192 results on '"H. W. Barz"'
Search Results
2. On the space-time difference of proton and composite particle emission in central heavy-ion reactions at 400 A· MeV
- Author
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M. Eskef, A. Somov, K. Wiśniewski, R. Kotte, D. Pelte, Y. Leifels, Philippe Crochet, Mihai Petrovici, D. Schüll, N. Cindro, N. Bendarag, Byung-Sik Hong, Alexandre Lebedev, W. Neubert, Nicole Bastid, Pascal Dupieux, Peter Wagner, M. Kowalczyk, D. Wohlfarth, K. S. Lee, T. Kress, J. P. Alard, H. Merlitz, M. Dželalija, Z. Basrak, Y. Yushmanov, Y. Grishkin, D. Moisa, Z. Fodor, W. Reisdorf, A. Gobbi, A. Devismes, V. Simion, B. de Schauenburg, Vladislav Manko, H. W. Barz, Ralf Peter Averbeck, R. Kutsche, A. Zhilin, M. Korolija, J. T. Yang, K. D. Hildenbrand, C. Plettner, R. Čaplar, M. Kirejczyk, Y. J. Kim, Z. Seres, Gabriel Stoicea, M. A. Vasiliev, J. Kecskemeti, A. Nianine, G. Berek, K. Siwek-Wilczyńska, Anton Andronic, K. S. Sim, N. Herrmann, B. Sikora, Fouad Rami, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and FOPI
- Subjects
Physics ,Nuclear and High Energy Physics ,Proton ,010308 nuclear & particles physics ,Hadron ,Relative velocity ,Radius ,heavy-ion ,correlation function ,space-time ,[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] ,01 natural sciences ,Charged particle ,Ion ,Nuclear physics ,Correlation function (statistical mechanics) ,0103 physical sciences ,Nuclear fusion ,Atomic physics ,010306 general physics - Abstract
Small-angle correlations of pairs of nonidentical light charged particles produced in central collisions of heavy ions in the A= 100 mass region at a beam energy of 400 A· MeV are investigated with the FOPI detector system at GSI Darmstadt. The difference of longitudinal correlation functions with the relative velocity parallel and anti-parallel to the center-of-mass velocity of the pair in the central source frame is studied. This method allows extracting the apparent space-time differences of the emission of the charged particles. Comparing the correlations with results of a final-state interaction model delivers quantitative estimates of these asymmetries. Time delays as short as 1~fm/c or – alternatively – source radius differences of a few tenth fm are resolved. The strong collective expansion of the participant zone introduces not only an apparent reduction of the source radius but also a modification of the emission times. After correcting for both effects a complete sequence of the space-time emission of p, d, t, 3He, α particles is presented for the first time.
- Published
- 1999
3. Statistical fragmentation of Au projectiles atE/A=600 MeV
- Author
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J. Hubele, Gerd Joachim Kunde, H. Sann, W. A. Friedman, M. Begemann-Blaich, C. Ngô, P. Kreutz, G. Imme, J. Pochodzalla, Alfred R. Deangelis, I. Iori, D.H.E. Gross, H.R. Jaqaman, P. Bouissou, Z. Liu, W. Seidel, U. Lynen, U. Milkau, R. Heck, A. Tucholski, H. Schulz, J.C. Adloff, Robert Meijer, G. Raciti, W. F. J. Müller, L. Stuttge, A. Schüttauf, S. Leray, R. J. Charity, V. Lindenstruth, W. Trautmann, C. A. Ogilvie, G. Rudolf, A. Moroni, and H. W. Barz
- Subjects
Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Projectile ,Isotopes of copper ,Computer Science::Information Retrieval ,Nuclear Theory ,Breakup ,Fragmentation (mass spectrometry) ,Incident energy ,Isotopes of gold ,Atomic physics ,Nuclear Experiment ,Excitation - Abstract
The mean multiplicity of intermediate mass fragments (IMF) {l angle}{ital M}{sub IMF}{r angle} produced by fragmentation of Au projectiles interacting with targets of C, Al, Cu, and Pb at an incident energy of {ital E}/{ital A}=600 MeV is compared to predictions of statistical multifragmentation and sequential evaporation models. The initial conditions for the calculations were provided by Boltzmann-Uehling-Uhlenbeck simulations. In the high excitation energy regime where the IMF multiplicity reaches its maximum the observed universal correlation between {l angle}{ital M}{sub IMF}{r angle} and the total charge {ital Z}{sub bound} of projectile fragments with charges {ital Z}{ge}2 cannot be reproduced by a sequential evaporation code. In this regime the data are better described by statistical decay calculations which assume the formation of an expanded nuclear system and a rather fast breakup.
- Published
- 1992
4. Thermal particle production at SIS?
- Author
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H. W. Barz, B. Kämpfer, and György Wolf
- Subjects
Physics ,Nuclear physics ,Nuclear and High Energy Physics ,Nuclear Theory ,Thermal ,Particle ,Nuclear Experiment ,Nucleon - Abstract
In a transport model calculation we study some of the basic assumptions of thermal models, We find that at SIS energies the particles are mainly produced in a highly non-equilibrium situation, At freeze-out only nucleons are thermalized.
- Published
- 1999
5. Description of the nuclear stopping process within anisotropic thermo-hydrodynamics
- Author
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H. W. Barz, B. Lukács, Burkhard Kampfer, and Gy. Wolf
- Subjects
Physics ,Momentum ,Nuclear and High Energy Physics ,Distribution (mathematics) ,Scientific method ,Nuclear Theory ,Mechanics ,Statistical physics ,Nuclear Experiment ,Anisotropy ,Nucleon ,Generalized hydrodynamics - Abstract
A generalized hydrodynamics is presented, which takes into account the anisotropy of the nucleon momentum distribution. The dynamics of the nuclear stopping process is studied in this framework.
