The relativistic mean-field approach was implemented in the Lanzhou quantum molecular dynamics transport model(LQMD.RMF). Using the LQMD.RMF, the properties of collective flow and pion production were investigated sys...The relativistic mean-field approach was implemented in the Lanzhou quantum molecular dynamics transport model(LQMD.RMF). Using the LQMD.RMF, the properties of collective flow and pion production were investigated systematically for nuclear reactions with various isospin asymmetries. The directed and elliptic flows of the LQMD.RMF are able to describe the experimental data of STAR Collaboration. The directed flow difference between free neutrons and protons was associated with the stiffness of the symmetry energy, that is, a softer symmetry energy led to a larger flow difference. For various collision energies, the ratio between the π^(-) and π^(+) yields increased with a decrease in the slope parameter of the symmetry energy. When the collision energy was 270 MeV/nucleon, the single ratio of the pion transverse momentum spectra also increased with decreasing slope parameter of the symmetry energy in both nearly symmetric and neutron-rich systems.However, it is difficult to constrain the stiffness of the symmetry energy with the double ratio because of the lack of threshold energy correction on the pion production.展开更多
In this study, the rapidity distribution, collective flows, and nuclear stopping power in ^(197)Au+^(197)Au collisions at intermediate energies were investigated using the ultrarelativistic quantum molecular dynamics(...In this study, the rapidity distribution, collective flows, and nuclear stopping power in ^(197)Au+^(197)Au collisions at intermediate energies were investigated using the ultrarelativistic quantum molecular dynamics(UrQMD) model with GEMINI++ code. The UrQMD model was adopted to simulate the dynamic evolution of heavy-ion collisions, whereas the GEMINI++ code was used to simulate the decay of primary fragments produced by UrQMD. The calculated results were compared with the INDRA and FOPI experimental data. It was found that the rapidity distribution, collective flows, and nuclear stopping power were affected to a certain extent by the decay of primary fragments, especially at lower beam energies. Furthermore, the experimental data of the collective flows and nuclear stopping power at the investigated beam energies were better reproduced when the sequential decay effect was included.展开更多
The main purpose of the present work is to discuss whether or not the collective flows in heavy-ion collision at the Fermi energy can be taken as a tool to investigate the cluster configuration in light nuclei. In pra...The main purpose of the present work is to discuss whether or not the collective flows in heavy-ion collision at the Fermi energy can be taken as a tool to investigate the cluster configuration in light nuclei. In practice, within an extended quantum molecular dynamics model, four a-clustering (linear chain, kite, square and tetrahedron) configurations of 16O are employed in the initialization, 16O+16O around the Fermi energy (40-60 MeV/nucleon) with impact parameter 1-3fro are simulated, and the directed and elliptic flows are analyzed. It is found that collective flows are influenced by the different a-clustering configurations, and the directed flow of free protons is more sensitive to the initial cluster configuration than the elliptic flow. Nuclear reaction at the Fermi energy can be taken as a useful way to study cluster configuration in light nuclei.展开更多
Within the framework of a semiclassical Boltzmann-Uehling-Uhlenbeck (BUU) transport model, the high mo- mentum tail (HMT) effects of nucleon momentum distribution in the nucleus on the nucleon collective flows are...Within the framework of a semiclassical Boltzmann-Uehling-Uhlenbeck (BUU) transport model, the high mo- mentum tail (HMT) effects of nucleon momentum distribution in the nucleus on the nucleon collective flows are studied in semieentral Au+Au collisions. The HMT due to the isospin-dependent short-range correlations causes a smaller value of the collective flows. We find that the HMT effects on the nucleon collective flows are remarkable at beam energy of 300 MeV/nucleon and become weak as the incident beam energy increases. The results indicate that for the collective flow studies at intermediate energies, the HMT of nucleon momentum distribution in nucleus should be taken into account in transport models.展开更多
Within the isospin-dependent quantum molecular dynamics model, we investigate the nuclear collective flows produced in semi-central 197 Au+197 Au collisions at intermediate energies. The neutron proton differential f...Within the isospin-dependent quantum molecular dynamics model, we investigate the nuclear collective flows produced in semi-central 197 Au+197 Au collisions at intermediate energies. The neutron proton differential flows and difference of neutron proton collective flows are sensitive to the momentum-dependent symmetry potential. This sensitivity is less affected by both the isoscalar part of nuclear equation of state and in-medium nucleon- nucleon cross sections. Moreover, this sensitivity becomes pronounced with increasing the rapidity cut.展开更多
