Detector calibration procedure for detectors with Kappa Euler and partial Euler/Kappa goniostats.

Here is a description of the test data needed for full calibration:

  • Lysozyme or similarly well diffracting crystal - frozen.
  • Detector should be placed in such distance that diffraction spots can be observed in the corners.
  • The oscillation angle should be 1 degree.
  • Probably 10 seconds per frame should be adequate - if you will not have reasonably strong spots at the corner make the exposure longer and check your primary beam intensity.
 
!!!!! IMPORTANT: 2theta (swing) should be set to zero for sets 1-6 !!!!!
 

Calibration of the Kappa/Euler goniostat requires the following data sets 

  1. 180 degrees of omega scan, phi=0, kappa=0  (oscillation range 1 degree, 180 frames)
  2. 20 degrees of omega scan, phi=180, kappa=0 (oscillation range 1 degree, 20 frames)
  3. 20 degrees of omega scan, phi=0, kappa=5 (oscillation range 1 degree, 20 frames)
  4. 20 degrees of omega scan, phi=0, kappa=-10 (oscillation range 1 degree, 20 frames)
  5. 20 degrees of omega scan, phi=20, kappa=-10 (oscillation range 1 degree, 20 frames)
  6. 20 degrees of omega scan, phi=0, kappa=0 (oscillation range 1 degree, 20 frames) at the distance that differs by 10 millimeters.
  7. 20 degrees of omega scan, phi=0, kappa=0 (oscillation range 1 degree, 20 frames) with 2theta 10 degrees
  8. 20 degrees of omega scan, phi=0, kappa=0 (oscillation range 1 degree, 20 frames) with 2theta -5 degrees

    And optionally:

  9. 20 degrees of phi scan, omega=-45 (oscillation range 1 degree, 20 frames) (optional - phi scanning is usually inferior); only for Kappa goniostat
 
Explanation:
 
Set 1 is needed to calibrate distortion and overall performance of the detector.
Sets 1-6 are needed to calibrate the goniostat
Sets 7-8 are needed to calibrate goniostat and swing angle.
 
The Kappa in the previous description should be replaced by Chi for Euler goniostat. For partial Euler or Kappa, some scans have to be omitted. 
 
 
Note that the distance and swing are correlated. If you do not have a distance controlled by the motor, the calibration will strongly depend on how accurate the distance is set.