General formula for determination of cross-section from measured SANS intensities

A detailed derivation of the formula connecting measured SANS intensity with the smeared cross-section (raw-data treatment) is presented. The derivation is carried out considering also a possible high probability of the coherent small-angle scattering. The information content of the so-called transmission measurement is analyzed. The individual effects which contribute to the primary-beam attenuation as well as the different modes of the transmission measurement are described. Multiple scattering contribution to the excess of the forward scattering of the water calibration standard is discussed.