Gamma-energy emitting isotopes

These are used invariably for the gamma-energy emitting isotopes, for instance 125I-the more common iodine-isotope. 

The appropriate average beta and gamma energies emitted per disintegration, as given in the Table of Isotopes, Sixth Edition, by C.M. Lederer, J.M. Hollander, 1. Perlman University of California, Berkeley Lawrence Radiation Laboratory should be used, (g) For BWRs with stacks the atmospheric diffusion model should be as follows ... 

Neutron activation analysis (NAA) is a technique for the qualitative and/or quantitative determination of atoms possessing certain types of nuclei. Bombarding a sample with neutrons transforms some stable isotopes into radioactive isotopes measuring the energy and/or intensity of the gamma rays emitted from the radioactive isotopes created as a result of the irradiation reveals information on the nature of the elements in the sample. NAA Is widely used to characterize such archaeological materials as pottery, obsidian, chert, basalt, and limestone (Keisch 2003). 

In neutron activation analysis, the sample is bombarded with a beam of neutrons, some of which are absorbed into sample nuclei. These sample nuclei are now radioactive. They emit electromagnetic radiation, gamma rays. Each isotope is represented by a specific energy and frequency of gamma ray, which identifies the isotope and, thus, the element. In this method of detecting art forgeries, the sample is not changed and its composition can be accurately assessed. 

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 ... 

If the source is a positron emitter, a peak at 0.511 MeV is always present. The positron-emitting isotope Na is such an example. It emits only one gamma with energy 1.274 MeV, yet its spectrum shows two peaks. The second peak is produced by 0.511-MeV annihilation photons emitted after a positron annihilates (Fig. 12.8). 

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