Chapter 3 – Radioactivity

This chapter focuses on radioactivity at both the nuclear level and for a collection of radioactive atoms, termed radionuclides or radioisotopes. Radioactivity is explained in terms of a neutron excess or deficiency. The various decay modes, such as electron capture, and the particles emitted are delineated, including alpha, beta, positron, neutrino and gamma ray. The half-life and principal radiations for important radionuclides are tabulated. The decay law is derived and its exponential solution provided from which the activity is obtained. Besides simple parent to daughter decay, more complex situations including radionuclide buildup, compound decay and decay chains are introduced.