WorldWideScience

Sample records for ion collisions eos-sensitive

  1. LEXUS heavy ion collisions

    CERN Document Server

    Sang Yong Jeon

    1997-01-01

    We use a Glauber-like approach to describe very energetic nucleus- nucleus collisions as a sequence of binary nucleon-nucleon collisions. No free parameters are needed: all the information comes from simple parametrizations of nucleon-nucleon collision data. Produced mesons are assumed not to interact with each other or with the original baryons. Comparisons are made to published experimental measurements of baryon rapidity and transverse momentum distributions, negative hadron rapidity and transverse momentum distributions, average multiplicities of pions, kaons, hyperons, and antihyperons, and zero degree energy distributions for sulfur-sulfur collisions at 200 GeV/c per nucleon and for lead-lead collisions at 158 GeV/c per nucleon. Good agreement is found except that the number of strange particles produced, especially antihyperons, is too small compared with experiment. We call this model LEXUS: Linear EXtrapolation of Ultrarelativistic nucleon-nucleon Scattering to heavy ion collisions. (11 refs).

  2. in heavy-ion collisions

    Indian Academy of Sciences (India)

    2015-05-06

    May 6, 2015 ... the 'Big Bang', and has now been (re-)created as the hottest matter ever in laboratory by heavy-ion collisions ('Little Bang') at the Relativistic Heavy Ion Collider (RHIC) as well as at the Large Hadron Collider (LHC). To experimentally measure and theoretically understand the various properties of the QGP ...

  3. High-energy ion-atom collisions

    International Nuclear Information System (INIS)

    Berenyi, Denes.

    1987-01-01

    The progress in energetic ion-atom collision studies is shown briefly on the basis of the Workshop in the field above held in Debrecen. The 'hot topics', namely 'two-center' and electron correlation phenomena, collisions with antiprotons, recent results on alignment and orientation in energetic heavy-ion collisions, autoionization electron studies in the meV region and the utilization of heavy-ion storage rings in ion-atom collision experiments are treated. (author) 4 figs

  4. Semiholography for heavy ion collisions

    CERN Document Server

    Mukhopadhyay, Ayan

    2017-01-01

    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.

  5. QCD in heavy ion collisions

    CERN Document Server

    Iancu, Edmond

    2014-04-10

    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.

  6. Central collisions of heavy ions

    International Nuclear Information System (INIS)

    Fung, Sun-yiu.

    1991-10-01

    This report describes the activities of the Heavy Ion Physics Group at the University of California, Riverside from October 1, 1990 to September 30, 1991. During this period, our program focuses on particle production at AGS energies, and correlation studies at the Bevalac in nucleus central collisions. We participated in the preparation of letters of intent for two RHIC experiments -- the OASIS proposal and the Di-Muon proposal -- and worked on two RHIC R ampersand D efforts -- a silicon strip detector project and a muon-identifier project. A small fraction of time was also devoted to physics programs outside the realm of heavy ion reactions by several individuals

  7. Relativistic heavy-ion collisions

    CERN Document Server

    Bhalerao, Rajeev S.

    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.

  8. Phenomenological approaches of dissipative heavy ion collisions

    International Nuclear Information System (INIS)

    Ngo, C.

    1983-09-01

    These lectures describe the properties of dissipative heavy ion collisions observed in low bombarding energy heavy ion reactions. These dissipative collisions are of two different types: fusion and deep inelastic reactions. Their main experimental properties are described on selected examples. It is shown how it is possible to give a simple interpretation to the data. A large number of phenomenological models have been developped to understand dissipative heavy ion collisions. The most important are those describing the collision by classical mechanics and friction forces, the diffusion models, and transport theories which merge both preceding approaches. A special emphasis has been done on two phenomena observed in dissipative heavy ion collisions: charge equilibratium for which we can show the existence of quantum fluctuations, and fast fission which appears as an intermediate mechanism between deep inelastic reactions and compound nucleus formation [fr

  9. Atomic collisions in fusion plasmas involving multiply charged ions

    International Nuclear Information System (INIS)

    Salzborn, E.

    1980-01-01

    A short survey is given on atomic collisions involving multiply charged ions. The basic features of charge transfer processes in ion-ion and ion-atom collisions relevant to fusion plasmas are discussed. (author)

  10. Charge exchange in ion-atom collisions

    International Nuclear Information System (INIS)

    Bransden, B.H.

    1990-01-01

    Charge exchange reactions in which electrons are transferred from one ion (or atom) to another during a collision have been studied both as interesting examples of rearrangement collisions and because of important applications in plasma physics. This article reviews the modern theory developed for use at non-relativistic energies, but excluding the thermal and very low energy region. (author)

  11. Electron capture in ion-molecule collisions at intermediate energy

    International Nuclear Information System (INIS)

    Kumura, M.

    1986-01-01

    Recent progress of theoretical charge transfer study in ion-molecule collisions at the intermediate energy is reviewed. Concept of close and distant collisions obtained from extensive ion-atom collision studies is identified so that it can be utilized to model two distinct collision processes. For a close collision, explicit representation of the whole collision complex is necessary to describe collision dynamics correctly, while a model potential approach for molecule is appropriate for a distant collision. It is shown that these two distinct models are indeed capable of reproducing experimental charge transfer cross sections. Some remarks for further theoretical study of ion-molecule collisions are also given. 21 refs., 8 figs

  12. Jet production in heavy ion collisions

    CERN Document Server

    Calucci, G

    2000-01-01

    We discuss the production of jets in heavy ion collisions at LHC. The process allows one to determine to a good accuracy the value of the impact parameter of the nuclear collision in each single inelastic event. The knowledge of the geometry is a powerful tool for a detailed analysis of the process, making it possible to test the various different elements which, in accordance with present theoretical ideas, take part to the production mechanism. (8 refs).

  13. Physics with relativistic heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    Dönigus Benjamin

    2015-01-01

    Full Text Available An overview is given on the experimental study of physics with relativistic heavy-ion collisions, with emphasis on recent measurements at the Large Hadron Collider (LHC and the Relativistic Heavy Ion Collider (RHIC. The focus here is laid on p–Pb collisions at the LHC and the corresponding d–Au measurements at RHIC. The topics touched are “collectivity and approach to equilibrium”, “high pT and jets”, “heavy flavour and electroweak bosons” and “search for exotic objects”.

  14. Heavy ion collisions at intermediate energy

    International Nuclear Information System (INIS)

    Bertsch, G.; Amsden, A.A.

    1978-01-01

    Two types of measurement are proposed for the analysis of heavy ion collisions in the range of energy of 20--200 MeV/A. First, measurement of the longitudinal component of the kinetic energy of the collision products characterizes the impact parameter of the collision. The distribution in this quantity allows the dissipation in the theoretical models to be determined. A second kind of measurement is that of the coefficients of a spherical harmonic expansion of the angular distribution of the products. Besides giving independent information on the impact parameter and reaction dynamics, measurement of these coefficients offers the possibility of measuring the stiffness of the equation of state of nuclear matter. These ideas are explored in the context of a hydrodynamic model for the collision. In the purely hydrodynamic model there is a large measurable asymmetry in the angular distribution, but the dependence on the equation of state is small

  15. Heavy ion collisions with the ATLAS detector

    International Nuclear Information System (INIS)

    Nevski, Pavel

    2004-01-01

    The ATLAS detector is designed to study high-p T physics in proton-proton collisions at the LHC design luminosity. The detector capabilities for heavy-ion physics are now being evaluated. This paper reports on a preliminary assessment of the baseline ATLAS detector potential for heavy-ion physics. The ATLAS sensitivity to some of the expected signatures from the quark-gluon plasma (e.g. jet quenching, Υ suppression) is discussed. (orig.)

  16. Electronic stopping in ion-fullerene collisions

    NARCIS (Netherlands)

    Schlathölter, T.A.; Hadjar, O.; Hoekstra, R.A.; Morgenstern, R.W.H.

    The electronic friction experienced by a multiply charged ion interacting with the valence electrons of a single fullerene is an important aspect of the collision dynamics. It manifests itself in a considerable loss of projectile kinetic energy transferred to the target, resulting in excitation. The

  17. Multifragmentation and dynamics in heavy ion collisions

    Indian Academy of Sciences (India)

    The investigation of heavy-ion collision mechanisms at intermediate energies, around the nucleon Fermi energy, have set major understanding objectives to reach. For several years, such studies have been focusing on intermediate-mass fragment (IMF) production. More specifically, the probing of nuclear liquid-gas phase ...

  18. Ultrarelativistic heavy ion collisions Theoretical overview

    International Nuclear Information System (INIS)

    Blaizot, Jean-Paul

    2006-01-01

    This is a short review of some theoretical aspects of the physics of ultra-relativistic heavy ion collisions. I review the main properties of the QCD phase diagram and recent developments in the physics of high gluon densities in the hadronic wavefunctions at high energy. Then I comment salient results obtained at RHIC

  19. Study of heavy ion collisions with TAPS

    NARCIS (Netherlands)

    Löhner, H.

    The photon spectrometer TAPS is a versatile instrument to measure nuclear bremsstrahlung and neutral mesons via their gamma decay. The formation and evolution of compressed nuclear matter is studied in heavy ion collisions at relativistic energies by analyzing the yield and spectral distribution of

  20. Particle production in heavy ion collisions

    International Nuclear Information System (INIS)

    Braun-Munzinger, P.; Redlich, K.; Wroclaw Univ.; Stachel, J.

    2003-04-01

    The status of thermal model descriptions of particle production in heavy ion collisions is presented. We discuss the formulation of statistical models with different implementation of the conservation laws and indicate their applicability in heavy ion and elementary particle collisions. We analyze experimental data on hadronic abundances obtained in ultra-relativistic heavy ion collisions, in a very broad energy range starting from RHIC/BNL (√(s) = 200 A GeV), SPS/CERN (√(s) ≅ 20 A GeV) up to AGS/BNL (√(s) ≅ 5 A GeV) and SIS/GSI (√(s) ≅ 2 A GeV) to test equilibration of the fireball created in the collision. We argue that the statistical approach provides a very satisfactory description of experimental data covering this wide energy range. Any deviations of the model predictions from the data are indicated. We discuss the unified description of particle chemical freeze-out and the excitation functions of different particle species. At SPS and RHIC energy the relation of freeze-out parameters with the QCD phase boundary is analyzed. Furthermore, the application of the extended statistical model to quantitative understanding of open and hidden charm hadron yields is considered. (orig.)

  1. Nonrelativistic theory of heavy-ion collisions

    International Nuclear Information System (INIS)

    Bertsch, G.

    1984-01-01

    A wide range of phenomena is observed in heavy-ion collisions, calling for a comprehensive theory based on fundamental principles of many-particle quantum mechanics. At low energies, the nuclear dynamics is controlled by the mean field, as we know from spectroscopic nuclear physics. We therefore expect the comprehensive theory of collisions to contain mean-field theory at low energies. The mean-field theory is the subject of the first lectures in this chapter. This theory can be studied quantum mechanically, in which form it is called TDHF (time-dependent Hartree-Fock), or classically, where the equation is called the Vlasov equation. 25 references, 14 figures

  2. Nonrelativistic theory of heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Bertsch, G.

    1984-07-17

    A wide range of phenomena is observed in heavy-ion collisions, calling for a comprehensive theory based on fundamental principles of many-particle quantum mechanics. At low energies, the nuclear dynamics is controlled by the mean field, as we know from spectroscopic nuclear physics. We therefore expect the comprehensive theory of collisions to contain mean-field theory at low energies. The mean-field theory is the subject of the first lectures in this chapter. This theory can be studied quantum mechanically, in which form it is called TDHF (time-dependent Hartree-Fock), or classically, where the equation is called the Vlasov equation. 25 references, 14 figures.

  3. Application of hydrodynamics to heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Felsberger, Lukas

    2014-12-02

    The Bjorken model is a simple tool for making rough predictions of the hydrodynamic evolution of the thermalized matter created in a heavy ion collision. The advantage of the model clearly lies in its simplicity, rather than accuracy. As it is still used for making rough estimations 'by hand', in this thesis, I investigate in which cases the Bjorken model gives useful results and in which it is not recommended. For central collisions, I show which critical size the nuclei should have so that the Bjorken model can be applied. For non-central collisions, I demonstrate that using Glauber initial conditions combined with the Bjorken evolution, leads to reasonable results up to large impact parameters. Finally, I study the case of a non-ideal (viscous) description of the thermalized matter which leads to strongly differing results if first- or second-order hydrodynamics is applied.

  4. 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...... method are applied in order to describe the target molecule and the collision process. It is shown that three perpendicular orientations of the molecular axis with respect to the trajectory are sufficient to accurately reproduce the ionization cross section calculated by Sakimoto [Phys. Rev. A 71, 062704...... (2005)] reducing the numerical effort drastically. The independent-event model is employed to approximate the cross section for double ionization and H+ production in antiproton collisions with H2....

  5. High energy heavy ion collisions: Lessons from relativistic heavy ion ...

    Indian Academy of Sciences (India)

    crease in √s at RHIC brings us to a new regime of high energy heavy-ion collisions, ... Another scenario comes from the picture of particle production .... nuclear media. To study the effect on spectra, ratio between spectra from pA or AA with spectra from pp are taken. Spectra from pp are scaled for nuclear thickness.

  6. 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.

  7. Dissipative processes in light heavy ion collisions

    Science.gov (United States)

    Pop, A.; Andronic, A.; Berceanu, I.; Duma, M.; Moisâ, D.; Petrovici, M.; Simion, V.; Immé, G.; Lanzanò, G.; Pagano, A.; Raciti, G.; Coniglione, R.; Del Zoppo, A.; Piatelli, P.; Sapienza, P.; Colonna, N.; D'Erasmo, G.; Pantaleo, A.

    1999-09-01

    The characteristics of the dissipative processes in the collisions of light heavy ion systems at incident energies below 10 MeV/nucleon have been studied. The correlations between different experimental observables show similar trends as those known at much heavier systems and semiempirical relationships are established starting from assumptions on the nature of the micro-scopic mechanisms. The charge equilibration process in light systems is also studied.

  8. Dissipative processes in light heavy ion collisions

    International Nuclear Information System (INIS)

    Pop, A.; Andronic, A.; Berceanu, I.; Duma, M.; Moisa, D.; Petrovici, M.; Simion, V.; Imme, G.; Lanzano, G.; Pagano, A.; Raciti, G.; Coniglione, R.; Del Zoppo, A.; Piatelli, P.; Sapienza, P.; Colonna, N.; D'Erasmo, G.; Pantaleo, A.

    1999-01-01

    The characteristics of the dissipative processes in the collisions of light heavy ion systems at incident energies below 10 MeV/nucleon have been studied. The correlations between different experimental observables show similar trends as those known at much heavier systems and semiempirical relationships are established starting from assumptions on the nature of the microscopic mechanisms. The charge equilibration process in light systems is also studied. (author)

  9. Probing jet decoherence in heavy ion collisions

    Science.gov (United States)

    Casalderrey-Solana, Jorge; Mehtar-Tani, Yacine; Salgado, Carlos A.; Tywoniuk, Konrad

    2017-11-01

    We suggest to use the SofDrop jet grooming technique to investigate the sensitivity of jet substructure to color decoherence in heavy ion collisions. We propose in particular to analyze the two-prong probability angular distribution as a probe of the transition between the coherent and incoherent energy loss regimes. We predict an increasing suppression of two-prong substructures with angle as the medium resolves more jet substructure.

  10. Hadron chemistry in heavy ion collisions

    International Nuclear Information System (INIS)

    Montvay, I.; Zimanyi, J.

    1978-06-01

    In the models for energetic heavy ion reactions it is assumed that during the reaction a hot and dense nuclear matter, a fireball is formed from all or a part of nucleons of the target and projectile nuclei. The process is similar to the chemical processes leading to dynamical equilibrium. The relaxation times necessary to establish ''chemical'' equilibrium among different hadrons in hot, dense hadronic matter is deducted in a statistical model. Consequences for heavy ion collisions are discussed. The possibility of Bose-Einstein pion condensation around the break-up time of the nuclear fireball is pointed out. (D.P.)

  11. 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.

  12. 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.)

  13. 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.

  14. Fast ion-atom and ion-molecule collisions

    CERN Document Server

    2013-01-01

    The principal goal of this book is to provide state-of-the art coverage of the non-relativistic three- and four-body theories at intermediate and high energy ion-atom and ion-molecule collisions. The focus is on the most frequently studied processes: electron capture, ionization, transfer excitation and transfer ionization. The content is suitable both for graduate students and experienced researchers. For these collisions, the literature has seen enormous renewal of activity in the development and applications of quantum-mechanical theories. This subject is of relevance in several branches of science and technology, like accelerator-based physics, the search for new sources of energy and high temperature fusion of light ions. Other important applications are in life sciences via medicine, where high-energy ion beams are used in radiotherapy for which a number of storage ring accelerators are in full operation, under construction or planned to be built worldwide. Therefore, it is necessary to review this fiel...

  15. Charge equilibration in light heavy ion collisions

    International Nuclear Information System (INIS)

    Pop, A.; Berceanu, I.; Duma, M.; Moisa, D.; Petrovici, M.; Simion, V.; Coniglione, R.; Del Zoppo, A.; Piatelli, P.; Sapienza, P.

    1997-01-01

    The charge equilibration (isospin relaxation) mode is one of the fastest degrees of freedom in deep inelastic collisions. The light heavy ion reactions 19 F(136.9 MeV) + 27 Al( 12 C) and 27 Al(140.14 MeV) + 27 Al( 12 C) have been studied with the experimental device DRACULA mounted at LNS, Catania. The reaction products have been identified by their atomic number with two large area position-sensitive ionization chambers and by mass using the time-of-light path of 60 cm between a start and a stop parallel plate avalanche detector. The obtained Z-A matrix is given. The mass resolution was of the order of one unit mass. The identification of both mass and charge allowed to study the charge equilibration process in light heavy ion collisions by extracting from data the experimental conditional variance at the initial mass asymmetry. The nature of the charge equilibration process was a challenging subject for many years. The studies have been almost exclusively done for medium and heavy nuclei. The conditional variance obtained for two measured systems is shown together with the predictions of the statistical and quantum mechanical limits. Although the data are not corrected for evaporation emission they lie above the statistical limit. The reconstruction of the primary distribution and detailed comparison with different models are currently in progress

  16. Storage rings for investigation of ion-atom collisions

    International Nuclear Information System (INIS)

    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

  17. Observing B-violation in relativistic heavy-ion collisions

    Indian Academy of Sciences (India)

    Observing B-violation in relativistic heavy-ion collisions. RAJARSHI RAY. Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005, India. Abstract. Under certain situations, partons formed in heavy-ion collision experiments may expand out forming a shell-like structure. The partons in the outer shell subsequently ...

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

    Indian Academy of Sciences (India)

    2015-05-06

    May 6, 2015 ... 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 ...

  19. High baryon density from relativistic heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Y.; Kahana, S.H. [Brookhaven National Lab., Upton, NY (United States); Schlagel, T.J. [Brookhaven National Lab., Upton, NY (United States)]|[State Univ. of New York, Stony Brook, NY (United States)

    1993-10-01

    A quantitative model, based on hadronic physics, is developed and applied to heavy ion collisions at BNL-AGS energies. This model is in excellent agreement with observed particle spectra in heavy ion collisions using Si beams, where baryon densities of three and four times the normal nuclear matter density ({rho}{sub 0}) are reached. For Au on Au collisions, the authors predict the formation of matter at very high densities (up to 10 {rho}{sub 0}).

  20. Hard probes in heavy ion collisions at the LHC: PDFs, shadowing and $pA$ collisions

    CERN Document Server

    Accardi, Alberto; Botje, M.; Brodsky, S.J.; Cole, B.; Eskola, K.J.; Fai, George I.; Frankfurt, L.; Fries, R.J.; Geist, Walter M.; Guzey, V.; Honkanen, H.; Kolhinen, V.J.; Kovchegov, Yu.V.; McDermott, M.; Morsch, A.; Qiu, Jian-wei; Salgado, C.A.; Strikman, M.; Takai, H.; Tapprogge, S.; Vogt, R.; Zhang, X.f.

    2003-01-01

    This manuscript is the outcome of the subgroup ``PDFs, shadowing and $pA$ collisions'' from the CERN workshop ``Hard Probes in Heavy Ion Collisions at the LHC''. In addition to the experimental parameters for $pA$ collisions at the LHC, the issues discussed are factorization in nuclear collisions, nuclear parton distributions (nPDFs), hard probes as the benchmark tests of factorization in $pA$ collisions at the LHC, and semi-hard probes as observables with potentially large nuclear effects. Also, novel QCD phenomena in $pA$ collisions at the LHC are considered. The importance of the $pA$ program at the LHC is emphasized.

  1. Numerical simulation of ion temperature gradient driven modes in the presence of ion-ion collisions

    International Nuclear Information System (INIS)

    Xu, X.Q.

    1990-08-01

    Ion temperature gradient driven modes in the presence of ion-ion collisions in a toroidal geometry with trapped ions have been studied by using a 1 2/2 d linearized gyro-kinetic particle simulation code in the electrostatic limit. The purpose of the investigation is to try to understand the physics of flat density discharges, in order to test the marginal stability hypothesis. Results giving threshold conditions of L Ti /R 0 , an upper bound on k χ , and linear growth rates and mode frequencies over all wavelengths for the collisionless ion temperature gradient driven modes are obtained. The behavior of ion temperature gradient driven instabilities in the transition from slab to toroidal geometry, with trapped ions, is shown. A Monte Carlo scheme for the inclusion of ion-ion collisions, in which ions can undergo Coulomb collisional dynamical friction, velocity space diffusion and random walk of guiding centers, has been constructed. The effects of ion-ion collisions on the long wave length limit of the ion modes is discussed. 44 refs., 12 figs

  2. Studies of relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Madansky, L.

    1989-01-01

    This report presents the progress in our program of Relativistic Heavy Ion studies. The first phase of experiments on lepton pairs is almost complete and the results from the initial part of this program are presented in copies of three publications. It appears that the origin of lepton pairs is the annihilation of pions. The evidence for this seems to be the shape of the dilepton mass spectrum, the cross-section as a function of energy which seems to scale with pion production, and the general kinematic behavior of the lepton pairs themselves. We present progress on the development of Ring Imaging Cerenkov counters for dilepton observations in general, and a short report on a high resolution method counter proposal that could be adapted to RHIC counters in general. Publication of results on hyperon polarization with incident polarized proton beams is also presented. These results use the phenomenological approach that could be useful in understanding hyperon production in heavy ion collisions. In this connection, a proposal for studying high density nuclear matter with incident antiprotons is presented. Progress on the TPC detectors developed by the BNL group for heavy ion research is reported, along with recent analysis of polarization with incident silicon beams. Finally, the most recent results on subthreshold antiproton production is presented. These latter results are several orders of magnitude more than expected and they point to some kind of coherent hadronic phenomena even at extremely low energies

  3. Identifying Multiquark Hadrons from Heavy Ion Collisions

    International Nuclear Information System (INIS)

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

    2011-01-01

    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.

  4. 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

  5. ''Antiflow'' of antiprotons in heavy ion collisions

    International Nuclear Information System (INIS)

    Jahns, A.; Spieles, C.; Sorge, H.; Stoecker, H.; Greiner, W.

    1994-01-01

    In the framework of the relativistic quantum molecular dynamics approach we investigate antiproton (bar p) observables in Au+Au collisions at 10.7A GeV. The rapidity dependence of the in-plane directed transverse momentum p x (y) of bar p's shows the opposite sign of the nucleon flow, which has indeed recently been discovered at 10.7A GeV by the E877 group. The ''antiflow'' of bar p's is also predicted at 2A GeV and at 160A GeV and appears at all energies also for π's and K - 's. These predicted bar p anticorrelations are a direct proof of strong bar p annihilation in massive heavy ion reactions

  6. Behaviour of ion velocity distributions for a simple collision model

    Science.gov (United States)

    St-Maurice, J.-P.; Schunk, R. W.

    1974-01-01

    Calculation of the ion velocity distributions for a weakly ionized plasma subjected to crossed electric and magnetic fields. An exact solution to Boltzmann's equation has been obtained by replacing the Boltzmann collision integral with a simple relaxation model. At altitudes above about 150 km, where the ion collision frequency is much less than the ion cyclotron frequency, the ion distribution takes the shape of a torus in velocity space for electric fields greater than 40 mV/m. This shape persists for one to two hours after application of the electric field. At altitudes where the ion collision and cyclotron frequencies are approximately equal (about 120 km), the ion velocity distribution is shaped like a bean for large electric field strengths. This bean-shaped distribution persists throughout the lifetime of ionospheric electric fields. These highly non-Maxwellian ion velocity distributions may have an appreciable affect on the interpretation of ion temperature measurements.

  7. Heavy ion collisions at collider energies – Insights from PHENIX

    Indian Academy of Sciences (India)

    15Korea University, Seoul 136-701, Korea. 16Russian Research ... 23Myongji University, Yongin, Kyonggido 449-728, Korea. 24Nagasaki Institute of ..... High pT phenomena. Hard scattering provides a novel tomographic tool to study nuclear matter created in heavy- ion collisions at collider energies. In pp collisions at ...

  8. Status of chemical equilibrium in relativistic heavy-ion collisions

    Indian Academy of Sciences (India)

    collisions. J CLEYMANS. Department of Physics, University of Cape Town, Rondebosch 7701, South Africa. Abstract. 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 ...

  9. Enhancement of strangeness in relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Grassi, F.; Heiselberg, H.

    1990-01-01

    The theoretical and experimental conditions to obtain strange particle production in heavy ion collisions at high energies are discussed, by analysis of results obtained from Super Proton Synchrotron - CERN and Alternating Gradient Synchrotron in United States. (M.C.K.)

  10. Dileptons in high-energy heavy-ion collisions

    Indian Academy of Sciences (India)

    relativistic heavy- ion collisions is discussed with special emphasis on signals from the (approach towards) chirally restored and deconfined phases. In particular, recent results of the CERN-SPS low-energy runs are compared to model ...

  11. Some remarks on the statistical model of heavy ion collisions

    International Nuclear Information System (INIS)

    Koch, V.

    2003-01-01

    This contribution is an attempt to assess what can be learned from the remarkable success of this statistical model in describing ratios of particle abundances in ultra-relativistic heavy ion collisions

  12. Development of a collision induced dissociation ion cyclotron resonance spectrometer

    International Nuclear Information System (INIS)

    Fan, Y.N.

    1982-01-01

    A transient analysis ion cyclotron resonance spectrometer is developed to investigate the phenomena of collision induced dissociation. The Fourier transform method and the modified maximum entropy spectral analysis or covariance least square method are implemented in measuring the mass spectrum of the ion ensemble. The Fourier transform method can be used in quantitative analysis while the maximum entropy method as developed here is useful for qualitative analysis only. The cyclotron resonance frequency, relaxation time constant, and the relative ion population are observable from the Fourier transform spectrum. These parameters are very important in investigating collision induced dissociation process and other topics in gas phase chemistry. The ion cyclotron resonance spectrometer is not only developed to study fragments and their abundance from a parent ion, but also to determine the threshold energy and reaction cross section in the collision induced dissociation process. When hard sphere model is used in the ion-molecule collision, the radius of acetone ion measured from the reactive cross section is 2.2 angstrom which is very close to the physical dimension of acetone. The threshold energy for acetone ion in collision induced dissociation process is 1.8 eV which is similar to the result obtained by the angle-resolved mass spectrometer

  13. Heavy ion collisions and quark distribution in nuclei

    International Nuclear Information System (INIS)

    Liu Lian-sou; Pan Ji-cai; Peng Hung-an

    1986-01-01

    Heavy-ion collisions are studied by means of two-component Fokker--Planck equations on the assumption that there exist multiquark states in nuclei. Inclusive cross sections for the production of protons are calculated in heavy-ion collisions of C+C, Ne+NaF, and Ar+KCl at 800 MeV/A; Ne+Na at 400 MeV/A, 800 MeV/A, and 2100 MeV/A. Satisfactory agreement with the experimental data near 90 degrees c.m. is obtained. The production of deuterons in the collision of C+C at 800 MeV/A is also discussed

  14. TARGET EXCITATION IN BARE ION XE/AR COLLISIONS STUDIED BY ELECTRON TARGET ION COINCIDENCES

    NARCIS (Netherlands)

    DENIJS, G; HOEKSTRA, R; MORGENSTERN, R

    We present electron spectra resulting from collisions of bare ions N-15(7+) and C-13(6+) on Ar and the charge state distribution of target ions resulting from C-13(6+)-Xe collisions. From both type of experiments we find evidence that electron capture accompanied by target excitation is an important

  15. Electromagnetic processes in relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Bertulani, C.A.; Rio de Janeiro Univ.

    1987-05-01

    A study of the processes generated by the electromagnetic interaction in relativistic nuclear, and atomic collisions is presented. Very strong electromagnetic fields for a very short time are present in distant collisions with no nuclear contact. Such fields can also lead to interesting effects, which are discussed here. (orig.)

  16. Proceedings of the Budapest workshop on relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Csoergoe, T.; Hegyi, S.; Levai, P.

    1993-04-01

    This volume is the Proceedings of the Budapest workshop on relativistic heavy ion collisions held in Budapest, 10-13 Aug, 1992. The topics include experimental heavy ion physics, Bose-Einstein correlations, intermittency, relativistic transport theory, Quark-Gluon Plasma rehadronization, astronuclear physics and cosmology. All contributions were indexed and abstracted. (author)

  17. International Workshop on Collectivity in Relativistic Heavy Ion Collisions

    CERN Document Server

    2014-01-01

    The International Workshop on Collectivity in Relativistic Heavy Ion Collisions (IWoC 2014) aims to collect theoreticians and experimentalists working in the field of relativistic heavy ion physics. The conference will be hosted in the Conference Center of the Orthodox Academy of Creta (OAC), an exceptionally beautiful location only a few meters from the mediteranean sea.

  18. Proton capture and loss in ion-molecule collisions

    International Nuclear Information System (INIS)

    Ibanez, S; Alessi, M; Zimmerman, V; Fregenal, D; Focke, P; Bernardi, G; Suarez, S

    2007-01-01

    We have measured proton distributions from the collision systems Ar + , Kr + on CH 4 molecular targets, searching for atom capture into the projectile continuum. Within the studied energy range (100 to 300 eV/u) we have not distinctive evidence of capture. A small contamination of ion beams with molecular ions as ArH + or KrH + , have shown to be enough to produce peak shaped structures at the projectile velocity. We, therefore, concentrate our study on proton loss from molecular ions in collision with several targets

  19. Constraints on the symmetry energy from heavy ion collisions

    International Nuclear Information System (INIS)

    Lynch, W.G.; Tsang, M.B.; Chajecki, Z.; Coupland, D.; Danielewicz, P.; Famiano, M.; Hodges, R.K.; Kilburn, M.; Winkelbauer, J.; Youngs, M.; Lu, F.; Zhang, Y.Z.

    2010-01-01

    Constraints on the Equation of State for symmetric matter (equal neutron and proton numbers) have been extracted from energetic collisions of heavy ions over a range of energies. Collisions of neutron-deficient and neutron-rich heavy ions now provide initial constraints on the Equation of State of neutron-rich matter at sub-saturation densities from isospin diffusions and neutron proton ratios. This talk reviews the experimental constraints from heavy ion reactions on the density dependence of symmetry energy at sub-saturation density. These constraints are compared to other available constraints from nuclear structures, masses and neutron skins. (author)

  20. Background Effects on Jet Detection in Heavy Ion Collisions

    Science.gov (United States)

    Aukerman, Alexander; Hughes, Charles; Krobatch, Thomas; Matyja, Adam; Nattrass, Christine; Neuhas, James; Sorensen, Soren; Witt, Will

    2017-09-01

    Heavy ion collisions performed at the LHC and RHIC at large energy scales produce a liquid of quarks and gluons known as a Quark-Gluon Plasma (QGP). Jets, which are collimated bunches of particles emitted from highly energetic partons, are produced at the early stages of these collisions, and can provide information about the properties of the QGP. Partonic energy loss in the medium can by quantified by measurements of fragmentation functions. However, the high background energies resulting from emissions uncorrelated to the initial hard scatterings in the heavy ion collisions place limitations on jet detection methods and fragmentation measurements. For the purpose of investigating the limitations on these current jet detection methods we generated a heavy ion background based on charged hadron data. We explore the behavior of a jet finding algorithm with our generated background to examine how the presence of a heavy ion background may affect the measurements of jet properties.

  1. The theory of relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    1993-07-01

    This program began in January 1993. Its primary goals are studies of highly excited matter and its production in nuclear collisions at very high energies. After a general orientation on the project, abstracts describing the contents of completed papers and providing some details of current projects are given. Principal topics of interest are the following: the dynamics of nuclear collisions at very high energies (RHIC and LHC), the dynamics of nuclear collisions at AGS energies, high-temperature QCD and the physics of the quark-gluon plasma, and the production of strangelets and other rare objects

  2. Particle production in relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Vary, J.P.

    1978-01-01

    Within the framework of multiple scattering theory we present and contrast both the conventional limiting case of independent multiple collisions of nucleons and the multiple scattering of collective degrees of freedom. Dramatically different predictions may be obtained for particle production in relativistic nucleon-nucleus and nucleus-nucleus collisions. We first study the pion multiplicity distributions to uncover evidence for a coherent-collective mechanism. Attention is then focused on potentially more conclusive tests - subthreshold (in the nucleon-nucleon kinematics) production of massive particles anti p, K - , PSI/J and W, as examples. Evidence for a collective mechanism is found by examining subthreshold anti p production data in particle-nucleus collisions and contrasting with results from the IMC model including realistic Fermi motion. As perhaps the leading candidate for a coherent-collective mechanism we specifically adopt the Coherent Tube Model to explain these data since it has been successful in high energy particle-nucleus collisions. (orig.) [de

  3. Jet studies in heavy ion collisions with the ATLAS detector

    CERN Document Server

    Slovak, Radim; The ATLAS collaboration

    2016-01-01

    In relativistic heavy ion collisions, a hot medium with a high density of unscreened color charges is produced. Jets are produced at the early stages of this collision and are known to become attenuated as they propagate through the hot matter. One manifestation of this energy loss is a lower yield of jets emerging from the medium than expected in the absence of medium effects. ATLAS has provided a quantification of this jet suppression by the jet Raa measurement in run 1 of LHC. A factor of two suppression was seen in central heavy ion collisions with respect to pp collisions. The Raa exhibited only a week, if any, rapidity dependence, and a slow rise with increasing jet momentum. This talk summarizes the run 1 results on the inclusive jet production and the new results on dijet measurements.

  4. Formation of heavy quarks in ultrarelativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Schneider, S.M.; Greiner, W.; Soff, G.

    1992-02-01

    We investigate the production of heavy quarks in continuum and bound states in nuclear collisions. Creation for free banti b and tanti t quark pairs and for bottomonium and toponium in the ground state are computed at RHIC, LHC and SSC energies. Central and peripheral heavy-ion collisions are discussed. For top quark creation we assumed a mass range of 90 GeV ≤ m t ≤ 250 GeV. The creation rate for top quarks on peripheral collisions is estimated to be by a factor 40 to 130 smaller compared with corresponding central collisions. For m t = 130 GeV we calculated a creation rate of about 4760 top quark pairs per day at the LHC (3.5 TeV/u) for Pb-Pb collisions. (orig.)

  5. Status of chemical equilibrium in relativistic heavy-ion collisions

    Indian Academy of Sciences (India)

    µB =0 and a radius of 1.2 fm. There are two important differences in the behavior ofλ s in elementary compared to heavy-ion collisions. Firstly, the strangeness content is smaller by a factor of two. In elementary collisions, particle multiplicities follow the values given by. 790. Pramana – J. Phys., Vol. 60, No. 4, April 2003 ...

  6. Electron collisions and internal excitation in stored molecular ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Buhr, H.

    2006-07-26

    In storage ring experiments the role, which the initial internal excitation of a molecular ion can play in electron collisions, and the effect of these collisions on the internal excitation are investigated. Dissociative recombination (DR) and inelastic and super-elastic collisions are studied in the system of He{sup +}{sub 2}. The DR rate coefficient at low energies depends strongly on the initial vibrational excitation in this system. Therefore changes in the DR rate coefficient are a very sensitive probe for changes in the vibrational excitation in He{sup +}{sub 2}, which is used to investigate the effects of collisions with electrons and residual gas species. The low-energy DR of HD{sup +} is rich with resonances from the indirect DR process, when certain initial rotational levels in the molecular ion are coupled to levels in neutral Rydberg states lying below the ion state. Using new procedures for high-resolution electron-ion collision spectroscopy developed here, these resonances in the DR cross section can be measured with high energy sensitivity. This allows a detailed comparison with results of a MQDT calculation in an effort to assign some or all of the resonances to certain intermediate Rydberg levels. (orig.)

  7. Phenomenology of anomalous chiral transports in heavy-ion collisions

    Science.gov (United States)

    Huang, Xu-Guang

    2018-01-01

    High-energy Heavy-ion collisions can generate extremely hot quark-gluon matter and also extremely strong magnetic fields and fluid vorticity. Once coupled to chiral anomaly, the magnetic fields and fluid vorticity can induce a variety of novel transport phenomena, including the chiral magnetic effect, chiral vortical effect, etc. Some of them require the environmental violation of parity and thus provide a means to test the possible parity violation in hot strongly interacting matter. We will discuss the underlying mechanism and implications of these anomalous chiral transports in heavy-ion collisions.

  8. Progress in jet reconstruction and heavy ion collisions

    CERN Document Server

    Rojo, Juan

    2010-01-01

    We review recent developments related to jet clustering algorithms and jet reconstruction, with particular emphasis on their implications in heavy ion collisions. These developments include fast implementations of sequential recombination algorithms, new IRC safe algorithms, quantitative determination of jet areas and quality measures for jet finding, among many others. We also show how jet reconstruction provides a useful tool to probe the characteristics of the hot and dense medium created in heavy ion collisions, which allows one to distinguish between different models of parton-medium interaction.

  9. Estimation on Local Energy Density in Relativistic Heavy Ion Collisions

    Science.gov (United States)

    Ma, Zhong-Biao; Miao, Hong; Gao, Chong-Shou

    2003-02-01

    Energy density for the central region in relativistic heavy ion collisions can be estimated via the pseudorapidity distribution of transverse energy. The way to estimate the local energy density for the central region in relativistic heavy ion collisions is proposed, in which only final state particles emitted from the same source are included. The arrived energy density in NA49 experiments is about 1.03 GeV/fm3. The project supported in part by National Natural Science Foundation of China under Grant No. 90103019, and the Doctoral Program Foundation of Institution of Higher Education, the National Education Commission of China under Grant No. 2000000147

  10. Some aspects of the ion solid collision studies using highly charged and energetic heavy ion beams

    International Nuclear Information System (INIS)

    Tandon, P.N.

    1995-01-01

    Some aspects of the ion solid collision studies using highly charged and energetic heavy ions are presented. These relate to the polarization acquired by such ions when they travel through a polarized ferromagnetic material. The effects of the wake potential as investigated by the radiative electron capture are also presented. (author). 22 refs., 9 figs

  11. Correlated electron-ion collisions in a strong laser field

    International Nuclear Information System (INIS)

    Ristow, T.

    2007-01-01

    Electron-ion-collisions in plasmas in the presence of an ultra-short intensive laser pulse can cause high energy transfers to the electrons. During the collision the oscillation energy of the electron in the laser field is changed into drift energy. In this regime, multi-photon processes, known from the ionization of neutral atoms (Above-Threshold Ionization), and successive, so called correlated collisions, are important. The subject of the thesis is a study of binary Coulomb collisions in strong laser fields. The collisions are treated both in the context of classical Newtonian mechanics and in the quantum-mechanical framework by the Schroedinger equation. In the classical case a simplified instantaneous collision model and a complete dynamical treatment are discussed. Collisions can be treated instantaneously, if the ratio of the impact parameter to the quiver amplitude is small. The energy distributions calculated in this approximation show an elastic peak and a broad plateau due to rescattered electrons. At incident velocities smaller than the quiver velocity, correlated collisions are observed in the electron trajectories of the dynamical model. This effect leads to characteristic momentum distributions of the electrons, that are explicitly calculated and compared with the results of the instantaneous model. In addition, the time-dependence of the collisions is discussed in the framework of a singular perturbation theory. The complete description of the Coulomb scattering requires a quantum-mechanical description. A time-dependent method of wave-packet scattering is used and the corresponding time-dependent three-dimensional Schroedinger equation is solved by an implicit ADImethod on a spatial grid. The momentum and the energy distributions of the scattered electrons are calculated by the Fourier transformation of the wavefunction. A comparison of the scattering from a repulsive and an attractive potential is used to distinguish between simple collisions and

  12. Jets in heavy ion collisions with the ATLAS detector

    CERN Document Server

    Santos, Helena; The ATLAS collaboration

    2017-01-01

    Jets constitute a golden probe to study the quark gluon plasma produced in heavy ion collisions at the LHC. Being produced at the early stages of the collisions, they are expected to be modified as propagating through the hot and dense medium. A signature of the modification is the energy loss lowering the jet yields at a given transverse momentum. A factor of two suppression is observed in central Pb+Pb collisions with respect to pp collisions. Other signatures are the modification of the dijet momentum balance and the modification of fragmentation functions. This talk will present the currently available jet results from ATLAS in Run 2. The high statistical significance of this data sample collected by ATLAS in Run 2 allows precision measurements of these observables in a wide range of transverse momentum, centrality and rapidity intervals.

  13. Jets in heavy ion collisions with the ATLAS detector

    CERN Document Server

    Santos, Helena; The ATLAS collaboration

    2018-01-01

    Jets constitute a golden probe to study the quark gluon plasma produced in heavy ion collisions at the LHC. Being produced at the early stages of the collisions, they are expected to be modified as propagating through the hot and dense medium. A signature of the modification is the energy loss lowering the jet yields at a given transverse momentum. A factor of two suppression is observed in central Pb+Pb collisions with respect to pp collisions. Other signatures are the modification of the dijet momentum balance and the modification of fragmentation functions. This talk will present the currently available jet results from ATLAS in Run 2. The high statistical significance of this data sample collected by ATLAS in Run 2 allows precision measurements of these observables in a wide range of transverse momentum, centrality and rapidity intervals.

  14. Rescattering and Fluctuations in Ultrarelativistic Heavy-Ion Collisions

    Science.gov (United States)

    Friedman, Gerald Alan

    1993-12-01

    We study ultra-relativistic heavy-ion collisions using, as far as possible, known physics and simple assumptions. One focus is on the measurable effects of rescattering of produced particles in the colliding nuclei. Two models for proton -nucleus collisions are presented, one built from independent hadron-hadron collisions, the other based on the Lund model. We use them to study various assumptions about rescattering. Another focus is on fluctuations of global observables. We find a general formula for fluctuations in independent -collision models and show that its predictions are inconsistent with experimental data. We discuss possible explanations of the data. The fluctuations in our previously presented models are calculated and examined in the light of that discussion. Finally we give a method for comparing calculated fluctuations to experimental results.

  15. Scaling properties in single collision model of light ion reflection

    International Nuclear Information System (INIS)

    Vukanic, J.; Simovic, R.

    2004-01-01

    Light ion reflection from solids in the keV energy region has been studied within the single collision model. Particle and energy reflection coefficients as functions of the scaled transport cross section have been calculated numerically by utilizing the exact scattering function for the Kr-C potential and analytically with an effective power approximation for the same potential. The obtained analytical formulae approximate very accurately to the numerical results. Comparison of the calculated reflection coefficients with the experimental data and computer simulations for different light ion-heavy target combinations shows that the scaled transport cross section remains a convenient scaling parameter in the single collision domain, as adopted previously in multiple collision theory

  16. Electron-positron pair creation in heavy ion collisions

    International Nuclear Information System (INIS)

    Kienle, P.

    1987-08-01

    We review here the status of experiments to study the electron positron pair creation in heavy ion atom collisions at bombarding energies close to the Coulomb barrier. The disentanglement and characterisation of various sources of positrons observed in such collisions are described with a focus on the monoenergetic electron positron pairs observed. They seem to originate from the two-body decay of a family of neutral particles with masses of about 3 m e and life times in the range of 6x10 -14 s -10 s, produced by high Coulomb fields. First attempts were made to create these particles by resonant Bhabha scattering. First we present some experimental methods for high efficiency positron spectroscopy in heavy ion collisions. Then we describe the discovery of positron creation induced by strong time changing Coulomb fields. (orig./HSI)

  17. Bibliography on electron transfer processes in ion-ion/atom/molecule collisions. Updated 1997

    Energy Technology Data Exchange (ETDEWEB)

    Tawara, H.

    1997-04-01

    Following our previous compilations (IPPJ-AM-45 (1986), NIFS-DATA-7 (1990), NIFS-DATA-20 (1993)), bibliographic information on experimental and theoretical studies on electron transfer processes in ion-ion/atom/molecule collisions is up-dated. The references published through 1954-1996 are listed in the order of the publication year. For easy finding of the references for a combination of collision partners, a simple list is provided. (author)

  18. Collective flow in relativistic heavy-ion collisions

    Indian Academy of Sciences (India)

    journal of. November 2003 physics pp. 1021–1025. Collective flow in relativistic heavy-ion collisions. R S BHALERAO. Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road,. Mumbai 400 .... Wherever statistical analyses are done, whether in physics, biology or psychology, corre-.

  19. Collective flow in relativistic heavy-ion collisions

    Indian Academy of Sciences (India)

    It is important to investigate whether the quark–gluon matter formed in relativistic heavy- ion collisions, attains thermal equilibrium before it hadronizes. One can claim the forma- tion of a new state of matter, namely quark–gluon plasma, only if the thermalization is demonstrated unambiguously. Observation of a strong ...

  20. Heavy ion collisions at collider energies – Insights from PHENIX

    Indian Academy of Sciences (India)

    April 2003 physics pp. 639–650. Heavy ion collisions at collider energies – Insights from PHENIX. A DREES28, for the PHENIX Collaboration. K Adcox40, S S Adler3, N N Ajitanand27, Y Akiba14, J Alexander27, .... With a reasonable choice of the formation time τ0 .... interpreted in terms of initial state multiple scattering.

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

    Indian Academy of Sciences (India)

    2015-05-06

    May 6, 2015 ... physics pp. 881–899. Quarkonia at finite temperature in relativistic heavy-ion collisions. SAUMEN DATTA. Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road,. Mumbai 400 005, India. E-mail: saumen@theory.tifr.res.in. DOI: 10.1007/s12043-015-0975-y; ...

  2. Transport models for relativistic heavy-ion collisions at Relativistic ...

    Indian Academy of Sciences (India)

    2015-04-29

    Apr 29, 2015 ... We review the transport models that are widely used to study the properties of the quark-gluon plasma formed in relativistic heavy-ion collisions at RHIC and LHC. We show that transport model analysis of two important and complementary observables, the anisotropic flow of bulk hadrons and suppression ...

  3. Medium response to jets in heavy ion collisions

    Science.gov (United States)

    Tachibana, Yasuki

    2018-01-01

    A short overview on recent progress in studies of medium response to jet quenching in heavy ion collisions is presented. We show the typical features of medium response and give comment on their connection to jet observables by introducing the work done by the author and collaborators as an example.

  4. Electron emission in collisions of intermediate energy ions with atoms

    International Nuclear Information System (INIS)

    Garibotti, C.R.

    1988-01-01

    The aim of this work, is the analysis of the processes of electronic emission produced in the collisions of small ions (H + , He ++ ) of intermediate energy (50 a 200 KeV/amu) with light gaseous targets. (A.C.A.G.) [pt

  5. Fragmentation in heavy-ion collisions using quantum molecular ...

    Indian Academy of Sciences (India)

    approach for intermediate energy heavy-ion collisions [2,4,6]. On the other hand, semiclassical dynamical models [5] are very useful for studying the reaction from the start to final state where matter is fragmented and cold. In addition, these models also give a possibility to extract the information about the nuclear equation of ...

  6. Hydrodynamic modelling for relativistic heavy-ion collisions at RHIC ...

    Indian Academy of Sciences (India)

    progress on hydrodynamic modelling, investigation on the flow data and the extraction of the QGP shear viscosity in relativistic heavy-ion collisions at RHIC and LHC. 2. Hydrodynamic modelling – a short introduction. 2.1 Viscous hydrodynamics. Relativistic hydrodynamics is a macroscopic tool to simulate the QGP fireball ...

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

    Indian Academy of Sciences (India)

    2015-05-06

    May 6, 2015 ... ... 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.

  8. Event by event fluctuations in heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Volker

    2001-01-01

    The authors discuss the physics underlying event-by-event fluctuations in relativistic heavy ion collisions. We will argue that the fluctuations of the ratio of positively over negatively charged particles may serve as a unique signature for the Quark Gluon Plasma.

  9. Event-by-event fluctuations in heavy ion collisions

    OpenAIRE

    Doering, M.; Koch, V.

    2002-01-01

    We discuss the physics underlying event-by-event fluctuations in relativistic heavy ion collisions. We will argue that the fluctuations of the ratio of positively over negatively charged particles may serve as a unique signature for the Quark Gluon Plasma.

  10. Energy losses at collisions of relativistic structural heavy ions with atoms

    International Nuclear Information System (INIS)

    Matveev, V.I.; Gusarevich, E.S.

    2001-01-01

    One elaborated nonperturbation theory of energy losses at collisions of structural highly-charged heavy ions moving with relativistic speed. Ions containing partially populated electron shells are taken to be structural ions. The elaborated theory considers ion as an extended structural particle which size is equal to that of electronic shells. Paper contains the results of calculations of the efficient breaking at collision of a relativistic highly-charged ions with hydrogen atom derived for three domains of collision parameter values corresponding to low, average and high parameters of collision. The derived results are generalized for the case of collisions of relativistic structural heavy ions with compound atoms [ru

  11. Master Equation Studies of Collision-Induced Processes of Large Hydrocarbon Ions and Clusters

    National Research Council Canada - National Science Library

    Troe, Jurgen

    2003-01-01

    .... Calibrating collisional stabilization against measured fragmentation rates, collisional energy transfer of excited ions is shown to proceed at the ion-molecule collision rate with average energies...

  12. Exotic phenomena in collisions of very heavy ions

    International Nuclear Information System (INIS)

    Soff, G.; Mueller, U.; Schramm, S.; de Reus, T.; Mehler, G.; Reinhardt, J.; Mueller, B.; Greiner, W.

    1987-01-01

    Over the last decade their knowledge on atomic structure of superheavy quasimolecules in the range 110 ≤ Z/sub tot/ ≤ 188 has increased considerably. Heavy ion collisions, in which superheavy quasimolecules are formed for a short period of time, offer them a unique tool to investigate the electronic structure of ultra-high Z-systems, which are not otherwise accessible to experiment. Comparison of K-vacancy formation, δ-electron and positron emission with available experimental data suggests the validity of the quasimolecular picture, which will be taken as the theoretical framework of these calculations. To exemplify current theoretical investigations three different topics will be discussed. After a presentation of the underlying theoretical framework for ionization processes the possibility to employ δ-electron emission as a clock to measure nuclear reaction times in intermediate energy collisions of very heavy ions will be sketched. Besides the phenomenon of vacuum decay into a new twofold negatively charged stable vacuum ground state, electron excitation in heavy ion collisions may be employed for the determination of delay and deceleration times on the nuclear time scale, i.e. offering an atomic clock, operating in the range 10 -21 - 10 -24 s. In deep-inelastic heavy ion collisions this provides a test for classical nuclear reaction models. In collisions at intermediate energies an independent measurement of the deceleration time is of interest for comparison, e.g., with the results of the pion bremsstrahlung model. After that the influence of one or more pockets in the ion scattering potential on the energy distribution of emitted positrons within a quantum mechanical framework is investigated. Finally phenomenological corrections to the Dirac equation and its consequences on electron binding energies in heavy and superheavy atoms is briefly considered. 42 references, 5 figures

  13. Localization effects in heavy ion collisions

    International Nuclear Information System (INIS)

    Donangelo, R.J.

