Radioactive Decay Chain

A heavy nucleus walks a decay series to stable lead. The primary scene is the physical nucleus, protons and neutrons packed and intermixed, transmuting each step: alpha decay sheds a He-4 cluster ($Z-2, N-2$), beta-minus turns a neutron into a proton ($Z+1, N-1$). The $Q$ value comes from the Bethe-Weizsaecker semi-empirical mass formula and the alpha half-life from the Geiger-Nuttall law. The side panel is the Segre chart tracing the path from the parent to the stable endpoint (Pb-206 for U-238, Pb-208 for Th-232).