high-energy collision induced: Topics by WorldWideScience.org

Sample records for high-energy collision induced

High-energy limit of collision-induced false vacuum decay

Energy Technology Data Exchange (ETDEWEB)

Demidov, Sergei; Levkov, Dmitry [Institute for Nuclear Research of the Russian Academy of Sciences,60-th October Anniversary Prospect 7a, Moscow, 117312 (Russian Federation)

2015-06-17

We develop a consistent semiclassical description of field-theoretic collision-induced tunneling at arbitrary high collision energies. As a playground we consider a (1+1)-dimensional false vacuum decay initiated by a collision of N particles at energy E, paying special attention to the realistic case of N=2 particles. We demonstrate that the cross section of this process is exponentially suppressed at all energies. Moreover, the respective suppressesion exponent F{sub N}(E) exhibits a specific behavior which is significant for our semiclassical method and assumed to be general: it decreases with energy, reaches absolute minimum F=F{sub min}(N) at a certain threshold energy E=E{sub rt}(N), and stays constant at higher energies. We show that the minimal suppression F{sub min}(N) and threshold energy can be evaluated using a special class of semiclassical solutions which describe exponentially suppressed transitions but nevertheless evolve in real time. Importantly, we argue that the cross section at energies above E{sub rt}(N) is computed perturbatively in the background of the latter solutions, and the terms of this perturbative expansion stay bounded in the infinite-energy limit. Transitions in the high-energy regime proceed via emission of many soft quanta with total energy E{sub rt}; the energy excess E−E{sub rt} remains in the colliding particles till the end of the process.
High energy hadron-hadron collisions

International Nuclear Information System (INIS)

Chou, T.T.

1990-01-01

Results of a study on high energy collision with the geometrical model are summarized in three parts: (i) the elastic hadron-hadron collision, (ii) the inelastic hadron-hadron collision, and (iii) the e + e - annihilation. The geometrical description of high-energy elastic scattering developed earlier is still in general agreement with experiments at the CERN-S bar ppS energies. A simple one-parameter expression for the blackness of bar pp system has been proposed recently which describes very well all existing data from ISR to S bar ppS energies. The geometrical description has also been extended to include processes of fragmentation and diffraction dissociation and other phenomena. In the past five years, a unified physical picture for multiparticle emission in hadron-hadron and e + e - collisions was developed. It focuses on the idea of the wide range of values for the total angular momentum in hadron-hadron collisions. An extension of this consideration yields a theory for the momentum distribution of the outgoing particles which agrees with bar pp and e + e - collision experiments. The results and conclusions of this theory have been extrapolated to higher energies and yielded many predictions which can be experimentally tested. 37 refs
Transverse-energy distribution in proton-nucleus collisions at high energy

International Nuclear Information System (INIS)

Liu, F.H.

2001-01-01

Based on the model of nuclear-collision geometry, the independent N - N collision picture and participant contribution picture are used to describe the transverse-energy distribution in p-A collisions at high energy. In the independent N - N collision picture, the energy loss of leading proton in each p-N collision is considered. The calculated results are in agreement with the experimental data of p-Al, p-Cu, p-U collisions at 200 GeV/c. (author)
Theoretical interpretation of high-energy nuclear collisions

International Nuclear Information System (INIS)

Fai, G.

1992-06-01

Nuclear collisions are interpreted theoretically. The nuclear equation of state is studied in a wide energy range. Subnucleonic degrees of freedom are invoked at high energy densities and at short length-scales. Questions of dynamical collision simulations are investigated. Direct support is provided for experiment in the form of collaborative projects. The major objective of this nuclear theory program is a better understanding of the properties of strongly interacting matter on the nuclear energy scale, as manifested in high-energy heavy-ion collisions
Interferometry of high energy nuclear collisions

International Nuclear Information System (INIS)

Padula, S.S.

1990-01-01

The interferometry is used for determining large space time dimensions of the Quark Gluon Plasma formed in high energy nuclear collisions or in high multiplicity fluctuations in p-barp collisions. (M.C.K.)
High-energy hadron-hadron collisions

International Nuclear Information System (INIS)

Yang, C.N.

1983-01-01

While high energy collision experiments yield a wealth of complicated patterns, there are a few general and very striking features that stand out. Because of the universality of these features, and because of the dominating influence they have on high energy phenomena, it is the authors opinion that a physical picture of high energy collisions must address itself first of all to these features before going into specific details. In this short talk these general and striking features are stated and a physical picture developed in the last few years to specifically accommodate these features is described. The picture was originally discussed for elastic scattering. But it leads naturally, indeed inevitably as they shall discuss, to conclusions about inelastic processes, resulting in an idea called the hypothesis of limiting fragmentation
Models of high energy nuclear collisions

International Nuclear Information System (INIS)

Glendenning, N.K.

1978-06-01

The discussion covers nuclear collisions at relativistic energies including classes of high energy nucleus--nucleus collisions, and the kinetics of a central collision; and the asymptotic hadron spectrum including known and unknown hadrons, the relevance of the spectrum and the means of its study, thermodynamics of hadronic matter, examples of hadronic spectra, the temperature, composition of the initial fireball and its expansion, isoergic expansion with no pre-freezeout radiation, isentropic expansion of the fireball, the quasi-dynamical expansion, and finally antinuclei, hypernuclei, and the quark phase. 28 references
Energy changes in massive target-nuclei, induced by high-energy hadronic projectiles

International Nuclear Information System (INIS)

Strugalski, Z.; Strugalska-Gola, E.

1997-01-01

Now it turned out that it is real to estimate by experiments the energy changes in massive target-nuclei, induced by high-energy hadronic projectiles. The subject matter in this work is to present results of the quantitative estimations of the energy changes in intranuclear matter at various stages of hadron-nucleus collision reactions. Appropriate formulas are proposed for the energy balances - as following from the experimentally based mechanism of the hadron-nucleus collision reactions
High energy nucleus-nucleus collisions

International Nuclear Information System (INIS)

Bhalla, K.B.

1980-01-01

An attempt is made to explain nucleus-nucleus collisions based on nuclear emulsion experiments. Peripheral and central collisions are described in detail. Assuming the fireball model, the concepts of geometry, kinematics and thermodynamics in this model are discussed. Projectile and target fragmentations are studied. The advantages of using nuclear emulsions as detectors, are mentioned. Proton-nucleus collisions and nucleus-nucleus collisions are compared. Interactions, of projectiles such as Ca, B and C on targets such as Pb, Ag, Br etc. at very high energies (approximately 300 to 1700 Gev) are listed. A comparison of the near multiplicities in these interactions is given. A generalized explanation is given on the processes involved in these interactions. (A.K.)
Theoretical interpretation of high-energy nuclear collisions

International Nuclear Information System (INIS)

Fai, G.

1991-07-01

Nuclear collision data are interpreted theoretically. The nuclear equation of state is investigated with particular emphasis on momentum-dependent mean field effects. Subnucleonic degrees of freedom are invoked at high energies and densities, and a short length-scales. A nontopological soliton model for baryons is studied in which effective meson fields are generated from extended quark-antiquark pairs. The major objective of this nuclear theory project is a better understanding of the properties of strongly interacting matter on the nuclear energy scale, as manifested in high-energy heavy-ion collisions
Axial spatial distribution focusing: improving MALDI-TOF/RTOF mass spectrometric performance for high-energy collision-induced dissociation of biomolecules.

Science.gov (United States)

Belgacem, O; Pittenauer, E; Openshaw, M E; Hart, P J; Bowdler, A; Allmaier, G

2016-02-15

For the last two decades, curved field reflectron technology has been used in matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometers, assisting in the generation of post-source-decay (PSD) or collision-induced dissociation (CID) without decelerating precursor ions, producing true high-energy CID spectra. The result was the generation of product ion mass spectra with product ions typical of high-energy (10 keV and beyond) collision processes. The disadvantage of this approach was the lack of resolution in CID spectra resulting from the excess laser energy deposition used to generate those MS/MS spectra. The work presented in this study overcomes this limitation and includes comprehensive examples of high-energy and high-resolution CID MALDI-MS/MS spectra of biomolecules. The devices used in this study are TOF/RTOF instruments equipped with a high-vacuum MALDI ion source. High-resolution and high-energy CID spectra result from the use of axial spatial distribution focusing (ASDF) in combination with curved field reflectron technology. A CID spectrum of the P14 R1 peptide exhibits product ion resolution in excess of 10,000 (FWHM) but at the same time yields typical high-energy product ions such as w- and [y-2]-type ion series. High-energy CID spectra of lipids, exemplified by a glycerophospholipid and triglyceride, demonstrate C-C backbone fragmentation elucidating the presence of a hydroxyl group in addition to double-bond positioning. A complex high mannose carbohydrate (Man)8 (GlcNAc)2 was also studied at 20 keV collision energy and revealed further high-energy product ions with very high resolution, allowing unambiguous detection and characterization of cross-ring cleavage-related ions. This is the first comprehensive study using a MALDI-TOF/RTOF instrument equipped with a curved field reflectron and an ASDF device prior to the reflectron. © 2015 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley
Mean charged hadron multiplicities in high-energy collisions

Energy Technology Data Exchange (ETDEWEB)

Albini, E [Istituto di Matematica dell' Universita Cattolica di Brescia (Italy); Capiluppi, P; Giacomelli, G; Rossi, A M [Bologna Univ. (Italy). Istituto di Fisica

1976-03-01

A collection of mean charged hadron multiplicities per inelastic collision in various high-energy processes is presented. An extensive list of fits of as a function of energy is presented and discussed. As the energy increases the multiplicities for different collisions tend to a unique curve, independent of the type of colliding particles.
Mechanisms of High Energy Hadron-Nucleus and Nucleus-Nucleus Collision Processes

International Nuclear Information System (INIS)

Strugalski, Z.

1994-01-01

Mechanisms of high energy hadron-nucleus and nucleus-nucleus collision processes are depicted qualitatively, as prompted experimentally. In hadron-nucleus collisions the interaction of the incident hadron in intranuclear matter is localized in small cylindrical volume, with the radius as large as the strong interaction range is, centered on the hadron course in the nucleus. The nucleon emission is induced by the hadron in its passing through the nucleus; particles are produced via intermediate objects produced in 2 → 2 endoergic reactions of the hadron and its successors with downstream nucleons. In nucleus-nucleus collisions, the outcome of the reaction appears as the composition of statistically independent hadron-nucleus collision outcomes at various impact parameters. Observable effects supporting such mechanisms are discussed. 51 refs
Collision-induced destructive quantum interference

International Nuclear Information System (INIS)

Yang Xihua; Sun Zhenrong; Zhang Shi'an; Ding Liang'en; Wang Zugeng

2005-01-01

We conduct theoretical studies on the collision-induced destructive quantum interference of two-colour two-photon transitions in an open rhomb-type five-level system with a widely separated doublet by the density matrix approach. The effects of the collision-induced decay rates, the ratio of the transition dipole moments and the energy separation of the doublet on the interference are analysed. It is shown that a narrow dip appears in the excitation spectrum due to the collision-induced destructive interference, and that the narrow interference dip still exists even when the collision broadening is comparable to the energy separation of the doublet. The physical origin of the collision-induced destructive quantum interference is analysed in the dressed-atom picture
High energy hadron-hadron collisions. Annual progress report

International Nuclear Information System (INIS)

Chou, T.T.

1979-03-01

Work on high energy hadron-hadron collisions in the geometrical model, performed under the DOE Contract No. EY-76-S-09-0946, is summarized. Specific items studied include the behavior of elastic hadron scatterings at super high energies and the existence of many dips, the computation of meson radii in the geometrical model, and the hadronic matter current effects in inelastic two-body collisions
Multiplicity distributions in high energy collisions

International Nuclear Information System (INIS)

Giovannini, A.; Lupia, S.; Ugoccioni, R.

1992-01-01

We discuss the important phases in the evolution of our understanding of multiplicity distributions in high energy collisions with particular emphasis to intermittent behavior and shoulder structure problem. (orig.)
Multiplicity distributions in high energy collisions

Energy Technology Data Exchange (ETDEWEB)

Giovannini, A.; Lupia, S.; Ugoccioni, R. (Dipt. di Fisica Teorica, Univ. Turin (Italy) INFN, Turin (Italy))

1992-03-01

We discuss the important phases in the evolution of our understanding of multiplicity distributions in high energy collisions with particular emphasis to intermittent behavior and shoulder structure problem. (orig.).
High energy nuclear collisions: theory review

International Nuclear Information System (INIS)

Fries, Rainer J.

2009-01-01

Full text: High Energy Nuclear Collisions are studied at the Relativistic Heavy Ion Collider (RHIC) and, starting next year, also at the Large Hadron Collider (LHC) to study the formation and properties of quark gluon plasma (QGP). This effort is driven by the prediction that above a certain critical temperature quarks and gluons are deconfined. For the past ten years of running RHIC has performed marvelously. Data from RHIC has answered many initial questions, but it has also provided new, more challenging problems to understand the nature of quark gluon plasma and the dynamics of heavy ion collisions. In this talk I review some of the basic concepts of high energy nuclear collisions and quark gluon plasma formation. We also discuss some of the novel and open questions that we are faced with. We discuss recent predictions on properties of hot quantum chromodynamics, emerging signatures for the color glass condensate, the fascinating idea of local P and CP violation in QCD, as well as ongoing research on hard probes and electromagnetic signatures
Reaction mechanism in high energy heavy-ion collisions

International Nuclear Information System (INIS)

Tanihata, Isao.

1982-04-01

The reaction mechanism in high energy heavy-ion collision is discussed. The discussion is mainly based on the experimental data. Empirical equations have been given for the total cross-sections of nucleus-nucleus reactions and the reaction cross-sections. These cross-sections are well described by the geometrical size of the colliding nuclei. The cross-sections are also understood by microscopic calculation. The charged particle multiplicity gives additional information about the geometrical aspect of heavy ion collision. The data suggested that the total energy, independent of projectile size, is most important for determining the multiplicity. The inclusive proton spectrum in a heavy ion collision showed two distinct regions. The one is the fragment region, and the other the participant region. The spectral shapes of inclusive pion spectra are reasonably well explained by the Coulomb interaction of pions with nuclear fragments. The high energy heavy ion reaction occurs in the overlap region of the projectile and target. This has been tested by measuring the number of participants for various reactions. The space and the time structure of the collision are also discussed in this paper as well as the dynamical aspects of the collision. (Kato, T.)
Energy transfer in diatom/diatom molecular collisions

International Nuclear Information System (INIS)

Sohlberg, K.W.

1992-01-01

In a collision of two molecules, the translational energy of the collision may be redistributed into internal energy of rotation, vibration, or electron motion, in one or both of the colliding partners. In addition, internal energy in one or more of these modes may be open-quotes quenchedclose quotes into translation, leading to a superelastic collision. Such energy transfer may take place by a number of mechanisms. This energy transfer is of fundamental importance in understanding chemical reaction dynamics. Nearly all chemical reactions take place through a bimolecular collision process (or multiple bimolecular collisions) and the quantum state specificity of the reaction can have a major role in determining the kinetics of the reaction, In particular, the author has investigated vibrational energy transfer in collisions between two diatomic molecules. In addition to serving as models for all molecular collision process, gas phase collisions of these species are ubiquitous in atmospheric phenomena which are of critical importance in answering the current questions about the human induced degradation of the earth's atmospheric. Classical trajectory methods have been used to explore the excitation of vibrations in gas-phase collisions of the nitrogen molecular ion with its parent molecule. The near symmetry of the reactants is shown to result in a high probability that the two molecules are excited by an equal amount of energy. This provides a possible explanation of the molecular beam measurements which show that the total number of vibrational energy quanta excited in the collision is, with a high probability that the two molecules are excited by an equal amount of energy. This provides a possible explanation of the molecular beam measurements which show that the total number of vibrational energy quanta excited in the collision is, with a high probability, even

Nuclear energy release in hadron-nucleus collisions

International Nuclear Information System (INIS)

Strugalski, Z.; Strugalska-Gola, E.

1998-01-01

Energy release process in nuclear reactions induced by fast hadrons in hadron-nucleus collisions is discussed. Some portion of the internal nuclear energy is released when the locally damaged in a collision, and instable therefore, residual target nucleus transits itself into light nuclear fragments (nucleons, D, T) and a stable lighter final nucleus or some number of stable lighter nuclei. It is not excluded that in some of the collisions the induced intranuclear nuclear reactions may be energy overcompensating. Corresponding reconnaissance should be made - in analysing the nuclear reactions induced in hadron-nucleus collisions
Perspectives in high energy nuclear collisions

International Nuclear Information System (INIS)

Rafelski, J.

1983-08-01

This report gives an overview of some aspects of hadronic physics relevant for the conception of a research facility devoted to the study of high energy nuclear collisions. Several concepts to be studied in nuclear collisions are selected, with emphasis placed on the properties and nature of the quark-gluon plasma, the formation of the plasma state in the central region and its anticipated lifetime, and the observability, through strangeness content of this new form of nuclear matter. (orig.)
Global flow of glasma in high energy nuclear collisions

Energy Technology Data Exchange (ETDEWEB)

Chen, Guangyao; Fries, Rainer J., E-mail: rjfries@comp.tamu.edu

2013-06-25

We discuss the energy flow of the classical gluon fields created in collisions of heavy nuclei at collider energies. We show how the Yang–Mills analog of Faraday's Law and Gauss' Law predicts the initial gluon flux tubes to expand or bend. The resulting transverse and longitudinal structure of the Poynting vector field has a rich phenomenology. Besides the well-known radial and elliptic flow in transverse direction, classical quantum chromodynamics predicts a rapidity-odd transverse flow that tilts the fireball for non-central collisions, and it implies a characteristic flow pattern for collisions of non-symmetric systems A+B. The rapidity-odd transverse flow translates into a directed particle flow v{sub 1} which has been observed at RHIC and LHC. The global flow fields in heavy ion collisions could be a powerful check for the validity of classical Yang–Mills dynamics in high energy collisions.
Jets in high energy nucleon-nucleon collisions

International Nuclear Information System (INIS)

Strugalski, Z.

1982-01-01

From the experimental studies of high-energy hardon-nucleon and nucleon-nucleon collisions, by means of nuclear targets applied as detectors, it follows that particles are produced via intermediate objects created first in a 2 → 2 type endoergic reaction. These objects, called generons, decay in flight into finally observed particles and resonances after their lifetime tausub(g) > or approximately 10 - 22 s. The jet structure of the outcome in nucleon-nucleon collisions is a simple and indispensable consequence of this particle production mechanism. The picture of the jet structure in the collision outcome observed in the CMS of the colliding nucleons depends on the energy of these nUcleons. New particle production scheme is proposed, which can be tested experimentally; corresponding simple relations between characteristics of colliding nucleons and of produced jets are proposed for a testing
High energy nuclear collisions: Theory overview

Indian Academy of Sciences (India)

1012 K, were deconfined and existed as a quark gluon plasma (QGP). These ideas can be tested in collisions of nuclei at ultra-relativistic energies. At the relativistic heavy-ion collider (RHIC), nuclei as heavy as gold are accelerated to an energy of 100 GeV per nucleon. A total energy of 40 TeV is available in the collision of.
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)
High energy collisions of nuclei: experiments

International Nuclear Information System (INIS)

Heckman, H.H.

1977-09-01

Heavy-ion nuclear reactions with projectile energies up to 2.1 GeV/A are reviewed. The concept of ''rapidity'' is elucidated, and the reactions discussed are divided into sections dealing with target fragmentation, projectile fragmentation, and the intermediate region, with emphasis on the production of light nuclei in high-energy heavy-ion collisions. Target fragmentation experiments using nuclear emulsion and AgCl visual track detectors are also summarized. 18 figures
Proton multiplicity distributions in high-energy hadron-nuclei collisions

International Nuclear Information System (INIS)

Strugalski, Z.

1979-01-01

The fast proton emission process is analyzed in high-energy hadron-nuclei collisions. The formula describing the proton multiplicity distributions is derived. It describes well enough the proton multiplicity distribution of pion-nuclei and proton-nuclei collisions at 200 and 400 GeV
Rapidity and multiplicity correlations in high energy hadronic collisions

International Nuclear Information System (INIS)

Heiselberg, H.

1993-01-01

Rapidity and multiplicity correlations of particle production in high energy hadronic collisions are studied. A simple model including short range correlations in rapidity due to clustering and long range correlations due to energy conservation is able to describe the two-body correlation functions well hadron-nucleon collisions around lab energies of 250 GeV. In this model fractional moments are calculated and compared to data. The strong rise of the factorial moments in rapidity intervals by size δy∝1 can be explained by long and short range correlation alone whereas the factorial moments approach a constant value at very small δy due to lack of correlations also in agreement with experiment. There is therefore no need for introducing intermittency in the particle production in hadronic collisions at these energies. (orig.)
Disoriented Chiral Condensates in High-Energy Nuclear Collisions

Energy Technology Data Exchange (ETDEWEB)

Randrup, Jorgen

2000-10-18

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

International Nuclear Information System (INIS)

Gronqvist, Hanna

2016-01-01

We study fluctuations that are omnipresent in high-energy particle collisions. These fluctuations can be either of either classical or quantum origin and we will study both. Firstly, we consider the type of quantum fluctuations that arise in proton-proton collisions. These are computable perturbatively in quantum field theory and we will focus on a specific class of diagrams in this set-up. Secondly, we will consider the fluctuations that are present in collisions between nuclei that can be heavier than protons. These are the quantum laws of nature that describe the positions of nucleons within a nucleus, but also the hydrodynamic fluctuations of classical, thermal origin that affect the evolution of the medium produced in heavy-ion collisions. The fluctuations arising in proton-proton collisions can be computed analytically up to a certain order in perturbative quantum field theory. We will focus on one-loop diagrams of a fixed topology. Loop diagrams give rise to integrals that typically are hard to evaluate. We show how modern mathematical methods can be used to ease their computation. We will study the relations among unitarity cuts of a diagram, the discontinuity across the corresponding branch cut and the coproduct. We show how the original integral corresponding to a given diagram can be reconstructed from the information contained in the coproduct. We expect that these methods can be applied to solve more complicated topologies and help in the computation of new amplitudes in the future. Finally, we study the two types of fluctuations arising in heavy-ion collisions. These are related either to the initial state or the intermediate state of matter produced in such collisions. The initial state fluctuations are experimentally observed to give rise to non-Gaussianities in the final-state spectra. We show how these non-Gaussianities can be explained by the random position and interaction energy of 'sources' in the colliding nuclei. Furthermore, we
Pion production and fragmentation of nuclei in high energy nucleus-nucleus collisions

International Nuclear Information System (INIS)

Oskarsson, A.

1983-01-01

In collisions between nuclei at high energies one can study the behaviour of nuclear matter under extreme conditions, regarding nuclear density and temperature. The Bevalac and the CERN SC beams have been used and nuclear emulsion and scintillation telescopes have measured the reaction products. Collisions at 50A-200A MeV and at 2A GeV have been investigated. Proton spectra from 12 C induced reactions at 85A MeV have been recorded for different targets. Energetic protons at large angles can be assumed to be emitted from a source moving with half the beam velocity and a temperature between 13 and 17 MeV, depending on the target. In collisions between nuclei, pions can be produced below 290A MeV due to the internal Fermi motion of the nucleons. Subthreshold pion production has been studied for 12 C induced reactions at 85A and 75A Mev. The cross-sections are consistent with a quasi-free nucleon-nucleon scattering picture, involving Fermi motion, Pauli blocking and pion reabsorption. 16 C induced reactions in emulsion have been studied at 75A, 175A and 2000A MeV. It is shown that the excitation of the parts of the nuclei which are not overlapping (the spectators) increases with the beam energy. The 16 O projectile frequently breaks up into multiple He fragments. These events are associated with large impact parameters. Central collisions with Ag, Br target at 50A-110A MeV have been analysed separately. It is shown that the momentum transfer to the target nucleus is limited to a value considerably lower than the full momentum transfer in a fusion reactions. Events are observed where there are numerous fragments with 3< Z<8. These multifragmentation events cannot be understood in a thermal approach. (author)
Inclusive cross sections in AA collisions at high energies

International Nuclear Information System (INIS)

Braun, M.A.

1988-01-01

Inclusive cross sections in AA collisions at high energies are considered in the Glauber multiple scattering theory taking into account many-nucleon collisions. Correspondence is found between the AA amplitude and the effective action of the two-dimensional quantum field theory with exponential interaction. The tree and one-loop contributions are calculated in this formalism. The rules are derived, which relate the absorption part of the AA-collision amplitudes associated with various inclusive cross sections to the absorption parts of NN amplitudes. These rules generalize the well-known Agranowsky-Gribov-Kanchelli rules for hh and hA collisions. Formulas are written for single and double inclusive cross sections in AA collisions
Microscopic descriptions of high-energy heavy-ion collisions

International Nuclear Information System (INIS)

Bodmer, A.R.

1977-01-01

The essentials of the equation-of-motion (EOM) approach are given and some of its significant and interesting results are described. A framework for the theoretical description of high-energy heavy-ion (HE-HI) collisions is presented; specifically included are a critical assessment of various approaches--EOM calculations, Boltzmann equations/cascade calculations, and hydrodynamics--their relationships and their respective domains of applicability, if any, to HE-HI collisions. 11 figures, 3 tables
Theoretical interpretation of data from high-energy nuclear collisions

International Nuclear Information System (INIS)

Fai, G.

1988-09-01

Nuclear collision data at energies ranging from medium to relativistic are interpreted theoretically. The major objective is a better understanding of high-energy heavy-ion collisions, with particular emphasis on the properties of excited nuclear matter. Further progress towards a satisfactory description of excited subsaturation nuclear matter is achieved. The mean free path of a nucleon in nuclear matter, which is a critical parameter in assessing the applicability of certain nuclear collision models, is investigated. Experimental information is used together with theoretical concepts in collaborations with experimentalists in order to learn about the reaction mechanism and about excited nuclear matter properties. In the framework of a more strictly theoretical program development, subnuclear degrees of freedom and nonlinear phenomena in model field theories are studied
Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies.

Science.gov (United States)

Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Drees, K A; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Gutierrez, T D; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Rykov, V; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

2003-10-24

We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for 5collision energy dependence of the yields and the centrality and p(T) dependence of the suppression provide stringent constraints on theoretical models of suppression. Models incorporating initial-state gluon saturation or partonic energy loss in dense matter are largely consistent with observations. We observe no evidence of p(T)-dependent suppression, which may be expected from models incorporating jet attenuation in cold nuclear matter or scattering of fragmentation hadrons.
Comparison of models of high energy nuclear collisions

International Nuclear Information System (INIS)

Gyulassy, M.

1978-01-01

The treatment of high energy nuclear reaction models covers goals of such collisions, the choice of theoretical framework, the zoo of models (p inclusive), light composites, models versus experiment, conclusions drawn, needed experiments, and pion production. 30 diagrams
Heavy Quark and Quarkonium Transport in High Energy Nuclear Collisions

Energy Technology Data Exchange (ETDEWEB)

Zhou, Kai [Physics Department, Tsinghua University and Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China); Institute for Theoretical Physics, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main (Germany); Dai, Wei [Physics Department, Tsinghua University and Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China); Xu, Nu [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Zhuang, Pengfei [Physics Department, Tsinghua University and Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China)

2016-12-15

The strong interaction between heavy quarks and the quark gluon plasma makes the open and hidden charm hadrons be sensitive probes of the deconfinement phase transition in high energy nuclear collisions. Both the cold and hot nuclear matter effects change with the colliding energy and significantly influence the heavy quark and charmonium yield and their transverse momentum distributions. The ratio of averaged quarkonium transverse momentum square and the elliptic flow reveal the nature of the QCD medium created in heavy ion collisions at SPS, RHIC and LHC energies.
Heavy Quark and Quarkonium Transport in High Energy Nuclear Collisions

International Nuclear Information System (INIS)

Zhou, Kai; Dai, Wei; Xu, Nu; Zhuang, Pengfei

2016-01-01

The strong interaction between heavy quarks and the quark gluon plasma makes the open and hidden charm hadrons be sensitive probes of the deconfinement phase transition in high energy nuclear collisions. Both the cold and hot nuclear matter effects change with the colliding energy and significantly influence the heavy quark and charmonium yield and their transverse momentum distributions. The ratio of averaged quarkonium transverse momentum square and the elliptic flow reveal the nature of the QCD medium created in heavy ion collisions at SPS, RHIC and LHC energies.
Inelastic scattering and endohedral complex formation in high-energy collisions of fullerenes with He

International Nuclear Information System (INIS)

Callahan, J.H.; Mowrey, R.C.; Ross, M.M.

1992-01-01

Since the original postulation of its icosahedral structure by Smalley and Kroto in 1985, C 60 (also known as buckminsterfullerene) has fascinated investigators in a variety of fields. With the publication of a synthetic method for the bulk production of C 60 , there has been an explosion of research interest in this molecule. A number of intriguing experimental results have been published, including work in the area of mass spectrometry. For example, at a workshop at the 1991 ASMS meeting, Schwartz and coworkers reported a remarkable result. They showed that high energy collisions of C 60 + with He resulted not only in the expected formation of collision-induced dissociation (CID) products such as C 56 + and C 58 + (C 2 loss is the main fragmentation pathway for C 60 ), but also in the formation of products such as C 56 + + 4 and C 58 + + 4. Careful experiments with He showed that the products were C 56 He + and C 58 He + , most likely formed by the uptake of He by C 60 + during the collision. Subsequent experiments in this laboratory were able to directly observe the C 60 He + product, the product ion shifts in kinetic energy by an amount equal to the center-of-mass collision energy, consistent with kinematic arguments. C 60 He + was also observed by the Gross group and the Schwarz group. Gross and coworkers also showed that inelastic scattering processes can be observed in the collision spectrum. More recently, the Anderson group has studied reverse processes, in which ions such as He + , Li + , and C + undergo collisions with C 60 and are taken up in the collision

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
Neural network model for proton-proton collision at high energy

International Nuclear Information System (INIS)

El-Bakry, M.Y.; El-Metwally, K.A.

2003-01-01

Developments in artificial intelligence (AI) techniques and their applications to physics have made it feasible to develop and implement new modeling techniques for high-energy interactions. In particular, AI techniques of artificial neural networks (ANN) have recently been used to design and implement more effective models. The primary purpose of this paper is to model the proton-proton (p-p) collision using the ANN technique. Following a review of the conventional techniques and an introduction to the neural network, the paper presents simulation test results using an p-p based ANN model trained with experimental data. The p-p based ANN model calculates the multiplicity distribution of charged particles and the inelastic cross section of the p-p collision at high energies. The results amply demonstrate the feasibility of such new technique in extracting the collision features and prove its effectiveness
Semiclassical calculation for collision induced dissociation. II. Morse oscillator model

International Nuclear Information System (INIS)

Rusinek, I.; Roberts, R.E.

1978-01-01

A recently developed semiclassical procedure for calculating collision induced dissociation probabilities P/sup diss/ is applied to the collinear collision between a particle and a Morse oscillator diatomic. The particle--diatom interaction is described with a repulsive exponential potential function. P/sup diss/ is reported for a system of three identical particles, as a function of collision energy E/sub t/ and initial vibrational state of the diatomic n 1 . The results are compared with the previously reported values for the collision between a particle and a truncated harmonic oscillator. The two studies show similar features, namely: (a) there is an oscillatory structure in the P/sup diss/ energy profiles, which is directly related to n 1 ; (b) P/sup diss/ becomes noticeable (> or approx. =10 -3 ) for E/sub t/ values appreciably higher than the energetic threshold; (c) vibrational enhancement (inhibition) of collision induced dissociation persists at low (high) energies; and (d) good agreement between the classical and semiclassical results is found above the classical dynamic threshold. Finally, the convergence of P/sup diss/ for increasing box length is shown to be rapid and satisfactory
Effect of free-particle collisions in high energy proton and pion-induced nuclear reactions

International Nuclear Information System (INIS)

Jacob, N.P. Jr.

1975-07-01

The effect of free-particle collisions in simple ''knockout'' reactions of the form (a,aN) and in more complex nuclear reactions of the form (a,X) was investigated by using protons and pions. Cross sections for the 48 Ti(p,2p) 47 Sc and the 74 Ge(p,2p) 73 Ga reactions were measured from 0.3 to 4.6 GeV incident energy. The results indicate a rise in (p,2p) cross section for each reaction of about (25 +- 3) percent between the energies 0.3 and 1.0 GeV, and are correlated to a large increase in the total free-particle pp scattering cross sections over the same energy region. Results are compared to previous (p,2p) excitation functions in the GeV energy region and to (p,2p) cross section calculations based on a Monte Carlo intranuclear cascade-evaporation model. Cross section measurements for (π/sup +-/, πN) and other more complex pion-induced spallation reactions were measured for the light target nuclei 14 N, 16 O, and 19 F from 45 to 550 MeV incident pion energy. These measurements indicate a broad peak in the excitation functions for both (π,πN) and (π,X) reactions near 180 MeV incident energy. This corresponds to the large resonances observed in the free-particle π + p and π - p cross sections at the same energy. Striking differences in (π,πN) cross section magnitudes are observed among the light nuclei targets. The experimental cross section ratio sigma(π - ,π - n)/sigma(π + ,πN) at 180 MeV is 1.7 +- 0.2 for all three targets. The experimental results are compared to previous pion and analogous proton-induced reactions, to Monte Carlo intranuclear cascade-evaporation calculations, and to a semi-classical nucleon charge exchange model. (108 references) (auth)
PARTON SATURATION, PRODUCTION, AND EQUILIBRATION IN HIGH ENERGY NUCLEAR COLLISIONS

International Nuclear Information System (INIS)

VENUGOPALAN, R.

1999-01-01

Deeply inelastic scattering of electrons off nuclei can determine whether parton distributions saturate at HERA energies. If so, this phenomenon will also tell us a great deal about how particles are produced, and whether they equilibrate, in high energy nuclear collisions
Geometric branching model of high-energy hadron-hadron collisions

International Nuclear Information System (INIS)

Chen, W.

1988-01-01

A phenomenological model is proposed to describe collisions between hadrons at high energies. In the context of the eikonal formalism, the model consists of two components: soft and hard. The former only involves the production of particles with small transverse momenta; the latter is characterized by jet production. Geometrical scaling is taken as an essential input to describe the geometrical properties of hadrons as extended objects on the one hand, and on the other to define the soft component in both regions below and above the jet threshold. A stochastical Furry branching process is adopted as the mechanism of soft particle production, while the jet fragmentation and gluon initial-state bremsstrahlung are for the production of hadrons in hard collisions. Impact parameter and virtuality are smeared to describe the statistical averaging effects of hadron-hadron collisions. Many otherwise separated issues, ranging from elastic scattering to parton decay function, are connected together in the framework of this model. The descriptions of many prominent features of hadronic collisions are in good agreement with the observed experimental data at all available energies. Multiplicity distributions at all energies are discussed as a major issue in this paper. KNO scaling is achieved for energies within ISR range. The emergence of jets is found to be responsible not only for the violation of both geometrical scaling and KNO scaling, but also for the continuous broadening of the multiplicity distribution with ever increasing energy. It is also shown that the geometrical size of a hadron reaches an asymptote in the energy region of CERN-SppS. A Monte Carlo version of the model for soft production is constructed
High energy structures in heavy ion collisions: a multiphonon description

International Nuclear Information System (INIS)

Chomaz, P.; Blumenfeld, Y.; Frascaria, N.

1984-01-01

Energy spectra of fragments from the 36 Ar + 208 Pb reaction at 11 MeV/n exhibit structures at high excitation energies. These structures are interpreted in terms of target multi-phonon excitations built from giant resonances. The importance of such processes for the kinetic energy dissipation in heavy ion collisions is emphasized
Discovery of hydrodynamic behavior in high energy heavy ion collisions

International Nuclear Information System (INIS)

Hamagaki, Hideki

2010-01-01

The objective of high energy heavy ion collision experiments is creating high temperature and high density states to investigate hadron matter properties in such extreme conditions. Since the start of heavy ion collision experiments with BEVALAC, knowledge of the space-time evolution of collision has become indispensable for understanding the hadronic matter properties. This problem is reviewed here from the hydrodynamics view point. Although its importance has been generally recognized since the time of BEVALAC, the hydrodynamic description has not been successful because the hydrodynamic model assuming non-viscous or small fluid had not been considered to be enough to properly describe the space-time evolution of hadron-hadron collisions until the RHIC experiments. Items of the following titles are picked up and reviewed here: Development of heavy ion accelerations; Space-time evolution of hadron collision process and hydrodynamic model; Chemical freezing and kinematical freezing, including transverse momentum spectra at proton-proton collisions and particle spectra in heavy ion collisions; Elliptical azimuthal angle anisotropy; Discovery of hydrodynamic flow at BEVALAC; Problems of incident beam dependence of v2; Elliptic azimuthal angle anisotropy at RHIC; What is it that carries the elliptic anisotropy? Discussion of attainment of thermodynamical equilibrium state at RHIC; and finally investigations of fluid properties other than azimuthal anisotropy, such as, Fluid properties probed by heavy quarks and Observing QCD fluid responses. (S. Funahashi)
Heterotic Pomeron: high energy hadronic collisions in QCD

International Nuclear Information System (INIS)

Chung-I Tan

1993-01-01

A unified treatment of high energy collisions in QCD is presented. Using a probabilistic approach, both perturbative (hard) and non-perturbative (soft) components are incorporated in a consistent fashion, leading to a ''Heterotic Pomeron''. As a Regge trajectory, it is non linear, approaching 1 in the limit t → -∞. 2 tabs., 9 refs
Final stage of high energy hadron-nucleus nuclear collision reactions

International Nuclear Information System (INIS)

Strugal'ski, Z.; Jedrzejec, H.; Strugalska-Gola, E.; Mulas, E.

1996-01-01

The final or 'slow' stage of the hadron-nucleus collision reactions at high energy is considered on the basis of the collision mechanism prompted experimentally. The transmutation process of the damaged target nucleus into nucleons and stable nuclear fragments is discussed. Relations between intensities or multiplicities n p of the emitted fast protons and the mean intensities or multiplicities b > of the evaporated nucleons and nuclear fragments are presented. 14 refs
High energy particle collisions near black holes

Directory of Open Access Journals (Sweden)

Zaslavskii O. B.

2016-01-01

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

International Nuclear Information System (INIS)

Myers, W.D.

1978-01-01

A model is developed for high-energy heavy-ion collisions that treats the variation across the overlap region of the target and projectile in the amount of energy and momentum that is deposited. The expression for calculating any observable takes the form of a sum over a series of terms, each one of which consists of a geometric, a kinematic, and a statistical factor. The geometrical factors for a number of target projectile systems are tabulated. (Auth.)
Mean free paths for high energy hadron collisions in nuclear matter

International Nuclear Information System (INIS)

Strugalski, Z.

1983-01-01

The mean free paths for various collisions of high energy pion in nuclear matter are determined experimentally using pion-xenon nucleus collision events at 3.5 GeV/c momentum. The relation between the mean free path lambdasub(i) for hadron-nucleon particle producing collisions in nuclear matter and corresponding cross section σsub(i) for particle producing collisions of this hadron with free nucleon is derived and discussed. This relation is lambdasub(i)=k/σsub(i), where lambdasub(i) is in nucleons per fm 2 and σ sub(i) - in fm 2 per nucleon, correspondingly, k=3.00+-0.26 is a coefficient accounting for the display of the nucleon inner structure in hadron-nucleus collisions
Quarkonium production in high energy proton-proton and proton-nucleus collisions

International Nuclear Information System (INIS)

Conesa del Valle, Z.; Corcella, G.; Fleuret, F.; Ferreiro, E.G.; Kartvelishvili, V.; Kopeliovich, B.; Lansberg, J.P.; Lourenco, C.; Martinez, G.; Papadimitriou, V.; Satz, H.; Scomparin, E.; Ullrich, T.; Teryaev, O.; Vogt, R.; Wang, J.X.

2011-01-01

We present a brief overview of the most relevant current issues related to quarkonium production in high energy proton-proton and proton-nucleus collisions along with some perspectives. After reviewing recent experimental and theoretical results on quarkonium production in pp and pA collisions, we discuss the emerging field of polarisation studies. Afterwards, we report on issues related to heavy-quark production, both in pp and pA collisions, complemented by AA collisions. To put the work in broader perpectives, we emphasize the need for new observables to investigate the quarkonium production mechanisms and reiterate the qualities that make quarkonia a unique tool for many investigations in particle and nuclear physics.
Charged Particle, Photon Multiplicity, and Transverse Energy Production in High-Energy Heavy-Ion Collisions

Directory of Open Access Journals (Sweden)

Raghunath Sahoo

2015-01-01

Full Text Available We review the charged particle and photon multiplicities and transverse energy production in heavy-ion collisions starting from few GeV to TeV energies. The experimental results of pseudorapidity distribution of charged particles and photons at different collision energies and centralities are discussed. We also discuss the hypothesis of limiting fragmentation and expansion dynamics using the Landau hydrodynamics and the underlying physics. Meanwhile, we present the estimation of initial energy density multiplied with formation time as a function of different collision energies and centralities. In the end, the transverse energy per charged particle in connection with the chemical freeze-out criteria is discussed. We invoke various models and phenomenological arguments to interpret and characterize the fireball created in heavy-ion collisions. This review overall provides a scope to understand the heavy-ion collision data and a possible formation of a deconfined phase of partons via the global observables like charged particles, photons, and the transverse energy measurement.
Photon and dilepton production in high-energy heavy-ion collisions

Indian Academy of Sciences (India)

2015-05-07

May 7, 2015 ... Photons; dileptons; Relativistic Heavy Ion Collider; Large Hadron Collider; quark ... the collisions produces relatively high pT photons, often referred to ..... energy have been found for identified charged hadrons at RHIC [25].
Fragmentation of high-energy ionic hydrogen clusters by single collision with helium

International Nuclear Information System (INIS)

Ouaskit, S.; Farizon, B.; Farizon, M.; Gaillard, M.J.; Chevarier, A.; Chevarier, N.; Gerlic, E.; Stern, M.

1994-09-01

Fragmentation of mass-selected 60-keV/amu-H n + induced by single collision with helium has been studied for various cluster sizes n (9, 13,21, 25, and 31). The absolute cross sections of the charged fragments H p + are measured from p equal to n-2. The deduced mass distributions are strongly different from those obtained at lower collision energy (where molecular evaporation is mainly involved) due to a strong production of ionic fragments with a size of p/n -τ , where A is the normalized fragment mass (p/n) and τ an exponent close to 2.6. (authors)
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
Characteristics of particle production in high energy nuclear collisions a model-based analysis

CERN Document Server

Guptaroy, P; Bhattacharya, S; Bhattacharya, D P

2002-01-01

The present work pertains to the production of some very important negatively charged secondaries in lead-lead and gold-gold collisions at AGS, SPS and RHIC energies. We would like to examine here the role of the particular version of sequential chain model (SCM), which was applied widely in the past in analysing data on various high-energy hadronic collisions, in explaining now the latest findings on the features of particle production in the relativistic nucleus-nucleus collisions. The agreement between the model of our choice and the measured data is found to be modestly satisfactory in cases of the most prominent and abundantly produced varieties of the secondaries in the above-stated two nuclear collisions. (25 refs).
Point defects migration induced by subthreshold focused collisions

International Nuclear Information System (INIS)

Tenenbaum, A.; Doan, N.V.

1976-01-01

The persistence of the phenomenon of focused atomic collisions in a large range of temperature up to 0.3 Tf in copper have been shown using computer simulation by the Molecular Dynamics Technique. On the other hand, different processes by which the subthreshold collisions can induce a vacancy migration have been investigated. A quantitative model relating the induced vacancy migration to the flux density, direction and energy of incident particles has been developed. For example in an electron irradiation, it is found that the induced vacancy jump frequency depends notably on the incident direction and exhibits a maximum value in the range of electron energy between 60 and 100keV

Transparency in high-energy nuclear collisions

International Nuclear Information System (INIS)

Karol, P.J.

1992-01-01

Problems associated with transparency schemes based on sharp cutoff models are discussed. The soft spheres model of hadron-nucleus and nucleus-nucleus collisions has been used to explore the influence of the realistic nuclear density geometry on transparency. An average nuclear transparency and an average reaction transparency are defined and their dependence on target and projectile dimensions and on the hadron-nucleon collision cross section are described. The results are expected to be valid for projectile energies above several hundred MeV/nucleon through the ultrarelativistic regime. For uniform (hard sphere) nuclear profiles, methods for obtaining effective total transparencies are suggested
Computer simulation studies of high energy collision cascades

International Nuclear Information System (INIS)

Robinson, M.T.

1991-07-01

A modified binary collision approximation allowing the proper order of the collisions in time was used to study cascades in Cu and Au at primary kinetic energies up to 100 keV. Nonlinearities were approximated by letting already-stopped cascade atoms become targets in later collisions, using an improved method of locating potential targets to extend the calculations to energies much higher than heretofore. Beside the effect of the approximate nonlinearity, the effect of thermal disorder in the targets was examined. Target redisplacements reduce the damage in Cu by 3% at most, but in Au they reduce it by amounts up to 20% at 100 keV. Thermal disorder is also important: by disrupting crystal effects, the damage is reduced significantly. 11 refs., 4 figs
Low-energy electron collisions with metal clusters: Electron capture and cluster fragmentation

International Nuclear Information System (INIS)

Kresin, V.V.; Scheidemann, A.; Knight, W.D.

1993-01-01

The authors have carried out the first measurement of absolute cross sections for the interaction between electrons and size-resolved free metal clusters. Integral inelastic scattering cross sections have been determined for electron-Na n cluster collisions in the energy range from 0.1 eV to 30 eV. At energies ≤1 eV, cross sections increase with decreasing impact energies, while at higher energies they remain essentially constant. The dominant processes are electron attachment in the low-energy range, and collision-induced fragmentation at higher energies. The magnitude of electron capture cross sections can be quantitatively explained by the effect of the strong polarization field induced in the cluster by the incident electron. The cross sections are very large, reaching values of hundreds of angstrom 2 ; this is due to the highly polarizable nature of metal clusters. The inelastic interaction range for fragmentation collisions is also found to considerably exceed the cluster radius, again reflecting the long-range character of electron-cluster interactions. The important role played by the polarization interaction represents a bridge between the study of collision processes and the extensive research on cluster response properties. Furthermore, insight into the mechanisms of electron scattering is important for understanding production and detection of cluster ions in mass spectrometry and related processes
High energy hadron-nucleus collision

International Nuclear Information System (INIS)

Takagi, Fujio

1983-02-01

This is a lecture note concerning high energy hadron-nucleus collision. The lecture gives the inelastic total cross section and the Glanber approximate multiple scattering formula at first. The mechanism of nuclear spallation is described in a cylindrical image. The multiplicity, the one particle distribution and the time-space structure of particle production are discussed. Various models are presented. The attenuation of forward particles and the structure of hadrons are discussed for each model. The atomic number (A) dependence of the production of large transverse momentum particles and jet, and the A dependence of charged multiplicity are presented. The backward production of particles and many body correlation are discussed. Lepton pair production and the initial interaction of constituents, collective interaction, multi quark state and phase transition are described. (Kato, T.)
Soft electromagnetic bremsstrahlung in inelastic hadronic collisions at high and intermediate energies

International Nuclear Information System (INIS)

Rueckl, R.

1978-01-01

Electromagnetic bremsstrahlung in hadronic collisions was studied extensively at low and intermediate energies. It was found that the infrared divergent term of the cross section describes the data well up to surprisingly large photon energies. Using essentially the same soft photon approximation, production of low mass-low energy electron pairs via internal conversion of soft virtual bremsstrahlung accompanying the production of charged hadrons in hadron-hadron collisions at very high and intermediate energies. The resulting electron yields explain, at least in part, the direct electrons with small transverse momenta seen at the ISR, and are in no contradiction to the rates observed at LAMPF
Z-scaling in proton-nucleus collisions at high energies

International Nuclear Information System (INIS)

Zborovsky, I.; Tokarev, M.V.; Panebrattsev, Yu.A.; Skoro, G.P.

1997-01-01

New scaling, z-scaling, in the inclusive particle production in pA collisions is studied. The scaling function H A (z) is expressed via the inclusive cross section of particle production Ed 3 σ/dq 3 and the particle multiplicity density dN/dη at pseudorapidity η=0 in the corresponding nucleon-nucleon (NN) center-of-mass (CMS) system. The dependence of H A (z) on scaling variable z, the center-of-mass energy √, and the detection angle θ is investigated. The available experimental data on inclusive particle production (π ± , K ± ) in pA interactions at high energies are used to verify the universality of z-scaling found in hadron-hadron collisions. The A-dependence of H A (z) for π + -meson production is studied. It is shown that the experimental data >from pd collisions confirm the scaling properties of the function H d (z). Some predictions for H au (z) concerning production of π + -mesons in pAu interaction using the HIJING Monte Carlo code have been made. The obtained results can be of interest for future experiments at RHI and LHC in searching the signals of quark-gluon plasma formation
Initial angular momentum and flow in high energy nuclear collisions

Science.gov (United States)

Fries, Rainer J.; Chen, Guangyao; Somanathan, Sidharth

2018-03-01

We study the transfer of angular momentum in high energy nuclear collisions from the colliding nuclei to the region around midrapidity, using the classical approximation of the color glass condensate (CGC) picture. We find that the angular momentum shortly after the collision (up to times ˜1 /Qs , where Qs is the saturation scale) is carried by the "β -type" flow of the initial classical gluon field, introduced by some of us earlier. βi˜μ1∇iμ2-μ2∇iμ1 (i =1 ,2 ) describes the rapidity-odd transverse energy flow and emerges from Gauss's law for gluon fields. Here μ1 and μ2 are the averaged color charge fluctuation densities in the two nuclei, respectively. Interestingly, strong coupling calculations using anti-de Sitter/conformal field theory (AdS/CFT) techniques also find an energy flow term featuring this particular combination of nuclear densities. In classical CGC the order of magnitude of the initial angular momentum per rapidity in the reaction plane, at a time 1 /Qs , is |d L2/d η |≈ RAQs-3ɛ¯0/2 at midrapidity, where RA is the nuclear radius, and ɛ¯0 is the average initial energy density. This result emerges as a cancellation between a vortex of energy flow in the reaction plane aligned with the total angular momentum, and energy shear flow opposed to it. We discuss in detail the process of matching classical Yang-Mills results to fluid dynamics. We will argue that dissipative corrections should not be discarded to ensure that macroscopic conservation laws, e.g., for angular momentum, hold. Viscous fluid dynamics tends to dissipate the shear flow contribution that carries angular momentum in boost-invariant fluid systems. This leads to small residual angular momentum around midrapidity at late times for collisions at high energies.
QMD and JAM calculations for high energy nucleon-nucleus collisions

International Nuclear Information System (INIS)

Niita, Koji

2002-01-01

We describe the two simulation codes, QMD and JAM (Jet AA Microscopic Transport Model), for high energy nuclear reactions. QMD can treat the nucleus-nucleus reactions as well as nucleon-nucleus reactions based on the molecular dynamics. We have applied the QMD code intensively to nucleon-nucleus reactions and checked its validity. The cross sections obtained by the QMD are now used for evaluation of high energy nuclear data in JAERI. JAM is a hadronic cascade code including the resonance and string model for the hadron-hadron collisions at high energy up to 200 GeV. We have developed a high energy particle transport code NMTC/JAM by including the JAM code for the intra-nuclear cascade part. (author)
Triple parton scatterings in high-energy proton-proton collisions arXiv

CERN Document Server

d'Enterria, David

2017-01-01

A generic expression to compute triple parton scattering cross sections in high-energy proton-proton (pp) collisions is presented as a function of the corresponding single parton cross sections and the transverse parton profile of the proton encoded in an effective parameter σeff,TPS. The value of σeff,TPS is closely related to the similar effective cross section that characterizes double parton scatterings, and amounts to σeff,TPS=12.5±4.5 mb. Estimates for triple charm (cc¯) and bottom (bb¯) production in pp collisions at LHC and FCC energies are presented based on next-to-next-to-leading-order perturbative calculations for single cc¯, bb¯ cross sections. At s≈100 TeV, about 15% of the pp collisions produce three cc¯ pairs from three different parton-parton scatterings.
Quenching ilmenite with a high-temperature and high-pressure phase using super-high-energy ball milling.

Science.gov (United States)

Hashishin, Takeshi; Tan, Zhenquan; Yamamoto, Kazuhiro; Qiu, Nan; Kim, Jungeum; Numako, Chiya; Naka, Takashi; Valmalette, Jean Christophe; Ohara, Satoshi

2014-04-25

The mass production of highly dense oxides with high-temperature and high-pressure phases allows us to discover functional properties that have never been developed. To date, the quenching of highly dense materials at the gramme-level at ambient atmosphere has never been achieved. Here, we provide evidence of the formation of orthorhombic Fe2TiO4 from trigonal FeTiO3 as a result of the high-temperature (>1250 K) and high-pressure (>23 GPa) condition induced by the high collision energy of 150 gravity generated between steel balls. Ilmenite was steeply quenched by the surrounding atmosphere, when iron-rich ilmenite (Fe2TiO4) with a high-temperature and high-pressure phase was formed by planetary collisions and was released from the collision points between the balls. Our finding allows us to infer that such intense planetary collisions induced by high-energy ball milling contribute to the mass production of a high-temperature and high-pressure phase.
Investigation of Rare Particle Production in High Energy Nuclear Collisions

International Nuclear Information System (INIS)

Crawford, Henry J.; Engelage, Jon M.

