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Machine Learning for Real-Time Processing of ATLAS Liquid Argon Calorimeter Signals with FPGAs
No full textThe Phase-II Upgrade of the LHC will increase its instantaneous luminosity by a factor of 7 leading to the HL-LHC era. At the HL-LHC, the number of proton-proton collisions in one bunch crossing, pileup, increases significantly, putting stringent requirements on the LHC detectors electronics and real-time data processing capabilities. The ATLAS LAr calorimeter measures the energy of particles produced in LHC collisions. It also feeds the ATLAS trigger to identify interesting events. To enhance the ATLAS physics discovery potential at HL-LHC, an excellent energy resolution and an accurate time detection is crucial. The computation of the deposited energy is performed using electronic boards based on FPGAs. Currently this computation is done using optimal filtering algorithms that are adapted to situations with limited pileup. With the increased luminosity and pileup, the performance of the optimal filter algorithms decreases. The off-detector electronic boards for the LAr Phase-II Upgrade will use the next generation of INTEL FPGAs with increased processing power and memory. This will allow the use on these boards of more complex algorithms. We developed several neural networks (NNs) with significant performance improvements with respect to the optimal filtering algorithms. Five NN algorithms will be presented. The improvement of the energy resolution and the accuracy of the deposited time compared to the legacy filter algorithms will be discussed. The implementation of these networks in firmware will be shown
Search for a resonance decaying into a scalar particle and a Higgs boson in the final state with two bottom quarks and two photons with 199 fb of data collected at √s=13 TeV and √s=13.6 TeV with the ATLAS detector.
No full textA search for the resonant production of a heavy scalar decaying into a Higgs boson and a lighter scalar , through the process , where the two photons are consistent with the Higgs boson decay, is performed. The search is conducted using integrated luminosities of 140 fb and 58.6 fb of proton-proton collision data at centre-of-mass energies of 13 TeV and 13.6 TeV respectively, recorded with the ATLAS detector at the Large Hadron Collider. The search is performed over the mass ranges of 170 1000 GeV and 15 500 GeV. No significant excess over the Standard Model background prediction is observed and limits at 95% confidence level are set on the cross-section at 13 TeV, ranging from 9 fb to 0.06 fb
Magnet R&D; for the Muon Collider -- European Strategy Input
No full textThe Muon Collider, proposed under the International Muon Collider Collaboration (IMCC), represents a groundbreaking advancement in circular collider technology. By using muons instead of protons or electrons, this collider has the potential of unprecedented discovery reach, luminosity, and compact design, significantly increasing energy efficiency, reducing environmental impact and improving sustainability. However, achieving this vision necessitates overcoming unique and extreme challenges in superconducting magnet technology. This document summarizes the state of the art, challenges, and the proposed R&D; roadmap for developing the next generation of superconducting magnet systems crucial for the Muon Collider over the next ten years. The goal is to advance accelerator magnet technology beyond current limits, with a special focus on High-Temperature Superconductors (HTS) materials for high-field and high-temperature applications. This note is a concise summary of the extensive proposal [BOT-2025] which we refer to for detailed referencing and as supporting material. We focus here on the technology gap to be filled by the proposed R&D;, the structure and objectives of the proposed R&D;, and provide the resource estimate for the next ten years
Measurement and related interpretations of cross-sections in pp collisions at = 13 TeV with the ATLAS detector
No full textMeasurements of integrated and differential cross-sections for production in proton–proton collisions are presented. The data collected by the ATLAS detector at the Large Hadron Collider from 2015 to 2018 at a centre-of-mass energy of = 13 TeV are used, corresponding to an integrated luminosity of 140 fb. The candidate events are reconstructed using leptonic decay modes of the gauge bosons into electrons or muons. The integrated cross-section per lepton flavour for the production of is measured in the detector fiducial region. The measured value is compared to the Standard Model prediction at a precision of up to next-to-next-to-leading-order in QCD and next-leading-order in electroweak. Cross-sections for and production as well as their ratio are presented. The production is also measured differentially as functions of various kinematic variables, including new observables sensitive to CP-violation effects. All measurements are compared to state-of-the-art Standard Model predictions from fixed-order calculations or Monte Carlo generators based on next-to-leading-order matrix elements interfaced with parton showers. An effective field theory interpretation of the measurements is performed, considering both CP-conserving and CP-violating dimension-6 operators modifying the production. Limits on CP-conserving Wilson coefficients are extracted using the transverse mass of the system. For CP-violating coefficients a machine learning pproach is used to construct an observable with enhanced sensitivity to CP-violation effects
Estimation of backgrounds from jets misidentified as tau leptons using the Universal Fake Factor method with the ATLAS detector
No full textPhysical processes with one or more τ-lepton in the final state play an important role in several analyses of the ATLAS experiment physics program. The usage of hadronic channels, in which τ-leptons decay into one or more pions, enables to exploit the large statistics associated with hadronic τ-lepton decays, but also requires a precise estimate of a sizable background of hadronic jets mis-reconstructed as fake τ-leptons. This poster will present a new technique developed by the ATLAS Collaboration to estimate the fake τ-lepton background from data - the Universal Fake Factor method. This technique improves on previous methodologies as it enables a more solid validation of the estimated background. Details on how to implement this methodology will be given as well as on its validation with single and di-τ final states. Information on ATLAS physics analyses that successfully exploited this technique will also be given
