Estimation of the mosaic spread and the mosaic-block size of zinc single-crystal spheres by simulations of ψ scans with UMWEG90

In a previous paper [Rossmanith (1992). Acta Cryst. A48, 596–610], new formulae for the Lorentz factor and peak width for single and multiple diffraction were given. These formulae are used in the program UMWEG90 for the calculation of ψ-scan simulations. In this paper, simulations are compared with five different ψ scans of two different zinc single-crystal spheres measured with Mo and Ag Kα radiations, respectively. It is shown that, by fitting the calculated to the measured ψ scans, consistent and physically significant parameters for the mosaic structure parameters – mosaic spread and mosaic block size – and for the divergence parameters of the X-ray beam are obtained. Moreover, it is shown that the parameters obtained from multiple-diffraction experiments are consistent with those resulting from single-diffraction experiments performed with synchrotron radiation.