Analog of theT>giant dipole resonance in light nuclei

Abstract

Giant resonances were observed in (${\mathrm{\ensuremath{\pi}}}^{+}$,${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$) double charge exchange on $^{13}\mathrm{C}$, $^{27}\mathrm{Al}$, and $^{59}\mathrm{Co}$ at excitation energies of 8.8, 14.2, and 27.9 MeV, respectively, where the giant dipoles built on the isobaric analog states are expected to appear. Partial angular distributions were measured for both $^{13}\mathrm{C}$ and $^{27}\mathrm{Al}$ and observed to have a dipole shape. The resonance on the T=1/2 targets has a single isospin value (T=3/2) and is the analog of the ${\mathit{T}}_{>}$ giant dipole state in the above nuclei. The results are in good agreement with photonuclear reactions and indicate a new general method for an accurate determination of the ${\mathit{T}}_{>}$=T+1 giant dipole state in T=1/2 nuclei.