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
>>> ---
>>>
>>> The Francis Crick Institute Limited is a registered charity in
>>> England and Wales no. 1140062 and a company registered in England
>>> and
>>> Wales no. 06885462, with its registered office at 215 Euston Road,
>>> London NW1 2BE.
>>
>> --
>> 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/
>> ===================================================
--
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/
===================================================
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