Construction and calibration of gaseous detectors at KAHVELab and CERN ATLAS experiment

Abstract

Gaseous detectors detect particles that interact electromagnetically. With different geometries, they can be used for many purposes from small scale table-top experiments to high energy collider experiments. In this thesis, rst the design, simulation and construction of a Delay Wire Chamber (DWC) at KAHVELab is described. Built to have the same specifications as those used at CERN beam lines, it has position resolution of 200?m and an active area of 10cm x 10cm. It has been tested with cosmic particles at KAHVELab and radioactive sources at the CERN gaseous detector laboratory, and shown to have a better gain than its counterparts at the CERN. Next, drift circle error calibration of a large collider-type gaseous detector the Transition Radiation Tracker (TRT) at ATLAS experiment is described. Drift circle errors are important for particle tracking. This calibration is performed using the pull sigma values of the drift circle error. Unlike earlier calibrations, the values are recorded in the database as a function of the mean number of the interactions per bunch. The pull sigma values approach unity as expected which validates the process. The ATLAS data and Monte Carlo comparisons are also observed to be consistent. Lastly, measurement of the t tV + t t contamination in Z+jets control region of an ATLAS exotic analysis is presented. Z reconstruction using electrons and muons is of critical importance for many studies and make use of the data from TRT as well as the other subdetectors. The measurement is done using multivariate analysis (multilayer perceptron). The method is veri ed with the pseudo-data, and the measured value from the pseudo-data template t is found to be within one sigma standard deviation of the expected value.