of accidents occurred due to improper communication among the network between drivers and control room, due to wrong signaling, worst atmospheric condition, immediate change of route. The train driver doesn’t get proper information in time leading to hazardous situations. So this system by using zigbee protocol provides communication in between trains, which provide information or track id of one train to another train to avoid collision.

  1. LHC: Collisions on course for 2007

    CERN Multimedia

    2006-01-01

    In the LHC tunnel and caverns, a particle accelerator and detectors are rapidly taking shape. At last week's Council meeting, delegates took stock of the year's progress towards first collisions in 2007.

  2. Recent results on relativistic heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Munhoz, Marcelo [Universidade de Sao Paulo (IF/USP), Sao Paulo, SP (Brazil). Inst. de Fisica

    2013-07-01

    Full text: The study of relativistic heavy ion collisions is a very important tool in order to understand the strong interaction described by QCD. The formation of the Quark-Gluon Plasma and the study of its properties is a very challenging quest. The Large Hadron Collider (LHC) from CERN (European Organization for Nuclear Research) generates ultra-relativistic Pb + Pb collisions at the TeV scale inaugurating a new era for such studies. Three experiments, ATLAS, CMS and ALICE are able to measure the products of such collisions. In special, the ALICE experiment was designed specifically for the study of heavy ion collisions. In this presentation, I'll discuss the latest results that shed light in the QGP understanding. (author)

  3. Simulating the universe(s) II: phenomenology of cosmic bubble collisions in full general relativity

    Energy Technology Data Exchange (ETDEWEB)

    Wainwright, Carroll L.; Aguirre, Anthony [SCIPP and Department of Physics, University of California, 1156 High St., Santa Cruz, CA, 95064 (United States); Johnson, Matthew C. [Department of Physics and Astronomy, York University, 4700 Keele St., Toronto, On, M3J 1P3 Canada (Canada); Peiris, Hiranya V., E-mail: cwainwri@ucsc.edu, E-mail: mjohnson@perimeterinstitute.ca, E-mail: aguirre@scipp.ucsc.edu, E-mail: h.peiris@ucl.ac.uk [Department of Physics and Astronomy, University College London, Gower St., London, WC1E 6BT U.K. (United Kingdom)

    2014-10-01

    Observing the relics of collisions between bubble universes would provide direct evidence for the existence of an eternally inflating Multiverse; the non-observation of such events can also provide important constraints on inflationary physics. Realizing these prospects requires quantitative predictions for observables from the properties of the possible scalar field Lagrangians underlying eternal inflation. Building on previous work, we establish this connection in detail. We perform a fully relativistic numerical study of the phenomenology of bubble collisions in models with a single scalar field, computing the comoving curvature perturbation produced in a wide variety of models. We also construct a set of analytic predictions, allowing us to identify the phenomenologically relevant properties of the scalar field Lagrangian. The agreement between the analytic predictions and numerics in the relevant regions is excellent, and allows us to generalize our results beyond the models we adopt for the numerical studies. Specifically, the signature is completely determined by the spatial profile of the colliding bubble just before the collision, and the de Sitter invariant distance between the bubble centers. The analytic and numerical results support a power-law fit with an index 1< κ ∼< 2. For collisions between identical bubbles, we establish a lower-bound on the observed amplitude of collisions that is set by the present energy density in curvature.

  4. Simulating the universe(s) II: phenomenology of cosmic bubble collisions in full general relativity

    Science.gov (United States)

    Wainwright, Carroll L.; Johnson, Matthew C.; Aguirre, Anthony; Peiris, Hiranya V.

    2014-10-01

    Observing the relics of collisions between bubble universes would provide direct evidence for the existence of an eternally inflating Multiverse; the non-observation of such events can also provide important constraints on inflationary physics. Realizing these prospects requires quantitative predictions for observables from the properties of the possible scalar field Lagrangians underlying eternal inflation. Building on previous work, we establish this connection in detail. We perform a fully relativistic numerical study of the phenomenology of bubble collisions in models with a single scalar field, computing the comoving curvature perturbation produced in a wide variety of models. We also construct a set of analytic predictions, allowing us to identify the phenomenologically relevant properties of the scalar field Lagrangian. The agreement between the analytic predictions and numerics in the relevant regions is excellent, and allows us to generalize our results beyond the models we adopt for the numerical studies. Specifically, the signature is completely determined by the spatial profile of the colliding bubble just before the collision, and the de Sitter invariant distance between the bubble centers. The analytic and numerical results support a power-law fit with an index 1< κ lesssim 2. For collisions between identical bubbles, we establish a lower-bound on the observed amplitude of collisions that is set by the present energy density in curvature.

  5. LightForce: An Update on Orbital Collision Avoidance Using Photon Pressure

    Science.gov (United States)

    Stupl, Jan; Mason, James; De Vries, Willem; Smith, Craig; Levit, Creon; Marshall, William; Salas, Alberto Guillen; Pertica, Alexander; Olivier, Scot; Ting, Wang

    2012-01-01

    We present an update on our research on collision avoidance using photon-pressure induced by ground-based lasers. In the past, we have shown the general feasibility of employing small orbit perturbations, induced by photon pressure from ground-based laser illumination, for collision avoidance in space. Possible applications would be protecting space assets from impacts with debris and stabilizing the orbital debris environment. Focusing on collision avoidance rather than de-orbit, the scheme avoids some of the security and liability implications of active debris removal, and requires less sophisticated hardware than laser ablation. In earlier research we concluded that one ground based system consisting of a 10 kW class laser, directed by a 1.5 m telescope with adaptive optics, could avoid a significant fraction of debris-debris collisions in low Earth orbit. This paper describes our recent efforts, which include refining our original analysis, employing higher fidelity simulations and performing experimental tracking tests. We investigate the efficacy of one or more laser ground stations for debris-debris collision avoidance and satellite protection using simulations to investigate multiple case studies. The approach includes modeling of laser beam propagation through the atmosphere, the debris environment (including actual trajectories and physical parameters), laser facility operations, and simulations of the resulting photon pressure. We also present the results of experimental laser debris tracking tests. These tests track potential targets of a first technical demonstration and quantify the achievable tracking performance.

  6. New method for selection and characterization of single-source events in Ni+Ni collisions at 32 A.MeV; Nouvelle methode de selection et caracterisation des evenements monosource dans les collisions Ni+Ni a 32 A.MeV

    Energy Technology Data Exchange (ETDEWEB)

    Maskay-Wallez, Anne-Marie [Inst. de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France)

    1999-07-13

    The study of heavy ion collisions, with the help of such efficient multi-detectors as INDRA, has shown the persistence of reactions leading to single-source events, up to bombarding energies higher than the Fermi one. These events could help characterizing an expected phase transition in nuclear matter. Whatever interesting they may be, the single-source events correspond to a small part of the total cross section, which makes them difficult to isolate and therefore to analyze. That is why different selection means have been tested - thanks to the 'Simon' event generator - on a simulated Ni + Ni at 32 A{center_dot}MeV sample, before any application to the INDRA experimental data. As the known methods based on global variables did not prove effective, a set of new 4-dimensional quantities has been built, whose main advantage lies in a better description of physical events. From a Discriminant Analysis performed on 625 of these new 'moments' proceeds a highly discriminant variable, called D{sub 625}. The experimental cross section associated with D{sub 625}-selected single-source events amounts to 170 mb at 32 A{center_dot}MeV. Such quasi-fusion events are shown to disappear at about 60 A{center_dot}MeV. As regards the deexcitation mode of the 32 A{center_dot}MeV Ni + Ni single-source events, an extensive experimental study and comparisons of the data with two reference models seem to confirm the hypothesis of a transition between fusion-evaporation and simultaneous multifragmentation mechanisms. (author)

  7. Fusion-Fission process and gamma spectroscopy of binary products in light heavy ion collisions (40 {<=} A{sub CN} {<=} 60); Processus de fusion-fission et spectroscopie gamma des produits binaires dans les collisions entre ions lourds legers (40 {<=} A{sub NC} {<=} 60)

    Energy Technology Data Exchange (ETDEWEB)

    Nouicer, Rachid [Institut de Recherche Subatomique, CNRS-IN2P3 - Universite Louis Pasteur, 67 - Strasbourg (France)

    1997-11-21

    During the work on which this Thesis is based, the significant role of the Fusion-Fission Asymmetric mechanism in light heavy ion collisions (A{sub NC} {<=} 60) has been emphasized. The Spin Dis-alignment in the oblate-oblate system has supplied evidence for the first time for the Butterfly mode in a resonant-like reaction. These two aspects, one macroscopic and the other more closely related to microscopic effects are certainly different from a conceptual point of view but are quite complementary for a global understanding of dinuclear systems. In the first part, inclusive and exclusive measurements of the {sup 35}Cl + {sup 12}C and {sup 35}Cl + {sup 24}Mg reaction have been performed at 8 MeV/nucleon in the Saclay experiment. These measurements have permitted us to verify the origin of products which have given rise of the asymmetric fusion-fission mechanism and which have demonstrated that the three-body process in this energy range is very weak. In the second part the {sup 28}Si + {sup 28}Si reaction has been performed at the resonance energy E{sub lab}> = 111.6 MeV at Strasbourg with the Eurogam phase II multi-detector array and VIVITRON accelerator. An angular momentum J{sup {pi}} 38{sup +} for inelastic and mutual channels of the {sup 28}Si + {sup 28}Si exit channel has been measured and has supplied evidence for a spin dis-alignment which has been interpreted in the framework of a molecular model by Butterfly motion. The spectroscopic study of {sup 32}S nucleus, has revealed the occurrence of a new {gamma}-ray transition 0{sup +}(8507.8 keV) {yields} 2{sub 1}{sup +}(2230.2 keV). (author) 105 refs., 116 figs., 26 tabs.

  8. Gondwanide continental collision and the origin of Patagonia

    Science.gov (United States)

    Pankhurst, R. J.; Rapela, C. W.; Fanning, C. M.; Má; rquez, M.

    2006-06-01

    A review of the post-Cambrian igneous, structural and metamorphic history of Patagonia, largely revealed by a five-year programme of U-Pb zircon dating (32 samples), geochemical and isotope analysis, results in a new Late Palaeozoic collision model as the probable cause of the Gondwanide fold belts of South America and South Africa. In the northeastern part of the North Patagonian Massif, Cambro-Ordovician metasediments with a Gondwana provenance are intruded by Mid Ordovician granites analogous to those of the Famatinian arc of NW Argentina; this area is interpreted as Gondwana continental crust at least from Devonian times, probably underlain by Neoproterozoic crystalline basement affected by both Pampean and Famatinian events, with a Cambrian rifting episode previously identified in the basement of the Sierra de la Ventana. In the Devonian (following collision of the Argentine Precordillera terrane to the north), the site of magmatism jumped to the western and southwestern margins of the North Patagonian Massif, although as yet the tectonics of this magmatic event are poorly constrained. This was followed by Early Carboniferous I-type granites representing a subduction-related magmatic are and Mid Carboniferous S-type granites representing crustal anatexis. The disposition of these rocks implies that the North Patagonian Massif was in the upper plate, with northeasterly subduction beneath Gondwana prior to the collision of a southern landmass represented by the Deseado Massif and its probable extension in southeastern Patagonia. This 'Deseado terrane' may have originally rifted off from a similar position during the Cambrian episode. Intense metamorphism and granite emplacement in the upper plate continued into the Early Permian. Known aspects of Late Palaeozoic sedimentation, metamorphism, and deformation in the Sierra de la Ventana and adjacent Cape Fold Belt of South Africa are encompassed within this model. It is also compatible with modern geophysical and

  9. Kink Collisions in Curved Field Space

    Science.gov (United States)

    Ahlqvist, Pontus; Eckerle, Kate; Greene, Brian

    2015-04-01

    We study bubble universe collisions in the ultrarelativistic limit with the new feature of allowing for nontrivial curvature in field space. We establish a simple geometrical interpretation of such collisions in terms of a double family of field profiles whose tangent vector fields stand in mutual parallel transport. This provides a generalization of the well-known flat field space limit of the free passage approximation. We investigate the limits of this approximation and illustrate our analytical results with numerical simulations.

  10. Two-Dimensional Distributed Velocity Collision Avoidance

    Science.gov (United States)

    2014-02-11

    a mechanism for congestion control. The TCP is useful for applications that need reliability and correctness such as web pages or databases. The...a curved turn, and for the protection of hardware assets via a buffer region. If the bot radius is too low, then the bots will always scrape or...both the KVO and non-KVO scenarios. Figure 12 shows the results in terms of scrapes , collisions, and runs completed with no collisions, and Figure 13

  11. ALICE: Simulated lead-lead collision

    CERN Document Server

    2003-01-01

    This track is an example of simulated data modelled for the ALICE detector on the Large Hadron Collider (LHC) at CERN, which will begin taking data in 2008. ALICE will focus on the study of collisions between nuclei of lead, a heavy element that produces many different particles when collided. It is hoped that these collisions will produce a new state of matter known as the quark-gluon plasma, which existed billionths of a second after the Big Bang.

  12. The effect of collisions in ionogram inversion

    CERN Document Server

    Scotto, Carlo

    2012-01-01

    The results of this paper demonstrate how the effect of collisions on the group refraction index is small, when the ordinary ray is considered. If, however, in order to improve the performance of a system for automatic interpretation of ionograms, the information contained in ordinary and extraordinary traces is combined, the effect of collisions between the electrons and neutral molecules should be taken into account for the extraordinary ray.

  13. Coulomb collision effects on linear Landau damping

    Energy Technology Data Exchange (ETDEWEB)

    Callen, J. D., E-mail: callen@engr.wisc.edu [University of Wisconsin, Madison, Wisconsin 53706-1609 (United States)

    2014-05-15

    Coulomb collisions at rate ν produce slightly probabilistic rather than fully deterministic charged particle trajectories in weakly collisional plasmas. Their diffusive velocity scattering effects on the response to a wave yield an effective collision rate ν{sub eff} ≫ ν and a narrow dissipative boundary layer for particles with velocities near the wave phase velocity. These dissipative effects produce temporal irreversibility for times t ≳ 1/ν{sub eff} during Landau damping of a small amplitude Langmuir wave.

  14. Nuclear collisions at the Future Circular Collider

    Science.gov (United States)

    Armesto, N.; Dainese, A.; d'Enterria, D.; Masciocchi, S.; Roland, C.; Salgado, C. A.; van Leeuwen, M.; Wiedemann, U. A.

    2016-12-01

    The Future Circular Collider is a new proposed collider at CERN with centre-of-mass energies around 100 TeV in the pp mode. Ongoing studies aim at assessing its physics potential and technical feasibility. Here we focus on updates in physics opportunities accessible in pA and AA collisions not covered in previous Quark Matter contributions, including Quark-Gluon Plasma and gluon saturation studies, novel hard probes of QCD matter, and photon-induced collisions.

  15. Nuclear collisions at the Future Circular Collider

    CERN Document Server

    Armesto, N; d'Enterria, D; Masciocchi, S; Roland, C; Salgado, C A; van Leeuwen, M; Wiedemann, U A

    2016-01-01

    The Future Circular Collider is a new proposed collider at CERN with centre-of-mass energies around 100 TeV in the pp mode. Ongoing studies aim at assessing its physics potential and technical feasibility. Here we focus on updates in physics opportunities accessible in pA and AA collisions not covered in previous Quark Matter contributions, including Quark-Gluon Plasma and gluon saturation studies, novel hard probes of QCD matter, and photon-induced collisions.

  16. Transition rates in proton - Rydberg atom collisions

    Science.gov (United States)

    Vrinceanu, Daniel

    2016-05-01

    Monte Carlo simulations for energy and angular momentum transfer processes in proton - Ryderg atom collisions were performed and the corresponding rates are reported.The relevance of these rates in the context of cosmological recombination is discussed. The rates are contrasted with the similar rates in electron - Rydberg atom collisions. This work has been supported by National Science Foundation through grants for the Center for Research on Complex Networks (HRD-1137732) and Research Infrastructure for Science and Engineering (RISE) (HRD-1345173).

  17. COLLISIONS OF ROAD VEHICLES WITH BRIDGE COLUMNS

    OpenAIRE

    2015-01-01

    As speed limits and traffic on city roads continue to increase, collisions between road vehicles and bridge columns are becoming more common. Current regulations analyze collision with one major simplification: replacing dynamic action with the equivalent static force. In the present paper, we develop a numerical model of a typical Croatian overpass and loaded it with an equivalent static load according to the EN1991-7 and ASSHTO LRFD provisions, analyzing the differences in overpass behavior...

  18. Molecular vibrational states during a collision

    Science.gov (United States)

    Recamier, Jose A.; Jauregui, Rocio

    1995-01-01

    Alternative algebraic techniques to approximate a given Hamiltonian by a harmonic oscillator are described both for time-independent and time-dependent systems. We apply them to the description of a one dimensional atom-diatom collision. From the resulting evolution operator, we evaluate vibrational transition probabilities as well as other time-dependent properties. As expected, the ground vibrational state becomes a squeezed state during the collision.

  19. Planetesimal Collisions as a Chondrule Forming Event

    Science.gov (United States)

    Wakita, Shigeru; Matsumoto, Yuji; Oshino, Shoichi; Hasegawa, Yasuhiro

    2017-01-01

    Chondritic meteorites contain unique spherical materials named chondrules: sub-mm sized silicate grains once melted in a high temperature condition in the solar nebula. We numerically explore one of the chondrule forming processes—planetesimal collisions. Previous studies have found that impact jetting via protoplanet–planetesimal collisions can make chondrules with 1% of the impactors’ mass, when the impact velocity exceeds 2.5 km s‑1. Based on the mineralogical data of chondrules, undifferentiated planetesimals would be more suitable for chondrule-forming collisions than potentially differentiated protoplanets. We examine planetesimal–planetesimal collisions using a shock physics code and find two things: one is that planetesimal–planetesimal collisions produce nearly the same amount of chondrules as protoplanet–planetesimal collisions (∼1%). The other is that the amount of produced chondrules becomes larger as the impact velocity increases when two planetesimals collide with each other. We also find that progenitors of chondrules can originate from deeper regions of large targets (planetesimals or protoplanets) than small impactors (planetesimals). The composition of targets is therefore important, to fully account for the mineralogical data of currently sampled chondrules.

  20. The Underlying Physics in Wetted Particle Collisions

    Science.gov (United States)

    Donahue, Carly; Hrenya, Christine; Davis, Robert

    2008-11-01

    Wetted granular particles are relevant in many industries including the pharmaceutical and chemical industries and has applications to granulation, filtration, coagulation, spray coating, drying and pneumatic transport. In our current focus, we investigate the dynamics of a three-body normal wetted particle collision. In order to conduct collisions we use an apparatus called a ``Stokes Cradle,'' similar to the Newton's Cradle (desktop toy) except that the target particles are covered with oil. Here, we are able to vary the oil thickness, oil viscosity, and material properties. With a three particle collision there are four possible outcomes: fully agglomerated (FA); Newton's Cradle (NC), the striker and the first target ball are agglomerated and the last target ball is separated; Reverse Newton's Cradle (RNC), the striker is separated and the two targets are agglomerated; and fully separated (FS). Varying the properties of the collisions, we have observed all four outcomes. We use elastohydrodynamics as a theoretical basis for modeling the system. We also have considered the glass transition of the oil as the pressure increases upon impact and the cavitation of the oil as the pressure drops below the vapor pressure upon rebound. A toy model has been developed where the collision is modeled as a series of two-body collisions. A qualitative agreement between the toy model and experiments gives insight into the underlying physics.

  1. J/$\\psi$ suppression at forward rapidity in Pb-Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV

    CERN Document Server

    Abelev, Betty; Adamova, Dagmar; Adare, Andrew Marshall; Aggarwal, Madan; Aglieri Rinella, Gianluca; Agocs, Andras Gabor; Agostinelli, Andrea; Aguilar Salazar, Saul; Ahammed, Zubayer; Ahmad, Arshad; Ahmad, Nazeer; Ahn, Sang Un; Akindinov, Alexander; Aleksandrov, Dmitry; Alessandro, Bruno; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Almaraz Avina, Erick Jonathan; Alme, Johan; Alt, Torsten; Altini, Valerio; Altinpinar, Sedat; Altsybeev, Igor; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anson, Christopher Daniel; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshauser, Harald; Arbor, Nicolas; Arcelli, Silvia; Arend, Andreas; Armesto, Nestor; Arnaldi, Roberta; Aronsson, Tomas Robert; Arsene, Ionut Cristian; Arslandok, Mesut; Asryan, Andzhey; Augustinus, Andre; Averbeck, Ralf Peter; Awes, Terry; Aysto, Juha Heikki; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bailhache, Raphaelle Marie; Bala, Renu; Baldini Ferroli, Rinaldo; Baldisseri, Alberto; Baldit, Alain; Baltasar Dos Santos Pedrosa, Fernando; Ban, Jaroslav; Baral, Rama Chandra; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Barret, Valerie; Bartke, Jerzy Gustaw; Basile, Maurizio; Bastid, Nicole; Bathen, Bastian; Batigne, Guillaume; Batyunya, Boris; Baumann, Christoph Heinrich; Bearden, Ian Gardner; Beck, Hans; Belikov, Iouri; Bellini, Francesca; Bellwied, Rene; Belmont-Moreno, Ernesto; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bergmann, Cyrano; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhati, Ashok Kumar; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Bjelogrlic, Sandro; Blanco, F; Blanco, Francesco; Blau, Dmitry; Blume, Christoph; Boccioli, Marco; Bock, Nicolas; Bogdanov, Alexey; Boggild, Hans; Bogolyubsky, Mikhail; Boldizsar, Laszlo; Bombara, Marek; Book, Julian; Borel, Herve; Borissov, Alexander; Bose, Suvendu Nath; Bossu, Francesco; Botje, Michiel; Bottger, Stefan; Boyer, Bruno Alexandre; Braidot, Ermes; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Browning, Tyler Allen; Broz, Michal; Brun, Rene; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Bugaiev, Kyrylo; Busch, Oliver; Buthelezi, Edith Zinhle; Caballero Orduna, Diego; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calvo Villar, Ernesto; Camerini, Paolo; Canoa Roman, Veronica; Cara Romeo, Giovanni; Carena, Wisla; Carena, Francesco; Carlin Filho, Nelson; Carminati, Federico; Carrillo Montoya, Camilo Andres; Casanova Diaz, Amaya Ofelia; Castillo Castellanos, Javier Ernesto; Castillo Hernandez, Juan Francisco; Casula, Ester Anna Rita; Catanescu, Vasile; Cavicchioli, Costanza; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Charvet, Jean-Luc Fernand; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Chawla, Isha; Cherney, Michael Gerard; Cheshkov, Cvetan; Cheynis, Brigitte; Chiavassa, Emilio; Chibante Barroso, Vasco Miguel; Chinellato, David; Chochula, Peter; Chojnacki, Marek; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Coccetti, Fabrizio; Colamaria, Fabio; Colella, Domenico; Conesa Balbastre, Gustavo; Conesa del Valle, Zaida; Constantin, Paul; Contin, Giacomo; Contreras, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortese, Pietro; Cortes Maldonado, Ismael; Cosentino, Mauro Rogerio; Costa, Filippo; Cotallo, Manuel Enrique; Crescio, Elisabetta; Crochet, Philippe; Cruz Alaniz, Emilia; Cuautle, Eleazar; Cunqueiro, Leticia; Dainese, Andrea; Dalsgaard, Hans Hjersing; Danu, Andrea; Das, Kushal; Das, Indranil; Das, Debasish; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; de Barros, Gabriel; De Caro, Annalisa; de Cataldo, Giacinto; de Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; Delagrange, Hugues; Del Castillo Sanchez, Eduardo; Deloff, Andrzej; Demanov, Vyacheslav; De Marco, Nora; Denes, Ervin; De Pasquale, Salvatore; Deppman, Airton; D'Erasmo, Ginevra; de Rooij, Raoul Stefan; Diaz Corchero, Miguel Angel; Di Bari, Domenico; Dietel, Thomas; Di Giglio, Carmelo; Di Liberto, Sergio; Di Mauro, Antonio; Di Nezza, Pasquale; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Dobrowolski, Tadeusz Antoni; Dominguez, Isabel; Donigus, Benjamin; Dordic, Olja; Driga, Olga; Dubey, Anand Kumar; Ducroux, Laurent; Dupieux, Pascal; Dutta Majumdar, AK; Dutta Majumdar, Mihir Ranjan; Elia, Domenico; Emschermann, David Philip; Engel, Heiko; Erdal, Hege Austrheim; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Evans, David; Eyyubova, Gyulnara; Fabris, Daniela; Faivre, Julien; Falchieri, Davide; Fantoni, Alessandra; Fasel, Markus; Fearick, Roger Worsley; Fedunov, Anatoly; Fehlker, Dominik; Feldkamp, Linus; Felea, Daniel; Feofilov, Grigory; Fernandez Tellez, Arturo; Ferretti, Alessandro; Ferretti, Roberta; Figiel, Jan; Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiore, Enrichetta Maria; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Fragkiadakis, Michail; Frankenfeld, Ulrich Michael; Fuchs, Ulrich; Furget, Christophe; Fusco Girard, Mario; Gaardhoje, Jens Joergen; Gagliardi, Martino; Gago, Alberto; Gallio, Mauro; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Garabatos, Jose; Garcia-Solis, Edmundo; Garishvili, Irakli; Gerhard, Jochen; Germain, Marie; Geuna, Claudio; Gheata, Andrei George; Gheata, Mihaela; Ghidini, Bruno; Ghosh, Premomoy; Gianotti, Paola; Girard, Martin Robert; Giubellino, Paolo; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez, Ramon; Gonzalez Ferreiro, Elena; Gonzalez-Trueba, Laura Helena; Gonzalez-Zamora, Pedro; Gorbunov, Sergey; Goswami, Ankita; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Grajcarek, Robert; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoriev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grinyov, Boris; Grion, Nevio; Gros, Philippe; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerra Gutierrez, Cesar; Guerzoni, Barbara; Guilbaud, Maxime Rene Joseph; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Gutbrod, Hans; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Han, Byounghee; Hanratty, Luke David; Hansen, Alexander; Harmanova, Zuzana; Harris, John William; Hartig, Matthias; Hasegan, Dumitru; Hatzifotiadou, Despoina; Hayrapetyan, Arsen; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Herrmann, Norbert; Hetland, Kristin Fanebust; Hicks, Bernard; Hille, Per Thomas; Hippolyte, Boris; Horaguchi, Takuma; Hori, Yasuto; Hristov, Peter Zahariev; Hrivnacova, Ivana; Huang, Meidana; Huber, Sebastian Bernd; Humanic, Thomas; Hwang, Dae Sung; Ichou, Raphaelle; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Incani, Elisa; Innocenti, Gian Michele; Innocenti, Pier Giorgio; Ippolitov, Mikhail; Irfan, Muhammad; Ivan, Cristian George; Ivanov, Vladimir; Ivanov, Andrey; Ivanov, Marian; Ivanytskyi, Oleksii; Jacholkowski, Adam Wlodzimierz; Jacobs, Peter; Jancurova, Lucia; Jang, Haeng Jin; Jangal, Swensy Gwladys; Janik, Malgorzata Anna; Janik, Rudolf; Jayarathna, Sandun; Jena, Satyajit; Jimenez Bustamante, Raul Tonatiuh; Jirden, Lennart; Jones, Peter Graham; Jung, Hyung Taik; Jusko, Anton; Kaidalov, Alexei; Kakoyan, Vanik; Kalcher, Sebastian; Kalinak, Peter; Kalisky, Matus; Kalliokoski, Tuomo Esa Aukusti; Kalweit, Alexander Philipp; Kanaki, Kalliopi; Kang, Ju Hwan; Kaplin, Vladimir; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karpechev, Evgeny; Kazantsev, Andrey; Kebschull, Udo Wolfgang; Keidel, Ralf; Khan, Mohisin Mohammed; Khan, Shuaib Ahmad; Khan, Palash; Khanzadeev, Alexei; Kharlov, Yury; Kileng, Bjarte; Kim, Minwoo; Kim, Jin Sook; Kim, Dong Jo; Kim, Taesoo; Kim, Beomkyu; Kim, Se Yong; Kim, Seon Hee; Kim, Do Won; Kim, Jonghyun; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Klay, Jennifer Lynn; Klein, Jochen; Klein-Bosing, Christian; Kliemant, Michael; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Koch, Kathrin; Kohler, Markus; Kolojvari, Anatoly; Kondratiev, Valery; Kondratyeva, Natalia; Konevskih, Artem; Korneev, Andrey; Kottachchi Kankanamge Don, Chamath; Kour, Ravjeet; Kowalski, Marek; Kox, Serge; Koyithatta Meethaleveedu, Greeshma; Kral, Jiri; Kralik, Ivan; Kramer, Frederick; Kraus, Ingrid Christine; Krawutschke, Tobias; Krelina, Michal; Kretz, Matthias; Krivda, Marian; Krizek, Filip; Krus, Miroslav; Kryshen, Evgeny; Krzewicki, Mikolaj; Kucheriaev, Yury; Kuhn, Christian Claude; Kuijer, Paul; Kurashvili, Podist; Kurepin, A; Kurepin, AB; Kuryakin, Alexey; Kushpil, Svetlana; Kushpil, Vasily; Kvaerno, Henning; Kweon, Min Jung; Kwon, Youngil; Ladron de Guevara, Pedro; Lakomov, Igor; Langoy, Rune; Lara, Camilo Ernesto; Lardeux, Antoine Xavier; La Rocca, Paola; Lazzeroni, Cristina; Lea, Ramona; Le Bornec, Yves; Lee, Sung Chul; Lee, Ki Sang; Lefevre, Frederic; Lehnert, Joerg Walter; Leistam, Lars; Lenhardt, Matthieu Laurent; Lenti, Vito; Leon, Hermes; Leon Monzon, Ildefonso; Leon Vargas, Hermes; Levai, Peter; Lien, Jorgen; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Liu, Lijiao; Loenne, Per-Ivar; Loggins, Vera; Loginov, Vitaly; Lohn, Stefan Bernhard; Lohner, Daniel; Loizides, Constantinos; Loo, Kai Krister; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lovhoiden, Gunnar; Lu, Xianguo; Luettig, Philipp; Lunardon, Marcello; Luo, Jiebin; Luparello, Grazia; Luquin, Lionel; Luzzi, Cinzia; Ma, Ke; Ma, Rongrong; Madagodahettige-Don, Dilan Minthaka; Maevskaya, Alla; Mager, Magnus; Mahapatra, Durga Prasad; Maire, Antonin; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Ludmila; Mal'Kevich, Dmitry; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Mangotra, Lalit Kumar; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Marin, Ana Maria; Marin Tobon, Cesar Augusto; Markert, Christina; Martashvili, Irakli; Martinengo, Paolo; Martinez, Mario Ivan; Martinez Davalos, Arnulfo; Martinez Garcia, Gines; Martynov, Yevgen; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Massacrier, Laure Marie; Mastromarco, Mario; Mastroserio, Annalisa; Matthews, Zoe Louise; Matyja, Adam Tomasz; Mayani, Daniel; Mayer, Christoph; Mazer, Joel; Mazzoni, Alessandra Maria; Meddi, Franco; Menchaca-Rocha, Arturo Alejandro; Mercado Perez, Jorge; Meres, Michal; Miake, Yasuo; Milano, Leonardo; Milosevic, Jovan; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz; Mitu, Ciprian Mihai; Mlynarz, Jocelyn; Mohanty, Ajit Kumar; Mohanty, Bedangadas; Molnar, Levente; Montano Zetina, Luis Manuel; Monteno, Marco; Montes, Esther; Moon, Taebong; Morando, Maurizio; Moreira De Godoy, Denise Aparecida; Moretto, Sandra; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhuri, Sanjib; Muller, Hans; Munhoz, Marcelo; Musa, Luciano; Musso, Alfredo; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Nattrass, Christine; Naumov, Nikolay; Navin, Sparsh; Nayak, Tapan Kumar; Nazarenko, Sergey; Nazarov, Gleb; Nedosekin, Alexander; Nicassio, Maria; Nielsen, Borge Svane; Niida, Takafumi; Nikolaev, Sergey; Nikolic, Vedran; Nikulin, Vladimir; Nikulin, Sergey; Nilsen, Bjorn Steven; Nilsson, Mads Stormo; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Novitzky, Norbert; Nyanin, Alexandre; Nyatha, Anitha; Nygaard, Casper; Nystrand, Joakim Ingemar; Ochirov, Alexander; Oeschler, Helmut Oskar; Oh, Sun Kun; Oh, Saehanseul; Oleniacz, Janusz; Oppedisano, Chiara; Ortiz Velasquez, Antonio; Ortona, Giacomo; Oskarsson, Anders Nils Erik; Ostrowski, Piotr Krystian; Otwinowski, Jacek Tomasz; Oyama, Ken; Ozawa, Kyoichiro; Pachmayer, Yvonne Chiara; Pachr, Milos; Padilla, Fatima; Pagano, Paola; Paic, Guy; Painke, Florian; Pajares, Carlos; Pal, Susanta Kumar; Pal, S; Palaha, Arvinder Singh; Palmeri, Armando; Papikyan, Vardanush; Pappalardo, Giuseppe; Park, Woo Jin; Passfeld, Annika; Pastircak, Blahoslav; Patalakha, Dmitri Ivanovich; Paticchio, Vincenzo; Pavlinov, Alexei; Pawlak, Tomasz Jan; Peitzmann, Thomas; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitri; Perez Lara, Carlos Eugenio; Perez Lezama, Edgar; Perini, Diego; Perrino, Davide; Peryt, Wiktor Stanislaw; Pesci, Alessandro; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petran, Michal; Petris, Mariana; Petrov, Plamen Rumenov; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Piccotti, Anna; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Pitz, Nora; Piuz, Francois; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Pluta, Jan Marian; Pocheptsov, Timur; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polak, Karel; Polichtchouk, Boris; Pop, Amalia; Porteboeuf-Houssais, Sarah; Pospisil, Vladimir; Potukuchi, Baba; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puchagin, Sergey; Puddu, Giovanna; Pujol Teixido, Jordi; Pulvirenti, Alberto; Punin, Valery; Putis, Marian; Putschke, Jorn Henning; Quercigh, Emanuele; Qvigstad, Henrik; Rachevski, Alexandre; Rademakers, Alphonse; Radomski, Sylwester; Raiha, Tomi Samuli; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Ramirez Reyes, Abdiel; Raniwala, Sudhir; Raniwala, Rashmi; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Reichelt, Patrick; Reicher, Martijn; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riccati, Lodovico; Ricci, Renato Angelo; Richert, Tuva; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Rodriguez Cahuantzi, Mario; Roed, Ketil; Rohr, David; Rohrich, Dieter; Romita, Rosa; Ronchetti, Federico; Rosnet, Philippe; Rossegger, Stefan; Rossi, Andrea; Roukoutakis, Filimon; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Ryabinkin, Evgeny; Rybicki, Andrzej; Sadovsky, Sergey; Safarik, Karel; Sahoo, Raghunath; Sahu, Pradip Kumar; Saini, Jogender; Sakaguchi, Hiroaki; Sakai, Shingo; Sakata, Dosatsu; Salgado, Carlos Albert; Salzwedel, Jai; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sandor, Ladislav; Sandoval, Andres; Sano, Satoshi; Sano, Masato; Santo, Rainer; Santoro, Romualdo; Sarkamo, Juho Jaako; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Hans Rudolf; Schmidt, Christian Joachim; Schreiner, Steffen; Schuchmann, Simone; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Patrick Aaron; Scott, Rebecca; Segato, Gianfranco; Selioujenkov, Ilya; Senyukov, Serhiy; Seo, Jeewon; Serci, Sergio; Serradilla, Eulogio; Sevcenco, Adrian; Sgura, Irene; Shabetai, Alexandre; Shabratova, Galina; Shahoyan, Ruben; Sharma, Natasha; Sharma, Satish; Shigaki, Kenta; Shimomura, Maya; Shtejer, Katherin; Sibiriak, Yury; Siciliano, Melinda; Sicking, Eva; Siddhanta, Sabyasachi; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, catherine; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Sinha, Tinku; Sinha, Bikash; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Skjerdal, Kyrre; Smakal, Radek; Smirnov, Nikolai; Snellings, Raimond; Sogaard, Carsten; Soltz, Ron Ariel; Son, Hyungsuk; Song, Myunggeun; Song, Jihye; Soos, Csaba; Soramel, Francesca; Sputowska, Iwona; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stan, Ionel; Stefanek, Grzegorz; Stefanini, Giorgio; Steinbeck, Timm Morten; Steinpreis, Matthew; Stenlund, Evert Anders; Steyn, Gideon Francois; Stocco, Diego; Stolpovskiy, Mikhail; Strabykin, Kirill; Strmen, Peter; Suaide, Alexandre Alarcon do Passo; Subieta Vasquez, Martin Alfonso; Sugitate, Toru; Suire, Christophe Pierre; Sukhorukov, Mikhail; Sultanov, Rishat; Sumbera, Michal; Susa, Tatjana; Szanto de Toledo, Alejandro; Szarka, Imrich; Szostak, Artur Krzysztof; Tagridis, Christos; Takahashi, Jun; Tapia Takaki, Daniel Jesus; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Thader, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony; Tlusty, David; Toia, Alberica; Torii, Hisayuki; Toscano, Luca; Tosello, Flavio; Truesdale, David Christopher; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ulery, Jason Glyndwr; Ullaland, Kjetil; Ulrich, Jochen; Uras, Antonio; Urban, Jozef; Urciuoli, Guido Marie; Usai, Gianluca; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; van der Kolk, Naomi; Vande Vyvre, Pierre; van Leeuwen, Marco; Vannucci, Luigi; Vargas, Aurora Diozcora; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vechernin, Vladimir; Veldhoen, Misha; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara, Sergio; Vernekohl, Don Constantin; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Vikhlyantsev, Oleg; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Yury; Vinogradov, Leonid; Virgili, Tiziano; Viyogi, Yogendra; Vodopianov, Alexander; Voloshin, Sergey; Voloshin, Kirill; Volpe, Giacomo; von Haller, Barthelemy; Vranic, Danilo; vrebekk, Gaute; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Vladimir; Wan, Renzhuo; Wang, Yifei; Wang, Dong; Wang, Yaping; Wang, Mengliang; Watanabe, Kengo; Wessels, Johannes; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Grzegorz Andrzej; Wilk, Alexander; Williams, Crispin; Windelband, Bernd Stefan; Xaplanteris Karampatsos, Leonidas; Yang, Hongyan; Yang, Shiming; Yasnopolsky, Stanislav; Yi, JunGyu; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-Kwon; Yoon, Jongik; Yu, Weilin; Yuan, Xianbao; Yushmanov, Igor; Zach, Cenek; Zampolli, Chiara; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zaviyalov, Nikolai; Zbroszczyk, Hanna Paulina; Zelnicek, Pierre; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Xiaoming; Zhou, Daicui; Zhou, You; Zhou, Fengchu; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zinovjev, Gennady; Zoccarato, Yannick Denis; Zynovyev, Mykhaylo

    2012-01-01

    The ALICE experiment has measured the inclusive J/ψ production in Pb-Pb collisions at √sNN = 2.76 TeV down to pt = 0 in the rapidity range 2.5 < y < 4. A suppression of the inclusive J/ψ yield in Pb-Pb is observed with respect to the one measured in pp collisions scaled by the number of binary nucleon-nucleon collisions. The nuclear modification factor, integrated over the 0%–80% most central collisions, is 0.545 ± 0.032(stat.) ± 0.084(syst.) and does not exhibit a significant de- pendence on the collision centrality. These features appear significantly different from lower energy measurements. Models including J/ψ production from charm quarks in a deconfined partonic phase can describe our data.

