Charm production in the OPERA experiment and the study of a high temperature superconducting solenoid for a liquid argon time projection chamber

The OPERA Experiment (Oscillation Project with Emulsion tRacking Apparatus) is a long baseline neutrino oscillation experiment aiming for the first observation of $\nu_{\tau}$- appearance in a nearly pure $\nu_{\mu}$-beam (with a small $\nu^{e}$-contamination). The CERN Neu- trinos to Gran Sasso (CNGS) beamline has a length of 730 km and was optimized for detecting the appearance of $\tau$-neutrinos through the reconstruction of $\tau$-decays after a $\nu_\tau$ charged current interaction. The oscillation amplitude (probability) depends on the mixing angle µ23 of the Pontecorvo Maki Nakagawa Sakata (PNMS) matrix elements, which is close to 45 , i.e. the mixing is maximal. The OPERA experiment is situated in the underground hall C of the Laboratori Nazionali del Gran Sasso (LNGS) in a highway tun- nel near L'Aquila (Italy). For five years of running at the nominal beam intensity, about ten reconstructed $\tau$-decays are expected. Since at the CNGS energies the probability of a $\nu_\mu$ to oscillate on its way from CERN to LNGS into a $\nu_\tau$ is only a few percent, most of the interactions in the OPERA target are $\nu_\mu$ charged and neutral current interactions (CC,NC). In the charged current interaction the energy of the primary interaction is high enough to allow charm production in about 4% of the events. Since the lifetime and the masses of charm and $\tau$ particles are similar, the main goal of this thesis is to demonstrate the efficient reconstruction of charm events in the OPERA detector, proving the principle for detection of short lived particles. Also the background of charm decays in the OPERA experiment was studied and is presented here. Furthermore, the engineering and R&D studies for a magnetized liquid argon time pro- jection chamber (LAr TPC) using high temperature superconductors (HTS) are presented in the appendix.