Hi Mark,
I think William was asking by how much he could increase the
transmission by given a certain crystal size - the rough answer being he
could increase to 100% as he has ~10 positions given the beam and
crystal size....... But a proper calculation is always better and of
course one has to assume that a crystal diffracts homogeneously, which
is not always the case.
To answer your question the transmission could be changed if the
collection is multiple position and not a continuous scan (ie the
crystal is not translated during a wedge). There are certain conditions
where this is advantageous and Sasha Popov's BEST strategy calculation
program has options to do this....
Best wishes, Matt.
On 2015-04-24 13:18, Mark J van Raaij wrote:
Hi Matthew,
William seems to want to increase the x-ray intensity gradually
during the experiment by augmenting the transmission gradually. It
that possible? If so, would it be advisable?
Mark J van Raaij
Dpto de Estructura de Macromoleculas
Centro Nacional de Biotecnologia - CSIC
c/Darwin 3
E-28049 Madrid, Spain
tel. (+34) 91 585 4616
http://www.cnb.csic.es/~mjvanraaij
On 24 Apr 2015, at 12:45, Matthew BOWLER wrote:
Dear William,
at the ESRF we have a Helical characterisation workflow that will
calculate a strategy based on the observed diffraction patterns and
the distance between 2 points selected on a crystal, best wishes,
Matt.
On 2015-04-24 12:00, William Chao wrote:
Dear all,
Does anyone have experience in maximising anomalous signal during a
helical/line scan? Most (all?) automated data collection strategies
in
synchrotrons seem to work on a single point of a crystal but don't
give strategies for line scan. Would it be advisable to increase
the
recommended transmission as radiation is spread along the crystal?
If
the strategy suggests us to use 10% transmission (100% = 2x10^11
ph/s)
for a 360-degree collection on a single point, to what amount
should I
increase say along a 200 micron scan with a 20 micron beam (crystal
dimension 200x100x20)?
Thank you very much in advance for the suggestions!
William
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Matthew Bowler
Synchrotron Diffraction Group
European Molecular Biology Laboratory
71, avenue des Martyrs
CS 90181
F-38042 GRENOBLE Cedex 9
FRANCE
France
===================================================
Tel: +33 (0) 4.76.20.76.37
Fax: +33 (0) 4.76.88.29.04
http://www.embl.fr/
===================================================
