The most common layout for small- (and wide-) angle X-ray scattering experiments, the so-called transmission geometry is shown in the figure. The center of the set-up is the sample, being hit by highly parallel and monochromatic X-rays, and the scattered photons are recorded by one or more detectors placed downstream from the position of the interaction.
The direct result of a scattering measurement with a two-dimensional position sensitive detector is the so-called scattering pattern. Each image element (pixel) holds the number of recorded X-ray impacts in the corresponding detector element. This number is proportional to the intensity scattered under the angle pertaining to that pixel. From this matrix a one-dimensional scattering curve can be derived by azimuthal averaging. This curve carries the dependence of the scattered intensity from the scattering angle in a more tractable form.