- Published
- 1990
6. In-Medium Effects on Phase Space Distributions of Antikaons Measured in Proton-Nucleus Collisions
- Author
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B. Kämpfer, Eckart Grosse, Andreas Wagner, E. Schwab, Peter Senger, W. Waluś, A. Förster, F. Dohrmann, L. Naumann, B. Kohlmeyer, W. Scheinast, C. Sturm, G. Surówka, M. Menzel, F. Laue, H. W. Barz, F. Uhlig, P. Koczon, Y. Shin, I. Böttcher, H. Ströbele, and M. Debowski
- Subjects
Physics ,Meson ,Nuclear Theory ,General Physics and Astronomy ,Strangeness ,Nuclear physics ,medicine.anatomical_structure ,Phase space ,medicine ,Physics::Accelerator Physics ,Atomic physics ,Multiplicity (chemistry) ,Nuclear Experiment ,Proton density ,Beam energy ,Nucleus - Abstract
Differential production cross sections of ${K}^{\ifmmode\pm\else\textpm\fi{}}$ mesons have been measured in $p+\mathrm{C}$ and $p+\mathrm{Au}$ collisions at 1.6, 2.5, and 3.5 GeV proton beam energy. At beam energies close to the production threshold, the ${K}^{\ensuremath{-}}$ multiplicity is strongly enhanced with respect to proton-proton collisions. According to microscopic transport calculations, this enhancement is caused by two effects: the strangeness exchange reaction $NY\ensuremath{\rightarrow}{K}^{\ensuremath{-}}NN$ and an attractive in-medium ${K}^{\ensuremath{-}}N$ potential at saturation density.
- Published
- 2006
7. Transport Theories for Heavy-Ion Collisions in the 1 AGeV Regime
- Author
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J. Aichelin, Che Ming Ko, Elena Bratkovskaya, C. Fuchs, M. Reiter, H. W. Barz, Theodoros Gaitanos, Wolfgang Cassing, Pawel Danielewicz, Alexei Larionov, Marcus Bleicher, C. Hartnack, Gy. Wolf, Lie-Wen Chen, Evgeni E. Kolomeitsev, Laboratoire SUBATECH Nantes (SUBATECH), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), J. Cleymans, P. Steinberg, and Z. Vilakazi
- Subjects
Physics ,Nuclear and High Energy Physics ,Nuclear Theory ,[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th] ,010308 nuclear & particles physics ,FOS: Physical sciences ,7. Clean energy ,01 natural sciences ,Nuclear Theory (nucl-th) ,Nuclear physics ,Pion ,0103 physical sciences ,Transverse momentum ,Rapidity ,Heavy ion ,ddc:530 ,High Energy Physics::Experiment ,Astrophysics::Earth and Planetary Astrophysics ,010306 general physics ,Nuclear Experiment - Abstract
We compare multiplicities as well as rapidity and transverse momentum distributions of protons, pions and kaons calculated within presently available transport approaches for heavy ion collisions around 1 AGeV. For this purpose, three reactions have been selected: Au+Au at 1 and 1.48 AGeV and Ni+Ni at 1.93 AGeV., 15 pages, 13 figures, proceedings of Strange Quark Matter 2004, Cape Town, South Africa
- Published
- 2005
8. ϕmeson production in near-threshold proton-nucleus collisions
- Author
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H. W. Barz and M. Zétényi
- Subjects
Physics ,Nuclear and High Energy Physics ,Particle physics ,Meson production ,Nuclear Theory ,Proton ,Meson ,FOS: Physical sciences ,Phi meson production ,Electron ,Nuclear Theory (nucl-th) ,Nuclear physics ,Near threshold ,medicine.anatomical_structure ,medicine ,mass dependence of cross section ,High Energy Physics::Experiment ,Production (computer science) ,proton-nucleus collisions ,Nuclear Experiment ,Nucleus ,Nuclear theory - Abstract
The cross section for production of Phi mesons in proton-nucleus reactions is calculated as a function of the target mass. The decay width of the Phi meson is affected by the change of the masses of the Phi, K+ and K- mesons in the medium. A strong attractive K- potential leads to a measurable change of the behavior of the cross section as a function of of the target mass. Comparison between the kaon and electron decay modes are made., 4 pages, 1figure, new figure, new references
- Published
- 2004
9. Contribution of the nucleon-hyperon reaction channels toK−production in proton-nucleus collisions
- Author
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Lutz Naumann and H. W. Barz
- Subjects
Nuclear reaction ,Physics ,Nuclear and High Energy Physics ,Particle physics ,Proton ,Meson ,High Energy Physics::Phenomenology ,Nuclear Theory ,Hadron ,Hyperon ,Elementary particle ,Nuclear physics ,High Energy Physics::Experiment ,Production (computer science) ,Nuclear Experiment ,Nucleon - Abstract
The cross sections for producing ${K}^{\ensuremath{-}}$ mesons in nucleon-hyperon elementary processes are estimated assuming one-pion exchange and using the experimentally known pion-hyperon cross sections. The results are implemented in a transport model which is applied to calculation of proton-nucleus collisions. In significant difference to earlier estimates for heavy-ion collisions the inclusion of the nucleon-hyperon cross section roughly doubles the ${K}^{\ensuremath{-}}$ production in near-threshold proton-nucleus collisions.
