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Pathologies: Difference between revisions
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→Scale factor plot in case of problems (beam or spindle)
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The scale factor is printed, in INTEGRATE.LP, for every frame (column 3). This plot shows spikes indicating that the beam was weak, or the spindle went too fast every 13 frames or so. A change of flux ''within'' a frame is detrimental to data quality; however if the change of flux occurs during the readout (i.e. between the frames) then the scale factor accurately compensates the flux change. A change in rotation speed is also to some extent compensated by the change in scale factor, but there is the additional effect that the next frame starts at a phi offset (which has to be compensated by ORIENTATION refinement in INTEGRATE). | The scale factor is printed, in INTEGRATE.LP, for every frame (column 3). This plot shows spikes indicating that the beam was weak, or the spindle went too fast every 13 frames or so. A change of flux ''within'' a frame is detrimental to data quality; however if the change of flux occurs during the readout (i.e. between the frames) then the scale factor accurately compensates the flux change. A change in rotation speed is also to some extent compensated by the change in scale factor, but there is the additional effect that the next frame starts at a phi offset (which has to be compensated by ORIENTATION refinement in INTEGRATE). | ||
Possible sources of beam flux changes are attenuators that vibrate, top-up injections, and other types of vibrations. The shorter the exposure times are, the more these problems usually become visible. | |||
=== Mosaicity plots in case of problems === | === Mosaicity plots in case of problems === | ||