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Xscale: Difference between revisions
→Radiation damage correction
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== Radiation damage correction == | == Radiation damage correction == | ||
To "switch on" radiation damage correction ([http://dx.doi.org/10.1107/S0907444903006516 K. Diederichs, S. McSweeney and R. B. G. Ravelli (2003) Zero-dose extrapolation as part of macromolecular synchrotron data reduction. ''Acta Cryst.'' '''D59''', 903-909]) it suffices to use the CRYSTAL_NAME keyword. '''The CRYSTAL_NAME parameters of different datasets do not have to be different'''. If they are different, this results in more degrees of freedom (namely, the slopes of the reflection intensity as a function of dose) for the program to fit the observed changes of intensities which are induced by radiation damage. However, if the datasets are based on the same crystal, or the datasets are based on crystals from the same drop, it is reasonable to assume that the slopes are the same. | === based on resolution shell and frame number === | ||
The usual (like in MOSFLM and other programs) correction based on resolution shell and frame number is performed in [[XDS]] as part of the CORRECT step - it can be switched off by omitting DECAY from the default CORRECTIONS= DECAY MODULATION ABSORP). This correction is also available from XSCALE. | |||
It is instructive to inspect DECAY.pck (using "VIEW DECAY.pck"). This visualizes the scale factors employed by the CORRECT step; the right bar gives the mapping between colours and numbers. Along the horizontal axis the frame number is shown, along the vertical axis the resolution shell. | |||
=== for individual reflections === | |||
To "switch on" radiation damage correction of individual reflections ([http://dx.doi.org/10.1107/S0907444903006516 K. Diederichs, S. McSweeney and R. B. G. Ravelli (2003) Zero-dose extrapolation as part of macromolecular synchrotron data reduction. ''Acta Cryst.'' '''D59''', 903-909]) it suffices to use the CRYSTAL_NAME keyword. '''The CRYSTAL_NAME parameters of different datasets do not have to be different'''. If they are different, this results in more degrees of freedom (namely, the slopes of the reflection intensity as a function of dose) for the program to fit the observed changes of intensities which are induced by radiation damage. However, if the datasets are based on the same crystal, or the datasets are based on crystals from the same drop, it is reasonable to assume that the slopes are the same. | |||
Example: | Example: | ||
OUTPUT_FILE=fae-merge.ahkl | OUTPUT_FILE=fae-merge.ahkl | ||