Radioactive isotopes transformation

For the purposes of analytical chemistry, four kinds of monochromatic beams need to be considered. (The quotation marks are to remind the reader that the beams under discussion are not always truly monochromatic.) Three kinds of beams—those produced by Bragg reflection (4.9), filtered beams (4.6), beams in which characteristic lines predominate over a background that can be neglected— will be discussed later ( 6.2). The fourth kind of beam contains monochromatic x-rays that are a by-product of our atomic age and that promise to grow in importance they are given off by radioactive isotopes. These x-rays must not be confused with 7-rays (11.1), which also originate from radioactive atoms but which differ from x-rays because the transformation that leads to radiation involves the nucleus. 

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). 

Two of these isotopes, carbon-12, the most abundant, and carbon-13 are stable. Carbon-14, on the other hand, is an unstable radioactive isotope, also known as radiocarbon, which decays by the beta decay process a beta particle is emitted from the decaying atomic nucleus and the carbon-14 atom is transformed into an isotope of another element, nitrogen-14, N-14 for short (chemical symbol 14N), the most common isotope of nitrogen ... 

The curie unit (Ci) is based on the activity of 1 g of pure radium-226, which undergoes 3.7 X 1010 transformations per second. It is therefore defined as the quantity of a radioactive isotope which gives 3.7 X 1010 disintegrations per second. The SI unit of activity is the becquerel (Bq), which is equal to one nuclear transformation per second. Hence ... 

Neutrino detectors are placed at great depths, at the bottom of mines and tunnels, in order to reduce interference induced by cosmic rays (Fig. 5.3). Two methods of detection have been used to date. The first is radiochemical. It involves the production by transmutation of a radioactive isotope that is easily detectable even in minute quantities. More precisely, the idea is that a certain element is transformed into another by a neutrino impact, should it occur. Inside the target nucleus, the elementary reaction is... 

Physical Properties. Hafnium is a hard, heavy, somewhat ductile metal having an appearance slightly darker than that of stainless steel. The color of hafnium sponge metal is a dull powder gray. Physical properties of hafnium are summarized in Table 1. These data are for commercially pure hafnium which may contain from 0.2 to 3% zirconium. Although a number of radioactive isotopes have been artificially produced, naturally occurring hafnium consists of six stable isotopes (Table 2). Hafnium crystallizes in a body-centered cubic system which transforms to a hexagonal close-packed system below 2033 K. 

When the products of nuclear transformations are radioactive, they can be detected and determined quantitatively in terms of the radiations that characterize their radioactive decay. Instruments can measure the quantities of radioactive isotopes present in samples, and these methods are much more rapid and convenient than laborious chemical analyses. 

In order to use the perturbation theory it is necessary that the state vectors in the matrix element Eq. (8) belong to the spectrum of the unperturbed Hamiltonian H0 only. However, this is usually not so, since, in p decay, the initial particles are not the same as the final products of the reaction the initial molecule containing the radioactive atom transforms into a different molecule besides, the ft electron and the neutrino appear. One of the ways to describe the initial and final states using only the H0 Hamiltonian is to use the isotopic spin formalism for both the nucleons and the leptons (/ electron and neutrino). In the appendix (Section V) we present the wave functions of the initial and the final states together with the necessary transformations, which one can use to factorize the initial matrix element Eq. (8) into the intranuclear and the molecular parts. Here we briefly discuss only the approximations necessary for performing such a factorization. 

The radioactive isotope 247Bk decays by a series of a-particle and j3-particle productions, taking 247Bk through many transformations to end up as 207Pb. In the complete decay series, how many a particles and /3 particles are produced ... 

When an atom of any of these five isotopes decays, it emits an alpha particle (the nucleus of a helium atom) and transforms into a radioactive isotope of another element. The process continues through a series of radionuclides until reaching a stable, non-radioactive isotope of lead. The radionuclides in these transformation series (such as radium and radon), emit alpha, beta, and gamma radiations with energies and intensities that are unique to the individual radionuclide. 

