Figure 5.

Back detector refinement. (a) Top: experimental setup. High-angle diffracted X-rays are recorded on the front CSPAD, while low-angle Bragg reflections are recorded on the back detector, approximately 2.5 m from the crystal. Bottom: Δxy plots for hierarchical mode refinement of the back detector, showing Δxy initially and after refining the detector, quadrants and sensors, colored as in Fig. 3 ▸. Regions with no diffraction were shadowed by equipment in the beam path. (b) Maximum composite of runs 11–22, showing refined sensor positions. Rays extending radially from the beam center arise from diffraction from the liquid jet. Rings are numbered according to their Miller indices. Rings 001, 002 and 003 are systematic absences in space group P6₁22; 564 reflections were indexed for 001, but for 002 and 003 fewer than ten each were found (dashed lines). Only one reflection from 113 was observed (solid red line). Enlarged views of 001 and 003 are shown on the lower right. Reflections are listed in a table on the right along with their resolution and the multiplicity of observation. (c) Correlation of calculated intensities from PDB entry 4ow3 with average intensities from reflections indexed on the back CSPAD. Intensities from the back CSPAD are unscaled and otherwise uncorrected. Nonsystematically absent reflections with at least 20 observations are shown, and they have a CC of 65.7% with the intensities calculated from the reference structure.