共查询到20条相似文献,搜索用时 15 毫秒
1.
A. Hombach W. Cassing U. Mosel 《The European Physical Journal A - Hadrons and Nuclei》1999,5(1):77-84
We study the mixing and the kinetic equilibration of projectile and target nucleons in relativistic heavy-ion collisions
in the energy regime between 150 AMeV and 2 AGeV in a coupled-channel BUU (CBUU) approach. We find that equilibrium in the
projectile-target degrees of freedom is in general not reached even for large systems at low energy where elastic nucleon-nucleon
collisions dominate. Inelastic nucleon excitations are more favorable for equilibration and their relative abundance increases
both with energy and mass. Experimentally, the projectile/target admixture can be determined by measuring the degree of isospin
equilibration in isospin asymmetric nuclear collisions. For one of the most promising systems currently under investigation,
96
44Ru +96
40Zr, we investigate the influence of the equation of state and the inelastic in-medium cross section.
Received: 23 September 1998 / Revised version: 3 December 1998 相似文献
2.
3.
Charged particle pseudorapidity distributions have been measured in Au+ Au collisions using the BRAHMS detector at RHIC. The
results are presented as a function of the collision centrality and the center of mass energy. They are compared to the predictions
of different parton scattering models and the important role of hard scattering processes at RHIC energies is discussed. Keywords.
Relativistic heavy-ion collisions; charged hadron production; pseudorapidity distributions; centrality dependence; hard scattering
processes. 相似文献
4.
In these proceedings, we briefly review how jets can be reconstructed in heavy-ion collisions. The main point we address is the subtraction of the large contamination from the underlying event background. We first present the main ingredients needed to define the jets and perform the background subtraction and then discuss the efficiency of the subtraction for different jet algorithms and background-estimation methods. 相似文献
5.
R. S. Bhalerao 《Pramana》2003,61(5):1021-1025
A brief introduction is given to the field of collective flow, currently being investigated experimentally at the Relativistic
Heavy-Ion Collider, Brookhaven National Laboratory. It is followed by an outline of the work that I have been doing in this
field, in collaboration with Nicolas Borghini and Jean-Yves Ollitrault. 相似文献
6.
By means of the AKK08 fragmentation function, the net-proton transverse momentum (pT) spectra in A+A collisions are studied with two phenomenological models based on the Color Glass Condensate formalism. After a x2 analysis of the experimental data from BRAHMS, the normalization constant C is extracted at RHIC energies of √SNN =62.4 and 200 GeV, and the theoretical results of the net-proton pT spectra at selected rapidities are also given. It is shown that the theoretical results are in good agreement with the experimental data. Finally, assuming the constant C should have an exponent dependence of √SNN, we also predict the theoretical results of net-proton pT spectra at LHC energies of √SNN = 2.76, 3.94, and 5.52 TeV. 相似文献
7.
Charged-particle multiplicity at mid-rapidity in Au-Au collisions at relativistic heavy-ion collider
The particle density at mid-rapidity is an essential global variable for the characterization of nuclear collisions at ultra-relativistic
energies. It provides information about the initial conditions and energy density reached in these collisions. The pseudorapidity
densities of charged particles at mid-rapidity in AuAu collisions at √s
NN = 130 and 200 GeV at RHIC (relativistic heavy ion collider) have been measured with the PHENIX detector. The measurements
were performed using sets of wire-chambers with pad readout in the two central PHENIX tracking arms. Each arm covers one quarter
of the azimuth in the pseudorapidity interval |η| < 035. Data is presented and compared with results from proton-proton collisions
and nucleus-nucleus collisions at lower energies. Extrapolations to LHC energies are discussed. 相似文献
8.
By means of the AKK08 fragmentation function, the net-proton transverse momentum (pT) spectra in A+A collisions are studied with two phenomenological models based on the Color Glass Condensate formalism. After a χ2 analysis of the experimental data from BRAHMS, the normalization constant C is extracted at RHIC energies of √sNN=62.4 and 200 GeV, and the theoretical results of the net-proton pT spectra at selected rapidities are also given. It is shown that the theoretical results are in good agreement with the experimental data. Finally, assuming the constant C should have an exponent dependence of √sNN, we also predict the theoretical results of net-proton pT spectra at LHC energies of √sNN=2.76, 3.94, and 5.52 TeV. 相似文献
9.
Shi Shusu Du Jiaxin Liu Lianshou 《The European Physical Journal A - Hadrons and Nuclei》2007,33(1):53-56
The inversion-asymmetry of the particle emission source in relativistic heavy-ion collision under the Bertsch-Pratt convention
is discussed and explicitly exhibited by a Monte Carlo model. The Gaussian source function popularly used in the HBT analysis
of relativistic heavy-ion collisions is invalid in this case. An inversion-asymmetric source function is suggested. A method
for extracting the inversion-asymmetry degree of the source together with the source size from experimental data is proposed. 相似文献
10.
11.
给出了两种统计系综下相对论重离子碰撞中部分相干源的相干因子的表达式 相似文献
12.
