Simulation Studies of Muon Chamber System in Compressed Baryonic Matter Experiment

Paul, Souvik (2022) Simulation Studies of Muon Chamber System in Compressed Baryonic Matter Experiment. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Souvik Paul (17MS070)) 17MS070_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (7MB)

Abstract

The Compressed Baryonic Matter (CBM) experiment is a fixed target experiment at the upcoming Facility for Antiproton and Ion Research (FAIR) accelerators at Darmstadt, Germany. The main goal is to carry out precision measurements of the diagnostic probes of strongly interacting matter at extreme net-baryon densities, using the high-intensity heavy-ion beams. It is focused on finding the equation of state of baryonic matter, in-medium properties of hadrons and charmed particles, phase transitions at high net-baryon densities, hypernuclei, strange di-baryons and heavy multi-strange short-lived objects. The properties of the strongly interacting matter can be studied by the measurement of rare probes, such as (i) low mass vector mesons (ρ⁰, ω, ϕ), (ii) Thermal electromagnetic radiation, and (iii) Charmonium (J/ψ) dissociation. The rare probes decay via different modes. In CBM, we exploit the leptonic decay modes (such as e⁺e or ⁺ pairs) for their measurements because leptons do not participate in strong interactions with matter. Hence they carry undistorted information about the medium. The Muon Chamber (MuCh) of CBM has been designed to measure di-muon signals. It consists of alternating of detetor and absorber layers, enabling measurement of di-muons in a broad momentum range. For the first two stations of MuCh, which experience high particle rate, Gas Electron Multiplier (GEM) based tracking chambers have been implemented. The primary aim of this project is to understand the characteristic response of the MuCh detector in simulations. For this, one of the foremost requirement is the implementation of realistic detector components and materials in the MuCh geometry. We will then perform the transport and reconstruction in the CBMRoot framework. The simulation chain involves: (a) generating particles using Ultra-relativistic Quantum Molecular Dynamics (UrQMD) by simulating collisions, (b) transporting particles through all upstream detectors, their material, absorbers and tracking chambers using the Geometry and Tracking (GEANT) platform, (c) energy deposition, segmentation, digitization and hit formation, (d) track propagation in MuCh chambers, (e) selection of tracks as muon candidates, (f) reconstuction of di-muon tracks, and (g) analyses: transverse momentum spectra, invariant mass spectra, etc. This study would help us understand the impact of geometrical parameters on the invariant mass distribution of the di-muon sources. Di-lepton emissions from relativistic heavy-ion collisions forms the basis of this thesis work. Ch 1 and 2 introduces the CBM Experiment at FAIR and discusses the physics goals of the experiment. Emphasis has been laid on di-lepton physics. In Ch 3, we talk about the design of the MuCh detector system and the principle behind GEM technology. Ch 4 details our work in MuCh detector simulations, including material implementation, transport runs and di-muon analyses, and presents the results. We conclude our project work with Ch 5.

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