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Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha, beta, and gamma decay.
Spontaneous fission (SF) is a form of radioactive decay in which a heavy atomic nucleus splits into two or more lighter nuclei. In contrast to induced fission , there is no inciting particle to trigger the decay; it is a purely probabilistic process.
Spontaneous emission is the process in which a quantum mechanical system (such as a molecule, an atom or a subatomic particle) transits from an excited energy state to a lower energy state (e.g., its ground state) and emits a quantized amount of energy in the form of a photon.
In particle physics, particle decay is the spontaneous process of one unstable subatomic particle transforming into multiple other particles. The particles created in this process (the final state ) must each be less massive than the original, although the total mass of the system must be conserved.
Of these decay processes, only alpha decay (fission of a helium-4 nucleus) changes the atomic mass number (A) of the nucleus, and always decreases it by four. Because of this, almost any decay will result in a nucleus whose atomic mass number has the same residue mod 4. This divides the list of nuclides into four classes.
The decay energy is the mass difference Δm between the parent and the daughter atom and particles. It is equal to the energy of radiation E . If A is the radioactive activity , i.e. the number of transforming atoms per time, M the molar mass, then the radiation power P is:
Natural radioactivity is the spontaneous decay of the atoms of certain isotopes into other isotopes. If the resultant isotope is not stable, it undergoes further decay until a stable isotope forms. The decay process is usually accompanied by emissions of alpha, beta, and gamma radiation. Natural gamma ray radiation is one form of spontaneous ...
The second most common type of decay that americium-241 undergoes is spontaneous fission, with a branching ratio of 3.6×10 −12 [10] and happening 1.2 times a second per gram of 241 Am. It is written as such (the asterisk denotes an excited nucleus):