Isospin effect in statistical sequential decay

Isospin effect of the statistical emission fragments from the equilibrated source is investigated in the frame of statistical binary decay implemented into the GEMINI code, isoscaling behavior is observed and the dependences of isoscaling parameters alpha and beta on emission fragment size, source size, source isospin asymmetry and excitation energies are studied. Results show that alpha and beta neither depends on light fragment size nor on source size. A good linear dependence of alpha and beta on the inverse of temperature T is manifested and the relationship of alpha=4C(sym)[(Z(s)/A(s))(1)(2)-(Z(s)/A(s))(2)(2)]/T and beta=4C(sym)[(N-s/A(s))(1)(2)-(N-s/A(s))(2)(2)]/T from different isospin asymmetry sources is satisfied. The symmetry energy coefficient C-sym extracted from simulation results is similar to 23 MeV which includes both the volume and surface term contributions, of which the surface effect seems to play a significant role in the symmetry energy.