Reality → Energy → Nuclear energy → Decay
The decomposition of atomic nuclei into lighter fractions is a naturally occurring process that cannot be influenced by any external action. Quantum mechanics postulate that it is impossible to predict the decay of a single nucleus; however, the decay of a substance (composed of a huge number of atoms) follows an exponential law of great accuracy [1] . Based on lab experiments, the decay formula allows accurate prediction of the timeline of nuclear decay, described by the constant of half-life, an isotope-specific parameter that can be much shorter than an attosecond and much longer than the age of the universe [2] . Alpha decay occurs only with heavy nuclei (atomic mass >200) [3] . Because 2 protons and 2 neutrons are emitted, the atomic number is reduced by 2 and the atomic mass by 4. Beta decay occurs with relatively neutron-rich nuclei when a neutron is transformed into a proton, an electron, and an antineutrino. As a result, the atomic number increases by 1 [4] . Gamma radiation accompanies alpha and beta decay, caused by the transition of the excited nucleus to a stable energy level.
Half-life is the time it takes for half the number of nuclei to decay (it can be deduced from plotting radiation activity over time). According to a Wikipedia list, some artificially created nuclei may have half-lives shorter than 10-21 second (i.e., a thousandth attosecond), while the nuclei of some stable natural elements may have half-lives longer than 1021 years (i.e., trillion times the age of the universe).
Alpha decay is dominating in three naturally occurring decay chains (two uranium chains and one thorium chain) that result in three different lead isotopes.
The increase in atomic number occurs in beta minus decay, which is much more common than beta plus decay. In beta minus decay, one of the neutron's two down quarks emits a (virtual) W- boson, which immediately decomposes into an electron and an antineutrino (occurs if an unstable isotope’s nucleus has a neutron surplus). In beta plus decay, which converts a proton into a neutron, one of the proton’s two up quarks emits a W+ boson, which immediately decomposes into a positron and a neutrino (occurs if an unstable isotope’s nucleus has a neutron deficit).