The directed and elliptic flow of positively charged kaons produced in 28^58Ni+28^58Ni reactions at incident kinetic energy 1.91 AGe V are studied within the covariant kaon dynamics and compared to new data. We obser...The directed and elliptic flow of positively charged kaons produced in 28^58Ni+28^58Ni reactions at incident kinetic energy 1.91 AGe V are studied within the covariant kaon dynamics and compared to new data. We observe that the influence of the Lorentz force on the directed and differential directed flow of K+mesons is obvious. Our calculated results indicate that it is necessary for the Lorentz force to be included in the kaon dynamics in order to reasonably describe experimental data.展开更多
In this study,we reconstruct theγ-photon energy spectrum,which is in good agreement with the experimental data of ^(86)Kr+^(12)C at E/A=44 Me V within the framework of the modified EQMD model.The directed and ellipti...In this study,we reconstruct theγ-photon energy spectrum,which is in good agreement with the experimental data of ^(86)Kr+^(12)C at E/A=44 Me V within the framework of the modified EQMD model.The directed and elliptic flows of free protons and direct photons were investigated by considering theα-clustering structure of ^(12)C.Compared with free protons,direct photon flows provide clearer information about the early stage of a nuclear reaction.The difference in the collective flows between different configurations of ^(12)C is observed in this study.This indicates that the collective flows of direct photons are sensitive to the initial configuration.Therefore,theγbremsstrahlung process might be taken as an alternative probe to investigate theα-clustering structure in a light nucleus from heavy-ion collisions within the Fermienergy region.展开更多
By implementing an additional heavy quark-antiquark pair production trigger in a multiphase transport(AMPT)model,we study the effect on anisotropy flows of identified particles with a focus on charged particles and qu...By implementing an additional heavy quark-antiquark pair production trigger in a multiphase transport(AMPT)model,we study the effect on anisotropy flows of identified particles with a focus on charged particles and quarkonium(J/ΨandΥ).A systematic increase in the collision rate for active partons in the AMPT model with such an implementation has been observed.It leads to a slight increase of identified particles anisotropy flows as a function of transverse momentum(pT)and rapidity,and gives a better description of the experimental data of elliptic flow toward larger pT.Our approach provides an efficient way to study the heavy quark dynamics in the AMPT model at LHC energies.展开更多
Collective flow is a powerful tool used to analyze the properties of a medium created during high-energy nuclear collisions.Here,we report a systematic study of the first two Fourier coefficients v_(1)and v_(2)of the ...Collective flow is a powerful tool used to analyze the properties of a medium created during high-energy nuclear collisions.Here,we report a systematic study of the first two Fourier coefficients v_(1)and v_(2)of the proton andπ^(+)from Au+Au collisions in the energy range√sNN=2.11-4.9 GeV within the framework of a hadronic transport model(UrQMD).Recent results from the STAR experiment were used to test the model calculations.A meanfield mode with strong repulsive interaction is needed to reproduce the 10-40%data at 3 GeV.This implies that hadronic interactions play an important role in the collective flow development in the high baryon density region.The mean values of the freeze-out time for protons andπ^(+)are shifted earlier owing to the additional repulsive interactions.We predict the energy dependence of the mean values of the transverse momentum<pT>,v_(1),and v_(2)for both protons andπ^(+)from the Au+Au collisions.展开更多
The Cooling Storage Ring external-target experiment(CEE)spectrometer is used to study the nuclear matter created in heavy-ion collisions at√sNN=2.1-2.4 GeV with the aim to reveal the quantum chromodynamics phase stru...The Cooling Storage Ring external-target experiment(CEE)spectrometer is used to study the nuclear matter created in heavy-ion collisions at√sNN=2.1-2.4 GeV with the aim to reveal the quantum chromodynamics phase structure in the high-baryon-density region.Collective flow is considered an effective probe for evaluating the properties of media during high-energy nuclear collisions.One of the main functions of the zero-degree calorimeter(ZDC),a subdetector system in the CEE,is to determine the reaction plane in heavy-ion collisions.This step is crucial for measuring the collective flow and other reaction-plane-related analyses.In this paper,we illustrate the procedures for event plane determination using the ZDC.Finally,isospin-dependent quantum molecular dynamics model-based predictions of the rapidity dependence of the directed and elliptical flows for p,d,t,3He,and 4He,produced in 2.1 GeV U+U collisions,are presented.展开更多
In this review article,we first briefty 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 improv...In this review article,we first briefty 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 transrer,fragmentation,collective flow and particle production are reviewed and discussed within the framework of the two models.The constraints on the isospin asymmetric muclear 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.展开更多
