What is a Wedged MAD data collection?
Each circle on the figure below represents 180o sweep on the same crystal at three different energies. For example GDA will first collect sweep 1 (0 to 45o) at Energy 1, then sweep 2 (0 to 45o) at Energy 2, followed by sweep 3 (0 to 45o) at Energy 3 and so on.
The advantage using wedged MAD collection compared to regular MAD data collection is that the same reflection at three (or more) different energies will be collected with equivalent dose. It will result in a better assesment of the anomalous signal less polluted by radiation damage.
How to set up a Wedged MAD data collection
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 Folder where you want to collect your data, Prefix and the specs for the data collection. For example for each energy we will collect 1800 images, 0.1o oscillation, 0.040s exposure and 100% transmission:
Add experiments until you have one for each energy you want to collect for your MAD data. In this example we will do 3 energies.
Change the wavelength or energy in the table to the desired value for each experiment:
Then convert entry into wedged MAD as shown below:
In this example we choose to do wedge of 25o(250 images with 0.1o oscillation). Note that for wedged MAD data collection we recommend to use 5o wedge or lower.
The data collection has been broken up into 25o wedges and reorganized so that each wedge is collected at 3 different energies before moving on to the next wedge. The prefix name has also been updated to indicate which energy is collected: E1, E2 or E3. To run it just click on the "Run All" button.
In this case the results will appear as 3 data sets: Lysoszyne_E1, Lysozyme_E2 and Lysozyme_E3.
Note that the wedged MAD experiment is not restricted to 3 energies.