  2. LHC Report: First collisions soon

    CERN Multimedia

    Jan Uythoven for the LHC team

    2012-01-01

    On the evening of Friday 16 March beams were accelerated in the LHC at 4 TeV for the first time: a new world record! According to the schedule for the machine restart it will take another three weeks before the stable beams mode – the requirement for the detectors to start taking data – is achieved.   During the beam commissioning period the equipment teams make sure that their systems – beam instrumentation, radio frequency, beam interlock, feedback on orbit and tune, etc. – are working flawlessly with beam. Confidence in the correct functioning of all the magnets, their settings and their alignment is obtained by detailed measurements of the optics and the physical aperture. The optics measurements include the beta* of the squeezed beam at the centre of the experiments where the collisions will soon take place. This year the aim is to have a smaller beta* of 60 cm for the ATLAS and CMS experiments. As a reminder, smaller values of beta* mean thinner and m...

  3. Collision prediction software for radiotherapy treatments

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, Laura [Virginia Commonwealth University Medical Center, Richmond, Virginia 23298 (United States); Pearson, Erik A. [Techna Institute and the Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 2M9 (Canada); Pelizzari, Charles A., E-mail: c-pelizzari@uchicago.edu [Department of Radiation and Cellular Oncology, The University of Chicago, Chicago, Illinois 60637 (United States)

    2015-11-15

    Purpose: This work presents a method of collision predictions for external beam radiotherapy using surface imaging. The present methodology focuses on collision prediction during treatment simulation to evaluate the clearance of a patient’s treatment position and allow for its modification if necessary. Methods: A Kinect camera (Microsoft, Redmond, WA) is used to scan the patient and immobilization devices in the treatment position at the simulator. The surface is reconstructed using the SKANECT software (Occipital, Inc., San Francisco, CA). The treatment isocenter is marked using simulated orthogonal lasers projected on the surface scan. The point cloud of this surface is then shifted to isocenter and converted from Cartesian to cylindrical coordinates. A slab models the treatment couch. A cylinder with a radius equal to the normal distance from isocenter to the collimator plate, and a height defined by the collimator diameter is used to estimate collisions. Points within the cylinder clear through a full gantry rotation with the treatment couch at 0° , while points outside of it collide. The angles of collision are reported. This methodology was experimentally verified using a mannequin positioned in an alpha cradle with both arms up. A planning CT scan of the mannequin was performed, two isocenters were marked in PINNACLE, and this information was exported to AlignRT (VisionRT, London, UK)—a surface imaging system for patient positioning. This was used to ensure accurate positioning of the mannequin in the treatment room, when available. Collision calculations were performed for the two treatment isocenters and the results compared to the collisions detected the room. The accuracy of the Kinect-Skanect surface was evaluated by comparing it to the external surface of the planning CT scan. Results: Experimental verification results showed that the predicted angles of collision matched those recorded in the room within 0.5°, in most cases (largest deviation

  4. Evolution of stellar collision products in open clusters : II. A grid of low-mass collisions

    NARCIS (Netherlands)

    Glebbeek, E.; Pols, O.R.

    2008-01-01

    In a companion paper we studied the detailed evolution of stellar collision products that occurred in an N-body simulation of the old open cluster M 67 and compared our detailed models to simple prescriptions. In this paper we extend this work by studying the evolution of the collision products in o

  5. CMS collision events: candidate Upsilons in heavy-ion collisions – Dec 2010

    CERN Multimedia

    McCauley, Thomas

    2011-01-01

    Candidate Upsilon decay to two muons observed in a lead-lead collision at the LHC. The two red lines (tracks) are the two muons, the mass of orange lines are tracks from other particles produced in the collision, whose energy is measured in the electromagnetic calorimeter (red cuboids) and the hadron calorimeter (blue cuboids).

  6. GPU Accelerated Real-Time Collision Handling in Virtual Disassembly

    Institute of Scientific and Technical Information of China (English)

    Peng Du; Jie-Yi Zhao; Wan-Bin Pan; Yi-Gang Wang

    2015-01-01

    Previous collision detection methods for virtual disassembly mainly detect collisions at discrete time intervals, and use oriented bounding boxes to speed up the process. However, these discrete methods cannot guarantee no penetration occurs when the components move. Meanwhile, because some of the components are embedded into each other, these components cannot be separated in the subsequent process. To solve these problems, we propose an approach for real-time collision handling by utilizing the computational power of modern GPUs. First we present a novel GPU-based collision handling framework for virtual disassembly. Second we use a collision-streams based continuous collision detection to guarantee no collision missed. Finally we introduce a triangle intersection detection algorithm to solve the problem that collision cannot be detected when the components are embedded into each other at the initial configuration. The experimental results show that our method can improve the overall performance of collision detection and achieve real-time simulation.

  7. Mutual recombination in slow Si+ + H- collisions

    Institute of Scientific and Technical Information of China (English)

    Wang Jian-Guo; Liu Chun-Lei; Janev R. K.; Yan Jun; Shi Jian-Rong

    2006-01-01

    This paper studies the process of mutual neutralization of Si+ and H- ions in slow collisions within the multichannel Landau-Zener model. All important ionic-covalent couplings in this collision system are included in the collision dynamics. The cross sections for population of specific final states of product Si atom are calculated in the CM energy range 0.05 eV/u-5 keV/u. Both singlet and triplet states are considered. At collision energies below ~10 eV/u, the most populated singlet state is Si(3p4p, 1S0), while for energies above ~150eV/u it is the Si(3p, 4p, 1P1) state. In the case of triplet states, the mixed 3p4p(3 S1 +3P0) states are the most populated in the entire collision energy range investigated. The total cross section exhibits a broad maximum around 200-300 eV/u and for ECM ≤ 10eV/u it monotonically increases with decreasing the collision energy, reaching a value of 8 × 10-13 cm2 at ECM = 0.05 eV/u. The ion-pair formation process in Si(3p2 3PJ)+H(1s) collisions has also been considered and its cross section in the considered energy range is very small (smaller than 10-20 cm2 in the energy region below 1 keV/u).

  8. RELATIVISTIC HEAVY ION COLLISIONS: EXPERIMENT

    Energy Technology Data Exchange (ETDEWEB)

    Friedlander, Erwin M.; Heckman, Harry H.

    1982-04-01

    Relativistic heavy ion physics began as a 'no man's land' between particle and nuclear physics, with both sides frowning upon it as 'unclean', because on one hand, hadronic interactions and particle production cloud nuclear structure effects, while on the other, the baryonic environment complicates the interpretation of production experiments. They have attempted to review here the experimental evidence on RHI collisions from the point of view that it represents a new endeavor in the understanding of strong interaction physics. Such an approach appears increasingly justified; first, by the accumulation of data and observations of new features of hadronic interactions that could not have been detected outside a baryonic environment; second, by the maturation of the field owing to the advances made over the past several years in experimental inquiries on particle production by RHI, including pions, kaons, hyperons, and searches for antiprotons; and third, by the steady and progressive increase in the energy and mass ranges of light nuclear beams that have become available to the experiment; indeed the energy range has widened from the {approx} 0.2 to 2 AGeV at the Bevalac to {approx}4 AGeV at Dubna and recently, to the quantum jump in energies to {approx} 1000 equivalent AGeV at the CERN PS-ISR. Accompanying these expansions in the energy frontier are the immediate prospects for very heavy ion beams at the Bevalac up to, and including, 1 AGeV {sup 238}U, thereby extending the 'mass frontier' to its ultimate extent.

  9. Underactuated spacecraft formation reconfiguration with collision avoidance

    Science.gov (United States)

    Huang, Xu; Yan, Ye; Zhou, Yang

    2017-02-01

    Underactuated collision-free controllers are proposed in this paper for multiple spacecraft formation reconfiguration in circular orbits with the loss of either the radial or in-track thrust. A nonlinear dynamical model of underactuated formation flying is introduced, which is then linearized about circular orbits for controllability and feasibility analyses on underactuated formation reconfiguration. By using the inherent dynamics coupling of system states, reduced-order sliding mode controllers are then designed for either case to indirectly stabilize the system trajectories to the desired formations. In consideration of the collision-avoidance requirement, the artificial potential function method is then employed to design novel underactuated collision-avoidance maneuvers. Rigorous proof substantiates the capabilities of such maneuvers in preventing collisions even in the absence of radial or in-track thrust. Furthermore, a Lyapunov-based analysis ensures the asymptotic stability of the overall closed-loop system. Numerical simulations are performed in a J2-perturbed environment to verify the validity of the proposed underactuated control schemes for collision-free reconfiguration.

  10. The collision between two hydrogen atoms

    CERN Document Server

    Ray, Hasi

    2013-01-01

    The electron-electron correlation term in two-atomic collision is the most important, most difficult term to obtain the effective interatomic potential. Generally the H and H collision is a four center problem. It is extremely difficult to compute the electron-electron correlation term to include the effect of exchange or antisymmetry between two system electrons exactly. All the two-atomic collision related theoretical data differ from each other due to its difference in approximating the electron-electron correlation term. I invent a trick to evaluate the term exactly. Earlier the positronium (Ps) and H system was easily approximated as a three center problem due to the light mass of Ps. My new code for H-H collision using the ab-initio and exact static-exchange model (SEM) can reproduce exactly the same data of Ps and H system just by using the appropriate atomic parameters. The success of the present trick makes the foundation of a big monument in cold and low energy atomic collision physics. The Feshbach...

  11. Collisions of solid ice in planetesimal formation

    Science.gov (United States)

    Deckers, J.; Teiser, J.

    2016-03-01

    We present collision experiments of centimetre projectiles on to decimetre targets, both made up of solid ice, at velocities of 15-45 m s-1 at an average temperature of {T_{avg}}=255.8 ± 0.7 K. In these collisions, the centimetre body gets disrupted and part of it sticks to the target. This behaviour can be observed up to an upper threshold, that depends on the projectile size, beyond which there is no mass transfer. In collisions of small particles, as produced by the disruption of the centimetre projectiles, we also find mass transfer to the target. In this way, the larger body can gain mass, although the efficiency of the initial mass transfer is rather low. These collision results can be applied to planetesimal formation near the snowline, where evaporation and condensation is expected to produce solid ice. In free fall collisions at velocities up to about 7 m s-1, we investigated the threshold to fragmentation and coefficient of restitution of centimetre ice spheres.

  12. Collisions of solid ice in planetesimal formation

    CERN Document Server

    Deckers, J

    2016-01-01

    We present collision experiments of centimetre projectiles on to decimetre targets, both made up of solid ice, at velocities of $15\\,\\mathrm{m\\,s^{-1}}$ to $45\\,\\mathrm{m\\,s^{-1}}$ at an average temperature of $\\mathrm{T_{avg}}=255.8\\pm0.7\\,\\mathrm{K}$. In these collisions the centimetre body gets disrupted and part of it sticks to the target. This behaviour can be observed up to an upper threshold, that depends on the projectile size, beyond which there is no mass transfer. In collisions of small particles, as produced by the disruption of the centimetre projectiles, we also find mass transfer to the target. In this way the larger body can gain mass, although the efficiency of the initial mass transfer is rather low. These collision results can be applied to planetesimal formation near the snowline, where evaporation and condensation is expected to produce solid ice. In free fall collisions at velocities up to about $7\\,\\mathrm{m\\,s^{-1}}$, we investigated the threshold to fragmentation and coefficient of re...

  13. Modelling of a collision between two smartphones

    Science.gov (United States)

    de Jesus, V. L. B.; Sasaki, D. G. G.

    2016-09-01

    In the predominant approach in physics textbooks, the collision between particles is treated as a black box, where no physical quantity can be measured. This approach becomes even more evident in experimental classes where collisions are the simplest and most common way of applying the theorem of conservation of linear momentum in the asymptotic behavior. In this paper we develop and analyse an experiment on collisions using only two smartphones. The experimental setup is amazingly simple; the two devices are aligned on a horizontal table of lacquered wood, in order to slide more easily. At the edge of one of them a piece of common sponge is glued using double-sided tape. By using a free smartphone application, the values generated by the accelerometer of the two devices in full motion are measured and tabulated. Through numerical iteration, the speed graphs of the smartphones before, during, and after the collision are obtained. The main conclusions were: (i) the demonstration of the feasibility of using smartphones as an alternative to air tracks and electronic sensors employed in a teaching lab, (ii) the possibility of investigating the collision itself, its characteristics and effects; this is the great advantage of the use of smartphones over traditional experiments, (iii) the compatibility of the results with the impulse-momentum theorem, within the margin of uncertainty.

  14. Analyse du canal $\\Lambda_b \\to \\Lambda + J/\\Psi$ et mesure de la polarisation du baryon $\\Delta$ produit dans les collisions $p-p$ à 7 TeV avec le détecteur LHCb

    CERN Document Server

    Jahjah, Marwa

    2011-01-01

    The topics discussed and developed in this dissertation aim to propose a new way to test, in a direct manner, the symmetry of time reversal (T): an opportunity is offered by the LHC through the copious production of beauty baryons, especially the $\\Lambda_b$ whose decay channels in $\\Lambda V (1^{-})$ would reveal the existence of new odd observables under T. The Emphasis is put on the importance of the $\\Lambda_b$ initial polarization produced in p-p collisions, and especially those of intermediate resonances coming from $\\Lambda_b$. We first present the theoretical framework of this work and secondly the different procedures concerning the direct search of T violation. A phenomenological model considering the decay $\\Lambda_b \\to \\Lambda J/\\Psi$ has been developed, from which angular distributions are computed. A detailed study of the reconstruction and selection of the channel $\\Lambda_b \\to \\Lambda J/\\Psi$ is exposed as well as that of the channel $B_d^0 \\to J/\\Psi K_S^0$; channel used to validate the e...

  15. The Theory of High Energy Collision Processes - Final Report DOE/ER/40158-1

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tai, T.

    2011-09-15

    In 1984, DOE awarded Harvard University a new Grant DE-FG02-84ER40158 to continue their support of Tai Tsun Wu as Principal Investigator of research on the theory of high energy collision processes. This Grant was renewed and remained active continuously from June 1, 1984 through November 30, 2007. Topics of interest during the 23-year duration of this Grant include: the theory and phenomenology of collision and production processes at ever higher energies; helicity methods of QED and QCD; neutrino oscillations and masses; Yang-Mills gauge theory; Beamstrahlung; Fermi pseudopotentials; magnetic monopoles and dyons; cosmology; classical confinement; mass relations; Bose-Einstein condensation; and large-momentum-transfer scattering processes. This Final Report describes the research carried out on Grant DE-FG02-84ER40158 for the period June 1, 1984 through November 30, 2007. Two books resulted from this project and a total of 125 publications.

  16. Solitons collision and freak waves in a plasma with Cairns-Tsallis particle distributions

    Science.gov (United States)

    El-Tantawy, S. A.; Wazwaz, A. M.; Schlickeiser, R.

    2015-12-01

    The solitons collision (head-on collision) and rogue waves in an unmagnetized plasma comprising nonthermal-nonextensive distributed (Cairns-Tsallis) electrons and cold ions are investigated. For solitons collision, the extended Poincaré-Lighthill-Kuo (PLK) method is employed to derive the coupled Korteweg-de Vries (KdV) equations and their corresponding phase shifts. It is found that solitons having two polarities can propagate in the present model. The coefficients of the nonlinear terms of the coupled KdV equations vanish at a critical value of nonthermality. Therefore, another set of coupled modified KdV (mKdV) equations with cubic nonlinearity is derived and the corresponding phase shifts are calculated. It is found analytically and numerically that the solutions of the coupled KdV equations allow solitons collision only when the solitons have the same polarity, whereas the coupled mKdV equations allow the collisions between the two solitons of the same and opposite polarities. The influence of the nonthermal-nonextensive parameters on the phase shifts of the solitons collision is examined. Furthermore, the rogue waves are studied in the framework of the mKdV equation. The behavior of the rogue waves is analyzed using the nonlinear Schrödinger equation (NLSE), derived from the mKdV equation. It is found that the rogue wave amplitude shrinks with the increase of the nonextensive parameter. The NLSE derived from the KdV equation cannot support the presence of rogue waves.

  17. {phi}, {rho} and {omega} meson production in the collisions d-C, d-U, S-U at 200 GeV/nucleon and Pb-Pb at 158 GeV/nucleon; Production de mesons {phi}, {rho} et {omega} dans les collisions d-C,d-U, S-U a 200 GeV/nucleon et Pb-Pb a 158 GeV/nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Astruc, J. [Institut National de Physique Nucleaire et de Physique des Particules (India2P3), 75 - Paris (France)

    1997-07-09

    Experiments NA38 and NA50, at the CERN-SPS, study the muon production in ultrarelativistic heavy ion collisions. They are dedicated to the measurement of the {phi}, {omega}, {rho} and J/{psi} production rates. The change of the vector meson production when using heavy ion projectiles, may be a signature for quark gluon plasma (QGP) phase transition. This new form of matter could be produced at the high temperature reached in this collisions. Among others, the anomalous increase of strangeness production could be a signature of the QGP formation. In this thesis, we present the studies of the {phi} strange meson production with respect to that of non-strange mesons, {rho} and {omega}, in d-C, d-U and S-U collisions at 200 GeV/c per nucleon and Pb-Pb at 158 GeV/c per nucleon in different transverse mass bins of the muon pairs. The comparison between the {phi} and the {rho} + {omega} production, as well as the mass continuum, shows an increase of the {phi} production with respect to that of the {rho} + {omega}, with the increasing size of the system and with increasing centrality in S-U and Pb-Pb collisions. The cross section studies in the different systems show the change of the behaviour of vector meson production when going from deuterium-nucleus to nucleus-nucleus interactions. Besides, a general evolution of the {rho} + {omega} and continuum production is observed, on which an additional increase for {phi} is superimposed. These evolutions are even more coherent between the S-U and Pb-Pb collisions and manifest themselves by an increase of the inverse slopes of the transverse mass spectra between d-C and S-U. A atypical behaviour of the {phi}/{omega} ratio in the in the most central Pb-Pb collisions for which the same experiment has made evident a abnormal suppression of J/{psi}, was also observed. (author) 61 refs.

  18. Chiral Magnetic Effect in Heavy Ion Collisions

    CERN Document Server

    Liao, Jinfeng

    2016-01-01

    The Chiral Magnetic Effect (CME) is a remarkable phenomenon that stems from highly nontrivial interplay of QCD chiral symmetry, axial anomaly, and gluonic topology. 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 $|\\vec{\\bf B}|\\sim m_\\pi^2$ are present during the early stage of such collisions. Significant efforts have been made to look for CME signals in heavy ion collision experiments. In this contribution we give a brief overview on the status of such efforts.

  19. Characteristics of Collision, Capacitive Radio Frequency Sheath

    Institute of Scientific and Technical Information of China (English)

    Zhang Yu; DingWanYu; Wang Wenchun; Liu JinYuan; Wang Xiaogang; Liu Yue

    2005-01-01

    A simple collisional radio frequency (rf) sheath fluid model, which is not restricted by the ratio of rf frequency to ion plasma frequency (β=ωrf/ωpi), was established and solved numerically. In the ion balance equation, the effect of the collision on the ion and the ion velocity is assumed to be a direct ratio to ion velocity. The ion energy distributions (IEDs) calculated in the model in comparison with the experimental data [M. A. Sobolewski, J. K. Olthoff, and Y.C. Wang, J. Appl. Phys. 85, 3966 (1999)], proved the validity of the model. And the effect of the collision on the sheath characteristic was obtained and discussed. This paper demonstrates that the collision frequency is another crucial parameter as well as the ratio β to determine the rf sheath characteristics and the shape of IE Ds.

  20. Physics of Ultra-Peripheral Nuclear Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Bertulani, Carlos A.; Klein, Spencer R.; Nystrand, Joakim

    2005-02-02

    Moving highly-charged ions carry strong electromagnetic fields which act as a field of photons. In collisions at large impact parameters, hadronic interactions are not possible, and the ions interact through photon-ion and photon-photon collisions known as ultra-peripheral collisions (UPC). Hadron colliders like the Relativistic Heavy Ion Collider (RHIC), the Tevatron and the Large Hadron Collider (LHC) produce photonuclear and two-photon interactions at luminosities and energies beyond that accessible elsewhere; the LHC will reach a {gamma}p energy ten times that of the Hadron-Electron Ring Accelerator (HERA). Reactions as diverse as the production of anti-hydrogen, photoproduction of the {rho}{sup 0}, transmutation of lead into bismuth and excitation of collective nuclear resonances have already been studied. At the LHC, UPCs can study many types of ''new physics''.

  1. Collision-spike Sputtering of Au Nanoparticles.

    Science.gov (United States)

    Sandoval, Luis; Urbassek, Herbert M

    2015-12-01

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; the remainder is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering.

  2. Chemical Equilibrium in Collisions of Small Systems

    CERN Document Server

    Kraus, I; Oeschler, H; Redlich, K; Wheaton, S

    2007-01-01

    The system-size dependence of particle production in heavy-ion collisions at the top SPS energy is analyzed in terms of the statistical model. A systematic comparison is made of two suppression mechanisms that quantify strange particle yields in ultra-relativistic heavy-ion collisions: the canonical model with strangeness correlation radius determined from the data and the model formulated in the canonical ensemble using chemical off-equilibrium strangeness suppression factor. The system-size dependence of the correlation radius and the thermal parameters are obtained for p-p, C-C, Si-Si and Pb-Pb collisions at sqrt(s_NN) = 17.3 AGeV. It is shown that on the basis of a consistent set of data there is no clear difference between the two suppression patterns. In the present study the strangeness correlation radius was found to exhibit a rather weak dependence on the system size.

  3. Neutrino quantum kinetic equations: The collision term

    Science.gov (United States)

    Blaschke, Daniel N.; Cirigliano, Vincenzo

    2016-08-01

    We derive the collision term relevant for neutrino quantum kinetic equations in the early universe and compact astrophysical objects, displaying its full matrix structure in both flavor and spin degrees of freedom. We include in our analysis neutrino-neutrino processes, scattering and annihilation with electrons and positrons, and neutrino scattering off nucleons (the latter in the low-density limit). After presenting the general structure of the collision terms, we take two instructive limiting cases. The one-flavor limit highlights the structure in helicity space and allows for a straightforward interpretation of the off-diagonal entries in terms of the product of scattering amplitudes of the two helicity states. The isotropic limit is relevant for studies of the early universe: in this case the terms involving spin coherence vanish and the collision term can be expressed in terms of two-dimensional integrals, suitable for computational implementation.

  4. Neutrino Quantum Kinetic Equations: The Collision Term

    CERN Document Server

    Blaschke, Daniel N

    2016-01-01

    We derive the collision term relevant for neutrino quantum kinetic equations in the early universe and compact astrophysical objects, displaying its full matrix structure in both flavor and spin degrees of freedom. We include in our analysis neutrino-neutrino processes, scattering and annihilation with electrons and positrons, and neutrino scattering off nucleons (the latter in the low-density limit). After presenting the general structure of the collision terms, we take two instructive limiting cases. The one-flavor limit highlights the structure in helicity space and allows for a straightforward interpretation of the off-diagonal entries in terms of the product of scattering amplitudes of the two helicity states. The isotropic limit is relevant for studies of the early universe: in this case the terms involving spin coherence vanish and the collision term can be expressed in terms of two-dimensional integrals, suitable for computational implementation.

  5. Tilting Uranus without a Collision

    Science.gov (United States)

    Rogoszinski, Zeeve; Hamilton, Douglas P.

    2016-10-01

    The most accepted hypothesis for the origin of Uranus' 98° obliquity is a giant collision during the late stages of planetary accretion. This model requires a single Earth mass object striking Uranus at high latitudes; such events occur with a probability of about 10%. Alternatively, Uranus' obliquity may have arisen from a sequence of smaller impactors which lead to a uniform distribution of obliquities. Here we explore a third model for tilting Uranus using secular spin-orbit resonance theory. We investigate early Solar System configurations in which a secular resonance between Uranus' axial precession frequency and another planet's orbital node precession frequency might occur.Thommes et al. (1999) hypothesized that Uranus and Neptune initially formed between Jupiter and Saturn, and were then kicked outward. In our scenario, Neptune leaves first while Uranus remains behind. As an exterior Neptune slowly migrates outward, it picks up both Uranus and Saturn in spin-orbit resonances (Ward and Hamilton 2004; Hamilton and Ward 2004). Only a distant Neptune has a nodal frequency slow enough to resonate with Uranus' axial precession.This scenario, with diverging orbits, results in resonance capture. As Neptune migrates outward its nodal precession slows. While in resonance, Uranus and Saturn each tilt a bit further, slowing their axial precession rates to continually match Neptune's nodal precession rate. Tilting Uranus to high obliquities takes a few 100 Myrs. This timescale may be too long to hold Uranus captive between Jupiter and Saturn, and we are investigating how to reduce it. We also find that resonance capture is rare if Uranus' initial obliquity is greater than about 10°, as the probability of capture decreases as the planet's initial obliquity increases. We will refine this estimate by quantifying capture statistics, and running accretion simulations to test the likelihood of a low early obliquity. Our preliminary findings show that most assumptions about

  6. Collision strengths and transition probabilities for Co II infrared forbidden lines

    CERN Document Server

    Storey, P J; Sochi, Taha

    2016-01-01

    We calculate collision strengths and their thermally-averaged Maxwellian values for electron excitation and de-excitation between the fifteen lowest levels of singly-ionised cobalt, Co+, which give rise to emission lines in the near- and mid-infrared. Transition probabilities are also calculated and relative line intensities predicted for conditions typical of supernova ejecta. The diagnostic potential of the 10.52, 15.46 and 14.74 micro-metre transition lines is briefly discussed.

  7. High energy density in multisoliton collisions

    Science.gov (United States)

    Saadatmand, Danial; Dmitriev, Sergey V.; Kevrekidis, Panayotis G.

    2015-09-01

    Solitons are very effective in transporting energy over great distances and collisions between them can produce high energy density spots of relevance to phase transformations, energy localization and defect formation among others. It is then important to study how energy density accumulation scales in multisoliton collisions. In this study, we demonstrate that the maximal energy density that can be achieved in collision of N slowly moving kinks and antikinks in the integrable sine-Gordon field, remarkably, is proportional to N2, while the total energy of the system is proportional to N . This maximal energy density can be achieved only if the difference between the number of colliding kinks and antikinks is minimal, i.e., is equal to 0 for even N and 1 for odd N and if the pattern involves an alternating array of kinks and antikinks. Interestingly, for odd (even) N the maximal energy density appears in the form of potential (kinetic) energy, while kinetic (potential) energy is equal to zero. The results of the present study rely on the analysis of the exact multisoliton solutions for N =1 ,2 , and 3 and on the numerical simulation results for N =4 ,5 ,6 , and 7. The effect of weak Hamiltonian and non-Hamiltonian perturbations on the maximal energy density in multikink collisions is also discussed as well as that of the collision relative phase. Based on these results one can speculate that the soliton collisions in the sine-Gordon field can, in principle, controllably produce very high energy density. This can have important consequences for many physical phenomena described by the Klein-Gordon equations.

  8. Reaction mechanisms and staggering in S+Ni collisions

    Science.gov (United States)

    D'Agostino, M.; Bruno, M.; Gulminelli, F.; Morelli, L.; Baiocco, G.; Bardelli, L.; Barlini, S.; Cannata, F.; Casini, G.; Geraci, E.; Gramegna, F.; Kravchuk, V. L.; Marchi, T.; Moroni, A.; Ordine, A.; Raduta, Ad. R.

    2011-07-01

    The reactions S32+Ni58 and S32+Ni64 are studied at 14.5 A MeV. After a selection of the collision mechanism, we show that important even-odd effects are present in the isotopic fragment distributions when the excitation energy is small. Close to the multifragmentation threshold this staggering appears hidden by the rapid variation of the production yields with the fragment size. Once this effect is accounted for, the staggering appears to be a universal feature of fragment production, slightly enhanced when the emission source is neutron poor. A closer look at the behavior of the production yields as a function of the neutron excess N-Z, reveals that odd-even effects cannot be explained by pairing effects in the nuclear masses alone, but depend in a more complex way on the de-excitation chain.

  9. Reaction mechanisms and staggering in S+Ni collisions

    Energy Technology Data Exchange (ETDEWEB)

    D' Agostino, M., E-mail: dagostino@bo.infn.it [Dipartimento di Fisica dell' Universita and INFN, Bologna (Italy); Bruno, M. [Dipartimento di Fisica dell' Universita and INFN, Bologna (Italy); Gulminelli, F. [LPC (IN2P3-CNRS/Ensicaen et Universite), F-14076 Caen cedex (France); Morelli, L. [Dipartimento di Fisica dell' Universita and INFN, Bologna (Italy); Baiocco, G. [Dipartimento di Fisica dell' Universita and INFN, Bologna (Italy); LPC (IN2P3-CNRS/Ensicaen et Universite), F-14076 Caen cedex (France); Bardelli, L. [INFN, Firenze (Italy); INFN, Catania (Italy); Barlini, S. [INFN, Firenze (Italy); Cannata, F. [Dipartimento di Fisica dell' Universita and INFN, Bologna (Italy); Casini, G. [INFN, Firenze (Italy); Geraci, E. [Dipartimento di Fisica dell' Universita, Catania (Italy); INFN, Catania (Italy); Gramegna, F.; Kravchuk, V.L. [INFN, Laboratori Nazionali di Legnaro (Italy); Marchi, T. [INFN, Laboratori Nazionali di Legnaro (Italy); Dipartimento di Fisica dell' Universita, Padova (Italy); Moroni, A. [INFN, Milano (Italy); Ordine, A. [INFN, Napoli (Italy); Raduta, Ad.R. [NIPNE, Bucharest-Magurele, POB-MG6 (Romania)

    2011-07-01

    The reactions {sup 32}S+{sup 58}Ni and {sup 32}S+{sup 64}Ni are studied at 14.5 A MeV. After a selection of the collision mechanism, we show that important even-odd effects are present in the isotopic fragment distributions when the excitation energy is small. Close to the multifragmentation threshold this staggering appears hidden by the rapid variation of the production yields with the fragment size. Once this effect is accounted for, the staggering appears to be a universal feature of fragment production, slightly enhanced when the emission source is neutron poor. A closer look at the behavior of the production yields as a function of the neutron excess N-Z, reveals that odd-even effects cannot be explained by pairing effects in the nuclear masses alone, but depend in a more complex way on the de-excitation chain.

