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Most
diffraction data collected on the MacCHESS beamlines at CHESS consists
of images recorded by the oscillation method. A series of images is
collected, one at a time, on a 2-dimensional detector such as a CCD
detector or an imaging plate. These images must be processed to extract
the structure factor amplitudes which are needed for determining a
molecular structure. Although it is possible to just collect images at
CHESS and do all the processing later, we strongly recommend that users
process at least some of their data here, because: |
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data quality can
be quantitatively assessed, and bad data can be recollected (if time
permits);
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changes in space
group or cell parameters, which may necessitate changes in data
collection strategy, can be recognized;
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potential
derivatives can be screened, and data collected only on the useful ones;
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space limitations
on the home computer, tape drive incompatibility, etc. become
unimportant if final structure factors are produced and sent home by
FTP; raw images need only be backed up and taken home in case of
disaster. |
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For 2005, MacCHESS data collection
computers at each beamline have been replaced with Linux machines.
Additional Linux machines are located at each beamline for data
processing and backup. Also, Linux computers may be found in the
computer room, where two of the Linux machines (kaoline & opaline) are
equipped for 'stereo' graphical use. All MacCHESS data
collection/processing computers are linked via gigabit ethernet. The
Linux computers have a variety of data processing software (see below)
along with common crystallographic software including CCP4, Solve, pymol,
O and SnB.
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Apple Mac computers are stationed at F1
and in the computer room for data
backup. Currently the Macs do not have a lot of crystallographic
software.
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By early 2006 the remaining Alphas will
be phased out. Availability of tape
drives, which require SCSI interfaces, will be reduced as well. |
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The
following programs for processing oscillation data are installed at
CHESS: |
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HKL-2000, a new program package based on extended versions of
Denzo, Xdisplayf and Scalepack, is available on all the MacCHESS
computers for processing data from all the detectors used on stations
A-1, F-1, and F-2.
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HKL (xdisp/denzo/scalepack) can be used for data taken
with the ADSC Quantum-4 CCD, ADSC Quantum-210 CCD, or Fuji
imaging plates.
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The Interactive DPS/Mosflm/CCP4 package
can be used for data taken with the ADSC Quantum-4 (4-module) CCD
and ADSC Quantum-210 CCD.
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Mosflm
and CCP4, without the integrated
interface, can be used for data from any of the detectors at CHESS.
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