Nuclear fission primarily refers to the process by which a heavy nucleus splits into two or more smaller nuclei, along with the release of energy, neutrons, and gamma radiation. However, there are also several types of decay processes that can be related to the broader context of nuclear reactions but are not typically classified directly as "nuclear fission."
In nuclear physics, the types of decay processes generally discussed are:
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Alpha Decay: In alpha decay, an unstable nucleus releases an alpha particle (two protons and two neutrons), resulting in a new nucleus with a lower atomic number. While this process doesn't involve fission of the nucleus into two separate heavy nuclei, it does involve the emission of particles from the nucleus.
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Beta Decay: In beta decay, a neutron in an unstable nucleus is transformed into a proton (or vice versa), resulting in the emission of a beta particle (an electron or positron). This process changes the composition of the nucleus but does not involve the splitting of the nucleus as in fission.
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Spontaneous Fission: This is a specific form of nuclear fission in which a heavy nucleus splits into lighter nuclei without external influence, such as neutron absorption. It occurs in very heavy elements, like uranium-238 and californium-252, and is a rare form of decay compared to induced fission, which occurs when a heavy nucleus absorbs a neutron.
While these processes are related to nuclear reactions, it's important to note that fission is generally distinct from alpha and beta decay in terms of the mechanisms involved. If you're specifically looking for forms of nuclear fission, spontaneous fission and induced fission (which occurs when a nucleus is bombarded with neutrons) would be the two main categories, along with the broader classification of fission processes.