We study elastic Nα scattering and produce a quantitative correlation
between the range of the effective potential and the energy of the system. This
allows the identification of the waves and energies for which the scattering
may be said to be peripheral. We then show that the corresponding phase shifts
are sensitive to the tail of the NN potential, which is due to the exchange of
two pions. However, the present uncertainties in the experimental phase shifts
prevent the use of Nα scattering to discriminate the existing models
for the NN interaction.Comment: 19 pages, 6 PostScript figures, RevTeX, to be appear in Phys. Rev.