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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. Trace quantities also originate from spontaneous fission of uranium-238. It is ...
It is also not produced by nuclear weapons because 135 Cs is created by beta decay of original fission products only long after the nuclear explosion is over. 136 Cs also captures neutrons with a cross section of 13.00 barns, becoming medium-lived radioactive 137 Cs. Caesium-136 undergoes beta decay (β−), producing 136 Ba directly.
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 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 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.
A chart or table of nuclides maps the nuclear, or radioactive, behavior of nuclides, as it distinguishes the isotopes of an element.It contrasts with a periodic table, which only maps their chemical behavior, since isotopes (nuclides that are variants of the same element) do not differ chemically to any significant degree, with the exception of hydrogen.
Radioactive isotope table "lists ALL radioactive nuclei with a half-life greater than 1000 years", incorporated in the list above. The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys. C 45 030001. The PDF of this article lists the half-lives of all known radioactives nuclides.
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 ...