Study of Gas Electron Multiplier Detectors For The CMS Experiment At The LHC \& Its Application In Other Fields

The muon system of Compact Muon Solenoid (CMS) is intended for prompt and accurate identification of muons generated from proton-proton (p-p) collisions. The forward region of the end-caps was under-equipped and relied solely on Cathode Strip Chambers (CSCs), thus resulting in a lack of redundancy during Large Hadron Collider (LHC) Run-2. This lack of redundancy was projected to pose challenges with the upcoming High Luminosity-LHC (HL-LHC) upgrades, as increasing background rates were predicted to impact Level-1 (L1) trigger performance and, as a result, the selection of crucial physics channels. The integrity of the muon system will face additional challenges due to the ongoing upgrades to the LHC, especially in the high-rate environment, where there will be a 2.5-fold increase in instantaneous luminosity (L) to 5 × 1034 cm−2s−1. Furthermore, prolonged operation in a high-rate environment is expected to have a detrimental impact on the performance of the CSCs, thereby presenting a challenge to the overall performance of the muon system in the forward region. In response to increasing particle rates and the ageing of CSCs, the proposal to integrate Gas Electron Multiplier (GEM) detectors alongside existing CSCs was made. The CMS-GEM Collaboration proposed to strengthen the under-equipped high-η region with GEM detectors, referred as GEM End-cap Station 1 Ring 1 (GE1/1), GEM End-cap Station 2 Ring 1 (GE2/1), and Muon End-cap Station 0 (ME0) specific to their location in the CMS end-cap. This integration aimed to increase the precision of muon bending angle measurements, thereby improving muon trigger capabilities. GEMs, renowned for their high- rate handling capabilities, are especially well-suited for deployment in the forward regions of the CMS muon system. This doctoral thesis presents comprehensive research on GEM detector technology including four distinct studies. The initial study involves assembling the GE1/1 detectors and the execution of QC procedures on the assembled chambers at Panjab University, Chandigarh. Following this, the chambers were sent to Conseil Européen pour la Recherche Nucléaire (CERN) and integrated into the CMS experiment detector during Long Shutdown 2 (LS2). Currently, the installed GE1/1 detectors are actively collecting data during the ongoing Run-3, which started in July 2022. The second study is dedicated to precisely estimating the sensitivity of the triple-GEM GE1/1 detector to the significant background radiation inherent to CMS. These background radiations are mainly composed of neutrons and photons that are produced as a result of interactions with CMS detectors. These predicted sensitivity metrics serve to gauge the background radiation hit-rate within the GE1/1 region, aiding in the development of a predictive model for background radiation in anticipation of the upcoming GEM-based detector upgrade in the forward region. The evaluation of background hit-rates was estimated using FLUktuierende KAskade (FLUKA) + GEometry ANd Tracking (GEANT) simulation and is further validated using background data obtained from the GE1/1 Slice Test. This technique is presently undergoing another validation through the analysis of background data collected for GE1/1 detectors from the ongoing LHC Run-3. The third study in this thesis assesses the performance of blank and random-hole segmented GEM foils, specifically in the context of the ME0 detector upgrade. While blank segmentation was utilised in the photo-lithographic manufacturing technique of GE1/1 GEM-foils, the high-rate environment at the ME0 region necessitates the adoption of random-hole segmented foils for the ME0 detector. A beam test was conducted using a muon beam, involving assembled triple-GEM chambers, one containing blank segmented foils and another containing random-hole segmented foils. The performance of both types of GEM foils is thoroughly evaluated using ANalysis SYStem (ANSYS) + Garfield simulation, enabling a comparative analysis with experimental data. Finally, the fourth study discusses the expansion of GEM foil applications beyond the High-Energy Physics (HEP), specifically introducing a novel detection technique for Positron Emission Tomography (PET). This technique utilises the polarisation correlation inherent in the annihilation of positron and electron (in the case of parapositronium), producing two photons with orthogonal polarisation. A comprehensive research using a GEM-based detector prototype simulation has been conducted, with preliminary findings presented accordingly. The anticipated outcomes of this doctoral research effort are expected to make substantial contributions to advancing the upcoming GEM upgrades within the CMS. Ongoing research efforts are rigorously directed towards further refining the proposed detection technique, aiming to not only augment but also ensure the better quality and precision of imaging data.