NECAT Beamline

The Northeastern Collaborative Access Team (NE-CAT) facility at the Advanced Photon Source at Argonne National Laboratory is managed by Cornell University and consists of seven member institutions:

  • Columbia University
  • Cornell University
  • Harvard University
  • Memorial Sloan-Kettering Cancer Center
  • Massachusetts Institute of Technology
  • Rockefeller University
  • Yale University.

    • Primary funding for this project comes from the National Center for Research Resources (NCRR), a division of the National Institutes of Health (NIH). Additional financial support for NE-CAT comes from the member institutions.

    Status of NE-CAT Sector 24 Activities

     

    October 2007  

     

    Sector 24 ID-C Beam Line

      APS user operations resumed on October 2 after a one month long shut down for accelerator preventive maintenance. The variable-energy insertion-device beam line 24-ID-C is already heavily booked for the entire 2007-3 APS run cycle by NE- CAT members and General Resource Users.

    A new feature has been successfully tested and added to the 24-ID-C beam line controls. Now when users change energy, the control software will automatically insure that the beam position remains constant, based on a previously measured steering function. The steering function is generated automatically with minimum intervention from the user.

    A growing number of our users have requested that a sample placement robot be available for their use. We are now re-engineering the ALS robot previously used at 8-BM to be installed on 24-ID-C. This re-engineering entails changing the “handedness” of the robot, i.e., looking downstream with the beam, the robot orientation is being reversed from being on the right hand of the goniometry to the left hand in order to be compatible with the location of the goniometry on 24-ID-C.

     

    Sector 24 ID-E Beam Line

    The fixed-energy insertion-device beam line 24-ID- E has been in commissioning studies for a number of months as well as the MD-2 micro-diffractometer now mounted on this beam line. Through these commissioning studies, the beam line has been proven to be very stable and highly reliable. Also, our staff’s commissioning of the MD-2 as well as commissioning activities conducted by NE- CAT members and General Resource Users have clearly demonstrated that the MD-2 is a most important instrument for conduct of experiments with very small, < 20 micron, crystals. With these commissioning experiments successfully concluded, NE- CAT has formally declared to APS that the 24-ID-E beam line and the MD-2 are fully operational. With this declaration, the 24-ID-E beam line will be fully open to NE- CAT members and General Resource Users for the 2008-1 run cycle beginning in February 2008, with 50% of its usage to be allocated to General Resource Users.

    The energy calibration for this beam line has been verified again to be accurate to within 1 ev.

    In order to circumvent the radiation damage problem, users have been successfully rastering the micro-beam across a single crystal or using multiple crystals to obtain complete data sets. Although successful, users are finding manual merging of data sets to be laborious. We now are near to finishing development of a software package to automatically merge together partial data sets to create complete data sets.

    We are engaged in a collaborative program with Lawrence Berkeley National Laboratory and ALS to develop a next generation sample placement robotics system to be installed on 24-ID-E. This new robotic system consists of a gantry type system consisting of a motorized XYZ Cartesian stage consisting of three SmartModules from Adept Technology. This stage is equipped with absolute encoders for error-free initialization and control through software rather than reliance of mechanical shims and clamps as in the case of the original robot design. The new design also eliminates use of all pneumatic controls. Models and a photograph of the prototype robot (courtesy of ALS) are shown below.

     

     

     

     

    Malcolm Capel visited ALS this month to work out the many needed design features specific to 24-ID-E. A 3-D computer model of the new robot system to be located at 24-ID-E is now being developed by our ALS collaborators to insure the robot’s operation will be compatible with the limited foot print at our beam line- before fabrication begins.

     

    CCD- Based Detectors, the NE- CAT Quantum 315 Detectors

     Beam lines, such as those of NE- CAT, with heavy investments in large-area tapered fiber-optic CCD based detectors are continually trying to improve the performance of these detectors. Several most recent presentations have shown that the quality of response of fiber-optic tapers used in these CCD-based detectors is degraded at the corners of each module - which can affect the quality of data. An example of this effect for one of our ADSC Quantum 315 detectors is shown in the figure below.

     

     

    In this figure, we have selected those events which are “rejects” in the data analysis. Clearly, it can be seen that the preponderant amount of rejects occurs at the corners of the individual taper fiber optics modules. This is due to non-uniformaties introduced in pulling the tapered fiber optics during manufacture, leading to increased point spread function and other detrimental effects at the outer perimeters of the glass tapers. Although the number of rejects is small and for most cases this effect does not substantially affect data quality, for some specific cases (e.g., very small mosaicity crystals) it can have a negative effect. We are currently working with ADSC to develop a correction algorithm to correct for this effect and improve the quality of data that can be obtained using our ADSC Quantum 315 Detectors.

     

     

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