Prototype radiators of a barrel DIRC for the PANDA experiment

The antiproton experiment PANDA at the future accelerator facility FAIR will among others be able to measure charmonium states with a hitherto unreached accuracy. In order to reach this goal a very good particle-identification ability is required. A good separation between pions and kaons is reached by application of a Cherenkov detector. The power of a DIRC depends on the quality of its radiator. In order to be able to specify the quality of the radiator rods, in the framework of this thesis an optical measuring apparature was developed. This setup allows to measure the transmission as well as the surface roughness of the rods. Several radiator rods of synthetic quartz glass and acryl glass were studied. The measurement accuracy at high-quality rods lies for the transmission measurement at about 1 % and for the roughness at 1-2 Aa. The measurement result at different wavelengths exhibit a good agreement with the scalar scattering theory, which describes the connection between reflection coefficient and roughness. At a beam time at the GSI with a 2 GeV proton beam a first prototype for the barrel DIRC with a rod of synthetical quartz glass as radiator was tested. By variation of the incident angle and the position of the proton beam on the radiator Cherenkov rings could be uniquely detected. Additionally the Cherenkov angle and the single-photon resolution was determined in good agreement with the expected and the simulation.