Nuclear theory

Comparatively little space will therefore be devoted to some rather recent approaches, such as the plasma model of Bohm and Pines, the two-body interaction method developed by Brueckner in connection with nuclear theory, Daudel s loge theory, and the method of variation of the second-order density matrix. This does not mean that these methods would be less powerful or less impor-... 

The equation of state (EOS), the composition and the possible occurrence of phase transitions in nuclear matter are widely discussed topics not only in nuclear theory, but are also of great interest in astrophysics and cosmology. Experiments on heavy ion collisions, performed over the last decades, gave new insight into the behavior of nuclear systems in a broad range of densities and temperatures. The observed cluster abundances, their spectral distribution... 

Dr. Flinn The tin case is peculiarly diflBcult from the point of view of nuclear theory. There are some cases where the nuclear theory is clear cut, and one not only obtains a good value but a definite sign and a fairly good estimate of the magnitude. This just happened to be a bad one. 

During the last few years the study of spectra of heavy and superheavy elements (atoms and ions) has been of great interest for further development in atomic and nuclear theories [1-12]. Theoretical methods used to calculate the spectroscopic characteristics of heavy and superheavy ions may be divided into... 

Lecture on Nuclear Theory," translated from the Russian, Plenum Press, NY(1959)... 

Nonrelativistic quantum mechanics, extended by the theory of electron spin and by the Pauli exclusion principle, provides a reliable theory for the computation of atomic spectral frequencies and intensities, of cross sections for scattering or capture of electrons by atomic systems, of chemical bonds and many properties of solids, including magnetic properties, although with much more complicated systems it has not always proved possible to develop with adequate accuracy the consequences of the theory. Quantum mechanics has also had a limited success in nuclear theory although m this field it is possible that a more fundamental system of mechanics is required. 

Although the material contained in this book concerns the theory of many-electron atoms and ions, its many ideas and methods (e.g., graphical methods, quasispin and isospin techniques, particle-hole formalism, etc.) are fairly universal and may be easily applied (or already are) to other domains of physics (nuclear theory, elementary particles, molecular, solid state physics, etc.). 

J. M. Eisenberg and W. Greiner, Nuclear Theory vol. 2, North-Holland, Amsterdam, 1970. 

To adequately treat these many applications and to illustrate the specific ways in which decay data make useful, if not crucial, contributions to them is a task that lies beyond the space and time limitations of this paper. We have thus chosen to limit the scope of this presentation to the discussion of several selected examples, drawn mostly from the area of fission-reactor physics. These include the results of recent significant developments in actinide-nuclide decay data and, in the spirit of this symposium, decay data of fission-product nuclides off the line of p stability and some of the problems and challenges they present to both experimental capabilities and nuclear theory. 

LAN64] A.M. Lane, Nuclear Theory, New York, Benjamin Cummings (1964). 

Wheeler, J.A. Fission Physics and Nuclear Theory . In Proceedings of the International Conference on the Peaceful Uses of Atomic Energy , Geneva,... 

From the beginning of his studies Langmuir was especially interested in the structure of the atom. The nature of the atom s structure was still very much in doubt. Many had crossed swords with nature to wrest this secret from her. Kelvin had pictured the atom as consisting of mobile electrons embedded in a sphere of positive electrification. J. J. Thomson had developed this same idea but his model, too, had failed because it could not account for many contradictory phenomena. Rutherford s nuclear theory of the atom as a solar system was also objected to as incomplete. The greatest difficulty to the acceptance of these models was that they all lacked a consistent explanation of the peculiar spectra of gaseous elements when heated to incandescence. 

H. A. Bethe, P. Morrison, Elementary Nuclear Theory, 2nd ed., Wiley, New York, 1956... 

The nuclear theory of atomic structure, put forward by Rutherford, regarded the electrons as moving in orbits round the nucleus. The dynamical theory of this system was developed by Bohr, who found it necessary to supplement classical mechanics by the quantum mechanics of Planck. According to classical theory, a system consisting of an electron moving in a circular orbit round a nucleus, to which it is attracted according to Coulomb s law, would lose energy, with the result that the electron would approach and finally collide with the nucleus. Thus on the basis of classical theory, the Rutherford atom would only be stable for about io seconds, after which time the electron would have fallen into the nucleus. 

After Ernest Rutherford (1871-1937) discovered the atomic nucleus in 1911, he proposed the name proton for the very lightest of all nuclei the nucleus of the ordinary hydrogen atom. Proto- is Greek for first. In 1932, when James Chadwick (1891-1974) discovered another particle in the nucleus that was very similar to the positive proton except that it was electrically neutral, it was natural for him to call it a neutron. It was then equally natural to call both nuclear particles nucleons, especially when nuclear theory began to treat the proton and the neutron as two different states of the same fundamental particle. 

Some of the subgroups which are of special interest are the Office of Scientific Personnel the Office of Documentation the Nuclear Data Project which publishes Nuclear Data Tables, Nuclear Reaction Graphs, and Nuclear Theory Cards Office of Critical Tables, which publishes the Directory of Continuing Numerical Data Projects and the Prevention of Deterioration Center which publishes Prevention of Deterioration Ahstracts, Environmental Effects on Materials and Equipment Abstracts, and PDC Newsletter. The Cardiovascular Literature Project which recently left NAS-NRC is now operating as the Washington office of the Institute for Advancement of Medical Communications. 

The composition of the Earth was determined both by the chemical composition of the solar nebula, from which the Sun and planets formed, and by the nature of the physical processes that concentrated materials to form planets. The bulk elemental and isotopic composition of the nebula is believed or usually assumed to be identical to that of the Sun. The few exceptions to this include elements and isotopes such as lithium and deuterium that are destroyed in the bulk of the Sun s interior by nuclear reactions. The composition of the Sun as determined by optical spectroscopy is similar to the majority of stars in our galaxy and, accordingly, the relative abundances of elements in the Sun are referred to as "cosmic abundances". Although the cosmic abundance pattern is commonly seen in other stars, there are dramatic exceptions, such as stars composed of iron or solid nuclear matter, as is the case with neutron stars. The best estimation of solar abundances is based on data from optical spectroscopy and meteorite studies and in some cases extrapolation and nuclear theory. The measured solar abundances are listed in Fig. 2-1 and Table 2-1. It is believed to be accurate to about 10% for the majority of elements. The major features of the solar abundance distribution are a strong decrease in the abundance of heavier elements, a large deficiency of Li, Be, and B, and a broad abundance peak centered near Fe. The factor of 10 higher... 

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