Advertisement

Giant Dipole Resonances in Excited Nuclei

  • K. A. Snover
Conference paper

Abstract

Since 1981 [1], many experiments have demonstrated the universal nature of the giant dipole resonance (GDR) in the high energy γ-decay of highly excited, equilibrated nuclei formed in heavy ion reactions. Typically the GDR is excited along with other degrees of freedom, so that its decay leaves the nucleus in an excited state. The signature of GDR decay is high energy (Eγ ~ 10–30 MeV) γ-emission. As in photoabsorption in the giant resonance region, other multipoles contribute only weakly, while non3tatistical emission processes such as pre-equilibrium giant resonance excitation and/or nuclear bremstrahlung are appreciable only at higher bombarding energies. The effect of GDR decay shows up as a “bump” for Eγ ~ ED (~80A-1/3 MeV in medium-heavy nuclei) on an otherwise exponentially decaying spectrum, and the shape of the bump reflects the average shape of the GDR built on excited states, which may be extracted by a statistical model analysis of the measured spectrum shape. Statistical evaporation or high energy γ rays with Eγ ~ ED > En ≅ Bn + 2T (Bn=neutron binding energy, T = temperature) is favored to occur at the earliest stage of the evaporation process; as a result, the spectrum shape is characteristic of the properties of the highly excited nucleus.

Keywords

Compound Nucleus Giant Dipole Resonance Giant Resonance High Excitation Energy Excited Nucleus 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    J.O. Newton, B. Herskind, R.M. Diamond, E.L. Dines, J.E. Draper, K.H. Lindenberger, C. Schück, S. Shih, and F.S. Stephens, Phys. Rev. Lett. 46, 1383 (1981).ADSCrossRefGoogle Scholar
  2. 2.
    K.A. Snover, Ann. Rev. of Nucl. Part. Phys., Vol. 36, 1986, in press.Google Scholar
  3. 3.
    C.A. Gossett, K.A. Snover, J.H. Gundlach, G. Feldman, J. Behr, and M. Kicinska-Habior, to be published.Google Scholar
  4. 4.
    J.H. Gundlach et al., to be published.Google Scholar
  5. 5.
    C.A. Gossett, K.A. Snover, J.A. Behr, G. Feldman, and J.L. Osborne, Phys. Rev. Lett. 54, 1486 (1985).ADSCrossRefGoogle Scholar
  6. 6.
    P.F. Bortignon and R.A. Broglia, Proc. of the Topical Meeting on Phase Space Approach to Nuclear Dynamics, Trieste, Italy, Singapore: World Sci. Pub. Co. (1986), P.F. Bortignon, R.A. Broglia, G.F. Bertsch, and J. Pacheco, to be published (1986).Google Scholar
  7. 7.
    M.N. Harakeh, D.H. Dowell, G. Feldman, E.F. Garman, R. Loveman, J.L. Osborne, and K.A. Snover, Phys. Lett., in press.Google Scholar
  8. 8.
    M. Gallardo, M. Diebel, T. Dossing, and R.A. Broglia, Nucl. Phys. A 443, 415 (1985).ADSCrossRefGoogle Scholar
  9. 9.
    J.J. Gaardhøje, C. Ellegaard, B. Herskind, R.M. Diamond, M.A. Delaplangue, G. Dines, A.O. Macchiavelli, and F.S. Stephens, Phys. Rev. Lett. 56, 1783 (1986).ADSCrossRefGoogle Scholar
  10. 10.
    J.J. Gaardhøje, C. Ellegaard, B. Herskind, and S.G. Steadman, Phys. Rev. Lett. 53, 148 (1984)ADSCrossRefGoogle Scholar
  11. 10a.
    J.J. Gaardhøje, Nuclear Structure, 1985 R. Broglia, G. Hagemann, B. Herskind, eds. Amsterdam: North-Holland pp. 519–534 (1985).Google Scholar
  12. 11.
    H. Sagawa and G.F. Bertsch, Phys. Lett. B 146, 138 (1984).ADSCrossRefGoogle Scholar
  13. 12.
    M. Barranco, A. Polls, S. Marcos, J. Navarro, and J. Treiner, Phys. Lett. B 154, 96 (1985).ADSCrossRefGoogle Scholar
  14. 13.
    F. Puhlhofer, Nucl. Phys. A 280:267 (1977).ADSCrossRefGoogle Scholar
  15. 14.
    G. Nebhia et al., to be published.Google Scholar
  16. 15.
    M. Kicinska-Habior, E.F. Garman, C.A. Gossett, K.A. Snover, J. Behr, G. Feldman, H.. Glatzel, and J.H. Gundlach, to be published.Google Scholar
  17. 16.
    D. Schwalm, 1984 Erice Summer School Proceedings (1985).Google Scholar
  18. 17.
    J.A. Behr, G. Feldman, C.A. Gossett, J. Gundlach, and K.A. Snover, to be published (1986).Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1986

Authors and Affiliations

  • K. A. Snover
    • 1
  1. 1.Department of PhysicsUniversity of WashingtonSeattleUSA

Personalised recommendations