Nuclear Decay and Radioactivity

Many nuclei with finite lifetimes are produced by nuclear reactions and/or nuclear decays, though the number of stable nuclei is limited to less than 300 if we call those nuclei whose lifetime is longer than or nearly equal to the age of the universe, i.e., about \(13.8\times 10^9\) years, as stable nuclei. Also, all the excited states of nuclei eventually decay into other nuclei via \(\alpha \) or \(\beta \) decay or fission, or make transitions to lower energy levels of the same nucleus by emitting \(\gamma \) rays. The decay called cluster decay or heavy particle decay or cluster radioactivity, where a nucleus decays by emitting a nucleus heavier than \(\alpha \) particle such as \(^{14}\)C, has also been actively studied since 1980s (see Rose and Jones, Nature, 307: 245 (1984), [1]). In 2000s, the study of one-proton and two-proton radioactivities of proton-rich nuclei has also become active (see Blank and Borge, Prog Part Nucl Phys, 60: 403 (2008); Blank and Ploszajczak Rep Prog Phys, 71: 046301 (2008), [2]). In this chapter we learn the \(\alpha \)-decay and electromagnetic transitions among the decay of nuclei and radioactivity. We also briefly discuss recent developments concerning fission.