    1984-01-01

    Radial and angular localization in heavy ion reactions on deformed nuclei is discussed. A theoretical method appropriate to study these localization effects is briefly described and then applied to the determination of deformed heavy ion potentials from inclastic scattering data. It is argued that one-and two-nucleon transfer reactions on deformed nuclei can provide a probe of nuclear structure in high angular momentum states and be at least qualitatively analyzed in the light of these localization concepts. (Author) [pt

  14. Atomic collisions with 33-TeV lead ions

    International Nuclear Information System (INIS)

    Vane, C.R.; Datz, S.; Krause, H.F.; Dittner, P.F.; Deveney, E.F.; Schuch, R.; Gao, H.

    1997-01-01

    Recent availability of relativistic and ultrarelativistic beams of heavy ions has permitted the first controlled studies of atomic collisions at energies sufficient to measure effects of several new basic phenomena. These include measurements substantiating recently predicted finite nuclear size effects resulting in a reduction in the total electronic energy loss of heavy ions in matter, and measurements of Coulomb collisions in which electrons are excited from the Dirac negative energy continuum. Measurements of total energy loss, free electron-positron pair production, and electron capture from pair production have been recently performed using 33-TeV Pb 82+ ions from the CERN SPS accelerator in Geneva. Results of these studies are presented, along with comparisons with relevant theory. (orig.)

  15. Atomic collisions with 33-TeV lead ions

    International Nuclear Information System (INIS)

    Vane, C.R.; Datz, S.; Krause, H.F.

    1996-01-01

    Recent availability of relativistic and ultrarelativistic beams of heavy ions has permitted the first controlled studies of atomic collisions at energies sufficient to measure effects of several new basic phenomena. These include measurements substantiating recently predicted finite nuclear size effects resulting in a reduction in the total electronic energy loss of heavy ions in matter, and measurements of Coulomb collisions in which electrons are excited from the Dirac negative energy continuum. Measurements of total energy loss, free electron-positron pair production, and electron capture from pair production have been recently performed using 33-TeV Pb 82+ ions from the CERN SPS accelerator in Geneva. Results of these studies are presented, along with comparisons with relevant theory

  16. Auger processes in ion-surface collisions

    International Nuclear Information System (INIS)

    Zampieri, Guillermo.

    1985-01-01

    Bombardment of solid targets with low-energy noble gas ions can produce Auger electron emission from the target atoms and/or from the projectiles. In the case of Auger emission from the projectile, Auger emission was observed during the bombardment of Na, Mg, Al and Si with Ne + ions. This emission was studied as a function of the energy, incidence angle and charge state of the projectile. From the analysis, it is concluded that the emission originates in the decay in vacuum of excited and reflected Ne atoms, moving outside the surface. Auger emission was not observed during the bombardment of K, V and Ni with Ar + ions; Zr and Cs with Kr + , and Xe + ions, respectively; and Li and Be with He + ions. In the case of Auger emission from the target, studies of certain aspects of the Na, Mg and Al Auger electron emission spectra were made. The results allow to identify two components in the Auger feature, coresponding to two kinds of Auger transition. The total spectra results from the superposition of both kinds of emission. Auger spectra from K obtained during Ar + and K + bombardment of K-implanted Be, Mg, Al and Cu were also analyzed. Similar to the Na, Mg and Al Auger spectra, the K Auger feature is composed of an atomic like peak superimposed on a bandlike structure. Both components correspond to Auger transitions in K atoms with a 3p vacancy, occuring in vacuum and inside the solid, respectively. (M.E.L.) [es

  17. Two-gluon correlations in heavy–light ion collisions

    International Nuclear Information System (INIS)

    Wertepny, Douglas E.

    2014-01-01

    We derive the cross-section for two-gluon production in heavy–light ion collisions in the saturation/Color Glass Condensate framework. This calculation includes saturation effects to all orders in one of the nuclei (heavy ion) along with a single saturation correction in the projectile (light ion). The calculation of the correlation function predicts (qualitatively) two identical ridge-like correlations, near- and away-side. This prediction was later supported by experimental findings in p + A collisions at the LHC. Concentrating on the energy and geometry dependence of the correlation functions we find that the correlation function is nearly center-of-mass energy independent. The geometry dependence of the correlation function leads to an enhancement of near- and away-side correlations for the tip-on-tip U + U collisions when compared with side-on-side U + U collisions, an exactly opposite behavior from the correlations generated by the elliptic flow of the quark–gluon plasma

  18. Universal pion freeze-out in heavy-ion collisions

    CERN Document Server

    Adamova, D; Appelshäuser, H; Belaga, V; Braun-Munzinger, P; Castillo, A; Cherlin, A; Damjanovic, S; Dietel, T; Dietrich, L; Drees, A; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Zeev; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Kushpil, V; Lenkeit, B C; Ludolphs, W; Maas, A; Marin, A; Milosevic, J; Milov, A; Miskowiec, D; Panebratsev, Yu A; Petchenova, O Yu; Petracek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Rehak, P; Sako, H; Schükraft, Jürgen; Sedykh, S; Shimansky, S S; Slivova, J; Specht, H J; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, Itzhak; Wessels, J P; Wienold, T; Windelband, B; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V; Schmitz, W

    2003-01-01

    Based on an evaluation of recent systematic data on two-pion interferometry and on measured particle yields at mid-rapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda_f reaches a value of approximately 2.5 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and its value is constant at all currently available beam energies from AGS to RHIC.

  19. Event-By-Event Initial Conditions for Heavy Ion Collisions

    Science.gov (United States)

    Rose, S.; Fries, R. J.

    2017-04-01

    The early time dynamics of heavy ion collisions can be described by classical fields in an approximation of Quantum ChromoDynamics (QCD) called Color Glass Condensate (CGC). Monte-Carlo sampling of the color charge for the incoming nuclei are used to calculate their classical gluon fields. Following the recent work by Chen et al. we calculate the energy momentum tensor of those fields at early times in the collision event-by-event. This can then be used for subsequent hydrodynamic evolution of the single events.

  20. Vorticity and particle polarization in heavy ion collisions (experimental perspective)

    Science.gov (United States)

    Voloshin, Sergei A.

    2018-02-01

    The recent measurements of the global polarization and vector meson spin alignment along the system orbital momentum in heavy ion collisions are briefly reviewed. A possible connection between the global polarization and the chiral anomalous effects is discussed along with possible experimental checks. Future directions, in particular those aimed on the detailed mapping of the vorticity fields, are outlined. The Blast Wave model is used for an estimate of the anisotropic flow effect on the vorticity component along the beam direction. We also point to a possibility of a circular pattern in the vorticity field in asymmetric, e.g. Cu+Au, central collisions.

  1. Vorticity and particle polarization in heavy ion collisions (experimental perspective

    Directory of Open Access Journals (Sweden)

    Voloshin Sergei A.

    2018-01-01

    Full Text Available The recent measurements of the global polarization and vector meson spin alignment along the system orbital momentum in heavy ion collisions are briefly reviewed. A possible connection between the global polarization and the chiral anomalous effects is discussed along with possible experimental checks. Future directions, in particular those aimed on the detailed mapping of the vorticity fields, are outlined. The Blast Wave model is used for an estimate of the anisotropic flow effect on the vorticity component along the beam direction. We also point to a possibility of a circular pattern in the vorticity field in asymmetric, e.g. Cu+Au, central collisions.

  2. Pion source parameters in heavy ion collisions

    International Nuclear Information System (INIS)

    Crowe, K.M.; Bistirlich, J.A.; Bossingham, R.R.

    1984-12-01

    Following the early work of Goldhaber, Lee, and Pais, many experiments have used the momentum correlations between identical bosons to determine the space-time extent of the pion source for various reactions between elementary hadrons. This technique, known as intensity interferometry, has recently been applied to nuclear collisions at both intermediate and very high energies. Here we report on measurements of the radius and lifetime of the pion source in the reactions 1.8 A GeV 40 Ar + KCl → 2π/sup +-/ + X, 1.8 A GeV 20 Na + NaF → 2π - + X, and 1.71 A GeV 56 Fe + Fe → 2π - + X. 11 references

  3. Heavy Flavor in heavy ion collisions

    International Nuclear Information System (INIS)

    Ruan, L.J.

    2010-01-01

    The recent results on heavy flavor at the Relativistic Heavy Ion Collider will be reviewed. The results on charm cross section, heavy flavor collectivity and energy loss, color screening effect and quarkonia production mechanism will be highlighted. Precise measurements with future detector upgrades will be discussed.

  4. Electronic excitation in ion-atom collisions

    International Nuclear Information System (INIS)

    Rodriguez, V.D.; Miraglia, J.E.

    1988-01-01

    Theoretical calculations for excitation of hydrogen-like atoms by ion impact at high and intermediate energies, are presented. Impulsive and eikonal wave functions are employed, both normalized. It is studied the dependence on energy and projectil charge (saturation) of cross sections, compared to experimental results. (A.C.A.S.) [pt

  5. Head-on collision of dust-ion-acoustic solitons in electron-dust-ion ...

    Indian Academy of Sciences (India)

    March 2013 physics pp. 519–531. Head-on collision of dust-ion-acoustic solitons in electron-dust-ion quantum plasmas. PRASANTA CHATTERJEE1, MALAY KUMAR GHORUI1,2,∗ and RAJKUMAR ROYCHOUDHURY3. 1Department of Mathematics, Siksha Bhavana, Visva Bharati University,. Santiniketan 731 235, India.

  6. Mean field instabilities in dissipative heavy ion collisions

    International Nuclear Information System (INIS)

    Colonna, M.; Guarnera, A.; Istituto Nazionale di Fisica Nucleare, Bologna; Catania Univ.; Di Torro, M.; Catania Univ.

    1995-01-01

    We discuss new reaction mechanisms that may occur in semi-peripheral heavy ion collisions at intermediate energies. In particular we focus on the dynamics of the overlapping zone, showing the development of neck instabilities, coupled with the possibility of an increasing amount amount of dynamical fluctuations. In a very selected beam energy range between 40 and 70 MeV/u we observe an important interplay between stochastic nucleon exchange and the random nature of nucleon-nucleon collisions. Expected consequences are intermediate mass fragment emissions from the neck region and large variances in the projectile-like and target-like observables. The crucial importance of a time matching between the growth of mean field instabilities and the separation of the interacting system is stressed. Some hints towards the observation of relatively large instability effects in deep inelastic collisions at lower energy are finally suggested. (authors). 29 refs., 5 figs., 2 tabs

  7. QCD Jets and particle correlations in heavy-ion collisions

    CERN Document Server

    Nguyen, Matthew

    2017-01-01

    Measurements of jets and particle correlations in nucleus-nucleus collisions are intended to probe QCD interactions in the high temperature phase, where matter is understood to behave as a quark-gluon plasma. Two probes are reviewed: jets which are used to study the energy loss of hard-scattered partons in this medium and particle correlations which are used to understand collective effects of the bulk matter. Whereas collisions of lighter systems, namely proton-ion and proton-proton, initially served primarily as control experiments, certain (but not all) effects first observed in nucleus-nucleus collisions have proven to be pervasive in these systems. Comparative measurements in these three systems have broadened our understanding of many-body QCD phenomena, and raised new questions. This talk reviewed these recent developments.

  8. Heavy-ion peripheral collisions in the Fermi energy domain: fragmentation processes or dissipative collisions

    International Nuclear Information System (INIS)

    Borderie, B.; Rivet, M.F.; Tassan-Got, L.

    1990-01-01

    For several years a new field in nuclear physics has been opened by the opportunity to accelerate heavy ions through an energy domain including the Fermi energy of nucleons. This new domain has to be seen as a link between dissipative processes observed at low energies, dominated by mean field considerations, and high energy collisions for which nucleon-nucleon collisions play an important role. This paper reviews our present knowledge on peripheral collisions. A reminder of contiguous energy domains is done as well as their extension in the new field. Specific calculations are also presented. Finally a wide comparison between experiments and calculations is performed. A fast dissipative stage proves to be responsible for the dominant mechanisms involved, at least when the incident energy is lower than 50 MeV/nucleon

  9. Towards relativistic heavy ion collisions by small steps towards the stars

    International Nuclear Information System (INIS)

    Scott, D.K.

    1979-03-01

    A review lecture is given on current attempts to search for the exotic processes occurring in relativistic heavy ion collisions. From peripheral collisions the discussion proceeds to central collisions and lastly the search for the exotic, in which the tools developed for the study of peripheral and central collisions are used. 200 references

  10. Transfer of momentum, mass and charge in heavy ion collisions

    International Nuclear Information System (INIS)

    Beck, F.; Feldmeier, H.; Dworzecka, M.

    1979-01-01

    A model for the first two phases of heavy ion collisions based on the transport of single nucleons through the window between the two scattering nuclei is described in some detail. It is pointed out that the model can account simultaneously for a large portion of the energy transfer from relative to intrinsic motion and for the observed variances in mass and charge numbers for reaction times up to the order of 10 -21 s. (P.L.)

  11. Transverse flow of kaons in heavy-ion collisions

    CERN Document Server

    Zheng Yu Ming; Fuchs, C; Faessler, A; Xiao Wu; Hua Da Ping; Yan Yu Peng

    2002-01-01

    The transverse flow of positively charged kaons from heavy-ion collisions at intermediate energy is investigated within the framework of the quantum molecular dynamics model. The calculated results show that the experimental data are only consistent with those including the kaon mean-field potential from the chiral Lagrangian. This indicates that the transverse flow pattern of kaons is a useful probe of the kaon potential in a nuclear medium

  12. Studying heavy-ion collisions with FAUST-QTS

    Directory of Open Access Journals (Sweden)

    Cammarata P.

    2015-01-01

    Full Text Available Heavy-ion collisions at lower energies provide a rich environment for investigating reaction dynamics. Recent theory has suggested a sensitivity to the symmetry energy and the equation of state via deformations of the reaction system and ternary breaking of the deformed reaction partners into three heavy fragments. A new detection system has been commissioned at Texas A&M University in an attempt to investigate some of the observables sensitive to the nuclear equation of state.

  13. Transport theory of dissipative heavy-ion collisions

    International Nuclear Information System (INIS)

    Norenberg, W.

    1979-01-01

    The lectures present the formulation of a transport theory, the derivation of a practicable transport equation (Fokker-Planck equation) and the evaluation of transport coefficients for dissipative (or deeply inelastic) heavy-ion collisions. The applicability of the theoretical concept is tested with remarkable success in the analyses of various experimental information (mass transfer, angular-momentum dissipation and energy loss). Some critical remarks on the present situation of transport theories are added. Future developments are outlined. (author)

  14. How (non-) linear is the hydrodynamics of heavy ion collisions?

    CERN Document Server

    Floerchinger, Stefan; Beraudo, Andrea; Del Zanna, Luca; Inghirami, Gabriele; Rolando, Valentina

    2014-01-01

    We provide evidence from full numerical solutions that the hydrodynamical evolution of initial density fluctuations in heavy ion collisions can be understood order-by-order in a perturbative series in deviations from a smooth and azimuthally symmetric background solution. To leading linear order, modes with different azimuthal wave numbers do not mix. Quadratic and higher order corrections are small and can be understood as overtones with corresponding wave numbers.

  15. Multi module model for ultra-relativistic heavy ion collisions

    CERN Document Server

    Magas, V K; Strottman, D D

    2001-01-01

    The Multi Module Model for Ultra-Relativistic Heavy Ion Collisions at RHIC and LHC energies is presented. It uses the Effective String Rope Model for the calculation of the initial stages of the reaction; the output of this model is used as the initial state for the subsequent one-fluid calculations. It is shown that such an initial state leads to the creation of the third flow component. The hydrodynamical evolution of the energy density distribution is also presented.

  16. Comparison of models of high energy heavy ion collision

    International Nuclear Information System (INIS)

    Gyulassy, M.

    1977-01-01

    Some of the main theoretical developments on heavy ion collisions at energies (0.1 to 2.0) GeV/nuc are reviewed. The fireball, firestreak, hydrodynamic (1-fluid, 2-fluids), ''row on row'', hard sphere and intranuclear cascades, and classical equations of motion models are discussed in detail. Results are compared to each other and to measured Ne + U → p + X reactions

  17. Ion-atom collisions for materials study

    International Nuclear Information System (INIS)

    Loaiza S, N.S.

    1976-01-01

    The diffusion process of silver in aluminium was studied in thin films as a function of temperature, the most important characteristics of dispersor atoms that technique permits us to study are the atomic mass and depth into the solid. This is possible because when a sample is bombarded with ions of a given energy, the ions are dispersed with different energies for different masses and depths, hence this technique is a useful instrument for research into the physical processes which ocurr in thin films up to depths of several microns, one of the results obtained after the bombardment of the target with protons having an energy of 650 KeV was that when the target reached a temperature of approximately 40 0 C, 80 0 C, 110 0 C and 160 0 C during 15 minutes and the spectra of heated and unheated targets were compared it was found that the aluminium peak, the valley, the silver peak and the peak over the silver peak change with the increase of temperature and tend to get mixed, that is to say that silver and the aluminium are diffusing themselves. The analysis is essentially qualitative with this technique we ca also measure the thickness of thin films, the silver thickness was measured (3320A). (author)

  18. Freeze-out dynamics in heavy-ion collisions: Recent advances

    Indian Academy of Sciences (India)

    2015-05-01

    May 1, 2015 ... and heavy-ion collisions, a picture emerges in which hadrons are born in chemical equilibrium at hadronization, thereafter undergoing inelastic and elastic collisions whose impact on the primordial distribution depends on the system size. Keywords. Relativistic heavy-ion collisions; freeze-out; statistical ...

  19. Colour rope model for extreme relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Biro, T.S.; Nielsen, H.B.; Knoll, J.

    1984-04-01

    Our goal is to investigate the possible cumulative effects of the colour fields of the observable meson multiplicity distribution in the central rapidity region in extreme relativistic heavy ion collisions. In the first Chapter we overview the space-time picture of the string formation in a central heavy ion collision. We take into account trivial geometrical factors in a straight line geometry. In the second Chapter we consider the colour chargation process of heavy ions as a random walk. We calculate the expectation value and the relative standard deviation of the total effective charge square. In the third Chapter we consider the stochastic decay of a K-fold string-rope to mesons by the Schwinger-mechanism. We calculate the expected lifetime of a K-fold string and the time for the first quark antiquark pair creation. In the fourth Chapter we deal with the meson production of a K-fold rope relative to that of a single string and hence we look for a scaling between A + A and p + p collisions. (orig./HSI)

  20. An investigation of collision propagation in energetic ion initiated cascades in copper

    International Nuclear Information System (INIS)

    Chakarov, I.R.; Webb, R.P.; Smith, R.; Beardmore, K.

    1995-01-01

    Using simple Binary Collision simulations of energetic ion initiated collision cascades, particles are considered to undergo a series of binary collisions with their surroundings. In Molecular Dynamics simulation it is difficult to even define what is meant by a collision as the interaction potentials are infinite in nature and consequently all particles are considered to interact with all other particles. By making a suitable definition of a collision for Molecular Dynamics we are able to compare the temporal behaviour of the number of collisions occurring during the propagation of a collision cascade between the two different calculation schemes. An investigation is made of the number of collisions as a function of time occurring in collision cascades. We compare these results to the time ordered version of MARLOWE. By making further definitions about what makes a many body collision, we further investigate the numbers of many body collisions occurring during a number of collision cascades. (orig.)

  1. Approach to equilibrium in high energy heavy ion collisions

    International Nuclear Information System (INIS)

    Epelbaum, Thomas

    2014-01-01

    This thesis deals with the theory of the early stages of a heavy ion collision. Just after such a collision, the matter produced - called the Quark-Gluon-Plasma (QGP) - has been shown to be far out of thermal equilibrium. One would like to know whether the QGP thermalizes, and what is the typical time scale for this. Proving that the QGP thermalizes would also justify from first principles the hydrodynamical treatment of the subsequent evolution of a heavy ion collision. After having recalled some essential theoretical concepts, the manuscript addresses these questions in two different theories. In a first part, we study a scalar field theory. Starting from an out of equilibrium initial condition, one studies the approach to equilibrium in a fixed volume or in a one-dimensional expanding system. In both cases, clear signs of thermalization are obtained: an equation of state is formed, the pressure tensor becomes isotropic and the occupation number approaches a classical thermal distribution. These results are obtained thanks to the classical statistical approximation (CSA), that includes contributions beyond the Leading Order perturbative calculation. In a second part, the Color Glass Condensate - a quantum chromodynamics (QCD) effective theory well suited to describe the early life of the QGP - is used to treat more realistically the approach to thermalization in heavy ion collisions. After having derived some analytical prerequisites for the application of the CSA, the numerical simulations performed with the Yang-Mills equations show evidences of an early onset of hydrodynamical behavior of the QGP: the system becomes isotropic on short time scales, while the shear viscosity over entropy ratio is very small, which is characteristic of a quasi perfect fluid. (author) [fr

  2. Mass Spectra and Ion Collision Cross Sections of Hemoglobin

    Science.gov (United States)

    Kang, Yang; Terrier, Peran; Douglas, D. J.

    2011-02-01

    Mass spectra of commercially obtained hemoglobin (Hb) show higher levels of monomer and dimer ions, heme-deficient dimer ions, and apo-monomer ions than hemoglobin freshly prepared from blood. This has previously been attributed to oxidation of commercial Hb. Further, it has been reported that that dimer ions from commercial bovine Hb have lower collision cross sections than low charge state monomer ions. To investigate these effects further, we have recorded mass spectra of fresh human Hb, commercial human and bovine Hb, fresh human Hb oxidized with H2O2, lyophilized fresh human Hb, fresh human Hb both lyophilized and chemically oxidized, and commercial human Hb oxidized with H2O2. Masses of α-monomer ions of all hemoglobins agree with the masses expected from the sequences within 3 Da or better. Mass spectra of the β chains of commercial Hb and oxidized fresh human Hb show a peak or shoulder on the high mass side, consistent with oxidation of the protein. Both commercial proteins and oxidized fresh human Hb produce heme-deficient dimers with masses 32 Da greater than expected and higher levels of monomer and dimer ions than fresh Hb. Lyophilization or oxidation of Hb both produce higher levels of monomer and dimer ions in mass spectra. Fresh human Hb, commercial human Hb, commercial bovine Hb, and oxidized commercial human Hb all give dimer ions with cross sections greater than monomer ions. Thus, neither oxidation of Hb or the difference in sequence between human and bovine Hb make substantial differences to cross sections of ions.

  3. Ionization of excited hydrogen and excited hydrogen-like ions in collisions with bare ions

    International Nuclear Information System (INIS)

    Igarashi, Akinori; Shirai, Toshizo

    1995-01-01

    Accompanying the heightening of the density of nuclear fusion plasma and the heightening of the energy of incident atoms, attention has been paid to multi-stage collision excitation process. This collision process possesses a large cross section, and the evaluation of the cross section is an urgent task to analyze the efficiency of plasma heating. In this study, by using CDW-EIS approximation, of which the calculation is relatively easy, the ionization cross section in the collision of bare ions with excited state hydrogen and hydrogen-like ions was calculated. The CDW-EIS approximation was introduced by Crothers and McCann, and it is the high energy approximation that reproduces best the experimental data on the ionization cross section of ground state hydrogen by bare ions. It was confirmed by the result of make-up calculation that if energy becomes high to some extent, the CDW-EIS approximation and Born approximation approach and agree for the ionization from ground state and also from excited state. The results of the ionization collision of bare ions with excited hydrogen atoms and excited hydrogen-like ions are reported. (K.I.)

  4. $J/\\psi$ Absorption in Heavy Ion Collisions

    CERN Document Server

    Maiani, Luciano; Polosa, Antonio; Riquer, V

    2004-01-01

    We present a new calculation of the pi-J/psi dissociation cross sections within the Constituent Quark-Meson Model recently introduced. To discuss the absorption of J/psi in heavy-ion collisions, we assume the J/psi to be produced inside a thermalized pion gas, as discussed by Bjorken, and introduce the corrections due to absorption by nuclear matter as well. We fit the absorption length of the J/psi to the data obtained at the CERN SPS by the NA50 Collaboration for Pb-Pb collisions. Collisions of lower centrality allow us to determine the temperature and the energy density of the pion gas. For both these quantities we find values close to those indicated by lattice gauge calculations for the transition to a quark-gluon plasma. A simple extrapolation to more central collisions, which takes into account the increase of the energy deposited due to the increased nucleon flux, fails to reproduce the break in J/psi absorption indicated by NA50, thus lending support to the idea that an unconfined quark-gluon phase m...

  5. Doubly charmed baryon production in heavy ion collisions

    Science.gov (United States)

    Yao, Xiaojun; Müller, Berndt

    2018-04-01

    We give an estimate of Ξcc ++ production rate and transverse momentum spectra in relativistic heavy ion collisions. We use Boltzmann transport equations to describe the dynamical evolution of charm quarks and diquarks inside quark-gluon plasma. In-medium formation and dissociation rates of charm diquarks are calculated from potential nonrelativistic QCD for the diquark sector. We solve the transport equations by Monte Carlo simulations. For 2.76 TeV Pb-Pb collisions with 0-10% centrality, the number of Ξcc ++ produced in the transverse momentum range 0-5 GeV and rapidity from -1 to 1 is roughly 0.02 per collision. We repeat the calculation with a melting temperature 250 MeV above which no diquarks can be formed. The number of Ξcc ++ produced in the same kinematic region is about 0.0125 per collision. We discuss how to study diquarks at finite temperature on a lattice and construct the antitriplet free energy in a gauge invariant but path dependent way. We also comment on extensions of the calculation to other doubly heavy baryons and doubly heavy tetraquarks and the feasibility of experimental measurements.

  6. Large amounts of antiproton production by heavy ion collision

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroshi; Powell, J.

    1987-01-01

    To produce large amounts of antiprotons, on the order of several grams/year, use of machines to produce nuclear collisions are studied. These can be of either proton-proton, proton-nucleus and nucleus-nucleus in nature. To achieve high luminosity colliding beams, on the order of 10/sup 41/ m/cm/sup 2/, a self-colliding machine is required, rather than a conventional circular colliding type. The self-colliding machine can produce additional antiprotons through successive collisions of secondary particles, such as spectator nucleons. A key problem is how to collect the produced antiprotons without capture by beam nuclei in the collision zone. Production costs for anti-matter are projected for various energy source options and technology levels. Dedicated facilities using heavy ion collisions could produce antiproton at substantially less than 1 million $/milligram. With co-production of other valuable products, e.g., nuclear fuel for power reactors, antiproton costs could be reduced to even lower values.

  7. Evidence for chiral symmetry restoration in heavy-ion collisions

    Science.gov (United States)

    Moreau, P.; Palmese, A.; Cassing, W.; Seifert, E.; Steinert, T.; Bratkovskaya, E. L.

    2017-11-01

    We study the effect of the chiral symmetry restoration (CSR) on heavy-ion collisions observables in the energy range √{sNN} = 3- 20GeV within the Parton-Hadron-String Dynamics (PHSD) transport approach. The PHSD includes the deconfinement phase transition as well as essential aspects of CSR in the dense and hot hadronic medium, which are incorporated in the Schwinger mechanism for particle production. Our systematic studies show that chiral symmetry restoration plays a crucial role in the description of heavy-ion collisions at √{sNN} = 3- 20GeV, realizing an increase of the hadronic particle production in the strangeness sector with respect to the non-strange one. Our results provide a microscopic explanation for the horn structure in the excitation function of the K+ /π+ ratio: the CSR in the hadronic phase produces the steep increase of this particle ratio up to √{sNN} ≈ 7GeV, while the drop at higher energies is associated to the appearance of a deconfined partonic medium. Furthermore, the appearance/disappearance of the horn structure is investigated as a function of the system size. We additionally present an analysis of strangeness production in the (T ,μB)-plane (as extracted from the PHSD for central Au+Au collisions) and discuss the perspectives to identify a possible critical point in the phase diagram.

  8. Shannon information entropy in heavy-ion collisions

    Science.gov (United States)

    Ma, Chun-Wang; Ma, Yu-Gang

    2018-03-01

    The general idea of information entropy provided by C.E. Shannon "hangs over everything we do" and can be applied to a great variety of problems once the connection between a distribution and the quantities of interest is found. The Shannon information entropy essentially quantify the information of a quantity with its specific distribution, for which the information entropy based methods have been deeply developed in many scientific areas including physics. The dynamical properties of heavy-ion collisions (HICs) process make it difficult and complex to study the nuclear matter and its evolution, for which Shannon information entropy theory can provide new methods and observables to understand the physical phenomena both theoretically and experimentally. To better understand the processes of HICs, the main characteristics of typical models, including the quantum molecular dynamics models, thermodynamics models, and statistical models, etc., are briefly introduced. The typical applications of Shannon information theory in HICs are collected, which cover the chaotic behavior in branching process of hadron collisions, the liquid-gas phase transition in HICs, and the isobaric difference scaling phenomenon for intermediate mass fragments produced in HICs of neutron-rich systems. Even though the present applications in heavy-ion collision physics are still relatively simple, it would shed light on key questions we are seeking for. It is suggested to further develop the information entropy methods in nuclear reactions models, as well as to develop new analysis methods to study the properties of nuclear matters in HICs, especially the evolution of dynamics system.

  9. Towards relativistic heavy ion collisions 'by small steps towards the stars'

    International Nuclear Information System (INIS)

    Scott, D.K.

    1980-01-01

    Current attempts to search for the exotic processes occurring in relativistic heavy ion collisions are reviewed under the headings; peripheral collisions (peripheral collisions as a function of energy, new features at intermediate energies, ground state correlations, microscopic aspects), central collisions (low energy perspective, time scales in heavy ion collisions, spatial, temporal localization and the onset of the nuclear fireball, models of particle emission in central relativistic collisions, the heart of the matter, multiplicity selection, the emission of composite particles), a search for the exotic (the limits of temperature and pressure, temporal and spatial limits, the limits of nuclear matter and nuclei,). 229 references. (U.K.)

  10. Ion heating due to rotation and collision in magnetized plasma

    International Nuclear Information System (INIS)

    Anderegg, F.; Stern, R.A.; Skiff, F.; Hammel, B.A.; Tran, M.Q.; Paris, P.J.; Kohler, P.

    1986-01-01

    The E x B rotation and associated collisional ion heating of noble-gas magnetized plasmas are investigated with high resolution by means of laser-induced fluorescence and electrical probes. Plasma rotation results from a radial potential gradient which can be controlled by biasing of the discharge electrodes. The time and space evolution of the potential, the rotation velocity v/sub t//sub h//sub e//sub t//sub a/, and the ion perpendicular temperature indicate that heating is due to the randomization of v/sub t//sub h//sub e//sub t//sub a/ by ion-neutral collisions, and leads to temperature increases as high as a factor of 50 over initial values

  11. Chemical freeze-out in relativistic heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    Jun Xu

    2017-09-01

    Full Text Available One surprising result in relativistic heavy-ion collisions is that the abundance of various particles measured in experiments is consistent with the picture that they reach chemical equilibrium at a temperature much higher than the temperature they freeze out kinetically. Using a multiphase transport model to study particle production in these collisions, we find, as an example, that the effective pion to nucleon ratio, which includes those from resonance decays, indeed changes very little during the evolution of the hadronic matter from the chemical to the kinetic freeze-out, and it is also accompanied by an almost constant specific entropy. We further use a hadron resonance gas model to illustrate the results from the transport model study.

  12. Head-on collision of dust-ion-acoustic solitons in electron-dust-ion ...

    Indian Academy of Sciences (India)

    acoustic (DIA) soli- tons in quantum electron-dust-ion plasma. Using the extended Poincaré–Lighthill–Kuo (PLK) method, we obtain the Korteweg–de Vries (KdV) equations, the phase shifts and the trajecto- ries after the head-on collision of the two ...

  13. Gauge/String Duality, Hot QCD and Heavy Ion Collisions

    CERN Document Server

    Casalderrey-Solana, Jorge; Mateos, David; Rajagopal, Krishna; Wiedemann, Urs Achim

    2011-01-01

    Over the last decade, both experimental and theoretical advances have brought the need for strong coupling techniques in the analysis of deconfined QCD matter and heavy ion collisions to the forefront. As a consequence, a fruitful interplay has developed between analyses of strongly-coupled non-abelian plasmas via the gauge/string duality (also referred to as the AdS/CFT correspondence) and the phenomenology of heavy ion collisions. We review some of the main insights gained from this interplay to date. To establish a common language, we start with an introduction to heavy ion phenomenology and finite-temperature QCD, and a corresponding introduction to important concepts and techniques in the gauge/string duality. These introductory sections are written for nonspecialists, with the goal of bringing readers ranging from beginning graduate students to experienced practitioners of either QCD or gauge/string duality to the point that they understand enough about both fields that they can then appreciate their in...

  14. Mass and charge distribution in heavy-ion collisions

    International Nuclear Information System (INIS)

    Beck, F.; Dworzecka, M.; Feldmeier, H.

    1978-01-01

    A statistical model based on the independent particle picture is used to calculate mass and charge distributions in deep inelastic heavy-ion collisions. Different assumptions on volume and charge equilibrations are compared with measured variances of charge distributions. One combination of assumptions is clearly favoured by experiment, and gives a reasonable description of the variance versus energy loss curves up to energy losses of about 200 MeV in the heavy systems Kr+Ho and Xe+Bi, and up to about 60 MeV for the light system Ar+Ca [af

  15. Artificial neural network modelling in heavy ion collisions

    International Nuclear Information System (INIS)

    El-dahshan, E.; Radi, A.; El-Bakry, M.Y.; El Mashad, M.

    2008-01-01

    The neural network (NN) model and parton two fireball model (PTFM) have been used to study the pseudo-rapidity distribution of the shower particles for C 12, O 16, Si 28 and S 32 on nuclear emulsion. The trained NN shows a better fitting with experimental data than the PTFM calculations. The NN is then used to predict the distributions that are not present in the training set and matched them effectively. The NN simulation results prove a strong presence modeling in heavy ion collisions

  16. Expectations and realities in relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Hwa, R.C.

    1988-06-01

    Interpretations of some recent results from experiments done at the CERN-SPS on relativistic heavy-ion collisions are discussed. A cautionary note is given for the observed J//Psi/ suppression due to the hadronic interaction of J//Psi/ in the final state. The multiplicity dependence of average transverse momentum has many complications, and is unsuitable as an indicator of phase transition. Multiplicity fluctuation may be a better diagnostic tool. No indication of any collective behavior has been seen in the recent experiments. 30 refs., 3 figs

  17. Radiative double electron capture (RDEC) in ion-atom collisions

    Science.gov (United States)

    Simon, A.; Tanis, J. A.; Elkafrawy, T.; Warczak, A.

    2012-11-01

    Radiative double electron capture (RDEC) observed in collisions of bare ions with atoms is a charge exchange process, during which two target electrons are captured into a bound state of the projectile and a single photon is emitted. This process could be related to the time inverse of double photoionization. For the past twenty years it has been studied, both experimentally and theoretically. However, significant discrepancies between theoretical predictions of the RDEC cross section and experimental results were noted. Here, an overview of the investigation of the RDEC process is given and various theoretical predictions are compared with experimental results.

  18. On $Z$ and $Z + jet$ Production in Heavy Ion Collisions

    OpenAIRE

    Kartvelishvili, V.; Kvatadze, R.; Shanidze, R.

    1995-01-01

    Z+jet production in heavy ion collisions at the LHC is proposed as a possible probe of the properties of the dense hadronic matter. It is shown that the accuracy of this measurement with general purpose LHC detectors and under realistic experimental conditions can be high enough. It is argued also that $Z$-boson production and subsequent leptonic decay is a good reference process for this measurement, as well as for the QCD process of high $P_T$ jet pair production.

  19. Radial and tangential friction in heavy ion strongly damped collisions

    International Nuclear Information System (INIS)

    Jain, A.K.; Sarma, N.

    1979-01-01

    Deeply inelastic heavy ion collisions have been successfully described in terms of a nucleon exchange mechanism between two nucleon clouds. This model has also predicted the large angular momentum that is induced in the colliding nuclei. However computations were simplified in the earlier work by assuming that the friction was perturbation on the elastic scattering trajectory. Results of a more rigorous calculation are reported and the effect of modification of the trajectory on the energy transfer, the angular momentum induced and on the ratio of the radial to the tangential friction coefficients is reported. (auth.)

  20. Entropy of the system formed in heavy ion collision

    International Nuclear Information System (INIS)

    Gudima, K.K.; Schulz, H.; Toneev, V.D.

    1985-01-01

    In frames of a cascade model the entropy evolution in a system producted in heavy ion collisions is investigated. Entropy calculation is based on smoothing of the distribution function over the momentum space by the temperature field introduction. The resulting entropy per one nucleon is shown to be rather sensitive to phase space subdivision into cells at the stage of free scattering of reaction products. Compared to recent experimental results for specific entropy values inferred from the composite particle yield of 4π measurements, it is found that cascade calculations do not favour some particular entropy model treatments and suggest smaller entropy values than following from consideration within equilibrium statistics

  1. A flow paradigm in heavy-ion collisions

    Science.gov (United States)

    Yan, Li

    2018-04-01

    The success of hydrodynamics in high energy heavy-ion collisions leads to a flow paradigm, to understand the observed features of harmonic flow in terms of the medium collective expansion with respect to initial state geometrical properties. In this review, we present some essential ingredients in the flow paradigm, including the hydrodynamic modeling, the characterization of initial state geometry and the medium response relations. The extension of the flow paradigm to small colliding systems is also discussed. Supported by Natural Sciences and Engineering Research Council of Canada

  2. Scaling of anisotropy flows in intermediate energy heavy ion collisions

    International Nuclear Information System (INIS)

    Ma, Y.G.; Yan, T.Z.; Cai, X.Z.; Chen, J.G.; Fang, D.Q.; Guo, W.; Liu, G.H.; Ma, C.W.; Ma, E.J.; Shen, W.Q.; Shi, Y.; Su, Q.M.; Tian, W.D.; Wang, H.W.; Wang, K.

    2007-01-01

    Anisotropic flows (v 1 , v 2 and v 4 ) of light nuclear clusters are studied by a nucleonic transport model in intermediate energy heavy ion collisions. The number-of-nucleon scalings of the directed flow (v 1 ) and elliptic flow (v 2 ) are demonstrated for light nuclear clusters. Moreover, the ratios of v 4 /v 2 2 of nuclear clusters show a constant value of 1/2 regardless of the transverse momentum. The above phenomena can be understood by the coalescence mechanism in nucleonic level and are worthy to be explored in experiments

  3. Heavy Ion Collisions at the LHC - Last Call for Predictions

    Energy Technology Data Exchange (ETDEWEB)

    Armesto, N; Borghini, N; Jeon, S; Wiedemann, U A; Abreu, S; Akkelin, V; Alam, J; Albacete, J L; Andronic, A; Antonuv, D; Arleo, F; Armesto, N; Arsene, I C; Barnafoldi, G G; Barrette, J; Bauchle, B; Becattini, F; Betz, B; Bleicher, M; Bluhm, M; Boer, D; Bopp, F W; Braun-Munzinger, P; Bravina, L; Busza, W; Cacciari, M; Capella, A; Casalderrey-Solana, J; Chatterjee, R; Chen, L; Cleymans, J; Cole, B A; delValle, Z C; Csernai, L P; Cunqueiro, L; Dainese, A; de Deus, J D; Ding, H; Djordjevic, M; Drescher, H; Dremin, I M; Dumitru, A; El, A; Engel, R; d' Enterria, D; Eskola, K J; Fai, G; Ferreiro, E G; Fries, R J; Frodermann, E; Fujii, H; Gale, C; Gelis, F; Goncalves, V P; Greco, V; Gyulassy, M; van Hees, H; Heinz, U; Honkanen, H; Horowitz, W A; Iancu, E; Ingelman, G; Jalilian-Marian, J; Jeon, S; Kaidalov, A B; Kampfer, B; Kang, Z; Karpenko, I A; Kestin, G; Kharzeev, D; Ko, C M; Koch, B; Kopeliovich, B; Kozlov, M; Kraus, I; Kuznetsova, I; Lee, S H; Lednicky, R; Letessier, J; Levin, E; Li, B; Lin, Z; Liu, H; Liu, W; Loizides, C; Lokhtin, I P; Machado, M T; Malinina, L V; Managadze, A M; Mangano, M L; Mannarelli, M; Manuel, C; Martinez, G; Milhano, J G; Mocsy, A; Molnar, D; Nardi, M; Nayak, J K; Niemi, H; Oeschler, H; Ollitrault, J; Paic, G; Pajares, C; Pantuev, V S; Papp, G; Peressounko, D; Petreczky, P; Petrushanko, S V; Piccinini, F; Pierog, T; Pirner, H J; Porteboeuf, S; Potashnikova, I; Qin, G Y; Qiu, J; Rafelski, J; Rajagopal, K; Ranft, J; Rapp, R; Rasanen, S S; Rathsman, J; Rau, P; Redlich, K; Renk, T; Rezaeian, A H; Rischke, D; Roesler, S; Ruppert, J; Ruuskanen, P V; Salgado, C A; Sapeta, S; Sarcevic, I; Sarkar, S; Sarycheva, L I; Schmidt, I; Shoski, A I; Sinha, B; Sinyukov, Y M; Snigirev, A M; Srivastava, D K; Stachel, J; Stasto, A; Stocker, H; Teplov, C Y; Thews, R L; Torrieri, G; Pop, V T; Triantafyllopoulos, D N; Tuchin, K L; Turbide, S; Tywoniuk, K; Utermann, A; Venugopalan, R; Vitev, I; Vogt, R; Wang, E; Wang, X N; Werner, K; Wessels, E; Wheaton, S; Wicks, S; Wiedemann, U A; Wolschin, G; Xiao, B; Xu, Z; Yasui, S; Zabrodin, E; Zapp, K; Zhang, B

    2008-02-25

    In August 2006, the CERN Theory Unit announced to restructure its visitor program and to create a 'CERN Theory Institute', where 1-3 month long specific programs can take place. The first such Institute was held from 14 May to 10 June 2007, focusing on 'Heavy Ion Collisions at the LHC - Last Call for Predictions'. It brought together close to 100 scientists working on the theory of ultra-relativistic heavy ion collisions. The aim of this workshop was to review and document the status of expectations and predictions for the heavy ion program at the Large Hadron Collider LHC before its start. LHC will explore heavy ion collisions at {approx} 30 times higher center of mass energy than explored previously at the Relativistic Heavy Ion Collider RHIC. So, on the one hand, the charge of this workshop provided a natural forum for the exchange of the most recent ideas, and allowed to monitor how the understanding of heavy ion collisions has evolved in recent years with the data from RHIC, and with the preparation of the LHC experimental program. On the other hand, the workshop aimed at a documentation which helps to distinguish pre- from post-dictions. An analogous documentation of the 'Last Call for Predictions' [1] was prepared prior to the start of the heavy-ion program at the Relativistic Heavy Ion Collider RHIC, and it proved useful in the subsequent discussion and interpretation of RHIC data. The present write-up is the documentation of predictions for the LHC heavy ion program, received or presented during the CERN TH Institute. The set-up of the CERN TH Institute allowed us to aim for the wide-most coverage of predictions. There were more than 100 presentations and discussions during the workshop. Moreover, those unable to attend could still participate by submitting predictions in written form during the workshop. This followed the spirit that everybody interested in making a prediction had the right to be heard. To arrive at a concise

  4. Possibilities for relativistic heavy ion collisions at Brookhaven

    International Nuclear Information System (INIS)

    Barton, M.O.; Hahn, H.

    1983-01-01

    Since 1980 there has been considerable interest at Brookhaven in exploiting the existence of the Colliding Beam Accelerator, CBA, earlier referred to as Isabelle, for the generation of heavy ion collisions at very high energies. The only requirement for a heavy ion collider would have been for an energy booster for the Tandem accelerator and a tunnel and magnet transport system to the AGS. For a few million dollars heavy ions up to nearly 200 GeV/amu could be collided with luminosities of 10 27 to 10 28 /cm 2 sec in experimental halls with ideal facilities for heavy ion physics studies. Although the CBA project has been stopped, it is still true that Brookhaven has in place enormous advantages for constructing a heavy ion collider. This paper describes a design that exploits those advantages. It uses the tunnel and other civil construction, the refrigerator, vacuum equipment, injection line components, and the magnet design for which there is expertise and a production facility in place. The result is a machine that appears quite different than would a machine designed from first principles without access to these resources but one which is of high performance and of very attractive cost

  5. Ionization of uracil in collisions with fast bare ions

    Science.gov (United States)

    Tribedi, L. C.; Agnihotri, A. N.; Galassi, M. E.; Rivarola, R. D.; Champion, C.

    2012-11-01

    We study the atomic collisions with large molecules and simple atoms. The ionization and fragmentation spectra are investigated for uracil, a RNA base molecule, under the impact of fast bare C, O and F-ions. The experiments are conducted using a recoil-ion time-of-flight spectrometer. The energy dependence of the total ionization cross sections (TCS) and fragmentation yields are measured for MeV/u energies. In addition, the angular distribution of the electron double differential cross sections (DDCS) are also shown in some cases. The total cross sections of ionization and also the DDCS data are compared with the CDW-EIS calculations. The qualitative agreement is good but, in general, the theory tends to overestimate the data by a factor of 2.2. The angular distribution of electrons clearly indicates a good qualitative agreement except for the lowest energy electrons.

  6. Selected Experimental Results from Heavy-Ion Collisions at LHC

    Directory of Open Access Journals (Sweden)

    Ranbir Singh

    2013-01-01

    Full Text Available We review a subset of experimental results from the heavy-ion collisions at the Large Hadron Collider (LHC facility at CERN. Excellent consistency is observed across all the experiments at the LHC (at center of mass energy sNN=2.76 TeV for the measurements such as charged particle multiplicity density, azimuthal anisotropy coefficients, and nuclear modification factor of charged hadrons. Comparison to similar measurements from the Relativistic Heavy Ion Collider (RHIC at lower energy (sNN=200 GeV suggests that the system formed at LHC has a higher energy density and larger system size and lives for a longer time. These measurements are compared to model calculations to obtain physical insights on the properties of matter created at the RHIC and LHC.

  7. Correlated charge-changing ion-atom collisions

    International Nuclear Information System (INIS)

    Tanis, J.A.

    1992-04-01

    This report summarizes the progress and accomplishments in accelerator atomic physics research supported by DOE grant DE-FG02-87ER13778 from March 16, 1991 through March 15, 1992. This work involves the experimental investigation of fundamental atomic processes in collisions of charged projectiles with neutral targets or electrons, with particular emphasis on two-electron interactions and electron correlation effects. Processes involving combinations of excitation, ionization, and charge transfer are investigated utilizing coincidence techniques in which projectiles charge-changing events are associated with x-ray emission, target recoil ions, or electron emission. New results have been obtained for studies involving (1) resonant recombination of atomic ions, (2) double ionization of helium, and (3) continuum electron emission. Experiments were conducted using accelerators at the Lawrence Berkeley Laboratory, Argonne National Laboratory, Michigan State University, Western Michigan University, and the Institute of Nuclear Research, Debrecen, Hungary. Brief summaries of work completed and work in progress are given in this report

  8. Fragmentation of molecular ions in slow electron collisions

    International Nuclear Information System (INIS)

    Novotny, Steffen

    2008-01-01

    The fragmentation of positively charged hydrogen molecular ions by the capture of slow electrons, the so called dissociative recombination (DR), has been investigated in storage ring experiments at the TSR, Heidelberg, where an unique twin-electron-beam arrangement was combined with high resolution fragment imaging detection. Provided with well directed cold electrons the fragmentation kinematics were measured down to meV collision energies where pronounced rovibrational Feshbach resonances appear in the DR cross section. For thermally excited HD + the fragmentation angle and the kinetic energy release were studied at variable precisely controlled electron collision energies on a dense energy grid from 10 to 80 meV. The anisotropy described for the first time by Legendre polynomials higher 2 nd order and the extracted rotational state contributions were found to vary on a likewise narrow energy scale as the rotationally averaged DR rate coefficient. Ro-vibrationally resolved DR experiments were performed on H 2 + produced in distinct internal excitations by a novel ion source. Both the low-energy DR rate as well as the fragmentation dynamics at selected resonances were measured individually in the lowest two vibrational and first three excited rotational states. State-specific DR rates and angular dependences are reported. (orig.)

  9. Relativistic ion collisions as the source of hypernuclei

    Energy Technology Data Exchange (ETDEWEB)

    Botvina, A.S. [J.W. Goethe University, Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); Russian Academy of Sciences, Institute for Nuclear Research, Moscow (Russian Federation); Bleicher, M.; Steinheimer, J. [J.W. Goethe University, Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); Pochodzalla, J. [J. Gutenberg-Universitaet, Helmholtz-Institut Mainz, Mainz (Germany); J. Gutenberg-Universitaet Mainz, Institut fuer Kernphysik and PRISMA Cluster of Excellence, Mainz (Germany)

    2016-08-15

    We shortly review the theory of hypernuclei production in relativistic ion collisions, that is adequate to future experiments at BM rate at N, NICA, and FAIR. Within a hybrid approach we use transport, coalescence and statistical models to describe the whole process. We demonstrate that the origin of hypernuclei can be explained by typical baryon interactions, that is similar to the production of conventional nuclei. In particular, heavy hypernuclei are coming mostly from projectile and target residues, whereas light hypernuclei can be produced at all rapidities. The yields of hypernuclei increase considerably above the energy threshold for Λ hyperon production, and there is a tendency to saturation of yields of hypernuclei with increasing the beam energy up to few TeV. There are unique opportunities in relativistic ion collisions which are difficult to realize in traditional hypernuclear experiments: The produced hypernuclei have a broad distribution in masses and isospin. They can even reach beyond the neutron and proton drip-lines and that opens a chance to investigate properties of exotic hypernuclei. One finds also the abundant production of multi-strange nuclei, of bound and unbound hypernuclear states with new decay modes. In addition, we can directly get an information on the hypermatter both at high and low temperatures. (orig.)

  10. Photon and dilepton production in high-energy heavy-ion collisions

    Indian Academy of Sciences (India)

    2015-05-07

    -ion collisions, obtained particularly at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) are reviewed. The results are new not only in terms of the probes, but also in terms of the precision. We shall ...

  11. Hard and soft physics of relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Tywoniuk, Konrad

    2008-01-01

    Already over thirty years ago [ 174] it was suggested that it would be interesting to explore new phenomena 'by distributing high energy or high nucleon density over a relatively large volume:' It was soon realized that colliding heavy ions at high energies would provide such conditions. The conditions at RHIC and LHC correspond to the early universe 1 μ after the Big Bang. But does the mini Big Bang created in the laboratory really resemble the cosmological 'bigger brother'? Are the timescales long enough for the particles to 'dissolve' into their smaller constituents? What are the intermediate stages, before the 'dissolving' and also after, when particles are formed? At which energy (or energy density) does this 'melting' happen? More fundamentally, what is the difference between proton-proton and nucleus-nucleus collisions at very high energies? At the LHC one expects that the plasma phase will live much longer than at RHIC. What will be the signatures of this super-QGP? One should be able to answer all of this questions, but, unfortunately, at the present moment we are not. It is therefore very important to understand what the relevant degrees of freedom are in theses extreme situations. Investigation of deep inelastic scattering at very high energies and, in particular, low-x shadowing effects on nuclei can give important information on properties of dense quark-gluon systems. By comparing data at different energies on both proton-nucleus and nucleus-nucleus collisions and interpret them in a comprehensive framework, we hope to learn more about the dynamics leading to the features we see in the data. The thesis consists of two parts. In the first part we will give a short introduction to topics relevant to high-energy collisions while the second part contains the papers written during the thesis work. In Chapter 2 we give a brief account of the main experimental results from heavy-ion experiments. The choice of topics and interpretation of the results is

  12. Jet Physics in Heavy Ion Collisions with Compact Muon Solenoid detector at the LHC

    CERN Document Server

    Lokhtin, I P

    2006-01-01

    The status of CMS jet simulations and physics analysis in heavy ion collisions is presented. Jet reconstruction and high transverse momentum particle tracking in the high multiplicity environment of heavy ion collisions at the LHC using the CMS calorimetry and tracking system are described. The Monte Carlo tools used to simulate jet quenching are discussed.

  13. Correlated radiative double electron capture (RDEC) in collisions of bare oxygen ions with carbon targets

    Science.gov (United States)

    Simon, A.; Tanis, J. A.; ElKafrawy, T.; Warczak, A.

    2009-11-01

    Multielectron capture processes observed in low energy collisions of bare ions give insight into electron-electron correlations in strong fields. The main intention of this experiment is to observe radiative double electron capture (RDEC) in collisions of bare oxygen ions at energies of a few MeV/u with carbon targets. Measured results are to be compared with recent theoretical calculations.

