A scintillating fiber profile monitor for intense proton beams

We have built and tested a beam profile monitor for the proton beam directed to the Ks target of the NA48 experiment at the CERN SPS. The beam has a small cross-section of 3 × 6 mm2 and a total flux of 3 × 107 protons per pulse. The counter is constructed from two orthogonal sets of 20 square scintillating fibers covering an active area of 10 × 10 mm2. The fibers are read out in parallel with a 64-channel photomultiplier. The beam position can be measured in real-time with a resolution of 55 μm.