Plastic scintillator fiber detectors for heavy ion trajectory reconstruction for the Super-FRS at FAIR

At the FAIR facility, currently under construction at GSI (Darmstadt), a 1.5 AGeV uranium beam with intensities up to 2.5 × 10 11 238 U/spill will impinge on a graphite target at the entrance of the Super-FRS for the production of a wide range of rare isotopes by projectile fission and fragmentation. The next generation in-flight magnetic separator Super-FRS, operated up to a magnetic rigidity of 20 Tm with a large angular acceptance (Δ θ = ± 40 mrad, Δ ϕ = ± 20 mrad) and momentum acceptance (Δ p/p = ± 2.5%), requires a new generation of tracking detectors with a position resolution of 0.2 mm ( σ x ) over large detector areas reaching up to 570 cm 2 . Besides gas detectors, planar detectors made of scintillating fibers are an option worth investigating not only because of the comparable material budget but especially for the fast response and high-rate capability. A one-dimensional prototype consisting of 128 fibers with active area of 25.6 × 100 mm 2 coupled to Multi-Pixel-Photon Counters (MPPCs) and readout by FPGA TDC is described together with some recent 197 Au beam test results.