Positron emission

Jump to: navigation, search

Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [1] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.

Positron emission is a type of beta decay, sometimes referred to as "beta plus" (β+). In beta plus decay, a proton is converted, via the weak force, to a neutron, a positron (also known as the "beta plus particle", the antimatter counterpart of an electron), and a neutrino.

Isotopes which undergo this decay and thereby emit positrons include carbon-11, potassium-40, nitrogen-13, oxygen-15, fluorine-18, and iodine-121. As an example, the following equation describes the beta plus decay of carbon-11 to boron-11, emitting a positron β+ and a neutrino νe:

These isotopes are used in positron emission tomography, a technique used for medical imaging.

Nuclei which decay by positron emission may also decay by electron capture. For low-energy decays, electron capture is energetically favored by 2mec2 = 1.022 MeV, since the final state has an electron removed rather than a positron added. As the energy of the decay goes up, so does the branching ratio towards positron emission. However, if the energy difference is less than 2mec2, then positron emission cannot occur and electron capture is the sole decay mode. Certain isotopes (for instance, 7Be) are stable in galactic cosmic rays, because the electrons are stripped away and the decay energy is too small for positron emission.

ast:Emisión de positrones ms:Pemancaran positron ko:양전자 방출



Linked-in.jpg