1999-01-01

Our program is an investigation of the hadronization process through measurement of rare particle production in high energy nuclear interactions. Such collisions of heavy nuclei provide an environment similar in energy density to the conditions in the Big Bang. We are currently involved in two major experiments to study this environment, E896 at the AGS and STAR at RHIC. We have completed our physics running of E896, a search for the H dibaryon and measurement of hyperon production in AuAu collisions, and are in the process of analyzing the data. We have produced the electronics and software for the STAR trigger and will begin to use these tools to search for anti-nuclei and strange hadrons when RHIC turns on later this year
Mesonic atom production in high-energy nuclear collisions

International Nuclear Information System (INIS)

Wakai, M.; Bando, H.; Sano, M.

1987-08-01

The production probability of π-mesonic atom in high-energy nuclear collisions is estimated by a coalescence model. The production cross section is calculated for p + Ne and Ne + Ne systems at 2.1 GeV/A and 5.0 GeV/A beam energy. It is shown that nuclear fragments with larger charge numbers have the advantage in the formation of π-mesonic atoms. The cross section is proportional to Z 3 and of the order of magnitude of 1 ∼ 10 μb in all the above cases. The production cross sections of K-mesonic atoms are also estimated. (author)
Mobility of point defects induced by subthreshold collisions

International Nuclear Information System (INIS)

Tenenbaum, A.; Nguyen Van Doan

1976-01-01

The effect of thermal vibrations on atomic collision focusing was studied with the view to demonstrate that such collisions may induce point defect migration through the crystal. The persistence of the phenomenon of focused atomic collisions in a crystal at thermal equilibrium was studied, using a computer simulation by the Molecular Dynamics Technique. In the temperature range (0 to 500K) matter and momentum transfers in c.f.c. crystals proceed mainly by focused collisions along and directions. Their contribution to the induced migration of radiation defects was determined from the threshold energy of every primary able to be involved in the process. As an example, the quantitative model is applied to electron irradiation along the crystallographic directions [fr
Energy dependence of the ionization of highly excited atoms by collisions with excited atoms

International Nuclear Information System (INIS)

Shirai, T.; Nakai, Y.; Nakamura, H.

1979-01-01

Approximate analytical expressions are derived for the ionization cross sections in the high- and low-collision-energy limits using the improved impulse approximation based on the assumption that the electron-atom inelastic-scattering amplitude is a function only of the momentum transfer. Both cases of simultaneous excitation and de-excitation of one of the atoms are discussed. The formulas are applied to the collisions between two excited hydrogen atoms and are found very useful for estimating the cross sections in the wide range of collisions energies
A plausible picture of high-energy proton-nucleus collisions

International Nuclear Information System (INIS)

Kim, C.O.

1976-01-01

Results experimentally obtained from jets of E(p)=10-10 3 GeV in nuclear emulsion show that the target nucleus in proton-nucleus collisions seems to present ''limiting fragmentation''. In the same energy range, proton-nucleus collisions resemble closely proton-proton collisions and asymmetric shape of rapidities is only caused by the break-up products of heavy targets [fr
Rapidity distributions in unequal nuclei collision at high energies and hydrodynamic model

International Nuclear Information System (INIS)

Zhuang Pengfei; Wang Zhengqing; Liu Liansou

1986-01-01

The mechanism of high-energy A'-A collisions (A>A', A'sup(1/3)>>1) and the space-time evolution of the fluid formed in the collision are analysed. The corresponding 1+1 dimensional hydrodynamic equations are set up. The average rapidity distributions are estimated and compared with cosmic ray data. The origin of the unsymmetry of rapidity distributions is explained. (orig.)
Rapidity distributions in unequal nuclei collision at high energies and hydrodynamical model

International Nuclear Information System (INIS)

Zhuang Pengfei; Wang Zhengqing

1987-01-01

The mechanism of high-energy A'-A collision (A > A', A' 1/3 >> 1) and the space-time evolution of the fluid formed in the collision are analysed. The corresponding 1 + 1 dimensional hydrodynamical equations are established. The average rapidity distributions are estimated and compared with some cosmic ray events. The origin of the nonsymmetry of rapidity distribution is explained
Balance Function in High-Energy Collisions

International Nuclear Information System (INIS)

Tawfik, A.; Shalaby, Asmaa G.

2015-01-01

Aspects and implications of the balance functions (BF) in high-energy physics are reviewed. The various calculations and measurements depending on different quantities, for example, system size, collisions centrality, and beam energy, are discussed. First, the different definitions including advantages and even short-comings are highlighted. It is found that BF, which are mainly presented in terms of relative rapidity, and relative azimuthal and invariant relative momentum, are sensitive to the interaction centrality but not to the beam energy and can be used in estimating the hadronization time and the hadron-quark phase transition. Furthermore, the quark chemistry can be determined. The chemical evolution of the new-state-of-matter, the quark-gluon plasma, and its temporal-spatial evolution, femtoscopy of two-particle correlations, are accessible. The production time of positive-negative pair of charges can be determined from the widths of BF. Due to the reduction in the diffusion time, narrowed widths refer to delayed hadronization. It is concluded that BF are powerful tools characterizing hadron-quark phase transition and estimating some essential properties
Hawking-Unruh Hadronization and Strangeness Production in High Energy Collisions

CERN Document Server

Castorina, P

2014-01-01

The thermal multihadron production observed in different high energy collisions poses many basic problems: why do even elementary, $e^+e^-$ and hadron-hadron, collisions show thermal behaviour? Why is there in such interactions a suppression of strange particle production? Why does the strangeness suppression almost disappear in relativistic heavy ion collisions? Why in these collisions is the thermalization time less than $\\simeq 0.5$ fm/c? We show that the recently proposed mechanism of thermal hadron production through Hawking-Unruh radiation can naturally answer the previous questions. Indeed, the interpretation of quark- antiquark pairs production, by the sequential string breaking, as tunneling through the event horizon of colour confinement leads to thermal behavior with a universal temperature, $T \\simeq 170$ Mev,related to the quark acceleration, a, by $T=a/2\\pi$. The resulting temperature depends on the quark mass and then on the content of the produced hadrons, causing a deviation from full equilib...
Multinucleon interactions in collisions with nuclei at high energies

International Nuclear Information System (INIS)

Braun, M.A.

1988-11-01

The parton picture of multiple hA and AA scattering at high energies is developed. It is shown that it leads to the standard Glauber amplitude provided the number of partons in a hadron is distributed according to Poisson's law. Within this picture collisions of more than a pair of nucleons are considered. For AA scattering a two-dimensional effective quantum field theory is constructed which allows to conveniently calculate contributions to the amplitude with a given number of loops. The AGK rules for AA scattering are established. Inclusive cross-sections for particle production in hA and AA collisions are studied both in the non-cumulative and cumulative kinematical regions. (author). 13 refs, 9 figs

Multiparticle correlations and intermittency in high energy collisions

CERN Document Server

Bozek, P

1992-01-01

In this work the analysis of the intermittency signal observed in high energy experi- ments is done using multiparticle distributions and correlation functions. The effect of the dimensional projection of the multiparticle distributions on one or two-dimensional subspace is discussed. The structure of the multiparticle cumulants is analyzed for the DELPHI e + e~ annihilation data. The language of the self-similar distribution func- tions, which is used in this work, is shown to be largely equivalent to the well known a-model. In the case of the ultrarelativistic nuclear collisions, where the Monte-Carlo simulations fail to reproduce the data, we argue that the observed intermittency pattern is a signal of some nonlinear effect beyond the simple superposition of nucleon-nucleon collisions. The model of spatiotemporal intermittency is discussed in details and is shown to reproduce qualitatively the dependence of t...
Jet and Leading Hadron Production in High-energy Heavy-ion Collisions

International Nuclear Information System (INIS)

Wang, Xin-Nian

2005-01-01

Jet tomography has become a powerful tool for the study of properties of dense matter in high-energy heavy-ion collisions. I will discuss recent progresses in the phenomenological study of jet quenching, including momentum, colliding energy and nuclear size dependence of single hadron suppression, modification of dihadron correlations and the soft hadron distribution associated with a quenched jet
Energy Dependence of Particle Multiplicities in Central Au+Au Collisions

Science.gov (United States)

Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Corbo, J.; Decowski, M. P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Henderson, C.; Hicks, D.; Hofman, D.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A.; Mülmenstädt, J.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Rafelski, M.; Rbeiz, M.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

2002-01-01

We present the first measurement of the pseudorapidity density of primary charged particles in Au+Au collisions at (sNN) = 200 GeV. For the 6% most central collisions, we obtain dNch/dη\\|\\|η\\|<1 = 650+/-35(syst). Compared to collisions at (sNN) = 130 GeV, the highest energy studied previously, an increase by a factor of 1.14+/-0.05 at 90% confidence level, is found. The energy dependence of the pseudorapidity density is discussed in comparison with data from proton-induced collisions and theoretical predictions.
Collision-induced dissociation of aflatoxins.

Science.gov (United States)

Tóth, Katalin; Nagy, Lajos; Mándi, Attila; Kuki, Ákos; Mézes, Miklós; Zsuga, Miklós; Kéki, Sándor

2013-02-28

The aflatoxin mycotoxins are particularly hazardous to health when present in food. Therefore, from an analytical point of view, knowledge of their mass spectrometric properties is essential. The aim of the present study was to describe the collision-induced dissociation behavior of the four most common aflatoxins: B1, B2, G1 and G2. Protonated aflatoxins were produced using atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) combined with high-performance liquid chromatography (HPLC). For the tandem mass spectrometry (MS/MS) experiments nitrogen was used as the collision gas and the collision energies were varied in the range of 9-44 eV (in the laboratory frame). The major APCI-MS/MS fragmentations of protonated aflatoxins occurred at 30 eV collision energy. The main fragmentation channels were found to be the losses of a series of carbon monoxide molecules and loss of a methyl radical, leading to the formation of radical-type product ions. In addition, if the aflatoxin molecule contained an ether- or lactone-oxygen atom linked to a saturated carbon atom, loss of a water molecule was observed from the [M + H](+) ion, especially in the case of aflatoxins G1 and G2. A relatively small modification in the structure of aflatoxins dramatically altered the fragmentation pathways and this was particularly true for aflatoxins B1 and B2. Due to the presence of a C = C double bond connected to the ether group in aflatoxin B1 no elimination of water was observed but, instead, formation of radical-type product ions occurred. Fragmentation of protonated aflatoxin B1 yielded the most abundant radical-type cations. Copyright © 2013 John Wiley & Sons, Ltd.
Geometric and electronic structures of molecular ions from high energy collisions

International Nuclear Information System (INIS)

Groeneveld, K.O.

1983-01-01

This chapter examines the characteristics of heavy ion collision and of beam foil spectroscopy. It discusses the kinematic consequences of the high energies and presents results from ''Coulomb explosion'' and structure determination of molecular ions. It demonstrates that studies of molecular ions with accelerators can provide electronic and geometric structure information of molecules or molecular ions and points out that the understanding of the microscopic processes at such high energies is incomplete and needs further experimental and theoretical efforts
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
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 ...
Ion induced fragmentation of biomolecular systems at low collision energies

International Nuclear Information System (INIS)

Bernigaud, V; Adoui, L; Chesnel, J Y; Rangama, J; Huber, B A; Manil, B; Alvarado, F; Bari, S; Hoekstra, R; Postma, J; Schlathoelter, T

2009-01-01

In this paper, we present results of different collision experiments between multiply charged ions at low collision energies (in the keV-region) and biomolecular systems. This kind of interaction allows to remove electrons form the biomolecule without transferring a large amount of vibrational excitation energy. Nevertheless, following the ionization of the target, fragmentation of biomolecular species may occur. It is the main objective of this work to study the physical processes involved in the dissociation of highly electronically excited systems. In order to elucidate the intrinsic properties of certain biomolecules (porphyrins and amino acids) we have performed experiments in the gas phase with isolated systems. The obtained results demonstrate the high stability of porphyrins after electron removal. Furthermore, a dependence of the fragmentation pattern produced by multiply charged ions on the isomeric structure of the alanine molecule has been shown. By considering the presence of other surrounding biomolecules (clusters of nucleobases), a strong influence of the environment of the biomolecule on the fragmentation channels and their modification, has been clearly proven. This result is explained, in the thymine and uracil case, by the formation of hydrogen bonds between O and H atoms, which is known to favor planar cluster geometries.
Proton rapidity distribution in nucleus-nucleus collisions at high energy

International Nuclear Information System (INIS)

Liu, F.H.

2002-01-01

The proton rapidity distributions in nucleus-nucleus collisions at the Alternating Gradient Synchrotron (AGS) and the Super Proton Synchrotron (SPS) energies are analysed by the revised thermalized cylinder model. The calculated results are compared and found to he in agreement with the experimental data of Si-AI and Si-Pb collisions at 14.6 A GeV/c, Pb-Pb collisions at 158 A GeV/c, and S-S collisions at 200 A GeV/c. (Author)
Constituent quark model for nuclear stopping in high energy nuclear collisions

International Nuclear Information System (INIS)

Choi, T.K.; Maruyama, M.; Takagi, F.

1997-01-01

We study nuclear stopping in high energy nuclear collisions using the constituent quark model. It is assumed that wounded nucleons with a different number of interacted quarks hadronize in different ways. The probabilities of having such wounded nucleons are evaluated for proton-proton, proton-nucleus, and nucleus-nucleus collisions. After examining our model in proton-proton and proton-nucleus collisions and fixing the hadronization functions, it is extended to nucleus-nucleus collisions. It is used to calculate the rapidity distribution and the rapidity shift of final-state protons in nucleus-nucleus collisions. The computed results are in good agreement with the experimental data on 32 S+ 32 S at E lab =200A GeV and 208 Pb+ 208 Pb at E lab =160A GeV. Theoretical predictions are also given for proton rapidity distribution in 197 Au+ 197 Au at √(s)=200A GeV (BNL-RHIC). We predict that the nearly baryon-free region will appear in the midrapidity region and the rapidity shift is left-angle Δy right-angle=2.24
Peripheral collisions in Ar induced reactions between 27 and 44 A.MeV: study of energy dissipation by measuring the correlated neutron multiplicities

International Nuclear Information System (INIS)

Guerreau, D.; Doubre, H.; Galin, J.; Pouthas, J.; Jahnke, U.; Jiang, D.X.; Lott, B.; Jacquet, D.

1988-01-01

A 4 π detector measuring the neutron multiplicities has been used to investigate the energy dissipation during peripheral collisions in Ar induced reactions around the Fermi Energy. Besides the persistance of direct transfer reactions for the most peripheral collisions, there are strong evidences for the occurrence of quite large energy dissipation, a clear signature for the one body friction to still play a major role at these intermediate energies
Modeling defect production in high energy collision cascades

International Nuclear Information System (INIS)

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

1993-01-01

A multi-model approach roach (MMA) to simulating defect production processes at the atomic scale is described that incorporates molecular dynamics (MD), binary collision approximation (BCA) calculations and stochastic annealing simulations. The central hypothesis of the MMA is that the simple, fast computer codes capable of simulating large numbers of high energy cascades (e.g., BCA codes) can be made to yield the correct defect configurations when their parameters are calibrated using the results of the more physically realistic MD simulations. The calibration procedure is investigated using results of MD simulations of 25 keV cascades in copper. The configurations of point defects are extracted from the MD cascade simulations at the end of the collisional phase, similar to the information obtained with a binary collision model. The MD collisional phase defect configurations are used as input to the ALSOME annealing simulation code, and values of the ALSOME quenching parameters are determined that yield the best fit to the post-quenching defect configurations of the MD simulations
The Spectator-Induced Electromagnetic Effect on Meson Production in Nucleus-Nucleus Collisions at SPS Energies

Directory of Open Access Journals (Sweden)

Rybicki Andrzej

2012-12-01

Full Text Available The electromagnetic interaction between the spectator system and the charged mesons produced in the course of the high energy heavy ion collision was studied experimentally and theoretically in earlier works [1,2]. This effect was found to result in very large distortions of the final state spectra of the produced mesons [3] and to bring new information on the space-time evolution of the non-perturbative meson production process [4]. In this paper a more extended analysis of this effect will be presented, including a comparative study between charged meson spectra produced in Pb+Pb collisions as well as collisions of Pb ions with smaller nuclei. The experimental results will be compared with Monte Carlo simulations, giving a fair overall understanding of the interplay between the strong and the electromagnetic interaction in the heavy ion collision. A universal behaviour of charged meson spectra emerges from the above comparative study. This gives a unique chance of using the spectator charge as a tool to study the space-time evolution of the high energy nucleus-nucleus reaction.
Investigation of nuclear matter properties by means of high energy nucleus-nucleus collisions

International Nuclear Information System (INIS)

Stock, R.

1985-09-01

We review recent advances towards an understanding of high density nuclear matter, as created in central collisions of nuclei at high energy. In particular, information obtained for the nuclear matter equation of state will be discussed. The lectures focus on the Bevalac energy domain of 0.4 to 2 GeV per projectile nucleon. (orig.)
Testing the black disk limit in $pp$ collisions at very high energy

OpenAIRE

Brogueira, P.; de Deus, J. Dias

2011-01-01

We use geometric scaling invariant quantities to measure the approach, or not, of the imaginary and real parts of the elastic scattering amplitude, to the black disk limit, in $pp$ collisions at very high energy.
Laser induced energy transfer

International Nuclear Information System (INIS)

Falcone, R.W.

1979-01-01

Two related methods of rapidly transferring stored energy from one excited chemical species to another are described. The first of these, called a laser induced collision, involves a reaction in which the energy balance is met by photons from an intense laser beam. A collision cross section of ca 10 - 17 cm 2 was induced in an experiment which demonstrated the predicted dependence of the cross section on wavelength and power density of the applied laser. A second type of laser induced energy transfer involves the inelastic scattering of laser radiation from energetically excited atoms, and subsequent absorption of the scattered light by a second species. The technique of producing the light, ''anti-Stokes Raman'' scattering of visible and infrared wavelength laser photons, is shown to be an efficient source of narrow bandwidth, high brightness, tunable radiation at vacuum ultraviolet wavelengths by using it to excite a rare gas transition at 583.7 A. In addition, this light source was used to make the first measurement of the isotopic shift of the helium metastable level at 601 A. Applications in laser controlled chemistry and spectroscopy, and proposals for new types of lasers using these two energy transfer methods are discussed
Energy dependence of opaqueness for pp collisions at high energies

CERN Document Server

Chou, T T

1978-01-01

Opaqueness of pp collisions is evaluated at three CERN-ISR energies. Comparisons with predictions of the factorisable eikonal models and the scaling hypothesis are made. It appears that results are in favour of the factorisable models. (20 refs).
Study of proton-nucleus collisions at high energies based on the hydrodynamical model

International Nuclear Information System (INIS)

Masuda, N.; Weiner, R.M.

1978-01-01

We study proton-nucleus collisions at high energies using the one-dimensional hydrodynamical model of Landau with special emphasis on the effect of the size of the target nucleus and of the magnitude of velocity of sound of excited hadronic matter. We convert a collision problem of a proton and a nucleus with a spherical shape into that of a proton and a one-dimensional nuclear tunnel whose length is determined from the average impact parameter. By extending the methods developed by Milekhin and Emelyanov, we obtain the solutions of the hydrodynamical equations of proton-nucleus collisions for arbitrary target tunnel length and arbitrary velocity of sound. The connection between these solutions and observable physical quantities is established as in the work of Cooper, Frye, and Schonberg. Extensive numerical analyses are made at E/sub lab/ = 200 GeV and for the velocity of sound u = 1/√3 of a relativistic ideal Bose gas and u = 1/(7.5)/sup 1/2/ of an interacting Bose gas. In order to compare proton-nucleus collisions with proton-proton collisions, all the analyses are made in the equal-velocity frame. We find the following results. (1) In comparing the number of secondary particles produced in p-A collisions N/sub p/A with those in p-p collisions N/sub p/p, while most of the excess of N/sub p/A over N/sub p/p is concentrated in the backward rapidity region, there exists also an increase of N/sub p/A with A in the forward rapidity region. This result is at variance with the predictions of the energy-flux-cascade model and of the coherent-production model. (2) The excess energies are contained exclusively in the backward region. We also find evidence for new phenomena in proton-nucleus collisions. (3) The existence of an asymmetry of average energies of secondary particles between forward and backward regions, in particular, >> for larger nuclear targets. Thus, energetic particles are predominantly produced in the backward region
The gluon condensation at high energy hadron collisions

Energy Technology Data Exchange (ETDEWEB)

Zhu, Wei, E-mail: weizhu@mail.ecnu.edu.cn [Department of Physics, East China Normal University, Shanghai 200241 (China); Lan, Jiangshan [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2017-03-15

We report that the saturation/CGC model of gluon distribution is unstable under action of the chaotic solution in a nonlinear QCD evolution equation, and it evolves to the distribution with a sharp peak at the critical momentum. We find that this gluon condensation is caused by a new kind of shadowing–antishadowing effects, and it leads to a series of unexpected effects in high energy hadron collisions including astrophysical events. For example, the extremely intense fluctuations in the transverse-momentum and rapidity distributions of the gluon jets present the gluon-jet bursts; a sudden increase of the proton–proton cross sections may fill the GZK suppression; the blocking QCD evolution will restrict the maximum available energy of the hadron–hadron colliders.
Application of the non-extensive statistical approach to high energy particle collisions

Science.gov (United States)

Bíró, Gábor; Barnaföldi, Gergely Gábor; Biró, Tamás Sándor; Ürmössy, Károly

2017-06-01

In high-energy collisions the number of created particles is far less than the thermodynamic limit, especially in small colliding systems (e.g. proton-proton). Therefore final-state effects and fluctuations in the one-particle energy distribution are appreciable. As a consequence the characterization of identified hadron spectra with the Boltzmann - Gibbs thermodynamical approach is insuffcient [1]. Instead particle spectra measured in high-energy collisions can be described very well with Tsallis -Pareto distributions, derived from non-extensive thermodynamics [2, 3]. Using the Tsallis q-entropy formula, a generalization of the Boltzmann - Gibbs entropy, we interpret the microscopic physics by analysing the Tsallis q and T parameters. In this paper we give a quick overview on these parameters, analyzing identified hadron spectra from recent years in a wide center-of-mass energy range. We demonstrate that the fitted Tsallis-parameters show dependency on the center-of-mass energy and particle species. Our findings are described well by a QCD inspired evolution ansatz. Based on this comprehensive study, apart from the evolution, both mesonic and barionic components found to be non-extensive (q > 1), beside the mass ordered hierarchy observed in parameter T.

Simulation of a Local Collision of SC Wall Using High Energy Absorbing Steel

Energy Technology Data Exchange (ETDEWEB)

Yoo, H. K.; Chung, C. H.; Park, J.; Lee, J. W. [Dankook University, Yongin (Korea, Republic of); Kim, S. Y. [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2011-05-15

Local damage evaluations for nuclear power plant(NPP) design are performed against turbine impact, tornado impact, airplane engine impact, etc., where turbine is a internal source of impact, whereas tornado and airplane engine are external sources of impact. The thickness of NPP wall structure is determined at initial design stage not to be penetrated by local impacts. This study investigated the local damage of NPP substructure against internal turbine impact. Simulation of local collisions of SC wall in NPP structure, which consists of two models: one using general steel and the other using high energy absorbing steel, were performed. The performance of SC wall using ductile high energy absorbing steel can be greatly improved on local collisions when compared with that of general steel
Simulation of a Local Collision of SC Wall Using High Energy Absorbing Steel

International Nuclear Information System (INIS)

Yoo, H. K.; Chung, C. H.; Park, J.; Lee, J. W.; Kim, S. Y.

2011-01-01

Local damage evaluations for nuclear power plant(NPP) design are performed against turbine impact, tornado impact, airplane engine impact, etc., where turbine is a internal source of impact, whereas tornado and airplane engine are external sources of impact. The thickness of NPP wall structure is determined at initial design stage not to be penetrated by local impacts. This study investigated the local damage of NPP substructure against internal turbine impact. Simulation of local collisions of SC wall in NPP structure, which consists of two models: one using general steel and the other using high energy absorbing steel, were performed. The performance of SC wall using ductile high energy absorbing steel can be greatly improved on local collisions when compared with that of general steel
Search for Fractionally Charged Nuclei in High-Energy Oxygen-Lead Collisions

CERN Multimedia

2002-01-01

We propose to use stacks of CR-39 plastic track detectors to look for fractionally charged projectile fragments produced in collisions of high-energy oxygen, sulfur, and calcium nuclei with a lead target. The expected charge resolution is @s^z~=~0.06e for fragments with 17e/3~@$<$~Z~@$<$~23e/3. We request that two target + stack assemblies be exposed to 1~x~10|5 oxygen nuclei at maximum available energy.
Three-Body Collision Contributions to Recombination and Collision-Induced Dissociation. II. Kinetics

International Nuclear Information System (INIS)

Kendrick, Brian; Pack, Russell T.; Walker, Robert B.

1998-01-01

Detailed rate constants for the reaction Ne + Ne + H r e quilibrium Ne 2 + H are generated, and the master equations governing collision-induced dissociation (CID) and recombination are accurately solved numerically. The temperature and pressure dependence are explored. At all pressures, three-body (3B) collisions dominate. The sequential two-body energy-transfer (ET) mechanism gives a rate that is more than a factor of two too small at low pressures and orders of magnitude too small at high pressures. Simpler models are explored; to describe the kinetics they must include direct 3B rates connecting the continuum to the bound states and to the quasibound states. The relevance of the present reaction to more general CID/recombination reactions is discussed. For atomic fragments, the 3B mechanism usually dominates. For diatomic fragments,the 3B and ET mechanism are competitive, and for polyatomic fragments the ET mechanism usually dominates
Threshold collision-induced dissociation of diatomic molecules: a case study of the energetics and dynamics of O2- collisions with Ar and Xe.

Science.gov (United States)

Ahu Akin, F; Ree, Jongbaik; Ervin, Kent M; Kyu Shin, Hyung

2005-08-08

The energetics and dynamics of collision-induced dissociation of O2- with Ar and Xe targets are studied experimentally using guided ion-beam tandem mass spectrometry. The cross sections and the collision dynamics are modeled theoretically by classical trajectory calculations. Experimental apparent threshold energies are 2.1 and 1.1 eV in excess of the thermochemical O2- bond dissociation energy for argon and xenon, respectively. Classical trajectory calculations confirm the observed threshold behavior and the dependence of cross sections on the relative kinetic energy. Representative trajectories reveal that the bond dissociation takes place on a short time scale of about 50 fs in strong direct collisions. Collision-induced dissociation is found to be remarkably restricted to the perpendicular approach of ArXe to the molecular axis of O2-, while collinear collisions do not result in dissociation. The higher collisional energy-transfer efficiency of xenon compared with argon is attributed to both mass and polarizability effects.
Threshold collision-induced dissociation of diatomic molecules: A case study of the energetics and dynamics of O2- collisions with Ar and Xe

International Nuclear Information System (INIS)

Ahu Akin, F.; Ree, Jongbaik; Ervin, Kent M.; Hyung, Kyu Shin

2005-01-01

The energetics and dynamics of collision-induced dissociation of O 2 - with Ar and Xe targets are studied experimentally using guided ion-beam tandem mass spectrometry. The cross sections and the collision dynamics are modeled theoretically by classical trajectory calculations. Experimental apparent threshold energies are 2.1 and 1.1 eV in excess of the thermochemical O 2 - bond dissociation energy for argon and xenon, respectively. Classical trajectory calculations confirm the observed threshold behavior and the dependence of cross sections on the relative kinetic energy. Representative trajectories reveal that the bond dissociation takes place on a short time scale of about 50 fs in strong direct collisions. Collision-induced dissociation is found to be remarkably restricted to the perpendicular approach of Ar/Xe to the molecular axis of O 2 - , while collinear collisions do not result in dissociation. The higher collisional energy-transfer efficiency of xenon compared with argon is attributed to both mass and polarizability effects
Achieving high baryon densities in the fragmentation regions in heavy ion collisions at top RHIC energy

International Nuclear Information System (INIS)

Li, Ming; Kapusta, Joseph I.

2017-01-01

Heavy ion collisions at extremely high energy, such as the top energy at RHIC, exhibit the property of transparency where there is a clear separation between the almost net-baryon-free central rapidity region and the net-baryon-rich fragmentation region. We calculate the net-baryon rapidity loss and the nuclear excitation energy using the energy-momentum tensor obtained from the McLerran-Venugopalan model. Nuclear compression during the collision is further estimated using a simple space-time picture. The results show that extremely high baryon densities, about twenty times larger than the normal nuclear density, can be achieved in the fragmentation regions. (paper)
High energy factorization in nucleus-nucleus collisions, I

CERN Document Server

Gelis, François; Venugopalan, Raju

2008-01-01

We derive a high energy factorization theorem for inclusive gluon production in A+A collisions. Our factorized formula resums i) all order leading logarithms (g^2 \\ln(1/x_{1,2}))^n of the incoming partons momentum fractions, and ii) all contributions (g \\rho_{1,2})^n that are enhanced when the color charge densities in the two nuclei are of order of the inverse coupling-- \\rho_{1,2}\\sim g^{-1}. The resummed inclusive gluon spectrum can be expressed as a convolution of gauge invariant distributions W[\\rho_{1,2}] from each of the nuclei with the leading order gluon number operator. These distributions are shown to satisfy the JIMWLK equation describing the evolution of nuclear wavefunctions with rapidity. As a by-product, we demonstrate that the JIMWLK Hamiltonian can be derived entirely in terms of retarded light cone Green's functions without any ambiguities in their pole prescriptions. We comment on the implications of our results for understanding the Glasma produced at early times in A+A collisions at coll...
The mechanism of nuclear energy release in nucleus-nucleus collisions

International Nuclear Information System (INIS)

Strugalski, Z.; Strugalska-Gola, E.

1998-01-01

The mechanism of intranuclear energy release in reactions induced by nucleus-nucleus collisions at energies higher than ∼ 0.5 GeV/nucl. is presented - as prompted experimentally. The intranuclear energy release goes through local damages of the colliding nuclei
Determination of kinetic coefficients for proton-nucleus collisions at high energy

International Nuclear Information System (INIS)

Rizzato, C.M.

1987-01-01

From the effective proton dynamics, the approximations in the context of high energy collisions which lead to the Boltzmann equation, are established. From this equation, general expressions for the kinetic coefficients are deduced. Using a simple model, analytical expressions for kinetic coefficients are obtained. The importance of the effect of Pauli blocking is also shown. (author) [pt
Hard scattering contribution to particle production in high energy heavy-ion collisions

International Nuclear Information System (INIS)

Pareek, Pooja; Mishra, Aditya Nath; Sahoo, Pragati; Sahoo, Raghunath

2014-01-01

Global observables like the multiplicity of produced charged particles and transverse energy, are the key observables used to characterize the properties of the matter created in heavy-ion collisions. In order to study the dependence of the charged particle density on colliding system, center of mass energy and collision centrality, there have been measurements starting few GeV to TeV energies at LHC. There is a need to understand the particle production contribution coming from the QCD hard processes, which scale with number of binary nucleon-nucleon collisions, N coll and soft processes scaling with number of participant nucleons, N part
Analysis of $\\pi^{0},\\eta$ and $\\omega$ mesons in pp collisions with a high energy photon trigger at ALICE

CERN Document Server

Yano, Satoshi

High energy heavy ion collision is a powerful and unique tool to achieve the high density and temperature like the early universe. At normal temperature, partons are confined in nucleons and they can not move freely due to the asymp- totic freedom which is a property of the Quantum Chromo Dynamics (QCD). However, at high density and/or high temperature, they can be deconfined from nucleons. This phase is called the Quark Gluon Plasma (QGP). Hadron production measurements in proton-proton collisions at the Large Hadron Collider (LHC) energies can observe new phenomena which must be a frontier in the particle physics and allow validation of the predictive power of the QCD and can provide further constrains on pQCD theory for LHC energies. It is well known that the yield of high transvers momentum particles is suppressed in nucleus-nucleus collisions relative to that in proton-proton collisions. This effect is attributed to energy loss of parent partons or perhaps of hadrons after freeze-out. Since π 0 , η and...
Baryon number violation in high energy collisions

International Nuclear Information System (INIS)

Farrar, G.R.; Meng, R.

1990-08-01

We study the phenomenology of baryon number violation induced by electroweak instantons. We find that if the naive-instanton amplitudes were valid for arbitrarily high energies, the event rate at the SSC would be a few per hour, with a typical event consisting of 3 'primary' antileptons and 7 'primary' antiquark jets, accompanied by ≅ 85 electroweak gauge bosons, having a sharp threshold in the total sub-energy at about 17 TeV. We describe how to establish their electroweak-instanton-induced origin. The naive instanton approximation is known to overestimate the rate for these processes, so this work focusses attention on the need for more accurate calculations, and for a calculational method which is appropriate when the energy of the initial particles is above the sphaleron energy. (orig.)
Inclusive glueball production in high-energy p+p(p) collisions

CERN Document Server

Peng Hong An; He Zhen Min

2001-01-01

Using the factorizable character of amplitudes for the double diffractive process in the Landshoff-Nachtmann model (1987), we have discussed the inclusive glueball production in high-energy pp collisions via the fusion process of two non-perturbative gluons, and have compared it with the double diffractive alike process. We found that, as the c.m. energy E/sub CMS/ increases from 20 to 20 000 GeV, the cross sections of the latter process are about one to two orders larger than the former. Such an outcome could be explained from the hypothesis of duality between glueballs and pomeron. (7 refs).
Spin conversion induced by spin-orbit interaction in positronium collisions

International Nuclear Information System (INIS)

Saito, H; Nakayama, T; Hyodo, T

2009-01-01

The positronium spin conversion reaction induced by spin-orbit interaction is investigated. We obtain the reaction rates during positronium-Xe and positronium-Kr collisions by using the Zeeman mixing of positronium states. At thermal energies corresponding to room temperature, the reaction rate for spin conversion due to spin-orbit interaction is found to be almost twice that for the positronium pick-off reaction. We also study the energy dependence of the reaction rate. The mean energy of positronium is controlled by changing the gas temperature and using positronium in thermal equilibrium. We found that the reaction rate increases with the collision energy.
Further Study of Λ-Related Quantum Interference of Π-State Diatomic on Collision-Induced Rotational Energy Transfer

International Nuclear Information System (INIS)

Li Yongqing; Song Peng; Chen Yuehui; Wang Weili; Ma Fengcai

2005-01-01

In our previous theoretical studies [Meng-Tao Sun, Yong-Qing Lee, and Feng-Cai Ma, Chem. Phys. Lett. 371 (2003) 342], we have reported the quantum interference on collision-induced rotational energy transfer on CO (A 1 Π, v = 3) with inert gases, which originates from the difference between the two Λ-related collision potential energy surfaces. The interference angle, which measures the degree of coherence, is presented in this paper. Based on the time-dependent first order Born approximation, taking into account the anisotropic Lennard-Jones interaction potentials, the relation of the interference angle with the factors, including experimental temperature, partner, and rotational quantum number, are obtained. The changing tendencies with them are discussed. This theoretical model is important to understanding and performing this kind of experiment.
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.
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.
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.
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.

High energy nucleus-nucleus collisions at CERN: Signatures, physical observables and experimental results

International Nuclear Information System (INIS)

Harris, J.W.

1988-02-01

Experimental results on high energy nucleus-nucleus collisions have become available with the recent experiments at CERN utilizing 200 GeV/n oxygen and sulfur beams. Physics motivations for these experiments are presented: a description of predicted signatures for possible formation of a quark-gluon plasma and physical observables that are expected to provide important information for understanding the dynamics of these collisions. A presentation will be made of some of the first experimental results to emerge from this new field. 28 refs., 9 figs
Quantum chromodynamics at high energy, theory and phenomenology at hadron colliders; Chromodynamique quantique a haute energie, theorie et phenomenologie appliquee aux collisions de hadrons

Energy Technology Data Exchange (ETDEWEB)

Marquet, C

2006-09-15

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

International Nuclear Information System (INIS)

Strugalska-Gola, E.; Strugalski, Z.

1997-01-01

Experimental data on nuclear collisions at high energies, mainly obtained from photographic emulsions, are considered from the point of view of the picture of the nuclear collision processes mechanisms prompted experimentally. In fact, the disintegration products of each nucleus involved in a nuclear collision, in its own rest-frame, are similar to that produced by the impact of a number of nucleons of velocity equal to that of the moving primary nucleus
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
Low-energy particle production and residual nuclei production from high-energy hadron-nucleus collisions

International Nuclear Information System (INIS)

Alsmiller, F.S.; Alsmiller, R.G. Jr.; Hermann, O.W.

1987-01-01

The high-energy hadron-nucleus collision model, EVENTQ, has been modified to include a calculation of the excitation and kinetic energy of the residual compound nucleus. The specific purpose of the modification is to make it possible to use the model in the high-energy radiation transport code, HETC, which, in conjunction with MORSE, is used to transport the low energy particles. It is assumed that the nucleons in the nucleus move in a one-dimensional potential well and have the momentum distribution of a degenerate Fermi gas. The low energy particles produced by the deexcitation of the residual compound nucleus, and the final residual nucleus, are determined from an evaporation model. Comparisons of multiplicities and residual nuclei distributions with experimental data are given. The ''grey'' particles, i.e., charged particles with 0.25 < β < 0.7, are in good agreement with experimental data but the residual nuclei distributions are not. 12 refs., 3 figs
Hard Pomeron-odderon interference effects in the production of π+π- pairs in high energy γγ collisions at the LHC

International Nuclear Information System (INIS)

Pire, B.; Schwennsen, F.; Szymanowski, L.; Wallon, S.

2008-01-01

We estimate the production of two meson pairs in high energy photon-photon collisions produced in ultraperipheral collisions at LHC. We show that the study of charge asymmetries may reveal the existence of the perturbative Odderon and discuss the concrete event rates expected at the LHC. Sizable rates and asymmetries are expected in the case of proton-proton collisions and medium values of γγ energies √(s γγ )≅20 GeV. Proton-proton collisions will benefit from a high rate due to a large effective γγ luminosity and ion-ion collisions with a somewhat lower rate from the possibility to trigger on ultraperipheral collisions and a reduced background from strong interactions.
Interference between vibration-to-translation and vibration-to-vibration energy transfer modes in diatomic molecules at high collision energies

International Nuclear Information System (INIS)

Shin, H.K.

1983-01-01

An explicit time dependent approach for simultaneous VT and VV energy transfer in diatom--diatom collisions is explored using the exponential form of ladder operators in the solution of the Schroedinger equation of motion. The collision of two hydrogen molecules is chosen to illustrate the extent of interference between VT and VV modes among various vibrational states. While vibrational energy transfer processes of nominally VT type can be treated with pure VT mode at low collision energies, the intermode coupling is found to be very important at collision energies of several hω. The occurrence of the coupling appears to be nearly universal in vibrational transitions at such energies. Exceptions to the coupling have been discussed
Heavy-flavor production and medium properties in high-energy nuclear collisions --What next?

NARCIS (Netherlands)

Aarts, G.; Aichelin, J.; Allton, C.; Arnaldi, R.; Bass, S. A.; Bedda, C.; Brambilla, N.; Bratkovskaya, E.; Braun-Munzinger, P.; Bruno, G. E.; Dahms, T.; Das, S. K.; Dembinski, H.; Djordjevic, M.; Ferreiro, E. G.; Frawley, A.; Gossiaux, P. B.; Granier de Cassagnac, R.; Grelli, A.; He, Ming; Horowitz, W. A.; Innocenti, G. M.; Jo, M.; Kaczmarek, O.; Kuijer, P; Laine, M.; Lombardo, M. P.; Mischke, A.; Munhoz, M. G.; Nahrgang, M.; Nguyen, Mai; Oliveira da Silva, A. C.; Petreczky, P.; Rothkopf, A.; Schmelling, M.; Scomparin, E.; Song, Ting; Stachel, J.; Suaide, A. A P; Tolos, L.; Trzeciak, B.; Uras, A.; van Doremalen, L.; Vermunt, L.; Vigolo, S.; Xu, N.; Ye, Z.; Zanoli, H.J.C.; Zhuang, P.

2017-01-01

Open and hidden heavy-flavor physics in high-energy nuclear collisions are entering a new and exciting stage towards reaching a clearer understanding of the new experimental results with the possibility to link them directly to the advancement in lattice Quantum Chromo-Dynamics (QCD). Recent results
Inelastic collisions of medium energy atomic elements. Qualitative model of energy losses during collisions

International Nuclear Information System (INIS)

Pustovit, A.N.

2006-01-01

A new approach to the theoretical description of energy losses of atomic particle of medium energy during their interaction with the substance is proposed. The corner-stone of this approach is the supposition that all of the collision processes have inelastic nature during particle movement through the substance, while the calculation of the atomic particles braking is based on the law of their dispersion and the laws of energy and momentum conservation at the inelastic collisions. It is shown that inelastic atomic collision there are three dispersion zones for the only potential interaction with different laws, which characterize energy losses. The application conditions of this approach are determined [ru
Searching for squeezed particle-antiparticle correlations in high-energy heavy-ion collisions

International Nuclear Information System (INIS)

Padula, Sandra S.; Socolowski, O. Jr.

2010-01-01

Squeezed correlations of particle-antiparticle pairs were predicted to exist if the hadron masses were modified in the hot and dense medium formed in high-energy heavy-ion collisions. Although well-established theoretically, they have not yet been observed experimentally. We suggest here a clear method to search for such a signal by analyzing the squeezed correlation functions in terms of measurable quantities. We illustrate this suggestion for simulated φφ pairs at the Relativistic Heavy Ion Collider (RHIC) energies.
QCD and the space-time evolution of high energy e+e-, p anti p, and heavy ion collisions

International Nuclear Information System (INIS)

Bjorken, J.D.

1982-06-01

We begin with a discussion of e + e - annihilation into hadrons, a process blessed with well-known elements of simplicity. We consider the opposite extreme of highly relativistic nucleus-nucleus collisions. Here a space-time description has its own elements of simplicity, elements which might conceivably be applicable in hadron-hadron collisions. We also address the more immediate issues of how these ideas relate to present-day observations, especially high-energy hadron-hadron collisions. 40 references
ψ' and J/ψ suppression in high-energy nucleon-nucleus and nucleus-nucleus collisions

International Nuclear Information System (INIS)

Wong, Cheuk-Yin.

1995-01-01

The observed features of ψ' to J/ψ suppression in pA and nucleus-nucleus collisions can be explained in terms of a two-component absorption model. For the hard component of the absorption due to the interaction of the produced c bar c systems with baryons at high relative energies, the absorption cross sections are insensitive to the radii of the c bar c systems, as described by the Additive Quark Model. For the soft component due to the low energy c bar c interactions with soft particles produced by other baryon-baryon collisions, the absorption cross sections are greater for ψ' than for J/ψ, because the breakup threshold for ψ' is much smaller than for ψ
Nuclear suppression in p-A collisions from induced radiation

International Nuclear Information System (INIS)

Arleo, F.; Kolevatov, R.; Peigne, S.; Sami, T.

2016-01-01

The current status of coherent energy loss is reviewed, both in theory and in its phenomenological applications to p-A collisions. The induced energy loss is not bounded in general, but only in the specific situation where the energetic parton is suddenly accelerated (as in deep inelastic scattering) in the nuclear medium. In the situation where the parton is asymptotic, i.e. 'prepared' at t = -∞ and 'tagged' at t = +∞ after crossing a nuclear medium of thickness L (a situation relevant to forward hadron production in p-A collisions), ΔE appears to be proportional to E. Both situations are detailed in the article
TCP (truncated compound Poisson) process for multiplicity distributions in high energy collisions

International Nuclear Information System (INIS)

Srivastave, P.P.

1990-01-01

On using the Poisson distribution truncated at zero for intermediate cluster decay in a compound Poisson process, the authors obtain TCP distribution which describes quite well the multiplicity distributions in high energy collisions. A detailed comparison is made between TCP and NB for UA5 data. The reduced moments up to the fifth agree very well with the observed ones. The TCP curves are narrower than NB at high multiplicity tail, look narrower at very high energy and develop shoulders and oscillations which become increasingly pronounced as the energy grows. At lower energies the distributions, of the data for fixed intervals of rapidity for UA5 data and for the data (at low energy) for e + e - annihilation and pion-proton, proton-proton and muon-proton scattering. A discussion of compound Poisson distribution, expression of reduced moments and Poisson transforms are also given. The TCP curves and curves of the reduced moments for different values of the parameters are also presented
Finite escape fraction for ultrahigh energy collisions around Kerr

Indian Academy of Sciences (India)

We investigate the issue of observability of high-energy collisions around Kerr naked singularity and show that results are in contrast with the Kerr black hole case. We had shown that it would be possible to have ultrahigh energy collisions between the particles close to the location = M around the Kerr naked singularity if ...
Finite escape fraction for ultrahigh energy collisions around Kerr ...

Indian Academy of Sciences (India)

Abstract. We investigate the issue of observability of high-energy collisions around Kerr naked singularity and show that results are in contrast with the Kerr black hole case. We had shown that it would be possible to have ultrahigh energy collisions between the particles close to the location r = M around the Kerr naked ...
Production of light fragments in hA collisions at high energies

International Nuclear Information System (INIS)

Braun, M.A.; Vechernin, V.V.

1988-12-01

Production of fast relativistic light fragments in hA collisions at high energies is considered. Direct coalescence of produced nucleons into fragments is shown to be the main mechanism for fragment production. The influence of the nuclear field is small and is not described by the well-known Butler-Pearson formulas. The coalescence coefficient strongly depends on the angle and on the behaviour of the fragment wave function at small internucleon distances. (author). 14 refs, 7 figs
Free-parameterless model of high energy particle collisions with atomic nuclei

International Nuclear Information System (INIS)

Strugalski, Z.

1982-01-01

In result of studies, it has been discovered that: a) Intensive emission of fast nucleons of kinetic energy from 20 to 400 MeV proceeds independently of the pion production process; b) The particle production in hadron-nucleon collisions is mediated by intermediate objects produced first in a 2 → 2 type endoergic reaction and decaying after lifetime tausub(g) > or approximately 10 - 22 s into commonly known resonances and particles; c) Inside of massive enough atomic nuclei quasi-onedimensional cascades of the intermediate objects can develop; d) A definite simple connection exists between the characteristics of the secondaries appearing in hadron-nucleus collision events and corresponding hadron-nucleon collision events, the target-nucleus size and the nucleon density distribution in it. The yield of the hadron-nucleus collisions is described in a convincing manner in terms of the hadron-nucleon collision data by means of simple formulas
Single electron capture differential cross section in H+ + He collisions at intermediate and high collision energies

International Nuclear Information System (INIS)

Abufager, P N; Fainstein, P D; MartInez, A E; Rivarola, R D

2005-01-01

The generalized continuum distorted wave-eikonal initial state (CDW-EIS II) approximation is employed to study differential cross sections (DCS) for single electron capture in H + + He collisions at intermediate and high energies. Present results are compared with theoretical calculations obtained using the previous CDW-EIS formulation in order to show the importance of the description of the bound and continuum target states in the entrance and exit channels, respectively. Both DCS are also shown together with other theoretical results and with experimental data
Angular distributions of nucleons emitted in high energy hadron-nucleus collisions

International Nuclear Information System (INIS)

Strugalski, Z.

1983-01-01

Angular distributions of ''fast'' protons, of kinetic energy from about 20 to about 400 MeV, emitted in pion-xenon nucleus collisions at 3.5 GeV/c momentum were studied in two groups of events - when particles are produced and when particle production does not occur. The distributions are practically the same in both the groups of events and in subgroups of events with various multiplicities of emitted protons. Comparison of angular distributions of protons emitted in pion-xenon nucleus collisions at 3.5 GeV/c momentum with corresponding angular distributions of protons emitted in proton-emulsion collisions at 300-400 GeV/c momentum is performed. Results obtained allow to conclude that average value of the nucleon emission angle and the nucleon angular distributions do not depend practically on the nuclear matter layer thickness the incident hadron collided with. Fast nucleons emitted from the target nucleus seem did not interact inside the parent nucleus. Fast nucleon angular distributions do not depend on the energy of incident hadron, they are the same for pion-nucleus and for proton-nucleus collisions as well

Early time evolution of high-energy heavy-ion collisions

Energy Technology Data Exchange (ETDEWEB)

Fries, Rainer J [Cyclotron Institute and Department of Physics, Texas A and M University, College Station, TX 77843 (United States); RIKEN/BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973 (United States)

2007-08-15

We solve the Yang-Mills equations in the framework of the McLerran-Venugopalan model for small times {tau} after a collision of two nuclei. An analytic expansion around {tau} = 0 leads to explicit results for the field strength and the energy-momentum tensor of the gluon field at early times. We then discuss constraints for the energy density, pressure and flow of the plasma phase that emerges after thermalization of the gluon field.
High energy nuclear collisions in the few GeV/nucleon region: projectile and target fragmentation

International Nuclear Information System (INIS)

Schroeder, L.S.

1980-06-01

A general review of nucleon-nucleus and nucleus-nucleus collisions for incident energies <10 GeV/nucleon is presented. The division of these interactions into peripheral and central collisions is briefly discussed. Subjects treated include the following: target and projectile fragmentation systematics, production of exotic nuclear fragments, studies of multiparticle final states, total cross section measurements, results from an experiment that indicate the production of projectile fragments with an anomalously short reaction mean free path, high-energy particle production at backward angles beyond simple N-N kinematic limits, and recent results on backward particle emission in studies with the Berkeley streamer chamber. Both the particle and nuclear physics aspects that are present are considered. A brief discussion of future trends in this energy range ends the presentation. 65 references, 37 figures
Collision-induced dissociation with Fourier transform mass spectrometry

International Nuclear Information System (INIS)

Cody, R.B.; Burnier, R.C.; Freiser, B.S.

1982-01-01

Collision-induced dissociations (CID) is demonstrated on a number of primary and secondary ions using a Nicolet prototype Fourier transform mass spectrometer (FT-MS). Like the triple quadrupole technique, CID using FT-MS is a relatively low energy and efficient process. The ability to study a wide range of ion-molecule reaction products is exemplified by results on proton-bound dimers and transition metal containing ionic species. Variation of collision energy by varying the RF irradiation level can provide information about product distributions as a function of energy as well as yield ion structural information. Like the triple quadrupole technique, no slits are employed and virtually all of the fragment ions formed by the CID process may be detected. Unlike all previous mass spectrometric techniques for studying CID, a tandem instrument is not required, and different experiments are performed by making software modifications rather than hardware modifications
The Theory of High Energy Collision Processes - Final Report DOE/ER/40158-1

Energy Technology Data Exchange (ETDEWEB)

Wu, Tai, T.

2011-09-15

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

Energy Technology Data Exchange (ETDEWEB)

Fries, Rainer J. [Cyclotron Institute, Texas A and M University, College Station, TX 77843 (United States); RIKEN/BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973 (United States)], E-mail: rjfries@comp.tamu.edu

2008-06-01

I discuss some recent progress in our understanding of high energy nuclear collisions. I will focus on two topics which I was lucky to co-pioneer in the recent past. One is recombination of quarks and its interpretation as a signal for deconfinement, the second is electromagnetic radiation from jets passing through a quark gluon plasma. This talk was given during the award ceremony for the 2007 IUPAP Young Scientist Award.
The mechanisms of the hadron-nucleus collision processes and of the hadron-nucleus collision induced nuclear reactions - in the light of experimental data

International Nuclear Information System (INIS)

Strugalski, Z.; Strugalska-Gola, E.

