Triple-GEM tracker and HCAL-J: two detectors for the study of Nucleon Form Factors at Jefferson Lab.

In the experimental Hall A of the Thomas Jefferson National Laboratory (JLab, USA/VA) is underway the integration and installation of the different equipments which will constitute the experimental setup of the new SBS (Super BigBite Spectrometer) physics program, largely devoted to the measurements of the electromagnetic Nucleons Form Factors; the SBS program will start data taking in September 2021. The present thesis work has focused on two key detectors of SBS: the GEM (Gas Electron Multiplier) based Front Tracker and the HCAL-J segmented hadron calorimeter. The latter is devoted mainly to provide the main trigger in the hadron arm, as well as the particles energy, the neutral pion identification and a course spatial correlation in high luminosity experiments; the former is an high spatial resolution charged particles tracker either in the electron or hadron arm, depending on the specific experiment of the SBS program. The thesis activities have been carried on in the group of researchers, within the INFN-JLAB12 collaboration, composed by the Physics Department of Catania, INFN of Catania, INFN of Bari, INFN of Genova and INFN of Rome, which has responsibilities in the development, construction, characterization and commissioning of both GEM Front Tracker and HCAL-J. Microscopic simulations based on ANSYS mechanical modeler and the CERN-GARFIELD++ library have been implemented to better understand and characterize the GEM chambers performances. The relative complexity of the development of the charge avalanche in the GEM layers has been investigated on different mechanical models, approaches and initial conditions. Ultimately the simulations have been validated by test-beam data. A central part of the thesis has involved the preparation, running and analysis of cosmic and LED based tests for the characterization and calibration of the HCAL-J sensors and electronics, primarily in terms of gains and time resolution of each module; the appropriate calibration of these parameters are fundamental for the operation of the whole calorimeter during the real experiment.