Global ETD Search

41	Dark Matter signals at the Large Hadron Collider with Deep Learning Andersson, Max, Glöckner, Edward, Löfkvist, Carl January 2023 (has links) While holding a firm position in popular culture and science fiction, Dark Matter (DM) is nonetheless a highly relevant topic at the forefront of modern particle physics. We study the applicability of characterizing DM particle candidates SUSY neutralino and sneutrino using Deep Learning (DL) methods. We focus on the monojet and mono-Z signatures and the emergence of missing transverse energy as the result of the undetectable DM candidates. Based on kinematic distributions of outgoing particles as input, a DM candidate classifier is built for each signature, along with a DM mass regressor. The DM candidate classifier obtained near perfect accuracy of 0.995 for the monojet, and 0.978 for mono-Z signature. The monojet and mono-Z mass regressors achieved a Mean Absolute Percentage Error (MAPE) of 17.9 % and 8.5 % respectively. Furthermore, we discuss both the shortcomings and simplification that our choice of model implied, as well as an interpretation of the results. Finally, we debate the prospects of DL in the discovery of new physics and it's use in experiments. Machine Learning Dark Matter Classification Regression Particle Physics Supersymmetry LHC CERN Computer Sciences Datavetenskap (datalogi) Accelerator Physics and Instrumentation Acceleratorfysik och instrumentering Subatomic Physics Subatomär fysik
42	Intelligent Trigger System for RNO-G and IceCube-Gen2 Liland, Lukas January 2022 (has links) Artificial intelligence (AI) and deep learning have made a full impact on society the last decades, including the realm of particle physics. This thesis explores whether a neural network, a deep learning program mimicking the biological brain, can be used to reject noise in real time at the Radio Neutrino Observatory in Greenland (RNO-G). RNO-G aims to detect radio waves in the ice cape of Greenland, induced by ultra high energy neutrinos ($>10^{18}$ eV). Due to the low flux of neutrinos at these energies, it is desired to increase the sensititivty of RNO-G by lowering the trigger threshold as much as possible. However, lowering the threshold is currently limited by unavoidable thermal noise fluctuations that would otherwise saturate the detector. Previous research has shown that a neural network could be used on a similar neutrino detector, ARIANNA, to reject thermal noise in real time, thus making it possible to lower the trigger threshold below the noise floor. This thesis aims to do the same for RNO-G. Ultra high energy neutrinos radio detection deep learning Natural Sciences Naturvetenskap Astronomy, Astrophysics and Cosmology Astronomi, astrofysik och kosmologi Accelerator Physics and Instrumentation Acceleratorfysik och instrumentering Subatomic Physics Subatomär fysik
43	Demonstrating reliableinstrumentation in theATLAS Tile Calorimeter : Fault tolerance and redundancy in hardware and firmwarefor the Phase-II Demonstrator project in preparation forHigh Luminosity LHC at CERN Åkerstedt, Henrik January 2024 (has links) The Large Hadron Collider at CERN is scheduled to undergo upgrades in 2026-2028 to significantly increase its luminosity. These upgrades, while providing the experiments with a higher collision rate, pose a number of challenges to the design of the hardware and software in the detectors. The Tile Calorimeter (a scintillating sampling calorimeter read out by photomultiplier tubes) at the ATLAS experiment will have its read-out electronics completely replaced to enable performance and reliability improvements. Advances in electronics, new requirements due to the luminosity upgrade as well as lessons learned from the current readout scheme drove development with the goals to partition the readout into small independent units with full granularity readout and a robust mitigation strategy for radiation induced errors. To verify the functionality of the new system while retaining backward compatibility a "Demonstrator'' has been developed to emulate the current functionality while using new and improved hardware. The board responsible for managing digitized calorimeter data and communicating with the off-detector electronics, called the DaughterBoard, is the main focus of this thesis. It has two electrically isolated sides for redundancy where each side consists of voltage regulators, two optical transceivers, a GigaBit transceiver chip (for clocking and configuration) and a Kintex FPGA for data processing. In addition to data management and transmission, the FPGA (and every other component) needs to be able to withstand the effects of radiation both in terms of total dose (ionization and displacement damage) and due to single event effects. The DaughterBoard was developed with this in mind and has undergone several radiation tests during its development to verify reliability and fault tolerance. / CERN CERN ATLAS Tile calorimeter TileCal FPGA SEU TMR Kintex Demonstrator DaughterBoard Radiation testing Radiation tolerant Accelerator Physics and Instrumentation Acceleratorfysik och instrumentering Physical Sciences Fysik
