Can multiple neutron scattering be computed without knowing the scattering law?

The most common approach to the computation of multiple neutron scattering is based on ray-tracing simulations where scattering events are sampled from the joint probability distribution of energy and momentum transfer as calculated from the dynamic structure factors of the sample. We present here an alternative route based on Monte Carlo calculation of multiple scattering intensity expressed through multidimensional integrals where the free-gas scattering law is assumed. The results for double scattering are compared in a test case with those obtained with the ray-tracing approach using as input simulated data for the dynamic structure factors.