Here is an outline of a data processing workflow. This assumes that you already have your data collected. Depending on your objectives, follow the matching track.

The scripts and software you should use for each step are

• Data: you should look at your diffraction data with Fabian. Pay attention about image orientation and rotation. You can also start looking at diffraction intensity levels, in the background, in the peaks, etc.
• Generating backgrounds, median, average images: Image Math.
• Looking at images with background subtracted: Fabian.
• Peak extraction: Peaksearch
• To be completed…

1. Create an input file with the ending .inp. It should contain information on instrumentals of the experiment, the grain, the sample, strain, background, peak shape, and so on. You find an example of an input file here.
2. Next you can run the simulation with PolyXSim. This simulation may take a while…
3. Afterwards, you can look at the output with Fabian.
4. If you have “real” data, this would be the point when you work on the background (more information on this topic here). If you also simulated noise, strain or other things that make your data look more like “real” data, it might be useful to do a background substraction, too.
5. Now you can search for peaks using the software PeakSearch.
6. In ImageD11 the found peaks are fitted to the parameters of the sample and experiment, followed by the calculation of the g-vector.
7. With the calculated g-vector, the grains will now be indexed, using GrainSpotter.
8. The calculated grains should then be compared and checked with the simulated grains.

Create an input file with the ending .inp. For a start, simply modify an existing one like this. Afterwards, you can run the simulation with PolyXSim. The purpose of this step is to simulate the outcome of a DAC experiment (grains with random orientations, random strains etc.). The simulation will not only provide 2D diffraction images but also G-vectors, inverse Ub matrices and some more files. You will get at least 7 different files from the simulation plus the diffraction images. The amount of diffraction images depends on the ω range and the step size. For example, a ω range from -28° to +28° with a step size of 0.5° produces 112 images (numbers from 0 to 111).

To run the simulation write the following to the Konsole:

PolyXSim.py -i 'some_input_file'.inp

The 7 different files (which were just mentioned above) are usually created quite fast. The time consuming process is the creation of images. This time highly depends on the parameters you put in the input file, e.g. the amount of grains, the peak shape and if you switched on strain tensors or noise. If you just want to test if the software is working it is wise to use an input file with very simple parameters (only 1 grain, no strain tensors, no noise, small ω range etc.).

While the simulation is running you can already look at the images, which are already created, with Fabian. Open a new tab in the Konsole and open Fabian:

fabian.py