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

2017/12/31 by Li Li, Yingxun Zhang, Zhuxia Li +4 · 15 citations
Physics and Astronomy · #Heavy ion #High-Energy Particle Collisions Research #Impact parameter #Ion #Isospin #Nuclear physics #Nuclear physics research studies #Observable #Particle physics #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Statistical physics #nucl-ex #nucl-th

paper · pdf · doi:10.1103/physrevc.97.044606

published in Physical Review C 97(4) (American Institute of Physics) · 6 pages, 5 figures, accepted by PRC

openalex publication_date 2018/04/16 · arxiv created 2018/04/18 · arxiv updated 2018/04/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

The validity of impact parameter estimation from the multiplicity of charged particles at low-intermediate energies is checked within the framework of the improved quantum molecular dynamics 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 \ensuremath∼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 ¹¹²Sn+¹¹²Sn at the beam energy of 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 ^124,132Sn+¹²⁴Sn 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 ¹³²Sn+¹²⁴Sn relative to that for ¹²⁴Sn+¹²⁴Sn, and this reaction system should be measured in future experiments to study the effective mass splitting by heavy ion collisions.

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