Relationship between counting modes, absolute noise term and the errors of structure functions in the interpretation of small‐angle X‐ray scattering data

The requirements imposed on the magnitude of the noise in a scattering curve in order to minimize the corresponding error in the structure functions are estimated for a given value of the time T in which the scattering curve is recorded. Typical small‐angle X‐ray scattering (SAXS) curves have been used to check how these conditions are fulfilled when different counting modes are applied for the measurement. It is shown that fixed‐time counting is the most practical technique and produces error bands in the structure functions with magnitudes close to the smallest values attainable in SAXS investigations.