Inverse Beam SAD

The circle on the figure below represents 360^o sweep on the same crystal with the same energy. For example, GDA will first collect sweep 1 (0 to 45^o), then sweep 2  at 180^o apart (181 to 225^o), followed by sweep 3 (46 to 90^o) and so on...

The advantage using inverse beam SAD data collection compared to regular SAD data is that the Friedel pairs will be collected with equivalent dose. It will result in a better assesment of the anomalous signal less polluted by radiation damage.

In GDA, go to "Data Collection" then click on the tab "Data Collection Table Input"

Note: Click on the images to view full size

Enter the parameters required for your data collection. For example omega start 0 degree, 0.1^o oscillation, 0.040s exposure, energy at 12658 eV and 1800 images for total oscillation of 180^o. You need to be aware that after converting into inverse beam SAD mode the total oscillation will doubled and be effectively 360^o in this case. 

Then convert entry into inverse beam SAD as shown below:

In this example we choose to do wedge of 25^o (250 images with 0.1^o oscillation). Note that for inverse beam SAD data collection we recommend to use 5^o  wedge or lower.

The data collection has been broken up into 25^o wedges and reorganized so that each wedge is collected 180^o apart. The prefix name has also been updated to indicate which wedge is collected: A or B, with B meaning same wedge as A + 180^o. To run it just click on the "Run All" button.