International Linear Collider
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Simultaneous cross section measurements of top quark-antiquark pair production with additional heavy flavor jets at the CMS experiment
No full textThis thesis presents a simultaneous cross section measurement of top quark-antiquark pair () production in association with b jets, c jets, a Higgs boson, or a Z boson in the decay mode with exactly two charged leptons (e,), targeting the dilepton decay channel. The measurement is performed at the CMS experiment at the CERN LHC in proton-proton collisions at a center-of-mass energy of and the analyzed data corresponds to an integrated luminosity of approximately . Collision events are modeled as a mathematical graph structure and processed using graph transformer neural network architectures based on multi-head attention mechanisms to perform multi-class classification. The measured cross sections are parameterized as signal strength parameters relative to the cross sections predicted by the SM. Four signal strength parameters are simultaneously extracted in a maximum likelihood fit to data and result to , , , and , corresponding to an observed (expected) significance of () for , () for , () for , and () for compared to the SM prediction without these processes. The results reveal a good agreement with the SM expectation for the signal strength of one within the 68% confidence interval
Q2 and corrector package cryostats freshly painted
No full textQ2 and corrector package cryostats for the HL-LHC were recently painted to show their respective collaboration logos and flags, ready for the cryostatting phase
Software Upgrades for the High-Luminosity LHC
No full textThe High Luminosity upgrade of the LHC (HL-LHC) presents a fresh set of challenges that will need to be overcome in order to fully utilize the prodigious amount of data set to be collected throughout the course of its operation. These proceedings provide an overview of the various ongoing efforts to prepare the software of the ALICE, ATLAS, CMS, and LHCb collaborations for this exciting new era of research. Center stage to these developments are the topics of accelerator technologies and machine learning algorithms, both of which have seen a tremendous amount of activity and progress in recent years. Cross-experiment R\&D; projects are also highlighted, in addition to software that must be written for new sub-detectors as well as for the support of legacy data
AD-7/GBAR status report for the 2025 CERN SPSC
No full textWe report on the activities performed during 2024 and the plans for 2025 for the GBAR experiment. Highlights include record positron accumulation and an order-of-magnitude increase in antihydrogen production, with several publications in preparation
Evaluating the Electro-Magnetic Effects of Electrical Short-Circuits in a Nb-Ti Accelerator Magnet
No full textElectrical short-circuits in the coil winding pack of a superconducting magnet can severely impact the magnet's performance and safety during operation. Hence, finding ways to detect and assess these non-conformities is essential. Measurements of the complex impedance as a function of the frequency are a promising method to investigate such non-conformities more closely. The complex impedance of one HL-LHC recombination dipole magnet was recently measured at the CERN magnet test facility. Moreover, to mimic an inter-turn short in the coils, resistances at warm were connected externally to the voltage taps and the complex impedance of the magnet was measured. The acquired measurements are used to validate a developed lumped-element network model, reproducing the electromagnetic behaviour of the HL-LHC recombination dipole magnet in the frequency domain. The simulation results are compared to the measurements without artificial short circuits and are in good agreement up to a frequency of 10 kHz. The simulated effects of short circuits across a few turns in the frequency domain are compared to the measurements performed on the magnet. Since good agreement between measurements and simulations was obtained, these models can be used to predict the electromagnetic effects of any inter-turn short in the HL-LHC recombination dipole magnet or similar types of accelerator magnets
