The Limits of Beta-Stability

The beta-stable nuclides are plotted in such a manner as to indicate the charge of maximum stability for odd mass numbers and the upper and lower limits of beta-stability for even mass and charge numbers. Curves representing these three quantities are drawn in following considerations based on the liquid-drop nuclear model, by which their positions can be determined fairly closely. The spacing between the curves is related to the parameters of the empirical mass equation of Bohr and Wheeler. The diagram is used to indicate the possibility of undetected natural radioactivities, and to suggest possible undiscovered or "missing" beta-stable nuclides.