Isospin Effects on Anisotropic Flows in Intermediate Energy Heavy Ion Collisions

Anisotropic flows per nucleon (v(1)/A, v(2)/A v(3)/A and v(4)/A) of light fragments up to the mass number 4 as a function of transverse momentum per nucleon are studied for 55 MeV/nucleon Fe-58+Fe-58 and Ni-58+Ni-58 at large impact parameters by the isospin-dependent quantum molecular dynamics model. The effects of symmetry energy and nucleon-nucleon cross sections, which are both isospin-dependent on anisotropic flows, are studied in detail. In comparison of the two systems with or without symmetry potential term, the results show that the strength of flows is sensitive to symmetry potential and nucleon-nucleon cross sections, which mainly cause a repulsion effect in this energy region.