(a) The peaks of LaB6 in high-resolution mode (radius of 240 mm) with the data collected using a stationary detector at each peak position while rocking the sample. The intensities match those of the database (cf. Fig. 10) and the peaks widths match those expected from theory (see text). (b) The profile of 001 LaB6 at 55 mm (dashed line) and 240 mm (continuous line), indicating how the resolution is improved, and how without rocking sometimes the peak profile can be very narrow, suggesting that the intrinsic instrumental broadening is very small (dotted line).