Taking the conservation of baryon number into account in a non-uniform flow model, the rapidity distribution of the net protons at the LHC is predicted. The energy dependence of the rapidity distribution, baryon stopp...Taking the conservation of baryon number into account in a non-uniform flow model, the rapidity distribution of the net protons at the LHC is predicted. The energy dependence of the rapidity distribution, baryon stopping and collective flow from BNL/AGS to CERN/LHC are systematically investigated.展开更多
The centrality dependence of transverse momentum spectra for identified hadrons at midrapidityin Au+Au collisions at √sNN=200GeV is systematically studied in a quark combination model. The PTspectra of π^±, K^...The centrality dependence of transverse momentum spectra for identified hadrons at midrapidityin Au+Au collisions at √sNN=200GeV is systematically studied in a quark combination model. The PTspectra of π^±, K^±, p(p) and A(A) in different centrality bins and the nuclear modification factors (Rcp) forthese hadrons are calculated. The centrality dependence of the average collective transverse velocity (β (r)) for the hot and dense quark matter is obtained in Au+Au collisions, and it is applied to a relative smallerCu+Cu collision system. The centrality dependence of PT spectra and the Rcp for π^0, Ks^0 and A in Cu-bCucollisions at √sNN = 200 GeV are well described. The results show that (β (r)〉is only a function of the numberof participants Npart and it is independent of the collision system.展开更多
It is demonstrated that with Heinz's collective flow model charged particle distributions at AGS and lower SPS energies (less than 20 GeV/n) , can successfully be analyzed, but that the model fails for the RHIC dat...It is demonstrated that with Heinz's collective flow model charged particle distributions at AGS and lower SPS energies (less than 20 GeV/n) , can successfully be analyzed, but that the model fails for the RHIC data. Heinz's model calculation underestimates the tails of the charged particle distributions from RHIC, the discrepancy becoming bigger as the energy increases. To study the multiplicity distributions at RHIC we develop the so-called "Thermalization Component Model", which is based on Heinz's collective flow model. It is realized that the limitation of phase space of collective flow can be reflected in that of the thermalization region. By comparing the contributions of particle production from the thermaUzation regions at different energies and different centralities, we can deepen our understanding of the features of collective motion at RHIC.展开更多
Based on an isospin-dependent transport model, the effects of the density- and momentum-dependent potentials are studied by simulating Au on Au collisions at 90, 120, 150 and 400 MeV/nucleon. It is found that the calc...Based on an isospin-dependent transport model, the effects of the density- and momentum-dependent potentials are studied by simulating Au on Au collisions at 90, 120, 150 and 400 MeV/nucleon. It is found that the calculated results overestimate the experimental data on the directed flow and underestimate the data on the elliptic flow for protons. The impact of the density- and momentum-dependent potentials is observed in the mid-rapidity region of the final spectra. At 90 MeV/nucleon, the momentum-dependent potential has a larger impact on the observables than the density-dependent potential, and the elliptic flow has a higher value with the positive effective mass splitting. At 400 MeV/nucleon, however, the opposite is observed. The rapidity dependence of the elliptic flow for protons is sensitive to the symmetry energy. A soft symmetry energy corresponds to a higher value of the proton elliptic flow.展开更多
基金This study was supported by the National Natural Science Foundation ofChina(Nos.12147106,12175072,and 11722546)the Talent Programof South China University of Technology(No.20210115).
文摘The relativistic mean-field approach was implemented in the Lanzhou quantum molecular dynamics transport model(LQMD.RMF). Using the LQMD.RMF, the properties of collective flow and pion production were investigated systematically for nuclear reactions with various isospin asymmetries. The directed and elliptic flows of the LQMD.RMF are able to describe the experimental data of STAR Collaboration. The directed flow difference between free neutrons and protons was associated with the stiffness of the symmetry energy, that is, a softer symmetry energy led to a larger flow difference. For various collision energies, the ratio between the π^(-) and π^(+) yields increased with a decrease in the slope parameter of the symmetry energy. When the collision energy was 270 MeV/nucleon, the single ratio of the pion transverse momentum spectra also increased with decreasing slope parameter of the symmetry energy in both nearly symmetric and neutron-rich systems.However, it is difficult to constrain the stiffness of the symmetry energy with the double ratio because of the lack of threshold energy correction on the pion production.
