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TeraAgent: A Distributed Agent-Based Simulation Engine for Simulating Half a Trillion Agents
No full textAgent-based simulation is an indispensable paradigm for studying complex systems. These systems can comprise billions of agents, requiring the computing resources of multiple servers to simulate. Unfortunately, the state-of-the-art platform, BioDynaMo, does not scale out across servers due to its shared-memory-based implementation. To overcome this key limitation, we introduce TeraAgent, a distributed agent-based simulation engine. A critical challenge in distributed execution is the exchange of agent information across servers, which we identify as a major performance bottleneck. We propose two solutions: 1) a tailored serialization mechanism that allows agents to be accessed and mutated directly from the receive buffer, and 2) leveraging the iterative nature of agent-based simulations to reduce data transfer with delta encoding. Built on our solutions, TeraAgent enables extreme-scale simulations with half a trillion agents (an 84x improvement), reduces time-to-result with additional compute nodes, improves interoperability with third-party tools, and provides users with more hardware flexibility
Preliminary findings and recommendations from the Token Trust and Traceability Working Group
No full textCreated in 2023, the Token Trust and Traceability Working Group (TTT) was formed in order to answer questions of policy and best practice with the ongoing move from X.509 and VOMS proxy certificates to token-based solutions as the primary authorisation and authentication method in distributed computing environments. With a remit to act in an investigatory and advisory capacity alongside other working groups in the token space, the TTT is composed of a broad variety of stakeholders to provide a breadth of experience and viewpoints. While the requirements of grid sites, users, identity providers and virtual organisations to be able to trace workflows have remained largely the same in a token paradigm as to one using X.509 certificates, tokens provide a new set of challenges, requiring a rethink and restructure of the policies and processes that were defined with just X.509 and VOMS in mind, in order to meet these requirements in the new context. After providing an overview of the current status of the token trust landscape we will detail the initial findings, future plans and recommendations to be made by the TTT. This will include best practice for sites and identity providers, suggestions for token development, and methodologies for tracing token usage by system administrators within common grid middleware stacks
Measurements of jet cross-section ratios with ATLAS
No full textJet cross-section ratios between inclusive bins of jet multiplicity are measured differentially in variables that are sensitive to either the energy-scale or angular distribution of hadronic energy flow in the final state. Several improvements to the calibration of jets are described, which result in significant improvements in the overall jet energy scale uncertainty. The measurements are compared to state-of-the-art NLO and NNLO predictions, and could be used to determine the strong-coupling constant at the reference scale of the Z-boson mass and its running up to high energies
SSRPM annual meeting at CERN
No full textPhotos of few keynote speakers, room, attendance, crowd at CERN during coffee breaks or lunch depending on your availability. Camera pictures only
Search for single production of a vector-like T quark decaying to a top quark and a neutral scalar boson in the lepton+jets final state in proton-proton collisions at 13 TeV
No full textA search for single production of a vector-like T quark with charge 2/3, decaying to a top quark and a neutral scalar boson is presented. The boson can be a standard model Higgs boson (H) or a new scalar boson (). In the first case, a branching fraction of 25% is assumed for the decay , while in the second case the T quark is assumed to decay exclusively to . The top quark is identified via its lepton+jets decay, and the neutral boson via its decay into a bottom quark-antiquark pair. Final states with Lorentz-boosted topologies are considered and machine-learning techniques are exploited for optimal event classification. The analysis uses data collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb recorded at the CERN LHC in 2016-2018. Upper limits at 95% confidence level are set on the product of cross section and branching fraction for a T quark in a narrow-width approximation. They vary between 14.8 and 0.1 fb, for T quark masses in the range 1-3 TeV and boson masses in the range 25-250 GeV. These are the first exclusion limits set on the production of a single T quark decaying into a top quark and a new neutral scalar boson. For the decay channel into a top quark and a standard model Higgs boson, the results provide the best limits on production cross sections to date, for T quark masses above 2 TeV.A search for single production of a vector-like T quark with charge 2/3, decaying to a top quark and a neutral scalar boson is presented. The boson can be a standard model Higgs boson (H) or a new scalar boson (). In the first case, a branching fraction of 25% is assumed for the decay T tH, while in the second case the T quark is assumed to decay exclusively to t. The top quark is identified via its lepton+jets decay, and the neutral boson via its decay into a bottom quark-antiquark pair. Final states with Lorentz-boosted topologies are considered and machine-learning techniques are exploited for optimal event classification. The analysis uses data collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb recorded at the CERN LHC in 20162018. Upper limits at 95% confidence level are set on the product of cross section and branching fraction for a T quark in a narrow-width approximation. They vary between 14.8 and 0.1 fb, for T quark masses in the range 13 TeV and boson masses in the range 25250 GeV. These are the first exclusion limits set on the production of a single T quark decaying into a top quark and a new neutral scalar boson. For the decay channel into a top quark and a standard model Higgs boson, the results provide the best limits on production cross sections to date, for T quark masses above 2 TeV
High efficiency veto hadron calorimeter in the NA64 experiment at CERN
