The Origin of the Giant Dipole Resonance

Understand

The Giant Dipole Resonance (GDR), which is conventionally described as due to collective motion, is instead shown to be the result of a sudden increase in level density at the 2h{\omega} shell closure.

• The energy of the GDR closely follows the shell model harmonic oscillator energy model where h{\omega} = 39A^-1/3, for heavy nuclei.
• A better fit covering the entire mass range is given by h{\omega} = 47:55(0:13)(A^-1/3 - A^-2/3).
• The GDR is shown to be composed of a lower energy peak, E1, corresponding to the population of levels with oblate deformation and a higher energy peak, E2 corresponding to the population of levels with prolate deformation.