Determining the 40K radioactivity in rocks using x-ray spectrometryDetermining the 40K radioactivity in rocks using x-ray spectrometry Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2018-04-182017enIn this paper we propose an experimental method for the determination of potassium-40 (40K) radioactivity in commercial granite samples using x-ray fluorescence (XRF). The method correlates the total potassium concentration (yield) in samples deduced by XRF analysis with the radioactivity of the sample due to the 40K radionuclide. This method can be used in an undergraduate student laboratory. A brief theoretical background and description of the method, as well as some results and their interpretation, are presented. http://creativecommons.org/licenses/by/4.0/European Journal of Physics385 Pilakouta M. Kallithrakas-Kontos Nikolaos Καλλιθρακας-Κοντος Νικολαος Nikolaou G. Institute of Physics Publishing Granites Physics and chemistry education Potassium radioactivity XRF