  14. Treatment of Ion-Atom Collisions Using a Partial-Wave Expansion of the Projectile Wavefunction

    Science.gov (United States)

    Wong, T. G.; Foster, M.; Colgan, J.; Madison, D. H.

    2009-01-01

    We present calculations of ion-atom collisions using a partial-wave expansion of the projectile wavefunction. Most calculations of ion-atom collisions have typically used classical or plane-wave approximations for the projectile wavefunction, since partial-wave expansions are expected to require prohibitively large numbers of terms to converge…

  15. Coincident Auger electron and recoil ion momentum spectroscopy for low-energy ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, G. E-mail: glaurent@ganil.fr; Tarisien, M.; Flechard, X.; Jardin, P.; Guillaume, L.; Sobocinski, P.; Adoui, L.; Bordenave-Montesquieu, A.; Bordenave-Montesquieu, D.; Chesnel, J.-Y.; Fremont, F.; Hennecart, D.; Lienard, E.; Maunoury, L.; Moretto-Capelle, P.; Cassimi, A

    2003-05-01

    The recoil ion momentum spectroscopy (RIMS) method combined with the detection of Auger electrons has been used successfully to analyse double electron capture following O{sup 6+} + He collisions at low impact velocities. Although RIMS and Auger spectroscopies are known to be efficient tools to obtain details on the primary processes occurring during the collision, the conjunction of both techniques provides new insights on the electron capture process. In the present experiment, triple coincidence detection of the scattered projectile, the target recoil ion and the Auger electron allows for a precise identification of the doubly excited states O{sup 4+} (1s{sup 2}nln{sup '}l{sup '}) populated after double electron-capture events.

  16. Azimuthal Distributions of K+ Mesons in Heavy-Ion Collisions

    International Nuclear Information System (INIS)

    Srisawad, P.; Zheng, Y.M.; Katsungnoen, O.; Limphirat, A.; Yan, Y.

    2013-01-01

    Strange mesons are considered to be sensitive to in-medium modifications. Theory predicts a repulsive K + N potential and an attractive K − N potential in dense matter. A repulsive K + N potential would repel the K + mesons from the bulk of the nucleons and therefore cause a preferred out-of-plane emission of K + mesons at midrapidity and a directed flow opposite to the nucleons at target and projectile rapidity. One of observables to probe in-medium effects is the azimuthal emission pattern of K + mesons in heavy ion collisions. KaoS collaboration has measured the azimuthal distributions of K + mesons in Au + Au reactions at 1.5 A GeV and Ni + Ni reactions at 1.93 A GeV. Data show that K + mesons exhibit a pronounced enhancement at ϕ=90°, i.e. perpendicular to the reaction plane. The data have also been fitted using the first two components of a Fourier series to get the directed flow v 1 and elliptic flow v 2 . We used the quantum molecular dynamics model based on the covariant kaon dynamics to simulate the Au + Au collisions at 1.5 A GeV and the Ni + Ni collisions at 1.93 A GeV, to analyze the azimuthal distributions of K + mesons, and to calculate v 1 and v 2 of K + mesons. Calculated results with a repulsive in-medium K + N potential can reasonably describe the features of KaoS data. This indicates that the azimuthal distribution is one of sensitive probes to extract information on in-medium properties at high densities. (author)

  17. Subthreshold Production of Neutral Pions in Heavy Ion Collisions

    CERN Multimedia

    2002-01-01

    The pion production below the threshold at 290 MeV/u (corresponding to the minimum beam velocity at which pions can be produced in nucleon-nucleon collisions) is sensitive to coherent effects in the momentum distribution of the nucleons in the internuclear collision region. Such collective or coherent effects would manifest themselves in an enhancement of the observed cross section with respect to a prediction on the basis of model momentum distributions, e.g. from the Fermi gas model. \\\\ \\\\ With neutral pions such experiments can be extended to rather low energies and rather small cross sections (in the sub-@mb range) due to the fact that the @p|0's leave the composite nuclear system undisturbed by the Coulomb forces and that their decay $\\gamma$ rays can be detected with high efficiency also at very low pion momentum. In our experiments using |1|2C~ions of 60, 74 and 84~MeV/u and |1|80 of 84~MeV/u we were able to clearly sep from background from different sources. The large efficiency of the annular lead gl...

  18. Heavy Ion Collisions at the dawn of the LHC era

    CERN Document Server

    Takahashi, J.

    2013-06-27

    This is a proceeding of the CERN Latin American School of High-Energy physics that took place in the beautiful city of Natal, northern Brazil, in March 2011. In this paper I present a review of the main topics associated with the study of Heavy Ion Collisions, intended for students starting or interested in the field. It is impossible to summarize in a few pages the large amount of information that is available today, after a decade of operations of the RHIC accelerator and the beginning of the LHC operations. Thus, I had to choose some of the results and theories in order to present the main ideas and goals. All results presented here are from publicly available references, but some of the discussions and opinions are my personal view, where I have made that clear in the text.

  19. Neutron removal in peripheral relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Aumann, T.

    1994-09-01

    We investigate the relativistic Coulomb fragmentation of 197 Au by heavy ions, leading to one-, two- and three-neutron removal. To resolve the ambiguity connected with the choice of a specific minimum impact parameter in a semiclassical calculation, a microscopic approach is developed based on nucleon-nucleon collisions ('soft-spheres' model). This approach is compared with experimental data for 197 Au at 1 GeV/nucleon and with a calculation using the 'sharp-cutoff' approximation. We find that the harmonic-oscillator model predicting a Poisson distribution of the excitation probabilities of multiphonon states gives a good agreement with one-neutron removal cross sections but is unable to reach an equally good agreement with three-neutron removal cross sections. (orig.)

  20. Heavy ion collision evolution modeling with ECHO-QGP

    Science.gov (United States)

    Rolando, V.; Inghirami, G.; Beraudo, A.; Del Zanna, L.; Becattini, F.; Chandra, V.; De Pace, A.; Nardi, M.

    2014-11-01

    We present a numerical code modeling the evolution of the medium formed in relativistic heavy ion collisions, ECHO-QGP. The code solves relativistic hydrodynamics in (3 + 1)D, with dissipative terms included within the framework of Israel-Stewart theory; it can work both in Minkowskian and in Bjorken coordinates. Initial conditions are provided through an implementation of the Glauber model (both Optical and Monte Carlo), while freezeout and particle generation are based on the Cooper-Frye prescription. The code is validated against several test problems and shows remarkable stability and accuracy with the combination of a conservative (shock-capturing) approach and the high-order methods employed. In particular it beautifully agrees with the semi-analytic solution known as Gubser flow, both in the ideal and in the viscous Israel-Stewart case, up to very large times and without any ad hoc tuning of the algorithm.

  1. Transverse Flow of Gluon Fields in Heavy Ion Collision

    Science.gov (United States)

    Chen, Guangyao; Fries, Rainer J.

    2014-09-01

    We describe the dynamics of initial gluon fields in heavy ion collision using a formal recursive solution of the Yang Mills equations and solving for the energy momentum tensor analytically in a boost-invariant setup. We generalize the original McLerran-Venugopalan (MV) model in order to allow for realistic nuclear profiles. This leads to a transverse flow of gluon fields. This flow pattern is inherited by the quark gluon plasma fluid after thermalization. Its most interesting aspect is a rapidity-odd flow component. We show that this rapidity-odd flow does not break boost invariance and that it emerges naturally from the Yang Mills equations. It leads to directed flow of particles and introduces angular momentum to the system.

  2. Processes of hypernuclei formation in relativistic ion collisions

    Directory of Open Access Journals (Sweden)

    Botvina Alexander

    2018-01-01

    Full Text Available The study of hypernuclei in relativistic ion collisions open new opportunities for nuclear and particle physics. The main processes leading to the production of hypernuclei in these reactions are the disintegration of large excited hyper-residues (target- and projectile-like, and the coalescence of hyperons with other baryons into light clusters. We use the transport, coalescence and statistical models to describe the whole reaction, and demonstrate the effectiveness of this approach: These reactions lead to the abundant production of multi-strange nuclei and new hypernuclear states. A broad distribution of predicted hypernuclei in masses and isospin allows for investigating properties of exotic hypernuclei, as well as the hypermatter both at high and low temperatures. There is a saturation of the hypernuclei production at high energies, therefore, the optimal way to pursue this experimental research is to use the accelerator facilities of intermediate energies, like FAIR (Darmstadt and NICA (Dubna.

  3. Interferometry of hard photons in heavy-ion collisions

    International Nuclear Information System (INIS)

    Ostendorf, R.W.

    1993-10-01

    Heavy ion collisions offer the unique opportunity to study interference effects between independent hard photons (energies above 25 MeV). The theoretical basis of interference is presented in the framework of classical as well as quantum theory. Experiments use the photon spectrometer TAPS, a modular array of BaF 2 crystals covering 30% of the solid angle. The properties of the spectrometer and the data analysis techniques are described for the experiment 129 Xe + 197 Au at 44 MeV/u, the very first dedicated to the study of photon correlation function. Data are interpreted using GEANT3 simulations to analyse the effect of the method as well as the response function of the photon spectrometer. A second experiment, 86 Kr + 58 Ni at 60 MeV/u is described briefly, where for the first time the existence of an interference effect between hard photons is observed. 52 figs., 76 refs

  4. Modelling early stages of relativistic heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    Ruggieri M.

    2016-01-01

    Full Text Available In this study we model early time dynamics of relativistic heavy ion collisions by an initial color-electric field which then decays to a plasma by the Schwinger mechanism. The dynamics of the many particles system produced by the decay is described by relativistic kinetic theory, taking into account the backreaction on the color field by solving self-consistently the kinetic and the field equations. Our main results concern isotropization and thermalization for a 1+1D expanding geometry. In case of small η/s (η/s ≲ 0.3 we find τisotropization ≈ 0.8 fm/c and τthermalization ≈ 1 fm/c in agreement with the common lore of hydrodynamics.

  5. Theory of ion-atom collisions at high energy, I

    International Nuclear Information System (INIS)

    Watanabe, T.; Hino, K.

    1985-01-01

    Electron capture process by an ion from a neutral atom is one of the fundamental problems in the theory of atomic collision physics. Here a brief review is given mainly on the processes of non-radiative and radiative electron capture (charge transfer and REC). The main mechanism which govern the charge transfer process is introduced and the characteristic feature which is predicted by the theory is explained. As for the radiative electron capture process, after introducting the present theories, the full-quantum mechanical theoretical treatment is introduced. The theory leads a result which includes some inconsistency with formulae obtained by guage transformation. The relativistic quantum mechanical treatment is being tried in order to remove this inconsistency. The some results including mass and velocity dependence are reported and discussed. (author)

  6. From many body wee partons dynamics to perfect fluid: a standard model for heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Venugopalan, R.

    2010-07-22

    We discuss a standard model of heavy ion collisions that has emerged both from experimental results of the RHIC program and associated theoretical developments. We comment briefly on the impact of early results of the LHC program on this picture. We consider how this standard model of heavy ion collisions could be solidified or falsified in future experiments at RHIC, the LHC and a future Electro-Ion Collider.

  7. The production of Higgs bosons in high-energetic heavy-ion collisions

    International Nuclear Information System (INIS)

    Vidovic, M.

    1991-09-01

    The aim of this diploma thesis was to produce the Higgs boson in high-energetic, peripheral heavy-ion collisions by purely electromagnetic processes. In order to take only peripheral collisions into consideration and to avoid the strong hadronic background of central collisions the equivalent-photon method for the case of the Higgs boson was extended concerning an impact-parameter study. By this it was possible to exclude the contribution of central collisions by cut in the impact parameter at b=2R, in order to determine thus the production rate for purely peripheral collisions. (orig./HSI) [de

  8. Search for nuclei in heavy ion collisions at ultrarelativistic energies

    CERN Multimedia

    2002-01-01

    We would like to know if nuclei are still present after a collision of two heavy ions at ultrarelativistic energies. If one can detect some of them at large angle $(>10^{\\circ}-15^{\\circ})$ they very likely come from a multifragmentation of the excited target spectators. Such a multifragmentation in several nuclei has been in proton induced reactions at Fermilab and it was interpreted as a gas-liquid phase transition in nuclei matter near the critical point. With heavy ions the energy deposited in the target spectators will be much higher than in the case of protons and a different mechanism should be involved if nuclei are still observed. \\\\ \\\\ We propose to detect nuclei using 1-2 silicon telescopes and a 1-2mg/cm$^{2}$ Au target bombarded by an $^{16}$O or $^{32}$S beam at 226 GeV/u. The set-up will be installed in a small cube located just before the NA38 experiment and should not perturb it.\\\\ \\\\ Data from $^{16}$O incident on Au have been taken last year. The experiment is presently taking data with $^{...

  9. Light heavy - ion dissipative collisions at low energy

    International Nuclear Information System (INIS)

    Pop, A.; Andronic, A.; Berceanu, I.; Duma, M.; Moisa, D.; Petrovici, M.; Simion, V.; Imme, G.; Lanzano, G.; Pagano, A.; Raciti, G.; Coniglione, R.; Zoppo, A. Del; Piatelli, P.; Sapienza, P.; Colonna, N.; Pantaleo, A.; D'Erasmo, G.

    2003-01-01

    The collisions of light heavy ions were less studied as compared to the large amount of information on dissipative processes collected for heavy systems. For moderate energy damping both experimental data and theoretical models were concentrated on optimum Q value systematics. The energy domain of complete damping was studied from the challenging point of view of the competition between the deep inelastic orbiting mechanism and the fusion-fission one. Dissipative processes have been investigated experimentally in several light heavy-ion systems, using a complex detector which has as main components two position sensitive ionization chamber. The investigated systems were: 19 F(111.4, 125, 136.9 MeV) + 27 Al, 19 F(111.4, 136.9 MeV) + 12 C and 27 Al(140.14 MeV) + 12 C, 27 Al. Experimental evidence and comparison with theoretical calculations suggesting a mechanism similar to deep inelastic processes in heavy and medium systems, even in the case of completely damped events, will be presented in this work. (authors)

  10. Probing the nuclear symmetry energy with heavy ion collisions

    Science.gov (United States)

    Coupland, Daniel David Schechtman

    There are two distinct components involved in using heavy ion collisions to constrain the density dependence of the symmetry energy. On one hand, observables sensitive to the symmetry energy must be identified and measured with enough precision to provide meaningful constraints. On the other hand, nuclear reaction simulations are used to predict those observables for different possible forms of the symmetry energy. Examination of both components and the interface between them is important to improve the constraints. This thesis contributes to both the experimental and theoretical parts of this endeavor. First, we examine the uncertainties in the simulation of the isospin diffusion observable by varying the input physics within the pBUU transport code. In addition to the symmetry energy, several other uncertain parts of the calculation affect isospin diffusion, most notably the in-medium nucleon-nucleon cross sections and light cluster production. There is also a difference in the calculated isospin transport ratios depending on whether they are computed using the isospin asymmetry of the heavy residue or of all forward-moving fragments. We suggest that measurements comparing these two quantities would help place constraints on the input physics, including the density dependence of the symmetry energy. Second, we present a measurement of the neutron and proton kinetic energy spectra emitted from central collisions of 124Sn + 124Sn and 112Sn + 112Sn at beam energies of 50 MeV per nucleon and 120 MeV per nucleon. Previous transport simulations indicate that ratios of these spectra are sensitive to the density dependence of the symmetry energy and to the isovector momentum dependence of the mean field. Protons were detected in the Large Area Silicon Strip Array (LASSA) and neutrons were detected in the MSU Neutron Walls. The multiplicity of charged particles detected in the MSU Miniball was used to determine the impact parameter of the collisions. Several thin

  11. Collective phenomena in relativistic heavy-ion collisions

    Science.gov (United States)

    Wang, Shan

    1998-12-01

    Collective motion in the final state of relativistic nucleus-nucleus collisions, produced by the release of compressional energy built-up during the stage of maximum density, is widely accepted as a good observable to test models and a useful tool to probe the nuclear equation of state. This dissertation presents an experimental study of nuclear collisions at the Bevalac accelerator at Lawrence Berkeley National Laboratory, with special emphasis on collective phenomena. The main detector used is a time projection chamber with more than two million pixels. Using high statistics measurements of all charged final- state fragments in Au + Au reactions at 0.25, 0.4, 0.6, 0.8, 1.0, and 1.15A GeV, we present a new method to unify the description of light fragment spectra and the three main categories of collective motion: sideward flow, squeeze-out, and transverse expansion. In this alternative representation, the speed of collective expansion is shown to be slowest in the plane of the reaction, and is modulated sinusoidally according to fragment azimuth relative to this plane. This simple yet complete characterization of squeeze-out leads to its interpretation as an in-plane retardation of collective expansion. We test momentum space power law behavior by studying the momentum-space densities of fragments up to 4He. We conclude that the simple momentum-space power law consistently describes light participant fragment production at p⊥/A/ge0.2 GeV/c over a remarkably wide range of transverse momentum, azimuth relative to the reaction plane, rapidity, multiplicity and beam energy in intermediate-energy heavy-ion collisions and in particular, the increase in sideward flow with fragment mass is well described by a momentum- space power law under these conditions. This behavior is consistent with composite fragment formation through a statistical coalescence mechanism in momentum space. Our conclusion supports the use of models without composite formation to interpret flow

  12. Modeling and Analysis of Ultrarelativistic Heavy Ion Collisions

    Science.gov (United States)

    McCormack, William; Pratt, Scott

    2014-09-01

    High-energy collisions of heavy ions, such as gold, copper, or uranium serve as an important means of studying quantum chromodynamic matter. When relativistic nuclei collide, a hot, energetic fireball of dissociated partonic matter is created; this super-hadronic matter is believed to be the quark gluon plasma (QGP), which is theorized to have comprised the universe immediately following the big bang. As the fireball expands and cools, it reaches freeze-out temperatures, and quarks hadronize into baryons and mesons. To characterize this super-hadronic matter, one can use balance functions, a means of studying correlations due to local charge conservation. In particular, the simple model used in this research assumed two waves of localized charge-anticharge production, with an abrupt transition from the QGP stage to hadronization. Balance functions were constructed as the sum of these two charge production components, and four parameters were manipulated to match the model's output with experimental data taken from the STAR Collaboration at RHIC. Results show that the chemical composition of the super-hadronic matter are consistent with that of a thermally equilibrated QGP. High-energy collisions of heavy ions, such as gold, copper, or uranium serve as an important means of studying quantum chromodynamic matter. When relativistic nuclei collide, a hot, energetic fireball of dissociated partonic matter is created; this super-hadronic matter is believed to be the quark gluon plasma (QGP), which is theorized to have comprised the universe immediately following the big bang. As the fireball expands and cools, it reaches freeze-out temperatures, and quarks hadronize into baryons and mesons. To characterize this super-hadronic matter, one can use balance functions, a means of studying correlations due to local charge conservation. In particular, the simple model used in this research assumed two waves of localized charge-anticharge production, with an abrupt transition

  13. An integrated Boltzmann+hydrodynamics approach to heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Hannah

    2009-04-22

    In this thesis the first fully integrated Boltzmann+hydrodynamics approach to relativistic heavy ion reactions has been developed. After a short introduction that motivates the study of heavy ion reactions as the tool to get insights about the QCD phase diagram, the most important theoretical approaches to describe the system are reviewed. The hadron-string transport approach that this work is based on is the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) approach. Predictions for the charged particle multiplicities at LHC energies are made. The next step is the development of a new framework to calculate the baryon number density in a transport approach. Time evolutions of the net baryon number and the quark density have been calculated at AGS, SPS and RHIC energies. Studies of phase diagram trajectories using hydrodynamics are performed. The hybrid approach that has been developed as the main part of this thesis is based on the UrQMD transport approach with an intermediate hydrodynamical evolution for the hot and dense stage of the collision. The full (3+1) dimensional ideal relativistic one fluid dynamics evolution is solved using the SHASTA algorithm. Three different equations of state have been used, namely a hadron gas equation of state without a QGP phase transition, a chiral EoS and a bag model EoS including a strong first order phase transition. For the freeze-out transition from hydrodynamics to the cascade calculation two different set-ups are employed. The parameter dependences of the model are investigated and the time evolution of different quantities is explored. The hybrid model calculation is able to reproduce the experimentally measured integrated as well as transverse momentum dependent v{sub 2} values for charged particles. The multiplicity and mean transverse mass excitation function is calculated for pions, protons and kaons in the energy range from E{sub lab}=2-160 A GeV. The HBT correlation of the negatively charged pion source

  14. Charged particle multiplicity and correlations in heavy ion collisions in the ATLAS experiment

    CERN Document Server

    "Zabinski, B; The ATLAS collaboration

    2013-01-01

    Since the start of LHC the ATLAS experiment has collected data from pp, PbPb and recently pPb collisions. In this talk two topics from the heavy ion programme are presented. The first of them is the multiplicity of charged particles in PbPb collisions studied as a function centrality. In such collisions very high pseudorapidity particle density is obtained, reaching 1738 $pm$ 76 at $eta sim 0$. For the pPb collisions the latest analysis of two-particle correlations is presented. The "ridge" observed in pp events with large multiplicities is present also in central pPb collisions selected by large $Sigma E_{T}$ at the Pb fragmentation side. In the azimuthal correlation for $2 < Deltaeta < 5$ two components can be extracted. Assuming that in the peripheral collisions only the correlation due to momentum conservation effects are present, in the central collisions additional quadruple modulation component can be identified.

  15. Heavy flavours in ultra-relativistic heavy ions collisions; Les saveurs lourdes dans les collisions d'ions lourds ultra-relativistes

    Energy Technology Data Exchange (ETDEWEB)

    Rosnet, Ph

    2008-01-15

    The ultra-relativistic collisions of heavy ions are the today's only means to tackle in laboratory conditions the phase diagram in quantum chromodynamics and the strong interaction. The most recent theoretical studies predict a phase transition between the cold nuclear matter (a hadronic gas) and a plasma of quarks and gluons. Heavy flavour can characterize the nuclear matter produced in a heavy ion collision as well as its spatial-temporal evolution. Their study can be made through their decay into muons. The first part of this work presents the issue of ultra-relativistic heavy ion collisions and the role of heavy flavours. In the second part the author reviews the results of experiments performed at RHIC and particularly presents the analysis of the mass spectrum of dimuons in the Phenix experiment. The third part describes the muon trigger system of the Alice experiment at CERN and the expected performances for the study of di-muons.

  16. The initial stages of heavy-ion collisions in the colour glass ...

    Indian Academy of Sciences (India)

    Heavy-ion collisions at ultrarelativistic energies are used to study the properties of nuclear matter in extreme conditions of temperature and density in the laboratory, where it is expected to undergo a transition to a deconfined state called the quark-gluon plasma [1]. In such a collision, one can distinguish several stages, ...

  17. Baryon production and the centrality dependence of limiting fragmentation in heavy ion collision

    International Nuclear Information System (INIS)

    Mondal, M.M.; Chattopadhyay, S.

    2006-01-01

    In experiments with the relativistic heavy ion collisions the primary goals is to study the particle distribution in pseudorapidity variable. From the study of the distribution information of the collision mechanism such as the study of hypothesis of limiting fragmentation can be made

  18. HE2+-HE COLLISIONS - ONE-ELECTRON CAPTURE AND TARGET-ION EXCITATION

    NARCIS (Netherlands)

    FOLKERTS, HO; BLIEK, FW; MENG, L; OLSON, RE; MORGENSTERN, R; VONHELLERMANN, M; SUMMERS, HP; HOEKSTRA, R

    1994-01-01

    By means of photon emission spectroscopy we have studied state selective one-electron capture and target-ion excitation in collisions of He-2+ with He. The collision energy has been varied from 1 to 75 keV amu-1 Four-body classical trajectory Monte Carlo calculations have been performed in the

  19. Ekpyrosis and inflationary dynamics in heavy ion collisions: the role of quantum fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Dusling, K.; Venugopalan, R.; Gelis, F.

    2011-05-23

    We summarize recent significant progress in the development of a first-principles formalism to describe the formation and evolution of matter in very high energy heavy ion collisions. The key role of quantum fluctuations both before and after a collision is emphasized. Systematic computations are now feasible to address early time isotropization, flow, parton energy loss and the Chiral Magnetic Effect.

  20. On the quantum mechanics of deep inelastic collisions between heavy ions

    International Nuclear Information System (INIS)

    Toledo Piza, A.F.R. de

    1981-06-01

    An overview of the quantum-mechanical foundations of the dynamical behaviour of deep inelastic collisions between heavy ions is given. The use of time dependent Hartree-Fock method is stressed. (L.C.) [pt

  1. Two views on the Bjorken scenario for ultra-relativistic heavy-ion collisions

    CERN Multimedia

    Maire, Antonin

    2011-01-01

    The sketch describes the Bjorken scenario foreseen for the collision of ultra-relativistic heavy-ions, leading to the creation of strongly-interacting hot and dense deconfined matter, the so-called Quark-Gluon Plasma (QGP).

  2. Heavy Flavor Production in Heavy Ion Collisions at CMS

    CERN Document Server

    Sun, Jian

    2016-01-01

    Studies of Heavy flavor production are of great interest in heavy ion collisions. In the produced medium, the binding potential between a quark and antiquark in quarkonium is screened by surrounding light quarks and antiquarks. Thus, the various quarkonium states are expected to be melt at different temperatures depending on their binding energies, which allows us to characterize the QCD phase transition. In addition, open heavy flavor production are relevant for flavor-dependence of the in-medium parton energy loss. In QCD, gluons are expected to lose more energy compared to quarks when passing through the QGP due to the larger color charge. Compared to light quarks, heavy quarks are expected to lose less radiative energy because gluon radiation is suppressed at angles smaller than the ratio of the quark mass to its energy. This dead cone effect (and its disappearance at high transverse momentum) can be studied using open heavy flavor mesons and heavy flavor tagged jets. With CMS detector, quarkonia, open he...

  3. Two-pion correlations in heavy ion collisions

    International Nuclear Information System (INIS)

    Zajc, W.A.

    1982-08-01

    An application of intensity interferometry to relativistic heavy ion collisions is reported. Specifically, the correlation between two like-charged pions is used to study the reactions Ar+KCl→2π/sup +-/+X and Ne+NaF→2π - +X. Source sizes are obtained that are consistent with a simple geometric interpretation. Lifetimes are less well determined but are indicative of a faster pion production process than predicted by Monte Carlo cascade calculations. There appears to be a substantial coherent component of the pion source, although measurement is complicated by the presence of final state interactions. Additionally, the generation of spectra of uncorrelated events is discussed. In particular, the influence of the correlation function on the background spectrum is analyzed, and a prescription for removal of this influence is given. A formulation to describe the statistical errors in the background is also presented. Finally, drawing from the available literature, a self-contained introduction to Bose-Einstein correlations and the Hanbury-Brown - Twiss effect is provided, with an emphasis on points of contact between classical and quantum mechanical descriptions

  4. INFN what next ultra-relativistic heavy-ion collisions

    CERN Document Server

    Dainese, A.; Usai, G.; Antonioli, P.; Arnaldi, R.; Beraudo, A.; Bruna, E.; Bruno, G.E.; Bufalino, S.; Di Nezza, P.; Lombardo, M.P.; Nania, R.; Noferini, F.; Oppedisano, C.; Piano, S.; Prino, F.; Rossi, A.; Agnello, M.; Alberico, W.M.; Alessandro, B.; Alici, A.; Andronico, G.; Antinori, F.; Arcelli, S.; Badala, A.; Barbano, A.M.; Barbera, R.; Barile, F.; Basile, M.; Becattini, F.; Bedda, C.; Bellini, F.; Beole, S.; Bianchi, L.; Bianchin, C.; Bonati, C.; Bossu, F.; Botta, E.; Caffarri, D.; Camerini, P.; Carnesecchi, F.; Casula, E.; Cerello, P.; Cicalo, C.; Cifarelli, M.L.; Cindolo, F.; Colamaria, F.; Colella, D.; Colocci, M.; Corrales Morales, Y.; Cortese, P.; De Caro, A.; De Cataldo, G.; De Falco, A.; De Gruttola, D.; D'Elia, M.; De Marco, N.; De Pasquale, S.; Di Bari, D.; Elia, D.; Fantoni, A.; Feliciello, A.; Ferretti, A.; Festanti, A.; Fionda, F.; Fiorenza, G.; Fragiacomo, E.; Fronze, G.G.; Girard, M. Fusco; Gagliardi, M.; Gallio, M.; Garg, K.; Giubellino, P.; Greco, V.; Grossi, E.; Guerzoni, B.; Hatzifotiadou, D.; Incani, E.; Innocenti, G.M.; Jacazio, N.; Das, S. Kumar; La Rocca, P.; Lea, R.; Leardini, L.; Leoncino, M.; Lunardon, M.; Luparello, G.; Mantovani Sarti, V.; Manzari, V.; Marchisone, M.; Margagliotti, G.V.; Masera, M.; Masoni, A.; Mastroserio, A.; Mazzilli, M.; Mazzoni, M.A.; Meninno, E.; Mesiti, M.; Milano, L.; Moretto, S.; Muccifora, V.; Nappi, E.; Nardi, M.; Nicassio, M.; Pagano, P.; Pappalardo, G.S.; Pastore, C.; Paul, B.; Petta, C.; Pinazza, O.; Plumari, S.; Preghenella, R.; Puccio, M.; Puddu, G.; Ramello, L.; Ratti, C.; Ravasenga, I.; Riggi, F.; Ronchetti, F.; Rucci, A.; Ruggieri, M.; Rui, R.; Sakai, S.; Scapparone, E.; Scardina, F.; Scarlassara, F.; Scioli, G.; Siddhanta, S.; Sitta, M.; Soramel, F.; Suljic, M.; Terrevoli, C.; Trogolo, S.; Trombetta, G.; Turrisi, R.; Vercellin, E.; Vino, G.; Virgili, T.; Volpe, G.; Williams, M.C.S.; Zampolli, C.

    2016-01-01

    This document was prepared by the community that is active in Italy, within INFN (Istituto Nazionale di Fisica Nucleare), in the field of ultra-relativistic heavy-ion collisions. The experimental study of the phase diagram of strongly-interacting matter and of the Quark-Gluon Plasma (QGP) deconfined state will proceed, in the next 10-15 years, along two directions: the high-energy regime at RHIC and at the LHC, and the low-energy regime at FAIR, NICA, SPS and RHIC. The Italian community is strongly involved in the present and future programme of the ALICE experiment, the upgrade of which will open, in the 2020s, a new phase of high-precision characterisation of the QGP properties at the LHC. As a complement of this main activity, there is a growing interest in a possible future experiment at the SPS, which would target the search for the onset of deconfinement using dimuon measurements. On a longer timescale, the community looks with interest at the ongoing studies and discussions on a possible fixed-target p...

  5. Partial correlation analysis method in ultrarelativistic heavy-ion collisions

    Science.gov (United States)

    Olszewski, Adam; Broniowski, Wojciech

    2017-11-01

    We argue that statistical data analysis of two-particle longitudinal correlations in ultrarelativistic heavy-ion collisions may be efficiently carried out with the technique of partial covariance. In this method, the spurious event-by-event fluctuations due to imprecise centrality determination are eliminated via projecting out the component of the covariance influenced by the centrality fluctuations. We bring up the relationship of the partial covariance to the conditional covariance. Importantly, in the superposition approach, where hadrons are produced independently from a collection of sources, the framework allows us to impose centrality constraints on the number of sources rather than hadrons, that way unfolding of the trivial fluctuations from statistical hadronization and focusing better on the initial-state physics. We show, using simulated data from hydrodynamics followed with statistical hadronization, that the technique is practical and very simple to use, giving insight into the correlations generated in the initial stage. We also discuss the issues related to separation of the short- and long-range components of the correlation functions and show that in our example the short-range component from the resonance decays is largely reduced by considering pions of the same sign. We demonstrate the method explicitly on the cases where centrality is determined with a single central control bin or with two peripheral control bins.

  6. Two-pion correlations in heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Zajc, W.A.

    1982-08-01

    An application of intensity interferometry to relativistic heavy ion collisions is reported. Specifically, the correlation between two like-charged pions is used to study the reactions Ar+KCl..-->..2..pi../sup +-/+X and Ne+NaF..-->..2..pi../sup -/+X. Source sizes are obtained that are consistent with a simple geometric interpretation. Lifetimes are less well determined but are indicative of a faster pion production process than predicted by Monte Carlo cascade calculations. There appears to be a substantial coherent component of the pion source, although measurement is complicated by the presence of final state interactions. Additionally, the generation of spectra of uncorrelated events is discussed. In particular, the influence of the correlation function on the background spectrum is analyzed, and a prescription for removal of this influence is given. A formulation to describe the statistical errors in the background is also presented. Finally, drawing from the available literature, a self-contained introduction to Bose-Einstein correlations and the Hanbury-Brown - Twiss effect is provided, with an emphasis on points of contact between classical and quantum mechanical descriptions.

  7. The study of hadron dynamics in relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Venema, L.B.

    1994-01-01

    In this thesis, pion emission patterns were studied in two reaction systems Ar + Ca and Au + Au at 1 GeV/u, with the aim to improve the understanding of the pion production in relativistic heavy ion collisions. The study of the high energy tail of the π 0 -momentum spectrum was regarded as promising because of its sensitivity to compression since it did not appear in small reaction systems. Experiments were performed with TAPS together with the Forward Wall of the FoPi-collaboration at GSI. The combined measurement of charged particle multiplicities in the Forward Wall and the particles entering TAPS enabled an exclusive study of the pion production. TAPS was tested in separate experiments and its capabilities were demonstrated by measuring different reaction products, like photons, charged particles and neutrons. The data analysis involved new methods to treat the background contamination below the invariant mass peak of the π 0 -meson due to the geometry of the detector and to perform particle identification in a high particle multiplicity environment. (orig.)

  8. Thermal electromagnetic radiation in heavy-ion collisions

    Science.gov (United States)

    Rapp, R.; van Hees, H.

    2016-08-01

    We review the potential of precise measurements of electromagnetic probes in relativistic heavy-ion collisions for the theoretical understanding of strongly interacting matter. The penetrating nature of photons and dileptons implies that they can carry undistorted information about the hot and dense regions of the fireballs formed in these reactions and thus provide a unique opportunity to measure the electromagnetic spectral function of QCD matter as a function of both invariant mass and momentum. In particular we report on recent progress on how the medium modifications of the (dominant) isovector part of the vector current correlator ( ρ channel) can shed light on the mechanism of chiral symmetry restoration in the hot and/or dense environment. In addition, thermal dilepton radiation enables novel access to a) the fireball lifetime through the dilepton yield in the low invariant-mass window 0.3 GeV ≤ M ≤ 0.7 GeV, and b) the early temperatures of the fireball through the slope of the invariant-mass spectrum in the intermediate-mass region (1.5 GeV < M < 2.5 GeV). The investigation of the pertinent excitation function suggests that the beam energies provided by the NICA and FAIR projects are in a promising range for a potential discovery of the onset of a first-order phase transition, as signaled by a non-monotonous behavior of both low-mass yields and temperature slopes.

  9. Holography for Heavy Ions Collisions at LHC and NICA

    Science.gov (United States)

    Aref'eva, Irina

    2017-12-01

    This is a contribution for the Proceedings of 5th International Conference on New Frontiers in Physics (ICNFP 2016), held at Crete, 6-14 July 2016. Our goal is to obtain phenomenologically reliable insights for the physics of the quark-gluon plasma (QGP) from the holography. I briefly review how in the holographical setup one can describe the QGP formation in heavy ion collisions and how to get quantitatively the main characteristics of the QGP formation - the total multiplicity and the thermalization time. To fit the experimental form of dependence of total multiplicity on energy, obtained at LHC, we have to deal with a special anisotropic holographic model, related with the Lifshitz-type background. Our conjecture is that this Lifshitz-type background with non-zero chemical potential can be used to describe future data expected from NICA. In particular, we present the results of calculations the holographic confinement/deconfinement phase transition in the (µ, T) (chemical potential, temperature) plane in this anizotropic background and show the dependence of the transition line on the orientation of the quark pair. This dependence leads to a non-sharp character of physical confinement/deconfinement phase in the (µ, T)-plane. We use the bottom-up soft wall approach incorporating quark confinement deforming factor and vector field providing the non-zero chemical potential. In this model we also estimate the holographic photon production.

  10. Role of giant resonance excitation in heavy ion collisions

    International Nuclear Information System (INIS)

    Catara, F.; Chomaz, Ph.

    1987-01-01

    In this paper we discuss several aspects of heavy ion collisions involving collective vibrational modes. In our approach the relative motion is treated in a semiclassical approximation, while the intrinsic degrees of freedom are described microscopically within the RPA. The differences with respect to macroscopic models are analyzed in the appendix. First we present some results on the inelastic scattering cross section and we show that the structures observed experimentally can be explained in terms of multiple excitation of the Giant Quadrupole Resonance. After we calculate an adiabatic polarization potential describing the coupling to the collective vibrational modes and show that it produces a strong enhancement of the subbarrier fusion cross section. This enhancement is found to be enough to reproduce the experimental data for symmetric systems, while for asymmetric reactions the coupling to other degrees of freedom, like transfer, is needed. Finally we report some preliminary results on a dynamical calculation of the real and imaginary parts of the polarization potential. We show that at high incident energies (E/A > 20MeV) the role of the Giant Quadrupole Resonance becomes dominant

  11. Thermal electromagnetic radiation in heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, R. [Texas A and M University, Cyclotron Institute and Department of Physics and Astronomy, College Station, TX (United States); Hees, H. van [Goethe-Universitaet Frankfurt, Institut fuer Theoretische Physik, Frankfurt (Germany); Frankfurt Institute of Advanced Studies (FIAS), Frankfurt (Germany)

    2016-08-15

    We review the potential of precise measurements of electromagnetic probes in relativistic heavy-ion collisions for the theoretical understanding of strongly interacting matter. The penetrating nature of photons and dileptons implies that they can carry undistorted information about the hot and dense regions of the fireballs formed in these reactions and thus provide a unique opportunity to measure the electromagnetic spectral function of QCD matter as a function of both invariant mass and momentum. In particular we report on recent progress on how the medium modifications of the (dominant) isovector part of the vector current correlator (ρ channel) can shed light on the mechanism of chiral symmetry restoration in the hot and/or dense environment. In addition, thermal dilepton radiation enables novel access to (a) the fireball lifetime through the dilepton yield in the low invariant-mass window 0.3 GeV ≤ M ≤ 0.7 GeV, and (b) the early temperatures of the fireball through the slope of the invariant-mass spectrum in the intermediate-mass region (1.5 GeV < M < 2.5 GeV). The investigation of the pertinent excitation function suggests that the beam energies provided by the NICA and FAIR projects are in a promising range for a potential discovery of the onset of a first-order phase transition, as signaled by a non-monotonous behavior of both low-mass yields and temperature slopes. (orig.)

  12. Multiple electromagnetic pair production in ultrarelativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Best, C.

    1992-04-01

    The problem of the unitary violation in the pair production in ultrarelativistic heavy ion collisions was studied by a consideration of the field-theoretical foundations. The quantum electrodynamics in an external field were thereby reduced to a Dirac-sea model, the equivalence of which to the non-radiative QED resulted from the equality of the generating functionals. The latter can both be expressed explicitely by means of the complet set of the solutions of the Dirac equation in an external field. This method is based solely on the path-integral approach, which makes it possible to discriminate clearly between the physically given correlation functions and their generating functional at the one hand and at the other hand between the models constructed to their interpretation. From the model expression for the pair production amplitudes and multiplicities could be calculated, for which only the knowledge of the one-particle S matrix is necessary. For the calculation of the multiplicities different forms of the perturbation theory were discussed. Finally an impact-parameter dependent Weizsaecker-Williams approximation for the calculation of arbitrary two-photon graphs was constructed and applied to the given problem. The results indicate that at small distances very high pair multiplicities are to be expected. Finally a new approach to the pair production in an external field was discussed, which is not based on the canonical field theory, but on the formalism of the Wigner functions. (orig./HSI) [de

  13. Auto transfer to Rydberg states during ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Bachau, H.; Harel, C. (Laboratoire des Collisions Atomiques, Unite Propre de Recherche 260 du CNRS, Universite Bordeaux I, 351 Cours de la Liberation, 33405 Talence (France)); Barat, M.; Roncin, P. (Laboratoire des Collisions Atomiques et Moleculaires, Unite associee 281 du CNRS, Universite de Paris Sud, Batiment 351, 91405 Orsay (France)); Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Benoit-Cattin, P.; Gleizes, A.; Benhenni, M. (IRSAMC, Unite associee 770 du CNRS, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse (France))

    1993-06-05

    Electron capture by slow multiply charged ions colliding on rare-gas targets is known to populate highly excited states of the projectile. On the basis of experimental measurement of energy and angle differential cross-sections we have shown that capture to a resonant doubly excited state may lead to Autoionizing Double Capture (ADC) as well as to True Double Capture (TDC). In this model TDC appears as a two step post-collisional process, the state populated by the collision decays to (or delutes into) a dense adjacent Rydberg series, followed by radiative deexcitation of the inner electron of the (3,n) Rydberg states. We report here new experimental observations in electron spectra measured in [ital N][sup 7+]+[ital He]. Auto transfer to Rydber states has also important consequences on the determination of the lifetime of the autoionizing states, some discrepancies between theoretical width values for low [ital N][sup 5+](4,4) resonant states will be discussed and partially resolved.

  14. Radiative Double Electron Capture in Collisions of O8+ Ions with Carbon

    Science.gov (United States)

    Simon, A.; Warczak, A.; Elkafrawy, T.; Tanis, J. A.

    2010-03-01

    Multielectron capture processes observed in low energy collisions of bare ions with target atoms open insight into electron correlations in electromagnetic fields. Radiative double electron capture (RDEC) provides the simplest tool for investigation of such processes. Here, the experimental observation of the RDEC process in collisions of O8+ ions with thin carbon films is presented and the RDEC cross section value obtained is compared with recent theoretical calculations.

  15. Towards high-density matter with relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Nagamiya, Shoji.

    1990-04-01

    Recent progress in nucleus-nucleus collisions at BNL and CERN suggests a hint that the formation of high-density nuclear matter could be possible with relativistic heavy-ion beams. What is the maximum density that can be achieved by heavy-ion collisions? Are there data which show evidence or hints on the formation of high density matter? Why is the research of high-density interesting? How about the future possibilities on this subject? These points are discussed. (author)

  16. Numerical analysis of energy density and particle density in high energy heavy-ion collisions

    International Nuclear Information System (INIS)

    Fu Yuanyong; Lu Zhongdao

    2004-01-01

    Energy density and particle density in high energy heavy-ion collisions are calculated with infinite series expansion method and Gauss-Laguerre formulas in numerical integration separately, and the results of these two methods are compared, the higher terms and linear terms in series expansion are also compared. The results show that Gauss-Laguerre formulas is a good method in calculations of high energy heavy-ion collisions. (author)

  17. Constraints on the density dependence of the symmetry energy from heavy-ion collisions

    Science.gov (United States)

    Tsang, M. B.; Chajecki, Z.; Coupland, D.; Danielewicz, P.; Famiano, F.; Hodges, R.; Kilburn, M.; Lu, F.; Lynch, W. G.; Winkelbauer, J.; Youngs, M.; Zhang, Y. X.

    2011-04-01

    Constraints on the equation of state (EoS) for symmetric matter (equal neutron and proton numbers) have been extracted from energetic collisions of heavy ions over a range of energies. Collisions of neutron-deficient and neutron-rich heavy ions now provide initial constraints on the EoS of neutron-rich matter at subsaturation densities from isospin diffusions and neutron proton ratios. This article reviews the experimental constraints on the density dependence of symmetry energy at subsaturation density.

  18. X-ray emission in slow highly charged ion-surface collisions

    International Nuclear Information System (INIS)

    Watanabe, H; Abe, T; Fujita, Y; Sun, J; Takahashi, S; Tona, M; Yoshiyasu, N; Nakamura, N; Sakurai, M; Yamada, C; Ohtani, S

    2007-01-01

    X-rays emitted in the collisions of highly charged ions with a surface have been measured to investigate dissipation schemes of their potential energies. While 8.1% of the potential energy was dissipated in the collisions of He-like I ions with a W surface, 29.1% has been dissipated in the case of He-like Bi ions. The x-ray emissions play significant roles in the dissipation of the potential energies in the interaction of highly charged heavy ions with the surface

  19. Magneto optical trap recoil ion momentum spectroscopy: application to ion-atom collisions

    International Nuclear Information System (INIS)

    Blieck, J.

    2008-10-01

    87 Rb atoms have been cooled, trapped and prepared as targets for collision studies with 2 and 5 keV Na + projectiles. The physics studied deals with charge exchange processes. The active electron, which is generally the most peripheral electron of the atomic target, is transferred from the target onto the ionic projectile. The ionized target is called recoil ion. The technique used to study this physics is the MOTRIMS (Magneto Optical Trap Recoil Ion Momentum Spectroscopy) technique, which combines a magneto optical trap and a recoil ion momentum spectrometer. The spectrometer is used for the measurement of the recoil ions momentum, which gives access to all the information of the collision: the Q-value (which is the potential energy difference of the active electron on each particle) and the scattering angle of the projectile. The trap provides extremely cold targets to optimize the measurement of the momentum, and to release the latter from thermal motion. Through cinematically complete experiments, the MOTRIMS technique gives access to better resolutions on momentum measurements. Measurements of differential cross sections in initial and final capture states and in scattering angle have been done. Results obtained for differential cross sections in initial and final states show globally a good agreement with theory and an other experiment. Nevertheless, discrepancies with theory and this other experiment are shown for the measurements of doubly differential cross sections. These discrepancies are not understood yet. The particularity of the experimental setup designed and tested in this work, namely a low background noise, allows a great sensitivity to weak capture channels, and brings a technical and scientific gain compared with previous works. (author)

  20. Dynamic screening and wake effects on electronic excitation in ion-solid and ion-surface collisions

    Energy Technology Data Exchange (ETDEWEB)

    Burgdoerfer, J. (Tennessee Univ., Knoxville, TN (United States). Dept. of Physics Oak Ridge National Lab., TN (United States))

    1991-01-01

    The collective electronic response in a solid effectively alters ionic and atomic potentials giving rise to dynamic screening and to a wake'' of density fluctuations trailing ions as they propagate through the solid. The presence of dynamic screening modifies electronic excitation processes of projectiles in ion-solid collisions as compared to binary ion-atom collisions. We review recent theoretical and experimental studies directed at the search for and identification of signatures of dynamic screening and wake effects. Examples include the formation of excited projectile bound states under channeling conditions, radiative electron capture, the search for wake riding'' electrons in antiproton-solid collisions, and the neutralization of highly charged ions near surfaces. 42 refs., 7 figs.

  1. Operator of pair electron-ion collisions in alternating electromagnetic fields

    International Nuclear Information System (INIS)

    Balakin, A. A.

    2008-01-01

    Collisions of electrons with ions in the presence of an alternating electromagnetic field are considered. Based on the first principles (the Liouville equations for N particles), a general expression for the collisional operator in the approximation of pair collisions at an arbitrary scattering potential, including that depending periodically on time, is derived. The problem of collisions in plasma in the presence of an electromagnetic field can be reduced to this case by introducing drift coordinates. It is shown that the method of test particles can be applied to the problem of particle collisions in an alternating electromagnetic field.

  2. Electroweak bosons in heavy-ion collisions measured with the ATLAS detector

    CERN Document Server

    Perepelitsa, Dennis; The ATLAS collaboration

    2017-01-01

    Electroweak bosons do not interact strongly with the dense and hot medium formed in nuclear collisions, and thus are sensitive to the nuclear modification of parton distribution functions (nPDFs). The ATLAS detector, optimised to search for new physics in proton-proton interactions, is well equipped to measure photons, W and Z bosons in the high occupancy environment produced in heavy-ion collisions. Results from the ATLAS experiment on photons, W, and Z boson yields in lead-lead and proton-lead collisions are presented. These results have particular importance in the context of understanding the collision geometry and nuclear initial state.

  3. The ATLAS TRT performance in proton-proton and ion-ion collisions at the LHC

    CERN Document Server

    Smirnov, S Yu; The ATLAS collaboration

    2011-01-01

    The Transition Radiation Tracker (TRT) is the outermost of the three sub-systems of the ATLAS Inner Detector at the Large Hadron Collider at CERN. It consists of close to 300000 thin-wall drift tubes (straws) providing on average 30 two-dimensional space points with 0.12-0.15 mm resolution for charged particle tracks with |η| < 2 and pT > 0.5 GeV. Along with continuous tracking, it provides particle identification capability through the detection of transition radiation X-ray photons generated by high-velocity particles in the many-polymer fibres or films that fill the spaces between the straws. This report gives the review of the TRT detector commissioning using cosmic muons studies and first operational experience in the proton-proton and ion-ion collisions at the LHC. The emphasis will be given to the TRT performance on the reconstruction and analysis of particle collisions. The first studies of the TRT detector response to the extremely high track density conditions during the November 2010...

  4. Pion correlations in relativistic heavy ion collisions at Heavy Ion Spectrometer Systems (HISS)

    International Nuclear Information System (INIS)

    Christie, W.B. Jr.

    1990-05-01

    This thesis contains the setup, analysis and results of experiment E684H ''Multi-Pion Correlations in Relativistic Heavy Ion Collisions''. The goals of the original proposal were: (1) To initiate the use of the HISS facility in the study of central Relativistic Heavy Ion Collisions (RHIC). (2) To perform a second generation experiment for the detailed study of the pion source in RHIC. The first generation experiments, implied by the second goal above, refer to pion correlation studies which the Riverside group had performed at the LBL streamer chamber. The major advantage offered by moving the pion correlation studies to HISS is that, being an electronic detector system, as opposed to the Streamer Chamber which is a visual detector, one can greatly increase the statistics for a study of this sort. An additional advantage is that once one has written the necessary detector and physics analysis code to do a particular type of study, the study may be extended to investigate the systematics, with much less effort and in a relatively short time. This paper discusses the Physics motivation for this experiment, the experimental setup and detectors used, the pion correlation analysis, the results, and the conclusions possible future directions for pion studies at HISS. If one is not interested in all the details of the experiment, I believe that by reading the sections on intensity interferometry, the section the fitting of the correlation function and the systematic corrections applied, and the results section, one will get a fairly complete synopsis of the experiment

  5. Overview on collision processes of highly charged ions with atoms present status and problems

    International Nuclear Information System (INIS)

    Janev, R.K.

    1983-05-01

    This paper provides a brief discussion on the present status of the collision physics of highly charged ions with atoms. The emphasis is on the main achievements in understanding and describing the most important collision processes, and as charge transfer, ionization and Auger-type processes, and even more on those open problems which, due either to their scientific or practical importance, represent challenges to current research in this field. The paper concentrates on general ideas and problems whose development and solutions have advanced or will advance our basic understanding of the collision dynamics of multiply charged ions with atoms

  6. Collision cross section calculations for polyatomic ions considering rotating diatomic/linear gas molecules

    International Nuclear Information System (INIS)

    Larriba-Andaluz, Carlos; Hogan, Christopher J.