1997-01-01

The mechanisms of the hadron-nucleus collision processes and of the hadron-nucleus collision induced nuclear reactions are described - as experimentally based. The target nuclei are damaged definitely and locally in the collisions and the configurations of the nucleons in them became instable. The configuration must transit into stable stages of the nuclear transition reaction products. The difference between the initial internal energy of the unstable residual nucleus and the total final energy of the stable products of the nuclear transition reaction may be released in some cases
Production and decay of exotic fermions in high energy collisions

International Nuclear Information System (INIS)

Queiroz Filho, Pedro Pacheco de

1995-05-01

In this work, we investigate the production and decay of exotic fermions predicted by some extensions of the standard model. We select for our study the more popular models: vector singlet, vector doublet and Fermion Mirror-Fermion. We want to establish the differences between these models and also in relation to the Standard Model. We make investigations by Monte Carlo simulations, to study the phenomenology of the particles expected in these models, particularly the exotic fermions. These studies were done for electron-proton collisions at DESY HERA energies. We considered the investigation of exotic quark production, electron-positron collisions in LEP II and NLC energies in order to study the production of exotic leptons, and virtual exotic lepton contribution in the specific process e + e - → ιν-bar ι W + . (author)
2006-2007 Academic training programme: QCD and high energy nuclear collision

CERN Multimedia

HR Department

2007-01-01

LECTURE SERIES 7, 8, 9 May QCD and high energy nuclear collisions D. Kharzeev, Brookhaven National Laboratory, USA 11:00 to 12:00 - Main Auditorium, Bldg. 500 on 7 and 8 May, Council Chamber on 9 May Six years ago, Relativistic Heavy Ion Collider at Brookhaven started colliding heavy nuclei at record center-of-mass energies of up to 200 GeV/nucleon. Very soon, the Large Hadron Collider at CERN will push the energy of the ions to an astounding 5 TeV/nucleon. What can be learnt from the experiments at these machines? What do we know about the physics of super--dense matter already? I will argue that heavy ion accelerators bring us to the new frontiers of physical knowledge by creating strong color fields and very high densities of partons, at which qualitatively new phenomena emerge. I will also discuss the cross-disciplinary implications for cosmology, astrophysics, and connections to condensed matter physics.
2006-2007 Academic training programme: QCD and high energy nuclear collisions

CERN Multimedia

HR Department

2007-01-01

LECTURE SERIES 7, 8, 9 May 2007 11:00 to 12:00 - Main Auditorium, Bldg. 500 on 7 and 8 May, Council Chamber on 9 May QCD and high energy nuclear collisions D. Kharzeev, Brookhaven National Laboratory, USA Six years ago, the Relativistic Heavy Ion Collider at Brookhaven started colliding heavy nuclei at record center-of-mass energies of up to 200 GeV/nucleon. Very soon, the Large Hadron Collider at CERN will push the energy of the ions to an astounding 5 TeV/nucleon. What can be learnt from the experiments at these machines? What do we know about the physics of super--dense matter already? I will argue that heavy ion accelerators bring us to the new frontiers of physical knowledge by creating strong color fields and very high densities of partons, at which qualitatively new phenomena emerge. I will also discuss the cross-disciplinary implications for cosmology, astrophysics, and connections to condensed matter physics.
Forward-backward multiplicity fluctuation and longitudinal harmonics in high-energy nuclear collisions

Science.gov (United States)

Jia, Jiangyong; Radhakrishnan, Sooraj; Zhou, Mingliang; Huo, Peng

2016-12-01

Forward-backward (FB) multiplicity fluctuation in high-energy nuclear collisions can be quantified by two-particle pseudo-rapidity correlation function and its expansion into Legendre polynomials. The corresponding coefficients represent different fluctuation modes in longitudinal direction. The leading term corresponds to the asymmetry of numbers of the participants from the two colliding nuclei. This method is tested in events generated from AMPT and HIJING model. The an signal are found to be strongly dampened in AMPT than in HIJIGN, due to weaker short-range correlaitons and final-state effects in AMPT. Two-particle correlation also reveals an intresting shallow minimum around Δη ≈ 0 in AMPT events, which is absent in HIJING results. The method opens a new avenue to elucidate the particle production mechanism and early time dynamics in heavy-ion collisions.
Discussion of electron capture theories for ion-atom collisions at high energies

Energy Technology Data Exchange (ETDEWEB)

Miraglia, J E [Instituto de Astronomia y Fisica del Espacio, Buenos Aires (Argentina); Piacentini, R D [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires (Argentina); Rivarola, R D [Rosario Univ. Nacional (Argentina). Dept. de Fisica; Salin, A [Bordeaux-1 Univ., 33 - Talence (France)

1981-03-14

Different theories of charge exchange processes in ion-atom collisions at high energies for the H/sup +/-H system are considered. Large discrepancies are found in the differential cross sections obtained from the various models. The validity of Dettmann's peaking approximation is analysed by comparison with exact values for the first- and second-order Oppenheimer-Brinkman-Kramers (OBK 1 and OBK 2) theories. It is also shown that for energies up to a few MeV the OBK 2 differential cross sections are higher than the corresponding OBK 1 ones. Total cross sections in the OBK 2 approximation are given.
Theory of e+e/sup /minus// collisions at very high energy

International Nuclear Information System (INIS)

Peskin, M.E.

1988-04-01

In these lectures, the array of new phenomena are reviewed which might be discovered in electron-positron reactions conducted at energies well above the Z/degree/. Before beginning a discussion of what new phenomena we might find, or how we might uncover them, the question is addressed of why such a program of research is important. The question of what we should be looking for, and what discoveries will be the most illuminating, as we search for the next layer of fundamental physics is argued. With this background, we can then discuss in some considerable detail the contributions that the study of electron-positron collisions at high energy can make in this search
Multi-property isotropic intermolecular potentials and predicted spectral lineshapes of collision-induced absorption (CIA), collision-induced light scattering (CILS) and collision-induced hyper-Rayleigh scattering (CIHR) for H2sbnd Ne, -Kr and -Xe

Science.gov (United States)

El-Kader, M. S. A.; Godet, J.-L.; Gustafsson, M.; Maroulis, G.

2018-04-01

Quantum mechanical lineshapes of collision-induced absorption (CIA), collision-induced light scattering (CILS) and collision-induced hyper-Rayleigh scattering (CIHR) at room temperature (295 K) are computed for gaseous mixtures of molecular hydrogen with neon, krypton and xenon. The induced spectra are detected using theoretical values for induced dipole moment, pair-polarizability trace and anisotropy, hyper-polarizability and updated intermolecular potentials. Good agreement is observed for all spectra when the literature and the present potentials which are constructed from the transport and thermo-physical properties are used.
Universality, maximum radiation, and absorption in high-energy collisions of black holes with spin.

Science.gov (United States)

Sperhake, Ulrich; Berti, Emanuele; Cardoso, Vitor; Pretorius, Frans

2013-07-26

We explore the impact of black hole spins on the dynamics of high-energy black hole collisions. We report results from numerical simulations with γ factors up to 2.49 and dimensionless spin parameter χ=+0.85, +0.6, 0, -0.6, -0.85. We find that the scattering threshold becomes independent of spin at large center-of-mass energies, confirming previous conjectures that structure does not matter in ultrarelativistic collisions. It has further been argued that in this limit all of the kinetic energy of the system may be radiated by fine tuning the impact parameter to threshold. On the contrary, we find that only about 60% of the kinetic energy is radiated for γ=2.49. By monitoring apparent horizons before and after scattering events we show that the "missing energy" is absorbed by the individual black holes in the encounter, and moreover the individual black-hole spins change significantly. We support this conclusion with perturbative calculations. An extrapolation of our results to the limit γ→∞ suggests that about half of the center-of-mass energy of the system can be emitted in gravitational radiation, while the rest must be converted into rest-mass and spin energy.
Energy-Aware RFID Anti-Collision Protocol.

Science.gov (United States)

Arjona, Laura; Simon, Hugo Landaluce; Ruiz, Asier Perallos

2018-06-11

The growing interest in mobile devices is transforming wireless identification technologies. Mobile and battery-powered Radio Frequency Identification (RFID) readers, such as hand readers and smart phones, are are becoming increasingly attractive. These RFID readers require energy-efficient anti-collision protocols to minimize the tag collisions and to expand the reader's battery life. Furthermore, there is an increasing interest in RFID sensor networks with a growing number of RFID sensor tags. Thus, RFID application developers must be mindful of tag anti-collision protocols. Energy-efficient protocols involve a low reader energy consumption per tag. This work presents a thorough study of the reader energy consumption per tag and analyzes the main factor that affects this metric: the frame size update strategy. Using the conclusion of this analysis, the anti-collision protocol Energy-Aware Slotted Aloha (EASA) is presented to decrease the energy consumption per tag. The frame size update strategy of EASA is configured to minimize the energy consumption per tag. As a result, EASA presents an energy-aware frame. The performance of the proposed protocol is evaluated and compared with several state of the art Aloha-based anti-collision protocols based on the current RFID standard. Simulation results show that EASA, with an average of 15 mJ consumed per tag identified, achieves a 6% average improvement in the energy consumption per tag in relation to the strategies of the comparison.
QCD in high-energy proton-proton and proton-antiproton collisions

International Nuclear Information System (INIS)

Baier, R.

1985-01-01

The experimental and theoretical investigation of nucleon-nucleon collisions at high energies allows to explore the structure of the nucleon by large momentum transfer (deep-inelastic) processes. In these lectures the structure of the nucleon from momentum scales Q > 1 GeV/c ( -16 cm) is discussed. In the first lecture the basic concepts of the parton model and of perturbative quantum chromodynamics (QCD) are introduced, and applied to deep inelastic lepton-nucleon scattering. The following lectures cover large transverse momentum, psub(T), hadronic processes, massive dilepton production and production of prompt real photons at large psub(T). The present status of the theoretical understanding of these processes is summarized. (Auth.)
On the angular distribution of spectator nucleons in high-energy collisions with deuterium nuclei

International Nuclear Information System (INIS)

Bartke, J.

1975-01-01

Angular distributions of spectator nucleons in collisions of high-energy particles with deuterium nuclei are discussed in the framework of the impulse model. Comparison with experimental data shows that predictions following from this simple theoretical model are verified by experiment. Some general remarks on the study of angular distributions of spectator nucleons are given. (author)
High energy nuclear collisions

Indian Academy of Sciences (India)

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

International Nuclear Information System (INIS)

Yang Xihua; Sheng Jiteng; Xiao Min

2011-01-01

We conduct theoretical studies on electromagnetically induced absorption via incoherent collisions in an inhomogeneously broadened ladder-type three-level system with the density-matrix approach. The effects of the collision-induced coherence decay rates as well as the probe laser field intensity on the probe field absorption are examined. It is shown that with the increase of the collisional decay rates in a moderate range, a narrow dip due to electromagnetically induced transparency superimposed on the Doppler-broadened absorption background can be turned into a narrow peak under the conditions that the probe field intensity is not very weak as compared to the pump field, which results from the enhancement of constructive interference and suppression of destructive interference between one-photon and multiphoton transition pathways. The physical origin of the collision-assisted electromagnetically induced absorption is analyzed with a power-series solution of the density-matrix equations.
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

Generalized z-scaling in proton-proton collisions at high energies

International Nuclear Information System (INIS)

Zborovsky, I.; Tokarev, M.

2006-01-01

New generalization of z-scaling in inclusive particle production is proposed. The scaling variable z is a fractal measure which depends on kinematical characteristics of the underlying subprocess expressed in terms of the momentum fractions x 1 and x 2 of the incoming protons. In the generalized approach, the x 1 and x 2 are functions of the momentum fractions y a and y b of the scattered and recoil constituents carried out by the inclusive particle and recoil object, respectively. The scaling function ψ(z) for charged and identified hadrons produced in proton-proton collisions is constructed. The fractal dimensions and heat capacity of the produced medium entering definition of the z are established to obtain energy, angular and multiplicity independence of the ψ(z). The scheme allows unique description of data on inclusive cross sections of charged particles, pions, kaons, antiprotons, and lambdas at high energies. The obtained results are of interest to use z-scaling as a tool for searching for new physics phenomena of particle production in high transverse momentum and high multiplicity region at the proton-proton colliders RHIC and LHC
Collisions of low-energy multicharged ions

International Nuclear Information System (INIS)

Phaneuf, R.A.; Crandall, D.H.

1981-01-01

Experimental measurements of cross sections for collisions of multiply charged ions with atoms at the lowest attainable collision energies are reported. Emphasis is on electron capture from hydrogen atoms by multiply charged ions at energies below 1 keV/amu. The principal effort is the development of a merged-ion-atom-beams apparatus for studies down to 1 eV/amu relative energy
Laser-induced charge exchange in ion-atom collisions

International Nuclear Information System (INIS)

Riera, A.

1986-01-01

The theory of laser-induced charge transfer (LICT) in ion-atom collisions is presented for the range of impact energies in which a quasimolecular description is appropriate. For each relative orientation of the AC field, LICT cross sections can be obtained with trivial modifications of standard programs. Simpler, perturbative expressions for the orientation-averaged cross sections are accurate for I v -1 6 W s cm -3 , and the analytical Landau-Zener perturbative expression often provides good estimates for these cross sections. The practical advantages of the dressed state formalism as an alternative approach are critically examined, and the general characteristics of LICT cross sections in multicharged ion-atom collisions are shown with the help of an example. (Auth.)
Collision induced fragmentation dynamics of small metallic clusters; Dynamique de fragmentation induite par collision de petits agregats metalliques

Energy Technology Data Exchange (ETDEWEB)

Picard, Y

1999-04-15

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

International Nuclear Information System (INIS)

Pleich, R.

1983-10-01

Modern laser technology permits the measurement of collision induced light-scattering spectra from molecular gases at low densities. Measurements of this type provide a test for the separation dependent pair polarizabilities and pair potentials. For this work the octahedral molecule sulphurhexafluoride (SF 6 , point group symmetry 0sub(h)) has been chosen for which the permanent polarizability anisotropy vanishes. For the experiment an argon ion laser in combination with a double grating monochromator and standard photon counting techniques were used. Both the polarized and depolarized scattering cross sections were obtained. The point dipole-induced-dipole (DID) effect is shown to account for the most of the total scattered intensity. At low frequency shifts the line shape of the SF 6 spectrum is dominated by bound dimers, whereas the intermediate frequency range up to 50 cm -1 is well described by a DID free trajectory binary collision model. The high frequency wings are discussed in terms of the collision induced rotational Raman (CIRR) effect and estimates for the dipole-octopole polarizability E are obtained both from the spectral distribution and from the depolarization ratio. It is demonstrated that the hierarchy of effects constituting the CIRR-model converges slowly for large frequency shifts. (Author)
Mass distribution and multiple fragmentation events in high energy cluster-cluster collisions: evidence for a predicted phase transition

International Nuclear Information System (INIS)

Farizon, B.; Farizon, M.; Gaillard, M.J.; Genre, R.; Louc, S.; Martin, J.; Senn, G.; Scheier, P.; Maerk, T.D.

1996-09-01

Fragment size distributions including multiple fragmentation events have been measured for high energy H 25 + cluster ions (60 keV/amu) colliding with a neutral C 60 target. In contrast to earlier collision experiments with a helium target the present studies do not show a U-shaped fragment mass distribution, but a single power-law falloff with increasing fragment mass. This behaviour is similar to what is known for the intermediate regime in nuclear collision physics and thus confirms a recently predicted scaling from nuclear to molecular collisions
Event-by-Event Simulations of Early Gluon Fields in High Energy Nuclear Collisions

Science.gov (United States)

Nickel, Matthew; Rose, Steven; Fries, Rainer

2017-09-01

Collisions of heavy ions are carried out at ultra relativistic speeds at the Relativistic Heavy Ion Collider and the Large Hadron Collider to create Quark Gluon Plasma. The earliest stages of such collisions are dominated by the dynamics of classical gluon fields. The McLerran-Venugopalan (MV) model of color glass condensate provides a model for this process. Previous research has provided an analytic solution for event averaged observables in the MV model. Using the High Performance Research Computing Center (HPRC) at Texas A&M, we have developed a C++ code to explicitly calculate the initial gluon fields and energy momentum tensor event by event using the analytic recursive solution. The code has been tested against previously known analytic results up to fourth order. We have also have been able to test the convergence of the recursive solution at high orders in time and studied the time evolution of color glass condensate.
Quark-gluon plasmas and collective features of nucleus-nucleus collisions at high energy

International Nuclear Information System (INIS)

Blaizot, J.P.

1987-05-01

This paper reviews some aspects of the dynamics of the quark-gluon plasmas which may be produced in ultra-relativistic heavy ion collisions. A space-time description of the central rapidity region is presented. It is shown that the hydrodynamical flow induces correlations between particle transverse momenta and multiplicities. One discusses to which extent these correlations could signal the occurrence of a phase transition in heavy ion collisions
Inclusive spectra of mesons with large transverse momenta in proton-nuclear collisions at high energies

International Nuclear Information System (INIS)

Lykasov, G.I.; Sherkhonov, B.Kh.

1982-01-01

Basing on the proposed earlier quark model of hadron-nucleus processes with large transverse momenta psub(perpendicular) the spectra of π +- , K +- meson production with large psub(perpendicular) in proton-nucleus collisions at high energies are calculated. The performed comparison of their dependence of the nucleus-target atomic number A with experimental data shows a good agreement. Theoretical and experimental ratios of inclusive spectra of K +- and π +- mesons in the are compared. Results of calculations show a rather good description of experimental data on large psub(perpendicular) meson production at high energies
Removal of nonorthogonality in the Born theory used for study of electron capture in high energy ion-atom collisions

International Nuclear Information System (INIS)

Kimura, M.

1989-01-01

We show the complete removal of the nonorthogonality of wave functions between initial and final states in the Born theory. Hence, this treatment offers more realistic electron capture cross sections in high energy ion-atom collisions. Representative results for resonant electron capture in H + + H collision are discussed in conjunction with other perturbative results. 10 refs., 1 fig
Effective-energy budget in multiparticle production in nuclear collisions

Energy Technology Data Exchange (ETDEWEB)

Mishra, Aditya Nath; Sahoo, Raghunath [Indian Institute of Technology Indore, Discipline of Physics, School of Basic Sciences, Indore (India); Sarkisyan, Edward K.G. [CERN, Department of Physics, Geneva 23 (Switzerland); The University of Texas at Arlington, Department of Physics, Arlington, TX (United States); Sakharov, Alexander S. [CERN, Department of Physics, Geneva 23 (Switzerland); Kyungpook National University, Department of Physics, Daegu (Korea, Republic of)

2014-11-15

The dependencies of charged particle pseudorapidity density and transverse energy pseudorapidity density at midrapidity on the collision energy and on the number of nucleon participants, or centrality, measured in nucleus-nucleus collisions are studied in the energy range spanning a few GeV to a few TeV per nucleon. The approach in which the multiparticle production is driven by the dissipating effective energy of participants is introduced. This approach is based on the earlier proposed consideration, combining the constituent quark picture together with Landau relativistic hydrodynamics shown to interrelate the measurements from different types of collisions. Within this picture, the dependence on the number of participants in heavy-ion collisions are found to be well described in terms of the effective energy defined as a centrality-dependent fraction of the collision energy. For both variables under study, the effective-energy approach reveals a similarity in the energy dependence obtained for the most central collisions and centrality data in the entire available energy range. Predictions are made for the investigated dependencies for the forthcoming higher-energy measurements in heavy-ion collisions at the LHC. (orig.)
Effective-energy budget in multiparticle production in nuclear collisions

International Nuclear Information System (INIS)

Mishra, Aditya Nath; Sahoo, Raghunath; Sarkisyan, Edward K.G.; Sakharov, Alexander S.

2014-01-01

The dependencies of charged particle pseudorapidity density and transverse energy pseudorapidity density at midrapidity on the collision energy and on the number of nucleon participants, or centrality, measured in nucleus-nucleus collisions are studied in the energy range spanning a few GeV to a few TeV per nucleon. The approach in which the multiparticle production is driven by the dissipating effective energy of participants is introduced. This approach is based on the earlier proposed consideration, combining the constituent quark picture together with Landau relativistic hydrodynamics shown to interrelate the measurements from different types of collisions. Within this picture, the dependence on the number of participants in heavy-ion collisions are found to be well described in terms of the effective energy defined as a centrality-dependent fraction of the collision energy. For both variables under study, the effective-energy approach reveals a similarity in the energy dependence obtained for the most central collisions and centrality data in the entire available energy range. Predictions are made for the investigated dependencies for the forthcoming higher-energy measurements in heavy-ion collisions at the LHC. (orig.)
Correlations between high momentum particles in proton-proton collisions at high energies

International Nuclear Information System (INIS)

Bobbink, G.J.

1981-01-01

This thesis describes an experiment performed at the CERN Intersecting Storage Rings. The experiment studies the reaction p+p→h 1 +h 2 +X at two centre-of-mass energies, √s=44.7 GeV and √s=62.3 GeV. Two of the outgoing particles (h 1 and h 2 ) are detected in opposite c.m.s. hemispheres at small polar angles with respect to the direction of two incident protons. The remaining particles produced (X) are not detected. The hadrons hsub(i) are identified mesons (π + , π - , K + , K - ) or baryons (p, Λ) with relatively large longitudinal psub(L) and small transverse momentum psub(T). The aim of the experiment is twofold. The first aim is to study whether the momentum distributions of the fast particles hsub(i) are correlated and thereby to constrain the possible interaction mechanisms responsible for the production of high psub(L), low psub(T) particles. The second aim is to establish to what extent the production of pions and kaons in inclusive proton-proton collisions (e.g. p+p→π+X, X=all other particles) resembles the production of pions and kaons in diffractive proton-proton collisions (e.g. p+p→p+π+X, in which the final-state proton has a momentum close to its maximum possible value). (Auth.)
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
Ridge formation induced by jets in pp collisions at 7 TeV

International Nuclear Information System (INIS)

Hwa, Rudolph C.; Yang, C. B.

2011-01-01

An interpretation of the ridge phenomenon found in pp collisions at 7 TeV is given in terms of enhancement of soft partons due to energy loss of semihard jets. A description of ridge formation in nuclear collisions can directly be extended to pp collisions since hydrodynamics is not used and azimuthal anisotropy is generated by semihard scattering. The observed ridge structure is then understood as a manifestation of soft-soft transverse correlation induced by semihard partons without long-range longitudinal correlation. Both the p T and multiplicity dependencies are well reproduced. Some predictions are made about other observables.
Angular pattern of minijet transverse energy flow in hadron and nuclear collisions

International Nuclear Information System (INIS)

Leonidov, A.V.; Ostrovsky, D.M.

2002-01-01

The azimuthal asymmetry of a minijet system produced at the early stage of nucleon-nucleon and nuclear collisions in a central rapidity window is studied. We show that, in pp collisions, the minijet-transverse-energy production in a central rapidity window is essentially unbalanced in azimuth because of asymmetric contributions in which only one minijet hits the acceptance window. We further study the angular pattern of the transverse-energy flow generated by semihard degrees of freedom at the early stage of high-energy nuclear collisions and its dependence on the number of semihard collisions in the models either including or neglecting soft contributions to the inelastic cross section at RHIC and LHC energies, as well as on the choice of infrared cutoff
Angular pattern of minijet transverse energy flow in hadron and nuclear collisions

International Nuclear Information System (INIS)

Leonidov, A.V.; Ostrovsky, D.M.

2000-01-01

The azimuthal asymmetry of a minijet system produced at the early stage of nucleon-nucleon and nuclear collisions in a central rapidity window is studied. We show that in pp collisions the minijet transverse energy production in a central rapidity window is essentially unbalanced in the azimuth due to asymmetric contributions in which only one minijet hits the acceptance window. We further study the angular pattern of the transverse energy flow generated by the semihard degrees of freedom at the early stage of high energy nuclear collisions and its dependence on the number of semihard collisions in the models both including and neglecting soft contributions to the inelastic cross section at RHIC and LHC energies as well as on the choice of the infrared cutoff. (orig.)
Baseline measures for net-proton distributions in high energy heavy-ion collisions

International Nuclear Information System (INIS)

Netrakanti, P.K.; Mishra, D.K.; Mohanty, A.K.; Mohanty, B.

2014-01-01

The STAR experiment at the Relativistic Heavy-Ion Collider facility has reported results for the cumulants and their ratios from the net-proton distributions upto the fourth order cumulants at various collision energies. These measurements were carried to look for the signatures of the possible critical point (CP) in the phase diagram for a system undertaking strong interactions. The results show an intriguing dependence of the cumulant ratios C 3 /C 2 and C 4 /C 2 as a function of beam energy. The beam energy dependence appears to be non-monotonic in nature. However the experiment also reports that the energy dependence is observed to be consistent with expectation from an approach based on the independent production of proton and anti-protons in the collisions. In this paper we emphasize the need to have a proper baseline for appropriate interpretation of the cumulant measurements and argue that the comparison to independent production approach needs to be done with extreme caution
High density matter in AGS, SPS and RHIC collisions. Proceedings. Volume 9

International Nuclear Information System (INIS)

1998-01-01

This 1-day workshop focused on phenomenological models regarding the specific question of the maximum energy density achievable in collisions at AGS, SPS and RHIC. The idea was to have 30-minute (or less) presentations of each model--but not the model as a whole, rather then that strongly narrowed to the above physics question. The key topics addressed were: (1) to estimate the energy density in heavy-ion collisions within a model, and to discuss its physical implications; (2) to suggest experimental observables that may confirm the correctness of a model approach--with respect to the energy density estimate; (3) to compare with existing data from AGS and SPS heavy-ion collisions, and to give predictions for the future RHIC experiments. G. Ogilvie started up the workshop with a critical summary of experimental manifestations of high-density matter at the AGS, and gave a personal outlook on RHIC physics. R. Mattiello talked about his newly developed hadron cascade model for applications to AGS and SPS collisions. Next, D. Kharzeev gave a nice introduction of the Glauber approach to high-energy collisions and illustrated the predictive power of this approach in nucleus-nucleus collisions at the SPS. It followed S. Vance with a presentation of the baryon-junction model to explain the observed baryon stopping phenomenon in collisions of heavy nuclei. S. Bass continued with a broad perspective of the UrQMD model, and provided insight into the details of the microscopic dynamical features of nuclear collisions at high energy. J. Sandweiss and J. Kapusta addressed the interesting aspect of photon production in peripherical nuclear collisions due to intense electromagnetic bremstrahlung by the highly charged, fast moving ions. Finally, H. Sorge closed up the one-day workshop with a presentation of his recent work with the RQMD model. This report consists of a summary and vugraphs of the presentations
High density matter in AGS, SPS and RHIC collisions: Proceedings. Volume 9

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-12-01

This 1-day workshop focused on phenomenological models regarding the specific question of the maximum energy density achievable in collisions at AGS, SPS and RHIC. The idea was to have 30-minute (or less) presentations of each model--but not the model as a whole, rather then that strongly narrowed to the above physics question. The key topics addressed were: (1) to estimate the energy density in heavy-ion collisions within a model, and to discuss its physical implications; (2) to suggest experimental observables that may confirm the correctness of a model approach--with respect to the energy density estimate; (3) to compare with existing data from AGS and SPS heavy-ion collisions, and to give predictions for the future RHIC experiments. G. Ogilvie started up the workshop with a critical summary of experimental manifestations of high-density matter at the AGS, and gave a personal outlook on RHIC physics. R. Mattiello talked about his newly developed hadron cascade model for applications to AGS and SPS collisions. Next, D. Kharzeev gave a nice introduction of the Glauber approach to high-energy collisions and illustrated the predictive power of this approach in nucleus-nucleus collisions at the SPS. It followed S. Vance with a presentation of the baryon-junction model to explain the observed baryon stopping phenomenon in collisions of heavy nuclei. S. Bass continued with a broad perspective of the UrQMD model, and provided insight into the details of the microscopic dynamical features of nuclear collisions at high energy. J. Sandweiss and J. Kapusta addressed the interesting aspect of photon production in peripherical nuclear collisions due to intense electromagnetic bremstrahlung by the highly charged, fast moving ions. Finally, H. Sorge closed up the one-day workshop with a presentation of his recent work with the RQMD model. This report consists of a summary and vugraphs of the presentations.

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}).
Multiple collision effects on the antiproton production by high energy proton (100 GeV - 1000 GeV)

International Nuclear Information System (INIS)

Takahashi, Hiroshi; Powell, J.

1987-01-01

Antiproton production rates which take into account multiple collision are calculated using a simple model. Methods to reduce capture of the produced antiprotons by the target are discussed, including geometry of target and the use of a high intensity laser. Antiproton production increases substantially above 150 GeV proton incident energy. The yield increases almost linearly with incident energy, alleviating space charge problems in the high current accelerator that produces large amounts of antiprotons
Hydrodynamic evolution and jet energy loss in Cu + Cu collisions

International Nuclear Information System (INIS)

Schenke, Bjoern; Jeon, Sangyong; Gale, Charles

2011-01-01

We present results from a hybrid description of Cu + Cu collisions using (3 + 1)-dimensional hydrodynamics (music) for the bulk evolution and a Monte Carlo simulation (martini) for the evolution of high-momentum partons in the hydrodynamical background. We explore the limits of this description by going to small system sizes and determine the dependence on different fractions of wounded nucleon and binary collisions scaling of the initial energy density. We find that Cu + Cu collisions are well described by the hybrid description at least up to 20% central collisions.
Transverse momentum in high-energy nuclear collisions: Collective expansion

International Nuclear Information System (INIS)

Wang, X.; Hwa, R.C.

1987-01-01

Hadron production in the central region in high-energy nuclear collisions is investigated. The hydrodynamical expansion of a locally thermalized system is studied for both the cases with and without phase transition. The case with phase transition is considered by using a sound-velocity function c/sub s/(T) parametrized to fit the energy density determined in a lattice gauge calculation. The effect of a transverse rarefaction wave is included in the calculation of the temperature profile of the expanding fluid. The transverse-momentum distribution of hadrons is calculated by collecting all the hadrons produced when the hadron gas is cooled down to a freeze-out temperature at different times in the expansion. Fluctuation in initial temperature and radius is allowed due to variation in impact parameter. On the basis of a study of the thermalization process in the parton model we impose a constraint on the initial temperature and the thermalization time, the simultaneous variation of both of which gives rise to a relationship between the average transverse momentum and rapidity density. We have found that there is no so-called ''plateau'' region in that relationship. The implication on the diagnostics of a quark-gluon plasma is discussed
Charge transfer and ionization in collisions of Si3+ with H from low to high energy

Science.gov (United States)

Wang, J. G.; He, B.; Ning, Y.; Liu, C. L.; Yan, J.; Stancil, P. C.; Schultz, D. R.

2006-11-01

Charge transfer processes due to collisions of ground state Si3+(3sS1) ions with atomic hydrogen are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) and classical-trajectory Monte Carlo (CTMC) methods. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained from Herrero [J. Phys. B 29, 5583 (1996)] which were calculated with a full configuration-interaction method. Total and state-selective single-electron capture cross sections are obtained for collision energies from 0.01eV/u to 1MeV/u . Total and state-selective rate coefficients are also presented for temperatures from 2×103K to 107K . Comparison with existing data reveals that the total CTMC cross sections are in good agreement with the experimental measurements at the higher considered energies and that previous Landau-Zener calculations underestimate the total rate coefficients by a factor of up to two. The CTMC calculations of target ionization are presented for high energies.
Studies of QCD structure in high-energy collisions

International Nuclear Information System (INIS)

Nadolsky, Pavel M.

2016-01-01

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

Science.gov (United States)

Rodgers, M. T.; Armentrout, P. B.

1998-08-01

Collision-induced dissociation of (R1OH)Li+(R2OH) with xenon is studied using guided ion beam mass spectrometry. R1OH and R2OH include the following molecules: water, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol. In all cases, the primary products formed correspond to endothermic loss of one of the neutral alcohols, with minor products that include those formed by ligand exchange and loss of both ligands. The cross-section thresholds are interpreted to yield 0 and 298 K bond energies for (R1OH)Li+-R2OH and relative Li+ binding affinities of the R1OH and R2OH ligands after accounting for the effects of multiple ion-molecule collisions, internal energy of the reactant ions, and dissociation lifetimes. We introduce a means to simultaneously analyze the cross sections for these competitive dissociations using statistical theories to predict the energy dependent branching ratio. Thermochemistry in good agreement with previous work is obtained in all cases. In essence, this statistical approach provides a detailed means of correcting for the "competitive shift" inherent in multichannel processes.
Collision-induced coherence

International Nuclear Information System (INIS)

Bloembergen, N.

1985-01-01

Collision-induced coherence is based on the elimination of phase correlations between coherent Feynman-type pathways which happen to interfere destructively in the absence of damping for certain nonlinear processes. One consequence is the appearance of the extra resonances in four-wave light mixing experiments, for which the intensity increases with increasing buffer gas pressure. These resonances may occur between a pair of initially unpopulated excited states, or between a pair of initially equally populated ground states. The pair of levels may be Zeeman substrates which became degenerate in zero magnetic field. The resulting collision-enhanced Hanle resonances can lead to very sharp variations in the four-wave light mixing signal as the external magnetic field passes through zero. The theoretical description in terms of a coherence grating between Zeeman substrates is equivalent to a description in terms of a spin polarization grating obtained by collision-enhanced transverse optical pumping. The axis of quantization in the former case is taken perpendicular to the direction of the light beams; in the latter case is taken parallel to this direction
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....
Correlation between the pionization region and the fragmentation region in high energy proton-proton collisions

CERN Document Server

Albrow, M G; Barber, D P; Bogaerts, A; Bosnjakovic, B; Brooks, J R; Clegg, A B; Erné, F C; Gee, C N P; Locke, D H; Loebinger, F K; Murphy, P G; Rudge, A; Sens, Johannes C

1973-01-01

Measurements are reported of two-particle correlations in high energy proton-proton collisions with one particle in the pionization region and the other a proton in the fragmentation region. The correlation function is independent of x of the fragmentation proton for 0.55energy-independent function of x. The measurements for two values of the rapidity of the pionization particle give similar results. (11 refs).
Atomic collisions by neutrons-induced charged particles in water, protein and nucleic acid

International Nuclear Information System (INIS)

Bergman, R.

1976-01-01

The action of slow charged particles is peculiar in that atomic collisions are commonly invlolved. In atomic collisions, which are rare events when fast particles interact with matter, displacement of atoms and chemical bond-breakage is possible. Sufficiently energetic neutrons generate charged recoil particles in matter. Some of these are slow as compared to orbital electrons, but the energy transferred to such slow particles is generally relatively small. Yet, it contributes significantly to the dose absorbed from 0.1-30 keV neutrons. In tissue all recoils induced by neutrons of less than 30 keV are slow, and above 0.1 keV the absorbed dose due to collisiondominates over that due to capture reactions. The aim of the present paper is to identify those intervals of neutron energy in which atomic collision damage is most probable in living matter. The results of calculations presented here indicate that atomic collisions should be most significant for 0.5-3 keV neutrons. (author)
The energy-deposition model. Electron loss of heavy ions in collisions with neutral atoms at low and intermediate energies

International Nuclear Information System (INIS)

Shevelko, V.P.; Litsarev, M.S.; Kato, D.; Tawara, H.

2010-09-01

Single- and multiple-electron loss processes in collisions of heavy many-electron ions (positive and negative) in collisions with neutral atoms at low and intermediate energies are considered using the energy-deposition model. The DEPOSIT computer code, created earlier to calculate electron-loss cross sections at high projectile energies, is extended for low and intermediate energies. A description of a new version of DEPOSIT code is given, and the limits of validity for collision velocity in the model are discussed. Calculated electron-loss cross sections for heavy ions and atoms (N + , Ar + , Xe + , U + , U 28+ , W, W + , Ge - , Au - ), colliding with neutral atoms (He, Ne, Ar, W) are compared with available experimental and theoretical data at energies E > 10 keV/u. It is found that in most cases the agreement between experimental data and the present model is within a factor of 2. Combining results obtained by the DEPOSIT code at low and intermediate energies with those by the LOSS-R code at high energies (relativistic Born approximation), recommended electron-loss cross sections in a wide range of collision energy are presented. (author)
The problem of phase transition and the heavy ion collisions at very high energies

International Nuclear Information System (INIS)

Waheed, A.

1993-09-01

This paper presents a review of our current understanding of deconfined phases of strongly interacting matter at high energy densities - quark matter, or the quark-gluon plasma, likely to be produced in ultra-relativistic heavy ion collisions. Properties of the deconfined quark matter and speculations concerning the ways in which this phase transition can be explored in laboratory are discussed. Some suggestions have been put forward for the future experiments. (author). 91 refs
Experimental and phenomenological investigations of QCD matter in high-energy nucleus-nucleus collisions

Energy Technology Data Exchange (ETDEWEB)

Andronic, Anton

2014-07-15

This thesis is heterogeneous, comprising experimental papers at low energies (SIS-18 at GSI) and at the LHC, papers on phenomenology of high-energy nucleus-nucleus collisions, and papers on detectors. The overview covers the experimental papers and those on phenomenology. I have chosen to write it in a general manner, intended to be accessible to non-experts. It emphasizes recent measurements and their understanding at the LHC. The detector papers, which address many principle aspects of gaseous detectors, are summarized and placed in context in the review I co-wrote and which closes the stack. The detector papers included here are the outcome of an R and D program for the Transition Radiation Detector of ALICE.
Experimental and phenomenological investigations of QCD matter in high-energy nucleus-nucleus collisions

International Nuclear Information System (INIS)

Andronic, Anton

2014-07-01

This thesis is heterogeneous, comprising experimental papers at low energies (SIS-18 at GSI) and at the LHC, papers on phenomenology of high-energy nucleus-nucleus collisions, and papers on detectors. The overview covers the experimental papers and those on phenomenology. I have chosen to write it in a general manner, intended to be accessible to non-experts. It emphasizes recent measurements and their understanding at the LHC. The detector papers, which address many principle aspects of gaseous detectors, are summarized and placed in context in the review I co-wrote and which closes the stack. The detector papers included here are the outcome of an R and D program for the Transition Radiation Detector of ALICE.
Heavy ion collisions at energies near the Coulomb barrier 1990

International Nuclear Information System (INIS)

Nagarajan, M.A.

1991-01-01

During recent years, detailed experimental and theoretical investigations have been carried out on heavy ion collisions at energies close to the Coulomb barrier. These studies have provided direct evidence of strong couplings between the various reaction channels available at energies near the top of the Coulomb barrier. This field of research has remained the focus of interest and with improved experimental techniques, new detailed high resolution data have been obtained. The workshop on ''Heavy Ion Collisions at Energies Close to the Coulomb Barrier'' was organized with the aim of reviewing the current understanding of the collision dynamics and to discuss future directions in this area of research. The topics discussed at the workshop were broadly classified under the titles: quasielastic reactions; fusion of heavy ions; and shape and spin dependence in heavy ion collisions. The last of these topics was included to review new data obtained with polarized heavy ions and their theoretical interpretations. This volume contains the invited and contributed talks as well as a few short presentations during panel discussions. (author)
Are high energy heavy ion collisions similar to a little bang, or just a very nice firework?

Energy Technology Data Exchange (ETDEWEB)

Shuryak, E.V. [State University of New York, NY (United States)

2001-07-01

The talk is a brief overview of recent progress in heavy ion physics, with emphasis on applications of macroscopic approaches. The central issues are whether the systems exhibit macroscopic behavior we need in order to interpret it as excited hadronic matter, and, if so, what is its effective Equation of State (EoS). This, in turn, depends on the collision rate in matter: we think we understand in hadronic matter near freeze-out, but certainly not at earlier stages of the collisions. Still (and this is about the most important statement we make) there is no indication that is not high enough, so that a hydro description of excited matter be possible. More specifically, we concentrate on such properties of the produced excited system as collective flow, particle composition and fluctuations relaxation are ultimately a measure of a collision rate we would like to know. We also try to explain what exactly are the expected differences between collisions at AGS/SPS and RHIC energies. (author)
Are high energy heavy ion collisions similar to a little bang, or just a very nice firework?

International Nuclear Information System (INIS)

Shuryak, E.V.

2001-01-01

The talk is a brief overview of recent progress in heavy ion physics, with emphasis on applications of macroscopic approaches. The central issues are whether the systems exhibit macroscopic behavior we need in order to interpret it as excited hadronic matter, and, if so, what is its effective Equation of State (EoS). This, in turn, depends on the collision rate in matter: we think we understand in hadronic matter near freeze-out, but certainly not at earlier stages of the collisions. Still (and this is about the most important statement we make) there is no indication that is not high enough, so that a hydro description of excited matter be possible. More specifically, we concentrate on such properties of the produced excited system as collective flow, particle composition and fluctuations relaxation are ultimately a measure of a collision rate we would like to know. We also try to explain what exactly are the expected differences between collisions at AGS/SPS and RHIC energies. (author)
Monte Carlo event generator MCMHA for high energy hadron-nucleus collisions and intranuclear cascade interactions

International Nuclear Information System (INIS)

Iga, Y.; Hamatsu, R.; Yamazaki, S.

1988-01-01

The Monte Carlo event generator for high energy hadron-nucleus (h-A) collisions has been developed which is based on the multi-chain model. The concept of formation zone and the cascade interactions of secondary particles are properly taken into account in this Monte Carlo code. Comparing the results of this code with experimental data, the importance of intranuclear cascade interactions becomes very clear. (orig.)
Calibrating a multi-model approach to defect production in high energy collision cascades

International Nuclear Information System (INIS)

Heinisch, H.L.; Singh, B.N.; Diaz de la Rubia, T.

1994-01-01

A multi-model approach to simulating defect production processes at the atomic scale is described that incorporates molecular dynamics (MD), binary collision approximation (BCA) calculations and stochastic annealing simulations. The central hypothesis is that the simple, fast computer codes capable of simulating large numbers of high energy cascades (e.g., BCA codes) can be made to yield the correct defect configurations when their parameters are calibrated using the results of the more physically realistic MD simulations. The calibration procedure is investigated using results of MD simulations of 25 keV cascades in copper. The configurations of point defects are extracted from the MD cascade simulations at the end of the collisional phase, thus providing information similar to that obtained with a binary collision model. The MD collisional phase defect configurations are used as input to the ALSOME annealing simulation code, and values of the ALSOME quenching parameters are determined that yield the best fit to the post-quenching defect configurations of the MD simulations. ((orig.))

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
On the nuclear fragmentation mechanisms in nuclear collisions at intermediate and high energies

International Nuclear Information System (INIS)

Jipa, Al; Besliu, C.; Felea, D.

2004-01-01

The nuclear fragmentation mechanisms can be discussed by taking into account different scales related to the fragment sizes. Considering two fragmentation mechanisms of the nuclei at the same incident energy an analysis of the experimental results obtained was done. Goldhaber formula was improved by analyzing the discrepancies between data and theories concerning the projectile fragmentation. We implied that the projectile fragmentation process would be governed by the distribution of nucleon momenta in the projectile after the collision occurred. We used in our analysis protons from the 4 He + 7 Li at 4.5 GeV/c per nucleon incident momentum, as well as from 40 Ar + 12 C at 213 AMeV bombarding energy. We proved that in order to proceed in analyzing the projectile fragmentation process at intermediate and high energies one has to consider the dependence σ 0 on the apparent temperature of projectile nucleus after the collision took place. The generalized Bertsch correction for light projectile nuclei and fragments was used and the number of spatial correlations between identical nucleons having anticorrelated momenta was found. Thus we found apparent temperature values close to the separation energies of the considered fragments per number of fragments. The temperatures associated to kinetic energy spectra of the projectile fragments were calculated following two methods. The results from Bauer's method were compared with those obtained by fitting the kinetic energy distributions of the projectile fragments in the rest frame of the projectile with a Maxwellian curve. We also accomplished the comparison of the experimental results with similar events simulated with RQMD 2.4. All the results obtained suggested two nuclear fragmentation mechanisms: a sudden fragmentation by explosive mechanisms, like shock waves and a slow fragmentation by the 'fission' of the spectator regions, mainly because of the interactions with the particles or fragments emitted from the
Out-of-equilibrium phenomena in high energy nuclear collisions

CERN Document Server

Serreau, J

2001-01-01

In the first part we study the possibility that a Disoriented Chiral Condensate (DCC) forms when hot hadronic matter is quenched, using the linear sigma model. We formulate an original sampling strategy for the initial field configuration in order to get an estimate of the probability that a potentially observable coherent pion field appears in a heavy-ion collision. We obtain a probability of the order of 1/1000 at CERN SPS energies. Next, we study the correlation between isospin orientations of the distinct modes of the pion field emerging after a quench. We show that this correlation is absent: the distinct modes behave as distinct DCCs. This contradicts the common belief that the state produced in the simplest form of the quench scenario - with a fully thermalized initial state - is identical to the originally proposed DCC. In the second part, we investigate the role of elastic scatterings in the process of kinetic equilibration of gluons produced in the very early times of the collision. We compare the t...
Minijet thermalization and diffusion of transverse momentum correlation in high-energy heavy-ion collisions

International Nuclear Information System (INIS)

Pang Longgang; Wang Qun; Wang Xinnian; Xu Rong

2010-01-01

Transverse momentum correlations in the azimuthal angle of hadrons produced owing to minijets are first studied within the HIJING Monte Carlo model in high-energy heavy-ion collisions. Quenching of minijets during thermalization is shown to lead to significant diffusion (broadening) of the correlation. Evolution of the transverse momentum density fluctuation that gives rise to this correlation in azimuthal angle in the later stage of heavy-ion collisions is further investigated within a linearized diffusion-like equation and is shown to be determined by the shear viscosity of the evolving dense matter. This diffusion equation for the transverse momentum fluctuation is solved with initial values given by HIJING and together with the hydrodynamic equation for the bulk medium. The final transverse momentum correlation in azimuthal angle is calculated along the freeze-out hypersurface and is found to be further diffused for higher values of the shear viscosity to entropy density ratio, η/s∼0.2-0.4. Therefore the final transverse momentum correlation in azimuthal angle can be used to study the thermalization of minijets in the early stage of heavy-ion collisions and the viscous effect in the hydrodynamic evolution of strongly coupled quark-gluon plasma.
Charge transfer and ionization in collisions of Si3+ with H from low to high energy

International Nuclear Information System (INIS)

Wang, J. G.; He, B.; Ning, Y.; Liu, C. L.; Yan, J.; Stancil, P. C.; Schultz, D. R.

2006-01-01

Charge transfer processes due to collisions of ground state Si 3+ (3s 1 S) ions with atomic hydrogen are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) and classical-trajectory Monte Carlo (CTMC) methods. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained from Herrero et al. [J. Phys. B 29, 5583 (1996)] which were calculated with a full configuration-interaction method. Total and state-selective single-electron capture cross sections are obtained for collision energies from 0.01 eV/u to 1 MeV/u. Total and state-selective rate coefficients are also presented for temperatures from 2x10 3 K to 10 7 K. Comparison with existing data reveals that the total CTMC cross sections are in good agreement with the experimental measurements at the higher considered energies and that previous Landau-Zener calculations underestimate the total rate coefficients by a factor of up to two. The CTMC calculations of target ionization are presented for high energies
Partial inelasticity coefficients of negative pions produced in hadron-nucleus and nucleus-nucleus collisions at high energies

International Nuclear Information System (INIS)

OLIMOV, K.; LUTPULLAEV, S.L.; PETROV, V.I.; OLIMOV, A.K.

2015-01-01

New experimental data on the partial inelasticity coefficients of negative pions produced in "1"6Op-collisions at 3.25 A GeV/s, pC-interactions at 4.2 and 9.9 GeV/s, and d,α,C(C)-collisions at 4.2 A GeV/s are presented. It is established that the behavior of partial inelasticity coefficients of pions at intermediate energies (<10 GeV) in hadron-nucleus collisions has a transitional character, reaching the limiting value at ultrahigh energies. It is shown that the mean values of partial inelasticity coefficients of pions produced in nucleus-nucleus collisions decrease with an increase in mass number of the projectile nucleus. (authors)
Transverse energy and charged particle multiplicity in 14.6 GeV/c proton-nucleus collisions

International Nuclear Information System (INIS)

Wang, Gang

1995-01-01

Transverse energy and charged particle multiplicity produced in 14.6 GeV/c p + Al and p + Pb collisions have been studied using the E814 set-up at the BNL-AGS. Measurements of dσ/dE T , dE T /dη,dσ/dN c , and dN c /dη are presented. From the present data the mean transverse energy per particle is obtained and it is compared to values observed in Si induced collisions at the same energy In contrast to what is observed in nucleus-nucleus collisions, a very weak correlation is found between the transverse energy and the charged particle multiplicity. These results are compared to the predictions of various theoretical models used to describe heavy-ion collisions. The event generators RQMD and HIJET reproduce well the pseudorapidity distribution of both the transverse energy and charged particle multiplicity, whereas FRITIOF fails to reproduce the measured distributions. Contrary to what had been suggested previously in a Si + A study, the present study shows that the pseudorapidity dependence of charged particle multiplicity distributions do not follow KNO scaling. (author)
Cluster-collision frequency. II. Estimation of the collision rate

International Nuclear Information System (INIS)

Amadon, A.S.; Marlow, W.H.

