Figure 8
Geometry involved in detection of a Bragg peak at qHKL = (qr, qz) in transmission geometry. In this illustration the sample is oriented perpendicular to the hexapod platform and the incident X-ray beam. For a given qHKL, the Bragg peak can only be located on the circle on the detector that corresponds to q = |qHKL|. The dash-dotted circle represents the trace on the Ewald sphere that corresponds to q = |qHKL|. The dashed circle represents the possible location of the qHKL vector for the crystal being examined. The crystal must be rotated by ω = θ − α in the plane defined by the incident beam and qHKL, so that the reciprocal vector qHKL for the crystal becomes located on the Ewald sphere and therefore the corresponding Bragg peak is recorded in the diffraction pattern. |