Cobalt radioactive isotopes

A number of artificial radionuclides are produced as a result of activation during nuclear weapons tests, operation of reprocessing plants and reactors in nuclear power stations, and in nuclear studies. Modem radioanalytical techniques have enabled activation products such as Na, Cr, " Mn, Fe, °Co, Ni Zn, °Ag, and " Sb to be detected in the environment [28,29]. Stainless steel containing iron, nickel, and cobalt is an important material in nuclear power reactors and is used to constmct nuclear test devices or their supporting stmctures [30,31]. During neutron activation of the stable isotopes of cobalt, radioactive isotope °Co (J = 5.27 years) is produced. It is a beta emitter and decays into °Ni, with energy niax of... 

The most direct information on the state of cobalt has come from Mossbauer spectroscopy, applied in the emission mode. As explained in Chapter 5, such experiments are done with catalysts that contain the radioactive isotope 57Co as the source and a moving single-line absorber. Great advantages of this method are that the Co-Mo catalyst can be investigated under in situ conditions and the spectrum of cobalt can be correlated to the activity of the catalyst. One needs to be careful, however, because the Mossbauer spectrum one obtains is strictly speaking not that of cobalt, but that of its decay product, iron. The safest way to go is therefore to compare the spectra of the Co-Mo catalysts with those of model compounds for which the state of cobalt is known. This was the approach taken... 

High-energy radiation may be classified into photon and particulate radiation. Gamma radiation is utilized for fundamental studies and for low-dose rate irradiations with deep penetration. Radioactive isotopes, particularly cobalt-60, produced by neutron irradiation of naturally occurring cobalt-59 in a nuclear reactor, and caesium-137, which is a fission product of uranium-235, are the main sources of gamma radiation. X-radiation, of lower energy, is produced by electron bombardment of suitable metal targets with electron beams, or in a... 

Symbol Ni atomic number 28 atomic weight 58.693 a transition metal element in the first triad of Group VIll(Group 10) after iron and cobalt electron configuration [Ar]3d 4s2 valence states 0, -i-l, +2, and -f-3 most common oxidation state +2 the standard electrode potential, NF+ -1- 2e Ni -0.237 V atomic radius 1.24A ionic radius (NF+) 0.70A five natural isotopes Ni-58 (68.08%), Ni-60 (26.22%), Ni-61 (1.14%), Ni-62 (3.63%), Ni-64 (0.93%) nineteen radioactive isotopes are known in the mass range 51-57, 59, 63, 65-74 the longest-lived radioisotope Ni-59 has a half-life 7.6x10 years. 

Particles emitted from radioactive isotopes are generally too low in energy to provide the penetration required for conventional treatments of tumors with external radiation beams. Most external beam radiation therapies are performed with high-energy x-rays or electrons produced with compact linear accelerators with accelerating potentials between about 4 and 20 MeV. One notable exception is certain devices designed for stereotactical radiosurgery or radiation therapy of superficial tumors that use cobalt-60 y-rays. The... 

The most widely used radioactive isotopes in medical and industrial applications are cobalt 60 ( C), cesium 137 ( Cs), and iridium 192 ( lr). The half-life of is 5.3 years, that of Cs is 30 years, and the half-life of Ir is 74 days. When used for irradiation the isotope is generally in the form of a pellet size, 1.5 x 1.5 mm, loaded into a stainless steel capsule and sealed. Unlike electron beam or x-rays, gamma rays cannot be turned off. 

Impulseless resonance absorption of y-quants (gamma radiation) from a radioactive isotope, here Cobalt 57Co 57Fe + y (main quant 122 keV quant used for spectroscopy has a different energy)... 

Commonly used radiopharmaceuticals are carbon 14 (ti/2 30 years), cobalt 57 (ti/2 271 days), cobalt-58 (ti/2 70.8 days), gold-198 (ti/2 2.7 days), iodine-123 (ti/2 12.3 hours), iodine-125 O1/2 60 hours), iodine-131 (ti/2 8.04 days), and tritium (ti/2 12.3 years). The iodine radioisotope is used to study thyroid function and is used in the treatment of hyperthyroidism and thyroid carcinoma. Various monoclonal antibodies labeled with iodine-171 are used for the detection of malignant neoplasms. Genetic damage is a dangerous side effect of radioactive isotopes prior to and during the reproductive period. Exposure to large doses leads to leukopenia, anemia, skin inflammation, radiation sickness, and neoplasm. 

