Development of track reconstruction for the upgraded NA61/SHINE Vertex Detector

This thesis is dedicated to the upgraded Vertex Detector used in the NA61/SHINE experiment, i.e. its hardware and software. The performance of the improved software is demonstrated on simulation of D$^{0}$ mesons generated in Pb+Pb central collisions at 150A GeV/c. Moreover, an analysis of the acceptances and reconstruction efficiencies of the upgraded Vertex Detector for single particles (kaons and pions) and two particles (charm mesons D$^{0}$). The analysis was based on selected decay channel of the D$^{0}$ meson: \begin{equation} \text{D}^{0} \rightarrow \text{K}^{-} + \pi^{+} \end{equation} The thesis is divided into 12 chapters. In the first chapter (chapter 1) there is a physical description of heavy ion collisions and the formulation of the Standard Model. The next chapter (chapter 2) describes the NA61/SHINE experiment and a detailed explanation of the so-called open charm measurements which is the main physics program in the NA61/SHINE experiment. To carry out such studies, a specialized device is required, the so-called Vertex Detector (VD). The chapter 3 contains the description of the pilot version of VD used in the NA61/SHINE experiment, while the chapter 4 describes the reconstruction chain. During Long shutdown 2 (LS2), the Vertex Detector detector has been upgraded as described in the chapter 5. This required an upgrade of the VD software, which is described in the chapter 6. In the next two chapters (chapter 7 and 8) an analysis of acceptances and reconstruction efficiencies of single particles (kaons and pions) and D$^{0}$ mesons for the upgraded Vertex Detector are presented. The obtained results are presented in the chapter 9, while the conclusions are provided in the chapter 10. A final summary of the thesis and description of further steps are given in the chapter 11, while some additional figures used in this thesis are collected in the appendix (chapter Appendix).