- Published
- 2003
10. Combined effects of nuclear Coulomb field, radial flow, and opaqueness on two-pion correlations
- Author
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H. W. Barz
- Subjects
Physics ,Source function ,Nuclear and High Energy Physics ,Field (physics) ,Nuclear Theory ,FOS: Physical sciences ,Nuclear matter ,Nuclear Theory (nucl-th) ,Momentum ,Nuclear physics ,symbols.namesake ,Pion ,Quantum electrodynamics ,Coulomb ,symbols ,High Energy Physics::Experiment ,Wave function ,Nuclear Experiment ,Klein–Gordon equation - Abstract
Correlations of two like charged pions emitted from a hot and charged spherically expanding nuclear system are investigated. The motion of the pions is described quantum mechanically using the Klein-Gordon equation which includes Coulomb field and pion absorption. Flow modifies the radial distribution of the source function and rescales the pion wave functions. The radii extracted from the correlation functions are calculated in sideward and outward direction as a function of the pair momentum. Comparison with recent measurements at SIS and AGS energies is made., 13 pages and 4 figures
- Published
- 1998
11. Analysis of hard two-photon correlations measured in heavy-ion reactions at intermediate energies
- Author
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Wolfgang Bauer, Gy. Wolf, H. W. Barz, and Burkhard Kampfer
- Subjects
Physics ,Nuclear and High Energy Physics ,Photon ,010308 nuclear & particles physics ,Nuclear Theory ,Correlation function (quantum field theory) ,01 natural sciences ,7. Clean energy ,Nuclear physics ,Two-photon excitation microscopy ,0103 physical sciences ,Production (computer science) ,Heavy ion ,Atomic physics ,Nuclear Experiment ,010306 general physics ,Nucleon ,Nuclear Physics - Abstract
Analysis of hard two-photon correlations measured in heavy-ion reactions at intermediate energies H.W.Barz1,2, B.Kämpfer1,2, GY. Wolf3,4, W. Bauer5 1Institut für Kern- und Hadronenphysik, FZ Rossendorf, PF 510119, 01314 Dresden, Germany 1Institut für Theoretische Physik, TU Dresden, Momrnsenstr. 13, 01062 Dresden, Germany 3GSI Darmstadt, PF 110552, 64220 Darmstadt, Germany 4KFKI RMKI Budapest, POB. 49, H-1525 Budapest, Hungary MSU Michigan, East Lansing, MI 48824, USA Abstract Recently reported measurements of hard photon correlations in the reactions 36Ar On 27Al at 95 A*MeV, 86Kr on natNi at 60 A*MeV, and 181Ta on 197Au at 39.5 A*MeV are analyzed. A Boltzmann-Ühling-Uhlenbeck transport model is used to describe the photon production by individual nucleon-nucleon collisions. In the lighter systems we find the best agreement with data when taking into account only the photons from first chance collisions of nucleons or photons produced during the Passage of the nuclei, while the model predicts also a considerable late-time emission of photons which leads to a depletion of the calculated correlation function. The accuracy of the present data daas not allow firm conclusions on the reliability of this late time evolution. Our inveatigatiions do not support a recently reported interference pattern in the heavy Ta + Au system.
- Published
- 1995
12. Transport Treatment Of An Expanding Pion Gas in Ultrarelativistic Heavy Ion Collisions
- Author
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H. W. Barz, H. Schulz, G. M. Welke, George F. Bertsch, and Pawel Danielewicz
- Subjects
Physics ,Particle physics ,Thermalisation ,Pion ,Meson ,Nuclear Theory ,High Energy Physics::Experiment ,Plasma ,Nuclear Experiment ,Boltzmann equation ,Spectral line ,Hadronization ,Ion - Abstract
In ultrarelativistic collisions of heavy ions a hot central region is formed that subsequently decays mostly into π mesons. One of the main goals of the theory of collisions is to trace the evolution of the hot initial zone until the stage when the freezeout occurs. For this purpose one has to study the dynamics of the pionic gas. One of the problems to be solved is, to what extent the observed pion spectra and, in particular, the enhancement at low momenta have to be associated with the formation of a hot and dense pionic zone right after the hadronization. In other words, one has to find out, whether in the rapidly expanding pion cloud the ππ collisions arc effective and frequent enough to thermalize the distribution of the pions. If not, the experimentally observed distribution of the pions might be remainder of the hadronization process itself and could give us, for example, information on whether the pions originate from a hadronizing plasma blob or not.
- Published
- 1994
13. Stability of detonation fronts leading to quark-gluon plasma
- Author
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B. Kämpfer, B. Lukács, L. P. Csernai, and H. W. Barz
- Subjects
Physics ,Shock wave ,Quark ,Phase transition ,Particle physics ,Astrophysics::High Energy Astrophysical Phenomena ,Nuclear Theory ,Detonation ,Plasma ,Nuclear matter ,Strange matter ,Quantum electrodynamics ,Quark–gluon plasma ,Astrophysics::Galaxy Astrophysics - Abstract
The transition from nuclear matter to quark matter in shock fronts is discussed. The relativistic shock equations are considered and applied to quark-matter production in dependence on the bag constant. The problem of shock splitting is discussed as a possible signature of the phase transition. One-dimensional hydrodynamical calculations for a two-phase system of nuclear matter and quark plasma are presented and compared to results of the shock equations for stable and unstable shock fronts.
- Published
- 1985
14. Energy dependence of the production of pions, kaons and antikaons calculated in the hadrochemical model
- Author
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J. Zimányi, B. Lukács, Tamás S. Biró, and H. W. Barz
- Subjects
Physics ,Nuclear and High Energy Physics ,Range (particle radiation) ,High Energy Physics::Phenomenology ,Nuclear Theory ,chemistry.chemical_element ,Nuclear physics ,Neon ,Pion ,chemistry ,Nuclear fusion ,High Energy Physics::Experiment ,Heavy ion ,Atomic physics ,Nuclear Experiment - Abstract
Cross sections for production of pions, kaons and antikaons in heavy ion reactions are calculated in the framework of the hadrochemical model. For the reaction Ne on NaF satisfactory agreement to the measured data is reached in a wide range of energies. The importance of consecutive hadron-hadron collisions for the mass dependence is shown.
- Published
- 1983
15. Dynamical aspects of the transition from nuclear matter to a quark-gluon plasma in heavy ion collisions
- Author
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L. P. Csernai, B. Lukács, Burkhard Kampfer, and H. W. Barz
- Subjects
Physics ,Hagedorn temperature ,Nuclear and High Energy Physics ,Particle physics ,High Energy Physics::Phenomenology ,Nuclear Theory ,Nuclear matter ,Nuclear physics ,Strange matter ,Quark star ,Latent heat ,Quark–gluon plasma ,State of matter ,High Energy Physics::Experiment ,Nuclear Experiment ,Nucleon - Abstract
Taking into account a finite conversion rate the transition of nuclear matter to quark-gluon matter and vice versa is treated in a hydrodynamical model for heavy ion collisions. For fast conversion pure quark matter is formed for laboratory energies between 4 and 10 GeV per nucleon while below 4 GeV per nucleon matter stays in a mixed phase. Due to the large amount of latent heat the temperature does not exceed k T = 160 MeV.
