Inbetriebnahme eines schnellen Photondetektors für den ringabbildenden Cerenkov-Detektor am COMPASS-Experiment

This thesis is dedicated to the characterisation and comissioning of the new photon detection system of the upgraded COMPASS-RICH-1 detector and its new readout electronics. The jitter of the digital part of the readout electronics versus a reference TDC-CMC was determined to be (192 ± 2) ps. The time resolution of the entire readout chain, consisting of a multi-anode photo-multiplier, a pre-amplifier/discriminator and the digital electronics, was measured to be (323 ± 3) ps. The crosstalk between different channels of the whole readout chain was measured to be negligible, as it is below 1h. In order to test the new photon detection system including readout whenever necessary, a test system consisting of two LEDs inside the RICH vessel was designed and installed. The effective time window containing all relevant entries for physics analysis was determined after analysing the time distribution within all channels and within Cherenkov rings on an event by event basis. The T0 calibration ensures a central position of the time peak for all channels. An offline cut of ±4.5 ns around this time peak leads to a reduction of the background by a factor of 10. The new detector shows a performance as good as and better than expected from the design studies. It has been included sucessfully in the COMPASS experiment since the beginning of the 2006 data-taking period.