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- I24-CdTe-Eiger
Beamline Phone Number:
+44 (0) 1235 778950
Principal Beamline Scientist:
Robin Owen
Tel: +44 (0) 1235 778522
E-mail: robin.owen@diamond.ac.uk
Email: david.hall@diamond.ac.uk
Tel: +44 (0) 1235 778926
The CdTe Eiger2 9M detector is a new type of detector that allows routine high energy MX. At high energies the diffracted intensity per unit absorbed dose is increased for protein crystals. This means you can use a lower dose to obtain the same Bragg intensities and so your crystal will last longer in the X-ray beam. Evidence for this can be found in the IUCrJ paper
Experimental evidence for the benefits of higher X-ray energies for macromolecular crystallography
Selina L. S. Storm, Danny Axford and Robin L. Owen
https://doi.org/10.1107/S2052252521008423
For data collections when you don't need to be near an elemental edge for phasing there is really no downside to collecting at 17.5 or 20 keV compared to 12.4 keV. The CdTe E9M detector can also be used at 'standard' MX energies but it is worth reading the below before choosing the best detector for your beamtime.
Please let us know if you have feedback on the detector or these pages.
The Pilatus you are familiar with is still in place. You can switch between the detectors using GDA
Click the relevant 'change to..' to choose the detector you want to use.
The detectors are mounted in an 'up and under' configuration. it takes ~5mins for the vertical stage to move between detectors.
High energy notes
Our default high energies are currently 17.5 keV (flux approx 3x10^12 ph/s) or 20 keV (flux approx 2x10^12 ph/s). Higher energies will become accessible in the near future. If you have a pressing reason to push higher please talk to your local contact ahead of your beamtime.
'Normal' energy notes
Our default 'normal' energy is 12.4 keV. The CdTe works well at 12.4 keV but note that an Eiger 9M is somewhat smaller than a Pilatus 6M. Currently the minimum crystal to detector distance is 200 mm (we are working to reduce this). At this distance and at 12.4 keV
The data quality from the two detectors at 12.4 keV is comparable. See comparative plots from a selenium soaked thaumatin crystal below. The dominant factor at high resolution is the detector size and the differing fall off in stats reflects the size of the detector.
You can also collect good data using the CdTe E9M below 12 keV but at some point the area of the detector will become limiting
https://www.diamond.ac.uk/Instruments/Mx/I04/I04-Manual/Eiger2-Detectors.html
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