Electronic Theses and Dissertations (Masters)

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Browsing Electronic Theses and Dissertations (Masters) by Author "Mellado, Bruce"

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    Leveraging Machine Learning in the Search for New Bosons at the LHC and Other Resulting Applications
    (University of the Witwatersrand, Johannesburg, 2023-09) Stevenson, Finn David; Mellado, Bruce
    This dissertation focuses on the use of semi-supervised machine learning for data generation in high-energy physics, specifically to aid in the search for new bosons at the Large Hadron Collider. The overarching physics analysis for this work involves the development of a generative machine learning model to assist in the search for resonances in the Zγ final state background data. A number of Variational Auto-encoder (VAE) derivatives are developed and trained to be able to generate a chosen Monte Carlo fast simulated dataset. These VAE derivatives are then evaluated using chosen metrics and plots to assess their performance in data generation. Overall, this work aims to demonstrate the utility of semi-supervised machine learning techniques in the search for new resonances in high-energy physics. Additionally, a resulting application of the use of machine learning in COVID-19 crisis management was also documented.
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    The development of a burn-in test station at Wits for the Phase-II upgrade of the Tile Calorimeter of the ATLAS experiment
    (University of the Witwatersrand, Johannesburg, 2023-07) Njara, Nkosiphendule; Mellado, Bruce
    The University of the Witwatersrand is responsible for producing over 1200 Low Voltage Power Supply (LVPS) bricks to power the on-detector electronics of the Tile Calorimeter (TileCal) of the ATLAS detector in preparation for the Phase II upgrade. The LVPS brick is a DC/DC switch-mode power supply module that steps down a 200 VDC input to a 10 VDC output. Before being sent to CERN for installation, the LVPS bricks must undergo a quality assurance test. To ensure that these electronic devices meet the necessary standards for high-quality and reliability, the University of the Witwatersrand employs a burn-in test station that subjects them to electronic tests at elevated temperatures and other stressful conditions. The burn-in test station comprises of different Printed Circuit Boards (PCBs), each responsible for various functions, and a PIC microcontroller needs to be programmed for each board to perform its respective functions. An assembler MPLABX IDE and a compiler (CCS) are used for programming the PIC microcontroller, and the Labview software is used as the control program for the burn-in test station. A simulation was used in Proteus software to test the firmware functionality before programming the hardware. Preliminary results of the current version (version 8.4.2) of the LVPS brick are discussed.
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    The development of a burn-in test station for the ATLAS Tile Calorimeter Low Voltage Power Supplies for phase II upgrades
    (University of the Witwatersrand, Johannesburg, 2022) Lepota, Thabo James; Mellado, Bruce
    It is planned that the High Luminosity (HL) function of the Large Hadron Collider (LHC) will begin operation in 2027 with an integrated luminosity of 4000 fb−1.By using the HL-LHC scientists will be able to investigate new physics beyond the Standard Model (SM), examine electroweak symmetry in more detail, and examine the characteristics of the Higgs boson. The ATLAS Tile Calorimeter’s on and off detector electronics will be completely redesigned during phase II upgrade, run 3. Due to the high radiation levels, trigger rates, and high pile-up conditions associated with the HL-LHC era, it will be necessary to accommodate its acquisition system. The Institute of Collider Particle Physics is responsible for developing and manufacturing over a thousand transformer-coupled buck converters, known as Bricks, for the Low Voltage Power Supply (LVPS) system. The LVPS is critical to the TileCAL on detector electronics as it powers them by converting 200 V high voltage to 10 V. The Bricks are located within the inner barrel, they can only be accessed once a year. If an LVPS box fails, it can be down for up to a year, causing the Front-End electronics it supports to remain offline for the same amount of time. As a result, the Bricks’ reliability is of critical concern that must be addressed throughout their manufacturing process. In addition to the burn-in test station, the Bricks that pass the quality assurance tests are sent to the European Organization for Nuclear Research (CERN), to be installed in the ATLAS detector. In this manuscript, we show how we programmed the Peripheral Interface Controller (PIC) firmware, which is an integral part of the Brick Interface board functionality in the burn-in test station. We further give detail as to how the software framework (LabVIEW) used as a control program was modified and used to operate the burn-in test station during the burn-in process. The purpose of the test results discussed is to demonstrate the burn-in test station is functional according to the preliminary protocols prescribed for Bricks