Ice rings: Difference between revisions

Revision as of 07:25, 20 May 2013

For versions of XDS after May 30,2013 one can use INCLUDE_RESOLUTION_RANGE and EXCLUDE_RESOLUTION_RANGE already in the IDXREF step. For the latter to be effective, the geometry should of course be rather accurate.
Please see Optimization for how to treat remaining ice reflections showing up as "aliens" in CORRECT.LP.

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-* Please see [[Wishlist#Would be nice to have]]: there's a list of additional (high-) resolution ranges one might want to exclude (in [[CORRECT]]).
+* For versions of XDS after May 30,2013 one can use INCLUDE_RESOLUTION_RANGE and EXCLUDE_RESOLUTION_RANGE already in the IDXREF step. For the latter to be effective, the geometry should of course be rather accurate.
-* A currently possible way to prevent ice rings from spoiling the [[IDXREF]] step is to set "TRUSTED_REGION=0 X" for INIT, where X is calculated such that ice rings are excluded. Using Bragg's law and an approximation, we find that <br /> X = <math>\frac{Wavelength \cdot Distance} {4 \cdot NX \cdot QX}</math> should give approx. 4 Å cutoff, which should exclude all ice rings. <br /> Drawback: after successful indexing, INIT needs to be re-run with "TRUSTED_REGION=0 1.05" or so.
-A potential pitfall: the above assumes that the direct beam position is near the middle of the detector.
 * Please see [[Optimization]] for how to treat remaining ice reflections showing up as "aliens" in [[CORRECT.LP]].