Determination of theHe4-He4Repulsive Potential up to 0.14 eV by Inversion of High-Resolution Total—Cross-Section Measurements

High-resolution measurements of the ${\mathrm{He}}^4$-${\mathrm{He}}^4$ total scattering cross section are presented for reduced collision energies between 0.2 and 200 meV. Clear evidence for the Ramsauer-Townsend effect is observed and thirteen backward glory extrema are resolved. From these extrema we derive the energy dependence of the $s$ phase shift. Applying the semiclassical inversion method proposed by Miller we then compute the repulsive potential up to 0.14 eV.