SMEARING EFFECTS INTRODUCED BY THE RESPONSE FUNCTION OF POSITION-SENSITIVE GAS DETECTORS IN SAXS EXPERIMENTS

The response of gas-filled position-sensitive detectors consists not o nly of the main Gaussian response (FWHM similar to 0.1 mm) but also of a linear exponential term measurable up to 7 mm from the excitation, superimposed on an incoherent background. This effect depends on gas t ype and pressure and is due to fluorescence of the detection gas. The consequences of this effect on some standard experimental methods used in small-angle X-ray scattering (SAXS), i.e. Porod limit and Guinier radii determination, are investigated.