Isoscaling in statistical models

Different statistical multifragmentation models have been used to study isoscaling, i.e., the factorization of the isotope ratios from two reactions, into fugacity terms of proton and neutron number, R21(N ,Z) 5Y 2(N ,Z)/Y 1(N ,Z)5C exp(aN1bZ). Even though the primary isotope distributions are quite different from the final distributions due to evaporation from the excited fragments, the values of a and b are not much affected by sequential decays. a is shown to be mainly sensitive to the proton-to-neutron composition of the emitting source and may be used to study isospin-dependent properties in nuclear collisions, such as, the symmetry energy in the equation of state of asymmetric nuclear matter.