Chemical properties of intermediate mass residue with isobaric yield ratio method in heavy-ion reaction

Background: Chemical properties of projectile residues are important in studying the symmetry energy using isobaric yield ratio (IYR) and isoscaling methods. Purpose: The correlation between chemical properties of intermediate mass residues and reaction systems is to be studied. It is hoped that the symmetry energy information can be extracted more precisely. Methods: In the framework of the grand-canonical ensemble theory, the Δμ/T difference between two heave-ion reactions, which was labeled as Δμ₂₁/T, was extracted by using isobaric yield ratio difference (IBD) method. Results: By comparing the Δμ₂₁/T among six different combinations ⁴⁸Ca + ⁹Be/⁴⁰Ca + ⁹Be, ⁴⁸Ca + ⁹Be/⁵⁸Ni + ⁹Be, ⁶⁴Ni + ⁹Be/⁴⁰Ca + ⁹Be, ⁶⁴Ni + ⁹Be/⁵⁸Ni + ⁹Be, ⁵⁸Ni + ⁹Be/⁴⁰Ca + ⁹Be, ⁴⁸Ca + ⁹Be/⁶⁴Ni + ⁹Be, it was proved that Δμ/T depends on the reaction system. In different reactions, the values of Δμ/T were not fixed. When the double neutron-to-proton ratios (N/Z)₂₁ = 1.17, Δμ₂₁/T can be approximately a constant. Conclusion: Symmetry energy can be more reasonable in isoscaling and IBD methods, when double neutron-to-proton ratios (N/Z)₂₁ = 1.17 between two similar reaction system. (authors)