Monte Carlo simulation and fundamental quantities

Physics interaction models suited for Monte Carlo simulation of coupled electron- photon transport in EPMA and other spectroscopic techniques are briefly described. The considered models are required to be applicable to any material and valid for a wide energy range. Differential cross-sections, the fundamental quantities in Monte Carlo simulation, are presented for the relevant interactions of photons and electrons with energies up to about 500 keV. Approximations and simplifications underlying the interaction models and the particle tracking scheme are discussed. (paper)