  The effect of different isospin-dependent cross-section on directed flow is
studied for variety of systems(for which experimental balance energies are
available) using an isospin-dependent Quantum Molecular Dynamic (IQMD) model.
We show that balance energies are sensitive towards isospin-dependent
cross-sections for light systems, while nearly no effect exist for heavier
nuclei. A reduced cross-section $\sigma = 0.9\sigma_{NN}$ with stiff equation
of state is able to explain experimental balance energies in most of systems. A
power law behaviour is also given for the mass dependence of balance energy,
which also follow N/Z dependence.
