A tunable monochromatic X-ray source for metrological studies in the 1-20 keV energy range: application to the measurement of attenuation coefficients.

A tunable monochromatic X-ray source operating in the 1-20 keV energy range is described. An X-ray tube provides initial photons. A dispersive crystal performs the energy selection, according to Bragg's law. An X-ray detector is connected to the monochromator fixed exit. This setup can be used for metrological studies. A first application consists in measuring attenuation coefficients in the 4-10 keV energy range. Results for aluminum and copper are given, with average relative uncertainties (1sigma) of 1% and 3% respectively.