Radioactive decay Auger electron

The most widely used radioactive tag in RIA is iodine 125. Iodine 125 decays by electron capture. It emits a single gamma ray having an energy of 35.48 keV. Four tellurium K x-rays with energies between 27.5 and 31.8 keV are also emitted. In addition there are L and M x-rays with energies of about 4 and 0.5 keV, respectively, as well as a variety of conversion and Auger electrons. Measurement of these relatively weak photons by... 

The electron capture process is followed by X-ray and/or Auger electron emission, in which the vacancy in the atomic shell is filled up with an electron from an external shell. As a consequence of the interaction between the nucleus and the electron or positron, a very weak electromagnetic radiation of continuous wavelength distribution (called internal brems-strahlung) is also always present in the radioactive P and EC decay (Petterson 1965). 

As a common consequence of any interaction of nuclear radiation with matter, electron vacancies are created in the K, L, M shells of the atoms. Radioactive decay can also create vacancies in the daughter atoms (electron capture, internal conversion). Electron vacancies can cause X-ray transitions or - as shown by Auger (1925) - the vacancy is filled at the expense of a shell electron emission with the energy... 

Generator-derived therapeutic radionuclides have a number of characteristic decay processes, and can emit P particles. Auger electrons, low-energy photons, and a particles. Since many therapeutic radionuclides are characterized by P decay, they are often directly produced in a nuclear reactor, since neutron capture by the target nuclide forms a radioactive or unstable product that decays by P emission. Key examples of therapeutic radionuclides obtained from reactor-produced parent radionuclides include Ho - from the Dy/ Ho generator, and Re - from the W/ Re generator. 

The most common type of source for Fe Mossbauer spectroscopy consists of elemental Co incorporated into a host metal lattice such as rhodium or copper. In the case of Sn measurements, " Sn-enriched CaSnOa or BaSnOa is used as a source. Schematic diagrams of the radioactive decay schemes for these two isotopes are shown in Figure 5. In addition to these transitions, internal conversion processes may give rise to emission of radiation of other energies. For example, in the case of Fe, the / = state may decay via the ejection of a X-shell 7.3-keV electron, and the hole created be filled by an L-shell electron, leading to the emission of either a 6.4-keV electron (Auger process) or X-ray in order to conserve energy. 

Comprehensive theoretical calculations of radiative transition rates as well as Auger and Coster-Kronig transition rates are available. However, uncertainties are large for Coster-Kronig transitions with small excess energy due to the strong influence of several effects (i) many-body interactions in the initial and final atomic systems, (ii) relaxation in the final ionic state, and (iii) exchange interaction between the continuum electron and the final bound-state electrons. For an experimental determination of decay rates, various techniques have been employed, e.g., the use of radioactive sources or coincidence techniques. Most techniques... 

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