Thermodynamic properties and shear viscosity over entropy-density ratio of the nuclear fireball in a quantum-molecular dynamics model

Within a Boltzmann transport model, we demonstrate correlation between stopping observables and shear viscosity in central nuclear collisions at intermediate energies (on the order of 10-1000MeV/nucleon). The correlation allows us to assess the viscosity of nuclear matter, by tuning the in-medium nucleon-nucleon cross section in our transport model to agree with nuclear stopping data. We also calculate the ratio of shear viscosity to entropy density to determine how close the system is to the universal quantum lower limit proposed in the context of ultrarelativistic heavy ion collisions. * bbarker@roosevelt.edu 1 arXiv:1612.04874v3 [nucl-th]

Section: The Nn Cross Section In the Nuclear Mediummentioning

confidence: 99%

Shear viscosity from nuclear stopping

Barker

Danielewicz

2019

“…In the current work, six source systems with different masses and charge numbers but with similar N/Z of approximately ∼ 1.3, i.e., (A,Z) = (36, 15), (52,24), (80, 33), (100, 45), (112, 50), and (129, 54), are excited at an initial temperature varying from 0 to 20 MeV. The de-excitation process can be studied using the ThIQMD model [25].…”

Section: Calculations and Discussionmentioning

confidence: 99%

“…where ρ is the total density of the nuclear system, which is calculated using the interaction density in IQMD [23,24,48,49] as follows:…”

Section: Modelmentioning

confidence: 99%

Finite-size scaling phenomenon of nuclear liquid-gas phase transition probes

Liu

Fang

2019

Self Cite

Based on the isospin-dependent quantum molecular dynamics model, finite-size scaling effects on nuclear liquid-gas phase transition probes are investigated by studying the de-excitation processes of six thermal sources of different sizes with the same initial density and similar N/Z. Using several probes including the total multiplicity derivative (dMtot/dT ), second moment parameter (M2), intermediate mass fragment (IMF) multiplicity (NIMF ), Fisher's power-law exponent (τ ), and Ma's nuclear Zipf's law exponent (ξ), the relationship between the phase transition temperature and the source size has been established. It is observed that the phase transition temperatures obtained from the IMF multiplicity, Fisher's exponent, and Ma's nuclear Zipf's law exponent have a strong correlation with the source size. Moreover, by employing the finite-size scaling law, the critical temperature Tc and the critical exponent ν have been obtained for infinite nuclear matter.

“…The quark-gluon plasma (QGP) produced in ultrarelativistic heavy-ion collisions is believed to be a nearly ideal fluid and has a very small specific shear viscosity η/s [1-4], i.e., the ratio of the shear viscosity η to the entropy density s. It has been further found that the η/s decreases with increasing temperature in the hadronic phase while increases with increasing temperature in QGP, resulting in a minimum value at the temperature of hadron-quark phase transition [5,6]. At even lower temperatures, the η/s of nuclear matter with nucleon degree of freedom has been investigated from the relaxation time approach [7-9] and transport model studies [10][11][12][13]. Similar to the behavior near hadron-quark phase transition, the η/s also shows a minimum in the vicinity of nuclear liquid-gas phase transition from various approaches [11][12][13][14][15][16].…”

mentioning

confidence: 99%

“…At even lower temperatures, the η/s of nuclear matter with nucleon degree of freedom has been investigated from the relaxation time approach [7-9] and transport model studies [10][11][12][13]. Similar to the behavior near hadron-quark phase transition, the η/s also shows a minimum in the vicinity of nuclear liquid-gas phase transition from various approaches [11][12][13][14][15][16]. Since the correlation between the elliptic flow and the specific shear viscosity seems to be a general feature in not only relativistic [3] but also intermediate-energy heavy-ion collisions [17], it might be promising to measure the η/s experimentally, meanwhile providing an alternative way of searching for nuclear liquid-gas phase transition in heavy-ion collisions at intermediate energies in the future.…”

mentioning

confidence: 99%

Isospin splitting of nucleon effective mass and shear viscosity of nuclear matter

2015

Based on an improved isospin-and momentum-dependent interaction, I have studied the qualitative effect of isospin splitting of nucleon effective mass on the specific shear viscosity of neutron-rich nuclear matter from a relaxation time approach. It is seen that for m n > m p , the relaxation time of neutrons is smaller, and the neutron flux between flow layers is weaker, leading to a smaller specific shear viscosity of neutron-rich matter compared to the case for m n < m p . The effect is larger in nuclear matter at higher densities, lower temperatures, and larger isospin asymmetries, but it does not affect the behavior of the specific shear viscosity much near nuclear liquid-gas phase transition. PACS number(s): 21.65.−f, 64.10.+h, 51.20.+d Understanding the basic strong interaction and the properties of nuclear matter is the main purpose of nuclear physics. The knowledge of transport properties of the hot dense matter is important in understanding the dynamics in heavy-ion collision experiments as well as the properties of protoneutron stars. The quark-gluon plasma (QGP) produced in ultrarelativistic heavy-ion collisions is believed to be a nearly ideal fluid and has a very small specific shear viscosity η/s [1-4], i.e., the ratio of the shear viscosity η to the entropy density s. It has been further found that the η/s decreases with increasing temperature in the hadronic phase while increases with increasing temperature in QGP, resulting in a minimum value at the temperature of hadron-quark phase transition [5,6]. At even lower temperatures, the η/s of nuclear matter with nucleon degree of freedom has been investigated from the relaxation time approach [7-9] and transport model studies [10][11][12][13]. Similar to the behavior near hadron-quark phase transition, the η/s also shows a minimum in the vicinity of nuclear liquid-gas phase transition from various approaches [11][12][13][14][15][16]. Since the correlation between the elliptic flow and the specific shear viscosity seems to be a general feature in not only relativistic [3] but also intermediate-energy heavy-ion collisions [17], it might be promising to measure the η/s experimentally, meanwhile providing an alternative way of searching for nuclear liquid-gas phase transition in heavy-ion collisions at intermediate energies in the future.In my previous studies, the specific shear viscosity of neutron-rich matter was investigated based on an isospinand momentum-dependent interaction [9,16]. Recently, this interaction has been further improved [18], providing the possibility of studying more flexibly detailed isovector properties of nucleon interaction, such as the neutron-proton effective mass splitting. The interest was inspired by the recent experimental data of double neutron/proton ratio from the National Superconducting Cyclotron Laboratory, which seems to favor a smaller neutron effective mass than proton based on the calculation using an improved quantum molecular dynamics model [19]. However, the well-known Lane * xujun@sinap.ac.cn potential, r...