P02.1 - Public : Azimuthal integration of 2D data with DAWN

1. Calibration of the sample-to-detector distance 

• Open DAWN and select the “Powder Calibration” tab (right upper corner).
• Load your calibration image (left upper corner): File > Open File > (search your file) > Click Open
• Choose the right calibrant in the Calibrant section. Use a lower number of rings in the first iteration (e.g., 10 rings):

Notice that the size of each window or viewing area can be adjusted by placing the mouse pointer in the gap between them until a double arrow appears. Then click and drag. Additionally, the contrast of the detector image displayed in the Diffraction Plotting window can be also adjusted by clicking and dragging the mouse pointer along the scale:

• Select the “Manual” mode in the Routine subtab and fix the energy under the Options subtab: (notice that if you change the mode from "Manual" to "Automatic", you will need to set the Options subtab again)

• Introduce the right values in the Powder Diffraction window. From top to bottom: Wavelength: request your local contact the calculated energy value; Distance: introduce the approximate sample-to-detector distance; Detector: select the right detector type; Normal (orientation):set yaw, pitch and roll to zero.

Notice that as you change the sample-to-detector distance, the position of the calculated diffraction rings on the detector image (red rings in the Diffraction Plotting window) change as well.

• Click and drag to adjust the beam center:

• Go back to the Routine subtab and click on Find Rings. After that, you can run the calibration: click the Run Calibration button (left bottom corner):

• The integrated pattern and calculated diffraction lines are shown in the Powder Calibration Check window. You can zoom in and out by using the Rubberhand Zoom and Perform Auto Scale icons (indicated by two red arrows in the screenshot above on the right). You can repeat the calibration using a higher number of rings and check if the result improves.

• Save your calibration file here:

2. Integration of diffraction patterns

• Go to the Processing tab (upper right corner) and load the patterns that you want to integrate (left upper corner): File > Open File > (you can select multiple files) > Click Open. A window pops up where you can choose the file type. It is set to 2D-image by default. Let the program load the detector image and click on “Finish”. Now a list of patterns should me shown in Data Slice View.
• Now, you need to create your own beamstop mask. For that, click on the DataVis tab (right upper corner), load an image using 'File > Open File' (e.g., you can use the calibrant image), and check the box that appears to the right of the file name in the Data Files window.The detector image will be displayed on the Plot window.

• Select the Fast Mask option from the Image Tools list indicated by a green arrow on the next screenshot. Go to the right-hand panel and, in the Draw Regions window choose ‘Box’ as the shape of your mask (blue arrow) and click on Draw (pink arrow). Place the mouse pointer on the detector image and click and drag to create a rectangle along the beamstop. In case something went wrong while drawing, you can delete the box by clicking on Remove All (red dashed rectangle on the screenshot). Once you have created the final rectangle, click on Apply (orange arrow): the rectangle will become solid green. Click on Save (red arrow) to save the mask: browse to choose the right file location, enter a file name (e.g., beamstop_mask) and click on Save. Now click on Next and unclick all the given options except for Mask. Enter again the same file name (beamstop_mask), and click on Finish.

• Go back to the Processing tab. Request your local contact the DAWN pipeline created for P02.1: notice that P02.1 provides pipelines for both detector configurations: center or corner configuration. Go to the Processing window and load the right pipeline by clicking on the Load configured pipeline icon, browse, select the pipeline and click OK.

• Let’s set the right values in each of the operation lines in the Processing window:
  • Click on the Import Detector Calibration line and import the calibration file that you previously created. Click the folder icon, select your file, click Open and press enter.

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  • No changes needed in the Powder Diffraction Intensity Corrections operation.
  • In the first Import Mask From File operation, import the detector mask provided by your local contact (this mask should be in the same folder as the pipeline).
  • In the second Import Mask From File operation, import the beamstop mask that you have created.
  • Nothing needed in the Mask by coordinate. You actually delete it by selecting it and clicking here:

• • In the Azimuthal Integration operation line, set the Number of bins to 5000, delete whatever is written in the Radial range (this way the program will use the entire range) and select the wanted X axis units.
  • Last step, click on the Export to Text File operation and choose the file extension and the folder where you want to store the integrated patterns:

• In order to run the pipeline through all the loaded patterns, click on the green arrow that appears at the top of the Data Slice View window, choose the same file path as the one that you chose for the Export to Text File operation, AND if you want all the integrated patterns to be plot together in the DataVis tab, click on Automatically load data to DataVis perspective:

• Now you can visualize your integrated patterns in the DataVis tab.