IPA, A PROGRAM FOR PROCESSING POWDER DIFFRACTION IMAGES Ken Lagarec and Serge Desgreniers, Département de physique, Université d'Ottawa, Ottawa, CANADA, K1N 6N5

We describe a program and the underlying algorithms for processing powder diffraction images recorded on phosphor imaging plates (currently digitized by the FUJI BAS2000 laser scanner). The code, written in object-oriented C++, takes advantage of the recent availability of inexpensive and fast PCs and runs under the widespread Windows graphical interface. In order to produce, as the final goal, a 2Q-profile usable for refinement (e.g. a Rietveld analysis), the program accomplishes four main tasks on a digitized image showing partially complete Debye traces: i. a simplified image manipulation (e.g. loading, zooming, contrast enhancement, artefact removal); ii. image center finding, sample-to- detector calibration and calibration of the orientation of the image plane with respect to the incident X-ray beam direction; iii. intensity integration along the Debye traces; iv. azimuthal intensity profile generation. Algorithms used for planar orientation calibration and integration are partially based on a method described by Piltz et al. [1]. As an example, we show a powder diffraction image of a mixed sample of HfO₂ (monoclinic)/Mo (bcc) loaded in a Merrill-Bassett diamond anvil cell recorded at CHESS D1: the 2Q-profile generated by IPA is excellent as ascertained by a full Rietveld analysis.

[1] Piltz, R. O., McMahon, M. I., Crain, J., Hatton, P. D., Nelmes, R. J., Cernik, R. J. and Busnell-Wye, G., Rev. Sci. Instrum. 63, 700 (1992).