TY - INPR A1 - Li, Qingfeng A1 - Li, Zhuxia A1 - Stöcker, Horst T1 - Probing the symmetry energy and the degree of isospin equilibrium N2 - The rapidity dependence of the single- and double- neutron to proton ratios of nucleon emission from isospin-asymmetric but mass-symmetric reactions Zr+Ru and Ru+Zr at energy range 100 ~ 800 A MeV and impact parameter range 0 ~ 8 fm is investigated. The reaction system with isospin-asymmetry and mass-symmetry has the advantage of simultaneously showing up the dependence on the symmetry energy and the degree of the isospin equilibrium. We find that the beam energy- and the impact parameter dependence of the slope parameter of the double neutron to proton ratio (F_D) as function of rapidity are quite sensitive to the density dependence of symmetry energy, especially at energies E_b ~ 400 A MeV and reduced impact parameters around 0.5. Here the symmetry energy effect on the F_D is enhanced, as compared to the single neutron to proton ratio. The degree of the equilibrium with respect to isospin (isospin mixing) in terms of the F_D is addressed and its dependence on the symmetry energy is also discussed. Y1 - 2006 UR - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/2670 UR - https://nbn-resolving.org/urn:nbn:de:hebis:30-27347 ER -