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Analysis of Measurements of the Magnetic Flux Density in Steel Blocks of the Compact Muon Solenoid Magnet Yoke with Solenoid Coil Fast Discharges
No full textThe general-purpose Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) at CERN is used to study the production of new particles in proton–proton collisions at an LHC center of mass energy of 13.6 TeV. The detector includes a magnet based on a 6 m diameter superconducting solenoid coil operating at a current of 18.164 kA. This current creates a central magnetic flux density of 3.8 T that allows for the high-precision measurement of the momenta of the produced charged particles using tracking and muon subdetectors. The CMS magnet contains a 10,000 ton flux-return yoke of dodecagonal shape made from the assembly of construction steel blocks distributed in several layers. These steel blocks are magnetized with the solenoid returned magnetic flux and wrap the muons escaping the hadronic calorimeters of total absorption. To reconstruct the muon trajectories, and thus to measure the muon momenta, the drift tube and cathode strip chambers are located between the layers of the steel blocks. To describe the distribution of the magnetic flux in the magnet yoke layers, a three-dimensional computer model of the CMS magnet is used. To validate the calculations, special measurements are performed, with the flux loops wound in 22 cross-sections of the flux-return yoke blocks. The measured voltages induced in the flux loops during the CMS magnet ramp-ups and -downs, as well as during the superconducting coil fast discharges, are integrated over time to obtain the initial magnetic flux densities in the flux loop cross-sections. The measurements obtained during the seven standard ramp-downs of the magnet were analyzed in 2018. From that time, three fast discharges occurred during the standard ramp-downs of the magnet. This allows us to single out the contributions of the eddy currents, induced in steel, to the flux loop voltages registered during the fast discharges of the coil. Accounting for these contributions to the flux loop measurements during intentionally triggered fast discharges in 2006 allows us to perform the validation of the CMS magnet computer model with better precision. The technique for the flux loop measurements and the obtained results are presented and discussed. The method for measuring magnetic flux density in steel blocks described in this study is innovative. The experience of 3D modeling and measuring the magnetic field in steel blocks of the magnet yoke, as part of a muon detector system, has good prospects for use in the construction and operation of particle detectors for the Future Circular Electron–Positron Collider and the Circular Electron–Positron Collider.The Compact Muon Solenoid (CMS) detector at the Large Hadron Collider at CERN is used to study the production of new particles in proton-proton collisions at a center of mass energy of 13.6 TeV. The detector includes a magnet based on a 6 m diameter superconducting coil operating at a current of 18.164 kA. This current creates a central magnetic flux density of 3.8 T that allows for the high-precision measurement of the momenta of the produced charged particles using tracking and muon subdetectors. The CMS magnet contains a 10,000 ton flux-return yoke made from the construction steel blocks. These blocks are magnetized, with the coil returned magnetic flux and wrap the muons escaping the hadronic calorimeters. To describe the distribution of the magnetic flux in the magnet yoke layers, a three-dimensional computer model of the CMS magnet is used. To validate the calculations, special measurements are performed, with the flux loops wound in 22 cross-sections of the flux-return yoke blocks. The measured voltages induced in the flux loops during the CMS magnet current variations, are integrated over time to obtain the initial magnetic flux densities in the flux loop cross-sections. In the last time, three fast discharges occurred during the standard ramp-downs of the magnet. This allows us to single out the contributions of the eddy currents, induced in steel, to the flux loop voltages. Accounting for these contributions to the flux loop measurements during intentionally triggered fast discharges in 2006 allows us to perform the validation of the CMS magnet computer model with better precision. The technique for the flux loop measurements and the obtained results are presented and discussed. The method for measuring magnetic flux density in steel blocks described in this study is innovative
Beyond the Standard Model in the Higgs sector
No full textThe discovery of the Higgs boson with the mass of about 125 GeV completed the particle content predicted by the Standard Model. Even though this model is well established and consistent with many measurements, it is not capable to solely explain some observations. Many extensions of the Standard Model addressing such shortcomings introduce additional Higgs bosons, beyond-the-Standard-Model couplings to the Higgs boson, or new particles decaying into Higgs bosons. In this talk, the latest searches in the Higgs sector by the ATLAS experiment are reported, with emphasis on the results obtained with the full LHC Run 2 dataset at 13 TeV
Design and Optimization of the ASACUSA1 Beam Transport Line
No full textThe document presents an analysis of beam transport optimization in the ASACUSA1 line at CERN. Initial attempts to model the beam optics using MAD-X proved unsatisfactory due to discrepancies between the model and observed beam behavior. A Python optimizer code was implemented, but significant losses persisted. A more realistic model was then developed using SIMPA, which accounts for the geometry of line elements and fringe fields. This resulted in a marked improvement in beam intensity and spot size reduction
