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Beamtime available at CHESS, June 2 - July 20, 2010
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The CHESS/MacCHESS facility, located at Cornell University in Ithaca,
NY, invites macromolecular crystallographers and users of BioSAXS to
apply for time on one or more of our stations:
A1 station, monochromatic wiggler source, suitable for Se SAD
experiments as well as native data collection, with ADSC Q-210 detector.
F1 station, monochromatic wiggler source, suitable for Br SAD or native
data, with ADSC Q-270 detector and ALS-type automounter.
F2 station, wiggler source tunable from 7 - 14 keV, can be configured
either for MAD/SAD experiments, with ADSC Q-210 detector, or for BioSAXS
experiments, with ADSC Q-1 detector.
F3 station, bending magnet source with multilayer optics, tunable from
5.9 - 15.4 keV, suitable for SAD experiments using Fe, Co, etc., with
ADSC Q-4u detector.
G1 station, wiggler source with multilayer optics, general purpose
station one of whose standard configurations is for SAXS experiments;
good data can be obtained for d-spacings up to 2500 Angstroms.
===== Special options ======
Pressure-cryocooling of (unfrozen) crystals is available by
prearrangement. This method can reduce the damage induced by
cryocooling, often with no need for cryoprotectants (Kim et al., Acta
Cryst. D61, 881-890 (2005)).
Microbeam (down to about 5 microns) using focusing capillary optics is
available on request at any of the stations.
======= Support =======
CHESS/MacCHESS provides a high level of support for all users. We are
very willing to help with non-standard experimental setups - just ask.
Our staff scientists also invite collaborations for more extended
projects investigating novel techniques. Mail-in service is available -
we will be pleased to collect (and process, if you like) data from
crystals that you send to us.
======== Applying for time ========
Visit http://www.chess.cornell.edu and look at "Beam Time" under the
"Users" menu. All applications can be done on line, any time. Processing
of proposals is rapid, with a turn-around time of just a couple of weeks
for the usual Express Mode option.
More information is available on the web site, or contact administrator
Kathy Dedrick, [email protected].
============ Recent developments ====================
SAXS
----
F2 station continues to improve as a SAXS beamline. In this
configuration, the large Q210 detector has been replaced with a freshly
re-calibrated Q1 detector. This move was motivated by pedestal mismatch
and ghosting problems that made the Q210 a less-than-optimal detector
for SAXS. The Q1 was used very successfully for SAXS in G1 for a number
of years and should improve wide-angle data quality significantly at F2.
Søren Nielson has recently joined MacCHESS as a postdoc. He specialized
in BioSAXS and microfluidics ("lab on a chip") at the Technical
University of Denmark and is the author of the BioXTAS RAW data
processing program (J.App. Cryst. 42 pp 959-964 (2009)). During the
coming run, we expect to have fully customized and tested this software
for automated data processing on our SAXS beamlines. This
freely-available open-source code should also be valuable for those
processing SAXS data at home.
MacCHESS has purchased a pipetting robot for automated sample loading,
including preparation of dilution series. The robot will be tested on F2
and G1 during this run and may be available to selected users once
testing is complete. We also hope to test a basic SAXS flow cell. If
sufficient sample is available (30-50 ul), the use of a flow cell can
eliminate the effects of radiation damage and allow for dramatically
better signal-to-noise in data collection.
For more information on SAXS, contact Richard Gillilan, [email protected].
Pressure-cryocooling
--------------------
In 2009, pressure-cooling succeeded in increasing the success rate for
cryocooling users' crystals which had previously yielded only one good
"freeze" out of dozens or hundreds.
The option of pressure-cooling in capillaries is available for crystals
which are not compatible with oil coating, or are subject to mechanical
damage during loop mounting.
Reminder: pressure-cooling will not improve crystals that are bad at
room temperature; what it does is reduce damage on cryocooling. Please
verify that your crystals show acceptable diffraction at room
temperature before requesting pressure-cooling.
For more information on pressure-cryocooling, contact Chae Un Kim,
[email protected].
