we ran into a funny thing which may or may not be your problem.
It seems that between two versions of FIT2D the definition of the center
of the IP changed. It was related to how FIT2D defined the top and
bottom of the image. We found out in similar fashion. We ran
calibrations and extracted the detector-sample distance at the
synchrotron, then integrated data at home. Things weren't working out.
We traced it to the fact that there was a different version number for
the FIT2D at the beamline and on our home computers. We redid the
calibration on the same FIT2D that we did the integration and all was well.
S
Angus P. Wilkinson wrote:
Dear All:
Recently we performed some measurements using a MAR345 detector. As we
knew the ambient temperature and pressure lattice constants for the
sample, we used this information for the sample to image plate and tilt
correction calibration in FIT2D. We then used this sample to plate and
tilt information to perform an integration of the same image that was
used for the calibration. If we take the integrated data and perform a
LeBail fit in GSAS we can not get a good fit to the data without
introducing a zero shift (this does not make sense to me). Additionally,
after refining the zero shift, the lattice constant that we get back is
different from that used in the original calibration! Essentially the
peak positions in the integrated data do not agree with the peak
positions that were used in the calibration. Any ideas as to what might
be going wrong?
Thanks in advance, Angus
Dr. Angus P. Wilkinson School of Chemistry and
Biochemistry
Prof. Chemistry and Biochemistry Georgia
Institute of Technology
Prof. Materials Science and Engineering 770 State St.
Atlanta, GA 30332-0400
Tel: 404 894 4036
Fax: 404 894 7452
--
Prof. Simon Billinge
Department of Physics and Astronomy
4268 Biomed. Phys. Sciences Building
Michigan State University
East Lansing, MI 48824
tel: +1-517-355-9200 x2202
fax: +1-517-353-4500
email: [EMAIL PROTECTED]
home: http://nirt.pa.msu.edu/
