Modelling diffractive X-ray scattering using the EGS Monte Carlo code

An extension to the EGSnrc Monte Carlo code has been developed that allows diffractive scattering to be modelled from both crystalline and amorphous materials. The extended code allows the user to specify cross-sections and form-factors for materials and implements the physics of scattering from powdered crystals and amorphous materials. A computer code has been developed to facilitate the calculation of the cross-sections and form-factors of materials containing mixtures of crystalline and amorphous components. A modified next-event point-flux tally estimator has also been developed as a variance reduction technique specifically for diffractive scattering from crystals. The extended EGSnrc code has been used to optimise the design of a prototype energy-dispersive X-ray diffraction spectrometer. Initial results show promising agreement between the energy spectrum of diffracted X-rays obtained using the Monte Carlo model and measured experimentally.