- Published
- 1984
16. Notable abbreviations in telecommunications
- Author
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H W Barz
- Subjects
Computer Networks and Communications ,Software - Published
- 1987
17. Two-fluid hydrodynamics applied to the deconfinement transition in the fragmentation region in ultra-relativistic nuclear collisions
- Author
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H. W. Barz, Burkhard Kampfer, L.P. Csernai, and B. Lukács
- Subjects
Nuclear reaction ,Physics ,Nuclear and High Energy Physics ,High Energy Physics::Lattice ,High Energy Physics::Phenomenology ,Nuclear Theory ,Plasma ,Nuclear matter ,Deconfinement ,Nuclear physics ,Fragmentation (mass spectrometry) ,Quark–gluon plasma ,High Energy Physics::Experiment ,Color confinement ,Nuclear Experiment ,Two fluid - Abstract
A two-fluid model is presented which describes the interpenetration of nuclei colliding at ultra-relativistic energies. The two fluids are coupled by friction resulting from hadron-hadron collisions. The model calculations predict the deconfinement transition in the baryon-rich fragmentation region. The degree of the conversion and the maximum temperature depend sensitively on the characteristic time for the rearrangement of nuclear matter into the quark-gluon plasma.
- Published
- 1987
18. On the role of the delta resonances in high energy heavy ion reactions
- Author
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B. Lukács, G. Fái, H. W. Barz, Bo Jakobsson, and J. Zimányi
- Subjects
Physics ,Nuclear and High Energy Physics ,Proton ,High Energy Physics::Lattice ,Nuclear Theory ,Elementary particle ,Spectral line ,Delta baryon ,Nuclear physics ,Particle decay ,Pion ,Nuclear fusion ,High Energy Physics::Experiment ,Heavy ion ,Atomic physics ,Nuclear Experiment - Abstract
Proton and pion spectra from relativistic heavy ion collisions are calculated in the framework of a hydrochemical model. An explanation of the striking absence of the delta decay pion peak in the observed pion spectra is suggested.
- Published
- 1981
19. Subthreshold Pion Production and Statistical Multifragmentation in Nucleus-Nucleus Collisions
- Author
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H. W. Barz, J. Lopez, J. P. Bondorf, H. Schulz, and C. Guet
- Subjects
Nuclear physics ,Physics ,Particle physics ,medicine.anatomical_structure ,Pion ,Intermediate energy ,Subthreshold conduction ,Nuclear Theory ,medicine ,General Physics and Astronomy ,Nuclear Experiment ,Collision ,Nucleus - Abstract
It is shown that subthreshold pion production in a collision between two nuclei at intermediate energy has to be attributed to an early stage of the collision and cannot take place together with a multifragmentation break-up at a later stage of the collision.
- Published
- 1987
20. Deconfinement transition in anisotropic matter
- Author
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H. W. Barz, B. Lukács, Gy. Wolf, Burkhard Kampfer, and K. Martinás
- Subjects
Quark ,Physics ,Nuclear and High Energy Physics ,Condensed matter physics ,Plasma formation ,Nuclear transparency ,Phase equilibrium ,Relative velocity ,Anisotropy ,Deconfinement ,Phase diagram - Abstract
Because of nuclear transparency at beam energies relevant to quark plasma formation, the extension of phase equilibrium conditions for interpenetrating pieces of matter is investigated. Applying this thermodynamical formalism to the deconfinement transition a non-trivial change is found on the phase diagram, due to the relative velocity of the interpenetrating matter elements.
- Published
- 1987
21. Strange particle production in the hadrochemical model
- Author
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B. Lukács, H. W. Barz, J. Zimányi, and Tamás S. Biró
- Subjects
Physics ,Nuclear physics ,Nuclear and High Energy Physics ,Particle physics ,Strange quark ,Cascade ,Nuclear Theory ,Production model ,Hyperon ,Interaction model ,Heavy ion ,Nuclear Experiment - Abstract
Strange particle production in heavy ion collisions is calculated in the framework of a hadrochemical model. It is compared with the results of cascade and fireball model calculations and experimental data. The importance of πN and πΔ collisions in producing kaons and hyperons is pointed out.
- Published
- 1982
22. The Power of Synchronization Mechanisms
- Author
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H W. Barz
- Subjects
Hierarchy ,General Computer Science ,Computer science ,General Mathematics ,Distributed computing ,Synchronization (computer science) ,Parallelism (grammar) ,Data synchronization ,Outcome (game theory) ,Measure (mathematics) ,Clock synchronization ,Power (physics) - Abstract
A common question in parallel programming is How to implement a program efficiently for a particular synchronization problem? Here we pose a more general question: Is a certain synchronization mechanism capable of implementing efficiently a particular synchronization problem represented by a program using another synchronization mechanism? We give a definition of “implementing efficiently” which measures efficiency by the amount of parallelism of the parallel programs. If this measure is reduced by the implementation the efficiency of the implementation is inferior. It is shown that some synchronization mechanisms cannot implement programs based on another mechanism without some loss in parallelism, i.e., a reduced measure. These results imply a power hierarchy (or efficiency hierarchy) of synchronization mechanisms. A further outcome of this paper is that simple synchronization mechanisms, with only a few variables, are capable of implementing any synchronization problem implementable by more powerful me...
- Published
- 1984
23. The description of hypernuclei in the continuum shell-model
- Author
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R. Wünsch and H. W. Barz
- Subjects
Nuclear physics ,Nuclear reaction ,Physics ,Continuum (measurement) ,Quantum electrodynamics ,SHELL model ,General Physics and Astronomy - Abstract
The advantage of the continuum shell-model in describing nuclear reactions producing hypernuclei is discussed. Numerical results obtained within this model for the (K−,π−) reaction on9Be,12C,16O and40Ca are presented.
- Published
- 1982
24. On the nuclear isovector quadrupole moment
- Author
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H U Jager, H W Barz, and V V Balashov
- Subjects
Nuclear physics ,Scattering cross-section ,Physics ,Nuclear and High Energy Physics ,Isovector ,Component (thermodynamics) ,Nuclear Theory ,Nuclear magnetic moment ,Quadrupole ,General Physics and Astronomy ,Mirror nuclei ,Atomic physics ,Nuclear Experiment - Abstract
It is shown that the differential cross section of (p,n) reactions with 1 GeV protons corresponding to a Fermi-type transition between mirror nuclei is sensitive to the isovector component of the nuclear quadrupole moment because of the nuclear spin-re-orientation effect.
