Abstract
We report the first observation of a double isovector giant dipole state in nuclei (i.e., an isovector giant dipole resonance built on another giant dipole). Two new resonances were observed in () double charge exchange (at MeV) on at excitation energies of 24.7 and 28.7 MeV. The energy centroid is very close to the energy at which the double dipole () state is expected to appear. The angular distributions for the resonances have a clear quadrupole shape. The measured cross sections and the angular distribution agree well with a simple sequential two-step calculation in which single charge exchange through the giant dipole resonance to the double dipole is evaluated.
- Received 4 April 1988
DOI:https://doi.org/10.1103/PhysRevLett.61.531
©1988 American Physical Society