Tests of the data acquisition system and detector control system for the muon chambers of the CMS experiment at the LHC

The Phys. Inst. III A of RWTH Aachen University is involved in the development, production and tests of the Drift Tube (DT) muon chambers for the barrel muon system of the CMS detector at the LHC at CERN (Geneva). The thesis describes some test procedures which were developed and performed for the chamber local Data Acquisition (DAQ) system, as well as for parts of the Detector Control System (DCS). The test results were analyzed and discussed. Two main kinds of DAQ tests were done. On the one hand, to compare two different DAQ systems, the chamber signals were split and read out by both systems. This method allowed to validate them by demonstrating, that there were no relevant differences in the measured drift times, generated by the same muon event in the same chamber cells. On the other hand, after the systems were validated, the quality of the data was checked. For this purpose extensive noise studies were performed. The noise dependence on various parameters (threshold, HV) was investigated quantitatively. Also detailed studies on single cells, qualified as "dead" and "noisy" were done. For the DAQ tests a flexible hardware and software environment was needed. The organization and installation of the supplied electronics, as well as the software development was realized within the scope of this thesis. The DCS tests were focused on the local gas pressure read-out components, attached directly to the chamber: pressure senso r, manifolds and the pressure ADC (PADC). At first it was crucial to proof, that the calibration of the mentioned chamber components for the gas pressure measurement is valid. The sensor calibration data were checked and possible differences in their response to the same pressure were studied. The analysis of the results indicated that the sensor output depends also on the ambient temperature, a new experience which implied an additional pedestal measurement of the chamber gas pressure sensors at CMS. The second test sequence considered the gas pressure read-out quality. This kind of test used data obtained during the CMS Magnet Test and Cosmic Challenge (MTCC). The signal of two sensor types measuring the same gas pressure at the same time were compared. Also the stability of the sensor output, as well as of the sensor supply voltage were analyzed at different magnetic field values. To perform the mentioned DCS tests a complex software system was developed. This system merges the sensor and calibration data to obtain the final pressure values for each possible sensor/PADC/chamber combination. This proceeds fully automatically by connecting to the diverse internal and external databases, by finding proper data, performing calculations and creating the Look Up Tables (LUT).