Part III: Radioactive Decay

"The atoms of radioactive matter are, so to speak, unstable, and each is liable at any moment to shoot out the alpha ray with great velocity." — Ernest Rutherford, Radioactive Substances and their Radiations (1913)

Of the roughly 3,300 nuclides known to exist, only about 250 are stable. The rest decay — transforming themselves into different nuclides by emitting alpha particles, beta particles, gamma rays, or more exotic radiation. Radioactive decay is the clock by which we date the Earth and the universe, the mechanism by which nuclear medicine diagnoses and treats disease, the hazard that demands radiation protection, and one of the most beautiful demonstrations of quantum mechanics at work in nature.

In these five chapters, we develop radioactive decay from the fundamental physics. We begin with the statistical foundations: the exponential decay law, activity, half-life, and the Bateman equations that govern decay chains — with applications to radioactive dating and equilibrium. Alpha decay reveals quantum tunneling through the Coulomb barrier, one of the first triumphs of quantum mechanics (Gamow, 1928). Beta decay introduces the weak interaction and the neutrino, with Fermi's theory providing the framework and the Wu experiment demonstrating that nature distinguishes left from right. Gamma decay and internal conversion connect back to the electromagnetic transition theory of Chapter 9, with the Mössbauer effect as a stunning application of recoilless resonance absorption.

The final chapter of Part III bridges decay physics to detection: how alpha particles, beta particles, gamma rays, and neutrons interact with matter, and how we build detectors to observe them. This chapter is essential preparation for the experimental techniques discussed throughout the rest of the book.

Chapters in Part III: - Chapter 12: Radioactivity Fundamentals — decay law, activity, half-life, decay chains - Chapter 13: Alpha Decay — quantum tunneling through the Coulomb barrier - Chapter 14: Beta Decay — the weak interaction in the nucleus - Chapter 15: Gamma Decay and Internal Conversion - Chapter 16: Radiation Interactions with Matter — how we detect what nuclei do

Chapters in This Part

• Chapter 12 — Radioactivity Fundamentals: Decay Law, Activity, Half-Life, and Decay Chains
• Chapter 13 — Alpha Decay: Quantum Tunneling Through the Coulomb Barrier
• Chapter 14 — Beta Decay: The Weak Interaction in the Nucleus
• Chapter 15 — Gamma Decay and Internal Conversion: Nuclear De-Excitation
• Chapter 16 — Radiation Interactions with Matter: How We Detect What Nuclei Do