PHOTON CROSS-SECTION DATA FROM X-RAY-DIFFRACTION PATTERN MEASUREMENTS- CORRECTION PROCEDURE EVALUATIONS

The feasibility of evaluating absolute differential cross-sections of coherently scattered X-rays by exploiting diffraction pattern measurem ents has been tested in the case of plastic and biological samples. Th e investigation takes into account three powder diffractometers with d ifferent irradiation facilities. The main relevant correction factors have been evaluated by means of Monte Carlo and computational algorith m approaches. A careful evaluation of the effect of nonmonochromatic i ncident photon beams allows this procedure to be valid without resorti ng to sophisticated irradiation facilities Moreover in comparing the e xperimental data with the theory, it is shown that some assumptions us ually made when calculating theoretical scattering cross-sections are not valid when a scattering angle ranging from forward to backscatteri ng values is to be considered. These results, together with other usua l instrumental corrections, permit us to evaluate the differential sca ttering cross-sections within acceptable uncertainties. (C) 1998 Elsev ier Science B.V. All rights reserved.