Zerfallsklassen

Zerfallsklassen, or decay classes, is a conceptual framework used in nuclear physics to categorize unstable nuclei according to their decay properties. The idea is to group nuclei not only by their element and mass but by the characteristic pathways through which they release energy and transform into daughters.

Classes are typically defined by factors such as the dominant decay mode (alpha decay, beta minus decay, beta plus decay or electron capture, gamma emission, cluster decay, or spontaneous fission), the associated branching ratios, and the observable features of the decay (emitted particles, energy spectra, and half-life). Additional criteria may include the spin and parity of the initial and final states and the conservation rules that govern the transition.

In practice, Zerfallsklassen serve as a heuristic to organize nuclear data and to simplify modeling of decay chains in simulations and astrophysical or reactor contexts. They are not static categories, because a nucleus can exhibit multiple decay channels with different probabilities, and environmental factors can influence decay paths in certain exotic cases.

Typical classes might include alpha-emitters, beta-minus emitters, beta-plus/electron-capture dominated decays, gamma-isomeric transitions, and spontaneous fission processes. Cluster decay and multifold beta decays are discussed as more specialized or rare classes. The concept is used in data compilations and evaluations to help users navigate decay schemes and to build reaction networks.

Zerfallsklassen reflects German terminology for decay classification; in international literature the same idea is usually described with phrases like decay modes or branching classifications. See also nuclear decay, radioactive decay, half-life, decay chain, nuclear data.