Nuclides parent nuclide, radioactive decay

Calorimetry. Radioactive decay produces heat and the rate of heat production can be used to calculate half-life. If the heat production from a known quantity of a pure parent, P, is measured by calorimetry, and the energy released by each decay is also known, the half-life can be calculated in a manner similar to that of the specific activity approach. Calorimetry has been widely used to assess half-lives and works particularly well for pure a-emitters (Attree et al. 1962). As with the specific activity approach, calibration of the measurement technique and purity of the nuclide are the two biggest problems to overcome. Calorimetry provides the best estimates of the half lives of several U-series nuclides including Pa, Ra, Ac, and °Po (Holden 1990). 

Figure 1. (a) Schematic representation of the evolution by radioactive decay of the daughter-parent (N2/N1) activity ratio as a function of time t after an initial fractionation at time 0. The initial (N2/Ni)o activity ratio is arbitrarily set at 2. Time t is reported as t/T2, where T2 is the half-life of the daughter nuclide. Radioactive equilibrium is nearly reached after about 5 T2. (b) Evolution of (N2/N1) activity ratios for various parent-daughter pairs as a function of time since fractionation (after Williams 1987). Note that the different shape of the curves in (a) and (b) is a consequence of the logarithmic scale on the x axis in (b). 

Suppose the initial number of nuclei of a radioactive nuclide is N0, and that the half-life is T. Then the amount of parent nuclei remaining at a time t can be written as Nx = NQ( /2)(tlT>. This relationship is called the radioactive decay equation. What is the number of daughter nuclei present at time t, expressed in terms of N0 and Nx ... 

In case of nuclides for which the input into the box is only due to their i n situ production from radioactive decay of their parents, equation (3) modifies to ... 

Write the nuclear equation for the radioactive decay of potassium-40 by beta emission. Identify the parent and daughter nuclides in the decay. 

In the above radioactive decays, a parent nuclide shakes itself to become another nuclide or two nuclides. A unidirectional arrow indicates that there is no reverse reaction or if there is any reverse reaction, it is not considered. He produced by the homogeneous reaction (radioactive decay) may subsequently escape into another phase, which would be another kinetic process. 

The first term on the right-hand side is the melting term the second term on the right-hand side is the radioactive decay of the nuclide and the last term on the right-hand side represents the radiogenic production by the parent of the nuclide. and Cj" are the concentrations of the nuclide... 

Daughter The term is used to describe the nuclide formed by the radioactive decay of another nuclide, which in this context is called the parent. 

Geochronological measurements (isochrone methodology) are based on the radioactive decay of the parent nuclide to the daughter nuclide using the fundamental Equation (8.8) for calculating the ages of minerals. 

Since the rock was formed, the parent nuclidic content of the mineral has been changed only by radioactive decay. 

The radioactive decay scheme of the parent nuclide is well known. 

During radioactive decay an unstable atomic nucleus emits radiation in the form of particular particles or electromagnetic waves. This process results in a parallel loss of energy as so-called parent nuclide(s) transform into daughter nuclide(s). The principal types of radioactive decay are alpha (a), beta (ft) and gamma (y), as described further in Table 10.1 the SI unit of radioactive decay is the Becquerel (Bq), where one Bq is one decay (or transformation disintegration) per second. 

A radionuclide, upon undergoing disintegration of a particular type, yields a specified nuclide. The original radionuclide is called the parent and the decay product is called the daughter. The daughter may also be a radionuclide. A succession of nuclides, each of which transforms by radioactive disintegration into the next until a stable nuclide results, is called a radioactive series. Examples of such series are the uranium series and the thorium series. 

Radioactivity is characterized by the emission of energy (electromagnetic or in the form of a particle) from the nucleus of an atom, usually with associated elemental conversion. There are four basic types of radioactive decay (Table 5.4), of which alpha (a) and beta (p ) decay are most common in nature. Alpha emission is the only type of decay that causes a net mass change in the parent nuclide by loss of two protons plus two neutrons. Because two essentially weightless orbiting electrons are also lost when the equivalent of a helium nucleus is emitted, the parent nuclide transmutes into a daughter element two positions to the left on the periodic table. Thus decays by ot... 

Th is the parent of the 4n radioactive decay series shown in Fig. 6.1 and listed in Table 6.3. The last column of Table 6.3 gives the ratio of the number of atoms of each decay product of natural thorium to Th, assuming that the thorium has been undisturbed long enough, around 40 years, for its decay products to reach equilibrium. At equilibrium, the activities of all these radioactive nuclides are equal, except for Po and T1, which are alternative decay products of Bi. 

Radioactive decay allows calculation of an age if the concentrations of both parent and daughter nuclide are known, the beginning of the time interval is defined and the system is not disturbed (i.e. it is a "closed system") during the time interval. Some chronometers involve production of particular stable or radioactive nuclides, or decay of the latter. Typically, the chronometer half-life should be comparable with the time interval being measured. 

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