Isoscaling in statistical sequential decay model

A sequential decay model is used to study isoscaling, i.e. the factorization of the isotope ratios from sources of different isospins and sizes over a broad range of excitation energies, into fugacity terms of proton and neutron number, R21(N,Z)=Y2(N,Z)/Y1(N,Z)=C exp(αN + βZ). It is found that the isoscaling parameters α and β have a strong dependence on the isospin difference of equilibrated source and excitation energy, no significant influence of the source size on α and β has been observed. It is found that α and β decayse with the excitation energy and are linear functions of 1/T and Δ(Z/A)2 or Δ(N/A)2 of the source. Symmetry energy coefficient Csym is constrained from the relationship of α and source Δ(Z/A)2, β and source Δ(N/A)2. (authors)