$^{40}$K measurement to determine the total potassium content

Abstract

Total potassium concentration has been determined measuring the 1461 keV gamma-rays emitted during the $^{40}$K decay. Using KCl salt set of $^{40}$K sources were prepared as standards and were used to characterize a NaI(Tl) $\gamma $-ray spectrometer. To test the procedure two unknown sources were used, for these $^{40}$K mass were determined as well as the specific activity. The rate of change between the mass of K and the net count rate under the 1461 keV photopeak is constant, allowing determining the mass of K measuring the $\gamma $-ray emitted during $^{40}$K decay. Specific activity was approximately 31 Bq/g being consistent with values reported in literature.