Exotic nuclear decay

In the following, exotic nuclear decay modes of heavy nuclei, cluster radioactivities, delayed fission, and spontaneous fission (SF) together with the recent progress on deformation paths toward fission are briefly introduced. 

Delayed fission is also an exotic nuclear decay process of heavy nuclei that is observed subsequent to P or EC decay. In the delayed fission process, P decays or electron captures (EC) of the parent nuclide populate excited states of the daughter nucleus, and if these states are of energies comparable to or greater than the fission barrier of the daughter nucleus, then fission may compete with other decay modes of the excited states. The process is schematically shown in O Fig. 18.12. Reviews give a detailed description of delayed fission (Oganessian and Lazarev 1985 Hall and Hoffinan 1992). 

Exotic Decays. In addition to the common modes of nuclear decay, two exotic modes have been observed. These decay modes are of theoretical interest because theh long half-Hves place strict constraints on the details of any theory used to calculate them. 

Nuclear decay, 21 290-291 exotic modes of, 21 305-306 modes of, 21 295—306 Nuclear energy, uranium as a source of, 25 420... 

Exotic Nuclei and Their Decay. As reported by J.C. Hardy (Chalk River Nuclear Laboratories. Atomic Energy of Canada, Ltd.), recent advances in nuclear accelerators and experimental techniques have led to an increasing ability to synthesize new isotopes. As isotopes are produced with more and more extreme combinations of neutrons and protons in their nuclei, new phenomena are observed, and the versatility of the nucleus is increased as a laboratory for studying fundamental forces. Hardy reports that, among the newly discovered decay modes are (1) proton radioactivity, (2) triton, two-proton, two-neutron, and three-neutron decays that are beta-delayed, and (3) 14C emission m radioactive decay, Precise tests of the properties of the weak force have also been achieved. 

A continuing effort among experimentalists who study nuclei far from beta stability is the measurement of the atomic mass surface As a manifestation of the nuclear force and the nuclear many body system, atomic masses signal important features of nuclear structure on both a macroscopic and microscopic scale It has thus been a challenge to nuclear theorists to devise models which can reproduce the measured mass surface and to predict successfully the masses of new isotopes Both the measured mass surface and that beyond it which can be predicted by these models serve as important input to a variety of fundamental and applied problems, e g, nucleosynthesis calculations, predictions of decay modes of exotic nuclei far from stability, nuclear de-excitation by particle evaporation, decay heat simulations, etc ... 

Undoubtedly the Chalk River ISOL will be used, as others are, in the identification and spectroscopy of exotic nuclei. The nuclear chart in figure 5 illustrates the scope for such studies. However, the extreme purity of isotopes separated by our ISOL has been essential in the past to precision studies of the weak interaction, in one case the lifetimes of superallowed 0+ 0+ transitions [K.OS83], in another 8-v-a triple correlation coefficients in the decay of 2( Na [CLI83] both yielded measurements of the weak vector coupling constant. These types of measurements will be extended to other nuclei, since they exploit the best qualities of the accelerator and separator. 

Nuclear reactions producing exotic nuclei at the limits of stability are usually very non-specific. For the fast and efficient removal of typically several tens of interfering elements with several hundreds of isotopes from the nuclides selected for study mainly mass separation [Han 79, Rav 79] and rapid chemical procedures [Her 82] are applied. The use of conventional mass separators is limited to elements for which suitable ion sources are available. There exists a number of elements, such as niobium, the noble metals etc., which create problems in mass separation due to restrictions in the diffusion-, evaporation- or ionization process. Such limitations do not exist for chemical methods. Although rapid off-line chemical methods are still valuable for some applications, continuously operated chemical procedures have been advanced recently since they deliver a steady source of activity needed for measurements with low counting efficiencies and for studies of rare decay modes. The present paper presents several examples for such techniques and reports briefly actual applications of these methods for the study of exotic nuclei. 

If a sample is irradiated with particles or radiation then the non-radiactive nuclei take part in nuclear reactions. As a result of which radioactive nuclides are obtained. Decaying they emit radiation which is proportional to the quantity of atoms and its energy is characteristic for the respective nucleus. Depending on the type of irradiation and emission several versions of activation analysis (AA) can be distinguished, some of which are rather exotic though very effective (Hoste et al., 1971 De Soete et al., 1972 Das et al., 1983 Erdtmann and Petri, 1986 Alfassi, 1990). 

Abstract This chapter reviews the historical perspective of transuranium elements and the recent progress in the production and study of nuclear properties of transuranium nuclei. Exotic decay properties of heavy nuclei are also introduced. Chemical properties of transuranium elements in aqueous and solid states are summarized based on the actinide concept. For new application of studying transuranium elements, an X-ray absorption fine structure (XAFS) method and computational chemistry are surveyed. 

The decay of the exotic atom can be a simple decay of the exotic particle in the case of light muonic atoms however, due to the strong nuclear interaction in hadronic atoms, the negative hadron can be absorbed by the nucleus leading to nuclear reaction (O Fig. 28.5). 

His research field is nuclear theory reactions, clustering, cluster decay and light exotic nuclei. He is a coauthor of the monograph Structure and Reactions of Light Exotic Nuclei (2003). 

We conclude this chapter with a look at some more exotic properties, at least from the point of view of mainstream chemistry. In a 1949 article celebrating Einstein s 70th birthday, Dirac (1949) suggested that the laws of nature might not be invariant with respect to space inversion or time reversal. Special relativity only requires that physical laws be invariant with respect to the position and velocity of the observer, and any change in these can be effected though a series of (infinitesimal) transformations that do not involve reflections of time or space. Experimental evidence for processes that do not conserve parity under space inversion, P-odd processes, was eventually observed in nuclear p decay, contributing in turn to the development of the standard model for... 

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