Isospin character of the giant quadrupole transition inSn124

Use has been made of the interference between the nuclear and Coulomb amplitudes in the scattering of 84 MeV/nucleon ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ ions by ${}_{}{}^{124}{}_{}{}^{}\mathrm{Sn}$ to study the isospin character of the giant quadrupole transition. The data are well described by assuming the transition is ‘‘isoscalar,’’ i.e., ${\mathit{M}}_{\mathit{n}}$/${\mathit{M}}_{\mathit{p}}$=N/Z. This is in disagreement with the results of ${\mathrm{\pi }}^{+}$/${\mathrm{\pi }}^{\mathrm{-}}$ scattering on ${}_{}{}^{118}{}_{}{}^{}\mathrm{Sn}$ and recent (e,e’n) measurements on ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$. Cross sections for excitation of the $2^{+}$ state at 1.132 MeV, $3^{\mathrm{-}}$ state at 2.614 MeV, and giant monopole resonance are included with corresponding coupled-channels calculations.