  10. Percolation Approach to Initial Stage Effects in High Energy Collisions

    CERN Document Server

    Srivastava, Brijesh K

    2014-01-01

    Possible phase transition of strongly interacting matter from hadron to a quark-gluon plasma state have in the past received considerable interest. The clustering of color sources provides a framework of the the partonic interactions in the initial stage of the collisions. The onset of de-confinement transition is identified by the spanning percolation cluster in 2D percolation. In this talk results are presented both for the multiplicity and the elliptic flow at RHIC and LHC energies. The thermodynamic quantities temperature, equation of state and transport coefficient are obtained in the framework of clustering of color sources. It is shown that the results are in excellent agreement with the recent lattice QCD calculations(LQCD).

  11. Newton's cradle undone: Experiments and collision models for the normal collision of three solid spheres

    Science.gov (United States)

    Donahue, C. M.; Hrenya, C. M.; Zelinskaya, A. P.; Nakagawa, K. J.

    2008-11-01

    Using an apparatus inspired by Newton's cradle, the simultaneous, normal collision between three solid spheres is examined. Namely, an initially touching, motionless pair of "target" particles (doublet) is impacted on one end by a third "striker" particle. Measurements of postcollisional velocities and collision durations are obtained via high-speed photography and an electrical circuit, respectively. Contrary to intuition, the expected Newton's cradle outcome of a motionless, touching particle pair at the bottom of the pendulum arc is not observed in either case. Instead, the striker particle reverses its direction and separates from the middle particle after collision. This reversal is not observed, however, if the target particles are separated by a small distance (not in contact) initially, although a separation still occurs between the striker and middle particle after the collision, with both particles traveling in the same direction. For the case of initially touching target particles, contact duration measurements indicate that the striker separates from the three particles before the two target particles separate. However, when the targets are slightly separated, a three-particle collision is never observed, and the collision is, in fact, a series of two-body collisions. A subsequent implementation of a variety of hard-sphere and soft-sphere collision models indicates that a three-body (soft-sphere) treatment is essential for predicting the velocity reversal, consistent with the experimental findings. Finally, a direct comparison between model predictions and measurements of postcollisional velocities and contact durations provides a gauge of the relative merits of existing collision models for three-body interactions.

  12. Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions

    CERN Document Server

    Chen, Lin; Wei, Shu-Yi; Xiao, Bo-Wen; Zhang, Han-Zhong

    2016-01-01

    Dijet, dihadron, hadron-jet angular correlations have been reckoned as important probes of the transverse momentum broadening effects in relativistic nuclear collisions. When a pair of high-energy jets created in hard collisions traverse the quark-gluon plasma produced in heavy-ion collisions, they become de-correlated due to the vacuum soft gluon radiation associated with the Sudakov logarithms and the medium-induced transverse momentum broadening. For the first time, we employ the systematical resummation formalism and establish a baseline calculation to describe the dihadron and hadron-jet angular correlation data in $pp$ and peripheral $AA$ collisions where the medium effect is negligible. We demonstrate that the medium effects, especially the so-called jet quenching parameter $\\hat q$, can be extracted from the angular de-correlations observed in $AA$ collisions. A global $\\chi^2$ analysis of dihadron and hadron-jet angular correlation data renders the best fit $\\langle \\hat q L\\rangle_{\\textrm{tot}} \\si...

  13. SOME COLLISION PROCESSES IN PLASMAS WITH HIGHER TEMPERATURE AND DENSITY

    Institute of Scientific and Technical Information of China (English)

    KazuoTakayanagi

    1990-01-01

    Some collision processes important in hot and dense plasmas are discussed.Recent calculation of secondary electron velocity distribution in ionizing collision between an electron and a multiply-charged ion is reported.

  14. Multiobjective Optimization Based Vessel Collision Avoidance Strategy Optimization

    Directory of Open Access Journals (Sweden)

    Qingyang Xu

    2014-01-01

    Full Text Available The vessel collision accidents cause a great loss of lives and property. In order to reduce the human fault and greatly improve the safety of marine traffic, collision avoidance strategy optimization is proposed to achieve this. In the paper, a multiobjective optimization algorithm NSGA-II is adopted to search for the optimal collision avoidance strategy considering the safety as well as economy elements of collision avoidance. Ship domain and Arena are used to evaluate the collision risk in the simulation. Based on the optimization, an optimal rudder angle is recommended to navigator for collision avoidance. In the simulation example, a crossing encounter situation is simulated, and the NSGA-II searches for the optimal collision avoidance operation under the Convention on the International Regulations for Preventing Collisions at Sea (COLREGS. The simulation studies exhibit the validity of the method.

  15. Plasmas applied atomic collision physics, v.2

    CERN Document Server

    Barnett, C F

    1984-01-01

    Applied Atomic Collision Physics, Volume 2: Plasmas covers topics on magnetically confined plasmas. The book starts by providing the history of fusion research and describing the various approaches in both magnetically and inertially confined plasmas. The text then gives a general discussion of the basic concepts and properties in confinement and heating of a plasma. The theory of atomic collisions that result in excited quantum states, particularly highly ionized impurity atoms; and diverse diagnostic topics such as emission spectra, laser scattering, electron cyclotron emission, particle bea

  16. Horndeski/Galileon in High Energy Collisions

    CERN Document Server

    Latosh, B N

    2016-01-01

    Horndeski/Galileons may be considered as a proper generalization of General Relativity in high energy regime. Thus one may search for manifestation of Galileons interaction in collision experiments. In this paper we give arguments supporting this thesis. Galileon scalar field do not interact with matter via Standard Model interactions, we discuss a mechanism that allows Galileons to have influence on particle collisions. We give reasons to narrow the whole class of Horndeski/Galileons models to one particular term - John term from Fab Four subclass - for this particular issue. We were able to establish the constraint on the model coupling constant.

  17. Spatial Analysis Methods of Road Traffic Collisions

    DEFF Research Database (Denmark)

    Loo, Becky P. Y.; Anderson, Tessa Kate

    Spatial Analysis Methods of Road Traffic Collisions centers on the geographical nature of road crashes, and uses spatial methods to provide a greater understanding of the patterns and processes that cause them. Written by internationally known experts in the field of transport geography, the book...... outlines the key issues in identifying hazardous road locations (HRLs), considers current approaches used for reducing and preventing road traffic collisions, and outlines a strategy for improved road safety. The book covers spatial accuracy, validation, and other statistical issues, as well as link......-attribute and event-based approaches, cluster identification, and risk exposure....

  18. Plasma Polarization Spectroscopy and collision cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Takashi; Nakai, Manabu [Dept. of Engineering Physics and Mechanics, Graduate School of Engineering, Kyoto Univ. (Japan)

    2000-01-01

    In Plasma Polarization Spectroscopy (PPS), we observe the polarized spectral lines emitted from a plasma. For berylliumlike oxygen lines from a tokamak plasma the polarization feature is interpreted as due to the anisotropic velocity distribution of electrons which excite the ions. In this interpretation in terms of the population-alignment collisional-radiative (PACR) model various collision processes are involved concerning the population and the alignment, e.g., transfer of the alignment, and the coherence by collisional excitation and production of an alignment from a population by elastic collisions. These latter processes are little known so far. (author)

  19. Regular collision of dilatonic inflating branes

    CERN Document Server

    Leeper, E; Maartens, R

    2005-01-01

    We demonstrate that a two brane system with a bulk scalar field driving power-law inflation on the branes has an instability in the radion. We solve for the resulting trajectory of the brane, and find that the instability can lead to collision. Brane quantities such as the scale factor are shown to be regular at this collision. In addition we describe the system using a low energy expansion. The low energy expansion accurately reproduces the known exact solution, but also identifies an alternative solution for the bulk metric and brane trajectory.

  20. Photons from nuclear collisions at RHIC energies

    CERN Document Server

    Gale, Charles; Frodermann, Evan; Heinz, Ulrich

    2008-01-01

    We model the hot and dense strongly interacting mater produced in high energy heavy ion collisions using relativistic hydrodynamics. Several different sources of real photons produced during these collisions are considered and their relative importance is assessed. We include contributions from QCD jets, which are allowed to loose and gain energy as they proceed through the hot matter. This is treated within the AMY formalism. We obtain photon spectra, R_{AA}, and v_2 in agreement with measurements performed by the PHENIX collaboration.

  1. Applied atomic and collision physics special topics

    CERN Document Server

    Massey, H S W; Bederson, Benjamin

    1982-01-01

    Applied Atomic Collision Physics, Volume 5: Special Topics deals with topics on applications of atomic collisions that were not covered in the first four volumes of the treatise. The book opens with a chapter on ultrasensitive chemical detectors. This is followed by separate chapters on lighting, magnetohydrodynamic electrical power generation, gas breakdown and high voltage insulating gases, thermionic energy converters, and charged particle detectors. Subsequent chapters deal with the operation of multiwire drift and proportional chambers and streamer chambers and their use in high energy p

  2. Guide to the collision avoidance rules

    CERN Document Server

    Cockcroft, A N

    2004-01-01

    A Guide to the Collision Avoidance Rules is the essential reference to the safe operation of all vessels at sea. Published continuously since 1965, this respected and expert guide is the classic text for all who need to, practically and legally, understand and comply with the Rules. This sixth edition incorporates all of the amendments to the International Regulations for Preventing Collisions at Sea which came into force in November 2003.The books sets out all of the Rules with clear explanation of their meaning, and gives detailed examples of how the rules have been used in practice

  3. Intelligent Sensor Tasking for Space Collision Mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S S; Pertica, A J; Henderson, J R

    2010-04-01

    Orbital collisions pose a hazard to space operations. Using a high performance computer modeling and simulation environment for space situational awareness, we explore a new paradigm for improving satellite conjunction analysis by obtaining more precise orbital information only for those objects that pose a collision risk greater than a defined threshold to a specific set of satellites during a specified time interval. In particular, we assess the improvement in the quality of the conjunction analysis that can be achieved using a distributed network of ground-based telescopes.

  4. Centrality determination in pPb collisions with CMS

    Energy Technology Data Exchange (ETDEWEB)

    Tuo, Shengquan

    2014-06-15

    Centrality is very important for defining the collision system size in heavy ion collisions. It provides a tool for selecting events according to cross section in a similar way in different experiments and facilitates the comparison of experimental results and theoretical calculations. The progress of centrality determination in pPb collisions at CMS is presented. The choice of variables used for event classification will be discussed. Methods for the estimation of the number of nucleon–nucleon collisions will be shown.

  5. 14 CFR 121.356 - Collision avoidance system.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Collision avoidance system. 121.356 Section... Collision avoidance system. Effective January 1, 2005, any airplane you operate under this part must be equipped and operated according to the following table: Collision Avoidance Systems If you operate...

  6. 14 CFR 437.65 - Collision avoidance analysis.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Collision avoidance analysis. 437.65..., DEPARTMENT OF TRANSPORTATION LICENSING EXPERIMENTAL PERMITS Safety Requirements § 437.65 Collision avoidance... permittee must obtain a collision avoidance analysis from United States Strategic Command. (b) The...

  7. 14 CFR 417.231 - Collision avoidance analysis.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Collision avoidance analysis. 417.231..., DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.231 Collision avoidance analysis. (a) General. A flight safety analysis must include a collision avoidance analysis...

  8. 14 CFR 125.224 - Collision avoidance system.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Collision avoidance system. 125.224 Section... Requirements § 125.224 Collision avoidance system. Effective January 1, 2005, any airplane you operate under this part 125 must be equipped and operated according to the following table: Collision...

  9. Some properties of the central heavy ion collisions

    CERN Document Server

    Wazir, Z; Khan, E U; Haseeb, Mahnaz Q; Ajaz, M; Khan, K H

    2009-01-01

    Some experimental results are discussed in connection with the properties of the central heavy ion collisions. These experiments indicate the regime changes and saturation at some values of the centrality. This phenomenon is considered to be a signal of the percolation cluster formation in heavy ion collisions at high energies. Keywords: heavy ion collisions, theoretical models, centrality, phase transition.

  10. Gluon field fluctuations in nuclear collisions: Multiplicity and eccentricity distributions

    CERN Document Server

    Schenke, Björn; Venugopalan, Raju

    2013-01-01

    We discuss different sources of fluctuations in nuclear collisions and their realization in the IP-Glasma model. We present results for multiplicity distributions in p+p and p+A collisions and compare eccentricity distributions in A+A collisions to the flow harmonic distributions in 10 centrality classes measured by the ATLAS collaboration.

  11. High energy photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Zerwas, P.M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    1994-07-01

    The collisions of high energy photons produced at a electron-positron collider provide a comprehensive laboratory for testing QCD, electroweak interactions and extensions of the standard model. The luminosity and energy of the colliding photons produced by back-scattering laser beams is expected to be comparable to that of the primary e{sup +}e{sup {minus}} collisions. In this overview, we shall focus on tests of electroweak theory in photon-photon annihilation, particularly {gamma}{gamma} {yields} W{sup +}W{sup {minus}}, {gamma}{gamma} {yields} Higgs bosons, and higher-order loop processes, such as {gamma}{gamma} {yields} {gamma}{gamma}, Z{gamma} and ZZ. Since each photon can be resolved into a W{sup +}W{sup minus} pair, high energy photon-photon collisions can also provide a remarkably background-free laboratory for studying WW collisions and annihilation. We also review high energy {gamma}{gamma} tests of quantum chromodynamics, such as the scaling of the photon structure function, t{bar t} production, mini-jet processes, and diffractive reactions.

  12. Updated Vertical Extent of Collision Damage

    DEFF Research Database (Denmark)

    Tagg, R.; Bartzis, P.; Papanikolaou, P.;

    2002-01-01

    The probabilistic distribution of the vertical extent of collision damage is an important and somewhat controversial component of the proposed IMO harmonized damage stability regulations for cargo and passenger ships. The only pre-existing vertical distribution, currently used in the international...

  13. The evolution of runaway stellar collision products

    CERN Document Server

    Glebbeek, E; de Mink, S E; Pols, O R; Zwart, S F Portegies

    2009-01-01

    In the cores of young dense star clusters repeated stellar collisions involving the same object can occur, which has been suggested to lead to the formation of an intermediate-mass black hole. In order to verify this scenario we compute the detailed evolution of the merger remnant of three sequences. We follow the evolution until the onset of carbon burning and estimate the final remnant mass to determine the ultimate fate of a runaway merger sequence. We use a detailed stellar evolution code to follow the evolution of the collision product. At each collision, we mix the two colliding stars, taking account of mass loss during the collision. During the stellar evolution we apply mass loss rates from the literature, as appropriate for the evolutionary stage of the merger remnant. We compute models for high ($Z=0.02$) and low ($Z=0.001$) metallicity to quantify metallicity effects. We find that the merger remnant becomes a Wolf-Rayet star before the end of core hydrogen burning. Mass loss from stellar winds domi...

  14. THE PHYSICAL MECHANISM OF COLLISION BETWEEN SOLITONS

    Institute of Scientific and Technical Information of China (English)

    张卓; 唐翌; 颜晓红

    2001-01-01

    An easy and general way to access more complex soliton phenomena is introduced in this paper. The collisionprocess between two solitons of the KdV equation is investigated in great detail with this novel approach, which is different from the sophisticated method of inverse scattering transformation. A more physical and transparent picture describing the collision of solitons is presented.

  15. Fast Collision Attack on MD5

    NARCIS (Netherlands)

    Stevens, M.M.J.

    2006-01-01

    In this paper, we present an improved attack algorithm to find two-block collisions of the hash function MD5. The attack uses the same differential path of MD5 and the set of sufficient conditions that was presented by Wang et al. We present a new technique which allows us to deterministically fulfi

  16. Relativistic Hydrodynamics for Heavy-Ion Collisions

    Science.gov (United States)

    Ollitrault, Jean-Yves

    2008-01-01

    Relativistic hydrodynamics is essential to our current understanding of nucleus-nucleus collisions at ultrarelativistic energies (current experiments at the Relativistic Heavy Ion Collider, forthcoming experiments at the CERN Large Hadron Collider). This is an introduction to relativistic hydrodynamics for graduate students. It includes a detailed…

  17. LHC Report: LHC smashes collision records

    CERN Multimedia

    Sarah Charley

    2016-01-01

    The Large Hadron Collider is now producing more than a billion proton-proton collisions per second.   The LHC is colliding protons at a faster rate than ever before: approximately 1 billion times per second. Since April 2016, the LHC has delivered more than 30 inverse femtobarns (fb-1) to both ATLAS and CMS. This means that around 2.4 quadrillion (2.4 million billion) collisions have been seen by each of the experiments this year. The inverse femtobarn is the unit of measurement for integrated luminosity, indicating the cumulative number of potential collisions. This compares with the total of 33.2 fb-1 produced between 2010 and 2015. The unprecedented performance this year is the result of both the incremental increases in collision rate and the sheer amount of time the LHC has been up and running. This comes after a slow start-up in 2015, when scientists and engineers still needed to learn how to operate the machine at a much higher energy. “With more energy, the machine is much more sen...

  18. Efficient Collision Detection in a Simulated Hydrocyclone

    NARCIS (Netherlands)

    Eijkeren, van D.F.; Krebs, T.; Hoeijmakers, H.W.M.

    2015-01-01

    Hydrocyclones enhance oil–water separation efficiency compared to conventional separation methods. An efficient collision detection scheme with Np ln Np dependency on the number of particles is proposed. The scheme is developed to investigate the importance of particle–particle interaction for flow

  19. Quarkonium production in heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    Arnaldi Roberta

    2014-03-01

    Full Text Available The production of quarkonium states plays a crucial role among the probes to investigate the formation of the plasma of quarks and gluons (QGP in heavy-ion collisions. A review of the charmonium and bottomonium production, mainly focussing on the latest results from the LHC experiments, is presented.

  20. Elliptic flow at different collision stages

    NARCIS (Netherlands)

    Dubla, Andrea

    2016-01-01

    ALICE (A Large Ion Collider Experiment) is one of the four main experiments at the Large Hadron Collider (LHC) optimized for the study of heavy-ion collisions. The prime aim of the experiment is to study in detail the behaviour of nuclear matter at high densities and temperatures. In ALICE also prot

  1. Rapidity Correlation Structure in Nuclear Collisions

    Science.gov (United States)

    Zin, Christopher; Gavin, Sean; Moschelli, George

    2016-09-01

    The forces that drive the nuclear collision system towards local thermal equilibrium leave few observable traces. Heavy ion experiments report a range of features widely attributed to the hydrodynamic flow of a near-equilibrium quark gluon plasma. In particular, measurements of azimuthal anisotropy provide the most comprehensive support for the hydrodynamic description of these systems. In search of the source of this flow, we turned to smaller proton-proton, proton-nucleus and deuterium-nucleus collisions, expecting to find this effect absent. Instead, these collisions show an azimuthal anisotropy that is comparable to the larger ion-ion systems. How can we learn about the mechanisms that give rise to hydrodynamics if every available collision system exhibits flow? We show that measurements of the rapidity dependence of transverse momentum correlations can be used to determine the characteristic time τπ that dictates the rate of isotropization of the stress energy tensor, as well as the shear viscosity ν = η / sT . We formulate methods for computing these correlations using second order dissipative hydrodynamics with noise. Current data are consistent with τπ / ν 10 but targeted measurements can improve this precision. NSF PHY-1207687.

  2. Strangeness production in AA and pp collisions

    Energy Technology Data Exchange (ETDEWEB)

    Castorina, Paolo [Universita di Catania, Dipartimento di Fisica ed Astronomia, Catania (Italy); INFN, Catania (Italy); Satz, Helmut [Universitaet Bielefeld, Fakultaet fuer Physik, Bielefeld (Germany)

    2016-07-15

    Boost-invariant hadron production in high-energy collisions occurs in causally disconnected regions of finite space-time size. As a result, globally conserved quantum numbers (charge, strangeness, baryon number) are conserved locally in spatially restricted correlation clusters. Their size is determined by two time scales: the equilibration time specifying the formation of a quark-gluon plasma, and the hadronization time, specifying the onset of confinement. The expected values for these scales provide the theoretical basis for the suppression observed for strangeness production in elementary interactions (pp, e{sup +}e{sup -}) below LHC energies. In contrast, the space-time superposition of individual collisions in high-energy heavy-ion interactions leads to higher energy densities, resulting in much later hadronization and hence much larger hadronization volumes. This largely removes the causality constraints and results in an ideal hadronic resonance gas in full chemical equilibrium. In the present paper, we determine the collision energies needed for that; we also estimate when pp collisions reach comparable hadronization volumes and thus determine when strangeness suppression should disappear there as well. (orig.)

  3. Embedding initial data for black hole collisions

    CERN Document Server

    Romano, J D; Romano, Joseph D; Price, Richard H

    1994-01-01

    We discuss isometric embedding diagrams for the visualization of initial data for the problem of the head-on collision of two black holes. The problem of constructing the embedding diagrams is explicitly presented for the best studied initial data, the Misner geometry. We present a partial solution of the embedding diagrams and discuss issues related to completing the solution.

  4. Conservative discretization of the Landau collision integral

    CERN Document Server

    Hirvijoki, Eero

    2016-01-01

    We describe a density, momentum, and energy conserving discretization of the nonlinear Landau collision integral. Our algorithm is suitable for both the finite-element and discontinuous Galerkin methods and does not require structured meshes. The conservation laws for the discretization are proven algebraically and demonstrated numerically for an axially symmetric nonlinear relaxation problem.

  5. Positron production in collision of heavy nuclei

    CERN Document Server

    Khriplovich, I B

    2016-01-01

    We consider the electromagnetic production of positron in collision of slow heavy nuclei, with the simultaneously produced electron captured by one of the nuclei. The cross-section of the discussed process exceeds essentially the cross-section of $e^+e^-$ production.

  6. The way to collisions, step by step

    CERN Multimedia

    2009-01-01

    While the LHC sectors cool down and reach the cryogenic operating temperature, spirits are warming up as we all eagerly await the first collisions. No reason to hurry, though. Making particles collide involves the complex manoeuvring of thousands of delicate components. The experts will make it happen using a step-by-step approach.

  7. High energy nuclear collisions: Theory overview

    Indian Academy of Sciences (India)

    R J Fries

    2010-08-01

    We review some basic concepts of relativistic heavy-ion physics and discuss our understanding of some key results from the experimental program at the relativistic heavy-ion collider (RHIC). We focus in particular on the early time dynamics of nuclear collisions, some result from lattice QCD, hard probes and photons.

  8. Heavy quark production in pp collisions

    Energy Technology Data Exchange (ETDEWEB)

    McGaughey, P.L. [Los Alamos National Lab., NM (United States); Quack, E. [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany); Ruuskanen, P.V. [Univ. of Helsinki (Finland)]|[Univ. of Jyvaeskylae (Finland)] [and others

    1995-07-01

    A systematic study of the inclusive single heavy quark and heavy-quark pair production cross sections in pp collisions is presented for RHIC and LHC energies. We compare with existing data when possible. The dependence of the rates on the renormalization and factorization scales is discussed. Predictions of the cross sections are given for two different sets of parton distribution functions.

  9. Fan Affinity Laws from a Collision Model

    Science.gov (United States)

    Bhattacharjee, Shayak

    2012-01-01

    The performance of a fan is usually estimated using hydrodynamical considerations. The calculations are long and involved and the results are expressed in terms of three affinity laws. In this paper we use kinetic theory to attack this problem. A hard sphere collision model is used, and subsequently a correction to account for the flow behaviour…

  10. On wounded constituents in nuclear collisions

    CERN Document Server

    Bozek, Piotr; Rybczynski, Maciej

    2016-01-01

    In this talk we summarize the main results of our recent paper, Phys. Rev. C94, 014902, where we explore predictions of the wounded quark model for particle production and the properties of the initial state formed in ultra-relativistic collisions of atomic nuclei.

  11. Strangeness production in AA and pp collisions

    Science.gov (United States)

    Castorina, Paolo; Satz, Helmut

    2016-07-01

    Boost-invariant hadron production in high-energy collisions occurs in causally disconnected regions of finite space-time size. As a result, globally conserved quantum numbers (charge, strangeness, baryon number) are conserved locally in spatially restricted correlation clusters. Their size is determined by two time scales: the equilibration time specifying the formation of a quark-gluon plasma, and the hadronization time, specifying the onset of confinement. The expected values for these scales provide the theoretical basis for the suppression observed for strangeness production in elementary interactions ( pp , e^+e^- below LHC energies. In contrast, the space-time superposition of individual collisions in high-energy heavy-ion interactions leads to higher energy densities, resulting in much later hadronization and hence much larger hadronization volumes. This largely removes the causality constraints and results in an ideal hadronic resonance gas in full chemical equilibrium. In the present paper, we determine the collision energies needed for that; we also estimate when pp collisions reach comparable hadronization volumes and thus determine when strangeness suppression should disappear there as well.

  12. The quarkonium saga in heavy ion collisions

    CERN Document Server

    Tserruya, Itzhak

    2013-01-01

    J/psi suppression was proposed more than 25 years ago as an unambiguous signature for the formation of the Quark Gluon Plasma in relativistic heavy ion collisions. After intensive efforts, both experimental and theoretical, the quarkonium saga remains exciting, producing surprising results and not fully understood. This talk focuses on recent results on quarkonium production at RHIC and the LHC.

  13. Collisions of antiprotons with hydrogen molecular ions

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2009-01-01

    Time-dependent close-coupling calculations of the ionization and excitation cross section for antiproton collisions with molecular hydrogen ions are performed in an impact energy range from 0.5 keV to 10 MeV. The Born-Oppenheimer and Franck-Condon approximations as well as the impact parameter...

  14. Probability of Grounding and Collision Events

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup

    1996-01-01

    To quantify the risks involved in ship traffic, rational criteria for collision and grounding accidents have to be developed. This implies that probabilities as well as inherent consequences have to be analyzed and assessed.The present notes outline a method for evaluation of the probability...

  15. Probability of Grounding and Collision Events

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup

    1996-01-01

    To quantify the risks involved in ship traffic, rational criteria for collision and grounding accidents are developed. This implies that probabilities as well as inherent consequences can be analysed and assessed. The presnt paper outlines a method for evaluation of the probability of ship...

  16. Electron-Atom Collisions in Gases

    Science.gov (United States)

    Kraftmakher, Yaakov

    2013-01-01

    Electron-atom collisions in gases are an aspect of atomic physics. Three experiments in this field employing a thyratron are described: (i) the Ramsauer-Townsend effect, (ii) the excitation and ionization potentials of xenon and (iii) the ion-electron recombination after interrupting the electric discharge.

  17. The evolution of runaway stellar collision products

    NARCIS (Netherlands)

    Glebbeek, E.; Gaburov, E.; de Mink, S.E.; Pols, O.R.; Portegies Zwart, S.F.

    2009-01-01

    In the cores of young dense star clusters, repeated stellar collisions involving the same object can occur. It has been suggested that this leads to the formation of an intermediate-mass black hole. To verify this scenario we compute the detailed evolution of the merger remnant of three sequences, t

  18. Electromagnetic effects on meson production: a new tool for studying the space-time evolution of heavy ion collisions

    CERN Document Server

    Rybicki, Andrzej; Klusek-Gawenda, Mariola; Davis, Nikolaos; Ozvenchuk, Vitalii; Kielbowicz, Miroslaw

    2016-01-01

    We review our studies of spectator-induced electromagnetic (EM) effects on the emission of charged mesons in the final state of ultrarelativistic heavy ion collisions. We argue that these effects offer sensitivity to the distance $d_E$ between the charged meson formation zone at freeze-out and the spectator system. As such, the can serve as an independent, new tool to probe the space time evolution and longitudinal of the system created in the collision. As a phenomenological application for this tool in the context of resonance production and decay, we obtain a first estimate of the pion decoupling time from EM effects.

  19. Coastal river plumes: Collisions and coalescence

    Science.gov (United States)

    Warrick, Jonathan A.; Farnsworth, Katherine L.

    2017-02-01

    Plumes of buoyant river water spread in the ocean from river mouths, and these plumes influence water quality, sediment dispersal, primary productivity, and circulation along the world's coasts. Most investigations of river plumes have focused on large rivers in a coastal region, for which the physical spreading of the plume is assumed to be independent from the influence of other buoyant plumes. Here we provide new understanding of the spreading patterns of multiple plumes interacting along simplified coastal settings by investigating: (i) the relative likelihood of plume-to-plume interactions at different settings using geophysical scaling, (ii) the diversity of plume frontal collision types and the effects of these collisions on spreading patterns of plume waters using a two-dimensional hydrodynamic model, and (iii) the fundamental differences in plume spreading patterns between coasts with single and multiple rivers using a three-dimensional hydrodynamic model. Geophysical scaling suggests that coastal margins with numerous small rivers (watershed areas 100,000 km2). When two plume fronts meet, several types of collision attributes were found, including refection, subduction and occlusion. We found that the relative differences in pre-collision plume densities and thicknesses strongly influenced the resulting collision types. The three-dimensional spreading of buoyant plumes was found to be influenced by the presence of additional rivers for all modeled scenarios, including those with and without Coriolis and wind. Combined, these results suggest that plume-to-plume interactions are common phenomena for coastal regions offshore of the world's smaller rivers and for coastal settings with multiple river mouths in close proximity, and that the spreading and fate of river waters in these settings will be strongly influenced by these interactions. We conclude that new investigations are needed to characterize how plumes interact offshore of river mouths to better

  20. Molecular Dissociation Induced by Electron Collisions

    Science.gov (United States)

    Wolf, Andreas

    2009-05-01

    Free electrons can efficiently break molecules or molecular ions in low-energy collisions by the processes of dissociative recombination or attachment. These processes make slow electrons efficient chemical agents in many environments. For dissociative recombination, in particular, studies of the underlying reaction paths and mechanisms have become possible on a uniquely elementary level in recent years both for theory and experiment. On the experimental side, collisions can be prepared at resolved collision energies down to the meV (10 Kelvin) level, increasingly gaining control also over the initial molecular quantum level, and individual events are detected and kinematically analyzed by fast-beam coincidence fragment imaging. Experiments are reported from the ion cooler ring TSR in Heidelberg. Stored beams of molecular ions cooled in their external and internal degrees of freedom are collinearly merged with intense and cold electron beams from cryogenic GaAs photocathodes, recently shown to yield fast cooling of the center-of-mass motion also for heavy and correspondingly slow molecular ion beams. To reconstruct the molecular fragmentation events multiparticle imaging can now be used systematically with collision energies set a wide range, especially aiming at specific electron capture resonances. Thus, for CF^+ it is found that the electronic state of the C fragment (^3P or ^1D) switches resonantly when the collision energy is changed by only a small fraction. As a new powerful tool, an energy-sensitive multi-strip surface-barrier detector (EMU) has been set up to measure with near-unity efficiency the masses of all fragments together with their hit positions in high-multiplicity events. Among many uses, this device allows internal molecular excitations to be derived for individual chemical channels in polyatomic fragmentation. New results will be presented in particular on the breakup of the hydronium ion (D3O^+).

  1. Collision Tumor Composed of Meningioma and Cavernoma

    Science.gov (United States)

    Weigel, Jens; Neher, Markus; Schrey, Michael; Wünsch, Peter H.; Steiner, Hans-Herbert

    2017-01-01

    A true collision tumor is a rare entity composed of two histologically distinct neoplasms coinciding in the same organ. This paper reports a unique case of cerebral collision tumor consisting of two benign components. On the first hand, meningioma which is usually a benign lesion arising from the meningothelial cell in the arachnoidal membrane. On the other, cerebral cavernoma which is a well-circumscribed, benign vascular hamartoma within the brain. To our knowledge, there is no previously documented case of cerebral collision tumor consisting of two benign components. A 56-year-old Caucasian male suffered in 2002 from an atypical meningioma WHO II° located in the left lateral ventricle. Three years after the tumor extirpation, the patient suffered from a hematoma in the fourth ventricle due to a recurrently haemorrhaged cavernoma. In 2008, a recurrence of the tumor in the left lateral ventricle was discovered. Additionally, another tumor located in the quadrigeminal lamina was detected. After surgical resection of the tumor in the left lateral ventricle, the pathological examination confirmed the diagnosis of a collision tumor consisting of components of a meningioma WHO II° and a cavernoma. Postoperatively, no adjuvant treatment was needed and no tumor recurrence is discovered up to the present. A possible explanation for the collision of those two different tumors may be migration of tumor cells mediated by the cerebrospinal fluid. After 5-years of follow-up, there is no sign of any tumor recurrence; therefore, surgical tumor removal without adjuvant therapy seems to be the treatment of choice. PMID:28061500

  2. Studies of multiplicity in relativistic heavy-ion collisions

    CERN Document Server

    Back, B B; Alexa, C; Arnaldi, R; Atayan, M; Baglin, C; Baldit, A; Bedjidian, M; Beolè, S; Boldea, V; Bordalo,a, P; Borenstein, S R; Borges, G; Bussière, A; Capelli, L; Castanier, C; Castor, J I; Chaurand, B; Cheynis, B; Chiavassa, E; Cical, C; Claudino, T; Comets, M P; Constantinescu, S; Cortese, P; Cruz, J; De Falco, A; De Marco, N; Dellacasa, G; Devaux, A; Dita, S; Drapier, O; Espagnon, B; Fargeix, J; Force, P; Gallio, M; Gavrilov, Yu K; Gerschel, C; Giubellino,c, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grigorian, S; Grossiord, J Y; Guber, F F; Guichard, A; Gulkanian, H R; Hokobyan, R; Haroutunian, R; Idzik, M; Jouan, D; Karavitcheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; Macciotta, P; MacCormick, M; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, A; Pizzi, J R; Prado da Silva, W L; Prino, F; Puddu, G; Quintans, C; Ramello, L; Ramos,a, S; Rato-Mendes, P; Riccati, L; Romana, A; Santos, H; Saturnini, P; Scalas, E; Scomparin, E; Serci, S; Shahoyan, R; Sigaudo, F; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, E; Villatte, L; Willis, N; Wu, T

    2005-01-01

    In this talk I'll review the present status of charged particle multiplicity measurements from heavy-ion collisions. The characteristic features of multiplicity distributions obtained in Au+Au collisions will be discussed in terms of collision centrality and energy and compared to those of p+p collisions. Multiplicity measurements of d+Au collisions at 200 GeV nucleon-nucleon center-of-mass energy will also be discussed. The results will be compared to various theoretical models and simple scaling properties of the data will be identified.

  3. Properties of the Collision Efficiency of Nanoparticles in Brownian Coagulation

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-Ming; LIN Jian-Zhong; CHEN Zhong-Li

    2011-01-01

    The collision efficiency of nanoparticles with diameters from 100 nm to 750nm in the Brownian coagulation is studied by building and solving numerically the equations of particle collision in the presence of the van der Waals force, the elastic deformation force, the Stokes resistance, the lubrication force and the electrostatic force. The results show that the collision efficiency decreases overall with the increasing particle diameter. It is found that there exists an abrupt increase in the collision efficiency when the particle diameter is equals to 550 nm. Finally a new expression for the collision efficiency is presented.

  4. Total Probability of Collision as a Metric for Finite Conjunction Assessment and Collision Risk Management

    Science.gov (United States)

    Frigm, R.; Johnson, L.

