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New ADSC
Q-270 detector at the F1 station |
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A new ADSC
Q-270 detector is now available for use at the F1 station. This
is the latest development from ADSC; it utilizes a new low-noise
CCD chip for improved performance with weakly diffracting
crystals. As its name implies, the Q-270 has an active area 270
mm square, over 50% larger than the Q-210 detectors installed at
A1 and F2. In pixels, the dimensions are 4168 x 4168 (2084 x
2084 in binned mode). The readout time is about 1 second,
similar to the Q-210 and considerably faster than the older Q-4,
which was previously the only type of detector available at F1.
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In testing at
CHESS, data from the Q-270 were similar in overall quality to
data from other ADSC detectors, perhaps a little better for weak
reflections. Data are readily processed with HKL2000 and denzo, DPS, mosflm, or XDS. Users at F1 can
choose to use either the Q-270 or one or both Q-4's; switchover
is quick and easy. |
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Marian Szebenyi
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Recent improvements have
made it possible to collect better data,faster at the F2 station: |
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Flux down the collimator has been
improved, particularly at low energies, by installation of a
longer in-vacuum focusing mirror, removal of some absorbers in
the beam upstream of the hutch, and replacement of the beam pipe
in the hutch with a helium-filled, better shielded, model. A
group that recently collected data at the Zn edge (9.6 KeV)
reported a 20-30% improvement in X-ray intensity over an earlier
visit. Another group was able to get sufficient anomalous signal
at 7.1 KeV to successfully perform sulfur SAD phasing. At the
optimum energy of about 13 KeV, high quality monochromatic data
may be collected, albeit with
exposure times longer than those for A1 or F1.
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Energy drifts have been reduced,
due to increased beam stability in the present filling mode and
to better thermal control for monochromator box components. New
software makes it easier to perform energy calibrations when
needed.
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Data collection facilities are on
a par with the A1 and F1 stations: the goniostat incorporates an
air bearing to allow rapid, precise spindle rotation, the X-ray
detector is an ADSC Q-210 CCD with 1-second readout time, a
convenient and reliable crystal centering system is in
place, and new Opteron computers with a 2 TB RAID system
attached are used for data collection and processing. A variety
of phasing and structure solution programs are available. |
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Marian Szebenyi
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CHESS to operate as a dedicated source |
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Starting from 2003, all x-ray operations at CHESS run in a fully
dedicated mode. This has numerous advantages for macromolecular
users, including long fills, brighter beams and improved beam
stability. |
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Time is
open for both new and existing users on the macromolecular ID
beamlines. Time is awarded based on peer review of the proposed
science, with short Express Mode proposals and rapid review
available along with traditional Program Proposals. |
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Proprietary review is possible for industrial users, or others,
concerned about privacy. We strive to be accessible to groups
that are new to CHESS, especially investigators that have not
yet benefited from the MacCHESS facility. |
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We now
have a crystallographically trained staff available to help all
macromolecular users with data collection and structure
determination. |
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Because
of the high cost to travel to Ithaca, we will consider providing
the data collection service in limited cases, where the user
only ships the samples. Please contact me if you are interested. |
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Quan Hao
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Current station CCD configuration |
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MacCHESS data
collection computers at each beamline have been replaced with
Linux machines. An additional two Linux machines are located at each beamline for data processing and
backup. More Linux computers and Alphas 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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David
Schuller
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HKL2000, a graphical interface to
Denzo, XdisplayF, Scalepack, and associated routines, is
available, through a collaborative arrangement with HKL
Research, on all the MacCHESS computers. All detectors in use on
MacCHESS beamlines are supported. |
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DPS/mosflm/CCP4,
version 2.03, for all detectors at CHESS. A tutorial on running
this package is available in the "Processing data" section of
these web pages. |
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Marian Szebenyi
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All
macromolecular stations have been equipped with new Cryostreams
700 series from Oxford Cryosystems
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The temperature is
usually set to 100 K, but can be varied from 80 K to 400 K. The
systems can be programmed to cool down or warm up with a
specific gradient, reach certain set points and hold these for a
certain amount of time. The cold gas flow is variable and can be
set to either 5 or 10 L/min (turbo mode). For temperatures below
100 K the system automatically adjusts the flow to 10 L/min, for
temperatures above 100 K a flow of 5L/min is sufficient to
maintain the temperature within 0.1 K. The cold gas flow can be
positioned in many different ways, from vertical to horizontal.
Accurate alignment is being done using the three positioners at
the support stand with the aid of a nozzle alignment tool. |
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Ulrich
Englich
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Each data collection machine has
a 2 TB RAID array attached.(/A1a, /F1a, /F2a). Data should be
written to the RAID array if possible for best capacity and
performance. Additional disks and a spare RAID array are
available in case of emergencies, and should be kept clear in
case their use is needed. |
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Users are welcome to bring their
own laptop or other computers to CHESS for data processing and
backup. IP addresses can be set up easily with DHCP, and static
addresses are also available. |
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MacCHESS supports IEEE 1394
(FireWire) and USB 2.0 connections on Mac and Linux. These
interfaces are also available on Windows machines supported by
CHESS. The Macs (macmac in the computer room and tarmac at F1)
also support FireWire 800 (IEEE 1394b) as does the Linux machine
kaoline in the computer room. |
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Data can be transferred from
CHESS to your home lab over the network.
CHESS/MacCHESS is connected to the Cornell campus network via
gigabit ethernet. Transfer speed to your home lab will vary from
case to case. CHESS has a firewall, so connections to CHESS from
outside are difficult. Consult your staff scientist if incoming
connections are necessary. |
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Tape drives are still available;
please contact MacCHESS in advance if you wish to use any of
these tape formats: 8mm (Exabyte 8500), 4mm (DDS 1-4), DLT4000,
Ultrium. |
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For a more detailed description
of data backup and transport, see Dave
Schuller's web page on bringing your data home
http://staff.chess.cornell.edu/~schuller/backup.html |
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David
Schuller
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Each
beam line has an 8mm tape drive and a 4mm DAT tape drive.
Additional 8mm and 4mm tape drives are located in the computer
room, along with a DLT4000 drive (lowerdec) and an Ultrium drive
(flightdec). Bring your own tapes. If you need extras, the CHESS
stockroom carries 8mm tapes and DDS-1 and DDS-3 4mm tapes. |
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supported tape formats: |
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capacity |
transfer rate (uncompressed) |
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| 8mm |
Exabyte 8500 |
5
GB |
0.5
MB/s |
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| 4mm
DAT |
DDS-2 |
4
GB |
<0.5 MB/s |
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DDS-3 |
12
GB |
1
MB/s |
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DDS-4 |
20
GB |
3
MB/s |
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| DLT
(Digital Linear Tape) |
DLT
4000 |
20
GB |
1.5
MB/s |
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Ultrium |
100
GB |
16
MB/s |
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MacCHESS
still has older drives which handle the Exabyte 8200 8mm and
DDS-1 4mm formats, but these will be unsupported (i.e. if they
break we may not fix them). |
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David Schuller
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