No full textThe NA64 is a fixed-target experiment at the CERN SPS designed to search for Light particle Dark Matter (LDM) candidates with masses in the sub-GeV range. During the 2016-2022 runs, the experiment obtained the world-leading constraints, leaving however part of the well-motivated region of parameter space suggested by benchmark LDM models still unexplored. To further improve sensitivity, as part of the upgrades to the setup of NA64 at the CERN SPS H4 beamline, a prototype veto hadron calorimeter (VHCAL) was installed in the downstream region of the experiment during the 2023 run. The VHCAL, made of Cu-Sc layers, was expected to be an efficient veto against upstream electroproduction of large-angle hadrons or photon-nuclear interactions, reducing the background from secondary particles escaping the detector acceptance. With the collected statistics of 4.4×10^11 electrons on target (EOT), we demonstrate the effectiveness of this approach by rejecting this background by more than an order of magnitude. This result provides an essential input for designing a full-scale optimized VHCAL to continue running background-free during LHC Run 4, when we expect to collect 10^13 EOT. Furthermore, this technique combined with improvements in the analysis enables us to decrease our missing energy threshold from 50 GeV to 40 GeV thereby enhancing the signal sensitivity of NA64
Opracowanie w oprogramowaniu WinCC O.A. systemu SCADA (ang. Supervisory Control And Data Acquisition) do obsługi stacji laboratoryjnej poddetektorów FIT (ang. Fast Interaction Trigger) w eksperymencie ALICE (ang. A Large Ion Collider Experiment)
No full textThe subject of this thesis was the development of a Supervisory Control And Data Acquisition (SCADA) system in SIMATIC WinCC Open Architecture Version 3.19 (WinCC OA) for the operation of the laboratory station of The Fast Interaction Trigger (FIT) subdetectors in A Large Ion Collider Experiment. A Large Ion Collider Experiment (ALICE) is one of the major experiments conducted at the Large Hadron Collider within the European Organization for Nuclear Research (CERN) in Geneva. Its primary objective is to investigate the properties of a state of matter known as quarkgluon plasma, which according to current scientific knowledge is believed to have existed fractions of a second after the Big Bang. The FIT subdetector system is a key component of the experiment comprising three detector systems FT0, FV0, and FDD grouped into five modules. These detectors provide information to less dynamic detectors in the experiment regarding the occurrence of collisions, determine the interaction plane, and assess collision centrality. The development work was carried out at CERN in collaboration with the Faculty of Electrical Engineering and the Faculty of Physics of the Warsaw University of Technology during July and August 2024. The author of this thesis contributed to the development of a new control structure for the FIT subdetector system and served as an oncall expert. The scope of tasks included modernizing the original software controlling the subdetector system which did not meet the standards required for the experiment. As a result a compliant structure was developed including the SCADA application created by the author and described in this thesis enabling complete control over the new system. During the system’s development the CERN Joint Controls Project Framework (JCOP) was implemented into the WinCC OA application allowing communication with lower system layers via the Distributed Information Management (DIM) protocol. The structure of transmitted data frames was defined and a script was prepared for their import into WinCC enabling integration with the internal database. The final stage involved designing and programming a user interface for managing the Front-end Electronics (FEE) modules the Processing Module (PM) and the Trigger and Clock Module (TCM). The first implementation of the developed system was at the detector simulation station in the FIT laboratory which allows for training on-call experts. Each detector in the experiment has an on-call expert assigned around the clock who resolves issues by connecting to the control system in case of a malfunction. The previous software structure did not allow for error generation under simulated conditions which prevented practical training for future experts in troubleshooting. The developed system is ultimately intended for implementation in the control of the FIT in the real ALICE experiment
Measurement of the W boson properties in the forward region in pp collisions at TeV
No full textThis thesis primarily presents a detailed study of the fiducial cross--sections for and boson production at TeV, using data from the LHCb experiment at the Large Hadron Collider at CERN. The dataset corresponds to an integrated luminosity of , recorded during 2017. The research focusses on muonic decays of W bosons. The cross--sections are measured differentially in intervals of the muon transverse momentum between 25 and 55 GeV, with the pseudorapidity ranging from 2.2 to 2.4. Integrated over this 2D fiducial sub--volume, the cross--sections are measured to be: \begin{align*} \sigma_{W^+ \to \mu^+ \nu} &= 301.62 \pm 3.00 \pm 3.74 \pm 6.03 \ \text{pb}, \\ \sigma_{W^- \to \mu^- \bar{\nu}_\mu} &= 237.80 \pm 2.72 \pm 2.67 \pm 4.76 \ \text{pb}, \end{align*} where the first uncertainty is statistical, the second systematic, and the third is attributed to the luminosity determination. A fit to the differential cross--sections yields the following determination of the \W boson mass: \begin{align*} m_W = 80355 \pm 128 \pm 21 \ \text{MeV}, \end{align*} where the first error is experimental (statistical and systematic errors combined) and the second error is theory systematic errors for measuring . It is important to note that the result is currently blinded, and the analysis is in internal review within the international LHCb collaboration. This analysis serves as a proof--of--principle for determining the W boson mass with intermediate measurements of the differential cross--sections in intervals of the muon transverse momentum. The method of investigation involves novel techniques to extract the W boson mass using differential cross--sections in bins of transverse momentum. By eventually applying this approach to the full Run 2 dataset at = 13 TeV, we expect a precision of around 15 MeV, which would be a competitive measurement that enriches the findings of ATLAS and CMS. Furthermore, the thesis covers the author’s role in the Real--Time Analysis (RTA) project at the LHCb experiment. This involves developing data processing software and optimising workflows for the Run 3 data collection phase