Giant Dipole Resonance Energy Research Articles

Dynamical effects in finite nuclei and their importance in giant resonance calculations

Dynamical effects on the single-particle self-energy Σ m ( ω), i.e., its ω dependence, are studied microscopically using realistic finite-range NN interactions. In heavy nuclei the coupling of particles to high collective low-lying surface vibrations causes dynamical effects much stronger than in nuclear matter. This result can resolve the discrepancies in previous calculations of giant dipole resonance energies.

Total muon capture rates for N = Z nuclei in the 1p shell

The approach to total muon capture rates by means of sum rule techniques is applied systematically to 1p shell nuclei. Explicit calculations involve ground-state wave functions extracted from Cohen-Kurath effective interactions. For the double commutator expectation value we use a form of the potential consistent with the effective interaction and the giant dipole resonance energy. Results are given for N = Z nuclei, studying the minimal sensitivity with the parameter of the improved closure approach. The manifestations of SU(4) breaking are quantitatively shown. Within the uncertainties of the model the rates thus obtained compare reasonably well with experiment.

Self-consistent mean-field theory, progenitor sum rules, and the giant dipole resonance

Self-consistent mean-field theory gives an expression for the giant dipole resonance energy which depends on κ (the enhancement of the dipole sum rule by exchange currents). The value of κ needed to fit the GDR is much smaller than that obtained from the integrated photoabsorption cross section, in Suzuki's treatment. A corrected treatment which resolves this discrepancy is given here.

Widths of giant resonances from nuclear viscosity

The hydrodynamic two-fluid model of Steinwedel and Jensen (1950) for the explanation of the isovector giant dipole resonance energies is extended to include viscosity and is generalized to isoscalar and isovector resonances of arbitrary multipolarity. It is thus possible to calculate the energies as well as the widths of various giant resonances and to compare them with experimental data. Viscosity enters solely by the Navier-Stokes viscous forces and not by a phenomenological linear frictional force as has been previously employed.