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Since at this stage you can only look at angles between
different nrlvs (and ndlvs), correct values for the
crystal to detector distance
and the beam position are crucial for
successful indexing. To check the beam position:
- Display the conics at the top of the list of ndlvs with
a reasonable small value of on the image using:
show ndlv 1
and check if these conics look like proper ellipses/hyperboles/etc.
- If a large number of conics has wrongly assigned spots, you have to refine
the beam position, using the correct conics:
calc beam 1 2 4 5 8 9 11
If the beam position changes significantly, you should rerun
NODIRAX ( run nodirax), check and, if necessary,
refine the beam position again.
- The beam position can also be checked by using the
gnomonic projection, show gnom dist.
Spots lying on a conic in the Laue pattern will form a straight
line in the gnomonic projection. Curving of these lines
indicates an error in the direct beam position. You can try to
optimize the beam center manually using this projection.
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