Development of a Linear Fast Shutter for BM05 at ESRF and BEATS at SESAME
C. Muñoz Pequeño, J.M. Clement, P. Thevenau, P. Van Vaerenbergh
ESRF, Grenoble, France
This paper presents the design of a new linear fast shutter for topography and tomography. A prototype will be assembled and tested at the BM05 beamline at ESRF, and another unit will be installed in the future BEATS beamline at SESAME. The application of the shutter in X-ray diffraction topography allows performance of long exposure cycles of monochromatic beam on crystal samples while preventing irradiation of the detector during readout. It can be also used during sample alignment and acquisition of X-ray tomography scans. Particularly for white-beam tomography, which uses a very high photon flux, minimizing exposure is critical to protect the sample and detector from radiation damage. This highlights the importance of obtaining a short and uniform exposure time over the beam aperture. To fulfill this objective, a new shutter based on the synchronization of two tantalum blades driven by linear brushless DC motors is under development. This versatile design can be used with both monochromatic and white-beam, and it can achieve exposure times ranging from 50 ms to 60 s for a beam size of H 80 mm x V 20 mm. The linear motors allow for a much smoother operation, preventing vibration issues reported with the old shutter. In addition, the use of linear motors rather than solenoids allows an unlimited exposure time, where the previous version used solenoids that could overheat if kept open for too long. A test bench has been constructed for the characterization of the sequence produced by the linear motors, and exposure times of 50 ms with a maximum error of 1 ms have been measured. This article describes the main features of the shutter prototype and its associated motion control system, and the results of the measurements with the motor test bench are discussed as well.
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