Determination of working channels in the Aerogel RICH of Belle II spectrometer

In 2018, the accelerator SuperKEKB in Japan and the Belle II spectrometer started their operations. At the beginning of a spectrometer operation researchers began the calibration process of all sub-detectors. In this master thesis we present the calibration of the Aerogel Ring Imaging Cherenkov detector (ARICH). ARICH sub- detector consists of an aerogel plane and a position-sensitive photon detector plane. We explore which channels of the photon detector detected photons when there were not any photons present and which channels have never detected any photons at all. Then we investigate how the number of none working channels changes throughout the Belle II spectrometer operation. In the end we explore how the none working channels influence the measurements of the Cherenkov angle. V začeteku leta 2018 je na Japonskem v pospeševalniku SuperKEKB začel obra- tovati spektrometer Belle II. Ob pričetku delovanja je potrebno spektrometer in njegove komponente umeriti. V magistrski nalogi opišemo potek umeritve detek- torja Čerenkovih obročev ali po angleško Aerogel Ring Imaging Cherenkov detector (ARICH). ARICH je sestavljen iz sloja aerogela in fotonskega detektorja, razdel- jenega na 60480 kanalov. V delu raziščemo, kateri kanali fotonskega detektorja zaznajo fotone, tudi ko fotonov ni bilo, in kateri kanali fotonov ne zaznajo nikoli. Nato pregledamo vpliv takšnih kanalov na meritve Čerenkovega kota in kako se število napačno delujočih kanalov spreminja tekom obratovanja spektrometra Belle II.