Screening

Open the QEGui Eiger_collect_tab by clicking “MX collect” on the PyPanel at the bottom of the home screen, and select the Screening tab.

Fill in details for your sample in the Input boxes:

1. Attenuation: How much of the beam is cut off. It can be anywhere between 0 and 99%, depending on how well you crystal diffracts and how much you are worried about beam damage. Please note, this is not transmittance!

2. File Prefix: The name of your sample or pin. If you are mounting with the robot, this will automatically fill with the puck and sample number. Otherwise, fill it in with your sample name. USE ONLY ALPHANUMERICS. DO NOT USE SPACES, DASHES OR SPECIAL CHARACTERS. And it must be shorter than 60 characters.

3. Folder: The folder the data will go into. If you are using the robot it will also autofill. Otherwise leave it as /s/.

4. Total exposure: The time your crystal will be in the beam. Standard exposure for a screen is 2 seconds. If you are already on 0% attenuation and not getting high enough resolution, you can increase this.

5. Wedge: The angle your crystal will rotate through during the total exposure. Standard wedge for a screen is 20 degrees.

6. Distance: The detector distance. The closest approach is 110 mm, which will get you the highest resolution possible. To calculate the distance you need for a given resolution, go to the Distance Selector tab in the QEGui MX1/ MX2 controls.

7. Frequency: Leave this at 0.00

Click Screen. The shutter will open and collect the 20 degree wedge in 2 seconds.

To see the result of your screening, open the Processing results page, by clicking the Quick Access link on the PyPanel and selecting “All processing results (dataset and indexing)”. This page shows a new line for every screening or dataset you run (for more information on processing, see Data Processing ) While it is processing it will show the status as a Blue information box on the right of each line. After XDS has run you will see:

1. A green Success box next to your sample if the data processing has been successful. It will show you the Resolution, space group and unit cell based on this wedge.

2. A red Failed box will show up if the data has not processed. If you want to retrigger this screening to see if it will succeed, follow instructions on the Data Processing page.

Once you are happy with your screening, copy your sample information from the Screening tab to the Collection tab by clicking Copy on the Screening tab.

The screening results can be used to determine the optimum data collection strategy. To do this, check the box which says Autostrategy on the Screening tab. See for instructions.