基金partly supported by the National Natural Science Foundation of China (Nos. U2032145 and 11875125)the National Key Research and Development Program of China (No. 2020YFE0202002)。
文摘In this study, the rapidity distribution, collective flows, and nuclear stopping power in ^(197)Au+^(197)Au collisions at intermediate energies were investigated using the ultrarelativistic quantum molecular dynamics(UrQMD) model with GEMINI++ code. The UrQMD model was adopted to simulate the dynamic evolution of heavy-ion collisions, whereas the GEMINI++ code was used to simulate the decay of primary fragments produced by UrQMD. The calculated results were compared with the INDRA and FOPI experimental data. It was found that the rapidity distribution, collective flows, and nuclear stopping power were affected to a certain extent by the decay of primary fragments, especially at lower beam energies. Furthermore, the experimental data of the collective flows and nuclear stopping power at the investigated beam energies were better reproduced when the sequential decay effect was included.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11421505,11220101005,11305239 and 11605270the Major State Basic Research Development Program of China under Grant No 2014CB845401+1 种基金the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences under Grant No QYZDJ-SSW-SLH002the China Postdoctoral Science Foundation under Grant No 2016M591730
文摘The main purpose of the present work is to discuss whether or not the collective flows in heavy-ion collision at the Fermi energy can be taken as a tool to investigate the cluster configuration in light nuclei. In practice, within an extended quantum molecular dynamics model, four a-clustering (linear chain, kite, square and tetrahedron) configurations of 16O are employed in the initialization, 16O+16O around the Fermi energy (40-60 MeV/nucleon) with impact parameter 1-3fro are simulated, and the directed and elliptic flows are analyzed. It is found that collective flows are influenced by the different a-clustering configurations, and the directed flow of free protons is more sensitive to the initial cluster configuration than the elliptic flow. Nuclear reaction at the Fermi energy can be taken as a useful way to study cluster configuration in light nuclei.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No lzujbky-2014-170the Research Fund for the Doctoral Program of Higher Education of China under Grant No 20120211120002the National Natural Science Foundation of China under Grant Nos 11205075 and 11375076
文摘Within the framework of a semiclassical Boltzmann-Uehling-Uhlenbeck (BUU) transport model, the high mo- mentum tail (HMT) effects of nucleon momentum distribution in the nucleus on the nucleon collective flows are studied in semieentral Au+Au collisions. The HMT due to the isospin-dependent short-range correlations causes a smaller value of the collective flows. We find that the HMT effects on the nucleon collective flows are remarkable at beam energy of 300 MeV/nucleon and become weak as the incident beam energy increases. The results indicate that for the collective flow studies at intermediate energies, the HMT of nucleon momentum distribution in nucleus should be taken into account in transport models.
基金Supported by the National Natural Science Foundation of China under Grant No 11505150the Yuncheng University Research Project under Grant No YQ-2014014the China Postdoctoral Science Foundation under Grant No 2015M582730
文摘Within the isospin-dependent quantum molecular dynamics model, we investigate the nuclear collective flows produced in semi-central 197 Au+197 Au collisions at intermediate energies. The neutron proton differential flows and difference of neutron proton collective flows are sensitive to the momentum-dependent symmetry potential. This sensitivity is less affected by both the isoscalar part of nuclear equation of state and in-medium nucleon- nucleon cross sections. Moreover, this sensitivity becomes pronounced with increasing the rapidity cut.
基金Supported by National Natural Science Foundation of China(NSFC)(11265013)
文摘The directed and elliptic flow of positively charged kaons produced in 28^58Ni+28^58Ni reactions at incident kinetic energy 1.91 AGe V are studied within the covariant kaon dynamics and compared to new data. We observe that the influence of the Lorentz force on the directed and differential directed flow of K+mesons is obvious. Our calculated results indicate that it is necessary for the Lorentz force to be included in the kaon dynamics in order to reasonably describe experimental data.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030008)the National Natural Science Foundation of China(Nos.11890710,11890714,and 11961141003)the Strategic Priority Research Program of the CAS(No.XDB34000000)。
文摘In this study,we reconstruct theγ-photon energy spectrum,which is in good agreement with the experimental data of ^(86)Kr+^(12)C at E/A=44 Me V within the framework of the modified EQMD model.The directed and elliptic flows of free protons and direct photons were investigated by considering theα-clustering structure of ^(12)C.Compared with free protons,direct photon flows provide clearer information about the early stage of a nuclear reaction.The difference in the collective flows between different configurations of ^(12)C is observed in this study.This indicates that the collective flows of direct photons are sensitive to the initial configuration.Therefore,theγbremsstrahlung process might be taken as an alternative probe to investigate theα-clustering structure in a light nucleus from heavy-ion collisions within the Fermienergy region.
