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Performance and long-term aging studies on Eco-Friendly Resistive Plate Chamber detectors
No full textIn High Energy Physics Resistive Plate Chamber (RPC) detectors are typically operated in avalanche mode, making use of a high-performance gas mixture whose main component, Tetrafluoroethane (C2H2F4), is classified as a fluorinated high Global Warming Potential greenhouse gas. The RPC EcoGas@GIF++ Collaboration is pursuing an intensive R&D; on new gas mixtures for RPC detectors to explore environmentally friendly alternatives complying with recent European regulations. During the last few years, the performance of RPCs characterized by different layouts and read-out electronics have been studied with Tetrafluoropropene (C3H2F4)–CO2 based gas mixtures at the CERN Gamma Irradiation Facility. A long-term ageing test campaign was launched in 2022 and is still on-going. In 2023 and 2024 all detector systems underwent evaluation by means of dedicated beam tests. Preliminary results on these studies are presented in this paper together with their future perspectives
Radiochromic Film Dosimetry for VHEE and UHDR: Considerations for the CLEAR Facility and Comparisons with Alanine, RPL and Dosimetry Phantoms
No full textRadiochromic films (RCFs) offer valuable two-dimensional dosimetry capabilities with a conceptually simple operating principle that requires minimal investment, making them particularly suitable for very high energy electron (VHEE) FLASH dosimetry where dosimetry standards are currently lacking. However, achieving high-accuracy measurements with RCFs presents significant practical challenges. Without the standardised protocols that ensure reliable outcomes across applications and facilities, knowledge of RCF behaviour becomes essential. This paper identifies common sources of error in RCF preparation, scanning, and processing while proposing specific mitigation strategies to improve accuracy and efficiency. Using our optimised RCF protocol at the CLEAR facility, we demonstrate relative agreement within 5% compared to alanine dosimeters when measuring Gaussian VHEE beams, establishing a foundation for reliable dosimetry in these advanced radiotherapy applications
The Calibr-A-Ton: a novel method for calorimeter energy calibration
No full textThe energy calibration of calorimeters at collider experiments, such as the ones at the CERN Large Hadron Collider, is crucial for achieving the experiments physics objectives. Standard calibration approaches have limitations that become more pronounced as detector granularity increases. In this paper we propose a novel calibration procedure to simultaneously calibrate individual detector cells belonging to a particle shower by targeting a well-controlled energy reference. The method bypasses some of the difficulties that exist in more standard approaches, and it is implemented using differentiable programming. Simulated energy deposits in the electromagnetic section of a high-granularity calorimeter are used to study the method and demonstrate its performance. It is shown that the method is able to correct for biases in the energy response
(Quadratically) Refined Discrete Anomaly Cancellation
No full textIn this work we study the cancellation of non-perturbative anomalies of gravitational theories with gauge group ℤ in six dimensions. These subtle anomalies require a classification of deformation classes of manifolds with discrete gauge bundles known as bordism groups. The consistency of the theory demands a cancellation of the fermion anomalies, which can be done by the transformation properties of 2-form fields in the theory. Since the 2-forms in six dimensions are themselves chiral, their formulation needs subtle topological information encoded in a so-called quadratic refinement. A matching between the fermionic anomalies and the defining properties of the quadratic refinement, lead to strong consistency constraints on the charged fermion spectrum. We explicitly determine these consistency conditions for the case of a single chiral 2-form and various discrete gauge groups. Since we provide a model-independent formulation, these restrictions hold universally for theories of this type.In this work we study the cancellation of non-perturbative anomalies of gravitational theories with gauge group in six dimensions. These subtle anomalies require a classification of deformation classes of manifolds with discrete gauge bundles known as bordism groups. The consistency of the theory demands a cancellation of the fermion anomalies, which can be done by the transformation properties of 2-form fields in the theory. Since the 2-forms in six dimensions are themselves chiral, their formulation needs subtle topological information encoded in a so-called quadratic refinement. A matching between the fermionic anomalies and the defining properties of the quadratic refinement, lead to strong consistency constraints on the charged fermion spectrum. We explicitly determine these consistency conditions for the case of a single chiral 2-form and various discrete gauge groups. Since we provide a model-independent formulation, these restrictions hold universally for theories of this type
Gravitational Wave Scattering on Magnetic Fields
