  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)=Y2(N,Z)/Y1(N,Z)=C*exp(a*N+b*Z). 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
and 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.
