The SPS Target Station for CHORUS and NOMAD Neutrino Experiments

A new SPS target station, T9, has been constructed for the CHORUS and NOMAD neutrino experiments at CERN. The heart of the station is the target box : 11 beryllium rods are aligned in a cast aluminium box ; they are cooled by a closed circuit helium gas with adjusted flow to each rod. The box is motorised horizontally and vertically at both ends, to remotely optimise the secondary particle production by aligning the target with the incident proton beam. Radiation protection around the station is guaranteed by more than 100 tons of shielding material (iron, copper, marble). This presentation describes briefly the various components of the target station ; it emphasises particularly the thermal and mechanical calculations which define a safe maximum beam intensity on the beryllium rods. Over the first two years of successful operation, the station has received more than 2€1019 protons at 450 GeV/c, with intensity peaks of 2.8€1013 protons per machine cycle.