Experimental apparatus to study crystal channeling in an external SPS beamline

For the new generation of high intensity hadronic machines as, for instance, LHC, halo collimation is a necessary issue for the accelerator to operate at the highest possible luminosity and to prevent the damage of superconductor magnets.1 We propose an experiment aimed to a systematic study of channeling phenomenology and of the newly observed \volume re ection" eect. This experiment will be performed in an external SPS beamline and will make use of a primary proton beam with 400 GeV=c momentum and a very small ( 3 rad) divergence. An advantage of the proposed experiment is precise tracking of the particles that interacted with the crystal, so that to determine single-pass eciencies for all the processes involved. For the purpose, a telescope equipped with high-resolution silicon microstrip detectors will be used. New generation silicon crystals and an extra-precise goniometer are mandatory issues. Main goal of the experiment is the achievement of precise information on channeling of relativistic particles and, ultimately, on the feasibility of such technique for halo collimation in the LHC. In this contribution we review the status of the setting-up of the experimental apparatus and its future development in sight of the planned run in September 2006.