    The Probability of Collision (Pc) has become a universal metric and statement of on-orbit collision risk. Although several flavors of the computation exist and are well-documented in the literature, the basic calculation requires the same input: estimates for the position, position uncertainty, and sizes of the two objects involved. The Pc is used operationally to make decisions on whether a given conjunction poses significant collision risk to the primary object (or space asset of concern). It is also used to determine necessity and degree of mitigative action (typically in the form of an orbital maneuver) to be performed. The predicted post-maneuver Pc also informs the maneuver planning process into regarding the timing, direction, and magnitude of the maneuver needed to mitigate the collision risk. Although the data sources, techniques, decision calculus, and workflows vary for different agencies and organizations, they all have a common thread. The standard conjunction assessment and collision risk concept of operations (CONOPS) predicts conjunctions, assesses the collision risk (typically, via the Pc), and plans and executes avoidance activities for conjunctions as a discrete events. As the space debris environment continues to increase and improvements are made to remote sensing capabilities and sensitivities to detect, track, and predict smaller debris objects, the number of conjunctions will in turn continue to increase. The expected order-of-magnitude increase in the number of predicted conjunctions will challenge the paradigm of treating each conjunction as a discrete event. The challenge will not be limited to workload issues, such as manpower and computing performance, but also the ability for satellite owner/operators to successfully execute their mission while also managing on-orbit collision risk. Executing a propulsive maneuver occasionally can easily be absorbed into the mission planning and operations tempo; whereas, continuously planning evasive

  5. Multiple Cosmic Collisions and the Microwave Background Power Spectrum

    CERN Document Server

    Kozaczuk, Jonathan

    2012-01-01

    Collisions between cosmic bubbles of different vacua are a generic feature of false vacuum eternal inflation scenarios. While previous studies have focused on the consequences of a single collision event in an observer's past, we begin here an investigation of the more general scenario allowing for many "mild" collisions intersecting our past light cone (and one another). We discuss the general features of multiple collision scenarios and consider their impact on the cosmic microwave background (CMB) temperature power spectrum, treating the collisions perturbatively. In a large class of models, one can approximate a multiple collision scenario as a superposition of individual collision events governed by nearly isotropic and scale-invariant distributions, most appearing to take up less than half of the sky. In this case, the shape of the expected CMB temperature spectrum maintains statistical isotropy and typically features a dramatic increase in power in the low multipoles relative to that of the best-fit $\\...

  6. Hybrid Collision Detection Algorithm based on Image Space

    Directory of Open Access Journals (Sweden)

    XueLi Shen

    2013-07-01

    Full Text Available Collision detection is an important application in the field of virtual reality, and efficiently completing collision detection has become the research focus. For the poorly real-time defect of collision detection, this paper has presented an algorithm based on the hybrid collision detection, detecting the potential collision object sets quickly with the mixed bounding volume hierarchy tree, and then using the streaming pattern collision detection algorithm to make an accurate detection. With the above methods, it can achieve the purpose of balancing load of the CPU and GPU and speeding up the detection rate. The experimental results show that compared with the classic Rapid algorithm, this algorithm can effectively improve the efficiency of collision detection.

  7. Apports et limites du marquage individuel dans la connaissance de l'écobiologie du chevaine (Leuciscus cephalus

    Directory of Open Access Journals (Sweden)

    LE LOUARN H.

    1997-04-01

    Full Text Available Depuis 1991, des marquages individuels ont été effectués sur des chevaines (Leuciscus cephalus de la rivière Boutonne, affluent de la Charente, afin d'améliorer les connaissances écobiologiques de l'espèce qui restent très fragmentaires pour les populations atlantiques françaises. 718 individus, de taille supérieure à 120 mm, ont été capturés par pêche électrique sur un secteur de 2,7 km, lors de la période de reproduction (mi-juin, et marqués essentiellement par marque nouille (5 années mais également par implant visible (une année durant cinq ans. Au total, 162 poissons ont été recapturés et certains individus plusieurs fois au cours de la période d'étude. L'analyse des résultats fait ressortir que : - Seuls deux poissons marqués par implant visible ont été recapturés (0,9 % ; le taux moyen de recapture des individus marqués par marque nouille a été de 22,3 % mais a varié selon l'année et l'état de maturité du poisson (de 6,6 à 37,7 % ; il apparaît plus faible pour les immatures (6,4 % que pour les géniteurs (25,2 % et reste identique chez les deux sexes. - La méthode de capture-recapture a permis de valider l'estimation de l'âge et de la croissance par scalimétrie : définition de la marque hivernale ; existence d'une chronologie de l'apparition de l'anneau hivernal et donc de la reprise de croissance ; validation de la régression reliant la longueur du poisson à celle de son écaille pour la population étudiée. - Les déplacements à l'intérieur du secteur étudié sont faibles et les femelles montrent une grande fidélité à leur site de reproduction. - Le marquage par marque nouille entraîne un déficit de croissance, principalement chez les poissons de plus de cinq ans ; ce déficit semble se réduire dès la deuxième année suivant le marquage. La discussion des résultats montre qu'en dépit de certains facteurs limitants, l'utilisation de cette technique de marquage individuel appara

  8. LightForce Photon-Pressure Collision Avoidance: Efficiency Assessment on an Entire Catalogue of Space Debris

    Science.gov (United States)

    Stupl, J.; Faber, N.; Foster, C.; Yang, F.; Levit, C.

    2013-09-01

    The potential to perturb debris orbits using photon pressure from ground-based lasers has been confirmed by independent research teams. Useful applications of this scheme are protecting space assets from impacts with debris and stabilizing the orbital debris environment, both relying on collision avoidance rather than de-orbiting debris. This paper presents the results of a new assessment method to analyze the efficiency of the concept. Earlier research concluded that one ground based system consisting of a 10 kW class laser, directed by a 1.5 m telescope with adaptive optics, can avoid a significant fraction of debris-debris collisions in low Earth orbit. That research used in-track displacement to measure efficiency and restricted itself to an analysis of a limited number of objects. As orbit prediction error is dependent on debris object properties, a static displacement threshold should be complemented with another measure to assess the efficiency of the scheme. In this paper we present the results of an approach using probability of collision. Using a least-squares fitting method, we improve the quality of the original TLE catalogue in terms of state and co-state accuracy. We then calculate collision probabilities for all the objects in the catalogue. The conjunctions with the highest risk of collision are then engaged by a simulated network of laser ground stations. After those engagements, the perturbed orbits are used to re-assess the collision probability in a 24h window around the original conjunction. We then use different criteria to evaluate the utility of the laser based collision avoidance scheme and assess the number of base-line ground stations needed to mitigate a significant number of high probability conjunctions. Finally, we also give an account how a laser ground station can be used for both orbit deflection and debris tracking.

  9. The chronology of the India-Asia collision

    Science.gov (United States)

    Garzanti, Eduardo; Hu, Xiumian

    2016-04-01

    Markedly diverging interpretations and incompatible scenarios have been proposed for the early stages of the Himalayan Orogeny. One view is that the northern Indian passive margin may have been involved in ophiolite obduction, arc-continent, or continent-continent collision as early as the Late Cretaceous. A different view is that India may have not come into contact with Asia until as late as the Oligo-Miocene. Ages assigned to the India-Asia collision have thus ranged rather freely from as old as 70 Ma to as young as 25-20 Ma, allowing researchers to select in remarkable liberty the age that fitted best with their lines of reasoning. In recent years, however, a growing body of stratigraphic evidence has constrained the chronology of collision with increasing accuracy and precision. Provenance analysis has ruled out early collision or ophiolite-obduction hypotheses, indicating that renewed terrigenous supply in the Maastrichtian to Danian (72-62 Ma) was derived from India in the south - rejuvenated by magmatic upwelling during the Deccan event - rather than from Asia or from an obducting ophiolite in the north (Garzanti and Hu, 2015). Integrated biostratigraphy and detrital-zircon chronostratigraphy has demonstrated that the first continent-continent contact and consequent disappearance of Neotethyan oceanic lithosphere at one point in south Tibet took place in the Selandian (59 ± 1 Ma; DeCelles et al., 2014; Wu et al., 2014; Hu et al., 2015). A major disconformity documenting tectonic uplift of carbonate platforms all along the Tethys Himalaya from the Gamba and Tingri areas of south Tibet to the Zanskar Range of the NW Himalaya, allowed dating the arrival of the orogenic wave in the inner part of the northern Indian passive margin around the Paleocene/Eocene boundary (ca. 56 Ma; Garzanti et al., 1987; Li et al., 2015). Shallow-marine seaways linked with Neotethys persisted in the Himalaya until the mid-Ypresian (ca. 50 Ma), when they were finally filled by

  10. The Cocos Ridge drives collision of Panama with northwestern South America

    Science.gov (United States)

    LaFemina, Peter; Govers, Rob; Mora-Paez, Hector; Geirsson, Halldor; Cmacho, Eduardo

    2015-04-01

    The collision of the Panamanian isthmus with northwestern South America is thought to have initiated as early as Oligocene - Miocene time (23-25 Ma) based on geologic and geophysical data and paleogeographic reconstructions. This collision was driven by eastward-directed subduction beneath northwestern South America. Cocos - Caribbean convergence along the Middle America Trench, and Nazca - Caribbean oblique convergence along the South Panama Deformed Belt have resulted in complex deformation of the southwestern Caribbean since Miocene - Pliocene time. Subduction and collision of the aseismic Cocos Ridge is thought to have initiated volcanism and uplift of the Cordillera de Talamanca; 2) Quaternary migration of the volcanic arc toward the back-arc; 3) Quaternary to present deformation within the Central Costa Rica Deformed Belt; 4) Quaternary to present shortening across the fore-arc Fila Costeña fold and thrust belt and back-arc North Panama Deformed Belt (NPDB); 5) Quaternary to present outer fore-arc uplift of Nicoya Peninsula above the seamount domain, and the Osa and Burica peninsulas above the ridge; and 6) Pleistocene to present northwestward motion of the Central American Fore Arc (CAFA) and northeastward motion of the Panama Region. We investigate the geodynamic effects of Cocos Ridge collision on motion of the Panama Region with a new geodynamic model. The model is compared to a new 1993-2015 GPS-derived three-dimensional velocity field for the western Caribbean and northwestern South America. Specifically, we test the hypotheses that the Cocos Ridge is the main driver for upper plate deformation in the western Caribbean. Our models indicate that Cocos Ridge collision drives northwest-directed motion of the CAFA and the northeast-directed motion of the Panama Region. The Panama Region is driven into the Caribbean across the NPDB and into northwestern South America, which is also converging with the Panama Region, pushing it toward the west

  11. Initial Temperature and Extent of Chemical Equilibration of Partons in Relativistic Collision of Heavy Nuclei

    CERN Document Server

    Srivastava, Dinesh K; Mustafa, Munshi G

    2016-01-01

    We emphasize that a knowledge of energy and entropy densities of quark gluon plasma - a thermalized de-confined matter, formed in relativistic heavy ion collisions fixes the formation temperature and the product of gluon fugacity and formation time uniquely, {\\em provided} we know the relative fugacities of quarks and gluons. This also provides that a smaller formation time would imply larger fugacities for partons. Next we explore the limits of chemical equilibration of partons during the initial stages in relativistic collision of heavy nuclei. The experimentally measured rapidity densities of transverse energy and charged particle multiplicity at RHIC and LHC energies are used to estimate the energy and number densities with the assumption of formation of a thermally equilibrated quark gluon plasma which may be chemically equilibrated to the same or differing extents for quarks and gluons. The estimates are found to be very sensitive to the correction factor used for the Bj\\"{o}rken energy density for iden...

  12. Assessment and Mitigation of the Proton-Proton Collision Debris Impact on the FCC Triplet

    CERN Document Server

    Besana, Maria Ilaria; Fartoukh, Stephane; Martin, Roman; Tomás, Rogelio

    2016-01-01

    The Future Circular hadron Collider (FCC-hh), which is designed to operate at a centre-of-mass energy of 100 TeV and to deliver ambitious targets in terms of both instantaneous and integrated luminosity, poses extreme challenges in terms of machine protection during operation and with respect to long-term damages. Energy deposition studies are a crucial ingredient for its design. One of the relevant radiation sources are collision debris particles, which de- posit their energy in the interaction region elements and in particular in the superconducting magnet coils of the final focus triplet quadrupoles, to be protected from the risk of quenching and deterioration. In this contribution, the collision debris will be characterised and expectations obtained with FLUKA will be presented, including magnet lifetime considerations. New techniques including crossing angle gymnastics for peak dose deposition mitigation (as recently introduced in the framework of the LHC operation), will be discussed.

  13. Long-range consequences of interplanetary collisions

    Science.gov (United States)

    Sagan, Carl; Ostro, Steven J.

    1994-01-01

    As Comet Shoemaker-Levy 9 races toward its mid-July collision with the planet Jupiter, considerable public attention is focused on catastrophic impacts with the Earth -- in the past and in the future. In recent years calls have been made to develop technologies that could deflect any asteroid or comet on a collision course. Careful consideration must be given to the nature and time scale of the risk and to the cost-effectiveness and possible problems in the suggested solutions. Risk assessment, threat removal, and resources misuse are examined. The greatest concern is to have a poorly informed public -- exerting pressure for means to mitigate even non-existent threats. The only foreseeable solution is a combination of accurate orbit estimation, realistic threat assessment, and effective public education.

  14. Strangeness Production in AA and pp Collisions

    CERN Document Server

    Satz, P Castorina ad H

    2016-01-01

    Boost-invariant hadron production in high energy collisions occurs in causally disconnected regions of finite space-time size. As a result, globally conserved quantum numbers (charge, strangeness, baryon number) are conserved locally in spatially restricted correlation clusters. Their size is determined by two time scales: the equilibration time specifying the formation of a quark-gluon plasma, and the hadronization time, specifying the onset of confinement. The expected values for these scales provide the theoretical basis for the suppression observed for strangeness production in elementary interactions ($pp$, $e^+e^-$) below LHC energies. In contrast, the space-time superposition of individual collisions in high energy heavy ion interactions leads to higher energy densities, resulting in much later hadronization and hence much larger hadronization volumes. This largely removes the causality constraints and results in an ideal hadronic resonance gas in full chemical equilibrium. In the present paper, we det...

  15. Theory of Electron-Ion Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Donald C

    2009-10-02

    Collisions of electrons with atoms and ions play a crucial role in the modeling and diagnostics of fusion plasmas. In the edge and divertor regions of magnetically confined plasmas, data for the collisions of electrons with neutral atoms and low charge-state ions are of particular importance, while in the inner region, data on highly ionized species are needed. Since experimental measurements for these collisional processes remain very limited, data for such processes depend primarily on the results of theoretical calculations. Over the period of the present grant (January 2006 - August 2009), we have made additional improvements in our parallel scattering programs, generated data of direct fusion interest and made these data available on The Controlled Fusion Atomic Data Center Web site at Oak Ridge National Laboratory. In addition, we have employed these data to do collsional-radiative modeling studies in support of a variety of experiments with magnetically confined fusion plasmas.

  16. Positronium collisions with rare-gas atoms

    CERN Document Server

    Gribakin, G F; Wilde, R S; Fabrikant, I I

    2015-01-01

    We calculate elastic scattering of positronium (Ps) by the Xe atom using the recently developed pseudopotential method [Fabrikant I I and Gribakin G F 2014 Phys. Rev. A 90 052717] and review general features of Ps scattering from heavier rare-gas atoms: Ar, Kr and Xe. The total scattering cross section is dominated by two contributions: elastic scattering and Ps ionization (break-up). To calculate the Ps ionization cross sections we use the binary-encounter method for Ps collisions with an atomic target. Our results for the ionization cross section agree well with previous calculations carried out in the impulse approximation. Our total Ps-Xe cross section, when plotted as a function of the projectile velocity, exhibits similarity with the electron-Xe cross section for the collision velocities higher than 0.8 a.u., and agrees very well with the measurements at Ps velocities above 0.5 a.u.

  17. The CLIC Post-Collision Line

    CERN Document Server

    Gschwendtner, E; Elsener, K; Sailer, A; Uythoven, J; Appleby, R B; Salt, M; Ferrari, A; Ziemann, V

    2010-01-01

    The 1.5 TeV CLIC beams, with a total power of 14 MW per beam, are disrupted at the interaction point due to the very strong beam-beam effect. As a result, some 3.5 MW reach the main dump in form of beamstrahlung photons. About 0.5 MW of e+e- pairs with a very broad energy spectrum need to be disposed of along the post-collision line. The conceptual design of this beam line will be presented. Emphasis will be on the optimization studies of the CLIC post-collision line design with respect to the energy deposition in windows, dumps and absorbers, on the design of the luminosity monitoring for a fast feedback to the beam steering and on the background conditions for the luminosity monitoring equipment.

  18. CLIC Post-Collision Line Luminosity Monitoring

    CERN Document Server

    Appleby, R B; Deacon, L; Geschwendtner, E

    2011-01-01

    The CLIC post collision line is designed to transport the un-collided beams and the products of the collided beams with a total power of 14MW to the main beam dump. Full Monte Carlo simulation has been done for the description of the CLIC luminosity monitoring in the post collision line. One method of the luminosity diagnostic is based on the detection of high energy muons produced by beamstrahlung photons in the main beam dump. The disrupted beam and the beamstrahlung photons produce at the order of 106 muons per bunch crossing per cm2, with energies higher than 10 GeV. Threshold Cherenkov counters are considered after the beam dump for the detection of these high energy muons. Another method for luminosity monitoring is presented using the direct detection of the beamstrahlung photons.

  19. Inelastic collisions of excited lithium molecules

    Science.gov (United States)

    Rosenberry, Mark; Marhatta, Ramesh; Stewart, Brian

    2010-03-01

    Energy transfer and reactions during molecular collisions are fundamental processes in astronomy and chemistry. The H2 + H system has been well studied, and theoretical calculations are now becoming feasible for an excited lithium dimer colliding with a ground state lithium atom, increasing interest in corresponding experimental measurements. Our laboratory observes laser-induced fluorescence spectra from lithium vapor in a heat pipe oven. Our recent switch from a modest diode laser to a pulsed dye laser gives us new access to a variety of highly excited molecular states. Here we report our progress in measuring absolute level-to-level rate constants and collision-induced dissociation for molecular states of this system.

  20. Axion bremsstrahlung from collisions of global strings

    CERN Document Server

    Galtsov, D V; Kerner, R

    2003-01-01

    We calculate axion radiation emitted in the collision of two straight global strings. The strings are supposed to be in the unexcited ground state, to be inclined with respect to each other, and to move in parallel planes. Radiation arises when the point of minimal separation between the strings moves faster than light. This effect exhibits a typical Cerenkov nature. Surprisingly, it allows an alternative interpretation as bremsstrahlung under a collision of point charges in 2+1 electrodynamics. This can be demonstrated by suitable world-sheet reparameterizations and dimensional reduction. Cosmological estimates show that our mechanism generates axion production comparable with that from the oscillating string loops and may lead to further restrictions on the axion window.

  1. Path Integral Approach to Atomic Collisions

    Science.gov (United States)

    Harris, Allison

    2016-09-01

    The Path Integral technique is an alternative formulation of quantum mechanics that is based on a Lagrangian approach. In its exact form, it is completely equivalent to the Hamiltonian-based Schrödinger equation approach. Developed by Feynman in the 1940's, following inspiration from Dirac, the path integral approach has been widely used in high energy physics, quantum field theory, and statistical mechanics. However, only in limited cases has the path integral approach been applied to quantum mechanical few-body scattering. We present a theoretical and computational development of the path integral method for use in the study of atomic collisions. Preliminary results are presented for some simple systems. Ultimately, this approach will be applied to few-body ion-atom collisions. Work supported by NSF grant PHY-1505217.

  2. High energy particle collisions near black holes

    Directory of Open Access Journals (Sweden)

    Zaslavskii O. B.

    2016-01-01

    Full Text Available If two geodesic particles collide near a rotating black hole, their energy in the centre of mass frame Ec.m. can become unbound under certain conditions (the so-called BSW effect. The special role is played here by so-called critical geodesics when one of particles has fine-tuned energy and angular momentum. The nature of geodesics reveals itself also in fate of the debris after collisions. One of particles moving to a remote observer is necessarily near-critical. We discuss, when such a collision can give rise not only unboud Ec.m. but also unbound Killing energy E (so-called super-Penrose process.

  3. Holography, Hydrodynamization and Heavy-Ion Collisions

    CERN Document Server

    Heller, Michal P

    2016-01-01

    In the course of the past several years holography has emerged as an ab initio tool in exploring strongly-time-dependent phenomena in gauge theories. These lecture notes overview recent developments in this area driven by phenomenological questions concerning applicability of hydrodynamics under extreme conditions occurring in ultrarelativistic heavy-ion collisions at RHIC and LHC. The topics include equilibration time scales, holographic collisions and hydrodynamization from the point of view of the asymptotic character of the hydrodynamic gradient expansion. The emphasis is put on concepts rather than calculational techniques and particular attention is devoted to present these developments in the context of the most recent advances and some of the open problems.

  4. Electron collisions with coherently prepared atomic targets

    Energy Technology Data Exchange (ETDEWEB)

    Trajmar, S.; Kanik, I.; LeClair, L.R.; Khakoo, M.S. [California Inst. of Tech., Pasadena, CA (United States). Jet Propulsion Lab.; Bray, I.; Fursa, D. [Flinders Univ. of South Australia, Adelaide (Australia). Electronics Structure of Materials Centre; Csanak, G. [Los Alamos National Lab., NM (United States)

    1998-02-01

    The subject of electron scattering by laser-excited atoms is briefly reviewed. To demonstrate some aspects of these electron collision processes, the authors describe the procedures and the results of a joint experimental and theoretical study concerning elastic scattering by coherently excited {sup 138}Ba (...6s6p {sup 1}P{sub 1}) atoms. Examples of experimental and theoretical collision parameters and magnetic sublevel differential cross sections for elastic scattering are given and compared. The convergent close coupling calculations (with the neglect of spin-orbit interaction) are in good agreement with experiment at 20 eV impact energy and 10, 15 and 20{degree} scattering angles and can be expected to yield reliable integral magnetic sublevel and alignment creation cross sections. The role of these quantities in plasma polarization spectroscopy is pointed out.

  5. Transplanckian Collisions at the LHC and Beyond

    CERN Document Server

    Giudice, Gian Francesco; Wells, J D; Giudice, Gian F.; Rattazzi, Riccardo; Wells, James D.

    2002-01-01

    Elastic collisions in the transplanckian region, where the center-of-mass energy is much larger than the fundamental gravity mass scale, can be described by linearized general relativity and known quantum-mechanical effects as long as the momentum transfer of the process is sufficiently small. For larger momentum transfer, non-linear gravitational effects become important and, although a computation is lacking, black-hole formation is expected to dominate the dynamics. We discuss how elastic transplanckian collisions can be used at high-energy colliders to study, in a quantitative and model-independent way, theories in which gravity propagates in flat extra dimensions. At LHC energies, however, incalculable quantum-gravity contributions may significantly affect the experimental signal.

  6. Oscillating collision of the granular chain on static wall

    Science.gov (United States)

    Ma, Liang; Huang, Decai; Chen, Weizhong; Jiao, Tengfei; Sun, Min; Hu, Fenglan; Su, Jiaye

    2017-02-01

    Collision of the granular chain on static wall is investigated by discrete element method. Collision time and traveling time are proposed on the basis of the characteristics of the collision of a single grain with a wall and the propagation of interaction force wave in a granular chain to explain the collision process. Simulation results show that an oscillating collision force is generated when the force waves successively arrive at the wall. For the collision of a mono-dispersed chain, the simulation data are in good agreement with the predicted relationship between the maximum chain length of nmax and the first maximum collision force FA. Rigid wall and soft wall are defined as nmax = 1 and nmax ≥ 2, respectively. Two similar processes of oscillating collisions occur when a light or a heavy impure grain is introduced. In these processes, two maximum collision forces, namely, FA and FB, are observed, respectively. The simulation results about the influence of the mass and position of light impure grain on the collision force FB further confirm our theoretical predictions.

  7. Three-body collision contributions to recombination and collision-induced dissociation. 1: Cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Pack, R.T.; Walker, R.B.; Kendrick, B.K.

    1998-04-10

    Atomic and molecular recombination and collision-induced dissociation (CID) reactions comprise two of the most fundamental types of chemical reactions. They are important in all gas phase chemistry; for example, about half of the 196 reactions identified as important in combustion chemistry are recombination or CID reactions. Many of the current chemical kinetics textbooks and kinetics papers treat atomic and molecular recombination and CID as occurring only via sequences of two-body collisions. Actually, there is considerable evidence from experiment and classical trajectory calculations for contributions by true three-body collisions to the recombination of atomic and diatomic radicals, and that evidence is reviewed. Then, an approximate quantum method treating both two-body and three-body collisions simultaneously and on equal footing is used to calculate cross sections for the reaction Ne{sub 2} + H {rightleftharpoons} Ne + Ne + H. The results provide clear quantum evidence that direct three-body collisions do contribute significantly to recombination and CID.

  8. Crash and burn? Vehicle, collision, and driver factors that influence motor vehicle collision fires.

    Science.gov (United States)

    Bunn, T L; Slavova, S; Robertson, M

    2012-07-01

    A retrospective population-based case-control study was performed to determine the association between vehicle fires, and vehicle, collision, and driver factors on highways with a posted speed limit of at least 55mph. Data were obtained from the Kentucky Collision Report Analysis for Safer Highways (CRASH) electronic files for 2000-2009 from the Kentucky State Police Records Sections. The results from the final multiple logistic regression show that large trucks were at a higher risk for a collision involving a fire than passenger vehicles and pickup trucks. When controlling for all other variables in the model, vehicles 6 years old and older, driving straight down the highway, and single vehicle collisions were also identified as factors that increase the risk of motor vehicle collision fires on roadways with a posted speed limit of ≥55mph. Of the 2096 vehicles that caught fire, there were 632 (30%) non-fatally injured drivers and 224 (11%) fatally injured drivers. The results of this study have the potential to inform public health messages directed to the transportation industry, particularly semi truck drivers, in regard to fire risk.

  9. Evolution of stellar collision products in open clusters. II. A grid of low-mass collisions

    CERN Document Server

    Glebbeek, E

    2008-01-01

    In a companion paper we studied the detailed evolution of stellar collision products that occurred in an $N$-body simulation of the old open cluster M67 and compared our detailed models to simple prescriptions. In this paper we extend this work by studying the evolution of the collision products in open clusters as a function of mass and age of the progenitor stars. We calculated a grid of head-on collisions covering the section of parameter space relevant for collisions in open clusters. We create detailed models of the merger remnants using an entropy-sorting algorithm and follow their subsequent evolution during the initial contraction phase, through the main sequence and up to the giant branch with our detailed stellar evolution code. We compare the location of our models in a colour-magnitude diagram to the observed blue straggler population of the old open clusters M67 and NGC 188 and find that they cover the observed blue straggler region of both clusters. For M67, collisions need to have taken place r...

  10. Direct photons in heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Baeuchle, Bjoern

    2010-12-13

    Direct photon emission from heavy-ion collisions has been calculated and compared to available experimental data. Three different models have been combined to extract direct photons from different environments in a heavy-ion collision: Thermal photons from partonic and hadronic matter have been extracted from relativistic, non-viscous 3+1-dimensional hydrodynamic calculations. Thermal and non-thermal photons from hadronic interactions have been calculated from relativistic transport theory. The impact of different physics assumptions about the thermalized matter has been studied. The models used for the determination of photons from both hydrodynamic and transport calculations have been elucidated and their numerical properties tested. The origin of direct photons, itemised by emission stage, emission time, channel and baryon number density, has been investigated for various systems, as have the transverse momentum spectra and elliptic flow patterns of direct photons. Taking into account the full (vacuum) spectral function of the rho-meson decreases the direct photon emission by approximately 10% at low photon transverse momentum. In all systems that have been considered -- heavy-ion collisions at E{sub lab}=35 AGeV and 158 AGeV, (s{sub NN}){sup 1/2}=62.4 GeV, 130 GeV and 200 GeV -- thermal emission from a system with partonic degrees of freedom is greatly enhanced over that from hadronic systems, while the difference between the direct photon yields from a viscous and a non-viscous hadronic system (transport vs. hydrodynamics) is found to be very small. Predictions for direct photon emission in central U+U-collisions at 35 AGeV have been made. (orig.)

  11. Optically controlled collisions of biological objects

    Science.gov (United States)

    Davies, Benjamin J.; Kishore, Rani; Mammen, Mathai; Helmerson, Kristian; Choi, Seok-Ki; Phillips, William D.; Whitesides, George M.

    1998-04-01

    We have developed a new assay in which two mesoscale particles are caused to collide using two independently controlled optical tweezers. This assay involves the measurement of the adhesion probability following a collision. Since the relative orientation, impact parameter (i.e., distance of closest approach), and collision velocity of the particles, as well as the components of the solution, are all under the user's control, this assay can mimic a wide range of biologically relevant collisions. We illustrate the utility of our assay by evaluating the adhesion probability of a single erythrocyte (red blood cell) to an influenza virus-coated microsphere, in the presence of sialic acid-bearing inhibitors of adhesion. This probability as a function of inhibitor concentration yields a measure of the effectiveness of the inhibitor for blocking viral adhesion. Most of the inhibition constants obtained using the tweezers agree well with those obtained from other techniques, although the inhibition constants for the best of the inhibitors were beyond the limited resolution of conventional assays. They were readily evaluated using our tweezers-based assay, however, and prove to be the most potent inhibitors of adhesion between influenza virus and erythrocytes ever measured. Further studies are underway to investigate the effect of collision velocity on the adhesion probability, with the eventual goal of understanding the various mechanisms of inhibition (direct competition for viral binding sites versus steric stabilization). Analysis of these data also provide evidence that the density of binding sites may be a crucial parameter in the application of this assay and polymeric inhibition in general.

  12. Cross Sections for Electron Collisions with Methane

    Energy Technology Data Exchange (ETDEWEB)

    Song, Mi-Young, E-mail: mysong@nfri.re.kr; Yoon, Jung-Sik [Plasma Technology Research Center, National Fusion Research Institute, 814-2 Osikdo-dong, Gunsan, Jeollabuk-do 573-540 (Korea, Republic of); Cho, Hyuck [Department of Physics, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Itikawa, Yukikazu [Institute of Space and Astronautical Science, Sagamihara 252-5210 (Japan); Karwasz, Grzegorz P. [Faculty of Physics, Astronomy and Applied Informatics, University Nicolaus Copernicus, Grudziadzka 5, 87100 Toruń (Poland); Kokoouline, Viatcheslav [Department of Physics, University of Central Florida, Orlando, Florida 32816 (United States); Nakamura, Yoshiharu [6-1-5-201 Miyazaki, Miyamae, Kawasaki 216-0033 (Japan); Tennyson, Jonathan [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2015-06-15

    Cross section data are compiled from the literature for electron collisions with methane (CH{sub 4}) molecules. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational and vibrational states, dissociation, ionization, and dissociative attachment. The data derived from swarm experiments are also considered. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed through early 2014.

  13. Collisions of planetesimals and formation of planets

    CERN Document Server

    Dvorak, Rudolf; Süli, Áron; Schäfer, Christoph M; Speith, Roland; Burger, Christoph

    2015-01-01

    We present preliminary results of terrestrial planet formation using on the one hand classical numerical integration of hundreds of small bodies on CPUs and on the other hand -- for comparison reasons -- the results of our GPU code with thousands of small bodies which then merge to larger ones. To be able to determine the outcome of collision events we use our smooth particle hydrodynamics (SPH) code which tracks how water is lost during such events.

  14. Collisions of Planetesimals and Formation of Planets

    Science.gov (United States)

    Dvorak, Rudolf; Maindl, Thomas I.; Süli, Áron; Schäfer, Christoph M.; Speith, Roland; Burger, Christoph

    2016-01-01

    We present preliminary results of models of terrestrial planet formation using on the one hand classical numerical integration of hundreds of small bodies on CPUs and on the other hand-for comparison-the results of our GPU code with thousands of small bodies which then merge to larger ones. To be able to determine the outcome of collision events we use our smooth particle hydrodynamics (SPH) code which tracks how water is lost during such events.

  15. b-flavour tagging in pp collisions

    CERN Multimedia

    Birnkraut, Alex

    2015-01-01

    An essential ingredient of all time-dependent CP violation studies of B mesons is the ability to tag the initial flavour of the B meson. The harsh environment of 7 and 8 TeV pp collisions makes this a particularly difficult enterprise. We report progresses in the flavour tagging of B0 and Bs mesons, including developments of novel techniques like the use of an opposite side charm tagger.

  16. Mobile Robot Collision Avoidance in Human Environments

    OpenAIRE

    Lingqi Zeng; Gary M. Bone

    2013-01-01

    Collision avoidance is a fundamental requirement for mobile robots. Avoiding moving obstacles (also termed dynamic obstacles) with unpredictable direction changes, such as humans, is more challenging than avoiding moving obstacles whose motion can be predicted. Precise information on the future moving directions of humans is unobtainable for use in navigation algorithms. Furthermore, humans should be able to pursue their activities unhindered and without worrying about the robots around them....

  17. Studying Proton-Proton Collisions Using Pythia

    Science.gov (United States)

    Zolotov, Adi

    2004-10-01

    At Brookhaven National Lab, the RHIC experiments are currently investigating, on a subatomic level, what happens when heavy ions collide at high speeds. This is done in order to create such high temperatures and densities that quarks are no longer bound to one another. This state of matter is called the Quark-Gluon Plasma (QGP). Evidence for the existence of the QGP may be the quenching of hadron jets, which occurs when the fast quarks or gluons lose so much energy in the hot, dense medium that they cannot survive. Then the jets of particles that these particles usually result in cannot be made. By studying the particle yield at high transverse momentum (Pt), one can probe what is happening to the jets created during collisions. Using Pythia, a standard model event generator based on the Lund String Model, we study jets of particles created when elementary protons collide. Then we know what should happen to jets at high transverse momentum transfer, when no QGP is present. Comparing the pt spectrum of jet partners generated by Pythia to RHIC results for proton-proton collisions shows that the two do in fact agree. This not only insures that the analysis of RHIC data is correct, but it also establishes a basis for comparison for Au-Au collisions. Comparing d+Au collision data to the Pythia Pt spectrum of jets with leading baryon and meson triggers, we found good agreement. Thus the jet production does not change drastically in nature in the presence of a cold nuclear medium.

  18. Angular Momentum Sharing in Dissipative Collisions

    Science.gov (United States)

    Casini, G.; Poggi, G.; Bini, M.; Calamai, S.; Maurenzig, P. R.; Olmi, A.; Pasquali, G.; Stefanini, A. A.; Taccetti, N.; Steckmeyer, J. C.; Laforest, R.; Saint-Laurent, F.

    1999-09-01

    Light charged particles emitted by the projectilelike fragment were measured in the direct and reverse collision of 93Nb and 116Sn at 25A MeV. The experimental multiplicities of hydrogen and helium particles as a function of the primary mass of the emitting fragment show evidence for a correlation with net mass transfer. The ratio of hydrogen and helium multiplicities points to a dependence of the angular momentum sharing on the net mass transfer.

