MEASUREMENTS OF HEAVY ION BEAM LOSSES FROM COLLIMATION

The collimation efficiency for 208Pb82+ ion beams in the LHC is predicted to be lower than requirements. Nu-clear fragmentation and electromagnetic dissociation in the primary collimators create fragments with a wide range of Z/A ratios, which are not intercepted by the secondary collimators but lost where the dispersion has grown suf-ficiently large. In this article we present measurements of loss patterns caused by a prototype LHC collimator in the CERN SPS. The loss maps show a qualitative difference between 208Pb82+ ions and protons, with the maximum loss rate observed at different places in the ring. This be-haviour was predicted by simulations and provides a valu-able benchmark of our understanding of ion beam losses caused by collimation