PREDICTION OF DEUTERON POLARIZATION FROM d - a SCATTERING

nuclei singles out the isotopic spin exchange part, Vb• of the neutron-proton interaction inside nuclei. Thus a comparison of the experimental cross section for this reaction with a detailed theoretical calculation of the cross section ought to provide the potential Vb of (2). It is important to note that no one has yet succeeded in calculating the correct absolute magnitude of the cross section for a direct interaction process. Levinson and Banerjee8 have given the most complete treatment in their study of proton inelastic scattering from C12• They found it necessary to use a direct interaction with a strength of more than twice the free nucleon -nucleon potential. These authors suggested that the increased effective interaction may arise from a polarization of the nucleons in the target nucleus. This effect would of course be absent in the interaction (1), if it is correct to think of the target nucleus as an inert core plus one neutron in a well -defined state. Moreover the (p, n) reaction involves unambiguously a nucleon -nucleon interaction, whereas inelastic scattering by direct interaction may proceed by particle excitation in the target, or by excitation of a collective state, and these two modes are not necessarily easily distinguished. 7 Thus the (p, n) reactions connecting the ground states of mirror nuclei are particularly suited to a rather direct measurement of the effective proton-neutron interaction in nuclei, or more specifically the charge exchange part of the interaction.