The preceding equations hold for decay schemes that involve the simple transformation of one isotope to another. Three types of decay schemes useful for geochronology are special cases that yield somewhat more complicated age equations. Branched decay leads to the production of two different daughter isotopes from a single radioactive isotope. A familiar example is the spontaneous conversion of to both " °Ar (through electron capture) and " °Ca (through /3 decay). In such cases, the age equations must be modified by factors that correct for the fact that not all decays result in the production of the daughter isotope of interest. For the — " Ar... 

There are nine known radioactive isotopes and six are listed in Table 2. Sulfur-35 has the longest half-life and is produced by cosmogenic synthesis in the upper atmosphere cosmogenic S-35 (Tanaka and Turekian, 1991) is sufficiently long lived to be useful in determining overall removal and transformation rates of SO2 from the atmosphere and an estimated dry deposition flux to total flux ratio is —0.20 in the eastern US (Turekian and Tanaka, 1992). 

Stable isotope compositions are useful tracers of the sources and transformations of marine materials however, they carry no direct information about the rates and dates of the associated processes. Such temporal distinctions are possible, however, with the many different naturally occurring radioactive isotopes (Fig. 5.1) and their wide range of elemental forms and decay rates. These highly dependable atomic clocks decay by nuclear processes that allow them to be detected at veiy low concentrations. Long-lived and Th... 

Radioactive decay - The process wherein radioactive isotopes emit ionizing radiation and transform into different elements. 

Radioanalytical chemistry was first developed by Mme. M. Curie, with contributions by many other distinguished researchers, notably E. Rutherford and F. Soddy. These pioneers performed chemical separations and radiation measurements on terrestrial radioactive substances during the 20 years following 1897 and in the process created the very concept of radionuclides. Their investigations defined the three major radiation types, confirmed the emission of these radiations by the nucleus and the associated atomic transformations, established the periodic table between bismuth and uranium, and demonstrated the distinction between stable and radioactive isotopes. 

When the unstable nucleus of a radioactive isotope undergoes a nuclear transformation, i.e., decays, a new atomic species is formed with the concomitant emission... 

Not all of the 300 naturally occurring isotopes are stable. Unstable nuclei (protons and neutrons) spontaneously transform (decay) to achieve stability and are the radioactive materials syn. radionuclides or radioisotopes. Many other radioactive isotopes are made artificially by bombarding atoms with neutrons or charged particles in processes that occur in nuclear energy reactors and particle accelerators. As nuclei decay, they emit one of four types of radiation characteristic of the atom ... 

Additionally, some isotopes are radioisotopes - they generate radioactivity (electromagnetic waves with specific wavelengths) by transforming spontaneously into other elements (or their isotopes). Examples of radioactive isotope are Carbon-14 C C) or deuterium (hydrogen-2, H), while C and H are the stable isotopes of carbon and hydrogen, respectively. Radioisotopes are easy to identify due to the radiations they emit. 

One of the uses of neutronic reactors is to irradiate materials with neutrons and other particles and radiations. In this manner, radioactive isotopes may be produced for all chemical elements with the exception of helium. The physical transformation of elements as a result of irradiation in a neutronic reactor may be ac- complisbed through any one of a number of reactions which are fully described in the published literature. Radioactive isotopes produced by neutronic reactors are receiving large commercial interest, particularly such isotopes as H, P32, 35, and 1 As a result, there is a... 

In neutron activation analysis, an activation of a sample material is accomplished by placing the sample in some position within the neutron environment. At the time the sample is exposed to neutrons, a compound nucleus is formed as the result of the interaction of a neutron with the nucleus of a stable isotope of the element being determined. The compound nucleus i.e. the end-product of an excitation process caused by both the kinetic and binding energy of the neutron with the nucleus, instantaneously loses its excess energy by a transformation to a more stable isotope by emitting prompt radiations. As a result of this event, another stable nuclide or a radioactive isotope is formed. This radioisotope then becomes the activation, or isotopic, indicator of the element of interest. 

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