Giant Resonances Excited by Heavy-ions
Giant Resonances Excited by Heavy-ions

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Publisher:

Published: 1979

Total Pages:

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The potential of heavy-ion inelastic scattering as a method for studying giant resonance spectroscopy is investigated and compared to results obtained with the (.cap alpha., .cap alpha.') reaction. Optical model calculations reveal a strong dependence of the excitation cross sections upon bombarding energy. Differences between the backgrounds encountered in light and heavy hadron scattering experiments are discussed. 35 references.

Gamma Decay of Giant Resonances Excited by Heavy Ions
Gamma Decay of Giant Resonances Excited by Heavy Ions

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Publisher:

Published: 1988

Total Pages:

ISBN-13:

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Experiments on 2°8Pb bombarded by 17O at 22 MeV/nucleon (ORNL) and 84 MeV nucleon (GANIL) are reviewed. Inelastically scattered projectiles were detected at forward angles in coincidence with gamma rays seen in NaI (ORNL) or in BaF2 (GANIL). The 17O were identified by 6 Si telescopes covering THETA = 11. 5/degree/--14.5/degree/ (ORNL) or by the focal-plane detector system of the energy-loss spectrometer SPEG, set to accept THETA = 1. 5/degree/--5.0/degree/ (GANIL). The .gamma.-ray data provide information on the multipole character of various parts of the giant resonance region, matrix elements between the GR region and low-lying states in 2°8Pb, and the relative contribution of direct and compound process to .gamma.0 decay. At the higher energy the 9--15 MeV GR region is excited very strongly. The isovector giant dipole is dominant over most of the angles studied. Significant contributions from the isoscalar giant quadrupole and monopole resonances are also present. Decomposition of the GR into L = 1, 2, and 0 components was based on coincidences with the overwhelmingly dipole .gamma.0 transitions. The magnitude (1.7 +- 0.2%) and energy distribution of the .gamma.0 branch can be reproduced well by a parameter-free calculation. The .gamma.0 decay of the isoscalar giant quadrupole resonance is more easily observed at the lower energy. The .gamma.0 angular correlations confirm the presence of E2 radiation from states in the 9--11 MeV region. The B(E2) implies that the ratio of neutron to proton matrix elements is consistent with the expected value of N/Z. This conclusion is confirmed by evidence form Coulomb-nuclear interference in the singles data at 84 MeV/nucleon. Photon decays to excited states indicate that 4 and/or 6/sup +/ strength is present around 9--10 MeV, and are consistent with a monopole contribution from 12.5--15.5 MeV. 20 refs., 14 figs.

Excitation and Photon Decay of Giant Resonances Excited by Intermediate Energy Heavy Ions
Excitation and Photon Decay of Giant Resonances Excited by Intermediate Energy Heavy Ions

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Publisher:

Published: 1987

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Inelastic scattering of medium energy heavy ions provides very large cross sections and peak-to-continuum ratios for excitation of giant resonances. For energies above about 50 MeV/nucleon, giant resonances are excited primarily through Coulomb excitation, which is indifferent to isospin, thus providing a good probe for the study of isovector giant resonances. The extremely large cross sections available from heavy ion excitation permit the study of rare decay modes of the giant resonances. In particular, recent measurements have been made of the photon decay of giant resonances following excitation by 22 and 84 MeV/nucleon 17O projectiles. The singles results at 84 MeV/nucleon yield peak cross sections for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance of approximately 0.8 and 3 barns/sr, respectively. Data on the ground state decay of the isoscalar giant quadrupole and isovector giant dipole resonances are presented and compared with calculations. Decays to low-lying excited states are also discussed. Preliminary results from an experiment to isolate the 2°8Pb isovector quadrupole resonance using its gamma decay are presented. 22 refs., 19 figs., 1 tab.

Heavy Ion Excitation of Giant Resonances
Heavy Ion Excitation of Giant Resonances

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Published: 1987

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The prospects for high energy heavy ion excitation of giant resonances are discussed. A brief review is provided of the results obtained to date using low/medium energy heavy ions and it is suggested that those results show no substantial advantage of heavy ions for giant resonance excitation. Calculations are presented that show that Coulomb excitation becomes the dominant excitation mechanism of the giant resonances for heavy ions above about 100 MeV/nucleon. The Coulomb excitation provides extremely large differential cross sections for excitation of both isovector and isoscalar resonances. Recent data are presented for inelastic scattering of 84 MeV/nucleon 17O ions on 2°8Pb that demonstrate the effectiveness of Coulomb excitation in providing extremely large cross sections and peak-to-continuum ratios for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance. 19 refs., 17 figs.

