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Caesium-137 (137 55 Cs ), cesium-137 (US), [ 7 ] or radiocaesium , is a radioactive isotope of caesium that is formed as one of the more common fission products by the nuclear fission of uranium-235 and other fissionable isotopes in nuclear reactors and nuclear weapons .
Decay Scheme of Caesium-137. Based on a public domain image by Kieran Maher (see original image) Date: 31 August 2006: Source: Own work: Author: Dirk Hünniger: Other versions: Derivative works of this file: Caesium-137 Decay Scheme-de-2.svg
The decay scheme of a radioactive substance is a graphical presentation of all the transitions occurring in a decay, and of their relationships. Examples are shown below. It is useful to think of the decay scheme as placed in a coordinate system, where the vertical axis is energy, increasing from bottom to top, and the horizontal axis is the proton number, increasing from left to right.
The low decay energy, lack of gamma radiation, and long half-life of 135 Cs make this isotope much less hazardous than 137 Cs or 134 Cs. Its precursor 135 Xe has a high fission product yield (e.g., 6.3333% for 235 U and thermal neutrons ) but also has the highest known thermal neutron capture cross section of any nuclide.
As caesium 133, 135, and 137 are formed by the beta particle decay of the corresponding xenon isotopes, this causes the caesium to become physically separated from the bulk of the uranium oxide fuel. Because 135 Xe is a potent nuclear poison with the largest cross section for thermal neutron absorption, the buildup of 135 Xe in the fuel inside ...
The accompanying decay scheme diagram shows the beta decay of caesium-137. 137 Cs is noted for a characteristic gamma peak at 661 keV, but this is actually emitted by the daughter radionuclide 137m Ba. The diagram shows the type and energy of the emitted radiation, its relative abundance, and the daughter nuclides after decay.
The following other wikis use this file: Usage on ar.wikipedia.org سيزيوم; Usage on be.wikipedia.org Цэзій-137; Usage on bn.wikipedia.org
Caesium-137 is one such radionuclide. It has a half-life of 30 years, and decays by beta decay without gamma ray emission to a metastable state of barium-137 (137m Ba). Barium-137m has a half-life of a 2.6 minutes and is responsible for all of the gamma ray emission in this decay sequence. The ground state of barium-137 is stable.