    2014-01-01

    Structural characterization of ions in the gas phase is facilitated by measurement of ion collision cross sections (CCS) using techniques such as ion mobility spectrometry. Further information is gained from CCS measurement when comparison is made between measurements and accurately predicted CCSs for model ion structures and the gas in which measurements are made. While diatomic gases, namely molecular nitrogen and air, are being used in CCS measurement with increasingly prevalency, the majority of studies in which measurements are compared to predictions use models in which gas molecules are spherical or non-rotating, which is not necessarily appropriate for diatomic gases. Here, we adapt a momentum transfer based CCS calculation approach to consider rotating, diatomic gas molecule collisions with polyatomic ions, and compare CCS predictions with a diatomic gas molecule to those made with a spherical gas molecular for model spherical ions, tetra-alkylammonium ions, and multiply charged polyethylene glycol ions. CCS calculations are performed using both specular-elastic and diffuse-inelastic collisions rules, which mimic negligible internal energy exchange and complete thermal accommodation, respectively, between gas molecule and ion. The influence of the long range ion-induced dipole potential on calculations is also examined with both gas molecule models. In large part we find that CCSs calculated with specular-elastic collision rules decrease, while they increase with diffuse-inelastic collision rules when using diatomic gas molecules. Results clearly show the structural model of both the ion and gas molecule, the potential energy field between ion and gas molecule, and finally the modeled degree of kinetic energy exchange between ion and gas molecule internal energy are coupled to one another in CCS calculations, and must be considered carefully to obtain results which agree with measurements

  7. Studies of negative ions by collision-induced decomposition and hydrogen-deuterium exchange techniques.

    Science.gov (United States)

    Hunt, D F; Sethi, S K; Shabanowitz, J

    1980-06-01

    Development of two new techniques for studying the gas phase chemistry of negative ions is reported. Collision induced dissociation (CID) of (M-1)- ions has been accomplished in a newly constructed triple stage quadrupole mass spectrometer. This instrument was assembled by adding two additional Finnigan quadrupole mass filters to a Finnigan Model 3200 CI mass spectrometer. Generation of (M-1)- ions is accomplished by allowing OH- and sample to react under CI conditions in the ion source. The first quadrupole mass filter, Q1, is then employed to selectively pass the (M-1)- ion into a second quadrupole filter containing argon or neon at 10(-3) torr. On collision with the inert gas the (M-1)- ions dissociate into fragments which are then mass analyzed in the third quadrupole filter, CID spectra of (M-1)- ions from twelve carbonyl compounds are presented in this paper. Ion molecule isotope exchange reactions in the CI ion source can be used to count the number of hydrogen atoms in many different chemical environments. Collisions between sample (M-1)- ions and deuterium-labeled reagent gases (ND3, D2O, EtOD) facilitate incorporation of deuterium into the negative ion if the basicities of the sample and reagent anions are similar. Thus it is possible to selectively incorporate deuterium into many organic samples by controlling the exothermicity of the acid base, ion-molecule chemistry.

  8. Measurement of quarkonia production in heavy-ion collisions with the ATLAS detector

    CERN Document Server

    Kremer, Jakub Andrzej; The ATLAS collaboration

    2017-01-01

    The suppression of heavy quarkonia states in heavy-ion collisions is a phenomenon understood as a consequence of QGP formation in the hot, dense system formed in heavy-ion collisions at the LHC. In addition to hot matter effects in heavy-ion collisions, cold nuclear effects may also affect quarkonia production. Therefore, a full assessment requires detailed studies on the effects present in both A-A and p+A collisions. Based on p+Pb data collected in 2013 and pp and Pb+Pb data collected in 2015 at the LHC, the ATLAS experiment has studied prompt and non-prompt J/psi and psi(2S) productions as well as Upsilon production via the di-muon decay final states. The results of the various measurements are discussed

  9. Femtoscopic analysis of baryon correlations in ultra-relativistic heavy-ion collisions registered by ALICE

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00361630

    Heavy-ion collisions at ultra-relativistic energies give a unique possibility to create and to analyse the Quark-Gluon Plasma predicted by the theory of Quantum Chromodynamics. The research on the properties of such state of matter is crucial for understanding the features of the strongly interacting system. Experimental results reveal the collective behaviour of matter created in the heavy-ion collisions at ultra-relativistic energies. The existence of this effect can be verified by the measurement of the transverse mass dependence of the source size extracted using different particle species. Such characteristics can be determined using the analysis technique called femtoscopy. This method is based on the correlations of particles with small relative momenta which originate from the effects of Quantum Statistics as well as the strong and Coulomb Final State Interactions. A recent analysis of the particle production at the highest available collision energies of heavy-ion collisions reveals the puzzling res...

  10. Measurement of quarkonia production in heavy-ion collisions with the ATLAS detector

    CERN Document Server

    Tapia Araya, Sebastian; The ATLAS collaboration

    2017-01-01

    The suppression of heavy quarkonia states in heavy-ion collisions is a phenomenon understood as a consequence of QGP formation in the hot, dense system formed in heavy-ion collisions at the LHC. In addition to hot matter effects in heavy-ion collisions , cold nuclear effects may also affect quarkonia production . Therefore, a full assessment requires detailed studies on the effects present in both A-A and p+A collisions. Based on p+Pb data collected in 2013 and pp and Pb+Pb data collected in 2015 at the LHC, the ATLAS experiment has studied prompt and non-prompt J/psi and psi(2S) productions as well as Upsilon production via the di-muon decay final states. The results are of the various measurements are discussed.

  11. Strangeness and charm production in high energy heavy ion collisions

    International Nuclear Information System (INIS)

    Xu, Nu

    2001-01-01

    We discuss the dynamical effects of strangeness and charm production in high energy nuclear collisions. In order to understand the early stage dynamical evolution, it is necessary to study the transverse momentum distributions of multi-strange hadrons like Ξ and Ω and charm mesons like J/Ψ as a function of collision centrality

  12. Comparison of string models for heavy ion collisions

    International Nuclear Information System (INIS)

    Werner, K.

    1990-01-01

    An important method to explore new domains in physics is to compare new results with extrapolations from known areas. For heavy ion collision this can be done with string models, which extrapolate from light to heavy systems and which also may be used to extrapolate to higher energies. That does not mean that these string models are only background models, one may easily implement new ideas on top of the known aspects, providing much more reliable models than those formed from scratch. All the models to be considered in this paper have in common that they consist of three independent building blocks: (a) geometry, (b) string formation and (c) string fragmentation. The geometry aspect is treated quite similar in all models: nucleons are distributed inside each nucleus according to some standard parameterization of nuclear densities. The nuclei move through each other on a straight line trajectory, with all the nucleon positions being fixed. Whenever a projectile and a target nucleon come close, they interact. Such an interaction results in string formation. In the last step these strings decay into observable hadrons according to some string fragmentation procedure. The three building blocks are independent, so one can combine different methods in an arbitrary manner. Therefore rather than treating the models one after the other, the author discusses the procedures for string formation and string fragmentation as used by the models. He considers string models in a very general sense, so he includes models where the authors never use the word string, but which may be most naturally interpreted as string models and show strong similarities with real string models. Although very important he does not discuss - for time and space reasons - recent developments concerning secondary scattering

  13. MEGHNAD – A multi element detector array for heavy ion collision ...

    Indian Academy of Sciences (India)

    When heavy ion beam available from such machines fall on a target and undergo collision, very rich and often pristine fields of research open up. In order to carry on such activities, we have taken up a project to build a multi element gamma, heavy ion and neutron array of detectors (MEGHNAD) to detect and study the ...

  14. Energy Partitioning in Collisions of Slow Polyatomic Ions with Carbon Surfaces

    Czech Academy of Sciences Publication Activity Database

    Žabka, Ján; Dolejšek, Zdeněk; Roithová, Jana; Grill, V.; Märk, T. D.; Herman, Zdeněk

    2002-01-01

    Roč. 213, 2/3 (2002), s. 145-156 ISSN 1387-3806 R&D Projects: GA ČR GA203/00/0632 Institutional research plan: CEZ:AV0Z4040901 Keywords : ion-surface collisions * polyatomic ions * energy partitioning Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.134, year: 2002

  15. Fast heavy ion collisions with C{sub 60}: Collective excitation

    Energy Technology Data Exchange (ETDEWEB)

    Kadhane, Umesh [Tata Institute of Fundamental Research, Colaba, Mumbai-400005 (India); Kelkar, A.H. [Tata Institute of Fundamental Research, Colaba, Mumbai-400005 (India); Misra, D. [Tata Institute of Fundamental Research, Colaba, Mumbai-400005 (India); Kumar, Ajay [Tata Institute of Fundamental Research, Colaba, Mumbai-400005 (India); Tribedi, L.C. [Tata Institute of Fundamental Research, Colaba, Mumbai-400005 (India)]. E-mail: lokesh@tifr.res.in

    2006-11-15

    Ionization and fragmentation of C{sub 60} in collision with 5 MeV/{mu}m O{sup 6+} ions are studied using recoil ion ToF method. Relative ionization cross sections up to C{sub 60} {sup 4+} are determined. The qualitative trend for different C{sub 60} charge states was compared against simple plasmon excitation model.

  16. Photon and dilepton production in high-energy heavy-ion collisions

    Indian Academy of Sciences (India)

    2015-05-07

    May 7, 2015 ... The recent results on direct photons and dileptons in high-energy heavy-ion collisions, obtained particularly at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) are reviewed. The results are new not only in terms of the probes, but also in terms of the precision. We shall discuss the ...

  17. Influence of the nuclear autocorrelation function on the positron production in heavy-ion collisions

    International Nuclear Information System (INIS)

    Tomoda, T.; Weidenmueller, H.A.

    1983-01-01

    The influence of a nuclear reaction on atomic positron production in heavy-ion collisions is investigated. Using statistical concepts, we describe the nuclear S matrix for a heavy-ion induced reaction as a statistically fluctuating function of energy. The positron production rate is then dependent on the autocorrelation function of this S matrix, and on the ratio of the ''direct'' versus the ''fluctuating'' part of the nuclear cross section. Numerical calculations show that in this way, current experimental results on positron production in heavy-ion collisions can be reproduced in a semiquantitative fashion

  18. High l state population in O7+ produced in ion-solid collisions

    International Nuclear Information System (INIS)

    Kemmler, J.; Bourgdoerfer, J.; Reinhold, C.O.

    1991-01-01

    The high ell-state population of fast ions excited in ion-solid interactions is very different from ell-state populations produced under single collision conditions. A study of the population dynamics of electronic excitation and transport within the framework of a classical transport theory for O 2+ (2 MeV/u) ions traversing carbon foils shows food agreement with experimental results from delayed photon emission spectroscopy. We investigate the dependence of the characteristic exponent for the power-law decay of delayed Lyα and Lyβ radiation on the initial n,ell distribution. From our simulations we find evidence that the very high ell-state populations produced in ion-solid collision are the consequence of a high-ell state diffusion under the influence of multiple inelastic and elastic collisions in the bulk of the solid. 15 refs., 4 figs

  19. Assessment of ion-atom collision data for magnetic fusion plasma edge modelling

    International Nuclear Information System (INIS)

    Phaneuf, R.A.

    1990-01-01

    Cross-section data for ion-atom collision processes which play important roles in the edge plasma of magnetically-confined fusion devices are surveyed and reviewed. The species considered include H, He, Li, Be, C, O, Ne, Al, Si, Ar, Ti, Cr, Fe, Ni, Cu, Mo, W and their ions. The most important ion-atom collision processes occurring in the edge plasma are charge-exchange reactions. Excitation and ionization processes are also considered. The scope is limited to atomic species and to collision velocities corresponding to plasma ion temperatures in the 2-200 eV range. Sources of evaluated or recommended data are presented where possible, and deficiencies in the data base are indicated. 42 refs., 1 fig., 4 tabs

  20. High energy heavy ion collisions from the view point of the 'strong field physics'

    International Nuclear Information System (INIS)

    Itakura, Kazunori

    2012-01-01

    In the high energy heavy ion collisions at the facilities like RHIC and LHC, two strongest fields in the present universe are generated. First of all, a very strong electromagnetic field is generated, though its duration is very short due to the very high speed collisions of nuclei and the large electric charges. On the other hand, the nuclei are described as the high density saturation gluon state just before the moment of the collision and the high density gluon is released by the collision. A very strong color electromagnetic field is generated. The color glass condensate (CGC) is a reasonable picture. In this text, dynamics of the GLASMA (Glass + plasma), the new physics brought about by those 'strong fields', are introduced and are explained how the yet unsolved problems of the heavy ion collisions are going to be investigated on the new view point. The mechanism of the apparitions of the strong electromagnetic field and the strong color electromagnetic field are explained at first. The heavy ion collisions can be described as the process CGC to develop into QGP. As the phenomena under the strong electromagnetic field and the heavy ion collisions, their synchrotron radiations, the photon birefringence, the photon decay, the splitting of photons and the chiral phase transitions under high field are picked up. Concerning the strong color electromagnetic field dynamics and the heavy ion collisions, the plasma flux tube dynamics, the color magnetic flux tube, the color electric flux tube and the coexisting case of the color electric field and magnetic field are presented. (S. Funahashi)

  1. High-Energy Electron-Ion and Photon-Ion Collisions: Status and Challenges

    Science.gov (United States)

    Kallman, Timothy R.

    2010-01-01

    Non-LTE plasmas are ubiquitous in objects studied in the UV and X-ray energy bands. Collisional and photoionization cross sections for atoms and ions are fundamental to our ability to model such plasmas. Modeling is key in the X-ray band, where detector properties and limited spectral resolution limit the ability to measure model-independent line strengths, or other spectral features. Much of the motivation for studying such collisions and many of the tools, are not new. However, the motivation for such studies and their applications, have been affected by the advent of X-ray spectroscopy with the gratings on Chandra and XMM-Newton. In this talk I will review this motivation and describe the tools currently in use for such studies. I will also describe some current unresolved problems and the likely future needs for such data.

  2. ATLAS Event Display: Run 2 Heavy Ion Collision

    CERN Multimedia

    ATLAS Collaboration

    2018-01-01

    Event display of a lead-lead collision with a large transverse momentum photon. In this event, the expected balancing jet is not visible by eye, consistent with it being degraded by its passage through the quark-gluon plasma.

  3. Pion correlations in relativistic heavy ion collisions at Heavy Ion Spectrometer Systems (HISS)

    Energy Technology Data Exchange (ETDEWEB)

    Christie, W.B. Jr.

    1990-05-01

    This thesis contains the setup, analysis and results of experiment E684H Multi-Pion Correlations in Relativistic Heavy Ion Collisions''. The goals of the original proposal were: (1) To initiate the use of the HISS facility in the study of central Relativistic Heavy Ion Collisions (RHIC). (2) To perform a second generation experiment for the detailed study of the pion source in RHIC. The first generation experiments, implied by the second goal above, refer to pion correlation studies which the Riverside group had performed at the LBL streamer chamber. The major advantage offered by moving the pion correlation studies to HISS is that, being an electronic detector system, as opposed to the Streamer Chamber which is a visual detector, one can greatly increase the statistics for a study of this sort. An additional advantage is that once one has written the necessary detector and physics analysis code to do a particular type of study, the study may be extended to investigate the systematics, with much less effort and in a relatively short time. This paper discusses the Physics motivation for this experiment, the experimental setup and detectors used, the pion correlation analysis, the results, and the conclusions possible future directions for pion studies at HISS. If one is not interested in all the details of the experiment, I believe that by reading the sections on intensity interferometry, the section the fitting of the correlation function and the systematic corrections applied, and the results section, one will get a fairly complete synopsis of the experiment.

  4. Experimental investigation of the formation of negative hydrogen ions in collisions between positive ions and atomic or molecular targets

    International Nuclear Information System (INIS)

    Lattouf, Elie

    2013-01-01

    The formation of the negative hydrogen ion (H - ) in collisions between a positive ion and a neutral atomic or molecular target is studied experimentally at impact energies of a few keV. The doubly-differential cross sections for H - formation are measured as a function of the kinetic energy and emission angle for the collision systems OH + + Ar and O + + H 2 O at 412 eV/a.m.u. These H - ions can be emitted at high energies (keV) in hard quasi-elastic two-body collisions involving a large momentum transfer to the H center. However, H - anions are preferentially emitted at low energy (eV) due to soft many-body (≥ 2) collisions resulting in a low momentum transfer. The formation of H - ions by electron capture follows excitation or ionization of the molecule. The molecular fragmentation dynamics is modeled to simulate the emission of H - ions. The overall good agreement between the simulation and the experiment leads to the understanding of most of the experimental observations. (author) [fr

  5. Measurement of quarkonia production in heavy-ion collisions with the ATLAS detector

    CERN Document Server

    Kremer, Jakub Andrzej; The ATLAS collaboration

    2017-01-01

    The suppression of heavy quarkonia states in heavy-ion collisions is a phenomenon understood as a consequence of QGP formation in the hot, dense system formed in nucleus-nucleus collisions at the LHC. In addition to hot matter effects in heavy-ion collisions, cold nuclear effects may also affect quarkonia production. Therefore, a full assessment requires detailed studies on the effects present in both A+A and $\\textit{p}$+A collisions. Based on $\\textit{p}$+Pb data collected in 2013 and $\\textit{pp}$ and Pb+Pb data collected in 2015 at the LHC, the ATLAS experiment has studied prompt and non-prompt $J/\\psi$ and $\\psi\\left(2\\mathrm{S}\\right)$ productions as well as $\\Upsilon\\left(n\\mathrm{S}\\right)$ production via the di-muon decay final states. The results of the various measurements are discussed.

  6. Medium modification of averaged jet charge in heavy-ion collisions

    Science.gov (United States)

    Chen, Shi-Yong; Zhang, Ben-Wei; Wang, Enke

    2017-08-01

    Jet charge characterizes the electric charge distribution inside a jet. In this talk we make the first theoretical study of jet charge in high-energy nuclear collisions and calculate numerically the medium alternations of jet charge due to parton energy loss in the quark-gluon plasma. The parton multiple scattering in hot/dense QCD medium is simulated by a modified version of PYQUEN Monte Carlo model with 3+1D ideal hydrodynamical evolution of the fireball. Our preliminary results show that the averaged jet charge is significant modified in A+A collisions relative to that in p+p. The different features of quark jet charge and gluon jet charge in heavy-ion collisions, and the sensitivity of jet charge modifications to flavour dependence of energy loss are observed, which could then be used to discriminate quark and gluon jet as well as their energy loss patterns in heavy-ion collisions.

  7. Formation time of hadrons and density of matter produced in relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Pisut, J.; Zavada, P.

    1994-06-01

    Densities of interacting hadronic matter produced in Oxygen-Lead and Sulphur-Lead collisions at 200 GeV/nucleon are estimated as a function of the formation time of hadrons. Uncertainties in our knowledge of the critical temperature T c and of the formation time of hadrons τ 0 permit at present three scenarios: an optimistic one (QGP has already been produced in collisions of Oxygen and Sulphur with heavy ions and will be copiously in Lead collisions), a pessimistic one (QGP cannot be produced at 200 GeV/nucleon) and an intermediate one (QGP has not been produced in Oxygen and Sulphur Interactions with heavy ions and will be at best produced only marginally in Pb-collisions). The last option is found to be the most probable. (author)

  8. Quarkonia measurements in 5 TeV heavy-ion collisions with the ATLAS detector

    CERN Document Server

    Smirnov, Nikita; The ATLAS collaboration

    2017-01-01

    The in-medium suppression of heavy quarkonia production in heavy-ion collisions, with respect to proton-proton collisions, serves as a sensitive probe for studying the QGP. A full assessment of the suppression requires understanding of hot and cold nuclear matter effects using A-A and smaller sized p-A collision systems, respectively. Based on proton-lead collision data collected in 2013 and proton-proton and lead-lead collision data collected in 2015 at the LHC, it is possible to study J/psi, psi(2S) and Upsilon(nS) production using the ATLAS detector. The charmonium states are further separated into contributions from B-hadron decays and prompt production to study effects of charmonium suppression for B-hardons traversing the hot medium. Several measurements such as nuclear modification factors and excited-to-ground state ratios will be presented in this talk.

  9. Studies of relativistic heavy ion collisions at the AGS (E814/E877)

    International Nuclear Information System (INIS)

    Cleland, W.E.

    1993-01-01

    Efforts have continued in the area of peripheral and central collisions of relativistic heavy ions. In the area of peripheral collisions, the analysis of the 1n and 2p decay channels has been completed. In the area of central collisions, the first measurement of the E T distributions in Au + Au collisions, through the use of the participant calorimeter, was completed, and the results were compared with those obtained in collisions with Si projectiles. In addition, a thorough study of two-particle correlation functions was carried out by use of the data from the silicon pad multiplicity detector. Differential cross sections for 14.6-GeV/c 28 Si on Al, Cu, and Pb, and 11.4-GeV/c 197 Au on Al, Cu, Au, and Pb are given. 32 figs., 4 tabs., 24 refs

  10. Electron excitation collision strengths for positive atomic ions: a collection of theoretical data

    Energy Technology Data Exchange (ETDEWEB)

    Merts, A.L.; Mann, J.B.; Robb, W.D.; Magee, N.H. Jr.

    1980-03-01

    This report contains data on theoretical and experimental cross sections for electron impact excitation of positive atomic ions. It is an updated and corrected version of a preliminary manuscript which was used during an Atomic Data Workshop on Electron Excitation of Ions held at Los Alamos in November 1978. The current status of quantitative knowledge of collisional excitation collision strengths is shown for highly stripped ions where configuration mixing, relativistic and resonance effects may be important. The results show a reasonably satisfactory state for first-row isoelectronic ions and indicate that a considerable amount of work remains to be done for second-row and heavier ions.

  11. K-Vacancy Production in the Collision of Highly Charged Relativistic Ions With Heavy Atoms

    OpenAIRE

    KHABIBULLAEV, P. K.

    2000-01-01

    A general expression for the cross section of the inelastic collision of relativistic highly charged ion with heavy (relativistic) atoms is obtained using the generalized eikonal approximation. In the ultrarelativistic limit, the obtained formula coincides with a known exact one. As an application of the obtained result, probability and cross section of the K-vacany production in the U92+ - U91+ collision are calculated.

  12. Semiclassical approach to sequential fission in peripheral heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    Strazzeri Andrea

    2016-01-01

    Full Text Available A closed-form theoretical approach describing in a single picture both the evaporation component and the fast nonequilibrium component of the sequential fission of projectilelike fragments in a semiperipheral heavy-ion collision is derived and then applied to the dynamical fission observed in the 124Sn+64Ni semiperipheral collision at 35A MeV. Information on opposite polarization effects of the fissioning projectilelike fragments and on their “formation-to-fast fission lifetimes” are obtained.

  13. Fragment ion distribution in charge-changing collisions of 2-MeV Si ions with C60

    Science.gov (United States)

    Itoh, A.; Tsuchida, H.; Miyabe, K.; Majima, T.; Nakai, Y.

    2001-09-01

    We have measured positive fragment ions produced in collisions of 2 MeV Siq+ (q=0, 1, 2, 4) projectiles with a C60 molecular target. The measurement was performed with a time-of-flight coincidence method between fragment ions and charge-selected outgoing projectiles. For all the charge-changing collisions investigated here, the mass distribution of small fragment ions C+n (n=1-12) can be approximated fairly well by a power-law form of n-λ as a function of the cluster size n. The power λ derived from each mass distribution is found to change strongly according to different charge-changing collisions. As a remarkable experimental finding, the values of λ(loss) in electron loss collisions are almost the same for the same final charge states k irrespective of the initial charge q, exhibiting a nearly perfect linear relationship with k. We also performed calculations of the projectile ionization on the basis of the semiclassical approximation and obtained inelastic energy deposition for individual collision processes. The estimated energy deposition is found to have a simple correlation with the experimentally determined values of λ(loss).

  14. Estimation of electric conductivity of the quark gluon plasma via asymmetric heavy-ion collisions

    OpenAIRE

    Hirono, Yuji; Hongo, Masaru; Hirano, Tetsufumi

    2012-01-01

    We show that in asymmetric heavy-ion collisions, especially off-central Cu+Au collisions, a sizable strength of electric field directed from Au nucleus to Cu nucleus is generated in the overlapping region, because of the difference in the number of electric charges between the two nuclei. This electric field would induce an electric current in the matter created after the collision, which result in a dipole deformation of the charge distribution. The directed flow parameters $v_1^{\\pm}$ of ch...

  15. One- and two-body dissipation in peripheral heavy ion collisions

    International Nuclear Information System (INIS)

    Bartel, J.; Feldmeier, H.

    1980-01-01

    For peripheral collisions of heavy ions we solve the man-body Schroedinger equation in second order time-dependent perturbation theory. The two nuclei interact via a two-body interaction of finite range. With controllable approximations we get to a sensible comparison between 1p-1h excitations caused by the coherent Hartree part and direct 2p-2h excitations both created by the same two-body interaction. The results of the calculation show that for peripheral collisions almost all excitation energy originates from one-body dissipation. Furthermore we encounter large virtual excitations during the collision indicating a non Markovian process. (orig.)

  16. Measurement of charmonium production in heavy-ion collisions with the ATLAS detector

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00511724; The ATLAS collaboration

    2017-01-01

    The suppression of heavy charmonia states in heavy-ion collisions is a phenomenon understood as a consequence of quark gluon plasma formation in the hot, dense system formed in heavy ion collisions at the LHC. In addition to hot matter effects in heavy-ion collisions, cold nuclear effects may also affect heavy charmonia production. Therefore, a full assessment requires detailed studies on the effects present in both A+A and p+A collisions. Based on p+Pb data collected in 2013 and pp and Pb+Pb data collected in 2015 at the LHC, the ATLAS experiment has studied prompt and non-prompt $J/\\psi$ and $\\psi$(2S) productions via the dimuon decay final states. The production and excited-to-ground state ratios of heavy charmonia measured in both p+Pb and Pb+Pb collision data with respect to that measured in pp collision data will be presented in intervals of transverse momentum, rapidity and centrality.

  17. Measurement of charmonia production in heavy-ion collisions with the ATLAS detector

    CERN Document Server

    Lopez, Jorge; The ATLAS collaboration

    2017-01-01

    The suppression of heavy charmonia states in heavy-ion collisions is a phenomenon understood as a consequence of QGP formation in the hot, dense system formed in heavy ion collisions at the LHC. In addition to hot matter effects in heavy-ion collisions , cold nuclear effects may also affect heavy charmonia production . Therefore, a full assessment requires detailed studies on the effects present in both A+A and p+A collisions. Based on p+Pb data collected in 2013 and pp and Pb+Pb data collected in 2015 at the LHC, the ATLAS experiment has studied prompt and non-prompt $J/\\psi$ and $\\psi(2S)$ productions via the di-muon decay final states. The production and excited-to-ground state ratios of heavy charmonia measured in both p+Pb and Pb+Pb collision data with respect to that measured in pp collision data will be presented in intervals of transverse momentum, rapidity and centrality.

  18. Correlated electron-ion collisions in a strong laser field; Korrelierte Elektron-Ion-Stoesse in starken Laserfeldern

    Energy Technology Data Exchange (ETDEWEB)

    Ristow, T.

    2007-12-17

    Electron-ion-collisions in plasmas in the presence of an ultra-short intensive laser pulse can cause high energy transfers to the electrons. During the collision the oscillation energy of the electron in the laser field is changed into drift energy. In this regime, multi-photon processes, known from the ionization of neutral atoms (Above-Threshold Ionization), and successive, so called correlated collisions, are important. The subject of the thesis is a study of binary Coulomb collisions in strong laser fields. The collisions are treated both in the context of classical Newtonian mechanics and in the quantum-mechanical framework by the Schroedinger equation. In the classical case a simplified instantaneous collision model and a complete dynamical treatment are discussed. Collisions can be treated instantaneously, if the ratio of the impact parameter to the quiver amplitude is small. The energy distributions calculated in this approximation show an elastic peak and a broad plateau due to rescattered electrons. At incident velocities smaller than the quiver velocity, correlated collisions are observed in the electron trajectories of the dynamical model. This effect leads to characteristic momentum distributions of the electrons, that are explicitly calculated and compared with the results of the instantaneous model. In addition, the time-dependence of the collisions is discussed in the framework of a singular perturbation theory. The complete description of the Coulomb scattering requires a quantum-mechanical description. A time-dependent method of wave-packet scattering is used and the corresponding time-dependent three-dimensional Schroedinger equation is solved by an implicit ADImethod on a spatial grid. The momentum and the energy distributions of the scattered electrons are calculated by the Fourier transformation of the wavefunction. A comparison of the scattering from a repulsive and an attractive potential is used to distinguish between simple collisions and

  19. High-resolution electron collision spectroscopy with multicharged ions in merged beams

    Energy Technology Data Exchange (ETDEWEB)

    Lestinsky, M.

    2007-04-18

    The Heidelberg ion storage ring Tsr is currently the only ring equipped with two independent devices for the collinear merging of a cold electron beam with stored ions. This greatly improves the potential of electron-ion collision experiments, as the ion beam can be cooled with one electron beam, while the other one is used as a dedicated target for energy-resolved electron collision processes, such as recombination. The work describes the implementation of this system for rst electron collision spectroscopy experiments. A detection system has been realized including an ion detector and specroscopic beam-control software and instrumentation. Moreover, in order to improve the spectroscopic resolution systematical studies of intrinsic relaxation processes in the electron beam have been carried out. These include the dependence on the electron beam density, the magnetic guiding eld strength, and the acceleration geometry. The recombination measurements on low-lying resonances in lithiumlike Sc{sup 18+} yield a high-precision measurement of the 2s-2p{sub 3/2} transition energy in this system. Operation of the two-electron-beam setup at high collision energy ({approx}1000 eV) is established using resonances of hydrogenlike Mg{sup 11+}, while the unique possibility of modifying the beam-merging geometry con rms its importance for the electron-ion recombination rate at lowest relative energy, as demonstrated on F{sup 6+}. (orig.)

  20. Treatment of ion-atom collisions using a partial-wave expansion of the projectile wavefunction

    Energy Technology Data Exchange (ETDEWEB)

    Foster, M [Los Alamos National Laboratory; Colgan, J [Los Alamos National Laboratory; Wong, T G [SANTA CLARA U; Madison, D H [MISSOURI U

    2008-01-01

    We present calculations of ion-atom collisions using a partial-wave expansion of the projectile wavefunction. Most calculations of ion-atom collisions have typically used classical or plane-wave approximations for the projectile wavefunction, since partial-wave expansions are expected to require prohibitively large numbers of terms to converge scattering quantities. Here we show that such calculations are possible using modern high-performance computing. We demonstrate the utility of our method by examining elastic scattering of protons by hydrogen and helium atoms, problems familiar to undergraduate students of atomic scattering. Application to ionization of helium using partial-wave expansions of the projectile wavefunction, which has long been desirable in heavy-ion collision physics, is thus quite feasible.

  1. Violent heavy ion collisions around the Fermi energy

    International Nuclear Information System (INIS)

    Borderie, B.

    1985-01-01

    Experimental results on central collisions will be presented and it will be shown that a fusion process still occurs; deexcitation of the hot fused systems formed will be discussed. Then, from the qualitative evolution of central collision products from different reactions studied in the E/A range 20-84 MeV, the vanishing of fusion processes will be inferred; it will be discussed in terms of critical energy deposit and maximum excitation energy per nucleon that nuclei can carry. Finally results concerning the large production of light fragments (3 < approximately Z < approximately 12) experimentally observed in the Fermi energy domain will be presented and discussed in terms of a multifragmentation of the whole nuclear system or of part of it for intermediate impact parameter collisions (109 refs, 49 fig)

  2. Learning from numerical calculations of ion-atom collisions

    International Nuclear Information System (INIS)

    Reading, J.F.; Ford, A.L.; Martir, M.; Becker, R.L.

    1981-01-01

    Violent collision of two independent many-particle systems, victims, are discussed in the atomic sphere. The asymmetric region where the charge of the projectile Z/sub p/ is less than the target nuclear charge Z/sub n/ is now well understood though interesting details still need to be worked out. Negatively charged projectiles offer a new illustration of Fadeev re-arrangement collisions. Multi-electron coherence effects illustrate the richness of the field but a symmetric (Z/sub p/ approx. Z/sub n/) collision treatment is needed. A new one and a half center expansion method promises a solution to this problem. Future areas of interest are discussed

  3. Electroweak bosons in heavy ion collisions in CMS

    Energy Technology Data Exchange (ETDEWEB)

    Zsigmond, Anna Julia

    2014-06-15

    The Compact Muon Solenoid (CMS) is fully equipped to measure leptonic decays of electroweak probes in the high multiplicity environment of nucleus–nucleus collisions. The inclusive and differential Z boson yields in the muon and electron decay channels are presented, together with measurements of the yield of W bosons decaying into a muon and an (anti)neutrino as a function of centrality, and the W charge asymmetry as a function of rapidity. The results confirm the binary scaling hypothesis, and show that possible modifications due to nuclear PDFs with respect to pp collisions, scaled by the number of elementary nucleon–nucleon collisions, are within the statistical and systematic uncertainties of the current measurements.

  4. Numerical analysis of effects of ion-neutral collision processes on RF ICP discharge

    Science.gov (United States)

    Nishida, K.; Mattei, S.; Lettry, J.; Hatayama, A.

    2018-01-01

    The discharge process of a radiofrequency (RF) inductively coupled plasma (ICP) has been modeled by an ElectroMagnetic Particle-in-Cell Monte Carlo Collision method (EM PIC-MCC). Although the simulation had been performed by our previous model to investigate the discharge mode transition of the RF ICP from a kinetic point of view, the model neglected the collision processes of ions (H+ and H2+) with neutral particles. In this study, the RF ICP discharge process has been investigated by the latest version of the model which takes the ion-neutral collision processes into account. The basic characteristics of the discharge mode transition provided by the previous model have been verified by the comparison between the previous and present results. As for the H-mode discharge regime, on the other hand, the ion-neutral collisions play an important role in evaluating the growth of the plasma. Also, the effect of the ion-neutral collisions on the kinetic feature of the plasma has been investigated, which has highlighted the importance of kinetic perspective for modeling the RF ICP discharge.

  5. Experimental overview on flow observables in heavy ion collisions

    CERN Document Server

    Mohapatra, Soumya

    2016-01-01

    This paper summarizes the experimental results on flow phenomena that were presented at Quark matter 2015, with a focus on new flow observables and correlations in small systems. The results presented include event-shape selected pT spectra and vn measurements, correlations between flow harmonics of different orders, study of factorization breakdown in two-particle correlations, and principal component analysis of two-particle correlations. Recent developments in investigation of collective effects in small collisions systems, namely, p+A, d+A and 3He + A as well as in pp collisions are also presented.

  6. Pauli correlations in heavy-ion collisions at high energies

    International Nuclear Information System (INIS)

    Franco, V.; Nutt, W.T.

    1977-01-01

    The effects of short-range correlations on the Glauber expansion for nucleus-nucleus collisions are calculated using the Fermi gas model for nuclei. When the Pauli principle is neglected for collisions between heavy nuclei, calculation of the optical phase-shift function leads to non-unitary results and cross sections cannot be obtained. When Pauli correlations are included important cancellations in the optical phase-shift function are found which make possible the calculation of total and differential cross sections for heavy nuclei. (Auth.)

  7. Measurement Of The Heavy-Ion Collision Event Characteristics With The Atlas Experiment At The Lhc

    Directory of Open Access Journals (Sweden)

    Iwona Grabowska-Bołd

    2015-01-01

    Full Text Available Heavy-ion collisions at extreme energies can reproduce conditionspresent in the early Universe. The new state of very dense and hotmatter of deconfined quarks and gluons, called the Quark GluonPlasma~(QGP, is observed. This state is characterised by very lowviscosity resembling the properties of a perfect fluid. In suchmedium, the density fluctuations can be easily spread. In experimentalpractice, the size of these fluctuations is estimated by measuring theangular correlation of produced particles. The aim of this paper isto present measurements of the azimuthal anisotropy of chargedparticles produced in heavy-ion collisions using the ATLAS detector atthe LHC. Two measurement techniques are presented and compared.

  8. Effect of position and momentum constraints on charge distribution in heavy-ion collisions

    International Nuclear Information System (INIS)

    Rajni; Kumar, Suneel

    2012-01-01

    The rich phenomenology of multifragmentation has been widely explored after two decades of its discovery. It has been experimentally shown that in one single heavy ion collision many intermediate mass fragments (IMFs) are produced, where IMFs are defined as fragments with 5 ≤ A ≤ A tot /6. In the earlier literature, the multifragmentation was studied by Jakobsson et al. who measured the charge particle distribution along with their kinetic energy spectra in 16 O/ 36 Ar induced reaction between 25 and 200 MeV/nucleon representing the various phenomena in heavy ion collisions

  9. Systematics of elliptic flow in heavy-ion collisions

    Indian Academy of Sciences (India)

    Abstract. We analyze elliptic flow from SIS to RHIC energies systematically in a realistic dy- namical cascade model. We compare our results with the recent data from STAR and PHOBOS collaborations on elliptic flow of charged particles at midrapidity in Au·Au collisions at RHIC. In the analysis of elliptic flow at RHIC energy ...

  10. Electroweak Bosons in Heavy Ion Collisions with the ATLAS Detector

    CERN Document Server

    Hu, Qipeng; The ATLAS collaboration

    2015-01-01

    Electroweak bosons processes (W, Z and photon) provide experimental controls over initial geometric and nuclear PDFs (nPDFs). The ATLAS has measured the production of all three bosons in Pb+Pb at 2.76 TeV and the production of Z bosons in p+Pb collisions at 5.02 TeV. Z bosons are measured via both di-electron and di-muon decay channel. W bosons are measured with isolated single leptons and missing transverse energy constructed from tracks. Photons are measured using ATLAS electromagnetic calorimeter and calorimeter-based isolation observables. The yields of all three bosons in Pb+Pb collisions are found to obey binary collision scaling. But Run 1 Pb+Pb data is not yet sensitive enough to discern specific features of nPDF effects. The Z yield in p+Pb collisions provide another excellent opportunity to test nPDF effects. In addition, the centrality dependence of Z boson production in p+Pb is measured and analyzed within standard Glauber model and the Glauber-Gribov model with event-by-event fluctuations. The ef...

  11. Fragmentation of positronium in collision with Li ion including ...

    Indian Academy of Sciences (India)

    Because of the large breakup probability of the Ps (above its binding energy 6.8 eV), the multiple scattering effect from inner layer atoms of the solid is expected to be negligible for the Ps (unlike the low energy electron and positron) and as such the low energy Ps collision should be confined to the outermost surface layers.

  12. Systematics of elliptic flow in heavy-ion collisions

    Indian Academy of Sciences (India)

    We analyze elliptic flow from SIS to RHIC energies systematically in a realistic dynamical cascade model. We compare our results with the recent data from STAR and PHOBOS collaborations on elliptic flow of charged particles at midrapidity in Au + Au collisions at RHIC. In the analysis of elliptic flow at RHIC energy, we find ...

  13. Low-energy collision processes of ions with atoms and solid surfaces. Progress report for 1995/11/15-1998/11/14

    International Nuclear Information System (INIS)

    Solov'ev, E.A.

    1999-01-01

    Ionisation cross sections for ground state hydrogen under collision with helium, carbon and oxygen ions were studied. Using a adiabatic super promotion model of low-energy atomic collisions, a simple scaling relationship was derived. For state-selective excitations in atom-ion collisions, a classical description was found for arbitrary values of collision energy

  14. Report on the Oak Ridge workshop on Monte Carlo codes for relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Awes, T.C.; Sorensen, S.P.

    1988-01-01

    In order to make detailed predictions for the case of purely hadronic matter, several Monte Carlo codes have been developed to describe relativistic nucleus-nucleus collisions. Although these various models build upon models of hadron-hadron interactions and have been fitted to reproduce hadron-hadron collision data, they have rather different pictures of the underlying hadron collision process and of subsequent particle production. Until now, the different Monte Carlo codes have, in general, been compared to different sets of experimental data, according to which results were readily available to the model builder or which Monte Carlo code was readily available to an experimental group. As a result, it has been difficult to draw firm conclusions about whether the observed deviations between experiments and calculations were due to deficiencies in the particular model, experimental discrepancies, or interesting effects beyond a simple superposition of nucleon-nucleon collisions. For this reason, it was decided that it would be productive to have a structured confrontation between the available experimental data and the many models of high-energy nuclear collisions in a manner in which it could be ensured that the computer codes were run correctly and the experimental acceptances were properly taken into account. With this purpose in mind, a Workshop on Monte Carlo Codes for Relativistic Heavy-Ion Collisions was organized at the Joint Institute for Heavy Ion Research at Oak Ridge National Laboratory from September 12--23, 1988. This paper reviews this workshop. 11 refs., 6 figs

  15. Observation of Global Hyperon Polarization in Ultrarelativistic Heavy-Ion Collisions

    Science.gov (United States)

    Upsal, Isaac; STAR Collaboration

    2017-11-01

    Collisions between heavy nuclei at ultra-relativistic energies form a color-deconfined state of matter known as the quark-gluon plasma. This state is well described by hydrodynamics, and non-central collisions are expected to produce a fluid characterized by strong vorticity in the presence of strong external magnetic fields. The STAR Collaboration at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) has measured collisions between gold nuclei at center of mass energies √{sNN} = 7.7- 200 GeV. We report the first observation of globally polarized Λ and Λ bar hyperons, aligned with the angular momentum of the colliding system. These measurements provide important information on partonic spin-orbit coupling, the vorticity of the quark-gluon plasma, and the magnetic field generated in the collision.

  16. Collective flow of open heavy flavour in heavy ion collisions at the LHC energies with CMS

    CERN Document Server

    Lee, Yen-Jie

    2017-01-01

    Heavy flavour mesons are used as powerful tools for the study of the strongly interacting medium in heavy ion collisions as heavy quarks are sensitive to the transport properties of the medium. In these proceedings, $D^0$ nuclear modification factors, comparing the yields in PbPb and pp collisions, and azimuthal anisotropies in PbPb collisions are reported. Prompt $D^0$ mesons and their antiparticles have been measured with the CMS detector via the hadronic decay channels $D^0 \\to K^- \\pi^+$ and $\\bar{D}^0 \\to K^+ \\pi^-$ in PbPb and pp collisions at a centre-of-mass energy of 5.02 TeV. Nonprompt $D^0$ from b decays are subtracted. The $D^0$ results are compared to inclusive charged particles, nonprompt $J/\\psi$~ mesons from b decays and $B^+$ mesons in order to reveal possible meson mass dependence of the observables.

  17. Investigation of the intermediate LK molecular orbital radiation in heavy ion-atom collisions

    International Nuclear Information System (INIS)

    Frank, W.; Kaun, K.-H.; Manfrass, P.

    1981-01-01

    The continuum consisting of an intensive low-energy and a high-energy components in heavy-ion atom collision systems with atomic numbers Z 1 , Z 2 > 28 is studied. The aim of the study is to prove that the C1 continuum cannot be caused by ridiative electron capture (REC) being molecular orbital (MO) radiation to the 2ptau level. It is shown that the comparison of the C1 yields obtained in Kr+Nb asymmetric collisions in gas and solid targets is associated with the formation of vacancies in the lower-Z collision partner and can be interpreted as quasimolecular radiation to the 2ptau orbital level. The strong suppression of the C2 component in the gas target experimets indicates that the MO radiation to the 1stau orbit is emitted preferentially in the two-collision process in symmetric and near-symmetric systems with Z 1 , Z 2 [ru

  18. Evolution of the nuclide distribution and heat partition along the dissipation path in heavy ion collisions

    International Nuclear Information System (INIS)

    Planeta, R.

    1990-04-01

    We discuss several problems of nuclear physics with heavy ions. Special attention is paid to close collisions, where impact parameters are considerably smaller than the corresponding grazing values. Such collisions can lead to a formation of a compound nucleus (fusion) or to two body exit channels with a sizable loss of kinetic energy and large transfer of mass and charge between interacting nuclei (damped collisions). A short survey of experimental works done with my participation and devoted to fusion reactions is presented. This is followed by presentation of new experimental results in the field of damped collisions. The data demonstrate that the N/Z equilibration and temperature equilibration are not rapid processes. A distinct correlation between the net nucleon transfer and the heating of the acceptor nucleus is observed. Experimental data are compared with the transport model. Disagreement between model and experiment is discussed. 113 refs. (author)

  19. Second Order Dissipative Fluid Dynamics and Relativistic Heavy Ion Collisions

    International Nuclear Information System (INIS)

    Muronga, Azwinndini

    2004-01-01

    Non-ideal fluid dynamics is used to describe the space-time evolution of matter produced in relativistic nuclear collisions such as those at RHIC in BNL and at LHC in CERN. Dissipation is accounted for by employing causal theory of relativistic dissipative fluid dynamics derived from extended irreversible thermodynamics. The results are compared to those obtained by using Navier-Stokes theory and the ones obtained by perfect fluid approximation

  20. Probing early-time correlations in heavy ion collisions

    International Nuclear Information System (INIS)

    Gavin, Sean; Moschelli, George

    2013-01-01

    We investigate the common influence of correlations arising from initial state parton density fluctuations on measured multiplicity and momentum fluctuations as well as flow fluctuations. We calculate both a universal correlation scale in an initial stage Glasma flux tube picture and the modification to these correlations from later stage hydrodynamic flow. We find quantitative agreement with measurements over a range of collision systems and energies.

  1. Charged particle multiplicity and correlations in heavy ion collisions in the ATLAS experiment

    CERN Document Server

    Zabinski, B; The ATLAS collaboration

    2013-01-01

    Since the start of Large Hadron Collider (LHC) the ATLAS experiment has collected data from $p+p$, Pb+Pb and recently $p$+Pb collisions. In this paper two topics from the heavy ion programme are presented. The first of them is the multiplicity of charged particles in Pb+Pb collisions studied as a function of centrality. In such collisions very high pseudorapidity particle density is obtained, reaching 1738 $\\pm 76$ at $\\eta \\approx0$. For the $p$+Pb collisions the latest analysis of two-particle correlations is presented. The "ridge" observed in pp events with large multiplicities is present also in central $p$+Pb collisions selected by large $\\Sigma E_{T}$ measured at the Pb fragmentation side. In the azimuthal correlation for $2<|\\Delta \\eta|< 5$ two components can be extracted. Assuming that in the peripheral collisions only the correlation due to momentum conservation effects are present, in the central collisions additional quadruple modulation component can be identified.

  2. Two components in charged particle production in heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    A.A. Bylinkin

    2016-02-01

    Full Text Available Transverse momentum spectra of charged particle production in heavy-ion collisions are considered in terms of a recently introduced Two Component parameterization combining exponential (“soft” and power-law (“hard” functional forms. The charged hadron densities calculated separately for them are plotted versus number of participating nucleons, Npart. The obtained dependences are discussed and the possible link between the two component parameterization introduced by the authors and the two component model historically used for the case of heavy-ion collisions is established. Next, the variations of the parameters of the introduced approach with the center of mass energy and centrality are studied using the available data from RHIC and LHC experiments. The spectra shapes are found to show universal dependences on Npart for all investigated collision energies.

  3. Triggering on Hard Probes in Heavy-Ion Collisions with the CMS Experiment at the LHC

    CERN Document Server

    Roland, Christof

    2009-01-01

    Studies of heavy-ion collisions at the LHC will benefit from an array of qualitatively new probes not readily available at lower collision energies. These include fully formed jets at $E_T > 50$~GeV, Z$^0$'s and abundantly produced heavy flavors. For Pb+Pb running at LHC design luminosity, the collision rate in the CMS interaction region will exceed the available bandwidth to store data by several orders of magnitude. Therefore an efficient trigger strategy is needed to select the few percent of the incoming events containing the most interesting signatures. In this report, we will present the heavy-ion trigger strategy developped for the unique two-layer trigger system of the CMS experiment consisting of a ``Level-1'' trigger based on custom electronics and a High Level Trigger (HLT) implemented using a large cluster of commodity computers.

  4. Heavy Quarkonium Dissociation Cross Sections in Relativistic Heavy-Ion Collisions

    Energy Technology Data Exchange (ETDEWEB)

    C.-Y. Wong; Eric Swanson; Ted Barnes

    2001-12-01

    Many of the hadron-hadron cross sections required for the study of the dynamics of matter produced in relativistic heavy-ion collisions can be calculated using the quark-interchange model. Here we evaluate the low-energy dissociation cross sections of J/{psi}, {psi}', {chi}, {Upsilon}, and {Upsilon}' in collision with {pi}, {rho}, and K, which are important for the interpretation of heavy-quarkonium suppression as a signature for the quark gluon plasma. These comover dissociation processes also contribute to heavy-quarkonium suppression, and must be understood and incorporated in simulations of heavy-ion collisions before QGP formation can be established through this signature.

  5. Origins of the di-jet asymmetry in heavy ion collisions

    CERN Document Server

    Milhano, José Guilherme

    2016-01-01

    The di-jet asymmetry --- the measure of the momentum imbalance in a di-jet system --- is a key jet quenching observable. Using the event generator \\jewel we show that the di-jet asymmetry is dominated by fluctuations both in proton-proton and in heavy ion collisions. We discuss how in proton-proton collisions the asymmetry is generated through recoil and out-of-cone radiation. In heavy ion collisions two additional sources contribute to the asymmetry, namely energy loss fluctuations and differences in path length. The latter is shown to be a sub-leading effect. We discuss the implications of our results for the interpretation of this observable.

  6. A Cross-Platform Numerical Model of Ion-Wall Collisions

    CERN Document Server

    Veitzer, Seth A; Molvik, Arthur; Stoltz, Peter; Vay, Jean-Luc

    2005-01-01

    Ion collisions with beam-pipe walls is a significant source of secondary electron clouds and desorbed neutral gasses in particle accelerators. Ions may reflect from beam-pipe walls and undergo further collisions downstream. These effects can cause beam degradation and are expected to be problematic in the design of heavy ion accelerators. The well-known SRIM code provides physically-based monte carlo simulations of ion-wall collisions. However, it is difficult to interface SRIM with high-performance simulation codes. We present details on the development of a package of Python modules which integrate the simulation of ion-wall interactions at grazing incidences with the high-performance particle-in-cell and electron cloud codes WARP and POSINST. This software package, called GriPY, calculates reflected angles and energies of ions which strike beam-pipe walls at grazing incidences, based upon interpolation of monte carlo statistics generated by benchmark simulations run in SRIM for a variety of relevant incide...

  7. ELECTRON-CAPTURE IN HIGHLY-CHARGED ION-ATOM COLLISIONS

    NARCIS (Netherlands)

    MORGENSTERN, R

    1993-01-01

    An attempt is made to identify the most important mechanisms responsible for the rearrangement of electrons during collisions between multiply charged ions and atoms at keV energies. It is discussed to which extent the influence of binding energy, angular momentum of heavy particles and electrons,

  8. Jet and Leading Hadron Production in High-energy Heavy-ionCollisions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin-Nian

    2005-11-01

    Jet tomography has become a powerful tool for the study ofproperties of dense matter in high-energy heavy-ion collisions. I willdiscuss recent progresses in the phenomenological study of jet quenching,including momentum, colliding energy and nuclear size dependence ofsingle hadron suppression, modification of dihadron correlations and thesoft hadron distribution associatedwith a quenched jet.

  9. 12th International workshop on Inelastic Ion-Surface Collisions.Final report

    International Nuclear Information System (INIS)

    Rabalais, J.W.; Nordlander, P.

    1999-01-01

    The twelfth international workshop on inelastic ion surface collisions was held at the Bahia Mar Resort and Conference Center on South Padre Island, Texas (USA) from January 24-29, 1999. The workshop brought together most of the leading researchers from around the world to focus on both the theoretical and experimental aspects of particle - surface interactions and related topics

  10. Event-by-Event Cluster Analysis of Final States from Heavy Ion Collisions

    International Nuclear Information System (INIS)

    Fialkowski, K.; Wit, R.

    1999-01-01

    We present an event-by-event analysis of the cluster structure of final multihadron states resulting from heavy ion collisions. A comparison of experimental data with the states obtained from Monte Carlo generators is shown. The analysis of the first available experimental events suggests that the method is suitable for selecting some different types of events. (author)

  11. Energy of vanishing flow in heavy-ion collisions: Role of mass ...

    Indian Academy of Sciences (India)

    Energy of vanishing flow in heavy-ion collisions: Role of mass asymmetry of a reaction. VARINDERJIT KAUR and SUNEEL KUMAR. ∗. School of Physics and Material Science, Thapar University, Patiala 147 004, India. ∗. Corresponding author. E-mail: suneel.kumar@thapar.edu. MS received 28 April 2011; revised 4 July ...

  12. Heavy ion reaction measurements with the EOS TPC (looking for central collisions with missing energy)

    International Nuclear Information System (INIS)

    Wieman, H.H.

