Model independent method for determination of the DIS structure of free neutron

We present a model independent procedure for extracting deep-inelastic structure function of "free'' neutron from the electron - deuteron scattering with protons produced in the target fragmentation region of the reaction. This procedure is based on the extrapolation of t, which describes the invariant momentum transfered to the proton, to the unphysical region corresponding to the mass of the struck neutron. We demonstrate that the impulse approximation diagram of the reaction has a pole at this limit with a residue being proportional to the "free" neutron structure function. The method is analogous to that of Chew and Low for extraction of the ``free'' pion-pion and neutron-neutron cross sections from p(pion,p)X and d(n,n)pn reactions respectively. We demonstrate that in the extrapolation the final state interaction amplitudes are smooth functions of $t$ and have negligible contribution in the extracted ``free'' nucleon structure function. We also estimate the range of the recoil nucleon momenta which could be used for successful extrapolation procedure.