Heavy Ion Excitation and Photon Decay of Giant Resonances
Heavy Ion Excitation and Photon Decay of Giant Resonances

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Published: 1983

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Results are presented for excitation of giant multipole resonances by inelastic scattering of 350 and 500 MeV 16O projectiles from 9°Zr and 2°8Pb. The giant quadrupole resonance is excited with large cross sections and a very large resonance peak to continuum ratio is obtained. Extracted cross sections agree with DWBA calculations which use standard collective model form factors. Using 380 MeV 170 to excite the giant resonances, the .gamma.-ray decay has been measured for the giant quadrupole resonance region of 2°8Pb. 10 references.

Giant Resonances
Giant Resonances

Author: M. N. Harakeh

Publisher: Oxford Studies in Nuclear Phys

Published: 2001

Total Pages: 658

ISBN-13: 9780198517337

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Giant resonances are collective excitations of the atomic nucleus, a typical quantum many-body system. The study of these fundamental modes has in many respects contributed to our understanding of the bulk behavior of the nucleus and of the dynamics of non-equilibrium excitations. Although the phenomenon of giant resonances has been known for more than 50 years, a large amount of information has been obtained in the last 10 years. This book gives an up-to-date, comprehensive account of our present knowledge of giant resonances. It presents the experimental facts and the techniques used to obtain that information, describes how these facts fit into theoretical concepts and how this allows to determine various nuclear properties which are otherwise difficult to obtain. Included as an introduction is an overview of the main facts, a short history of how the field has developed in the course of time, and a discussion of future perspectives.

Giant Resonances and Intermediate Energy Heavy Ions
Giant Resonances and Intermediate Energy Heavy Ions

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Publisher:

Published: 1991

Total Pages: 11

ISBN-13:

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We briefly explore how large cross sections for excitation of both isoscalar and isovector giant multipole resonances which can be obtained using intermediate energy heavy-ion reactions can be utilized in photon-decay coincidence experiments to provide new information on subjects ranging from basic nuclear structure properties to resonance damping and pre-compound decay. We also discuss experiments in which photon-decay techniques are used as a tag to isolate and identify very weakly excited modes, enabling us to explore such diverse subjects as hadronic excitation of the giant dipole resonance, the distribution of isovector quadrupole strength in 2°8Pb, and the excitation of two-phonon giant resonance strength. 25 refs., 12 figs.

Excitation and Photon Decay of Giant Multipole Resonances - the Role and Future of Medium-energy Heavy Ions
Excitation and Photon Decay of Giant Multipole Resonances - the Role and Future of Medium-energy Heavy Ions

Author:

Publisher:

Published: 1988

Total Pages:

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Inelastic scattering of medium energy heavy ions provides very large cross sections and peak-to-continuum ratios for excitation of giant resonances. For energies above about 50 MeV/nucleon, giant resonances are excited primarily through Coulomb excitation, which is indifferent to isospin, thus providing a good probe for the study of isovector giant resonances. The extremely large cross sections available from heavy ion excitation permit the study of rare decay modes of the photon decay of giant resonances following excitation by 22 and 84 MeV/nucleon 17O projectiles. The singles results at 84 MeV/nucleon yield peak cross sections for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance of approximately 0.8 and 3 barns/sr, respectively. Data on the ground state decay of the isoscalar giant quadrupole and isovector giant dipole resonances are presented and compared with calculations. Decays to low-lying excited states are also discussed. Preliminary results from an experiment to isolate the 2°8Pb isovector quadrupole resonance using its gamma decay are presented.

Giant Resonances
Giant Resonances

Author: P.F. Bortigan

Publisher: Taylor & Francis

Published: 2023-05-31

Total Pages: 290

ISBN-13: 1000940667

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The series of volumes, Contemporary Concepts in Physics, is addressed to the professional physicist and to the serious graduate student of physics. The subject of many-body systems constitutes a central chapter in the study of quantum mechanics, with applications ranging from elementary particle and condensed matter physics to the behaviour of compact stellar objects. Quantal size effects is one of the most fascinating facets of many-body physics; this is testified to by the developments taking place in the study of metallic clusters, fullerenes, nanophase materials, and atomic nuclei. This book is divided into two main parts: the study of giant resonances based on the atomic nucleus ground state (zero temperature), and the study of the y-decay of giant resonances from compound (finite temperature) nuclei.