    1994-05-01

    The EOS TPC was constructed for complete event measurement of heavy ion collisions at the Bevalac. We report here on the TPC design and some preliminary measurements of conserved event quantities such as total invariant mass, total momentum, total A and Z

  13. Surface Collisions of Small Cluster Ions at Incident Energies 10-102 eV

    Czech Academy of Sciences Publication Activity Database

    Herman, Zdeněk

    2004-01-01

    Roč. 233, - (2004), s. 361-371 ISSN 1387-3806 R&D Projects: GA MŠk ME 561 Grant - others:XE(CZ) EURATOM-IPP.CR Institutional research plan: CEZ:AV0Z4040901 Keywords : surface collisions * cluster ions * unimolecular dissociation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.235, year: 2004

  14. Energy scan in heavy-ion collisions and search for a critical point

    Czech Academy of Sciences Publication Activity Database

    Tokarev, M. V.; Zborovský, Imrich

    2012-01-01

    Roč. 75, č. 6 (2012), s. 700-706 ISSN 1063-7788 R&D Projects: GA MŠk LA08002; GA MŠk LA08015 Institutional support: RVO:61389005 Keywords : heavy-ion collisions * specific heat Subject RIV: BE - Theoretical Physics Impact factor: 0.539, year: 2012

  15. ATLAS One of the first Heavy ions collisions with stable beams- Event Display - November 2015

    CERN Multimedia

    ATLAS Collaboration

    2015-01-01

    One of the first heavy ions collisions with stable beams recorded by ATLAS in November 2015. Tracks reconstructed from hits in the inner tracking detector are shown as orange arcs curving in the solenoidal magnetic field. The green and yellow bars indicate energy deposits in the Liquid Argon and Scintillating Tile calorimeters respectively. The beam pipe and the inner detectors are also shown.

  16. Hot nuclei and search for multifragmentation in medium-energy heavy-ion collisions

    International Nuclear Information System (INIS)

    Doubre, H.

    1988-01-01

    Some recent determinations of the excitation energies and temperatures of composite systems formed in intermediate-energy heavy-ion collisions are described and the issue of a limiting temperature is discussed. Several examples of experimental investigations of an eventual occurrence of a multifragmentation process are also described

  17. Collective flows in high-energy heavy-ion collisions at AGS and SPS ...

    Indian Academy of Sciences (India)

    Collective flows in high-energy heavy-ion collisions at AGS and SPS energies∗. A OHNISHI1, M ISSE1, N OTUKA2, P K SAHU3 and Y NARA4. 1Division of Physics, Graduate School of Science, Hokkaido University, Sapporo,. Hokkaido 060-0810, Japan. 2Nuclear Data Center, Department of Nuclear Energy System, Japan ...

  18. Collective flows in high-energy heavy-ion collisions at AGS and SPS ...

    Indian Academy of Sciences (India)

    Abstract. Proton collective flows in heavy-ion collisions from AGS ((2–11) A GeV) to. SPS ((40, 158) A GeV) energies are investigated in a nonequilibrium transport model with nuclear mean-field (MF). Sideward 〈px〉, directed v1, and elliptic v2 flows are systematically studied with different assumptions on the nuclear ...

  19. New analytical treatment for a kind of two dimensional integrals in ion-atom collisions

    International Nuclear Information System (INIS)

    Yang Qifeng; Kuang Yurang

    1994-01-01

    A kind of two-dimensional integrals, separated from two-center matrix elements in ion-atom collisions, is analytically integrated by introducing the Laplace transform into the integrals and expressed by the modified Bessel functions. The traditional Feynman transform is very complicated for this kind of more general integrals related to the excited state capture

  20. Coupling constant corrections in a holographic model of heavy ion collisions

    NARCIS (Netherlands)

    Grozdanov, Sašo; Schee, Wilke van der|info:eu-repo/dai/nl/330953974

    2017-01-01

    We initiate a holographic study of coupling-dependent heavy ion collisions by analysing for the first time the effects of leading-order, inverse coupling constant corrections. In the dual description, this amounts to colliding gravitational shock waves in a theory with curvature-squared terms. We

  1. ''Atomic'' Bremsstrahlung or polarizational radiation in collision of many-electron ions

    International Nuclear Information System (INIS)

    Amusia, M.Ya.; Solov'yov, A.V.

    1991-01-01

    In this work the so-called ''Atomic'' bremsstrahlung (AB) or polarizational radiation, created in collisions of atoms or ions, is discussed. This kind of radiation arises due to the polarization of the electron shell of colliding particles. It is created by the structured projectiles and targets if the constituents are electrically charged. 6 refs, 2 figs

  2. Jets and Jet-like Correlations in Heavy Ion and p+p Collisions at PHENIX

    International Nuclear Information System (INIS)

    2010-01-01

    Jets from heavy ion collisions provide a measurement of the medium-induced parton energy loss and the in-medium fragmentation properties. The medium modification effects are determined by comparing to a p+p baseline measurement, but the high multiplicity background in a heavy ion collision inhibits the direct application of traditional jet reconstruction techniques and novel approaches are needed to deal with this environment. Alternatively, angular correlations between the hadronic fragments of energetic partons can be used to understand the hot dense matter produced in relativistic heavy ion collisions. The yield and shape modifications of the away side peaks as function of transverse momentum compared to p+p has been interpreted as a medium response to parton energy loss. Direct photon-hadron correlations are another excellent channel to study jets from heavy ion collisions. Photons do not interact strongly with the medium and thus the photon approximately balances the momentum of the opposing jet, allowing the measurement of the effective modification to the fragmentation function through jet energy loss in the medium.

  3. Positron-electron pairs produced in heavy-ion collisions

    International Nuclear Information System (INIS)

    Ahmad, I.; Austin, Sam. M.; Back, B. B.; Betts, R. R.; Calaprice, F. P.; Chan, K. C.; Chishti, A.; Conner, C. M.; Dunford, R. W.; Fox, J. D.

    1999-01-01

    The production of positron-electron pairs in collisions of 238 U+ 232 Th at 5.95 MeV/nucleon, and of 238 U+ 181 Ta at 5.95, 6.1, and 6.3 MeV/nucleon, has been studied with the APEX spectrometer at Argonne National Laboratory. Several analyses have been performed to search for sharp structures in sum-energy spectra for positron-electron pairs. Such features have been reported in previous experiments. No statistically convincing evidence for such behavior is observed in the present data. (c) 1999 The American Physical Society

  4. Nuclear equation of state in heavy- ion collisions

    International Nuclear Information System (INIS)

    Sahu, P.K.; Ohnishi, A.

    1999-01-01

    We extend the baryon flow (P x /A(y)) calculation in the relativistic transport model at SIS (0.25 - 2 AGeV) to AGS (≤20.0 AGeV) energies for Au + Au collisions. We can reproduce the flow data of the EoS and E877 collaborations and the nucleon optical potential upto 1 GeV, by reducing the strength of the vector potential moderately at high relative momentum. This reduction leads to a softening of the nuclear matter equation of state at high density. (author)

  5. Investigating the multiparticle decay in intermediate energy heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Del Zoppo, A.; Alba, R.; Coniglione, R.; Agodi, C.; Bellia, G.; Finocchiaro, P.; Loukachine, K.; Maiolino, C.; Migneco, E.; Peghaire, A.; Piattelli, P.; Santonocito, D.; Sapienza, P. (INFN Laboratorio Nazionale del Sud, Via S. Sofia 44, 95123 Catania (Italy) Dipartimento di Fisica dell' Universita di Catania (Italy) GANIL, Caen (France))

    1994-06-01

    Exclusive measurements of light charged products (LCP) in the [sup 132]Xe+[sup 197]Au collisions at 44 MeV/nucleon have been performed using MEDEA 4[pi] detection system. The admixture of each partricle type into the LCP multiplicity is found to be almost independent of the impact parameter. The data are analyzed with a formalism where the fluctuations of the multiparticle decay are described by uncorrelated Poissonian statistical distributions. The impact parameter filtering is performed using the LCP multiplicity. Self-correlation and impact parameter averagining effects are identified. The dominance of the statistical contribution in the fluctuations of the LCP multiplicity is deduced.

  6. D meson production in heavy ion collisions with CMS

    CERN Document Server

    Kim, Hyunchul

    2016-01-01

    The nuclear modification factor, $R_{\\text{AA}}$, of the $D^0$ meson production has been measured in pp and PbPb collisions at $\\sqrt{s_{NN}}~=~2.76$ TeV and 5.02 TeV with CMS detector. This measurement is important in investigating the properties of the high-density QCD (quantum chromodynamics) matter. The dependence on the centrality and transverse momentum up to 100 GeV were presented in a poster at this conference.

  7. Dynamical Evolution of the Scalar Condensate in Heavy Ion Collisions

    CERN Document Server

    Csernai, Laszlo P.; Jeon, Sangyong; Kapusta, Joseph I.; Csernai, Laszlo P.; Ellis, Paul J.; Jeon, Sangyong; Kapusta, Joseph I.

    2000-01-01

    We derive the effective coarse-grained field equation for the scalar condensate of the linear sigma model in a simple and straightforward manner using linear response theory. In general, the necessary response functions cannot be obtained in perturbation theory but require a summation of ladder diagrams. We estimate these response functions using direct physical reasoning. The field equation is solved for hot matter undergoing either one or three dimensional expansion and cooling in the aftermath of a high energy nuclear collision. The results show that the time constant for returning the scalar condensate to thermal equilibrium is of order 2 fm/c.

  8. Atom capture and loss in ion molecule collisions

    International Nuclear Information System (INIS)

    Breinig, M.; Lasley, S.E.; Gaither, C.C. III.

    1985-01-01

    Progress is reported in measuring the energy and angular distribution of protons emerging with velocity close to the beam velocity from the target region when Ar + beams collide with a CH 4 target and ArH + beams collide with a He target at asymptotically high speeds. The protons result from the transfer of a target constituent to the projectile (atom capture) or from the dissociation of the projectile molecule in the collision (atom loss). For atom capture processes the Thomas peak is clearly observed. 10 refs., 3 figs

  9. Lifetime measurement of a collision complex using ion cyclotron double resonance - H2C6N2(+)

    Science.gov (United States)

    Anicich, Vincent G.; Sen, Atish D.; Huntress, Wesley T., Jr.; Mcewan, Murray J.

    1991-01-01

    In the ion-molecule reaction between HC3N(+) and HC3N, the lifetime of the collision complex (H2C6N2+)-asterisk was long enough that ion cyclotron double-resonance techniques could be used to probe the distribution of the lifetimes of the collision complex. The mean lifetime of the collision complex at room temperature was measured as 180 microsec with a distribution ranging from 60 to 260 microsec as measured at the half-heights in the distribution. Lifetimes of this magnitude with respect to unimolecular dissociation allow for some stabilization of the collision complex by the slower process of infrared photon emission.

  10. A Cone Jet-Finding Algorithm for Heavy-Ion Collisions at LHCEnergies

    Energy Technology Data Exchange (ETDEWEB)

    Blyth, S.-L.; Horner, M.J.; Awes, T.C.; Cormier, T.; Gray, H.M.; Klay, J.L.; Klein, S.R.; van Leeuwen, M.; Morsch, A.; Odyniec, G.; Pavlinov, A.

    2006-07-27

    Standard jet finding techniques used in elementary particle collisions have not been successful in the high track density of heavy-ion collisions. This paper describes a modified cone-type jet finding algorithm developed for the complex environment of heavy-ion collisions. The primary modification to the algorithm is the evaluation and subtraction of the large background energy, arising from uncorrelated soft hadrons, in each collision. A detailed analysis of the background energy and its event-by-event fluctuations has been performed on simulated data, and a method developed to estimate the background energy inside the jet cone from the measured energy outside the cone on an event-by-event basis. The algorithm has been tested using Monte-Carlo simulations of Pb+Pb collisions at {radical}s = 5.5 TeV for the ALICE detector at the LHC. The algorithm can reconstruct jets with a transverse energy of 50 GeV and above with an energy resolution of {approx} 30%.

  11. Entropy production and effective viscosity in heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Yu.B. [National Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation); National Research Nuclear University ' ' MEPhI' ' (Moscow Engineering Physics Institute), Moscow (Russian Federation); Soldatov, A.A. [National Research Nuclear University ' ' MEPhI' ' (Moscow Engineering Physics Institute), Moscow (Russian Federation)

    2016-12-15

    The entropy production and an effective viscosity in central Au+Au collisions are estimated in a wide range of incident energies 3.3 GeV ≤ √(s{sub NN}) ≤ 39 GeV. The simulations are performed within a three-fluid model employing three different equations of state with and without deconfinement transition, which are equally good in the reproduction of the momentum-integrated elliptic flow of charged particles in the considered energy range. It is found that more than 80% entropy is produced during a short early collision stage which lasts ∝ 1 fm/c at the highest considered energies √(s{sub NN}) >or similar 20 GeV. The estimated values of the viscosity-to-entropy ratio (η/s) are approximately the same in all considered scenarios. At the final stages of the system expansion they range from ∝ 0.05 at the highest considered energies to ∝ 0.5 at the lowest ones. It is found that the η/s ratio decreases with the temperature (T) rise, approximately as ∝ 1/T{sup 4}, and exhibits a rather weak dependence on the net-baryon density. (orig.)

  12. Highly Charged Ion -- Molecule Collisions: a probe and a tool for studying complex systems

    Science.gov (United States)

    Adoui, L.; Rousseau, P.; Capron, M.; Maisonny, R.; Lawicki, A.; Domaracka, A.; Manil, B.; Mery, A.; Poully, J.-C.; Rangama, J.; Huber, B. A.; Lattouf, E.; Zettergren, H.; Johansson, H. A. B.; Seitz, F.; Rosen, S.; Schmidt, H. T.; Holm, A. I. S.; Cederquist, H.; Bari, S.; Hoekstra, R.; Schlatholter, T.; Alvarado, F.; Postma, J.

    2011-05-01

    It has already been demonstrated that collision with low energy Highly Charged Ions (HCI) provide a soft and efficient way to study the stability of complex systems. Indeed, such ions are known to remove electrons at large impact parameters resulting in a fast and gentle ionisation. We will present at this conference the different applications of these ions as: - they can be used to enlighten collision mechanisms viacompleteexperiments on fragmentation dynamics of small molecules; - they can act as a probe of the stability of the resulting charged species. We will illustrate this feature in the case of molecular clusters (for example in the case of Polycyclic Aromatic Hydrocarbons); - they can also be used, in a less conventional way, as a tool to form new bonds and induce the formation of even more complex molecules. Perspectives of this work will be discussed at the conference.

  13. Head-on collision of ion-acoustic solitary waves in multicomponent plasmas with positrons

    Science.gov (United States)

    El-Shamy, E. F.; Sabry, R.; Moslem, W. M.; Shukla, P. K.

    2010-08-01

    The head-on collision between two ion-acoustic solitary waves in an unmagnetized multicomponent plasma consisting of hot ions, hot positrons, and two-electron temperature distributions is investigated using the extended Poincaré-Lighthill-Kuo method. The Kortwege-de Vries equations and the analytical phase shifts after the head-on collision of two solitary waves in this multicomponent plasma are obtained. The effects of two different types of isothermal electrons, the ratio of the hot ion temperature to the effective temperature, the ratio of the effective temperature to the positron temperature, the ratio of the number density of positrons to that of electrons species, and the physical processes (either isothermal or adiabatic) on the phase shifts are studied. It is found that these parameters can significantly influence the phase shifts of the solitons. The relevance of this investigation to space and laboratory plasmas is pointed out.

  14. Coulomb excitation of highly charged projectile ions in relativistic collisions with diatomic molecules

    International Nuclear Information System (INIS)

    Artemyev, A. N.; McConnell, S. R.; Surzhykov, A.; Najjari, B.; Voitkiv, A. B.

    2011-01-01

    We investigate the Coulomb excitation of highly charged ions colliding with diatomic molecules. In this process, the coherent interaction between the projectile electron and two molecular centers may cause clear interference patterns in the (collision) energy dependencies of the total cross sections and alignment parameters. We discuss such a Young-type interference for the particular case of the K→L excitation of hydrogen- and helium-like projectile ions. Calculations, performed for the scattering of these ions on nitrogen molecules, indicate that the interference effects are extremely sensitive to the collisional geometry and are pronounced only if the molecular axis is aligned almost parallel to the incident beam trajectory.

  15. Charge-exchange collisions of multiply charged ions with atoms

    International Nuclear Information System (INIS)

    Grozdanov, T.P.; Janev, R.K.

    1978-01-01

    The problem of electron transfer between neutral atoms and multiply charged ions is considered at low and medium energies. It is assumed that a large number of final states are available for the electron transition so that the electron-capture process is treated as a tunnel effect caused by the strong attractive Coulomb field of the multicharged ions. The electron transition probability is obtained in a closed form using the modified-comparison-equation method to solve the Schroedinger equation. An approximately linear dependence of the one-electron transfer cross section on the charge of multicharged ion is found. Cross-section calculations of a number of charge-exchange reactions are performed

  16. Nucleon exchange as a mechanism for strongly damped heavy ion collisions

    International Nuclear Information System (INIS)

    Jain, A.K.; Sarma, N.

    1978-01-01

    The strongly damped collisions of two heavy ions are examined in a semi-classical model where nucleons migrating across a boundary between the nuclei are captured by the other nucleus. The density variation of nucleons is taken to be the two-parameter Fermi distribution and the Thomas-Fermi model is invoked to obtain their momentum distribution. The mass exchanged during collisions, the net mass transfer and the energy lost to internal excitation are calculated as a function of the impact parameter. The angle of deep inelastic scattering is computed by correcting the elastic scattering deflection function. (Auth.)

  17. Fast Heavy Ion Collisions with H2 Molecules And Young Type Interference

    Science.gov (United States)

    Tribedi, Lokesh C.; Misra, Deepankar

    2007-12-01

    We have investigated the Young type interference effect in electron emission spectrum from molecular H2 in Coulomb ionization induced by fast heavy ions. The details of the derivation of the oscillations due to this process from the electron double differential distributions are discussed. In addition, we have explored the effect of Compton profile, on such interference oscillations, which gives rise a double-peak structure in case of low energy collisions for which the binary encounter peak starts overlapping with soft collision electrons. The measured DDCS as well as the interference patterns are compared with molecular CDW-EIS models.

  18. Probing in-medium spin–orbit interaction with intermediate-energy heavy-ion collisions

    International Nuclear Information System (INIS)

    Xu, Jun; Li, Bao-An

    2013-01-01

    Incorporating for the first time both the spin and isospin degrees of freedom explicitly in transport model simulations of intermediate-energy heavy-ion collisions, we observe that a local spin polarization appears during collision process. Most interestingly, it is found that the nucleon spin up–down differential transverse flow is a sensitive probe of the spin–orbit interaction, providing a novel approach to probe both the density and isospin dependence of the in-medium spin–orbit coupling that is important for understanding the structure of rare isotopes and synthesis of superheavy elements

  19. Hydrodynamic radial and elliptic flow in heavy-ion collisions from AGS to LHC energies

    CERN Document Server

    Kestin, Gregory

    2009-01-01

    Using ideal relativistic hydrodynamics in 2+1 dimensions, we study the collision energy dependence of radial and elliptic flow, of the emitted hadron spectra, and of the transverse momentum dependence of several hadronic particle ratios, covering the range from Alternating Gradient Synchrotron (AGS) to Large Hadron Collider (LHC) energies. These calculations establish an ideal fluid dynamic baseline that can be used to assess non-equilibrium features manifest in future LHC heavy-ion experiments. Contrary to earlier suggestions we find that a saturation and even decrease of the differential elliptic flow v_2(p_T) with increasing collision energy cannot be unambiguously associated with the QCD phase transition.

  20. Nuclear fragmentation energy and momentum transfer distributions in relativistic heavy-ion collisions

    Science.gov (United States)

    Khandelwal, Govind S.; Khan, Ferdous

    1989-01-01

    An optical model description of energy and momentum transfer in relativistic heavy-ion collisions, based upon composite particle multiple scattering theory, is presented. Transverse and longitudinal momentum transfers to the projectile are shown to arise from the real and absorptive part of the optical potential, respectively. Comparisons of fragment momentum distribution observables with experiments are made and trends outlined based on our knowledge of the underlying nucleon-nucleon interaction. Corrections to the above calculations are discussed. Finally, use of the model as a tool for estimating collision impact parameters is indicated.

  1. Anisotropic flow fluctuations in hydro-inspired freeze-out model for relativistic heavy ion collisions

    CERN Document Server

    Bravina, L V; Korotkikh, V L; Lokhtin, I P; Malinina, L V; Nazarova, E N; Petrushanko, S V; Snigirev, A M; Zabrodin, E E

    2015-01-01

    The possible mechanisms contributing to anisotropic flow fluctuations in relativistic heavy ion collisions are discussed. The LHC data on event-by-event harmonic flow coefficients measured in PbPb collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted within the HYDJET++ model. To compare the model results with the experimental data the unfolding procedure is employed. It is shown that HYDJET++ correctly reproduces dynamical fluctuations of elliptic and triangular flows and related to it eccentricity fluctuations of the initial state.

  2. Electron collisions with atoms, ions, molecules, and surfaces: Fundamental science empowering advances in technology

    Science.gov (United States)

    Bartschat, Klaus; Kushner, Mark J.

    2016-06-01

    Electron collisions with atoms, ions, molecules, and surfaces are critically important to the understanding and modeling of low-temperature plasmas (LTPs), and so in the development of technologies based on LTPs. Recent progress in obtaining experimental benchmark data and the development of highly sophisticated computational methods is highlighted. With the cesium-based diode-pumped alkali laser and remote plasma etching of Si3N4 as examples, we demonstrate how accurate and comprehensive datasets for electron collisions enable complex modeling of plasma-using technologies that empower our high-technology-based society.

  3. Funny hills in pion spectra from heavy-ion collisions

    International Nuclear Information System (INIS)

    Rasmussen, J.O.

    1982-03-01

    A discussion of some of the systematic features of the pion spectra in heavy-ions reactions is given. A discussion of the hills and valleys in heavy ion pion spectra that show up at the lower pion energies is given. The following topics are discussed: (1) three kinds of funny hills; (2) π - / + ratios near center of mass; (3) new Monte Carlo studies of charged pion spectra; and (4) pion orbiting about fireballs and Bose-Einstein behavior as explanation for the mid-rapidity P/sub perpendicular to/ approx. = 0.4 to 0.5 m/sub π/c hill

  4. Exotic charmed baryon production in ultrarelativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Zimanyi, J.; Biro, T.S.; Levai, P.

    1993-01-01

    The authors investigate multi-heavy baryon formation in Au + Au collision using an extended version of the combinatoric break up model for rehadronization. A penalty factor, p, is introduced to characterize the coalescence probability of a light quark with a heavy one. At LHC energy large production rate is found for certain multi-heavy baryons and mesons such as Ω ccc , Ξ cc , J/Ψ and suppression for Λ c , D. They speculate also on the possible existence of a heavy bottom-charm six-quark baryon. A semiclassical and a gaussian estimate reveal that the octet-octet bbb-cc configuration can be energetically favored with respect to the singlet-singlet one

  5. Baryon femtoscopy in heavy-ion collisions at ALICE

    CERN Document Server

    Szymański, Maciej Pawel

    2014-01-01

    In this report, femtoscopic measurements with proton-proton, antiproton-antiproton, proton-antiproton, proton-antilambda, antiproton-lambda and lambda-antilambda pairs in Pb-Pb collisions at sqrt(s_NN)=2.76 TeV registered by ALICE at the LHC are presented. Emission source sizes extracted from the correlation analysis with (anti)protons grow with the event multiplicity, as expected. A method to extract the interaction potentials (e.g. for proton-antilambda and antiproton-lambda pairs) based on femtoscopy analysis is discussed. The importance of taking into account the so-called residual correlations induced by pairs contaminated by secondary particles is emphasized for all analyses mentioned above.

  6. Photon emission spectroscopy of ion-atom collisions

    International Nuclear Information System (INIS)

    Nystroem, B.

    1995-10-01

    Emission cross sections for the 1snp 1 P 1 -levels have been measured by photon emission spectroscopy for the collision systems He + + He at 10 keV and He 2+ + He at 10-35 keV. Photon spectra of Krypton (Kr VIII) and Xenon (Xe V - IX) have also been obtained using 10q keV beams of Kr q+ (q=7-9) and Xe q+ (q=5-9) colliding with Helium and Argon. The Lifetimes of 3p 2 P-levels in Na-like Nb are reported together with lifetime for the 3s3p 3 P 1 -level in Mg-like Ni, Kr, Y, Zr and Nb where this level has an intercombination transition to the ground state. 45 refs, 20 figs

  7. Photon emission spectroscopy of ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Nystroem, B.

    1995-10-01

    Emission cross sections for the 1snp{sup 1}P{sub 1}-levels have been measured by photon emission spectroscopy for the collision systems He{sup +} + He at 10 keV and He{sup 2+} + He at 10-35 keV. Photon spectra of Krypton (Kr VIII) and Xenon (Xe V - IX) have also been obtained using 10q keV beams of Kr{sup q+} (q=7-9) and Xe{sup q+} (q=5-9) colliding with Helium and Argon. The Lifetimes of 3p{sup 2}P-levels in Na-like Nb are reported together with lifetime for the 3s3p{sup 3}P{sub 1}-level in Mg-like Ni, Kr, Y, Zr and Nb where this level has an intercombination transition to the ground state. 45 refs, 20 figs.

  8. Is there evidence for flow in heavy ion collisions?

    International Nuclear Information System (INIS)

    Von Gersdorff, H.

    1990-07-01

    Calculations using a transverse hydrodynamical model with a phase transition in the equation of state are compared to recent heavy ion data. We argue that hydrodynamics alone cannot reproduce the low p T part of the experimental spectrum. 6 refs., 2 figs

  9. Theory of heavy ion collision physics in hadron therapy

    CERN Document Server

    2013-01-01

    Advances in Quantum Chemistry presents surveys of current topics in this rapidly developing field that has emerged at the cross section of the historically established areas of mathematics, physics, chemistry, and biology. It features detailed reviews written by leading international researchers. This volume focuses on the theory of heavy ion physics in medicine.

  10. Ionic fragmentation channels in electron collisions of small molecular ions

    International Nuclear Information System (INIS)

    Hoffmann, Jens

    2009-01-01

    Dissociative Recombination (DR) is one of the most important loss processes of molecular ions in the interstellar medium (IM). Ion storage rings allow to investigate these processes under realistic conditions. At the Heidelberg test storage ring TSR a new detector system was installed within the present work in order to study the DR sub-process of ion pair formation (IPF). The new detector expands the existing electron target setup by the possibility to measure strongly deflected negative ionic fragments. At the TSR such measurements can be performed with a uniquely high energy resolution by independently merging two electron beams with the ion beam. In this work IPF of HD + , H 3 + and HF + has been studied. In the case of HD + the result of the high resolution experiment shows quantum interferences. Analysis of the quantum oscillations leads to a new understanding of the reaction dynamics. For H 3 + it was for the first time possible to distinguish different IPF channels and to detect quantum interferences in the data. Finally the IPF of HF + was investigated in an energy range, where in previous experiments no conclusive results could be obtained. (orig.)

  11. Fragmentation and momentum correlations in heavy-ion collisions

    Indian Academy of Sciences (India)

    The role of momentum correlations in the production of light and medium mass frag- ments is studied by imposing momentum cut ... Sakshi Gautam and Rajni Kant is very dilute. But, the fragments ... We describe the time evolution of a heavy-ion reaction within the framework of quantum molecular dynamics (QMD) model [2 ...

  12. Pion production in high energy heavy ion collisions

    International Nuclear Information System (INIS)

    Wolf, K.L.; Bock, R.; Brockmann, R.

    1984-01-01

    Experimental data for heavy ion pion production reactions are compared with the predictions of a number of versions of cascade models. Pion suppression effects observed in the experimental data are fit by introducing refinements into cascade theory. Impact parameter adjustment, off-shell effects on the potential and perturbations due to nuclear matter are considered

  13. Collective flow in relativistic heavy-ion collisions

    Indian Academy of Sciences (India)

    A brief introduction is given to the field of collective flow, currently being investigated experimentally at the Relativistic Heavy-Ion Collider, Brookhaven National Laboratory. It is followed by an outline of the work that I have been doing in this field, in collaboration with Nicolas Borghini and Jean-Yves Ollitrault.

  14. Selective electron capture into slow highly ionized recoil atoms produced in heavy ion-atom collisions

    International Nuclear Information System (INIS)

    Beyer, H.F.; Folkmann, F.; Mann, R.; Schartner, K.-H.

    1979-01-01

    The first experimental observation of the selective electron capture of slow highly ionized neon ions in the collisions with various gases is described. The slow neon ions were produced in the collision of fast heavy ions Pb 36+ , accelerated to the specific energy of 1.4 MeV/amu. X-ray spectroscopy and Auger-electron spectroscopy were applied to study the selective electron capture into higher shells. The measured spectra showed that the very heavy projectiles of 1.4 MeV/amu specific energy were likely to remove more than six electrons of the L-shell from light target atoms in a single collision. The electron capture from surrounding neutral target atoms into the outer shells of metastable highly charged recoil ions was observed. The capture process is discriminated from direct excitation because outer shells are selectively populated. A simple two center, one electron model was proposed which allows the calculation of principal quantum number and of capture radius. (Kato, T.)

  15. Molecular growth in clusters of polycyclic aromatic hydrocarbons induced by collisions with ions

    International Nuclear Information System (INIS)

    Delaunay, Rudy

    2016-01-01

    This thesis concerns the experimental study of the interaction between low energy ions (keV range) and neutral isolated molecules or clusters of polycyclic aromatic hydrocarbons (PAH) in the gas phase. The use of ionising radiations on these complex molecular systems of astrophysical interest allowed to highlight processes of statistical fragmentation, corresponding to the redistribution of the energy through the degrees of freedom of the target, and non-statistical fragmentation, linked to binary collisions of the ions on the nuclei of the target. A mechanism of intermolecular growth in clusters of PAH is observed. It is associated to the ultrafast (≤ ps) formation of fragments inside the clusters following binary collisions. The presence of a molecular environment around the fragments formed during the interaction may initiate a process of reactivity between the fragments and the molecules of the clusters. More precisely, the study focusses on the importance of the electronic stopping power SE and the nuclear stopping power SN of the projectile ion. It shows that the molecular growth is enhanced when SN is higher than SE. This can be explained by the fact that the deposit of energy is mainly due to the interaction with the nuclei of the target. The process of growth has been observed for all the molecules of PAH studied during this thesis and also for nitrogenated analogues of the molecule of anthracene. This demonstrates that molecular growth may be efficiently induced by collisions of low energy ions with clusters of PAH. (author) [fr

  16. Charged Particle Multiplicity and Open Heavy Flavor Physics in Relativistic Heavy Ion Collisions at the LHC

    Science.gov (United States)

    Chen, Yujiao

    RAA, which is defined as the ratio of a spectrum from heavy ion collisions to the same but scaled spectrum from nucleon-nucleon collisions. The observed RAA has little dependence on pT within the uncertainties quoted here. The results for RAA indicate a factor of about 3 suppression in the yield of muons in the most central (0-10%) collisions compared to the p+p collisions.

  17. Jet measurements in heavy-ion collisions with the ATLAS detector

    CERN Document Server

    Havener, Laura Brittany; The ATLAS collaboration

    2017-01-01

    In relativistic heavy-ion collisions, a hot medium with a high density of unscreened colour charges is produced. Jets are produced by parton-parton scatterings in the early stages of the collision, and are observed to be attenuated as they propagate through the hot matter. One manifestation of this energy loss is a lower yield of jets emerging from the medium than expected in the absence of medium effects. Another manifestation of energy loss is the modification of both dijet transverse energy balance, and a similar modification of photon-jet correlations. Finally, the internal structure of jets is also observed to be modified, from a careful study of fragmentation functions. In this talk, the latest ATLAS results on single jet suppression, dijet suppression, photon-jet correlations, and modification of the jet internal structure in both p+Pb and Pb+Pb collisions, compared to pp, will be presented.

  18. Coherent Bremsstrahlung emission in the early stage of relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Bertulani, C.; Mornas, L.; Ornik, U.

    1994-12-01

    We present a model of coherent Bremsstrahlung emission from the compression phase of relativistic heavy ion collisions based on a hydrodynamical description of the collision process. The deceleration of the matter through a shock front, calculated in 1-D relativistic dissipative hydrodynamics, is at the origin of a copious Bremsstrahlung emission. The interferences between the Bremsstrahlung emitted by two receeding shock fronts result in deviations from the usual 1/ω law, with in particular a strong suppression of low energy photons in symmetric collisions. We show how it might be possible to obtain information on the equation of state, possible transition to a quark gluon plasma and dynamical properties of the matter from the study of the interference pattern. We show that the optimal region for the observation of coherent photons is in SIS-AGS energy range. (orig.)

  19. b-jet tagged nuclear modification factors in heavy ion collisions with CMS

    CERN Document Server

    Jung, Kurt

    2014-01-01

    The energy loss of jets in heavy-ion collisions is expected to depend on the flavor of the fragmenting parton. Thus, measurements of jet quenching as a function of flavor place powerful constraints on the thermodynamical and transport properties of the hot and dense medium. Measurements of the nuclear modification factors of the heavy-flavor-tagged jets in both PbPb and pPb collisions can quantify such energy loss effects. Specifically, pPb measurements provide crucial insights into the behavior of the cold nuclear matter effect, which is required to fully understand the hot and dense medium effects on jets in PbPb collisions. In this talk, we present the b-jet spectra and the first measurement of the nuclear modification factors as a function of transverse momentum and pseudorapidity, using the high statistics pp, pPb and PbPb data taken in 2011 and 2013.

  20. {gamma}-radiation of excited nuclear discrete levels in peripheral heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Korotkikh, V.L.; Chikin, K.A. [Scobeltsyn Institute of Nuclear Physics, Moscow State University (Russian Federation)

    2002-06-01

    A new process of a nuclear excitation to discrete states in peripheral heavy ion collisions is studied. High-energy photons are emitted by the exited nuclei with energies up to a few tens of GeV at angles of a few hundred microradians with respect to the beam direction. We show that a two-stage process, where an electron-positron pair is produced by virtual photons emitted by nuclei and then the electron or positron excites the nucleus, has a large cross-section. It is equal to about 5 b for CaCa collisions. On the one hand, it produces a significant {gamma}-rays background in the nuclear fragmentation region but, on the other hand, it could be used for monitoring the nuclear beam intensity at the LHC. These secondary nuclear photons could be a good signal for triggering peripheral nuclear collisions. (orig.)

  1. γ-radiation of excited nuclear discrete levels in peripheral heavy ion collisions

    Science.gov (United States)

    Korotkikh, V. L.; Chikin, K. A.

    A new process of a nuclear excitation to discrete states in peripheral heavy ion collisions is studied. High-energy photons are emitted by the exited nuclei with energies up to a few tens of GeV at angles of a few hundred microradians with respect to the beam direction. We show that a two-stage process, where an electron-positron pair is produced by virtual photons emitted by nuclei and then the electron or positron excites the nucleus, has a large cross-section. It is equal to about 5 b for CaCa collisions. On the one hand, it produces a significant γ-rays background in the nuclear fragmentation region but, on the other hand, it could be used for monitoring the nuclear beam intensity at the LHC. These secondary nuclear photons could be a good signal for triggering peripheral nuclear collisions.

  2. γ-radiation of excited nuclear discrete levels in peripheral heavy ion collisions

    International Nuclear Information System (INIS)

    Korotkikh, V.L.; Chikin, K.A.

    2002-01-01

    A new process of a nuclear excitation to discrete states in peripheral heavy ion collisions is studied. High-energy photons are emitted by the exited nuclei with energies up to a few tens of GeV at angles of a few hundred microradians with respect to the beam direction. We show that a two-stage process, where an electron-positron pair is produced by virtual photons emitted by nuclei and then the electron or positron excites the nucleus, has a large cross-section. It is equal to about 5 b for CaCa collisions. On the one hand, it produces a significant γ-rays background in the nuclear fragmentation region but, on the other hand, it could be used for monitoring the nuclear beam intensity at the LHC. These secondary nuclear photons could be a good signal for triggering peripheral nuclear collisions. (orig.)

  3. Jet quenching and γ-jet correlation in high-energy heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin-Nian [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Nuclear Science Division Mailstop 70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94740 (United States); Zhu, Yan [Departamento de Física de Partículas and IGFAE, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Galicia (Spain)

    2014-12-15

    Medium modification of γ-tagged jets in high-energy heavy-ion collisions is investigated within a linearized Boltzmann transport model which includes both elastic parton scattering and induced gluon emission. In Pb + Pb collisions at √(s)=2.76 TeV, a γ-tagged jet is seen to lose 15% of its energy at 0–10% central collisions. Simulations also point to a sizable azimuthal angle broadening of γ-tagged jets at the tail of a distribution which should be measurable when experimental errors are significantly reduced. An enhancement at large z{sub jet}=p{sub L}/E{sub jet} in jet fragmentation function at the Large Hadron Collider (LHC) can be attributed to the dominance of leading particles in the reconstructed jet. A γ-tagged jet fragmentation function is shown to be more sensitive to jet quenching, therefore a better probe of the jet transport parameter.

  4. 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.

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

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  6. Light Heavy-Ion Dissipative Collisions at Low Energy

    Science.gov (United States)

    Pop, A.; Andronic, A.; Berceanu, I.; Duma, M.; Moisa, D.; Petrovici, M.; Simion, V.; Immé, G.; Lanzanó, G.; Pagano, A.; Raciti, G.; Coniglione, R.; Del Zoppo, A.; Piatelli, P.; Sapienza, P.; Colonna, N.; D'Erasmo, G.; Pantaleo, A.

    2004-09-01

    Dissipative processes have been investigated experimentally in several light heavy-ion systems, using a complex detector which has as main components two position sensitive ionization chambers. Experimental evidence and comparison with theoretical calculations suggest a mechanism similar to deep inelastic processes in heavy and medium systems, even in the case of completely damped events. Note from Publisher: This article contains the abstract and references only.

  7. Proton-ion collisions: behind the scenes of an exotic interaction

    CERN Document Server

    Antonella Del Rosso

    2012-01-01

    Protons to the right, ions to the left: the basic principle of proton-ion collisions at the LHC might seem straightforward. However, this is an almost unprecedented mode of collider operation, certainly unique at the energy provided by the LHC. In addition to being a remarkable technical achievement, this interaction between a proton and an ion can potentially contribute a lot to the understanding of the properties of matter in its primordial state.   Prior to last week, the LHC had only collided protons with protons and lead ions with lead ions. These were indeed the two operational schemes the LHC was designed for. However, since science can often evolve in directions that were not necessarily expected at the beginning of a project, over the years the scientific community has become more and more interested in the hybrid type of interaction – that between protons and ions. Last week’s collisions were only a test for the teams involved in the operation of the LHC, in prepara...

  8. Probing QCD critical fluctuations from light nuclei production in relativistic heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    Kai-Jia Sun

    2017-11-01

    Full Text Available Based on the coalescence model for light nuclei production, we show that the yield ratio Op-d-t=NH3Np/Nd2 of p, d, and 3H in heavy-ion collisions is sensitive to the neutron relative density fluctuation Δn=〈(δn2〉/〈n〉2 at kinetic freeze-out. From recent experimental data in central Pb+Pb collisions at sNN=6.3 GeV, 7.6 GeV, 8.8 GeV, 12.3 GeV and 17.3 GeV measured by the NA49 Collaboration at the CERN Super Proton Synchrotron (SPS, we find a possible non-monotonic behavior of Δn as a function of the collision energy with a peak at sNN=8.8 GeV, indicating that the density fluctuations become the largest in collisions at this energy. With the known chemical freeze-out conditions determined from the statistical model fit to experimental data, we obtain a chemical freeze-out temperature of ∼144 MeV and baryon chemical potential of ∼385 MeV at this collision energy, which are close to the critical endpoint in the QCD phase diagram predicted by various theoretical studies. Our results thus suggest the potential usefulness of the yield ratio of light nuclei in relativistic heavy-ion collisions as a direct probe of the large density fluctuations associated with the QCD critical phenomena.

  9. Correlated charge changing ion-atom collisions. Progress report, March 15, 1985-March 14, 1986

    International Nuclear Information System (INIS)

    Bernstein, E.M.; Tanis, J.A.

    1986-04-01

    X-ray emission associated with projectile charge-changing events in ion-atom collisions has been used to isolate and investigate excitation, ionization, and charge transfer, as well as combinations of these processes. New measurements were made of K-shell and L-shell resonant transfer and excitation (RTE) for 210 to 300 MeV 20 Ca/sup 10,11+/ + H 2 collisions and 230 to 610 MeV 41 Nb 31+ + H 2 collisions, respectively. Nonresonant transfer and excitation (NTE) was studied for 40 to 160 MeV S 13+ + Ne. Single-electron capture and loss measurements, requiring accel-decel techniques, were made for 2.5 to 200 MeV S 13+ on He. In the case of Ca/sup 16,17,18,19 + / + H 2 collisions the single capture cross cross sections exhibit a nonmonotonic energy dependence which we attribute to RTE. Double-electron capture in single collisions was investigated for S 13+ + He and Ne and Ar 15+ + Ne and the cross sections were found to be 10 to 100 times smaller than the single-capture cross sections. Measured two-electron loss cross sections for Ca/sup q + / ions incident on H 2 vary with charge state and depend strongly on whether L- or K-shell electrons are removed. Measurements of simultaneous projectile excitation and electron loss for several collision systems indicate that K-vacancy production occurs primarily through excitation rather than loss of the 1s electron. 13 refs

  10. Centrality dependence of strangeness enhancement in ultrarelativistic heavy ion collisions: A core-corona effect

    International Nuclear Information System (INIS)

    Aichelin, J.; Werner, K.

    2009-01-01

    In ultrarelativistic heavy ion collisions, the multiplicity of multistrange baryons per participating nucleon increases with centrality in a different fashion for different systems and energies. At RHIC, for copper+copper (CuCu) collisions the increase is much steeper than for gold-gold (AuAu) collisions. We show that this system size dependence is due to a core-corona effect: the relative importance of the corona as compared to the core (thermalized matter) contribution varies and the contribution of a corona nucleon to the multiplicity differs from that of a core nucleon. φ mesons follow--as all hadrons--the same trend, but the difference between core and corona multiplicity is relatively small, and therefore the CuCu and AuAu results are quite similar. This simple geometrical explanation makes also a strong case in favor of the validity of Glauber geometry in the peripheral regions of ultrarelativistic heavy ion collisions, which is crucial for understanding the early evolution of the system.

  11. New results on Coulomb effects in meson production in relativistic heavy ion collisions

    Directory of Open Access Journals (Sweden)

    Rybicki Andrzej

    2014-01-01

    Full Text Available We propose a new method of investigating the space-time evolution of meson production in heavy ion collisions, by making use of spectator-induced electromagnetic (“Coulomb” effects. The presence of two nuclear remnants (“spectator systems” in the non-central collision generates a strong Coulomb field, which modifies the trajectories of charged final state hadrons. This results in charge-dependent azimuthal anisotropies in final state meson emission. In our approach, this effect can be computed numerically by means of a high-statistics Monte Carlo simulation, using the distance between the meson formation zone and the spectator system as free parameter. Our simulation correctly describes the electromagnetic effect on azimuthal anisotropies observed for π+ and π−mesons in Au+Au collisions at lower RHIC energy, known from data recently reported by the STAR Collaboration. Similarly to our earlier studies of spectator-induced electromagnetic effects, also in the present study we find that these effects offer sensitivity to the position of the meson formation zone with respect to the spectator system. Therefore, we conclude that they can serve as a new tool to investigate the space-time evolution of meson production, and the dynamics of the heavy ion collision.

  12. 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...

  13. Head-on collisions of electrostatic solitons in multi-ion plasmas

    International Nuclear Information System (INIS)

    Verheest, Frank; Hellberg, Manfred A.; Hereman, Willy A.

    2012-01-01

    Head-on collisions between two electrostatic solitons are dealt with by the Poincaré-Lighthill-Kuo method of strained coordinates, for a plasma composed of a number of cold (positive and negative) ion species and Boltzmann electrons. The nonlinear evolution equations for both solitons and their phase shift due to the collision, resulting in time delays, are established. A Korteweg-de Vries description is the generic conclusion, except when the plasma composition is special enough to replace the quadratic by a cubic nonlinearity in the evolution equations, with concomitant repercussions on the phase shifts. Applications include different two-ion plasmas, showing positive or negative polarity solitons in the generic case. At critical composition, a combination of a positive and a negative polarity soliton is possible.

  14. Jet Reconstruction with Particle Flow in Heavy-Ion Collisions with CMS

    CERN Document Server

    INSPIRE-00242647

    2011-01-01

    In the particle-flow approach information from all available sub-detector systems is combined to reconstruct all stable particles. The global event reconstruction has been shown to improve, in particular, the resolution of jets and missing transverse energy in pp collisions compared to purely calorimetric measurements. This improvement is achieved primarily by combining the precise momentum determination of charged hadrons in the silicon tracker with the associated energy depositions in the calorimeters. By resolving individual particles inside jets, particle flow reduces the sensitivity of the jet energy scale to the jet fragmentation pattern, which is known to be one of the largest sources of systematic uncertainty in jet reconstruction. Particle flow reconstruction is thus potentially well-suited for the study of potential modifications to jet fragmentation in heavy-ion collisions. The particle flow algorithm has been adapted to the heavy-ion environment. The performance of jet reconstruction from particle...

  15. Jet Reconstruction with Particle Flow in Heavy-Ion Collisions with CMS

    CERN Document Server

    Nguyen, Matthew

    2011-01-01

    In the particle-flow approach information from all available sub-detector systems is combined to reconstruct all stable particles. The global event reconstruction has been shown to improve, in particular, the resolution of jets and missing transverse energy in $pp$ collisions compared to purely calorimetric measurements. This improvement is achieved primarily by combining the precise momentum determination of charged hadrons in the silicon tracker with the associated energy depositions in the calorimeters. By resolving individual particles inside jets, particle flow reduces the sensitivity of the jet energy scale to the jet fragmentation pattern, which is known to be one of the largest sources of systematic uncertainty in jet reconstruction. Particle flow reconstruction is thus potentially well-suited for the study of potential modifications to jet fragmentation in heavy-ion collisions. The particle flow algorithm has been adapted to the heavy-ion environment. The performance of jet reconstruction from parti...

  16. Heavy ions collisions and the site-bond percolation

    International Nuclear Information System (INIS)

    Desbois, J.

    1986-07-01

    Site-bond percolation on a lattice is used for the investigation of heavy ions reactions. A model characterized by two parameters, p and q, is worked out and a critical zone in the p-q plane is shown up. Analytical expressions for various quantities concerning percolation and evaporation are established. Calculations of energy spectra, linear momentum transfer, fragment multiplicities and mass yields at various bombarding energies are compared with experimental data. Different possibilities for the attainment of the multifragmentation regime are discussed. 17 figs; 43 refs

  17. Scaling of cross sections in ion-atom collisions

    International Nuclear Information System (INIS)

    Differential electron emission at 15 degrees is investigated for 50-500 keV/amu hydrogen impacting on He and H targets. From hydrogen particles (H, H + , H 2 + , H 3 + ) ratios of cross sections relative to proton impact data, it is shown how bound projectile electrons influence the differential electron emission and where different ionization mechanisms are important. It is demonstrated that the H 2 + and H 3 + molecular ions interact as though they are composed of independent nuclei with the appropriate number of bound electrons, the electronic structure of the components appearing to be unimportant

  18. Various light particles emissions accompaning light heavy ion collisions

    International Nuclear Information System (INIS)

    Billerey, R.

    1981-01-01

    In this work we have investigated light particles emission accompanying heavy-ion induced reactions. The experiments were performed at the isochronous cyclotron of the I.S.N. de Grenoble and we got in and out of plane correlations between solid state and gazeous detectors. In 14 N (100 MeV) + 27 Al we have chosen, light particles emitted in coincidence with deep inelastic fragments or evaporation residues have been measured. Likewise we observed the correlations between fragments and fragments. The particularities we found between protons and alpha emissions are to be assigned to differences in separation energies, but their relative energies and angular momenta have also a significant part [fr

  19. The QCD Phase Diagram, Equation of State, and Heavy Ion Collisions

    OpenAIRE

    Shuryak, E. V.

    2001-01-01

    After some historic remarks and a brief summary of recent theoretical news about the QCD phases, we turn to the issue of $freeze-out$ in heavy ion collisions. We argue that the chemical freeze-out line should actually consists of two crossing lines of different nature. We also consider some inelatic reactions which occure $after$ chemical freeze-out, emphasizing the role of overpopulation of pions. The $hydrodynamics$ (with or without hadronic afterburner) explaines SPS/RHIC data on radial an...

  20. Baryonic contributions to the dilepton spectra in relativistic heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Bleicher, M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Dutt-mazumder, A. K. [McGill Univ., Montreal, QC (Canada); Gale, C. [McGill Univ., Montreal, QC (Canada); Ko, C. M. [Texas A & M Univ., College Station, TX (United States); Koch, V. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-05-09

    We investigate the baryonic contributions to the dilepton yield in high energy heavy ion collisions within the context of a transport model. The relative contribution of the baryonic and mesonic sources are examined. It is observed that most dominant among the baryonic channels is the decay of N*(1520) and mostly confined in the region below the rho peak. In a transport theory implementation we find the baryonic contribution to the lepton pair yield to be small.

  1. Observation of Global Hyperon Polarization in Ultrarelativistic Heavy-Ion Collisions

    Czech Academy of Sciences Publication Activity Database

    Upsal, I.; Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Bielčík, J.; Bielčíková, Jana; Chaloupka, P.; Federič, Pavol; Rusňák, Jan; Rusňáková, O.; Šimko, Miroslav; Šumbera, Michal; Vértési, Robert

    2017-01-01

    Roč. 967, č. 11 (2017), s. 760-763 ISSN 0375-9474 R&D Projects: GA MŠk LG15001; GA MŠk LM2015054 Institutional support: RVO:61389005 Keywords : STAR collaboration * heavy ion collision s * quark-gluon plasma Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics Impact factor: 1.916, year: 2016

  2. Electron interference in fast ion collisions with H2 and the frequency parameter

    Science.gov (United States)

    Chatterjee, S.; Misra, D.; Fainstein, P. D.; Tribedi, L. C.

    2011-06-01

    The Young-type interference effect has been investigated in electron emission from molecular hydrogen in collision of 5 MeV u- 1 F9+ ions. The double differential cross section ratios of molecular-to-atomic hydrogen exhibits oscillatory structure, which is discussed in terms of the Young-type electron interference. We have obtained the frequencies of such oscillation for different angles. A comparative study of the frequency parameter is given with early measurements performed by other groups.

  3. Low energy ion-neutral collisions. Progress report, June 1, 1985-May 31, 1986

    International Nuclear Information System (INIS)

    Leventhal, J.J.

    1985-11-01

    This report summarizes work performed within the past year. New results on energy disposal, energy conversion and energy partitioning in atomic and molecular collisions of the type that control plasma and discharge behavior were obtained in several different experiments. An experiment on positive ion formation resulting from the production of atoms in very high quantum states was completed and a detailed manuscript describing our analysis of the data submitted for publication. 1 tab

  4. Heavy-Ion Collisions and Black Holes in Anti-de-Sitter Space

    CERN Document Server

    Ellis, John R.

    1999-07-02

    Recent developments linking non-perturbative quantum gauge theories in Minkowski space to classical gravity theories in anti-de-Sitter space are reviewed at a simple level. It is suggested how these spectacular advances may be extended to discuss the quark-gluon phase transition in terms of black holes in anti-de-Sitter space, with possible relevance to heavy-ion collisions.

  5. Electromagnetic production of Higgs bosons, SUSY particles, glueballs and mesons in ultrarelativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Greiner, M.; Soff, G.

    1992-12-01

    The electromagnetic creation of various exotic particles in ultrarelativistic heavy-ion collisions is discussed. The production of intermediate mass Higgs bosons of the minimal supersymmetric extension of the Standard Model is enhanced over the Standard Model Higgs boson formation for certain model parameter choices and as a consequence might be detectable at LCH and SSC. We also investigate the electromagnetic generation of supersymmetric fermions and bosons as well as glueballs, mesons and fermions. (orig.)

  6. Negative ion formation in collisions involving excited alkali atoms

    International Nuclear Information System (INIS)

    Cheret, M.

