The Radioactive Isotope of Potassium

Abstract

By means of a high intensity mass spectrometer we have separated the three isotopes of potassium. Measurements of the radioactivity of the isotopic samples indicate that ${\mathrm{K}}^{40}$ is radioactive. Comparison of the beta-particle emission from the isotopic samples and from KCl shows that ${\mathrm{K}}^{40}$ is responsible for both of the known beta-ray bands.