1991-01-01

Gas-phase cluster-collision rates, including effects of cluster morphology and long-range intermolecular forces, are calculated. Identical pairs of icosahedral or dodecahedral carbon tetrachloride clusters of 13, 33, and 55 molecules in two different relative orientations were discussed in the preceding paper [Phys. Rev. A 43, 5483 (1991)]: long-range interaction energies were derived based upon (i) exact calculations of the iterated, or many-body, induced-dipole interaction energies for the clusters in two fixed relative orientations; and (ii) bulk, or continuum descriptions (Lifshitz--van der Waals theory), of spheres of corresponding masses and diameters. In this paper, collision rates are calculated according to an exact description of the rates for small spheres interacting via realistic potentials. Utilizing the interaction energies of the preceding paper, several estimates of the collision rates are given by treating the discrete clusters in fixed relative orientations, by computing rotationally averaged potentials for the discrete clusters, and by approximating the clusters as continuum spheres. For the discrete, highly symmetric clusters treated here, the rates using the rotationally averaged potentials closely approximate the fixed-orientation rates and the values of the intercluster potentials for cluster surface separations under 2 A have negligible effect on the overall collision rates. While the 13-molecule cluster-collision rate differs by 50% from the rate calculated as if the cluster were bulk matter, the two larger cluster-collision rates differ by less than 15% from the macroscopic rates, thereby indicating the transition of microscopic to macroscopic behavior
Enhanced production of multi-strange hadrons in high-multiplicity proton–proton collisions

CERN Document Server

Adam, Jaroslav; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agrawal, Neelima; Ahammed, Zubayer; Ahmad, Shakeel; Ahn, Sang Un; Aiola, Salvatore; Akindinov, Alexander; Alam, Sk Noor; Silva De Albuquerque, Danilo; Aleksandrov, Dmitry; Alessandro, Bruno; Alexandre, Didier; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altinpinar, Sedat; Altsybeev, Igor; Alves Garcia Prado, Caio; An, Mangmang; Andrei, Cristian; Andrews, Harry Arthur; Andronic, Anton; Anguelov, Venelin; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arcelli, Silvia; Arnaldi, Roberta; Arnold, Oliver Werner; Arsene, Ionut Cristian; Arslandok, Mesut; Audurier, Benjamin; Augustinus, Andre; Averbeck, Ralf Peter; Azmi, Mohd Danish; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bala, Renu; Balasubramanian, Supraja; Baldisseri, Alberto; Baral, Rama Chandra; Barbano, Anastasia Maria; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Ramillien Barret, Valerie; Bartalini, Paolo; Barth, Klaus; Bartke, Jerzy Gustaw; Bartsch, Esther; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batista Camejo, Arianna; Batyunya, Boris; Batzing, Paul Christoph; Bearden, Ian Gardner; Beck, Hans; Bedda, Cristina; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bello Martinez, Hector; Bellwied, Rene; Belmont Iii, Ronald John; Belmont Moreno, Ernesto; Espinoza Beltran, Lucina Gabriela; Belyaev, Vladimir; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bertens, Redmer Alexander; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhat, Inayat Rasool; Bhati, Ashok Kumar; Bhattacharjee, Buddhadeb; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Biro, Gabor; Biswas, Rathijit; Biswas, Saikat; Bjelogrlic, Sandro; Blair, Justin Thomas; Blau, Dmitry; Blume, Christoph; Bock, Friederike; Bogdanov, Alexey; Boggild, Hans; Boldizsar, Laszlo; Bombara, Marek; Bonora, Matthias; Book, Julian Heinz; Borel, Herve; Borissov, Alexander; Borri, Marcello; Bossu, Francesco; Botta, Elena; Bourjau, Christian; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Broker, Theo Alexander; Browning, Tyler Allen; Broz, Michal; Brucken, Erik Jens; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Buncic, Predrag; Busch, Oliver; Buthelezi, Edith Zinhle; Bashir Butt, Jamila; Buxton, Jesse Thomas; Cabala, Jan; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calero Diaz, Liliet; Caliva, Alberto; Calvo Villar, Ernesto; Camerini, Paolo; Carena, Francesco; Carena, Wisla; Carnesecchi, Francesca; Castillo Castellanos, Javier Ernesto; Castro, Andrew John; Casula, Ester Anna Rita; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Cerkala, Jakub; Chang, Beomsu; Chapeland, Sylvain; Chartier, Marielle; Charvet, Jean-Luc Fernand; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Chauvin, Alex; Chelnokov, Volodymyr; Cherney, Michael Gerard; Cheshkov, Cvetan Valeriev; Cheynis, Brigitte; Chibante Barroso, Vasco Miguel; Dobrigkeit Chinellato, David; Cho, Soyeon; Chochula, Peter; Choi, Kyungeon; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Colamaria, Fabio Filippo; Colella, Domenico; Collu, Alberto; Colocci, Manuel; Conesa Balbastre, Gustavo; Conesa Del Valle, Zaida; Connors, Megan Elizabeth; Contreras Nuno, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortes Maldonado, Ismael; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Crkovska, Jana; Crochet, Philippe; Cruz Albino, Rigoberto; Cuautle Flores, Eleazar; Cunqueiro Mendez, Leticia; Dahms, Torsten; Dainese, Andrea; Danisch, Meike Charlotte; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Supriya; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; De Caro, Annalisa; De Cataldo, Giacinto; De Conti, Camila; De Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; Derradi De Souza, Rafael; Deisting, Alexander; Deloff, Andrzej; Denes, Ervin Sandor; Deplano, Caterina; Dhankher, Preeti; Di Bari, Domenico; Di Mauro, Antonio; Di Nezza, Pasquale; Di Ruzza, Benedetto; Diaz Corchero, Miguel Angel; Dietel, Thomas; Dillenseger, Pascal; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Domenicis Gimenez, Diogenes; Donigus, Benjamin; Dordic, Olja; Drozhzhova, Tatiana; Dubey, Anand Kumar; Dubla, Andrea; Ducroux, Laurent; Dupieux, Pascal; Ehlers Iii, Raymond James; Elia, Domenico; Endress, Eric; Engel, Heiko; Epple, Eliane; Erazmus, Barbara Ewa; Erdemir, Irem; Erhardt, Filip; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Eum, Jongsik; Evans, David; Evdokimov, Sergey; Eyyubova, Gyulnara; Fabbietti, Laura; Fabris, Daniela; Faivre, Julien; Fantoni, Alessandra; Fasel, Markus; Feldkamp, Linus; Feliciello, Alessandro; Feofilov, Grigorii; Ferencei, Jozef; Fernandez Tellez, Arturo; Gonzalez Ferreiro, Elena; Ferretti, Alessandro; Festanti, Andrea; Feuillard, Victor Jose Gaston; Figiel, Jan; Araujo Silva Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiore, Enrichetta Maria; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Francescon, Andrea; Francisco, Audrey; Frankenfeld, Ulrich Michael; Fronze, Gabriele Gaetano; Fuchs, Ulrich; Furget, Christophe; Furs, Artur; Fusco Girard, Mario; Gaardhoeje, Jens Joergen; Gagliardi, Martino; Gago Medina, Alberto Martin; Gajdosova, Katarina; Gallio, Mauro; Duarte Galvan, Carlos; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Gao, Chaosong; Garabatos Cuadrado, Jose; Garcia-Solis, Edmundo Javier; Garg, Kunal; Gargiulo, Corrado; Gasik, Piotr Jan; Gauger, Erin Frances; Germain, Marie; Gheata, Mihaela; Ghosh, Premomoy; Ghosh, Sanjay Kumar; Gianotti, Paola; Giubellino, Paolo; Giubilato, Piero; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez Coral, Diego Mauricio; Gomez Ramirez, Andres; Sanchez Gonzalez, Andres; Gonzalez, Victor; Gonzalez Zamora, Pedro; Gorbunov, Sergey; Gorlich, Lidia Maria; Gotovac, Sven; Grabski, Varlen; Grachov, Oleg Anatolievich; Graczykowski, Lukasz Kamil; Graham, Katie Leanne; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoryev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grynyov, Borys; Grion, Nevio; Gronefeld, Julius Maximilian; Grosse-Oetringhaus, Jan Fiete; Grosso, Raffaele; Gruber, Lukas; Guber, Fedor; Guernane, Rachid; Guerzoni, Barbara; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Haake, Rudiger; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Hamon, Julien Charles; Harris, John William; Harton, Austin Vincent; Hatzifotiadou, Despina; Hayashi, Shinichi; Heckel, Stefan Thomas; Hellbar, Ernst; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Herrmann, Florian; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hillemanns, Hartmut; Hippolyte, Boris; Horak, David; Hosokawa, Ritsuya; Hristov, Peter Zahariev; Hughes, Charles; Humanic, Thomas; Hussain, Nur; Hussain, Tahir; Hutter, Dirk; Hwang, Dae Sung; Ilkaev, Radiy; Inaba, Motoi; Incani, Elisa; Ippolitov, Mikhail; Irfan, Muhammad; Isakov, Vladimir; Ivanov, Marian; Ivanov, Vladimir; Izucheev, Vladimir; Jacak, Barbara; Jacazio, Nicolo; Jacobs, Peter Martin; Jadhav, Manoj Bhanudas; Jadlovska, Slavka; Jadlovsky, Jan; Jahnke, Cristiane; Jakubowska, Monika Joanna; Janik, Malgorzata Anna; Pahula Hewage, Sandun; Jena, Chitrasen; Jena, Satyajit; Jimenez Bustamante, Raul Tonatiuh; Jones, Peter Graham; Jusko, Anton; Kalinak, Peter; Kalweit, Alexander Philipp; Kang, Ju Hwan; Kaplin, Vladimir; Kar, Somnath; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karayan, Lilit; Karpechev, Evgeny; Kebschull, Udo Wolfgang; Keidel, Ralf; Keijdener, Darius Laurens; Keil, Markus; Khan, Mohammed Mohisin; Khan, Palash; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Khatun, Anisa; Kileng, Bjarte; Kim, Do Won; Kim, Dong Jo; Kim, Daehyeok; Kim, Hyeonjoong; Kim, Jinsook; Kim, Jiyoung; Kim, Minwoo; Kim, Se Yong; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Kiss, Gabor; Klay, Jennifer Lynn; Klein, Carsten; Klein, Jochen; Klein-Boesing, Christian; Klewin, Sebastian; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Kobdaj, Chinorat; Kofarago, Monika; Kollegger, Thorsten; Kolozhvari, Anatoly; Kondratev, Valerii; Kondratyeva, Natalia; Kondratyuk, Evgeny; Konevskikh, Artem; Kopcik, Michal; Kour, Mandeep; Kouzinopoulos, Charalampos; Kovalenko, Oleksandr; Kovalenko, Vladimir; Kowalski, Marek; Koyithatta Meethaleveedu, Greeshma; Kralik, Ivan; Kravcakova, Adela; Krivda, Marian; Krizek, Filip; Kryshen, Evgeny; Krzewicki, Mikolaj; Kubera, Andrew Michael; Kucera, Vit; Kuhn, Christian Claude; Kuijer, Paulus Gerardus; Kumar, Ajay; Kumar, Jitendra; Kumar, Lokesh; Kumar, Shyam; Kurashvili, Podist; Kurepin, Alexander; Kurepin, Alexey; Kuryakin, Alexey; Kweon, Min Jung; Kwon, Youngil; La Pointe, Sarah Louise; La Rocca, Paola; Ladron De Guevara, Pedro; Lagana Fernandes, Caio; Lakomov, Igor; Langoy, Rune; Lapidus, Kirill; Lara Martinez, Camilo Ernesto; Lardeux, Antoine Xavier; Lattuca, Alessandra; Laudi, Elisa; Lea, Ramona; Leardini, Lucia; Lee, Seongjoo; Lehas, Fatiha; Lehner, Sebastian; Lemmon, Roy Crawford; Lenti, Vito; Leogrande, Emilia; Leon Monzon, Ildefonso; Leon Vargas, Hermes; Leoncino, Marco; Levai, Peter; Li, Shuang; Li, Xiaomei; Lien, Jorgen Andre; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Ljunggren, Hans Martin; Lodato, Davide Francesco; Lonne, Per-Ivar; Loginov, Vitaly; Loizides, Constantinos; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lowe, Andrew John; Luettig, Philipp Johannes; Lunardon, Marcello; Luparello, Grazia; Lupi, Matteo; Lutz, Tyler Harrison; Maevskaya, Alla; Mager, Magnus; Mahajan, Sanjay; Mahmood, Sohail Musa; Maire, Antonin; Majka, Richard Daniel; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Liudmila; Mal'Kevich, Dmitry; Malzacher, Peter; Mamonov, Alexander; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Margutti, Jacopo; Marin, Ana Maria; Markert, Christina; Marquard, Marco; Martin, Nicole Alice; Martinengo, Paolo; Martinez Hernandez, Mario Ivan; Martinez-Garcia, Gines; Martinez Pedreira, Miguel; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Mastroserio, Annalisa; Matyja, Adam Tomasz; Mayer, Christoph; Mazer, Joel Anthony; Mazzilli, Marianna; Mazzoni, Alessandra Maria; Mcdonald, Daniel; Meddi, Franco; Melikyan, Yuri; Menchaca-Rocha, Arturo Alejandro; Meninno, Elisa; Mercado-Perez, Jorge; Meres, Michal; Mhlanga, Sibaliso; Miake, Yasuo; Mieskolainen, Matti Mikael; Mikhaylov, Konstantin; Milano, Leonardo; Milosevic, Jovan; Mischke, Andre; Mishra, Aditya Nath; Mishra, Tribeni; Miskowiec, Dariusz Czeslaw; Mitra, Jubin; Mitu, Ciprian Mihai; Mohammadi, Naghmeh; Mohanty, Bedangadas; Molnar, Levente; Montano Zetina, Luis Manuel; Montes Prado, Esther; Moreira De Godoy, Denise Aparecida; Perez Moreno, Luis Alberto; Moretto, Sandra; Morreale, Astrid; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhlheim, Daniel Michael; Muhuri, Sanjib; Mukherjee, Maitreyee; Mulligan, James Declan; Gameiro Munhoz, Marcelo; Munning, Konstantin; Munzer, Robert Helmut; Murakami, Hikari; Murray, Sean; Musa, Luciano; Musinsky, Jan; Naik, Bharati; Nair, Rahul; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Naru, Muhammad Umair; Ferreira Natal Da Luz, Pedro Hugo; Nattrass, Christine; Rosado Navarro, Sebastian; Nayak, Kishora; Nayak, Ranjit; Nayak, Tapan Kumar; Nazarenko, Sergey; 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Paul, Biswarup; Pei, Hua; Peitzmann, Thomas; Peng, Xinye; Pereira Da Costa, Hugo Denis Antonio; Peresunko, Dmitry Yurevich; Perez Lezama, Edgar; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petrov, Viacheslav; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Pikna, Miroslav; Pillot, Philippe; Ozelin De Lima Pimentel, Lais; Pinazza, Ombretta; Pinsky, Lawrence; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Planinic, Mirko; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polishchuk, Boris; Poljak, Nikola; Poonsawat, Wanchaloem; Pop, Amalia; Poppenborg, Hendrik; Porteboeuf, Sarah Julie; Porter, R Jefferson; Pospisil, Jan; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puccio, Maximiliano; Puddu, Giovanna; Pujahari, Prabhat Ranjan; Punin, Valery; Putschke, Jorn Henning; Qvigstad, Henrik; Rachevski, Alexandre; Raha, Sibaji; Rajput, Sonia; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Rami, Fouad; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Ravasenga, Ivan; Read, Kenneth Francis; Redlich, Krzysztof; Reed, Rosi Jan; Rehman, Attiq Ur; Reichelt, Patrick Simon; Reidt, Felix; Ren, Xiaowen; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Reygers, Klaus Johannes; Riabov, Viktor; Ricci, Renato Angelo; Richert, Tuva Ora Herenui; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Ristea, Catalin-Lucian; Rodriguez Cahuantzi, Mario; Rodriguez Manso, Alis; Roeed, Ketil; Rogochaya, Elena; Rohr, David Michael; Roehrich, Dieter; Ronchetti, Federico; Ronflette, Lucile; Rosnet, Philippe; Rossi, Andrea; Roukoutakis, Filimon; Roy, Ankhi; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Russo, Riccardo; Ryabinkin, Evgeny; Ryabov, Yury; Rybicki, Andrzej; Saarinen, Sampo; Sadhu, Samrangy; Sadovskiy, Sergey; Safarik, Karel; Sahlmuller, Baldo; Sahoo, Pragati; Sahoo, Raghunath; Sahoo, Sarita; Sahu, Pradip Kumar; Saini, Jogender; Sakai, Shingo; Saleh, Mohammad Ahmad; Salzwedel, Jai Samuel Nielsen; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sandor, Ladislav; Sandoval, Andres; Sano, Masato; Sarkar, Debojit; Sarkar, Nachiketa; Sarma, Pranjal; Scapparone, Eugenio; Scarlassara, Fernando; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schmidt, Martin; Schuchmann, Simone; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Rebecca Michelle; Sefcik, Michal; Seger, Janet Elizabeth; Sekiguchi, Yuko; Sekihata, Daiki; Selyuzhenkov, Ilya; Senosi, Kgotlaesele; Senyukov, Serhiy; Serradilla Rodriguez, Eulogio; Sevcenco, Adrian; Shabanov, Arseniy; Shabetai, Alexandre; Shadura, Oksana; Shahoyan, Ruben; Shangaraev, Artem; Sharma, Ankita; Sharma, Mona; Sharma, Monika; Sharma, Natasha; Sheikh, Ashik Ikbal; Shigaki, Kenta; Shou, Qiye; Shtejer Diaz, Katherin; Sibiryak, Yury; Siddhanta, Sabyasachi; Sielewicz, Krzysztof Marek; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, Catherine Micaela; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singhal, Vikas; Sarkar - Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Slupecki, Maciej; Smirnov, Nikolai; Snellings, Raimond; Snellman, Tomas Wilhelm; Song, Jihye; Song, Myunggeun; Song, Zixuan; Soramel, Francesca; Sorensen, Soren Pontoppidan; Sozzi, Federica; Spiriti, Eleuterio; Sputowska, Iwona Anna; Spyropoulou-Stassinaki, Martha; Stachel, Johanna; Stan, Ionel; Stankus, Paul; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Strmen, Peter; Alarcon Do Passo Suaide, Alexandre; Sugitate, Toru; Suire, Christophe Pierre; Suleymanov, Mais Kazim Oglu; Suljic, Miljenko; Sultanov, Rishat; Sumbera, Michal; Sumowidagdo, Suharyo; Swain, Sagarika; Szabo, Alexander; Szarka, Imrich; Szczepankiewicz, Adam; Szymanski, Maciej Pawel; Tabassam, Uzma; Takahashi, Jun; Tambave, Ganesh Jagannath; Tanaka, Naoto; Tarhini, Mohamad; Tariq, Mohammad; Tarzila, Madalina-Gabriela; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terasaki, Kohei; Terrevoli, Cristina; Teyssier, Boris; Thaeder, Jochen Mathias; Thakur, Dhananjaya; Thomas, Deepa; Tieulent, Raphael Noel; Tikhonov, Anatoly; Timmins, Anthony Robert; Toia, Alberica; Trogolo, Stefano; Trombetta, Giuseppe; Trubnikov, Victor; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ullaland, Kjetil; Uras, Antonio; Usai, Gianluca; Utrobicic, Antonija; Vala, Martin; Valencia Palomo, Lizardo; Van Der Maarel, Jasper; Van Hoorne, Jacobus Willem; Van Leeuwen, Marco; Vanat, Tomas; Vande Vyvre, Pierre; Varga, Dezso; Diozcora Vargas Trevino, Aurora; Vargyas, Marton; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vauthier, Astrid; Vazquez Doce, Oton; Vechernin, Vladimir; Veen, Annelies Marianne; Velure, Arild; Vercellin, Ermanno; Vergara Limon, Sergio; Vernet, Renaud; Vickovic, Linda; Viinikainen, Jussi Samuli; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Villatoro Tello, Abraham; Vinogradov, Alexander; Vinogradov, Leonid; Virgili, Tiziano; Vislavicius, Vytautas; Viyogi, Yogendra; Vodopyanov, Alexander; Volkl, Martin Andreas; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; Von Haller, Barthelemy; Vorobyev, Ivan; Vranic, Danilo; Vrlakova, Janka; Vulpescu, Bogdan; Wagner, Boris; Wagner, Jan; Wang, Hongkai; Wang, Mengliang; Watanabe, Daisuke; Watanabe, Yosuke; Weber, Michael; Weber, Steffen Georg; Weiser, Dennis Franz; Wessels, Johannes Peter; Westerhoff, Uwe; Whitehead, Andile Mothegi; Wiechula, Jens; Wikne, Jon; Wilk, Grzegorz Andrzej; Wilkinson, Jeremy John; Willems, Guido Alexander; Williams, Crispin; Windelband, Bernd Stefan; Winn, Michael Andreas; Yalcin, Serpil; Yang, Ping; Yano, Satoshi; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-Kwon; Yoon, Jin Hee; Yurchenko, Volodymyr; Zaborowska, Anna; Zaccolo, Valentina; Zaman, Ali; Zampolli, Chiara; Correia Zanoli, Henrique Jose; Zaporozhets, Sergey; Zardoshti, Nima; Zarochentsev, Andrey; Zavada, Petr; Zavyalov, Nikolay; Zbroszczyk, Hanna Paulina; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhang, Yonghong; Chunhui, Zhang; Zhang, Zuman; Zhao, Chengxin; Zhigareva, Natalia; Zhou, Daicui; Zhou, You; Zhou, Zhuo; Zhu, Hongsheng; Zhu, Jianhui; Zichichi, Antonino; Zimmermann, Alice; Zimmermann, Markus Bernhard; Zinovjev, Gennady; Zyzak, Maksym

2017-01-01

At sufficiently high temperature and energy density, nuclear matter undergoes a transition to a phase in which quarks and gluons are not confined: the quark–gluon plasma (QGP). Such an exotic state of strongly interacting quantum chromodynamics matter is produced in the laboratory in heavy nuclei high-energy collisions, where an enhanced production of strange hadrons is observed. Strangeness enhancement, originally proposed as a signature of QGP formation in nuclear collisions, is more pronounced for multi-strange baryons. Several effects typical of heavy-ion phenomenology have been observed in high-multiplicity proton–proton (pp) collisions, but the enhanced production of multi-strange particles has not been reported so far. Here we present the first observation of strangeness enhancement in high-multiplicity proton–proton collisions. We find that the integrated yields of strange and multi-strange particles, relative to pions, increases significantly with the event charged-particle multiplicity. The me...
Formation and disintegration of high-density nuclear matter in heavy-ion collisions

International Nuclear Information System (INIS)

Kitazoe, Yasuhiro; Matsuoka, Kazuo; Sano, Mitsuo

1976-01-01

The formation of high-density nuclear matter which may be expected to be attained in high-energy heavy-ion collisions and the subsequent disintegration of dense matter are investigated by means of the hydrodynamics. Head-on collisions of identical nuclei are considered in the nonrelativistic approximation. The compressed density cannot exceed 4 times of the normal one so long as the freedom of only nucleons is considered, and can become higher than 4 times when other freedoms such as the productions of mesons and also nucleon isobars are additionally taken into account. The angular distributions for ejected particles predominate both forwards and backwards at low collision energies, corresponding to the formation of nuclear density less than 2 times of the normal density and become isotropic at the point of 2 times of the normal one. As the collision energy increases further, lateral ejection is intensified gradually. (auth.)
Universal behavior of charged particle production in heavy ion collisions at RHIC energies

Science.gov (United States)

Steinberg, Peter A.; Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.; Phobos Collaboration

2003-04-01

The PHOBOS experiment at RHIC has measured the multiplicity of primary charged particles as a function of centrality and pseudorapidity in Au+Au collisions at √ SNN = 19.6, 130 and 200 GeV. Two kinds of universal behavior are observed in charged particle production in heavy ion collisions. The first is that forward particle production, over a range of energies, follows a universal limiting curve with a non-trivial centrality dependence. The second arises from comparisons with pp/ overlinepp and e +e - data. / in nuclear collisions at high energy scales with √ s in a similar way as Nch in e +e - collisions and has a very weak centrality dependence. This feature may be related to a reduction in the leading particle effect due to the multiple collisions suffered per participant in heavy ion collisions.
Are High Energy Heavy Ion Collisions similar to a Little Bang, or just a very nice Firework?

Science.gov (United States)

Shuryak, E. V.

2001-09-01

The talk is a brief overview of recent progress in heavy ion physics, with emphasis on applications of macroscopic approaches. The central issues are whether the systems exhibit macroscopic behavior we need in order to interpret it as excited hadronic matter, and, if so, what is its effective Equation of State (EoS). This, in turn, depends on the collision rate in matter: we think we understand in hadronic matter near freeze-out, but certainly not at earlier stages of the collisions. Still (and this is about the most important statement we make) there is no indication that it is not high enough, so that a hydro description of excited matter be possible. More specifically, we concentrate on such properties of the produced excited system as collective flow, particle composition and fluctuations. Note that both a generation of a pressure and the rate of fluctuation relaxation are ultimately a measure of a collision rate we would like to know. We also try to explain what exactly are the expected differences between collisions at AGS/SPS and RHIC energies.
Excitation energy partition in 74Ge + 165Ho collision at energy 8.5 MeV/A

International Nuclear Information System (INIS)

Blocki, J.; Grotowski, K.; Planeta, R.

1990-01-01

The distribution of the excitation energy between both fragments in Heavy Ion Collision has been measured recently for the reaction 74 Ge + 165 Ho at 8.5 MeV/A. One can see from the experimental data a gradual transition from moreless equal partition of the heat for the peripheral collisions (small energy loss) toward equal temperatures in more central collisions (high energy loss). The similar dependence of the heat partition as a function of the energy loss was observed earlier by Vandenbosch et al for the reaction 56 Fe + 238 U at 8.5 MeV/A and by Benton et al for the 56 Fe + 165 Ho for a broad range of energy dissipation. Theoretical calculations leading to the excitation energy division between both fragments have been carried out by Randrup and by Feldmeier. In both calculations the same excitation mechanism was assumed which is the exchange of particles between colliding nuclei. Differences between results are mainly due to the different shape parametrization and calculation of the potential energy. Randrup's results are moving much faster towards equal temperatures limit if one goes to more central collisions. Both models however do not predict the direction of the experimental mass flow for the 56 Fe + 165 Ho system. In the present paper classical dynamical calculations following Feldmeir's approach with some modifications are presented for 74 Ge + 165 Ho system
Impact Parameter Dependence of π"-/π"+ Ratio in Probing the Nuclear Symmetry Energy Using Heavy-Ion Collisions

International Nuclear Information System (INIS)

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

2016-01-01

The impact parameter dependence of π"-/π"+ ratio is examined in heavy-ion collisions at 400 MeV/nucleon within a transport model. It is shown that the sensitivity of π"-/π"+ ratio on symmetry energy shows a transition from central to peripheral collisions; that is, the stiffer symmetry energy leads to a larger π"-/π"+ 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 π"-/π"+ ratio, we found this transition of sensitivity of π"-/π"+ ratio to symmetry energy is mainly from less energetic pions; that is, the softer symmetry energy gets the less energetic pions to form a smaller π"-/π"+ ratio in peripheral collisions while these pions generate a larger π"-/π"+ ratio in central collisions. Undoubtedly, the softer symmetry energy can also lead more energetic pions to form a larger π"-/π"+ ratio in peripheral collisions. Nevertheless, considering that most of pions are insufficiently energetic at this beam energy, we therefore suggest the π"-/π"+ ratio as a probe of the high-density symmetry energy effective only in central at most to midcentral collisions, thereby avoiding the possible information of low-density symmetry energy carried in π"-/π"+ ratio from peripheral collisions.
Unpolarised and spin-change collisions between He/sup +/ and H at low energies

Energy Technology Data Exchange (ETDEWEB)

Falcon, C; Opradolce, L [Instituto de Astronomia y Fisica del Espacio, Buenos Aires (Argentina); Piacentini, R D

1978-09-14

He/sup +/-H collisions are studied for energies lower than the electron excitation threshold. Unpolarised cross sections having resonances and values greater than 4000 a/sup 2//sub 0/ and spin-change cross sections showing high structures are obtained. Comparisons with the corresponding H-H collision cross sections are displayed. The sensitivity of the cross sections to the potential energy curves is discussed.
Transverse energy distribution, charged particle multiplicities and spectra in 16O-nucleus collisions

International Nuclear Information System (INIS)

Sunier, J.W.

1987-01-01

The HELIOS (High Energy Lepton and Ion Spectrometer) experiment, installed at the CERN Super Proton Synchrotron, proposes to examine in details the physical properties of a state of high energy created in nuclei by ultra-relativistic nucleus-nucleus collisions. It is generally believed that, at high densities or temperatures, a phase transition to a plasma of quark and gluons will occur. The dynamic of the expansion of such a plasma and its subsequent condensation into a hadron gas should markedly affect the composition and momentum distribution of the emerging particles and photons. The HELIOS experimental setup therefore combines 4π calorimetric coverage with measurements of inclusive particle spectra, two particle correlations, low and high mass lepton pairs and photons. The emphasis is placed on transverse energy flow (E/sub T/) measurements with good energy resolution, and the ability to trigger the acquisition of data in a variety of E/sub T/ ranges, thereby selecting the impact parameter or the violence of the collisions. This short note presents HELIOS results, for the most part still preliminary, on 16 O-nucleus collisions at the incident energies of 60 and 200 GeV per nucleon. The E/sub T/ distributions from Al, Ag and W targets are discussed and compared to the associated charged particle multiplicities from W. Charged particle and (converted) photon spectra measured with the external magnetic spectrometer are compared for 16 O + W and p + W collisions at 200 GeV per nucleon. 5 refs., 7 figs
Multiparticle Collectivity from Initial State Correlations in High Energy Proton-Nucleus Collisions

Science.gov (United States)

Dusling, Kevin; Mace, Mark; Venugopalan, Raju

2018-01-01

Qualitative features of multiparticle correlations in light-heavy ion (p +A ) collisions at RHIC and LHC are reproduced in a simple initial state model of partons in the projectile coherently scattering off localized domains of color charge in the heavy nuclear target. These include (i) the ordering of the magnitudes of the azimuthal angle n th Fourier harmonics of two-particle correlations vn{2 }, (ii) the energy and transverse momentum dependence of the four-particle Fourier harmonic v2{4 }, and (iii) the energy dependence of four-particle symmetric cumulants measuring correlations between different Fourier harmonics. Similar patterns are seen in an Abelian version of the model, where we observe v2{2 }>v2{4 }≈v2{6 }≈v2{8 } of two, four, six, and eight particle correlations. While such patterns are often interpreted as signatures of collectivity arising from hydrodynamic flow, our results provide an alternative description of the multiparticle correlations seen in p +A collisions.
Nuclear reactions induced by high-energy alpha particles

Science.gov (United States)

Shen, B. S. P.

1974-01-01

Experimental and theoretical studies of nuclear reactions induced by high energy protons and heavier ions are included. Fundamental data needed in the shielding, dosimetry, and radiobiology of high energy particles produced by accelerators were generated, along with data on cosmic ray interaction with matter. The mechanism of high energy nucleon-nucleus reactions is also examined, especially for light target nuclei of mass number comparable to that of biological tissue.
Effects of temperature in binary-collision simulations of high-energy displacement cascades

International Nuclear Information System (INIS)

Heinisch, H.L.

1981-10-01

Several hundred cascades ranging from 1 to 500 keV were generated using the binary collision code MARLOWE for primary knock-on atoms (PKAs) with randomly chosen directions in both a non-thermal copper lattice and one having atomic displacements representative of room temperature. To simulate the recombination occurring during localized quenching of the highly excited cascade region, an effective spontaneous recombination radius was applied to reduce the number of defect pairs to be consistent with values extracted from resistivity measurements at 4 0 K. At room temperature fewer widely separated pairs are produced, thus the recombination radius is smaller, however, the recombination radii were found to be independent of energy over the entire energy range investigated for both the cold and room temperature cases. The sizes and other features of the point defect distributions were determined as a function of energy. Differences between cold and room temperature cascade dimensions are small. The room temperature cascades tend to have a greater number of distinct damage regions per cascade, with about the same frequency of widely separated subcascades
A panorama of phase transition signals and influence of collision-induced correlations

Energy Technology Data Exchange (ETDEWEB)

Bougault, R. [LPC Caen IN2P3-CNRS/ENSICAEN et Univ., 14 - Caen (France)

2003-07-01

The presented results will show the richness of nuclear heavy-ion physics where data are accumulated as a succession of independent events. The different reaction mechanisms can provide for 39 A.MeV Ta+Au, 40 and 80 A.MeV Au+Au peripheral collisions a set of data almost free of entrance channel effects as well as a set of events where collision-induced correlations can be evidenced. The event selection method will be presented and it will be shown how the entrance channel dynamical effects affect determination of heat capacity through partial energy fluctuation measurements. (author)

A panorama of phase transition signals and influence of collision-induced correlations

International Nuclear Information System (INIS)

Bougault, R.

2003-01-01

The presented results will show the richness of nuclear heavy-ion physics where data are accumulated as a succession of independent events. The different reaction mechanisms can provide for 39 A.MeV Ta+Au, 40 and 80 A.MeV Au+Au peripheral collisions a set of data almost free of entrance channel effects as well as a set of events where collision-induced correlations can be evidenced. The event selection method will be presented and it will be shown how the entrance channel dynamical effects affect determination of heat capacity through partial energy fluctuation measurements. (author)
Dynamical and statistical aspects of intermediate energy heavy ion collisions

International Nuclear Information System (INIS)

Knoll, J.

1987-01-01

The lectures presented deal with three different topics relevant for the discussion of nuclear collisions at medium to high energies. The first lecture concerns a subject of general interest, the description of statistical systems and their dynamics by the concept of missing information. If presents an excellent scope to formulate statistical theories in such a way that they carefully keep track of the known (relevant) information while maximizing the ignorance about the irrelevant, unknown information. The last two lectures deal with quite actual questions of intermediate energy heavy-ion collisions. These are the multi-fragmentation dynamics of highly excited nuclear systems, and the so called subthreshold particle production. All three subjects are self-contained, and can be read without the knowledge about the other ones. (orig.)
System size and energy dependence of jet-induced hadron pair correlation shapes in Cu+Cu and Au+Au collisions at square root sNN=200 and 62.4 GeV.

Science.gov (United States)

Adare, A; Adler, S S; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Al-Jamel, A; Aoki, K; Aphecetche, L; Armendariz, R; Aronson, S H; Asai, J; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Baksay, G; Baksay, L; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bauer, F; Bazilevsky, A; Belikov, S; Bennett, R; Berdnikov, Y; Bickley, A A; Bjorndal, M T; Boissevain, J G; Borel, H; Boyle, K; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Campbell, S; Chai, J-S; Chand, P; Chang, B S; Chang, W C; Charvet, J-L; Chernichenko, S; Chiba, J; Chi, C Y; Chiu, M; Choi, I J; Choudhury, R K; Chujo, T; Chung, P; Churyn, A; Cianciolo, V; Cleven, C R; Cobigo, Y; Cole, B A; Comets, M P; Constantin, P; Csanád, M; Csörgo, T; Cussonneau, J P; Dahms, T; Das, K; David, G; Deák, F; Deaton, M B; Dehmelt, K; Delagrange, H; Denisov, A; d'Enterria, D; Deshpande, A; Desmond, E J; Devismes, A; Dietzsch, O; Dion, A; Donadelli, M; Drachenberg, J L; Drapier, O; Drees, A; Dubey, A K; Durum, A; Dutta, D; Dzhordzhadze, V; Efremenko, Y V; Egdemir, J; Ellinghaus, F; Emam, W S; Enokizono, A; En'yo, H; Espagnon, B; Esumi, S; Eyser, K O; Fields, D E; Finck, C; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Forestier, B; Fox, B D; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fung, S-Y; Fusayasu, T; Gadrat, S; Garishvili, I; Gastineau, F; Germain, M; Glenn, A; Gong, H; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-A; Hachiya, T; Hadj Henni, A; Haegemann, C; Haggerty, J S; Hagiwara, M N; Hamagaki, H; Han, R; Hansen, A G; Harada, H; Hartouni, E P; Haruna, K; Harvey, M; Haslum, E; Hasuko, K; Hayano, R; Heffner, M; Hemmick, T K; Hester, T; Heuser, J M; He, X; Hidas, P; Hiejima, H; Hill, J C; Hobbs, R; Hohlmann, M; Holmes, M; Holzmann, W; Homma, K; Hong, B; Hoover, A; Horaguchi, T; Hornback, D; Hur, M G; Ichihara, T; Ikonnikov, V V; Imai, K; Inaba, M; Inoue, Y; Inuzuka, M; Isenhower, D; Isenhower, L; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Jacak, B V; Jia, J; Jin, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kaneta, M; Kang, J H; Kanou, H; Katou, K; Kawabata, T; Kawagishi, T; Kawall, D; Kazantsev, A V; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D H; Kim, D J; Kim, E; Kim, G-B; Kim, H J; Kim, Y-S; Kinney, E; Kiss, A; Kistenev, E; Kiyomichi, A; Klay, J; Klein-Boesing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Kohara, R; Komkov, B; Konno, M; Kotchetkov, D; Kozlov, A; Král, A; Kravitz, A; Kroon, P J; Kubart, J; Kuberg, C H; Kunde, G J; Kurihara, N; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y-S; Lajoie, J G; Lebedev, A; Le Bornec, Y; Leckey, S; Lee, D M; Lee, M K; Lee, T; Leitch, M J; Leite, M A L; Lenzi, B; Lim, H; Liska, T; Litvinenko, A; Liu, M X; Li, X; Li, X H; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mao, Y; Martinez, G; Masek, L; Masui, H; Matathias, F; Matsumoto, T; McCain, M C; McCumber, M; McGaughey, P L; Miake, Y; Mikes, P; Miki, K; Miller, T E; Milov, A; Mioduszewski, S; Mishra, G C; Mishra, M; Mitchell, J T; Mitrovski, M; Mohanty, A K; Morreale, A; Morrison, D P; Moss, J M; Moukhanova, T V; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagata, Y; Nagle, J L; Naglis, M; Nakagawa, I; Nakamiya, Y; Nakamura, T; Nakano, K; Newby, J; Nguyen, M; Norman, B E; Nyanin, A S; Nystrand, J; O'Brien, E; Oda, S X; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, H; Okada, K; Oka, M; Omiwade, O O; Oskarsson, A; Otterlund, I; Ouchida, M; Oyama, K; Ozawa, K; Pak, R; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Park, W J; Pate, S F; Pei, H; Penev, V; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pierson, A; Pinkenburg, C; Pisani, R P; Purschke, M L; Purwar, A K; Qualls, J M; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Rembeczki, S; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Rykov, V L; Ryu, S S; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakai, S; Sakata, H; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Seele, J; Seidl, R; Semenov, V; Seto, R; Sharma, D; Shea, T K; Shein, I; Shevel, A; Shibata, T-A; Shigaki, K; Shimomura, M; Shohjoh, T; Shoji, K; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, C P; Singh, V; Skutnik, S; Slunecka, M; Smith, W C; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Suire, C; Sullivan, J P; Sziklai, J; Tabaru, T; Takagi, S; Takagui, E M; Taketani, A; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Taranenko, A; Tarján, P; Thomas, T L; Togawa, M; Toia, A; Tojo, J; Tomásek, L; Torii, H; Towell, R S; Tram, V-N; Tserruya, I; Tsuchimoto, Y; Tuli, S K; Tydesjö, H; Tyurin, N; Uam, T J; Vale, C; Valle, H; vanHecke, H W; Velkovska, J; Velkovsky, M; Vertesi, R; Veszprémi, V; Vinogradov, A A; Virius, M; Volkov, M A; Vrba, V; Vznuzdaev, E; Wagner, M; Walker, D; Wang, X R; Watanabe, Y; Wessels, J; White, S N; Willis, N; Winter, D; Wohn, F K; Woody, C L; Wysocki, M; Xie, W; Yamaguchi, Y L; Yanovich, A; Yasin, Z; Ying, J; Yokkaichi, S; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zaudtke, O; Zhang, C; Zhou, S; Zimányi, J; Zolin, L; Zong, X

2007-06-08

We present azimuthal angle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from dijets in Cu+Cu and Au+Au collisions at square root sNN=62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is broadened, non-Gaussian, and peaked away from Delta phi=pi in central and semicentral collisions in all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collision energy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.
Charge transfer and excitation in high-energy ion-atom collisions

International Nuclear Information System (INIS)

Schlachter, A.S.; Berkner, K.H.; McDonald, R.J.

1986-11-01

Coincidence measurements of charge transfer and simultaneous projectile electron excitation provide insight into correlated two-electron processes in energetic ion-atom collisions. Projectile excitation and electron capture can occur simultaneously in a collision of a highly charged ion with a target atom; this process is called resonant transfer and excitation (RTE). The intermediate excited state which is thus formed can subsequently decay by photon emission or by Auger-electron emission. Results are shown for RTE in both the K shell of Ca ions and the L shell of Nb ions, for simultaneous projectile electron loss and excitation, and for the effect of RTE on electron capture
Energy density, stopping and flow in ultrarelativistic heavy ion collisions

International Nuclear Information System (INIS)

Sorge, H.; von Keitz, A.; Mattiello, R.; Stoecker, H.; Greiner, W.

1990-01-01

The Lorentz invariant molecular dynamics approach (RQMD) is employed to investigate the space-time evolution of heavy ion collisions at energies (E kin = 10AGeV hor-ellipsis 200AGeV). The calculations for various nucleus nucleus reactions show a high degree of stopping power. The importance of secondary rescattering at these beam energies is demonstrated. The computed nucleon rapidity distributions are compared to available experimental data. It is demonstrated that nonlinear, collective effects like full stopping of target and projectile and matter flow could be expected for heavy projectiles only. For nuclear collisions in the Booster era at BNL and for the lead beam at CERN SPS the authors predict a stimulating future: then a nearly equilibrated, long lived (8 fm/c) macroscopic volume of very high energy density (> 1 GeV/fm 3 ) and baryon density (> 5 times ground state density) is produced
Performance Limitations in High-Energy Ion Colliders

CERN Document Server

Fischer, Wolfram

2005-01-01

High-energy ion colliders (hadron colliders operating with species other than protons) are premier research tools for nuclear physics. The collision energy and high luminosity are important design and operations considerations. However, the experiments also expect flexibility with frequent changes in the collision energy, lattice configuration, and ion species, including asymmetric collisions. For the creation, acceleration, and storage of bright intense ion beams, attention must be paid to space charge, charge exchange, and intra-beam scattering effects. The latter leads to luminosity lifetimes of only a few hours for heavy ions. Ultimately cooling at full energy is needed to overcome this effect. Currently, the Relativistic Heavy Ion Collider at BNL is the only operating high-energy ion collider. The Large Hadron Collider, under construction at CERN, will also run with heavy ions.
Introduction to high-energy heavy-ion collisions

CERN Document Server

Wong, Cheuk-Yin

1994-01-01

Written primarily for researchers and graduate students who are new in this emerging field, this book develops the necessary tools so that readers can follow the latest advances in this subject. Readers are first guided to examine the basic informations on nucleon-nucleon collisions and the use of the nucleus as an arena to study the interaction of one nucleon with another. A good survey of the relation between nucleon-nucleon and nucleus-nucleus collisions provides the proper comparison to study phenomena involving the more exotic quark-gluon plasma. Properties of the quark-gluon plasma and s
Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse

Energy Technology Data Exchange (ETDEWEB)

Grishkov, V. E.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

2017-03-15

Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron–ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.
Radio-Frequency Emissions from Streamer Collisions: Implications for High-Energy Processes.

Science.gov (United States)

Luque, A.

2017-12-01

The production of energetic particles in a discharge corona is possibly linked to the collision of streamers of opposite polarities [Cooray et al. (2009), Kochkin et al. (2012), Østgaard et al. (2016)]. There is also experimental evidence linking it to radio-frequency emissions in the UHF frequency range (300 MHz-3 GHz) [Montanyà et al. (2015), Petersen and Beasley (2014)]. Here we investigate these two links by modeling the radio-frequency emissions emanating from an encounter between two counter-propagating streamers. Our numerical model combines self-consistently a conservative, high-order Finite-Volume scheme for electron transport with a Finite-Difference Time-Domain (FDTD) method for electromagnetic propagation. We also include the most relevant reactions for streamer propagation: impact ionization, dissociative attachment and photo-ionization. Our implementation benefits from massive parallelization by running on a General-Purpose Graphical Processing Unit (GPGPU). With this code we found that streamer encounters emit electromagnetic waves predominantly in the UHF range, supporting the hypothesis that streamer collisions are essential precursors of high-energy processes in electric discharges. References Cooray, V., et al., J. Atm. Sol.-Terr. Phys., 71, 1890, doi:10.1016/j.jastp.2009.07.010 (2009). Kochkin, P. O., et al., J. Phys. D, 45, 425202, doi: 10.1088/0022-3727/45/42/425202 (2012). Montanyà, J., et al., J. Atm. Sol.-Terr. Phys., 136, 94, doi:10.1016/j.jastp.2015.06.009, (2015). Østgaard, N., et al., J. Geophys. Res. (Atmos.), 121, 2939, doi:10.1002/2015JD024394 (2016). Petersen, D., and W. Beasley, Atmospheric Research, 135, 314, doi:10.1016/j.atmosres.2013.02.006 (2014).
Peripheral collisions of heavy ions induced by 40Ar at intermediate energies: giant resonance high energy structures and projectile fragmentation

International Nuclear Information System (INIS)

Blumenfeld, Y.

1987-09-01

The results obtained in similar studies at low incident energies are first of all reviewed. The time of flight spectrometer built for the experiments is then described. A study of the properties of the projectile-like fragments shows numerous deviations from the relativistic energy fragmentation model. Evidence for a strong surface transfer reaction component is given and the persistence of mean field effects at intermediate energies is stressed. A calculation of the contribution of the transfer evaporation mechanism to the inelastic spectra shows that this mechanism is responible for the major part of the background measured at high excitation energy and can in some cases induce narrow structures in the spectra. The inelastic spectra shows a strong excitation of the giant quadrupole resonance. In the region between 20 and 80 MeV excitation energy narrow structures are present for all the studied systems. Statistical and Fourier analysises allow to quantify the probabilities of existence, the widths and the excitation energies of these structures. A transfer evaporation hypothesis cannot consistently reproduce all the observed structures. The excitation energies of the structures can be well described by phenomenological laws where the energies are proportional to the -1/3 power of the target mass. Complete calculations of the excitation probabilities of giant resonances and multiphonon states are performed within a model where the nuclear excitation are calculated microscopically in the Random Phase Approximation. It is shown that a possible interpretation of the structures is the excitation of multiphonon states built with 2 + giant resonances [fr
Microscopic classical equations of motion calculations of high-energy heavy-ion collisions

International Nuclear Information System (INIS)

Panos, C.N.

1979-01-01

Classical microscopic nonrelativistic calculations are made for collisions between equal-mass-nuclei projectile and target with A/sub P/ = A/sub T/ = 20 for laboratory energies E/sub L/ = 117, 400, and 800 MeV/A/sub P/ and also between nuclei with A/sub P/ = A/sub T/ = 40 for E/sub L/ = 400 MeV/A/sub P/. For a given initial configuration of the projectile and target nucleons the trajectories of all nucleons are calculated classically with two-body forces between all pairs of nucleons. The implementation of the CEOM calculations is discussed in detail. More limited relativistic calculations for single initial configurations are also made. The configurations representing the initial nuclei are chosen to have a reasonable radius and kinetic energy; however, they do not saturate with the two-body potentials used. The trajectory information is analyzed to give a large number of position and momentum dependent quantities such as densities, rapidity distributions, inclusive double differential cross sections, etc. The results show that a central collision (b = 0) proceeds in three stages, an initial transparent stage, a strongly interacting stage where the dissipation is large, and finally an expansion stage for which there is considerable dissipation. Appreciable potential energy effects were found for b = 0; however, the final distributions were very similar for the scattering equivalent potentials. For lower energies (E/sub L/ approx. = 100 MeV) there is some evidence of fusion into large fragments. The thermal models for b = 0 are tested. Noncentral collisions show typical nonequilibrium and transparency features. The multiplicity distribution is obtained for A/sub P/ = A/sub T/ = 20 and E/sub L/ = 800 MeV. A comparison of the impact parameter-integrated inclusive double differential cross sections is made with the experimental data for A/sub P/ = A/sub T/ = 20, E/sub L/ = 800 MeV and shows fair agreement
Probing medium-induced jet splitting and energy loss in heavy-ion collisions

Science.gov (United States)

Chang, Ning-Bo; Cao, Shanshan; Qin, Guang-You

2018-06-01

The nuclear modification of jet splitting in relativistic heavy-ion collisions at RHIC and the LHC energies is studied based on the higher twist formalism. Assuming coherent energy loss for the two splitted subjets, a non-monotonic jet energy dependence is found for the nuclear modification of jet splitting function: strongest modification at intermediate jet energies whereas weaker modification for larger or smaller jet energies. Combined with the smaller size and lower density of the QGP medium at RHIC than at the LHC, this helps to understand the groomed jet measurements from CMS and STAR Collaborations: strong modification of the momentum sharing zg distribution at the LHC and no obvious modification of zg distribution at RHIC. In addition, the observed nuclear modification pattern of the groomed jet zg distribution cannot be explained solely by independent energy loss of the two subjets. Our result may be tested in future measurements of groomed jets with lower jet energies at the LHC and larger jet energies at RHIC, for different angular separations between the two subjets.
On the global ship hull bending energy in ship collisions

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Li, Yujie

2009-01-01

During ship collisions part of the kinetic energy of the involved vessels immediately prior to contact is absorbed as energy dissipated by crushing of the hull structures, by friction and by elastic energy. The purpose of this report is to present an estimate of the elastic energy that can...... be stored in elastic hull vibrations during a ship collision. When a ship side is strengthened in order to improve the crashworthiness it has been argued in the scientific literature that a non-trivial part of the energy released for structural deformation during the collision can be absorbed as elastic...... energy in global ship hull vibrations, such that with strong ship sides less energy has to be spent in crushing of the striking ship bow and/or the struck ship side. In normal ship–ship collision analyses both the striking and struck ship are usually considered as rigid bodies where structural crushing...
Energy independent scaling of the ridge and final state description of high multiplicity p +p collisions at √{s }=7 and 13 TeV

Science.gov (United States)

Sarkar, Debojit

2018-02-01

An energy independent scaling of the near-side ridge yield at a given multiplicity has been observed by the ATLAS and the CMS collaborations in p +p collisions at √{s }=7 and 13 TeV. Such a striking feature of the data can be successfully explained by approaches based on initial state momentum space correlation generated due to gluon saturation. In this paper, we try to examine if such a scaling is also an inherent feature of the approaches that employ strong final state interaction in p +p collisions. We find that hydrodynamical modeling of p +p collisions using EPOS 3 shows a violation of such scaling. The current study can, therefore, provide important new insights on the origin of long-range azimuthal correlations in high multiplicity p +p collisions at the LHC energies.
Collision-induced dissociation of diatomic ions

International Nuclear Information System (INIS)

Los, J.; Govers, T.R.

1978-01-01

An attempt is made to illustrate how mass spectrometric studies of dissociation in diatomic molecular ions can provide information on the dynamics of these collisions and on the predissociative states involved. Restriction is made to primary beam energies of the order of at least keV. The review covers the dynamics of dissociation, experimental techniques, direct dissociation in heavy-particle collisions, and translational spectroscopy. 120 references
HARD PARTON PHYSICS IN HIGH ENERGY NUCLEAR COLLISIONS. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, VOLUME 17

Energy Technology Data Exchange (ETDEWEB)

CARROLL,J.

1999-09-10

The RIKEN-BNL center workshop on ''Hard parton physics in high energy nuclear collisions'' was held at BNL from March 1st-5th! 1999. The focus of the workshop was on hard probes of nucleus-nucleus collisions that will be measured at RHIC with the PHENIX and STAR detectors. There were about 45 speakers and over 70 registered participants at the workshop, with roughly a quarter of the speakers from overseas. About 60% of the talks were theory talks. A nice overview of theory for RHIC was provided by George Sterman. The theoretical talks were on a wide range of topics in QCD which can be classified under the following: (a) energy loss and the Landau-Pomeranchuk-Migdal effect; (b) minijet production and equilibration; (c) small x physics and initial conditions; (d) nuclear parton distributions and shadowing; (e) spin physics; (f) photon, di-lepton, and charm production; and (g) hadronization, and simulations of high pt physics in event generators. Several of the experimental talks discussed the capabilities of the PHENIX and STAR detectors at RHIC in measuring high pt particles in heavy ion collisions. In general, these talks were included in the relevant theory sessions. A session was set aside to discuss the spin program at RHIC with polarized proton beams. In addition, there were speakers from 08, HERA, the fixed target experiments at Fermilab, and the CERN fixed target Pb+Pb program, who provided additional perspective on a range of issues of relevance to RHIC; from jets at the Tevatron, to saturation of parton distributions at HERA, and recent puzzling data on direct photon production in fixed target experiments, among others.
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
Collision-Induced Infrared Absorption by Molecular Hydrogen Pairs at Thousands of Kelvin

Directory of Open Access Journals (Sweden)

Xiaoping Li

2010-01-01

Full Text Available Collision-induced absorption by hydrogen and helium in the stellar atmospheres of cool white dwarfs causes the emission spectra to differ significantly from the expected blackbody spectra of the cores. For detailed modeling of radiative processes at temperatures up to 7000 K, the existing H2–H2 induced dipole and potential energy surfaces of high quality must be supplemented by calculations with the H2 bonds stretched or compressed far from the equilibrium length. In this work, we describe new dipole and energy surfaces, based on more than 20 000 ab initio calculations for H2–H2. Our results agree well with previous ab initio work (where those data exist; the calculated rototranslational absorption spectrum at 297.5 K matches experiment similarly well. We further report the calculated absorption spectra of H2–H2 for frequencies from the far infrared to 20 000 cm−1, at temperatures of 600 K, 1000 K, and 2000 K, for which there are no experimental data.
High energy hadron scattering

International Nuclear Information System (INIS)

Johnson, R.C.

1980-01-01

High energy and small momentum transfer 2 'yields' 2 hadronic scattering processes are described in the physical framework of particle exchange. Particle production in high energy collisions is considered with emphasis on the features of inclusive reactions though with some remarks on exclusive processes. (U.K.)
On the Global Ship Hull Bending Energy in Ship Collisions

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Li, Y.

2004-01-01

During ship collisions part of the kinetic energy of the involved vessels prior to contact is absorbed as energy dissipated by crushing of the hull structures, by friction and by elastic energy. The purpose of this report is to present an estimate of the elastic energy that can be stored in elastic...... hull vibrations during a ship collision. When a ship side is strengthened in order to improve the crashworthiness it has been argued in the scientific literature that a non trivial part of the energy released for structural deformation during the collision can be absorbed as elastic energy in global...... ship hull vibrations, such that with strong ship sides less energy has to be spent in crushing of the striking ship bow and/or the struck ship side. In normal ship-ship collision analyses both the striking and struck ship are usually considered as rigid bodies where structural crushing is confined...

Quarkonium production in high energyproton-proton and proton-nucleus collisions

Energy Technology Data Exchange (ETDEWEB)

del Valle, Z C; Corcella, G; Fleuret, F; Ferreiro, E G; Kartvelishvili, V; Kopeliovich, B; Lansberg, J P; Lourenco, C; Martinez, G; Papadimitriou, V; Satz, H; Scomparin, E; Ullrich, T; Teryaev, O; Vogt, R; Wang, J X

2011-03-14

We present a brief overview of the most relevant current issues related to quarkonium production in high energy proton-proton and proton-nucleus collisions along with some perspectives. After reviewing recent experimental and theoretical results on quarkonium production in pp and pA collisions, we discuss the emerging field of polarization studies. Afterwards, we report on issues related to heavy-quark production, both in pp and pA collisions, complemented by AA collisions. To put the work in broader perpectives, we emphasize the need for new observables to investigate the quarkonium production mechanisms and reiterate the qualities that make quarkonia a unique tool for many investigations in particle and nuclear physics.
Reaction mechanisms in collisions induced by $^{8}$B beam close to the barrier

CERN Multimedia

The aim of the proposed experiment is to investigate the reaction dynamics of proton-halo induced collisions at energies around the Coulomb barrier where coupling to continuum effects are expected to be important. We propose to measure the $^{8}$B + $^{64}$Zn elastic scattering angular distribution together with the measurement, for the first time, of p - $^{7}$Be coincidences coming from transfer and/or break-up of $^{8}$B. The latter will allow a better understanding of the relative contribution of elastic $\\textit{vs}$ non-elastic break-up in reactions induced by extremely weakly-bound nuclei. We believe that with the availability of the post accelerated $^{8}$B beam at REX-ISOLDE we will be able to collect for the first time high quality data for the study of such an important topic.
High energy nuclear collisions: Theory overview

Energy Technology Data Exchange (ETDEWEB)

Fries, R.J.

2010-08-01

We review some basic concepts of relativistic heavy-ion physics and discuss our understanding of some key results from the experimental program at the relativistic heavy-ion collider (RHIC). We focus in particular on the early time dynamics of nuclear collisions, some result from lattice QCD, hard probes and photons.
Deviation from normal Boltzmann distribution of high-lying energy levels of iron atom excited by Okamoto-cavity microwave-induced plasmas using pure nitrogen and nitrogen–oxygen gases

International Nuclear Information System (INIS)

Wagatsuma, Kazuaki

2015-01-01

This paper describes several interesting excitation phenomena occurring in a microwave-induced plasma (MIP) excited with Okamoto-cavity, especially when a small amount of oxygen was mixed with nitrogen matrix in the composition of the plasma gas. An ion-to-atom ratio of iron, which was estimated from the intensity ratio of ion to atomic lines having almost the same excitation energy, was reduced by adding oxygen gas to the nitrogen MIP, eventually contributing to an enhancement in the emission intensities of the atomic lines. Furthermore, Boltzmann plots for iron atomic lines were observed in a wide range of the excitation energy from 3.4 to 6.9 eV, indicating that plots of the atomic lines having lower excitation energies (3.4 to 4.8 eV) were well fitted on a straight line while those having more than 5.5 eV deviated upwards from the linear relationship. This overpopulation would result from any other excitation process in addition to the thermal excitation that principally determines the Boltzmann distribution. A Penning-type collision with excited species of nitrogen molecules probably explains this additional excitation mechanism, in which the resulting iron ions recombine with captured electrons, followed by cascade de-excitations between closely-spaced excited levels just below the ionization limit. As a result, these high-lying levels might be more populated than the low-lying levels of iron atom. The ionization of iron would be caused less actively in the nitrogen–oxygen plasma than in a pure nitrogen plasma, because excited species of nitrogen molecule, which can provide the ionization energy in a collision with iron atom, are consumed through collisions with oxygen molecules to cause their dissociation. It was also observed that the overpopulation occurred to a lesser extent when oxygen gas was added to the nitrogen plasma. The reason for this was also attributed to decreased number density of the excited nitrogen species due to collisions with oxygen
Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC.