  19. Angular momentum sharing in dissipative collisions

    CERN Document Server

    Casini, G; Bini, M; Calamai, S; Maurenzig, P R; Olmi, A; Pasquali, G; Stefanini, A A; Taccetti, N; Steckmeyer, J C; Laforest, R; Saint-Laurent, F

    1999-01-01

    Light charged particles emitted by the projectile-like fragment were measured in the direct and reverse collision of $^{93}$Nb and $^{116}$Sn at 25 AMeV. The experimental multiplicities of Hydrogen and Helium particles as a function of the primary mass of the emitting fragment show evidence for a correlation with net mass transfer. The ratio of Hydrogen and Helium multiplicities points to a dependence of the angular momentum sharing on the net mass transfer.

  20. Fan affinity laws from a collision model

    CERN Document Server

    Bhattacharjee, Shayak

    2012-01-01

    The performance of a fan is usually estimated from hydrodynamical considerations. The calculations are long and involved and the results are expressed in terms of three affinity laws. In this work we use kinetic theory to attack this problem. A hard sphere collision model is used, and subsequently a correction to account for the flow behaviour of air is incorporated. Our calculations prove the affinity laws and provide numerical estimates of the air delivery, thrust and drag on a rotating fan.

  1. Hadron thermodynamics in relativistic nuclear collisions

    Science.gov (United States)

    Ammiraju, P.

    1985-01-01

    Various phenomenological models based on statistical thermodynamical considerations were used to fit the experimental data at high P sub T to a two temperature distribution. Whether this implies that the two temperatures belong to two different reaction mechanisms, or consequences of Lorentz-contraction factor, or related in a fundamental way to the intrinsic thermodynamics of Space-Time can only be revealed by further theoretical and experimental investigations of high P sub T phenomena in extremely energetic hadron-hadron collisions.

  2. NA35: sulphur-gold collision

    CERN Multimedia

    1991-01-01

    In this image the real particles produced by the collision of a 6400 GeV sulphur ion with a gold target can be seen as they pass through a streamer chamber. Streamer chambers consist of a gas chamber through which a strong pulsed electric field is passed, creating sparks as a charged particle passes through it. The NA35 experiment, which was in operation in the 1980s, was part of CERN's ongoing heavy ion project.

  3. Dynamics of reactive collisions by optical methods

    Science.gov (United States)

    Ureña, A. González; Vetter, R.

    This paper reviews recent developments in the study of reactive collisions using optical methods. Although the basic approach is from the experimental viewpoint, attention is paid to the conceptual and theoretical aspects of the physics underlying modern reaction dynamics. After a brief resume of basic concepts and definitions on both scalar and vectorial quantities characterizing the chemical reaction, a significant body of this paper describes the recent achievements using laser techniques, mainly via laser-induced fluorescence, and chemiluminescence. Both high-resolution crossed-beam and high-resolution bulb studies are presented in a complementary fashion, as they provide a detailed picture of reaction dynamics through the measurement of quantum state specific differential cross-sections. Specific examples include the use of Doppler resolved laser-induced fluorescence, multiphoton ionization or Cars studies. Some examples are also included based on the use of product imaging techniques, the novel approach of obtaining quantum state resolved differential cross-sections for chemical reactions. In addition, new data on the collision energy dependence of the collision cross-section, i.e. the excitation function, obtained by highly sensitive collision energy cross-beam techniques is also presented and reviewed. Another part of the paper is dedicated to recent advances in the study of reaction dynamics using electronically excited species. Emphasis is placed not only on the opening of new channels for chemical reactions but also on the possible outcome of the reaction products associated with the different symmetries of the excited potential energy surfaces. Finally, a section is dedicated to recent developments in studies carried out in the area of van der Waals and cluster reactions. The possibility of clocking the chemical act as well as very efficient trapping of reaction intermediates is illustrated with some examples. Throughout the whole paper care is taken to

  4. Catalytic Reactions in Heavy-ion Collisions

    CERN Document Server

    Kolomeitsev, E E

    2011-01-01

    We discuss a new type of reactions of a phi meson production on hyperons, pi Y--> phi Y and anti-kaons bar-K N --> phi Y. These reactions are not suppressed according to Okubo-Zweig-Iizuka rule and can be a new efficient source of phi mesons in a nucleus-nucleus collision. We discuss how these reactions can affect the centrality dependence and the rapidity distributions of the phi yield.

  5. Catalytic reactions in heavy-ion collisions

    Science.gov (United States)

    Kolomeitsev, E. E.; Tomášik, B.

    2012-06-01

    We discuss a new type of reactions of a ϕ-meson production on hyperons, πY → ϕY and antikaons -KN → ϕY. These reactions are not suppressed according to Okubo-Zweig-Iizuka rule and can be a new efficient source of ϕ mesons in a nucleus-nucleus collision. We discuss how these reactions can affect the centrality dependence and the rapidity distributions of the ϕ yield.

  6. Femtoscopy in Relativistic Heavy Ion Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Lisa, M; Pratt, S; Soltz, R A; Wiedemann, U

    2005-07-29

    Analyses of two-particle correlations have provided the chief means for determining spatio-temporal characteristics of relativistic heavy ion collisions. We discuss the theoretical formalism behind these studies and the experimental methods used in carrying them out. Recent results from RHIC are put into context in a systematic review of correlation measurements performed over the past two decades. The current understanding of these results are discussed in terms of model comparisons and overall trends.

  7. Azimuthal correlations in photon-photon collisions

    CERN Document Server

    Artéaga-Romero, N; Kessler, P; Ong, S; Panella, O

    1995-01-01

    Using the general helicity formula for \\gamma^* \\gamma^* collisions, we are showing that it should be possible to determine a number of independent ``structure functions'', i.e. linear combinations of elements of the two-photon helicity tensor, through azimuthal correlations in two-body or quasi two-body reactions induced by the photon-photon interaction, provided certain experimental conditions are satisfied. Numerical results of our computations are presented for some particular processes and dynamic models.

  8. Multiparticle collision dynamics in porous media

    CERN Document Server

    Matyka, Maciej

    2016-01-01

    We adopt the multiparticle collision dynamics method to simulate fluid flows in porous media. For this, the particle-level drag force is introduced into the original algorithm. The force hinder the flow resulting in global resistance and decrease of permeability. The extended algorithm is validated in the flow through fully porous channel with analytical solution. Basic properties of the solver are investigated including its dependency of permeability on model parameters.

  9. Statistical Hadronisation in Positron-proton Collisions

    CERN Document Server

    Urmossy, Karoly

    2016-01-01

    We reproduce charged hadron momentum fraction distributions measured in diffractive positron-proton collisions resulting in hadronic final states with two jets of approximately equal energies. Our hadronisation model is based on microcanonical statistics and negative binomial multiplicity fluctuations. We describe the scale dependence of the fit parameters of the model with formulas obtained by approximating the exact solution of the DGLAP equation in the $\\phi^3$ theory with leading order splitting function and 1-loop coupling.

  10. Vibrational and Electronic Energy Transfer and Dissociation of Diatomic Molecules by Electron Collisions

    Science.gov (United States)

    Huo, Winifred M.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    At high altitudes and velocities equal to or greater than the geosynchronous return velocity (10 kilometers per second), the shock layer of a hypersonic flight will be in thermochemical nonequilibrium and partially ionized. The amount of ionization is determined by the velocity. For a trans atmospheric flight of 10 kilometers per second and at an altitude of 80 kilometers, a maximum of 1% ionization is expected. At a velocity of 12 - 17 kilometer per second, such as a Mars return mission, up to 30% of the atoms and molecules in the flow field will be ionized. Under those circumstances, electrons play an important role in determining the internal states of atoms and molecules in the flow field and hence the amount of radiative heat load and the distance it takes for the flow field to re-establish equilibrium. Electron collisions provide an effective means of transferring energy even when the electron number density is as low as 1%. Because the mass of an electron is 12,760 times smaller than the reduced mass of N2, its average speed, and hence its average collision frequency, is more than 100 times larger. Even in the slightly ionized regime with only 1% electrons, the frequency of electron-molecule collisions is equal to or larger than that of molecule-molecule collisions, an important consideration in the low density part of the atmosphere. Three electron-molecule collision processes relevant to hypersonic flows will be considered: (1) vibrational excitation/de-excitation of a diatomic molecule by electron impact, (2) electronic excitation/de-excitation, and (3) dissociative recombination in electron-diatomic ion collisions. A review of available data, both theory and experiment, will be given. Particular attention will be paid to tailoring the molecular physics to the condition of hypersonic flows. For example, the high rotational temperatures in a hypersonic flow field means that most experimental data carried out under room temperatures are not applicable. Also

  11. Photon-Photon Collisions -- Past and Future

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC

    2005-12-02

    I give a brief review of the history of photon-photon physics and a survey of its potential at future electron-positron colliders. Exclusive hadron production processes in photon-photon and electron-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes. There are also important high energy {gamma}{gamma} and e{gamma} tests of quantum chromodynamics, including the production of jets in photon-photon collisions, deeply virtual Compton scattering on a photon target, and leading-twist single-spin asymmetries for a photon polarized normal to a production plane. Since photons couple directly to all fundamental fields carrying the electromagnetic current including leptons, quarks, W's and supersymmetric particles, high energy {gamma}{gamma} collisions will provide a comprehensive laboratory for Higgs production and exploring virtually every aspect of the Standard Model and its extensions. High energy back-scattered laser beams will thus greatly extend the range of physics of the International Linear Collider.

  12. Collision Statistics of Driven Polydisperse Granular Gases

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhi-Yuan; ZHANG Duan-Ming; LI Zhong-Ming; YANG Feng-Xia; GUO Xin-Ping

    2008-01-01

    We present a dynamicai model of two-dimensional polydisperse granular gases with fractal size distribution, in which the disks are subject to inelastic mutual collisions and driven by standard white noise. The inhomogeneity of the disk size distribution can be measured by a fractal dimension df. By Monte Carlo simulations, we have mainly investigated the effect of the inhomogeneity on the statistical properties of the system in the same inelasticity case. Some novel results are found that the average energy of the system decays exponentiaUy with a tendency to achieve a stable asymptotic value, and the system finally reaches a nonequilibrium steady state after a long evolution time. Furthermore, the inhomogeneity has great influence on the steady-state statisticai properties. With the increase of the fractal dimension df, the distributions of path lengths and free times between collisions deviate more obviously from expected theoretical forms for elastic spheres and have an overpopulation of short distances and time bins. The collision rate increases with df, but it is independent of time. Meanwhile, the velocity distribution deviates more strongly from the Gaussian one, but does not demonstrate any apparent universal behavior.

  13. Collisions of Rydberg Atoms with Charged Particles

    Science.gov (United States)

    MacAdam, Keith B.

    2000-10-01

    The long range of Coulomb interactions, together with the large size, long radiative lifetimes and high state densities of highly excited Rydberg atoms, results in inelastic collision cross sections of prodigious size -- often large enough to outweigh small number densities in astrophysica and cool laboratory plasmas -- and in other unusual features. This talk will provide: (a) a brief survey of the significant features of collisions between electron or positive ions and state-selected Rydberg atoms and of recent experiments( O. Makarov and K.B. MacAdam, Phys. Rev. A 60), 2131-8 (1999); and K.B. MacAdam, J.C. Day and D.M. Homan, Comm. At. Mol. Phys./Comm. Mod. Phys. 1(2), Part D, 57-73 (1999). to investigate them; (b) an introduction to some of the special techniques that have been developed(J.L. Horn, D.M. Homan, C.S. Hwang, W.L. Fuqua III and K.B. MacAdam, Rev. Sci. Instrum. 69), 4086-93 (1998). for preparation, manipulation and detection of Rydberg atoms; and (c) a glimpse at new directions in Rydberg atom collision research.

  14. Collision of two black holes: Theoretical framework

    Energy Technology Data Exchange (ETDEWEB)

    Smarr, L.; Cadez, A.; DeWitt, B.; Eppley, K.

    1976-11-15

    Highly nonspherical time-dependent collisions between black holes may be powerful sources of gravitational radiation. We consider various attempts at estimating the efficiency of the generation of radiation by such collisions. To determine the actual efficiency as well as to understand the details of the dynamical coalescence of black-hole event horizons, we have developed a numerical method for solving the Einstein gravitational field equations in these high-velocity strong-field regions. The head-on collision of two nonrotating vacuum black holes is chosen as an example of our technique. We use the geometrodynamical model of a black hole as an Einstein-Rosen bridge. The initial data to be evolved are the time-symmetric conformally flat data discovered by Misner. A new set of spatial coordinates for these data is derived. Then the general space plus time decomposition of Einstein's equations is presented and specialized to the axisymmetric nonrotating case. Details of the evolution will be given in later papers. (AIP)

  15. LHC Report: Towards stable beams and collisions

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    Over the past two weeks, the LHC re-commissioning with beam has continued at a brisk pace. The first collisions of 2011 were produced on 2 March, with stable beams and collisions for physics planned for the coming days. Low intensity beams with just a few bunches of particles were used to test the energy ramp to 3.5 TeV and the squeeze. The results were successful and, as a by-product, the first collisions of 2011 were recorded 2 March. One of the main activities carried out by the operation teams has been the careful set-up of the collimation system, and the injection and beam dump protection devices. The collimation system provides essential beam cleaning, preventing stray particles from impacting other elements of the machine, particularly the superconducting magnets. In addition to the collimation system, also the injection and beam dump protection devices perform a vital machine protection role, as they detect any beam that might be mis-directed during rare, but not totally unavoidable, hardware hiccups...

  16. SPH simulations of high-speed collisions

    Science.gov (United States)

    Rozehnal, Jakub; Broz, Miroslav

    2016-10-01

    Our work is devoted to a comparison of: i) asteroid-asteroid collisions occurring at lower velocities (about 5 km/s in the Main Belt), and ii) mutual collisions of asteroids and cometary nuclei usually occurring at significantly higher relative velocities (> 10 km/s).We focus on differences in the propagation of the shock wave, ejection of the fragments and possible differences in the resultingsize-frequency distributions of synthetic asteroid families. We also discuss scaling with respect to the "nominal" target diameter D = 100 km, projectile velocity 3-7 km/s, for which a number of simulations were done so far (Durda et al. 2007, Benavidez et al. 2012).In the latter case of asteroid-comet collisions, we simulate the impacts of brittle or pre-damaged impactors onto solid monolithic targets at high velocities, ranging from 10 to 15 km/s. The purpose of this numerical experiment is to better understand impact processes shaping the early Solar System, namely the primordial asteroid belt during during the (late) heavy bombardment (as a continuation of Broz et al. 2013).For all hydrodynamical simulations we use a smoothed-particle hydrodynamics method (SPH), namely the lagrangian SPH3D code (Benz & Asphaug 1994, 1995). The gravitational interactions between fragments (re-accumulation) is simulated with the Pkdgrav tree-code (Richardson et al. 2000).

  17. Non-collision backgrounds in ATLAS

    CERN Document Server

    Gibson, S M; The ATLAS collaboration

    2012-01-01

    The proton-proton collision events recorded by the ATLAS experiment are on top of a background that is due to both collision debris and non-collision components. The latter comprises of three types: beam-induced backgrounds, cosmic particles and detector noise. We present studies that focus on the first two of these. We give a detailed description of beam-related and cosmic backgrounds based on the full 2011 ATLAS data set, and present their rates throughout the whole data-taking period. Studies of correlations between tertiary proton halo and muon backgrounds, as well as, residual pressure and resulting beam-gas events seen in beam-condition monitors will be presented. Results of simulations based on the LHC geometry and its parameters will be presented. They help to better understand the features of beam-induced backgrounds in each ATLAS sub-detector. The studies of beam-induced backgrounds in ATLAS reveal their characteristics and serve as a basis for designing rejection tools that can be applied in physic...

  18. Electromagnetic Radiations from Heavy Ion Collision

    Directory of Open Access Journals (Sweden)

    Payal Mohanty

    2013-01-01

    Full Text Available In this review, we have discussed the different sources of photons and dileptons produced in heavy ion collision (HIC. The transverse momentum (pT spectra of photons for different collision energies are analyzed with a view of extracting the thermal properties of the system formed in HIC. We showed the effect of viscosity on pT spectra of produced thermal photons. The dilepton productions from hot hadrons are considered including the spectral change of light vector mesons in the thermal bath. We have analyzed the pT and invariant mass (M spectra of dileptons for different collision energies too. As the individual spectra are constrained by certain unambiguous hydrodynamical inputs, so we evaluated the ratio of photon to dilepton spectra, Rem, to overcome those quantities. We argue that the variation of the radial velocity extracted from Rem with M is indicative of a phase transition from the initially produced partons to hadrons. In the calculations of interferometry involving dilepton pairs, it is argued that the nonmonotonic variation of HBT radii with invariant mass of the lepton pairs signals the formation of quark gluon plasma in HIC. Elliptic flow (v2 of dilepton is also studied at sNN=2.76 TeV for 30–40% centrality using the (2+1d hydrodynamical model.

  19. Granting silence to avoid wireless collisions

    KAUST Repository

    Choi, Jung Il

    2010-10-01

    We describe grant-to-send, a novel collision avoidance algorithm for wireless mesh networks. Rather than announce packets it intends to send, a node using grant-to-send announces packets it expects to hear others send. We present evidence that inverting collision avoidance in this way greatly improves wireless mesh performance. Evaluating four protocols from 802.11 meshes and 802.15.4 sensor networks, we find that grant-to-send matches or outperforms CSMA and RTS/CTS in all cases. For example, in a 4-hop UDP flow, grantto- send can achieve 96% of the theoretical maximum throughput while maintaining a 99.9% packet delivery ratio. Grant-tosend is also general enough to replace protocol-specific collision avoidance mechanisms common to sensor network protocols. Grant-to-send is simple. For example, incorporating it into 802.11 requires only 11 lines of driver code and no hardware changes. Furthermore, as it reuses existing 802.11 mechanisms, grant-to-send inter-operates with current networks and can be incrementally deployed. © 2010 IEEE.

  20. New Results for Ultraperipheral Heavy Ion Collisions

    CERN Document Server

    Szczurek, Antoni; Lebiedowicz, Piotr; Schäfer, Wolfgang

    2016-01-01

    We discuss diphoton semi(exclusive) production in ultraperipheral $PbPb$ collisions at energy of $\\sqrt{s_{NN}}=$ 5.5 TeV (LHC). The nuclear calculations are based on equivalent photon approximation in the impact parameter space. The cross sections for elementary $\\gamma \\gamma \\to \\gamma \\gamma$ subprocess are calculated including three different mechanisms: box diagrams with leptons and quarks in the loops, a VDM-Regge contribution with virtual intermediate hadronic excitations of the photons and the two-gluon exchange contribution (formally three-loops). We got relatively high cross sections in $PbPb$ collisions. This opens a possibility to study the $\\gamma \\gamma \\to \\gamma \\gamma$ (quasi)elastic scattering at the LHC. We find that the cross section for elastic $\\gamma\\gamma$ scattering could be measured in the lead-lead collisions for the diphoton invariant mass up to $W_{\\gamma\\gamma} \\approx 15-20$ GeV. We identify region(s) of phase space where the two-gluon exchange contribution becomes important in...

  1. Contributions of collision rate and collision efficiency to erythrocyte aggregation in postcapillary venules at low flow rates.

    Science.gov (United States)

    Kim, Sangho; Zhen, Janet; Popel, Aleksander S; Intaglietta, Marcos; Johnson, Paul C

    2007-09-01

    Red blood cell aggregation at low flow rates increases venous vascular resistance, but the process of aggregate formation in these vessels is not well understood. We previously reported that aggregate formation in postcapillary venules of the rat spinotrapezius muscle mainly occurs in a middle region between 15 and 30 microm downstream from the entrance. In light of the findings in that study, the main purpose of this study was to test two hypotheses by measuring collision frequency along the length of the venules during low flow. We tested the hypothesis that aggregation rarely occurs in the initial 15-microm region of the venule because collision frequency is very low. We found that collision frequency was lower than in other regions, but collision efficiency (the ratio of aggregate formation to collisions) was almost nil in this region, most likely because of entrance effects and time required for aggregation. Radial migration of red blood cells and Dextran 500 had no effect on collision frequency. We also tested the hypothesis that aggregation was reduced in the distal venule region because of the low aggregability of remaining nonaggregated cells. Our findings support this hypothesis, since a simple model based on the ratio of aggregatable to nonaggregatable red blood cells predicts the time course of collision efficiency in this region. Collision efficiency averaged 18% overall but varied from 0 to 52% and was highest in the middle region. We conclude that while collision frequency influences red blood cell aggregate formation in postcapillary venules, collision efficiency is more important.

  2. Coalescence collision of liquid drops I: Off-center collisions of equal-size drops

    Directory of Open Access Journals (Sweden)

    Alejandro Acevedo-Malavé

    2011-09-01

    Full Text Available The Smoothed Particle Hydrodynamics method (SPH is used here to model off-center collisions of equal-size liquid drops in a three-dimensional space. In this study the Weber number is calculated for several conditions of the droplets dynamics and the velocity vector fields formed inside the drops during the collision process are shown. For the permanent coalescence the evolution of the kinetic and internal energy is shown and also the approaching to equilibrium of the resulting drop. Depending of the Weber number three possible outcomes for the collision of droplets is obtained: permanent coalescence, flocculation and fragmentation. The fragmentation phenomena are modeled and the formation of small satellite drops can be seen. The ligament that is formed follows the “end pinching” mechanism and it is transformed into a flat structure.

  3. Conservative bin-to-bin fractional collisions

    Science.gov (United States)

    Martin, Robert

    2016-11-01

    Particle methods such as direct simulation Monte Carlo (DSMC) and particle-in-cell (PIC) are commonly used to model rarefied kinetic flows for engineering applications because of their ability to efficiently capture non-equilibrium behavior. The primary drawback to these methods relates to the poor convergence properties due to the stochastic nature of the methods which typically rely heavily on high degrees of non-equilibrium and time averaging to compensate for poor signal to noise ratios. For standard implementations, each computational particle represents many physical particles which further exacerbate statistical noise problems for flow with large species density variation such as encountered in flow expansions and chemical reactions. The stochastic weighted particle method (SWPM) introduced by Rjasanow and Wagner overcome this difficulty by allowing the ratio of real to computational particles to vary on a per particle basis throughout the flow. The DSMC procedure must also be slightly modified to properly sample the Boltzmann collision integral accounting for the variable particle weights and to avoid the creation of additional particles with negative weight. In this work, the SWPM with necessary modification to incorporate the variable hard sphere (VHS) collision cross section model commonly used in engineering applications is first incorporated into an existing engineering code, the Thermophysics Universal Research Framework. The results and computational efficiency are compared to a few simple test cases using a standard validated implementation of the DSMC method along with the adapted SWPM/VHS collision using an octree based conservative phase space reconstruction. The SWPM method is then further extended to combine the collision and phase space reconstruction into a single step which avoids the need to create additional computational particles only to destroy them again during the particle merge. This is particularly helpful when oversampling the

  4. Dielectron production in proton-proton collisions with ALICE

    CERN Document Server

    Koehler, Markus K

    Ultrarelativistic hadron collisions, such as delivered since a couple of years at the Large Hadron Collider (LHC), provide new insights into the properties of strongly interacting matter at high temperatures and densities, which is expected to have existed a few of a millionth seconds after the big bang. Electromagnetic probes, such as leptons and photons, are emitted during the entire collision. Since they do not undergo strong interactions, they reflect the entire evolution of the collision.\\\\ Pairs of leptons, so called dileptons, have the advantage compared to real photons, that they do not only carry momentum, but also have a non-zero invariant mass. The invariant mass spectrum of dileptons is a superposition of several components and allows to address different characteristics of the medium.\\\\ To understand dielectron production in heavy-ion collisions, reference measurements in proton-proton (pp) collisions are necessary. pp collisions reflect the vacuum contribution of the particles produced in heavy-...

  5. Post-collision interactions and the polarization effect in (e, 2e) collisions of helium

    Institute of Scientific and Technical Information of China (English)

    Zang Shuang-Shuang; Ge Zi-Ming

    2012-01-01

    A modified distorted-wave Born approximation (DWBA) method is used to calculate the triple differential cross sections (TDCSs) in a coplanar asymmetric geometry for the electron impact single ionization of a He (1s2) atom at intermediate and lower energies.The post-collision interaction and the polarization effect in (e,2e) collisions of helium are considered in the calculations.The polarization potentials from the damping method and density functional theory (DFT) arc compared.Theoretical results are compared with the recent experimental data.

  6. Analysis on Uncertain Information and Actions for Preventing Collision

    Institute of Scientific and Technical Information of China (English)

    胡甚平; FANG; Quan-gen

    2007-01-01

    Discusses and analyzes the causes and characteristics of the uncertainties of the information and actions for preventing collision at sea on the basic knowledge of the collision avoidance. Describes the ways and functions of the investigations about the uncertainties of the information and actions of collision avoidance with the navigation simulators. Puts forward some suggestions for the officers to master the skills of the recognition of these uncertainties of the information and actions by the training with the simulator during the MET course.

  7. Multiplicity and theremalization time in heavy-ions collisions

    Science.gov (United States)

    Aref'eva, Irina

    2016-10-01

    We present a concise review of quark-gluon plasma formation in heavy-ions collisions within the holographic approach. In particular, we discuss how to get the total multiplicity in heavy ions collision to fit the recent experimental data. We also discuss theoretical estimations of time formation of QGP in heavy ions collision and show that different observables can give the different times of QGP formation.

  8. Multiplicity and theremalization time in heavy-ions collisions

    Directory of Open Access Journals (Sweden)

    Aref’eva Irina

    2016-01-01

    Full Text Available We present a concise review of quark-gluon plasma formation in heavy-ions collisions within the holographic approach. In particular, we discuss how to get the total multiplicity in heavy ions collision to fit the recent experimental data. We also discuss theoretical estimations of time formation of QGP in heavy ions collision and show that different observables can give the different times of QGP formation.

  9. Search for Tetraquarks in Relativistic Heavy-Ion Collisions

    Institute of Scientific and Technical Information of China (English)

    MA Zhong-Biao; GAO Chong-Shou

    2006-01-01

    Tetraquarks can be produced in relativistic heavy-ion collision. The yield of this kind of tetraquarks can increase significantly soon as the formation of QGP after the collision. If there is no phase transition after collision, the upper bound of the production of this four-quark states can be estimated from the free hadronic gas model for nuclearmatter. The relative yield ratio of tetraquark cs(s)(s) to Ω is less than 0.0164.

  10. Collisions of Small Nuclei in the Thermal Model

    CERN Document Server

    Cleymans, J; Oeschler, H.; Redlich, K.; Sharma, N.

    2016-01-01

    An analysis is presented of the expectations of the thermal model for particle production in collisions of small nuclei. The maxima observed in particle ratios of strange particles to pions as a function of beam energy in heavy ion collisions, are reduced when considering smaller nuclei. Of particular interest is the $\\Lambda/\\pi^+$ ratio shows the strongest maximum which survives even in collisions of small nuclei.

  11. Real Time Collision Detection Using Depth Texturing Spheres

    Institute of Scientific and Technical Information of China (English)

    WANG Ji; ZHAI Zhengjun; CAI Xiaobin

    2006-01-01

    In this paper, we present a novel collision detection algorithm to real time detect the collisions of objects. We generate sphere textures of objects, and use programmable graphics hardware to mapping texture and check the depth of different objects to detect the collision. We have implemented the algorithm and compared it with CULLIDE. The result shows that our algorithm is more effective than CULLIDE and has fixed executive time to suit for real-time applications.

  12. Piezoelectric Polymer-Based Collision Detection Sensor for Robotic Applications

    Directory of Open Access Journals (Sweden)

    J. Michael Wooten

    2015-03-01

    Full Text Available The authors present a large area collision detection sensor utilizing the piezoelectric effect of polyvinylidene fluoride film. The proposed sensor system provides high dynamic range for touch sensation, as well as robust adaptability to achieve collision detection on complex-shaped surfaces. The design allows for cohabitation of humans and robots in cooperative environments that require advanced and robust collision detection systems. Data presented in the paper are from sensors successfully retrofitted onto an existing commercial robotic manipulator.

  13. Gluon field fluctuations in nuclear collisions: Multiplicity and eccentricity distributions

    Energy Technology Data Exchange (ETDEWEB)

    Schenke, Björn [Physics Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Tribedy, Prithwish [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Venugopalan, Raju [Physics Department, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2014-06-15

    We discuss different sources of fluctuations in nuclear collisions and their realization in the IP-Glasma model. We present results for multiplicity distributions in p+p and p+A collisions and compare eccentricity (ε{sub 2}, ε{sub 3}, ε{sub 4}) distributions in A + A collisions to the v{sub n} distributions in 10 centrality classes measured by the ATLAS Collaboration.

  14. Studies of QCD structure in high-energy collisions

    Energy Technology Data Exchange (ETDEWEB)

    Nadolsky, Pavel M. [Southern Methodist Univ., Dallas, TX (United States)

    2016-06-26

    ”Studies of QCD structure in high-energy collisions” is a research project in theoretical particle physics at Southern Methodist University funded by US DOE Award DE-SC0013681. The award furnished bridge funding for one year (2015/04/15-2016/03/31) between the periods funded by Nadolsky’s DOE Early Career Research Award DE-SC0003870 (in 2010-2015) and a DOE grant DE-SC0010129 for SMU Department of Physics (starting in April 2016). The primary objective of the research is to provide theoretical predictions for Run-2 of the CERN Large Hadron Collider (LHC). The LHC physics program relies on state-of-the-art predictions in the field of quantum chromodynamics. The main effort of our group went into the global analysis of parton distribution functions (PDFs) employed by the bulk of LHC computations. Parton distributions describe internal structure of protons during ultrarelivistic collisions. A new generation of CTEQ parton distribution functions (PDFs), CT14, was released in summer 2015 and quickly adopted by the HEP community. The new CT14 parametrizations of PDFs were obtained using benchmarked NNLO calculations and latest data from LHC and Tevatron experiments. The group developed advanced methods for the PDF analysis and estimation of uncertainties in LHC predictions associated with the PDFs. We invented and refined a new ’meta-parametrization’ technique that streamlines usage of PDFs in Higgs boson production and other numerous LHC processes, by combining PDFs from various groups using multivariate stochastic sampling. In 2015, the PDF4LHC working group recommended to LHC experimental collaborations to use ’meta-parametrizations’ as a standard technique for computing PDF uncertainties. Finally, to include new QCD processes into the global fits, our group worked on several (N)NNLO calculations.

  15. Coulomb-influenced collisions in aerosols and dusty plasmas.

    Science.gov (United States)

    Gopalakrishnan, Ranganathan; Hogan, Christopher J

    2012-02-01

    In aerosol and dusty plasma systems, the behavior of suspended particles (grains) is often strongly influenced by collisions occurring between ions and particles, as well as between particles themselves. In determining the collision kernel or collision rate coefficient for such charged entities, complications arise in that the collision process can be completely described neither by continuum transport mechanics nor by free molecular (ballistic) mechanics; that is, collisions are transition regime processes. Further, both the thermal energy and the potential energy between colliding entities can strongly influence the collision rate and must be considered. Flux-matching theory, originally developed by Fuchs, is frequently applied for calculation of collision rate coefficients under these circumstances. However, recent work suggests that crucial assumptions in flux-matching theory are not appropriate to describe transition regime collisions in the presence of potential interactions. Here, we combine dimensional analysis and mean first passage time calculations to infer the collision kernel between dilute charged entities suspended in a light background gas at thermal equilibrium. The motion of colliding entities is described by a Langevin equation, and Coulombic interactions are considered. It is found that the dimensionless collision kernel for these conditions, H, is a function of the diffusive Knudsen number, Kn(D) (in contrast to the traditional Knudsen number), and the potential energy to thermal energy ratio, Ψ(E). For small and large Kn(D), it is found that the dimensionless collision kernels inferred from mean first passage time calculations collapse to the appropriate continuum and free molecular limiting forms, respectively. Further, for repulsive collisions (Ψ(E) negative) or attractive collisions with Ψ(E)0.5, it is found that flux-matching theory predictions substantially underestimate the collision kernel. We find that the collision process in this

  16. A New Aloha Anti-Collision Algorithm Based on CDMA

    Science.gov (United States)

    Bai, Enjian; Feng, Zhu

    The tags' collision is a common problem in RFID (radio frequency identification) system. The problem has affected the integrity of the data transmission during the process of communication in the RFID system. Based on analysis of the existing anti-collision algorithm, a novel anti-collision algorithm is presented. The new algorithm combines the group dynamic frame slotted Aloha algorithm with code division multiple access technology. The algorithm can effectively reduce the collision probability between tags. Under the same number of tags, the algorithm is effective in reducing the reader recognition time and improve overall system throughput rate.

  17. Long-range correlations in high multiplicity and collisions

    Indian Academy of Sciences (India)

    Gunther Roland

    2015-05-01

    This review summarizes recent discoveries in high-energy proton+proton and proton+nucleus collisions, with particular attention on the observation of long-range azimuthal correlations in high multiplicity collisions. These correlations, which resemble those seen in ultrarelativistic nucleus–nucleus collisions, provide a unique window into the physics of the very early collision stage in high energy nuclear interactions. Here we present a compilation of the most important experimental results and briefly discuss successes and challenges for a selection of theoretical approaches.

  18. Turbulent collision statistics of cloud droplets at low dissipation rates

    Science.gov (United States)

    Banerjee, Sandipan

    Collisions of sedimenting droplets in a turbulent flow is of great importance in cloud physics. Collision efficiency and collision enhancement over gravitational collision by air turbulence govern the growth of the cloud droplets leading to warm rain initiation and precipitation dynamics. In this thesis we present direct numerical simulation (DNS) results for collision statistics of droplets in turbulent flows of low dissipation rates (in the range of 3 cm2/s3-100 cm2/s3) relevant to strato-cumulus clouds. First, we revisit the case of gravitational collision in still fluid to validate the details of the collision detection algorithm used in our code. We compare the collision statistics with either new analytical predictions regarding the percentages of different collision types, or results from published papers. The effect of initial conditions on the collision statistics and statistical uncertainties are analyzed both analytically and through the simulation data. Second, we consider the case of weak turbulence (as in strato-cumulus clouds). In this case the particle motion is mainly driven by gravity. The standard deviation (or the uncertainty) of the average collision statistics is examined analytically in terms of time correlation function of the data. We then report new DNS results of collision statistics in a turbulent flow, showing how air turbulence increases the geometric colli- sion statistics and the collision efficiency. We find that the collision-rate enhancement due to turbulence depends nonlinearly on the flow dissipation rate. This result calls for a more careful parameterization of the collision statistics in strato-cumulus clouds. Due to the low flow dissipation rate in stratocumulus clouds, a related challenge is low droplet Stokes number. Here the Stokes number is the ratio of droplet inertial response time to the flow Kolmogorov time. A very low Stokes number implies that the numerical integration time step is now governed by the droplet

  19. A collision detection approach in virtual environment of micromanipulation robot

    Institute of Scientific and Technical Information of China (English)

    Sun Lining; Tan Fusheng; Rong Weibin; Zhu Jiang

    2005-01-01

    Operators suffer much difficulty in manipulating micro-size objects without the assistance of friendly interfaces due to the scaling effects in micro world. The paper presented a general framework for micromanipulation robot based on virtual reality technology. With the framework we brought forward a FDH (Fixed Direction Hulls) based bounding box method to handle the collision detection of the peg-in-hole microassembly. The collision response model for the collision between micro needle and hole was presented. The virtual force and corresponding displacement were calculated with the model of bending deformation and pressing deformation. Experiments verify the validity of collision response model.

