Elsevier

Physics Letters B

Volume 670, Issue 3, 18 December 2008, Pages 200-204
Physics Letters B

Photon data shed new light upon the GDR spreading width in heavy nuclei

https://doi.org/10.1016/j.physletb.2008.10.055Get rights and content

Abstract

A global study of the electric dipole strength in and below the isovector giant dipole resonance (GDR) is presented for mass numbers A>80. It relies on the recently established remarkably good match between data for the nuclear photo effect to novel photon scattering data covering the region below the neutron emission threshold as well as by average resonance neutron capture (ARC). From the wide energy coverage of these data the correlation of the GDR spreading width with energy can be studied with remarkable accuracy. A clear sensitivity to details of the nuclear shape, i.e. the β- and γ-deformations, is demonstrated. Based hereon a new parameterization of the energy dependence of the nuclear electric-dipole strength is proposed which — with only two new parameters — allows to describe the dipole strength in all heavy nuclei with A>80. Although it differs significantly from previous parameterizations it holds for spherical, transitional, triaxial and well deformed nuclei. The GDR spreading width depends in a regular way on the respective resonance energy, but it is independent of the photon energy.

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Acknowledgement

Intensive discussions with F. Bečvář, F. Dönau, S. Frauendorf, M. Krtička, P. Michel, K.D. Schilling and R. Wünsch are gratefully acknowledged.

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    Supported by the DFG under Contract Nos. DFG-Gr1674/1-2 and DFG-Do466 /1-2.

    1

    Present address: Physics Department, Duke University, Durham NC 27708, USA.

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