Speaker
Description
Precision electron identification is a critical challenge in electro/photo-production and deep-inelastic scattering experiments with large hadronic backgrounds. The GlueX-III experiment, planned to run at Jefferson Lab for 2027-2028, will significantly enhance the laboratory’s capability to explore charmonium production near threshold and related aspects of Quantum Chromodynamics in the non-perturbative regime. This talk will present the physics motivation for GlueX-III’s charmonium program, with emphasis on J/ψ photoproduction near threshold, its sensitivity to gluonic structure of nucleons, and the critical role of efficient electron-hadron separation for rejecting hadronic backgrounds and isolating rare dielectron final states. A central upgrade for GlueX-III, approved by the Jefferson Lab Program Advisory Committee in 2025, is a large-scale triple-GEM Transition Radiation Detector (TRD) optimized for electron identification and pion suppression in the hadron-rich environment of fixed-target photoproduction. We will describe the design, construction, and in-beam performance of a 720x528 mm2 triple-GEM-TRD prototype tested in the existing GlueX-II experimental acceptance during the 2025 run, including detector stability, timing performance, and transition radiation cluster identification. The detector’s integration with the GlueX tracking system is anticipated to improve the overall momentum resolution of the experiment. Its projected impact on signal purity and systematic uncertainties of the cross-section measurement will also be discussed. Simulation studies on detector performance related to electron/pion separation will be presented. Reconstruction of dielectron final states using data collected with the detector during the GlueX-II run will also be demonstrated. This talk will outline how the development and use of a modern TRD technology in a high-background environment at Jefferson Lab stands to directly inform detector design choices as a future upgrade path for the Electron-Ion Collider (EIC). There, precise electron identification amidst vast hadronic backgrounds and high rates will be essential for a broad expanse of physics measurements. The detector simulations can also be readily applied to the Electron-Ion Collider environment, to better demonstrate the advantages of a GEM-based TRD for the planned EIC physics program.
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