Ice rings: Difference between revisions
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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]]). | * Please see [[Wishlist#Would be nice to have]]: there's a list of additional (high-) resolution ranges one might want to exclude (in [[CORRECT]]). | ||
* 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} { | * 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. | 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]]. | * Please see [[Optimization]] for how to treat remaining ice reflections showing up as "aliens" in [[CORRECT.LP]]. | ||
Revision as of 16:24, 5 December 2012
- Please see Wishlist#Would be nice to have: there's a list of additional (high-) resolution ranges one might want to exclude (in CORRECT).
- 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
X = [math]\displaystyle{ \frac{Wavelength \cdot Distance} {4 \cdot NX \cdot QX} }[/math] should give approx. 4 Å cutoff, which should exclude all ice rings.
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.