Effect of nuclear decay

Chemical effects of nuclear decay have been studied in Germanium through the use of Ge and Ge. Ge decays to Ga with a 275 day half-life by 100% electron capture with no y quanta emitted. Ge is a P emitter which decays to As with a 11.3 h half-life, by three jS transitions having maximum energies of 710 keV (23%), 1379 keV (35%) and 2196 keV (42%). From this are calculated maximum recoil energies of 1.7 eV, 4.5 eV and 10.2 eV, respectively. 

Effect of Nuclear Decay Mossbauer Emission Spectroscopy... 

A general conclusion from the review of the distribution of plutonium between different compartments of the ecosystem was that the enrichment of plutonium from water to food was fairly well compensated for by man s metabolic discrimination against plutonium. Therefore, under the conditions described above, it may be concluded that plutonium from a nuclear waste repository in deep granite bedrock is not likely to reach man in concentrations exceeding permissible levels. However, considering the uncertainties in the input equilibrium constants, the site-specific Kd-values and the very approximate transport equation, the effects of the decay products, etc. — as well as the crude assumptions in the above example — extensive research efforts are needed before the safety of a nuclear waste repository can be scientifically proven. 

A recent analysis by Thielemann et al. [THI83] of the effects of B" delayed processes on the progenitors of the Th-U-Pu chronometers showed that these processes (delayed fission in particular) did indeed significantly influence the final abundances of the chronometer progenitors. This leads to a long age for the Galaxy. In view of the importance of this result, it is useful to re-examine the calculation with a nuclear model that includes the effects of nuclear deformation on the B decay rates, fission barriers, and neutron separation energies self-consistently. 

Note that in this equation the net effect of beta decay is to change a neutron into a proton. Although an electron is ejected from the nucleus, it was not part of the nuclear composition. The electron called a beta particle comes into being only when the nucleus tries to become stable, as shown here ... 

We will review here experimental tests of quantum electrodynamics (QED) and relativistic bound-state formalism in the positron-electron (e+,e ) system, positronium (Ps). Ps is an attractive atom for such tests because it is purely leptonic (i.e. without the complicating effects of nuclear structure as in normal atoms), and because the e and e+ are antiparticles, and thus the unique effects of annihilation (decay into photons) on the real and imaginary (related to decay) energy levels of Ps can be tested to high precision. In addition, positronium constitutes an equal-mass, two-body system in which recoil effects are very important. 

Positron production a mode of nuclear decay in which a particle is formed having the same mass as an electron but opposite charge. The net effect is to change a proton to a neutron. (21.1)... 

Nuclear reactions may lead to stable or unstable (radioactive) products. In general, (n, y), (n, p), and (d, p) reactions give radionuclides on the right-hand side of the line of p stability that exhibit decay, whereas (p, n), (d,2n), (n, 2n), (y, n), (d, n) and (p, y) reactions lead to radionuclides on the left-hand side of the line of p stability that exhibit p decay or electron capture (e). (n, y), (d, p), (n, 2n) and (y, n) reactions give isotopic nuclides, and these cannot be separated from the target nuclides by chemical methods, except for the application of the chemical effects of nuclear transformations which will be discussed in chapter 9. 

Chemical effects of nuclear reactions were first observed by Szilard and Chalmers in 1934 when irradiating ethyl iodide with neutrons. They found several chemical species containing 1 that are produced by the chemical effects of the nuclear reaction l(n, y) 2 1. In the following years, chemical effects of radioactive decay were observed in gaseous compounds, liquids and solids. 

Figure 9.9. Charge distribution of the ions a) after decay of Xe b) after isomeric transition of (According to A. H. Snell, F. Pleasonton, T. A. Carlson Proceedings Series, Chemical Effects of Nuclear Transformations, Vol. I. IAEA Vienna 1961, S. 147.)...

Hot-atom chemistry Chemical effects of nuclear transfonnations (radioactive decay or nuclear reactions)... 

The chemical effects of nuclear transformations have been investigated also in the case of -decay of "°Bi bound in crystalline compounds Bi(p-ClC6H4)3, " Bi(p-BrCgHJj and ... 

Effects of nuclear transformation on ion-molecule reactions following P decay in tritiated cyclobutane and cyclopentane have been investigated by Pobo and Wexler p decay in tritium-labeled compormds RT gives a carbonium ion and a neutral helium atom ... 

Consequently when an optical pumping cell filled with Rb is illuminated with circularly-polarized radiation from a rubidium resonance lamp, all the transitions shown in Fig. 18.4(b) will be excited for those atoms in the F= l level of the ground state. The transitions for atoms in the F=2 hyperfine ground-state level are even more complex and are not shown for this reason. We see that there are many more states involved than in the case shown in Fig.17.1, where the effect of nuclear spin was ignored, and that the transition probabilities of the different decay routes are also more nearly equal. The net result is that hyperfine structure makes the Zeeman pumping process much less efficient. This point is discussed in more detail in early papers by Hawkins (1955) and Franzen and Emslie (1957). 

The analysis of steady-state and transient reactor behavior requires the calculation of reaction rates of neutrons with various materials. If the number density of neutrons at a point is n and their characteristic speed is v, a flux effective area of a nucleus as a cross section O, and a target atom number density N, a macroscopic cross section E = Na can be defined, and the reaction rate per unit volume is R = 0S. This relation may be appHed to the processes of neutron scattering, absorption, and fission in balance equations lea ding to predictions of or to the determination of flux distribution. The consumption of nuclear fuels is governed by time-dependent differential equations analogous to those of Bateman for radioactive decay chains. The rate of change in number of atoms N owing to absorption is as follows ... 

The nuclear decay of radioactive atoms embedded in a host is known to lead to various chemical and physical after effects such as redox processes, bond rupture, and the formation of metastable states [46], A very successful way of investigating such after effects in solid material exploits the Mossbauer effect and has been termed Mossbauer Emission Spectroscopy (MES) or Mossbauer source experiments [47, 48]. For instance, the electron capture (EC) decay of Co to Fe, denoted Co(EC) Fe, in cobalt- or iron-containing compormds has been widely explored. In such MES experiments, the compormd tmder study is usually labeled with Co and then used as the Mossbauer source versus a single-line absorber material such as K4[Fe(CN)6]. The recorded spectrum yields information on the chemical state of the nucleogenic Fe at ca. 10 s, which is approximately the lifetime of the 14.4 keV metastable nuclear state of Fe after nuclear decay. 

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