Fragmentation of Gamow-Teller strength observed inSn117,120(3He,t)117,120Sb charge-exchange reactions

The ${(}^3$He,t) charge-exchange reaction has been studied at E${(}^3$He)=200 MeV and angles near 0° on targets of ${}_{}{}^{117}{}_{}{}^{}\mathrm{Sn}$ and ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$. Fragmentation of the giant Gamow-Teller resonance into separate components of the particle-hole type has been observed in good agreement with theoretical predictions. These components are connected with what is usually referred to in the literature as direct-, core-polarization-, and back-spin-flip Gamow-Teller strength. The observed cross sections near θ=0° suggest contributions from the isovector spin-flip interaction as well as the isovector tensor interaction. A theoretically predicted configuration splitting of the main Gamow-Teller component into two components involving the 1${\mathit{h}}_{11/2}$ neutron orbital could not uniquely be identified. The data are compatible, though, with such a splitting since the observed widths of the main Gamow-Teller components in ${}_{}{}^{117}{}_{}{}^{}\mathrm{Sb}$ and ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sb}$ exceed the predicted splittings.