    1988-01-01

    Ion-pair production is considered as the prototype of the crossing problem between potential energy curves. In general an alkali atom is one of the reactants the other being an halogen, hydrogen atom or molecule. Experimental results are generally analyzed in the framework of the Landau-Zener-Stuekelberg theory, ionization potential and electron affinity, being the most important parameters. In order to vary these parameters over a wide range two experimental works have been devoted to systems of excited alkali atoms colliding with ground state alkali atoms. In the first study Rb atoms are excited to various ns or nd states from Rb(5d) to Rb(9s) in a cell. The second study is devoted to the Na(3p)-Na(3s) system, in this study also the possibility of creating excited negative ions (Na - (3s3p)) has been investigated. These results are presented and analyzed. Finally further developments of the subject are suggested. 17 refs.; 8 figs.; 1 table

  7. Effect of dust ion collision on dust ion acoustic waves in the framework of damped Zakharov-Kuznetsov equation in presence of external periodic force

    Science.gov (United States)

    Kanti Das, Tushar; Ali, Rustam; Chatterjee, Prasanta

    2017-10-01

    The dynamics of dust ion acoustic waves (DIAWs) is investigated in a magnetized dusty plasma whose constituents are cold ions, superthermal electrons, and dust particles in the framework of a damped Zakharov-Kuznetsov (dZK) equation in the presence of externally applied periodic force. The dZK equation is derived employing the standard reductive perturbation technique. The effect of dust ion collision on the quasiperiodic and chaotic motion of dust ion acoustic waves is discussed. It is observed that the collision frequency νid 0 plays the role of a switching parameter from the quasiperiodic route to chaos for the DIAWs.

  8. Theory of Rapidly Oscillating Electron Angular Distributions in Slow Ion-Atom Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Macek, J.H.; Ovchinnikov, S.Y. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1501 (United States)]|[Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States)

    1998-03-01

    A general expression for the ionization amplitude in slow ion-atom collisions is derived. The expression is inverted to obtain adiabatic electronic wave functions at complex values of the internuclear distance. It is shown that beating between {sigma} and {pi} components of electronic wave functions gives rise to rapid oscillations of electron angular distributions with ion velocity v . These rapid oscillations measure the real part of that eigenvalue whose imaginary part gives the well-known Wannier exponent. {copyright} {ital 1998} {ital The American Physical Society}

  9. Measurements of inelastic collisions between homonuclear ions: Na+, K+ and Rb+

    International Nuclear Information System (INIS)

    Peart, B.; Forrest, R.A.; Dolder, K.

    1981-01-01

    Cross sections have been measured for the formation of X 2+ by collisions between X + ions (X = Na, K or Rb) with centre of mass energies between 19.3 and 87.6 keV. The results were compared with similar measurements for Li + and Cs + previously made by Peart and coworkers (J. Phys. B.; 14:1655 and 3457 (1981)), but no simple empirical or theoretical scaling law could be found to relate results for the five single-charged alkali ions. (author)

  10. FOREWORD: International Conference on Heavy Ion Collisions in the LHC Era

    Science.gov (United States)

    Arleo, Francois; Salgado, Carlos A.; Tran Thanh Van, Jean

    2013-03-01

    The International Conference on Heavy Ion Collisions in the LHC Era was held in Quy Nhon, Vietnam, on 16-20 July 2012. The series Rencontres du Vietnam, created by Jean Tran Thanh Van in 1993, consists of international meetings aimed to stimulate the development of advanced research in Vietnam and more generally in South East Asia, and to establish collaborative research networks with Western scientific communities. This conference, as the whole series, also supports the International Center for Interdisciplinary Science Education being built in Quy Nhon. The articles published in this volume present the latest results from the heavy-ion collision programs of RHIC and LHC as well as the corresponding theoretical interpretation and future perspectives. Lower energy nuclear programs were also reviewed, providing a rather complete picture of the state-of-the-art in the field. We wish to thank the sponsors of the Conference on Heavy Ion Collisions in the LHC Era: the European Research Council; Xunta de Galicia (Spain); EMMI (Germany) and Agence Nationale de la Recherche (France) François Arleo (Laboratoire d'Annecy-le-Vieux de Physique Théorique, France) Francois Arleo, Carlos A Salgado and Jean Tran Thanh Van Conference photograph

  11. Intense laser driven collision-less shock and ion acceleration in magnetized plasmas

    Science.gov (United States)

    Mima, K.; Jia, Q.; Cai, H. B.; Taguchi, T.; Nagatomo, H.; Sanz, J. R.; Honrubia, J.

    2016-05-01

    The generation of strong magnetic field with a laser driven coil has been demonstrated by many experiments. It is applicable to the magnetized fast ignition (MFI), the collision-less shock in the astrophysics and the ion shock acceleration. In this paper, the longitudinal magnetic field effect on the shock wave driven by the radiation pressure of an intense short pulse laser is investigated by theory and simulations. The transition of a laminar shock (electro static shock) to the turbulent shock (electromagnetic shock) occurs, when the external magnetic field is applied in near relativistic cut-off density plasmas. This transition leads to the enhancement of conversion of the laser energy into high energy ions. The enhancement of the conversion efficiency is important for the ion driven fast ignition and the laser driven neutron source. It is found that the total number of ions reflected by the shock increases by six time when the magnetic field is applied.

  12. Impact parameter dependence of pion ratio in probing the nuclear symmetry energy using heavy-ion collisions

    OpenAIRE

    Wei, Gao-Feng; He, Guo-Qiang; Cao, Xin-Wei; Lu, Yi-Xin

    2016-01-01

    The impact parameter dependence of \\rpi ratio is examined in heavy-ion collisions at 400MeV/nucleon within a transport model. It is shown that the sensitivity of \\rpi ratio on symmetry energy shows a transition from central to peripheral collisions, i.e., the stiffer symmetry energy leads to a larger \\rpi ratio in peripheral collisions while the softer symmetry energy always leads this ratio to be larger in central collisions. After checking the kinematic energy distribution of \\rpi ratio, we...

  13. Negative ion collisions. Progress report, April 1, 1994 - March 31, 1997

    International Nuclear Information System (INIS)

    Champion, R.L.

    1996-08-01

    During the last three years, the experimental activities have concentrated on several somewhat distinct projects. First, the author has measured total cross sections for electron detachment and charge transfer for collisions of various negative ions with atomic hydrogen and the molecular target, O 3 (ozone). The second type of gas phase experiments investigated the collisional decomposition of the molecular ion H 3 + . Specifically he has measured total cross sections for dissociation and proton transfer with an apparatus utilizing a static gas target cell. The targets include hydrogen, deuterium and the rare gases. He has extended these experiments to include D 3 + in a crossed beam configuration in order to provide a more detailed understanding of the collisional dynamics for these reactants. In the area of ion-surface collisions he has measured sputtering yields for O - and electrons arising from collisions of ions with an Al/O surface. The amount of oxygen on the surface is carefully controlled and the kinetic energy distributions of the ejected anions and electrons have been determined. He has been able to develop a theoretical model which, to a large degree, can describe the process. In a slightly speculative endeavor, he has begun investigating the role of atom-catalyzed field emission, i.e., the extent to which an unoccupied negative ion state for an atom near a surface--under the influence of a strong electric field--can serve as a stepping-stone for electron field emission. Very brief accounts of these activities will be given in this report in section 2. Detailed discussions of the experimental results and their analyses published during the contract period may be found in the following articles which have appeared in the archival literature. Copies of these publications are appended to this report as section 4

  14. Deuteron Coulomb Excitation in Peripheral Collisions with a Heavy Ion

    Science.gov (United States)

    Du, Weijie; Yin, Peng; Li, Yang; Chen, Guangyao; Zuo, Wei; Zhao, Xingbo; Vary, James P.

    2017-09-01

    We develop an ab initio time-dependent Basis Function (tBF) method to solve non-perturbative and time-dependent problems in non-relativistic quantum mechanics. As a test problem, we apply this method to the Coulomb excitation of a deuteron by an impinging heavy ion. We employ wave functions for the bound and excited states of the deuterium system based on a realistic nucleon-nucleon interaction and study the evolution of the transition probability, the r.m.s. radius and the r.m.s. momentum of the system during the scattering process. The dependencies of these quantities on the external field strength and the bombarding energy are also analyzed and compared to corresponding results obtained from first-order perturbation theory. The time evolution of both the charge and the momentum distributions is shown. This work was supported in part by the U. S. Department of Energy (DOE) under Grants No. DESC0008485 (SciDAC/NUCLEI) and DE-FG02-87ER40371. W. Zuo and P. Yin are supported by the National Natural Science Foundation of China (11435014).

  15. Introduction to fluid model for RHIC heavy ion collisions

    International Nuclear Information System (INIS)

    Muraya, Shin

    2007-01-01

    An introductory review of the fluid model which has been looked upon as the promising phenomenological model for the heavy ion scattering experiments at RHIC is presented here. Subjects are especially focused on the fundamental assumptions of the model and the decision process of the phenomenological parameters considering newcomers to hadron physics. Introduction of thermodynamical quantities, 1+1 dimension model, time-space evolution of fluid, correspondence of fluid to particles, initial condition, boundary condition and comparison of the equation of state of fluid model and that of hadron model are described. Limitation of fluid picture and the validity of the model are discussed finally. It is summarized that the present fluid model does not predict much about results in advance but gives interpretation after the event, nevertheless it reproduces much of the experimental results in natural form. It is expected that the parameter of the fluid model is to be used as the intermediate theory to relate experimental results with theory. (S. Funahashi)

  16. Magnetic effects in heavy-ion collisions at intermediate energies

    International Nuclear Information System (INIS)

    Ou Li; Li Baoan

    2011-01-01

    The time evolution and space distribution of internal electromagnetic fields in heavy-ion reactions at beam energies between 200 and 2000 MeV/nucleon are studied within an isospin-dependent Boltzmann-Uhling-Uhlenbeck transport model (ibuu11). While the magnetic field can reach about 7x10 16 G, which is significantly higher than the estimated surface magnetic field (∼1x10 15 G) of magnetars, it has almost no effect on nucleon observables because the Lorentz force is normally much weaker than the nuclear force. Very interestingly, however, the magnetic field generated by the projectilelike (targetlike) spectator has a strong focusing and defocusing effect on positive and negative pions at forward (backward) rapidities. Consequently, the differential π - /π + ratio as a function of rapidity is significantly altered by the magnetic field, whereas the total multiplicities of both positive and negative pions remain about the same. At beam energies above about 1 GeV/nucleon, while the integrated ratio of total π - to π + multiplicities is not, the differential π - /π + ratio is sensitive to the density dependence of nuclear symmetry energy E sym (ρ). Our findings suggest that magnetic effects should be carefully considered in future studies of using the differential π - /π + ratio as a probe of the E sym (ρ) at suprasaturation densities.

  17. Determination of Collision Cross Sections Using a Fourier Transform Electrostatic Linear Ion Trap Mass Spectrometer.

    Science.gov (United States)

    Dziekonski, Eric T; Johnson, Joshua T; Lee, Kenneth W; McLuckey, Scott A

    2018-02-01

    Collision cross sections (CCSs) were determined from the frequency-domain linewidths in a Fourier transform electrostatic linear ion trap. With use of an ultrahigh-vacuum precision leak valve and nitrogen gas, transients were recorded as the background pressure in the mass analyzer chamber was varied between 4× 10 -8 and 7 × 10 -7 Torr. The energetic hard-sphere ion-neutral collision model, described by Xu and coworkers, was used to relate the recorded image charge to the CCS of the molecule. In lieu of our monoisotopically isolating the mass of interest, the known relative isotopic abundances were programmed into the Lorentzian fitting algorithm such that the linewidth was extracted from a sum of Lorentzians. Although this works only if the isotopic distribution is known a priori, it prevents ion loss, preserves the high signal-to-noise ratio, and minimizes the experimental error on our homebuilt instrument. Six tetraalkylammonium cations were used to correlate the CCS measured in the electrostatic linear ion trap with that measured by drift-tube ion mobility spectrometry, for which there was an excellent correlation (R 2 ≈ 0.9999). Although the absolute CCSs derived with our method differ from those reported, the extracted linear correlation can be used to correct the raw CCS. With use of [angiotensin II] 2+ and reserpine, the corrected CCSs (334.9 ± 2.1 and 250.1 ± 0.5, respectively) were in good agreement with the reported ion mobility spectrometry CCSs (335 and 254.3, respectively). With sufficient signal-to-noise ratio, the CCSs determined are reproducible to within a fraction of a percent, comparable to the uncertainties reported on dedicated ion mobility instruments. Graphical Abstract ᅟ.

  18. Determination of Collision Cross Sections Using a Fourier Transform Electrostatic Linear Ion Trap Mass Spectrometer

    Science.gov (United States)

    Dziekonski, Eric T.; Johnson, Joshua T.; Lee, Kenneth W.; McLuckey, Scott A.

    2018-02-01

    Collision cross sections (CCSs) were determined from the frequency-domain linewidths in a Fourier transform electrostatic linear ion trap. With use of an ultrahigh-vacuum precision leak valve and nitrogen gas, transients were recorded as the background pressure in the mass analyzer chamber was varied between 4× 10-8 and 7 × 10-7 Torr. The energetic hard-sphere ion-neutral collision model, described by Xu and coworkers, was used to relate the recorded image charge to the CCS of the molecule. In lieu of our monoisotopically isolating the mass of interest, the known relative isotopic abundances were programmed into the Lorentzian fitting algorithm such that the linewidth was extracted from a sum of Lorentzians. Although this works only if the isotopic distribution is known a priori, it prevents ion loss, preserves the high signal-to-noise ratio, and minimizes the experimental error on our homebuilt instrument. Six tetraalkylammonium cations were used to correlate the CCS measured in the electrostatic linear ion trap with that measured by drift-tube ion mobility spectrometry, for which there was an excellent correlation ( R 2 ≈ 0.9999). Although the absolute CCSs derived with our method differ from those reported, the extracted linear correlation can be used to correct the raw CCS. With use of [angiotensin II]2+ and reserpine, the corrected CCSs (334.9 ± 2.1 and 250.1 ± 0.5, respectively) were in good agreement with the reported ion mobility spectrometry CCSs (335 and 254.3, respectively). With sufficient signal-to-noise ratio, the CCSs determined are reproducible to within a fraction of a percent, comparable to the uncertainties reported on dedicated ion mobility instruments.

  19. Magneto optical trap recoil ion momentum spectroscopy: application to ion-atom collisions; Couplage entre un piege magneto-optique et un spectrometre d'impulsion d'ions de recul: application aux collisions ions-atomes

    Energy Technology Data Exchange (ETDEWEB)

    Blieck, J

    2008-10-15

    {sup 87}Rb atoms have been cooled, trapped and prepared as targets for collision studies with 2 and 5 keV Na{sup +} projectiles. The physics studied deals with charge exchange processes. The active electron, which is generally the most peripheral electron of the atomic target, is transferred from the target onto the ionic projectile. The ionized target is called recoil ion. The technique used to study this physics is the MOTRIMS (Magneto Optical Trap Recoil Ion Momentum Spectroscopy) technique, which combines a magneto optical trap and a recoil ion momentum spectrometer. The spectrometer is used for the measurement of the recoil ions momentum, which gives access to all the information of the collision: the Q-value (which is the potential energy difference of the active electron on each particle) and the scattering angle of the projectile. The trap provides extremely cold targets to optimize the measurement of the momentum, and to release the latter from thermal motion. Through cinematically complete experiments, the MOTRIMS technique gives access to better resolutions on momentum measurements. Measurements of differential cross sections in initial and final capture states and in scattering angle have been done. Results obtained for differential cross sections in initial and final states show globally a good agreement with theory and an other experiment. Nevertheless, discrepancies with theory and this other experiment are shown for the measurements of doubly differential cross sections. These discrepancies are not understood yet. The particularity of the experimental setup designed and tested in this work, namely a low background noise, allows a great sensitivity to weak capture channels, and brings a technical and scientific gain compared with previous works. (author)

  20. Rotationally inelastic collisions of H2+ ions with He buffer gas: Computing cross sections and rates

    Science.gov (United States)

    Hernández Vera, Mario; Gianturco, F. A.; Wester, R.; da Silva, H.; Dulieu, O.; Schiller, S.

    2017-03-01

    We present quantum calculations for the inelastic collisions between H2+ molecules, in rotationally excited internal states, and He atoms. This work is motivated by the possibility of experiments in which the molecular ions are stored and translationally cooled in an ion trap and a He buffer gas is added for deactivation of the internal rotational population, in particular at low (cryogenic) translational temperatures. We carry out an accurate representation of the forces at play from an ab initio description of the relevant potential energy surface, with the molecular ion in its ground vibrational state, and obtain the cross sections for state-changing rotationally inelastic collisions by solving the coupled channel quantum scattering equations. The presence of hyperfine and fine structure effects in both ortho- and para-H2+ molecules is investigated and compared to the results where such a contribution is disregarded. An analysis of possible propensity rules that may predict the relative probabilities of inelastic events involving rotational state-changing is also carried out, together with the corresponding elastic cross sections from several initial rotational states. Temperature-dependent rotationally inelastic rates are then computed and discussed in terms of relative state-changing collisional efficiency under trap conditions. The results provide the essential input data for modeling different aspects of the experimental setups which can finally produce internally cold molecular ions interacting with a buffer gas.

  1. Directed Flow in Heavy-Ion Collisions and Its Implications for Astrophysics

    Directory of Open Access Journals (Sweden)

    Yuri B. Ivanov

    2017-11-01

    Full Text Available Analysis of directed flow ( v 1 of protons, antiprotons and pions in heavy-ion collisions is performed in the range of collision energies s N N = 2.7–39 GeV. Simulations have been done within a three-fluid model employing a purely hadronic equation of state (EoS and two versions of the EoS with deconfinement transitions: a first-order phase transition and a smooth crossover transition. The crossover EoS is unambiguously preferable for the description of experimental data at lower collision energies s N N ≲ 20 Gev. However, at higher collision energies s N N ≳ 20 Gev. the purely hadronic EoS again becomes advantageous. This indicates that the deconfinement EoS in the quark-gluon sector should be stiffer at high baryon densities than those used in the calculation. The latter finding is in agreement with that discussed in astrophysics in connection with existence of hybrid stars with masses up to about two solar masses.

  2. Characteristic X-ray emission in close collisions between heavy ions and atoms

    International Nuclear Information System (INIS)

    Warczak, A.

    1985-12-01

    In this paper an attempt is given to answer the question of how far the inner-shell vacancy production in very heavy ion-atom collisions is influenced by the electronic configuration of the projectile prepared prior to the collision producing the observed vacancy. The variation of this configuration has been induced by changing the primary charge state of the projectile, the target density and thickness or by inverting the collision system. It turns out from the performed analysis of the experimental data that the excitation of even most strongly bound MO's can be easily dependent on these factors which have been ignored until now, especially in discussions of the 1sσ or 2pσ vacancy production at Z UA > 130. Experiments performed for the first time with gaseous targets for such heavy systems show very convincingly the influence of the outer-shell configuration on the vacancy production in inner shells. The analysis of the data has been performed in terms of electronic transitions among MO's transiently formed during the collision. In many cases a satisfactory agreement between theoretical predictions and experiment has been achieved. (orig./HSI)

  3. Study of resonance production as a probe of heavy-ion collisions with the ALICE detector

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    Hadronic resonances provide a rich set of measurements that can be used to study the properties of ultra-relativistic heavy-ion collisions. Measurements of resonances and long-lived particles provide information about the properties of the late hadronic phase due to the presence of scattering effects that can modify resonance yields. Resonances can also be used along with long-lived hadrons to study the various mechanisms that shape particle pT spectra, including in-medium energy loss, radial flow, and recombination. Measurements of resonances in pp and p-Pb collisions serve as baselines for measurements in heavy-ion collisions, provide input for tuning QCD-inspired event generators, and aid searches for collective behavior in small systems. I will present measurements of a wide variety of hadronic resonances, including some of the most recent results presented at the Quark Matter conference. By comparing measurements of resonances with different masses, lifetimes, and quark contents in pp, p-Pb, and Pb-Pb co...

  4. Low-energy collisions of helium clusters with size-selected cobalt cluster ions

    Science.gov (United States)

    Odaka, Hideho; Ichihashi, Masahiko

    2017-04-01

    Collisions of helium clusters with size-selected cobalt cluster ions, Com+ (m ≤ 5), were studied experimentally by using a merging beam technique. The product ions, Com+Hen (cluster complexes), were mass-analyzed, and this result indicates that more than 20 helium atoms can be attached onto Com+ at the relative velocities of 103 m/s. The measured size distributions of the cluster complexes indicate that there are relatively stable complexes: Co2+Hen (n = 2, 4, 6, and 12), Co3+Hen (n = 3, 6), Co4+He4, and Co5+Hen (n = 3, 6, 8, and 10). These stabilities are explained in terms of their geometric structures. The yields of the cluster complexes were also measured as a function of the relative velocity (1 × 102-4 × 103 m/s), and this result demonstrates that the main interaction in the collision process changes with the increase of the collision energy from the electrostatic interaction, which includes the induced deformation of HeN, to the hard-sphere interaction. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80015-0

  5. Measurement of quarkonia production in heavy-ion collisions with the ATLAS detector

    CERN Document Server

    Tapia Araya, Sebastian; The ATLAS collaboration

    2017-01-01

    The suppression of heavy quarkonia states in heavy-ion collisions is a phenomenon understood as a consequence of QGP formation in the hot, dense system produced in interactions of heavy ions at high energy. In addition to hot matter effects, cold nuclear effects can play an important role in quarkonia production. Therefore, a full assessment of different physics scenarios requires detailed studies on the effects present in Pb+Pb and p+Pb collisions in comparison to the pp collisions. Results of the studies based on p+Pb data collected in 2013 and pp and Pb+Pb data collected in 2015 at the LHC by the ATLAS experiment at the centre of mass energy of 5.02 TeV allowed studying prompt and non-prompt J/ψ and ψ(2S) productions as well as Υ(nS) (n = 1, 2, 3) production via the di-muon decay final states. The results of the measurements presented as a function rapidity and transverse momentum as well as the ratios between different species and systems are presented and discussed in the talk.

  6. Lead-ion collisions: the LHC achieves a new energy record

    CERN Multimedia

    John Jowett

    2015-01-01

    After the Bevatron (Berkeley, 1954) – which broke the energy barrier of billions of electronvolts – and the Tevatron (Fermilab, 1987) – which reached a trillion electronvolts – the LHC is now reaching the peta- (quadrillion) electronvolt level with its heavy-ion collisions (see here). However, one should remember that the average energy per colliding nucleon pair, within the 1 PeV “fireball”, is 5 TeV (compared to 13 TeV in the recent proton-proton collisions).   Heavy-ion collision events from the ALICE, ATLAS, CMS and LHCb experiments. Two of the great particle accelerators of the past were named after the symbolic energy barrier that they broke. The Bevatron (for "billions of electronvolts synchrotron"), at Berkeley in 1954, was the first to break the barrier of a billion electronvolts or BeV (now known as a gigaelectronvolt or GeV) in the centre-of-mass, by a large enough margin to create the laboratory’s ...

  7. Direct processes in ion-atom collisions at intermediate and high energies

    International Nuclear Information System (INIS)

    Rodriguez Chariarse, V.D.

    1990-01-01

    This thesis deals with direct processes induced by Zp charge ion impact on one or two electron atoms and ions at intermediate energies. At a first step, a one-dimensional collision model is used in order to prove the different theoretical methods available to study collisions at such energy range, such as: perturbative and related variational principles, and distorted wave methods. The best description of both, symmetric and asymmetric collision type, is achieved by the distorted wave methods, particularly the ones using the exact impulsive wave function. As a next step, the appropriate formulations of the wave functions employed in the one-dimensional model to describe the real 3-dimensional Coulomb interaction case are examined by using the Eikonal and impulse hypothesis. In this way, the VPS and Eikonal wave functions are reviewed, and furtherly, the Eikonal form of the extended impulse wave function is derived. The Eikonal impulse approximation (EIA) is introduced. This is a distorted wave method using the Eikonal and extended impulse wave functions. The choice of the EIA prior version, i.e., the one using extended impulse wave function in the final channel for excitation is widely discussed and justified. (Author) [es

  8. Final Report for Project ``Theory of ultra-relativistic heavy-ion collisions''

    Energy Technology Data Exchange (ETDEWEB)

    Ulrich W. Heinz

    2012-11-09

    In the course of this project the Ohio State University group led by the PI, Professor Ulrich Heinz, developed a comprehensive theoretical picture of the dynamical evolution of ultra-relativistic heavy-ion collisions and of the numerous experimental observables that can be used to diagnose the evolving and short-lived hot and dense fireball created in such collisions. Starting from a qualitative understanding of the main features based on earlier research during the last decade of the twentieth century on collisions at lower energies, the group exploited newly developed theoretical tools and the stream of new high-quality data from the Relativistic Heavy Ion Collider at Brookhaven National Laboratory (which started operations in the summer of the year 2000) to arrive at an increasingly quantitative description of the experimentally observed phenomena. Work done at Ohio State University (OSU) was instrumental in the discovery during the years 2001-2003 that quark-gluon plasma (QGP) created in nuclear collisions at RHIC behaves like an almost perfect liquid with minimal viscosity. The tool of relativistic fluid dynamics for viscous liquids developed at OSU in the years 2005-2007 opened the possibility to quantitatively determine the value of the QGP viscosity empirically from experimental measurements of the collective flow patterns established in the collisions. A first quantitative extraction of the QGP shear viscosity, with controlled theoretical uncertainty estimates, was achieved during the last year of this project in 2010. OSU has paved the way for a transition of the field of relativistic heavy-ion physics from a qualitative discovery stage to a new stage of quantitative precision in the description of quark-gluon plasma properties. To gain confidence in the precision of our theoretical understanding of quark-gluon plasma dynamics, one must test it on a large set of experimentally measured observables. This achievement report demonstrates that we have, at

  9. D$^{0}$ Meson Production in Heavy Ion Collisions in CMS experiment

    CERN Document Server

    Wang, Jing

    2016-01-01

    The measurement of heavy flavour production is a powerful tool to study the properties of the high-density QCD medium created in heavy-ion collisions as heavy quarks are sensitive to the transport properties of the medium and may interact with the QCD matter differently from light quarks. In particular, the comparison between the nuclear modification factors of light and heavy flavoured particles provides insights into the expected flavour dependence of in-medium parton energy loss. With the CMS detector, the D$^{0}$ meson production is studied in pp and PbPb collisions at 2.76 and 5.02 TeV. In this talk, the nuclear modification factor of D$^{0}$ meson are presented and compared to the charged hadron nuclear modification factor and theoretical calculations.

  10. Event-shape-engineering study of charge separation in heavy-ion collisions

    Science.gov (United States)

    Wen, Fufang; Bryon, Jacob; Wen, Liwen; Wang, Gang

    2018-01-01

    Recent measurements of charge-dependent azimuthal correlations in high-energy heavy-ion collisions have indicated charge-separation signals perpendicular to the reaction plane, and have been related to the chiral magnetic effect (CME). However, the correlation signal is contaminated with the background caused by the collective motion (flow) of the collision system, and an effective approach is needed to remove the flow background from the correlation. We present a method study with simplified Monte Carlo simulations and a multi-phase transport model, and develop a scheme to reveal the true CME signal via event-shape engineering with the flow vector of the particles of interest. Supported by a grant (DE-FG02-88ER40424) from U.S. Department of Energy, Office of Nuclear Physics

  11. Neutral Kaon System in Dense Matter and Heavy-Ion Collisions

    CERN Document Server

    Amelino-Camelia, G; Amelino-Camelia, Giovanni; Kapusta, Joseph

    1999-01-01

    Above a critical matter density the propagating modes of the neutral kaon system are essentially eigenstates of strangeness, but below it they are almost complete eigenstates of CP. We estimate the real and imaginary parts of the energies of these modes and their mixing at all densities up to nuclear matter density $2\\times 10^{14}$ g/cm$^3$. In a heavy ion collision the strong interactions create eigenstates of strangeness, and these propagate adiabatically until the density has fallen to the critical value, whereupon the system undergoes a sudden transition to (near) eigenstates of CP. We estimate the critical density to be 20 g/cm$^3$, and that this density will be reached about $2\\times 10^5$ fm/c after the end of the collision.

  12. Jets and charged hadrons in heavy ion collisions with the ATLAS detector

    CERN Document Server

    Santos, Helena; The ATLAS collaboration

    2017-01-01

    Ultrarelativistic heavy ion collisions at the LHC produce the Quark Gluon Plasma. Jets are a useful probe to study this state of matter since they are produced at the early stages of the collisions and are expected to be modified as propagating through the medium. One observable is the energy loss lowering the jet yields at a given transverse momentum. Other observables are the modification of the dijet momentum balance and the modification of fragmentation functions. A phenomenon strictly correlated to the jet energy loss is the modification of the charged-hadron momentum spectrum. The large new \\PbPb data sample collected by ATLAS in Run 2 allows precision measurements of these observables in a wide transverse momentum range and in different centrality and rapidity intervals.

  13. Jets and charged hadrons in heavy ion collisions with the ATLAS detector

    CERN Document Server

    Santos, Helena; The ATLAS collaboration

    2017-01-01

    Ultrarelativistic heavy ion collisions at the LHC produce the Quark Gluon Plasma. Jets are a useful probe to study this state of matter as they are produced at the early stages of the collisions and are expected to be modified as propagating through the medium. One observable is the energy loss lowering the jet yields at a given transverse momentum. Other observables are the modification of the dijet momentum balance and the modification of fragmentation functions. A phenomenon strictly correlated to the jet energy loss is the modification of the charged-hadron momentum spectrum. The large new Pb+Pb data sample collected by ATLAS in Run 2 allows precision measurements of these observables in a wide transverse momentum range and in different centrality and rapidity intervals.

  14. Langevin dynamics of heavy flavors in relativistic heavy-ion collisions

    CERN Document Server

    Alberico, W M; De Pace, A; Molinari, A; Monteno, M; Nardi, M; Prino, F

    2011-01-01

    We study the stochastic dynamics of c and b quarks, produced in hard initial processes, in the hot medium created after the collision of two relativistic heavy ions. This is done through the numerical solution of the relativistic Langevin equation. The latter requires the knowledge of the friction and diffusion coefficients, whose microscopic evaluation is performed treating separately the contribution of soft and hard collisions. The evolution of the background medium is described by ideal/viscous hydrodynamics. Below the critical temperature the heavy quarks are converted into hadrons, whose semileptonic decays provide single-electron spectra to be compared with the current experimental data measured at RHIC. We focus on the nuclear modification factor R_AA and on the elliptic-flow coefficient v_2, getting, for sufficiently large p_T, a reasonable agreement.

  15. Fluctuations of the initial color fields in high-energy heavy-ion collisions

    Science.gov (United States)

    Epelbaum, Thomas; Gelis, François

    2013-10-01

    In the color glass condensate approach to the description of high-energy heavy-ion collisions, one needs to superimpose small random Gaussian distributed fluctuations to the classical background field in order to resum the leading secular terms that result from the Weibel instability, which would otherwise lead to pathological results beyond leading order. In practical numerical simulations, one needs to know this spectrum of fluctuations at a proper time τ≪Qs-1 shortly after the collision, in the Fock-Schwinger gauge Aτ=0. In this paper, we derive these fluctuations from first principles by solving the Yang-Mills equations linearized around the classical background, with plane wave initial conditions in the remote past. We perform the intermediate steps in light-cone gauge, and we convert the results to the Fock-Schwinger gauge at the end. We obtain simple and explicit formulas for the fluctuation modes.

  16. A viscous blast-wave model for high energy heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    Jaiswal Amaresh

    2016-01-01

    Full Text Available Employing a viscosity-based survival scale for initial geometrical perturbations formed in relativistic heavy-ion collisions, we model the radial flow velocity at freeze-out. Subsequently, we use the Cooper-Frye freeze-out prescription, with viscous corrections to the distribution function, to extract the transverse momentum dependence of particle yields and flow harmonics. We fit the model parameters for central collisions, by fitting the spectra of identified particles at the Large Hadron Collider (LHC, and estimate them for other centralities using simple hydrodynamic relations. We use the results of Monte Carlo Glauber model for initial eccentricities. We demonstrate that this improved viscous blast-wave model leads to good agreement with transverse momentum distribution of elliptic and triangular flow for all centralities and estimate the shear viscosity to entropy density ratio η/s ≃ 0.24 at the LHC.

  17. Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Mehtar-Tani, Yacine [Institute of Nuclear Theory, University of Washington,Seattle, WA 98195-1550 (United States); Tywoniuk, Konrad [Theoretical Physics Department, CERN,1211 Geneva 23 (Switzerland)

    2017-04-21

    We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the “soft drop declustering” procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

  18. Principal component analysis of the nonlinear coupling of harmonic modes in heavy-ion collisions

    Science.gov (United States)

    BoŻek, Piotr

    2018-03-01

    The principal component analysis of flow correlations in heavy-ion collisions is studied. The correlation matrix of harmonic flow is generalized to correlations involving several different flow vectors. The method can be applied to study the nonlinear coupling between different harmonic modes in a double differential way in transverse momentum or pseudorapidity. The procedure is illustrated with results from the hydrodynamic model applied to Pb + Pb collisions at √{sN N}=2760 GeV. Three examples of generalized correlations matrices in transverse momentum are constructed corresponding to the coupling of v22 and v4, of v2v3 and v5, or of v23,v33 , and v6. The principal component decomposition is applied to the correlation matrices and the dominant modes are calculated.

  19. Multichannel approach to the Glauber model for heavy-ion collisions

    International Nuclear Information System (INIS)

    Lenzi, S.M.; Zardi, F.; Vitturi, A.

    1990-01-01

    A formalism is developed in order to describe, within the Glauber model, the scattering processes between heavy ions in situations involving several coupled channels. The approach is based on a suitable truncation of the number of nuclear states which can be excited at each microscopic nucleon-nucleon collision. The set of coupled equations for the S-matrix elements of the conventional reaction theory is replaced by simple matrix relations, only involving the nucleon-nucleon scattering amplitude and the nuclear densities and transition densities. This method avoids the difficulties arising from the combinatorial aspects of the multiple scattering theories, the slow convergence of the series, and the problems of center-of-mass correlations. We discuss some specific examples of multichannel collisions where the multiple-scattering series can be summed to give analytic expressions for the scattering amplitude. We finally explicate the formalism for the perturbative treatment of mutual excitation and charge-exchange processes

  20. Electron emission in energetic ion-atom collisions in the presence of coherent electromagnetic radiation

    International Nuclear Information System (INIS)

    Ciappina, M F; Madsen, L B

    2006-01-01

    We consider the effect of a low-frequency electromagnetic field on the spectra of electron emission in energetic nonrelativistic ion-atom collisions. The field is assumed to have linear polarization and to be weak compared to the typical atomic field. The incorporation of the projectile interaction opens a new scenario to the combined study of electromagnetic and atomic interactions. Our work suggests that the electromagnetic field can have a profound effect on two of the most important structures that appear in the electron emission spectra: the electron capture into the continuum and binary encounter (BE) peaks. We show that in the BE peak region the result for the laser-assisted scattering depends on the theory applied for the collision part, the first Born approximation or the distorted wave Born approximation

  1. Inclusion of the diffuseness in the schematic model of heavy ion collisions

    International Nuclear Information System (INIS)

    Marta, H.D.

    1989-01-01

    The schematic model of central heavy ion collisions developed by Swiatecki includes the Coulomb and surface contributions to the potential energy of the system and one-body dissipation. This model is extended by considering the diffuseness of the nuclear surface; this has the implication that we must consider the proximity forces in the dynamics of the collisions. For the sake of simplicity we work with symmetrical systems. The results of the model studied are compared with experimental data and with other theoretical calculations. We conclude that the detailed consideration of the diffuseness of the nuclear surfaces does not substantially change the results of the schematic model for sharp surfaces in which the diffuseness is considered only through the parameters. (author) [pt

  2. Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

    CERN Document Server

    Mehtar-Tani, Yacine

    2017-04-21

    We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the "soft drop declustering" procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

  3. Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

    Science.gov (United States)

    Mehtar-Tani, Yacine; Tywoniuk, Konrad

    2017-04-01

    We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the "soft drop declustering" procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

  4. Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

    International Nuclear Information System (INIS)

    Mehtar-Tani, Yacine; Tywoniuk, Konrad

    2017-01-01

    We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the “soft drop declustering” procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

  5. Bottomonium production with statistical hadronization in heavy-ion collisions at collider energies

    CERN Document Server

    Byungsik, Hong

    2004-01-01

    We present the bottomonium production estimated by using the hybrid model that combines direct bb pair creation in hard scattering and a statistical hadronization of the deconfined quark-gluon plasma. Complete color screening and full equilibration of the deconfined quark matter is assumed in the quark-gluon plasma phase. An enhanced production of the Upsilon (1S) state is predicted at collider energies. However, a significant, difference between the RHIC (Relativistic Heavy Ion Collider) and the LHC (Large Hadron Collider) is expected in the centrality dependence of the Upsilon (1S) production. Normalizing the Upsilon (1S) production by the average number of binary collisions, we expect about a factor of five decrease from half-overlap to central collisions at the RHIC, but almost no change at the LHC. Plans for measuring the bottomonium production cross-sections in future collider experiments are summarized. (28 refs).

  6. Near-threshold photoionization of hydrogenlike uranium studied in ion-atom collisions via the time-reversed process.

    Science.gov (United States)

    Stöhlker, T; Ma, X; Ludziejewski, T; Beyer, H F; Bosch, F; Brinzanescu, O; Dunford, R W; Eichler, J; Hagmann, S; Ichihara, A; Kozhuharov, C; Krämer, A; Liesen, D; Mokler, P H; Stachura, Z; Swiat, P; Warczak, A

    2001-02-05

    Radiative electron capture, the time-reversed photoionization process occurring in ion-atom collisions, provides presently the only access to photoionization studies for very highly charged ions. By applying the deceleration mode of the ESR storage ring, we studied this process in low-energy collisions of bare uranium ions with low- Z target atoms. This technique allows us to extend the current information about photoionization to much lower energies than those accessible for neutral heavy elements in the direct reaction channel. The results prove that for high- Z systems, higher-order multipole contributions and magnetic corrections persist even at energies close to the threshold.

  7. Effect of ion-neutral collisions on the evolution of kinetic Alfvén waves in plasmas

    Science.gov (United States)

    Goyal, R.; Sharma, R. P.

    2018-03-01

    This paper studies the effect of ion-neutral collisions on the propagation of kinetic Alfvén waves (KAWs) in inhomogeneous magnetized plasma. The inhomogeneity in the plasma imposed by background density in a direction transverse as well as parallel to the ambient magnetic field plays a vital role in the localization process. The mass loading of ions takes place due to their collisions with neutral fluid leading to the damping of the KAWs. Numerical analysis of linear KAWs in inhomogeneous magnetized plasma is done for a fixed finite frequency taking into consideration the ion-neutral collisions. There is a prominent effect of collisional damping on the wave localization, wave magnetic field, and frequency spectrum. A semi-analytical technique has been employed to study the magnetic field amplitude decay process and the effect of wave frequency in the range of ion cyclotron frequency on the propagation of waves leading to damping.

  8. The Shape and Flow of Heavy Ion Collisions (490th Brookhaven Lecture)

    Energy Technology Data Exchange (ETDEWEB)

    Schenke, Bjoern [BNL Physics Department

    2014-12-18

    The sun can’t do it, but colossal machines like the Relativistic Heavy Ion Collider (RHIC) at Brookhaven Lab and Large Hadron Collider (LHC) in Europe sure can. Quarks and gluons make up protons and neutrons found in the nucleus of every atom in the universe. At heavy ion colliders like RHIC and the LHC, scientists can create matter more than 100,000 times hotter than the center of the sun—so hot that protons and neutrons melt into a plasma of quarks and gluons. The particle collisions and emerging quark-gluon plasma hold keys to understanding how these fundamental particles interact with each other, which helps explain how everything is held together—from atomic nuclei to human beings to the biggest stars—how all matter has mass, and what the universe looked like microseconds after the Big Bang. Dr. Schenke discusses theory that details the shape and structure of heavy ion collisions. He will also explain how this theory and data from experiments at RHIC and the LHC are being used to determine properties of the quark-gluon plasma.

  9. Rho0 Photoproduction in Ultra-Peripheral Relativistic Heavy Ion Collisions with STAR

    Energy Technology Data Exchange (ETDEWEB)

    STAR Coll

    2007-12-20

    Photoproduction reactions occur when the electromagnetic field of a relativistic heavy ion interacts with another heavy ion. The STAR collaboration presents a measurement of {rho}{sup 0} and direct {pi}{sup +}{pi}{sup -} photoproduction in ultra-peripheral relativistic heavy ion collisions at {radical}s{sub NN} = 200 GeV. We observe both exclusive photoproduction and photoproduction accompanied by mutual Coulomb excitation. We find a coherent cross-section of {sigma}(AuAu {yields} Au*Au* {rho}{sup 0}) = 530 {+-} 19 (stat.) {+-} 57 (syst.) mb, in accord with theoretical calculations based on a Glauber approach, but considerably below the predictions of a color dipole model. The {rho}{sup 0} transverse momentum spectrum (p{sub T}{sup 2}) is fit by a double exponential curve including both coherent and incoherent coupling to the target nucleus; we find {sigma}{sub inc}/{sigma}{sub coh} = 0.29 {+-} 0.03 (stat.) {+-} 0.08 (syst.). The ratio of direct {pi}{sup +}{pi}{sup -} production is comparable to that observed in {gamma}p collisions at HERA, and appears to be independent of photon energy. Finally, the measured {rho}{sup 0} spin helicity matrix elements agree within errors with the expected s-channel helicity conservation.

  10. A Review on ϕ Meson Production in Heavy-Ion Collision

    Directory of Open Access Journals (Sweden)

    Md. Nasim

    2015-01-01

    Full Text Available The main aim of the relativistic heavy-ion experiment is to create extremely hot and dense matter and study the QCD phase structure. With this motivation, experimental program started in the early 1990s at the Brookhaven Alternating Gradient Synchrotron (AGS and the CERN Super Proton Synchrotron (SPS followed by Relativistic Heavy Ion Collider (RHIC at Brookhaven and recently at Large Hadron Collider (LHC at CERN. These experiments allowed us to study the QCD matter from center-of-mass energies (sNN 4.75 GeV to 2.76 TeV. The ϕ meson, due to its unique properties, is considered as a good probe to study the QCD matter created in relativistic collisions. In this paper we present a review on the measurements of ϕ meson production in heavy-ion experiments. Mainly, we discuss the energy dependence of ϕ meson invariant yield and the production mechanism, strangeness enhancement, parton energy loss, and partonic collectivity in nucleus-nucleus collisions. Effect of later stage hadronic rescattering on elliptic flow (v2 of proton is also discussed relative to corresponding effect on ϕ meson v2.

  11. Reverse engineering of heavy-ion collisions: Unraveling initial conditions from anisotropic flow data

    International Nuclear Information System (INIS)

    Retinskaya, Ekaterina

    2014-01-01

    Ultra-Relativistic heavy-ion physics is a promising field of high energy physics connecting two fields: nuclear physics and elementary particle physics. Experimental achievements of the last years have provided an opportunity to study the properties of a new state of matter created in heavy-ion collisions called quark-gluon plasma. The initial state of two colliding nuclei is affected by fluctuations coming from wave- functions of nucleons. These fluctuations lead to the momentum anisotropy of the hadronic matter which is observed by the detectors. The system created in the collision behaves like a fluid, so the initial state is connected to the final state via hydrodynamic evolution. In this thesis we model the evolution with relativistic viscous hydrodynamics. Our results, combined with experimental data, give non trivial constraints on the initial state, thus achieving 'reverse engineering' of the heavy-ion collisions. The observable which characterizes the momentum anisotropy is the anisotropic flow v n . We present the first measurements of the first harmonic of the anisotropic flow called directed flow v 1 in Pb-Pb collisions at the LHC. We then perform the first viscous hydrodynamic modeling of directed flow and show that it is less sensitive to viscosity than higher harmonics. Comparison of these experimental data with the modeling allows to extract the values of the dipole asymmetry of the initial state, which provides constraints on the models of initial states. A prediction for directed flow v 1 in Au-Au collisions is also made for RHIC. We then perform a similar modeling of the second and third harmonics of the anisotropic flow, called respectively elliptic v 2 and triangular v 3 flow. A combined analysis of the elliptic and triangular flow data compared with viscous hydrodynamic calculations allows us to put constraints on initial ellipticity and triangularity of the system. These constraints are then used as a filter for different models of

  12. Universality classes far from equilibrium. From heavy-ion collisions to superfluid Bose systems

    Energy Technology Data Exchange (ETDEWEB)

    Boguslavski, Kirill

    2016-07-27

    Quantum many-body systems far from equilibrium can approach a nonthermal fixed point during their real-time evolution. One example is scalar field theory, which occurs in models of cosmological inflation, and similar examples are found for non-Abelian plasmas relevant for heavy-ion collisions and for ultracold Bose gases. Investigating nonthermal fixed points of different microscopic theories, we present two novel universality classes that provide links between these systems. One of them involves nonrelativistic, N-component relativistic and expanding scalar systems. It occurs in the deep infrared regime of very high occupancies and is governed by a self-similar evolution. Its nonequilibrium dynamics leads to the formation of a Bose-Einstein condensate. The scaling properties of this region can be described by a vertex-resummed kinetic theory that is based on a systematic large-N expansion at next-to-leading order. The other novel universality class encompasses scalar field theories and non-Abelian plasmas in a longitudinally expanding background and corresponds to an early dynamical stage of heavy-ion collisions in the high-energy limit. We show that these systems share the same self-similar scaling properties for a wide range of momenta in a limit where particles are weakly coupled but their occupancy is high. Both universality classes are found in separate momentum regions in a longitudinally expanding N-component scalar field theory. We argue that the important role of the infrared dynamics ensures that key features of our results for scalar and gauge theories cannot be reproduced consistently in conventional kinetic theory frameworks. Moreover, the observed universality connects different physics disciplines from heavy-ion collisions to ultracold atoms, making a remarkable link between the world's hottest and coldest matter.

  13. Electron loss from multiply protonated lysozyme ions in high energy collisions with molecular oxygen

    DEFF Research Database (Denmark)

    Hvelplund, P; Nielsen, SB; Sørensen, M

    2001-01-01

    We report on the electron loss from multiply protonated lysozyme ions Lys-Hn(n)+ (n = 7 - 17) and the concomitant formation of Lys-Hn(n+1)+. in high-energy collisions with molecular oxygen (laboratory kinetic energy = 50 x n keV). The cross section for electron loss increases with the charge state...... of the precursor from n = 7 to n = 11 and then remains constant when n increases further. The absolute size of the cross section ranges from 100 to 200 A2. The electron loss is modeled as an electron transfer process between lysozyme cations and molecular oxygen....

  14. Heavy ion deep inelastic collisions studied by discrete gamma ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Krolas, W. [The H. Niewodniczanski Inst. of Nuclear Physics, Cracow (Poland)

    1996-05-01

    The discrete gamma ray spectroscopy has been used as a tool to investigate the heavy ion collision. It has been shown that such experimental information supplemented by results of additional of-line radioactivity measurements is complete enough to reconstruct distributions of products of very complex nuclear reactions. Three experiments have been performed in which the {sup 208}Pb + {sup 64}Ni, {sup 130}Te + {sup 64}Ni and {sup 208}Pb + {sup 58}Ni systems have been created. The production cross sections of fragment isotopes have been determined and compared with existing model predictions 64 refs, 59 figs, 19 tabs

  15. Abnormal enhancement of dilepton yield in central heavy-ion collisions from local parity breaking

    CERN Document Server

    Andrianov, A.A.; Espriu, Domenec; Planells, Xumeu

    2010-01-01

    We propose a novel explanation for the dilepton excess observed in heavy ion collisions at invariant masses below 1 GeV. We argue that the presence of local parity breaking due to a time-dependent isosinglet and/or isotriplet pseudoscalar condensate substantially modifies the dispersion relation of photons and vector mesons propagating in such a medium, changing the \\rho~ spectral function and resulting in a potentially large excess of e+e- and \\mu+\\mu- with respect to the theoretical predictions based in a 'cocktail' of known hadronic processes. Possible signatures to prove or disprove this effect are discussed.

  16. Electron interference in fast ion collisions with H{sub 2} and the frequency parameter

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, S; Misra, D; Tribedi, L C [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India); Fainstein, P D, E-mail: lokesh@tifr.res.in [Centro Atomico Bariloche, 8400 Bariloche (Argentina)

    2011-06-15

    The Young-type interference effect has been investigated in electron emission from molecular hydrogen in collision of 5 MeV u{sup -1} F{sup 9+} ions. The double differential cross section ratios of molecular-to-atomic hydrogen exhibits oscillatory structure, which is discussed in terms of the Young-type electron interference. We have obtained the frequencies of such oscillation for different angles. A comparative study of the frequency parameter is given with early measurements performed by other groups.

  17. Studying heavy-ion collisions with coverage near zero degrees using FAUST–QTS

    International Nuclear Information System (INIS)

    Cammarata, Paul; Chapman, Matthew B.; McIntosh, Alan B.; Souliotis, George A.; Bakhtiari, Layla; Behling, Spencer; Bonasera, Giacomo; Heilborn, Lauren A.; Mabiala, Justin; May, Larry W.; Raphelt, Andrew; Youngs, Michael D.

    2015-01-01

    Heavy-ion collisions around the Fermi energy provide a rich environment for investigating reaction dynamics and provide an opportunity to explore the transition from quasi-fission to multi-fragmentation. A new detection system, FAUST–QTS, has been commissioned at Texas A&M University in order to investigate the reaction dynamics in this transitional energy regime. FAUST–QTS is constructed through the coupling of the FAUST array to a large bore quadrupole triplet spectrometer, and designed to detect heavy fragments near the beam axis coincident with lighter particles

  18. R-matrix calculation of electron collisions with the BF{sup +} molecular ion

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarti, K [Department of Mathematics, Scottish Church College, 1 and 3 Urquhart Sq, Kolkata 700006 (India); Tennyson, Jonathan [Department of Physics and Astronomy, University College London, Gower St, London WC1E 6BT (United Kingdom)

    2009-05-28

    Electron collisions with the BF{sup +} molecular ion are studied using the framework of the diatomic version of the UK molecular R-matrix codes. A configuration-interaction calculation is performed for BF{sup +} to obtain potential energy curves and target properties for 14 lowest doublet and quartet states. Scattering calculations are performed which yield resonance parameters and excitation cross sections in the energy range 0-20 eV. Cross sections for rotational excitations and an approximate calculation for the electron impact dissociation cross section for BF{sup +} are also presented.

  19. Vector mesons in dense matter and dilepton production in heavy ion collisions at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Santini, Elvira

    2008-02-15

    The vector meson spectral functions are calculated to the first order in the nuclear matter density assuming the dominant contribution comes from the couplings of the vector mesons to nucleons and nucleon resonances. An attempt is made to reproduce the HADES dilepton production data with the in-medium spectral functions of the vector mesons using the Relativistic Quantum Molecular Dynamics (RQMD) transport model developed earlier for modelling heavy-ion collisions. The results are sensitive to the in-medium broadening of nucleon resonances. A generally good agreement with the HADES data is achieved for selfconsistent treatment of the nucleon resonance broadening and the vector meson spectral functions. (orig.)

  20. Resonance Model of $\\pi \\Delta \\rightarrow Y K$ for Kaon Production in Heavy Ion Collisions

    OpenAIRE

    Tsushima, K.; Huang, S. W.; Faessler, Amand

    1994-01-01

    The elementary production cross sections $\\pi \\Delta \\rightarrow Y K$ $(Y=\\Sigma,\\,\\, \\Lambda)$ and $\\pi N \\rightarrow Y K$ are needed to describe kaon production in heavy ion collisions. The $\\pi N \\rightarrow Y K$ reactions were studied previously by a resonance model. The model can explain the experimental data quite well \\cite{tsu}. In this article, the total cross sections $\\pi \\Delta \\rightarrow Y K$ at intermediate energies (from the kaon production threshold to3 GeV of $\\pi \\Delta$ ce...

  1. Central collisions of heavy ions at bombarding energies close to the Coulombbarrier

    International Nuclear Information System (INIS)

    Kienle, P.

    1980-01-01

    The results of experimental work carried out to investigate the influence of the mass-asymmetry of the entrance channel on the reaction mechanism and the time evolution of multinucleon transfer reactions between very heavy ions at small angular momentum are reported. The following aspects are examined: (1) Experimental methods and simple features of central collisions. (2) Influence of the mass-asymmetry of the entrance channel on the reaction mechanism. (3) Neutron rich nucleon flow. (4) Time evolution of the charge and mass flow. (5) Equilibration of the neutron to proton ratio. (UK)

  2. Dynamical evolution of spectator systems produced in ultrarelativistic heavy-ion collisions

    Science.gov (United States)

    Mazurek, K.; Szczurek, A.; Schmitt, C.; Nadtochy, P. N.

