Produkcja mezonu $\phi$ w oddziaływaniu $\textit{pp}$ przy energii 3.5 $\textit{GeV}$ z użyciem detektora HADES

The High Acceptance Di-Electron Spectrometer (HADES) working at GSI Darmstadt is an unique apparatus aiming for systematical investigations of dilepton and strangeness production in elementary and heavy ion collisions in 1-4 $\textit{AGeV}$ energy range. Measurements performed with this spectrometer in heavy ion and proton-nucleus collisions aim in investigation of hadron properties in nuclear matter. In wide scope of the HADES physics program the investigations of hadron production in elementary collisions are also foreseen. In the framework of this dissertation the exclusive $\phi$ meson production in proton-proton reactions at 3.5 $\textit{GeV}$ kinetic energy is presented. The ratio $\phi$ to $\omega$ production cross section has been obtained and discussed in connection to the OZI rule violation phenomena. Description of the analysis methods, which leads to estimation of the $pp \to pp\phi$ meson production cross sections is presented. This is followed by a comparison of the extracted φ meson production characteristics with the simulation of this reaction channel. In the simulation an isotropic $\phi$ angular distribution in the Center of Mass (CM) frame of colliding nucleons and an uniform phase space population in the proton-meson Dalitz distribution are assumed. A good agreement of the measured angular, momentum and proton-$\phi$ invariant mass distributions with the simulation have been achieved. The extracted exclusive $\phi$ production cross section at 3.5 $\textit{GeV}$ kinetic energy equals: $\sigma_{\phi}^{4\pi} = 1.05[\mu b] \pm 0.2[\mu b](stat.) \pm [\mu b](syst.)$ The exclusive $\omega$ production cross section obtained in this experiment allows to calculate the ratio of $\phi$ to $\omega$ production cross section which equals: $R_{\phi/\omega} = 0.0099 \pm 0.0018(stat.) \pm 0.0012(syst.)$ The obtained ratio is close to the one measured in pion-nucleon reaction which exceeds by factor $\sim$ 2-3 OZI rule predictions. In the second part, selected tasks of the HADES data acquisition (DAQ) system upgrade, which were in responsibility of the author of this thesis, are described. They concerned mainly following aspects: • developing, testing and validating of the central trigger system (CTS), • developing, testing and validating of the readout electronics for RPC, START, VETO, Forward Wall and TOF detectors. The newly developed HADES DAQ system, as it is presently used in ongoing Au+Au campaign, with its trigger distribution scheme, front-end boards and readout components are described as well