- Published
- 1980
25. The effect of correlations on the entropy and hadrochemical composition in heavy ion reactions
- Author
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H. W. Barz, T. S. Biró, B. Lukács, and J. Zimanyi
- Subjects
Physics ,Entropy density ,Excluded volume ,Thermodynamics ,Heavy ion ,Atomic physics ,Nuclear Experiment ,Nuclear matter - Abstract
It is shown that spatial correlations between the constituent particles of a gas lead to roughly excluded volume type corrections in the equation of state. These corrections will appreciably change the hadrochemical composition of fireballs formed in heavy ion reactions.
- Published
- 1987
26. Entropy and hadrochemical composition in heavy ion collision
- Author
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Tamás S. Biró, J. Zimányi, B. Lukács, and H. W. Barz
- Subjects
Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Meson ,Entropy production ,Hadron ,Elementary particle ,symbols.namesake ,Pion ,symbols ,Atomic physics ,van der Waals force ,Nuclear Experiment ,Boson - Abstract
The composite particle production in a heavy ion collision is calculated in the framework of a hadrochemical model. A critical comparison is performed between the produced entropy and the observables. The entropy production during the hadrochemical processes is found to be negligible.NUCLEAR REACTIONS Ne + NaF heavy ion collision, $E=0, 4\ensuremath{-}2.1$, calculated spectra $p$, $d$, ${\ensuremath{\pi}}^{+}$, van der Waals model, entropy.
- Published
- 1983
27. Spherical and linear fluid-dynamical models for relativistic central heavy ion collisions
- Author
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H. W. Barz and L. P. Csernai
- Subjects
Physics ,Nuclear and High Energy Physics ,Equation of state ,Classical mechanics ,Flow (mathematics) ,Compression (functional analysis) ,Nuclear fusion ,Heavy ion ,Nuclear matter - Abstract
Spherical hydrodynamical expansion and linear compression and expansion are calculated in viscous relativistic hydrodynamics. The break-up process subsequent to the hydrodynamical collective flow is also taken into account. The results lay the foundation of the blast-wave model and the comparison of the linear and spherical models with the experiment provides further evidence for the soft nuclear matter equation of state.
- Published
- 1980
28. Einfluß aktiver Nukleonen auf den Stripping-Prozeß mit Deuteronen
- Author
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H.-W. Barz
- Subjects
General Physics and Astronomy - Abstract
Ausgehend vom Matrixelement der Distorted Wave Born Approximation (DWBA) wird der Einflus der Austauschterme auf die Winkelverteilung der Reaktionen C13 (d, n) N11 und O17 (d, p1) O18 abgeschatzt. Dabei werden die gestorten Wellen durch ebene Wellen mit modifizierten Wellenzahlen ersetzt. Fur die Deuteronwellenfunktion werden die beiden Ansatze ν (χ) ˜ δ (χ) und ν (χ) ˜ konst. untersucht. Am Knockout-Prozes der B11 (d, p1) B10-Reaktionen zeigt sich, das der zweite Ansatz gunstiger ist. Die Rechnungen werden auf Winkel ≤ 60° beschrankt. Bei der C13 (d, n) N11-Reaktion verschieben die Austauschterme das Maximum der Winkelverteilung etwas nach kleineren Winkeln, wahrend der Wirkungsquerschnitt der Reaktion O17 (d, p1) O18 bei kleinen Winkeln deutlich angehoben wird.
- Published
- 1964
29. Extra entropy production due to nonequilibrium phase transitions in relativistic heavy ion reactions
- Author
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B. Lukács, H. W. Barz, L. P. Csernai, and Burkhard Kampfer
- Subjects
Nuclear physics ,Physics ,Nuclear and High Energy Physics ,Phase transition ,Entropy production ,High Energy Physics::Lattice ,High Energy Physics::Phenomenology ,Nuclear Theory ,Non-equilibrium thermodynamics ,High Energy Physics::Experiment ,Heavy ion ,Atomic physics ,Nuclear Experiment - Abstract
In a fluid-dynamical model, the extra entropy production which arises from a nonequilibrium phase transition from nuclear to quark-gluon matter is calculated.
- Published
- 1985
30. Shape of the E1 Strength Function in the Region of Pygmy Anomaly Due to Non Statistical Background Coupling
- Author
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L. P. Csernai and H. W. Barz
- Subjects
Physics ,Mass number ,Dipole ,Coupling (physics) ,Condensed matter physics ,Basis (linear algebra) ,Quantum electrodynamics ,Function (mathematics) ,Sum rule in quantum mechanics ,Anomaly (physics) ,Resonance (particle physics) - Abstract
Systematic deviations from the Lorentzian approximation to the E1-giant dipole resonance (GDR) shape has been observed at the low energy side of the GDR /1,2/. The strength involved amounts to a few percent of the E1 sum rule,so this phenomenon is called pygmy resonance. A remarkable regularity has been mentioned by Lane /3/: The anomaly appears in mass number regions where empty single-particle states with l=0,1 are near the threshold. Applying the 1p-1h description the 1p-1h states containing the mentioned s or p-neutron particle states (threshold states) have unperturbed energies close to the energy of the anomaly. So these states may be saved from being coupled to the GDR. Such calculations /3,4,5/ performed in the pure 1p-1h shell model provide different amounts of the strength of the pygmy resonance as a function of the used residual interaction and basis.
