View source for Physics:Delayed nuclear radiation

'''Delayed nuclear radiation''' is a form of nuclear decay. When an [[Physics:Isotope|isotope]] decays into a very short-lived isotope and then decays again to a relatively long-lived isotope, the products of the second decay are delayed. The short-lived isotope is usually a meta-stable [[Physics:Nuclear isomer|nuclear isomer]].

For example, [[Physics:Gallium-73|gallium-73]] decays via [[Physics:Beta decay|beta decay]] into [[Physics:Germanium-73|germanium-73m2]], which is short-lived (499ms). The germanium isotope emits two weak [[Physics:Gamma ray|gamma ray]]s and a conversion electron.

:{{nuclide|Gallium|73}} → {{nuclide|Germanium|73|m2}} + 2{{SubatomicParticle|Gamma}} + {{SubatomicParticle|Electron}} ; {{nuclide|Germanium|73|m2}} → {{nuclide|Germanium|73|charge=+}} + {{SubatomicParticle|Gamma}}(53.4&nbsp;keV) + {{SubatomicParticle|Gamma}}(13.3&nbsp;keV) + {{SubatomicParticle|Electron}}

Because the middle isotope is so short-lived, the gamma rays are considered part of the gallium decay. Therefore, the above equations are combined.

:{{nuclide|Gallium|73}} → {{nuclide|Germanium|73|charge=+}} + 4{{SubatomicParticle|Gamma}} + 2{{SubatomicParticle|Electron}}

However, since there is a short time delay between the beta decay and the high energy gamma emissions and the third and fourth gamma rays, it is said that the lower energy gamma rays are ''delayed''.

Delayed gamma emissions are the most common form of delayed radiation, but are not the only form. It is common for the short-lived isotopes to have delayed emissions of various particles. In these cases, it is commonly called a ''beta-delayed'' emission. This is because the decay is delayed until a beta decay takes place. For instance, [[Physics:Nitrogen-17|nitrogen-17]] emits two beta-delayed [[Physics:Neutron|neutron]]s after its primary beta emission. Just as in the above delayed gamma emission, the [[Chemistry:Nitrogen|nitrogen]] is not the actual source of the neutrons, the source of the neurons is a short-lived isotope of [[Chemistry:Oxygen|oxygen]].

==See also==
*[[Physics:Prompt neutron|Prompt neutron]]

== External links ==
* [http://nagysandor.eu/AsimovTeka/BetaNeutron/index_en.html Flash animation of beta-delayed neutron emission]
* [http://nagysandor.eu/AsimovTeka/BetaProton/index_en.html Flash animation of beta-delayed proton emission]
* [http://nagysandor.eu/AsimovTeka/BetaAlpha/index_en.html Flash animation of beta-delayed alpha emission]

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[[Category:Radioactivity]]



{{Sourceattribution|Delayed nuclear radiation}}