  The charge-exchange (3He,t) scattering to the isobaric analog state (IAS) of
the target can be considered as "elastic" scattering of 3He by the isovector
term of the optical potential (OP) that flips the projectile isospin.
Therefore, the accurately measured charge-exchange scattering cross- section
for the IAS can be a good probe of the isospin dependence of the OP, which is
determined exclusively within the folding model by the difference between the
neutron and proton densities and isospin dependence of the nucleon-nucleon
interaction. Given the neutron skin of the target is related directly to the
same density difference, it can be well probed in the analysis of the charge-
exchange (3He,t) reactions at medium energies when the two-step processes can
be neglected and the t-matrix interaction can be used in the folding
calculation. For this purpose, the data of the (3He,t) scattering to the IAS of
90Zr and 208Pb targets at Elab = 420 MeV have been analyzed in the distorted
wave Born approximation using the double-folded charge-exchange form factor.
The neutron skin deduced for these two nuclei turned out to be in a good
agreement with the existing database.
