COMPARISON OF THE DOUBLE GIANT-DIPOLE STATES OBSERVED IN PI-, PI+) AND (PI+, PI-) REACTIONS ON CA-40 AND AL-27

The double isovector giant-dipole state has been observed in the (pi-, pi+) DELTA-T(z) = +2 and (pi+, pi-) DELTA-T(z) = -2 double-charge-exchange reactions on Ca-40 and Al-27. The resonances observed in the (pi-,pi+) reaction are closely related via Coulomb energy and isospin symmetry to the resonances measured in the inverse (pi+,pi-) reaction on the same nuclei. The new observations provide strong support for the identification of the double giant-dipole state in nuclei. The differences between the self-conjugate and non-self-conjugate cases are outlined.