Delayed nuclear radiation
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200297529
2008-03-23T13:59:59Z
SkyLined
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Replaced symbols and formulae using [[:Category:NuclideTemplates]]
'''Delayed nuclear radiation''' can occur in a [[nuclear decay]]. It happens when an [[isotope]] decays into a very short-lived isotope and then decays again to a relatively long-lived isotope. The short-lived isotope is usually a meta-stable [[nuclear isomer]].
For example, [[Gallium-73]] decays via [[beta decay]] into [[Germanium-73]]m which is very short-lived. The Germanium isotope emits two weak [[gamma ray]]s and a [[conversion electron]].
:{{Nuclide|Gallium|73}} → {{Nuclide|Germanium|73|m}} + 2{{SubatomicParticle|Gamma}} → {{Nuclide|Germanium|73|charge=+}} + 2{{SubatomicParticle|Gamma}} + {{SubatomicParticle|Electron}}
Because the middle isotope is so short-lived, the gamma rays are considered part of the Gallium decay. Therefore the above equation is simplified.
:{{Nuclide|Gallium|73}} → {{Nuclide|Germanium|73|charge=+}} + 4{{SubatomicParticle|Gamma}} + {{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 it is 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 [[nitrogen-17]] emits two beta-delayed [[neutron]]s after its primary beta emission. Just as in the above delayed gamma emission, the [[nitrogen]] is not the actual source of the neutrons, a short lived isotope of [[oxygen]] is.
==See also==
*[[Prompt neutron]]
{{nuclear-stub}}
[[category:Radioactivity]]
[[ko:지체 핵 방사]]