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Electron capture happens most often in the heavier neutron-deficient elements where the mass change is smallest and positron emission is not always possible. When the loss of mass in a nuclear reaction is greater than zero but less than 2m e c 2 the process cannot occur by positron emission, but occurs spontaneously for electron capture.
Positron emission should not be confused with electron emission or beta minus decay (β − decay), which occurs when a neutron turns into a proton and the nucleus emits an electron and an antineutrino. Positron emission is different from proton decay, the hypothetical decay of protons, not necessarily those bound with neutrons, not necessarily ...
Positron emission tomography (PET) [1] is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. Different tracers are used for various imaging ...
The electron capture detector is used for detecting electron-absorbing components (high electronegativity) such as halogenated compounds in the output stream of a gas chromatograph. The ECD uses a radioactive beta particle (electron) emitter in conjunction with a so-called makeup gas flowing through the detector chamber.
The electron or positron emissions are called beta particles. Beta decay either increases or decreases the atomic number of the nucleus by one. Electron capture is more common than positron emission, because it requires less energy. In this type of decay, an electron is absorbed by the nucleus, rather than a positron emitted from the nucleus.
If the mass difference between the mother and daughter atoms is more than two masses of an electron (1.022 MeV), the energy released in the process is enough to allow another mode of decay, called electron capture with positron emission. It occurs along with double electron capture, their branching ratio depending on nuclear properties.
In physics, electron emission is the ejection of an electron from the surface of matter, [1] or, in beta decay (β− decay), where a beta particle (a fast energetic electron or positron) is emitted from an atomic nucleus transforming the original nuclide to an isobar.
Its modes of decay are: 74.4% electron capture, 25.6% positron emission. 124 I decays to 124 Te. Iodine-124 can be made by numerous nuclear reactions via a cyclotron. The most common starting material used is 124 Te. Iodine-124 as the iodide salt can be used to directly image the thyroid using positron emission tomography (PET). [9]