The Giessen Cosmic Station—A muon telescope for tests of particle detectors

The Giessen Cosmic Station (GCS) has been designed and built at the Justus Liebig University Giessen. It offers unique possibilities to commission particle detectors, especially Cherenkov detectors, using high energetic cosmic muons. The GCS consists of four tracking boxes with 192 scintillator bars, two trigger plates and a lead absorber to filter out low energy muons. GCS provides particle tracking with the resolution of 4.6 mm in position and 3.8 mrad in angle over the active area of $50\times 50$cm${}^2$ and with the muon rate of 0.2 particles/s including an energy cut of the trigger. By changing the geometry, the angular and position resolution can be further improved at the expense of the rate reduction. A trigger plate behind a lead absorber allows selection of high $\beta >0.989$ muons with kinetic energies above 600 MeV. The GCS has been designed to study the performance of the Endcap Disc DIRC (EDD) for the future PANDA experiment in Darmstadt which requires an excellent Particle Identification (PID) for pions and kaons up to 4.0 GeV/c momentum in EDD angular acceptance. Several measurements with cosmic muons and related Monte-Carlo simulations have been performed to validate the GCS design. The commissioning of the complete GCS setup was finished in 2019.