  20. Search for Exotic Strange Dibaryon in Relativistic Heavy Ion Collisions

    Institute of Scientific and Technical Information of China (English)

    GAOChong-Shou

    2003-01-01

    The exotic strange dibaryon particle (ΩΩ)0+ with S = -6 can be produced in relativistic heavy ion collisions. The yields of this kind of exotic strange dibaryon particles can increase signitlcantly soon as the formation of QGP does exhibit after the collision. If there is no phase transition after the collision, the upper bound of the production of this diomega can be estimated from the free hadronic gas model for nuclear matter. The relative yield ratio of diomega to deuteron is less than 0.000205, this means that if there is no QGP creation it is difficult to observe the production of diomega in relativistic heavy ion collisions.

  1. Theoretical study of charge exchange dynamics in He$^+$ + NO collisions

    CERN Document Server

    Bene, E

    2014-01-01

    We investigate the charge transfer mechanism in the collisions of helium ions on nitric oxide using a molecular description framework with consideration of the orientation of the projectile toward the target. The anisotropy of the collision process has been analysed in detail in connection with the non-adiabatic interactions around avoided crossings. Potential energy curves, radial and rotational coupling matrix elements have been determined by means of ab initio quantum chemical methods. The collision dynamics is performed in the [1.-25.] keV collision energy range using a semiclassical approach, and the total electron transfer cross sections are analysed with regard to available experimental data.

  2. Analysis and Design of Ship Collision Barriers on a Submerged Floating Tunnel subjected to Large Ship Collisions

    OpenAIRE

    Århus, Gisle Hoel

    2016-01-01

    Reinertsen AS is developing a bridge crossing concept to cross the Sognefjord in Norway. The concept consists of floating bridge and submerged tunnel. The submerged tunnel is exposed to ship collisions from passing ship traffic. A protective ship collision barrier is used to protect the exposed part of the submerged tunnel. A design of the collision barrier is proposed. The barrier is made of Aluminium. There are some special considerations one must take into account when using aluminium...

  3. New collision attacks on SHA-1 based on optimal joint local-collision analysis

    NARCIS (Netherlands)

    Stevens, M.M.J.; Johansson, T.; Nguyen, P.Q.

    2013-01-01

    The main contributions of this paper are two-fold. Firstly, we present a novel direction in the cryptanalysis of the cryptographic hash function {\\SHA}. Our work builds on previous cryptanalytic efforts on {\\SHA} based on combinations of local collisions. Due to dependencies, previous approaches u

  4. Action principle for Coulomb collisions in plasmas

    Science.gov (United States)

    Hirvijoki, Eero

    2016-09-01

    An action principle for Coulomb collisions in plasmas is proposed. Although no natural Lagrangian exists for the Landau-Fokker-Planck equation, an Eulerian variational formulation is found considering the system of partial differential equations that couple the distribution function and the Rosenbluth-MacDonald-Judd potentials. Conservation laws are derived after generalizing the energy-momentum stress tensor for second order Lagrangians and, in the case of a test-particle population in a given plasma background, the action principle is shown to correspond to the Langevin equation for individual particles.

  5. Action principle for Coulomb collisions in plasmas

    CERN Document Server

    Hirvijoki, Eero

    2015-01-01

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

  6. Luminosity and Crab Waist Collision Studies

    CERN Document Server

    Wu, Wanwei

    2015-01-01

    In high energy physics, the luminosity is one useful value to characterize the performance of a particle collider. To gain more available data, we need to maximize the luminosity in most collider experiments. With the discussions of tune shift involved the beam dynamics and a recently proposed "crabbed waist" scheme of beam-beam collisions, we present some qualitative analysis to increase the luminosity. In addition, beam-beam tune shifts and luminosities of $e^{+}e^{-}$, $pp$/$p\\bar{p}$, and $\\mu^{+}\\mu^{-}$ colliders are discussed.

  7. Non abelian hydrodynamics and heavy ion collisions

    CERN Document Server

    Calzetta, Esteban

    2013-01-01

    The goal of the relativistic heavy ion collisions (RHIC) program is to create a state of matter where color degrees of freedom are deconfined. The dynamics of matter in this state, in spite of the complexities of quantum chromodynamics, is largely determined by the conservation laws of energy momentum and color currents. Therefore it is possible to describe its main features in hydrodynamic terms, the very short color neutralization time notwithstanding. In this lecture we shall give a simple derivation of the hydrodynamics of a color charged fluid, by generalizing the usual derivation of hydrodynamics from kinetic theory to the non abelian case.

  8. Dimesoatoms production in high energy collisions

    CERN Document Server

    Afanasyev, L; Voskresenskaya, O

    2016-01-01

    The production of two meson electromagnetic bound states and free meson pairs $\\pi^+\\pi^-$, $K^+K^-$, $\\pi^+ K^{\\mp}$ in relativistic collisions has been considered. It was shown that making use of the exact Coulomb wave function for dimesoatom (DMA) allows one to calculate the yield of any nS state with desired accuracy. The relative probabilities of production of DMA and meson pairs in the free state are estimated. The amplitude of DMA transition from 1S to 2P state, which is essential for the pionium Lamb shift measurements, has been obtained.

  9. Sudden Hadronization in Relativistic Nuclear Collisions

    CERN Document Server

    Rafelski, Johann; Rafelski, Johann; Letessier, Jean

    2000-01-01

    We formulate and study the mechanical instability criterion of dense matter fireballs without considering a specific equation of state (EoS). We demonstrate the consistency with the chemical freeze-out of a fireball of matter formed in 158AGeV Pb-Pb collisions. Assuming EoS appropriate for quark-gluon matter, we demonstrate the required deep QGP supercooling prior to sudden hadronization. In a model independent approach, but using results of hadron abundance analysis and lattice QCD, we show that the latent heat of the deconfined phase is bounded from below 0.14GeV/fm^3\\le B.

  10. Helicity separation in Heavy-Ion Collisions

    CERN Document Server

    Baznat, Mircea; Sorin, Alexander; Teryaev, Oleg

    2013-01-01

    We study the P-odd effects related to the vorticity of the medium formed in noncentral heavy ion collisions. Using the kinetic Quark-Gluon Strings Model we perform the numerical simulations of the vorticity and hydrodynamical helicity for the various atomic numbers, energies and centralities. We observed the vortical structures typically occupying the relatively small fraction of the fireball volume. In the course of numerical simulations the noticeable hydrodanamical helicity was observed manifesting the specific mirror behaviour with respect to the reaction plane. The effect is maximal at the NICA and FAIR energy range.

  11. Inelastic Collision Rates of Trapped Metastable Hydrogen

    CERN Document Server

    Landhuis, D; Moss, S C; Steinberger, Jack; Van't, K M D; Willmann, L; Greytak, T J; Kleppner, D; Landhuis, David; Matos, Lia; Moss, Stephen C.; Steinberger, Julia K.; Vant, Kendra; Willmann, Lorenz; Greytak, Thomas J.; Kleppner, Daniel

    2003-01-01

    We report the first detailed decay studies of trapped metastable (2S) hydrogen. By two-photon excitation of ultracold H samples, we have produced clouds of at least 5x10^7 magnetically trapped 2S atoms at densities greater than 4x10^10 cm^-3 and temperatures below 100 \\muK. We derive experimental values for the total 2S-2S two-body loss rate constant in this temperature regime. Our results are in the range of recent theoretical calculations. We also find experimental upper limits on the rate constant for loss due to inelastic 1S-2S collisions.

  12. Non abelian hydrodynamics and heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Calzetta, E. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, Ciudad Universitaria, Buenos Aires 1428 (Argentina)

    2014-01-14

    The goal of the relativistic heavy ion collisions (RHIC) program is to create a state of matter where color degrees of freedom are deconfined. The dynamics of matter in this state, in spite of the complexities of quantum chromodynamics, is largely determined by the conservation laws of energy momentum and color currents. Therefore it is possible to describe its main features in hydrodynamic terms, the very short color neutralization time notwithstanding. In this lecture we shall give a simple derivation of the hydrodynamics of a color charged fluid, by generalizing the usual derivation of hydrodynamics from kinetic theory to the non abelian case.

  13. RHIC operation with asymmetric collisions in 2015

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Aschenauer, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Atoian, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Brown, K. A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Bruno, D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Connolly, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ottavio, T. D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Drees, K. A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fischer, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gu, X. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hayes, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Laster, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Luo, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); Makdisi, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); Marr, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Marusic, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Mernick, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Michnoff, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Montag, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Morris, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Narayan, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Nayak, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Nemesure, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pile, P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Poblaguev, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ranjbar, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Robert-Demolaize, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Roser, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Schmidke, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Schoefer, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Severino, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Shrey, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Smith, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Steski, D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tepikian, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Trbojevic, D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tsoupas, N. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wang, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); White, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Yip, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zaltsman, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zeno, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhang, S. Y. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-08-07

    To study low-x shadowing/saturation physics as well as other nuclear effects [1], [2], proton-gold (p-Au, for 5 weeks) and proton-Aluminum (p-Al, for 2 weeks) collisions were provided for experiments in 2015 at the Relativistic Heavy Ion Collider (RHIC), with polarized proton beam in the Blue ring and Au/Al beam in the Yellow ring. The special features of the asymmetric run in 2015 will be introduced. The operation experience will be reviewed as well in the report.

  14. Spin Dependent Collision of Ultracold Metastable Atoms

    CERN Document Server

    Uetake, Satoshi; Doyle, John M; Takahashi, Yoshiro

    2015-01-01

    Spin-polarized metastable atoms of ultracold ytterbium are trapped at high density and their inelastic collisional properties are measured. We reveal that in collisions of Yb(3P2) with Yb(1S0) there is relatively weak inelastic loss, but with a significant spin-dependence consistent with Zeeman sublevel changes as being the dominant decay process. This is in strong contrast to our observations of Yb(3P2)-Yb(3P2) collisional loss, which are, at low field, much more rapid and have essentially no spin dependence. Our results give a guideline to use the 3P2 states in many possible applications.

  15. Studies of Fluctuation Processes in Nuclear Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ayik, Sakir [Tennessee Technological Univ., Cookeville, TN (United States). Dept. of Physics

    2016-04-14

    The standard one-body transport approaches have been extensively applied to investigate heavy-ion collision dynamics at low and intermediate energies. At low energies the approach is the mean-field description of the time-dependent Hartree-Fock (TDHF) theory. At intermediate energies the approach is extended by including a collision term, and its application has been carried out mostly in the semi-classical framework of the Boltzmann-Uhling-Uhlenbeck (BUU) model. The standard transport models provide a good understanding of the average properties of the collision dynamics in terms of the effective interactions in both low and intermediate energies. However, the standard models are inadequate for describing the fluctuation dynamics of collective motion at low energies and disassembling of the nuclear system into fragments at intermediate energies resulting from the growth of density fluctuations in the spinodal region. Our tasks have been to improve the standard transport approaches by incorporating fluctuation mechanisms into the description. There are mainly two different mechanisms for fluctuations: (i) Collisional fluctuations generated by binary nucleon collisions, which provide the dominant mechanism at intermediate energies, and (ii) One-body mechanism or mean-field fluctuations, which is the dominant mechanism at low energies. In the first part of our project, the PI extended the standard transport model at intermediate energies by incorporating collisional mechanism according to the “Generalized Langevin Description” of Mori formalism. The PI and his collaborators carried out a number of applications for describing dynamical mechanism of nuclear multi fragmentations, and nuclear collective response in the semi-classical framework of the approach, which is known as the Boltzmann-Langevin model. In the second part of the project, we considered dynamical description at low energies. Because of the effective Pauli blocking, the collisional dissipation and

  16. Physics of Nuclear Collisions at High Energy

    Energy Technology Data Exchange (ETDEWEB)

    Hwa, Rudolph C. [Univ. of Oregon, Eugene, OR (United States)

    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

  17. Collision strengths for transitions in Ni XIX

    Indian Academy of Sciences (India)

    K M Aggarwal; F P Keenan

    2007-08-01

    In this paper we present calculations of electron impact excitation collision strengths for transitions among the 89 fine-structure levels of the 2s22p6, 2s22p53 ℓ, 2s2p63 ℓ, 2s22p54 ℓ, and 2s2p64 ℓ configurations of Ni XIX, for which flexible atomic code (FAC) has been adopted. Comparisons are made with the earlier available results in the literature, and the anomalies observed have been discussed.

  18. Backward charmonium production in $\\pi N$ collisions

    CERN Document Server

    Pire, B; Szymanowski, L

    2016-01-01

    Hard exclusive backward production of a $J/\\psi$ meson in pion-nucleon collisions is studied in the framework of QCD collinear factorization. In this approach, a hard subprocess amplitude responsible for the production of the heavy quark-antiquark pair factorizes from soft hadronic matrix elements, such as the nucleon distribution amplitude and the pion-to-nucleon transition distribution amplitude. We argue that this reaction mechanism dominates the backward kinematical region for the medium energy pion beam at J-Parc.

  19. Multifragmentation and dynamics in heavy ion collisions

    Indian Academy of Sciences (India)

    R Roy

    2001-07-01

    A midrapidity zone formed in heavy-ion collisions has been investigated through special selections of light particles and intermediate mass fragments detected in the reaction 35Cl on 12C at 43 MeV/nucleon and the reactions 58Ni on 12C, 24Mg, and 197Au at 34.5 MeV/nucleon, and of neutron energy spectra measured in the reaction 35Cl on natTa. Properties of the observables have been examined to characterize the neck-like structure formed between the two reaction partners.

  20. Absorbed Energy in Ship Collisions and Grounding

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    is that the absorbed energy does not depend on the arrangement of the structure, the material properties, and the damage mode.The purpose of the present paper is to establish a new simple relation between the absorbed energy and the destroyed material volume, which can be used as a design tool for analysis of ship......Minorsky's well-known empirical formula, which relates the absorbed energy to the destroyed material volume, has been widely used in analyses of high energy collision and grounding accidents for nearly 40 years. The advantage of the method is its apparent simplcity. Obviously, its drawback...

  1. General collision branching processes with two parameters

    Institute of Scientific and Technical Information of China (English)

    CHEN AnYue; LI JunPing

    2009-01-01

    A new class of branching models, the general collision branching processes with two parameters, is considered in this paper. For such models, it is necessary to evaluate the absorbing probabilities and mean extinction times for both absorbing states. Regularity and uniqueness criteria are firstly established. Explicit expressions are then obtained for the extinction probability vector, the mean extinction times and the conditional mean extinction times. The explosion behavior of these models is investigated and an explicit expression for mean explosion time is established. The mean global holding time is also obtained. It is revealed that these properties are substantially different between the super-explosive and sub-explosive cases.

  2. Jets in Heavy Ion Collisions with CMS

    CERN Document Server

    Salur, Sevil

    2016-01-01

    Jet physics in heavy ion collisions is a rich field which has been rapidly evolving since the first observations of medium interactions at RHIC through back-to-back hadron correlations and at LHC via reconstructed jets. In order to completely characterize the final state via jet-medium interactions and distinguish between competing energy loss mechanisms complementary and robust jet observables are investigated. Latest developments of jet finding techniques and their applications to heavy ion environments are discussed with an emphasis given on experimental results from CMS experiment.

  3. Energy-momentum balance in particle - domain wall perforating collision

    CERN Document Server

    Gal'tsov, D V; Spiirin, P A

    2014-01-01

    We investigate the energy-momentum balance in the perforating collision of a point particle with an infinitely thin planar domain wall within the linearized gravity in arbitrary dimensions. Since the metric of the wall increases with distance, the wall and the particle are never free, and their energy-momentum balance involves not only the instantaneous kinetic momenta, but also the non-local contribution of gravitational stresses. However, careful analysis shows that the stresses can be unambiguously divided between the colliding objects leading to definition of the gravitationally dressed momenta. These take into account for gravity in the same way as the potential energy does in the non-relativistic theory, but our treatment is fully relativistic. Another unusual feature of our problem is the non-vanishing flux of the total energy-momentum tensor through the lateral surface of the world tube. In this case the zero divergence of the energy-momentum tensor does not imply conservation of the total momentum de...

  4. Accelerated Hierarchical Collision Detection for Simulation using CUDA

    DEFF Research Database (Denmark)

    Jørgensen, Jimmy Alison; Fugl, Andreas Rune; Petersen, Henrik Gordon

    2011-01-01

    In this article we present a GPU accelerated, hybrid, narrow phase collision detection algorithm for simulation purposes. The algorithm is based on hierarchical bounding volume tree structures of oriented bounding boxes (OBB) that in the past has shown to be efficient for collision detection. The...

  5. Crabbed Waist Collisions in DAFNE and Super-B Design

    Energy Technology Data Exchange (ETDEWEB)

    Raimondi, P.; Alesini, D.; Biagini, M.E.; Biscari, C.; Boni, R.; Boscolo, M.; Bossi, F.; Buonomo, B.; Clozza, A.; Delle Monache, G.O.; Demma, T.; Di Pasquale, E.; Di Pirro, G.; Drago, A.; Gallo, A.; Ghigo, A.; Guiducci, S.; Ligi, C.; Marcellini, F.; Mazzitelli, Giovanni; Milardi, C.; /Frascati /Orsay, LAL /CERN /Rome III U. /Rome U. /Novosibirsk, IYF /KEK, Tsukuba /INFN, Pisa /INFN, Cosenza /SLAC /Frascati

    2011-11-02

    The new idea of increasing the luminosity of a collider with crab waist collisions and first experimental results from the DA{Phi}NE {Phi}-Factory at LNF, Frascati, using this concept are presented. Consequences for the design of future factories will be discussed. An outlook to the performance reach with crab waist collisions is given, with emphasis on future B Factories.

  6. Bubble chambers in high energy hadron collisions (and vice versa)

    Energy Technology Data Exchange (ETDEWEB)

    Kittel, W. (Dept. Exp. High Energy Physics, Univ. of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen (Netherlands))

    1994-07-01

    The contribution of bubble chambers to the field of high energy hadron collisions during the last 20 years is reviewed and results are compared to those from other types of collisions and to expectations from models based on the quark-parton content of the respective hadrons. ((orig.))

  7. Research on Double Collision Avoidance Mechanism of Ships at Sea

    Directory of Open Access Journals (Sweden)

    XiuYing Bi

    2015-03-01

    Full Text Available When power driven vessels encounter at sea, they need to avoid collision. The definition of right vessel may mislead ships officers think his or her direct navigating has absolute power with this special ship. This paper will define DCPA symbols; give the cause and the method of double collision avoidance mechanism of ships at sea.

  8. 14 CFR 129.18 - Collision avoidance system.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Collision avoidance system. 129.18 Section... § 129.18 Collision avoidance system. Effective January 1, 2005, any airplane you, as a foreign air... Avoidance Systems If you operate in the United States any . . . Then you must operate that airplane with:...

  9. Collision and recombination driven instabilities in variable charged dusty plasmas

    Indian Academy of Sciences (India)

    S Bal; M Bose

    2013-04-01

    The dust-acoustic instability driven by recombination of electrons and ions on the surface of charged and variably-charged dust grains as well as by collisions in dusty plasmas with significant pressure of background neutrals have been theoretically investigated. The recombination driven instability is shown to be dominant in the long wavelength regime even in the presence of dust-neutral and ion-neutral collisions, while in the shorter wavelength regime, the dust-neutral collision is found to play a major role. In an earlier research work, the dust-neutral collision was neglected in comparison to the effect due to the recombination for estimating the dust-acoustic instability; later the other report shows that the recombination effect is negligible in the presence of dust-neutral collisions. In line of this present situation our investigation revealed that the recombination is more important than dust-neutral collisions in laboratory plasma and fusion plasma, while the dust-neutral collision frequency is dominant in the interstellar plasmas. The effects of ion and dust densities and ion streaming on the recombination and collision driven mode in parameter regimes relevant for many experimental studies on dusty plasmas have also been calculated.

  10. Scheduled Collision Avoidance in wireless sensor network using Zigbee

    DEFF Research Database (Denmark)

    Dnyaneshwar, Mantri; Prasad, Neeli R.; Prasad, Ramjee

    2014-01-01

    . This paper proposes the Schedule based Collision Avoidance (SCA) algorithm for finding the tradeoff between reliability and energy efficiency by fusion of CSMA/CA and TDMA techniques in Zigbee/ IEEE802.15.4. It uses the multi-path data propagation for collision avoidance and effective utilization...

  11. Theoretical Concepts for Ultra-Relativistic Heavy Ion Collisions

    CERN Document Server

    McLerran, Larry

    2009-01-01

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

  12. Quarkonia at finite temperature in relativistic heavy-ion collisions

    Indian Academy of Sciences (India)

    Saumen Datta

    2015-05-01

    The behaviour of quarkonia in relativistic heavy-ion collisions is reviewed. After a detailed discussion of the current theoretical understanding of quarkonia in a static equilibriated plasma, we discuss quarkonia yield from the fireball created in ultrarelativistic heavy-ion collision experiments. We end with a brief discussion of the experimental results and outlook.

  13. Using Logistic Regression to Identify Risk Factors Causing Rollover Collisions

    Directory of Open Access Journals (Sweden)

    Essam Dabbour

    2012-12-01

    Full Text Available Rollover collisions are among the most serious collisions that usually result in severe injuries or fatalities. In 2009, there were 8,732 fatal rollover collisions in the United States of America that resulted in the death of 9,833 persons. Those numbers represent approximately 28% and 29% of the total numbers of fatal collisions and fatalities, respectively. The main objective of this paper is to examine the impact of different risk factors that may contribute to this type of serious collisions to help develop countermeasures that limit them. To avoid the bias that may be caused by interactions among different drivers, this analysis focuses on rollover related to single-vehicle collisions so that the behavior of the driver of the collided vehicle can be analyzed more effectively. Logistic regression technique is utilized to analyze single-vehicle rollover collisions that occurred on state and interstate highways in the states of Ohio and Washington in 2009. The results obtained from this analysis have the potential to help decision makers identify different strategies to limit the severity of this type of collisions.

  14. Observation of the Mott effect in heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Gudima, K.; Ploszajczak, M.; Bozek, P.; Danielewicz, P.

    1997-10-01

    The possibility of the observation of the Mott momentum in the distribution of the deuterons produced in the process p + n - d + {gamma} in the first stage of the nuclear collision is presented. The correlation of the hard photon with the deuteron allows to select deuterons produced at the beginning of the collision. (authors).

  15. Some Intensive and Extensive Quantities in High-Energy Collisions

    CERN Document Server

    Tawfik, A

    2013-01-01

    We review the evolution of some statistical and thermodynamical quantities measured in difference sizes of high-energy collisions at different energies. We differentiate between intensive and extensive quantities and discuss the importance of their distinguishability in characterizing possible critical phenomena of nuclear collisions at various energies with different initial conditions.

  16. Cross sections for electron collisions with nitric oxide

    Science.gov (United States)

    Itikawa, Yukikazu

    2016-09-01

    Cross section data are reviewed for electron collisions with nitric oxide. Collision processes considered are total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, ionization, and dissociative electron attachment. After a survey of the literature (up to the end of 2015), recommended values of the cross section are determined, as far as possible.

  17. Switching between alternative responses of the lithosphere to continental collision

    NARCIS (Netherlands)

    Baes, M.; Govers, R.; Wortel, R.

    2011-01-01

    We study possible responses to arc–continent or continent–continent collision using numerical models. Our short-term integration models show that the initial stage of deformation following continental collision is governed by the competition between three potential weakness zones: (1) mantle wedge,

  18. Polarization effects in collisions of. gamma. beams

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, I.F.; Kotkin, G.L.; Panfil' , S.L.; Serbo, V.G.

    1983-10-01

    We study polarization effects in collisions of high energy ..gamma.. beams obtained in the Compton scattering of laser light on electrons (according to the scheme of I. F. Ginzburg et al., Preprint 81-50, IYaF SO AN SSSR, Novosibirsk, 1981, and JETP Letters 34, 491 (1982)). For this we determine the Stokes parameters of the ..gamma.. beams xi/sub i/ and xi-tilde/sub j/ and their average values and as functions of the photon energy and polarization of the initial beams. The quantities that are measurable in ..gamma gamma.. collisions are expressed in terms of the average values , which, in general, are not equal to , which complicates the study of polarization phenomena. In particular, not =0, even for unpolarized electron and laser beams. It is shown that in two important limiting cases roughly-equal. Effects due to correlation between the beams are studied.

  19. Polarization effect in the photon beam collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, I.F. (AN SSSR, Novosibirsk. Inst. Matematiki); Kotkin, G.L.; Panfil' , S.L.; Serbo, V.G. (Novosibirskij Gosudarstvennyj Univ., USSR)

    1983-10-01

    Polarization effects are investigated for collisions of high-energy ..gamma.. beams produced from the Compton scattering of laser light on electrons. To do this, were obtained Stokes parameters Xisub(i), xisub(j) tilde of the ..gamma..-beams, and their average values (xisub(i)), (xisub(j) tilde), as functions of the photon energies and polarizations of the initial beams. The quantities to be measUred in the ..gamma gamma.. collisions are expressed via the average values (xisub(i)xisub(j) tilde), which are in general different from (Hisub(i))(xisub(j) tilde), the fact making the investigation of the polarization effects more complicated. In particular, (xi/sub 3/xi/sub 3/ tilde-xi/sub 11/ tilde) not equal to 0 even if the electron and the laser beams are not Polarized. It is shown that (xisub(i)xisub(j) tilde) approximately (xisub(i))(xisub(j) tilde) for two important limiting cases. Effects due to a correlation between the beams are considered.

  20. 20 years ago: first collisions (at LEP)

    CERN Multimedia

    2009-01-01

    It’s been 20 years since the first electron positron collision at LEP, and I have to confess to a little self-indulgence in my message this week. Back then I was a member of the OPAL collaboration, the first to see collisions at LEP just before midnight on 13 August 1989 and almost exactly one month after the first circulating beam. It was a historic moment, and the atmosphere in the OPAL control room, 100 metres underground, was one of anticipation and excitement. We reported back to the LEP control room, champagne duly arrived, and over the next few hours, all the experiments were recording data. The pilot run was as smooth as it could be, and within weeks we were announcing new physics. It’s interesting to contrast the start-up of LEP with that of the LHC. With the benefit of hindsight, LEP seems to have got going without a hitch, and indeed it was a smooth start. We circulated beam on 14 July, much to the joy of one of our host states, and it was just a month ...

  1. Proton-Nucleus Collisions in the LHC

    CERN Document Server

    Jowett, J M; Baudrenghien, P; Jacquet, D; Lamont, M; Manglunki, D; Redaelli, S; Sapinski, M; Schaumann, M; Solfaroli Camillocci, M; Tomás, R; Uythoven, J; Valuch, D; Versteegen, R; Wenninger, J

    2013-01-01

    Following the high integrated luminosity accumulated in the first two Pb-Pb collision runs in 2010 and 2011, the LHC heavy-ion physics community requested a first run with p-Pb collisions. This almost unprecedented mode of collider operation was not foreseen in the baseline design of the LHC whose two-in-one magnet design imposed equal rigidity and, hence, unequal revolution frequencies, during injection and ramp. Nevertheless, after a successful pilot physics fill in 2012, the LHC provided of p-Pb luminosity per experiment, at an energy of 5.02 TeV per colliding nucleon pair, with several variations of the operating conditions, in early 2013. Together with a companion p-p run at 2.76 TeV, this was the last physics before the present long shutdown. We summarise the beam physics, operational adaptations and strategy that resulted in extremely rapid commissioning. Finally, we give an account of the progress of the run and provide an analysis of the performance.

  2. High Gluon Densities in Heavy Ions Collisions

    CERN Document Server

    Blaizot, Jean-Paul

    2016-01-01

    The early stages of heavy ion collisions are dominated by high density systems of gluons that carry each a small fraction $x$ of the momenta of the colliding nucleons. A distinguishing feature of such systems is the phenomenon of "saturation" which tames the expected growth of the gluon density as the energy of the collision increases. The onset of saturation occurs at a particular transverse momentum scale, the "saturation momentum", that emerges dynamically and that marks the onset of non-linear gluon interactions. At high energy, and for large nuclei, the saturation momentum is large compared to the typical hadronic scale, making high density gluons amenable to a description with weak coupling techniques. This paper reviews some of the challenges faced in the study of such dense systems of small $x$ gluons, and of the progress made in addressing them. The focus is on conceptual issues, and the presentation is both pedagogical, and critical. Examples where high gluon density could play a visible role in hea...

  3. Aerial vehicles collision avoidance using monocular vision

    Science.gov (United States)

    Balashov, Oleg; Muraviev, Vadim; Strotov, Valery

    2016-10-01

    In this paper image-based collision avoidance algorithm that provides detection of nearby aircraft and distance estimation is presented. The approach requires a vision system with a single moving camera and additional information about carrier's speed and orientation from onboard sensors. The main idea is to create a multi-step approach based on a preliminary detection, regions of interest (ROI) selection, contour segmentation, object matching and localization. The proposed algorithm is able to detect small targets but unlike many other approaches is designed to work with large-scale objects as well. To localize aerial vehicle position the system of equations relating object coordinates in space and observed image is solved. The system solution gives the current position and speed of the detected object in space. Using this information distance and time to collision can be estimated. Experimental research on real video sequences and modeled data is performed. Video database contained different types of aerial vehicles: aircrafts, helicopters, and UAVs. The presented algorithm is able to detect aerial vehicles from several kilometers under regular daylight conditions.

  4. Calorimetry Hadronic with semidigital reading based on camera of resistive planes of glass for experiments on collision linear e + e-; Calorimetr@a hadr@nica con lectura semidigital basada en c@mara de planos resistivos de vidrio para experimentos en colisionadores lineales e + e-

    Energy Technology Data Exchange (ETDEWEB)

    Berenguer Antequera, J.

    2015-07-01

    Calorimetry Hadronic with semidigital reading based on camera of resistive planes of glass for experiments on collision linear e + e-. Electron-positron linear colliders have been proposed as next generation particle colliders to complement and extend the physics programme of the LHC (Large Hadron Collider) at CERN. Currently, two projects, ILC (International Linear Collider) and CLIC (Compact LInear Collider), have been suggested by the international community to reach this purpose. The requirements for a detector for both linear colliders are defined by the precision needed to fully exploit the physics potential of these colliders. In particular, one of the most important requirements is an excellent jet energy resolution. This can be achieved with the particle-flow concept in which the overall detector performance for jet reconstruction is optimised by reconstructing each particle individually. For this reason, the calorimeter system has to have unprecedented granularity fulfilling the task of shower separation and providing excellent jet energy resolution and background separation. (Author)

  5. INTEGRAL COLLISION KERNEL FOR THE GROWTH OF AEROSOL PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Hongyong Xie

    2005-01-01

    Integral collision kernel is elucidated using experimental results for titania, silica and alumina nanoparticles synthesized by FCVD process, and titania submicron particles synthesized in a tube furnace reactor. The integral collision kernel was obtained from a particle number balance equation by the integration of collision rates from the kinetic theory of dilute gases for the free-molecule regime, from the Smoluchowski theory for the continuum regime, and by a semi-empirical interpolation for the transition regime between the two limiting regimes. Comparisons have been made on particle size and the integral collision kernel, showing that the predicted integral collision kernel agreed well with the experimental results in Knudsen number range from about 1.5 to 20.

  6. Initial state fluctuations in collisions between light and heavy ions

    CERN Document Server

    Welsh, Kevin; Heinz, Ulrich W

    2016-01-01

    In high energy collisions involving small nuclei (p+p or x+Au collisions where x=p, d, or $^3$He) 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 semi-realistic 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.

  7. An Investigation of Collisions between Fiber Positioning Units in LAMOST

    CERN Document Server

    Liu, Xiao-Jie

    2015-01-01

    The arrangement of the fiber positioning units in LAMOST focal plane may lead to the collisions during the fiber allocation. To avoid these collisions, the soft protection system has to abandon some targets located in the overlapped field of the adjacent fiber units. In this paper, we firstly analyzed the probability of the collisions between fibers and inferred their possible reasons. It is useful to solve the problem of the fiber-positioning units collisions so as to improve LAMOST efficiency. Based on it, a collision handling system is designed by using the master-slave control structure between the micro control unit (MCU) and the microcomputer. The simulated experiments validate that the system can provide real-time inspection and swap the information between the fiber unit controllers and the main controller.

  8. [Electron transfer, ionization, and excitation in atomic collisions]. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    1992-12-31

    Fundamental processes of electron transfer, ionization, and excitation in ion-atom and ion-ion collisions are studied. Attention is focussed on one- and two-electron systems and, more recently, quasi-one-electron systems whose electron-target-ion core can be accurately modeled by one-electron potentials. The basic computational approaches can then be taken with few, if any, approximations, and the underlying collisional mechanisms can be more clearly revealed. At intermediate collision energies (e.g., proton energies for p-He{sup +} collisions on the order of 100 kilo-electron volts), many electronic states are strongly coupled during the collision, a coupled-state approach, such as a coupled-Sturmian-pseudostate approach, is appropriate. At higher collision energies (million electron-volt energies) the coupling is weaker with, however, many more states being coupled together, so that high-order perturbation theory is essential.

  9. Electron loss of fast projectiles in the collisions with molecules

    CERN Document Server

    Matveev, V I; Rakhimov, Kh Yu

    2011-01-01

    The single and multiple electron loss of fast highly charged projectiles in the collisions with neutral molecules are studied within the framework of a nonperturbative approach. The cross sections for single, double, and triple electron losses are calculated for the collision system $Fe^{q+}\\to N_2$ ($q$=24, 25, 26) at the collision energies 10, 100, and 1000 MeV/u. The effects caused by the collision multiplicity and the orientation of the axis of target molecule are treated. It is shown that collision multiplicity effect leads to considerable differences for the cases of perpendicular and parallel orientations of the molecular axes with respect to the direction of the projectile motion, while for chaotic orientation such effect is negligible.

