Distribution of the Gamow-Teller strength in90Nband208Bi

The ${(}^3\mathrm{He},t)$ charge-exchange reaction has been studied at ${E(}^3\mathrm{He})=450\mathrm{}\mathrm{MeV}$ and angles near $0°$ on targets of ${}^{90}\mathrm{Zr}$ and ${}^{208}\mathrm{Pb}.$ 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 ${}^{90}\mathrm{Nb}$ and in ${}^{208}\mathrm{Bi}$ has been calculated within the continuum quasiparticle random phase approximation and continuum-random-phase approximation approaches, respectively. These components, especially in ${}^{208}\mathrm{Pb},$ could be related with the direct, core polarization, and back-spin-flip Gamow-Teller strength.