Science.gov (United States)

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

2014-08-01

Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies.
Beam-Energy Dependence of Charge Separation along the Magnetic Field in Au +Au Collisions at RHIC

Science.gov (United States)

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

2014-08-01

Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au +Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies.
Calculation of Direct photon production in nuclear collisions

CERN Document Server

Cepila, J

2012-01-01

Prompt photons produced in a hard reaction are not expected to be accompanied by any final state interaction, either energy loss or absorption and one should not expect any nuclear effects at high pT . However, data from the PHENIX experiment indicates large-pT suppression in d+Au and central Au+Au collisions that cannot be accompanied by coherent phenomena. We propose a mechanism based on the energy sharing problem at large pT near the kinematic limit that is induced by multiple initial state interactions and that improves the agreement of calculations with PHENIX data. We calculate inclusive direct photon production cross sections in p+p collisions at RHIC and LHC energies using the color dipole approach without any additional parameter. Our predictions are in good agreement with the available data. Within the same framework, we calculate direct photon production rates in d+A and A+A collisions at RHIC energy. We also provide predictions for the same process in p+A collisions at LHC energy. Since the kinema...
How does the Quark-Gluon Plasma know the collision energy?

Science.gov (United States)

McInnes, Brett

2018-02-01

Heavy ion collisions at the LHC facility generate a Quark-Gluon Plasma (QGP) which, for central collisions, has a higher energy density and temperature than the plasma generated in central collisions at the RHIC. But sufficiently peripheral LHC collisions give rise to plasmas which have the same energy density and temperature as the "central" RHIC plasmas. One might assume that the two versions of the QGP would have very similar properties (for example, with regard to jet quenching), but recent investigations have suggested that they do not: the plasma "knows" that the overall collision energy is different in the two cases. We argue, using a gauge-gravity analysis, that the strong magnetic fields arising in one case (peripheral collisions), but not the other, may be relevant here. If the residual magnetic field in peripheral LHC plasmas is of the order of at least eB ≈ 5mπ2, then the model predicts modifications of the relevant quenching parameter which approach those recently reported.
High-energy collisions of particles, strings, and branes

CERN Document Server

Veneziano, Gabriele

2015-01-01

This chapter summarizes some 25 years of work on the transplanckian-energy collisions of particles, strings, and branes, seen as a theoretical laboratory for understanding how gravity and quantum mechanics can be consistently combined in string theory. The ultimate aim of the exercise is to understand whether and how a consistent quantization of gravity can solve some longstanding paradoxes, such as the apparent loss of information in the production and decay of black holes at a semiclassical level. Considerable progress has been made in understanding the emergence of General Relativity expectations and in evaluating several kinds of quantum string corrections to them in the weak-gravity regime while keeping unitarity manifest. While some progress has also been made in the strong-gravity/gravitational collapse domain, full control of how unitarity works in that regime is still lacking.
Transverse energy production in high energy nuclear collisions and the equation of state of nuclear matter

International Nuclear Information System (INIS)

Doss, K.G.R.; Gustafsson, H.A.; Gutbrod, H.H.; Kolb, B.; Ludewigt, B.; Poskanzer, A.M.; Ritter, H.G.; Schmidt, H.R.; Lawrence Berkeley Lab., CA; Kampert, K.H.; Loehner, H.

1987-08-01

In nuclear collisions of AU+Au, Nb+Nb and Ca+Ca at bombarding energies between 150 and 800 MeV per nucleon transverse energy and transverse momenta of light particles are studied event by event at θ = 90 0 in the center of mass system. At all energies a rise of the mean transverse energy per nucleon is observed with increasing charged particle multiplicity. Particularly large values of E perpendicular to have been found for 3 He-fragments. The hydrodynamical picture is discussed for a possible separation of the collective flow and the thermal parts of the E perpendicular to -spectrum. From this, evidence for a rather stiff equation of state is found. (orig.)
Evolution of pressures and correlations in the glasma produced in high energy nuclear collisions

Science.gov (United States)

Ruggieri, M.; Liu, J. H.; Oliva, L.; Peng, G. X.; Greco, V.

2018-04-01

We consider the SU(2) glasma with Gaussian fluctuations and study its evolution by means of classical Yang-Mills equations solved numerically on a lattice. Neglecting in this first study the longitudinal expansion, we follow the evolution of the pressures of the system and compute the effect of the fluctuations in the early stage up to t ≈2 fm /c , that is the time range in which the glasma is relevant for high energy collisions. We measure the ratio of the longitudinal over the transverse pressure, PL/PT, and we find that unless the fluctuations carry a substantial amount of the energy density at the initial time, they do not change significantly the evolution of PL/PT in the early stage and that the system remains quite anisotropic. We also measure the longitudinal fields correlators both in the transverse plane and along the longitudinal direction: while at initial time fields appear to be anticorrelated in the transverse plane, this anticorrelation disappears in the very early stage, and the correlation length in the transverse plane increases. On the other hand, we find a dependence of the gauge invariant correlator on the longitudinal coordinate, which we interpret as a partial loss of correlation induced by the dynamics that we dub the gauge invariant string breaking. We finally study the effect of fluctuations on the longitudinal correlations: we find that string breaking is accelerated by the fluctuations and waiting for a sufficiently long time fluctuations lead to the complete breaking of the color strings.
Some comments on the behaviour of the excited nuclear matter formed in nuclear collisions at high energies

International Nuclear Information System (INIS)

Besliu, Calin; Jipa, Alexandru; Argintaru, Dan

2003-01-01

In the last years many experiments have been performed in different laboratories to investigate the behaviour of the nuclear matter formed in nuclear collisions at high energies. Therefore, many experimental results are available at present. For explaining these experimental results a lot of models have been proposed. A very large number of concepts have been used. Taking into account some own experimental results obtained in proton-nucleus and nucleus-nucleus collisions at energies between a few A GeV and a few hundred A GeV we comments in the frame a phenomenological geometric picture the main experimental results on charged particle multiplicities, participants, cross sections, momentum spectra, temperature slopes, nuclear matter flow, size and structure of the participant regions, antiparticle to particle ratios and chemical potential. Some jumps in the dependencies of some interesting physical quantities on the available energies in the centre of mass system can be reported. Trends to behaviours like-saturation of some physical quantities are observed, too. Therefore, some connections with the possible phase transitions in nuclear matter are included. A few specific signals of different phase transitions in nuclear matter are suggested. (authors)
Mechanical Energy Changes in Perfectly Inelastic Collisions

Science.gov (United States)

Mungan, Carl E.

2013-01-01

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

International Nuclear Information System (INIS)

Lestinsky, M.

2007-01-01

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 18+ yield a high-precision measurement of the 2s-2p 3/2 transition energy in this system. Operation of the two-electron-beam setup at high collision energy (∼1000 eV) is established using resonances of hydrogenlike Mg 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 6+ . (orig.)
Identification of very low energy projectile autoionizing transitions in high velocity collisions using zero-degree Auger electron spectroscopy

International Nuclear Information System (INIS)

Zouros, T.J.M.; Liao, C.; Montenegro, E.C.; Hagmann, S.; Richard, P.; Grabbe, S.; Bhalla, C.P.; Wong, K.L.

1995-01-01

The unusual looking ''mesa''-shaped cusp observed in O 3+ collisions with He [N. Stolterfoht et al., Proc. 2nd US-Mexico Symp. on Atomic and Molecular Phy. eds. A. Cisneros and T. Morgan (Instituto de Fysica, Cuernavaca, Mexico, 1986) p. 51.], has been investigated using zero-degree electron spectroscopy, in both high resolution singles measurements and lower resolution electron-projectile coincidence measurements at 10, 15 and 23 MeV. The high resolution studies indicate the ''mesa'' peak to be actually composed of primarily two (other than the cusp) very strong autoionizing peaks corresponding to energies of 60 and 100 meV in the emitter frame. The coincidence studies, indicate these lines to originate from excitation of the O 3+ ion followed by autoionization. Ongoing Hartree-Fock-Slater calculations, severely tested at these extremely small transition energies, indicate that these lines can indeed result from the autoionization of t he O 3+ (1s 2 2s2p5l) Rydberg states produced during the collision. Furthermore, the unusually sharp edges of these lines giving rise to the characteristic ''mesa''-shape look, can be explained in terms of the kinematic constraints imposed by the energy and angular acceptance range of the spectrometer. (orig.)
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)
Central collisions in intermediate energy heavy-ion reactions

International Nuclear Information System (INIS)

Wong, C.Y.

1979-01-01

The critical collisions in intermediate energy heavy-ion reactions are examined from both a microscopic and macroscopic viewpoint. In the microscopic description the proper tool is the extended TDHF approximation involving both the mean field and the particle collisions. To understand the underlying physics, the effect of the mean field and the effect of particle collisions are studied separately. It is found that th sudden increase in the density of the overlapping region can cause the volcano effect, leading to the complete disintegration of one of the nuclei. The self-consistent mean field also gives rise to the bunching instability when the two Fermi spheres of the colliding nucleons separate. The collision between nucleons, on the other hand, leads to irreversible dissipation, thermalization, and the possibility of a hydrodynamical description of the dynamics. Next is studied the dynamics of central collisions using the hydrodynamical description for many combinations of targets and projectiles at different energies. The formation of shock waves, sidesplash, and the complete disintegration of the whole nucleus are examined. Nuclear viscosity is found to affect the angular distribution of the reaction products and also the maximum compression ratio achieved during the collision. 28 references
Heavy-flavor production and medium properties in high-energy nuclear collisions. What next?

Energy Technology Data Exchange (ETDEWEB)

Aarts, G.; Allton, C. [Swansea University, Swansea (United Kingdom); Aichelin, J.; Gossiaux, P.B.; Nahrgang, M. [Universite de Nantes, SUBATECH, Ecole des Mines de Nantes, Nantes (France); Arnaldi, R.; Scomparin, E. [INFN, Sezione di Torino, Torino (Italy); Bass, S.A. [Duke University, Durham, NC (United States); Bedda, C.; Grelli, A.; Trzeciak, B.; Doremalen, L. van; Vermunt, L.; Vigolo, S. [Utrecht University, Institute for Subatomic Physics, Utrecht (Netherlands); Brambilla, N. [Technische Universitaet Muenchen, Physik-Department and Excellence Cluster Universe, Garching (Germany); Technische Universitaet Muenchen, Institute for Advanced Study, Munich (Germany); Bratkovskaya, E. [GSI Helmholtzzentrum fuer Schwerionenforschung, Research Division and ExtreMe Matter Institute EMMI, Darmstadt (Germany); Frankfurt University, Institute for Theoretical Physics, Frankfurt am Main (Germany); Braun-Munzinger, P. [GSI Helmholtzzentrum fuer Schwerionenforschung, Research Division and ExtreMe Matter Institute EMMI, Darmstadt (Germany); Ruprecht-Karls-Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Bruno, G.E. [Dipartimento di Fisica and INFN, Bari (Italy); European Organization for Nuclear Research, Geneva (Switzerland); Dahms, T. [Technische Universitaet Muenchen, Physik-Department and Excellence Cluster Universe, Garching (Germany); Das, S.K. [University of Catania, Catania (Italy); Dembinski, H.; Schmelling, M. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Djordjevic, M. [University of Belgrade, Institute of Physics, Belgrade (Serbia); Ferreiro, E. [Universidad de Santiago de Compostela, Santiago de Compostela (Spain); Frawley, A. [Florida State University, Tallahassee, FL (United States); Granier de Cassagnac, R.; Jo, M.; Nguyen, M. [Ecole Polytechnique, Laboratoire Leprince-Ringuet, Palaiseau (France); He, M. [Nanjing University of Science and Technology, Department of Applied Physics, Nanjing (China); Horowitz, W.A. [University of Cape Town, Department of Physics, Rondebosch (South Africa); Innocenti, G.M. [Massachusetts Institute of Technology, Cambridge, MA (United States); Kaczmarek, O. [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan (China); University of Bielefeld, Bielefeld (Germany); Kuijer, P.G. [National Institute for Subatomic Physics, Amsterdam (Netherlands); Laine, M. [University of Bern, AEC, Institute for Theoretical Physics, Bern (Switzerland); Lombardo, M.P. [INFN - Laboratori Nazionali di Frascati, Frascati (Italy); Mischke, A. [Utrecht University, Institute for Subatomic Physics, Utrecht (Netherlands); National Institute for Subatomic Physics, Amsterdam (Netherlands); Munhoz, M.G.; Suaide, A.A.P. [Universidade de Sao Paulo (USP), Sao Paulo (Brazil); Oliveira da Silva, A.C.; Zanoli, H.J.C. [Utrecht University, Institute for Subatomic Physics, Utrecht (Netherlands); Universidade de Sao Paulo (USP), Sao Paulo (Brazil); Petreczky, P. [Brookhaven National Laboratory, Upton, NY (United States); Rothkopf, A. [Ruprecht-Karls-Universitaet Heidelberg, Institute for Theoretical Physics, Heidelberg (Germany); Song, T. [Frankfurt University, Institute for Theoretical Physics, Frankfurt am Main (Germany); Stachel, J. [Ruprecht-Karls-Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Tolos, L. [Frankfurt Institute for Advanced Studies (FIAS), Frankfurt (Germany); Institut de Ciencies de l' Espai (IEEC-CSIC), Bellaterra (Spain); Uras, A. [Domaine Scientifique de la Doua, Institute of Nuclear Physics, Villeurbanne Cedex (France); Xu, N. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Ye, Z. [University of Illinois, Chicago, IL (United States); Zhuang, P. [Tsinghua University, Beijng Shi (China)

2017-05-15

Open and hidden heavy-flavor physics in high-energy nuclear collisions are entering a new and exciting stage towards reaching a clearer understanding of the new experimental results with the possibility to link them directly to the advancement in lattice Quantum Chromo-Dynamics (QCD). Recent results from experiments and theoretical developments regarding open and hidden heavy-flavor dynamics have been debated at the Lorentz Workshop Tomography of the Quark-Gluon Plasma with Heavy Quarks, which was held in October 2016 in Leiden, The Netherlands. In this contribution, we summarize identified common understandings and developed strategies for the upcoming five years, which aim at achieving a profound knowledge of the dynamical properties of the quark-gluon plasma. (orig.)
Modification of reconstructed gamma-jets in heavy-ion collisions

Energy Technology Data Exchange (ETDEWEB)

Luo, Tan; He, Yayun; Wang, Enke [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); 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)

2016-12-15

We use the Linear Boltzmann Transport model to study gamma-triggered jets in high-energy heavy-ion collisions. Since both recoiled partons from elastic scattering and radiated gluons from inelastic processes and their further propagation are considered, the model can provide a description of not only the medium modification of reconstructed jets but also the energy flow in the underlying hydrodynamic background. In this study, we discuss the modification of jet shape and jet fragmentation function of γ-jet in central Pb+Pb collisions and in particular the energy flow induced by the jet-medium interaction.

Spin-flip processes in low-energy Fe17+ + He collisions

International Nuclear Information System (INIS)

Bruch, R.; Altick, P.L.; Rauscher, E.; Wang, H.; Schneider, D.

1993-01-01

Spin-nonconserving electron transfer processes violating the ''Wigner rule'' have been studied for slow multiply charged ion-atom collisions. Experimentally a strong population of highly metastable sodium-like quartet states in low energy Fe 17+ + He single collision events has been observed. The possibility of double-electron capture plus spin-flip mechanisms has been discussed experimentally and theoretically, Our theoretical model using time dependent perturbation theory predicts that spin-flip processes are as likely as no spin flip under the conditions of our experiment
Thermalization in high energy proton-nucleus collisions

International Nuclear Information System (INIS)

Wedemann, R.S.

1988-03-01

A relativistic proton-nucleus collision using the intranuclear cascade model is studied. The purpose is to verify the equilibration hypothesis at fragmentation time made by many nuclear fragmentation models. (author)
Fully-converged three-dimensional collision-induced dissociation calculations with Faddeev-AGS theory

International Nuclear Information System (INIS)

Haftel, M.I.; Lim, T.K.

1981-09-01

The first fully-converged quantum-mechanical calculation of the collision-induced dissociation cross section in a three-dimensional-model system of three helium-like atoms is reported. Faddeev-AGS theory is used. It yields as a bonus the elastic atom-diatom cross section. The obtained results resemble those from some collinear models but indicate clearly the futility of multiple-scattering approximations except at hyperthermal energies. (orig.)
Beam energy dependence of d and d ‾ production in Au+Au collisions at RHIC

Science.gov (United States)

Yu, Ning; STAR Collaboration

2017-11-01

The binding energy of light nuclei is small compared to the temperature of the system created in heavy-ion collisions. Consequently, the yields of light nuclei can be used to probe the freeze-out properties, such as correlation volume and local baryon density of the medium created in high-energy nuclear collisions. In this paper, we report the results of deuteron and anti-deuteron production in Au+Au collision at √{sNN} = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV, measured by STAR at RHIC. The collision energy, centrality and transverse momentum dependence of the coalescence parameter B2 for deuteron and anti-deuteron production are discussed. We find the values of B2 for anti-deuterons are systematically lower than those for deuterons indicating the correlation volume of anti-baryon are larger than that of baryon. In addition, the values of B2 are found to vary with collision energy and show a broad minimum around √{sNN} = 20GeV, implying a change of the equation of state of the medium in these collisions.
Coupled-Sturmian and perturbative treatments of electron transfer and ionization in high-energy p-He+ collisions

Science.gov (United States)

Winter, Thomas G.; Alston, Steven G.

1992-02-01

Cross sections have been determined for electron transfer and ionization in collisions between protons and He+ ions at proton energies from several hundred kilo-electron-volts to 2 MeV. A coupled-Sturmian approach is taken, extending the work of Winter [Phys. Rev. A 35, 3799 (1987)] and Stodden et al. [Phys. Rev. A 41, 1281 (1990)] to high energies where perturbative approaches are expected to be valid. An explicit connection is made with the first-order Born approximation for ionization and the impulse version of the distorted, strong-potential Born approximation for electron transfer. The capture cross section is shown to be affected by the presence of target basis functions of positive energy near v2/2, corresponding to the Thomas mechanism.
Coupled-Sturmian and perturbative treatments of electron transfer and ionization in high-energy p-He+ collisions

International Nuclear Information System (INIS)

Winter, T.G.; Alston, S.G.

1992-01-01

Cross sections have been determined for electron transfer and ionization in collisions between protons and He + ions at proton energies from several hundred kilo-electron-volts to 2 MeV. A coupled-Sturmian approach is taken, extending the work of Winter [Phys. Rev. A 35, 3799 (1987)] and Stodden et al. [Phys. Rev. A 41, 1281 (1990)] to high energies where perturbative approaches are expected to be valid. An explicit connection is made with the first-order Born approximation for ionization and the impulse version of the distorted, strong-potential Born approximation for electron transfer. The capture cross section is shown to be affected by the presence of target basis functions of positive energy near v 2 /2, corresponding to the Thomas mechanism
Jet energy loss in Boson-jet events in PbPb collisions at 5.02 TeV with CMS

CERN Document Server

Bi, Ran

2017-01-01

A typical approach to study the medium produced in heavy ion collisions is to understand the passage of elementary particles through it. As Z bosons and photons do not participate in the strong interaction, their correlation with jets within the same event is a clean probe of the medium-induced energy loss of (predominantly) quark jets. In this analysis, Z+jet and photon+jet correlations are studied using the high statistics PbPb and pp data taken at a center-of-mass energy of $\\sqrt{s_{NN}}$ = 5.02 TeV with the CMS detector. The evolution of azimuthal angular distributions and average momentum imbalance between the jet and Z or photon as a function of transverse momentum of the color neutral probe will be presented. In addition the jet $I_{AA}$, as a function of photon $p_{T}$ and collision centrality is studied.
Energy transfer in reactive and non-reactive H2 + OH collisions

International Nuclear Information System (INIS)

Rashed, O.; Brown, N.J.

1985-04-01

We have used the methods of quasi-classical dynamics to compute energy transfer properties of non-reactive and reactive H 2 + OH collisions. Energy transfer has been investigated as function of translational temperature, reagent rotational energy, and reagent vibrational energy. The energy transfer mechanism is complex with ten types of energy transfer possible, and evidence was found for all types. There is much more exchange between the translational degree of freedom and the H 2 vibrational degree of freedom than there is between translation and OH vibration. Translational energy is transferred to the rotational degrees of freedom of each molecule. There is a greater propensity for the transfer of translation to OH rotation than H 2 rotation. In reactive collisions, increases in reagent translational temperature predominantly appear as vibrational energy in the water molecule. Energy transfer in non-reactive and reactive collisions does not depend strongly on the initial angular momentum in either molecule. In non-reactive collisions, vibrational energy is transferred to translation, to the rotational degree of freedom of the same molecule, and to the rotational and vibrational degrees of freedom of the other molecule. In reactive collisions, the major effect of increasing the vibrational energy in reagent molecules is that, on the average, the vibrational energy of the reagents appears as product vibrational energy. 18 refs., 16 figs., 6 tabs
Predicting Induced Radioactivity at High Energy Accelerators

Energy Technology Data Exchange (ETDEWEB)

Fasso, Alberto

1999-08-27

Radioactive nuclides are produced at high-energy electron accelerators by different kinds of particle interactions with accelerator components and shielding structures. Radioactivity can also be induced in air, cooling fluids, soil and groundwater. The physical reactions involved include spallations due to the hadronic component of electromagnetic showers, photonuclear reactions by intermediate energy photons and low-energy neutron capture. Although the amount of induced radioactivity is less important than that of proton accelerators by about two orders of magnitude, reliable methods to predict induced radioactivity distributions are essential in order to assess the environmental impact of a facility and to plan its decommissioning. Conventional techniques used so far are reviewed, and a new integrated approach is presented, based on an extension of methods used at proton accelerators and on the unique capability of the FLUKA Monte Carlo code to handle the whole joint electromagnetic and hadronic cascade, scoring residual nuclei produced by all relevant particles. The radiation aspects related to the operation of superconducting RF cavities are also addressed.
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.
High-resolution measurements of x rays from ion-atom collisions

International Nuclear Information System (INIS)

Knudson, A.R.

1974-01-01

High resolution measurements of K x-ray spectra produced by ion-atom collisions at MeV energies are presented. These measurements indicate that a distribution of L-shell vacancies accompanies K-shell excitation. The variation of these spectra as a function of incident ion energy and atomic number is discussed. Difficulties in the analysis of these spectra due to rearrangement of vacancies between the time of the collision and the time of x-ray emission are considered. The use of high resolution x-ray measurements to obtain information on projectile ion vacancy configurations is demonstrated by data for Ar ions in KCl. X-ray spectra from Al projectiles in a variety of targets were measured and the effect of target composition on these spectra is discussed
Lepton-pair production and the modified Drell-Yan mechanism in high-energy unpolarized and polarized pp and p anti p collisions

International Nuclear Information System (INIS)

Chen, C.K.

1977-01-01

A modified Drell-Yan mechanism for inclusive dilepton pair production in hadronic reactions is studied, and the significance of comparing high-energy unpolarized and polarized pp and p anti p collisions is discussed. The required beams are currently proposed at Fermilab and CERN
Fifth high-energy heavy-ion study

International Nuclear Information System (INIS)

1981-10-01

This was the fifth of a continuing series of summer studies held at LBL to discuss high energy heavy ion collisions. Recently, a similar meeting has been held on alternate years at GSI (Darmstadt); and, in 1979, we held a meeting at LBL exclusively devoted to ultra-relativistic nuclear collisions. Two new features distinguish this study from earlier meetings in the series. First, the energy range for discussion was broadened by including collisions from about 20 MeV/nucleon to the highest available in the cosmic radiation. The lower range, particularly below 100 MeV/nucleon, will be under intense study in the near future with machines such as the upgraded Bevalac, Michigan State University Superconducting Cyclotron, GANIL in France, and the SC at CERN. Recently, the high energy collision regime has been expanded by the successful operation of the CERN ISR with alpha particles. Second, in addition to an extensive program of invited talks, we decided for the first time to actively solicit contributions. Forty-seven individual items from the conference were prepared separately for the data base
Fifth high-energy heavy-ion study

Energy Technology Data Exchange (ETDEWEB)

1981-10-01

This was the fifth of a continuing series of summer studies held at LBL to discuss high energy heavy ion collisions. Recently, a similar meeting has been held on alternate years at GSI (Darmstadt); and, in 1979, we held a meeting at LBL exclusively devoted to ultra-relativistic nuclear collisions. Two new features distinguish this study from earlier meetings in the series. First, the energy range for discussion was broadened by including collisions from about 20 MeV/nucleon to the highest available in the cosmic radiation. The lower range, particularly below 100 MeV/nucleon, will be under intense study in the near future with machines such as the upgraded Bevalac, Michigan State University Superconducting Cyclotron, GANIL in France, and the SC at CERN. Recently, the high energy collision regime has been expanded by the successful operation of the CERN ISR with alpha particles. Second, in addition to an extensive program of invited talks, we decided for the first time to actively solicit contributions. Forty-seven individual items from the conference were prepared separately for the data base. (GHT)
High energy gamma-ray production in nuclear reactions

International Nuclear Information System (INIS)

Pinston, J.A.; Nifenecker, H.; Nifenecker, H.

1989-01-01

Experimental techniques used to study high energy gamma-ray production in nuclear reactions are reviewed. High energy photon production in nucleus-nucleus collisions is discussed. Semi-classical descriptions of the nucleus-nucleus gamma reactions are introduced. Nucleon-nucleon gamma cross sections are considered, including theoretical aspects and experimental data. High energy gamma ray production in proton-nucleus reactions is explained. Theoretical explanations of photon emission in nucleus-nucleus collisions are treated. The contribution of charged pion currents to photon production is mentioned
Observation of strong azimuthal asymmetry between slow and fast particles from high energy nuclear collisions

International Nuclear Information System (INIS)

Gustafsson, H.A.; Gutbrod, H.H.; Kolb, B.; Loehner, H.; Ludewigt, B.; Poskanzer, A.M.; Renner, T.; Riedesel, H.; Ritter, H.G.; Siemiarczuk, T.; Stepaniak, J.; Warwick, A.; Wieman, H.

1984-10-01

Evidence is presented for the strong azimuthal asymmetry between slow and fast fragments in nuclear collisions in the energy interval of 0.4 to 1 GeV per nucleon. The asymmetry gets stronger when incident energy and impact parameter decrease. The results on the A dependence of the azimuthal asymmetry are also presented. (orig.)
Hadron-nucleus collisions

International Nuclear Information System (INIS)

Strugalski, Z.

1981-01-01

Qualitative picture of high energy hadron-nucleus collision process, emerging from the analysis of experimental data, is presented. Appropriate description procedure giving a possibility of reproducing various characteristics of this process in terms of the data on elementary hadron-nucleon interaction is proposed. Formula reproducing hadron-nucleus collision cross sections is derived. Inelastic collision cross sections for pion-nucleus and proton-nucleus reactions at wide energy interval are calculated for Pb, Ag, and Al targets. A-dependence of cross sections for pion-nucleus and proton-nucleus collisions at nearly 50 GeV/c momentum were calculated and compared with existing experimental data. Energy dependence of cross sections for hadron-nucleus collisions is determined simply by energy dependence of corresponding cross sections for hadron-nucleon collisions; A-dependence is determined simply by nuclear sizes and nucleon density distributions in nuclei
Prediction of catastrophe theory for heavy-ion collisions at high energies

International Nuclear Information System (INIS)

Kuchin, I.A.

2002-01-01

Studying the nature of limiting fragmentation of nuclei in high energy heavy-ion collisions has shown that the dynamic system of the nucleus is inclined to enter a nonequilibrium state, schottische and disintegrate on separate nucleons under conditions typical to each collision. There is a question: how the phenomenon of multifragmentation is possible here, i. e. formation of several nucleus with masses on interval from a nucleon up to a material nucleus A in a final state. What is it - debris of a material nucleus or newly created daughter nuclei? The purpose of offered report is discussion of this question. The initial for us statement is taken from the theory of dynamic systems. Chaos is a result of hashing of phase space which is carried out by means of operations of distension and compression. The appropriate transformation are called baker-transformation or Smale's horseshoe. The geometrical picture of chaos is a folded relief of multi-dimensional phase space. The stochastic amplification is understood as growth of folder number and their size. In typical interactions of massive ions, chaos formation conditions are provided automatically due to alternate force influence of Coulomb and Yukawa fields - compression is replaced by distension, and distension - by compression. Extending this representation on a case of massive ion collision, we supplement it accounting a possibility of constituents (nucleons) strong interaction on small distances. The easiest way to make it is approximating minima of potential function V(x, c) in catastrophe theory by rectangular holes of Fermi-gas in nuclear physics. The catastrophe theory is necessary to find connection between channels of fragments birth of different charge and masses, proceeding from the general form of a multi-dimensional phase space relief (a kind of potential function). The main result which can be taken from this theory at the given stage of researches consists in the general form of a curve of a
Studying the collision energy dependence of elliptic and triangular flow with a hybrid model

Energy Technology Data Exchange (ETDEWEB)

Auvinen, Jussi [Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); Petersen, Hannah [Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); Institut fuer Theoretische Physik, Goethe Universitaet, Frankfurt am Main (Germany)

2014-07-01

Elliptic flow has been one of the key observables for establishing the finding of the quark-gluon plasma (QGP) at the highest energies of Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). As a sign of collectively behaving matter, the elliptic flow is expected to decrease at lower beam energies, where the QGP is not produced. However, in the recent RHIC beam energy scan, it has been found that the inclusive charged hadron elliptic flow changes relatively little in magnitude within the energy range 7.7-39 GeV per nucleon-nucleon collision. We study the collision energy dependence of the elliptic and triangular flow utilizing a Boltzmann+hydrodynamics hybrid model. Such a hybrid model provides a natural framework for the transition from high collision energies, where the hydrodynamical description is essential, to smaller energies, where the hadron transport dominates. This approach is thus suitable for investigating the relative importance of these two mechanisms for the production of the collective flow at different beam energies.
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.

Angular distributions of target black fragments in nucleus–nucleus collisions at high energy

International Nuclear Information System (INIS)

Liu, Fuhu; Abd Allah, N.N.; Zhang, Donghai; Duan, Maiying

2003-01-01

The experimental results of space, azimuthal, and projected angular distributions of target black fragments produced in silicon-emulsion collisions at 4.5A GeV/c (the Dubna energy) are reported. A multi-source ideal gas model is suggested to describe the experimental angular distributions. The Monte Carlo calculated results are in agreement with the experimental data. (author)
High transverse momentum resonance production in Pb-Pb, pp and p-Pb collisions at LHC

CERN Document Server

Nayak, Kishora

2015-01-01

Resonance production in heavy-ion collisions is expected to be a sensitive probe to the proper- ties of strongly interacting matter produced in such collisions. The production of resonances at high transverse momentum will help us to understand the mechanism of particle production and parton energy loss in the medium formed in ultra-relativistic heavy-ion collisions. We report the measurements of K ∗ 0 ( τ ∼ 4 fm/ c ) and φ ( τ ∼ 42 fm/ c ) production at high transverse momen- tum in pp, p–Pb and Pb–Pb collisions at LHC energies and nuclear modification factors. These measurements are compared to corresponding results for the other produced hadrons like charged kaons and protons. Some aspects of resonance production and particle production in general are discussed.
Exploring the QCD Phase Structure with Beam Energy Scan in Heavy-ion Collisions

Energy Technology Data Exchange (ETDEWEB)

Luo, Xiaofeng, E-mail: xfluo@mail.ccnu.edu.cn

2016-12-15

Beam energy scan programs in heavy-ion collisions aim to explore the QCD phase structure at high baryon density. Sensitive observables are applied to probe the signatures of the QCD phase transition and critical point in heavy-ion collisions at RHIC and SPS. Intriguing structures, such as dip, peak and oscillation, have been observed in the energy dependence of various observables. In this paper, an overview is given and corresponding physics implications will be discussed for the experimental highlights from the beam energy scan programs at the STAR, PHENIX and NA61/SHINE experiments. Furthermore, the beam energy scan phase II at RHIC (2019–2020) and other future experimental facilities for studying the physics at low energies will be also discussed.
The energy overcompensating disintegrations of residual target nuclei damaged in hadron-nucleus collisions

International Nuclear Information System (INIS)

Strugalski, Z.

1995-01-01

Massive target nuclei damaged in hadron-nucleus collisions at high energies are used to disintegrate into nuclear fragments. In many cases such breakup is egzoergic - some portion of nuclear energy is released; this portion should be overcompensating the energy used for the nuclear damage, in some cases. 30 refs
Physics of Nuclear Collisions at High Energy

Energy Technology Data Exchange (ETDEWEB)

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

2012-05-01

A wide range of problems has been investigated in the research program during the period of this grant. Although the major effort has been in the subject of heavy-ion collisions, we have also studied problems in biological and other physical systems. The method of analysis used in reducing complex data in multiparticle production to simple descriptions can also be applied to the study of complex systems of very different nature. Phase transition is an important phenomenon in many areas of physics, and for heavy-ion collisions we study the fluctuations of multiplicities at the critical point. Human brain activities as revealed in EEG also involve fluctuations in time series, and we have found that our experience enables us to find the appropriate quantification of the fluctuations in ways that can differentiate stroke and normal subjects. The main topic that characterizes the research at Oregon in heavy-ion collisions is the recombination model for the treatment of the hadronization process. We have avoided the hydrodynamical model partly because there is already a large community engaged in it, but more significantly we have found the assumption of rapid thermalization unconvincing. Recent results in studying LHC physics lead us to provide more evidence that shower partons are very important even at low p_T, but are ignored by hydro. It is not easy to work in an environment where the conventional wisdom regards our approach as being incorrect because it does not adhere to the standard paradigm. But that is just what a vibrant research community needs: unconventional approach may find evidences that can challenge the orthodoxy. An example is the usual belief that elliptic flow in fluid dynamics gives rise to azimuthal anisotropy. We claim that it is only sufficient but not necessary. With more data from LHC and more independent thinkers working on the subject what is sufficient as a theory may turn out to be incorrect in reality. Another area of investigation that
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)
High baryon and energy densities achievable in heavy-ion collisions at √{sN N}=39 GeV

Science.gov (United States)

Ivanov, Yu. B.; Soldatov, A. A.

2018-02-01

Baryon and energy densities, which are reached in central Au+Au collisions at collision energy of √{sN N}= 39 GeV, are estimated within the model of three-fluid dynamics. It is shown that the initial thermalized mean proper baryon and energy densities in a sizable central region approximately are nB/n0≈ 10 and ɛ ≈ 40 GeV/fm3, respectively. The study indicates that the deconfinement transition at the stage of interpenetration of colliding nuclei makes the system quite opaque. The final fragmentation regions in these collisions are formed not only by primordial fragmentation fireballs, i.e., the baryon-rich matter passed through the interaction region (containing approximately 30% of the total baryon charge), but also by the baryon-rich regions of the central fireball pushed out to peripheral rapidities by the subsequent almost one-dimensional expansion of the central fireball along the beam direction.
Pion and kaon correlations in high energy heavy-ion collisions

International Nuclear Information System (INIS)

Wolf, K.L.

1996-01-01

Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV 208 Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered 208 Pb + Pb collisions. An upgraded multi-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-pion interferometry in the 1.2 A GeV Au+Au reaction, taken with full event characterization. 35 refs., 15 figs., 5 tabs
Binary cluster collision dynamics and minimum energy conformations

Energy Technology Data Exchange (ETDEWEB)

Muñoz, Francisco [Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany); Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y Nanotecnología, CEDENNA, Avenida Ecuador 3493, Santiago (Chile); Rogan, José; Valdivia, J.A. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y Nanotecnología, CEDENNA, Avenida Ecuador 3493, Santiago (Chile); Varas, A. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Nano-Bio Spectroscopy Group, ETSF Scientific Development Centre, Departamento de Física de Materiales, Universidad del País Vasco UPV/EHU, Av. Tolosa 72, E-20018 San Sebastián (Spain); Kiwi, Miguel, E-mail: m.kiwi.t@gmail.com [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y Nanotecnología, CEDENNA, Avenida Ecuador 3493, Santiago (Chile)

2013-10-15

The collision dynamics of one Ag or Cu atom impinging on a Au{sub 12} cluster is investigated by means of DFT molecular dynamics. Our results show that the experimentally confirmed 2D to 3D transition of Au{sub 12}→Au{sub 13} is mostly preserved by the resulting planar Au{sub 12}Ag and Au{sub 12}Cu minimum energy clusters, which is quite remarkable in view of the excess energy, well larger than the 2D–3D potential barrier height. The process is accompanied by a large s−d hybridization and charge transfer from Au to Ag or Cu. The dynamics of the collision process mainly yields fusion of projectile and target, however scattering and cluster fragmentation also occur for large energies and large impact parameters. While Ag projectiles favor fragmentation, Cu favors scattering due to its smaller mass. The projectile size does not play a major role in favoring the fragmentation or scattering channels. By comparing our collision results with those obtained by an unbiased minimum energy search of 4483 Au{sub 12}Ag and 4483 Au{sub 12}Cu configurations obtained phenomenologically, we find that there is an extra bonus: without increase of computer time collisions yield the planar lower energy structures that are not feasible to obtain using semi-classical potentials. In fact, we conclude that phenomenological potentials do not even provide adequate seeds for the search of global energy minima for planar structures. Since the fabrication of nanoclusters is mainly achieved by synthesis or laser ablation, the set of local minima configurations we provide here, and their distribution as a function of energy, are more relevant than the global minimum to analyze experimental results obtained at finite temperatures, and is consistent with the dynamical coexistence of 2D and 3D liquid Au clusters conformations obtained previously.
Born term for high-energy meson-hadron collisions from QCD and chiral quark model

International Nuclear Information System (INIS)

Ochs, W.; Shimada, T.

1988-01-01

Various experimental observations reveal a sizeable hard component in the high-energy 'soft' hadronic collisions. For primary meson beams we propose a QCD Born term which describes the dissociation of the primary meson into a quark-antiquark pair in the gluon field of the target. A pointlike effective pion-quark coupling is assumed as in the chiral quark model by Manohar and Georgi. We derive the total cross sections which for pion beams, for example, are given in terms of f π -2 and some properties of the hadronic final states. In particular, we stress the importance of studying three-jet events in meson-nucleon scattering and discuss the seagull effect. (orig.)
Hydrodynamics in high-energy nuclear collisions. Quarterly report 3. quarter 1987

International Nuclear Information System (INIS)

Kataja, Markku.

1989-05-01

This thesis is a review of six publications in which we make use of relativistic hydrodynamics to solve the evolution of matter produced in extremely energetic nucleus-nucleus collisions. In the first one of these papers we study the thermodynamics, the hydrodynamics and the decoupling conditions of such matter. We discuss the initial conditions for the flow, the hydrodynamic equations for the transverse expansion of matter assuming cylindrical symmetry and longitudinal boost invariance and finally present a numeric algorithm, which we use to integrate these equations. In the subsequent three papers this framework is utilized to calculate the transverse momentum spectra of hadrons, the dilepon production and the abundance of strange particles in the final state. The bag model equation of state is used to simulate the first-order phase transition between baryonless hadronic matter and quark-gluon plasma. In the fifth paper we include the particle production from decaying color electric field according to the flux tube model for heavy ion collisions. The hadronization is incorporated by introducing an equilibrium 'mixed state' of hadrons gas, plasma and the color field in analogy to the mixed phase described by the ordinary bag model equation of state. In the last paper I apply a 1+2 dimensional numeric code to analyze a 1+3 dimensional cylindrically symmetric flow of matter assumed to be formed in a central O+Pb collision at 200 GeV/nucleon. The flow data is used to calculte the pseudorapidity distribution of transverse energy for the produced pions
Experimental device for the study of elastic and inelastic diffusion at high-energy He+-He collisions

International Nuclear Information System (INIS)

Dagnac, R.; Bordenave-Montesquieu, D.; Baudon, J.

1978-01-01

An experimental device for studying heavy particle collisions in the energy range 5 to 40 keV is described. Differential inelastic cross sections are measured by means of an energy loss analysis at scattering angles ranging from 0.5 to 4 0 . Typical energy loss spectra obtained at 6.5 keV and 40 keV are given for two diffusion angles. (author)
[Search for strange quark matter and antimatter produced in high energy heavy ion collisions

International Nuclear Information System (INIS)

1992-01-01

This document describes the development and progress of our group's research program in high energy heavy ion physics. We are a subset of the Yale experimental high energy physics effort (YAUG group) who became interested in the physics of high energy heavy ions in 1988. Our interest began with the possibility of performing significant searches for strange quark matter. As we learned more about the subject and as we gained experimental experience through our participation in AGS experiment 814, our interests have broadened. Our program has focused on the study of new particles, including (but not exclusively) strange quark matter, and the high sensitivity measurement of other composite nuclear systems such as antinuclei and various light nuclei. The importance of measurements of the known, but rare, nuclear systems lies in the study of production mechanisms. A good understanding of the physics and phenomenology of rare composite particle production in essential for the interpretation of limits to strange quark matter searches. We believe that such studies will also be useful in probing the mechanisms involved in the collision process itself. We have been involved in the running and data analysis for AGS E814. We have also worked on the R ampersand D for AGS E864, which is an approved experiment designed to reach sensitivities where there will be a good chance of discovering strangelets or of setting significant limits on the parameters of strange quark matter
Energy sharing and sputtering in low-energy collision cascades

International Nuclear Information System (INIS)

Weller, R.A.; Weller, M.R.

1982-01-01

Using a non-linear transport equation to describe the energy-sharing process in an isotropic collision cascade, we have numerically calculated sputtered particle velocity spectra for several very low energy (=< 10 eV) primary recoil distributions. Our formulation of the sputtering process is essentially that used in the linear model and our equations yield the familiar linear model results in the appropriate limit. Discrepancies between our calculations and the linear model results in other cases may be understood by considering the effects of the linear model assumptions on the sputtering yield at very low energies. Our calculations are also compared with recent experimental results investigating ion-explosion sputtering. The results of this comparison support the conclusion that in insulators sputtering is initiated by very low energy recoil atoms when the energy of the incident beam is high enough that the stopping power is dominated by the electronic contribution. The calculations also suggest that energy spectra similar to those for evaporation may result from non-equilibrium processes but that the apparent temperatures of evaporation are not related in a simple way to any real temperature within the target. (author)
Time resolved laser induced fluorescence on argon intermediate pressure microwave discharges: Measuring the depopulation rates of the 4p and 5p excited levels as induced by electron and atom collisions

Energy Technology Data Exchange (ETDEWEB)

Palomares, J.M., E-mail: j.m.palomares-linares@tue.nl; Graef, W.A.A.D.; Hübner, S.; Mullen, J.J.A.M. van der, E-mail: jjamvandermullen@gmail.com

2013-10-01

The reaction kinetics in the excitation space of Ar is explored by means of Laser Induced Fluorescence (LIF) experiments using the combination of high rep-rate YAG–Dye laser systems with a well defined and easily controllable surfatron induced plasma setup. The high rep-rate favors the photon statistics while the low energy per pulse avoids intrusive plasma laser interactions. An analysis shows that, despite the low energy per pulse, saturation can still be achieved even when the geometrical overlap and spectral overlap are optimal. Out of the various studies that can be performed with this setup we confine the current paper to the study of the direct responses to the laser pump action of three 4p and one 5p levels of the Ar system. By changing the plasma in a controlled way one gets for these levels the rates of electron and atom quenching and therewith the total destruction rates of electron and atom collisions. Comparison with literature shows that the classical hard sphere collision rate derived for hydrogen gives a good description for the observed electron quenching (e-quenching) in Ar whereas for heavy particle quenching (a-quenching) this agreement was only found for the 5p level. An important parameter in the study of electron excitation kinetics is the location of the boundary in the atomic system for which the number of electron collisions per radiative life time equals unity. It is observed that for the Ar system this boundary is positioned lower than what is expected on grounds of H-like formulas. - Highlights: • Time resolved laser induced fluorescence at high repetition rate • Decay times as function of pressure, electron density and temperature • Measurement of total electron atom depopulation rates • Reasonable agreement of electron total rates with hard sphere approximations.
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
Semihard interactions in nuclear collisions based on a unified approach to high energy scattering

International Nuclear Information System (INIS)

Drescher, H.J.; Hladik, M.; Werner, K.; Ostapchenko, S.; Centre National de la Recherche Scientifique, 44 - Nantes

1998-01-01

Our ultimate goal is the construction of a model for interactions of two nuclei in the energy range between several tens of GeV up to several TeV per nucleon in the centre-of-mass system. Such nuclear collisions are very complex, being composed of many components, and therefore some strategy is needed to construct a reliable model. The central point of our approach is the hypothesis, that the behavior of high energy interactions is universal (universality hypothesis). A model for nuclear interactions in a modular fashion is proposed. The individual modules, based on the universality hypothesis, are identified as building blocks for more elementary interactions (like e + e - , lepton-proton), and can therefore be studied in a much simpler context. With these building blocks under control, a quite reliable model is developed for nucleus-nucleus scattering, providing in particular very useful tests for the complicated numerical procedures using Monte Carlo techniques. (author)
A quasi-classical study of energy transfer in collisions of hyperthermal H atoms with SO2 molecules.

Science.gov (United States)

da Silva, Ramon S; Garrido, Juan D; Ballester, Maikel Y

2017-08-28

A deep understanding of energy transfer processes in molecular collisions is at central attention in physical chemistry. Particularly vibrational excitation of small molecules colliding with hot light atoms, via a metastable complex formation, has shown to be an efficient manner of enhancing reactivity. A quasi-classical trajectory study of translation-to-vibration energy transfer (T-V ET) in collisions of hyperthermal H( 2 S) atoms with SO 2 (X̃ 1 A ' ) molecules is presented here. For such a study, a double many-body expansion potential energy surface previously reported for HSO 2 ( 2 A) is used. This work was motivated by recent experiments by Ma et al. studying collisions of H + SO 2 at the translational energy of 59 kcal/mol [J. Ma et al., Phys. Rev. A 93, 040702 (2016)]. Calculations reproduce the experimental evidence that during majority of inelastic non-reactive collision processes, there is a metastable intermediate formation (HOSO or HSO 2 ). Nevertheless, the analysis of the trajectories shows that there are two distinct mechanisms in the T-V ET process: direct and indirect. Direct T-V processes are responsible for the high population of SO 2 with relatively low vibrational excitation energy, while indirect ones dominate the conversion from translational energy to high values of the vibrational counterpart.
Baryon, charged hadron, Drell-Yan and J/ψ production in high energy proton-nucleus collisions

International Nuclear Information System (INIS)

Gale, Charles; Jeon, Sangyong; Kapusta, Joseph

1999-01-01

We show that the distributions of outgoing protons and charged hadrons in high energy proton-nucleus collisions are described rather well by a linear extrapolation from proton-proton collisions. The only adjustable parameter required is the shift in rapidity of a produced charged meson when it encounters a target nucleon. Its fitted value is 0.16. Next, we apply this linear extrapolation to precisely measured Drell-Yan cross sections for 800 GeV protons incident on a variety of nuclear targets which exhibit a deviation from linear scaling in the atomic number A. We show that this deviation can be accounted for by energy degradation of the proton as it passes through the nucleus if account is taken of the time delay of particle production due to quantum coherence. We infer an average proper coherence time of 0.4±0.1 fm/c, corresponding to a coherence path length of 8±2 fm in the rest frame of the nucleus. Finally, we apply the linear extrapolation to measured J/ψ production cross sections for 200 and 450 GeV/c protons incident on a variety of nuclear targets. Our analysis takes into account energy loss of the beam proton, the time delay of particle production due to quantum coherence, and absorption of the J/ψ on nucleons. The best representation is obtained for a coherence time of 0.5 fm/c, which is consistent with Drell-Yan production, and an absorption cross section of 3.6 mb, which is consistent with the value deduced from photoproduction of the J/ψ on nuclear targets
Maximizing kinetic energy transfer in one-dimensional many-body collisions

International Nuclear Information System (INIS)

Ricardo, Bernard; Lee, Paul

2015-01-01

The main problem discussed in this paper involves a simple one-dimensional two-body collision, in which the problem can be extended into a chain of one-dimensional many-body collisions. The result is quite interesting, as it provides us with a thorough mathematical understanding that will help in designing a chain system for maximum energy transfer for a range of collision types. In this paper, we will show that there is a way to improve the kinetic energy transfer between two masses, and the idea can be applied recursively. However, this method only works for a certain range of collision types, which is indicated by a range of coefficients of restitution. Although the concept of momentum, elastic and inelastic collision, as well as Newton’s laws, are taught in junior college physics, especially in Singapore schools, students in this level are not expected to be able to do this problem quantitatively, as it requires rigorous mathematics, including calculus. Nevertheless, this paper provides nice analytical steps that address some common misconceptions in students’ way of thinking about one-dimensional collisions. (paper)

Maximizing kinetic energy transfer in one-dimensional many-body collisions

Science.gov (United States)

Ricardo, Bernard; Lee, Paul

2015-03-01

The main problem discussed in this paper involves a simple one-dimensional two-body collision, in which the problem can be extended into a chain of one-dimensional many-body collisions. The result is quite interesting, as it provides us with a thorough mathematical understanding that will help in designing a chain system for maximum energy transfer for a range of collision types. In this paper, we will show that there is a way to improve the kinetic energy transfer between two masses, and the idea can be applied recursively. However, this method only works for a certain range of collision types, which is indicated by a range of coefficients of restitution. Although the concept of momentum, elastic and inelastic collision, as well as Newton’s laws, are taught in junior college physics, especially in Singapore schools, students in this level are not expected to be able to do this problem quantitatively, as it requires rigorous mathematics, including calculus. Nevertheless, this paper provides nice analytical steps that address some common misconceptions in students’ way of thinking about one-dimensional collisions.
[Reactive collisions of high-temperature systems]: Progress report

International Nuclear Information System (INIS)

Graff, M.M.

1988-01-01

We are developing an experiment to study the reactive collisions of systems with large activation barriers or endothermicities. The basis design involves the collision of fast radicals with a stable reactant gas (hydrogen) in a collision cell. Initially, products will be detected by ionization and mass analysis. Later, laser-induced fluorescence will be used to probe internal states of products. Studies will include an investigation of rotational effects by comparing results for rotational levels J = O and 1 of molecular hydrogen. 2 figs
Electrons with continuous energy distribution from energetic heavy ion collisions

International Nuclear Information System (INIS)

Berenyi, D.

1984-01-01

The properties and origin of continuous electron spectrum emitted in high energy heavy ion collisions are reviewed. The basic processes causing the characteristic regions of the continuous spectrum are described. The contribution of electrons ejected from the target and from the projectile are investigated in detail in the cases of light and heavy projectiles. The recently recognized mechanisms, electron-capture-to-continuum (ECC) and electron-loss-to-continuum (ELC), leading to a cusp in forward direction, and their theoretical interpretations are discussed. The importance of data from ion-atom collisions in the field of atomic physics and in applications are briefly summarized. (D.Gy)
High-energy radiation from collisions of high-velocity clouds and the Galactic disc

Science.gov (United States)

del Valle, Maria V.; Müller, A. L.; Romero, G. E.

2018-04-01

High-velocity clouds (HVCs) are interstellar clouds of atomic hydrogen that do not follow normal Galactic rotation and have velocities of a several hundred kilometres per second. A considerable number of these clouds are falling down towards the Galactic disc. HVCs form large and massive complexes, so if they collide with the disc a great amount of energy would be released into the interstellar medium. The cloud-disc interaction produces two shocks: one propagates through the cloud and the other through the disc. The properties of these shocks depend mainly on the cloud velocity and the disc-cloud density ratio. In this work, we study the conditions necessary for these shocks to accelerate particles by diffusive shock acceleration and we study the non-thermal radiation that is produced. We analyse particle acceleration in both the cloud and disc shocks. Solving a time-dependent two-dimensional transport equation for both relativistic electrons and protons, we obtain particle distributions and non-thermal spectral energy distributions. In a shocked cloud, significant synchrotron radio emission is produced along with soft gamma rays. In the case of acceleration in the shocked disc, the non-thermal radiation is stronger; the gamma rays, of leptonic origin, might be detectable with current instruments. A large number of protons are injected into the Galactic interstellar medium, and locally exceed the cosmic ray background. We conclude that under adequate conditions the contribution from HVC-disc collisions to the galactic population of relativistic particles and the associated extended non-thermal radiation might be important.
Can pions created in high-energy heavy-ion collisions produce a Centauro-type effect?

International Nuclear Information System (INIS)

Martinis, M.; Mikuta-Martinis, V.; Crnugelj, J.

