Comparison of the double giant in  (π^- ,π⁺) dipole states observed in and (π⁺ ,π^-) reactions on ⁴⁰Ca and ²⁷Al

The double isovector giant-dipolar state has been observed in the (π⁺ ,π^-) ΔT_z=+2 and (π⁺ ,π^-) ΔT_z=-2 double-charge-exchange reactions on ⁴⁰Ca and ²⁷Al. The resonances observed in the reaction are closely related via Coulomb energy and isospin symmetry to the resonances measured in the inverse (π⁺ ,π^-) 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.