> >>XIONGJP at UOXRAY.UOREGON.EDU wrote:
> >> I collected a dataset at about 20 degree of chi angle. But I can
You could try to get the chi angle more accurately. Try something
like this:
Overlay all your images with a program such as dtdisplay, MADNES or
IPDISP. You should see very clearly the direction of the rotation axis,
from which you can calculate the exact chi angle.
Use a program like MADNES or d*TREK which supports any rotation axis.
Refine the plate rotation angle around the beam.
Since you expect the rotation angle to be 0, adjust chi so the
the detector rotation around the beam is 0 degrees.
In this case (with these programs), the polarization and Lorentz
corrections will be calculated correctly.
If you forgot to lock down the chi axis during data collection and it actually
moved over the course of your experiment, then you are probably wasting
your time.
Jim