  10. Geocoding police collision report data from California: a comprehensive approach

    Directory of Open Access Journals (Sweden)

    Park Shin

    2009-12-01

    Full Text Available Abstract Background Collision geocoding is the process of assigning geographic descriptors, usually latitude and longitude coordinates, to a traffic collision record. On California police reports, relative collision location is recorded using a highway postmile marker or a street intersection. The objective of this study was to create a geocoded database of all police-reported, fatal and severe injury collisions in the California Statewide Integrated Traffic Records System (SWITRS for years 1997-2006 for use by public agencies. Results Geocoding was completed with a multi-step process. First, pre-processing was performed using a scripting language to clean and standardize street name information. A state highway network with postmile values was then created using a custom tool written in Visual Basic for Applications (VBA in ArcGIS software. Custom VBA functionality was also used to incorporate the offset direction and distance. Intersection and address geocoding was performed using ArcGIS, StreetMap Pro 2003 digital street network, and Google Earth Pro. A total of 142,007 fatal and severe injury collisions were identified in SWITRS. The geocoding match rate was 99.8% for postmile-coded collisions and 86% for intersection-coded collisions. The overall match rate was 91%. Conclusions The availability of geocoded collision data will be beneficial to clinicians, researchers, policymakers, and practitioners in the fields of traffic safety and public health. Potential uses of the data include studies of collision clustering on the highway system, examinations of the associations between collision occurrence and a variety of variables on environmental and social characteristics, including housing and personal demographics, alcohol outlets, schools, and parks. The ability to build maps may be useful in research planning and conduct and in the delivery of information to both technical and non-technical audiences.

  11. Sensor management for collision alert in orbital object tracking

    Science.gov (United States)

    Xu, Peiran; Chen, Huimin; Charalampidis, D.; Shen, Dan; Chen, Genshe; Blasch, Erik; Pham, Khanh

    2011-06-01

    Given the increasingly dense environment in both low-earth orbit (LEO) and geostationary orbit (GEO), a sudden change in the trajectory of any existing resident space object (RSO) may cause potential collision damage to space assets. With a constellation of electro-optical/infrared (EO/IR) sensor platforms and ground radar surveillance systems, it is important to design optimal estimation algorithms for updating nonlinear object states and allocating sensing resources to effectively avoid collisions among many RSOs. Previous work on RSO collision avoidance often assumes that the maneuver onset time or maneuver motion of the space object is random and the sensor management approach is designed to achieve efficient average coverage of the RSOs. Few attempts have included the inference of an object's intent in the response to an RSO's orbital change. We propose a game theoretic model for sensor selection and assume the worst case intentional collision of an object's orbital change. The intentional collision results from maximal exposure of an RSO's path. The resulting sensor management scheme achieves robust and realistic collision assessment, alerts the impending collisions, and identifies early RSO orbital change with lethal maneuvers. We also consider information sharing among distributed sensors for collision alert and an object's intent identification when an orbital change has been declared. We compare our scheme with the conventional (non-game based) sensor management (SM) scheme using a LEO-to-LEO space surveillance scenario where both the observers and the unannounced and unplanned objects have complete information on the constellation of vulnerable assets. We demonstrate that, with adequate information sharing, the distributed SM method can achieve the performance close to that of centralized SM in identifying unannounced objects and making early warnings to the RSO for potential collision to ensure a proper selection of collision avoidance action.

  12. Real-time collision avoidance in space: the GETEX experiment

    Science.gov (United States)

    Freund, Eckhard; Rossmann, Juergen; Schluse, Michael

    2000-10-01

    Intelligent autonomous robotic systems require efficient safety components to assure system reliability during the entire operation. Especially if commanded over long distances, the robotic system must be able to guarantee the planning of safe and collision free movements independently. Therefore the IRF developed a new collision avoidance methodology satisfying the needs of autonomous safety systems considering the dynamics of the robots to protect. To do this, the collision avoidance system cyclically calculates the actual collision danger of the robots with respect to all static and dynamic obstacles in the environment. If a robot gets in collision danger the methodology immediately starts an evasive action to avoid the collision and guides the robot around the obstacle to its target position. This evasive action is calculated in real-time in a mathematically exact way by solving a quadratic convex optimization problem. The secondary conditions of this optimization problem include the potential collision danger of the robots kinematic chain including all temporarily attached grippers and objects and the dynamic constraints of the robots. The result of the optimization procedure are joint accelerations to apply to prevent the robot from colliding and to guide it to its target position. This methodology has been tested very successfully during the Japanese/German space robot project GETEX in April 1999. During the mission, the collision avoidance system successfully protected the free flying Japanese robot ERA on board the satellite ETS-VII at all times. The experiments showed, that the developed system is fully capable of ensuring the safety of such autonomous robotic systems by actively preventing collisions and generating evasive actions in cases of collision danger.

  13. Collisions of Dark Matter Axion Stars with Astrophysical Sources

    Energy Technology Data Exchange (ETDEWEB)

    Eby, Joshua [Fermilab; Leembruggen, Madelyn [Cincinnati U.; Leeney, Joseph [Cincinnati U.; Suranyi, Peter [Cincinnati U.; Wijewardhana, L. C.R. [Cincinnati U.

    2017-01-05

    If QCD axions form a large fraction of the total mass of dark matter, then axion stars could be very abundant in galaxies. As a result, collisions with each other, and with other astrophysical bodies, can occur. We calculate the rate and analyze the consequences of three classes of collisions, those occurring between a dilute axion star and: another dilute axion star, an ordinary star, or a neutron star. In all cases we attempt to quantify the most important astrophysical uncertainties; we also pay particular attention to scenarios in which collisions lead to collapse of otherwise stable axion stars, and possible subsequent decay through number changing interactions. Collisions between two axion stars can occur with a high total rate, but the low relative velocity required for collapse to occur leads to a very low total rate of collapses. On the other hand, collisions between an axion star and an ordinary star have a large rate, $\\Gamma_\\odot \\sim 3000$ collisions/year/galaxy, and for sufficiently heavy axion stars, it is plausible that most or all such collisions lead to collapse. We identify in this case a parameter space which has a stable region and a region in which collision triggers collapse, which depend on the axion number ($N$) in the axion star, and a ratio of mass to radius cubed characterizing the ordinary star ($M_s/R_s^3$). Finally, we revisit the calculation of collision rates between axion stars and neutron stars, improving on previous estimates by taking cylindrical symmetry of the neutron star distribution into account. Collapse and subsequent decay through collision processes, if occurring with a significant rate, can affect dark matter phenomenology and the axion star mass distribution.

  14. Nonplanar ion-acoustic solitons collision in Xe+-F-- SF6- and Ar+-F-- SF6- plasmas

    Science.gov (United States)

    El-Tantawy, S. A.; Carbonaro, P.

    2016-04-01

    The solitons collision in nonplanar (cylindrical and spherical) plasmas consisting of positive ions, two different negative ions, and isothermal electrons is studied. For this purpose, the Poincaré-Lighthill-Kuo (PLK) method is used to obtain two-coupled nonplanar Korteweg-de Vries (nKdV) equations. Also, the nonplanar phase shifts are calculated. The physical parameters of two plasma experiments; namely Xe+-F-- SF6- and Ar+-F-- SF6- are used to examine the properties of the localized pulses and their phase shifts after collision. It is found that the present model gives rise to the propagation of positive and negative pulses. The effects of the total negative ions concentration, the density ratio of the second-negative ions, the temperature ratio, and the geometrical effects on the behavior of solitons collisions and their phase shifts are investigated. Furthermore, it is found that the phase shifts in the case of the Ar+-F-- SF6- plasma are much larger than those of the Xe+-F-- SF6- plasma. Also, for fixed plasma parameters, the solitons collision received the largest phase shift in spherical geometry, followed by the cylindrical and planar geometries.

  15. Wounded nucleon model with realistic nucleon-nucleon collision profile and observables in relativistic heavy-ion collisions

    CERN Document Server

    Rybczyński, Maciej

    2011-01-01

    We investigate the influence of the nucleon-nucleon collision profile (probability of interaction as a function of the nucleon-nucleon impact parameter) in the wounded nucleon model and its extensions on several observables measured in relativistic heavy-ion collisions. We find that the participant eccentricity coefficient, $\\epsilon^\\ast$, as well as the higher harmonic coefficients, $\\epsilon_n^\\ast$, are reduced by 10-20% for mid-peripheral collisions when the realistic (Gaussian) profile is used, as compared to the case with the commonly-used hard-sphere profile. Similarly, the multiplicity fluctuations, treated as the function of the number of wounded nucleons in one of the colliding nuclei, are reduced by 10-20%. This demonstrates that the Glauber Monte Carlo codes should necessarily use the realistic nucleon-nucleon collision profile in precision studies of these observables. The Gaussian collision profile is built-in in {\\tt GLISSANDO}.

  16. Heat focussing, granite genesis and inverted metamorphic gradients in continental collision zones

    Science.gov (United States)

    Jaupart, Claude; Provost, Ariel

    1985-05-01

    The thermal conductivity of sedimentary rocks is usually much lower than that of crystalline rocks, gneisses and granites. Continental collision zones are characterized by large-scale thrusts which superpose crystalline basement and sedimentary layers. This leads to heat refraction effects of significant magnitude. Sedimentary layers act as a barrier to the transport of heat. We show that the peculiar geometry of a gently sloping sedimentary layer thrust into more conductive rocks is very efficient in diverting the vertical flux of heat. Temperatures can vary by more than 50% along the horizontal and reach a marked maximum at the top of crystalline layers. These results are in general agreement with the main features of orogenic belts as exemplified by the Himalayas. They explain why the young leucogranites of the Main Central Thrust (MCT) are confined to a narrow belt at the top of the basement slab. They also account for the inverted metamorphic gradient observed there. In a crustal accretionary wedge, folding and thrusting modify the structure of the upper crust, by thickening the sedimentary cover and by introducing sedimentary rocks at depth. This leads to high temperatures at shallow depths in specific places. Les zones de collision continentale se caractérisent par de grands chevauchementsàfaible pendage qui empilent les unes sur les autres des couches de socle cristallin et des couches sédimentaires. Cette structure particulière engendre d'importants effets de réfraction thermique. En effet, leur conductibilitéthermiqueétant normalement bien plus faible que celle des roches cristallines, les formations sédimentaires font office de barrières pour le transfert thermique: le flux de chaleur se trouve fortement dévié. Dans un plan horizontal, la température peut varier de plus de 50%, les maximaétant situésàl'interface supérieur des dalles cristallines. En ces endroits précis, les isothermes profonds remontent très significativement. Ces r

  17. The collision that changed the world

    Directory of Open Access Journals (Sweden)

    Wally Broecker

    2015-07-01

    Full Text Available Abstract In connection with the Anthropocene, one might ask how climate is likely to evolve in the absence of man’s intervention and whether humans will be able to purposefully alter this course. In this commentary, I deal with the situation for very long time scales. I make a case that fifty million years ago, the collision between the northward drifting Indian land mass and Asia set the Earth’s climate on a new course. Ever since then, it has cooled. In the absence of some other dramatic disruption in the movement of the plates which make up our planet’s crust, on the time scale of tens of millions of years, this drift would cause the Earth to freeze over as it did during the late Precambrian. Evidence for this change in course comes from records of oxygen and lithium isotopic composition of foraminifer shells. It is reinforced by records of Mg to Ca in halite-hosted fluid inclusions and in marine CaCO3. In addition, the collision appears to have created abrupt changes in the sulfur isotope composition of marine barite and the carbon isotope composition of amber. Not only did this collision create the Himalaya, but more important, it led to a reorganization of the crustal plate motions. Through some combination of the building of mountains and lowering of sea level, these changes generated a mismatch between the supply of CO2 by planetary outgassing and that of calcium by the weathering of silicate rock. The tendency toward an oversupply of calcium has been compensated by a drawdown of the atmosphere’s CO2 content. This drawdown cooled the Earth, slowing down the supply of calcium. Although we are currently inadvertently compensating for this cooling by burning fossil fuels, the impacts of this CO2 on Earth climate will last no more than a tenth of a million years. So, if humans succeed in avoiding extinction, there will likely be a long-term effort to warm the planet.

  18. Dielectron production in proton-proton collisions with ALICE

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, Markus Konrad

    2015-10-01

    Ultrarelativistic hadron collisions, such as delivered since a couple of years at the Large Hadron Collider (LHC), provide new insights into the properties of strongly interacting matter at high temperatures and densities, which is expected to have existed a few of a millionth seconds after the big bang. Electromagnetic probes, such as leptons and photons, are emitted during the entire collision. Since they do not undergo strong interactions, they reflect the entire evolution of the collision. Pairs of leptons, so called dileptons, have the advantage compared to real photons, that they do not only carry momentum, but also have a non-zero invariant mass. The invariant mass spectrum of dileptons is a superposition of several components and allows to address different characteristics of the medium. To understand dielectron production in heavy-ion collisions, reference measurements in proton-proton (pp) collisions are necessary. pp collisions reflect the vacuum contribution of the particles produced in heavy-ion collisions. The analysis of pp collisions is an essential step towards the extraction of medium influences on the vector meson spectral functions and the thermal radiation in heavy-ion collisions. In this thesis, the production of electron-positron pairs (dielectrons) in pp collisions at a collision energy of 7 TeV in the ALICE central barrel is analysed. ALICE has unique particle identification capabilities at low momentum. Electrons and positrons are identified with a high purity and combined to pairs. The invariant mass distribution of dielectrons is corrected for detector effects and the selection criteria in the analysis with Monte Carlo simulations. The dielectron invariant mass spectrum of known hadronic sources is calculated based on the cross sections measured in other decay channels using the known decay kinematics. This so called hadronic cocktail represents the dielectron spectrum at the moment of kinematic freeze-out and can be compared to the

  19. Study on Collision Between Two Ships Using Selected Parameters in Collision Simulation

    Institute of Scientific and Technical Information of China (English)

    Dong-Myung Bae; Aditya Rio Prabowo; Bo Cao; Ahmad Fauzan Zakki; Gunawan Dwi Haryadi

    2016-01-01

    In the present analysis, several parameters used in a numerical simulation are investigated in an integrated study to obtain their influence on the process and results of this simulation. The parameters studied are element formulation, friction coefficient, and material model. Numerical simulations using the non-linear finite element method are conducted to produce virtual experimental data for several collision scenarios. Pattern and size damages caused by collision in a real accident case are assumed as real experimental data, and these are used to validate the method. The element model study performed indicates that the Belytschko-Tsay element formulation should be recommended for use in virtual experiments. It is recommended that the real value of the friction coefficient for materials involved is applied in simulations. For the study of the material model, the application of materials with high yield strength is recommended for use in the side hull structure.

  20. Fragmentation of the C60 molecule in collision with light ions studied by a multi-correlation technique. Cross-sections, electron spectroscopy; Fragmentation de la molecule C60 par impact d'ions legers etudiee en multicorrelation. Sections efficaces, spectroscopie d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Rentenier, A

    2004-04-01

    A quantitative study of the C60 fullerenes fragmentation in collision with light ions (H{sub n}{sup +} with n=1,2,3, He{sup q+} with q=1,2) in the velocity range 0,1 - 2,3 u.a.) is presented. The multi-correlation technique, developed between fragment ions and electrons with well defined energy, has enlightened some of the dependences and properties of fragmentation mechanisms (cross sections, electron spectroscopy, size distributions, kinetic energy of fragment ions, Campi's scatter plot, activation energies). The deposited energy hence appeared as an important parameter. Cross sections have been measured, for the first time, for all the collisional processes. Ionisation and capture only depends on the collision velocity. On the other hand, scaling laws with the deposited energy have been observed for the cross sections of multifragmentation, which depends on the collision energy and the nature of the projectile. The deposited energy has also been found as an essential parameter to understand the evolution of the charged fragment size distributions. The electron spectroscopy, achieved at an emission angle of 35 degrees, showed spectra peaked at important energies (from 5 to 20 eV). The spectra shape depends on the collision velocity. A first theoretical analysis points out the link between the observed energy distribution and the presence of a centrifugal potential barrier. Finally, correlation experiments between produced ions and electron energy reveal that electron energy increases with internal energy. (author)

  1. Advances and challenges in electron molecule scattering physics—A Report of the 14th International Symposium on Electron Molecule Collisions and Swarms

    Science.gov (United States)

    Khakoo, M. A.; Lima, M. A. P.; Tennyson, J.

    2006-07-01

    A report is presented of the 13th International Symposium on Electron Molecule Collisions Physics (Instituto de Fisica, Unicamp, Campinas, Brazil, 27 30 July 2005). This workshop covered low-energy electron interactions with atoms, molecules and condensed matter systems. Several important aspects of this symposium were to bring together theory and experimental advances in this field for gaseous targets as well as showcasing the increasing diversity of electron molecule collision applications in condensed matter and biological applications. A summary session was held wherein were discussed aspects of the future of the field, including the development of new theoretical and experimental capabilities.

  2. Head-on collision and overtaking collision between an envelope solitary wave and a KdV solitary wave in a dusty plasma.

    Science.gov (United States)

    Zhang, Heng; Duan, Wen-Shan; Qi, Xin; Yang, Lei

    2016-02-12

    Head-on collision and overtaking collision between a KdV solitary wave and an envelope solitary wave are first studied in present paper by using Particle-in-cell (PIC) method in a dusty plasma. There are phase shifts of the KdV solitary wave in both head-on collision and the overtaking collision, while no phase shift is found for the envelop solitary wave in any cases. The remarkable difference between head-on collision and the overtaking collision is that the phase shift of KdV solitary wave increases as amplitude of KdV solitary wave increases in head-on collision, while it decreases as amplitude of the KdV solitary wave increases in the overtaking collision. It is found that the maximum amplitude during the collision process is less than sum of two amplitudes of both solitary waves, but is larger than either of the amplitude.

  3. Molecular dynamics and binary collision modeling of the primary damage state of collision cascades

    DEFF Research Database (Denmark)

    Heinisch, H.L.; Singh, B.N.

    1992-01-01

    Quantitative information on defect production in cascades in copper obtained from recent molecular dynamics simulations is compared to defect production information determined earlier with a model based on the binary collision approximation (BCA). The total numbers of residual defects, the fracti...... that is practical for simulating much higher energies and longer times than MD alone can achieve. The extraction of collisional phase information from MD simulations and the correspondence of MD and BCA versions of the collisional phase is demonstrated at low energy....

  4. Differential cross sections of positron hydrogen collisions

    Institute of Scientific and Technical Information of China (English)

    于荣梅; 濮春英; 黄晓玉; 殷复荣; 刘旭焱; 焦利光; 周雅君

    2016-01-01

    We make a detailed study on the angular differential cross sections of positron–hydrogen collisions by using the momentum-space coupled-channels optical (CCO) method for incident energies below the H ionization threshold. The target continuum and the positronium (Ps) formation channels are included in the coupled-channels calculations via a complex equivalent-local optical potential. The critical points, which show minima in the differential cross sections, as a function of the scattering angle and the incident energy are investigated. The resonances in the angular differential cross sections are reported for the first time in this energy range. The effects of the target continuum and the Ps formation channels on the different cross sections are discussed.

  5. Signatures of massive collisions in debris discs

    CERN Document Server

    Kral, Quentin; Augereau, Jean-Charles; Boccaletti, Anthony; Charnoz, Sebastien

    2014-01-01

    Violent stochastic collisional events have been invoked as a possible explanation for some debris discs displaying pronounced asymmetries or having a great luminosity excess. So far, no thorough modelling of the consequences of such events has been carried out, mainly because of the extreme numerical challenge of coupling the dynamical and collisional evolution of dust. We perform the first fully self-consistent modelling of the aftermath of massive breakups in debris discs. We follow the collisional and dynamical evolution of dust released after the breakup of a Ceres-sized body at 6 AU from its central star. We investigate the duration, magnitude and spatial structure of the signature left by such a violent event, as well as its observational detectability. We use the recently developed LIDT-DD code (Kral et al., 2013), which handles the coupled collisional and dynamical evolution of debris discs. The main focus is placed on the complex interplay between destructive collisions, Keplerian dynamics and radiat...

  6. Vector Meson Production in Collisions of Nucleons

    Science.gov (United States)

    Brinkmann, K.-Th.; Abdel-Bary, M.; Abdel-Samad, S.; Clement, H.; Doroshkevich, E.; Dshemuchadse, S.; Dutz, H.; Ehrhardt, K.; Erhardt, A.; Eyrich, W.; Filippi, A.; Freiesleben, H.; Fritsch, M.; Georgi, J.; Gillitzer, A.; Gonser, P.; Jäkel, R.; Karsch, L.; Kilian, K.; Koch, H.; Kreß, J.; Kuhlmann, E.; Marcello, S.; Meyer, W.; Michel, P.; Morsch, H. P.; Möller, K.; Mörtel, H.; Naumann, L.; Pinna, L.; Pizzolotto, L.; Roderburg, E.; Schamlott, A.; Schönmeier, P.; Schroeder, W.; Schulte-Wissermann, M.; Sefzick, T.; Steinke, M.; Stinzing, F.; Sun, G. Y.; Ucar, A.; Ullrich, W.; Wagner, G. J.; Wagner, M.; Wilms, A.; Wintz, P.; Wirth, S.; Wüstner, P.; Zupranski, P.

    The production of vector mesons in collisions between nucleons is studied in order to address a variety of issues concerning nucleon-nucleon interaction, reaction mechanism and properties of baryons. These studies are summarized with emphasis on the most recent experiments at the Time-of-Flight spectrometer TOF and results obtained at the COoler SYnchrotron COSY in Jülich. While currently the open questions regarding the so-called OZI violation, its relation to the meson exchange picture and the relative importance of contributions to the production mechanism from various channels within this formalism are still unresolved, the present-day experiments hold the potential to clarify the situation greatly. Possible extensions of the experimental program on vector mesons using 4π detection techniques for charged as well as neutral particles, in particular π0, are discussed.

  7. Coalescence and Collisions of Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Eduardo Pérez-Tijerina

    2011-01-01

    Full Text Available We study the assembling of small gold clusters subject to collisions and close contact coalescence by using molecular dynamics simulations to simulate events that occur typically in the sputtering process of synthesis. Our results support the notion that the kinetics of coalescence processes strongly determine the geometry and structure of the final particle. While impact velocities, relative orientations, and the initial shape of the interacting particles are unlikely to strictly determine the structural details of the newly formed particle, we found that high initial temperatures and/or impact velocities increase the probability of appearance of icosahedral-like structures, Wulff polyhedra are likely to be formed as a product of the interactions between nanospheres, while the appearance of fcc particles of approximately cuboctahedral shape is mainly due to the interaction between icosahedra.

  8. Slepton production in polarized hadron collisions

    Energy Technology Data Exchange (ETDEWEB)

    Bozzi, G. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier/CNRS-IN2P3, 53 Avenue des Martyrs, F-38026 Grenoble (France); Fuks, B. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier/CNRS-IN2P3, 53 Avenue des Martyrs, F-38026 Grenoble (France); Klasen, M. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier/CNRS-IN2P3, 53 Avenue des Martyrs, F-38026 Grenoble (France)]. E-mail: klasen@lpsc.in2p3.fr

    2005-03-10

    We calculate cross sections and asymmetries for slepton pair production through neutral and charged electroweak currents in polarized hadron collisions for general slepton masses and including mixing of the left- and right-handed interaction eigenstates relevant for third generation sleptons. Our analytical results confirm and extend a previous calculation. Numerically, we show that measurements of the longitudinal single-spin asymmetry at the existing polarized pp collider RHIC and at possible polarization upgrades of the Tevatron or the LHC would allow for a determination of the tau slepton mixing angle and/or the associated supersymmetry breaking parameters {lambda} for gauge mediation and A{sub 0} for minimal supergravity. Furthermore, the Standard Model background from tau pair production can be clearly distinguished due to the opposite sign of the associated asymmetry.

  9. Slepton production in polarized hadron collisions

    CERN Document Server

    Bozzi, G; Klasen, M

    2005-01-01

    We calculate cross sections and asymmetries for slepton pair production through neutral and charged electroweak currents in polarized hadron collisions for general slepton masses and including mixing of the left- and right-handed interaction eigenstates relevant for third generation sleptons. Our analytical results confirm and extend a previous calculation. Numerically, we show that measurements of the longitudinal single-spin asymmetry at the existing polarized pp collider RHIC and at possible polarization upgrades of the Tevatron or the LHC would allow for a determination of the tau slepton mixing angle and/or the associated supersymmetry breaking parameters Lambda for gauge mediation and A0 for minimal supergravity. Furthermore, the Standard Model background from tau pair production can be clearly distinguished due to the opposite sign of the associated asymmetry.

  10. Hadron Production in Heavy Ion Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, Hans Georg; Xu, Nu

    2009-05-19

    Heavy ion collisions are an ideal tool to explore the QCD phase diagram. The goal is to study the equation of state (EOS) and to search for possible in-medium modifications of hadrons. By varying the collision energy a variety of regimes with their specific physics interest can be studied. At energies of a few GeV per nucleon, the regime where experiments were performed first at the Berkeley Bevalac and later at the Schwer-Ionen-Synchrotron (SIS) at GSI in Darmstadt, we study the equation of state of dense nuclear matter and try to identify in-medium modifications of hadrons. Towards higher energies, the regime of the Alternating Gradient Synchrotron (AGS) at the Brookhaven National Laboratory (BNL), the Super-Proton Synchrotron (SPS) at CERN, and the Relativistic Heavy Ion Collider (RHIC) at BNL, we expect to produce a new state of matter, the Quark-Gluon Plasma (QGP). The physics goal is to identify the QGP and to study its properties. By varying the energy, different forms of matter are produced. At low energies we study dense nuclear matter, similar to the type of matter neutron stars are made of. As the energy is increased the main constituents of the matter will change. Baryon excitations will become more prevalent (resonance matter). Eventually we produce deconfined partonic matter that is thought to be in the core of neutron stars and that existed in the early universe. At low energies a great variety of collective effects is observed and a rather good understanding of the particle production has been achieved, especially that of the most abundantly produced pions and kaons. Many observations can be interpreted as time-ordered emission of various particle species. It is possible to determine, albeit model dependent, the equation of state of nuclear matter. We also have seen indications, that the kaon mass, especially the mass of the K{sup +}, might be modified by the medium created in heavy ion collisions. At AGS energies and above, emphasis shifts towards

  11. Planet Scattering Around Binaries: Ejections, Not Collisions

    CERN Document Server

    Smullen, Rachel A; Shannon, Andrew

    2016-01-01

    Transiting circumbinary planets discovered by Kepler provide unique insight into binary and planet formation. Several features of this new found population, for example the apparent pile-up of planets near the innermost stable orbit, may distinguish between formation theories. In this work, we determine how planet-planet scattering shapes planetary systems around binaries as compared to single stars. In particular, we look for signatures that arise due to differences in dynamical evolution in binary systems. We carry out a parameter study of N-body scattering simulations for four distinct planet populations around both binary and single stars. While binarity has little influence on the final system multiplicity or orbital distribution, the presence of a binary dramatically effects the means by which planets are lost from the system. Most circumbinary planets are lost due to ejections rather than planet-planet or planet-star collisions. The most massive planet in the system tends to control the evolution. Asid...

  12. Electromagnetic probes in heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    van Hees H.

    2015-01-01

    Full Text Available Due to their penetrating nature, electromagnetic probes, i.e., lepton-antilepton pairs (dileptons and photons are unique tools to gain insight into the nature of the hot and dense medium of strongly-interacting particles created in relativistic heavy-ion collisions, including hints to the nature of the restoration of chiral symmetry of QCD. Of particular interest are the spectral properties of the electromagnetic current-correlation function of these particles within the dense and/or hot medium. The related theoretical investigations of the in-medium properties of the involved particles in both the partonic and hadronic part of the QCD phase diagram underline the importance of a proper understanding of the properties of various hadron resonances in the medium.

  13. Efficient Queue-based CSMA with Collisions

    CERN Document Server

    Shah, Devavrat

    2010-01-01

    Recently there has been considerable interest in the design of efficient carrier sense multiple access(CSMA) protocol for wireless network. The basic assumption underlying recent results is availability of perfect carrier sense information. This allows for design of continuous time algorithm under which collisions are avoided. The primary purpose of this note is to show how these results can be extended in the case when carrier sense information may not be perfect, or equivalently delayed. Specifically, an adaptation of algorithm in Rajagopalan, Shah, Shin (2009) is presented here for time slotted setup with carrier sense information available only at the end of the time slot. To establish its throughput optimality, in additon to method developed in Rajagopalan, Shah, Shin (2009), understanding properties of stationary distribution of a certain non-reversible Markov chain as well as bound on its mixing time is essential. This note presents these key results. A longer version of this note will provide detailed...

  14. Jet Structure in Heavy Ion Collisions

    CERN Document Server

    Blaizot, Jean-Paul

    2015-01-01

    We review recent theoretical developments in the study of the structure of jets that are produced in ultra relativistic heavy ion collisions. The core of the review focusses on the dynamics of the parton cascade that is induced by the interactions of a fast parton crossing a quark-gluon plasma. We recall the basic mechanisms responsible for medium induced radiation, underline the rapid disappearance of coherence effects, and the ensuing probabilistic nature of the medium induced cascade. We discuss how large radiative corrections modify the classical picture of the gluon cascade, and how these can be absorbed in a renormalization of the jet quenching parameter $\\hat q $. Then, we analyze the (wave)-turbulent transport of energy along the medium induced cascade, and point out the main characteristics of the angular structure of such a cascade. Finally, color decoherence of the in-cone jet structure is discussed. Modest contact with phenomenology is presented towards the end of the review.

  15. Dilepton Production in Heavy-Ion Collisions

    CERN Document Server

    Rapp, R

    2013-01-01

    The properties of electromagnetic radiation from hot fireballs as created in ultra-relativistic heavy-ion collisions are reviewed. We first outline how the medium effects in the electromagnetic spectral function, which governs thermal production rates, relate to the (partial) restoration of chiral symmetry. In particular, we show how chiral and QCD sum rules, together with constraints from lattice QCD, can render these relations quantitative. Turning to dilepton data, we elaborate on updates in the space-time evolution and quark-gluon plasma emission rates from lattice-QCD calculations. With a now available excitation function in dilepton spectra from the RHIC beam-energy scan connecting down to SPS energies, we argue that a consistent interpretation of dilepton data emerges. Combining well-constrained space-time evolutions with state-of-the-art emission rates identifies most of the radiation to emanate from around the pseudo-critical temperature, and thus confirms resonance melting as the prevalent mechanism...

  16. Identifying multiquark hadrons from heavy ion collisions.

    Science.gov (United States)

    Cho, Sungtae; Furumoto, Takenori; Hyodo, Tetsuo; Jido, Daisuke; Ko, Che Ming; Lee, Su Houng; Nielsen, Marina; Ohnishi, Akira; Sekihara, Takayasu; Yasui, Shigehiro; Yazaki, Koichi

    2011-05-27

    Identifying hadronic molecular states and/or hadrons with multiquark components either with or without exotic quantum numbers is a long-standing challenge in hadronic physics. We suggest that studying the production of these hadrons in relativistic heavy ion collisions offers a promising resolution to this problem as yields of exotic hadrons are expected to be strongly affected by their structures. Using the coalescence model for hadron production, we find that, compared to the case of a nonexotic hadron with normal quark numbers, the yield of an exotic hadron is typically an order of magnitude smaller when it is a compact multiquark state and a factor of 2 or more larger when it is a loosely bound hadronic molecule. We further find that some of the newly proposed heavy exotic states could be produced and realistically measured in these experiments.

  17. Bubble collisions and measures of the multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Salem, Michael P., E-mail: salem@cosmos.phy.tufts.edu [Department of Physics, Stanford University, Stanford, CA 94305 (United States)

    2012-01-01

    To compute the spectrum of bubble collisions seen by an observer in an eternally-inflating multiverse, one must choose a measure over the diverging spacetime volume, including choosing an ''initial'' hypersurface below which there are no bubble nucleations. Previous calculations focused on the case where the initial hypersurface is pushed arbitrarily deep into the past. Interestingly, the observed spectrum depends on the orientation of the initial hypersurface, however one's ability observe the effect rapidly decreases with the ratio of inflationary Hubble rates inside and outside one's bubble. We investigate whether this conclusion might be avoided under more general circumstances, including placing the observer's bubble near the initial hypersurface. We find that it is not. As a point of reference, a substantial appendix reviews relevant aspects of the measure problem of eternal inflation.

  18. General collision branching processes with two parameters

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A new class of branching models,the general collision branching processes with two parameters,is considered in this paper.For such models,it is necessary to evaluate the absorbing probabilities and mean extinction times for both absorbing states.Regularity and uniqueness criteria are firstly established.Explicit expressions are then obtained for the extinction probability vector,the mean extinction times and the conditional mean extinction times.The explosion behavior of these models is investigated and an explicit expression for mean explosion time is established.The mean global holding time is also obtained.It is revealed that these properties are substantially different between the super-explosive and sub-explosive cases.

  19. Vector correlations in rotationally inelastic molecular collisions

    Energy Technology Data Exchange (ETDEWEB)

    Lemeshko, Mikhail

    2011-04-13

    The thesis presents an analytic model that describes scalar and vector properties of molecular collisions, both field-free and in fields. The model is based on the sudden approximation and treats molecular scattering as the Fraunhofer diffraction of matter waves from the hard-core part of the interaction potential. The theory has no fitting parameters and is inherently quantum, rendering fully state- and energy-resolved scattering amplitudes and all the quantities that unfold from them in analytic form. This allows to obtain complex polarization moments inherent to quantum stereodynamics, and to account for interference and other non-classical effects. The simplicity and analyticity of the model paves a way to understanding the origin of the features observed in experiment and exact computations, such as the angular oscillations in the state-to-state differential cross sections and the polarization moments, the rotational-state dependent variation of the integral cross sections, and change of these quantities as a function of the applied field. The theory was applied to study the k - k{sup '} vector correlation (differential cross section) for the following collision systems: Ar-NO(X{sup 2}{pi}) and Ne-OCS(X{sup 1}{sigma}) in an electrostatic field, Na{sup +}-N{sub 2}(X{sup 1}{sigma}) in a laser field, and He-CaH({sup 2}{sigma}), He-O{sub 2}(X{sup 3}{sigma}), and He-OH(X{sup 2}{pi}) in a magnetic field. The model was able to reproduce the behavior of the differential cross sections and their variation with field strength. Combining the Fraunhofer model with the quantum theory of vector correlations made it possible to study three- and four-vector properties. The model results for the k-k{sup '}-j{sup '} vector correlation in Ar-NO(X{sup 2}{pi}) and He-NO(X{sup 2}{pi}) scattering were found to be in good agreement with experiment and exact computations. This allowed to demonstrate that the stereodynamics of such collisions is contained solely in the

  20. Muon pair production in relativistic nuclear collisions

    CERN Document Server

    Hencken, K; Serbo, V G

    2006-01-01

    The exclusive production of one $\\mu^+\\mu^-$ pair in collisions of two ultra-relativistic nuclei is considered. We present the simple method for calculation of the Born cross section for this process. Then we found that the Coulomb corrections to this cross section (which correspond to multi-photon exchange of the produced $\\mu^{\\pm}$ with nuclei) are small while the unitarity corrections are large. This is in sharp contrast to the exclusive $e^+e^-$ pair production where the Coulomb corrections to the Born cross section are large while the unitarity corrections are small. We calculated also the cross section for the production of one $\\mu^+\\mu^-$ pair and several $e^+e^-$ pairs in the leading logarithmic approximation. Using this cross section we found that the inclusive production of $\\mu^+\\mu^-$ pair coincides in this approximation with its Born value.