1995-01-01

We study a Centauro-type phenomenon in high-energy heavy-ion collisions by assuming that pions are produced semiclassically both directly and in pairs through the isovector channel. The leading-particle effect and the factorization property of the scattering amplitude in the impact-parameter space are used to define the classical pion field. We show that the Centauro-type effect is strongly suppressed if a large number of pions are produced in isovector pairs. Our conclusion is supported through the calculation of two pion correlation parameters, f 2 0- and f 2 00 , as well as f 2, n - 0 and the average number of neutral pions (left-angle n 0 right-angle n- ) a a function of negative pions (n - ) produced
High-$p_\\mathrm{T}$ probes of $p$+Pb collisions with ATLAS

CERN Document Server

Perepelitsa, Dennis; The ATLAS collaboration

2015-01-01

Measurements of high $p_\\mathrm{T}$ processes in ultrarelativistic proton--nucleus collisions are sensitive to changes in the partonic densities arising from the presence of the nuclear environment. Additionally, such measurements benchmark the so called ``cold nuclear matter'' effects, providing the context within which to understand the strong suppression of high $p_\\mathrm{T}$ processes observed in nucleus--nucleus collisions. Furthermore, measurements of the centrality dependence of jet production at forward (proton-going) rapidities may even shed light on the behavior of the proton wavefunction at large Bjorken-$x$. The latest ATLAS results for inclusive jets and charged particles in 28/nb of $5.02$~TeV proton--lead collisions at the LHC are presented. The centrality in these collisions is characterized through the sum of the transverse energy in the lead-going forward calorimeter. The nuclear modification factors $R_{p\\mathrm{Pb}}$ and $R_\\mathrm{CP}$ are presented for jets and charged particles as a fu...
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.)
Isospin effect of coulomb interaction on momentum dissipation in intermediate energy heavy ion collisions

International Nuclear Information System (INIS)

Liu Jianye; Guo Wenjun; Li Xiguo; Xing Yongzhong

2004-01-01

The authors investigate the isospin effect of Coulomb interaction on the momentum dissipation or nuclear stopping in the intermediate energy heavy ion collisions by using the isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces obviously the reductions of the momentum dissipation. The authors also find that the variation amplitude of momentum dissipation induced by the Coulomb interaction depends sensitively on the form and strength of symmetry potential. However, the isospin effect of Coulomb interaction on the momentum dissipation is less than that induced by the in-medium nucleon-nucleon cross section. In this case, Coulomb interaction does not changes obviously the isospin effect of momentum dissipation induced by the in-medium two-body collision. In particular, the Coulomb interaction is preferable for standing up the isospin effect of in-medium nucleon-nucleon cross section on the momentum dissipation and reducing the isospin effect of symmetry potential on it, which is important for obtaining the feature about the sensitive dependence of momentum dissipation on the in-medium nucleon-nucleon cross section and weakly on the symmetry potential. (author)
The effect of the intermolecular potential formulation on the state-selected energy exchange rate coefficients in N2-N2 collisions.

Science.gov (United States)

Kurnosov, Alexander; Cacciatore, Mario; Laganà, Antonio; Pirani, Fernando; Bartolomei, Massimiliano; Garcia, Ernesto

2014-04-05

The rate coefficients for N2-N2 collision-induced vibrational energy exchange (important for the enhancement of several modern innovative technologies) have been computed over a wide range of temperature. Potential energy surfaces based on different formulations of the intramolecular and intermolecular components of the interaction have been used to compute quasiclassically and semiclassically some vibrational to vibrational energy transfer rate coefficients. Related outcomes have been rationalized in terms of state-to-state probabilities and cross sections for quasi-resonant transitions and deexcitations from the first excited vibrational level (for which experimental information are available). On this ground, it has been possible to spot critical differences on the vibrational energy exchange mechanisms supported by the different surfaces (mainly by their intermolecular components) in the low collision energy regime, though still effective for temperatures as high as 10,000 K. It was found, in particular, that the most recently proposed intermolecular potential becomes the most effective in promoting vibrational energy exchange near threshold temperatures and has a behavior opposite to the previously proposed one when varying the coupling of vibration with the other degrees of freedom. Copyright © 2014 Wiley Periodicals, Inc.
Determination of the excitation energy and angular momentum of the quasi-projectiles produced in the heavy ion collisions Xe + Sn; Determination de l'energie d'excitation et du moment angulaire des quasi-projectiles produits dans les collisions d'ions lourds Xe + Sn

Energy Technology Data Exchange (ETDEWEB)

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

1999-04-08

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

CERN Document Server

Ellis, John

2016-04-14

In a recent paper, Tye and Wong (TW) have argued that sphaleron-induced transitions in high-energy proton-proton collisions should be enhanced compared to previous calculations, based on a construction of a Bloch wave function in the periodic sphaleron potential and the corresponding pass band structure. Here we convolute the calculations of TW with parton distribution functions and simulations of final states to explore the signatures of sphaleron transitions at the LHC and possible future colliders. We calculate the increase of sphaleron transition rates in proton-proton collisions at centre-of-mass energies of 13/14/33/100 TeV for different sphaleron barrier heights, while recognising that the rates have large overall uncertainties. We use a simulation to show that LHC searches for microscopic black holes should have good efficiency for detecting sphaleron-induced final states, and discuss their experimental signatures and observability in Run 2 of the LHC and beyond. We recast the early ATLAS Run-2 search...
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
Transverse energy distribution and hard constituent scattering in hadronic collisions

Directory of Open Access Journals (Sweden)

Torsten Åkesson

1983-01-01

Full Text Available We estimate the contributions to the total transverse energy spectrum from hard constituent scattering and the soft hadronic spectrum in hadron collisions. The transverse energy at which jet production starts to dominate is found to be essentially independent of the cms-energy (for large enough s and roughly a linear function of rapidity and azimuthal angle interval included. Calculations are presented for pp collisions at s= 25and60GeV, andp¯p interactions at s= 540GeV.
Kinetic energy dissipation in heavy-ion collisions

International Nuclear Information System (INIS)

Fedotov, S.I.; Jolos, R.V.; Kartavenko, V.G.

1979-01-01

Kinetic energy dissipation mechanism is considered in deep inelastic heavy-ion collisions. It is shown that the significant part of the kinetic energy loss can be explained by the excitation of the nuclear matter multipole vibrations. The main contribution of the energy dissipation is given by the time dependent heavy-ion interaction potential renormalized due to the nuclear excitations, rather than by the velocity proportional frictional forces
[Electron transfer, ionization and excitation in atomic collisions

International Nuclear Information System (INIS)

1991-01-01

The research being carried out at Penn State by Winter and Alston addresses the fundamental atomic-collision processes of electron transfer, ionization, and excitation. Winter has focussed attention on intermediate and, more recently, higher collision energies -- proton energies of at least about 50 keV -- for which coupled-state approaches are appropriate. Alston has concentrated on perturbative approaches to symmetric ion-ion/atom collisions at high energies and to asymmetric collisions at intermediate to high energies
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.
Energy and system size dependence of phi meson production in Cu+Cu and Au+Au collisions

Energy Technology Data Exchange (ETDEWEB)

STAR Coll

2008-10-28

We study the beam-energy and system-size dependence of {phi} meson production (using the hadronic decay mode {phi} {yields} K{sup +}K{sup -}) by comparing the new results from Cu + Cu collisions and previously reported Au + Au collisions at {radical}s{sub NN} = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented are from midrapidity (|y| < 0.5) for 0.4 < p{sub T} < 5 GeV/c. At a given beam energy, the transverse momentum distributions for {phi} mesons are observed to be similar in yield and shape for Cu + Cu and Au + Au colliding systems with similar average numbers of participating nucleons. The {phi} meson yields in nucleus-nucleus collisions, normalized by the average number of participating nucleons, are found to be enhanced relative to those from p + p collisions with a different trend compared to strange baryons. The enhancement for {phi} mesons is observed to be higher at {radical}s{sub NN} = 200 GeV compared to 62.4 GeV. These observations for the produced {phi}(s{bar s}) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems.
Collisions of polyatomic ions with surfaces: incident energy partitioning and chemical reactions

International Nuclear Information System (INIS)

Zabka, J.; Roithova, J.; Dolejsek, Z.; Herman, Z.

2002-01-01

transformed into the product ion translation energy varied with the incident angle between 18 - 45 % of the incident energy for the incident angle 40 o - 80 o with respect to the surface normal, respectively. The rest of the incident energy was absorbed by the surface. The only exception was the perfuloro-hydrocarbon SAM, where about 17 % of the incident energy was transformed into internal energy of the polyatomic projectile. The hydrocarbon SAM behaved very similarly as the stainless steel or carbon surfaces, covered by hydrocarbons. The peak of the angular distribution of the product ions showed a simple correlation between the parallel and perpendicular components of the velocities of the incident and product ions. Collisions of small polyatomic ions CD 5 + , CD 4 + , CD 3 + (from methane) with carbon HOPG (highly oriented pyrolytic graphite) surface were investigated at room and elevated (600 o C) temperature of the surface. At the room temperature and collision energies of 7 - 52 eV, the main processes was inelastic dissociation of the projectile ion and chemical reactions with surface hydrocarbons. The main chemical product with CD 4 + projectiles was CD 4 H - (H-atom transfer) and its dissociation products, and formation of C 2 X 3 + and C 3 X 3 + (X 0 H 2 D) in reactions with terminal groups of the surface hydrocarbons. Complementary experiments with CH 4 - and 13 CH 4 + enable determination of the fraction of the product from projectile ion-surface chemical reactions and surface sputtering. Translation energy and angular distributions of the product ions together with the isotopic scrambling data provided new information of the details of the ion-surface chemical processes. (author)
Expansion, thermalization, and entropy production in high-energy nuclear collisions

International Nuclear Information System (INIS)

Heiselberg, H.; Wang, X.

1996-01-01

The thermalization process is studied in an expanding parton gas using the Boltzmann equation with two types of collision terms. In the relaxation time approximation we determine the criteria under which a time-dependent relaxation time leads to thermalization of the partons. We calculate the entropy production due to collisions for the general time-dependent relaxation time. In a perturbative QCD approach on the other hand, we can, given the initial conditions, estimate the effective relaxation time due to elastic collisions; this will be an upper limit only since radiative processes will also contribute to thermalization. We find that the parton gas does thermalize eventually but only after having undergone a phase of free streaming and gradual equilibration where considerable entropy is produced (open-quote open-quote after burning close-quote close-quote). The final entropy and thus particle density depends on the collision time as well as the initial conditions (a open-quote open-quote memory effect close-quote close-quote). Results for entropy production are presented based upon various model estimates of early parton production. copyright 1996 The American Physical Society
Bose-Einstein Interferometry in High-Energy Hadron-Hadron Collisions

International Nuclear Information System (INIS)

Kulka, K.

1987-01-01

Bose-Einstein interference is observed at the Axial Field Spectrometer at the CERN ISR, in pp, pp and /alpha//alpha/ collisions. The existence of the correlations is established both for equally charged pions and kaons. The radial extension of the boson emitting region is determined, and is, for identical pions, found to increase with the mean charged multiplicity of the events. In pp and pp interactions, a prolate shape of the pion source is revealed, with the beam axis as symmetry axis. For /alpha//alpha/ collisions, data are consistent with a spherical emission region. (author)

Time resolved laser induced fluorescence on argon intermediate pressure microwave discharges: Measuring the depopulation rates of the 4p and 5p excited levels as induced by electron and atom collisions

Science.gov (United States)

Palomares, J. M.; Graef, W. A. A. D.; Hübner, S.; van der Mullen, J. J. A. M.

2013-10-01

The reaction kinetics in the excitation space of Ar is explored by means of Laser Induced Fluorescence (LIF) experiments using the combination of high rep-rate YAG-Dye laser systems with a well defined and easily controllable surfatron induced plasma setup. The high rep-rate favors the photon statistics while the low energy per pulse avoids intrusive plasma laser interactions. An analysis shows that, despite the low energy per pulse, saturation can still be achieved even when the geometrical overlap and spectral overlap are optimal. Out of the various studies that can be performed with this setup we confine the current paper to the study of the direct responses to the laser pump action of three 4p and one 5p levels of the Ar system. By changing the plasma in a controlled way one gets for these levels the rates of electron and atom quenching and therewith the total destruction rates of electron and atom collisions. Comparison with literature shows that the classical hard sphere collision rate derived for hydrogen gives a good description for the observed electron quenching (e-quenching) in Ar whereas for heavy particle quenching (a-quenching) this agreement was only found for the 5p level. An important parameter in the study of electron excitation kinetics is the location of the boundary in the atomic system for which the number of electron collisions per radiative life time equals unity. It is observed that for the Ar system this boundary is positioned lower than what is expected on grounds of H-like formulas.
[Studies of target fragmentation in intermediate energy, relativistic and ultra-relativistic nuclear collisions

International Nuclear Information System (INIS)

Loveland, W.D.

1991-08-01

The work described herein is part of a project involving the study of low energy ( 250 MeV/A) heavy ion reactions. In the low energy regime, we published a monograph on the properties of the heaviest elements and used that publication as a basis for making a set of ''best'' semi-empirical predictions of heavy element decay properties. The intermediate energy research effort focussed upon the completion of studies already begun and the initiation of a number of new experiments. In our study of a interaction of 21 MeV/nucleon 129 Xe with 197 Au, we compared the characteristics of the observed deep inelastic phenomena with various models of dissipative reactions and found significant discrepancies between observations and predictions. These discrepancies seemed to be caused by an improper treatment of pre-equilibrium in the early stages of the collision. In our study of the relativistic interaction of 400 MeV/nucleon 12 C with 197 Au, we reported the first direct physical measurement of the properties of the spallation residues from a nucleus-nucleus collision. We found the residue energies to be much lower than those predicted by the intranuclear cascade model, indicating some substantial modifications of that model are needed. But, we also found, indications of significant, non-zero values of the residue transverse momentum, a finding that calls into question the interpretation of a number of radiochemical recoil studies of the kinematics of high energy reactions. A program of performing numerical simulations of intermediate and high energy nuclear collisions using the QMD model was initiated
Determination of the excitation energy and angular momentum of the quasi-projectiles produced in the heavy ion collisions Xe + Sn

International Nuclear Information System (INIS)

Genouin-Duhamel, Emmanuel

1999-01-01

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

International Nuclear Information System (INIS)

Roser, T.

2001-01-01

The Brookhaven Relativistic Heavy Ion Collider (RHIC) provides the unique opportunity to collide polarized proton beams at a center-of-mass energy of up to 500 GeV and luminosities of up to 2 x 10 32 cm -2 s -1 . Such high luminosity and high energy polarized proton collisions will open up the possibility of studying spin effects in hard processes. However, the acceleration of polarized beams in circular accelerators is complicated by the numerous depolarizing spin resonances. Using a partial Siberian snake and a rf dipole that ensure stable adiabatic spin motion during acceleration has made it possible to accelerate polarized protons to 25 GeV at the Brookhaven AGS. After successful operation of RHIC with gold beams polarized protons from the AGS have been successfully injected into RHIC and accelerated using a full Siberian snakes built from four superconducting helical dipoles. A new high energy proton polarimeter was also successfully commissioned. Operation with two snakes per RHIC ring is planned for next year
Jet-Hadron Correlations in √sNN =200 GeV p +p and Central Au +Au Collisions

Science.gov (United States)

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

2014-03-01

Azimuthal angular correlations of charged hadrons with respect to the axis of a reconstructed (trigger) jet in Au +Au and p +p collisions at √sNN =200 GeV in STAR are presented. The trigger jet population in Au +Au collisions is biased toward jets that have not interacted with the medium, allowing easier matching of jet energies between Au +Au and p +p collisions while enhancing medium effects on the recoil jet. The associated hadron yield of the recoil jet is significantly suppressed at high transverse momentum (pTassoc) and enhanced at low pTassoc in 0%-20% central Au +Au collisions compared to p +p collisions, which is indicative of medium-induced parton energy loss in ultrarelativistic heavy-ion collisions.
Collision-induced absorption intensity redistribution and the atomic pair polarizabilities

International Nuclear Information System (INIS)

Bulanin, M. O.

1997-01-01

A modified relation between the trace polarizability of a diatom and the S(-2) dipole sum is proposed that accounts for the effect of atomic collisions on the dipole oscillator strength distribution. Contribution to the collision-induced trace due to redistribution in the ionization continuum of Ar is evaluated and is found to be significant
Transverse Energy in nucleus-nucleus collisions: A review

International Nuclear Information System (INIS)

Tincknell, M.

1988-01-01

The status of Transverse Energy (E/sub T/) in relativistic nucleus-nucleus collisions at the Brookhaven AGS and the CERN SPS is reviewed. The definition of E/sub T/ and its physical significance are discussed. The basic techniques and limitations of the experimental measurements are presented. The acceptances of the major experiments to be discussed are shown, along with remarks about their idiosyncrasies. The data demonstrate that the nuclear geometry of colliding spheres primarily determines the shapes of the observed spectra. Careful account of the acceptances is crucial to comparing and interpreting results. It is concluded that nuclear stopping power is high, and that the amount of energy deposited into the interaction volume is increasing with beam energy even at SPS energies. The energy densities believed to be obtained at the SPS are close to the critical values predicted for the onset of a quark-gluon plasma. 25 refs., 8 figs
Expectations for ultra-high energy interactions

International Nuclear Information System (INIS)

Feynman, R.P.

1978-01-01

Strong interactions at ultra-high energies are discussed with emphasis on the hadrons produced in high energy collisions. Evidence is considered that quantum chromodynamics might be the right theory, and also some estimates are given of quantum chromodynamics asymptotic-freedom phenomena, the work under discussion being very preliminary. 6 references
Determination of the rate of energy partition in deeply inelastic collisions

International Nuclear Information System (INIS)

Lazzarini, A.; Vandenbosch, R.

1984-01-01

We discuss how excitation energy is partitioned in a deeply inelastic collision. Using the nucleon exchange mechanism for the deep inelastic scattering process, it is possible to draw on existing information about the evolution of the charge and mass distributions with energy loss and combine this with recent information on the partition of excitation energy in deeply inelastic collisions to obtain rates of heating for the two reaction partners
Angular correlations and fragmentation in intermediate energy heavy ion collisions

International Nuclear Information System (INIS)

Kristiansson, Anders.

1990-05-01

Intermediate energy heavy-ion collisions have been studied from 35 A MeV up to 94 A MeV at various accelerators. Angular correlations between light particles and detection of projectile- and target-fragments have been used to investigate the reaction mechanisms in this transition region between low- and high energy. An excess of correlations is observed in the particle-particle elastic scattering plane. This excess increases with particle mass and can be understood in terms of momentum conservation. The fragmentation measurements gives an indication that both energy and momentum transfer to the spectator volumes does occur. (author)
(Studies of target fragmentation in intermediate energy, relativistic and ultra-relativistic nuclear collisions)

Energy Technology Data Exchange (ETDEWEB)

Loveland, W.D.

1991-08-01

The work described herein is part of a project involving the study of low energy (< 10 MeV/A), intermediate energy (10--100 MeV/A) and relativistic (> 250 MeV/A) heavy ion reactions. In the low energy regime, we published a monograph on the properties of the heaviest elements and used that publication as a basis for making a set of best'' semi-empirical predictions of heavy element decay properties. The intermediate energy research effort focussed upon the completion of studies already begun and the initiation of a number of new experiments. In our study of a interaction of 21 MeV/nucleon {sup 129}Xe with {sup 197}Au, we compared the characteristics of the observed deep inelastic phenomena with various models of dissipative reactions and found significant discrepancies between observations and predictions. These discrepancies seemed to be caused by an improper treatment of pre-equilibrium in the early stages of the collision. In our study of the relativistic interaction of 400 MeV/nucleon {sup 12}C with {sup 197}Au, we reported the first direct physical measurement of the properties of the spallation residues from a nucleus-nucleus collision. We found the residue energies to be much lower than those predicted by the intranuclear cascade model, indicating some substantial modifications of that model are needed. But, we also found, indications of significant, non-zero values of the residue transverse momentum, a finding that calls into question the interpretation of a number of radiochemical recoil studies of the kinematics of high energy reactions. A program of performing numerical simulations of intermediate and high energy nuclear collisions using the QMD model was initiated.
Transverse energy production in 208Pb+Pb collisions at 158 GeV per nucleon

International Nuclear Information System (INIS)

Alber, T.; Appelshaeuser, H.; Baechler, J.; Bartke, J.; Bialkowska, H.; Bieser, F.; Bloomer, M.A.; Blyth, C.O.; Bock, R.; Bormann, C.; Brady, F.P.; Brockmann, R.; Buncic, P.; Caines, H.L.; Cebra, D.; Chan, P.; Cooper, G.E.; Cramer, J.G.; Cramer, P.B.; Csato, P.; Derado, I.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Euler, S.; Ferguson, M.I.; Fischer, H.G.; Fodor, Z.; Foka, P.; Freund, P.; Fuchs, M.; Gal, J.; Gazdzicki, M.; Gladysz, E.; Grebieszkow, J.; Guenther, J.; Harris, J.W.; Heck, W.; Hegyi, S.; Hill, L.A.; Huang, I.; Howe, M.A.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P.G.; Kadija, K.; Kecskemeti, J.; Kowalski, M.; Kuehmichel, A.; Lasiuk, B.; Margetis, S.; Mitchell, J.W.; Mock, A.; Nelson, J.M.; Odyniec, G.; Palinkas, J.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Poskanzer, A.M.; Prindle, D.J.; Puehlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Ritter, H.G.; Roehrich, D.; Rudolph, H.; Runge, K.; Sandoval, A.; Sann, H.; Schaefer, E.; Schmitz, N.; Schoenfelder, S.; Seyboth, P.; Seyerlein, J.; Sikler, F.; Skrzypczak, E.; Stock, R.; Stroebele, H.; Szentpetery, I.; Sziklai, J.; Toy, M.; Trainor, T.A.; Trentalange, S.; Vassiliou, M.; Vesztergombi, G.; Vranic, D.; Wenig, S.; Whitten, C.; Wienold, T.; Wood, L.; Zimanyi, J.; Zhu, X.; Zybert, R.

1995-01-01

Measurements of the forward and the transverse energy in 158 GeV per nucleon 208 Pb+Pb collisions are presented. A total transverse energy of about 1 TeV is created in central collisions. An energy density of about 3GeV/fm 3 is estimated for near head-on collisions. Only statistical fluctuations are seen in the ratio of electromagnetic to hadronic transverse energy. copyright 1995 The American Physical Society
Investigation of L X-ray intensity ratios in Pt induced by proton collisions

International Nuclear Information System (INIS)

Kaur, Manpuneet; Kaur, Mandeep; Mohan, Harsh; Jain, Arvind Kumar; Singh, Parjit S.; Vohra, Neelam; Sharma, Sunita

2015-01-01

A survey of literature on L X-ray parameters inspires us for taking up the present investigation. These parameters are useful to study atomic properties. In view of this, we report L X-ray intensity ratios for Pt, namely, L ℓ / L α , L β / L α and L γ / L α with proton collisions over the energy range 260 - 400 keV with an interval of 20 keV. The intention of research presented in this paper is to explore their energy dependence and comparison with theoretical calculations. These analyses will yield a data in the low energy region which assist in better clarity of proton induced X-ray emission phenomenon
Studies of QCD structure in high-energy collisions

Energy Technology Data Exchange (ETDEWEB)

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

2016-06-26

”Studies of QCD structure in high-energy collisions” is a research project in theoretical particle physics at Southern Methodist University funded by US DOE Award DE-SC0013681. The award furnished bridge funding for one year (2015/04/15-2016/03/31) between the periods funded by Nadolsky’s DOE Early Career Research Award DE-SC0003870 (in 2010-2015) and a DOE grant DE-SC0010129 for SMU Department of Physics (starting in April 2016). The primary objective of the research is to provide theoretical predictions for Run-2 of the CERN Large Hadron Collider (LHC). The LHC physics program relies on state-of-the-art predictions in the field of quantum chromodynamics. The main effort of our group went into the global analysis of parton distribution functions (PDFs) employed by the bulk of LHC computations. Parton distributions describe internal structure of protons during ultrarelivistic collisions. A new generation of CTEQ parton distribution functions (PDFs), CT14, was released in summer 2015 and quickly adopted by the HEP community. The new CT14 parametrizations of PDFs were obtained using benchmarked NNLO calculations and latest data from LHC and Tevatron experiments. The group developed advanced methods for the PDF analysis and estimation of uncertainties in LHC predictions associated with the PDFs. We invented and refined a new ’meta-parametrization’ technique that streamlines usage of PDFs in Higgs boson production and other numerous LHC processes, by combining PDFs from various groups using multivariate stochastic sampling. In 2015, the PDF4LHC working group recommended to LHC experimental collaborations to use ’meta-parametrizations’ as a standard technique for computing PDF uncertainties. Finally, to include new QCD processes into the global fits, our group worked on several (N)NNLO calculations.
Theory of low-energy electron-molecule collision physics in the coupled-channel method and application to e-CO2 scattering

International Nuclear Information System (INIS)

Morrison, M.A.

1976-08-01

A theory of electron-molecule scattering based on the fixed-nuclei approximation in a body-fixed reference frame is formulated and applied to e-CO 2 collisions in the energy range from 0.07 to 10.0 eV. The procedure used is a single-center coupled-channel method which incorporates a highly accurate static interaction potential, an approximate local exchange potential, and an induced polarization potential. Coupled equations are solved by a modification of the integral equations algorithm; several partial waves are required in the region of space near the nuclei, and a transformation procedure is developed to handle the consequent numerical problems. The potential energy is converged by separating electronic and nuclear contributions in a Legendre-polynomial expansion and including a large number of the latter. Formulas are derived for total elastic, differential, momentum transfer, and rotational excitation cross sections. The Born and asymptotic decoupling approximations are derived and discussed in the context of comparison with the coupled-channel cross sections. Both are found to be unsatisfactory in the energy range under consideration. An extensive discussion of the technical aspects of calculations for electron collisions with highly nonspherical targets is presented, including detailed convergence studies and a discussion of various numerical difficulties. The application to e-CO 2 scattering produces converged results in good agreement with observed cross sections. Various aspects of the physics of this collision are discussed, including the 3.8 eV shape resonance, which is found to possess both p and f character, and the anomalously large low-energy momentum transfer cross sections, which are found to be due to Σ/sub g/ symmetry. Comparison with static and static-exchange approximations are made
Low energy ion implantation and high energy heavy ion irradiation in C60 films

International Nuclear Information System (INIS)

Narayanan, K.L.; Yamaguchi, M.; Dharmarasu, N.; Kojima, N.; Kanjilal, D.

2001-01-01

C 60 films have been bombarded with low energy boron ions and high energy swift heavy ions (SHI) of silver and oxygen at different doses. Raman scattering and Fourier transform infrared (FTIR) studies were carried out on the virgin and irradiated films and the results are in good agreement with each other. The films subject to low energy boron ion implantation showed destruction of the bukky balls whereas the films subject to high energy ion irradiation did not show appreciable effects on their structure. These results indicate that C 60 films are more prone to defects by elastic collision and subsequent implantation at lower energy. Irradiation at higher energy was less effective in creating appreciable defects through electronic excitation by inelastic collisions at similar energy density
Low-Energy Charge Transfer in Multiply-Charged Ion-Atom Collisions Studied with the Combined SCVB-MOCC Approach

Directory of Open Access Journals (Sweden)

B. Zygelman

2002-03-01

Full Text Available A survey of theoretical studies of charge transfer involving collisions of multiply-charged ions with atomic neutrals (H and He is presented. The calculations utilized the quantum-mechanical molecular-orbital close-coupling (MOCC approach where the requisite potential curves and coupling matrix elements have been obtained with the spin-coupled valence bond (SCVB method. Comparison is made among various collision partners, for equicharged systems, where it is illustrated that even for total charge transfer cross sections, scaling-laws do not exist for low-energy collisions (i.e. < 1 keV/amu. While various empirical scaling-laws are well known in the intermediateand high-energy regimes, the multi-electron configurations of the projectile ions results in a rich and varied low-energy dependence, requiring an explicit calculation for each collision-partner pair. Future charge transfer problems to be addressed with the combined SCVB-MOCC approach are briefly discussed.
Mechanism of energy release from nucleus-target in hadron-nucleus collision

International Nuclear Information System (INIS)

Strugalski, Z.; Strugalska-Gola, E.

2000-01-01

The collisions of hadrons (protons, mesons) with 131 Xe nucleus and arising light nuclear fragments as nuclear refraction products have been observed in bubble chamber. Mechanism of energy release during these collisions has been discussed. The quantitative calculations has proved that this phenomena can be treated as potential energy source with use of many different target materials
Correlation effects on double electron capture in highly-charged, low-energy ion-atom collisions

International Nuclear Information System (INIS)

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

1987-01-01

The method of zero-degree Auger electron spectroscopy has been used to study two-electron excited states populated in slow double capture collisions of highly charged ions with He and H 2 . The focus of this study is on production of autoionization electrons originating from the non-equivalent 1s 2 2pnl electron configurations in comparison with electron production resulting from the Auger decay of (near) equivalent 1s 2 nln'l' (with n∼n') configurations. It is shown that production of non-equivalent electron configurations is significant and involves electron-electron correlation effects whose analysis leads beyond the independent-particle model. Recent results that include a measurement at non-zero angles are presented to illustrate the angular dependence of electron emission from non-equivalent electron configurations, as well as the dependence on projectile charge state and target species. Comparison of high resolution scans over two lines of the 1s 2 2pnl sequence for the O 6+ + He system with accurate transition energy calculations shows preferential population of high angular momentum substation
Investigation of rare particle production in high energy nuclear collisions. Progress report, December 15, 1997--December 14, 1998

International Nuclear Information System (INIS)

Crawford, H.J.; Engelage, J.

1998-01-01

The program is an investigation of the hadronization process through experimental measurement of rare particle production in high energy nuclear interactions. These interactions provide an environment similar in energy density to the conditions in the Big Bang. The authors are currently involved in two major experiments to study this environment, E896 at the AGS and STAR at RHIC. They have completed the first physics running of E896, a search for the H dibaryon and measurement of hyperon production in AuAu collisions, and are in the process of analyzing the data. They have prototyped the STAR trigger and are in the process of fabricating its components and installing them in the STAR detector

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)
Search for Fermi shuttle mechanisms in electron emission from atomic collision sequences

International Nuclear Information System (INIS)

Suarez, S.; Jung, M.; Rothard, H.; Schosnig, M.; Maier, R.; Clouvas, A.; Groeneveld, K.O.

1994-01-01

In electron spectra induced by slow heavy ion bombardment of solids a high energy tail can be observed, which is suggested to be explained by multiple collision sequences. In order to find those multiple collision effects like the ''Fermi shuttle'' acceleration mechanism we measured doubly differential electron emission cross sections for H + (33.5-700 keV) impact on different targets (He, Ne, C and Au) as a function of projectile energy and electron emission angle. We observed a surprising target dependence of the electron emission within the range of electron energies close to that of the binary encounter electrons for all observed angles of emission. (orig.)
Novel energy sharing collisions of multicomponent solitons

Indian Academy of Sciences (India)

2015-10-21

Oct 21, 2015 ... Abstract. In this paper, we discuss the fascinating energy sharing collisions of multicomponent solitons in certain incoherently coupled and coherently coupled nonlinear Schrödinger-type equations arising in the context of nonlinear optics.
Macroscopic damping model for zero degree energy distribution in ultra-relativistic heavy ion collisions

International Nuclear Information System (INIS)

Gao Chongshou; Wang Chengshing

1993-01-01

A macroscopic damping model is proposed to calculate the zero degree energy distribution in ultra-relativistic heavy ion collisions. The main features of the measured distributions are reproduced, good agreement is obtained in the middle energy region while overestimation results on the high energy side. The average energy loss coefficient of incident nucleons, varying in the reasonable region 0.2-0.6, depends on beam energy and target size
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
Direct integration multiple collision integral transport analysis method for high energy fusion neutronics

International Nuclear Information System (INIS)

Koch, K.R.

1985-01-01

A new analysis method specially suited for the inherent difficulties of fusion neutronics was developed to provide detailed studies of the fusion neutron transport physics. These studies should provide a better understanding of the limitations and accuracies of typical fusion neutronics calculations. The new analysis method is based on the direct integration of the integral form of the neutron transport equation and employs a continuous energy formulation with the exact treatment of the energy angle kinematics of the scattering process. In addition, the overall solution is analyzed in terms of uncollided, once-collided, and multi-collided solution components based on a multiple collision treatment. Furthermore, the numerical evaluations of integrals use quadrature schemes that are based on the actual dependencies exhibited in the integrands. The new DITRAN computer code was developed on the Cyber 205 vector supercomputer to implement this direct integration multiple-collision fusion neutronics analysis. Three representative fusion reactor models were devised and the solutions to these problems were studied to provide suitable choices for the numerical quadrature orders as well as the discretized solution grid and to understand the limitations of the new analysis method. As further verification and as a first step in assessing the accuracy of existing fusion-neutronics calculations, solutions obtained using the new analysis method were compared to typical multigroup discrete ordinates calculations
Fine-structure relaxation of O(3P) induced by collisions with He, H and H2

Science.gov (United States)

Lique, F.; Kłos, J.; Alexander, M. H.; Le Picard, S. D.; Dagdigian, P. J.

2018-02-01

The excitation of fine-structure levels of O(3P) by collisions is an important cooling process in the interstellar medium (ISM). We investigate here spin-orbit (de-)excitation of O(3Pj, j = 0, 1, 2) induced by collisions with He, H and H2 based on quantum scattering calculations of the relevant rate coefficients in the 10-1000 K temperature range. The underlying potential energy surfaces are derived from highly correlated abinitio calculations. Significant differences were found with the rate coefficients currently used in astrophysical applications. In particular, our new rate coefficients for collisions with H are up to a factor of 5 lower. Radiative transfer computations allow the assessment of the astrophysical impact of these new rate coefficients. In the case of molecular clouds, the new data are found to increase slightly the flux of the 3P1 → 3P2, while decreasing the flux of the 3P0 → 3P1 line. In the case of atomic clouds, the flux of both lines is predicted to decrease. The new rate coefficients are expected to impact significantly the modelling of cooling in astrophysical environments while also allowing new insights into oxygen chemistry in the ISM.
Avian collision risk models for wind energy impact assessments

International Nuclear Information System (INIS)

Masden, E.A.; Cook, A.S.C.P.

2016-01-01

With the increasing global development of wind energy, collision risk models (CRMs) are routinely used to assess the potential impacts of wind turbines on birds. We reviewed and compared the avian collision risk models currently available in the scientific literature, exploring aspects such as the calculation of a collision probability, inclusion of stationary components e.g. the tower, angle of approach and uncertainty. 10 models were cited in the literature and of these, all included a probability of collision of a single bird colliding with a wind turbine during passage through the rotor swept area, and the majority included a measure of the number of birds at risk. 7 out of the 10 models calculated the probability of birds colliding, whilst the remainder used a constant. We identified four approaches to calculate the probability of collision and these were used by others. 6 of the 10 models were deterministic and included the most frequently used models in the UK, with only 4 including variation or uncertainty in some way, the most recent using Bayesian methods. Despite their appeal, CRMs have their limitations and can be ‘data hungry’ as well as assuming much about bird movement and behaviour. As data become available, these assumptions should be tested to ensure that CRMs are functioning to adequately answer the questions posed by the wind energy sector. - Highlights: • We highlighted ten models available to assess avian collision risk. • Only 4 of the models included variability or uncertainty. • Collision risk models have limitations and can be ‘data hungry’. • It is vital that the most appropriate model is used for a given task.
Avian collision risk models for wind energy impact assessments

Energy Technology Data Exchange (ETDEWEB)

Masden, E.A., E-mail: elizabeth.masden@uhi.ac.uk [Environmental Research Institute, North Highland College-UHI, University of the Highlands and Islands, Ormlie Road, Thurso, Caithness KW14 7EE (United Kingdom); Cook, A.S.C.P. [British Trust for Ornithology, The Nunnery, Thetford IP24 2PU (United Kingdom)

2016-01-15

With the increasing global development of wind energy, collision risk models (CRMs) are routinely used to assess the potential impacts of wind turbines on birds. We reviewed and compared the avian collision risk models currently available in the scientific literature, exploring aspects such as the calculation of a collision probability, inclusion of stationary components e.g. the tower, angle of approach and uncertainty. 10 models were cited in the literature and of these, all included a probability of collision of a single bird colliding with a wind turbine during passage through the rotor swept area, and the majority included a measure of the number of birds at risk. 7 out of the 10 models calculated the probability of birds colliding, whilst the remainder used a constant. We identified four approaches to calculate the probability of collision and these were used by others. 6 of the 10 models were deterministic and included the most frequently used models in the UK, with only 4 including variation or uncertainty in some way, the most recent using Bayesian methods. Despite their appeal, CRMs have their limitations and can be ‘data hungry’ as well as assuming much about bird movement and behaviour. As data become available, these assumptions should be tested to ensure that CRMs are functioning to adequately answer the questions posed by the wind energy sector. - Highlights: • We highlighted ten models available to assess avian collision risk. • Only 4 of the models included variability or uncertainty. • Collision risk models have limitations and can be ‘data hungry’. • It is vital that the most appropriate model is used for a given task.
Electromagnetic radiation from nuclear collisions at RHIC energies

CERN Document Server

Turbide, Simon; Frodermann, Evan; Heinz, Ulrich

2008-01-01

The hot and dense strongly interacting matter created in collisions of heavy nuclei at RHIC energies is modeled with relativistic hydrodynamics, and the spectra of real and virtual photons produced at mid-rapidity in these events are calculated. Several different sources are considered, and their relative importance is compared. Specifically, we include jet fragmentation, jet-plasma interactions, the emission of radiation from the thermal medium and from primordial hard collisions. Our calculations consistently take into account jet energy loss, as evaluated in the AMY formalism. We obtain results for the spectra, the nuclear modification factor (R_AA), and the azimuthal anisotropy (v_2) that agree with the photon measurements performed by the PHENIX collaboration at RHIC.
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
State-to-state dynamics of H+HX collisions. II. The H+HX→HX/sup dagger/+H (X = Cl,Br,I) reactive exchange and inelastic collisions at 1.6 eV collision energy

International Nuclear Information System (INIS)

Aker, P.M.; Germann, G.J.; Tabor, K.D.; Valentini, J.J.

1989-01-01

We report measurement of product state distributions for the rotationally and/or vibrationally excited HX formed in collisions of translationally hot H atoms with HX (X = Cl, Br, and I) at 1.6 eV collision energy. The product state distributions are probed after only one collision of the fast H atom, using coherent anti-Stokes Raman scattering spectroscopy. Whether proceeding by inelastic collisions or reactive exchange, the transfer of translational energy to vibrational and rotational energy is quite inefficient in H+HX collisions at 1.6 eV. For all three hydrogen halides only 2--3% of the initial translational energy appears as HX vibration. For H+HCl only 6% of the initial energy is converted to HCl rotational energy, while for H+HBr and H+HI, this percentage is twice as large, 11--12%, but still small. The indistinguishability of the two H atoms involved makes it impossible to distinguish reactive exchange from inelastic energy transfer in these H+HX collisions. However, the difference in rotational energy partitioning for H+HBr and H+HI as compared with H+HCl, suggests that reactive exchange is dominant in the former and inelastic energy transfer dominates in the latter. The total cross sections for the combined energy transfer/reactive exchange do not change much with the identity of X, being 13 +- 3, 11 +- 2, and 11 +- 2 A 2 , for H+HCl, H+HBr, and H+HI, respectively
Neutral Pion Production in Proton+Proton Collisions at $\\sqrt{s}=8$ TeV and Insight into Hadron Production Mechanism

CERN Document Server

Yano, Satoshi

High transverse momentum particles play an important role for investigation of Quark-Gluon Plasma (QGP) induced by nucleus-nucleus collisions. When high transverse momentum partons traverse the QGP, they lose their energy. Consequently, the yield of high transverse momentum hadron is suppressed relative to proton+proton collisions scaled by the number of binary nucleon-nucleon collisions (jet quenching). The phenomenon is expected to give us much information about properties of QGP. Thus far, almost all models consider only parton energy loss during passing through. However, the perturbative Quantum Chromo Dynamics (QCD) predicts the direct hadron production (the higher-twist effect). If hadrons produced by this mechanism exist, the hadron energy loss should be considered additionally. For checking if there is the higher-twist effect, investigation of hadron production in proton+proton collisions is suitable. The invariant differential cross sections for inclusive neutral pion at midrapidity are measured in p...
Results of searches for the nucleon structure displays in high energy hadron-nucleus collisions

International Nuclear Information System (INIS)

Strugalski, Z.

1984-01-01

Hadron-nucleus collision data at projectile energy from a few GeV up to about eight thousand GeV were analysed in order to find effects in which a nucleon structure manifests itself. It was found that some nucleon structure displays in incident hadron deflection in its passage through atomic nuclei and in multiple production process, at energies above about 2 GeV. The distribution of the deflection angles consists of two components, the mean free path for multiparticle production is about three times larger than the expected one. These effects may be interpreted as caused by a nucleon structure
Hands on CERN an education project on the Internet using real high energy particle collisions

CERN Document Server

Johansson, E K

1999-01-01

An educational project primarily aimed at teachers and 15 to 18 year- old students describing the essential features of a modern high energy physics experiment has been created. The whole education package is available on the Internet. It gives a detailed description of the physics processes involved and the Standard Model of Microcosm. Real particle collisions produced with the facilities at the European particle physics laboratory (CERN) are displayed using the platform-independent programming language Java, enabling interaction with the user. The project has been used by several groups of teachers and students, and has increased their knowledge of, and interest in, particle physics. This project complements the traditional physics education and introduces students to contemporary fundamental physics. (7 refs).
A high-resolution tandem mass spectrometer for the collision-induced dissociation of large molecule ions

International Nuclear Information System (INIS)

Ouwerkerk, C.E.D.

1988-01-01

Instrumental development in the field of tandem mass spectrometry is described in order to use the technique for the analysis of large organic molecules. Experiments are also described in which the process of collision-induced dissociation (CID) is investigated. The fragmentation pattern of CH 4 + has been measured for three different target gases He, Ar and Xe. From these measurements fragmentation cross sections are calculated. 192 refs.; 47 figs.; 6 tabs
Characteristics of violent collisions in Ar-induced reactions at intermediaire energies

International Nuclear Information System (INIS)

Rivet, M.F.; Borderie, B.

1984-01-01

We report on two experiments performed with the Ganil facility using the 27 MeV/u Ar beam. The first one concerns an intermediate mass system, Ar + Ag. For the second one a heavier fissile system, Ar + U, was chosen. For Ar + Ag information about fusion requires the measurements of evaporation residues and fission. In the Ar + U reaction, most of the collisions lead to fission. The violence of the collision is therefore determined from the correlation angle of the coincidence fission fragments
What can we learn from the directed flow in heavy-ion collisions at BES RHIC energies?

Energy Technology Data Exchange (ETDEWEB)

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

2016-01-15

Analysis of directed flow (v{sub 1}) of protons, antiprotons and pions in heavy-ion collisions is performed in the range of collision energies √(s{sub NN}) = 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 the most part of experimental data in this energy range. The directed flow indicates that the crossover deconfinement transition takes place in semicentral Au+Au collisions in a wide range of collision energies 4 high baryon densities than those used in the calculation. The latter finding is in agreement with that discussed in astrophysics. (orig.)
Quark condensation, induced symmetry breaking and color superconductivity at high density

International Nuclear Information System (INIS)

Langfeld, Kurt; Rho, Mannque

1999-01-01

The phase structure of hadronic matter at high density relevant to the physics of compact stars and relativistic heavy-ion collisions is studied in a low-energy effective quark theory. The relevant phases that figure are (1) chiral condensation, (2) diquark color condensation (color superconductivity) and (3) induced Lorentz-symmetry breaking (''ISB''). For a reasonable strength for the effective four-Fermi current-current interaction implied by the low-energy effective quark theory for systems with a Fermi surface we find that the ''ISB'' phase sets in together with chiral symmetry restoration (with the vanishing quark condensate) at a moderate density while color superconductivity associated with scalar diquark condensation is pushed up to an asymptotic density. Consequently, color superconductivity seems rather unlikely in heavy-ion collisions although it may play a role in compact stars. Lack of confinement in the model makes the result of this analysis only qualitative but the hierarchy of the transitions we find seems to be quite robust
Manifestation of jet quenching in differential distributions of the total transverse energy in nucleus-nucleus collisions

International Nuclear Information System (INIS)

Savina, M.V.; Shmatov, S.V.; Slavin, N.V.; Zarubin, P.I.

1998-01-01

In the framework of the HIJING model, global characteristics of nucleus-nucleus collisions are studied for a Large Hadron Collider (LHC) energy scale. An interesting model prediction is the presence of a central bump over a pseudorapidity plateau of a total transverse energy distribution. The bump is induced by a jet quenching effect in a dense nuclear matter. It is shown that a wide acceptance calorimeter with a pseudorapidity coverage -5<η<5 allows one to obtain experimental confirmation of such an effect

Antimatter production in proton-proton and heavy-ion collisions at ultrarelativistic energies

International Nuclear Information System (INIS)

Cleymans, J.; Kabana, S.; Kraus, I.; Oeschler, H.; Redlich, K.; Sharma, N.

2011-01-01

One of the striking features of particle production at high beam energies is the near-equal abundance of matter and antimatter in the central rapidity region. In this paper we study how this symmetry is reached as the beam energy is increased. In particular, we quantify explicitly the energy dependence of the approach to matter-antimatter symmetry in proton-proton and in heavy-ion collisions. Expectations are presented also for the production of more complex forms of antimatter such as antihypernuclei.
Jet-hadron correlations in √[s(NN)]=200 GeV p+p and central Au+Au collisions.

Science.gov (United States)

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

2014-03-28

Azimuthal angular correlations of charged hadrons with respect to the axis of a reconstructed (trigger) jet in Au+Au and p+p collisions at √[s(NN)]=200 GeV in STAR are presented. The trigger jet population in Au+Au collisions is biased toward jets that have not interacted with the medium, allowing easier matching of jet energies between Au+Au and p+p collisions while enhancing medium effects on the recoil jet. The associated hadron yield of the recoil jet is significantly suppressed at high transverse momentum (pTassoc) and enhanced at low pTassoc in 0%-20% central Au+Au collisions compared to p+p collisions, which is indicative of medium-induced parton energy loss in ultrarelativistic heavy-ion collisions.
Theoretical aspects of high energy elastic nucleon scattering

CERN Document Server

Kundrat, Vojtech; Lokajicek, Milos

2010-01-01

The eikonal model must be denoted as strongly preferable for the analysis of elastic high-energy hadron collisions. The given approach allows to derive corresponding impact parameter profiles that characterize important physical features of nucleon collisions, e.g., the range of different forces. The contemporary phenomenological analysis of experimental data is, however, not able to determine these profiles unambiguously, i.e., it cannot give the answer whether the elastic hadron collisions are more central or more peripheral than the inelastic ones. However, in the collisions of mass objects (like protons) the peripheral behavior of elastic collisions should be preferred.
New parameter-free polarization potentials in low-energy positron collisions

Science.gov (United States)

Jain, Ashok

1990-01-01

The polarization potential plays a decisive role in shaping up the cross sections in low energy positron collisions with atoms and molecules. However, its inclusion without involving any adjustable parameter, is still a challenge. Various other techniques employed so far for positron collisions are summarized, and a new, nonadjustable and very simple form of the polarization potential for positron-atom (molecule) collisions below the threshold of positronium formation is discussed. This new recently proposed potential is based on the correlation energy of a single positron in a homogeneous electron gas. The correlation energy was calculated by solving the Schrodinger equation of the positron-electron system and fitted to an analytical form in various ranges of the density parameter. In the outside region, the correlation energy is joined smoothly with the correct asymptotic form. This new positron correlation polarization (PCOP) potential was tested on several atomic and molecular targets such as the Ar, CO, and CH4. The results on the total and differential cross sections on these targets are shown along with the experimental data where available.
Geometrical scaling in high energy hadron collisions

International Nuclear Information System (INIS)

Kundrat, V.; Lokajicek, M.V.

1984-06-01

The concept of geometrical scaling for high energy elastic hadron scattering is analyzed and its basic equations are solved in a consistent way. It is shown that they are applicable to a rather small interval of momentum transfers, e.g. maximally for |t| 2 for pp scattering at the ISR energies. (author)
Unified first principles description from warm dense matter to ideal ionized gas plasma: electron-ion collisions induced friction.

Science.gov (United States)

Dai, Jiayu; Hou, Yong; Yuan, Jianmin

2010-06-18

Electron-ion interactions are central to numerous phenomena in the warm dense matter (WDM) regime and at higher temperature. The electron-ion collisions induced friction at high temperature is introduced in the procedure of ab initio molecular dynamics using the Langevin equation based on density functional theory. In this framework, as a test for Fe and H up to 1000 eV, the equation of state and the transition of electronic structures of the materials with very wide density and temperature can be described, which covers a full range of WDM up to high energy density physics. A unified first principles description from condensed matter to ideal ionized gas plasma is constructed.
New results of novel long-range correlations in high-multiplicity pp collisions at 7 and 13 TeV from CMS

CERN Multimedia

CERN. Geneva

2015-01-01

In 2010, CMS reported the observation of a novel long-range two-particle angular correlation in high-multiplicity pp collisions at 7 TeV, where an enhanced correlation for particles emitted at similar azimuthal angle (phi) over a wide range in pseudorapidity (known as the ``ridge'') is observed. This ridge correlation phenomenon was not seen in pp collisions before but reminiscent of similar effect first seen in high-energy nucleus-nucleus collisions, which is attributed to collective flow of a strongly interacting, expanding quark-gluon medium. Later on, similar ridge correlations were also observed in high-multiplicity pPb collisions and studied in great detail by all LHC experiments. The start of the LHC run 2 brought new opportunities of exploring novel QCD emergent phenomena in pp collisions at the highest energy ever achieved. First CMS results on QCD physics in pp collisions at 13 TeV are presented and compared to the 7 TeV data. This includes the measurement of charged particle multipl...
High Energy Transport Code HETC

International Nuclear Information System (INIS)

Gabriel, T.A.

1985-09-01

The physics contained in the High Energy Transport Code (HETC), in particular the collision models, are discussed. An application using HETC as part of the CALOR code system is also given. 19 refs., 5 figs., 3 tabs
n l -> n' l' transition rates in electron and proton - Rydberg atom collision

Science.gov (United States)

Vrinceanu, Daniel

2017-04-01

Electrons and protons drive the recombination dynamics of highly excited Rydberg atoms in cold rarefied plasmas found in astrophysical conditions such as primordial recombination or star formation in H-II clouds. It has been recognized that collisions induce both energy and angular momentum transitions in Rydberg atoms, although in different proportions, depending on the initial state, temperature and the given species considered in the collision (electron or proton). Most studies focused on one collision type at a time, under the assumption that collision types are independent or their effects are not competing. The classical Monte-Carlo trajectory simulations presented in this work calculate the rates for both energy and angular momentum transfers and show their interdependence. For example, energy transfer with small angular momentum change are more efficient for target states with initial large angular momentum. The author acknowledges support received from the National Science Foundation through a Grant for the Center for Research on Complex Networks (HRD-1137732).
Emission of high-energy, light particles from intermediate-energy heavy-ion reactions

International Nuclear Information System (INIS)

Ball, J.B.; Auble, R.L.

1982-01-01

One of the early surprises in examining reaction products from heavy ion reactions at 10 MeV/nucleon and above was the large yield of light particles emitted and the high energies to which the spectra of these particles extended. The interpretation of the origin of the high energy light ions has evolved from a picture of projectile excitation and subsequent evaporation to one of pre-equilibrium (or nonequilibrium) emission. The time scale for particle emission has thus moved from one that occurs following the initial collision to one that occurs at the very early stages of the collision. Research at ORNL on this phenomenon is reviewed
Pion production - a probe for coherence in medium energy heavy ion collisions

International Nuclear Information System (INIS)

Stachel, J.

1985-01-01

Neutral pion production is observed in heavy ion collisions at beam energies as low as 25 MeV/u, where this process is consumming the major portion of the total center of mass energy available. At these low beam energies single nucleon nucleon collision models and also models that incorporate the cooperative sharing of the beam energy of several nucleons do not reproduce the data. Rather, the data presented here call for a fully coherent production mechanism. (orig.)
Three-hadron angular correlations in high-energy proton-proton and nucleus-nucleus collisions from perturbative QCD

International Nuclear Information System (INIS)

Ayala, Alejandro; Ortiz, Antonio; Paic, Guy; Jalilian-Marian, Jamal; Magnin, J.; Tejeda-Yeomans, Maria Elena

2011-01-01

We study three-hadron azimuthal angular correlations in high-energy proton-proton and central nucleus-nucleus collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider at midrapidity. We use the leading-order parton matrix elements for 2→3 processes and include the effect of parton energy loss in the quark-gluon plasma using the modified fragmentation function approach. For the case when the produced hadrons have either the same or not too different momenta, we observe two away-side peaks at 2π/3 and 4π/3. We consider the dependence of the angular correlations on energy loss parameters that have been used in studies of single inclusive hadron production at RHIC. Our results on the angular dependence of the cross section agree well with preliminary data by the PHENIX Collaboration. We comment on the possible contribution of 2→3 processes to dihadron angular correlations and how a comparison of the two processes may help characterize the plasma further.
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 ...
Study of new scaling of direct photon production in pp collisions at high energies using MC simulation

International Nuclear Information System (INIS)

Tokarev, M.V.; Potrebenikova, E.V.

1998-01-01

The new scaling, z scaling, of prompt photon production in pp collisions at high energies is studied. The scaling function H(z) is expressed via the inclusive cross section of photon production Ed 3 σ / dq 3 and the multiplicity density of charged particles, ρ (s), at pseudorapidity η = 0. Monte Carlo (MC) simulation based on the PYTHIA code is used to calculate the cross section and to verify the scaling. The MC technique used to construct the scaling function is described. The H (z) dependence on the scaling variable z, the center-of-mass energy √ s at a produced angle of θ = 90 deg is investigated. The predictions of the Ed 3 σ / dq 3 dependence on transverse momentum q at a colliding energy of √ s = 0.5, 5.0 and 14.0 TeV are made. The obtained results are compared with the experimental data and can be of interest for future experiments at RHIC (BNL). LHC (CERN), HERA (DESY) and Tevatron (Batavia)
High energy diets-induced metabolic and prediabetic painful polyneuropathy in rats.