- Published
- 1979
31. Coulomb effects on particle spectra in relativistic nuclear collisions
- Author
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H. W. Barz, Henning Heiselberg, J.P. Bondorf, and J. J. Gaardhøje
- Subjects
Physics ,Nuclear and High Energy Physics ,Nuclear Theory ,FOS: Physical sciences ,Numerical models ,Spectral line ,Nuclear Theory (nucl-th) ,Nuclear physics ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,Coulomb ,Particle ,Coulomb effect ,Nuclear Experiment ,Nuclear theory - Abstract
Coulomb effects on $\pi^\pm$ and $K^\pm$ spectra in relativistic nuclear collisions are investigated. At collision energies around 1 GeV the ratio of $\pi^-$ to $\pi^+$ is enhanced several times at low transverse momenta but less at ultrarelativistic energies. We describe the ratios at SIS, AGS and SPS energies with simple analytic models as well as more elaborate numerical models incorporating the expansion dynamics. The Coulomb effect depends on the properties of the source after the violent collision phase and provides information on source sizes, freeze-out times, and expansion velocities. Comparison with results from HBT analyses are made. Predictions for $\pi^\pm$ and $K^\pm$ at RHIC and LHC energies are given., Comment: 22 pages including 12 figures. Added figure and revisions
32. Freeze-out time in ultrarelativistic heavy ion collisions from Coulomb effects in transverse pion spectra
- Author
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J.P. Bondorf, Henning Heiselberg, J. J. Gaardhøje, and H. W. Barz
- Subjects
Physics ,Nuclear and High Energy Physics ,Field (physics) ,Nuclear Theory ,Charge density ,FOS: Physical sciences ,Charge (physics) ,Spectral line ,Nuclear physics ,Nuclear Theory (nucl-th) ,Transverse plane ,High Energy Physics - Phenomenology ,Pion ,High Energy Physics - Phenomenology (hep-ph) ,TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,Coulomb ,Rapidity ,Atomic physics ,Nuclear Experiment - Abstract
The influence of the nuclear Coulomb field on transverse spectra of $\pi^+$ and $\pi^-$ measured in $Pb+Pb$ reactions at 158 A GeV has been investigated. Pion trajectories are calculated in the field of an expanding fireball. The observed enhancement of the $\pi^-/\pi^+$ ratio at small momenta depends on the temperature and transverse expansion velocity of the source, the rapidity distribution of the net positive charge, and mainly the time of the freeze-out., Comment: 11 pages including 2 figures
33. Subthreshold phi meson production in heavy-ion collisions
- Author
-
M. Zétényi, Gy. Wolf, Burkhard Kampfer, and H. W. Barz
- Subjects
Physics ,Nuclear and High Energy Physics ,Meson production ,Nuclear Theory ,Subthreshold conduction ,FOS: Physical sciences ,heavy-ion collisions ,Phi meson ,Nuclear physics ,Nuclear Theory (nucl-th) ,subthreshold production ,phi-meson ,Elementary reaction ,Heavy ion ,Production (computer science) ,Nuclear Experiment ,phi-meson production ,Nuclear theory - Abstract
Within a transport code of BUU type the production of phi-mesons in the reactions Ni+Ni at 1.93 AGeV and Ru+Ru at 1.69 AGeV is studied. New elementary reaction channels rho+N(Delta) to phi+N and pi+N(1520) to phi+N are included. In spite of a substantial increase of the \phi multiplicities by these channels the results stay below the tentative numbers extracted from experimental data., Comment: 17 pages(LaTeX), two new figures added
34. Measuring Acceptance Levels of Webcast-Based E-Learning to Improve Remote Learning Quality Using Technology Acceptance Model.
- Author
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Satmintareja, Syafei, Wahyul Amien, and Yulianto, Aton
- Subjects
TECHNOLOGY Acceptance Model ,DISTANCE education ,DIGITAL learning ,COVID-19 pandemic ,STRUCTURAL equation modeling ,EDUCATIONAL technology ,MOBILE learning - Abstract
This study aims to improve the quality of distance learning by developing webcast-based e-learning media and integrating it into an e-learning platform for functional job training purposes at the National Research and Innovation Agency, Indonesia. This study uses a Technology Acceptance Model (TAM) to assess and predict user perceptions of information systems using webcast platforms as an alternative to conventional applications. The research method was an online survey using Google Forms. Data collected from 136 respondents involved in practical job training were analyzed using structural equation modeling to test the technology acceptance model. The results showed that the proposed model effectively explained the variables associated with the adoption of web-based e-learning during the COVID-19 pandemic in Indonesia for participants engaged in functional job training. These findings suggest that users' perceptions of ease of use, usefulness, benefits, attitudes, intentions, and webcast usage significantly contribute to the acceptance and use of a more effective and efficient webcast-based e-learning platform. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
35. Expanding fireballs and the account of the Pauli quenching for the deuteron production
- Author
-
H. Schulz, Tamás S. Biró, M. Schmidt, L. Münchow, H. Iwe, Gerd Röpke, H. W. Barz, and J. Zimányi
- Subjects
Nuclear physics ,Physics ,Quenching ,Nuclear and High Energy Physics ,symbols.namesake ,Pauli exclusion principle ,Deuterium ,Astrophysics::High Energy Astrophysical Phenomena ,Nuclear Theory ,symbols ,Nuclear fusion ,Nuclear Experiment - Abstract
Describing the expanding fireballs in a relativistic gas dynamical approach the formation of deuterons is calculated under consideration of inmedium corrections. The theoretical results are in good agreement with experimental data.
- Published
- 1982
36. Enhancing Bandwidth Utilization of IP Telephony Over IPv6 Networks.
- Author
-
Al-Mimi, Hani, Alrabanah, Yousef, Abualhaj, Mosleh M., and Al-khatib, Sumaya N.
- Subjects
COVID-19 pandemic ,BANDWIDTHS ,INTERNET telephony ,REAL-time transport protocol ,MULTIPLEXING - Abstract
The demand for the telecommunication services, such as IP telephony, has increased dramatically during the COVID-19 pandemic lockdown. IP telephony should be enhanced to provide the expected quality. One of the issues that should be investigated in IP telephony is bandwidth utilization. IP telephony produces very small speech samples attached to a large packet header. The header of the IP telephony consumes a considerable share of the bandwidth allotted to the IP telephony. This wastes the network's bandwidth and influences the IP telephony quality. This paper proposes a mechanism (called Smallerize) that reduces the bandwidth consumed by both the speech sample and the header. This is achieved by assembling numerous IP telephony packets in one header and use the header's fields to carry the speech sample. Several metrics have been used to measure the achievement Smallerize mechanism. The number of calls has been increased by 245.1% compared to the typical mechanism. The bandwidth saving has also reached 68% with the G.28 codec. Therefore, Smallerize is a possible mechanism to enhance bandwidth utilization of the IP telephony. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