QCD Scattering in the Regge Limit
No full textFixed-order computations of QCD amplitudes in general kinematics are limited to either one, two or three loops, depending on the number of particles produced. This strongly motivates our theoretical research programme aimed at understanding the behaviour of quark and gluon scattering amplitudes in special kinematic limits, in which new factorization and exponentiation properties arise. A particularly interesting limit is the Regge limit, where major simplifications take place. A remarkable and well-known property of this limit is the exponentiation of energy logarithms, a phenomenon known as gluon Reggeization, leading to power-like dependence on the energy (a Regge pole). This phenomenon and its breaking can be investigated using non-linear rapidity evolution equations. In the planar limit the evolution is consistent with a Regge pole to any logarithmic accuracy. However in full non-planar QCD multi-Reggeon interactions give rise to Regge cuts, in addition to the pole. Over the past decade an effective theory of multi-Reggeon interactions was developed, leading to a clear interpretation of state-of-the-art 2 → 2 and 2 → 3 QCD amplitude computations. Specifically, we are now able to fix all parameters associated with the Regge pole to the next-to-next-to-leading order (NNLO): the 3-loop trajectory, the 2-loop impact factors, and since recently, the two-loop Reggeon-gluon-Reggeon vertex. These, along with the effective multi-Reggeon theory, can be used to determine or resum higher-loop corrections in 2 → n scattering in the multi-Regge limit, and push BFKL theory to NNLO.</p
CERN PGDay 2025
No full textCERN, the European Organization for Nuclear Research, is at the forefront of scientific exploration, uncovering the fundamental nature of the universe. With groundbreaking experiments from worl-wide collaborations conducted at the Large Hadron Collider (LHC), the world’s largest and most powerful particle accelerator. The LHC hosts four main experiments: ATLAS and CMS, which investigate the fundamental particles and forces of the universe; ALICE, which studies the properties of quark-gluon plasma; and LHCb, which explores the differences between matter and antimatter. Through these experiments CERN generates petabytes of data that drive cutting-edge research in particle physics, pushing the boundaries of human knowledge. Supporting this ambitious mission requires a robust and scalable IT infrastructure to manage the vast and varied data demands of scientists and engineers across the globe.
Aiding this effort is the Database on Demand service, which provides reliable, scalable, and easy-to-use database solutions for CERN’s diverse community of users. This service enables researchers and engineers to rapidly create and manage databases without the need for extensive technical expertise, ensuring they can focus on their primary scientific objectives. It integrates seamlessly with CERN’s infrastructure, offering high performance, security, and flexibility to support a wide range of applications, from data analysis to operational tasks.
This brief keynote delves into the role of PostgreSQL in CERN’s Database on Demand service. PostgreSQL’s advanced features and open-source ethos align seamlessly with CERN’s collaborative and innovative spirit. It shows the importance of collaboration between scientific innovation and open-source technologies in driving discoveries that benefit humanity
Recent results on SM Higgs properties and rare decays in ATLAS
No full textWith the full Run 2 pp collision dataset collected at 13 TeV, very precise measurements of Higgs boson properties and its interactions can be performed, shedding light over the electroweak symmetry breaking mechanism. This talk presents measurements performed using the Run 2 dataset, as well as first results using the Run 3 pp collision dataset collected since 2022 at 13.6 TeV. Measurements of the Higgs boson properties by the ATLAS experiment in various decay channels are shown, including its production cross sections, simplified template cross sections, mass, width, CP quantum number, differential and fiducial cross sections, as well as their combination and interpretations. Specific scenarios of physics beyond the Standard Model are tested, as well as a generic extension in the framework of the Standard Model Effective Field Theory. The talk also presents the latest HH searches, which are sensitive to the Higgs boson self-coupling. Results are shown in terms of sensitivity to the SM HH production and limits on the Higgs boson self-coupling
Improvement of the timing calibration in the CMS-PPS timing detectors
No full textThe Precision Proton Spectrometer (PPS) is a near-beam subdetector of the Compact Muon Solenoid (CMS) experiment used for detecting forward protons. It comprises tracking and timing detectors located around 220 meters from the CMS detector. Due to their challenging operating environment, they require persistent calibration. Procedures for performing it have already been developed for Run 2 of the Large Hadron Collider (LHC) but for the LHC Run 3 the timing detector calibration algorithm has been shown not to perform ideally for most of the data-taking runs due to data anomalies and irregularities. Moreover, calibrating so many runs every year has been proven to be a mundane task. As a result, an in-house parallel processing automation framework has been developed to perform the calibration and validate its results. This framework has been built on top of industry-grade technologies such as Grafana or Jenkins. This note will focus on showing an improved timing calibration algorithm, as well as anomalies and irregularities which were observed and corrected by it