Evidence for three nucleon force effects in p-d elastic scattering

A new measurement of the p-d differential cross section at E{sub p}=1 MeV has been performed. These new data and older data sets at energies below the deuteron breakup are compared to calculations using the two-nucleon Argonne v{sub 18} and the three-nucleon Urbana IX potentials. A quantitative estimate of the capability of these interactions to describe the data is given in terms of a {chi}{sup 2} analysis. The {chi}{sup 2} per datum drastically improves when the three-nucleon interaction is included in the Hamiltonian.