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Status of the FCC-ee interaction region design
No full textThis paper presents a comprehensive overview of the Machine Detector Interface (MDI) design developed for the FCC-ee Feasibility Study. It highlights novel studies related to the lightweight interaction region, including a mechanical model of the vacuum chambers, integration of the vertex detector, the MDI alignment system, and assessments of machine-induced backgrounds. The small beam pipe radius and thickness, as well as the high power to be dissipated, require state-of-the-art mechanical design. The integration of all mechanical elements and detectors is challenging, necessitating careful studies to allow fulfilling conflicting requirements. The optimisation of the machine detector interface against formidable backgrounds is presented
A Comprehensive Bandwidth Testing Framework for the LHCb Upgrade Trigger System
No full textThe LHCb experiment at CERN has undergone a comprehensive upgrade, including a complete re-design of the trigger system into a hybrid-architecture, software-only system that records ten times more events per unit time for physics analysis than its predecessor. This increased efficiency - as well as the growing diversity of signals physicists want to analyse - makes it more challenging to conform to crucial operational targets on bandwidth and storage capacity. To address this, a comprehensive, automated testing framework has been developed that emulates the entire LHCb trigger and offline-processing software stack on simulated and real collision data. Scheduled both nightly and on-demand by software testers during development, these tests measure the onlineand offline-processing’s key operational performance metrics (such as rate and bandwidth), for each of the system’s 4000 distinct physics selection algorithms, and their cumulative totals. The results are automatically delivered via concise summaries - to GitLab merge requests and instant messaging channels - that further link to an extensive dashboard of per-algorithm information. The dashboard and pages therein facilitate test-driven trigger development by 100s of physicists, whilst the concise summaries enable efficient, data-driven decision-making by management and software maintainers. This novel bandwidth-testing framework has been helping LHCb build an operationallyviable trigger and data-processing system whilst maintaining the efficiency to satisfy its physics goals
Convolutional Neural Networks for pile-up suppression in the Global Trigger
No full textThis note describes a pile-up suppression algorithm using a convolutional neural network (CNN) architecture for the ATLAS Global Trigger upgrade planned for the High-Luminosity LHC programme. The CNN operates on cell towers and exploits both shower topology and \Et\ to correct for the contribution of pile-up. The algorithm is optimised for firmware deployment and demonstrates high throughput and low resource usage. The small size of the input and lightweight implementation enable a high degree of scalability and parallelisation. The physics performance of the algorithm is benchmarked against a range of existing algorithms by reconstructing and calibrating small- central jets. The results show that the CNN allows for the lowest thresholds for multi-jet, jet and signatures and, correspondingly, gives the highest acceptance for key signal processes like and in the simulation
Challenges in experimental measurements of quantum properties at the LHC
No full textThis talk highlights the challenges faced when attempting to measure quantum properties. In particular, difficulties in the identification of jet flavours and the reconstruction of ttbar systems will be considered, especially in the boosted topology where the decay products become highly collimated
Recent Non-Hadronic Results (ATLAS)
No full textRecent measurements and searches for New Physics using the full Run2 dataset of proton-proton collisions at collected by the ATLAS detector at the LHC are presented. A comprehensive study of high-mass τ τ ̄ production includes a cross-section measurement, constraints on effective field theory parameters and searches for new resonances. Additionally, a search for quantum black hole production in lepton+jet final states probes models of extra dimensions and quantum gravity effects at high mass
Constraint-Based Optimization of Particle Routing and Accelerator Utilization
No full textThis paper presents a constraint optimization model, implemented with CP-SAT, for static, cyclic particle beam scheduling in CERN’s accelerator complex. The formulation enforces hard constraints on beam shapes, sets of discrete basic periods (1.2 second intervals) across multiple accelerators, together with strict limits on beam repetitions per super-cycle, and particle accelerator non-overlap to prevent resource conflicts. The model integrates three prioritized objectives: (1) maximize machine utilization by densely filling the Beam Coordination Diagram (BCD), (2) promote uniform beam spacing to ensure stable particle currents for experiments, and (3) optimize Antiproton Decelerator (AD) average response time using a graph-based loss minimization. Additional features include handling of fixed-position beams and inter-beam temporal constraints. Solver steering strategies, including decision-variable ordering and hinting from previous solutions, enable solving of nominal BCDs with lengths over 50 basic periods in under 5 seconds. This constraint-based optimization approach replaces error-prone, labor-intensive manual scheduling, while improving particle accelerator utilization and delivering more consistent beam availability for experiments
Dr Nicodemos Damianou, Deputy Minister of Research, Innovation and Digital Policy, Republic of Cyprus, on the occasion of the remote signature of the agreement between the European Organization for Nuclear Research (CERN) and the Republic of Cyprus concerning the granting of the status of Associate Member State of CERN, on Friday, 22 August 2025.
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