The UA9 Experiment at the CERN-SPS

The UA9 experiment intends to assess the possibility of using bent silicon crystals as primary collimators to direct coherently the beam halo onto the secondary absorber, thus reducing out-scattering, beam losses in critical regions and radiation load. The experiment will be performed in the CERN-SPS in storage mode with a 120 or 270 GeV/c proton beam. The otherwise stable beam will be perturbed to create a diffusive halo. The setup consists of four stations: the crystal station with two goniometers for crystals, two tracking stations at about 90 degrees phase advance with detectors for single particle tracking and the collimation (TAL) station with a 600 mm long tungsten absorber. The observables are the localization of the losses in the collimation area, the collimation efficiency and the shape of the deflected beam phase space. We discuss the experimental layout and the way we expect to collect data in 2009.