19.1: Discovery of Radioactivity 19.2: Nuclear Decay Processes 19.3: Detection of Radioactivity Radioactivity is determined by measuring the number of decay processes per unit time. Perhaps the easiest way is simply to determine the number of counts/minute, with each count measuring a single decay process, such as the emission of an αα -particle. A particular isotope may have an activity of 5,000 counts/minute (cpm) while another isotope might only have 250cpm. The amount of activity gives a rough indication of the amount of the radioisotope present. 19.4: Half-Life Half-life is defined. Calculations involving half-life are described. 19.5: Background Radiation 19.6: Nuclear Fission Processes 19.7: Nuclear Power Generation 19.8: Nuclear Fusion 19.9: Penetrating Ability of Emissions 19.10: Effects of Radiation 19.11: Radioisotopes in Medical Diagnosis and Treatment 19.12: PET Scans Template:HideTOC