Transverse drift speed measurement of the halo in a hadron collider

In a high luminosity hadron collider, the particles in the halo diffuse towards the vacuum chamber wall and depose their energy in the surrounding material. This may be in the superconducting coils of the magnets which, beyond a certain limit of energy deposition, will provoke a quench. Therefore sophisticated collimator systems have to be provided. But the efficiency of such a system is strongly related to the characteristics of the particles in the halo which are determined by their transverse drift speed. Studies and measurements of the transverse drift speed have been made on the CERN SPS running in the proton-antiproton collision mode. The results of these measurements have already been used to estimate the protection against beam losses of the future LHC. (author)