Energy dependence of crystal assisted extraction at the CERN SPS

The feasibility of extracting particles from the halo of a circulating proton beam has been successfully demonstrated in an experiment at the SPS. Although most measurements were obtained at an intermediate energy of 120 GeV, more recently we had the opportunity to extract protons from a coasting beam at 14 GeV and 270 GeV, thus exploiting the full available energy range of the SPS. In this report we present a comparison of the measurements at the three energies and a qualitative comparison with the predictions