No full textThe conversion of gravitational to electromagnetic waves in the presence of background magnetic fields is known as the inverse Gertsenshtein effect, analogous to the Primakoff effect for axions.Rephrasing this conversion as a classical electrodynamics problem in the far-field regime of a magnetized region, we derive the angular distribution of the intensity and polarization of the emitted electromagnetic waves.We discuss the interplay of the internal structure of the magnetic field, the polarization of the gravitational wave and the scattering angle, demonstrating for example that a dipolar field can convert an unpolarized stochastic gravitational wave background into polarized electromagnetic emission, with peak emission intensity along the equator.We moreover outline how to incorporate medium effects in this framework, necessary for a realistic 3D description of gravitational wave to photon conversion in the magnetosphere of neutron stars.The conversion of gravitational to electromagnetic waves in the presence of background magnetic fields is known as the inverse Gertsenshtein effect, analogous to the Primakoff effect for axions. Rephrasing this conversion as a classical electrodynamics problem in the far-field regime of a magnetized region, we derive the angular distribution of the intensity and polarization of the emitted electromagnetic waves. We discuss the interplay of the internal structure of the magnetic field, the polarization of the gravitational wave and the scattering angle, demonstrating for example that a dipolar field can convert an unpolarized stochastic gravitational wave background into polarized electromagnetic emission, with peak emission intensity along the equator. We moreover outline how to incorporate medium effects in this framework, necessary for a realistic 3D description of gravitational wave to photon conversion in the magnetosphere of neutron stars
Capturing methane in a barn environment: the CH4 Livestock Emission (CH4rLiE) project
No full textThe CH4 Livestock Emission (CH4rLiE) project explores the development of a prototype system for capturing methane emissions in barn environments, offering an alternative approach to mitigating greenhouse gas emissions from livestock farming. Methane (CH4), with a global warming potential significantly higher than CO2 (GWP100 = 27), accounts for ~23% of anthropogenic climate impact. In 2021, The Assessment Report 6 of Intergovernmental Panel on Climate Change quantified CH4 livestock emissions in 123 Mt/yr, which, together with substantial N2O and CO2 emissions, contributed with a 12% to global emissions. Unlike strategies focused on altering animal feed, CH4rLiE investigates post-emission capture using porous materials, such as zeolites, to adsorb methane from barn air. The project draws on CERN's experience with gas recovery systems for particle detectors, adapting similar technologies to agricultural settings. Preliminary estimates, based on measured CH4 concentrations (~20 mg/m3) and partial air filtration in a 250-animal barn, suggest a low but detectable recovery potential, subject to validation through simulation and in-situ testing. Prototype development considers the potential for energy-efficient operation - possibly through pressure swing regeneration - and compatibility with existing ventilation infrastructure, though these aspects remain under evaluation. If methane concentrations in barns prove too diluted, the system may be better suited for environments with higher gas levels, such as pigsties or landfills. NH3 capture for fertilizer production is planned as a future enhancement. CH4rLiE aims to assess the feasibility of emission recovery in livestock settings without affecting animal welfare, contributing to sustainable farming practices, resource efficiency, and circular bioeconomy goals
ATLAS Muon Detectors upgrades for High Luminosity LHC
No full textThe muon spectrometer of the ATLAS detector will undergo a substantial upgrade during the Phase-II upgrade in Long Shutdown 3 to meet the operational demands of the High-Luminosity LHC. Most of the electronics for the Monitored Drift Tube (MDT) chambers, Resistive Plate Chambers (RPC), and Thin Gap Chambers (TGC) will be replaced to ensure compatibility with the higher trigger rates and extended latencies required for the new level-0 trigger. The MDT chambers will be integrated into the level-0 trigger to sharpen the momentum threshold. Additional RPC chambers will be installed in the inner barrel layer to enhance the acceptance and robustness of the trigger. Some MDT chambers in the inner barrel layer will be replaced with new small-diameter MDTs to optimize performance. New TGC triplet chambers will be installed in the barrel-endcap transition region, replacing the current TGC doublets to reduce the high trigger rate caused by random coincidences in this area. Additionally, the power systems for the RPC, TGC, and MDT chambers, along with their associated electronics, will be replaced due to component obsolescence, ageing, and radiation damage. This contribution will provide an overview of the upgrade challenges, the current status of the projects, prototype and production results
Commissioning and evolution of the Run 3 ATLAS Trigger
No full textThe ATLAS experiment in the LHC Run 3 uses a two-level trigger system to select events of interest to reduce the 40 MHz bunch crossing rate to a recorded rate of up to 3 kHz of fully-built physics events. The trigger system is composed of a hardware based Level-1 trigger and a software based High Level Trigger. Both hardware and software elements have had significant upgrades and improvements for LHC Run 3. We will present an overview of these improvements and how the trigger system has evolved to incorporate them