Low dose data: Difference between revisions

Low dose data (view source)

321 bytes removed , 22 October 2019

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 In XDS, the background of a data frame is used for scaling adjacent frames relative to each other in the INTEGRATE step.
-This seems to work well down to an average of 0.05 counts/pixel. If, however, the crystal is exposed so shortly/weakly that the average drops significantly below this value, scaling becomes impossible - the ratio of averages which are around zero is obviously undefined. The keyword [http://homes.mpimf-heidelberg.mpg.de/~kabsch/xds/html_doc/xds_parameters.html#DATA_RANGE_FIXED_SCALE_FACTOR== DATA_RANGE_FIXED_SCALE_FACTOR] has been introduced to handle this situation.
+This seems to work well down to an average of 0.05 counts/pixel. If, however, the crystal is exposed so shortly/weakly that the average drops significantly below this value, scaling becomes impossible - the ratio of averages which are around zero is obviously undefined. The keyword [http://xds.mpimf-heidelberg.mpg.de/html_doc/xds_parameters.html#DATA_RANGE_FIXED_SCALE_FACTOR== DATA_RANGE_FIXED_SCALE_FACTOR] has been introduced to handle this situation.
-Even if this feature is used, DEFPIX may stop with the (misleading) error message <pre>!!! ERROR !!! WRONG DETECTOR PARAMETERS</pre> If this happens, omit DEFPIX from the JOB= list of parameters, and copy BKGINIT.cbf to BKGPIX.cbf (DEFPIX would have to write BKGPIX.cbf, but this has to be done manually).
 See also: [[Difficult datasets]]