Hi Stephan,
If there were overflows on the detector, which cause lines due to the
spill over of the wells of the CCD, the lines would be visible in the
readout direction of the CCD detector, which generally is from bottom to
top or top to bottom. You can also see this with your own (pocket)
camera if you point it towards a bright light source, before you take
the actual picture.
The lines cannot be in a skew direction and will always be connected to
very strong reflections. As you can see in the images Margriet sent, the
lines are parallel to one of the reciprocal planes and there are plenty
of lines in the image that are not connected to reflections.
With very (and I mean very) strong reflections you will sometimes see an
speckled arc around the reflection. This is diffraction of the beryllium
window of the detector, where the reflected beam acts as the primary
beam (see attached picture.)
Bram
Stephan Ginell wrote:
Hi.... Such line can occur on a CCD detector if reflection are
saturating a pixel and is generally in the direction of the detector
readout. 1) what detector are you using, 2) are reflections in the
black center saturated i.e. Greater than the dynamic range of the
detector. 3) what is your exposure time, 4) do you see such streaks on
short / attenuated exposures? 5 do you see such streaks on dark images
of (no x-rays) but same time.
Steve
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*Bram Schierbeek*
Application Scientist Structural Biology
Bruker AXS B.V.
Oostsingel 209, P.O.Box 811
2600 AV Delft, the Netherlands
Tel.: +31 (15) 2152508
Fax: +31 (15)2152599
bram.schierb...@bruker-axs.nl
_www.bruker-axs.com_ <www.bruker-axs.de>
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