Double giant resonances in pion double charge exchange on V51, In115, and Au197

Resonances were observed in the continuum in pion-induced double charge exchange (at Tπ=295 MeV) on V51 at Q=-14.0, -32.4, and -48.0 MeV, on In115 at Q=-25.0, -37.3, and -49.6 MeV, and on Au197 at Q=-35.0, -44.3, and -54.9 MeV. The three resonances have different characteristic angular distributions. Partial angular distributions were measured on V51 and In115 and observed to have Jπ=0+, 1-, and 2+ shapes, respectively. Based on their centroid energies, angular distributions, and observed cross sections, we identify the resonances as the double isobaric analog state, the giant dipole built on the isobaric analog, and the double giant dipole resonance. The new observations are in close agreement with the gross features reported recently for the double giant resonances, and provide some of the best signals obtained to date for the double resonance states in nuclei.