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Re: [sdpd] Synchrotron powder diffraction
I agree with you that dedicated lines, such as Peter Stephens and yours
are more efficient for the general user. However, there is a place for
multi purpose lines, and particularly those on undulators, where often the
politics of funding and building the beamline (particularly at the APS)
forces the multi-purpose approach except for protein crystallography.
The setup time issue can be mitigated by judicious sequential scheduling
of powder diffraction experiments.
Another approach that we are looking into is to try to use one of the
dedicated protein crystallography lines at APS for powder diffraction
(specifically the IMCA-CAT line). The advantage being that the beam line
is already set up properly and the sample can just be popprd in.
However, the large 2D detectors usually present at such lines will not
give the high resolution that can be obtained with a flat crystal
analyzer.
That being said, it would be nice to have a dedicated powder diffraction
line at the APS (and we are working toward it) but even if it existed I
still might want to use the multi purpose line if my experiment is
particularly well-suited to its beam characteristics.
Cheers,
Carlo
On Sat, 8 Sep 2001, Lachlan Cranswick wrote:
>
>>I would echo this for the Advanced Photon Source, and in particular,
>>MR-CAT. We have the capability of doing high resolution PD at energies
>>from 10keV to 80keV. The hutch is not set up exclusively for this but is
>>easily reconfigured. MR-CAT is now accepting Independent Investigator
>>proposals through the APS User Office. Relevant links are
>>
>>http://www.aps.anl.gov
>>
>>http:/ixs.iit.edu/mrcat
>>
>>Carlo Segre, Deputy Director, MR-CAT
>
>How easy is "easy"? A common(?) folklore about "multi-use" synchrotron
>beamlines can be that the supposedly "routine" and "easy" setup can
>take from 1/2 to 2 days (or the entire beamtime allocation without
>working in a satisfactory manner) - where custom made, possibly neurotic
>equipment has to be jury rigged and aligned (while the minutes and
>hours of what users might hope would be productive beamtime slip away)
>
>--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
>
>Repeating a rant I have stated on previous occassions:
>
>A rival approach to this which seems to really pay dividends in
>"high reliability and high productivity synchrotron beamtime" is that
>taken by the 9.8 microcrystal single crystal beamline run by Simon Teat
>at Daresbury, UK lab. A "dedicated" beamline with an integrated piece
>of hardware based around a single commercial vendor (in this case a
>commodity Bruker Smart CCD diffractometer). Besides reliability and
>effeciency of beamtime, this has the advantage that if a user
>already know hows to use a laboratory SMART or similar system,
>they should not have difficulty immediately making effective use of 9.8.
>
> http://srs.dl.ac.uk/xrd/9.8/
>
>If the beam shines, users of 9.8 are pretty much guaranteed to collect
>very high quality, immediately analysable single crystal data (without
>the risks and frustrations associated with multi-use beamlines).
>
>--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
>
>Getting back to the general them of this thread:
>
>How many dedicated powder synchrotron beamlines exist that users of
>laboratory powder diffractometers can pretty much just start collecting
>high quality data (reliable - no thrills - 9.8 style) without the risks
>of time wasting and X-rays going spare associated with setting up
>and aligning non-dedicated equipment?
>
>Lachlan.
>
>-----------------------
>Lachlan M. D. Cranswick
>Collaborative Computational Project No 14 (CCP14)
> for Single Crystal and Powder Diffraction
> Birkbeck University of London and Daresbury Laboratory
>Postal Address: CCP14 - School of Crystallography,
> Birkbeck College,
> Malet Street, Bloomsbury,
> WC1E 7HX, London, UK
>Tel: (+44) 020 7631 6849 Fax: (+44) 020 7631 6803
>E-mail: l.m.d.cranswick...@dl.ac.uk
>WWW: http://www.ccp14.ac.uk
>
>
>
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
--
Carlo U. Segre -- Professor of Physics
Illinois Institute of Technology
Voice: 312.567.3498 Fax: 312.567.3494
Carlo.Segre...@iit.edu http://www.iit.edu/~segre
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