Commissioning of the new photon tagger of the BGO-OD experiment at ELSA

The BGO-OD Experiment, currently under construction at ELSA at the University of Bonn, is setup to investigate the photoproduction of mesons. Therefore, an electron beam provided by ELSA is used to produce Bremsstrahlung on a thin radiator. To determine the energy of the Bremsstrahlung, the electrons momenta are analysed through a dipole magnet which bends them into a hodoscope. It consists of 120 coincidence channels which cover an energy range from 10% to 90% of the incoming electron beam energy E₀. Due to geometrical constraints, the expected energy width of two overlapping scintillators varies from 0.4% to 1.7% of E₀. The optimum positions of the scintillators and the expected energy resolution were determined via Virtual Monte Carlo/Geant4. The commissioning of the tagger hodoscope was finished with a final energy calibration, the results of which agree perfectly with simulations.