基金supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB34030200)the Guangdong Major Project of Basic and Applied Basic Research(No. 2020B0301030008)the National Natural Science Foundation of China (Nos. 12025501, 11890710, 11890714, and12147114)
文摘By implementing an additional heavy quark-antiquark pair production trigger in a multiphase transport(AMPT)model,we study the effect on anisotropy flows of identified particles with a focus on charged particles and quarkonium(J/ΨandΥ).A systematic increase in the collision rate for active partons in the AMPT model with such an implementation has been observed.It leads to a slight increase of identified particles anisotropy flows as a function of transverse momentum(pT)and rapidity,and gives a better description of the experimental data of elliptic flow toward larger pT.Our approach provides an efficient way to study the heavy quark dynamics in the AMPT model at LHC energies.
基金supported by the National Key Research and Development Program of China (No. 2020YFE0202002)the National Natural Science Foundation of China [Nos. 11890710(11890711) and 12175084]
文摘Collective flow is a powerful tool used to analyze the properties of a medium created during high-energy nuclear collisions.Here,we report a systematic study of the first two Fourier coefficients v_(1)and v_(2)of the proton andπ^(+)from Au+Au collisions in the energy range√sNN=2.11-4.9 GeV within the framework of a hadronic transport model(UrQMD).Recent results from the STAR experiment were used to test the model calculations.A meanfield mode with strong repulsive interaction is needed to reproduce the 10-40%data at 3 GeV.This implies that hadronic interactions play an important role in the collective flow development in the high baryon density region.The mean values of the freeze-out time for protons andπ^(+)are shifted earlier owing to the additional repulsive interactions.We predict the energy dependence of the mean values of the transverse momentum<pT>,v_(1),and v_(2)for both protons andπ^(+)from the Au+Au collisions.
基金the National Key Research and Development Program of China(Nos.2022YFA1604900 and 2020YFE0202002)the National Natural Science Foundation of China(Nos.12175084,11890710,11890711,11927901)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB34030000)Fundamental Research Funds for Central Universities(No.CCNU220N003).
文摘The Cooling Storage Ring external-target experiment(CEE)spectrometer is used to study the nuclear matter created in heavy-ion collisions at√sNN=2.1-2.4 GeV with the aim to reveal the quantum chromodynamics phase structure in the high-baryon-density region.Collective flow is considered an effective probe for evaluating the properties of media during high-energy nuclear collisions.One of the main functions of the zero-degree calorimeter(ZDC),a subdetector system in the CEE,is to determine the reaction plane in heavy-ion collisions.This step is crucial for measuring the collective flow and other reaction-plane-related analyses.In this paper,we illustrate the procedures for event plane determination using the ZDC.Finally,isospin-dependent quantum molecular dynamics model-based predictions of the rapidity dependence of the directed and elliptical flows for p,d,t,3He,and 4He,produced in 2.1 GeV U+U collisions,are presented.
