heavynucleus

A heavynucleus is a nucleus with a relatively large number of nucleons, typically found in the heavier part of the periodic table. In nuclear physics, heavynuclei are generally those with mass numbers well above iron (A > ~60) and include most actinide and transactinide elements. The term is used to distinguish heavynuclei from lighter and medium-mass nuclei in discussions of binding energy, stability, and decay.

Across the heavynucleus regime, binding energy per nucleon decreases with increasing mass number once past the peak near iron, so heavynuclei are, on average, less tightly bound than mid-mass nuclei. They often decay by alpha decay, beta decay, spontaneous fission, or combinations thereof. Nuclei near magic numbers can achieve relative stability; for example lead-208 (Z=82, N=126) is doubly magic and among the most stable heavynuclei. Many heavynuclei are deformed and exhibit collective excitations such as quadrupole or octupole shapes.

Production and study: Heavynuclei are produced in laboratories by fusion of heavy ions or by neutron capture in reactors. They are identified through decay chains, gamma spectroscopy, and mass measurements. Transuranic elements arise in reactor or accelerator experiments; superheavy elements are studied with hot- and cold-fusion methods, expanding the known elements up to oganesson (Z=118).

Significance and applications: Heavynuclei are central to nuclear energy, where fission of heavy isotopes powers reactors, and to astrophysical nucleosynthesis, where heavy nuclei are built in rapid neutron capture processes. They also test models of nuclear structure and the limits of stability. Ongoing research seeks to map the island of stability among superheavy nuclei and to understand deformation and decay pathways in the heavynucleus regime.