Learning about the structure of giant resonances from their γ decay

The direct gamma decays of the giant dipole resonance (GDR) and the giant quadrupole resonance (GQR) of Pb-208 to low-lying states are investigated by means of a microscopic self-consistent model. The model considers effects beyond the linear response approximation. The experimental gamma-decay widths from GQR to the first 3(-) state and the low-lying dipole states are well reproduced with the Skyrme interaction SkP. The strong sensitivity of gamma decay to the isospin of the involved states is proven. By comparing the decay widths between GDR to 2(1)(+) and GQR to 3(1)(-), a much larger weight of the 3(1)(-) component in the GQR wave function of Pb-208 is deduced, with respect to the weight of the 2(1)(+) component in the GDR wave function. Thus, we have shown that gamma decay is a unique probe of the resonance wave functions, and a test ground for nuclear structure models.

Automated summary

The direct gamma decays of the giant dipole resonance (GDR) and the giant quadrupole resonance (GQR) of Pb-208 to low-lying states were investigated using a microscopic self-consistent model, showing the sensitivity of gamma decay to the isospin of the involved states. The comparison of decay widths between GDR and GQR revealed differences in the composition of their wave functions, demonstrating that gamma decay serves as a unique probe of resonance wave functions and a test ground for nuclear structure models.