Introduction
Software
Experiment
Data processing
Post-processing and results evaluation
Advanced discussions
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The aim of the calibration of the standard material is to obtain
Sample-detector distance and beam center can be obtained either from Fit2D or Dioptas. Both options should give the same (or very, very similar) results.
The instrument parameters are calculated in a different way, depending on the software (MAUD or ImageD11). Furthermore, each software uses parameters which the other software doesn't use. So even if the calibration in MAUD and ImageD11 seems to be the same, one has to do both calibrations independently from each other.
To make life easier, one should start with the sample-detector distance and the beam center (Fit2D/Dioptas). You can then enter those parameters in MAUD and ImageD11 and have already a very good guess. This saves time in the process of refinement.
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To do this, you should first have a look at your calibration image with Fabian. Check the intensities of the rings and the background (values at the bottom right of the Fabian window). Estimate a threshold value which clearly separates the background from the ring intensities.
Next, you can perform a Peaksearch. Then, you can load these peaks into ImageD11 (click Transformation → Load filtered peaks). Click Transformation → Edit parameters and enter all values which you know for certain. These are usually the cell parameters (make sure to use the same standard as in Fit2D/Dioptas and MAUD!), O-Matrix, omegasign, wavelength and pixel size. For the sample-detector distance and the beam center enter the values you obtained from Fit2D/Dioptas. Leave the other values as they are. Now activate the check boxes for distance, t_x, t_y, t_z, tilt_x, tilt_y, tilt_z, y_center and z_center and click Ok.
Click Transformation → Plot tth/eta. Now click Transformations → Fit repetitively until the lines are very straight, even when you zoom in.
For a last check-up you can click Transformation → Add unit cell peaks. The red tick marks should match the green lines of peaks perfectly.
When you're done, save the parameters (Transformation → Save parameters) with the ending .prm. Whenever you feel like doing something in ImageD11 in the future, always load the parameter file first (Transformation → Load parameters) and change nothing but the cell parameters (Transformation → Edit parameters)!
To process the data you need it in EDF format. Usually, the beamlines provide their data in MarCCD or TIFF so you have to convert it before further use.
