arXiv subjects

C. W. Ma

Publications and source records attributed to C. W. Ma.

26 records · Page 2Linked to original sources

arXiv2006

Surveying the Nucleon-Nucleon Momentum Correlation Function in the Framework of Quantum Molecular Dynamics Model

Momentum correlation functions of the nucleon-nucleon pairs are presented for reactions with C isotopes bombarding a $^{12} \rm C$ target within the framework of the isospin-dependent quantum molecular dynamics model. The binding-energy dependence of the momentum correlation functions is also explored, and other factors that have an influence on momentum correlation functions are investigated. These factors include momentum-dependent nuclear equation of state, in-medium nucleon-nucleon cross sections, impact parameters, total pair momenta, and beam energy. In particular, the rise and the fall of the strength of momentum correlation functions at lower relative momentum are shown with an increase in beam energy.

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arXiv2006

Dynamical and sequential decay effects on isoscaling and density dependence of the symmetry energy

The isoscaling properties of the primary and final products are studied via isospin dependent quantum molecular dynamics (IQMD) model and the followed sequential decay model GEMINI, respectively. It is found that the isoscaling parameters $α$ of both primary and final products keep no significant change for light fragments, but increases with the mass for intermediate and heavy products. The dynamical effects on isoscaling are exhibited by that $α$ value decreases a little with the evolution time of the system, and opposite trend for the heavy products. The secondary decay effects on isoscaling are reflected in the increasing of the $α$ value for the final products which experiences secondary decay process. Furthermore the density dependence of the symmetry energy has also been explored, it is observed that in the low densities the symmetry energy coefficient has the form of $C_{sym}(ρ)\sim C_{0}(ρ/ρ_{0})^γ$, where $γ= 0.7 \sim 1.3$ for both primary and final products, but $C_{0}$ have different values for primary and final products. It is also suggested that it might be more reasonable to describe the density dependence of the symmetry energy coefficient by the $C_{sym}(ρ/ρ_{0})\approx C_{1}(ρ/ρ_{0})^{γ_{soft}} + C_{2}(ρ/ρ_{0})^{γ_{stiff}}$ with $γ_{soft}\leq 1$, $γ_{stiff}\geq 1$ and $C_{1}, C_{2}$ constant parameters.

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arXiv2005

Isoscaling behavior in the Fission Dynamics

The fission processes of $^{112}$Sn + $^{112}$Sn and $^{116}$Sn + $^{116}$Sn are simulated with the combination of the Langevin equation and the statistical decay model. The masses of two fission fragments are given by assuming the process of symmetric fission or asymmetric fission by the Monte Carlo sampling with the Gaussian probability distribution. From the analysis to the isotopic/isotonic ratios of the fission fragments from both reactions, the isoscaling behavior has been observed and investigated in details. Isoscaling parameters $α$ and $β$ are extracted as a function of the charge number and neutron number, respectively, in different width of the sampling Gaussian probability distribution. It seems that $α$ is sensitive to the width of fission probability distribution of the mass asymmetrical parameter but $β$ is not. Both $α$ and $β$ drop with the increasing of beam energy and the reduced friction parameter.

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arXiv2005

Isoscaling of projectile-like fragments

The isotopic and isotonic distributions of the projectile fragmentation products have been simulated by a modified statistical abrasion-ablation (SAA) model and the isoscaling behavior of projectile-like fragments has been discussed. The isoscaling parameters $α$ and $β$ for hot fragments before evaporation and cold fragments after evaporation have been extracted, respectively. It looks that the evaporation has strong effect on $α$. For cold fragments, a monotonic increase of $α$ and $|β|$ with the increasing of $Z$ and $N$ is observed. The relation between isoscaling parameter and the change of isospin content is demonstrated. In addition, the disappearance of the isospin effect of projectile fragmentation is also discussed in the viewpoint of isoscaling parameter.

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arXiv2005

Effect of Hadronic Rescattering on Elliptic Flow Following Hydrodynamics Model

The effect of hadronic rescattering on the elliptic flow has been investigated by the Cooper-Frye hadronization model from hydrodynamic evolution following by the afterburner hadronic rescattering model for 200 GeV/c Au + Au at 20-40% centrality. It is found that the hadronic rescattering can suppress elliptic flow $v_2$ in momentum space especially in lower transverse momentum region. In addition, the hadronic rescattering effects on transverse momentum spectra and anisotropy coordinate space of hadrons are studied.

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arXiv2005

Study on the One-Proton Halo Structure in $^{23}$Al

The Glauber theory has been used to investigate the reaction cross section of proton-rich nucleus $^{23}$Al. A core plus a proton structure is assumed for $^{23}$Al. HO-type density distribution is used for the core while the density distribution for the valence proton is calculated by solving the eigenvalue problem of Woods-Saxon potential. The transparency function in an analytical expression is obtained adopting multi-Gaussian expansion for the density distribution. Coulomb correction and finite-range interaction are introduced. This modified Glauber model is apt for halo nuclei. A dominate s-wave is suggested for the last proton in $^{23}$Al from our analysis which is possible in the RMF calculation.

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arXiv2005

$Δ$-scaling and heat capacity in relativistic ion collisions

The $Δ$-scaling method has been applied to the total multiplicity distribution of the relativistic ion collisions of p+p, C+C and Pb+Pb which were simulated by a Monte Carlo package, LUCIAE 3.0. It is found that the $Δ$-scaling parameter decreases with the increasing of the system size. Moreover, the heat capacities of different mesons and baryons have been extracted from the event-by-event temperature fluctuation in the region of low transverse mass and they show the dropping trend with the increasing of impact parameter.

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arXiv2004

Isoscaling behavior in the Isospin dependent Quantum Molecular Dynamics model

The isoscaling behavior is investigated in the frame of Isospin dependent Quantum Molecular Dynamics (IQMD) models. The isotopic yields ratio $Y_2$/$Y_1$ for reactions $^{48}Ca$+$^{48}Ca$ and $^{40}Ca+^{40}Ca$ at different entrance channels are simulated and presented, the relationship between the isoscaling parameter and the entrance channel is analyzed, the results show that $α$ and $β$ reduce with the rise of incident energies and increase with the impact parameter b, which can be attributed to the temperature varying of the pre-fragments in different entrance channels. The relation of $α$ and symmetry-term coefficient $C_{sym}$ reveals that the chemical potential difference $\triangleμ$ is sensitive to the symmetry-term coefficient $C_{sym}$.

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