Polarization transfer in (p,n) reactions at 318 and 494 MeV and the effective interaction

The polarization transfer observable [ital D][sub [ital L][ital L]](0[degree]) has been measured for [sup 2]H([ital [rvec p]],[ital [rvec n]])2[ital p], [sup 12]C([ital [rvec p]],[ital [rvec n]])[sup 12]N, and [sup 14]C([ital [rvec p]],[ital [rvec n]])[sup 14]N reactions with beam energies of 318 and 494 MeV. The deuterium results are in close agreement with free [ital NN] scattering constrained to the [Delta][ital J][sup [pi]]=1[sup +] channel. The results for the carbon targets, however, are systematically more negative than those for deuterium, which suggests a difference between the free and effective nucleon-nucleon interactions. Such a medium modification of the spin-dependent interaction may have important implications for intepretation of other intermediate-energy scattering experiments.