基金Yingxun Zhang acknowledges the supports in part by the National Natural Science Foundation of China(Grant Nos.11875323,11875125,11475262,10675172,11075215,11475262,11790323,11790324,11790325,and 11961141003)the National Key R&D Program of China(Grant No.2018YFA0404404)+15 种基金the Continuous Basic Scientific Research Project(No.WDJC-2019-13)Ning Wang acknowledges the supports in part by the National Natural Science Foundation of China(Nos.U1867212 and 11422548)the Guangxi Natural Science Foundation(Nos.2015G XNSFDA139004,2017G XNSFG A198001)Qingfeng Li acknowledges the supports in part by the National Natural Science Foundation of China(Nos.11875125,11847315,11375062,11505057,11947410,and 11747312)the Zhejiang Provincial Natural Science Foundation of China(No.LY18A050002)the“Ten-Thousand Talent Program”of Zhejiang ProvinceJunlong Tian acknowledges the supports in part by the National Science Foundation of China(Nos.11961131010 and 11475004)Li Ou acknowledges the supports in part by the National Natural Science Foundation of China(No.11965004)the Natural Science Foundation of Guangxi Province(No.2016GXNSFFA380001)Foundation of Guangxi Innovative Team and Distinguished Scholar in Institutions of Higher EducationMin Liu acknowledges the supports in part by the National Natural Science Foundation of China(No.11875323)Kai Zhao acknowledges the supports in part by the National Natural Science Foundation of China(Nos.11675266,11005155,11475262,11275052,11375062,11547312,and 11275068)the National Key Basic Research Developm ent Program of China(Nos.2007CB209900 and 2013CB834404)Xizhen Wu acknowledges the supports in part by the National Natural Science Foundation of China(Nos.10235020,10979023,11005155,11365004,11475004,and 11675266)Zhuxia Li acknowledges the supports in part by the National Natural Science Foundation of China(Nos.19975073,10175093,10175089,10235030,11275052,11375062,11475262,11475004,11875323,and 11875125)the National Key Basic Research Development Program of China(Nos.G20000774 and 2007CB209900).
文摘In this review article,we first briefty 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 transrer,fragmentation,collective flow and particle production are reviewed and discussed within the framework of the two models.The constraints on the isospin asymmetric muclear 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.
基金Supported by National Natural Science Foundation of China (10975091)Excellent Youth Foundation of Hubei Scientific Committee (2006ABB036)Education Commission of Hubei Province of China (Z20081302)
文摘Taking the conservation of baryon number into account in a non-uniform flow model, the rapidity distribution of the net protons at the LHC is predicted. The energy dependence of the rapidity distribution, baryon stopping and collective flow from BNL/AGS to CERN/LHC are systematically investigated.
基金Supported by National Natural Science Foundation of China (10775089, 10475049)Science Fund of Qufu Normal University
文摘The centrality dependence of transverse momentum spectra for identified hadrons at midrapidityin Au+Au collisions at √sNN=200GeV is systematically studied in a quark combination model. The PTspectra of π^±, K^±, p(p) and A(A) in different centrality bins and the nuclear modification factors (Rcp) forthese hadrons are calculated. The centrality dependence of the average collective transverse velocity (β (r)) for the hot and dense quark matter is obtained in Au+Au collisions, and it is applied to a relative smallerCu+Cu collision system. The centrality dependence of PT spectra and the Rcp for π^0, Ks^0 and A in Cu-bCucollisions at √sNN = 200 GeV are well described. The results show that (β (r)〉is only a function of the numberof participants Npart and it is independent of the collision system.
基金Excellent Youth Foundation of Hubei Scientific Committee(2006ABB036)Education Commission of HubeiProvince of China (Z20081302)Natural Science Foundation of China Three Gorges University (2003C02)
文摘It is demonstrated that with Heinz's collective flow model charged particle distributions at AGS and lower SPS energies (less than 20 GeV/n) , can successfully be analyzed, but that the model fails for the RHIC data. Heinz's model calculation underestimates the tails of the charged particle distributions from RHIC, the discrepancy becoming bigger as the energy increases. To study the multiplicity distributions at RHIC we develop the so-called "Thermalization Component Model", which is based on Heinz's collective flow model. It is realized that the limitation of phase space of collective flow can be reflected in that of the thermalization region. By comparing the contributions of particle production from the thermaUzation regions at different energies and different centralities, we can deepen our understanding of the features of collective motion at RHIC.
基金Supported by National Natural Science Foundation of China(11505150)China Postdoctoral Science Foundation(2015M582730)Yuncheng University Research Project(YQ-2014014)
文摘Based on an isospin-dependent transport model, the effects of the density- and momentum-dependent potentials are studied by simulating Au on Au collisions at 90, 120, 150 and 400 MeV/nucleon. It is found that the calculated results overestimate the experimental data on the directed flow and underestimate the data on the elliptic flow for protons. The impact of the density- and momentum-dependent potentials is observed in the mid-rapidity region of the final spectra. At 90 MeV/nucleon, the momentum-dependent potential has a larger impact on the observables than the density-dependent potential, and the elliptic flow has a higher value with the positive effective mass splitting. At 400 MeV/nucleon, however, the opposite is observed. The rapidity dependence of the elliptic flow for protons is sensitive to the symmetry energy. A soft symmetry energy corresponds to a higher value of the proton elliptic flow.