Residue Coulomb Interaction Among Isobars and Its Influence in Symmetry Energy of Neutron-Rich Fragment**Supported by the Program for Science & Technology Innovation Talents in Universities of Henan Province (13HASTIT046), and Young Teacher Project in Henan Normal University (HNU), China

Abstract

The residue Coulomb interaction (RCI), which affects the result of symmetry-energy coefficient of neutron-rich nucleus in isobaric yield ratio (IYR) method, is difficult to be determined. Four RCI approximations are investigated: (i) The M1–RCI adopting the ac/T (the ratio of Coulomb energy coefficient to temperature) determined from the IYR of mirror-nucleus fragments; (ii) The M2–RCI by fitting the difference between IYRs; (iii) The M3–RCI adopting the standard Coulomb energy at a temperature T = 2 MeV; and (iv) Neglecting the RCI among isobars. The M1–, M2– and M3–RCI are no larger than 0.4. In particular, the M2–RCI is very close to zero. The effects of RCI in asym/T of fragment are also studied. The M1– and M4–asym/T are found to be the lower and upper limitations of asym/T, respectively. The M2–asym/T overlaps the M4–asym/T, which indicates that the M2–RCI is negligible in the IYR method, and the RCI among the three isobars can be neglected. The relative consistent low values of M3–asym/T (7.5 ± 2.5) are found in very neutron-rich isobars.