fissioni

Fissioni, commonly translated as fission, is the process by which a heavy atomic nucleus splits into lighter nuclei. The term is used principally in nuclear physics and, in biology, to describe a form of asexual reproduction in certain single-celled organisms. In nuclear fission, a nucleus such as uranium-235 or plutonium-239 absorbs a neutron, becomes unstable, and divides into two (often unequal) fragments, releasing energy and additional neutrons. These neutrons can trigger further fissions in surrounding nuclei, potentially producing a self-sustaining chain reaction. Fission can be induced, by neutron capture, or spontaneous, though spontaneous fission is relatively rare. The energy released per fission and the distribution of fission products drive both electricity generation in nuclear reactors and the potential destructive yield of nuclear weapons. Fission products are typically lighter, often radioactive isotopes with varying half-lives, and their decay contributes to heat and radiological concerns.

In biology, binary fission is a simple asexual reproductive mechanism used by many prokaryotes, including bacteria and archaea. The organism duplicates its genetic material and divides into two daughter cells, a process coordinated by a set of proteins that regulate DNA replication and cell division.

The discovery of nuclear fission occurred in the late 1930s, with experimental work by Otto Hahn and Fritz Strassmann and subsequent theoretical explanation by Lise Meitner and Otto Frisch, which established fission as a central topic in physics and technology.