Parametrization of a tabletop micro-XRF system

A table-top micro X-ray fluorescence apparatus composed of a conventional X-ray tube with a polycapillary lens and a silicon drift X-ray detector was parametrized according to an independent parameter approach. The tube bremsstrahlung spectrum was calculated from the Bethe-Heitler equation, convoluted by the energy distribution of radiating electrons in the target. In this paper, we propose a simple analytical approximation for this energy distribution. An analytical approximation is also proposed for transmission of the lens composed of curved capillaries.