[PDF] Pion Double Charge Exchange And Nuclear Structure eBook

Author : William R Gibbs
Publisher : World Scientific
Page : 622 pages
File Size : 25,29 MB
Release : 1990-09-24
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ISBN : 9814611875

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What do you associate with chemistry? Explosions, innovative materials, plastics, pollution? The public's confused and contradictory conception of chemistry as basic science, industrial producer and polluter contributes to what we present in this book as chemistry's image as an impure science. Historically, chemistry has always been viewed as impure both in terms of its academic status and its role in transforming modern society. While exploring the history of this science we argue for a characteristic philosophical approach that distinguishes chemistry from physics. This reflection leads us to a philosophical stance that we characterise as operational realism. In this new expanded edition we delve deeper into the questions of properties and potentials that are so important for this philosophy that is based on the manipulation of matter rather than the construction of theories./a

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Page : pages
File Size : 50,3 MB
Release : 1987
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Pion double charge exchange to both the double-analog state and the ground state is studied for medium weight nuclei. The relative cross section of these two transitions and the importance of nuclear structure as a function of pion kinetic energy is examined. 16 figs., 5 tabs.

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Page : 13 pages
File Size : 17,12 MB
Release : 1994
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Pion single and double charge exchange are being understood as an interplay between nuclear structure, hadron dynamics, and multiple scattering. Examples are given from work carried out in the last few years, and prospects for future development is given.

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Page : pages
File Size : 47,24 MB
Release : 1984
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Recognizing the importance of both the reaction mechanism and nuclear structure aspects of the DCX, a new reaction theory was proposed in 1981 which offers a consistent treatment of these two equally important components of pion DCX. In this theory, the density square-dependent interaction is derived from the dynamical consideration of true pion absorption on a nucleon pair inside the nucleus. The strength of this new pion-nucleus interaction can then be calculated from the knowledge of the second-order pion-nucleus optical potential. With no free parameters for the pion-nucleus interaction and with the use of the coexistence nuclear model, the theory gives satisfactory descriptions of the magnitude and the shape of 5° excitation functions as well as of the differential cross sections for the DCX reactions 18O(.pi., .pi.−) 18Ne(DIAS) and 42Ca(.pi., .pi.−) 42Ti(DIAS) between 120 and 290 MeV. Our basic conclusions are: (1) the TSSCX mechanism alone cannot describe pion DCX; (2) the position of the first minimum in the differential cross section is very sensitive to the inclusion of density square-dependent interaction; and (3) on the other hand, the magnitude of the cross section is very sensitive to the inclusion of pair correlations (core excitation in the case with 18O and 42Ca).

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Page : pages
File Size : 28,10 MB
Release : 1986
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Some experiments are reviewed that have used the pion as a probe of nuclear structure. The examples chosen use the qualitative features of the pion-nucleon interaction to study selectively certain aspects of nuclear structure. The talk is divided into five parts: (1) properties of the pion and the pion-nucleon interaction, (2) studies of the isospin mixing and neutron-to-proton matrix element ratios in inelastic scattering, (3) studies of isovector giant resonances in pion single-charge-exchange reactions, (4) the search for six-quark structures in the nucleus using pion double-charge-exchange reactions, and (5) concluding remarks. 20 refs., 12 figs.

Author : William R. Gibbs
Publisher :
Page : 0 pages
File Size : 11,84 MB
Release : 1990
Category : Science
ISBN : 9789810201487

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Spine title: Pion-nucleus double charge exchange.

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Page : pages
File Size : 35,10 MB
Release : 1987
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Whereas the nuclear charge distribution, essentially determined by the protons, has been studied for decades in elastic electron scattering, a study of the neutron distribution in nuclei has only recently become possible through pion charge-exchange experiments. The excitation of the isobaric analog state (IAS) in pion single-charge-exchange reactions is one of the most prominent candidates for such an investigation which will be especially interesting for strongly deformed nuclei which can be aligned in magnetic fields. This contribution concentrates on calculations related to such a reaction for the rare-earth nucleus Ho-165. 8 refs., 3 figs.

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Page : pages
File Size : 15,44 MB
Release : 1981
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The (.pi., .pi.−) double-charge-exchange (DCX) reaction has been performed on targets of T = 0,1 isospin (and isotopic) pairs 16 18O and 24 26Mg. Energy excitation functions of d sigma/d .cap omega., across the (3,3) .pi.-N resonance, are presented for transitions to double-isobaric analog state (DIAS) and non-DIAS ground-state residual nuclei. Angular distributions in the region of 5° to 33° are presented for the DIAS from the T = 1 nuclei. The similarities and differences of DIAS and non-DIAS distributions are discussed in relation to reaction-mechanism and nuclear-structure effects. Also, a simple, two-amplitude model for the 18O excitation function, consistent with the data, is presented. The utility of DCX in nuclear mass measurements is discussed, with some examples.