X-ray Centring

You can use grid scans to automatically centre your sample. This method is very successful with well frozen (ice-free) crystals mounted in clean loops.

For an already mounted sample make sure your loop is in the field of view and then click the X-ray Centre button on the Align tab of the Alignment view in GDA.

To enable X-ray Centring when driving data collections for each robot loaded sample, please open the 'User Options' and click the option labelled 'HT X-Ray Centring (5 min/sample)' before you load the (first) sample you want to centre. Additionally, the second option 'Use OAV Centring after Keyence Centring' needs to be ticked, which is the default.

Before selecting a sample make sure you specify your data collection parameters in the data collection table, as the data collection currently starts immediately after X-ray Centring.

If you now load your sample, the routine puts the loop at the cross-hairs (Keyence Centring), performs the OAV centring and then automatically carries out a two-dimensional grid scan. Afterwards, a finer, linear grid scan is performed perpendicularly to the two-dimensional one at the position where the crystal diffracts best. Then, the data collection is automatically started. The whole process from loading the sample to the end of a 360 degree data collection with standard parameters takes approximately 3.5 min.