The New X-Ray Guy

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The New X-Ray Guy
Peter Müller
Peter Mueller
4. Göttingen
3. Kasierslautern
1. Frankenthal / Mannheim
2. La Chapelle Aux Bois
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The New X-Ray Guy
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The New Cryostream
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And now Some Crystallography

• Judging the Quality of a Crystal.
• Determining the Best Exposure Time.
• Data Collection Strategy.

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Judging the Quality of the X-tal
Initial Immages
Take two immages 90 appart.
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Judging the Quality of the X-tal
The Rocking Curve
Number of frames in both directions
Size of the box
halfwidth mosaicity
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Determining the Exposure Time
Compare two (or more) immages that differ only in
exposure time. Does a longer exposure time add
information to the immage?
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Determining the Exposure Time
20 seconds is better than 10 seconds. 30
seconds not better than 20 sconds. Our exposure
time is 20 seconds per frame.
Always collect a new dark current at your
exposure time or at least load an older (but not
too old!) dark current taken at your exposure
time.
compare
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Collect Dark Current
Now you are ready for data collection
What is the best strategy?
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The Platform Geometry
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phi- and omega-scans
phi- and omega-scansare orthogonal
Omega-scansat different phi-angles
Phi-scansat different omega-angles
...try to combine them!
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Collect Dark Current
Three 200 omega-scans and two 360 phi-scans
Two 200 omega-scans and one 360 phi-scan
thats plenty for any situation.
is enough for mmm and higher.
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The Zero-Frames
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The Zero-Frames
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We have a new HOMEPAGE
http//web.mit.edu/x-ray
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Next Meeting
Tuesday November 9,1100 a.m. AMDUR room (here)
Data Reduction with SAINT and SADABS
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