Model independent determination of the elastic incoherent structure factor in neutron scattering experiments

In quasielastic neutron scattering (QENS) the dynamic structure factor S(Q, ω) consists of an elastic central line with area given by the elastic incoherent structure factor (EISF) and a continuous quasielastic broadening. Using only the resolution function of the spectrometer we discuss a method to derive the EISF directly from the raw experimental data points S(Q, ω) without any smoothing or any modelling of the quasielastic broadening. We compare this model to the Fourier transform method, show how it works on actual neutron scattering data and discuss its accuracy for several cases.