Directory of Open Access Journals (Sweden)

Fang Xie

Full Text Available To establish the role of the metabolic state in the pathogenesis of polyneuropathy, an age- and sex-matched, longitudinal study in rats fed high-fat and high-sucrose diets (HFSD or high-fat, high-sucrose and high-salt diets (HFSSD relative to controls was performed. Time courses of body weight, systolic blood pressure, fasting plasma glucose (FPG, insulin, free fatty acids (FFA, homeostasis model assessment-insulin resistance index (HOMA-IR, thermal and mechanical sensitivity and motor coordination were measured in parallel. Finally, large and small myelinated fibers (LMF, SMF as well as unmyelinated fibers (UMF in the sciatic nerves and ascending fibers in the spinal dorsal column were quantitatively assessed under electron microscopy. The results showed that early metabolic syndrome (hyperinsulinemia, dyslipidemia, and hypertension and prediabetic conditions (impaired fasting glucose could be induced by high energy diet, and these animals later developed painful polyneuropathy characterized by myelin breakdown and LMF loss in both peripheral and central nervous system. In contrast SMF and UMF in the sciatic nerves were changed little, in the same animals. Therefore the phenomenon that high energy diets induce bilateral mechanical, but not thermal, pain hypersensitivity is reflected by severe damage to LMF, but mild damage to SMF and UMF. Moreover, dietary sodium (high-salt deteriorates the neuropathic pathological process induced by high energy diets, but paradoxically high salt consumption, may reduce, at least temporarily, chronic pain perception in these animals.
High Energy Diets-Induced Metabolic and Prediabetic Painful Polyneuropathy in Rats

Science.gov (United States)

Hou, Jun-Feng; Jiao, Kai; Costigan, Michael; Chen, Jun

2013-01-01

To establish the role of the metabolic state in the pathogenesis of polyneuropathy, an age- and sex-matched, longitudinal study in rats fed high-fat and high-sucrose diets (HFSD) or high-fat, high-sucrose and high-salt diets (HFSSD) relative to controls was performed. Time courses of body weight, systolic blood pressure, fasting plasma glucose (FPG), insulin, free fatty acids (FFA), homeostasis model assessment-insulin resistance index (HOMA-IR), thermal and mechanical sensitivity and motor coordination were measured in parallel. Finally, large and small myelinated fibers (LMF, SMF) as well as unmyelinated fibers (UMF) in the sciatic nerves and ascending fibers in the spinal dorsal column were quantitatively assessed under electron microscopy. The results showed that early metabolic syndrome (hyperinsulinemia, dyslipidemia, and hypertension) and prediabetic conditions (impaired fasting glucose) could be induced by high energy diet, and these animals later developed painful polyneuropathy characterized by myelin breakdown and LMF loss in both peripheral and central nervous system. In contrast SMF and UMF in the sciatic nerves were changed little, in the same animals. Therefore the phenomenon that high energy diets induce bilateral mechanical, but not thermal, pain hypersensitivity is reflected by severe damage to LMF, but mild damage to SMF and UMF. Moreover, dietary sodium (high-salt) deteriorates the neuropathic pathological process induced by high energy diets, but paradoxically high salt consumption, may reduce, at least temporarily, chronic pain perception in these animals. PMID:23451227
Quantum analysis in the transition process to excited state of an oxygen molecule induced by electron collisions; Denshi shototsu ni tomonau sanso bunshi ni okeru reiki jotai sen`i no ryoshironteki kaiseki

Energy Technology Data Exchange (ETDEWEB)

Ishimaru, K. [Gifu National College of Technology, Gifu (Japan); Okazaki, K. [Tokyo Inst. of Technology, Tokyo (Japan)

1996-06-25

For understanding of fundamental chemical reactions under a highly non equilibrium condition which is quite often used in plasma processing, the relevant atomic and molecular processes must be clarified. In this study, an analysis of the transition process to the excited state of an oxygen molecule induced by electron collisions in the oxygen plasma has been carried out. First, the electron density distribution in an oxygen molecule has been calculated using the extended Huckel molecular orbital method. Then, the electron potential energy distribution in the transition process to the excited state has been estimated. The electron behavior has been calculated using the estimated unidimensional electron potential energy distribution and unsteady quantum mechanics. As a result, the transition process to the excited state of an oxygen molecule induced by electron collisions and its conditions have been clarified qualitatively. 9 refs., 9 figs.
Antiproton production in heavy-ion collisions at energies below the threshold

International Nuclear Information System (INIS)

Schroeter, A.

1993-08-01

In the framework of this thesis the antiproton production in heavy ion collisions at projectile energies far below the threshold for anti p production in nucleon-nucleon collisions (5.63 GeV/u) was studied. A suited detection apparature was developed and constructed at the fragment separator-magnet spectrometer at the Society for Heavy Ion Research (GSI). For the identification of the antiprotons the momentum of the particles emitted in beam direction was measured and their velocity multiple-redundantly determined by means of time-of-flight measurements and threshold Cherenkov detectors. By this way the antiprotons could be in spite of low anti p production cross sections and high production rates for lighter particles (R anti p: R K - -:R π - -∼1:5*10 3 :10 7 ) background-freely determined. By this experiment for Ne+NaF, Cu, Sn, and Bi as well ass Ni+Ni collisions at incident energies between 1.6 GeV/u and 2.0 GeV/u production cross sections for antiprotons in the momentum range between 1.0 GeV/c and 2.2 GeV/c and for kaons and pions between 0.5 GeV/c and 2.8 GeV/c were measured, in order to study the influence of collisional-system size, incident energy, and secondary-particle momentum on the production probabilities and to contribute in comparison with the prognoses of theoretical models to the explanation of the particle production mechanisms. (HSI)
Single-collision studies of hot atom energy transfer and chemical reaction

International Nuclear Information System (INIS)

Valentini, J.J.

1991-01-01

This report discusses research in the collision dynamics of translationally hot atoms, with funding with DOE for the project ''Single-Collision Studies of Hot Atom Energy Transfer and Chemical Reaction,'' Grant Number DE-FG03-85ER13453. The work reported here was done during the period September 9, 1988 through October 31, 1991. During this period this DOE-funded work has been focused on several different efforts: (1) experimental studies of the state-to-state dynamics of the H + RH → H 2 R reactions where RH is CH 4 , C 2 H 6 , or C 3 H 8 , (2) theoretical (quasiclassical trajectory) studies of hot hydrogen atom collision dynamics, (3) the development of photochemical sources of translationally hot molecular free radicals and characterization of the high resolution CARS spectroscopy of molecular free radicals, (4) the implementation of stimulated Raman excitation (SRE) techniques for the preparation of vibrationally state-selected molecular reactants
LOCAL COLLISION SIMULATION OF AN SC WALL USING ENERGY ABSORBING STEEL

Directory of Open Access Journals (Sweden)

CHUL-HUN CHUNG

2013-08-01

Full Text Available This study evaluates the local damage of a turbine in an auxiliary building of a nuclear power plant due to an external impact by using the LS-DYNA finite element program. The wall of the auxiliary building is SC structure and the material of the SC wall plate is high manganese steel, which has superior ductility and energy absorbance compared to the ordinary steel used for other SC wall plates. The effects of the material of the wall, collision speed, and angle on the magnitude of the local damage were evaluated by local collision analysis. The analysis revealed that the SC wall made of manganese steel had significantly less damage than the SC wall made of ordinary steel. In conclusion, an SC wall made of manganese steel can have higher effective resistance than an SC wall made of ordinary steel against the local collision of an airplane engine or against a turbine impact.

Local Collision Simulation of an SC Wall Using Energy Absorbing Steel

Energy Technology Data Exchange (ETDEWEB)

Chung, Chulhun; Choi, Hyun; Park, Jaegyun [Dankook Univ., Yongin (Korea, Republic of)

2013-08-15

This study evaluates the local damage of a turbine in an auxiliary building of a nuclear power plant due to an external impact by using the LS-DYNA finite element program. The wall of the auxiliary building is SC structure and the material of the SC wall plate is high manganese steel, which has superior ductility and energy absorbance compared to the ordinary steel used for other SC wall plates. The effects of the material of the wall, collision speed, and angle on the magnitude of the local damage were evaluated by local collision analysis. The analysis revealed that the SC wall made of manganese steel had significantly less damage than the SC wall made of ordinary steel. In conclusion, an SC wall made of manganese steel can have higher effective resistance than an SC wall made of ordinary steel against the local collision of an airplane engine or against a turbine impact.
Diabatic emission of neutrons: A probe for the energy dissipation mechanism in nucleus-nucleus collisions

International Nuclear Information System (INIS)

Noerenberg, W.; Cassing, W.

1984-05-01

The precompound emission of neutrons in central nucleus-nucleus collisions is investigated within the framework of dissipative diabatic dynamics. For 92 Mo + 92 Mo at bombarding energies between 7.5 and 20 MeV/u the differential neutron multiplicities dMsub(n)/dEsub(n) are estimated from the decay of highly excited diabatic single-particle states. The energy spectra have an almost exponential high-energy tail with effective temperatures up to 10 MeV for 20 MeV/u bombarding energy. (orig.)
Excitation of atoms and molecules in collisions with highly charged ions

International Nuclear Information System (INIS)

Watson, R.L.

1991-01-01

Much of the work this year has been directed toward studies of charge exchange and ionization in single collisions of heavy ions with gaseous atoms and molecules. A study of the double ionization of He by high energy N 7+ ions, which began last year, was extended up in energy to 40 MeV/amu. These measurements verified the deviations from the predictions of theory observed in our previous work and indicated that the energy required to reach the limiting value of the ratio of double-to-single ionization cross sections may be as high as 70 MeV/amu
Energy-exchange collisions of dark-bright-bright vector solitons.

Science.gov (United States)

Radhakrishnan, R; Manikandan, N; Aravinthan, K

2015-12-01

We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices.
High energy photons production in nuclear reactions

International Nuclear Information System (INIS)

Nifenecker, H.; Pinston, J.A.

1990-01-01

Hard photon production, in nucleus-nucleus collisions, were studied at beam energies between 10 and 125 MeV. The main characteristics of the photon emission are deduced. They suggest that the neutron-proton collisions in the early stage of the reaction are the main source of high energy gamma-rays. An overview of the theoretical approaches is given and compared with experimental results. Theoretical attempts to include the contribution of charged pion exchange currents to photon production, in calculations of proton-nucleus-gamma and nucleus-nucleus-gamma reactions, showed suitable fitting with experimental data
Energy and orientation dependence of electron-irradiation-induced defects in InP

International Nuclear Information System (INIS)

Sibille, A.; Suski, J.; LeRoux, G.

1984-01-01

The concentration of several electron-irradiation-induced deep defect levels in InP has been measured by deep-level transient spectroscopy (DLTS) as a function of electron energy. The dominant centers exhibit a threshold at about 100 keV, which clearly points to a primary production event by electron--phosphorus-atom collision. This unambiguous determination allowed a test of the recently proposed orientation dependence technique to find the nature of the sublattice involved in the collision process for III-V compounds. A good quantitative agreement is obtained with a hard-sphere model for secondary collisions if disorientation of the beam in the sample is taken into account. Other traps exhibit higher thresholds which correspond either to indium-atom displacements or to the involvement of secondary collisions in the production event
Jets in d (p )-A collisions: Color transparency or energy conservation

Science.gov (United States)

Kordell, Michael; Majumder, Abhijit

2018-05-01

The production of jets, and high momentum hadrons from jets, produced in deuteron-Au (d -Au) collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and proton-Pb (p -Pb) collisions at the CERN Large Hadron Collider (LHC) are studied as a function of centrality, a measure of the impact parameter of the collision. A modified version of the event generator pythia, widely used to simulate p -p collisions, is used in conjunction with a nuclear Monte Carlo event generator which simulates the locations of the nucleons within a large nucleus. We demonstrate how events with a hard jet may be simulated, in such a way that the parton distribution function of the projectile is "frozen" during its interaction with the extended nucleus. Using our approach, we demonstrate that the puzzling enhancement seen in peripheral events at RHIC and the LHC, as well as the suppression seen in central events at the LHC, are possibly due to mis-binning of central and semicentral events, containing a jet, as peripheral events. This occurs due to the suppression of soft particle production away from the jet, caused by the depletion of energy available in a nucleon of the deuteron (in d -Au at RHIC) or in the proton (in p -Pb at LHC), after the production of a hard jet. We conclude that partonic correlations built out of simple energy conservation are responsible for such an effect, though these are sampled at the hard scale of jet production and, as such, represent smaller states.
Unitarity corrections and high field strengths in high energy hard collisions

International Nuclear Information System (INIS)

Kovchegov, Y.V.; Mueller, A.H.

1997-01-01

Unitarity corrections to the BFKL description of high energy hard scattering are viewed in large N c QCD in light-cone quantization. In a center of mass frame unitarity corrections to high energy hard scattering are manifestly perturbatively calculable and unrelated to questions of parton saturation. In a frame where one of the hadrons is initially at rest unitarity corrections are related to parton saturation effects and involve potential strengths A μ ∝1/g. In such a frame we describe the high energy scattering in terms of the expectation value of a Wilson loop. The large potentials A μ ∝1/g are shown to be pure gauge terms allowing perturbation theory to again describe unitarity corrections and parton saturation effects. Genuine nonperturbative effects only come in at energies well beyond those energies where unitarity constraints first become important. (orig.)
Some interesting features of charged particles produced in high-energy hadron-emulsion collisions

International Nuclear Information System (INIS)

Khushnood, H.; Ansari, A.R.

1990-01-01

The emission characteristics of secondary charged particles produced in 400 GeV proton-emulsion interactions were compared with those obtained at other energies. The results revealed that the angular distribution of grey particles does not depend on the nature and energy of the projectile. The dependence of the average multiplicity of the grey, black, shower, and heavily ionizing tracks on the mass of the target nucleus (A) and the nature and energy of the projectiles are also examined. The ratio of the valance quarks in pions (π - ) and protons (p) was found to be almost equal to the ratio of the grey particles produced in π - -A and p-A collisions at the same energy. The values of the normalized moments of the multiplicity distributions of charged shower particles in different N h intervals were found to nearly the same. However, this value increased with increasing values of the moment index, K. Finally, the values of the normalized and central moments were almost equal for both p-p and p-A interactions
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)
[Reactive collisions of high-temperature systems

International Nuclear Information System (INIS)

Graff, M.M.

1990-01-01

The object of this research is to study reactivity at superthermal collision energies using a fast neutral beam that is generated by photodetachment. Systems scheduled for initial study include basic oxygen-hydrogen reactions. Unfortunately, we can not yet report realization of this goal, but during this funding period we have made advances that are anticipated to lead to successful measurements during the next year. The parameters described below refer to the model system O + H 2 → OH + H. The basic design involves the collision of fast neutrals, created by photodetachment of the corresponding negative molecular ion, with a stable reactant gas in a collision cell. Products are detected by ionization and mass analysis. We are equipped to study rotational effects on reactivity by comparing results for rotational levels J = 0 and 1 of H 2 . Highlights during the funding period are given in this report
QCD and high-energy nuclear collisions

CERN Multimedia

CERN. Geneva

2007-01-01

Six years ago, Relativistic Heavy Ion Collider at Brookhaven started colliding heavy nuclei at record center-of-mass energies of up to 200 GeV/nucleon. Very soon, the Large Hadron Collider at CERN will push the energy of the ions to an astounding 5 TeV/nucleon. What can be learnt from the experiments at these machines? What do we know about the physics of super--dense matter already? I will argue that heavy ion accelerators bring us to the new frontiers of physical knowledge by creating strong color fields and very high densities of partons, at which qualitatively new phenomena emerge. I will also discuss the cross-disciplinary implications for cosmology, astrophysics, and connections to condensed matter physics.
Chemical freeze-out study in proton-proton collisions at RHIC and LHC energies

International Nuclear Information System (INIS)

Das, Sabita; Mishra, Debadeepti; Mohanty, Bedangadas; Chatterjee, Sandeep

2016-01-01

Particle multiplicities measured at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) facilities can be used to understand the chemical freeze-out dynamics. At chemical freeze-out (CFO), inelastic collisions cease and the freeze-out parameters can be determined using measured particle multiplicities within the framework of a statistical model. The statistical model has proven to be quite successful in describing the particle production from elementary p-p and e"+e"- collisions up to heavy-ion collisions. It helps to do a systematic study of the centrality and energy dependence of freeze-out parameters in heavy-ion collisions from lower SPS to higher LHC energies. The new data at LHC along with the RHIC data can be used to do such a systematic study in proton-proton collisions
New results on nuclear multifragmentation in nucleon-nucleus and nucleus-nucleus collisions at relativistic energies

International Nuclear Information System (INIS)

Besliu, Calin; Jipa, Alexandru; Iliescu, Bogdan; Felea, Daniel

2002-01-01

Some new aspects on the multifragmentation processes in nucleus-nucleus and nucleon-nucleus collisions at high energies are discussed in this work. Experimental data obtained in international collaborations (for example, MULTI Collaboration with KEK Tsukuba (Japan) and SKM 200 Collaboration with JINR Dubna (Russia)) are used to discuss new mechanisms in the target nucleus fragmentation. Correlations with stopping power, participant region size and energy density are included. Comparisons of the experimental results with the predictions of a phenomenological geometric model of intermediate mass fragment multiplicity, caloric curves and angular distributions are also presented. These results are used for global description of the multifragmentation processes in nucleon-nucleus and nucleus-nucleus collisions at relativistic energies. The size of the participant region and the average intermediate mass fragments multiplicity are taken into consideration using the free space probability. A few correlations between the deposited energy in the participant region and stability state of the intermediate mass fragments are presented in this work. The importance of the collision geometry in the multifragmentation processes is stressed. The results suggest different time moments for the incident nucleus fragmentation and for the target nucleus fragmentation. The associated entropies are distinct. (authors)
Investigation of the Direct Charge Transfer in Low Energy D2+ + H Collisions using Merged-Beams Technique

Science.gov (United States)

Romano, S. L.; Guillen, C. I.; Andrianarijaona, V. M.; Havener, C. C.

2011-10-01

is obtained by photo-detachment of H-. Our first measurements are presented in Fig. 1 along with the theories and previous experiments. The collision is rovibrationally frozen at high energy where our measurements are seen to be in good agreement with the high energy theory. Both measurements and low energy theory increase toward low energies where the collision times are long enough to sample vibrational and rotational modes. This research is supported by the National Science Foundation through grant PHY-1068877 and by the Office of Fusion Energy Sciences and the Office of Basic Energy Sciences, U.S. DOE, Contract No. DE-AC05-00OR22725 with UT-Battelle, LLC.
Self-similarity of high-pT hadron production in π-p and π- A collisions

International Nuclear Information System (INIS)

Tokarev, M.V.; Panebrattsev, Yu.A.; Skoro, G.P.; Zborovsky, I.

2002-01-01

Self-similar properties of hadron production in π - p and π - A collisions over a high-p T region are studied. The analysis if experimental data is performed in the framework of z-scaling. The scaling variable depends on the anomalous fractal dimension of the incoming pion. Its value is found to be δ π ≅ 0.1. Independence of the scaling function Ψ(z) on the collision energy is shown. A-dependence of data z-presentation confirms self-similarity of particle formation in πA collisions
Charge-sign-clustering observed in high-multiplicity, high-energy heavy-ion collisions

International Nuclear Information System (INIS)

Takahashi, Y.; Gregory, J.C.; Hayashi, T.

1989-01-01

Charge-sign distribution in 200 GeV/amu heavy-ion collisions is studied with the Magnetic-Interferometric-Emulsion-Chamber (MAGIC) for central collision events in 16 O + Pb and 32 S + Pb interactions. Charge-sign clustering is observed in most of the fully-analyzed events. A statistical 'run-test' is performed for each measured event, which shows significant deviation from a Gaussian distribution (0,1) expected for random-charge distribution. Candidates of charge clusters have 5 - 10 multiplicity of like-sign particles, and are often accompanied by opposite-sign clusters. Observed clustering of identical charges is more significant in the fragmentation region than in the central region. Two-particle Bose-Einstein interference and other effects are discussed for the run-test examination. (author)
A unified treatment of high energy interactions

International Nuclear Information System (INIS)

Drescher, H.J.; Werner, K.; Ostapchenko, S.; Centre National de la Recherche Scientifique, 44 - Nantes

1999-01-01

It is well known that high energy interactions as different as electron-positron annihilation, deep inelastic lepton-nucleon scattering, proton-proton interactions, and nucleus-nucleus collisions have many features in common. Based upon this observation, a model for all these interactions is constructed which relies on the fundamental hypothesis that the behavior of high energy interactions is universal. (author)
The upper bound of radiation energy in the Myers-Perry black hole collision

International Nuclear Information System (INIS)

Gwak, Bogeun; Lee, Bum-Hoon

2016-01-01

We have investigated the upper bound of the radiation energy in the head-on collision of two Myers-Perry black holes. Initially, the two black holes are far away from each other, and they become one black hole after the collision. We have obtained the upper bound of the radiation energy thermodynamically allowed in the process. The upper bound of the radiation energy is obtained in general dimensions. The radiation bound depends on the alignments of rotating axes for a given initial condition due to spin-spin interaction. We have found that the collision may not be occurred for a initially ultra-spinning black hole.
Probing the nuclear symmetry energy with heavy-ion collisions

Directory of Open Access Journals (Sweden)

De Filippo E.

2015-01-01

Full Text Available Heavy ion collisions (HIC have been widely used to extract the parametrization of symmetry energy term of nuclear equation of state as a function of barionic density. HIC in fact are a unique tool in terrestrial laboratories to explore the symmetry energy around the saturation density (ρ0 = 0.16fm−3 from sub-saturation densities (Fermi energies towards compressed nuclear matter (ρ > 2 − 3ρ0 that can be reached at relativistic energies, as a function of different conditions of temperature, mass asymmetry and isospin. One of the main study at present is to reach a coherent description of EOS of asymmetric nuclear matter from heavy ion collisions of stable and exotic nuclei, nuclear structure studies and astrophysical observations. In this work an overview of the current status of the research is shortly reviewed together with new perspectives aimed to reduce the present experimental and theoretical uncertainties.

Inclusive pi$^{0}$ production from high-energy pp collisions at very large transverse momenta

CERN Document Server

Clark, A G; Dittmann, P; Eggert, Karsten; Hungerbühler, V; Patel, P M; Strauss, J; Zallo, A; Aubert, Bernard; Banner, M; Chèze, J C; Lapuyade, C; Modis, T; Pérez, P; Teiger, J; Tur, C; Vialle, J P; Zaccone, Henri; Zylberstejn, A; Jenni, Peter; Strolin, P; Tarnopolsky, G J

1978-01-01

The authors report on measurements of inclusive pi /sup 0/ production at c.m. energies of 53 and 63 GeV, theta approximately=90 degrees , from p-p collisions at the CERN ISR. In the range 0.2
Pion correlations and calorimeter design for high energy heavy ion collisions. Progress report

International Nuclear Information System (INIS)

Wolf, K.L.

1997-01-01

Data analysis is in progress for recent experiments performed by the NA44 collaboration with the first running of 160 A GeV 208 Pb-induced reactions at the CERN SPS. Identified singles spectra were taken for pions, kaons, protons, deuterons, antiprotons and antideuterons. Two-pion interferometry measurements were made for semi-central-triggered 208 Pb + Pb collisions. An updated multi-particle spectrometer allows high statistics data sets of identified particles to be collected near mid-rapidity. A second series of experiments will be performed in the fall of 1995 with more emphasis on identical kaon interferometry and on the measurement of rare particle spectra and correlations. Modest instrumentation upgrades by TAMU are designed to increase the trigger function for better impact parameter selection and improved collection efficiency of valid events. An effort to achieve the highest degree of projectile-target stopping is outlined and it is argued that an excitation function on the SPS is needed to better understand reaction mechanisms. Analysis of experimental results is in the final stages at LBL in the EOS collaboration for two-pion interferometry in the 1.2 A GeV Au + Au reaction, taken with full event characterization
Hard photons a probe of the heavy ion collision dynamics

International Nuclear Information System (INIS)

Schutz, Y.

1994-01-01

Heavy-ion collisions have proven to be a unique tool to study the nucleus in extreme states, with values of energy, spin and isospin far away from those encountered in the nucleus in its ground state. Heavy-ion collisions provide also the only mean to form and study in the laboratory nuclear matter under conditions of density and temperature which could otherwise only be found in stellar objects like neutron stars and super-novae. the goal of such studies is to establish the equation of state of nuclear matter and the method consist in searching the collective behaviour in which heavy-ion collisions differ from a superposition of many nucleon-nucleon collisions. Among the various probes of collective effects, like flow, multifragmentation, or subthreshold particles, we have selected hard photons because they provide, together with dileptons, the only unperturbed probe of a phase of the collision well localized in space and time. The origin of hard photons, defined as the photons building up the spectrum beyond the energy of the giant dipole resonance (E γ > 30∼MeV), is attributed predominantly to the bremsstrahlung radiation emitted incoherently in individual neutron-proton collisions. Their energy reflects the combination of the beam momentum and the momenta induced by the Fermi motion of the nucleons within the collision zone. Therefore, at intermediate energies, hard photons probe the dynamical phase space distribution of participant nucleons and they convey information on the densities reached in heavy-ion collisions, the size and life time of the dense photon source and the compressibility of nuclear matter. The techniques we have developed include intensity interferometry and exclusive measurements scanning with high resolution the whole range of impact parameters. The interpretation of our data is guided by dynamical phase space calculations of the BUU type
Approach to equilibrium in high energy heavy ion collisions

International Nuclear Information System (INIS)

Zimanyi, J.

1981-01-01

With the aim to clarify somewhat the question of equilibration in the following we investigate the approach to equilibrium of particle composition and momentum distribution of the particles within the firecloud formed in the central collision of energetic heavy ions. (orig.)
Future of high energy physics

International Nuclear Information System (INIS)

Panofsky, W.K.H.

1984-06-01

A rough overview is given of the expectations for the extension of high energy colliders and accelerators into the xtremely high energy range. It appears likely that the SSC or something like it will be the last gasp of the conventional method of producing high energy proton-proton collisions using synchrotron rings with superconducting magnets. It is likely that LEP will be the highest energy e+e - colliding beam storage ring built. The future beyond that depends on the successful demonstrations of new technologies. The linear collider offers hope in this respect for some extension in energy for electrons, and maybe even for protons, but is too early to judge whether, by how much, or when such an extension will indeed take place
Comparative study on contribution of charge-transfer collision to excitations of iron ion between argon radio-frequency inductively-coupled plasma and nitrogen microwave induced plasma

Energy Technology Data Exchange (ETDEWEB)

Satoh, Kozue; Wagatsuma, Kazuaki, E-mail: wagatuma@imr.tohoku.ac.jp

2015-06-01

This paper describes an ionization/excitation phenomenon of singly-ionized iron occurring in an Okamoto-cavity microwave induced plasma (MIP) as well as an argon radio-frequency inductively-coupled plasma (ICP), by comparing the Boltzmann distribution among iron ionic lines (Fe II) having a wide range of the excitation energy from 4.76 to 9.01 eV. It indicated in both the plasmas that plots of Fe II lines having lower excitation energies (4.76 to 5.88 eV) were fitted on each linear relationship, implying that their excitations were caused by a dominant thermal process such as collision with energetic electron. However, Fe II lines having higher excitation energies (more than 7.55 eV) had a different behavior from each other. In the ICP, Boltzmann plots of Fe II lines assigned to the higher excited levels also followed the normal Boltzmann relationship among the low-lying excited levels, even including a deviation from it in particular excited levels having an excitation energy of ca. 7.8 eV. This deviation can be attributed to a charge-transfer collision with argon ion, which results in the overpopulation of these excited levels, but the contribution is small. On the other hand, the distribution of the high-lying excited levels was non-thermal in the Okamoto-cavity MIP, which did not follow the normal Boltzmann relationship among the low-lying excited levels. A probable reason for the non-thermal characteristics in the MIP is that a charge-transfer collision with nitrogen molecule ion having many vibrational/rotational levels could work for populating the 3d{sup 6}4p (3d{sup 5}4s4p) excited levels of iron ion broadly over an energy range of 7.6–9.0 eV, while collisional excitation by energetic electron would occur insufficiently to excite these high-energy levels. - Highlights: • This paper describes the excitation mechanism of iron ion in Okamoto-cavity MIP in comparison with conventional ICP. • Boltzmann distribution is studied among iron ionic lines of
Effects of momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei

International Nuclear Information System (INIS)

Li Baoan; Das, Champak B.; Das Gupta, Subal; Gale, Charles

2004-01-01

Using an isospin- and momentum-dependent transport model we study effects of the momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei. It is found that symmetry potentials with and without the momentum-dependence but corresponding to the same density-dependent symmetry energy E sym (ρ) lead to significantly different predictions on several E sym (ρ)-sensitive experimental observables especially for energetic nucleons. The momentum- and density-dependence of the symmetry potential have to be determined simultaneously in order to extract the E sym (ρ) accurately. The isospin asymmetry of midrapidity nucleons at high transverse momenta is particularly sensitive to the momentum-dependence of the symmetry potential. It is thus very useful for investigating accurately the equation of state of dense neutron-rich matter
Development of a fragment detector system for the study of peripheral collisions at high beam energies

International Nuclear Information System (INIS)

Spies, H.

1992-06-01

In the framework of the experimental program at the accelerator facilities SIS/ESR of the Society for Heavy-Ion research in Darmstadt one of the essential research aims of the LAND collaboration is the study of high-lying collective states after electromagnetic excitation in heavy-ion collisions at nearly relativistic beam energies. By the exchange of virtual photons with high energy giant resonances are excited with high probabilities. The main decay channel of giant resonances in heavy nuclei is the emission of neutrons as well as below the particle threshold the emission of γ radiation. For the study of these states a detector system was developed, which makes the kinematically complete measurement of all reaction partners possible. For the determination of the neutron energy serves the Large Area Neutron Detector LAND, a time-of-flight spectrometer for high-energetic neutrons. For the measurement of the γ radiation emitted by the excited projectile the target is surrounded by an array of 48 BaF 2 crystals. A radiation detector system consisting of 6 single detectors and further 5 help detectors allows together with the magnetic spectrometer ALADIN the identification of the heavy projectile fragments by charge, momentum, and mass. Four position-sensitive plastic scintillators serve for the measurement of the trajectory of the projectile respectively the projectile fragments in front and behind the deviating magnet. Additionally with these detectors the velocity is measured. For the determination of the nuclear charge of the projectile fragments serve a multiple-ionization chamber and a Cherenkov detector. In this thesis the development and taking into operation of the LAND radiation detector system is described. (orig./HSI) [de
Definition and measurement of entropy in high energy heavy ion collisions

International Nuclear Information System (INIS)

Remler, E.A.

1986-01-01

This talk has two parts: the first on the definition and the second on the measurement of entropy. The connection to nuclear thermodynamics can be retained without the local equilibrium assumption via two steps. The first is relatively simple and goes as follows. The authors make the certainly reasonable assumption that in central collisions, at the moment of maximum compression, the state is similar to one or more fireballs and that the total entropy of each fireball approximates that of an equilibrated system at the same total energy and average density. This entropy, if measurable, would determine much of the thermodynamic properties of nuclear matter. The second step therefore concerns measurement of this entropy. This paper develops a method by which entropy may be measured using a minimum amount of theory. In particular, it is not based on any assumption local equilibrium
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.
High pT Harmonics in PbPb Collisions at 5.02 TeV

Science.gov (United States)

Wang, Quan; CMS Collaboration

2017-11-01

Studies of azimuthal anisotropies for very high pT particles in relativistic heavy ion collisions provide crucial information on the path length dependence of the parton energy loss mechanism in the quark-gluon plasma. Final high-precision data on the elliptic (v2) and triangular (v3) anisotropy harmonics of charged particles, obtained with the scalar product method, are presented up to pT ∼ 100 GeV/c in PbPb collisions at √{sNN} = 5.02 TeV, using data recorded during the LHC run 2 with the CMS detector. In particular, the v3 harmonic is explored to a very high pT regime for the first time, allowing for an improved understanding of the effect of initial-state fluctuations on the parton energy loss. The v2 values reaching up pT ∼ 100 GeV/c are also determined using 4-, 6- and 8-particle cumulants, shedding new light on the origin of the observed high-pT azimuthal anisotropies. These new results are compared to theoretical calculations and provide stringent constraints on the parton energy loss mechanisms and the influence of initial-state fluctuations.
Collision induced fragmentation of fast molecular ions in solids and gases

International Nuclear Information System (INIS)

Gemmell, D.S.

1979-01-01

A brief review is given of recent high resolution measurements on fragments arising from the collision-induced dissociation of fast (MeV) molecular ions. For solid targets, strong wake effects are observed. For gaseous targets, excited electronic states of the projectile ions play an important role. Measurements of this type provide useful information on the charge states of fast ions traversing matter. The experimental techniques show promise as a unique method for determining the geometrical structures of the molecular-ion projectiles. 41 references
Dynamics of the water dimer + nitric oxide collision

Energy Technology Data Exchange (ETDEWEB)

Ree, Jong Baik [Dept. of Chemistry Education, Chonnam National University, Gwangju (Korea, Republic of); Kim, Yoo Hang [Dept. of Chemistry, Inha University, Incheon (Korea, Republic of); Shin, Hyung Kyu [Dept. of Chemistry, University of Nevada, Nevada (Korea, Republic of)

2017-02-15

Collision-induced intermolecular energy transfer and intramolecular vibrational redistribution in the collision of a water dimer and nitric oxide are studied by use of quasiclassical procedures. Intermolecular energy flow is shown to occur mainly through a direct-mode mechanism transferring relatively large amounts in strong collisions. About a quarter of the energy initially deposited in the dimer transfers to the ground state NO, while the rest redistributes among internal motions of the collision system. The main portion of initial energy deposited in the dimer redistributes in the stretches of the donor monomer through the 1:1 resonance followed by in the bend through the 1:2 resonance. Energy transfer from the excited NO to the ground-state dimer is equally efficient, transferring more than half the initial excitation to the donor monomer, the efficiency that is attributed to the internal modes operating as energy reservoirs. The hydrogen bond shares about 15% of the initial excitation stored in both dimer-to-NO and NO-to-dimer processes as a result of strong coupling of the hydrogen bond with the proton-donor OH bond of the monomer. A small fraction of collisions proceeds through a complex-mode mechanism and lead to NO dissociation, the dissociated O atom showing a propensity to form a new hydrogen bond.
The morphology of collision cascades as a function of recoil energy

International Nuclear Information System (INIS)

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

1989-09-01

An analytical method based on defect densities has been devised to determine the threshold energies for subcascade formation in computer simulated collision cascades. Cascades generated with the binary collision code MARLOWE in Al, Cu, Ag, Au, Fe, Mo and W were analyzed to determine the threshold energy for subcascade formation, the number of subcascades per recoil per unit energy and the average spacing of subcascades. Compared on the basis of reduced damage energy, metals of the same crystal structure have subcascade thresholds at the same reduced energy. The number of subcascades per unit reduced damage energy is about the same for metals of the same crystal structure, and the average spacing of subcascades is about the same in units of lattice parameters. Comparisons between subcascade threshold energies and average recoil energies in fission and fusion neutron environments show the spectral sensitivity of the formation of subcascades
Transverse Phenomena in Pion Production in Hadronic Collisions at SPS energy

CERN Document Server

Chvála, Ondrej

A comparative study of pion production in hadronic collisio ns at SPS energies focusing on transverse phenomena is presented. Charged pion densities in p+p, p+C, p+Pb and Pb+Pb interactions, obtained at the CERN SPS with the NA49 detecto r setup, are discussed in the forward hemisphere covering ranges in Feynman x F between 0 and 0.4 and in transverse momentum from 0 to 2.1 GeV/c. A detailed description of the da ta analysis, the corrections and centrality determination is given for p+Pb interaction s using a sample of 2 M events. These data are compared to p+p collisions in order to extract those physics quantities which indicate deviations from the elementary reaction specific t o the presence of the nucleus. The evolution of these quantities as a function of centrality is discussed. Their comparison to p+C and Pb+Pb collisions reveals a smooth dependence on the n umber of collisions per participant. In particular, the enhancement of pion yields at high transverse momentum is studied. It is shown to be gove...
The impact of energy conservation in transport models on the π−/π+ multiplicity ratio in heavy-ion collisions and the symmetry energy

Directory of Open Access Journals (Sweden)

M.D. Cozma

2016-02-01

Full Text Available The charged pion multiplicity ratio in intermediate energy central heavy-ion collisions has been proposed as a suitable observable to constrain the high density dependence of the isovector part of the equation of state. A comparison of various transport model predictions with existing experimental data has led, however, to contradictory results. Using an upgraded version of the Tübingen QMD transport model, which allows the conservation of energy at a local or global level by accounting for the potential energy of hadrons in two-body collisions and leading thus to particle production threshold shifts, we demonstrate that compatible constraints for the symmetry energy stiffness can be extracted from pion multiplicity and elliptic flow observables. However, pion multiplicities and ratios are proven to be highly sensitive to the yet unknown isovector part of the in-medium Δ(1232 potential which hinders, at present, the extraction of meaningful information on the high density dependence of the symmetry energy. A solution to this problem together with the inclusion of contributions presently neglected, such as in-medium pion potentials and retardation effects, are needed for a final verdict on this topic.
Theoretical high energy physics

International Nuclear Information System (INIS)

Lee, T.D.

1993-01-01

Brief reports are given on the work of several professors. The following areas are included: quantum chromodynamics calculations using numerical lattice gauge theory and a high-speed parallel computer; the ''spin wave'' description of bosonic particles moving on a lattice with same-site exclusion; a high-temperature expansion to 13th order for the O(4)-symmetric φ 4 model on a four-dimensional F 4 lattice; spin waves and lattice bosons; superconductivity of C 60 ; meson-meson interferometry in heavy-ion collisions; baryon number violation in the Standard Model in high-energy collisions; hard thermal loops in QCD; electromagnetic interactions of anyons; the relation between Bose-Einstein and BCS condensations; Euclidean wormholes with topology S 1 x S 2 x R; vacuum decay and symmetry breaking by radiative corrections; inflationary solutions to the cosmological horizon and flatness problems; and magnetically charged black holes
Accelerator-based atomic and molecular collision physics

International Nuclear Information System (INIS)

Datz, S.

1993-01-01

Accelerators have been shown to have great utility in addressing a broad range of problems in experimental atomic physics. There are, of course, phenomena such as inner-shell MO promotion which can occur only at high collision energies. At much higher energies, large transient Coulomb fields can be generated which lead to copious production electron-positron pairs and to capture of electrons from the negative continuum. But in addition, many advantages can be gained by carrying out low-energy (center-of-mass) collisions at high laboratory energies, specifically in a single pass mode or in multi-pass modes in ion storage rings in which, e.g., collision in the milli-electron volt region can be achieved for electron-molecule reactions. Certain advantages also accrue using open-quotes reverse kinematicsclose quotes in which high velocity ions collide with almost open-quotes stationaryclose quotes electrons as in resonant transfer and excitation (RTE) and collisions of energetic ions in the dense open-quotes electron gasclose quotes found in crystal channels
High energy nuclear excitations

International Nuclear Information System (INIS)

Gogny, D.; Decharge, J.

1983-09-01

The main purpose of this talk is to see whether a simple description of the nuclear excitations permits one to characterize some of the high energy structures recently observed. The discussion is based on the linear response to different external fields calculated using the Random Phase Approximation. For those structure in heavy ion collisions at excitation energies above 50 MeV which cannot be explained with such a simple approach, we discuss a possible mechanism for this heavy ion scattering
High pT jet production in pp collisions

International Nuclear Information System (INIS)

Eskola, K.J.; Wang, X.N.

1995-01-01

Production rates of large p T jets in pp collisions at RHIC and LHC energies are studied using the next-to-leading order calculation of S. D. Ellis, Z. Zunszt and D. Soper. The computed inclusive one-jet cross sections are compared against the CERN and Fermilab jet data from p bar p and pp collisions. The dependence of the results on the choice of the parton distributions and renormalization/factorization scales is investigated

In-medium and isospin effects on eta production in heavy-ion collisions near threshold energies

Energy Technology Data Exchange (ETDEWEB)

Chen, Jie; Chen, Peng-Hui [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China); University of Chinese Academy of Sciences, Beijing (China); Feng, Zhao-Qing; Wang, Jian-Song [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China); Niu, Fei [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China); Henan Normal University, Institute of Particle and Nuclear Physics, Xinxiang (China); Guo, Ya-Fei [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China); Lanzhou University, School of Nuclear Science and Technology, Lanzhou (China)

2017-06-15

The dynamics of η meson produced in heavy-ion collisions has been investigated within the Lanzhou quantum molecular dynamics model (LQMD). The in-medium corrections have been considered in the model, in which an attractive η-nucleon potential is implemented. The impacts of the η optical potential and the nuclear symmetry energy on the η dynamics are investigated. It is found that the total yields are slightly influenced by the potential and weakly depend on the symmetry energy. However, the structure of the kinetic spectra is related to the optical potential and the stiffness of symmetry energy. The attractive potential leads to the reduction of high-momentum (kinetic energy) η production, i.e., the spectra of momentum and transverse mass distributions, increasing the reabsorption process by surrounding nucleons, and favoring the in-plane eta emissions. The reabsorption process in η-nucleon collisions plays a significant role on the η dynamics. (orig.)
Ion induced high energy electron emission from copper

International Nuclear Information System (INIS)

Ruano, G.; Ferron, J.

2008-01-01

We present measurements of secondary electron emission from Cu induced by low energy bombardment (1-5 keV) of noble gas (He + , Ne + and Ar + ) and Li + ions. We identify different potential and kinetic mechanisms and find the presence of high energetic secondary electrons for a couple of ion-target combinations. In order to understand the presence of these fast electrons we need to consider the Fermi shuttle mechanism and the different ion neutralization efficiencies.
Energy spectrum of tau leptons induced by the high energy Earth-skimming neutrinos

International Nuclear Information System (INIS)

Tseng, J.-J.; Yeh, T.-W.; Lee, F.-F.; Lin, G.-L.; Athar, H.; Huang, M.A.

2003-01-01

We present a semianalytic calculation of the tau-lepton flux emerging from the Earth induced by incident high energy neutrinos interacting inside the Earth for 10 5 ≤E ν /GeV≤10 10 . We obtain results for the energy dependence of the tau-lepton flux coming from the Earth-skimming neutrinos, because of the neutrino-nucleon charged-current scattering as well as the resonant ν(bar sign) e e - scattering. We illustrate our results for several anticipated high energy astrophysical neutrino sources such as the active galactic nuclei, the gamma-ray bursts, and the Greisen-Zatsepin-Kuzmin neutrino fluxes. The tau-lepton fluxes resulting from rock-skimming and ocean-skimming neutrinos are compared. Such comparisons can render useful information about the spectral indices of incident neutrino fluxes
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,
CGC/saturation approach for high energy soft interactions: 'soft' Pomeron structure and v{sub n} in hadron and nucleus collisions from Bose-Einstein correlations

Energy Technology Data Exchange (ETDEWEB)

Gotsman, E.; Maor, U. [Tel Aviv University, Department of Particle Physics School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Science, Tel Aviv (Israel); Levin, E. [Tel Aviv University, Department of Particle Physics School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Science, Tel Aviv (Israel); Universidad Tecnica Federico Santa Maria and Centro Cientifico-Tecnologico de Valparaiso, Departemento de Fisica, Valparaiso (Chile)

2016-11-15

In the framework of our model of soft interactions at high energy based on the CGC/saturation approach, we show that Bose-Einstein correlations of identical gluons lead to large values of v{sub n}. We demonstrate how three dimensional scales of high energy interactions, hadron radius, typical size of the wave function in diffractive production of small masses (size of the constituent quark), and the saturation momentum, influence the values of BE correlations, and in particular, the values of v{sub n}. Our calculation shows that the structure of the 'dressed' Pomeron leads to values of v{sub n} which are close to experimental values for proton-proton scattering, 20 % smaller than the observed values for proton-lead collisions and close to lead-lead collisions for 0-10 % centrality. Bearing this result in mind, we conclude that it is premature to consider that the appearance of long range rapidity azimuthal correlations are due only to the hydrodynamical behaviour of the quark-gluon plasma. (orig.)
Hawking-Unruh hadronization and strangeness production in high energy collisions

Directory of Open Access Journals (Sweden)

Castorina Paolo

2015-01-01

Full Text Available The interpretation of quark (q- antiquark (q̄ pairs production and the sequential string breaking as tunneling through the event horizon of colour confinement leads to a thermal hadronic spectrum with a universal Unruh temperature, T ≃ 165 Mev, related to the quark acceleration, a, by T = a/2π. The resulting temperature depends on the quark mass and then on the content of the produced hadrons, causing a deviation from full equilibrium and hence a suppression of strange particle production in elementary collisions. In nucleus-nucleus collisions, where the quark density is much bigger, one has to introduce an average temperature (acceleration which dilutes the quark mass effect and the strangeness suppression almost disappears.
Review of high energy hadron-nucleus data

Science.gov (United States)

Lissauer, D.

1987-01-01

In this review we will summarize new data on hardron-nucleus interactions. The possibility that quark-gluon plasma may be created in heavy ion collisions has led to renewed interest in hadron-nucleus collisions. In particular one hopes that understanding the energy loss of hadrons in h-A collissions will allow us to estimate the optimum energy in AA collisions in order to achieve maximum baryon and/or maximum energy density. This will allow us to choose the optimal experimental environment in the search for quark-gluon plasma. This review will thus omit many interesting results from hadron-nucleus collisions, such as the A dependence of lepton pair production, EMC effect and others. We will focus our attention on the following: (i) Estimating the rate of energy loss of the incident hadron as it propagates through the target. (ii) Determining where the enmergy is deposited in central hadron-nucleus collisions. It is clear that there is no direct or unique method of extrapolating our knowledge of h-A collisions to predict what will happen in AA-collisions. The knowledge and understanding of pp and pA collisions is, however, a useful and necessary guide to what one can expect in AA collisions. In this review we will concentrate on three experimental approaches to the study of h-A collisions. In Section 1 we will discuss the present status of pA → p + X inclusive measurements. In Section 2 measurements from visual detectors, in this case results from the 30″ hybrid spectrometer, which allows investigations of global event properties will be presented. In Section 3 data using 2π calorimeters, where one can trigger and measure transverse energy and energy flow over a given rapidity region, will be discussed. The conclusions will be given in Section 4.
Neutralization mechanisms in He+-Al surface collisions

International Nuclear Information System (INIS)

Bajales, N.; Ferron, J.; Goldberg, E.C.

2007-01-01

From a quantum mechanical calculation where the populations of He ground and first excited states are properly taken into account, we can identify for the first time the neutralization to the He first excited state as an operative mechanism in He + -Al surface collisions. This identification allows us to understand the presence of high energy electrons in the ion induced electron emission spectra, through the inclusion of Auger deexcitation as an electron emission source, as well as to suggest a possible cause for the disagreement still found between theory and experiments in low energy ion scattering (LEIS) for this system
Study of high mass dimuon production in heavy ion collisions with CMS

International Nuclear Information System (INIS)

Bedzhidyan, M.; Kvatadze, R.; Shanidze, R.

1996-01-01

High invariant mass muon pair production in Pb-Pb collisions with CMS detector at LHC has been considered. Various sources of dimuons have been included into the analysis. It is shown that for an appropriate set of cuts on the transverse momenta of μ, on the invariant mass of the muon pairs and on the hadronic/electromagnetic energy deposited into the calorimeters, one can separate the contribution of the semileptonic decays of open beauty particles. The latter process can be used as a reference for measuring the suppression of bb bar quarkonium states in nucleus-nucleus collisions. 25 refs., 7 figs
A review of experimental results obtained in Au-Au collisions at the RHIC-BNL energies using BRAHMS experimental set-up

International Nuclear Information System (INIS)

Jipa, Alexandru

2003-01-01

Ultrarelativistic heavy ion collisions are useful tools to investigate highly excited dense nuclear matter. At sufficiently high temperature, nuclear matter is expected to undergo a phase transition to quark-gluon plasma. Therefore, new experiments have been proposed to investigate the behaviour of the highly excited dense nuclear matter. One of the experiments performed at the Relativistic Heavy Ion Collider from Brookhaven National Laboratory is the BRAHMS Experiment. In the three running years many experimental data have been obtained. These data permitted to establish significant experimental results on charged pion, charged kaon, proton and antiproton production in Au-Au collisions at 130 A GeV and 200 A GeV in CMS. The present work summarizes the main experimental results on charged particle multiplicities, rapidity distributions, momentum spectra, antiparticle to particle ratios and connects these results with some interesting physical quantities. Their dependencies on the available energies in the CMS in similar collisions are included. Interesting behaviours with the increase of this energy are reported. The most interesting are related to the behaviour of the antiproton to proton ratio on the collision centrality and on the available energy in the centre of mass system, the strangeness production, Coulomb repulsion and slope parameters of the momentum spectra. A few new steps in the knowledge of the behaviour of the highly excited and dense nuclear matter can be reported. (authors)
Dynamical aspects of intermediate-energy nucleus-nucleus collisions. Pt. 1

International Nuclear Information System (INIS)

Cassing, W.

1987-01-01

Central collisions of heavy nuclei are investigated within the limit of selfconsistent independent single-particle motion in terms of the Wigner transform of the one-body density matrix in space and time. The energy regime considered extends from roughly 15 MeV/u to 150 MeV/u. Special attention is devoted to the relation between energy and momentum of the nucleons in the collision zone of the two nuclei. An initial average energy-momentum distribution f(k; E) is determined within the fully quantal approach which proves to be vital for our understanding of energetic particle production in the very early stage of the heavy-ion reaction. A comparison with related classical quantities shows the peculiar features of quantum dynamics for finite size fermion systems far from equilibrium. (orig.)
What can we learn from high-energy hadron-nucleus interactions

International Nuclear Information System (INIS)

Tow, D.M.

1979-12-01

High-energy hadron-nucleus (hA) collisions provide the exciting possibility of giving information about the spacetime development of hadron-hadron interactions and therefore differentiating various multiparticle production models. Some of the major developments in this field during the past decade, both experimentally and theoretically are reviewed. Several general features of the data are pointed out, and several classes of models are discussed. A recently proposed simple spacetime model for high-energy hA collisions is elaborated. Comments are made on the extension to nucleus-nucleus interactions and the future outlook
A microscopic description of absorption in high-energy string-brane collisions

CERN Document Server

D'Appollonio, Giuseppe; Russo, Rodolfo; Veneziano, Gabriele

2016-01-01

We study the collision of a highly energetic light closed string off a stack of Dp-branes at (sub)string-scale impact parameters and in a regime justifying a perturbative treatment. Unlike at larger impact parameters - where elastic scattering and/or tidal excitations dominate - here absorption of the closed string by the brane system, with the associated excitation of open strings living on it, becomes important. As a first step, we study this phenomenon at the disk level, in which the energetic closed string turns into a single heavy open string at rest whose particularly simple properties are described.
Ion induced high energy electron emission from copper

Energy Technology Data Exchange (ETDEWEB)

Ruano, G. [Instituto de Desarrollo Tecnologico para la Industria Quimica, Consejo Nacional de Investigaciones Cientificas y Tecnicas and Universidad Nacional del Litoral Gueemes 3450 CC 91, 3000 Santa Fe (Argentina)], E-mail: gdruano@ceride.gov.ar; Ferron, J. [Instituto de Desarrollo Tecnologico para la Industria Quimica, Consejo Nacional de Investigaciones Cientificas y Tecnicas and Universidad Nacional del Litoral Gueemes 3450 CC 91, 3000 Santa Fe (Argentina); Departamento de Ingenieria de Materiales, Facultad de Ingenieria Quimica, Consejo Nacional de Investigaciones Cientificas y Tecnicas and Universidad Nacional del Litoral Gueemes 3450 CC 91, 3000 Santa Fe (Argentina)

2008-11-15

We present measurements of secondary electron emission from Cu induced by low energy bombardment (1-5 keV) of noble gas (He{sup +}, Ne{sup +} and Ar{sup +}) and Li{sup +} ions. We identify different potential and kinetic mechanisms and find the presence of high energetic secondary electrons for a couple of ion-target combinations. In order to understand the presence of these fast electrons we need to consider the Fermi shuttle mechanism and the different ion neutralization efficiencies.
High $p_T$ harmonics in PbPb collisions at 5.02 TeV

CERN Document Server

Wang, Quan

2017-01-01

Studies of azimuthal anisotropies for very high $p_{T}$ particles in relativistic heavy ion collisions provide crucial information on the path length dependence of the parton energy loss mechanism in the quark-gluon plasma. Final high-precision data on the elliptic ($v_{2}$) and triangular ($v_{3}$) anisotropy harmonics of charged particles, obtained with the scalar product method, are presented up to $p_{T}$ $\\sim$ 100 GeV/c in PbPb collisions at $\\sqrt{s_{NN}}$ = 5.02 TeV, using data recorded during the LHC run 2 with the CMS detector. In particular, the $v_{3}$ harmonic is explored to a very high $p_{T}$ regime for the first time, allowing for an improved understanding of the effect of initial-state fluctuations on the parton energy loss. The $v_{2}$ values reaching up $p_{T}$ $\\sim$ 100 GeV/c are also determined using 4-, 6- and 8-particle cumulants, shedding new light on the origin of the observed high-$p_{T}$ azimuthal anisotropies. These new results are compared to theoretical calculations and provide ...
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.
Ab initio study of charge transfer in B2+ low-energy collisions with atomic hydrogen

International Nuclear Information System (INIS)

Turner, A.R.; Cooper, D.L.; Wang, J.G.; Stancil, P.C.

