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Visit by Mr Rudy Montero Mata, Deputy Minister of Science, Technology and Environment, Cuba
No full textVisit by His Excellency Mr Rudy Montero Mata, Deputy Minister of Science, Technology and Environment, Republic of Cub
Searches for New Physics at the LHC
No full textPlenary talk to be presented at the EPS 2025 conference on behalf of the ATLAS and CMS Collaborations (in this version showing ATLAS-only results - most of them still internal)
Performance analysis of dynamically integrated HPC resources in the ATLAS workflow at the WLCG Tier-2 site in Freiburg
No full textAt many Worldwide LHC Computing Grid (WLCG) sites, HPC resources are already integrated, or will be integrated in the near future, into the experiment specific workflows. The integration can be done either in an opportunistic way to use otherwise unused resources for a limited period of time, or in a permanent way. The WLCG ATLAS Tier-2 cluster in Freiburg has been extended in both ways: opportunistic use of resources from the NEMO HPC cluster in Freiburg and permanent use of the HoreKa HPC cluster at KIT. In order to integrate the computing resources into the Tier-2 cluster in Freiburg in a manner that is both transparent and efficient, a container-based approach was adopted, utilising the meta-scheduler COBalD/TARDIS. TARDIS launches so-called drones on the HPC cluster, which provide the Tier-2 cluster with additional resources. To differentiate these augmented resources from their counterparts installed in Freiburg, the accounting is handled by the AUDITOR accounting ecosystem. The compute hardware of the local Tier-2 cluster and the HPC cluster NEMO are largely identical and were replaced simultaneously. This facilitated a comprehensive analysis of the impact of various factors. Firstly, the difference in identical hardware from the bare-metal installation of a typical WLCG compute server was compared with drones on the HPC clusters. Furthermore, the influence of direct access from the Freiburg Tier-2 cluster and the Freiburg HPC cluster to the Freiburg-based storage, as well as remote access from Karlsruhe HoreKa, was analysed. Finally, the impact of varying drone sizes was investigated. These results will have a significant impact on the German HEP community's computing strategy for the next 5-10 years
SN 2023ixf: An average-energy explosion with circumstellar medium and a precursor
No full textThe fortunate proximity of the Type II supernova (SN) 2023ixf has allowed astronomers to follow its evolution from almost the moment of the collapse of the progenitor’s core. SN 2023ixf can be explained as an explosion of a massive star with an energy of 0.7 × 1051 erg but with a greatly reduced envelope mass, probably because of binary interaction. In our radiative-transfer simulations, the SN ejecta of 6 M⊙ interact with circumstellar matter (CSM) of (0.55–0.83) M⊙ extending to 1015 cm, which results in a light curve (LC) peak matching that of SN 2023ixf. The origin of this required CSM might be gravity waves originating from convective shell burning, which could enhance wind-like mass loss during the late stages of stellar evolution. The steeply rising low-luminosity flux during the first hours after observationally confirmed non-detection, however, cannot be explained by the collision of the energetic SN shock with the CSM. Instead, we consider it as a precursor that we can fit by the emission from (0.5–0.9) M⊙ of matter that was ejected with an energy of ∼1049 erg a fraction of a day before the main shock of the SN explosion reached the surface of the progenitor. The source of this energy injection into the outermost shell of the stellar envelope could also be dynamical processes related to the convective activity in the progenitor’s interior or envelope. Alternatively, the early rise of the LC could point to the initial breakout of a highly non-spherical SN shock or of fast-moving asymmetrically ejected matter that was swept out well ahead of the SN shock, potentially in a low-energy, nearly relativistic jet. We also discuss that pre-SN outbursts and LC precursors can be used to study or to constrain energy deposition in the outermost stellar layers by the decay of exotic particles, such as axions, which could be produced simultaneously with neutrinos in the newly formed hot neutron star. A careful analysis of the earliest few hours of the LCs of SNe can reveal elusive precursors and provide a unique window onto the surface activity of massive stars during their core collapse. This can greatly improve our understanding of stellar physics and consequently also offer new tools for searching for exotic particles.Key words: astroparticle physics / radiative transfer / shock waves / stars: massive / stars: mass-loss / supernovae: individual: SN 2023ixfAbridged: The fortunate proximity of the SN2023ixf allowed astronomers to follow its evolution from almost the moment of the collapse of the progenitor's core. SN2023ixf can be explained as an explosion of a massive star with an energy of 0.7e51 erg, however with a greatly reduced envelope mass, probably because of binary interaction. In our radiative-transfer simulations, the SN ejecta of 6 Msun interact with circumstellar material (CSM) of ~0.6 Msun extending to 1.e15 cm, which results in a light curve (LC) peak matching that of SN2023ixf. The origin of this required CSM might be gravity waves originating from convective shell burning, which could enhance wind-like mass-loss during the late stages of stellar evolution. The steeply rising, low-luminosity flux during the first hours after observationally confirmed non-detection, however, cannot be explained by the collision of the energetic SN shock with the CSM. Instead, we considered it as a precursor that we could fit by the emission from ~0.5 Msun of matter that was ejected with an energy of 1.e49 erg a fraction of a day before the main shock of the SN explosion reached the surface of the progenitor. The source of this energy injection into the outermost shell of the stellar envelope could also be dynamical processes related to the convective activity in the progenitor's interior or envelope. Alternatively, the early rise of the LC could point to the initial breakout of a highly non-spherical SN shock or of fast-moving, asymmetrically ejected matter that was swept out well ahead of the SN shock, potentially in a low-energy, nearly relativistic jet. We also discuss that pre-SN outbursts and LC precursors can be used to study or to constrain energy deposition in the outermost stellar layers by the decay of exotic particles, such as axions, which could be produced simultaneously with neutrinos in the newly formed, hot neutron star
Clarity through the Neutrino Fog: Constraining New Forces in Dark Matter Detectors
