Impact parameter smearing effects on isospin sensitive observables in heavy ion collisions

Abstract

The validity of impact parameter estimation from the multiplicity of charged particles at low-intermediate energies is checked within the framework of ImQMD model. The simulations show that the multiplicity of charged particles cannot estimate the impact parameter of heavy ion collisions very well, especially for central collisions at the beam energies lower than $\sim$70 MeV/u due to the large fluctuations of the multiplicity of charged particles. The simulation results for the central collisions defined by the charged particle multiplicity are compared to those by using impact parameter b=2 fm and it shows that the charge distribution for ${}^{112}$Sn +${}^{112}$Sn at 50 MeV/u is different evidently for two cases; and the chosen isospin sensitive observable, the coalescence invariant single neutron to proton yield ratio, reduces less than 15\% for neutron-rich systems ${}^{124,132}$Sn +${}^{124}$Sn at $E_{beam}$=50 MeV/u, while the coalescence invariant double neutron to proton yield ratio does not have obvious difference. The sensitivity of the chosen isospin sensitive observables to effective mass splitting is studied for central collisions defined by the multiplicity of charged particles. Our results show that the sensitivity is enhanced for ${}^{132}$Sn+${}^{124}$Sn relative to that for ${}^{124}$Sn+${}^{124}$Sn, and this reaction system should be measured in future experiments to study the effective mass splitting by heavy ion collisions.

6 pages, 5 figures, accepted by PRC

References in corpus (11)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Results of the ASY-EOS experiment at GSI: The symmetry energy at suprasaturation density
• Neutron and Proton Transverse Emission Ratio Measurements and the Density Dependence of the Asymmetry Term of the Nuclear Equation of State
• Nucleon Effective Masses in Neutron-Rich Matter
• Nuclear symmetry energy and its density slope at normal density extracted from global nucleon optical potentials
• Symmetry Energy of Nucleonic Matter With Tensor Correlations
• Isospin Diffusion and Equilibration for Sn+Sn collisions at E/A=35 MeV
• Neutron-proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon-nucleus scattering data within an isospin dependent optical model
• Isospin Diffusion Observables in heavy ion reactions
• Revisit of the neutron/proton ratio puzzle in intermediate-energy heavy-ion collisions
• Competition between Coulomb and Symmetry Potential in Semi-peripheral Heavy-ion Collisions

Cited by in corpus (5)

• Constraints on the symmetry energy and its associated parameters from nuclei to neutron stars
• Progress of Quantum Molecular Dynamics model and its applications in Heavy Ion Collisions
• Determining impact parameters of heavy-ion collisions at low-intermediate incident energies using deep learning with convolutional neural network
• A new probe to study symmetry energy at low density by deuteron breakup reaction
• Model independent reconstruction of impact parameter distributions for intermediate energy heavy ion collisions