Isotope dilution is applicable to any element for which an enriched isotope is available. Figure 1.1 of Chapter 1 indicates which elements are amenable to isotope dilution in most cases the natural element has at least two stable isotopes, but this is not necessarily the case. For example, 232Th, though radioactive (half-life of 1.4 X 1010 years), is present in the earth s crust 230Th (half-life of 7.5 X 104 years), an isotope present in nature at such low levels as to be negligible for most applications, is used as a spike for isotope dilution purposes in the author s laboratory. Another common example is the use of 233U (a synthetic isotope) as a spike for uranium analyses. The only elements not amenable to the technique are those, like cobalt and arsenic, that have only one stable isotope and all of whose radioactive isotopes have half-lives so short as to preclude their use. 

We can use the effects of radiation for good as well as evil. Radioactive isotopes of elements can be used in specific apparatus to focus their radiation on unwanted body material and cancerous cells. Often the gamma rays from the 60 isotope of cobalt (27C0) are used to produce these penetrating rays to kill cancer cells. This same isotope is also used to produce the gamma rays to sterilize medical instruments. It kills the germs but the instruments remain unaffected. 

One of the important applications of MBssbauer spectroscopy is in the determination of bonding of the MBssbauer nuclide. Since the cobalt MBssbauer s ctrun can only be observed in the emission mode, the radioactive isotope must be inserted into the... 

I don t say that they should change from basic research to applied research they still may be carrying on the basic research, but they need to explain to the public the importance of it. So many things are discovered. For example, in the case of my discovery of all these radioactive isotopes — technetium-99m, iodine-131, cobalt-60, and cesium-137, all turned out to have tremendous practical applications in nuclear medicine. There are millions of applications per year now. 

Twenty-six radioactive isotopes of cobalt are known also, for which half lives are available. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. 

Cobalt-60 One of the most widely used of all radioactive isotopes is cobalt-60. In medicine, it is used to find and treat diseases. For example, it is used in a test known as the Schilling test. This test is a method for determining whether a person s body is making and using vitamin Bj2 properly. Two other isotopes of cobalt, cobalt-57 and cobalt-58, are used for the same purpose. 

National authorities control the security of irradiation facilities the maximal energy of these radiations is fixed, according to WHO recommendations, by construction of the accelerator or by choice ofthe radioactive isotope (mainly cobalt 60) in order to avoid any induction of additional radioactivity in the foodstuff. 

There is no critical mass in a fusion bomb, and the force of the explosion is limited only by the quantity of reactants present. Thermonuclear bombs are described as being cleaner than atomic bombs because the only radioactive isotopes they produce are tritium, which is a weak /S-particle emitter (ti = 12.5 yr), and the products of the fission starter. Their damaging effects on the environment can be aggravated, however, by incorporating in the construction some nonfissionable material such as cobalt. Upon bombardment by neutrons, cobalt-59 is converted to cobalt-60, which is a very strong 7-ray emitter with a half-life of 5.2 yr. The presence of radioactive cobalt isotopes in the debris or fallout from a thermonuclear explosion would be fatal to those who survived the initial blast. 

As high-energy radiation, y-rays (electiomagnetic radiation emitted by a source of a radioactive isotope, mostly cobalt 60) or electron beams (electron accelerator of low energies, 0.1-3 MeV or high-energy electron accelerator, 10 MeV) are available. 

Cobalt-60 is a radioactive isotope used to treat cancers of the brain and other tissues. A gamma ray emitted by an atom of this isotope has an energy of 1.33 MeV (million electron volts 1 eV = 1.602X 10 J). What is the frequency (in Hz) and the wavelength (in m) of this gamma ray ... 

As time goes by, the activity of all radioactive sources diminishes according to an exponential law characterized by its half-life. The half-life is the time taken for the activity to fall to half of its original value. Cobalt-60 has a half-life of 5.3 years caesium-137 has a half-life of 30 years. Thus a radioactive isotope is decaying and losing activity at all times regardless of whether it is being used or not. This factor has economic implications for industrial-scale irradiation. 

Considerable work has been published concerning the incorporation of radioactive-isotope-labeled olefins in hydrocarbons during Fischer-Tropsch reactions. The pioneering work of Kummer and Emmett [89] and of Hall et al. [88] suggested that ethylene acted as a chain initiator over iron catalysts. The same results were obtained over cobalt catalyst by Eidus et al. [131]. 

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