Compaq Graphical User Interface mar345 - Manual (Page 14)

mar345 Program Manual 1 4
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The Change Parameters window is used to program data collection parameters. The
window comes in 4 slightly different flavours, depending on the button choice in the Collect
Menu:
− Single Data Set
− Multiple Data Sets
− Index Crystal
− MAD Data
The difference is, that in Multiple Data Sets one can program up to 64 data sets with the full
range of parameters. The amount of data sets that are offered for programming can be
controlled by the configuration file (entry SETS).
Index Crystal is a special way of collecting data with a
ϕ
movement inbetween each image.
This
ϕ
movement is denominated "
ϕ
increment" and serves the purpose to collect a small
number of images at different positions in
ϕ
.To collect 2 images that are 90 degrees away
from eachother with a
ϕ
oscillation of 1.0 degree for each image one will have to give an
increment of 89.0 degrees.
MAD Data is a special way of collecting data with anomalous signals. In this mode, a number
of images is collected, then the
ϕ
axis moves forward and collects the same number of
images in the equivalent position 180 degrees away.
Otherwise the items displayed in the window are as follows:
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Item Description
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Title Single Data Set, Multiple Data Sets or Index Crystal.
Directory Directory where the images will be written to.
Image root Name root of image files.
Scan mode Choice of image plate diameter to be scanned (345, 300,
240 or 180mm) and pixelsize used (0.1mm or 0.15mm)
Output format Usually only 1 choice: mar345. This format features a very
efficient image compression that requires approx. 70% less
disk space than uncompressed data.
Collect mode Time controlled or X−ray dose controlled
ϕ
movement.
The latter one should be used on X−ray sources with variable
X−ray flux (synchrotrons).
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