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Caesium is a relatively rare element, estimated to average 3 parts per million in the Earth's crust. [65] It is the 45th most abundant element and 36th among the metals. [66] Caesium is 30 times less abundant than rubidium, with which it is closely associated, chemically. [14]
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.
A caesium atomic fountain used as part of an atomic clock. The caesium standard is a primary frequency standard in which the photon absorption by transitions between the two hyperfine ground states of caesium-133 atoms is used to control the output frequency.
Caesium-135 is a mildly radioactive isotope of caesium with a half-life of 1.33 million years. It decays via emission of a low-energy beta particle into the stable isotope barium-135. Caesium-135 is one of the seven long-lived fission products and the only alkaline one.
The radiation source in the Goiânia accident was a small capsule containing about 93 grams (3.3 oz) of highly radioactive caesium chloride (a caesium salt made with a radioisotope, caesium-137) encased in a shielding canister made of lead and steel. The source was positioned in a container of the wheel type, where the wheel turns inside the ...
Caesium iodide or cesium iodide (chemical formula CsI) is the ionic compound of caesium and iodine. It is often used as the input phosphor of an X-ray image intensifier tube found in fluoroscopy equipment. Caesium iodide photocathodes are highly efficient at extreme ultraviolet wavelengths. [7]
Caesium standards are therefore regarded as primary time and frequency standards. Caesium clocks include the NIST-F1 clock, developed in 1999, and the NIST-F2 clock, developed in 2013. [63] [64] Caesium has several properties that make it a good choice for an atomic clock.
Caesium carbonate; Caesium chloride; Caesium chromate; Caesium cyanide; Caesium dibismuthide; Caesium dodecaborate; Caesium enneabromodibismuthate; Caesium fluoride; Caesium fluoroaluminate; Caesium heptafluoroxenate; Caesium hexafluorocobaltate(IV) Caesium hexafluorocuprate(IV) Caesium hydride; Caesium hydroxide; Caesium iodide; Caesium ...