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Cobalt-60 (60 Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2714 years. [ 3 ] [ 4 ] : 39 It is produced artificially in nuclear reactors . Deliberate industrial production depends on neutron activation of bulk samples of the monoisotopic and mononuclidic cobalt isotope 59
Naturally occurring cobalt, Co, consists of a single stable isotope, 59 Co (thus, cobalt is a mononuclidic element). Twenty-eight radioisotopes have been characterized; the most stable are 60 Co with a half-life of 5.2714 years, 57 Co (271.811 days), 56 Co (77.236 days), and 58 Co (70.844 days).
The truck, now contaminated by the cobalt-60, subsequently suffered a mechanical failure upon Sotelo's return from the junkyard and remained immobile near his home in Ciudad Juárez for 40 days. [4] Meanwhile, at the junkyard, the use of electromagnets for handling the scrap caused the cobalt-60 granules to spread throughout the yard.
A typical cobalt-60 capsule, comprising: (A) An international standard source holder (usually lead), (B) a retaining ring, and (C) a teletherapy "source" composed of (D) two nested stainless steel canisters welded to two (E) stainless steel lids surrounding an (F) internal shield (usually uranium metal or a tungsten alloy) that protects a (G) cylinder of radioactive source material.
Cobalt occurs naturally as only one stable isotope, cobalt-59. Cobalt-60 is a commercially important radioisotope, used as a radioactive tracer and for the production of high-energy gamma rays. Cobalt is also used in the petroleum industry as a catalyst when refining crude oil.
Scientists warn that if carbon dioxide and other greenhouse gas emissions continue to rise at their current rates, Earth’s temperatures could increase dramatically in future decades, leading to catastrophic and irreversible climate change. The 10 largest emitters produced about 26.4 gigatons of carbon dioxide in 2013.
A radiation accident occurred in Samut Prakan Province, Thailand in January–February 2000. The accident happened when an insecurely stored unlicensed cobalt-60 radiation source was recovered by scrap metal collectors who, together with a scrapyard worker, subsequently dismantled the container, unknowingly exposing themselves and others nearby to ionizing radiation.
The experiment monitored the decay of cobalt-60 (60 Co) atoms that were aligned by a uniform magnetic field (the polarizing field) and cooled to near absolute zero so that thermal motions did not ruin the alignment. [14] Cobalt-60 is an unstable isotope of cobalt that decays by beta decay to the stable isotope nickel-60 (60 Ni).