Development of the quality test protocol for the DEPFET pixel detectors and top-quark mass measurement at high energy e+e- colliders

The Standard Model is the most accurate theoretical framework, capable to include all particles discovered and their interactions. It is the result of more than 100 years of research on particle physics, starting with the observation, by J.J. Thompson, of the so called "corpuscles", using a small Cathode Ray Tube; to the recent discovery of the Higgs boson, which required the collaboration of thousands of researches from all around the world and the largest and more sophisticated machine ever constructed by the human kind (the LHC). The need of an explanation to the nature phenomena is unstoppable and likewise the necessity of new machines to continue discovering them. On this context, several projects, with different approaches, are being developed. The discoveries performed by the LHC need to be complemented with high precision studies, which can be provided by the clean environment of an e+e- collider, such the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). These machines will cover the energy range from hundreds of GeV to the multi-TeV scale. On the other hand, the SuperKEKB, which uses e+e- interaction at intermediate energies, will generate unprecedented luminosities to study the B-anti_B processes with very high accuracy. The work presented here, entered on this context to perform a tiny contribution. The thesis was divided in two main topics. First part is dedicated to the study and development of a DEPFET-based pixel detector for e+e- collides. DEPFET is an active pixel technology, characterised by its excellent position reconstruction, its low material budget and low power consumption, which is capable to cope with all the requirement of the future e+e- colliders. For this reason, DEPFET is one of the candidates for the (ILC) and the baseline technology for the Belle II Pixel Detector (PXD) at the new Japanese Superflavour Factory SuperKEKB. On this context, the DEPFET prototypes for Belle II PXD will be presented, likewise, the process of construction of the PXD shell, to contextualize and motivated the development of a quality control protocol using a needles card. The process of design and test of the distinct needle card prototypes will be described, together with a proposed testing protocol. This work resulted in a complete setup, with all the mechanical parts, the electronic boards and software, mounted and prepared to be used during the PXD production. The second study is focused on the measurement of the top-quark mass. On this part a new observable, "B(mt,S)", will be introduced, which uses the cross section of the t-anti_t radiative events to obtain the mass of the top-quark in the continuum. The study has been performed on a high-energy e+e- collider scenario, to take advantage of this new environment and, potentially, reach unprecedented sensitivities. A partonic level study was done in order to obtain the maximum potential sensitivity achievable on the ILC-500 GeV physics scenario. The calculations were performed, independently, using the ISR and FSR particles and then, combining them. Afterwards, to approach towards a realistic study, the hadronization and the basic detector effects were included. Moreover, the study was extended to CLIC-380 GeV and ILC-1000 GeV. "B(mt,S)" does not require a specific interaction energy, for this reason, the calculation of the mass can be done not only over the production threshold but in the continuum. Therefore, the mass parameter can be defined on a good renormalization system, being sensitive to its running. On this context, the sensitivity to the running of the top-quark mass was probed. Finally, the study of the systematic errors were performed and a method to minimize their effects was proposed. The results obtained proved that the resolution of "B(mt,S)" are way below the methods currently used in hadron colliders and in the same order of the threshold measurement on the ILC.