Distribution of the Gamow-Teller strength in Nb-90 and Bi-208

The (He-3,t) charge-exchange reaction has been studied at E(He-3)=450 MeV and angles near 0 degrees on targets of Zr-90 and Pb-208. Fragmentation of the Gamow-Teller (GT) strength into separate components of the particle-hole type has been observed. The distribution of the GT strength in Nb-90 and in Bi-208 has been calculated within the continuum quasiparticle random phase approximation and continuum-random-phase approximation approaches, respectively. These components, especially in Pb-208, could be related with the direct, core polarization, and back-spin-flip Gamow-Teller strength.