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Success, Open Source and You: Maximising the impact of your open-source contributions
No full textNavigating open source projects can be a challenge for both new and experienced contributors. This talk will cover contribution best practices that will help new contributors get started while also helping experienced contributors improve their interactions with open source projects. We'll discuss how to use metrics from the CHAOSS project to consider the health of the external projects you contribute to and identify areas that might indicate that a project is at risk of becoming unviable in the future. But the advantage of working in open source is that we can identify potential risks and work within projects to make them more viable, and this talk will discuss how to improve projects from within. By the end of this talk, you'll have learned tips and tricks for becoming an even better open source contributor
The Role of Azimuthal Prestress in the Longitudinal Degradation of Nb3Sn Superconducting Magnets
No full textSuperconducting magnet coils are subject to enormous electro-magnetic forces which push the cables away from the winding pole, and against the surrounding structure. This structure is usually optimized trying to limit the overall motion and the strains experienced by the superconducting elements. To achieve this, preload forces are applied both in the coil cross-section and along its length. If the e.m. forces overcome these preloads, separation between the coil and the pole occurs, resulting in an overall loss of rigidity. During the magnet design process, it is often tempting to treat the optimization of the azimuthal and longitudinal preload systems separately. However, the two are inextricably related: as the cross-section preload increases, friction can prevent any motion in the longitudinal plane, and decreasing it can instead allow dangerous motions in the conductor ends. The latter can result in very high strains and, in Nb3Sn conductors, damage that can prevent the magnet to reach the desired performances. In an attempt to define design guidelines, in this paper we use simplified numerical models to compute, as a function of the in-plane prestress, the variation of the peak strains in the end region of the coils. Finally, we investigate the impact of the azimuthal prestress on a real magnet case, the High-Luminosity Nb3Sn Quadrupole MQXF
Design and experimental verification of a bunch length monitor based on coherent Cherenkov diffraction radiation
No full textThis paper presents the design and experimental commissioning of a noninvasive electron bunch length monitor based on the detection of coherent Cherenkov diffraction radiation (ChDR). The measurement technique effectively eliminates the influence of bunch-by-bunch charge fluctuations, as each detector measures the signal from the same bunch while mitigating the impact of bunch position jitter on the measurements, providing a potential real-time diagnostic tool with significant operational advantages. The sensitivity of the measurements to both bunch length and longitudinal bunch profile was experimentally demonstrated, with results validated against invasive radio frequency deflector measurements at the CLEAR electron test facility at CERN. The ChDR bunch length monitor can be applied to accelerators operating with ultrashort bunches
Early Morning Coffee at CERN podcast episode on quantum entanglement at the LHC
No full textBehind-the-scenes of the new episode of the Early Morning Coffee at CERN (Emc2) video podcast on the topic of quantum entanglement at the LHC. The show is hosted by Steven Goldfarb, directed by Chetna Krishna with Technical Lead Ron Suykerbuyk. The episode features Giulia Negro from the CMS experiment and Yoav Afik from the ATLAS experiment
(Re)interpretation of the LHC results for new physics
No full textIn recent years, LHC experiments are increasingly publishing the full likelihood models for statistical analysis in HEPData. For the purporse of reproducing and reinterpreting such analyses, it is essential to understand the contents of these statistical workspaces. As part of the validation process for an ATLAS combination of searches for Beyond-Standard-Model particles, I have developed an open-access web-based interface to easily and quickly visualise workspace contents and perform fits, called "WorkspaceExplorer", which is freely available at workspaceexplorer.app.cern.ch. In addition to validation, it can be a convenient tool for exploration of unfamiliar statistical models, lowering the barrier for using these for reinterpretations. In this talk, I will present available features and discuss possible use cases for the tool as well as the potential for further developments
(Re)interpretation of the LHC results for new physics
No full textWhile advancements in software development practices across particle physics and adoption of Linux container technology have made substantial impact in the ease of replicability and reuse of analysis software stacks, the underlying software environments are still primarily bespoke builds that lack a full manifest to ensure reproducibility across time. The [HEP Packaging Coordination](https://github.com/hep-packaging-coordination) community project is bootstrapping packaging of the broader community ecosystem on [conda-forge](https://conda-forge.org/). This process covers multi-platform packaging from [low level language phenomenology tools](https://github.com/conda-forge/looptools-feedstock), to the [broader simulation stack](https://github.com/conda-forge/pythia8-feedstock), to [end user analysis tools](https://github.com/conda-forge/pyhf-feedstock), and the reinterpretation ecosystem. When combined with [next generation scientific package management and manifest tools](https://pixi.sh/), the creation of fully specified, portable, and trivially reproducible environments becomes easy and fast, even with the use of hardware accelerators. This ongoing process significantly lowers technical barriers across tool development, distribution, and use, and when combined with public data products provides a transparent system for full analysis reinterpretation and reuse