37. Transport model analysis of the pion interferometry in Au+Au collisions at Ebeam=1.23 GeV/nucleon.
- Author
-
Li, Pengcheng, Wang, Yongjia, Li, Qingfeng, and Zhang, Hongfei
- Abstract
Within the framework of the Ultra-relativistic Quantum Molecular Dynamics model, the effects of resonance decay widths, in-medium nucleon-nucleon (in)elastic cross sections, and potentials on the pion Hanbury-Brown-Twiss (HBT) intensity interferometry in central Au+Au collisions at E
beam = 1.23 GeV/nucleon are investigated. The results show that the pion emission source is visibly influenced by the Δ particles with small invariant masses, i.e., with long resonance lifetimes. Furthermore, the pion HBT radii are found to be insensitive to the nucleon-nucleon (in)elastic cross sections, while the measured rapidity distributions of the charged pions are sensitive to the nucleon-nucleon (in)elastic cross sections and can be much better reproduced by considering a reduction factor on the nucleon-nucleon inelastic cross sections. The observed charge-sign difference of the source radii, especially in outward and sideward directions, can be qualitatively explained by simulations with the potential contributions, especially including the Coulomb potential of mesons. The present work demonstrates that the potential updates play important roles in describing the measured HBT radii and duration-time-related radii ratios when understanding the dynamics in relativistic heavy-ion collisions at ∼GeV beam energies. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
38. Transport theories for heavy-ion collisions in the 1 A GeV regime.
- Author
-
E E Kolomeitsev, C Hartnack, H W Barz, M Bleicher, E Bratkovskaya, W Cassing, L W Chen, P Danielewicz, C Fuchs, T Gaitanos, C M Ko, A Larionov, M Reiter, and Gy Wolf and J Aichelin
- Published
- 2005
39. Nonequilibrium Hydrodynamic Approach to Describing the Emission of High-Energy Secondary Particles in Intermediate-Energy Heavy-Ion Collisions.
- Author
-
D'yachenko, A. T. and Mitropolsky, I. A.
- Subjects
HEAVY-ion atom collisions ,QUANTUM theory ,HEAVY ion collisions ,PARTICLES (Nuclear physics) ,MOLECULAR dynamics ,PIONS - Abstract
With the aim of developing the hydrodynamic approach to describing collisions of intermediate-energy heavy ions, it is proposed to solve simultaneously the equations of hydrodynamics and the kinetic equation. This makes it possible to include the nonequilibrium component in the present analysis and to describe successfully experimental data obtained at Institute for Theoretical and Experimental Physics (ITEP, Moscow) for the double-differential cross sections of the emission of cumulative protons, pions, and photons in collisions carbon nuclei with a beryllium target in the energy range between 2.0 and 3.2 GeV per nucleon. The correction for the microcanonical distribution and the contribution of the fragmentation process to the proton yield are taken into account in describing these spectra. The resulting description of these experimental data turns out to be better than the descriptions based on cascade models and models of quantum molecular dynamics. A comparison with other reactions and approaches is performed. It turns out that effects of short-range correlations are included in the proposed approach, since it provides a successful description of experimental hard-photon spectra, which are described within molecular dynamics only upon adding a high-momentum component. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
40. Impact of the Coulomb field on charged-pion spectra in few-GeV heavy-ion collisions.
- Author
-
Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Ciepał, I., Deveaux, C., Dreyer, J., Epple, E., Fabbietti, L., Fateev, O., Filip, P., and Fonte, P.
- Subjects
PROTON-proton interactions ,COLLISIONS (Nuclear physics) ,COULOMB potential ,FAIR value ,POTENTIAL energy ,BARYONS ,MOMENTUM transfer - Abstract
In nuclear collisions the incident protons generate a Coulomb field which acts on produced charged particles. The impact of these interactions on charged-pion transverse-mass and rapidity spectra, as well as on pion–pion momentum correlations is investigated in Au + Au collisions at s NN = 2.4 GeV. We show that the low- m t region ( m t < 0.2 GeV/ c 2 ) can be well described with a Coulomb-modified Boltzmann distribution that also takes changes of the Coulomb field during the expansion of the fireball into account. The observed centrality dependence of the fitted mean Coulomb potential energy deviates strongly from a A part 2 / 3 scaling, indicating that, next to the fireball, the non-interacting charged spectators have to be taken into account. For the most central collisions, the Coulomb modifications of the HBT source radii are found to be consistent with the potential extracted from the single-pion transverse-mass distributions. This finding suggests that the region of homogeneity obtained from two-pion correlations coincides with the region in which the pions freeze-out. Using the inferred mean-square radius of the charge distribution at freeze-out, we have deduced a baryon density, in fair agreement with values obtained from statistical hadronization model fits to the particle yields. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
41. Understanding the Origin of Matter: Perspectives in Quantum Chromodynamics.
- Author
-
Blaschke, David, Redlich, Krzysztof, Sasaki, Chihiro, and Turko, Ludwik
- Published
- 2022
- Full Text
- View/download PDF
42. FRAGMENT-FRAGMENT CORRELATIONS AND FRAGMENT FLOW IN HEAVY ION COLLISIONS DESCRIBED WITHIN MOLECULAR DYNAMICS.
- Author
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BARZ, H. W., BONDORF, J. P., IDIER, D., and MISHUSTIN, I. N.
- Subjects
HEAVY ion collisions ,MOLECULAR dynamics ,GOLD ,PARTICLES (Nuclear physics) ,FERMI energy - Published
- 1996
43. Systematic study of multifragmentation in Au-Au collisions.
- Author
-
Goyal, Supriya
- Subjects
QUANTUM theory ,MOLECULAR dynamics ,PHASE transitions ,COLLISION induced dissociation ,PARTICLES (Nuclear physics) - Abstract
We performed a systematic study of the formation of fragments with different mass ranges in
197 Au+197 Au collisions at incident energies between 20-1000 MeV/nucleon and at impact parameter between b = b/bmax = 0-0.98. In our present study, the dependence of fragment production on incident beam energy and geometry of the reaction is seen. Our results clearly indicate that the Quantum Molecular Dynamics simulations of197 Au+197 Au predict different behavior for different mass ranges than for Intermediate Mass Fragments (IMF's) with a change in incident energy and impact parameter. All charge yields (3≤Zfrag ≤12) can be parameterized by a power law (Zfrag −τ ) and no signal of liquid-gas phase transition is seen as no unique dependence of τ on impact parameter is seen. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
44. The effect of correlations on the entropy and hadrochemical composition in heavy ion reactions.
- Author
-
Barz, H., Biró, T., Lukács, B., and Zimányi, J.
