Measurement and monitoring of electron swarm parameters for the time projection chambers in the T2K near detector

During an upgrade, the Tokai to Kamioka (T2K) long baseline neutrino oscillation experiment has implemented two additional Time Projection Chambers (TPCs) into the near detector. Thereby the total fiducial volume is now made up of about 50% Argon-based gaseous detection medium. To ensure high data quality and detector operation safety, the properties of the detector gas have to be well understood and should be monitored continuously. This thesis presents the design, construction, and performance of a new set of Gas Monitoring Chambers (GMCs) for the T2K-Experiment. They continuously measure the relative gas gain and electron drift velocity with high precision and are able to detect changes in the gas properties, such as contamination or leaks. A GMC specific THick Gas Electron Multiplier (THGEM) is proposed and first light measurements demonstrate the interchangeability of readout structures for future experiments. Given the increased interest in optical readout techniques in the gaseous detector community, a method of measuring the photons produced during the avalanche processes within the GMCs is implemented. Additionally, a new measurement device, based around a Proportional Counter Tube (PCT), is presented with the focus on measuring Penning transfer probabilities in arbitrary gas mixtures. As a proof of principle, various binary Argon-based mixtures are measured and compared to findings in the literature. The results are consistent with previous studies, and the first measurements for the ternary T2K gas mixture are provided. The combination of GMC and PCT measurements provide a complete set of swarm parameters for electron drift based gaseous detectors.