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CERN DG Fabiola Gianotti visit to Fermi National Accelerator Laboratory
No full textCERN DG Fabiola Gianotti looking at CMS HGCAL prototype parts during her visit to Fermi National Accelerator Laborator
ATLAS Event Display: Search for leptoquarks in lepton–proton collisions
No full textVisualisation of a candidate event in the signal region selecting a high-energetic electron-jet pair in a back-to-back topology using the Run-3 dataset. Charged-particle trajectories in the inner detector are shown as orange lines, and the yellow/orange and green/cyan boxes represent the energy deposited in the hadronic and electromagnetic calorimeters, respectively. The green line represents the reconstructed electron, while the yellow cone illustrates the jet with an invariant mass of the electron-jet system of about 2.9 TeV
Running ATLAS and CMS distributed computing on HPCs with fapptainer
No full textThe HEP communities have developed an increasing interest in High Performance Computing (HPC) centres, as these hold the potential of providing significant computing resources to the current and future experiments. At the Large Hadron Collider (LHC), the ATLAS and CMS experiments are challenged with a scale up of several factors in computing for the High-Luminosity LHC (HL-LHC) Run 4, currently foreseen to begin by 2030. HPC platforms are not homogeneous, they expose a wide variation of environments, including proprietary software stacks, each with its own set of restrictions. The access barrier for the integration with the highly dynamic needs of the running HEP experiments remains high, and ad hoc solutions are typically needed in order to make use of such centres. The development of a common approach providing efficient utilisation of compute resources by abstracting the specifics of a particular machine is thus highly desirable. This work presents an integration technique developed for running ATLAS and CMS experiment computational workloads on the LUMI Supercomputer, and designed to be HPC centre agnostic. It leverages the capabilities of open source tools like the Advanced Resource Connector (ARC) middleware, CernVM-FS (CVMFS), SSH Filesystem (SSHFS) and common containerisation techniques, enhancing them with novel tools to overcome limitations of the container runtime provided by the HPC. The fapptainer tool implements un-nesting of the containers, running them sideways instead, without any modification to the workflow of the jobs. The tools run unprivileged and as such do not require system modification by the local sysadmins. The proposed technique can be used to integrate any HPC system that has SSH inbound access and a standard container runtime available, and by means of an ARC Computing Element node close to it. A wide range of current and future HPC machines meets the specified requirements, thus enabling wider adoption of such tools by the HEP community to integrate HPC resources. The presented solution enables connecting HPC resources to HEP experiments distributed computing infrastructures as regular WLCG grid-sites and provides a generalised way of running computations independently of workload type and HPC environment specifics, using stock software components and a few in-house developed open-source tools. The tools presented are novel, and allow overcoming difficulties and limitations of the local HPC environments. They also operate in unprivileged fashion without requesting any modifications from the sysadmins
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Turbulence and Magnetic Reconnection in Relativistic Multispecies Plasmas
No full textSimulations of relativistic plasmas traditionally focus on the dynamics of two-species mixtures of charged particles under the influence of external magnetic fields and those generated by particle currents. However, the extreme conditions of astrophysical plasmas near compact objects, such as black holes and neutron stars, are often characterized by mixtures of electrons, protons, and positrons, whose dynamics can differ significantly, because of the considerable mass contrast. We present the first two-dimensional particle-in-cell simulations of relativistic turbulence and magnetic reconnection in a three-species plasma, varying the relative abundances of electrons, protons, and positrons, while employing realistic mass ratios to achieve unprecedented accuracy. We find that turbulence leads to the formation of magnetic islands, current sheets, and plasmoids. Reconnection occurs between these structures, with plasma composition playing a key role in determining the number of reconnection sites and their energy conversion efficiency. In particular, as the proton fraction increases, very small-scale features of the turbulence are washed out, while global dissipative effects are amplified. Finally, using a novel generalization of Ohm’s law for a relativistic multispecies plasma, we find that the reconnection rate is primarily governed by the electric fields associated with the divergence of the positron and electron pressure tensors. These results provide new insights into dissipation and particle acceleration in turbulent relativistic plasmas, such as those near black holes and neutron stars, and can be used to interpret their high-energy emission and phenomenology.Simulations of relativistic plasmas traditionally focus on the dynamics of two-species mixtures of charged particles under the influence of external magnetic fields and those generated by particle currents. However, the extreme conditions of astrophysical plasmas near compact objects such as black holes and neutron stars are often characterized by mixtures of electrons, protons, and positrons, whose dynamics can differ significantly because of the considerable mass contrast. We present the first two-dimensional particle-in-cell simulations of relativistic turbulence and magnetic reconnection in a three-species plasma, varying the relative abundance of electrons, protons, and positrons while employing realistic mass ratios to achieve unprecedented accuracy. We find that turbulence leads to the formation of magnetic islands, current sheets, and plasmoids. Reconnection occurs between these structures, with plasma composition playing a key role in determining the number of reconnection sites and their energy-conversion efficiency. In particular, as the proton fraction increases, very small-scale features of the turbulence are washed out, while global dissipative effects are amplified. Finally, using a novel generalization of Ohm's law for a relativistic multi-species plasma, we find that the reconnection rate is primarily governed by the electric fields associated to the divergence of the positron and electron pressure tensors. These results provide new insights into dissipation and particle acceleration in turbulent relativistic plasmas, such as those near black holes and neutron stars, and can be used to interpret their high-energy emission and phenomenology
ELDRS in a Commercial 28-nm CMOS Technology
No full textEvidence of enhanced low-dose-rate sensitivity (ELDRS) in total ionizing dose (TID)-induced leakage current increase was observed in ring oscillators (ROs) and static random access memories (SRAMs) in 28-nm CMOS technology exposed to ultrahigh doses. Elevated temperature irradiation on isolated devices is used to evaluate the dependence of ELDRS on bias conditions, device size, and threshold voltage. The results obtained show that irradiation at high temperatures can represent reasonably well ELDRS, providing a viable solution for accelerated radiation tests