2003-01-01

Charge transfer processes due to collisions of ground state B 2+ (2s 2 S) ions with atomic hydrogen are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) method. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial and rotational coupling matrix elements obtained with the spin-coupled valence-bond approach. Total and state-selective cross sections and rate coefficients are presented. Comparison with the existing experiments shows our results to be in good agreement. When E 400 eV/u, inclusion of rotational coupling increases the total cross section by 50%-80%, improving the agreement between the current calculations and experiments. For state-selective cross sections, rotational coupling induces mixing between different symmetries; however, its effect, especially at low collision energies, is not as important as had been suggested in previous work
Quark model and high energy collisions

International Nuclear Information System (INIS)

Nyiri, J.; Kobrinsky, M.N.

1982-06-01

The aim of the present review is to show that the additive quark model describes well not only the static features of hadrons but also the interaction processes at high energies. Considerations of the hadron-hadron and hadron-nucleus interactions and of the hadron production in multiparticle production processes suggest serious arguments in favour of the nucleus-like hadron structure and show the possibility to apply the rules of quark statistics to the description of the secondary particle production. (author)
Multifragmentation and evaporation: two competing processes in intermediate energy nuclear collisions

International Nuclear Information System (INIS)

Campi, X.; Desbois, J.; Lipparini, E.

1984-05-01

We study the conditions at which mutiple break up of nuclei occurs during a collision. A minimal temperature of about 5MeV seems to be necessary to produce multifragmentation. The average number of fragments produced is correlated with the average number of primary nucleon-nucleon collisions. Based on these ideas a simple model of evaporation-multifragmentation reactions is developed, which accounts for most of the existing data for protons and heavy ions induced reactions
Hot nuclei with high spin states in collisions between heavy nuclei

International Nuclear Information System (INIS)

Galin, J.

1991-01-01

In the first part of this contribution we have shown that pretty hot nuclei could be obtained in peripheral collisions of Kr+Au. The collisions considered in the chosen example give rise to a nucleus of Z=28 with a kinetic energy of 1600 MeV (i.e. a velocity close to 27 MeV/u to be compared with the 32 MeV/u of the beam). The excitation energy deposited in the non-detected target like-nucleus, deduced from the neutron multiplicity measurements, amounts to 700 MeV (T= 6 MeV). In the second part of the contribution one used the well known properties of fission, and particularly its sensitivity to spin, to show in a qualitative way that pretty high spin values are into play. A more quantitative analysis together with additional measurements are still needed in order to infer precise figures of spin. It can be noted that for the 29 MeV/u Pb+Au reaction 1 max amounts to 1700 ℎ. If we assume that the sticking or rolling conditions can be fulfilled for initial angular momenta of about 2/3 1 max , then a projectile-like (and its target partner) could acquire an intrinsic spin of about 160 ℎ. The behavior of a Pb-like nucleus brought in such an exotic state (T=6 MeV and J=160ℎ)) is certainly worth to be studied in detail. It is also worth recalling that, when obtained in peripheral collisions, the hot nuclei thus formed do not suffer much initial compression at variance with what happens in more central collisions. There is thus an interesting field to be explored of hot, high spin but uncompressed nuclei

Nucleus-nucleus collisions at very high energies

International Nuclear Information System (INIS)

Hansen, O.

1990-01-01

The present report covers the material of two lectures. The first part, contains a collection of useful formulae from relativistic kinematics and deals with invariant cross sections and multiplicities. The remainder of the paper is on strangeness production in relativistic heavy ion collisions. Some elementary rules for particle production in nucleon-nucleon interactions are presented. This paper also contains arguments on why one expects enhanced strange particle production from the quark-gluon plasma. Next is presented some selected data on strangeness production in Si + Au and other interactions at 14.6 GeV/c per nucleon and from S + S at 200 GeV/c per nucleon. Some conclusions drawn from the experimental results are presented. 10 refs
On Pseudorapidity Distribution and Speed of Sound in High Energy Heavy Ion Collisions Based on a New Revised Landau Hydrodynamic Model

Directory of Open Access Journals (Sweden)

Li-Na Gao

2015-01-01

Full Text Available We propose a new revised Landau hydrodynamic model to study systematically the pseudorapidity distributions of charged particles produced in heavy ion collisions over an energy range from a few GeV to a few TeV per nucleon pair. The interacting system is divided into three sources, namely, the central, target, and projectile sources, respectively. The large central source is described by the Landau hydrodynamic model and further revised by the contributions of the small target/projectile sources. The modeling results are in agreement with the available experimental data at relativistic heavy ion collider, large hadron collider, and other energies for different centralities. The value of square speed of sound parameter in different collisions has been extracted by us from the widths of rapidity distributions. Our results show that, in heavy ion collisions at energies of the two colliders, the central source undergoes a phase transition from hadronic gas to quark-gluon plasma liquid phase; meanwhile, the target/projectile sources remain in the state of hadronic gas. The present work confirms that the quark-gluon plasma is of liquid type rather than being of a gas type.
Collision-induced stimulated photon echoes in ‘strong’ magnetic field

Science.gov (United States)

Reshetov, V. A.

2018-05-01

Collision-induced stimulated photon echoes formed in a gaseous medium on the transition with the angular momentum change Ja=0 → Jb=1 under the action of ‘strong’ longitudinal magnetic field, when the echo pulse becomes unpolarized, are considered with an account of elastic depolarizing collisions. In the case of narrow spectral line the explicit expressions for the echo polarization density matrix and the degree of polarization are obtained. In the case of broad spectral line the results of the numeric calculations reproduce qualitatively the curve obtained in the experiments with ytterbium vapor.
First-principles investigation of the dissociation and coupling of methane on small copper clusters: Interplay of collision dynamics and geometric and electronic effects

Energy Technology Data Exchange (ETDEWEB)

Varghese, Jithin J.; Mushrif, Samir H., E-mail: shmushrif@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459 (Singapore)

2015-05-14

Small metal clusters exhibit unique size and morphology dependent catalytic activity. The search for alternate minimum energy pathways and catalysts to transform methane to more useful chemicals and carbon nanomaterials led us to investigate collision induced dissociation of methane on small Cu clusters. We report here for the first time, the free energy barriers for the collision induced activation, dissociation, and coupling of methane on small Cu clusters (Cu{sub n} where n = 2–12) using ab initio molecular dynamics and metadynamics simulations. The collision induced activation of the stretching and bending vibrations of methane significantly reduces the free energy barrier for its dissociation. Increase in the cluster size reduces the barrier for dissociation of methane due to the corresponding increase in delocalisation of electron density within the cluster, as demonstrated using the electron localisation function topology analysis. This enables higher probability of favourable alignment of the C–H stretching vibration of methane towards regions of high electron density within the cluster and makes higher number of sites available for the chemisorption of CH{sub 3} and H upon dissociation. These characteristics contribute in lowering the barrier for dissociation of methane. Distortion and reorganisation of cluster geometry due to high temperature collision dynamics disturb electron delocalisation within them and increase the barrier for dissociation. Coupling reactions of CH{sub x} (x = 1–3) species and recombination of H with CH{sub x} have free energy barriers significantly lower than complete dehydrogenation of methane to carbon. Thus, competition favours the former reactions at high hydrogen saturation on the clusters.
First-principles investigation of the dissociation and coupling of methane on small copper clusters: Interplay of collision dynamics and geometric and electronic effects

International Nuclear Information System (INIS)

Varghese, Jithin J.; Mushrif, Samir H.

2015-01-01

Small metal clusters exhibit unique size and morphology dependent catalytic activity. The search for alternate minimum energy pathways and catalysts to transform methane to more useful chemicals and carbon nanomaterials led us to investigate collision induced dissociation of methane on small Cu clusters. We report here for the first time, the free energy barriers for the collision induced activation, dissociation, and coupling of methane on small Cu clusters (Cu n where n = 2–12) using ab initio molecular dynamics and metadynamics simulations. The collision induced activation of the stretching and bending vibrations of methane significantly reduces the free energy barrier for its dissociation. Increase in the cluster size reduces the barrier for dissociation of methane due to the corresponding increase in delocalisation of electron density within the cluster, as demonstrated using the electron localisation function topology analysis. This enables higher probability of favourable alignment of the C–H stretching vibration of methane towards regions of high electron density within the cluster and makes higher number of sites available for the chemisorption of CH 3 and H upon dissociation. These characteristics contribute in lowering the barrier for dissociation of methane. Distortion and reorganisation of cluster geometry due to high temperature collision dynamics disturb electron delocalisation within them and increase the barrier for dissociation. Coupling reactions of CH x (x = 1–3) species and recombination of H with CH x have free energy barriers significantly lower than complete dehydrogenation of methane to carbon. Thus, competition favours the former reactions at high hydrogen saturation on the clusters
Evidence of final-state suppression of high-p{_ T} hadrons in Au + Au collisions using d + Au measurements at RHIC

Science.gov (United States)

Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wysłouch, B.; Zhang, J.

Transverse momentum spectra of charged hadrons with pT 2 GeV/c). In contrast, the d + Au nuclear modification factor exhibits no suppression of the high-pT yields. These measurements suggest a large energy loss of the high-pT particles in the highly interacting medium created in the central Au + Au collisions. The lack of suppression in d + Au collisions suggests that it is unlikely that initial state effects can explain the suppression in the central Au + Au collisions. PACS: 25.75.-q
Absorbed Energy in Ship Collisions and Grounding

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Zhang, Shengming

1998-01-01

is that the absorbed energy does not depend on the arrangement of the structure, the material properties, and the damage mode.The purpose of the present paper is to establish a new simple relation between the absorbed energy and the destroyed material volume, which can be used as a design tool for analysis of ship...... collisions and grounding. The developed expressions reflect the structural arrangement, the material properties and different damage patterns.The present method is validated against a large number of existing experimental results and detailed numerical simulation results. Applications to full-sale ship...
Measurements of Transverse Energy Distributions in Au+Au Collisions at √sNN = 200 GeV

International Nuclear Information System (INIS)

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

2004-01-01

Transverse energy (E T ) distributions have been measured for Au+Au collisions at √s NN = 200 GeV by the STAR collaboration at RHIC. E T is constructed from its hadronic and electromagnetic components, which have been measured separately. E T production for the most central collisions is well described by several theoretical models whose common feature is large energy density achieved early in the fireball evolution. The magnitude and centrality dependence of E T per charged particle agrees well with measurements at lower collision energy, indicating that the growth in E T for larger collision energy results from the growth in particle production. The electromagnetic fraction of the total E T is consistent with a final state dominated by mesons and independent of centrality
Influence of Energy and Temperature in Cluster Coalescence Induced by Deposition

Directory of Open Access Journals (Sweden)

J. C. Jiménez-Sáez

2012-01-01

Full Text Available Coalescence induced by deposition of different Cu clusters on an epitaxial Co cluster supported on a Cu(001 substrate is studied by constant-temperature molecular dynamics simulations. The degree of epitaxy of the final system increases with increasing separation between the centres of mass of the projectile and target clusters during the collision. Structure, roughness, and epitaxial order of the supported cluster also influence the degree of epitaxy. The effect of energy and temperature is determinant on the epitaxial condition of the coalesced cluster, especially both factors modify the generation, growth and interaction among grains. A higher temperature favours the epitaxial growth for low impact parameters. A higher energy contributes to the epitaxial coalescence for any initial separation between the projectile and target clusters. The influence of projectile energy is notably greater than the influence of temperature since higher energies allow greater and instantaneous atomic reorganizations, so that the number of arisen grains just after the collision becomes smaller. The appearance of grain boundary dislocations is, therefore, a decisive factor in the epitaxial growth of the coalesced cluster.
Role of multiparton interactions on J /ψ production in p +p collisions at LHC energies

Science.gov (United States)

Thakur, Dhananjaya; De, Sudipan; Sahoo, Raghunath; Dansana, Soumya

2018-05-01

The production mechanism of quarkonia states in hadronic collisions is still to be understood by the scientific community. In high-multiplicity p +p collisions, underlying event observables are of major interest. The multiparton interactions (MPIs) are underlying event observables, in which several interactions occur at the partonic level in a single p +p event. This leads to dependence of particle production on event multiplicity. If the MPI occurs in a harder scale, there will be a correlation between the yield of quarkonia and total charged-particle multiplicity. The ALICE experiment at the LHC in p +p collisions at √{s }=7 and 13 TeV has observed an approximate linear increase of relative J /ψ yield, (d/NJ /ψ/d y ⟨d NJ /ψ/d y ⟩ ), with relative charged-particle multiplicity density, (d/Nch/d y ⟨d Nch/d y ⟩ ). In our present work, we have performed a comprehensive study of the production of charmonia as a function of charged-particle multiplicity in p +p collisions at LHC energies using the perturbative QCD-inspired multiparton interaction model, pythia8 tune 4C, with and without the color reconnection scheme. A detailed multiplicity and energy-dependent study is performed to understand the effects of MPI on J /ψ production. The ratio of ψ (2 S ) to J /ψ is also studied as a function of charged-particle multiplicity at LHC energies.
Heavy ion fragmentation in high energy

International Nuclear Information System (INIS)

Nemes, M.C.

1985-01-01

A review is made on the theoretical aspects of heavy ion collisions at high energies. A comparison with several experimental data obtained in a large variety of experiments is present. An emphasis is given on the basis of Glauber's theory of scattering. (L.C.) [pt
Beam-energy dependence of charge balance functions from Au + Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

Science.gov (United States)

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

2016-08-01

Balance functions have been measured in terms of relative pseudorapidity (Δ η ) for charged particle pairs at the BNL Relativistic Heavy Ion Collider from Au + Au collisions at √{sNN}=7.7 GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at √{sNN}=2.76 TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). The narrowing of the balance function in central collisions at √{sNN}=7.7 GeV implies that a QGP is still being created at this relatively low energy.
On Markov processes in the hadron-nuclear and nuclear-nuclear collisions at superhigh energies

International Nuclear Information System (INIS)

Lebedeva, A.A.; Rus'kin, V.I.

2001-01-01

In the article the possibility of the Markov processes use as simulation method for mean characteristics of hadron-nuclear and nucleus-nuclear collisions at superhigh energies is discussed. The simple (hadron-nuclear collisions) and non-simple (nucleus-nuclear collisions) non-uniform Markov process of output constant spectrum and absorption in a nucleon's nucleus-target with rapidity y are considered. The expression allowing to simulate the different collision modes were obtained
Low-energy charge transfer for collisions of Si3+ with atomic hydrogen

Science.gov (United States)

Bruhns, H.; Kreckel, H.; Savin, D. W.; Seely, D. G.; Havener, C. C.

2008-06-01

Cross sections of charge transfer for Si3+ ions with atomic hydrogen at collision energies of ≈40-2500eV/u were carried out using a merged-beam technique at the Multicharged Ion Research Facility at Oak Ridge National Laboratory. The data span an energy range in which both molecular orbital close coupling (MOCC) and classical trajectory Monte Carlo (CTMC) calculations are available. The influence of quantum mechanical effects of the ionic core as predicted by MOCC is clearly seen in our results. However, discrepancies between our experiment and MOCC results toward higher collision energies are observed. At energies above 1000 eV/u good agreement is found with CTMC results.
Nucleus-nucleus collisions at relativistic energies: The CERN WA80 experiment

International Nuclear Information System (INIS)

Plasil, F.; Albrecht, R.; Awes, T.C.

1987-01-01

QCD lattice calculations predict that, at sufficiently high energy densities, hadronic matter undergoes a transition to a new phase of matter, the quark-gluon plasma, in which quarks and gluons are deconfined over a relatively large volume. It has been suggested that collisions between heavy nuclei at ultrarelativistic energies may produce the energy densities, estimated to be greater than 2 to 3 GeV/fm 3 , necessary for this phase transition to occur. An important goal of the first experiments with ultrarelativistic heavy-ion beams at the SPS accelerator at CERN is to investigate the extent to which this suggestion is correct. The primary experimental quantity used for estimating the energy density is the transverse energy, E/sub T/. We present here energies measured at zero degrees, together with transverse energy measurements. Estimates of attained energy densities and preliminary transverse momentum distributions of neutral products are also presented. 24 refs., 7 figs
Collision-induced spectroscopy with long-range intermolecular interactions: A diagrammatic representation and the invariant form of the induced properties

International Nuclear Information System (INIS)

Kouzov, A. P.; Chrysos, M.; Rachet, F.; Egorova, N. I.

2006-01-01

Collision-induced properties of two interacting molecules a and b are derived by means of a general diagrammatic method involving M molecule-molecule and N photon-molecule couplings. The method is an extension of previous graphical treatments of nonlinear optics because it exhaustively determines interaction-induced polarization mechanisms in a trustworthy and handy fashion. Here we focus on long-range intermolecular interactions. Retardation effects are neglected. A fully quantum-mechanical treatment of the molecules is made whereas second quantization for the electromagnetic field, in the nonrelativistic approximation, is implicitly applied. The collision-induced absorption, Raman, and hyper-Raman processes are viewed and studied, through guiding examples, as specific cases N=1, 2, and 3, respectively. In Raman (N=2), the standard first-order (M=1) dipole-induced dipole term of the incremental polarizability, Δα, is the result of a coupling of the two photons with distinct molecules, a and b, which perturb each other via a dipole-dipole mechanism. Rather, when the two photons interact with the same molecule, a or b, the (N=2, M=1) graphs predict the occurrence of a nonlinear polarization mechanism. The latter is expected to contribute substantially to the collision-induced Raman bands by certain molecular gases
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 $^{...
A Method for Ship Collision Damage and Energy Absorption Analysis and its Validation

DEFF Research Database (Denmark)

Zhang, Shengming; Pedersen, Preben Terndrup

2017-01-01

For design evaluation, there is a need for a method which is fast, practical and yet accurate enough to deter-mine the absorbed energy and collision damage extent in ship collision analysis. The most well-known sim-plified empirical approach to collision analysis was made probably by Minorsky......, and its limitation is alsowell-recognised. The authors have previously developed simple expressions for the relation between theabsorbed energy and the damaged material volume which take into account the structural arrangements,the material properties and the damage modes. The purpose of the present paper...... is to re-examine thismethod’s validity and accuracy for ship collision damage analysis in ship design assessments by compre-hensive validations with experimental results from the public domain. In total, 20 experimental tests havebeen selected, analysed and compared with the results calculated using...
Modeling the radar scatter off of high-energy neutrino-induced particle cascades in ice

NARCIS (Netherlands)

de Vries, Krijn D.; van Eijndhoven, Nick; O'Murchadha, Aongus; Toscano, Simona; Scholten, Olaf

2017-01-01

We discuss the radar detection method as a probe for high-energy neutrino induced particle cascades in ice. In a previous work we showed that the radar detection techniqe is a promising method to probe the high-energy cosmic neutrino flux above PeV energies. This was done by considering a simplified
Quantum molecular dynamics study on energy transfer to the secondary electron in surface collision process of an ion

International Nuclear Information System (INIS)

Shibahara, M; Satake, S; Taniguchi, J

2008-01-01

In the present study the quantum molecular dynamics method was applied to an energy transfer problem to an electron during ionic surface collision process in order to elucidate how energy of ionic collision transfers to the emitted electrons. Effects of various physical parameters, such as the collision velocity and interaction strength between the observed electron and the classical particles on the energy transfer to the electron were investigated by the quantum molecular dynamics method when the potassium ion was collided with the surface so as to elucidate the energy path to the electron and the predominant factor of energy transfer to the electron. Effects of potential energy between the ion and the electron and that between the surface molecule and the electron on the electronic energy transfer were shown in the present paper. The energy transfer to the observed secondary electron through the potential energy term between the ion and the electron was much dependent on the ion collision energy although the energy increase to the observed secondary electron was not monotonous through the potential energy between the ion and surface molecules with the change of the ion collision energy

On the balance energy and nuclear dynamics in peripheral heavy-ion collisions

International Nuclear Information System (INIS)

Chugh, Rajiv; Puri, Rajeev K.

2010-01-01

We present here the system size dependence of balance energy for semi-central and peripheral collisions using quantum molecular dynamics model. For this study, the reactions of Ne 20 +Ne 20 , Ca 40 +Ca 40 , Ni 58 + Ni 58 , Nb 93 +Nb 93 , Xe 131 +Xe 131 , and Au 197 +Au 197 are simulated at different incident energies and impact parameters. A hard equation of state along with nucleon–nucleon cross-sections between 40 and 55 mb explains the data nicely. Interestingly, balance energy follows a power law ∝A τ for the mass dependence at all colliding geometries. The power factor τ is close to –1/3 in central collisions, whereas it is –2/3 for peripheral collisions suggesting stronger system size dependence at peripheral geometries. This also suggests that in the absence of momentum dependent interactions, Coulomb's interaction plays an exceedingly significant role. These results are further analyzed for nuclear dynamics at the balance point. (author)
Probing the nuclear matter at high baryon and isospin density with heavy ion collisions

International Nuclear Information System (INIS)

Di Toro, M.; Colonna, M.; Ferini, G.

2010-01-01

Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. High Energy Collisions are studied in order to access nuclear matter properties at high density. Particular attention is devoted to the selection of observables sensitive to the poorly known symmetry energy at high baryon density, of large fundamental interest, even for the astrophysics implications. Using fully consistent covariant transport simulations built on effective field theories we are testing isospin observables ranging from nucleon/cluster emissions, collective flows (in particular the elliptic, squeeze out, part) and meson production. The possibility to shed light on the controversial neutron/proton effective mass splitting in asymmetric matter is also stressed. The "symmetry" repulsion at high baryon density will also lead to an "earlier" hadron-deconfinement transition in n-rich matter. The phase transition of hadronic to quark matter at high baryon and isospin density is analyzed. Nonlinear relativistic mean field models are used to describe hadronic matter, and the MIT bag model is adopted for quark matter. The boundaries of the mixed phase and the related critical points for symmetric and asymmetric matter are obtained. Isospin effects appear to be rather significant. The binodal transition line of the (T,ρ B ) diagram is lowered in a region accessible to heavy ion collisions in the energy range of the new planned FAIR/NICA facilities. Some observable effects of the mixed phase are suggested, in particular a neutron distillation mechanism. Theoretically a very important problem appears to be the suitable treatment of the isovector part of the interaction in effective QCD lagrangian approaches. (author)
High energy heavy ion collisions: Lessons from relativistic heavy ion ...

Indian Academy of Sciences (India)

select events which respond to the observables correlated to the centrality of the collisions. .... pared to 130 GeV and is independent of centrality. Similar ..... observations, therefore coming out of these exclusive observables at RHIC directs.
Different fission behavior induced by heavy ion central and peripheral collisions

International Nuclear Information System (INIS)

Wu Enjiu; Zheng Jiwen; Xiao Zhigang; Zhang Chun; Tan Jilian; Yin Shuzhi; Wang Sufang; Jin Genming; Yin Xu; Song Mingtao; Jin Weiyang; Peng Xingping; Li Zuyu; Wu Heyu; He Zhiyong; Jiang Dongxing; Qian Xing

2000-01-01

Correlated fission fragments from the 40 Ar + 209 Bi reaction and their further correlation with α particles have been studied for peripheral and central collisions simultaneously. The existence of different fission behavior of hot nuclei formed in central and peripheral collisions was found from the systematic analysis of the mass and energy distributions of fission fragments as a function of the initial temperature of hot fissioning nuclei
Experiments on very high energy heavy ions

International Nuclear Information System (INIS)

Willis, W.J.

1981-01-01

In this paper I describe experimental techniques which could be used to investigate central collision of very high energy heavy ions. For my purposes, the energy range is defined by the number of pions produced, Nsub(π) >> 100, and consequently Nsub(π) >> Nsub(nucleon). In this regime we may expect that new phenomena will appear. (orig.)
Energy deposited in the high luminosity inner triplets of the LHC by collision debris

International Nuclear Information System (INIS)

Wildner, E.; Broggi, F.; Cerutti, F.; Ferrari, A.; Hoa, C.; Koutchouk, J.-P.; Mokhov, N.V.

2008-01-01

The 14 TeV center of mass proton-proton collisions in the LHC produce not only debris interesting for physics but also showers of particles ending up in the accelerator equipment, in particular in the superconducting magnet coils. Evaluations of this contribution to the heat, that has to be transported by the cryogenic system, have been made to guarantee that the energy deposition in the superconducting magnets does not exceed limits for magnet quenching and the capacity of the cryogenic system. The models of the LHC base-line are detailed and include description of, for energy deposition, essential elements like beam-pipes and corrector magnets. The evaluations made using the Monte-Carlo code FLUKA are compared to previous studies using MARS. For the consolidation of the calculations, a dedicated comparative study of these two codes was performed for a reduced setup
Isospin effects in intermediate energy heavy ion collision

International Nuclear Information System (INIS)

Liu Jianye; Zuo Wei; Yang Yanfang; Zhao Qiang; Guo Wenjun

2001-01-01

Based on the achievements for the intermediate energy heavy ion collision in authors' recent work and the progresses in the world, the isospin effects and the dependence of the entrance channel conditions on them in the intermediate energy heavy ion collisions were introduced, analysed and commended. From the calculation results by using isospin dependence quantum molecular dynamics, it is clear to see that the nuclear stopping power strongly depends on the in-medium isospin dependence nucleon-nucleon cross section and weakly on the symmetry potential in the energy region from about Fermi energy to 150 MeV/u and the intermediate mass fragment multiplicity also sensitively depends on the in-medium isospin dependent nucleon-nucleon cross section and weakly on the symmetry potential in a selected energy region. But the preequilibrium emission neutron-proton ratio is quite contrary, it sensitively depends on the symmetry potential and weakly on the in-medium isospin dependent nucleon-nucleon cross section. In addition to the nuclear stopping sensitively depending on the beam energy, impact parameter and the mass of colliding system and weakly on the neutron-proton ratio of the colliding systems with about the same mass, the preequilibrium emission neutron-neutron ratio sensitively depends on the beam energy and the neutron-proton ratio of colliding system, but weakly on the impact parameter. From above results it is proposed that the nuclear stopping is a new probe to extract the information on the in-medium isospin dependence nucleon-nucleon cross section in energy region from about Fermi energy to 150 MeV/u and the preequilibrium emission neutron-proton ratio is a good probe for extracting the information about the symmetry potential from the lower energy to about 150 MeV/u
Laser-induced interactions

International Nuclear Information System (INIS)

Green, W.R.

1979-01-01

This dissertation discusses some of the new ways that lasers can be used to control the energy flow in a medium. Experimental and theoretical considerations of the laser-induced collision are discussed. The laser-induced collision is a process in which a laser is used to selectively transfer energy from a state in one atomic or molecular species to another state in a different species. The first experimental demonstration of this process is described, along with later experiments in which lasers were used to create collisional cross sections as large as 10 - 13 cm 2 . Laser-induced collisions utilizing both a dipole-dipole interaction and dipole-quadrupole interaction have been experimentally demonstrated. The theoretical aspects of other related processes such as laser-induced spin-exchange, collision induced Raman emission, and laser-induced charge transfer are discussed. Experimental systems that could be used to demonstrate these various processes are presented. An experiment which produced an inversion of the resonance line of an ion by optical pumping of the neutral atom is described. This type of scheme has been proposed as a possible method for constructing VUV and x-ray lasers
Quark model and high-energy nuclear experiments

International Nuclear Information System (INIS)

Bialas, A.

1979-05-01

Theoretical aspects of the measurements of production of low transverse momentum secondaries in high-energy hadron-nucleus and nucleus-nucleus collisions are discussed. Applications of the quark model to those processes are discussed in some detail. 58 references
Quark model and high-energy nuclear experiments

Energy Technology Data Exchange (ETDEWEB)

Bialas, A.

1979-05-01

Theoretical aspects of the measurements of production of low transverse momentum secondaries in high-energy hadron-nucleus and nucleus-nucleus collisions are discussed. Applications of the quark model to those processes are discussed in some detail. 58 references.
Intermediate/high energy nuclear physics

International Nuclear Information System (INIS)

Vary, J.P.

1992-01-01

Progress during the last year is reviewed under the following topics: relativistic hadron--nucleus and nucleus--nucleus collisions (heavy meson production, photon production and fragmentation functions--direct photon production with the QCM and photon fragmentation functions, Cronin efffect and multiple scattering, effective nuclear parton distributions); solving quantum field theories in nonperturbative regime; light-front dynamics and high-spin states (soft form factor of the pion and nucleon for transverse and longitudinal momentum transfers, light front spinors for high-spin objects); high-energy spin physics; relativistic wave equations, quarkonia, and e + e - resonances; associated production of Higgs boson at collider energies, and microscopic nuclear many-body theory and reactions. 135 refs
Study of heavy ions collision at SIS energies with the detector FOPI; Etude des collisions d'ions lourds aux energies de SIS avec le detecteur FOPI

Energy Technology Data Exchange (ETDEWEB)

Bastid, N

1999-09-23

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

Science.gov (United States)

Peale, Stanton J.; Greenberg, R.

2009-09-01

A collision of a coorbiting satellite with Enceladus is proposed as the source of energy to power the observed plumes emanating from the south pole of the satellite. A coorbital would have impacted at a velocity only slightly above the escape velocity of Enceladus, which would likely be necessary to keep the collision gentle enough not to disrupt the old cratered terrain nearby. If the mass were 1% of Enceladus', the energy deposited can sustain the plumes for approximately 80,000 to 200,000 years at the estimated observed power of 6 to 15 GW, so the impact would have been quite recent. The collision at an arbitrary point would leave Enceladus with non-synchronous, non-principal-axis rotation and a significant obliquity. After subsuming the impactor's volume, the region around the impact point will have expanded in a manner consistent with the observed tectonic pattern. The ring-like expansion implied by the radial cracks suggests that the new principal axis of maximum moment of inertia could have passed through the impact point. Internal dissipation from precession of the spin axis about the axis of maximum moment of inertia in the body frame of reference and from tides raised on Enceladus cause the axes of spin and of maximum moment to converge as the spin is brought to a zero obliquity and synchronous rotation on a time scale that is extremely short compared to the lifetime of the plumes. Hence, the region of collision, which is hot, ends up at one of the poles where we find the plumes.
Hypernuclei, dibaryon and antinuclei production in high energy heavy ion collisions: Thermal production vs. coalescence

International Nuclear Information System (INIS)

Steinheimer, J.; Gudima, K.; Botvina, A.; Mishustin, I.; Bleicher, M.; Stöcker, H.

2012-01-01

We study the production of (hyper-)nuclei and dibaryons in most central heavy ion collisions at energies of E lab =1-160 A GeV. In particular we are interested in clusters produced from the hot and dense fireball. The formation rate of strange and non-strange clusters is estimated by assuming thermal production from the intermediate phase of the UrQMD-hydro hybrid model and alternatively by the coalescence mechanism from a hadronic cascade model. Both model types are compared in detail. For most energies we find that both approaches agree in their predictions for the yields of the clusters. Only for very low beam energies, and for dibaryons including Ξ's, we observe considerable differences. We also study the production of anti-matter clusters up to top RHIC energies and show that the observation of anti- 4 He and even anti- 4 Λ He is feasible. We have found a considerable qualitative difference in the energy dependence of the strangeness population factor R H when comparing the thermal production with the coalescence results.
Particle production in high energy nucleus-nucleus collisions

International Nuclear Information System (INIS)

Stock, R.

1985-05-01

Recent data on the production of pions and strange particles at the Bevalac and Synchrophasotron accelerators are reviewed, covering pion spectra and multiplicity distributions, Λ, K + and K - yields and spectra, and Λ polarization. Emphasis is placed on recent progress in determining the equation of state of compressed fireball nuclear matter from the observed pion yield in central collisions. Further, the information derived from apparent spectral temperatures is critically examined, along with a discussion of thermal and chemical equilibrium attainment in the reactions, as revealed by particle spectra and yields. (orig.)
Ab initio study of charge transfer in B2+ low-energy collisions with atomic hydrogen

Science.gov (United States)

Turner, A. R.; Cooper, D. L.; Wang, J. G.; Stancil, P. C.

2003-07-01

Charge transfer processes due to collisions of ground state B2+(2s 2S) ions with atomic hydrogen are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) method. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial and rotational coupling matrix elements obtained with the spin-coupled valence-bond approach. Total and state-selective cross sections and rate coefficients are presented. Comparison with the existing experiments shows our results to be in good agreement. When EMOCC cross sections with and without rotational coupling are small (400 eV/u, inclusion of rotational coupling increases the total cross section by 50% 80%, improving the agreement between the current calculations and experiments. For state-selective cross sections, rotational coupling induces mixing between different symmetries; however, its effect, especially at low collision energies, is not as important as had been suggested in previous work.
Quasi continuum vibrational of molecules and isotopic selectivity properties induced by collisions

International Nuclear Information System (INIS)

Angelie, Christian

1990-01-01

This research thesis proposes an overview of knowledge on vibrationally highly excited states of molecules. The author shows that the statistic quasi-continuum formed by these states is preceded by a quasi continuum of weak transitions with a lower energy, and that these transitions remain structured and very narrow up to the dissociation energy and beyond. Collisions between molecules excited in their quasi continuum are then studied. The author particularly analyses a new phenomenon of isotopic selectivity which is important for the dissociation of a molecule colliding another molecule. It appears that this selectivity regarding selectivity is due to a selectivity of transferred energy which paradoxically increases with the molecule vibrational content because of a resonance phenomenon of energies transferred by dipole-dipole interaction [fr
Centrality and collision system dependence of antiproton production from p+A to Au+Au collisions at AGS energies

International Nuclear Information System (INIS)

Sako, H.; Ahle, L.; Akiba, Y.

1997-12-01

Antiproton production in heavy ion collisions reflects subtle interplay between initial production and absorption by nucleons. Because the AGS energies (10--20 A·GeV/c) are close to the antiproton production threshold, antiproton may be sensitive to cooperative processes such as QGP and hadronic multi-step processes. On the other hand, antiproton has been proposed as a probe of baryon density due to large N anti N annihilation cross sections. Cascade models predict the maximum baryon density reaches about 10 times the normal nucleus density in central Au+Au collisions, where the strong antiproton absorption is expected. In this paper, the authors show systematic studies of antiproton production from p+A to Au+Au collisions
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.
Strangeness production in AA and pp collisions

Energy Technology Data Exchange (ETDEWEB)

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

2016-07-15

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

High Transverse Momentum Hadron Production in 400-GeV/c and 800-GeV/c Proton - Nucleon Collisions

Energy Technology Data Exchange (ETDEWEB)

Jaffe, David Edward [SUNY, Stony Brook

1987-08-01

Results of high transverse momentum hadron production in 400 Gev/c proton-proton and proton-deuteron and 800 Gev /c proton-proton collisions are presented in this dissertation. The transverse momentum range of the data was from 5.2 to 9.0 Gev/c for the 400 Gev/c collisions and from 3.6 to 11.0 Gev /c for the 800 Gev /c collisions; the data were centered around the proton-nucleon center-of-momentum production angle of 90°. Single pion invariant cross sections and particle ratios were measured at both energies and the unlike-sign dihadron correlation function was measured at the higher energy. The results are compared to previous experiments and the Lund model.
Turbulence-induced bubble collision force modeling and validation in adiabatic two-phase flow using CFD

Energy Technology Data Exchange (ETDEWEB)

Sharma, Subash L., E-mail: sharma55@purdue.edu [School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907-1290 (United States); Hibiki, Takashi; Ishii, Mamoru [School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907-1290 (United States); Brooks, Caleb S. [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois, Urbana, IL 61801 (United States); Schlegel, Joshua P. [Nuclear Engineering Program, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Liu, Yang [Nuclear Engineering Program, Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States); Buchanan, John R. [Bechtel Marine Propulsion Corporation, Bettis Laboratory, West Mifflin, PA 15122 (United States)

2017-02-15

Highlights: • Void distribution in narrow rectangular channel with various non-uniform inlet conditions. • Modeling of void diffusion due to bubble collision force. • Validation of new modeling in adiabatic air–water two-phase flow in a narrow channel. - Abstract: The prediction capability of the two-fluid model for gas–liquid dispersed two-phase flow depends on the accuracy of the closure relations for the interfacial forces. In previous studies of two-phase flow Computational Fluid Dynamics (CFD), interfacial force models for a single isolated bubble has been extended to disperse two-phase flow assuming the effect in a swarm of bubbles is similar. Limited studies have been performed investigating the effect of the bubble concentration on the lateral phase distribution. Bubbles, while moving through the liquid phase, may undergo turbulence-driven random collision with neighboring bubbles without significant coalescence. The rate of these collisions depends upon the bubble approach velocity and bubble spacing. The bubble collision frequency is expected to be higher in locations with higher bubble concentrations, i.e., volume fraction. This turbulence-driven random collision causes the diffusion of the bubbles from high concentration to low concentration. Based on experimental observations, a phenomenological model has been developed for a “turbulence-induced bubble collision force” for use in the two-fluid model. For testing the validity of the model, two-phase flow data measured at Purdue University are utilized. The geometry is a 10 mm × 200 mm cross section channel. Experimentally, non-uniform inlet boundary conditions are applied with different sparger combinations to vary the volume fraction distribution across the wider dimension. Examining uniform and non-uniform inlet data allows for the influence of the volume fraction to be studied as a separate effect. The turbulence-induced bubble collision force has been implemented in ANSYS CFX. The
Covariance analysis of symmetry energy observables from heavy ion collision

Directory of Open Access Journals (Sweden)

Yingxun Zhang

2015-10-01

Full Text Available Using covariance analysis, we quantify the correlations between the interaction parameters in a transport model and the observables commonly used to extract information of the Equation of State of Asymmetric Nuclear Matter in experiments. By simulating 124Sn + 124Sn, 124Sn + 112Sn and 112Sn + 112Sn reactions at beam energies of 50 and 120 MeV per nucleon, we have identified that the nucleon effective mass splitting is most strongly correlated to the neutrons and protons yield ratios with high kinetic energy from central collisions especially at high incident energy. The best observable to determine the slope of the symmetry energy, L, at saturation density is the isospin diffusion observable even though the correlation is not very strong (∼0.7. Similar magnitude of correlation but opposite in sign exists for isospin diffusion and nucleon isoscalar effective mass. At 120 MeV/u, the effective mass splitting and the isoscalar effective mass also have opposite correlation for the double n/p and isoscaling p/p yield ratios. By combining data and simulations at different beam energies, it should be possible to place constraints on the slope of symmetry energy (L and effective mass splitting with reasonable uncertainties.
\\psi (2S) enhancement in p-Pb collision as an indication of quark-gluon plasma formation at the Large Hadron Collider

Science.gov (United States)

Ganesh, S.; Singh, R., Captain; Mishra, M.

2018-03-01

Proton-nucleus collisions serve as an important baseline for the understanding and interpretation of the nucleus-nucleus collisions. These collisions have been employed to characterize the cold nuclear matter effects at SPS and Relativistic Heavy-Ion Collider energies for the past several years, as it was thought that quark-gluon plasma (QGP) is not formed in such collisions. However, at the Large Hadron Collider (LHC), there seems a possibility that QGP is formed during proton-lead (p-Pb) collisions. In this work, we have derived an expression for gluon induced excitation of J/\\psi to \\psi (2S), using pNRQCD, and show that the relative enhancement of \\psi (2S) vis-à-vis J/\\psi , especially at high p T , gives further indication that the QGP is indeed formed in p-Pb collisions at the most central collisions at LHC energy. J/\\psi and \\psi (2S) suppression effects seen at ALICE are also qualitatively explained.
The temporal development of collision cascades in the binary collision approximation

International Nuclear Information System (INIS)

Robinson, M.T.

1989-07-01

A modified binary collision approximation (BCA) was developed to allow explicit evaluation of the times at which projectiles in a collision cascade reach significant points in their trajectories, without altering the ''event-driven'' character of the model. The modified BCA was used to study the temporal development of cascades in copper and gold, initiated by primary atoms of up to 10 keV initial kinetic energy. Cascades generated with time-ordered collisions show fewer ''distant'' Frenkel pairs than do cascades generated with velocity-ordered collisions. In the former, the slower projectiles tend to move in less-damaged crystal than they do in the latter. The effect is larger in Au than in Cu and increases with primary energy. As an approach to cascade nonlinearities, cascades were generated in which stopped cascade atoms were allowed to be redisplaced in later encounters. There were many more redisplacements in time-ordered cascades than in velocity-ordered ones. Because of the additional stopping introduced by the redisplacement events, the cascades in which they were allowed had fewer defects than occurred otherwise. This effect also was larger in Au than in Cu and larger at high energies although most of the redisplacement encounters involved only low-energy particles. 13 refs., 5 figs., 4 tabs
Measurement of the very-forward energy spectrum in pp collisions at √(s) = 13 TeV with CMS

Energy Technology Data Exchange (ETDEWEB)

Baur, Sebastian; Akbiyik, Melike; Baus, Colin; Katkov, Igor; Ulrich, Ralf; Woehrmann, Hauke [Karlsruher Institut fuer Technologie (Germany)

2016-07-01

The energy spectrum dN/dE in pp collisions at a centre-of-mass energy of √(s)=13 TeV is measured with the CASTOR calorimeter of CMS at pseudorapidities -5.2>η>-6.6. The spectrum of the total energy, as well as the hadronic and electromagnetic energy, is presented and compared to models used to describe high-energy hadronic interactions. The performance also of model used to describe ultra-high energy cosmic ray air showers is tested, and the possible impact of the measurement on the air shower development is illustrated.
Studies on the dynamics of heavy ion collisions at intermediate energies

International Nuclear Information System (INIS)

David, C.; Hartnack, C; Aichelin, J.

1997-01-01

We use the Quantum Molecular Dynamics model for the investigation of the dynamics of heavy ion collisions at intermediate energies. A detailed comparison between different versions of the models demonstrate the influence of not exactly known parameters in the description of nuclei like interaction range or initial densities and thus describes the limits of predictive power. The dynamics of the reaction are discussed quite similarly in the different models. A radial expansion with a linear velocity profile is found at central collisions. A strong interaction of pions with nuclear matter is reported. This interaction is strongly influenced by the lifetime of baryonic resonances in nuclear matter. These lifetimes depend strongly on the mass distribution of the resonances. These mass distributions are influenced by the momentum distribution in the nuclei. Here the inclusion of the spectral function shows visible effects. These effects influence the energy dissipation in nuclei and thus enter e.g. into the analysis of p + A collisions for the GEDEON project. (author)
Theory of low energy collisions; Theorie des collisions a basse energie

Energy Technology Data Exchange (ETDEWEB)

Sparenberg, J.M. [Universite Libre de Bruxelles, Bruxelles (Belgium)

2007-07-01

The basic notions of low-energy quantum scattering theory are introduced (cross sections, phase shifts, resonances,... ), in particular for positively-charged particles, in view of nuclear physics applications. An introduction to the reaction-matrix (or R-matrix) method is then proposed, as a tool to both solve the Schroedinger equation describing collisions and fit experimental data phenomenologically. Most results are established without proof but with a particular emphasis on their intuitive understanding and their possible analogs in classical mechanics. Several choices are made consequently: (i) the text starts with a detailed reminder of classical scattering theory, (ii) the concepts are first introduced in ideal theoretical cases before going to the more complicated formalism allowing the description of realistic experimental situations, (iii) a single example is used throughout nearly the whole text, (iv) all concepts are established for the elastic scattering of spinless particles, with only a brief mention of their multichannel generalization at the end of the text. (author)
Deconfinement and nuclear collisions

International Nuclear Information System (INIS)

Sarma, Nataraja

1992-01-01

Expensive experiments to detect a deconfined parton phase have been done and are being planned. In these experiments it is hoped that nuclear collisions at relativistic energies will exhibit signals of this new phase. So far all the results may be interpreted in terms of independent nucleon-nucleon interactions. These elementary collisions at very high energies are therefore worth examination since each such collision produces a highly excited entity which emits a large number of hadrons. In the hadronic phase this results in the GS multiplicity distribution. In the parton phase, parton branching results in the popular negative binomial distribution. Though neither the GS nor the NB distribution alone agrees with the data beyond 200 GeV, it is fitted exceedingly well by a weighted sum of the two distributions. Since the negative binomial distribution arises from the branching of partons, we interpret the increase with energy of the negative binomial component in the weighted sum as the onset of a deconfined phase. The rising cross section for the negative binomial component parallels very closely the inclusive cross section for hadron jets which is also considered a consequence of partons branching. The consequences of this picture to nuclear collisions is discussed. (author). 8 refs., 9 figs., 3 tabs
Systematics of atom-atom collision strengths at high speeds

International Nuclear Information System (INIS)

Gillespie, G.H.; Inokuti, M.

1980-01-01

The collision strengths for atom-atom collisions at high speeds are calculated in the first Born approximation. We studied four classes of collisions, distinguished depending upon whether each of the collision partners becomes excited or not. The results of numerical calculations of the collision strengths are presented for all neutral atoms with Z< or =18. The calculations are based on atomic form factors and incoherent scattering functions found in the literature. The relative contribution of each class of collision processes to the total collision cross section is examined in detail. In general, inelastic processes dominate for low-Z atoms, while elastic scattering is more important for large Z. Other systematics of the collision strengths are comprehensively discussed. The relevant experimental literature has been surveyed and the results of this work for the three collision systems H-He, He-He, and H-Ar are compared with the data for electron-loss processes. Finally, suggestions are made for future work in measurements of atom-atom and ion-atom collision cross sections
Production of dimeson atoms in high-energy collisions

Energy Technology Data Exchange (ETDEWEB)

Afanasyev, L.; Gevorkyan, S.; Voskresenskaya, O. [Joint Institute for Nuclear Research, Dubna (Russian Federation)

2017-04-15

The production of two-meson electromagnetic bound states and free meson pairs π{sup +}π{sup -}, K{sup +}K{sup -}, π{sup +}K{sup -+} in relativistic collisions has been considered. It is shown that using of exact Coulomb wave functions for dimeson atom (DMA) allows one to calculate the yield of discrete states with the desired accuracy. The relative probabilities of production of DMA and meson pairs in the free state are estimated. The amplitude of DMA transition from 1S to 2P state, which is essential for the pionium Lamb shift measurements, has been obtained. (orig.)
A perspective on relativistic nuclear collisions

International Nuclear Information System (INIS)

Glendenning, N.K.; Paris-11 Univ., 91 - Orsay

1979-01-01

A quasi-dynamical model for the disassembly of a high energy hadronic fireball has been developed. It is fund that some signals from the early high density stage are expected to survive the expansion stage. Indeed cetain signals, the π /N and K / N ratio at high kinetic energy, are so qualitatively unique in their dependance on target projectile mass, that we believe they will survive a refinement of the collision dynamics. Therefore a determination of the assymptotic form of the hadron spectrum can be made by studying nuclear collisions. The required energies are high (approximately 10 GeV/ nucleon in C.M.), but they are within the reach of present technology
Isospin equilibrium and non-equilibrium in heavy-ion collisions at intermediate energies

International Nuclear Information System (INIS)

Chen Liewen; Ge Lingxiao; Zhang Xiaodong; Zhang Fengshou

1997-01-01

The equilibrium and non-equilibrium of the isospin degree of freedom are studied in terms of an isospin-dependent QMD model, which includes isospin-dependent symmetry energy, Coulomb energy, N-N cross sections and Pauli blocking. It is shown that there exists a transition from the isospin equilibrium to non-equilibrium as the incident energy from below to above a threshold energy in central, asymmetric heavy-ion collisions. Meanwhile, it is found that the phenomenon results from the co-existence and competition of different reaction mechanisms, namely, the isospin degree of freedom reaches an equilibrium if the incomplete fusion (ICF) component is dominant and does not reach equilibrium if the fragmentation component is dominant. Moreover, it is also found that the isospin-dependent N-N cross sections and symmetry energy are crucial for the equilibrium of the isospin degree of freedom in heavy-ion collisions around the Fermi energy. (author)
[Electron transfer, ionization, and excitation in atomic collisions

International Nuclear Information System (INIS)

1992-01-01

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

Science.gov (United States)

Wu, Benjamin; Tan, Jonathan C.; Nakamura, Fumitaka; Christie, Duncan; Li, Qi

2018-05-01

We investigate collisions between giant molecular clouds (GMCs) as potential generators of their internal turbulence. Using magnetohydrodynamic (MHD) simulations of self-gravitating, magnetized, turbulent GMCs, we compare kinematic and dynamic properties of dense gas structures formed when such clouds collide compared to those that form in non-colliding clouds as self-gravity overwhelms decaying turbulence. We explore the nature of turbulence in these structures via distribution functions of density, velocity dispersions, virial parameters, and momentum injection. We find that the dense clumps formed from GMC collisions have higher effective Mach number, greater overall velocity dispersions, sustain near-virial equilibrium states for longer times, and are the conduit for the injection of turbulent momentum into high density gas at high rates.
J/ψ production as a function of charged particle multiplicity in proton + proton collisions at LHC energies

International Nuclear Information System (INIS)

Thakur, Dhananjaya; De, Sudipan; Sahoo, Raghunath; Dansana, Soumya

2017-01-01

In high energy proton-proton collisions the total event multiplicity can have a substantial contribution from Multi-Parton Interactions (MPI), which is an Underlying Event observable. The sum of all processes that build up the final hadronic state in a collision is referred as the Underlying Event (UE). The Underlying Event includes fragmentation of beam remnant, multi-partonic interactions, and initial and final state radiation (ISR/FSR) associated with each interactions. In MPI, several interactions at the partonic level occurs in a single p+p collision, that leads to a strong dependence of particle production on total event multiplicity. MPI are commonly used to describe the soft underlying events such as the production of light quarks and gluons. But it is observed that it can also contribute on the hard and semi-hard scale such as the production of particles containing heavy quarks like J/ψ, open heavy flavors etc. This contribution become more and more relevant with increasing energy
Nonlinear energy loss of highly charged heavy ions

International Nuclear Information System (INIS)

Zwicknagel, G.Guenter.

2000-01-01

For slow, highly charged heavy ions strong coupling effects in the energy transfer from the projectile-ion to an electron target plasma become important. A theoretical description of this nonlinear ion stopping has to go beyond the standard approaches like the dielectric linear response or the binary collision model which are strictly valid only at weak ion-target coupling. Here we outline an improved treatment which is based on a suitable combination of binary collision and linear response contributions. As has been verified for isotropic, nonmagnetized electron plasmas by comparison with simulations, this approach well reproduces the essential features of nonlinear stopping up to moderate coupling strength. Its extension to anisotropic, magnetized electron plasmas basically involves the fully numerical determination of the momentum and energy transfer in binary ion-electron collisions in the presence of a magnetic field. First results of such calculations are presented and discussed
Strangeness production in heavy ion collisions

International Nuclear Information System (INIS)

Redlich, K.

2001-05-01

Strangeness production in heavy ion collisions is discussed in a broad energy range from SIS to RHIC. In the whole energy range particle yields are showing high level of chemical equilibration which can be described by the unified freezeout conditions of fixed energy/particle ≅ 1GeV. The statistical model within the canonical formulation of strangeness conservation provides a framework to describe the observed enhancement of (multi)strange particles from p+A to A+A collisions measured at the SPS energy and predicts that this enhancement should be larger for decreasing collision energy. However, only at the SPS and RHIC chemical freezeout temperature is consistent within error with the critical value required for deconfinement and simultaneously strangeness is uncorrelated and distributed in the whole volume of the fireball. (orig.)
Ion-atom collisions with laser-prepared target: High resolution study of single charge exchange process

International Nuclear Information System (INIS)

Leredde, Arnaud

2012-01-01

Single charge transfer in low-energy Na"++"8"7Rb(5s,5p) collisions is investigated using magneto-optically trapped Rb atoms and high-resolution recoil-ion momentum spectroscopy. The three-dimensional reconstruction of the recoil-ion momentum provides accurate relative cross-sections for the active channels and the projectile scattering angle distributions. Thanks to the high experimental resolution, scattering structures such as diffraction-like oscillations in angular distributions are clearly observed. The measurements are compared with molecular close-coupling calculations and an excellent agreement is found. To go further in the test of the theory, the target is prepared in an oriented state. It is the first time that such collision experiments with oriented target is performed with such a high resolution. The right-left asymmetry expected for the scattering angle distribution is evidenced. The agreement between MOCC calculations and experiments is very good. Simple models developed for collisions with oriented target are also discussed. (author) [fr
Statistical calculation of complete events in medium-energy nuclear collisions

International Nuclear Information System (INIS)

Randrup, J.

1984-01-01

Several heavy-ion accelerators throughout the world are presently able to deliver beams of heavy nuclei with kinetic energies in the range from tens to hundreds of MeV per nucleon, the so-called medium or intermediate energy range. At such energies a large number of final channels are open, each consisting of many nuclear fragments. The disassembly of the collision system is expected to be a very complicated process and a detailed dynamical description is beyond their present capability. However, by virtue of the complexity of the process, statistical considerations may be useful. A statistical description of the disassembly yields the least biased expectations about the outcome of a collision process and provides a meaningful reference against which more specific dynamical models, as well as the data, can be discussed. This lecture presents the essential tools for formulating a statistical model for the nuclear disassembly process. The authors consider the quick disassembly (explosion) of a hot nuclear system, a so-called source, into multifragment final states, which complete according to their statistical weight. First some useful notation is introduced. Then the expressions for exclusive and inclusive distributions are given and the factorization of an exclusive distribution into inclusive ones is carried out. In turn, the grand canonical approximation for one-fragment inclusive distributions is introduced. Finally, it is outlined how to generate a statistical sample of complete final states. On this basis, a model for statistical simulation of complete events in medium-energy nuclear collisions has been developed

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