Munira Khan ; Torben Ferber ; Kerstin Tackmann

2021
DESY Hamburg

Abstract: In the search for physics beyond the Standard Model, research in particle physics aims to probe particle interactions at high energies and strives for better precision on measurements. Experiments such as Belle II target higher luminosities to push the precision frontier. This requires stable detector performance and reliable identification of particles in environments with a large number of background processes, which leads to growing interest in new detector technologies. Pure caesium-iodide (CsI) scintillators are characterised by their fast scintillation time and high robustness against radiation, making them a promising calorimeter material. One of the first quantitative studies on the pulse shape discrimination (PSD) capabilities of pure CsI is performed in this thesis with the goal to distinguish electromagnetically and hadronically interacting particles. An experimental setup with a Thallium-doped CsI crystal, which is used at Belle II, and a single pure CsI crystal was designed and commissioned. Measurements near the beam dump of the European XFEL are performed. The charge ratio method, where the pulse shape is characterized based on the ratio of the integrated scintillation light output over different time gates, is applied in the analysis of the recorded data. It is found that pure CsI has PSD abilities in the probed energy range from 12 to 70\,MeV. The separation power to distinguish between muon-like and neutron-like pulse shapes is investigated for various short time gates from 40 to 200\,ns to determine the optimal integration time for PSD. The ideal short time gate is found to be at 100\,ns, which offers a separation of up to 95\% purity between the neutron-like and muon-like samples.

Note: Presented on 11 11 2021
Note: MSc