The Phase-2 upgrade of the Electromagnetic Calorimeter
No full textThe high luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN will provide unprecedented instantaneous luminosity of around . The CMS detector is therefore undergoing an extensive Phase-2 upgrade program to prepare for these demanding conditions. In the barrel region of the CMS Electromagnetic Calorimeter (ECAL), the lead tungstate crystals will continue to perform well. The APDs will also continue to be operational, with some increase in noise, which will be mitigated by reducing the temperature at which ECAL is operated. However, the entire readout and trigger electronics will need to be replaced to cope with the harsh conditions and increased trigger latency requirements at the HL-LHC. The upgraded detector will have a 25 times higher readout granularity at hardware trigger level, and a sampling rate increase by a factor of 4. In terms of physics performance, it will match the outstanding energy resolution of the current ECAL detector, while significantly enhancing the time resolution for electrons and photons above 50 GeV
The evolution of the CMS@Home project
No full textOver time, the idea of exploiting voluntary computing resources as additional capacity for experiments at the LHC has given rise to individual initiatives such as the CMS@Home project. With a starting point of R and D prototypes and projects such as jobs in the Vacuum and SETI@Home, the experiments have tried integrating these resources into their data production frameworks transparently to the computing infrastructure. Many of these efforts were subsequently rolled into the umbrella LHC@Home project.The use of virtual machines instantiated on volunteer resources, with images created and managed by the experiment according to its needs, provided the opportunity to implement this integration, and virtualization enabled CMS code from a Linux environment to also run on Windows and Macintosh systems, realizing a distributed and heterogeneous computing environment.A prototype of CMS@Home integrated with the CMS workload management CRAB3 was proposed in 2015, demonstrating the possibility of using BOINC as manager of volunteer resources and adapting the vacuum concept with the HTCondor Glidein system to get CMS pilots and jobs to execute on volunteers computers. Since then, the integration of volunteer machines with the CMS workload management WMAgent, the official service dedicated to data production, has been seriously considered. The characteristics of volunteer resources regarding bandwidth capacity, connection behavior, and CPU and RAM capacities make them suitable for low-priority workflows with low I/O demands.The poster describes how the configuration of volunteer resources has evolved to keep pace with the development of the CMS computing infrastructure, including using tokens for resource authentication, exploiting regular expressions to accept workflows, manual glideins to initiate pilots, and other implementation details to achieve successful workflows. Currently volunteers are able to execute task chains also of multicore jobs and, despite their limitations, are contributing to CMS computing capacity with around 600 cores daily
R and D Adoption and Progress in Full Simulation of the CMS experiment
No full textIn this work we report on evolution of usage of Geant4 within CMSSW and adaptation of the newest Geant4 11.2.1, which is expected to be used for CMS simulation production in 2025. Physics validation results and results on CPU performance are reported. For the Phase-2 simulation several R\&D are carried out. A significant update for CMS geometry description is performed. Different aspects of geometry description and physics simulation for the new detectors will be discussed. Progress on R\&D efforts for the Phase-2 simulation will be presented, which includes reports on experience of application of G4HepEm external library
Commissioning and exploitation of the MareNostrum5 cluster at the Barcelona Supercomputing Center for CMS computing
No full textThe MareNostrum 5 (MN5) is the newly deployed pre-exascale EuroHPC supercomputer hosted at the Barcelona Supercomputing Center (BSC) in Spain. Its 750,000-core general-purpose CPU cluster offers new opportunities for CMS data processing and simulation but also presents integration challenges within the CMS distributed computing system, particularly due to network segregation for compute nodes. To address these constraints, innovative solutions previously implemented for its predecessor, MN4, have been redeployed, alongside new functionalities to support data-intensive workflows. The system's expanded shared disk storage and enhanced wide-area network connectivity facilitate efficient staging of input datasets, leveraging MN5's substantial CPU capacity. This contribution provides an overview of the commissioning efforts and the subsequent exploitation of MN5 for CMS