Density and Symmetric Potential Dependences of Isoscaling Behaviour in the Lattice Gas Model

Isoscaling behaviour of the statistical emission fragments from the equilibrated sources with Z = 30 and N = 30, 33, 36 and 39 is investigated in the framework of the isospin-dependent lattice gas model. The dependences of isoscaling parameters a on source isospin asymmetry, temperature and freeze-out density are studied, and the 'symmetry energy' is deduced from isoscaling parameters. The results show that symmetry energy Csym is insensitive to the change of temperature but follows the power-law dependence on the freeze-out density ρ. The effect of strength of asymmetry of nucleon-nucleon interaction potential on the density dependence of the symmetry energy is discussed. (nuclear physics)