SHAPE - A COMPUTER-SIMULATION OF ENERGY-DISPERSIVE X-RAY-SPECTRA

The energy-dispersive x-ray spectrum is composed of a number of discrete XRF lines overlapping with a background which is due to processes of multiple scattering; both are modulated by the complex response function of the detector. Several physical processes contribute to the emission of x-rays. Under the isolated atoms assumption, the main interactions to be considered are the Rayleigh and Compton scattering and the photoelectric effect. All of these processes taken independently produce well defined and theoretically valuable contributions. Recently, the most important of the multiple scattering contributions involving these interactions have been established analytically in the framework of the transport theory. The two kinds of contributions together give a more detailed physical picture of an x-ray spectrum and make possible a closer comparison with experimental data. The SHARPE code uses this theoretical basis to simulate a complex x-ray spectrum, giving the capability of making a complete characterization of every contribution. The theoretical spectrum may be optionally processed by a routine that simulates the response function of a solid-state detector to produce a multi-channel-like output. Moreover, a graphic interface has been built in the program to allow the identification of the relative importances of the different processes and multiple scattering in every part of the spectrum with direct reading.