  1. Particle Ratios in Heavy-Ion Collisions

    CERN Document Server

    Tawfik, A

    2005-01-01

    In the framework of the statistical models, we calculated different particle ratios in the energy range \\hbox{$3.5$} ratios. We find within the statistical acceptance that the different peaks are located at one value of energy, $\\sqrt{s_{NN}}^{(c)}\\simeq7.5 $GeV. This energy value is corresponding to baryo-chemical potential of $\\mu_B\\simeq0.43 $GeV. We also found that a maximum entropy per particle is allocated at the same collision energy. The saddle-point in the entropy per particle likely refers to the critical endpoint which connects the first-order phase transition with the cross-over.

  2. Trending in Probability of Collision Measurements

    Science.gov (United States)

    Vallejo, J. J.; Hejduk, M. D.; Stamey, J. D.

    2015-01-01

    A simple model is proposed to predict the behavior of Probabilities of Collision (P(sub c)) for conjunction events. The model attempts to predict the location and magnitude of the peak P(sub c) value for an event by assuming the progression of P(sub c) values can be modeled to first order by a downward-opening parabola. To incorporate prior information from a large database of past conjunctions, the Bayes paradigm is utilized; and the operating characteristics of the model are established through a large simulation study. Though the model is simple, it performs well in predicting the temporal location of the peak (P(sub c)) and thus shows promise as a decision aid in operational conjunction assessment risk analysis.

  3. Total Probability of Collision as a Metric for Finite Conjunction Assessment and Collision Risk Management

    Science.gov (United States)

    Frigm, Ryan C.; Hejduk, Matthew D.; Johnson, Lauren C.; Plakalovic, Dragan

    2015-01-01

    On-orbit collision risk is becoming an increasing mission risk to all operational satellites in Earth orbit. Managing this risk can be disruptive to mission and operations, present challenges for decision-makers, and is time-consuming for all parties involved. With the planned capability improvements to detecting and tracking smaller orbital debris and capacity improvements to routinely predict on-orbit conjunctions, this mission risk will continue to grow in terms of likelihood and effort. It is very real possibility that the future space environment will not allow collision risk management and mission operations to be conducted in the same manner as it is today. This paper presents the concept of a finite conjunction assessment-one where each discrete conjunction is not treated separately but, rather, as a continuous event that must be managed concurrently. The paper also introduces the Total Probability of Collision as an analogous metric for finite conjunction assessment operations and provides several options for its usage in a Concept of Operations.

  4. Heavy flavour production at CMS in heavy ion collisions

    CERN Document Server

    Nguyen, Matthew

    2015-01-01

    We review recent results relating to beauty production in heavy-ion collisions, in both the closed and open heavy flavor sectors, from the CMS experiment at the LHC. The sequential suppression of the ° states in PbPb collisions is thought to be evidence of the dissociation of quarkonia bound states in deconfined matter. Data from pPb collisions demonstrate that while cold nuclear effects appear to be subdominant in minimum bias collisions, there exists a non-trivial dependence on collision multiplicity that remains to be understood. The suppression of high p T particles in heavy-ion collisions, relative to the expectation from pp collisions, is typically interpreted in terms of energy loss of hard scattered parton in the dense nuclear medium. The flavor dependence of the energy loss may be accessed via measurements of b hadrons and b-tagged jets. Measurement of B mesons, via non-prompt J = y , at relatively low p T indicate a smaller suppression factor than D meson or inclusive charged hadrons. Data on b jet...

  5. Experimental observation of the collision of three vortex rings

    Science.gov (United States)

    Hernández, R. H.; Monsalve, E.

    2015-06-01

    We investigate for the first time the motion, interaction and simultaneous collision between three initially stable vortex rings arranged symmetrically, making an angle of 120 degrees between their straight path lines. We report results with laminar vortex rings in air and water obtained through measurements of the ring velocity field with a hot-wire anemometer, both in free flight and during the entire collision. In the air experiment, our flow visualizations allowed us to identify two main collision stages. A first ring-dominated stage where the rings slowdown progressively, increasing their diameter rapidly, followed by secondary vortex structures resulting after the rings make contact. Local portions of the vortex tubes of opposite circulation are coupled together thus creating local arm-like vortex structures moving radially in outward directions, rapidly dissipating kinetic energy. From a similar water experiment, we provide detailed shadowgraph visualizations of both the ring bubble and the full size collision, showing clearly the final expanding vortex structure. It is accurately resolved that the physical contact between vortex ring tubes gives rise to three symmetric expanding vortex arms but also the vortex reconnection of the top and lower vortex tubes. The central collision zone was found to have the lowest kinetic energy during the entire collision and therefore it can be identified as a safe zone. The preserved collision symmetries leading to the weak kinematic activity in the safe zone is the first step into the development of an intermittent hydrodynamic trap for small and lightweight particles.

  6. Modelling seabird collision risk with off-shore wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Mateos, Maria; Arroyo, Gonzalo Munoz; Rosario, Jose Juan Alonso del

    2011-07-01

    Full text: Recent concern about the adverse effects of collision mortality of avian migrants at wind farms has highlighted the need to understand bird-wind turbine interactions. Here, a stochastic collision model, based on data of seabird behaviour collected on- site, is presented, as a flexible and easy to take tool to assess the collisions probabilities of off-shore wind farms in a pre-construction phase. The collision prediction model considering the wind farm area as a risk window has been constructed as a stochastic model for avian migrants, based on Monte Carlo simulation. The model calculates the probable number of birds collided per time unit. Migration volume, wind farm dimensions, vertical and horizontal distribution of the migratory passage, flight direction and avoidance rates, between other variables, are taken into account in different steps of the model as the input variables. In order to assess the weighted importance of these factors on collision probability predictions, collision probabilities obtained from the set of scenarios resulting from the different combinations of the input variables were modelled by using Generalised Additive Models. The application of this model to a hypothetical project for erecting a wind farm at the Strait of Gibraltar showed that collision probability, and consequently mortality rates, strongly depend on the values of the avoidance rates taken into account, and the distribution of birds into the different altitude layers. These parameters should be considered as priorities to be addressed in post-construction studies. (Author)

  7. The nature of mutations induced by replication–transcription collisions.

    Science.gov (United States)

    Sankar, T Sabari; Wastuwidyaningtyas, Brigitta D; Dong, Yuexin; Lewis, Sarah A; Wang, Jue D

    2016-07-01

    The DNA replication and transcription machineries share a common DNA template and thus can collide with each other co-directionally or head-on. Replication–transcription collisions can cause replication fork arrest, premature transcription termination, DNA breaks, and recombination intermediates threatening genome integrity. Collisions may also trigger mutations, which are major contributors to genetic disease and evolution. However, the nature and mechanisms of collision-induced mutagenesis remain poorly understood. Here we reveal the genetic consequences of replication–transcription collisions in actively dividing bacteria to be two classes of mutations: duplications/deletions and base substitutions in promoters. Both signatures are highly deleterious but are distinct from the previously well-characterized base substitutions in the coding sequence. Duplications/deletions are probably caused by replication stalling events that are triggered by collisions; their distribution patterns are consistent with where the fork first encounters a transcription complex upon entering a transcription unit. Promoter substitutions result mostly from head-on collisions and frequently occur at a nucleotide that is conserved in promoters recognized by the major σ factor in bacteria. This substitution is generated via adenine deamination on the template strand in the promoter open complex, as a consequence of head-on replication perturbing transcription initiation. We conclude that replication–transcription collisions induce distinct mutation signatures by antagonizing replication and transcription, not only in coding sequences but also in gene regulatory elements.

  8. An Approach Toward Understanding Wildlife-Vehicle Collisions

    Science.gov (United States)

    Litvaitis, John A.; Tash, Jeffrey P.

    2008-10-01

    Among the most conspicuous environmental effects of roads are vehicle-related mortalities of wildlife. Research to understand the factors that contribute to wildlife-vehicle collisions can be partitioned into several major themes, including (i) characteristics associated with roadkill hot spots, (ii) identification of road-density thresholds that limit wildlife populations, and (iii) species-specific models of vehicle collision rates that incorporate information on roads (e.g., proximity, width, and traffic volume) and animal movements. We suggest that collision models offer substantial opportunities to understand the effects of roads on a diverse suite of species. We conducted simulations using collision models and information on Blanding’s turtles ( Emydoidea blandingii), bobcats ( Lynx rufus), and moose ( Alces alces), species endemic to the northeastern United States that are of particular concern relative to collisions with vehicles. Results revealed important species-specific differences, with traffic volume and rate of movement by candidate species having the greatest influence on collision rates. We recommend that future efforts to reduce wildlife-vehicle collisions be more proactive and suggest the following protocol. For species that pose hazards to drivers (e.g., ungulates), identify collision hot spots and implement suitable mitigation to redirect animal movements (e.g., underpasses, fencing, and habitat modification), reduce populations of problematic game species via hunting, or modify driver behavior (e.g., dynamic signage that warns drivers when animals are near roads). Next, identify those species that are likely to experience additive (as opposed to compensatory) mortality from vehicle collisions and rank them according to vulnerability to extirpation. Then combine information on the distribution of at-risk species with information on existing road networks to identify areas where immediate actions are warranted.

  9. Quantal Nucleon Diffusion I: Central Collisions of Symmetric Nuclei

    CERN Document Server

    Ayik, S; Yilmaz, B; Umar, A S

    2016-01-01

    Quantal diffusion mechanism of nucleon exchange is studied in the central collisions of several symmetric heavy-ion collisions in the framework of the Stochastic Mean-Field (SMF) approach. Since at bombarding energies below the fusion barrier, di-nuclear structure is maintained, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Quantal diffusion coefficients, including memory effects, for proton and neutron exchanges are extracted microscopically employing the SMF approach. The quantal calculations of neutron and proton variances are compared with the semi-classical results.

  10. Division B Commission 14 Working Group: Collision Processes

    Science.gov (United States)

    Peach, Gillian; Dimitrijevic, Milan S.; Barklem, Paul S.

    2016-04-01

    Since our last report (Peach & Dimitrijević 2012), a large number of new publications on the results of research in atomic and molecular collision processes and spectral line broadening have been published. Due to the limited space available, we have only included work of importance for astrophysics. Additional relevant papers, not included in this report, can be found in the databases at the web addresses provided in Section 6. Elastic and inelastic collisions between electrons, atoms, ions, and molecules are included, as well as charge transfer in collisions between heavy particles which can be very important.

  11. Thermal, chemical and spectral equilibration in heavy-ion collisions

    CERN Document Server

    Almási, Gábor András

    2014-01-01

    We have considered the equilibration in a relativistic heavy ion collision using our transport model. We applied periodic boundary conditions to close the system in a box. We found that the thermal equilibration takes place in the first 20-40 fm/c which time is comparable to the duration of a heavy ion collision. The chemical equilibration is a much slower process and the system does not equilibrate in a heavy ion collision. We have also shown that the mass spectra of broad resonances immediately follows their in-medium spectral functions.

  12. Soil structure interaction in offshore wind turbine collisions

    DEFF Research Database (Denmark)

    Samsonovs, Artjoms; Giuliani, Luisa; Zania, Varvara

    2014-01-01

    . Dynamic finite element analyses have been performed taking into account the geometric and material nonlinearity of the tower, and the effects of soil structure interaction (SSI) have been studied in two representative collision scenarios of a service vessel with the turbine: a moderate energy impact...... after a ship collision, thus providing an insight on the consequences of a collision event and on the main aspects to be considered when designing for this load case. In particular, the role of the foundation soil properties (site conditions) on the response of the structural system is investigated...

  13. Condensed matter applied atomic collision physics, v.4

    CERN Document Server

    Datz, Sheldon

    1983-01-01

    Applied Atomic Collision Physics, Volume 4: Condensed Matter deals with the fundamental knowledge of collision processes in condensed media.The book focuses on the range of applications of atomic collisions in condensed matter, extending from effects on biological systems to the characterization and modification of solids. This volume begins with the description of some aspects of the physics involved in the production of ion beams. The radiation effects in biological and chemical systems, ion scattering and atomic diffraction, x-ray fluorescence analysis, and photoelectron and Auger spectrosc

  14. Storage rings for investigation of ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Schuch, R.

    1987-08-01

    In this survey, we give a brief description of synchrotron storage rings for heavy ions, and examples for their use in ion-atom collision physics. The compression of the phase space distribution of the ions by electron cooling, and the gain factors of in-ring experiments compared to single-pass experiments are explained. Some examples of a new generation of ion-atom collision experiments which may become feasible with storage rings are given. These include the studies of angular differential single- and double-electron capture cross sections, the production of slow highly charged recoil ions, and atomic collision processes using decelerated and crossed beam. 30 refs.

  15. Transfer ionization in collisions with a fast highly charged ion.

    Science.gov (United States)

    Voitkiv, A B

    2013-07-26

    Transfer ionization in fast collisions between a bare ion and an atom, in which one of the atomic electrons is captured by the ion whereas another one is emitted, crucially depends on dynamic electron-electron correlations. We show that in collisions with a highly charged ion a strong field of the ion has a very profound effect on the correlated channels of transfer ionization. In particular, this field weakens (strongly suppresses) electron emission into the direction opposite (perpendicular) to the motion of the ion. Instead, electron emission is redirected into those parts of the momentum space which are very weakly populated in fast collisions with low charged ions.

  16. Search for Exotic Strange Dibaryon in Relativistic Heavy Ion Collisions

    Institute of Scientific and Technical Information of China (English)

    GAO Chong-Shou

    2003-01-01

    The exotic strange dibaryon particle (ΩΩ)0+ with S = -6 can be produced in relativistic heavyioncollisions. The yields of this kind of exotic strange dibaryon particles can increase significantly soon as the formation ofQGP does exhibit after the collision. If there is no phase transition after the collision, the upper bound of the productionof this diomega can be estimated from the free hadronic gas model for nuclear matter. The relative yield ratio of diomegato deuteron is less than 0.000205, this means that if there is no QGP creation it is difficult to observe the production ofdiomega in relativistic heavy ion collisions.

  17. Crushing of ship bows in head-on collision

    DEFF Research Database (Denmark)

    Ocakli, H.; Zhang, S.; Pedersen, Preben Terndrup

    2004-01-01

    Semi-analytical methods for analysis of plate crushing and ship bow damage in head-on collisions are developed in this paper. Existing experimental and theoretical studies for crushing analysis of plated structures are summarized and compared. Simple formulae for determining the crushing force....... The approach developed can be used easily to determine the crushing resistance and damage extent of the ship bow when ship length and collision speed are known. The method can be used in probabilistic analysis of damage extents in ship collisions where a large number of calculations are generally required....

  18. Gas lasers applied atomic collision physics, v.3

    CERN Document Server

    McDaniel, E W

    1982-01-01

    Applied Atomic Collision Physics, Volume 3: Gas Lasers describes the applications of atomic collision physics in the development of many types of gas lasers. Topics covered range from negative ion formation in gas lasers to high-pressure ion kinetics and relaxation of molecules exchanging vibrational energy. Ion-ion recombination in high-pressure plasmas is also discussed, along with electron-ion recombination in gas lasers and collision processes in chemical lasers.Comprised of 14 chapters, this volume begins with a historical summary of gas laser developments and an overview of the basic ope

  19. Application of Ion and Electron Momentum Imaging to Atomic Collisions

    Science.gov (United States)

    Cocke, C. L.

    2000-06-01

    COLTRIMS (COLd Target Recoil Ion Momentum Spectroscopy) combines fast imaging detectors with a supersonically cooled gas target to allow the charged particles from any ionizing collision, including both recoil ions and electrons, to be collected with extremely high efficiency and with fully measured vector momenta. Since all particles are measured in event mode, the full multi-dimensional momentum space is mapped. We will review several examples of the use of this technique to study two- , three- and four-body final states created in ionizing interactions of photons and charged particles with He and D2 . The momentum spectra of electrons ejected from these targets by slow projectiles reveal the stucture of the molecular orbitals which are promoted into the continuum. Double photoionization of the same targets reveals patterns which can be interpreted in terms of collective coordinates. Two-electron removal from D2 by Xe ^26+ reveals the influence of the projectile field on the dissociation process. A recent application of the technique to ionization by high intensity laser fields will be discussed. Work performed in collaboration with M.A.Abdallah^1, I.Ali^1, Matthias Achler^2, H.Braeuning^2,3, Angela Braeuning-Deminian^2, Achim Czasch^2,3, R.Doerner^2,3, R.DuBois^6, A. Landers^1,5, V.Mergel^2, R.E.Olson^6, T.Osipov^1, M.Prior^3, H.Schmidt-Boecking^2, M.Singh^1, A.Staudte^2,3, T.Weber^2, W.Wolff^4, and H.E.Wolf^4 ^1J.R.Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS 66506; ^2 Institut fuer Kernphysik, Univ. Frankfurt, August-Euler-Str.6,D-60486 Frankfurt, Germany ; ^3Lawrence Berkeley National Laboratory, Berkeley, CA 94720; ^4Instituto de Fisica, Universidade Federal do Rio de Janeiro Caixa Postal 68.528, 21945-970, Rio de Janeiro, Brazil; ^5Physics Dept., Western Michigan University, Kalamazoo, MI 49008; ^6Physics Dept., Univ. Missouri Rolla, Rolla, MO 65409 Work supported by the Division of Chemical Sciences, Office of Basic

  20. A literature review of risk assessment of ship-FPSO collisions

    DEFF Research Database (Denmark)

    Wang, Ge; Pedersen, Preben Terndrup

    2007-01-01

    This paper reviews the state of the art of the research and analysis on the risks of collision with offshore installations. The focus is placed on: existing criteria, FPSO collision accident, design scenarios for FPSO collision, mechanics of collision incidents, and consequences. The content...

  1. The 2011 Dynamics of Molecular Collisions Conference

    Energy Technology Data Exchange (ETDEWEB)

    Nesbitt, David J. [JILA, NIST

    2011-07-11

    The Dynamics of Molecular Collisions Conference focuses on all aspects of molecular collisions--experimental & theoretical studies of elastic, inelastic, & reactive encounters involving atoms, molecules, ions, clusters, & surfaces--as well as half collisions--photodissociation, photo-induced reaction, & photodesorption. The scientific program for the meeting in 2011 included exciting advances in both the core & multidisciplinary forefronts of the study of molecular collision processes. Following the format of the 2009 meeting, we also invited sessions in special topics that involve interfacial dynamics, novel emerging spectroscopies, chemical dynamics in atmospheric, combustion & interstellar environments, as well as a session devoted to theoretical & experimental advances in ultracold molecular samples. Researchers working inside & outside the traditional core topics of the meeting are encouraged to join the conference. We invite contributions of work that seeks understanding of how inter & intra-molecular forces determine the dynamics of the phenomena under study. In addition to invited oral sessions & contributed poster sessions, the scientific program included a formal session consisting of five contributed talks selected from the submitted poster abstracts. The DMC has distinguished itself by having the Herschbach Medal Symposium as part of the meeting format. This tradition of the Herschbach Medal was first started in the 2007 meeting chaired by David Chandler, based on a generous donation of funds & artwork design by Professor Dudley Herschbach himself. There are two such awards made, one for experimental & one for theoretical contributions to the field of Molecular Collision Dynamics, broadly defined. The symposium is always held on the last night of the meeting & has the awardees are asked to deliver an invited lecture on their work. The 2011 Herschbach Medal was dedicated to the contributions of two long standing leaders in Chemical Physics, Professor

  2. Burnup calculation by the method of first-flight collision probabilities using average chords prior to the first collision

    Science.gov (United States)

    Karpushkin, T. Yu.

    2012-12-01

    A technique to calculate the burnup of materials of cells and fuel assemblies using the matrices of first-flight neutron collision probabilities rebuilt at a given burnup step is presented. A method to rebuild and correct first collision probability matrices using average chords prior to the first neutron collision, which are calculated with the help of geometric modules of constructed stochastic neutron trajectories, is described. Results of calculation of the infinite multiplication factor for elementary cells with a modified material composition compared to the reference one as well as calculation of material burnup in the cells and fuel assemblies of a VVER-1000 are presented.

  3. The record of India-Asia collision preserved in Tethyan ocean basin sediments.

    Science.gov (United States)

    Najman, Yani; Jenks, Dan; Godin, Laurent; Boudagher-Fadel, Marcelle; Bown, Paul; Horstwood, Matt; Garzanti, Eduardo; Bracialli, Laura; Millar, Ian

    2015-04-01

    The timing of India-Asia collision is critical to the understanding of crustal deformation processes, since, for example, it impacts on calculations regarding the amount of convergence that needs to be accommodated by various mechanisms. In this research we use sediments originally deposited in the Tethyan ocean basin and now preserved in the Himalayan orogeny to constrain the timing of collision. In the NW Himalaya, a number of workers have proposed a ca 55-50 Ma age for collision along the Indus suture zone which separates India from the Kohistan-Ladakh Intraoceanic Island arc (KLA) to the north. This is based on a number of factors including the age of youngest marine sediments in the Indus suture (e.g. Green et al. 2008), age of eclogites indicative of onset of Indian continental subduction (e.g. de Sigoyer et al. 2000), and first evidence of detritus from north of the suture zone deposited on the Indian plate (e.g. Clift et al. 2002). Such evidence can be interpreted as documenting the age of India-Asia collision if one takes the KLA to have collided with the Asian plate prior to its collision with India (e.g. Petterson 2010 and refs therein). However, an increasing number of workers propose that the KLA collided with Asia subsequent to its earlier collision with India, dated variously at 85 Ma (Chatterjee et al. 2013), 61 Ma (Khan et al. 2009) and 50 Ma (Bouilhol et al. 2013). This, plus the questioning of earlier provenance work (Clift et al. 2002) regarding the validity of their data for constraining timing of earliest arrival of material north of the suture deposited on the Indian plate (Henderson et al. 2011) suggests that the time is right for a reappraisal of this topic. We use a provenance-based approach here, using combined U-Pb and Hf on detrital zircons from Tethyan ocean basin sediments, along with petrography and biostratigraphy, to identify first arrival of material from north of the Indian plate to arrive on the Indian continent, to constrain

  4. Probing superheavy quasimolecular collisions with incoming inner shell vacancies

    Energy Technology Data Exchange (ETDEWEB)

    Verma, P. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany) and JMI University, New Delhi (India) and Vaish College, Rohtak (India)]. E-mail: P.Verma@gsi.de; Mokler, P.H. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); J. Liebig University, Giessen (Germany); Braeuning-Demian, A. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Braeuning, H. [J. Liebig University, Giessen (Germany); Kozhuharov, C. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Bosch, F. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Liesen, D. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Hagmann, S. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); J.W. Goethe University, Frankfurt (Germany); Stoehlker, Th. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Stachura, Z. [Institute for Nuclear Physics, Cracow (Poland); Banas, D. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Swietokrzyska Academy, Kielce (Poland); Orsic-Muthig, A. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Schoeffler, M. [J.W. Goethe University, Frankfurt (Germany); Sierpowski, D. [Jagellonian University, Cracow (Poland); Spillmann, U. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Tashenov, S. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Toleikis, S. [Atomphysik, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Wahab, M.A. [JMI University, New Delhi (India)

    2006-04-15

    With the advanced accelerator technologies used at the SIS/ESR heavy ion facility at GSI, the highest charge states (bare, H-like, etc.) even for the heaviest ions can be provided for experiments at moderate collision velocities (v {sub ion} < v {sub K}). Hence, inner shell vacancies can be provided prior to collisions for the innermost shells of transiently formed superheavy quasimolecules. However, projectile K-vacancies may be destroyed while penetrating solids. The goal of the present investigation is to establish how far at relatively low collision velocities, high incoming ionic charge states do survive in thin solid targets and hence, how far thin solid targets can be utilized for studying superheavy quasimolecules with well-defined, open, incoming, inner shell vacancy channels. The dependence of quasimolecular collisions on projectile charge state (q) and target thickness (t) is studied in very thin Au solid targets for 69 MeV/u U {sup q+} ions (73 {<=} q {<=} 91)

  5. Evidence for collective phenomena in pp collisions with CMS

    CERN Document Server

    Chen, Zhenyu

    2017-01-01

    Observation of long-range ridge-like correlations in high-multiplicity pp collisions opened up new opportunities for exploring novel QCD dynamics in small collision systems. Based on data collected in 2015 and 2016 with the CMS detector at the LHC, the second-order ($v_{2}$) and third-order ($v_{3}$) azimuthal anisotropy harmonics of $K_{s}^{0}$, $\\Lambda$ and inclusive charged particles are extracted from long-range two-particle correlations as functions of particle multiplicity and transverse momentum. For the first time in pp collisions, the $v_{2}$ signals are also extracted from multi-particle correlations, providing direct evidence of the collective nature of observed particle correlations. These results provide new insights on the origin of observed long-range correlations in pp collisions, and may shed light on how quantum fluctuations affect the proton structure at a very short time scale.

  6. Dependence of elastic hadron collisions on impact parameter

    CERN Document Server

    Prochazka, Jiri; Kundrat, Vojtech

    2015-01-01

    Elastic proton-proton collisions represent probably the greatest ensemble of available measured data, the analysis of which may provide large amount of new physical results concerning fundamental particles. However, it is necessary to analyze first some conclusions concerning pp collisions and following from the conviction that the behavior of microscopic objects differs significantly from that of macroscopic ones. It has been argued that elastic hadron collisions have been more central than inelastic ones. However, the given conclusion has started from approaches based on a greater number of simplifying mathematical assumptions (done already in earlier calculations), without their influence on physical interpretation having been analyzed and entitled. This influence has started to be studied in the approach based on eikonal model. The possibility of peripheral interpretation of elastic collisions will be demonstrated and corresponding results summarized. The arguments will be given why no preference may be g...

  7. Robotic Path Finding with Collision Avoidance Using Expert System

    Institute of Scientific and Technical Information of China (English)

    蔡自兴

    1989-01-01

    A rule-based expert system has been developed and used into a robotic planning system with collision-avoidance, The world model is represented as the knowledge data and stored in the knowledge base with rules. The expert system can find a collision-avoidance path . Otherwise, it shows the collision secton in which the moved object is blocked . Several examples for the different objects to pass throngli the different channels and to find a collision-free path have been testnd. The simulating resuks of the planner give out the planning sequence or blocked section(s) . The output information is useful for making decision of the robot motion and modifying the technological parameters of the world .

  8. Robotic Path Finding with Collision Avoidance Using Expert System

    Institute of Scientific and Technical Information of China (English)

    蔡自兴

    1989-01-01

    A rule-based expert system has been developed and used into a robotic planning system with collision-avoidance,The world model is represented as the knowledge data and stored in the knowledge base with rules.The expert system can find a collision-avoidance path.Otherwise.it shows the collision secton in which the moved object is blocked,Several examples for the different objects to pass through the different channels and to find a collision-free path have been tested.The simulating results of the palnner give out the planning sequence or blocked section(s).The output information is useful for making decision of the robot motion and modifyting the technological parameters of the world.

  9. Cumulative pion production via successive collisions in nuclear medium

    CERN Document Server

    Motornenko, A

    2016-01-01

    Production of pions in proton-nucleus (p+A) reactions outside of a kinematical boundary of proton-nucleon collisions, the so-called cumulative effect, is studied. The kinematical restrictions on pions emitted in backward direction in the target rest frame are analyzed. It is shown that cumulative pion production requires a presence of massive baryonic resonances that are produced during successive collisions of projectile with nuclear nucleons. After each successive collision the mass of created resonance may increase and, simultaneously, its longitudinal velocity decreases. Simulations within Ultra relativistic Quantum Molecular Dynamics model reveals that successive collisions of baryonic resonances with nuclear nucleons plays the dominant role in cumulative pion production in p+A reactions.

  10. Application of Machine Vision to Vehicle Automatic Collision Warning Algorithm

    Institute of Scientific and Technical Information of China (English)

    WANG Jiang-feng; GAO Feng; XU Guo-yan; YAO Sheng-zhuo

    2008-01-01

    Using the new technologies such as information technology, communication technology and electronic control technology, vehicle collision warning system(CWS) can acquire road condition, adjacent vehicle march condition as well as its dynamics performance continuously, then it can forecast the oncoming potential collision and give a warning. Based on the analysis of driver's driving behavior, algorithm's warning norms are determined. Based on warning norms adopting machine vision method, the cooperation collision warning algorithm(CWA) model with multi-input and multi-output is established which is used in supporting vehicle CWS. The CWA is tested using the actual data and the result shows that this algorithm can identify and carry out warning for vehicle collision efficiently, which has important meaning for improving the vehicle travel safety.

  11. Improved Collision Search for Hash Functions: New Advanced Message Modification

    Science.gov (United States)

    Naito, Yusuke; Ohta, Kazuo; Kunihiro, Noboru

    In this paper, we discuss the collision search for hash functions, mainly in terms of their advanced message modification. The advanced message modification is a collision search tool based on Wang et al.'s attacks. Two advanced message modifications have previously been proposed: cancel modification for MD4 and MD5, and propagation modification for SHA-0. In this paper, we propose a new concept of advanced message modification, submarine modification. As a concrete example combining the ideas underlying these modifications, we apply submarine modification to the collision search for SHA-0. As a result, we show that this can reduce the collision search attack complexity from 239 to 236 SHA-0 compression operations.

  12. Developing the plate tectonics from oceanic subduction to continental collision

    Institute of Scientific and Technical Information of China (English)

    ZHENG YongFei; YE Kai; ZHANG LiFei

    2009-01-01

    The studies of continental deep subduction and ultrahigh-pressure metamorphism have not only promoted the development of solid earth science in China,but also provided an excellent opportunity to advance the plate tectonics theory.In view of the nature of subducted crust,two types of subduction and collision have been respectively recognized in nature.On one hand,the crustal subduction occurs due to underflow of either oceanic crust (Pacific type) or continental crust (Alpine type).On the other hand,the continental collision proceeds by arc-continent collision (Himalaya-Tibet type) or continent-continent collision (Dabie-Sulu type).The key issues in the future study of continental dynamics are the chemical changes and differential exhumation in continental deep subduction zones,and the temporal-spatial transition from oceanic subduction to continental subduction.

  13. Status of Chemical Equilibrium in Relativistic Heavy Ion Collisions

    CERN Document Server

    Cleymans, Jean

    2009-01-01

    Recent work on chemical equilibrium in heavy ion collisions is reviewed. The energy dependence of thermal parameters is discussed. The centrality dependence of thermal parameters at SPS energies is presented.

  14. Quarkonium production in p–Pb collisions with ALICE

    CERN Document Server

    Lakomov, Igor

    2016-01-01

    The production of quarkonia, bound states of quark and anti-quark pairs, is intensively studied both experimentally and theoretically. They are ideal probes of the Quark-Gluon Plasma (QGP) formed in heavy-ion collisions. At the beginning of 2013, data from p–Pb collisions at sNN=5.02 TeV have been collected by ALICE, which can be exploited to measure cold nuclear matter (CNM) effects on quarkonium production. These measurements are important in order to disentangle, in Pb–Pb collisions, hot and CNM effects. In this paper final ALICE results on the charmonium and bottomonium production in p–Pb collisions from Run I of the LHC are presented. ALICE measurements are compared to various models of CNM effects and to PHENIX measurements.

  15. Experimental overview on small collision systems at the LHC

    Science.gov (United States)

    Loizides, Constantin

    2016-12-01

    These conferences proceedings summarize the experimental findings obtained in small collision systems at the LHC, as presented in the special session on "QGP in small systems?" at the Quark Matter 2015 conference.

  16. Collective phenomena in non-central nuclear collisions

    Energy Technology Data Exchange (ETDEWEB)

    Voloshin, Sergei A.; Poskanzer, Arthur M.; Snellings, Raimond

    2008-10-20

    Recent developments in the field of anisotropic flow in nuclear collision are reviewed. The results from the top AGS energy to the top RHIC energy are discussed with emphasis on techniques, interpretation, and uncertainties in the measurements.

  17. Collisions and turbulence in optical rogue wave formation

    DEFF Research Database (Denmark)

    Genty, G.; de Sterke, C.M.; Bang, Ole

    2010-01-01

    We discuss optical rogue wave generation in terms of collisions and turbulence processes. Simulations of picosecond pulse propagation in optical fibres show rogue soliton generation from either third-order dispersion or Raman scattering independently. Simulations of rogue soliton emergence...

  18. On Rational Design of Double Hull Tanker Structures against Collision

    DEFF Research Database (Denmark)

    Paik, Jeom Kee; Chung, Jang Young; Choe, Ich Hung;

    1999-01-01

    in the present study were (i) developing a framework for the collision design procedure for double hull tanker structures, (ii) experimental investigation of the structural crashworthiness of the collided vessels in collision or stranding, using double skinned structural models, (iii) validation of the special...... National University. The goal of the study has been to establish a rational practical design oriented approach to collision resistance that is more sophisticated than previous theoretically based procedures and less complicated than conventional nonlinear finite element methods. The main tasks undertaken...... investigation of the energy absorption capability characteristics of a collided double hull VLCC side structure in collision, and (vi) development of a new modified Minorsky method for double hull tanker side structures. The tools developed and the results and insights obtained by the present study should...

  19. Multiple electron capture in close ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Schlachter, A.S.; Stearns, J.W.; Berkner, K.H.; Bernstein, E.M.; Clark, M.W.; DuBois, R.D.; Graham, W.G.; Morgan, T.J.; Mueller, D.W.; Stockli, M.P.; Tanis, J.A.; Woodland, W.T. (Lawrence Berkeley Lab., CA (USA); Western Michigan Univ., Kalamazoo, MI (USA); Pacific Northwest Lab., Richland, WA (USA); Queen' s Univ., Belfast, Northern Ireland (UK); Wesleyan Univ., Middletown, CT (USA); University of North Tex

    1989-07-24

    Collisions in which a fast highly charged ion passes within the orbit of K electron of a target gas atom are selected by emission of a K x-ray from the projectile or target. Measurement of the projectile charge state after the collision, in coincidence with the K x-ray, allows measurement of the charge-transfer probability during these close collisions. When the projectile velocity is approximately the same as that of target electrons, a large number of electrons can be transferred to the projectile in a single collision. The electron-capture probability is found to be a linear function of the number of vacancies in the projectile L shell for 47-MeV calcium ions in an Ar target. 18 refs., 9 figs.

  20. Statistical Analysis of Ship Collisions with Bridges in China Waterway

    Institute of Scientific and Technical Information of China (English)

    DAI Tong-yu; NIE Wu; LIU Ying-jie; WANG Li-ping

    2002-01-01

    Having carried out investigations on ship collision accidents with bridges in waterway in China, a database of ship collision with bridge (SCB) is developed in this paper. It includes detailed information about more than 200 accidents near ship's waterways in the last four decades, in which ships collided with the bridges. Based on the information a statistical analysis is presented tentatively. The increase in frequency of ship collision with bridges appears, and the accident quantity of the barge system is more than that of single ship. The main reason of all the factors for ship collision with bridge is the human errors, which takes up 70%. The quantity of the accidents happened during flooding period shows over 3~6 times compared with the period from March to June in a year. The probability follows the normal distribution according to statistical analysis. Visibility, span between piers also have an effect on the frequency of the accidents.