Göttingen 1997 – wissenschaftliches Programm

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HK: Hadronen und Kerne

HK 59: Postersitzung

HK 59.8: Poster

Donnerstag, 27. März 1997, 14:00–16:30, P

The Contribution of Density Fluctuations to the Damping of Giant Resonances — •K. Morawetz¹, M. DiToro², and U. Fuhrmann¹ — ¹AG Quantentheorie und Vielteilchensysteme, FB Physik Universität Rostock, Universitätsplatz 3, D-18051 Rostock — ²Laboratorio Nazionale del Sud, Viale a. Doria - 95123 Catania, Italy

A generalized kinetic equation of Lennard- Balescu type is derived with retardation effects. By explicit consideration of the density-density fluctuations we give the contribution of fluctuations to the spreading width of giant resonances. Approximate formulas for the damping of giant resonances are derived [1]. The density fluctuations couple the equation of state to the damping rate and give rise to an overall enhancement factor. Explicit comparisons are made with the experimental values of giant monopole and dipole resonances. It is shown that the experimental widths can be described assuming finite nuclei since surface effects are important for the influence on density fluctuations. The recently reported saturation of the dipole width with increasing energy is explained as a transition between zero and first sound. Within this treatment we find an overcritical range of fluctuations, above which the nucleus is destroyed and no collective behaviour is possible at all.

[1] K. Morawetz, M. DiToro, and L. Münchow, Phys. Rev C. 54, 1 (1996).