    2018-02-01

    In peripheral heavy-ion collisions at ultrarelativistic energies, usually only parts of the colliding nuclei effectively interact with each other. In the overlapping zone, a fireball or quark-gluon plasma is produced. The excitation energy of the heavy remnant can range from a few tens to several hundreds of MeV, depending on the impact parameter. The decay of these excited spectators is investigated in this work for the first time within a dynamical approach based on the multidimensional stochastic Langevin equation. The potential of this exploratory work to understand the connection between electromagnetic fields generated by the heavy spectators and measured pion distributions is discussed.

  3. δ-electron spectroscopy and the atomic clock effect in heavy-ion collisions

    International Nuclear Information System (INIS)

    Mueller-Nehler, U.

    1993-11-01

    The properties of strongly bound electrons in superheavy quasimolecular systems with combined nuclear charge numbers Z = Z P + Z T ≥ 110 are investigated. The emission of δ-electrons may serve as an atomic clock for nuclear reactions which is associated with the large overlap of the electron probability density with the nuclear interior. Excitation and emission rates of inner-shell electrons in collisions of very heavy ions with beam energies at or above the nuclear Coulomb barrier depend explicitly on details of the nuclear dynamics. Theoretical and experimental results are reviewed. (orig.)

  4. How (non-)linear is the hydrodynamics of heavy ion collisions?

    Energy Technology Data Exchange (ETDEWEB)

    Floerchinger, Stefan; Wiedemann, Urs Achim [Physics Department, Theory Unit, CERN, CH-1211 Genève 23 (Switzerland); Beraudo, Andrea [Physics Department, Theory Unit, CERN, CH-1211 Genève 23 (Switzerland); Dep. de Fisica de Particulas, U. de Santiago de Compostela, E-15782 Santiago de Compostela, Galicia (Spain); Del Zanna, Luca [Dipartimento di Fisica e Astronomia, Università di Firenze, Via G. Sansone 1, I-50019 Sesto F.no (Firenze) (Italy); INFN - Sezione di Firenze, Via G. Sansone 1, I-50019 Sesto F.no (Firenze) (Italy); INAF - Osservatorio Astrofisico di Arcetri, L.go E. Fermi 5, I-50125 Firenze (Italy); Inghirami, Gabriele [Dipartimento di Fisica e Astronomia, Università di Firenze, Via G. Sansone 1, I-50019 Sesto F.no (Firenze) (Italy); INFN - Sezione di Firenze, Via G. Sansone 1, I-50019 Sesto F.no (Firenze) (Italy); Rolando, Valentina [INFN - Sezione di Ferrara, Via Saragat 1, I-44100 Ferrara (Italy); Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Via Saragat 1, I-44100 Ferrara (Italy)

    2014-07-30

    We provide evidence from full numerical solutions that the hydrodynamical evolution of initial density fluctuations in heavy ion collisions can be understood order-by-order in a perturbative series in deviations from a smooth and azimuthally symmetric background solution. To leading linear order, modes with different azimuthal wave numbers do not mix. When quadratic and higher order corrections are numerically sizable, they can be understood as overtones with corresponding wave numbers in a perturbative series. Several findings reported in the recent literature result naturally from the general perturbative series formulated here.

  5. Ultra-relativistic heavy-ion collisions - a hot cocktail of hydrodynamics, resonances and jets

    Directory of Open Access Journals (Sweden)

    Zabrodin E.

    2015-01-01

    Full Text Available Ultra-relativistic heavy-ion collisions at energies of RHIC and LHC are considered. For comparison with data the HYDJET++ model, which contains the treatment of both soft and hard processes, is employed. The study focuses mainly on the interplay of ideal hydrodynamics, final state interactions and jets, and its influence on the development of harmonics of the anisotropic flow. It is shown that jets are responsible for violation of the number-of-constituent-quark (NCQ scaling at LHC energies. The interplay between elliptic and triangular flows and their contribution to higher flow harmonics and dihadron angular correlations, including ridge, is also discussed.

  6. Radiative double-electron capture in collisions of fast heavy ions with solid carbon targets

    International Nuclear Information System (INIS)

    Yakhontov, V.L.; Amusia, M.Y.

    1997-01-01

    Two-electron capture with an emission of a single photon (TESP) in collisions of highly charged ions with light atoms is considered. Such a process is actually a time-reversed double photoionization but occurring at specific kinematics. In the lowest order in the interelectron interaction, the TESP probability is determined by two diagrams which are evaluated analytically by means of the Coulomb Green close-quote s function. The calculated ratio of the radiative double-electron capture and single recombination cross sections is in fair agreement with the data obtained in the recent experimental study of this phenomenon. copyright 1997 The American Physical Society

  7. Radiative double electron capture in fast heavy ion-atom collisions

    International Nuclear Information System (INIS)

    Yakhontov, V.L.; Amusia, M.Ya.

    1996-01-01

    Two-electron capture with emission of a single photon (TESP) in collisions of highly charged ions with light atoms is considered. Such a process is actually a time-reversed double photoionization but occurring at specific kinematics. In the lowest order in the inter-electron interaction, the TESP probability is determined by two diagrams which are evaluated analytically by means of the Coulomb Green function. The calculated ratio of the TESP and single recombination cross sections is in fair agreement with the data obtained in the recent experimental study of this phenomena. (orig.)

  8. Correlated double electron capture in slow, highly charged ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Stolterfoht, N.; Havener, C.C.; Phaneuf, R.A.; Swenson, J.K.; Shafroth, S.M.; Meyer, F.W.

    1986-01-01

    Recent measurements of autoionization electrons produced in slow, highly charged ion-atom collisions are reviewed. Mechanisms for double electron capture into equivalent and nonequivalent configurations are analyzed by comparing the probabilities for the creation of L/sub 1/L/sub 23/X Coster Kronig electrons and L-Auger electrons. It is shown that the production of the Coster-Kronig electrons is due to electron correlation effects whose analysis leads beyond the independent-particle model. The importance of correlation effects on different capture mechanisms is discussed. 28 refs., 6 figs.

  9. A high resolution X-ray crystal spectrometer to study electron and heavy-ion impact atomic collisions

    Science.gov (United States)

    Kumar, Ajay; Misra, D.; Kelkar, A. H.; Kadhane, U. R.; Thulasiram, K. V.; Tribedi, Lokesh C.

    2007-06-01

    We have studied fast ion-atom and electron-atom collision processes using a reconditioned high resolution X-ray spectrometer. The X-rays, generated by the collisions, are dispersed by a curved ADP crystal (Johansson geometry) and detected by a gas proportional counter. A self-written LabVIEW based program has been used to give precise and controlled movement to the crystal and for data acquisition. The performance was tested by detecting the Kα diagram and satellite lines of several elements. The Kα satellite lines of Al have been studied in collision with 3-12 keV electrons and 40 MeV C^{4+} ions. In ion collisions as large as four L-vacancies are created simultaneously with the K-vacancy, compared to two satellites in case of the e-impact. In addition, we have measured the X-rays from H-, He- and Li-like Si ions which arise due to the electron loss/capture process in highly charged 80 MeV Si^{7+} ions in collision with thin carbon foil. Approximate charge state distribution has been obtained using this new technique.

  10. Projectile X-ray emission in relativistic ion-atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Salem, Shadi Mohammad Ibrahim

    2010-03-16

    This work reports on the study of the projectile X-ray emission in relativistic ion-atom collisions. Excitation of K-shell in He-like uranium ions, electron capture into H-like uranium ions and Simultaneous ionization and excitation of initially He-like uranium ions have been studied using the experimental storage ring at GSI. For the K{sub {alpha}}{sub 1} and K{sub {alpha}}{sub 2} transitions originating from the excitation of the He-like uranium ions, no alignment was observed. In contrast, the Ly{sub {alpha}}{sub 1} radiation from the simultaneous ionization-excitation process of the He-like uranium ions shows a clear alignment. The experimental value leads to the inclusion of a magnetic term in the interaction potential. The capture process of target electrons into the highly-charged heavy ions was studied using H-like uranium ions at an incident energy of 220 MeV/u, impinging on N{sub 2} gas-target. It was shown that, the strongly aligned electrons captured in 2p{sub 3/2} level couple with the available 1s{sub 1/2} electron which shows no initial directional preference. The magnetic sub-state population of the 2p{sub 3/2} electron is redistributed according to the coupling rules to the magnetic sub-states of the relevant two-electron states. This leads to the large anisotropy in the corresponding individual ground state transitions contributing to the K{sub {alpha}}{sub 1} emission. From the K{sub {alpha}}{sub 1}/K{sub {alpha}}{sub 2} ratio, the current results show that the incoherent addition of the E1 and M2 transition components yield to an almost isotropic emission of the total K{sub {alpha}}{sub 1}. In contrast to the radiative electron capture, the experimental results for the K-shell single excitation of He-like uranium ions indicate that only the {sup 1}P{sub 1} level contributes to the K{sub {alpha}}{sub 1} transition. For this case, the anisotropy parameter {beta}{sub 20} was found to be -0.20{+-}0.03. This work also reports on the study of a two

  11. Collisions of carbon and oxygen ions with electrons, H, H/sub 2/ and He: Volume 5

    Energy Technology Data Exchange (ETDEWEB)

    Phaneuf, R.A.; Janev, R.K.; Pindzola, M.S.

    1987-02-01

    This report provides a handbook for fusion research of recommended cross-section and rate-coefficient data for collisions of carbon and oxygen ions with electrons, hydrogen atoms and molecules, and helium atoms. Published experimental and theoretical data have been collected and evaluated, and recommended data are presented in tabular, graphical, and parametrized form. Processes considered include exciation, ionization, and charge exchange at collision energies appropriate to applications in fusion-energy research.

  12. Particle Production in Strong Electromagnetic Fields in Relativistic Heavy-Ion Collisions

    Directory of Open Access Journals (Sweden)

    Kirill Tuchin

    2013-01-01

    Full Text Available I review the origin and properties of electromagnetic fields produced in heavy-ion collisions. The field strength immediately after a collision is proportional to the collision energy and reaches ~mπ2 at RHIC and ~10mπ2 at LHC. I demonstrate by explicit analytical calculation that after dropping by about one-two orders of magnitude during the first fm/c of plasma expansion, it freezes out and lasts for as long as quark-gluon plasma lives as a consequence of finite electrical conductivity of the plasma. Magnetic field breaks spherical symmetry in the direction perpendicular to the reaction plane, and therefore all kinetic coefficients are anisotropic. I examine viscosity of QGP and show that magnetic field induces azimuthal anisotropy on plasma flow even in spherically symmetric geometry. Very strong electromagnetic field has an important impact on particle production. I discuss the problem of energy loss and polarization of fast fermions due to synchrotron radiation, consider photon decay induced by magnetic field, elucidate J/ψ dissociation via Lorentz ionization mechanism, and examine electromagnetic radiation by plasma. I conclude that all processes in QGP are affected by strong electromagnetic field and call for experimental investigation.

  13. GPU-accelerated calculations of hadron spectra from heavy-ion collisions

    Science.gov (United States)

    Golden, Matthew; Heinz, Ulrich; Jetscape Collaboration

    2017-09-01

    To calculate observables for heavy ion collisions, many events with fluctuating initial conditions are simulated and statistically analyzed. A larger set of simulated collision events yields better statistical results, so decreasing the computation time per event is important. A modern GPU possesses thousands of cores and can efficiently perform identical tasks in parallel. We take advantage of this for performing the Cooper-Frye integrals for the hadron spectra obtained from the numerical output from dissipative hydrodynamic simulations. For a given event, this computation consists of two parts: (1) generating thermal spectra of all hadron resonances as Cooper-Frye integrals over the freeze-out surface, and (2) computing the spectra of stable hadrons by letting unstable resonances decay. We here show results using input from (2 +1)-dimensional boost-invariant hydrodynamic simulations where both of these steps were accelerated by parallelizing them on a GPU. The GPU implementation yields a speed-up by about two and one orders of magnitude, respectively, for the first and second of these steps. For semi-central Pb +Pb collision at the LHC, the time needed for the first step is reduced from 31 minutes on a single CPU to 16 seconds on the GPU, and for the second step from 4 minutes to 20 seconds. This research was funded by the National Science Foundation through the JETSCAPE collaboration.

  14. Phi Meson Production In Gold-Gold Collisions at the Relativistic Heavy Ion Collider

    CERN Document Server

    Yamamoto, E T

    2001-01-01

    Results from the first measurement of mid-rapidity &phis; vector meson production in Au + Au collisions at RHIC ( sNN = 130 GeV) are described. Using the STAR detector, &phis; mesons were measured from the &phis; → K+ K− decay channel. For the 11% most central collisions, the slope parameter from an exponential fit to the transverse mass distribution is T = 379 ± 51 (stat) ± 45 (syst) MeV, the yield dN/dy = 5.73 ± 0.37 (stat) ± 0.57 (syst) per event and the ratios N&phis;/N h− and N&phis;/ NK− are found to be 0.021 ± 0.001 (stat) ± 0.004 (syst) and 0.14 ± 0.01 (stat) ± 0.03 (syst). Within the statistics available, the mid-rapidity ratios, N&phis;/Nh− and N&phis;/NK− , and the slope parameter for the &phis; meson do not change for the selected centrality bins. The slope parameter increases in heavy ion collisions as a function of ...

  15. Open heavy flavor and quarkonia measurements in heavy-ion collisions at RHIC

    Directory of Open Access Journals (Sweden)

    Bielcik Jaroslav

    2014-04-01

    Full Text Available The properties of the hot and dense nuclear matter produced at RHIC in heavy-ion collisions can be investigated in multiple ways by heavy flavor production. The STAR and PHENIX experiments have excellent capability to study both open heavy flavor and quarkonia. Heavy quarks are produced in early stage of the collisions and the mechanisms of their interaction with nuclear matter are not yet well understood. The open heavy flavor hadrons can be studied using electrons from their semileptonic decays or via direct reconstruction through their hadronic decay channels. The heavy quarkonia production is expected to be sequentially suppressed depending on the temperature of the produced nuclear matter. However, cold nuclear matter effects play an important role and have to be well understood. In this paper we report recent results from the RHIC heavyion program on non-photonic electrons, direct reconstruction of charm mesons, J/ψ as well as ϒ in p+p, d+Au and Au+Au collisions at √sNN = 200 GeV.

  16. A Structures for Lossless Ion Manipulations (SLIM) Module for Collision Induced Dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Ian K.; Garimella, Sandilya V. B.; Norheim, Randolph V.; Baker, Erin S.; Ibrahim, Yehia M.; Smith, Richard D.

    2016-04-20

    A collision induced dissociation (CID) structures for lossless ion manipulations (SLIM) module is introduced and coupled to a quadrupole time-of-flight (QTOF) mass spectrometer (MS). The SLIM CID module was mounted after an ion mobility (IM) drift tube to enable IM/CID/MS studies. The efficiency of CID was studied by using the model peptide leucine enkephalin. CID efficiencies (62%) compared favorably to other beam-type CID methods. Additionally, the SLIM CID module was used to fragment a mixture of 9 peptides after IM separation. This work also represents the first application of SLIM in the 0.3 to 0.5 Torr pressure regime, an order of magnitude lower in pressure than previously studied.

  17. Inner-shell excitation in heavy ion collisions up to intermediate incident energies

    International Nuclear Information System (INIS)

    Reus, T. de.

    1987-04-01

    Electronic excitations in collisions of very heavy ions with a total nuclear charge Z greater than 1/α ≅ 137 at bombarding energies reaching from 3.6 MeV/n up to 100 MeV/n are the subject of this thesis. The dynamical behaviour of the electron-positron-field is described within a semiclassical model, which is reviewed and extended to include electronic interactions via a mean field. A detailed comparison with experimental data of K-vacancy formation, δ-electron and positron emission shows an improved agreement compared with former calculations. Structures in spectra of positrons emitted in sub- and supercritical collision are discussed in two respects: Firstly as a signal of the vacuum decay in supercritical electromagnetic fields which evolve in the vicinity of long living giant nuclear molecules. Secondly as an atomic effect, which might be related to an instaneous formation of molecular 1sσ- and 2p 1/2 σ- levels. However, beyond this speculation the emission spectra of electrons and positrons in deep inelastic reactions have proven to be a powerful tool for measuring nuclear reaction or delay times in the order of 10 -21 s. This property was transfered to the domain of intermediate energy collisions. In first order perturbation theory we derived a scaling law, exhibiting how nuclear stopping times could be extracted from the emission spectra of high energetic δ-electrons. Quantitative calculations within a coupled channel code have been carried out for the system Pb+Pb, yielding cross sections of up to 20 nb for the emission of electrons with a kinetic energy of 50 MeV in 60 MeV/n-collisions. (orig./HSI)

  18. Multifractal characteristics of multiparticle production in heavy-ion collisions at SPS energies

    Science.gov (United States)

    Khan, Shaista; Ahmad, Shakeel

    Entropy, dimensions and other multifractal characteristics of multiplicity distributions of relativistic charged hadrons produced in ion-ion collisions at SPS energies are investigated. The analysis of the experimental data is carried out in terms of phase space bin-size dependence of multiplicity distributions following the Takagi’s approach. Yet another method is also followed to study the multifractality which, is not related to the bin-width and (or) the detector resolution, rather involves multiplicity distribution of charged particles in full phase space in terms of information entropy and its generalization, Rényi’s order-q information entropy. The findings reveal the presence of multifractal structure — a remarkable property of the fluctuations. Nearly constant values of multifractal specific heat “c” estimated by the two different methods of analysis followed indicate that the parameter “c” may be used as a universal characteristic of the particle production in high energy collisions. The results obtained from the analysis of the experimental data agree well with the predictions of Monte Carlo model AMPT.

  19. Transverse energy per charged particle in heavy-ion collisions: Role of collective flow

    Science.gov (United States)

    Kumar Tiwari, Swatantra; Sahoo, Raghunath

    2018-03-01

    The ratio of (pseudo)rapidity density of transverse energy and the (pseudo)rapidity density of charged particles, which is a measure of the mean transverse energy per particle, is an important observable in high energy heavy-ion collisions. This ratio reveals information about the mechanism of particle production and the freeze-out criteria. Its collision energy and centrality dependence is almost similar to the chemical freeze-out temperature until top Relativistic Heavy-Ion Collider (RHIC) energy. The Large Hadron Collider (LHC) measurement at √{s_{NN}} = 2.76 TeV brings up new challenges towards understanding the phenomena like gluon saturation and role of collective flow, etc. being prevalent at high energies, which could contribute to the above observable. Statistical Hadron Gas Model (SHGM) with a static fireball approximation has been successful in describing both the centrality and energy dependence until top RHIC energies. However, the SHGM predictions for higher energies lie well below the LHC data. In order to understand this, we have incorporated collective flow in an excluded-volume SHGM (EV-SHGM). Our studies suggest that the collective flow plays an important role in describing E T/ N ch and it could be one of the possible parameters to explain the rise observed in E T/ N ch from RHIC to LHC energies. Predictions are made for E T/ N ch , participant pair normalized-transverse energy per unit rapidity and the Bjorken energy density for Pb+Pb collisions at √{s_{NN}} = 5.02 TeV at the Large Hadron Collider.

  20. Effects of bulk viscosity and hadronic rescattering in heavy ion collisions at energies available at the BNL Relativistic Heavy Ion Collider and at the CERN Large Hadron Collider

    Science.gov (United States)

    Ryu, Sangwook; Paquet, Jean-François; Shen, Chun; Denicol, Gabriel; Schenke, Björn; Jeon, Sangyong; Gale, Charles

    2018-03-01

    We describe ultrarelativistic heavy ion collisions at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider with a hybrid model using the IP-Glasma model for the earliest stage and viscous hydrodynamics and microscopic transport for the later stages of the collision. We demonstrate that within this framework the bulk viscosity of the plasma plays an important role in describing the experimentally observed radial flow and azimuthal anisotropy simultaneously. We further investigate the dependence of observables on the temperature below which we employ the microscopic transport description.

  1. Production of charm quarks in a parton cascade model for relativistic heavy ion collisions at √{sNN}=200 GeV

    Science.gov (United States)

    Srivastava, Dinesh K.; Bass, Steffen A.; Chatterjee, Rupa

    2017-12-01

    We study the production and dynamics of heavy quarks in the parton cascade model for relativistic heavy ion collisions. The model is motivated by the QCD parton picture and describes the dynamics of an ultrarelativistic heavy ion collision in terms of cascading partons which undergo scattering and multiplication while propagating. We focus on the dynamics of charm quark production and evolution in p +p and Au + Au collisions for several different interaction scenarios, viz., collisions only between primary partons without radiation of gluons, multiple collisions without radiation of gluons, and multiple collisions with radiation of gluons, allowing us to isolate the contributions of parton rescattering and radiation to charm production. We also discuss results of an eikonal approximation of the collision which provides a valuable comparison with minijet calculations and clearly brings out the importance of multiple collisions.

  2. The nuclear equation of state in effective relativistic field theories and pion yields in heavy-ion collisions

    International Nuclear Information System (INIS)

    Schoenhofen, M.; Cubero, M.; Gering, M.; Sambataro, M.; Feldmeier, H.; Noerenberg, W.

    1989-06-01

    Within the framework of relativistic field theory for nucleons, deltas, scalar and vector mesons, a systematic study of the nuclear equation of state and its relation to pion yields in heavy-ion collisions is presented. Not the compressibility but the effective nucleon mass at normal nuclear density turns out to be the most sensitive parameter. Effects from vaccum fluctuations are well modelled within the mean-field no-sea approximation by self-interaction terms for the scalar meson field. Incomplete thermalization in the fireball may be the reason for the low pion yields observed in heavy-ion collisions. (orig.)

  3. An Interlaboratory Evaluation of Drift Tube Ion Mobility–Mass Spectrometry Collision Cross Section Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Stow, Sarah M. [Department; Causon, Tim J. [Division; Zheng, Xueyun [Biological; Kurulugama, Ruwan T. [Agilent Technologies, Santa Clara, California 95051, United States; Mairinger, Teresa [Division; May, Jody C. [Department; Rennie, Emma E. [Agilent Technologies, Santa Clara, California 95051, United States; Baker, Erin S. [Biological; Smith, Richard D. [Biological; McLean, John A. [Department; Hann, Stephan [Division; Fjeldsted, John C. [Agilent Technologies, Santa Clara, California 95051, United States

    2017-08-14

    Collision cross section (CCS) measurements resulting from ion mobility-mass spectrometry (IM-MS) experiments provide a promising orthogonal dimension of structural information in MS-based analytical separations. As with any molecular identifier, interlaboratory standardization must precede broad range integration into analytical workflows. In this study, we present a reference drift tube ion mobility mass spectrometer (DTIM-MS) where improvements on the measurement accuracy of experimental parameters influencing IM separations provide standardized drift tube, nitrogen CCS values (DTCCSN2) for over 120 unique ion species with the lowest measurement uncertainty to date. The reproducibility of these DTCCSN2 values are evaluated across three additional laboratories on a commercially available DTIM-MS instrument. The traditional stepped field CCS method performs with a relative standard deviation (RSD) of 0.29% for all ion species across the three additional laboratories. The calibrated single field CCS method, which is compatible with a wide range of chromatographic inlet systems, performs with an average, absolute bias of 0.54% to the standardized stepped field DTCCSN2 values on the reference system. The low RSD and biases observed in this interlaboratory study illustrate the potential of DTIM-MS for providing a molecular identifier for a broad range of discovery based analyses.

  4. Radiative double electron capture in collisions of fully-stripped fluorine ions with thin carbon foils

    Science.gov (United States)

    Elkafrawy, Tamer Mohammad Samy

    Radiative double electron capture (RDEC) is a one-step process in ion-atom collisions occurring when two target electrons are captured to a bound state of the projectile simultaneously with the emission of a single photon. The emitted photon has approximately double the energy of the photon emitted due to radiative electron capture (REC), which occurs when a target electron is captured to a projectile bound state with simultaneous emission of a photon. REC and RDEC can be treated as time-reversed photoionization (PI) and double photoionization (DPI), respectively, if loosely-bound target electrons are captured. This concept can be formulated with the principle of detailed balance, in which the processes of our interest can be described in terms of their time-reversed ones. Fully-stripped ions were used as projectiles in the performed RDEC experiments, providing a recipient system free of electron-related Coulomb fields. This allows the target electrons to be transferred without interaction with any of the projectile electrons, enabling accurate investigation of the electron-electron interaction in the vicinity of electromagnetic field. In this dissertation, RDEC was investigated during the collision of fully-stripped fluorine ions with a thin carbon foil and the results are compared with the recent experimental and theoretical studies. In the current work, x rays associated with projectile charge-changing by single and double electron capture and no charge change by F9+ ions were observed and compared with recent work for O8+ ions and with theory. Both the F 9+ and O8+ ions had energies in the ˜MeV/u range. REC, in turn, was investigated as a means to compare with the theoretical predictions of the RDEC/REC cross section ratio. The most significant background processes including various mechanisms of x-ray emission that may interfere with the energy region of interest are addressed in detail. This enables isolation of the contributions of REC and RDEC from the

  5. Accurate calculations of the ground state and low-lying excited states of the (RbBa)+ molecular ion: a proposed system for ultracold reactive collisions

    DEFF Research Database (Denmark)

    Knecht, Stefan; Sørensen, Lasse Kragh; Jensen, Hans Jørgen Aagaard

    2010-01-01

    Collisions of ultracold Ba+ ions on a Rb Bose–Einstein condensate have been suggested as a possible benchmark system for ultracold ion-neutral collision experiments. However, a priori knowledge of the possible processes is desirable. For this purpose, we here present high-level four-component cou...

  6. Understanding Molecular Ion-Neutral Atom Collisions for the Production of Ultracold Molecular Ions

    Science.gov (United States)

    2016-06-06

    grant for Education , Research and Engineering: The number of undergraduates funded by your agreement who graduated during this period and intend to work...40Ca magneto-optical trap ( MOT ) co- located with a linear quadrupole radio- frequency ion trap (LQT) system. The 40Ca MOT laser...the linear quadrupole trap, while ultracold atoms are collected in a MOT . The ultracold atoms quickly cool the atomic/molecular ion’s

  7. Modeling near-barrier collisions of heavy ions based on a Langevin-type approach

    Science.gov (United States)

    Karpov, A. V.; Saiko, V. V.

    2017-08-01

    Background: Multinucleon transfer in low-energy nucleus-nucleus collisions is proposed as a method of production of yet-unknown neutron-rich nuclei hardly reachable by other methods. Purpose: Modeling of dynamics of nuclear reactions induced by heavy ions in their full complexity of competing reaction channels remains to be a challenging task. The work is aimed at development of such a model and its application to the analysis of multinucleon transfer in deep inelastic collisions of heavy ions leading, in particular, to formation of neutron-rich isotopes in the vicinity of the N =126 shell closure. Method: Multidimensional dynamical model of nucleus-nucleus collisions based on the Langevin equations has been proposed. It is combined with a statistical model for simulation of de-excitation of primary reaction fragments. The model provides a continuous description of the system evolution starting from the well-separated target and projectile in the entrance channel of the reaction up to the formation of final reaction products. Results: A rather complete set of experimental data available for reactions 136Xe+198Pt,208Pb,209Bi was analyzed within the developed model. The model parameters have been determined. The calculated energy, mass, charge, and angular distributions of reaction products, their various correlations as well as cross sections for production of specific isotopes agree well with the data. On this basis, optimal experimental conditions for synthesizing the neutron-rich nuclei in the vicinity of the N =126 shell were formulated and the corresponding cross sections were predicted. Conclusions: The production yields of neutron-rich nuclei with N =126 weakly depend on the incident energy. At the same time, the corresponding angular distributions are strongly energy dependent. They are peaked at grazing angles for larger energies and extend up to the forward angles at low near-barrier collision energies. The corresponding cross sections exceed 100 nb for

  8. Doubly Differential Final-State Momentum Distributions of the Ionization Products in Collision of Bare Ions with Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Tribedi, L.C.; Richard, P.; Wang, Y.D.; Lin, C.D.; Olson, R.E. [J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2601 (United States)]|[Physics Department, University of Missouri-Rolla, Rolla, Missouri 65401 (United States)

    1996-10-01

    In this paper recoil-ion production cross sections are presented differential in recoil-ion longitudinal momentum and electron emission angle in ionization of atomic and molecular hydrogen by bare ion projectiles. A new formulation for constructing these double differential distributions from the measured electron double differential cross sections is used. A novel feature is the separation of two different branches of the recoil-ion longitudinal momentum distribution corresponding to soft and hard collision mechanisms of ionization. The single differential distributions have also been derived. {copyright} {ital 1996 The American Physical Society.}

  9. Comparison of heavy-ion transport simulations: Collision integral in a box

    Science.gov (United States)

    Zhang, Ying-Xun; Wang, Yong-Jia; Colonna, Maria; Danielewicz, Pawel; Ono, Akira; Tsang, Manyee Betty; Wolter, Hermann; Xu, Jun; Chen, Lie-Wen; Cozma, Dan; Feng, Zhao-Qing; Das Gupta, Subal; Ikeno, Natsumi; Ko, Che-Ming; Li, Bao-An; Li, Qing-Feng; Li, Zhu-Xia; Mallik, Swagata; Nara, Yasushi; Ogawa, Tatsuhiko; Ohnishi, Akira; Oliinychenko, Dmytro; Papa, Massimo; Petersen, Hannah; Su, Jun; Song, Taesoo; Weil, Janus; Wang, Ning; Zhang, Feng-Shou; Zhang, Zhen

    2018-03-01

    Simulations by transport codes are indispensable to extract valuable physical information from heavy-ion collisions. In order to understand the origins of discrepancies among different widely used transport codes, we compare 15 such codes under controlled conditions of a system confined to a box with periodic boundary, initialized with Fermi-Dirac distributions at saturation density and temperatures of either 0 or 5 MeV. In such calculations, one is able to check separately the different ingredients of a transport code. In this second publication of the code evaluation project, we only consider the two-body collision term; i.e., we perform cascade calculations. When the Pauli blocking is artificially suppressed, the collision rates are found to be consistent for most codes (to within 1 % or better) with analytical results, or completely controlled results of a basic cascade code. In orderto reach that goal, it was necessary to eliminate correlations within the same pair of colliding particles that can be present depending on the adopted collision prescription. In calculations with active Pauli blocking, the blocking probability was found to deviate from the expected reference values. The reason is found in substantial phase-space fluctuations and smearing tied to numerical algorithms and model assumptions in the representation of phase space. This results in the reduction of the blocking probability in most transport codes, so that the simulated system gradually evolves away from the Fermi-Dirac toward a Boltzmann distribution. Since the numerical fluctuations are weaker in the Boltzmann-Uehling-Uhlenbeck codes, the Fermi-Dirac statistics is maintained there for a longer time than in the quantum molecular dynamics codes. As a result of this investigation, we are able to make judgements about the most effective strategies in transport simulations for determining the collision probabilities and the Pauli blocking. Investigation in a similar vein of other ingredients

  10. Probing transverse momentum broadening via dihadron and hadron-jet angular correlations in relativistic heavy-ion collisions

    Science.gov (United States)

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

    2017-10-01

    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-induced broadening 〈 p⊥2 〉 and the so-called jet quenching parameter q ˆ can be extracted from the angular de-correlations observed in AA collisions. A global χ2 analysis of dihadron and hadron-jet angular correlation data renders 〈p⊥ 2 〉 ∼13-4+5 GeV2 for a quark jet at RHIC top energy. Further experimental and theoretical efforts along the direction of this work shall significantly advance the quantitative understanding of transverse momentum broadening and help us acquire unprecedented knowledge of jet quenching parameter in relativistic heavy-ion collisions.

  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. Double differential distributions of electron emission in ion-atom and electron-atom collisions using an electron spectrometer

    Science.gov (United States)

    Misra, Deepankar; Thulasiram, K. V.; Fernandes, W.; Kelkar, Aditya H.; Kadhane, U.; Kumar, Ajay; Singh, Yeshpal; Gulyás, L.; Tribedi, Lokesh C.

    2009-01-01

    We study electron emission from atoms and molecules in collisions with fast electrons and heavy ions (C 6+). The soft collision electrons (SE), two center electron emission (TCEE), the binary encounter (BE) events and the KLL Auger lines along with the elastically scattered peaks (in electron collisions) are studied using a hemispherical electrostatic electron analyzer. The details of the measurements along with description of the spectrometer and data acquisition system are given. The angular distributions of the low energy (few eV) electrons in soft collisions and the binary encounter electrons at keV energies are compared with quantum mechanical models based on the first Born (B1) and the continuum distorted wave-Eikonal initial state approximation (CDW-EIS).

  13. Double differential distributions of electron emission in ion-atom and electron-atom collisions using an electron spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Misra, Deepankar [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India)], E-mail: dmisra@tifr.res.in; Thulasiram, K.V.; Fernandes, W.; Kelkar, Aditya H.; Kadhane, U.; Kumar, Ajay; Singh, Yeshpal [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India); Gulyas, L. [Institute of Nuclear Research of the Hungarian Academy of Science (ATOMKI), P.O. Box 51, H-4001 Debreccen (Hungary); Tribedi, Lokesh C. [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India)], E-mail: lokesh@tifr.res.in

    2009-01-15

    We study electron emission from atoms and molecules in collisions with fast electrons and heavy ions (C{sup 6+}). The soft collision electrons (SE), two center electron emission (TCEE), the binary encounter (BE) events and the KLL Auger lines along with the elastically scattered peaks (in electron collisions) are studied using a hemispherical electrostatic electron analyzer. The details of the measurements along with description of the spectrometer and data acquisition system are given. The angular distributions of the low energy (few eV) electrons in soft collisions and the binary encounter electrons at keV energies are compared with quantum mechanical models based on the first Born (B1) and the continuum distorted wave-Eikonal initial state approximation (CDW-EIS)

  14. Study of Doubly Charged Delta Baryons in Collisions of Copper Nuclei at the Relativistic Heavy Ion Collider

    Science.gov (United States)

    2017-05-22

    involving heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) produce the hottest matter known to humans, approximately 100,000 times hotter... properties of the medium in which they were produced. Some of the produced particles, known collectively as “resonances,” have lifetimes comparable to the...lifetime of the col- lision medium itself. More specifically , comparative studies of the relative pro- duction of short-lived resonances and possible

  15. An electrostatic charge state selector for ion-atom collisions: design, spectral line-shapes and performance

    International Nuclear Information System (INIS)

    Saha, Amal K.; Thulasi Ram, K.V.; Tribedi, L.C.; Fernandes, W.A.; Narvekar, S.D.; Nanal, V.; Kurup, M.B.; Prasad, K.G.; Tandon, P.N.

    1998-01-01

    An electrostatic charge state selector has been constructed for charge transfer studies in ion atom collisions. Its design and performance have been discussed illustrating with examples of some data taken using heavy ion beams from pelletron accelerator. Expressions for the determination of charge state fractions from the observed charge spectrum in voltage scanning mode of operation and also the line shapes have been discussed analytically in detail. (author)

  16. Monte-Carlo simulations on the antineutrino detection in heavy ion collisions

    International Nuclear Information System (INIS)

    Zude, E.

    1991-09-01

    Aim of the present thesis was to study, how far a large-area neutron detector with high efficiency operated at the Corporation for Heavy Ion Research in Darmstadt can also by applied for experiments on the sub-threshold antineutron production in heavy ion reactions for the study of the equation of state of highly excited nuclear matter. The experimental part consisted in the partition at the construction, the taking into operation, and the calibration measurements of the target-detector system, as well at the experiments with the LAND detector for the study of the Coulomb excitation of 136 Xe projectiles in the reaction 136 Xe+ 208 Pb at 700 respectively 800 MeV/u. Studies on the suppression of neutron events against antineutron events in the data acquisition in a typical SIS/LAND experiment on the antineutron production in heavy ion collisions were performed. The possibilities available on the level of the hardware trigger for the suppression of (multiple) neutron events were studied. Thereby resulted a reachable suppression factor of ≅ 10 -3 . Studies on the off-line analysis of antineutron events exhibited problems, which base on the high matter density in the detector. (orig./HSI) [de

  17. Bulk properties of the medium produced in relativistic heavy-ion collisions from the beam energy scan program

    Science.gov (United States)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Ajitanand, N. N.; Alekseev, I.; Anderson, D. M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Behera, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Brown, D.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chankova-Bunzarova, N.; Chatterjee, A.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elsey, N.; Engelage, J.; Eppley, G.; Esha, R.; Esumi, S.; Evdokimov, O.; Ewigleben, J.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Federicova, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A. I.; Hamed, A.; Harlenderova, A.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, B.; Huang, X.; Huang, H. Z.; Humanic, T. J.; Huo, P.; Igo, G.; Jacobs, W. W.; Jentsch, A.; Jia, J.; Jiang, K.; Jowzaee, S.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Kocmanek, M.; Kollegger, T.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulathunga, N.; Kumar, L.; Kvapil, J.; Kwasizur, J. H.; Lacey, R.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, W.; Li, Y.; Lidrych, J.; Lin, T.; Lisa, M. A.; Liu, H.; Liu, P.; Liu, Y.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, S.; Luo, X.; Ma, G. L.; Ma, L.; Ma, Y. G.; Ma, R.; Magdy, N.; Majka, R.; Mallick, D.; Margetis, S.; Markert, C.; Matis, H. S.; Meehan, K.; Mei, J. C.; Miller, Z. W.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mizuno, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nie, M.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Nonaka, T.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Ray, R. L.; Reed, R.; Rehbein, M. J.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roth, J. D.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Salur, S.; Sandweiss, J.; Saur, M.; Schambach, J.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Schweid, B. R.; Seger, J.; Sergeeva, M.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Strikhanov, M.; Stringfellow, B.; Sugiura, T.; Sumbera, M.; Summa, B.; Sun, Y.; Sun, X. M.; Sun, X.; Surrow, B.; Svirida, D. N.; Tang, A. H.; Tang, Z.; Taranenko, A.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vasiliev, A. N.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, G.; Wang, Y.; Wang, F.; Wang, Y.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y. F.; Xu, Z.; Yang, Y.; Yang, Q.; Yang, C.; Yang, S.; Ye, Z.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, Z.; Zhang, X. P.; Zhang, J. B.; Zhang, S.; Zhang, J.; Zhang, Y.; Zhang, J.; Zhang, S.; Zhao, J.; Zhong, C.; Zhou, L.; Zhou, C.; Zhu, X.; Zhu, Z.; Zyzak, M.; STAR Collaboration

    2017-10-01

    We present measurements of bulk properties of the matter produced in Au+Au collisions at √{sN N}=7.7 ,11.5 ,19.6 ,27 , and 39 GeV using identified hadrons (π±, K±, p , and p ¯) from the STAR experiment in the Beam Energy Scan (BES) Program at the Relativistic Heavy Ion Collider (RHIC). Midrapidity (|y |<0.1 ) results for multiplicity densities d N /d y , average transverse momenta 〈pT〉 , and particle ratios are presented. The chemical and kinetic freeze-out dynamics at these energies are discussed and presented as a function of collision centrality and energy. These results constitute the systematic measurements of bulk properties of matter formed in heavy-ion collisions over a broad range of energy (or baryon chemical potential) at RHIC.

  18. One of the first heavy-ion collisions with stable beams recorded by ATLAS in November 2015.

    CERN Multimedia

    ATLAS Collaboration

    2015-01-01

    One of the first heavy-ion collisions with stable beams recorded by ATLAS in November 2015. Tracks reconstructed from hits in the inner tracking detector are shown as orange arcs curving in the solenoidal magnetic field. The green and yellow bars indicate energy deposits in the Liquid Argon and Scintillating Tile calorimeters respectively.

  19. Properties of hot and dense matter created in relativistic heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Arsene, Ionut Cristian

    2009-07-01

    In this thesis we tried to characterize a few aspects of the rich field of relativistic heavy ion collisions at intermediate and high energies. In chapter 2 we used two different microscopic string models, UrQMD and QGSM, to study the formation and evolution of the locally equilibrated matter in the central zone of heavy ion collisions at energies spanning from sq root sNN approx 4 GeV up to 17.3 GeV. The calculations were performed both in the cubic central cell of fixed volume V = 5 centre dot 5 centre dot 5 fm3 and for the instantly expanding volume of homogeneous energy density. To decide whether or not equilibrium is reached we used a traditional approach based on the fulfillment of the conditions of kinetic, thermal and chemical equilibrium. Both models favor the formation of equilibrated matter for a period of about 10 fm/c in which the matter expands isentropically with constant entropy per baryon. The square of the speed of sound c{sub s}2 has been found to vary in UrQMD from 0.13 at AGS to 0.15 at SPS energies and in QGSM from 0.11 at AGS to 0.15 at SPS. In both models the rise in c{sub s}2 slows down at sq rootsNN approx 9 GeV. Chapter 3 describes the HYDJET++ model as a superposition of the soft, hydrotype state and the hard state resulting from multi-parton fragmentation. Both states are treated independently. The hard part is an NN collision generator called PYQUEN which modifies the 'standard' jet event obtained with the PYTHIA generator and includes radiative and collisional energy loss for partons. Initial state effects like shadowing are included also. The soft part is the thermal hadronic state generated on the chemical and thermal freeze-out hypersurfaces obtained from the parametrization of relativistic hydrodynamics. We found that this model gives a good description of soft observables at top RHIC energy, like the p{sub T} spectrum, elliptic flow and HBT correlations. The hard part of the model describes well the high-p{sub T

  20. Single-electron capture collisions of ground and metastable Ne2+ ions with molecular gases

    Science.gov (United States)

    Hasan, A.; Abu-Haija, O.; Harris, J.; Elkafrawy, T.; Kayani, A.; Kamber, E. Y.

    2013-09-01

    Using the translational energy-gain spectroscopy technique, we have measured the energy-gain spectra and absolute total cross sections for single-electron capture in collisions of Ne2+ with N2, CO2 and H2O at laboratory impact energies between 50 and 400 eV and 0° scattering angles. In all the collision systems studied here, reaction channels have been observed which indicate the presence of the long-lived metastable states of (2s2 2p4 1D and 1S) in the Ne2+ incident beam. These measurements also indicate that capture from the metastable states into excited states of the projectile product ions is the most important inelastic process. Contributions from capture accompanied by the excitation and ionization of the target product are also detected. In addition, the energy dependence of the total single-electron capture cross sections is studied and found to slowly increase with increasing impact energy. The present data are compared with the theoretical calculations of the classical over the barrier, extended classical over the barrier and Landau-Zener models.

  1. Dynamical initial-state model for relativistic heavy-ion collisions

    Science.gov (United States)

    Shen, Chun; Schenke, Björn

    2018-02-01

    We present a fully three-dimensional model providing initial conditions for energy and net-baryon density distributions in heavy-ion collisions at arbitrary collision energy. The model includes the dynamical deceleration of participating nucleons or valence quarks, depending on the implementation. The duration of the deceleration continues until the string spanned between colliding participants is assumed to thermalize, which is either after a fixed proper time, or a fluctuating time depending on sampled final rapidities. Energy is deposited in space time along the string, which in general will span a range of space-time rapidities and proper times. We study various observables obtained directly from the initial-state model, including net-baryon rapidity distributions, two-particle rapidity correlations, as well as the rapidity decorrelation of the transverse geometry. Their dependence on the model implementation and parameter values is investigated. We also present the implementation of the model with 3+1-dimensional hydrodynamics, which involves the addition of source terms that deposit energy and net-baryon densities produced by the initial-state model at proper times greater than the initial time for the hydrodynamic simulation.

  2. Intermediate energies heavy ion collisions : study of the charged particles emission dynamics and emitters characterization

    International Nuclear Information System (INIS)

    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, 40 Ar+Al, 40 Ar+Cu and 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

  3. Particle and jet production in heavy-ion collisions with the ATLAS detector at LHC

    CERN Document Server

    Debbe, R; The ATLAS collaboration

    2012-01-01

    Particles and jets produced in heavy ion collisions are used to understand the hot, dense matter created in these interactions. Because of its wide angular coverage, highly hermetic design, and high pT capabilities, the ATLAS detector at the LHC provides an ideal environment in which to study these collisions. ATLAS has measured a wide variety of observables characterizing the bulk medium properties as well as the response of the medium to high-pT probes. Measurements have been made of charged particle multiplicity, elliptic flow, and higher-order particle flow, which allow characterization of global properties of the system. For the first time at this energy, elliptic and higher order flow has been measured over 5 units of pseudorapidity, from -2.5 to 2.5, and over a broad range in transverse momentum, 0.5-20 GeV. The higher-order particle flow studies are providing new insight into the role of initial state geometric fluctuations in these observables, with results obtained for the first through the sixth Fo...

  4. Open heavy flavor and other hard probes in ultra-relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Uphoff, Jan

    2013-01-01

    In this thesis hard probes are studied in the partonic transport model BAMPS (Boltzmann Approach to MultiParton Scatterings). Employing Monte Carlo techniques, this model describes the 3+1 dimensional evolution of the quark gluon plasma phase in ultra-relativistic heavy-ion collisions by propagating all particles in space and time and carrying out their collisions according to the Boltzmann equation. Since hard probes are produced in hard processes with a large momentum transfer, the value of the running coupling is small and their interactions should be describable within perturbative QCD (pQCD). This work focuses on open heavy flavor, but also addresses the suppression of light parton jets, in particular to highlight differences due to the mass. For light partons, radiative processes are the dominant contribution to their energy loss. For heavy quarks, we show that also binary interactions with a running coupling and an improved Debye screening matched to hard-thermal-loop calculations play an important role. Furthermore, the impact of the mass in radiative interactions, prominently named the dead cone effect, and the interplay with the Landau-Pomeranchuk-Migdal (LPM) effect are studied in great detail. Since the transport model BAMPS has access to all medium properties and the space time information of heavy quarks, it is the ideal tool to study the dissociation and regeneration of J/ψ mesons, which is also investigated in this thesis.

  5. Electron emission following collisions between multi-charged ions and D2 molecules

    International Nuclear Information System (INIS)

    Laurent, G.

    2004-05-01

    Dissociative ionisation mechanisms induced in collisions involving a highly charged ion (S 15+ , 13.6 MeV/u) and a molecular deuterium target, have been studied through momentum vector correlations of both the D + 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)

  6. Time ordering of two-step processes in energetic ion-atom collisions: Basic formalism

    International Nuclear Information System (INIS)

    Stolterfoht, N.

    1993-01-01

    The semiclassical approximation is applied in second order to describe time ordering of two-step processes in energetic ion-atom collisions. Emphasis is given to the conditions for interferences between first- and second-order terms. In systems with two active electrons, time ordering gives rise to a pair of associated paths involving a second-order process and its time-inverted process. Combining these paths within the independent-particle frozen orbital model, time ordering is lost. It is shown that the loss of time ordering modifies the second-order amplitude so that its ability to interfere with the first-order amplitude is essentially reduced. Time ordering and the capability for interference is regained, as one path is blocked by means of the Pauli exclusion principle. The time-ordering formalism is prepared for papers dealing with collision experiments of single excitation [Stolterfoht et al., following paper, Phys. Rev. A 48, 2986 (1993)] and double excitation [Stolterfoht et al. (unpublished)

  7. $W$ boson production in ultrarelativistic heavy-ion collisions at the CERN LHC

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00356981

    Ultrarelativistic heavy-ion collisions at the CERN Large Hadron Collider (LHC) are capable of producing a medium of deconfined quarks and gluons. This phase of nuclear matter is called a Quark-Gluon Plasma (QGP) and is believed to have been present during the first microseconds following the Big Bang. $\\Wboson$ bosons are a unique probe in a QGP since they do not carry color charge and thus do not interact with a strongly-coupled medium. Furthermore, the kinematics of $\\Wboson$ bosons are sensitive to the Bjorken momentum fraction $x$ of partons within nucleons, and therefore $\\Wboson$ bosons may also be used to constrain parton distribution functions and to detect the presence of nuclear effects. This thesis presents the measurement of $\\Wboson$ boson production in the dense nuclear environment created in $\\PbPb$ collisions at a per nucleon pair center-of-mass energy $\\sqrt{s_{\\mathrm{NN}}}=2.76\\TeV$. The data for this measurement were collected with the ATLAS detector in 2011 and correspond to a...

  8. Study of Particle Production and Nuclear Fragmentation in Relativistic Heavy-Ion Collisions in Nuclear Emulsions

    CERN Multimedia

    2002-01-01

    % EMU11 \\\\ \\\\ We propose to use nuclear emulsions for the study of nuclear collisions of $^{207}$Pb, $^{197}$Au, and any other heavy-ion beams when they are available. We have, in the past, used $^{32}$S at 200A~GeV and $^{16}$O at 200A and 60A~GeV from CERN (Experiment EMU08) and at present the analysis is going on with $^{28}$Si beam from BNL at 14.5A~GeV. It will be important to compare the previous and the present investigations with the new $^{207}$Pb beam at 60-160A~GeV. We want to measure in nuclear emulsion, on an event by event basis, shower particle multiplicity, pseudorapidity density and density fluctuations of charged particles, charge multiplicity and angular distributions of projectile fragments, production and interaction cross-sections of heavily ionizing particles emitted from the target fragmentation. Special emphasis will be placed on the analysis of events produced in the central collisions which are selected on the basis of low energy fragments emitted from the target excitation. It woul...

  9. Search for signatures of phase transition and critical point in heavy ion collisions

    International Nuclear Information System (INIS)

    Tokarev, M.V.; Kechechyan, A.; Alakhverdyants, A.; Zborovsky, I.

    2011-01-01

    The general concepts in the critical phenomena related with the notions of 'scaling' and 'universality' are considered. Behavior of various systems near a phase transition is displayed. Search for clear signatures of the phase transition of the nuclear matter and location of the critical point in heavy ion collisions (HIC) is discussed. The experimental data on inclusive spectra measured in HIC at RHIC and SPS over a wide range of energies s NN 1/2 = 9-200 GeV are analyzed in the framework of z-scaling. A microscopic scenario of the constituent interactions is presented. Dependence of the energy loss on the momentum of the produced hadron, energy and centrality of the collision is studied. Self-similarity of the constituent interactions described in terms of momentum fractions is used to characterize the nuclear medium by 'specific heat' and colliding nuclei by fractal dimensions. Preferable kinematical regions to search for signatures of the phase transition of the nuclear matter produced in HIC are discussed. Discontinuity of the 'specific heat' is assumed to be a signature of the phase transition and the critical point

  10. Causal electric charge diffusion and balance functions in relativistic heavy-ion collisions

    Science.gov (United States)

    Kapusta, Joseph I.; Plumberg, Christopher

    2018-01-01

    We study the propagation and diffusion of electric charge fluctuations in high-energy heavy-ion collisions using the Cattaneo form for the dissipative part of the electric current. As opposed to the ordinary diffusion equation this form limits the speed at which charge can propagate. Including the noise term in the current, which arises uniquely from the fluctuation-dissipation theorem, we calculate the balance functions for charged hadrons in a simple 1+1-dimensional Bjorken hydrodynamical model. Limiting the speed of propagation of charge fluctuations increases the height and reduces the width of these balance functions when plotted versus rapidity. We also estimate the numerical value of the associated diffusion time constant from anti-de Sitter-space/conformal-field theory.

  11. Inclusive reconstruction of hadron resonances in elementary and heavy-ion collisions with HADES

    Directory of Open Access Journals (Sweden)

    Kornakov Georgy

    2016-01-01

    Full Text Available The unambiguous identification of hadron modifications in hot and dense QCD matter is one of the important goals in nuclear physics. In the regime of 1 - 2 GeV kinetic energy per nucleon, HADES has measured rare and penetrating probes in elementary and heavy-ion collisions. The main creation mechanism of mesons is the excitation and decay of baryonic resonances throughout the fireball evolution. The reconstruction of shortlived (≈ 1 fm/c resonance states through their decay products is notoriously difficult. We have developed a new iterative algorithm, which builds the best hypothesis of signal and background by distortion of individual particle properties. This allows to extract signals with signal-to-background ratios of <1%.