44	Designing radiation protection for a linear accelerator : using Monte carlo-simulations / Framtagning av förslag på förstärkt strålskydd för en linjäraccelerator : med hjälp av Monte Carlo-simuleringar Lindahl, Jonatan January 2019 (has links) The department of Radiation Sciences at Umeå University has obtained an old linear accelerator, intended for educational purposes. The goal of this thesis was to find proper reinforced radiation protection in an intended bunker (a room with thick concrete walls), to ensure that the radiation outside the bunker falls within acceptable levels. The main method was with the use of Monte Carlo-simulations. To properly simulate the accelerator, knowledge of the energy distribution of emitted radiation was needed. For this, a novel method for spectra determination, using several depth dose measurements including off-axis, was developed. A method that shows promising results in finding the spectra when measurements outside the primary beam are included. The found energy spectrum was then used to simulate the accelerator in the intended bunker. The resulting dose distribution was visualized together with 3D CAD-images of the bunker, to easily see in which locations outside the bunker where the dose was high. An important finding was that some changes are required to ensure that the public does not receive too high doses of radiation on a public outdoor-area that is located above the bunker. Otherwise, the accelerator is only allowed to be run 1.8 hours per year. A workaround to this problem could be to just plant a thorn bush, covering the dangerous area of radius 3m. After such a measure has been taken, which is assumed in the following results, the focus moves to the radiation that leaks into the accelerator’s intended control room, which is located right outside the bunker’s entrance door. The results show that the accelerator is only allowed to be run for a maximum of 6.1 or 3.3 hours per year (depending on the placement of the accelerator in the room), without a specific extra reinforced radiation protection consisting mainly of lead bricks. With the specific extra protection added, the accelerator is allowed to be run 44 or 54 hours per year instead, showing a distinct improvement. However, the dose rate to the control room was still quite high, 13.7 μGy/h or 11.2 μGy/h, compared to the average dose received by someone living in Sweden, which is 0.27 μGy/h. Therefore, further measures are recommended. This is however a worst case scenario, since the leakage spectrum from the accelerator itself was simulated as having the same energy spectrum as the primarybeam at 0.1 % of the intensity, which is the maximum leakage dose according to the specifications for the accelerator. This is probably an overestimation of the intensity. Also, the energy spectra of the leakage is probably of lower energy than the primary beam in at least some directions. Implementing more knowledge of the leak spectra in future work, should therefore result in more allowed run hours for the accelerator. linac linear accelerator accelerator mega voltage photons spectra determination high energy photons Monte carlo simulations radiation transport dose radiation radiation protection Accelerator Physics and Instrumentation Acceleratorfysik och instrumentering Atom and Molecular Physics and Optics Atom- och molekylfysik och optik Other Medical Engineering Annan medicinteknik
45	Exotic Decays of a Vector-liketop Partner at the LHC Skwarcan-Bidakowski, Alexander January 2019 (has links) An evaluation of how sensitive some ATLAS searches for new physics are to a new beyond standard model (BSM) vector-like quark (VLQ) and a pseudo Nambu-Goldstone boson (pNGB) scalar. This was done by simulating a signal containing these new particles and making a recast of it onto existing verified ATLAS searches for new physics at center-of-mass (CM) energy of 13 TeV (Run 2) at the Large Hadron Collider (LHC). Signals for recasting were tailored such that their final states would be appropriate in relation to each respective ATLAS search in order to use the same selection criteria as applied in the existing searches. The results are summarized in the form of significances (Z) for each masspoint of the new top-partner and S particle. Significances did not show any expectiation of excluding any masspoint in the examined mass range for the recasts at 95% CL. This suggests that a dedicated search for these particles in the considered masspoints would be required. Particle physics Vector-like quarks VLQ Composite Higgs model CHM Top-partner pseudo Nambu-Goldstone boson pNGB NGB ATLAS LHC CMS Significance Recast CheckMate CM MadGraph Pythia Delphes Detector Analysis Hierarchy Problem Exotic Decay QFT Quantum Field Theory fermions bosons Jets photons leptons 13 TeV Missing Transverse Energy momentum hypothetical selection criteria Standard model Signal background event Higgs Mechanism Simulation Confidence limit Other Physics Topics Annan fysik Accelerator Physics and Instrumentation Acceleratorfysik och instrumentering Subatomic Physics Subatomär fysik

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