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A Burn-in Test Station for the Transformer-Coupled Buck Converter Boards within the Low Voltage Power Supplies of the ATLAS Tile Calorimeter
No full textA comprehensive quality assurance testing procedure is developed to ensure the reliability of transformer-coupled buck converter boards (Bricks) within the ATLAS hadronic Tile Calorimeter (TileCal). With the impending Phase-II upgrades of the TileCal, which will contribute to the success of the forthcoming High-Luminosity Large Hadron Collider, ensuring the reliability of the Bricks in the TileCal's Low Voltage Power Supply (LVPS) system is essential. There are 256 LVPS Boxes within the TileCal, each equipped with eight Bricks that step down 200 V DC power received from the off-detector electronics to the voltage required by the on-detector front-end electronics. As part of the Phase-II upgrades in South Africa, we’re taking a significant role in production by manufacturing half of all the Bricks required. Access to the Bricks is limited to once per year during the Year-End Technical Stops due to their location within the inner barrel of the ATLAS detector. As a result, if a Brick failure occurs, it may be offline for up to one year, with the front-end electronics to which it supplies power being offline for a commensurate period. Establishing a Burn-in test station is essential, aimed at subjecting LVPS Bricks to accelerated aging to stimulate failure mechanisms and screening out defective Bricks that would compromise the detector’s performance. By ensuring the reliability of the final population of Bricks installed, we minimize instances of the front-end electronics being offline, thus improving detector performance and data integrity
CERN ion injector complex performance during 2024 magnesium test
No full textIn the second quarter of 2024 a new ion species, magnesium, has been tested in the CERN's ion injector complex. The test aimed at preparing the complex for the operation with magnesium beams as it is one of the species requested by the NA61/SHINE experiment for Run 4 (2030-2033). Furthermore, potential show-stoppers should be identified as early as possible. This note describes the beam commissioning steps and presents the performance achieved in Linac3, LEIR, and PS. The intensity reach, transmission efficiencies, and typical beam emittances are also reported. Finally, observed limitations and possible mitigation measures are discussed
South Africa’s Contribution to the Upgrade of the ATLAS TileCal low voltage power supply for the HL-LHC
No full textThe start of the operation of the High Luminosity LHC (HL-LHC) is planned for the year 2030. The associated increase in luminosity provides an opportunity for further scientific discoveries as while also introducing many technical challenges for the systems of ATLAS. The HL-LHC environment has necessitated the Phase-II upgrade of the ATLAS hadronic Tile-Calorimeter (TileCal) which will ensure its peak performance in the coming decades. The upgrade will take place during the third long shutdown of the LHC. It will encompass the replacement of both on- and off-detector electronics, the implementation of new on-detector mechanics as well as the replacement of Photo-multiplier tubes located in the most exposed regions of the detector. The on-detector electronics of the TileCal are powered by 256 adjacent Low-Voltage Power Supplies (LVPS) which themselves contain eight transformer-coupled buck converters known as Bricks. These Bricks function to step-down power received from off-detector bulk power supplies to that required by the front-end electronics. The South African cluster, headed by the University of the Witwatersrand, is responsible for the research and development, production, quality assurance testing and integration of half of the required Bricks for the Phase-II Upgrade. This presentation will provide an overview of the South African cluster's contributions to the development and production of the LVPS Bricks for the ATLAS Tile-Calorimeter Phase-II Upgrade. It will highlight the current project milestones, including research, development, and quality assurance achievements, and conclude with a forward-looking perspective on the remaining activities critical for ensuring the success of the project
Measurement of coherent exclusive production in ultraperipheral Pb+Pb collisions at TeV with the ATLAS detector
No full textThis note presents a measurement of coherent exclusive production in ultraperipheral Pb+Pb collisions at TeV. The dataset was recorded in 2023 and corresponds to 76.5 b. Exclusive candidates were selected with a dedicated track-sensitive trigger based on the ATLAS transition radiation detector. Although the trigger is sensitive to both leptonic decay modes ( and ), the measurement is performed only for the dimuon decay channel. The analysis involves reconstruction of the dimuon invariant mass based on muon tracks only from the inner detector, as the available muon transverse momentum range precludes the use of the standard muon reconstruction and identification algorithms. Differential cross-sections are measured as a function of rapidity and are compared with theoretical predictions. After interpolation to the lower beam energy, they are also compared with the previous LHC Run 2 measurements at TeV
First observation and branching fraction measurement of the decay at LHCb
No full textIn this thesis, the first significant observation of the decay and the measurement of the branching fraction are presented. The analysis has been performed within the LHCb experiment using proton-proton collision data recorded at centre-of-mass energies TeV, corresponding to an integrated luminosity of 5.4 fb. A number of signal candidates is observed with respect to the background expectation, marking the first clear observation of the decay. Furthermore, the result is normalised using the decay and the branching fraction is measured to be , where the first uncertainty is statistical and the second one is systematic. Additionally, the dimuon invariant mass is inspected for a possible New Physics hint. No significant signal has been found and an upper limit on the branching fraction of the resonant channel is set with the CL method at at 90% confidence level. In addition to this analysis, I was also involved in the test beam campaigns dedicated to the future upgrades of the LHCb RICH detector, in view of the high-luminosity phase of the Large Hadron Collider. In Appendix C, studies on the single-photon time resolution, using the data collected with the SPS charged particle beam facility at CERN, are presented
European Strategy for Particle Physics 2026: the NA60+/DiCE experiment at the SPS
No full textThe exploration of the phase diagram of Quantum ChromoDynamics (QCD) is carried out by studying ultrarelativistic heavy-ion collisions. The energy range covered by the CERN SPS ( GeV) is ideal for the investigation of the region corresponding to finite baryochemical potential (), and was little explored up to now. We propose in this document a new experiment, NA60+/DiCE (Dilepton and Charm Experiment), that will address several observables which are fundamental for the understanding of the phase transition from hadronic matter towards a Quark-Gluon Plasma (QGP) at finite . In particular, we propose to study, in Pb-Pb collisions, as a function of the collision energy, the production of thermal dimuons, from which one can obtain a caloric curve of the QCD phase diagram that may be sensitive to the order of the phase transition. In addition, the measurement of a mixing contribution will provide conclusive insights into the restoration of the chiral symmetry of QCD. Studies of open charm and charmonium production will also be carried out, addressing the measurement of transport properties of the QGP and the investigation of the onset of the deconfinement transition. Reference measurements with proton-nucleus collisions are an essential part of this program. The experimental set-up couples a vertex telescope based on monolithic active pixel sensors (MAPS) to a muon spectrometer with MWPC detectors. Two existing CERN dipole magnets, MEP48 and MNP33, will be used for the vertex and muon spectrometers, respectively. The continuing availability of Pb ion beams in the CERN SPS is a crucial requirement for the experimental program. After the submission of a LoI, the experiment proposal is currently in preparation and is due by mid 2025. The start of the data taking is foreseen by 2029/2030, and should last about 7 years