  12. Heavy Quark Correlations and J / Φ Production in Heavy Ion Collisions

    Science.gov (United States)

    Niazi, Reza; Liu, Yunpeng; Ko, Che-Ming

    2014-09-01

    Quark Gluon Plasma (QGP), a phase of QCD matter, was the temporary state that all matter had in the universe microseconds after its creation, which has been produced in high energy nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Normally being bound inside a proton or neutron, due to the strong nuclear force, the QGP is a hot ``soup'' of quarks and gluons that move relatively freely. QGP is still a very enigmatic state of matter; therefore, active work is being done in trying to understand what is left behind after this short-lived state of matter disintegrates. This includes the abundance of the charmonium meson that consists of a pair of heavy charm and anticharm quarks. In this study, a QGP simulation called the Parton Cascade Model is used with two different initial conditions to see if charm and anticharm quarks can create a charmonium meson in the expanding QGP. In the simulation, the charm quark pair is initially either correlated, with opposite momenta but same position, or uncorrelated, with random momenta and positions, within the QGP. Understanding the difference of the amount of charmonium mesons produced in these two conditions will be helpful in developing theoretical models for charmonium production in heavy ion collisions and thus determining the properties of QGP from experimental measurements. Quark Gluon Plasma (QGP), a phase of QCD matter, was the temporary state that all matter had in the universe microseconds after its creation, which has been produced in high energy nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Normally being bound inside a proton or neutron, due to the strong nuclear force, the QGP is a hot ``soup'' of quarks and gluons that move relatively freely. QGP is still a very enigmatic state of matter; therefore, active work is being done in trying to understand what is left behind after this short

  13. Multi-neutron and proton transfer reactions in deep inelastic heavy-ion collisions

    International Nuclear Information System (INIS)

    Yoshida, Satoshi; Patra, S.K.; Takigawa, Noboru

    1997-01-01

    We discuss the characteristics of multi-nucleon transfer reactions in deep-inelastic heavy-ion collisions. We calculate the number of transferred neutrons and protons based on a macroscopic approach using a Fokker-Planck equation, and compare with experimental data. We show that our macroscopic approach well reproduces the experimental data concerning the ratio of the mass to the proton numbers in the projectile-like fragment as a function of the energy loss from the relative motion. Our calculations, however, do not reproduce the recent data, where the transferred number of neutrons and protons are measured separately. The net flow of nucleons evolve even in opposite directions in the experimental data and in our transport theory. (author)

  14. Simulating V+jet processes in heavy ion collisions with JEWEL

    CERN Document Server

    Kunnawalkam Elayavalli, Raghav

    2016-01-01

    Processes in which a jet recoils against an electroweak boson complement studies of jet quenching in heavy ion collisions at the LHC. As the boson does not interact strongly it escapes the dense medium unmodified and thus provides a more direct access to the hard scattering kinematics than can be obtained in di-jet events. First measurements of jet modification in these processes are now available from the LHC experiments and will improve greatly with better statistics in the future. We present an extension of JEWEL to boson-jet processes. JEWEL is a dynamical framework for jet evolution in a dense background based on perturbative QCD, that is in agreement with a large variety of jet observables. We also obtain a good description of the CMS and ATLAS data for y+jet and Z+jet processes at 2.76 TeV and 5.02 TeV.

  15. Classical charge-transfer and ionization channels for ion collisions with circular Rydberg atoms

    Science.gov (United States)

    Homan, Dean M.; Cavagnero, Michael J.; Harmin, David A.

    1995-03-01

    Explorations of the classical phase space for ion collisions with circular Rydberg atoms are presented. Intermediate-energy capture and ionization processes are studied through the numerical integration of Newton's equations of motion and through the graphical depiction of the outcomes of large numbers of trajectories. Maps which correlate initial conditions with final outcomes are used to identify zones of parameter space leading to Thomas capture, direct capture, binary-encounter ionization, saddle-point ionization, and ionization by S superpromotion (E. A. Solov'ev, Zh. Eksp. Teor. Fiz. 81, 1681 (1981) [Sov. Phys. JETP 54, 893 (1981)]). Charge-transfer channels in which the electron passes once or three times through the midplane between the nuclei are shown to occur in separate zones of parameter space over the entire range of projectile speeds above the mean velocity of the target electron.

  16. Kinetic evolution of the glasma and thermalization in heavy-ion collisions

    International Nuclear Information System (INIS)

    Huang, Xuguang; Liao, Jinfeng

    2014-01-01

    In relativistic heavy-ion collisions, a highly occupied gluonic matter is created shortly after initial impact, which is in a nonthermal state and often referred to as the Glasma. Successful phenomenology suggests that the glasma evolves rather quickly toward the thermal quark–gluon plasma (QGP) and a hydrodynamic behavior emerges at a very early time ~ô(1) fm/c. Exactly how such 'apparent thermalization' occurs and connects the initial conditions to the hydrodynamic onset, remains a significant challenge for theory as well as phenomenology. We briefly review various ideas and recent progress in understanding the approach of the glasma to the thermalized QGP, with an emphasis on the kinetic theory description for the evolution of such far-from-equilibrium and highly overpopulated, thus weakly-coupled yet strongly interacting glasma. (author)

  17. Simulation of heavy ion collisions at √s = 20--200 GeV

    International Nuclear Information System (INIS)

    Kahana, D.E.; Kahana, S.H.; Brookhaven National Lab., Upton, NY

    1996-11-01

    A new hadronic cascade code (LUCIFER) is introduced, for simulation of relativistic heavy ion collisions at CERN energies and up to RHIC. It is based on a simple, experimentally and theoretically motivated picture of hh interactions. Final state hadrons are produced by decay of intermediate state clusters, or lumps of excited hadronic matter. These are similar to resonances, but have a continuous mass distribution. Clusters are the objects that re-interact in the cascade. Single diffractive dissociation is used to fix the cluster properties. The model has just two parameters: τ d , the decay time of the clusters, and τ f the formation time of the clusters. Comparison is made with recent CERN data in the Pb + Pb system. The first consistent cascade simulation, of J/ψ production/suppression is presented. It appears likely that a purely hadronic interpretation can be given to recent CERN data on apparently anomalous J/ψ suppression in Pb + Pb

  18. Simulation of heavy ion collisions at {radical}s = 20--200 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Kahana, D.E.; Kahana, S.H. [State Univ. of New York, Stony Brook, NY (United States). Physics Dept.]|[Brookhaven National Lab., Upton, NY (United States). Physics Dept.

    1996-11-01

    A new hadronic cascade code (LUCIFER) is introduced, for simulation of relativistic heavy ion collisions at CERN energies and up to RHIC. It is based on a simple, experimentally and theoretically motivated picture of hh interactions. Final state hadrons are produced by decay of intermediate state clusters, or lumps of excited hadronic matter. These are similar to resonances, but have a continuous mass distribution. Clusters are the objects that re-interact in the cascade. Single diffractive dissociation is used to fix the cluster properties. The model has just two parameters: {tau}{sub d}, the decay time of the clusters, and {tau}{sub f} the formation time of the clusters. Comparison is made with recent CERN data in the Pb + Pb system. The first consistent cascade simulation, of J/{psi} production/suppression is presented. It appears likely that a purely hadronic interpretation can be given to recent CERN data on apparently anomalous J/{psi} suppression in Pb + Pb.

  19. Entropy of a system formed in the collision of heavy ions

    International Nuclear Information System (INIS)

    Gudima, K.K.; Roepke, G.; Toneev, V.D.; Schulz, H.

    1987-01-01

    In the framework of the cascade model, we study the evolution of the entropy of a system formed in the collision of heavy ions. The method of calculating the entropy is based on a smoothing of the momentum distribution function by means of introducing a temperature field. It is shown that the resulting entropy per nucleon is very sensitive to the specific partitioning of phase space into cells in the free-expansion phase of the reaction. From comparison with experiment it is found that the cascade calculations do not show a preference for a particular model calculation of the entropy, but predict that the entropy is smaller than the values following from equilibrium statistics

  20. Equilibration of a three component nuclear system in heavy-ion collisions

    International Nuclear Information System (INIS)

    Rosenhauer, A.; Csernai, L.P.; Maruhn, J.A.; Greiner, W.

    1984-01-01

    A system of three different nuclear matter components is introduced to describe the nucleons participating in a high-energy heavy-ion reaction. The first and second component is attributed to the nucleons of target and projectile, while a third component is taken into account to study the formation of thermalized matter in the course of the reaction. It is assumed that the distributions of the incoming nuclei are equilibrated ones and that collisions of nucleons belonging to different distribution components populate the thermalized matter component. Then, by means of Boltzmann transport theory, the time evolution of such a three-component system for infinite uniform nuclear matter is calculated. The process of thermal equilibration is studied and the results are compared to the ones of other kinetic model calculations. Observable signs of the equilibration process are pointed out. (Auth.)

  1. Effects of ρ-meson width on pion distributions in heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    Pasi Huovinen

    2017-06-01

    Full Text Available The influence of the finite width of ρ meson on the pion momentum distribution is studied quantitatively in the framework of the S-matrix approach combined with a blast-wave model to describe particle emissions from an expanding fireball. We find that the proper treatment of resonances which accounts for their production dynamics encoded in data for partial wave scattering amplitudes can substantially modify spectra of daughter particles originating in their two body decays. In particular, it results in an enhancement of the low-pT pions from the decays of ρ mesons which improves the quantitative description of the pion spectra in heavy ion collisions obtained by the ALICE collaboration at the LHC energy.

  2. Collective Longitudinal Polarization in Relativistic Heavy-Ion Collisions at Very High Energy

    Science.gov (United States)

    Becattini, F.; Karpenko, Iu.

    2018-01-01

    We study the polarization of particles in relativistic heavy-ion collisions at very high energy along the beam direction within a relativistic hydrodynamic framework. We show that this component of the polarization decreases much slower with center-of-mass energy compared to the transverse component, even in the ideal longitudinal boost-invariant scenario with nonfluctuating initial state, and that it can be measured by taking advantage of its quadrupole structure in the transverse momentum plane. In the ideal longitudinal boost-invariant scenario, the polarization is proportional to the gradient of temperature at the hadronization and its measurement can provide important information about the cooling rate of the quark-gluon plasma around the critical temperature.

  3. Characterization of initial fluctuations for the hydrodynamical description of heavy ion collisions

    CERN Document Server

    Floerchinger, Stefan

    2013-01-01

    Event-by-event fluctuations in the initial conditions for a hydrodynamical description of heavy-ion collisions are characterized. We propose a Bessel-Fourier decomposition with respect to the azimuthal angle, the radius in the transverse plane and rapidity. This allows for a complete characterization of fluctuations in all hydrodynamical fields including energy density, pressure, fluid velocity, shear stress and bulk viscous pressure. It has the advantage that fluctuations can be ordered with respect to their wave length and that they can be propagated mode-by-mode within the hydrodynamical formalism. Event ensembles can then be characterized in terms of a functional probability distribution. For the event ensemble of a Monte Carlo Glauber model, we provide evidence that the latter is close to Gaussian form, thus allowing for a particularly simple characterization of the event distribution.

  4. Proceedings of the 2nd joint seminar on atomic collisions and heavy ion induced nuclear reactions

    International Nuclear Information System (INIS)

    Harada, Kichinosuke; Ozawa, Kunio; Kamitsubo, H.; Nomura, T.; Awaya, Y.; Watanabe, T.

    1982-11-01

    The meeting of the 2nd joint seminar on atomic collisions and heavy ion induced nuclear reactions was held at the University of Tokyo, May 13 and 14, 1982. The aim of this seminar has been not only to recognize the common problems lying between above two research fields, but also to obtain an overview of the theoretical and experimental approaches to clear the current problems. In the seminar, more than 50 participants gathered and presented 16 papers. These are two general reviews and fourteen comprehensive surveys on topical subjects which have been developed very intensively in recent years. The editors would like to thank all participants for their assistance and cooperation in making possible a publication of these proceedings. (author)

  5. Effects of ρ-meson width on pion distributions in heavy-ion collisions

    Science.gov (United States)

    Huovinen, Pasi; Lo, Pok Man; Marczenko, Michał; Morita, Kenji; Redlich, Krzysztof; Sasaki, Chihiro

    2017-06-01

    The influence of the finite width of ρ meson on the pion momentum distribution is studied quantitatively in the framework of the S-matrix approach combined with a blast-wave model to describe particle emissions from an expanding fireball. We find that the proper treatment of resonances which accounts for their production dynamics encoded in data for partial wave scattering amplitudes can substantially modify spectra of daughter particles originating in their two body decays. In particular, it results in an enhancement of the low-pT pions from the decays of ρ mesons which improves the quantitative description of the pion spectra in heavy ion collisions obtained by the ALICE collaboration at the LHC energy.

  6. Chiral symmetry restoration versus deconfinement in heavy-ion collisions at high baryon density

    Science.gov (United States)

    Bratkovskaya, E. L.; Palmese, A.; Cassing, W.; Seifert, E.; Steinert, T.; Moreau, P.

    2017-07-01

    The effect of the chiral symmetry restoration (CSR) on observables from heavy-ion collisions is studied in the energy range \\sqrt{{s}NN}=3-20 {GeV} within the Parton-Hadron-String Dynamics (PHSD) transport approach. The PHSD includes the deconfinement phase transition as well as essential aspects of CSR in the dense and hot hadronic medium, which are incorporated in the Schwinger mechanism for the hadronic particle production. We adopt different parametrizations of the nuclear equation of state from the non-linear σ - ω model, which enter in the computation of the quark scalar density for the CSR mechanism, in order to estimate the uncertainty in our calculations. For the pion-nucleon Σ-term we adopt Σ π ≈ 45 MeV which corresponds to some ‘world average’. Our systematic studies show that chiral symmetry restoration plays a crucial role in the description of heavy-ion collisions at \\sqrt{{s}NN}=3-20 {GeV}, realizing an increase of the hadronic particle production in the strangeness sector with respect to the non-strange one. We identify particle abundances and rapidity spectra to be suitable probes in order to extract information about CSR, while transverse mass spectra are less sensitive. Our results provide a microscopic explanation for the “horn” structure in the excitation function of the K +/π + ratio: the CSR in the hadronic phase produces the steep increase of this particle ratio up to \\sqrt{{s}NN}≈ 7 {GeV}, while the drop at higher energies is associated to the appearance of a deconfined partonic medium.

  7. Heavy flavor in heavy-ion collisions at RHIC and RHIC II

    Energy Technology Data Exchange (ETDEWEB)

    Frawley, A D; Ullrich, T; Vogt, R

    2008-03-30

    In the initial years of operation, experiments at the Relativistic Heavy Ion Collider (RHIC) have identified a new form of matter formed in nuclei-nuclei collisions at energy densities more than 100 times that of a cold atomic nucleus. Measurements and comparison with relativistic hydrodynamic models indicate that the matter thermalizes in an unexpectedly short time, has an energy density at least 15 times larger than needed for color deconfinement, has a temperature about twice the critical temperature predicted by lattice QCD, and appears to exhibit collective motion with ideal hydrodynamic properties--a 'perfect liquid' that appears to flow with a near-zero viscosity to entropy ratio--lower than any previously observed fluid and perhaps close to a universal lower bound. However, a fundamental understanding of the medium seen in heavy-ion collisions at RHIC does not yet exist. The most important scientific challenge for the field in the next decade is the quantitative exploration of the new state of nuclear matter. That will require new data that will, in turn, require enhanced capabilities of the RHIC detectors and accelerator. In this report we discuss the scientific opportunities for an upgraded RHIC facility --RHIC II--in conjunction with improved capabilities of the two large RHIC detectors, PHENIX and STAR. We focus solely on heavy flavor probes. Their production rates are calculable using the well-established techniques of perturbative QCD and their sizable interactions with the hot QCD medium provide unique and sensitive measurements of its crucial properties making them one of the key diagnostic tools available to us.

  8. Head-on collision of ion-acoustic solitons in an ultracold neutral plasma

    Science.gov (United States)

    El-Tantawy, S. A.; Moslem, W. M.; Sabry, R.; El-Labany, S. K.; El-Metwally, M.; Schlickeiser, R.

    2014-03-01

    Properties of ion acoustic solitons head-on collision in an ultracold neutral plasma composed of ion fluid and non-Maxwellian electron distributions are investigated. For this purpose, the extended Poincare-Lighthill-Kuo (PLK) method is employed to derive coupled Kortweg-de Vries (KdV) equations describing the system. The nonlinear evolution equations for the colliding solitons and corresponding phase shifts are investigated both analytically and numerically. It is found that the polarity of the colliding solitons strongly depends on the type of the non-Maxwellian distribution (via nonthermal or superthermal electron distributions). Especially the phase shift due to solitons collision is strongly influenced by the non-Maxwellian distribution. A new critical nonthermal parameter β c , characterizing the nonthermal electron distribution, and which is not present for superthermal particle distributions, allows the existence of double polarity of the solitons. The phase shift increases below β c for compressive solitons, but it decreases above β c for rarefactive soliton. For superthermal distribution the phase shift increases rapidly for low spectral index κ, whereas for higher values of κ, the phase shift decreases smoothly and becomes nearly stable for κ>10. Around β c and small values of κ, the deviation from the Maxwellian state is strongest, and therefore the phase shift has unexpected behavior due to the presence of more energetic electrons that are represented by the non-Maxwellian distributions. The nonlinear structure, as reported here, could be useful for controlling the solitons that may be created in future ultracold neutral plasma experiments.

  9. Studies of the QCD Phase Diagram with Heavy-Ion Collisions at J-PARC

    Science.gov (United States)

    Sako, Hiroyuki

    To clarify phase structures in the QCD phase diagram is an ultimate goal of heavy-ion collision experiments. Studies of internal structures of neutron stars are also one of the most important topics of nuclear physics since the discovery of neutron stars with two-solar mass. For these physics goals, J-PARC heavy-ion project (J-PARC-HI) has been proposed, where extremely dense matter with 5-10 times the normal nuclear density will be created. Heavy-ion beams up to Uranium will be accelerated to 1-19 AGeV/c, with the designed world's highest beam rate of 1011 Hz. The acceleration of such high-rate beams can be realized by a new heavy-ion linac and a new booster ring, in addition to the existing 3-GeV and 50-GeV proton synchrotrons. To study the above physics goals, following physics observables will be measured in extremely high statistics expected in J-PARC-HI. To search for the critical point, high-order event-by-event fluctuations of conserved charges such as a net-baryon number, an electric charge number, and a strangeness number will be measured. To study the chiral symmetry restoration, dilepton spectra from light vector meson decays will be measured. Also, collective flows, particle correlations will be measured to study the equation of state and hyperon-hyperon and hyperon-nucleon interactions related to neutron stars. Strange quark matter (strangelet) and multi-strangeness hypernuclei will be searched for which may be related directly to the matter constituting the neutron star core. In this work, the physics goals, the experimental design, and expected physics results of J-PARC-HI will be discussed.

  10. X-ray emission in heavy-ion collisions. Progress report, April 1, 1979-March 31, 1980

    International Nuclear Information System (INIS)

    Watson, R.L.

    1980-04-01

    Recent research in the cyclotron institute and department of chemistry at Texas A and M University on the x-ray emission in heavy-ion collisions is described. Areas covered include: spectra of Ka x-rays from 64 MeV sulfur ions traveling in solids; foil-excited Ka x-ray transitions in few-electron sulfur ions; high-resolution study of the target thickness dependence of x-ray emission from 65 MeV sulfur ions; dynamic screening of highly stripped sulfur ions in solids; Mg Ka x-ray satellites excited by ion bombardment, multiplet structure and dependence on projectile and chemical environment; angular distributions of beam and target Ka x-rays; chemical effects on K x-ray satellites of fluorine compounds; and a non-linear least-squares peak-fitting program employing Voight functions

  11. Observation of luminescent spectra in low energy ion-neutral collisions. Progress report, June 1, 1976--May 31, 1978

    International Nuclear Information System (INIS)

    Leventhal, J.J.

    1978-01-01

    The experiments reported provide detailed information on the fundamental nature of energy transfer processes in ion-molecule or atom-molecule collisions. By combining ion beam techniques with emission spectroscopy, data are obtained which directly lead to internal energy state distributions of atomic and molecular products of these collisions. Data are in the form of emission spectra from nascent energetically excited species formed in the energy transfer process. Changes in the collision-produced spectra as a function of beam kinetic energy yield information on the extent of energy conversion (kinetic → internal) in the collision process. Some of the specific energy transfer processes studied are applicable to the problem of achieving inverted energy level populations in high pressure gas lasers. Also discussed are experiments designed to test theoretical models which predict product energy partitioning in molecular collisions. Because experimentally determined energy state distributions deviate substantially from the predicted distributions it is concluded that additional theoretical work is needed. A simple model was developed which qualitatively reproduces the important features of the data. This model, which is considerably more general than those previously available is outlined and briefly discussed

  12. X-ray emission in collisions of highly charged I, Pr, Ho, and Bi ions with a W surface

    International Nuclear Information System (INIS)

    Watanabe, H.; Tona, M.; Ohtani, S.; Sun, J.; Nakamura, N.; Yamada, C.; Yoshiyasu, N.; Sakurai, M.

    2007-01-01

    X-ray emission yields, which are defined as the total number of emitted x-ray photons per incident ion, and dissipated fractions of potential energies through x-ray emission have been measured for slow highly charged ions of I, Pr, Ho, and Bi colliding with a W surface. A larger amount of potential energy was consumed for the x-ray emission with increasing the atomic number and the charge state. The present measurements show that x-ray emission is one of the main decay channels of hollow atoms produced in collisions of very highly charged ions of heavy elements

  13. Systematic investigation of negative Cooper-Frye contributions in heavy ion collisions using coarse-grained molecular dynamics

    Science.gov (United States)

    Oliinychenko, D.; Huovinen, P.; Petersen, H.

    2015-02-01

    In most heavy ion collision simulations involving relativistic hydrodynamics, the Cooper-Frye formula is applied to transform the hydrodynamical fields to particles. In this article the so-called negative contributions in the Cooper-Frye formula are studied using a coarse-grained transport approach. The magnitude of negative contributions is investigated as a function of hadron mass, collision energy in the range of Elab=5 -160 A GeV, collision centrality, and the energy density transition criterion defining the hypersurface. The microscopic results are compared to negative contributions expected from hydrodynamical treatment assuming local thermal equilibrium. The main conclusion is that the number of actual microscopic particles flying inward is smaller than the negative contribution one would expect in an equilibrated scenario. The largest impact of negative contributions is found to be on the pion rapidity distribution at midrapidity in central collisions. For this case negative contributions in equilibrium constitute 8-13% of positive contributions, depending on collision energy, but only 0.5-4% in cascade calculation. The dependence on the collision energy itself is found to be nonmonotonous with a maximum at 10 - 20 A GeV.

  14. Electron loss from hydrogen-like highly charged ions in collisions with electrons, protons and light atoms

    Science.gov (United States)

    Lyashchenko, K. N.; Andreev, O. Yu; Voitkiv, A. B.

    2018-03-01

    We consider electron loss from a hydrogen-like highly charged ion (HCI) in relativistic collisions with hydrogen and helium in the range of impact velocities v min ≤ v ≤ v max (v min and v max correspond to the threshold energy ε th for electron loss in collisions with a free electron and to ≈5 ε th, respectively) where any reliable data for loss cross sections are absent. In this range, where the loss process is characterized by large momentum transfers, we express it in terms of electron loss in collisions with equivelocity protons and electrons and explore by performing a detailed comparative study of these subprocesses. Our results, in particular, show that: (i) compared to equivelocity electrons protons are more effective in inducing electron loss, (ii) the relative effectiveness of electron projectiles grows with increase in the atomic number of a HCI, (iii) collisions with protons and electrons lead to a qualitatively different population of the final-state-electron momentum space and even when the total loss cross sections in these collisions become already equal the spectra of the outgoing electrons still remain quite different in almost the entire volume of the final-state-electron momentum space, (iv) in collisions with hydrogen and helium the contributions to the loss process from the interactions with the nucleus and the electron(s) of the atom could be rather well separated in a substantial part of the final-state-electron momentum space.

  15. Size-to-charge dispersion of collision-induced dissociation product ions for enhancement of structural information and product ion identification.

    Science.gov (United States)

    Zinnel, Nathanael F; Russell, David H

    2014-05-20

    Ion mobility is used to disperse product ions formed by collision-induced dissociation (CID) on the basis of charge state and size-to-charge ratio. We previously described an approach for combining CID with ion mobility mass spectrometry (IM-MS) for dispersing fragment ions along charge state specific trend lines (Zinnel, N. F.; Pai, P. J.; Russell, D. H. Anal. Chem. 2012, 84, 3390; Sowell, R. A.; Koeniger, S. L.; Valentine, S. J.; Moon, M. H.; Clemmer, D. E. J. Am. Soc. Mass Spectrom. 2004, 15, 1341; McLean, J. A.; Ruotolo, B. T.; Gillig, K. J.; Russell, D. H. Int. J. Mass Spectrom. 2005, 240, 301), and this approach was used to assign metal ion binding sites for human metallothionein protein MT-2a (Chen, S. H.; Russell, W. K.; Russell, D. H. Anal. Chem. 2013, 85, 3229). Here, we use this approach to distinguish b-type N-terminal fragment ions from both internal fragment ions and y-type C-terminal fragment ions. We also show that in some cases specific secondary structural elements, viz., extended coils or helices, can be obtained for the y-type fragment ions series. The advantage of this approach is that product ion identity can be correlated to gas-phase ion structure, which provides rapid identification of the onset and termination of extended coil structure in peptides.

  16. Atomic collision experiments utilizing low-velocity, highly-charged ion beams

    International Nuclear Information System (INIS)

    Johnson, B.M.; Jones, K.W.; Meron, M.

    1983-01-01

    Intense beams of highly-stripped ions are now routinely produced at low velocities using the Brookhaven dual MP-tandems in a unique four-stage accel/decel mode. This mode of operation combines three stages of acceleration, stripping at high energy, and one stage of deceleration to near-zero velocity. To date, experiments have used 10-100 nA beams of bare and few-electron heavy ions at energies as low as 0.2 MeV/amu, and upgrades of the facility should push the lower limit below 0.1 MeV/amu. Recent experiments, such as measurements of charge transfer and x-ray production for S 6 - 16 + on He and Ar at 6-20 MeV and P(b) measurements for MO x-rays produced in Cl 16 + + Ar collisions at 20, 10 and 5 MeV have demonstrated the usefulness of highly-stripped, low-velocity projectiles. These experiments and a few possibilities for future experiments are discussed

  17. Ambiguities in strong absorptionlike S functions and in the corresponding potentials for heavy-ion collisions

    International Nuclear Information System (INIS)

    Steward, C.; Fiedeldey, H.; Amos, K.; Allen, L.J.

    1995-01-01

    A semiclassical (WKB) method within fixed energy inverse scattering theory has been used to analyze the differential cross section from the elastic scattering of 1449 MeV 12 C ions off of 208 Pb and of 1503 MeV 16 O ions off of 12 C. Excellent, statistically significant, fits to the 12 C- 208 Pb experimental data have been found using a McIntyre form for the scattering function but with diverse sets of parameter values. There are corresponding diverse interaction potentials. To fit the 16 O- 12 C data, a Regge pole term was needed to supplement the McIntyre form. Inversion of those scattering functions resulted in interaction potentials that vary noticeably within the sensitive radial regions. In addition, conventional optical model potentials have been obtained with which direct solution of the Schroedinger equations result in similar excellent fits to the data. It is shown that these large ambiguities in the potentials are due, in the main, to the limited angular range of the cross-section data and although the corresponding cross-section shapes beyond the measured scattering angle range for the 12 C- 208 Pb collision vary over many orders of magnitude, it is unlikely that experiments can be made sensitive enough to select from among them because those cross sections are so small

  18. Energy loss of ions in a magnetized plasma: Conformity between linear response and binary collision treatments

    International Nuclear Information System (INIS)

    Nersisyan, H.B.; Zwicknagel, G.; Toepffer, C.

    2003-01-01

    The energy loss of a heavy ion moving in a magnetized electron plasma is considered within the linear response (LR) and binary collision (BC) treatments with the purpose to look for a connection between these two models. These two complementary approaches yield close results if no magnetic field is present, but there develop discrepancies with growing magnetic field at ion velocities that are lower than, or comparable with, the thermal velocity of the electrons. We show that this is a peculiarity of the Coulomb interaction which requires cutoff procedures to account for its singularity at the origin and its infinite range. The cutoff procedures in the LR and BC treatments are different as the order of integrations in velocity and in ordinary (Fourier) spaces is reversed in both treatments. While BC involves a velocity average of Coulomb logarithms, there appear in LR Coulomb logarithms of velocity averaged cutoffs. The discrepancies between LR and BC vanish, except for small contributions of collective modes, for smoothened potentials that require no cutoffs. This is shown explicitly with the help of an improved BC in which the velocity transfer is treated up to second order in the interaction in Fourier space

  19. Atomic collision experiments utilizing low-velocity, highly-charged ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, B.M.; Jones, K.W.; Meron, M.

    1982-01-01

    Intense beams of highly-stripped ions are now routinely produced at low velocities using the Brookhaven dual MP-tandens in a unique four-stage accel/decel mode. This mode of operation combines three stages of acceleration, stripping at high energy, and one stage of deceleration to near-zero velocity. To date, experiments have used 10-100 nA beams of bare and few-electron heavy ions at energies as low as 0.2 MeV/amu, and upgrades of the facility should push the lower limit below 0.1 MeV/amu. Recent experiments, such as measurements of charge transfer and x-ray production for S/sup 6-16+/ on He and Ar at 6 to 20 MeV and P(b) measurements for MO x-rays produced in Cl/sup 16 +/ + Ar collisions at 20, 10, and 5 MeV have demonstrated the usefulness of highly-stripped, low-velocity projectiles. These experiments and a few possibilities for future experiments are discussed.

  20. A review on recent light particle correlation data from heavy ion collisions at intermediate and low energies

    International Nuclear Information System (INIS)

    Ardouin, D.

    1996-01-01

    A review of recent two-particle interferometry data for heavy-ion collisions in the domain of energy between ten and a few hundreds of MeV/nucleon is presented. Not only identical particles but unlike particle correlations have been used successfully as a probe for space-time dynamics of the collision process. Due to the availability of new dedicated charged particles or photon multi-detectors, the field of particle interferometry is moving to a good level of quantitative description: excitation energy and impact parameter dependences are now provided which should stimulate additional theoretical calculations for two-particle cross sections and emission of light fragments. (author)

  1. State-to-state measurements of low-energy ion-molecule and ion-ion collisions by three dimensional momentum imaging

    Science.gov (United States)

    Urbain, Xavier

    2016-09-01

    While the measurement of total absolute cross sections remains challenging, the insight provided by differential cross sections and branching ratios is invaluable to assess the quality of theoretical predictions. Satisfactory agreement at the latter level gives better confidence in the proper identification of the reaction mechanism and key parameters. The three dimensional imaging of molecular dissociation, and more generally, the determination of all momentum vectors of the reaction products, gives direct access to the differential quantities of interest. For the prototype reaction of a proton colliding with H2, the secondary H2+current may be recorded to provide the total charge transfer yield. The dissociative charge transfer of the product ions with alkali targets leaves a characteristic signature in the total kinetic energy imparted to the H fragments. Its measurement is readily achieved by coincident detection on position sensitive detectors. This allows us to extract vibrational populations as a function of collision energy. A resonant enhancement of the charge transfer around 45 eV/amu is observed, that leaves the molecular ion in its vibrational ground state. Those observations are supported by state-of-the-art calculations. We have similarly explored the ionization of molecular oxygen by proton and alpha particle impact, at velocities characteristic of the solar wind. A somewhat more involved vibrational analysis of the O2+cations indicates a Franck-Condon like vibrational population of the ground electronic state from 50 eV to 10 keV, unlikely to modify the branching ratios of dissociative recombination, itself responsible for airglow emissions. More interestingly, a significant population of the 4Πu excited state is measured at velocities typical of the fast solar wind. Finally, we shall address the implementation of three dimensional imaging in merged ion-ion beam studies. Mutual neutralization involving anions and cations is a very efficient process

  2. An overview of experimental results from ultra-relativistic heavy-ion collisions at the CERN LHC: Hard probes

    Directory of Open Access Journals (Sweden)

    Panagiota Foka

    2016-11-01

    Full Text Available The first collisions of lead nuclei, delivered by the CERN Large Hadron Collider (LHC at the end of 2010, at a centre-of-mass energy per nucleon pair sNN= 2.76 TeV, marked the beginning of a new era in ultra-relativistic heavy-ion physics. The study of the properties of the produced hot and dense strongly-interacting matter at these unprecedented energies is currently experimentally pursued by all four big LHC experiments, ALICE, ATLAS, CMS, and LHCb. The more than a factor 10 increase of collision energy at LHC, relative to the previously achieved maximal energy at other collider facilities, results in an increase of production rates of hard probes. This review presents selected experimental results focusing on observables probing hard processes in heavy-ion collisions delivered during the first three years of the LHC operation. It also presents the first results from Run 2 heavy-ion data at the highest energy, as well as from the studies of the reference pp and p–Pb systems, which are an integral part of the heavy-ion programme.

  3. Collision integrals for the interaction of the ions of nitrogen and oxygen in a plasma at high temperatures and pressures

    Science.gov (United States)

    Stallcop, James R.; Partridge, Harry; Levin, E.

    1992-01-01

    The corrections to the transport cross-sections and collision integrals for Coulomb interactions arising from the application of realistic interaction energies of the ions of nitrogen and oxygen are investigated. Accurate potential-energy curves from an ab initio electronic-structure calculation and a semiclassical description of the scattering are used to determine the difference between the cross-sections for the real interaction forces and a Coulomb force for large values of the Debye shielding parameter. Graphs of the correction to the diffusion and viscosity-collision integrals are presented for temperatures from about 10,000 K to 150,000 K. This correction can be combined with tabulations of the collision integrals for shielded Coulomb potentials to determine the contribution of N(+)-N(+), N(+)-O(+), and O(+)-O(+) interactions to the transport properties of high-temperature air. Analytical forms are fitted to the calculated results to assist this application.

  4. 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)

  5. Charge breeding investigation in EBIS/T and collision study of ions with cold atoms for HITRAP

    Energy Technology Data Exchange (ETDEWEB)

    Sokolov, Alexey

    2010-01-29

    Highly charged ions (HCI) at low velocities or at rest are interesting systems for various atomic physics experiments. For investigations on HCI of heavy stable or radioactive nuclides the HITRAP (Highly charged Ion TRAP) decelerator facility has been set up at GSI to deliver cooled beams of HCI at an energy of 5 keV/q. The HCI are produced in a stripper foil at relativistic energies and are decelerated in several steps at ESR storage ring and HITRAP before they are delivered to experimental setups. One of the experiments is the investigation of multi-electron charge exchange in collisions of heavy HCI with cold atoms using novel MOTRIMS technique. Collision experiments on light ions from an ECR ion source colliding with cold atoms in a MOT have been performed and the results are described. An electron beam ion trap (EBIT) has been tested and optimized for commissioning of the HITRAP physics experiments. The process of charge breeding in the EBIT has been successfully studied with gaseous elements and with an alkaline element injected from an external ion source. (orig.)

  6. Charge breeding investigation in EBIS/T and collision study of ions with cold atoms for HITRAP

    International Nuclear Information System (INIS)

    Sokolov, Alexey

    2010-01-01

    Highly charged ions (HCI) at low velocities or at rest are interesting systems for various atomic physics experiments. For investigations on HCI of heavy stable or radioactive nuclides the HITRAP (Highly charged Ion TRAP) decelerator facility has been set up at GSI to deliver cooled beams of HCI at an energy of 5 keV/q. The HCI are produced in a stripper foil at relativistic energies and are decelerated in several steps at ESR storage ring and HITRAP before they are delivered to experimental setups. One of the experiments is the investigation of multi-electron charge exchange in collisions of heavy HCI with cold atoms using novel MOTRIMS technique. Collision experiments on light ions from an ECR ion source colliding with cold atoms in a MOT have been performed and the results are described. An electron beam ion trap (EBIT) has been tested and optimized for commissioning of the HITRAP physics experiments. The process of charge breeding in the EBIT has been successfully studied with gaseous elements and with an alkaline element injected from an external ion source. (orig.)

  7. Jet and electromagnetic tomography (JET) of extreme phases of matter in heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Heinz, Ulrich [The Ohio State Univ., Columbus, OH (United States)

    2015-08-31

    The Ohio State University (OSU) group contributed to the deliverables of the JET Collaboration three major products: 1. The code package iEBE-VISHNU for modeling the dynamical evolution of the soft medium created in relativistic heavy-ion collisions, from its creation all the way to final freeze-out using a hybrid approach that interfaces a free-streaming partonic pre-equilbrium stage with a (2+1)-dimensional viscous relativistic fluid dynamical stage for the quark-gluon plasma (QGP) phase and the microscopic hadron cascade UrQMD for the hadronic rescattering and freeze-out stage. Except for UrQMD, all dynamical evolution components and interfaces were developed at OSU and tested and implemented in collaboration with the Duke University group. 2. An electromagnetic radiation module for the calculation of thermal photon emission from the QGP and hadron resonance gas stages of a heavy-ion collision, with emission rates that have been corrected for viscous effects in the expanding medium consistent with the bulk evolution. The electromagnetic radiation module was developed under OSU leadership in collaboration with the McGill group and has been integrated in the iEBE-VISHNU code package. 3. An interface between the Monte Carlo jet shower evolution and hadronization codes developed by the Wayne State University (WSU), McGill and Texas A&M groups and the iEBE-VISHNU bulk evolution code, for performing jet quenching and jet shape modification studies in a realistically modeled evolving medium that was tuned to measured soft hadron data. Building on work performed at OSU for the theoretical framework used to describe the interaction of jets with the medium, initial work on the jet shower Monte Carlo was started at OSU and moved to WSU when OSU Visiting Assistant Professor Abhijit Majumder accepted a tenure track faculty position at WSU in September 2011. The jet-hydro interface was developed at OSU and WSU and tested and implemented in collaboration with the McGill, Texas

  8. Effect of collective response on electron capture and excitation in collisions of highly charged ions with fullerenes.

    Science.gov (United States)

    Kadhane, U; Misra, D; Singh, Y P; Tribedi, Lokesh C

    2003-03-07

    Projectile deexcitation Lyman x-ray emission following electron capture and K excitation has been studied in collisions of bare and Li-like sulphur ions (of energy 110 MeV) with fullerenes (C(60)/C(70)) and different gaseous targets. The intensity ratios of different Lyman x-ray lines in collisions with fullerenes are found to be substantially lower than those for the gas targets, both for capture and excitation. This has been explained in terms of a model based on "solidlike" effect, namely, wakefield induced stark mixing of the excited states populated via electron capture or K excitation: a collective phenomenon of plasmon excitation in the fullerenes under the influence of heavy, highly charged ions.

  9. Anisotropic flow studies with identified particles with ALICE: a tool to probe different stages of a heavy-ion collision

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    Anisotropic flow studies play a crucial role in the characterization of the nature of the quark gluon plasma (QGP) created in collisions of heavy ions at ultra-relativistic energies. These studies rely on measuring the coefficients vn of the Fourier expansion of the azimuthal particle distribution. They have been essential in establishing that the QGP is a strongly coupled, almost perfect fluid. In this seminar, I review the latest results from measurements of elliptic (v2), triangular (v3), quadrangular (v4) and pentagonal (v5) flow of identified particles at the LHC measured with ALICE. I will discuss how these results allow us to gain insight into the transport properties of the QGP and the initial conditions of a heavy-ion collision. In addition, they reveal the role of different hadronisation mechanisms as well as the highly dissipative hadronic rescattering phase to the development of vn.

  10. The Search for QCD Sphalerons and the Chiral Magnetic Effect in Heavy-Ion Collisions with ALICE

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    In non-central heavy-ion collisions unprecedented strong magnetic fields, of the order of 10^14 T, are expected to be produced by the incoming protons contained in the nuclei. These fields can be used to detect possible non-conservation of chirality in the QCD sector, a signature of sphaleron transitions. In particular, the interplay of chiral imbalance and magnetic fields results in the separation of positive and negative charges along the direction of the field, a phenomenon called “Chiral Magnetic Effect” (CME). In this seminar, the challenges and the opportunities in the search for the CME and the detection of magnetic fields in heavy-ion collisions will be discussed, with an emphasis on recent ALICE results.

  11. Recent progress in nonperturbative electromagnetic lepton-pair production with capture in relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Wells, J.C.; Oberacker, V.E.; Umar, A.S.

    1993-01-01

    The prospect of new colliding-beam accelerators capable of producing collisions of highly stripped high-Z ions, at fixed-target energies per nucleon up to 20 TeV or more, has motivated much interest in lepton-pair production from the QED vacuum. The time-dependent and essentially classical electromagnetic fields involved in such collisions contain larger Fourier components which give rise to sizable lepton-pair production in addition to many other exotic particles. The process of electron-positron production with electron capture is a principal beam-loss mechanism for highly charged ions in a storage ring. In this process, the electron is created in a bound state of one of the participant heavy ions (most likely the 1s state), thus changing the ion's charge state and causing it to be deflected out of the beam. There is a long and sometimes controversial history concerning the use of perturbative methods in studying electromagnetic lepton-pair production; however, reliable perturbative calculations have been used as input into design models for the Relativistic Heavy-Ion Collider (RHIC). Applying perturbation theory to these processes at high energies and small impact parameters results in probabilities which violate unitarity, and cross sections which violate the Froissart bound. This evidence, along with the initial nonperturbative studies, suggests that higher-order QED effects will be important for extreme relativistic collisions. Clearly, large nonperturbative effects in electron-pair production with capture would have important implications for RHIC. In this paper, the authors briefly discuss recent progress in nonperturbative studies of the capture problem. In Section 2, they state the Dirac equation for a lepton in the time-dependent external field of a heavy ion which must be solved to compute lepton-capture probabilities. Section 4 surveys results from recent applications of coupled-channel and lattice techniques to the lepton-capture problem

  12. Is the anomalous effect an experimental evidence for the excitation of new exotic states in heavy-ion collisions

    International Nuclear Information System (INIS)

    Ion, D.B.; Ion, R.; Topor Pop, V.

    1984-10-01

    Lower bound on the mean free path of the projectile fragments from the relativistic heavy ion collisions are drived using generalized Rarita-Schwed's theorems. These bounds are compared with the experimental data on the anomalous mean free path observed in recent experiments. The near saturation of these bounds provide a specific interpretation of the anomalous effects as an experimental evidence for the excitation of those extreme nuclear states which saturate the limits of the convetional nuclear physics. (authors)

  13. Gamma-ray spectroscopy of the neutron-rich Ni region through heavy-ion deep-inelastic collisions

    International Nuclear Information System (INIS)

    Ishii, T.; Asai, M.; Matsuda, M.; Ichikawa, S.; Makishima, A.; Hossain, I.; Kleinheinz, P.; Ogawa, M.

    2002-01-01

    Nuclei in the neutron-rich Ni region have been studied by γ-ray spectroscopy. Gamma-rays emitted from isomers, with T 1/2 >1 ns, produced in heavy-ion deep-inelastic collisions were measured with an isomer-scope. The nuclear structure of the doubly magic 68 Ni and its neighbor 69,71 Cu is discussed on the basis of the shell model. Future experiments for more neutron-rich Ni nuclei are also viewed. (orig.)

  14. Gamma-ray spectroscopy of the neutron-rich Ni region through heavy-ion deep-inelastic collisions

    Science.gov (United States)

    Ishii, T.; Asai, M.; Makishima, A.; Hossain, I.; Kleinheinz, P.; Ogawa, M.; Matsuda, M.; Ichikawa, S.

    Nuclei in the neutron-rich Ni region have been studied by γ-ray spectroscopy. Gamma-rays emitted from isomers, with T1/2 > 1 ns, produced in heavy-ion deep-inelastic collisions were measured with an isomer-scope. The nuclear structure of the doubly magic 68Ni and its neighbor 69,71Cu is discussed on the basis of the shell model. Future experiments for more neutron-rich Ni nuclei are also viewed.

  15. K-shell ionization of low Z elements in ion-solid collisions and applicability of local plasma approximation

    Energy Technology Data Exchange (ETDEWEB)

    Kadhane, U. [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India); Kumar, Ajay [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India); Montanari, C.C. [Instituto de Astronomiay Fisca de Espacio, CONICET-UBA, Buenos Aires (Argentina); Tribedi, L.C. [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India)]. E-mail: lokesh@tifr.res.in

    2006-11-15

    K-shell vacancy production cross sections are measured using X-ray technique, in collisions of highly charged fluorine ions with various solid targets such as, Cl, K, Fe and Cu, at energies from 50 to 110 MeV. The experimental data is compared with an ab initio model based on local plasma approximation (LPA) and the usually employed ECPSSR. A detailed comparison with the LPA model is presented as a function of generalized perturbation strength.

  16. Design and performance simulation of a segmented-absorber based muon detection system for high energy heavy ion collision experiments

    International Nuclear Information System (INIS)

    Ahmad, S.; Bhaduri, P.P.; Jahan, H.; Senger, A.; Adak, R.; Samanta, S.; Prakash, A.; Dey, K.; Lebedev, A.; Kryshen, E.; Chattopadhyay, S.; Senger, P.; Bhattacharjee, B.; Ghosh, S.K.; Raha, S.; Irfan, M.; Ahmad, N.; Farooq, M.; Singh, B.

    2015-01-01

    A muon detection system (MUCH) based on a novel concept using a segmented and instrumented absorber has been designed for high-energy heavy-ion collision experiments. The system consists of 6 hadron absorber blocks and 6 tracking detector triplets. Behind each absorber block a detector triplet is located which measures the tracks of charged particles traversing the absorber. The performance of such a system has been simulated for the CBM experiment at FAIR (Germany) that is scheduled to start taking data in heavy ion collisions in the beam energy range of 6–45 A GeV from 2019. The muon detection system is mounted downstream to a Silicon Tracking System (STS) that is located in a large aperture dipole magnet which provides momentum information of the charged particle tracks. The reconstructed tracks from the STS are to be matched to the hits measured by the muon detector triplets behind the absorber segments. This method allows the identification of muon tracks over a broad range of momenta including tracks of soft muons which do not pass through all the absorber layers. Pairs of oppositely charged muons identified by MUCH could therefore be combined to measure the invariant masses in a wide range starting from low mass vector mesons (LMVM) up to charmonia. The properties of the absorber (material, thickness, position) and of the tracking chambers (granularity, geometry) have been varied in simulations of heavy-ion collision events generated with the UrQMD generator and propagated through the setup using the GEANT3, the particle transport code. The tracks are reconstructed by a Cellular Automaton algorithm followed by a Kalman Filter. The simulations demonstrate that low mass vector mesons and charmonia can be clearly identified in central Au+Au collisions at beam energies provided by the international Facility for Antiproton and Ion Research (FAIR)

  17. Observation of an Energy-Dependent Difference in Elliptic Flow between Particles and Antiparticles in Relativistic Heavy Ion Collisions

    Czech Academy of Sciences Publication Activity Database

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C.; Barnovská, Zuzana; Bielčík, J.; Bielčíková, Jana; Chaloupka, P.; Chung, Paul; Hajková, O.; Kapitán, Jan; Pachr, M.; Rusňák, Jan; Šumbera, Michal; Tlustý, David

    2013-01-01

    Roč. 110, č. 14 (2013), s. 142301 ISSN 0031-9007 R&D Projects: GA ČR GA13-20841S Institutional support: RVO:61389005 Keywords : STAR * elliptic flow * heavy ion collisions * particles and antiparticles comparations Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 7.728, year: 2013 http://prl. aps .org/pdf/PRL/v110/i14/e142301

  18. State-selective electron capture in collisions of ground and metastable O2+ ions with H(1s)

    International Nuclear Information System (INIS)

    Cabello, C N; Errea, L F; Fernandez, L; Mendez, L; Macias, A; Rabadan, I; Riera, A

    2003-01-01

    An ab initio calculation of the electron capture cross sections for collisions of ground and metastable states of O 2+ with H(1s) is presented. For impact energies between 0.125 and 3.4 keV amu -1 , we find good agreement between the cross sections from the ground state ion with the mixed beam experimental data of Phaneuf et al (Phaneuf A, Alvarez I, Meyer F W and Crandall D H 1982 Phys. Rev. A 26 1892)

  19. Design and performance simulation of a segmented-absorber based muon detection system for high energy heavy ion collision experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, S. [University of Kashmir, Srinagar (India); Bhaduri, P.P. [Variable Energy Cyclotron Centre, Kolkata (India); Jahan, H. [Aligarh Muslim University, Aligarh (India); Senger, A. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Adak, R.; Samanta, S. [Bose Institute, Kolkata (India); Prakash, A. [Banaras Hindu University, Varanasi (India); Dey, K. [Gauhati University, Guwahati (India); Lebedev, A. [Institute für Kernphysik, Goethe Universität Frankfurt, Frankfurt (Germany); Kryshen, E. [Petersburg Nuclear Physics Institute (PNPI) NRC Kurchatov Institute, Gatchina (Russian Federation); Chattopadhyay, S., E-mail: sub@vecc.gov.in [Variable Energy Cyclotron Centre, Kolkata (India); Senger, P. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Bhattacharjee, B. [Gauhati University, Guwahati (India); Ghosh, S.K.; Raha, S. [Bose Institute, Kolkata (India); Irfan, M.; Ahmad, N. [Aligarh Muslim University, Aligarh (India); Farooq, M. [University of Kashmir, Srinagar (India); Singh, B. [Banaras Hindu University, Varanasi (India)

    2015-03-01

    A muon detection system (MUCH) based on a novel concept using a segmented and instrumented absorber has been designed for high-energy heavy-ion collision experiments. The system consists of 6 hadron absorber blocks and 6 tracking detector triplets. Behind each absorber block a detector triplet is located which measures the tracks of charged particles traversing the absorber. The performance of such a system has been simulated for the CBM experiment at FAIR (Germany) that is scheduled to start taking data in heavy ion collisions in the beam energy range of 6–45 A GeV from 2019. The muon detection system is mounted downstream to a Silicon Tracking System (STS) that is located in a large aperture dipole magnet which provides momentum information of the charged particle tracks. The reconstructed tracks from the STS are to be matched to the hits measured by the muon detector triplets behind the absorber segments. This method allows the identification of muon tracks over a broad range of momenta including tracks of soft muons which do not pass through all the absorber layers. Pairs of oppositely charged muons identified by MUCH could therefore be combined to measure the invariant masses in a wide range starting from low mass vector mesons (LMVM) up to charmonia. The properties of the absorber (material, thickness, position) and of the tracking chambers (granularity, geometry) have been varied in simulations of heavy-ion collision events generated with the UrQMD generator and propagated through the setup using the GEANT3, the particle transport code. The tracks are reconstructed by a Cellular Automaton algorithm followed by a Kalman Filter. The simulations demonstrate that low mass vector mesons and charmonia can be clearly identified in central Au+Au collisions at beam energies provided by the international Facility for Antiproton and Ion Research (FAIR)

  20. Radiative double electron capture (RDEC) in collisions of bare fluorine ions with carbon foils

    Science.gov (United States)

    Elkafrawy, T.; Tanis, J. A.; Simon, A.; Warczak, A.

    2012-06-01

    Radiative double electron capture (RDEC) is a charge exchange process involving the capture of two target electrons into a bound state of the projectile simultaneously with the emission of a single photon. RDEC is the time reversed process of double photoionization if the target electrons are loosely bound. This approach provides us with a clean tool to explore the problems involved with electron-electron correlations and a proper description of a two-electron-continuum wave function in various atomic systems. In this work, we investigate both radiative electron capture (REC) and RDEC in collisions of 42 MeV singly- and doubly-charge changed fluorine ions with carbon targets. The experiment was performed at the tandem Van de Graaff accelerator of Western Michigan University in which emitted x rays were measured at 90 to the beam line in coincidence with projectile charge-changing of bare and H-like fluorine. The first evidence to see the RDEC process in O^8+ + C collisionsootnotetextA. Simon et al., Phys. Rev. Lett. 104 (12), 123001 (2010) was the motivation to conduct the current work for the sake of the comparison between both observations and with recent theoretical calculations.ootnotetextA. I. Mikhailov et al., Phys. Lett. A 328, 350 (2004)^,ootnotetextA. I. Mikhailov et al., Phys. Rev. A 69, 032703 (2004)^,ootnotetextA. Nefiodov et al., Phys. Lett. A 346, 158 (2005).