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Nuclear Science and Techniques 2024年第1期35卷 155-169页

作者： Si-Na Wei Zhao-Qing Feng School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China

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.

关键词： Heavy-ion collision collective flow Pion production Symmetry energy Relativistic mean field

collective flow of K^+ mesons in heavy-ion collisions predicted by the covariant Kaon dynamics

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Chinese Physics C 2015年第11期39卷 50-53页

作者：邢永忠戴月茜 Institute of Fundamental Physics Tianshui Normal University

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.

关键词： kaon meson collective flow heavy-ion collisions covariant dynamics

Effects of sequential decay on collective flows and nuclear stopping power in heavy-ion collisions at intermediate energies

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Nuclear Science and Techniques 2023年第4期34卷 175-184页

作者： Kui Xiao Peng-Cheng Li Yong-Jia Wang Fu-Hu Liu Qing-Feng Li State Key Laboratory of Quantum Optics and Quantum Optics Devices and Collaborative Innovation Center of Extreme Optics Institute of Theoretical PhysicsShanxi UniversityTaiyuan 030006China School of Science Huzhou UniversityHuzhou 313000China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China Institut für Theoretische Physik Goethe Universität FrankfurtFrankfurt am Main 60438Germany Institute of Modern Physics Chinese Academy of ScienceLanzhou 730000China

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.

关键词： Heavy-ion collisions Sequential decay effect collective flow Nuclear stopping power

Event plane determination from the zero degree calorimeter at the cooling storage ring external-target experiment

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Nuclear Science and Techniques 2023年第7期34卷 113-121页

作者： Li-Ke Liu Hua Pei Ya-Ping Wang Biao Zhang Nu Xu Shu-Su Shi Key Laboratory of Quark and Lepton Physics(MOE)and Institute of Particle Physics Central China Normal UniversityWuhan 430079China

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.

关键词： QCD phase structure Heavy-ion collisions collective flow Reaction plane Zero-degree calorimeter

Anisotropy flows in Pb-Pb collisions at LHC energies from parton scatterings with heavy quark trigger

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Nuclear Science and Techniques 2022年第2期33卷 14-20页

作者： Hai Wang Jin-Hui Chen Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China

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.

关键词： Heavy-ion collision Quark-gluon plasma Quarkonium collective flow

Anisotropic flow in high baryon density region

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Nuclear Science and Techniques 2022年第2期33卷 79-86页

作者： Shao-Wei Lan Shu-Su Shi Key Laboratory of Quark and Lepton Physics(MOE)and Institute of Particle Physics Central China Normal UniversityWuhan 430079China

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,v_(1),and v_(2)for both protons andπ^(+)from the Au+Au collisions.

关键词： Heavy-ion collisions QCD phase diagram UrQMD collective flow Mean-field potential

α-clustering effect on flows of direct photons in heavy-ion collisions

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Nuclear Science and Techniques 2021年第6期32卷 122-132页

作者： Chen-Zhong Shi Yu-Gang Ma Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China University of the Chinese Academy of Sciences Beijing 100080China

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.

关键词： Nuclear reaction Direct photon collective flow α-clustering configuration

Analysis of charged hadron multiplicity distributions at RHIC

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Chinese Physics C 2008年第8期32卷 639-644页

作者：熊伟冯笙琴 College of Science China Three Gorges University

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.

关键词： thermalization collective flow thermalization component model

Progress of quantum molecular dynamics model and its applications in heavy ion collisions

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Frontiers of physics 2020年第5期15卷 1-64页

作者： Ying-Xun Zhang Ning Wang Qing-Feng Li Li Ou Jun-Long Tian Min Liu Kai Zhao Xi-Zhen Wu Zhu-Xia Li China Institute of Atomic Energy Beijing 102413China Key Laboratory of Nuclear Physics and Technology Guangxi Normal UniversityGuilin 541004China Guangxi Normal University Guilin 541004China School of Science Huzhou UniversityHuzhou 313000China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Physics and Electrical Engineering Anyang Normal UniversityAnyang 455002China

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.

关键词： quantum molecular dynamics model low energy heavy ion collisions low-intermediate energy heavy ion collisions fusion multinucleon transfer reaction multifragmentation collective flow isospin asymmetric equation of state in-medium nucleon-nucleon cross sections

Rapidity distributions of net protons from AGS to LHC energy regions

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Chinese Physics C 2010年第8期34卷 1085-1089页

作者：钟洋冯笙琴 College of Science China Three Gorges University Key Laboratory of Quark and Lepton Physics (Huazhong Normal Univ.) Ministry of Education School of Physics and Technology Wuhan University

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... 详细信息

关键词： relativistic heavy ion collisions LHC collective flow baryon stopping