Simulation of X-ray fluorescence and application to planetary astrophysics

In the last two years, in the context of the Geant4 toolkit, a package for the Monte Carlo simulation of atomic relaxation processes has been developed, and tested against experimental data. It includes models for the simulation of Auger electron and fluorescence photon emission. Results from a comparison with test beam data, presented here, show a very good statistical coincidence of the simulation and of experimental measurements. The package allows to fully exploit the power of other Geant4 components, such as geometry and materials modeling. This gives, for the first time, the chance of simulating fluorescence and Auger emission of complex material as rocks, whatever is the physical process inducing it, thanks to advanced object-oriented software techniques. Application results from the studies for the design of BepiColombo ESA mission to Mercury are presented.