Optimizing superconducting Nb film cavities by mitigating medium-field -slope through annealing
No full textNiobium films are of interest in applications in various superconducting devices, such as superconducting radiofrequency cavities for particle accelerators and superconducting qubits for quantum computing. In this study, we address the persistent medium-field -slope issue in Nb film cavities, which, despite their high-quality factor at low RF fields, exhibit a significant -slope at medium RF fields compared to bulk Nb cavities. Traditional heat treatments, effective in reducing surface resistance and mitigating the -slope in bulk Nb cavities, are challenging for Nb-coated copper cavities. To overcome this challenge, we employed DC bias high-power impulse magnetron sputtering to deposit Nb film onto a 1.3 GHz single-cell elliptical bulk Nb cavity, followed by annealing treatments aimed at modifying the properties of the Nb film. In-situ annealing at 340 °C increased the quench field from 10.0 to 12.5 MV m. Vacuum furnace annealing at 600 °C and 800 °C for 3 h resulted in a quench field increase of 13.5 and 15.3 MV m, respectively. Further annealing at 800 °C for 6 h boosted the quench field to 17.5 MV m. Additionally, the annealing treatments significantly reduced the field dependence of the surface resistance. However, increasing the annealing temperature to 900 °C induced a -switch phenomenon in the cavity. The analysis of RF performance and material characterization before and after annealing has provided critical insights into how the microstructure and impurity levels in Nb films influence the evolution of the -slope in Nb film cavities. Our findings highlight the significant roles of hydrides, high local misorientation, and lattice and surface defects in driving field-dependent losses. By strategically optimizing film properties and controlling impurity levels, we demonstrate a promising pathway to mitigate the medium-field -slope, paving the way for more efficient superconducting RF technologies.Niobium films are of interest in applications in various superconducting devices, such as superconducting radiofrequency cavities for particle accelerators and superconducting qubits for quantum computing. In this study, we addressed the persistent medium-field Q-slope issue in Nb film cavities, which, despite their high-quality factor at low RF fields, exhibit a significant Q-slope at medium RF fields compared to bulk Nb cavities. Traditional heat treatments, effective in reducing surface resistance and mitigating the Q-slope in bulk Nb cavities, are challenging for niobium-coated copper cavities. To overcome this challenge, we employed DC biased high-power impulse magnetron sputtering to deposit niobium film onto a 1.3 GHz single-cell elliptical bulk niobium cavity, followed by annealing treatments aimed at modifying the properties of the niobium film. In-situ annealing at 340 °C increased the quench field from 10.0 to 12.5 MV/m. Vacuum furnace annealing at 600 °C and 800 °C for 3 hours resulted in a quench field increase of 13.5 and 15.3 MV/m, respectively. Further annealing at 800 °C for 6 hours boosted the quench field to 17.5 MV/m. Additionally, the annealing treatments significantly reduced the field dependence of the surface resistance. However, increasing the annealing temperature to 900 °C induced a Q-switch phenomenon in the cavity. The analysis of RF performance and material characterization before and after annealing has provided critical insights into how the microstructure and impurity levels in Nb films influence the evolution of the Q-slope in Nb film cavities. Our findings highlight the significant roles of hydrides, high local misorientation, and lattice and surface defects in driving field-dependent losses
An updated HL-LHC halo population model based on recent experimental measurements
No full textThe transverse beam halo population in the Large Hadron Collider (LHC) has been found to carry a significant fraction of the total stored beam energy, potentially reaching several percent. With the anticipated increase in beam brightness for the High Luminosity LHC (HL-LHC), this poses an increasing risk to machine safety, particularly during abrupt orbit shifts or critical component failures. A comprehensive understanding and an accurate modelling of the transverse beam halo are crucial for simulations of beam losses around the ring as a consequence of such failure scenarios in the HL-LHC era. Various models, including Gaussian, double-Gaussian, and q-Gaussian distributions, have been used to describe the LHC beam halos for fitting the measured distributions. This paper provides an in-depth analysis of halo modelling based on collimator scraping measurements from the LHC operational Run 2 and Run 3, and evaluates the accuracy and representativeness of these different distribution models
Status and testing of the MDT Trigger Processor for the ATLAS Level-0 Muon Trigger at HL-LHC
No full textThe Monitored Drift Tube Trigger Processor (MDT-TP) will improve the rate capabilities of the first-level muon (L0 Muon) trigger of the ATLAS Experiment during the operation of the HL-LHC. The information of the trigger candidate, obtained by other muon trigger subsystems, will be combined with the precision of the MDT chambers in order to improve the resolution on the muon momentum measurement, while limiting the trigger rate to an acceptable level in the high-pileup environment of HL-LHC. The MDT-TP trigger logic is implemented on a AMD VU13P FPGA, where MDT hits are extracted around the region-of-interest identified by the trigger candidate and are used to perform muon reconstruction and transverse momentum estimation. For accepted events, MDT hits are transmitted by the MDT-TP to the ATLAS data acquisition system via FELIX. Monitoring, configuration and interfaces with other ATLAS subsystems are implemented via services running on a Zynq SoC. Several tests of the MDT-TP are being conducted, including the configuration and monitoring of the MDT-TP and the on-detector electronics, communication with other L0 Muon trigger boards and readout via FELIX. The current status of the prototype testing and the recent updates on firmware and software developments will be presented