Natural decay chain

The natural decay chains have several examples of short-lived a activities that are delayed by a longer-lived parent. In fact, the existence of these activities on Earth is possible by the fact that the head of the chain has a half-life on the order of the age of the Earth. Another more practical example near the end of the 4n chain is 212Pb with a half-life of 10.6 h that decays to 212Bi. The daughter rapidly decays by a or (3 emission. The lead nucleus is also preceded by a shortlived Rn parent, which can produce very thin sources of a particles by emanation. 

The idea of transmutation of elements in the natural decay chains did not accompany the discovery of radioactivity by Becquerel. However, Marie and Pierre Curie extended the investigations of Becquerel using a variety of... 

U minerals and found the radioactive properties to be not a function of the physical or chemical forms of the uranium, but properties of the element itself. Using chemical separation methods, they isolated two new radioactive substances associated with the U minerals in 1898 and named them polonium and radium. In 1902 Ernest Rutherford and Frederick Soddy explained the nature of the process occurring in the natural decay chains as the radioactive decays of U and Th to produce new substances by transmutation. 

Actinium (Ac) 89 21.8 y natural decay chain Nudear battery... 

Protactinium (Pa) 91 3.28x10 y natural decay chain No commercial use... 

Case (i) Successive radioactive decay. This occurs after formation of the first radioactive (parent) member Xj. Thus we only consider the left vertical chain, and assume a2, etc. = 0. In this A + I chain the second index is constant, and we omit it for case (i). This case is valid for all natural decay chains and for fission product decay chains. Each member of the decay chain can be described by the differential equation... 

The radionuclides in this category that emit beta particles also emit gamma rays that can be detected by spectral analysis. Short-lived radionuclides that emit alpha particles occur in the natural decay chains and usually are identified by other members of the decay chain that emit gamma rays. One caution to consider is that air filters and other surfaces in the environment collect particulate progeny of °Rn and Rn that emit alpha particles, beta particles, and gamma rays with half-lives of minutes to hours. Observation of such emissions and decays has misled unprepared observers into attributing these radiations to man-made radionuclides. 

Heusser, G. 2003. Low-background gamma spectroscopy of natural decay chain activity at the pliq/kg level. Paper presented at the national meeting of the American Chemical Society, Division of Nuclear Chemistry and Technology Paper No. 15. New York. Contact address for Heusser Max Planck Institut fuer Kernphysik, POB 103 980 D-69029, Heidelberg, Germany. 

The equations for growth and decay of genetically related radioactive materials were developed (Bateman 1910) in order to understand the complicated relations among the components of the natural decay chains. Time dependence remains important. First, it is of interest to... 

All of the members of the natural decay chains are unstable with respect to spontaneous fission, but the probabilities are small. The decay chains follow the side of the valley of stability where the fissionability parameter Z A is relatively small. However, fission is such an extraordinary event that even a few events can be detected, as long as they can be distinguished from events such as muon-induced fission. For the natural chains has the highest fraction of decays by spontaneous fission, 5.4 x 10. Although this leads to a multitude of natural decay chains consisting of fission followed by decays through fission product chains, the process will not be considered in this chapter. 

Instances of heavy ion emission by members of the natural decay chains... 

Bismuth-212 is a 60.6-min daughter of the natural decay chain. This radionuclide has two... 

There are two additional radioactive decay chains another natural decay chain starting with Th-232 ending with stable Pb-208 and an artificial decay chain that begins with Np-237 and goes through U-233 until a stable nuclide of Tl-205 is formed, shown in Figures 1.5 and 1.6, respectively. 

Similarly, natural thorium is a mononuclidic element, i.e., it has only one radioactive isotope thorium-232, parent radionuclide of the natural decay chain (4n), therefore, for a naturally occurring radioactive material containing a mass fraction of natural thorium, the specific activity of the parent radionuclide is given by ... 

It is an unfortunate fact that, within the natural decay chains, the nuclides most easily measured by gamma-ray spectrometry are in the later decay chain stages -beyond the point at which equilibrium might have been disturbed. 

The values have been determined on the basis of consideration of the worldwide distribution of activity concentrations for these radionuclides. Consequently, they are valid for the natural decay chains in secular equilibrium that is, those decay chains headed by U, U or Th, with the value given to be applied to the parent of the decay chain. The values can also... 

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