Journal of Applied Crystallography

Volume 46, Part 4 (August 2013)


research papers



J. Appl. Cryst. (2013). 46, 1058-1063    [ doi:10.1107/S0021889813013824 ]

A scanning CCD detector for powder diffraction measurements

B. H. Toby, T. J. Madden, M. R. Suchomel, J. D. Baldwin and R. B. Von Dreele

Abstract: Several different approaches have traditionally been used for detection of X-ray powder diffraction patterns, including area detectors, point detectors and position-sensitive detectors. Each has advantages. This paper discusses use of a low-cost CCD detector attached to a diffractometer arm, where line-by-line readout of the CCD is coupled to continuous motion of the arm. When this type of detector is used and where X-ray optics are employed to focus the source image onto the detector plane both high-resolution and rapid measurements can be performed, with data collection over a complete 2[theta] range. This is particularly advantageous for synchrotron applications but valuable also for Guinier diffractometer laboratory instruments. Peak resolutions are shown to be moderately better than what can be obtained with a position-sensitive detector and significantly better than with an area detector. Many samples have intrinsically broadened peak shapes for which little improvement in data quality could be obtained with an analyzer-crystal detector. With comparable numbers of modules, these CCD data collection speeds can be close to those with position-sensitive detectors, but without the low-angle asymmetry seen in the latter.

Keywords: powder diffraction; high resolution; area detection; CCDs; synchrotron instrumentation; Guinier diffractometer.


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[ doi:10.1107/S0021889813013824/he5600sup1.pdf ]
Appendix: Scanning CCD implementation details


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