X-ray data using area detectors are commonly collected in one of two ways:
  • In Small-Angle (SAXS) mode, the more common of the two, the primary beam is on or close to the detector (generally with a beamstop between the beam and the detector), and the face of the detector is approximately normal to the beam. If the detector is relatively close to the sample, the angular range spanned by the detector will be large, while if it is farther away the range will be small, but in either case the widest angle obtainable is generally determined by the size of the detector and the smallest angle by the size of the beamstop. Bragg rings will look approximately circular on the detector in this case. In Datasqueeze, the relationship between momentum transfer q and pixel number (x,y) can be determined if the instrumental configuration is characterized in terms of the wavelength lambda, the q-range (span of the detector in momentum), the coordinates of the pixel where the primary beam hits, and the amount and direction by which the detector is tilted relative to the primary beam (Detector Tilt and Tilt Azimuth).
  • In the less commonly used Wide Angle (WAXS) mode, the detector is mounted on a 2theta arm which may be rotated by a wide angle (often 90 degrees or more) from the primary beam. In Datasqueeze, the instrumental configuration is now characterized by the wavelength lambda, the q-range (the span in momentum transfer that the detector would have if the beam center were at the center of the detector), the amount and direction by which the detector 2theta arm was rotated relative to the primary beam (Detector 2Theta and Detector Azimuth), and the coordinates of the pixel where the primary beam would hit if Detector 2Theta = 0.
In Batch mode see the WAXSMODE option.