- Abstract
It is shown that spatial correlations between the constituent particles of a gas lead to roughly excluded volume type corrections in the equation of state. These corrections will appreciably change the hadrochemical composition of fireballs formed in heavy ion reactions. [ABSTRACT FROM AUTHOR]
- Published
- 1987
- Full Text
- View/download PDF
45. Charged-pion production in Au+Au collisions at sNN=2.4GeV.
- Author
-
Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Ciepał, I., Deveaux, C., Dreyer, J., Epple, E., Fabbietti, L., Fateev, O., Filip, P., and Fonte, P.
- Abstract
We present high-statistic data on charged-pion emission from Au + Au collisions at s NN = 2.4 GeV (corresponding to E beam = 1.23 A GeV ) in four centrality classes in the range 0–40% of the most central collisions. The data are analyzed as a function of transverse momentum, transverse mass, rapidity, and polar angle. Pion multiplicity per participating nucleon decreases moderately with increasing centrality. The polar angular distributions are found to be non-isotropic even for the most central event class. Our results on pion multiplicity fit well into the general trend of the available world data, but undershoot by 2.5 σ data from the FOPI experiment measured at slightly lower beam energy. We compare our data to state-of-the-art transport model calculations (PHSD, IQMD, PHQMD, GiBUU and SMASH) and find substantial differences between the measurement and the results of these calculations. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
46. Progress of quantum molecular dynamics model and its applications in heavy ion collisions.
- Author
-
Zhang, Ying-Xun, Wang, Ning, Li, Qing-Feng, Ou, Li, Tian, Jun-Long, Liu, Min, Zhao, Kai, Wu, Xi-Zhen, and Li, Zhu-Xia
- Abstract
In this review article, we first briefly introduce the transport theory and quantum molecular dynamics model applied in the study of the heavy ion collisions from low to intermediate energies. The developments of improved quantum molecular dynamics model (ImQMD) and ultra-relativistic quantum molecular dynamics model (UrQMD), are reviewed. The reaction mechanism and phenomena related to the fusion, multinucleon transfer, fragmentation, collective flow and particle production are reviewed and discussed within the framework of the two models. The constraints on the isospin asymmetric nuclear equation of state and in-medium nucleon-nucleon cross sections by comparing the heavy ion collision data with transport models calculations in last decades are also discussed, and the uncertainties of these constraints are analyzed as well. Finally, we discuss the future direction of the development of the transport models for improving the understanding of the reaction mechanism, the descriptions of various observables, the constraint on the nuclear equation of state, as well as for the constraint on in-medium nucleon-nucleon cross sections. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
47. Strange particle effective temperatures in relativistic nuclear collisions.
- Author
-
Ristea, Oana, Ristea, Catalin, and Jipa, Alexandru
- Subjects
COLLISIONS (Nuclear physics) ,STRANGE particles ,RELATIVISTIC Heavy Ion Collider ,HEAVY ion collisions - Abstract
The energy dependence of the effective temperatures of charged kaons, ϕ and Ω produced in Au + Au collisions at the Relativistic Heavy Ion Collider (RHIC) Beam Energy Scan (BES) energies are presented. At energies around s N N ∼ 8 GeV, there is a sudden change in the energy dependence of K ± and ϕ effective temperatures, while at higher energies a slower, continuous rise up to s N N = 2. 7 6 TeV is observed. This behavior is similar with previous SPS results and could indicate the onset of deconfinement in this energy range. The Ω effective temperatures increase with energy and no plateau-like behavior is evidenced by the data. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
48. Subthreshold Ξ- production in proton-nucleus collisions in a BUU model.
- Author
-
Zétényi, Miklós and Wolf, György
- Subjects
HEAVY ion collisions ,BARYONS ,HYPERONS ,MULTIPLICITY of nuclear particles ,NUCLEAR cross sections - Abstract
We study the production of the doubly strange Ξ baryon in subthreshold p + A collisions using a BUU type transport model. We propose a new mechanism for Ξ creation in a two-step process via hyperon-nucleon collisions. We study the influence of the anisotropy of hyperon production in N + N collisions on the Ξ multiplicity. Applying reasonable assumptions on the unknown elementary cross sections, we are able to reconstruct the Ξ yield observed by the HADES collaboration (GSI, Darmstadt) in subthreshold p+Nb collisions. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
49. Critical evolution of hot van der Waals droplets.
- Author
-
Kondratyev, V. N. and Lutz, H. O.
- Subjects
QUASIMOLECULES ,MOLECULAR dynamics - Abstract
Investigates the dynamical evolution and fragmentation of a hot finite van der Waals system in a classical molecular dynamics approach. Regimes in the evolution of a hot many-body system; Statistical properties of inclusive mass distributions; Correlation properties of mass distributions.
- Published
- 1997
- Full Text
- View/download PDF
50. Threshold Collision Energy of the QCD Phase Diagram Tricritical Endpoint.
- Author
-
Bugaev, K. A., Emaus, R., Sagun, V. V., Ivanytskyi, A. I., Bravina, L. V., Blaschke, D. B., Nikonov, E. G., Taranenko, A. V., Zabrodin, E. E., and Zinovjev, G. M.
- Abstract
Using the most advanced formulation of the hadron resonance gas model we analyze the two sets of irregularities found at chemical freeze-out of central nuclear-nuclear collisions at the center of mass energies 3.8-4.9 GeV and 7.6-9.2 GeV. In addition to previously reported irregularities at the collision energies 4.9 and 9.2 GeV we found sharp peaks of baryonic charge density. Also we analyze the collision energy dependence of the modified Wroblewski factor and the strangeness suppression factor. Based on the thermostatic properties of the mixed phase of a 1st order phase transition and the ones of the Hagedorn mass spectrum we explain, respectively, the reason of observed chemical equilibration of strangeness at the collision energy 4.9 GeV and above 8.7 GeV. It is argued that the both sets of irregularities possibly evidence for two phase transitions, namely, the 1st order transition at lower energy range and the 2nd order transition at higher one. In combination with a recent analysis of the light nuclei number fluctuations we conclude that the center of mass collision energy range 8.8-9.2 GeV may be in the nearest vicinity of the QCD tricritical endpoint. The properties of the phase existing between two phase transitions are revealed and discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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