Mariusz Michalec Wojciech Florkowski Wojciech Broniowski 《Physics letters. [Part B]》2001,520(3-4):213-216
By means of a simple rescaling, modifications of hadron masses and widths are incorporated into the thermal analysis of particle ratios in ultrarelativistic heavy-ion collisions. We find that moderate, up to 20%, changes of hadron masses do not spoil the quality of the fits, which remain as good as those obtained without modifications. Larger changes are not likely. The fits with the modified masses yield modified values of the optimal temperature and baryon chemical potential. In particular, with decreasing masses of all hadrons (except for pseudo-Goldstone bosons) the fitted values of the temperature and the baryon chemical potential are lowered, with the change approximately proportional to the scaling of masses. In addition, we find that the broadening of the hadron widths by less than a factor of two practically does not affect the fits. 相似文献
13.
The transverse mass spectra of protons, pions, kaons, Lambda and Antilambda produced in cen- tral nucleus-nucleus collisions at high energies are described by using one-temperature and two-temperature emission pictures. The calculated results are compared and found to be in good agreement with the experimen- tal data of the E895, E866 and E917 Collaborations measured in central Au-Au collisions at the Alternating Gradient Synchrotron (AGS) energies and the NA49 Collaboration measured in central Pb-Pb collisions at the Super Proton Synchrotron (SPS) energies. It is demonstrated that the transverse mass distributions of protons, kaons, Lambda and Antilambda, except for Lambda hyperons produced in central Pb-Pb collisions at 158 A GeV, can be described by using the one-temperature emission picture, and for pions, we need to use the two-temperature emission picture. 相似文献
14.
We investigate the lepton pair production with the Drell-Yan process in relativistic heavy ion collisions by computing the double differential cross section dσ/dM2dy and dσ/dM2dxF at the next-to-leading order in p+Au and Au+Au collisions with √sNN =200 GeV at RHIC. The resulting nuclear modification factors RpAu and RAuAu show strong sensitivity to the cold nuclear matter (CNM) effects and could probe the CNM effects at a very wide region of the longitudinal momentum fraction x. The variation of R with the invariant mass M, the rapidity y and the Feynman variable xF is shown and we find that the nuclear modification factor for the double differential cross section could be smaller than 0.4 in some kinematic regions of high-energy nucleus-nucleus reactions at RHIC. 相似文献
15.
We study soft hadron production in relativistic heavy-ion collisions in a wide range of reaction energy, 4.8 GeV <
< 200 GeV, and make predictions about yields of particles using the statistical hadronization model. In fits to experimental
data, we obtain both the statistical parameters as well as physical properties of the hadron source. We identify the properties
of the fireball at the critical energy threshold, 6.26 GeV <
< 7.61 GeV, marking for higher energies the hadronization of an entropy-rich phase. In terms of the chemical composition,
one sees a phase which at low energy is chemically under-saturated, and which turns into a chemically over-saturated state
persisting up to the maximum accessible energy. Assuming that there is no change in physical mechanisms in the energy range
15 >
≥200 GeV, we use continuity of particle yields and statistical parameters to predict the hadron production at
= 62.4 GeV, and obtain total yields of hadrons at
= 130 GeV. We consider, in depth, the pattern we uncover within the hadronization condition, and discuss possible mechanisms
associated with the identified rapid change in system properties at
. We propose that the chemically over-saturated 2 + 1 flavor hadron matter system undergoes a 1st-order phase transition. 相似文献
16.
The transverse mass spectra of protons, pions, kaons, Lambda and Antilambda produced in central nucleus-nucleus collisions at high energies are described by using one-temperature and two-temperature emission pictures. The calculated results are compared and found to be in good agreement with the experimental data of the E895, E866 and E917 Collaborations measured in central Au-Au collisions at the Alternating Gradient Synchrotron (AGS) energies and the NA49 Collaboration measured in central Pb-Pb collisions at the Super Proton Synchrotron (SPS) energies. It is demonstrated that the transverse mass distributions of protons, kaons, Lambda and Antilambda, except for Lambda hyperons produced in central Pb-Pb collisions at 158 A GeV, can be described by using the one-temperature emission picture, and for pions, we need to use the two-temperature emission picture. 相似文献
17.
Identified π±,K
±, p and -p transverse momentum spectra at mid-rapidity in √sNN = 130 GeV Au-Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average
transverse momenta increase with the number of participating nucleonsN
part similarly for all particle species. The multiplicity densities scale faster thanN
part. TheK
± andp
±yields per participant increase faster than the π± yields. We combine the PHENIX neutral and charged pion measurement and find that in central collisions forp
T >-2 GeV/c,-p andp yields are comparable to or even exceed the pion yields. 相似文献
18.
We present Monte-Carlo simulations for heavy-ion collisions combining PYTHIA and the McGill-AMY formalism to describe the evolution of hard partons in a soft background, modelled using hydrodynamic simulations. MARTINI generates full event configurations in the high pT region that take into account thermal QCD and QED effects as well as effects of the evolving medium. This way it is possible to perform detailed quantitative comparisons with experimental observables. 相似文献
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20.
Rajarshi Ray 《Pramana》2003,60(5):1005-1009
Under certain situations, partons formed in heavy-ion collision experiments may expand out forming a shell-like structure.
The partons in the outer shell subsequently hadronize, leaving a bubble of pure deconfined vacuum for a first-order quark-hadron
phase transition. The bubble collapses and may eventually decay into particles which may thermalize to temperatures exceeding
the electroweak transition temperature (100 GeV) at LHC. This will lead to the possibility of unsuppressed electroweak baryon
number violating processes. 相似文献