No full textThe PandaX-4T and XENONnT experiments present indications of Coherent Elastic Neutrino Nucleus Scattering (CEνNS) from B solar neutrinos at 2.6σ and 2.7σ, respectively. This constitutes the first observation of the neutrino “floor” or “fog”, an irreducible background that future dark matter searches in terrestrial detectors will have to contend with. Here, we first discuss the contributions from neutrino–electron scattering and from the Migdal effect in the region of interest of these experiments, and we argue that they are non-negligible. Second, we make use of the recent PandaX-4T and XENONnT data to derive novel constraints on light scalar and vector mediators coupling to neutrinos and quarks. We demonstrate that these experiments already provide world-leading laboratory constraints on new light mediators in some regions of parameter space.The PANDAX-4T and XENONnT experiments present indications of Coherent Elastic Neutrino Nucleus Scattering (CENS) from B solar neutrinos at 2.6 and 2.7, respectively. This constitutes the first observation of the neutrino "floor" or "fog", an irreducible background that future dark matter searches in terrestrial detectors will have to contend with. Here, we first discuss the contributions from neutrino-electron scattering and from the Migdal effect in the region of interest of these experiments, and we argue that they are non-negligible. Second, we make use of the recent PANDAX-4T and XENONnT data to derive novel constraints on light scalar and vector mediators coupling to neutrinos and quarks. We demonstrate that these experiments already provide world-leading laboratory constraints on new light mediators in some regions of parameter space
The Value of Open Science at CERN: An Analysis Based on a Travel Cost Model
No full textOpen science is a fundamental root of the European Organization for Nuclear Research, known by its acronym CERN. This international organization, located between Switzerland and France, has distinguished itself since its inception by sharing its discoveries, innovative technologies, and the information generated by its most ambitious project, the Large Hadron Collider (LHC) so that researchers around the world and society can benefit from the data gathered and the knowledge created. One of the main characteristics of the organization is the possibility to freely visit the particle accelerators and the experiments at these machines. On these occasions, visitors can meet the scientists and learn directly from them about the organization, its discoveries, and its daily activities. This study is one of the few assessing the economic value of these initiatives. It is based on a survey using a sample size of 900 visitors to CERN during one calendar year. Results from a travel cost application show that visitor would be willing to pay a total on average at least 0.72 € over the cost of the trip per person, owing to the experience and knowledge gained during their visit to the infrastructure
A new approach for nuclear spin determination via in-source resonance ionisation spectroscopy and yield measurements of neutron deficient radium isotopes
No full textUpdates of the ATLAS High-Level Trigger in Run 3
No full textThe main reconstruction and simulation software framework of the ATLAS experiment, Athena, underwent a major change during the LHC Run 3 in the way the configuration step of its applications is performed. The new configuration system, called ComponentAcumulator, emphasises modularity and provides a way for standalone execution of parts of a job, as long as the inputs are available, which allows unit-testing of individual components or groups of components, as well as easier debugging. The switch to the new configuration system of the High-Level Trigger (HLT) software, which utilises Athena algorithms for object reconstruction and hypothesis testing, required designing a special approach to prevent disruption of data taking during the code migration to ComponentAccumulator. An additional challenge is brought by a large amount of HLT chains, where in many cases copies of the same algorithm with varying configurations are used, which significantly increases the number of configured parameters compared to offline reconstruction jobs. This report describes migration of the HLT software to ComponentAccumulator along with further improvements in the data acquisition introduced for Run 3 data taking
The First Release of ATLAS Open Data for Research
No full textThe ATLAS Collaboration has released an extensive volume of data for research use for the first time. The full datasets of proton collisions from 2015 and 2016, alongside a wide array of matching simulated data, are all offered in the PHYSLITE format. This lightweight format is chosen for its efficiency and is the preferred standard for ATLAS internal analyses. Additionally, the inclusion of Heavy Ion collision data considerably widens the scope for research within the particle physics community. To ensure accessibility and usability, the release includes a comprehensive suite of software tools and detailed documentation, catering to a varied audience. Code examples, from basic Jupyter notebooks to more complex C++ analysis packages, aim to facilitate engagement with the data. This contribution details the available data, corresponding metadata, software, and documentation, and initial interactions with researchers outside the ATLAS collaboration, underscoring the project's potential to foster new research and collaborations
Mass production of RPC readout panels for ATLAS Phase-II upgrade and RD on thin gas gap production at USTC
No full textIn order to accommodate the High-Luminosity Large Hadron Collider, the current ATLAS Muon system needs a significant upgrade during the Long Shutdown-3. For the muon trigger, three layers of thin-gap Resistive Plate Chambers (RPCs) will be added to the Barrel Inner (BI) region. This new generation of RPCs features a thin-gap design that significantly enhances their rate capabilities. However, it poses significant challenges for detector production, Quality Assurance, and Quality Control.Our Chinese ATLAS group undertook the construction of 912 readout panels, the fabrication of 72 BI gas gaps, and the assembly of 360 singlets for the upgrade.To successfully implement the BI-RPC project in China, we have developed and refined a vacuum-bag-based method for producing honeycomb readout panels in our laboratory.This method is also utilized in the production of readout panels in the Chinese industry. The speed and quality of readout panel production have significantly improved.The procedures for gas gap production and the assembly of RPC singlets are outlined in detail. The gas gaps are treated with oil at a temperature of around degrees Celsius and flushed with heptane before the application of linseed oil. This process can greatly enhance the quality of linseed oiling on the inner surfaces of the Bakelite RPC. The quality of the gas gaps is assessed and the results are very promising